linux/tools/testing/selftests/x86/ldt_gdt.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
/*
* ldt_gdt.c - Test cases for LDT and GDT access
* Copyright (c) 2015 Andrew Lutomirski
*/
#define _GNU_SOURCE
#include <err.h>
#include <stdio.h>
#include <stdint.h>
#include <signal.h>
#include <setjmp.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <asm/ldt.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdbool.h>
#include <pthread.h>
#include <sched.h>
#include <linux/futex.h>
#include <sys/mman.h>
#include <asm/prctl.h>
#include <sys/prctl.h>
#define AR_ACCESSED (1<<8)
#define AR_TYPE_RODATA (0 * (1<<9))
#define AR_TYPE_RWDATA (1 * (1<<9))
#define AR_TYPE_RODATA_EXPDOWN (2 * (1<<9))
#define AR_TYPE_RWDATA_EXPDOWN (3 * (1<<9))
#define AR_TYPE_XOCODE (4 * (1<<9))
#define AR_TYPE_XRCODE (5 * (1<<9))
#define AR_TYPE_XOCODE_CONF (6 * (1<<9))
#define AR_TYPE_XRCODE_CONF (7 * (1<<9))
#define AR_DPL3 (3 * (1<<13))
#define AR_S (1 << 12)
#define AR_P (1 << 15)
#define AR_AVL (1 << 20)
#define AR_L (1 << 21)
#define AR_DB (1 << 22)
#define AR_G (1 << 23)
#ifdef __x86_64__
# define INT80_CLOBBERS "r8", "r9", "r10", "r11"
#else
# define INT80_CLOBBERS
#endif
static int nerrs;
/* Points to an array of 1024 ints, each holding its own index. */
static const unsigned int *counter_page;
static struct user_desc *low_user_desc;
static struct user_desc *low_user_desc_clear; /* Use to delete GDT entry */
static int gdt_entry_num;
static void check_invalid_segment(uint16_t index, int ldt)
{
uint32_t has_limit = 0, has_ar = 0, limit, ar;
uint32_t selector = (index << 3) | (ldt << 2) | 3;
asm ("lsl %[selector], %[limit]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_limit]\n\t"
"1:"
: [limit] "=r" (limit), [has_limit] "+rm" (has_limit)
: [selector] "r" (selector));
asm ("larl %[selector], %[ar]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_ar]\n\t"
"1:"
: [ar] "=r" (ar), [has_ar] "+rm" (has_ar)
: [selector] "r" (selector));
if (has_limit || has_ar) {
printf("[FAIL]\t%s entry %hu is valid but should be invalid\n",
(ldt ? "LDT" : "GDT"), index);
nerrs++;
} else {
printf("[OK]\t%s entry %hu is invalid\n",
(ldt ? "LDT" : "GDT"), index);
}
}
static void check_valid_segment(uint16_t index, int ldt,
uint32_t expected_ar, uint32_t expected_limit,
bool verbose)
{
uint32_t has_limit = 0, has_ar = 0, limit, ar;
uint32_t selector = (index << 3) | (ldt << 2) | 3;
asm ("lsl %[selector], %[limit]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_limit]\n\t"
"1:"
: [limit] "=r" (limit), [has_limit] "+rm" (has_limit)
: [selector] "r" (selector));
asm ("larl %[selector], %[ar]\n\t"
"jnz 1f\n\t"
"movl $1, %[has_ar]\n\t"
"1:"
: [ar] "=r" (ar), [has_ar] "+rm" (has_ar)
: [selector] "r" (selector));
if (!has_limit || !has_ar) {
printf("[FAIL]\t%s entry %hu is invalid but should be valid\n",
(ldt ? "LDT" : "GDT"), index);
nerrs++;
return;
}
/* The SDM says "bits 19:16 are undefined". Thanks. */
ar &= ~0xF0000;
/*
* NB: Different Linux versions do different things with the
* accessed bit in set_thread_area().
