V4 [PATCH] x86: Remove ARCH_CET_LEGACY_BITMAP [BZ #25397]
H.J. Lu
hjl.tools@gmail.com
Tue Mar 17 00:58:17 GMT 2020
On Mon, Mar 16, 2020 at 07:41:54PM -0400, Carlos O'Donell wrote:
> On 3/13/20 9:25 AM, H.J. Lu via Libc-alpha wrote:
> > On Tue, Mar 10, 2020 at 06:36:54AM -0700, H.J. Lu wrote:
> >> On Tue, Mar 10, 2020 at 02:13:37PM +0100, Florian Weimer wrote:
> >>> * H. J. Lu:
> >>>
> >>>>> I think the error message should say *where* indirect branch tracking
> >>>>> is not enabled. I assume this is a property of the loaded object.
> >>>> Fixed. Now I got
> >>>>
> >>>> .... libvirtd[1048]: internal error: Failed to load module
> >>>> '/usr/lib64/libvirt/storage-backend/libvirt_storage_backend_rbd.so':
> >>>> /usr/lib64/ceph/libceph-common.so.0: indirect branch tracking isn't
> >>>> enabled: Invalid argument
> >>> What I meant is that the error message should say that the object
> >>> needs to be rebuilt with IBT/SHSTK support. In the above, it's
> >>> unclear whether the process or the object has to enable IBT.
> >>>
> >>> (The Invalid Argument part should also be suppressed.)
> >> Like this? The diff against V2 patch is:
> >>
> >> diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
> >> index f527a1414c..b2843488be 100644
> >> --- a/sysdeps/x86/dl-cet.c
> >> +++ b/sysdeps/x86/dl-cet.c
> >> @@ -142,10 +142,10 @@ dl_cet_check (struct link_map *m, const char *program)
> >> /* When IBT is enabled, we cannot dlopen a shared
> >> object without IBT. */
> >> if (found_ibt_legacy)
> >> - _dl_signal_error (EINVAL,
> >> + _dl_signal_error (0,
> >> m->l_initfini[ibt_legacy]->l_name,
> >> "dlopen",
> >> - N_("indirect branch tracking isn't enabled"));
> >> + N_("rebuilt with IBT support needed"));
> >> }
> >>
> >> if (enable_shstk_type != CET_PERMISSIVE)
> >> @@ -153,10 +153,10 @@ dl_cet_check (struct link_map *m, const char *program)
> >> /* When SHSTK is enabled, we cannot dlopen a shared
> >> object without SHSTK. */
> >> if (found_shstk_legacy)
> >> - _dl_signal_error (EINVAL,
> >> + _dl_signal_error (0,
> >> m->l_initfini[shstk_legacy]->l_name,
> >> "dlopen",
> >> - N_("shadow stack isn't enabled"));
> >> + N_("rebuilt with SHSTK support needed"));
> >> }
> >>
> >> if (enable_ibt_type != CET_PERMISSIVE
> >>
> > PING.
>
> Please post v4 with adjusted error message, and expanded comment in new test,
> and I'll review that quickly.
>
> > H.J.
> > ---
> > Since legacy bitmap doesn't cover jitted code generated by legacy JIT
> > engine, it isn't very useful. This patch removes ARCH_CET_LEGACY_BITMAP
> > and treats indirect branch tracking similar to shadow stack by removing
> > legacy bitmap support.
>
> OK.
>
>
> >
> > * sysdeps/unix/sysv/linux/x86/dl-cet.h
> > (dl_cet_allocate_legacy_bitmap): Removed.
> > * sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> > (ARCH_CET_LEGACY_BITMAP): Removed.
> > * sysdeps/x86/Makefile (tests): Add tst-cet-legacy-7.
> > (CFLAGS-tst-cet-legacy-mod-5a.c): Changed to
> > -fcf-protection=branch.
> > (CFLAGS-tst-cet-legacy-mod-6a.c): Likewise.
> > (CFLAGS-tst-cet-legacy-7.c): New.
> > * sysdeps/x86/dl-cet.c (dl_cet_mark_legacy_region): Removed.
> > (dl_cet_check): Remove legacy bitmap support. Don't allow
> > dlopening legacy shared library when IBT is enabled. Set
> > feature_1 if IBT or SHSTK is enabled in executable.
> > * sysdeps/x86/dl-procruntime.c (_dl_x86_legacy_bitmap): Removed.
> > * sysdeps/x86/tst-cet-legacy-4.c: Include <string.h> and
> > <support/check.h>.
> > (do_test): Check indirect branch tracking error. Use
> > FAIL_EXIT1.
> > * sysdeps/x86/tst-cet-legacy-7.c: New file.
>
> Hopefully you don't plan to include this in the commit log :-)
>
Leftover from my old version :-).
