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b53767719b
Implement file posix capabilities. This allows programs to be given a subset of root's powers regardless of who runs them, without having to use setuid and giving the binary all of root's powers. This version works with Kaigai Kohei's userspace tools, found at http://www.kaigai.gr.jp/index.php. For more information on how to use this patch, Chris Friedhoff has posted a nice page at http://www.friedhoff.org/fscaps.html. Changelog: Nov 27: Incorporate fixes from Andrew Morton (security-introduce-file-caps-tweaks and security-introduce-file-caps-warning-fix) Fix Kconfig dependency. Fix change signaling behavior when file caps are not compiled in. Nov 13: Integrate comments from Alexey: Remove CONFIG_ ifdef from capability.h, and use %zd for printing a size_t. Nov 13: Fix endianness warnings by sparse as suggested by Alexey Dobriyan. Nov 09: Address warnings of unused variables at cap_bprm_set_security when file capabilities are disabled, and simultaneously clean up the code a little, by pulling the new code into a helper function. Nov 08: For pointers to required userspace tools and how to use them, see http://www.friedhoff.org/fscaps.html. Nov 07: Fix the calculation of the highest bit checked in check_cap_sanity(). Nov 07: Allow file caps to be enabled without CONFIG_SECURITY, since capabilities are the default. Hook cap_task_setscheduler when !CONFIG_SECURITY. Move capable(TASK_KILL) to end of cap_task_kill to reduce audit messages. Nov 05: Add secondary calls in selinux/hooks.c to task_setioprio and task_setscheduler so that selinux and capabilities with file cap support can be stacked. Sep 05: As Seth Arnold points out, uid checks are out of place for capability code. Sep 01: Define task_setscheduler, task_setioprio, cap_task_kill, and task_setnice to make sure a user cannot affect a process in which they called a program with some fscaps. One remaining question is the note under task_setscheduler: are we ok with CAP_SYS_NICE being sufficient to confine a process to a cpuset? It is a semantic change, as without fsccaps, attach_task doesn't allow CAP_SYS_NICE to override the uid equivalence check. But since it uses security_task_setscheduler, which elsewhere is used where CAP_SYS_NICE can be used to override the uid equivalence check, fixing it might be tough. task_setscheduler note: this also controls cpuset:attach_task. Are we ok with CAP_SYS_NICE being used to confine to a cpuset? task_setioprio task_setnice sys_setpriority uses this (through set_one_prio) for another process. Need same checks as setrlimit Aug 21: Updated secureexec implementation to reflect the fact that euid and uid might be the same and nonzero, but the process might still have elevated caps. Aug 15: Handle endianness of xattrs. Enforce capability version match between kernel and disk. Enforce that no bits beyond the known max capability are set, else return -EPERM. With this extra processing, it may be worth reconsidering doing all the work at bprm_set_security rather than d_instantiate. Aug 10: Always call getxattr at bprm_set_security, rather than caching it at d_instantiate. [morgan@kernel.org: file-caps clean up for linux/capability.h] [bunk@kernel.org: unexport cap_inode_killpriv] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Andrew Morgan <morgan@kernel.org> Signed-off-by: Andrew Morgan <morgan@kernel.org> Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/*
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* Capabilities Linux Security Module
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/security.h>
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#include <linux/file.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/skbuff.h>
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#include <linux/netlink.h>
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#include <linux/ptrace.h>
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#include <linux/moduleparam.h>
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static struct security_operations capability_ops = {
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.ptrace = cap_ptrace,
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.capget = cap_capget,
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.capset_check = cap_capset_check,
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.capset_set = cap_capset_set,
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.capable = cap_capable,
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.settime = cap_settime,
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.netlink_send = cap_netlink_send,
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.netlink_recv = cap_netlink_recv,
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.bprm_apply_creds = cap_bprm_apply_creds,
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.bprm_set_security = cap_bprm_set_security,
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.bprm_secureexec = cap_bprm_secureexec,
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.inode_setxattr = cap_inode_setxattr,
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.inode_removexattr = cap_inode_removexattr,
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.inode_need_killpriv = cap_inode_need_killpriv,
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.inode_killpriv = cap_inode_killpriv,
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.task_kill = cap_task_kill,
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.task_setscheduler = cap_task_setscheduler,
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.task_setioprio = cap_task_setioprio,
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.task_setnice = cap_task_setnice,
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.task_post_setuid = cap_task_post_setuid,
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.task_reparent_to_init = cap_task_reparent_to_init,
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.syslog = cap_syslog,
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.vm_enough_memory = cap_vm_enough_memory,
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};
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/* flag to keep track of how we were registered */
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static int secondary;
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static int capability_disable;
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module_param_named(disable, capability_disable, int, 0);
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static int __init capability_init (void)
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{
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if (capability_disable) {
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printk(KERN_INFO "Capabilities disabled at initialization\n");
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return 0;
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}
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/* register ourselves with the security framework */
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if (register_security (&capability_ops)) {
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/* try registering with primary module */
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if (mod_reg_security (KBUILD_MODNAME, &capability_ops)) {
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printk (KERN_INFO "Failure registering capabilities "
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"with primary security module.\n");
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return -EINVAL;
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}
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secondary = 1;
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}
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printk (KERN_INFO "Capability LSM initialized%s\n",
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secondary ? " as secondary" : "");
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return 0;
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}
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security_initcall (capability_init);
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