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linux-next/security/tomoyo/tomoyo.c

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 22:07:57 +08:00
// SPDX-License-Identifier: GPL-2.0
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
/*
* security/tomoyo/tomoyo.c
*
* Copyright (C) 2005-2011 NTT DATA CORPORATION
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
*/
#include <linux/lsm_hooks.h>
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
#include "common.h"
/**
* tomoyo_domain - Get "struct tomoyo_domain_info" for current thread.
*
* Returns pointer to "struct tomoyo_domain_info" for current thread.
*/
struct tomoyo_domain_info *tomoyo_domain(void)
KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] Add a keyctl to install a process's session keyring onto its parent. This replaces the parent's session keyring. Because the COW credential code does not permit one process to change another process's credentials directly, the change is deferred until userspace next starts executing again. Normally this will be after a wait*() syscall. To support this, three new security hooks have been provided: cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in the blank security creds and key_session_to_parent() - which asks the LSM if the process may replace its parent's session keyring. The replacement may only happen if the process has the same ownership details as its parent, and the process has LINK permission on the session keyring, and the session keyring is owned by the process, and the LSM permits it. Note that this requires alteration to each architecture's notify_resume path. This has been done for all arches barring blackfin, m68k* and xtensa, all of which need assembly alteration to support TIF_NOTIFY_RESUME. This allows the replacement to be performed at the point the parent process resumes userspace execution. This allows the userspace AFS pioctl emulation to fully emulate newpag() and the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to alter the parent process's PAG membership. However, since kAFS doesn't use PAGs per se, but rather dumps the keys into the session keyring, the session keyring of the parent must be replaced if, for example, VIOCSETTOK is passed the newpag flag. This can be tested with the following program: #include <stdio.h> #include <stdlib.h> #include <keyutils.h> #define KEYCTL_SESSION_TO_PARENT 18 #define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0) int main(int argc, char **argv) { key_serial_t keyring, key; long ret; keyring = keyctl_join_session_keyring(argv[1]); OSERROR(keyring, "keyctl_join_session_keyring"); key = add_key("user", "a", "b", 1, keyring); OSERROR(key, "add_key"); ret = keyctl(KEYCTL_SESSION_TO_PARENT); OSERROR(ret, "KEYCTL_SESSION_TO_PARENT"); return 0; } Compiled and linked with -lkeyutils, you should see something like: [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 355907932 --alswrv 4043 -1 \_ keyring: _uid.4043 [dhowells@andromeda ~]$ /tmp/newpag [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 1055658746 --alswrv 4043 4043 \_ user: a [dhowells@andromeda ~]$ /tmp/newpag hello [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: hello 340417692 --alswrv 4043 4043 \_ user: a Where the test program creates a new session keyring, sticks a user key named 'a' into it and then installs it on its parent. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-09-02 16:14:21 +08:00
{
struct tomoyo_task *s = tomoyo_task(current);
if (s->old_domain_info && !current->in_execve) {
atomic_dec(&s->old_domain_info->users);
s->old_domain_info = NULL;
}
return s->domain_info;
KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] Add a keyctl to install a process's session keyring onto its parent. This replaces the parent's session keyring. Because the COW credential code does not permit one process to change another process's credentials directly, the change is deferred until userspace next starts executing again. Normally this will be after a wait*() syscall. To support this, three new security hooks have been provided: cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in the blank security creds and key_session_to_parent() - which asks the LSM if the process may replace its parent's session keyring. The replacement may only happen if the process has the same ownership details as its parent, and the process has LINK permission on the session keyring, and the session keyring is owned by the process, and the LSM permits it. Note that this requires alteration to each architecture's notify_resume path. This has been done for all arches barring blackfin, m68k* and xtensa, all of which need assembly alteration to support TIF_NOTIFY_RESUME. This allows the replacement to be performed at the point the parent process resumes userspace execution. This allows the userspace AFS pioctl emulation to fully emulate newpag() and the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to alter the parent process's PAG membership. However, since kAFS doesn't use PAGs per se, but rather dumps the keys into the session keyring, the session keyring of the parent must be replaced if, for example, VIOCSETTOK is passed the newpag flag. This can be tested with the following program: #include <stdio.h> #include <stdlib.h> #include <keyutils.h> #define KEYCTL_SESSION_TO_PARENT 18 #define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0) int main(int argc, char **argv) { key_serial_t keyring, key; long ret; keyring = keyctl_join_session_keyring(argv[1]); OSERROR(keyring, "keyctl_join_session_keyring"); key = add_key("user", "a", "b", 1, keyring); OSERROR(key, "add_key"); ret = keyctl(KEYCTL_SESSION_TO_PARENT); OSERROR(ret, "KEYCTL_SESSION_TO_PARENT"); return 0; } Compiled and linked with -lkeyutils, you should see something like: [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 355907932 --alswrv 4043 -1 \_ keyring: _uid.4043 [dhowells@andromeda ~]$ /tmp/newpag [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 1055658746 --alswrv 4043 4043 \_ user: a [dhowells@andromeda ~]$ /tmp/newpag hello [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: hello 340417692 --alswrv 4043 4043 \_ user: a Where the test program creates a new session keyring, sticks a user key named 'a' into it and then installs it on its parent. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-09-02 16:14:21 +08:00
}
/**
* tomoyo_cred_prepare - Target for security_prepare_creds().