*/
if (ar != expected_ar && ar != (expected_ar | AR_ACCESSED)) {
printf("[FAIL]\t%s entry %hu has AR 0x%08X but expected 0x%08X\n",
(ldt ? "LDT" : "GDT"), index, ar, expected_ar);
nerrs++;
} else if (limit != expected_limit) {
printf("[FAIL]\t%s entry %hu has limit 0x%08X but expected 0x%08X\n",
(ldt ? "LDT" : "GDT"), index, limit, expected_limit);
nerrs++;
} else if (verbose) {
printf("[OK]\t%s entry %hu has AR 0x%08X and limit 0x%08X\n",
(ldt ? "LDT" : "GDT"), index, ar, limit);
}
}
static bool install_valid_mode(const struct user_desc *d, uint32_t ar,
bool oldmode, bool ldt)
{
struct user_desc desc = *d;
int ret;
if (!ldt) {
#ifndef __i386__
/* No point testing set_thread_area in a 64-bit build */
return false;
#endif
if (!gdt_entry_num)
return false;
desc.entry_number = gdt_entry_num;
ret = syscall(SYS_set_thread_area, &desc);
} else {
ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
&desc, sizeof(desc));
if (ret < -1)
errno = -ret;
if (ret != 0 && errno == ENOSYS) {
printf("[OK]\tmodify_ldt returned -ENOSYS\n");
return false;
}
}
if (ret == 0) {
uint32_t limit = desc.limit;
if (desc.limit_in_pages)
limit = (limit << 12) + 4095;
check_valid_segment(desc.entry_number, ldt, ar, limit, true);
return true;
} else {
if (desc.seg_32bit) {
printf("[FAIL]\tUnexpected %s failure %d\n",
ldt ? "modify_ldt" : "set_thread_area",
errno);
nerrs++;
return false;
} else {
printf("[OK]\t%s rejected 16 bit segment\n",
ldt ? "modify_ldt" : "set_thread_area");
return false;
}
}
}
static bool install_valid(const struct user_desc *desc, uint32_t ar)
{
bool ret = install_valid_mode(desc, ar, false, true);
if (desc->contents <= 1 && desc->seg_32bit &&
!desc->seg_not_present) {
/* Should work in the GDT, too. */
install_valid_mode(desc, ar, false, false);
}
return ret;
}
static void install_invalid(const struct user_desc *desc, bool oldmode)
{
int ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
desc, sizeof(*desc));
if (ret < -1)
errno = -ret;
if (ret == 0) {
check_invalid_segment(desc->entry_number, 1);
} else if (errno == ENOSYS) {
printf("[OK]\tmodify_ldt returned -ENOSYS\n");
} else {
if (desc->seg_32bit) {
printf("[FAIL]\tUnexpected modify_ldt failure %d\n",
errno);
nerrs++;
} else {
printf("[OK]\tmodify_ldt rejected 16 bit segment\n");
}
}
}
static int safe_modify_ldt(int func, struct user_desc *ptr,
unsigned long bytecount)
{
int ret = syscall(SYS_modify_ldt, 0x11, ptr, bytecount);
if (ret < -1)
errno = -ret;
return ret;
}
static void fail_install(struct user_desc *desc)
{
if (safe_modify_ldt(0x11, desc, sizeof(*desc)) == 0) {
printf("[FAIL]\tmodify_ldt accepted a bad descriptor\n");
nerrs++;
} else if (errno == ENOSYS) {
printf("[OK]\tmodify_ldt returned -ENOSYS\n");
} else {
printf("[OK]\tmodify_ldt failure %d\n", errno);
}
}
static void do_simple_tests(void)
{
struct user_desc desc = {
.entry_number = 0,
.base_addr = 0,
.limit = 10,
.seg_32bit = 1,
.contents = 2, /* Code, not conforming */
.read_exec_only = 0,
.limit_in_pages = 0,
.seg_not_present = 0,
.useable = 0
};
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB);
desc.limit_in_pages = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G);
check_invalid_segment(1, 1);
desc.entry_number = 2;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G);
check_invalid_segment(1, 1);
desc.base_addr = 0xf0000000;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G);
desc.useable = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_P | AR_DB | AR_G | AR_AVL);
desc.seg_not_present = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_DB | AR_G | AR_AVL);
desc.seg_32bit = 0;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_G | AR_AVL);
desc.seg_32bit = 1;
desc.contents = 0;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA |
AR_S | AR_DB | AR_G | AR_AVL);
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA |
AR_S | AR_DB | AR_G | AR_AVL);
desc.contents = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA_EXPDOWN |