> > ---
> > sysdeps/unix/sysv/linux/x86/dl-cet.h | 20 --
> > .../unix/sysv/linux/x86/include/asm/prctl.h | 5 -
> > sysdeps/x86/Makefile | 7 +-
> > sysdeps/x86/dl-cet.c | 217 +++++-------------
> > sysdeps/x86/dl-procruntime.c | 11 -
> > sysdeps/x86/tst-cet-legacy-4.c | 19 +-
> > sysdeps/x86/tst-cet-legacy-5.c | 2 +-
> > sysdeps/x86/tst-cet-legacy-6.c | 2 +-
> > sysdeps/x86/tst-cet-legacy-7.c | 36 +++
> > 9 files changed, 111 insertions(+), 208 deletions(-)
> > create mode 100644 sysdeps/x86/tst-cet-legacy-7.c
> >
> > diff --git a/sysdeps/unix/sysv/linux/x86/dl-cet.h b/sysdeps/unix/sysv/linux/x86/dl-cet.h
> > index 9b2aaa238c..ae97a433a2 100644
> > --- a/sysdeps/unix/sysv/linux/x86/dl-cet.h
> > +++ b/sysdeps/unix/sysv/linux/x86/dl-cet.h
> > @@ -18,26 +18,6 @@
> > #include <sys/prctl.h>
> > #include <asm/prctl.h>
> >
> > -static inline int __attribute__ ((always_inline))
> > -dl_cet_allocate_legacy_bitmap (unsigned long *legacy_bitmap)
> > -{
> > - /* Allocate legacy bitmap. */
> > -#ifdef __LP64__
> > - return (int) INTERNAL_SYSCALL_CALL (arch_prctl,
> > - ARCH_CET_LEGACY_BITMAP, legacy_bitmap);
> > -#else
> > - unsigned long long legacy_bitmap_u64[2];
> > - int res = INTERNAL_SYSCALL_CALL (arch_prctl,
> > - ARCH_CET_LEGACY_BITMAP, legacy_bitmap_u64);
> > - if (res == 0)
> > - {
> > - legacy_bitmap[0] = legacy_bitmap_u64[0];
> > - legacy_bitmap[1] = legacy_bitmap_u64[1];
> > - }
> > - return res;
> > -#endif
> > -}
> > -
>
> OK.
>
> > static inline int __attribute__ ((always_inline))
> > dl_cet_disable_cet (unsigned int cet_feature)
> > {
> > diff --git a/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> > index f67f3299b9..45ad0b052f 100644
> > --- a/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> > +++ b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
> > @@ -24,9 +24,4 @@
> > OUT: allocated shadow stack address: *addr.
> > */
> > # define ARCH_CET_ALLOC_SHSTK 0x3004
> > -/* Return legacy region bitmap info in unsigned long long *addr:
> > - address: addr[0].
> > - size: addr[1].
> > - */
> > -# define ARCH_CET_LEGACY_BITMAP 0x3005
>
> OK.
>
> > #endif /* ARCH_CET_STATUS */
> > diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
> > index 95182a508c..ec96b59a78 100644
> > --- a/sysdeps/x86/Makefile
> > +++ b/sysdeps/x86/Makefile
> > @@ -20,7 +20,7 @@ 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-5a tst-cet-legacy-6a tst-cet-legacy-7
>
> OK.
>
> > 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 \
> > @@ -43,14 +43,15 @@ CFLAGS-tst-cet-legacy-4b.c += -fcf-protection
> > CFLAGS-tst-cet-legacy-mod-4.c += -fcf-protection=none
> > CFLAGS-tst-cet-legacy-5a.c += -fcf-protection
> > CFLAGS-tst-cet-legacy-5b.c += -fcf-protection
> > -CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=none
> > +CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=branch
> > CFLAGS-tst-cet-legacy-mod-5b.c += -fcf-protection
> > CFLAGS-tst-cet-legacy-mod-5c.c += -fcf-protection
> > CFLAGS-tst-cet-legacy-6a.c += -fcf-protection
> > CFLAGS-tst-cet-legacy-6b.c += -fcf-protection
> > -CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=none
> > +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
>
> OK.