*
* @new: Pointer to "struct cred".
* @old: Pointer to "struct cred".
* @gfp: Memory allocation flags.
*
* Returns 0.
*/
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
static int tomoyo_cred_prepare(struct cred *new, const struct cred *old,
gfp_t gfp)
{
/* Restore old_domain_info saved by previous execve() request. */
struct tomoyo_task *s = tomoyo_task(current);
if (s->old_domain_info && !current->in_execve) {
atomic_dec(&s->domain_info->users);
s->domain_info = s->old_domain_info;
s->old_domain_info = NULL;
}
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
return 0;
}
/**
* tomoyo_bprm_committed_creds - Target for security_bprm_committed_creds().
*
* @bprm: Pointer to "struct linux_binprm".
*/
static void tomoyo_bprm_committed_creds(struct linux_binprm *bprm)
{
/* Clear old_domain_info saved by execve() request. */
struct tomoyo_task *s = tomoyo_task(current);
atomic_dec(&s->old_domain_info->users);
s->old_domain_info = NULL;
KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] Add a keyctl to install a process's session keyring onto its parent. This replaces the parent's session keyring. Because the COW credential code does not permit one process to change another process's credentials directly, the change is deferred until userspace next starts executing again. Normally this will be after a wait*() syscall. To support this, three new security hooks have been provided: cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in the blank security creds and key_session_to_parent() - which asks the LSM if the process may replace its parent's session keyring. The replacement may only happen if the process has the same ownership details as its parent, and the process has LINK permission on the session keyring, and the session keyring is owned by the process, and the LSM permits it. Note that this requires alteration to each architecture's notify_resume path. This has been done for all arches barring blackfin, m68k* and xtensa, all of which need assembly alteration to support TIF_NOTIFY_RESUME. This allows the replacement to be performed at the point the parent process resumes userspace execution. This allows the userspace AFS pioctl emulation to fully emulate newpag() and the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to alter the parent process's PAG membership. However, since kAFS doesn't use PAGs per se, but rather dumps the keys into the session keyring, the session keyring of the parent must be replaced if, for example, VIOCSETTOK is passed the newpag flag. This can be tested with the following program: #include <stdio.h> #include <stdlib.h> #include <keyutils.h> #define KEYCTL_SESSION_TO_PARENT 18 #define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0) int main(int argc, char **argv) { key_serial_t keyring, key; long ret; keyring = keyctl_join_session_keyring(argv[1]); OSERROR(keyring, "keyctl_join_session_keyring"); key = add_key("user", "a", "b", 1, keyring); OSERROR(key, "add_key"); ret = keyctl(KEYCTL_SESSION_TO_PARENT); OSERROR(ret, "KEYCTL_SESSION_TO_PARENT"); return 0; } Compiled and linked with -lkeyutils, you should see something like: [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 355907932 --alswrv 4043 -1 \_ keyring: _uid.4043 [dhowells@andromeda ~]$ /tmp/newpag [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 1055658746 --alswrv 4043 4043 \_ user: a [dhowells@andromeda ~]$ /tmp/newpag hello [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: hello 340417692 --alswrv 4043 4043 \_ user: a Where the test program creates a new session keyring, sticks a user key named 'a' into it and then installs it on its parent. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-09-02 16:14:21 +08:00
}
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
/**
* tomoyo_bprm_for_exec - Target for security_bprm_creds_for_exec().
*
* @bprm: Pointer to "struct linux_binprm".
*
* Returns 0.
*/
static int tomoyo_bprm_creds_for_exec(struct linux_binprm *bprm)
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
{
/*
* Load policy if /sbin/tomoyo-init exists and /sbin/init is requested
* for the first time.
*/
if (!tomoyo_policy_loaded)
tomoyo_load_policy(bprm->filename);
return 0;
}
#endif
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
/**
* tomoyo_bprm_check_security - Target for security_bprm_check().