AR_S | AR_DB | AR_G | AR_AVL);
desc.read_exec_only = 0;
desc.limit_in_pages = 0;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA_EXPDOWN |
AR_S | AR_DB | AR_AVL);
desc.contents = 3;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE_CONF |
AR_S | AR_DB | AR_AVL);
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE_CONF |
AR_S | AR_DB | AR_AVL);
desc.read_exec_only = 0;
desc.contents = 2;
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
AR_S | AR_DB | AR_AVL);
desc.read_exec_only = 1;
#ifdef __x86_64__
desc.lm = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL);
desc.lm = 0;
#endif
bool entry1_okay = install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL);
if (entry1_okay) {
printf("[RUN]\tTest fork\n");
pid_t child = fork();
if (child == 0) {
nerrs = 0;
check_valid_segment(desc.entry_number, 1,
AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL, desc.limit,
true);
check_invalid_segment(1, 1);
exit(nerrs ? 1 : 0);
} else {
int status;
if (waitpid(child, &status, 0) != child ||
!WIFEXITED(status)) {
printf("[FAIL]\tChild died\n");
nerrs++;
} else if (WEXITSTATUS(status) != 0) {
printf("[FAIL]\tChild failed\n");
nerrs++;
} else {
printf("[OK]\tChild succeeded\n");
}
}
printf("[RUN]\tTest size\n");
int i;
for (i = 0; i < 8192; i++) {
desc.entry_number = i;
desc.limit = i;
if (safe_modify_ldt(0x11, &desc, sizeof(desc)) != 0) {
printf("[FAIL]\tFailed to install entry %d\n", i);
nerrs++;
break;
}
}
for (int j = 0; j < i; j++) {
check_valid_segment(j, 1, AR_DPL3 | AR_TYPE_XOCODE |
AR_S | AR_DB | AR_AVL, j, false);
}
printf("[DONE]\tSize test\n");
} else {
printf("[SKIP]\tSkipping fork and size tests because we have no LDT\n");
}
/* Test entry_number too high. */
desc.entry_number = 8192;
fail_install(&desc);
/* Test deletion and actions mistakeable for deletion. */
memset(&desc, 0, sizeof(desc));
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P);
desc.seg_not_present = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S);
desc.seg_not_present = 0;
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S | AR_P);
desc.read_exec_only = 0;
desc.seg_not_present = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S);
desc.read_exec_only = 1;
desc.limit = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S);
desc.limit = 0;
desc.base_addr = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S);
desc.base_addr = 0;
install_invalid(&desc, false);
desc.seg_not_present = 0;
desc.seg_32bit = 1;
desc.read_exec_only = 0;
desc.limit = 0xfffff;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB);
desc.limit_in_pages = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB | AR_G);
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S | AR_P | AR_DB | AR_G);
desc.contents = 1;
desc.read_exec_only = 0;
install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G);
desc.read_exec_only = 1;
install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G);
desc.limit = 0;
install_invalid(&desc, true);
}
/*
* 0: thread is idle
* 1: thread armed
* 2: thread should clear LDT entry 0
* 3: thread should exit
*/
static volatile unsigned int ftx;
static void *threadproc(void *ctx)
{
cpu_set_t cpuset;
CPU_ZERO(&cpuset);
CPU_SET(1, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
err(1, "sched_setaffinity to CPU 1"); /* should never fail */
while (1) {
syscall(SYS_futex, &ftx, FUTEX_WAIT, 0, NULL, NULL, 0);
while (ftx != 2) {
if (ftx >= 3)
return NULL;
}
/* clear LDT entry 0 */
const struct user_desc desc = {};
if (syscall(SYS_modify_ldt, 1, &desc, sizeof(desc)) != 0)
err(1, "modify_ldt");
/* If ftx == 2, set it to zero. If ftx == 100, quit. */
unsigned int x = -2;
asm volatile ("lock xaddl %[x], %[ftx]" :
[x] "+r" (x), [ftx] "+m" (ftx));
if (x != 2)
return NULL;
}
}
#ifdef __i386__
#ifndef SA_RESTORE
#define SA_RESTORER 0x04000000
#endif
/*
* The UAPI header calls this 'struct sigaction', which conflicts with
* glibc. Sigh.
