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x86: Properly set usable CET feature bits [BZ #26625] 

commit 94cd37ebb2
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Sep 16 05:27:32 2020 -0700

    x86: Use HAS_CPU_FEATURE with IBT and SHSTK [BZ #26625]

broke

GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK

since it can no longer disable IBT nor SHSTK.  Handle IBT and SHSTK with:

1. Revert commit 94cd37ebb2.
2. Clears the usable CET feature bits if kernel doesn't support CET.
3. Add GLIBC_TUNABLES tests without dlopen.
4. Add tests to verify that CPU_FEATURE_USABLE on IBT and SHSTK matches
_get_ssp.
5. Update GLIBC_TUNABLES tests with dlopen to verify that CET is disabled
with GLIBC_TUNABLES.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
H.J. Lu 2021-01-26 20:48:45 -08:00
parent 6032ae6514
commit 04dff6fc0d
10 changed files with 120 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
sysdeps/x86/Makefile
View File

@ -82,7 +82,9 @@ sysdep-dl-routines += dl-cet
tests += tst-cet-legacy-1 tst-cet-legacy-1a tst-cet-legacy-2 \
tst-cet-legacy-2a tst-cet-legacy-3 tst-cet-legacy-4 \
tst-cet-legacy-5a tst-cet-legacy-6a tst-cet-legacy-7 \
tst-cet-legacy-8
tst-cet-legacy-8 tst-cet-legacy-9 tst-cet-legacy-9-static \
tst-cet-legacy-10 tst-cet-legacy-10-static
tests-static += tst-cet-legacy-9-static tst-cet-legacy-10-static
tst-cet-legacy-1a-ARGS = -- $(host-test-program-cmd)
ifneq (no,$(have-tunables))
tests += tst-cet-legacy-4a tst-cet-legacy-4b tst-cet-legacy-4c \
@ -123,6 +125,8 @@ 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
$(objpfx)tst-cet-legacy-1: $(objpfx)tst-cet-legacy-mod-1.so \
$(objpfx)tst-cet-legacy-mod-2.so
@ -163,6 +167,8 @@ $(objpfx)tst-cet-legacy-6b: $(libdl)
$(objpfx)tst-cet-legacy-6b.out: $(objpfx)tst-cet-legacy-mod-6a.so \
$(objpfx)tst-cet-legacy-mod-6b.so
tst-cet-legacy-6b-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK
tst-cet-legacy-9-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK
tst-cet-legacy-9-static-ENV = GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK
endif
endif

11
sysdeps/x86/cpu-features.c
View File

@ -75,6 +75,7 @@ update_usable (struct cpu_features *cpu_features)
CPU_FEATURE_SET_USABLE (cpu_features, PREFETCHWT1);
CPU_FEATURE_SET_USABLE (cpu_features, OSPKE);
CPU_FEATURE_SET_USABLE (cpu_features, WAITPKG);
CPU_FEATURE_SET_USABLE (cpu_features, SHSTK);
CPU_FEATURE_SET_USABLE (cpu_features, GFNI);
CPU_FEATURE_SET_USABLE (cpu_features, RDPID);
CPU_FEATURE_SET_USABLE (cpu_features, RDRAND);
@ -84,6 +85,7 @@ update_usable (struct cpu_features *cpu_features)
CPU_FEATURE_SET_USABLE (cpu_features, FSRM);
CPU_FEATURE_SET_USABLE (cpu_features, SERIALIZE);
CPU_FEATURE_SET_USABLE (cpu_features, TSXLDTRK);
CPU_FEATURE_SET_USABLE (cpu_features, IBT);
CPU_FEATURE_SET_USABLE (cpu_features, LAHF64_SAHF64);
CPU_FEATURE_SET_USABLE (cpu_features, LZCNT);
CPU_FEATURE_SET_USABLE (cpu_features, SSE4A);
@ -705,6 +707,11 @@ no_cpuid:
/* Check CET status. */
unsigned int cet_status = get_cet_status ();
if ((cet_status & GNU_PROPERTY_X86_FEATURE_1_IBT) == 0)
CPU_FEATURE_UNSET (cpu_features, IBT)
if ((cet_status & GNU_PROPERTY_X86_FEATURE_1_SHSTK) == 0)
CPU_FEATURE_UNSET (cpu_features, SHSTK)
if (cet_status)
{
GL(dl_x86_feature_1) = cet_status;
@ -720,9 +727,9 @@ no_cpuid:
GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK
*/
unsigned int cet_feature = 0;
if (!HAS_CPU_FEATURE (IBT))
if (!CPU_FEATURE_USABLE (IBT))
cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
if (!HAS_CPU_FEATURE (SHSTK))
if (!CPU_FEATURE_USABLE (SHSTK))
cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
if (cet_feature)

4
sysdeps/x86/dl-cet.c
View File

@ -77,11 +77,11 @@ dl_cet_check (struct link_map *m, const char *program)
GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK
*/
enable_ibt &= (HAS_CPU_FEATURE (IBT)
enable_ibt &= (CPU_FEATURE_USABLE (IBT)
&& (enable_ibt_type == cet_always_on
|| (m->l_x86_feature_1_and
& GNU_PROPERTY_X86_FEATURE_1_IBT) != 0));
enable_shstk &= (HAS_CPU_FEATURE (SHSTK)
enable_shstk &= (CPU_FEATURE_USABLE (SHSTK)
&& (enable_shstk_type == cet_always_on
|| (m->l_x86_feature_1_and
& GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0));