*
* @bprm: Pointer to "struct linux_binprm".
*
* Returns 0 on success, negative value otherwise.
*/
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
static int tomoyo_bprm_check_security(struct linux_binprm *bprm)
{
struct tomoyo_task *s = tomoyo_task(current);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
/*
* Execute permission is checked against pathname passed to execve()
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
* using current domain.
*/
if (!s->old_domain_info) {
const int idx = tomoyo_read_lock();
const int err = tomoyo_find_next_domain(bprm);
tomoyo_read_unlock(idx);
return err;
}
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
/*
* Read permission is checked against interpreters using next domain.
*/
return tomoyo_check_open_permission(s->domain_info,
&bprm->file->f_path, O_RDONLY);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_inode_getattr - Target for security_inode_getattr().
*
* @mnt: Pointer to "struct vfsmount".
* @dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_inode_getattr(const struct path *path)
{
return tomoyo_path_perm(TOMOYO_TYPE_GETATTR, path, NULL);
}
/**
* tomoyo_path_truncate - Target for security_path_truncate().
*
* @path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_truncate(const struct path *path)
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
{
return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_path_unlink - Target for security_path_unlink().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_unlink(const struct path *parent, struct dentry *dentry)
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_perm(TOMOYO_TYPE_UNLINK, &path, NULL);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_path_mkdir - Target for security_path_mkdir().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
* @mode: DAC permission mode.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_mkdir(const struct path *parent, struct dentry *dentry,
umode_t mode)
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_number_perm(TOMOYO_TYPE_MKDIR, &path,
mode & S_IALLUGO);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_path_rmdir - Target for security_path_rmdir().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_rmdir(const struct path *parent, struct dentry *dentry)
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_perm(TOMOYO_TYPE_RMDIR, &path, NULL);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_path_symlink - Target for security_path_symlink().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
* @old_name: Symlink's content.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_symlink(const struct path *parent, struct dentry *dentry,
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
const char *old_name)
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
return tomoyo_path_perm(TOMOYO_TYPE_SYMLINK, &path, old_name);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_path_mknod - Target for security_path_mknod().
*
* @parent: Pointer to "struct path".
* @dentry: Pointer to "struct dentry".
* @mode: DAC permission mode.
* @dev: Device attributes.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_mknod(const struct path *parent, struct dentry *dentry,
umode_t mode, unsigned int dev)
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
{
struct path path = { .mnt = parent->mnt, .dentry = dentry };
int type = TOMOYO_TYPE_CREATE;
const unsigned int perm = mode & S_IALLUGO;
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
switch (mode & S_IFMT) {
case S_IFCHR:
type = TOMOYO_TYPE_MKCHAR;
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
break;
case S_IFBLK:
type = TOMOYO_TYPE_MKBLOCK;
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
break;
default:
goto no_dev;
}
return tomoyo_mkdev_perm(type, &path, perm, dev);
no_dev:
switch (mode & S_IFMT) {
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
case S_IFIFO:
type = TOMOYO_TYPE_MKFIFO;
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
break;
case S_IFSOCK:
type = TOMOYO_TYPE_MKSOCK;
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
break;
}
return tomoyo_path_number_perm(type, &path, perm);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_path_link - Target for security_path_link().
*
* @old_dentry: Pointer to "struct dentry".
* @new_dir: Pointer to "struct path".
* @new_dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_link(struct dentry *old_dentry, const struct path *new_dir,
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
struct dentry *new_dentry)
{
struct path path1 = { .mnt = new_dir->mnt, .dentry = old_dentry };
struct path path2 = { .mnt = new_dir->mnt, .dentry = new_dentry };
return tomoyo_path2_perm(TOMOYO_TYPE_LINK, &path1, &path2);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_path_rename - Target for security_path_rename().
*
* @old_parent: Pointer to "struct path".
* @old_dentry: Pointer to "struct dentry".
* @new_parent: Pointer to "struct path".
* @new_dentry: Pointer to "struct dentry".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_rename(const struct path *old_parent,
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
struct dentry *old_dentry,
const struct path *new_parent,
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
struct dentry *new_dentry)
{
struct path path1 = { .mnt = old_parent->mnt, .dentry = old_dentry };
struct path path2 = { .mnt = new_parent->mnt, .dentry = new_dentry };
return tomoyo_path2_perm(TOMOYO_TYPE_RENAME, &path1, &path2);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_file_fcntl - Target for security_file_fcntl().
*
* @file: Pointer to "struct file".
* @cmd: Command for fcntl().
* @arg: Argument for @cmd.