*/
struct fake_ksigaction {
void *handler; /* the real type is nasty */
unsigned long sa_flags;
void (*sa_restorer)(void);
unsigned char sigset[8];
};
static void fix_sa_restorer(int sig)
{
struct fake_ksigaction ksa;
if (syscall(SYS_rt_sigaction, sig, NULL, &ksa, 8) == 0) {
/*
* glibc has a nasty bug: it sometimes writes garbage to
* sa_restorer. This interacts quite badly with anything
* that fiddles with SS because it can trigger legacy
* stack switching. Patch it up. See:
*
* https://sourceware.org/bugzilla/show_bug.cgi?id=21269
*/
if (!(ksa.sa_flags & SA_RESTORER) && ksa.sa_restorer) {
ksa.sa_restorer = NULL;
if (syscall(SYS_rt_sigaction, sig, &ksa, NULL,
sizeof(ksa.sigset)) != 0)
err(1, "rt_sigaction");
}
}
}
#else
static void fix_sa_restorer(int sig)
{
/* 64-bit glibc works fine. */
}
#endif
static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
int flags)
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = handler;
sa.sa_flags = SA_SIGINFO | flags;
sigemptyset(&sa.sa_mask);
if (sigaction(sig, &sa, 0))
err(1, "sigaction");
fix_sa_restorer(sig);
}
static jmp_buf jmpbuf;
static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
{
siglongjmp(jmpbuf, 1);
}
static void do_multicpu_tests(void)
{
cpu_set_t cpuset;
pthread_t thread;
int failures = 0, iters = 5, i;
unsigned short orig_ss;
CPU_ZERO(&cpuset);
CPU_SET(1, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
printf("[SKIP]\tCannot set affinity to CPU 1\n");
return;
}
CPU_ZERO(&cpuset);
CPU_SET(0, &cpuset);
if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
printf("[SKIP]\tCannot set affinity to CPU 0\n");
return;
}
sethandler(SIGSEGV, sigsegv, 0);
#ifdef __i386__
/* True 32-bit kernels send SIGILL instead of SIGSEGV on IRET faults. */
sethandler(SIGILL, sigsegv, 0);
#endif
printf("[RUN]\tCross-CPU LDT invalidation\n");
if (pthread_create(&thread, 0, threadproc, 0) != 0)
err(1, "pthread_create");
asm volatile ("mov %%ss, %0" : "=rm" (orig_ss));
for (i = 0; i < 5; i++) {
if (sigsetjmp(jmpbuf, 1) != 0)
continue;
/* Make sure the thread is ready after the last test. */
while (ftx != 0)
;
struct user_desc desc = {
.entry_number = 0,
.base_addr = 0,
.limit = 0xfffff,
.seg_32bit = 1,
.contents = 0, /* Data */
.read_exec_only = 0,
.limit_in_pages = 1,
.seg_not_present = 0,
.useable = 0
};
if (safe_modify_ldt(0x11, &desc, sizeof(desc)) != 0) {
if (errno != ENOSYS)
err(1, "modify_ldt");
printf("[SKIP]\tmodify_ldt unavailable\n");
break;
}
/* Arm the thread. */
ftx = 1;
syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
asm volatile ("mov %0, %%ss" : : "r" (0x7));
/* Go! */
ftx = 2;
while (ftx != 0)
;
/*
* On success, modify_ldt will segfault us synchronously,
* and we'll escape via siglongjmp.
*/
failures++;
asm volatile ("mov %0, %%ss" : : "rm" (orig_ss));
};
ftx = 100; /* Kill the thread. */
syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
if (pthread_join(thread, NULL) != 0)
err(1, "pthread_join");
if (failures) {
printf("[FAIL]\t%d of %d iterations failed\n", failures, iters);
nerrs++;
} else {
printf("[OK]\tAll %d iterations succeeded\n", iters);
}
}
static int finish_exec_test(void)
{
/*
x86/ldt: Prevent LDT inheritance on exec The LDT is inherited across fork() or exec(), but that makes no sense at all because exec() is supposed to start the process clean. The reason why this happens is that init_new_context_ldt() is called from init_new_context() which obviously needs to be called for both fork() and exec(). It would be surprising if anything relies on that behaviour, so it seems to be safe to remove that misfeature. Split the context initialization into two parts. Clear the LDT pointer and initialize the mutex from the general context init and move the LDT duplication to arch_dup_mmap() which is only called on fork(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirsky <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: dan.j.williams@intel.com Cc: hughd@google.com Cc: keescook@google.com Cc: kirill.shutemov@linux.intel.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-14 19:27:31 +08:00
* Older kernel versions did inherit the LDT on exec() which is
* wrong because exec() starts from a clean state.
