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x86/cet: Don't assume that SHSTK implies IBT

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Since shadow stack (SHSTK) is enabled in the Linux kernel without
enabling indirect branch tracking (IBT), don't assume that SHSTK
implies IBT.  Use "CPU_FEATURE_ACTIVE (IBT)" to check if IBT is active
and "CPU_FEATURE_ACTIVE (SHSTK)" to check if SHSTK is active.
This commit is contained in:
H.J. Lu 2023-12-16 08:53:12 -08:00
parent 12ab77e893
commit 442983319b
3 changed files with 11 additions and 11 deletions
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1
sysdeps/x86/Makefile
View file

@ -209,7 +209,6 @@ CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=branch
CFLAGS-tst-cet-legacy-mod-6b.c += -fcf-protection
CFLAGS-tst-cet-legacy-mod-6c.c += -fcf-protection
CFLAGS-tst-cet-legacy-7.c += -fcf-protection=none
CFLAGS-tst-cet-legacy-8.c += -mshstk
CFLAGS-tst-cet-legacy-10.c += -mshstk
CFLAGS-tst-cet-legacy-10-static.c += -mshstk

6
sysdeps/x86/tst-cet-legacy-10.c
View file

@ -21,19 +21,19 @@
#include <support/test-driver.h>
#include <support/xunistd.h>
/* Check that CPU_FEATURE_ACTIVE on IBT and SHSTK matches _get_ssp. */
/* Check that CPU_FEATURE_ACTIVE on SHSTK matches _get_ssp. */
static int
do_test (void)
{
if (_get_ssp () != 0)
{
if (CPU_FEATURE_ACTIVE (IBT) && CPU_FEATURE_ACTIVE (SHSTK))
if (CPU_FEATURE_ACTIVE (SHSTK))
return EXIT_SUCCESS;
}
else
{
if (!CPU_FEATURE_ACTIVE (IBT) && !CPU_FEATURE_ACTIVE (SHSTK))
if (!CPU_FEATURE_ACTIVE (SHSTK))
return EXIT_SUCCESS;
}

15
sysdeps/x86/tst-cet-legacy-8.c
View file

@ -18,7 +18,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <x86intrin.h>
#include <sys/platform/x86.h>
#include <sys/mman.h>
#include <support/test-driver.h>
#include <support/xsignal.h>
@ -29,11 +29,6 @@
static int
do_test (void)
{
/* NB: This test should trigger SIGSEGV on CET platforms. If SHSTK
is disabled, assuming IBT is also disabled. */
if (_get_ssp () == 0)
return EXIT_UNSUPPORTED;
void (*funcp) (void);
funcp = xmmap (NULL, 0x1000, PROT_EXEC | PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1);
@ -41,8 +36,14 @@ do_test (void)
/* Write RET instruction. */
*(char *) funcp = 0xc3;
funcp ();
/* NB: This test should trigger SIGSEGV when IBT is active. We should
reach here if IBT isn't active. */
if (!CPU_FEATURE_ACTIVE (IBT))
return EXIT_UNSUPPORTED;
return EXIT_FAILURE;
}
#define EXPECTED_SIGNAL (_get_ssp () == 0 ? 0 : SIGSEGV)
#define EXPECTED_SIGNAL (CPU_FEATURE_ACTIVE (IBT) ? SIGSEGV : 0)
#include <support/test-driver.c>