1
sysdeps/x86/tst-cet-legacy-10-static.c Normal file
View File

@ -0,0 +1 @@
#include "tst-cet-legacy-10.c"

43
sysdeps/x86/tst-cet-legacy-10.c Normal file
View File

@ -0,0 +1,43 @@
/* Check CPU_FEATURE_USABLE on IBT and SHSTK.
Copyright (C) 2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <x86intrin.h>
#include <sys/platform/x86.h>
#include <support/test-driver.h>
#include <support/xunistd.h>
/* Check that CPU_FEATURE_USABLE on IBT and SHSTK matches _get_ssp. */
static int
do_test (void)
{
if (_get_ssp () != 0)
{
if (CPU_FEATURE_USABLE (IBT) && CPU_FEATURE_USABLE (SHSTK))
return EXIT_SUCCESS;
}
else
{
if (!CPU_FEATURE_USABLE (IBT) && !CPU_FEATURE_USABLE (SHSTK))
return EXIT_SUCCESS;
}
return EXIT_FAILURE;
}
#include <support/test-driver.c>

11
sysdeps/x86/tst-cet-legacy-5.c
View File

@ -37,6 +37,12 @@ do_test_1 (const char *modname, bool fail)
int (*fp) (void);
void *h;
/* NB: dlopen should never fail on non-CET platforms. If SHSTK is
disabled, assuming IBT is also disabled. */
bool cet_enabled = _get_ssp () != 0 && !CET_MAYBE_DISABLED;
if (!cet_enabled)
fail = false;
h = dlopen (modname, RTLD_LAZY);
if (h == NULL)
{
@ -53,10 +59,7 @@ do_test_1 (const char *modname, bool fail)
FAIL_EXIT1 ("cannot open '%s': %s\n", modname, err);
}
/* NB: dlopen should never fail on non-CET platforms. If SHSTK is
disabled, assuming IBT is also disabled. */
bool cet_enabled = _get_ssp () != 0 && !CET_MAYBE_DISABLED;
if (fail && cet_enabled)
if (fail)
FAIL_EXIT1 ("dlopen should have failed\n");
fp = dlsym (h, "test");

11
sysdeps/x86/tst-cet-legacy-6.c
View File

@ -37,6 +37,12 @@ do_test_1 (const char *modname, bool fail)
int (*fp) (void);
void *h;
/* NB: dlopen should never fail on non-CET platforms. If SHSTK is
disabled, assuming IBT is also disabled. */
bool cet_enabled = _get_ssp () != 0 && !CET_MAYBE_DISABLED;
if (!cet_enabled)
fail = false;
h = dlopen (modname, RTLD_LAZY);
if (h == NULL)
{
@ -53,10 +59,7 @@ do_test_1 (const char *modname, bool fail)
FAIL_EXIT1 ("cannot open '%s': %s\n", modname, err);
}
/* NB: dlopen should never fail on non-CET platforms. If SHSTK is
disabled, assuming IBT is also disabled. */
bool cet_enabled = _get_ssp () != 0 && !CET_MAYBE_DISABLED;
if (fail && cet_enabled)
if (fail)
FAIL_EXIT1 ("dlopen should have failed\n");
fp = dlsym (h, "test");

1
sysdeps/x86/tst-cet-legacy-9-static.c Normal file
View File

@ -0,0 +1 @@
#include "tst-cet-legacy-9.c"

41
sysdeps/x86/tst-cet-legacy-9.c Normal file
View File

@ -0,0 +1,41 @@
/* Check CET compatibility with legacy JIT engine via GLIBC_TUNABLES.
Copyright (C) 2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <support/test-driver.h>
#include <support/xunistd.h>
/* Check that mmapped legacy code won't trigger segfault with
-fcf-protection and GLIBC_TUNABLES=glibc.cpu.hwcaps=-IBT,-SHSTK. */
static int
do_test (void)
{
void (*funcp) (void);
funcp = xmmap (NULL, 0x1000, PROT_EXEC | PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1);
printf ("mmap = %p\n", funcp);
/* Write RET instruction. */
*(char *) funcp = 0xc3;
funcp ();
return EXIT_SUCCESS;
}
#include <support/test-driver.c>

2
sysdeps/x86/tst-get-cpu-features.c
View File

@ -301,6 +301,7 @@ do_test (void)
CHECK_CPU_FEATURE_USABLE (OSPKE);
CHECK_CPU_FEATURE_USABLE (WAITPKG);
CHECK_CPU_FEATURE_USABLE (AVX512_VBMI2);
CHECK_CPU_FEATURE_USABLE (SHSTK);
CHECK_CPU_FEATURE_USABLE (GFNI);
CHECK_CPU_FEATURE_USABLE (VAES);
CHECK_CPU_FEATURE_USABLE (VPCLMULQDQ);
@ -324,6 +325,7 @@ do_test (void)
CHECK_CPU_FEATURE_USABLE (HYBRID);
CHECK_CPU_FEATURE_USABLE (TSXLDTRK);
CHECK_CPU_FEATURE_USABLE (PCONFIG);
CHECK_CPU_FEATURE_USABLE (IBT);
CHECK_CPU_FEATURE_USABLE (AMX_BF16);
CHECK_CPU_FEATURE_USABLE (AVX512_FP16);
CHECK_CPU_FEATURE_USABLE (AMX_TILE);