*/
x86/ldt: Prevent LDT inheritance on exec The LDT is inherited across fork() or exec(), but that makes no sense at all because exec() is supposed to start the process clean. The reason why this happens is that init_new_context_ldt() is called from init_new_context() which obviously needs to be called for both fork() and exec(). It would be surprising if anything relies on that behaviour, so it seems to be safe to remove that misfeature. Split the context initialization into two parts. Clear the LDT pointer and initialize the mutex from the general context init and move the LDT duplication to arch_dup_mmap() which is only called on fork(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirsky <luto@kernel.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Borislav Petkov <bpetkov@suse.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Laight <David.Laight@aculab.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eduardo Valentin <eduval@amazon.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Will Deacon <will.deacon@arm.com> Cc: aliguori@amazon.com Cc: dan.j.williams@intel.com Cc: hughd@google.com Cc: keescook@google.com Cc: kirill.shutemov@linux.intel.com Cc: linux-mm@kvack.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-14 19:27:31 +08:00
check_invalid_segment(0, 1);
return nerrs ? 1 : 0;
}
static void do_exec_test(void)
{
printf("[RUN]\tTest exec\n");
struct user_desc desc = {
.entry_number = 0,
.base_addr = 0,
.limit = 42,
.seg_32bit = 1,
.contents = 2, /* Code, not conforming */
.read_exec_only = 0,
.limit_in_pages = 0,
.seg_not_present = 0,
.useable = 0
};
install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB);
pid_t child = fork();
if (child == 0) {
execl("/proc/self/exe", "ldt_gdt_test_exec", NULL);
printf("[FAIL]\tCould not exec self\n");
exit(1); /* exec failed */
} else {
int status;
if (waitpid(child, &status, 0) != child ||
!WIFEXITED(status)) {
printf("[FAIL]\tChild died\n");
nerrs++;
} else if (WEXITSTATUS(status) != 0) {
printf("[FAIL]\tChild failed\n");
nerrs++;
} else {
printf("[OK]\tChild succeeded\n");
}
}
}
static void setup_counter_page(void)
{
unsigned int *page = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1, 0);
if (page == MAP_FAILED)
err(1, "mmap");
for (int i = 0; i < 1024; i++)
page[i] = i;
counter_page = page;
}
static int invoke_set_thread_area(void)
{
int ret;
asm volatile ("int $0x80"
: "=a" (ret), "+m" (low_user_desc) :
"a" (243), "b" (low_user_desc)
: INT80_CLOBBERS);
return ret;
}
static void setup_low_user_desc(void)
{
low_user_desc = mmap(NULL, 2 * sizeof(struct user_desc),
PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1, 0);
if (low_user_desc == MAP_FAILED)
err(1, "mmap");
low_user_desc->entry_number = -1;
low_user_desc->base_addr = (unsigned long)&counter_page[1];
low_user_desc->limit = 0xfffff;
low_user_desc->seg_32bit = 1;
low_user_desc->contents = 0; /* Data, grow-up*/
low_user_desc->read_exec_only = 0;
low_user_desc->limit_in_pages = 1;
low_user_desc->seg_not_present = 0;
low_user_desc->useable = 0;
if (invoke_set_thread_area() == 0) {
gdt_entry_num = low_user_desc->entry_number;
printf("[NOTE]\tset_thread_area is available; will use GDT index %d\n", gdt_entry_num);
} else {
printf("[NOTE]\tset_thread_area is unavailable\n");
}
low_user_desc_clear = low_user_desc + 1;
low_user_desc_clear->entry_number = gdt_entry_num;
low_user_desc_clear->read_exec_only = 1;
low_user_desc_clear->seg_not_present = 1;
}
static void test_gdt_invalidation(void)
{
if (!gdt_entry_num)
return; /* 64-bit only system -- we can't use set_thread_area */
unsigned short prev_sel;
unsigned short sel;
unsigned int eax;
const char *result;
#ifdef __x86_64__
unsigned long saved_base;
unsigned long new_base;
#endif
/* Test DS */
invoke_set_thread_area();
eax = 243;
sel = (gdt_entry_num << 3) | 3;