*
* Returns 0 on success, negative value otherwise.
*/
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
static int tomoyo_file_fcntl(struct file *file, unsigned int cmd,
unsigned long arg)
{
if (!(cmd == F_SETFL && ((arg ^ file->f_flags) & O_APPEND)))
return 0;
return tomoyo_check_open_permission(tomoyo_domain(), &file->f_path,
O_WRONLY | (arg & O_APPEND));
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_file_open - Target for security_file_open().
*
* @f: Pointer to "struct file".
* @cred: Pointer to "struct cred".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_file_open(struct file *f)
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
{
/* Don't check read permission here if called from execve(). */
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
if (current->in_execve)
return 0;
return tomoyo_check_open_permission(tomoyo_domain(), &f->f_path,
f->f_flags);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
}
/**
* tomoyo_file_ioctl - Target for security_file_ioctl().
*
* @file: Pointer to "struct file".
* @cmd: Command for ioctl().
* @arg: Argument for @cmd.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_file_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
return tomoyo_path_number_perm(TOMOYO_TYPE_IOCTL, &file->f_path, cmd);
}
/**
* tomoyo_path_chmod - Target for security_path_chmod().
*
* @path: Pointer to "struct path".
* @mode: DAC permission mode.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_chmod(const struct path *path, umode_t mode)
{
return tomoyo_path_number_perm(TOMOYO_TYPE_CHMOD, path,
mode & S_IALLUGO);
}
/**
* tomoyo_path_chown - Target for security_path_chown().
*
* @path: Pointer to "struct path".
* @uid: Owner ID.
* @gid: Group ID.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_chown(const struct path *path, kuid_t uid, kgid_t gid)
{
int error = 0;
if (uid_valid(uid))
error = tomoyo_path_number_perm(TOMOYO_TYPE_CHOWN, path,
from_kuid(&init_user_ns, uid));
if (!error && gid_valid(gid))
error = tomoyo_path_number_perm(TOMOYO_TYPE_CHGRP, path,
from_kgid(&init_user_ns, gid));
return error;
}
/**
* tomoyo_path_chroot - Target for security_path_chroot().
*
* @path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_path_chroot(const struct path *path)
{
return tomoyo_path_perm(TOMOYO_TYPE_CHROOT, path, NULL);
}
/**
* tomoyo_sb_mount - Target for security_sb_mount().
*
* @dev_name: Name of device file. Maybe NULL.
* @path: Pointer to "struct path".
* @type: Name of filesystem type. Maybe NULL.
* @flags: Mount options.
* @data: Optional data. Maybe NULL.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_sb_mount(const char *dev_name, const struct path *path,
const char *type, unsigned long flags, void *data)
{
return tomoyo_mount_permission(dev_name, path, type, flags, data);
}
/**
* tomoyo_sb_umount - Target for security_sb_umount().
*
* @mnt: Pointer to "struct vfsmount".
* @flags: Unmount options.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_sb_umount(struct vfsmount *mnt, int flags)
{
struct path path = { .mnt = mnt, .dentry = mnt->mnt_root };
return tomoyo_path_perm(TOMOYO_TYPE_UMOUNT, &path, NULL);
}
/**
* tomoyo_sb_pivotroot - Target for security_sb_pivotroot().
*
* @old_path: Pointer to "struct path".
* @new_path: Pointer to "struct path".
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_sb_pivotroot(const struct path *old_path, const struct path *new_path)
{
return tomoyo_path2_perm(TOMOYO_TYPE_PIVOT_ROOT, new_path, old_path);
}
/**
* tomoyo_socket_listen - Check permission for listen().
*
* @sock: Pointer to "struct socket".
* @backlog: Backlog parameter.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_listen(struct socket *sock, int backlog)
{
return tomoyo_socket_listen_permission(sock);
}
/**
* tomoyo_socket_connect - Check permission for connect().
*
* @sock: Pointer to "struct socket".
* @addr: Pointer to "struct sockaddr".
* @addr_len: Size of @addr.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_connect(struct socket *sock, struct sockaddr *addr,
int addr_len)
{
return tomoyo_socket_connect_permission(sock, addr, addr_len);
}
/**
* tomoyo_socket_bind - Check permission for bind().
*
* @sock: Pointer to "struct socket".
* @addr: Pointer to "struct sockaddr".
* @addr_len: Size of @addr.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_bind(struct socket *sock, struct sockaddr *addr,
int addr_len)
{
return tomoyo_socket_bind_permission(sock, addr, addr_len);
}
/**
* tomoyo_socket_sendmsg - Check permission for sendmsg().
*
* @sock: Pointer to "struct socket".