asm volatile ("movw %%ds, %[prev_sel]\n\t"
"movw %[sel], %%ds\n\t"
#ifdef __i386__
"pushl %%ebx\n\t"
#endif
"movl %[arg1], %%ebx\n\t"
"int $0x80\n\t" /* Should invalidate ds */
#ifdef __i386__
"popl %%ebx\n\t"
#endif
"movw %%ds, %[sel]\n\t"
"movw %[prev_sel], %%ds"
: [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
"+a" (eax)
: "m" (low_user_desc_clear),
[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
: INT80_CLOBBERS);
if (sel != 0) {
result = "FAIL";
nerrs++;
} else {
result = "OK";
}
printf("[%s]\tInvalidate DS with set_thread_area: new DS = 0x%hx\n",
result, sel);
/* Test ES */
invoke_set_thread_area();
eax = 243;
sel = (gdt_entry_num << 3) | 3;
asm volatile ("movw %%es, %[prev_sel]\n\t"
"movw %[sel], %%es\n\t"
#ifdef __i386__
"pushl %%ebx\n\t"
#endif
"movl %[arg1], %%ebx\n\t"
"int $0x80\n\t" /* Should invalidate es */
#ifdef __i386__
"popl %%ebx\n\t"
#endif
"movw %%es, %[sel]\n\t"
"movw %[prev_sel], %%es"
: [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
"+a" (eax)
: "m" (low_user_desc_clear),
[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
: INT80_CLOBBERS);
if (sel != 0) {
result = "FAIL";
nerrs++;
} else {
result = "OK";
}
printf("[%s]\tInvalidate ES with set_thread_area: new ES = 0x%hx\n",
result, sel);
/* Test FS */
invoke_set_thread_area();
eax = 243;
sel = (gdt_entry_num << 3) | 3;
#ifdef __x86_64__
syscall(SYS_arch_prctl, ARCH_GET_FS, &saved_base);
#endif
asm volatile ("movw %%fs, %[prev_sel]\n\t"
"movw %[sel], %%fs\n\t"
#ifdef __i386__
"pushl %%ebx\n\t"
#endif
"movl %[arg1], %%ebx\n\t"
"int $0x80\n\t" /* Should invalidate fs */
#ifdef __i386__
"popl %%ebx\n\t"
#endif
"movw %%fs, %[sel]\n\t"
: [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
"+a" (eax)
: "m" (low_user_desc_clear),
[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
: INT80_CLOBBERS);
#ifdef __x86_64__
syscall(SYS_arch_prctl, ARCH_GET_FS, &new_base);
#endif
/* Restore FS/BASE for glibc */
asm volatile ("movw %[prev_sel], %%fs" : : [prev_sel] "rm" (prev_sel));
#ifdef __x86_64__
if (saved_base)
syscall(SYS_arch_prctl, ARCH_SET_FS, saved_base);
#endif
if (sel != 0) {
result = "FAIL";
nerrs++;
} else {
result = "OK";
}
printf("[%s]\tInvalidate FS with set_thread_area: new FS = 0x%hx\n",
result, sel);
#ifdef __x86_64__
if (sel == 0 && new_base != 0) {
nerrs++;
printf("[FAIL]\tNew FSBASE was 0x%lx\n", new_base);
} else {
printf("[OK]\tNew FSBASE was zero\n");
}
#endif
/* Test GS */
invoke_set_thread_area();
eax = 243;
sel = (gdt_entry_num << 3) | 3;
#ifdef __x86_64__
syscall(SYS_arch_prctl, ARCH_GET_GS, &saved_base);
#endif
asm volatile ("movw %%gs, %[prev_sel]\n\t"
"movw %[sel], %%gs\n\t"
#ifdef __i386__
"pushl %%ebx\n\t"
#endif
"movl %[arg1], %%ebx\n\t"
"int $0x80\n\t" /* Should invalidate gs */
#ifdef __i386__
"popl %%ebx\n\t"
#endif
"movw %%gs, %[sel]\n\t"
: [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
"+a" (eax)
: "m" (low_user_desc_clear),
[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
: INT80_CLOBBERS);
#ifdef __x86_64__
syscall(SYS_arch_prctl, ARCH_GET_GS, &new_base);
#endif
/* Restore GS/BASE for glibc */
asm volatile ("movw %[prev_sel], %%gs" : : [prev_sel] "rm" (prev_sel));
#ifdef __x86_64__
if (saved_base)
syscall(SYS_arch_prctl, ARCH_SET_GS, saved_base);
#endif
if (sel != 0) {
result = "FAIL";
nerrs++;
} else {
result = "OK";
}
printf("[%s]\tInvalidate GS with set_thread_area: new GS = 0x%hx\n",
result, sel);
#ifdef __x86_64__
if (sel == 0 && new_base != 0) {
nerrs++;
printf("[FAIL]\tNew GSBASE was 0x%lx\n", new_base);
} else {
printf("[OK]\tNew GSBASE was zero\n");
}
#endif
}
int main(int argc, char **argv)
{
if (argc == 1 && !strcmp(argv[0], "ldt_gdt_test_exec"))
return finish_exec_test();
setup_counter_page();
setup_low_user_desc();
do_simple_tests();
do_multicpu_tests();
do_exec_test();
test_gdt_invalidation();
return nerrs ? 1 : 0;
}