* @msg: Pointer to "struct msghdr".
* @size: Size of message.
*
* Returns 0 on success, negative value otherwise.
*/
static int tomoyo_socket_sendmsg(struct socket *sock, struct msghdr *msg,
int size)
{
return tomoyo_socket_sendmsg_permission(sock, msg, size);
}
struct lsm_blob_sizes tomoyo_blob_sizes __lsm_ro_after_init = {
.lbs_task = sizeof(struct tomoyo_task),
};
/**
* tomoyo_task_alloc - Target for security_task_alloc().
*
* @task: Pointer to "struct task_struct".
* @flags: clone() flags.
*
* Returns 0.
*/
static int tomoyo_task_alloc(struct task_struct *task,
unsigned long clone_flags)
{
struct tomoyo_task *old = tomoyo_task(current);
struct tomoyo_task *new = tomoyo_task(task);
new->domain_info = old->domain_info;
atomic_inc(&new->domain_info->users);
new->old_domain_info = NULL;
return 0;
}
/**
* tomoyo_task_free - Target for security_task_free().
*
* @task: Pointer to "struct task_struct".
*/
static void tomoyo_task_free(struct task_struct *task)
{
struct tomoyo_task *s = tomoyo_task(task);
if (s->domain_info) {
atomic_dec(&s->domain_info->users);
s->domain_info = NULL;
}
if (s->old_domain_info) {
atomic_dec(&s->old_domain_info->users);
s->old_domain_info = NULL;
}
}
/*
* tomoyo_security_ops is a "struct security_operations" which is used for
* registering TOMOYO.
*/
static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(cred_prepare, tomoyo_cred_prepare),
LSM_HOOK_INIT(bprm_committed_creds, tomoyo_bprm_committed_creds),
LSM_HOOK_INIT(task_alloc, tomoyo_task_alloc),
LSM_HOOK_INIT(task_free, tomoyo_task_free),
#ifndef CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER
LSM_HOOK_INIT(bprm_creds_for_exec, tomoyo_bprm_creds_for_exec),
#endif
LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security),
LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl),
LSM_HOOK_INIT(file_open, tomoyo_file_open),
LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate),
LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink),
LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),
LSM_HOOK_INIT(path_rmdir, tomoyo_path_rmdir),
LSM_HOOK_INIT(path_symlink, tomoyo_path_symlink),
LSM_HOOK_INIT(path_mknod, tomoyo_path_mknod),
LSM_HOOK_INIT(path_link, tomoyo_path_link),
LSM_HOOK_INIT(path_rename, tomoyo_path_rename),
LSM_HOOK_INIT(inode_getattr, tomoyo_inode_getattr),
LSM_HOOK_INIT(file_ioctl, tomoyo_file_ioctl),
LSM_HOOK_INIT(path_chmod, tomoyo_path_chmod),
LSM_HOOK_INIT(path_chown, tomoyo_path_chown),
LSM_HOOK_INIT(path_chroot, tomoyo_path_chroot),
LSM_HOOK_INIT(sb_mount, tomoyo_sb_mount),
LSM_HOOK_INIT(sb_umount, tomoyo_sb_umount),
LSM_HOOK_INIT(sb_pivotroot, tomoyo_sb_pivotroot),
LSM_HOOK_INIT(socket_bind, tomoyo_socket_bind),
LSM_HOOK_INIT(socket_connect, tomoyo_socket_connect),
LSM_HOOK_INIT(socket_listen, tomoyo_socket_listen),
LSM_HOOK_INIT(socket_sendmsg, tomoyo_socket_sendmsg),
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
};
/* Lock for GC. */
DEFINE_SRCU(tomoyo_ss);
int tomoyo_enabled __lsm_ro_after_init = 1;
/**
* tomoyo_init - Register TOMOYO Linux as a LSM module.
*
* Returns 0.
*/
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
static int __init tomoyo_init(void)
{
struct tomoyo_task *s = tomoyo_task(current);
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
/* register ourselves with the security framework */
security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
pr_info("TOMOYO Linux initialized\n");
s->domain_info = &tomoyo_kernel_domain;
atomic_inc(&tomoyo_kernel_domain.users);
s->old_domain_info = NULL;
tomoyo_mm_init();
LSM adapter functions. DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-05 16:18:16 +08:00
return 0;
}
DEFINE_LSM(tomoyo) = {
.name = "tomoyo",
.enabled = &tomoyo_enabled,
.flags = LSM_FLAG_LEGACY_MAJOR,
.blobs = &tomoyo_blob_sizes,
.init = tomoyo_init,
};