>
> >
> > $(objpfx)tst-cet-legacy-1: $(objpfx)tst-cet-legacy-mod-1.so \
> > $(objpfx)tst-cet-legacy-mod-2.so
> > diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
> > index ca3b5849bc..b2843488be 100644
> > --- a/sysdeps/x86/dl-cet.c
> > +++ b/sysdeps/x86/dl-cet.c
> > @@ -33,63 +33,6 @@
> > # error GNU_PROPERTY_X86_FEATURE_1_SHSTK != X86_FEATURE_1_SHSTK
> > #endif
> >
> > -static int
> > -dl_cet_mark_legacy_region (struct link_map *l)
> > -{
> > - /* Mark PT_LOAD segments with PF_X in legacy code page bitmap. */
> > - size_t i, phnum = l->l_phnum;
> > - const ElfW(Phdr) *phdr = l->l_phdr;
> > -#ifdef __x86_64__
> > - typedef unsigned long long word_t;
> > -#else
> > - typedef unsigned long word_t;
> > -#endif
> > - unsigned int bits_to_set;
> > - word_t mask_to_set;
> > -#define BITS_PER_WORD (sizeof (word_t) * 8)
> > -#define BITMAP_FIRST_WORD_MASK(start) \
> > - (~((word_t) 0) << ((start) & (BITS_PER_WORD - 1)))
> > -#define BITMAP_LAST_WORD_MASK(nbits) \
> > - (~((word_t) 0) >> (-(nbits) & (BITS_PER_WORD - 1)))
> > -
> > - word_t *bitmap = (word_t *) GL(dl_x86_legacy_bitmap)[0];
> > - word_t bitmap_size = GL(dl_x86_legacy_bitmap)[1];
> > - word_t *p;
> > - size_t page_size = GLRO(dl_pagesize);
> > -
> > - for (i = 0; i < phnum; i++)
> > - if (phdr[i].p_type == PT_LOAD && (phdr[i].p_flags & PF_X))
> > - {
> > - /* One bit in legacy bitmap represents a page. */
> > - ElfW(Addr) start = (phdr[i].p_vaddr + l->l_addr) / page_size;
> > - ElfW(Addr) len = (phdr[i].p_memsz + page_size - 1) / page_size;
> > - ElfW(Addr) end = start + len;
> > -
> > - if ((end / 8) > bitmap_size)
> > - return -EINVAL;
> > -
> > - p = bitmap + (start / BITS_PER_WORD);
> > - bits_to_set = BITS_PER_WORD - (start % BITS_PER_WORD);
> > - mask_to_set = BITMAP_FIRST_WORD_MASK (start);
> > -
> > - while (len >= bits_to_set)
> > - {
> > - *p |= mask_to_set;
> > - len -= bits_to_set;
> > - bits_to_set = BITS_PER_WORD;
> > - mask_to_set = ~((word_t) 0);
> > - p++;
> > - }
> > - if (len)
> > - {
> > - mask_to_set &= BITMAP_LAST_WORD_MASK (end);
> > - *p |= mask_to_set;
> > - }
> > - }
> > -
> > - return 0;
> > -}
> > -
>
> OK.
>
> > /* Check if object M is compatible with CET. */
> >
> > static void
> > @@ -117,6 +60,8 @@ dl_cet_check (struct link_map *m, const char *program)
> > if (ibt_enabled || shstk_enabled)
> > {
> > struct link_map *l = NULL;
> > + unsigned int ibt_legacy = 0, shstk_legacy = 0;
> > + bool found_ibt_legacy = false, found_shstk_legacy = false;
>
> OK.
>
> >
> > /* Check if IBT and SHSTK are enabled in object. */
> > bool enable_ibt = (ibt_enabled
> > @@ -142,10 +87,7 @@ dl_cet_check (struct link_map *m, const char *program)
> > support IBT nor SHSTK. */
> > if (enable_ibt || enable_shstk)
> > {
> > - int res;
> > unsigned int i;
> > - unsigned int first_legacy, last_legacy;
> > - bool need_legacy_bitmap = false;
>
> OK.
>
> >
> > i = m->l_searchlist.r_nlist;
> > while (i-- > 0)
> > @@ -167,91 +109,25 @@ dl_cet_check (struct link_map *m, const char *program)
> > continue;
> > #endif
> >
> > - if (enable_ibt
> > - && enable_ibt_type != CET_ALWAYS_ON
> > - && !(l->l_cet & lc_ibt))
> > + /* IBT is enabled only if it is enabled in executable as
> > + well as all shared objects. */
> > + enable_ibt &= (enable_ibt_type == CET_ALWAYS_ON
> > + || (l->l_cet & lc_ibt) != 0);
> > + if (!found_ibt_legacy && enable_ibt != ibt_enabled)
> > {
> > - /* Remember the first and last legacy objects. */
> > - if (!need_legacy_bitmap)
> > - last_legacy = i;
> > - first_legacy = i;
> > - need_legacy_bitmap = true;
> > + found_ibt_legacy = true;
> > + ibt_legacy = i;
>
> OK.
>
> > }
> >
> > /* SHSTK is enabled only if it is enabled in executable as
> > well as all shared objects. */
> > enable_shstk &= (enable_shstk_type == CET_ALWAYS_ON
> > || (l->l_cet & lc_shstk) != 0);
> > - }
> > -
> > - if (need_legacy_bitmap)
> > - {
> > - if (GL(dl_x86_legacy_bitmap)[0])
> > - {
> > - /* Change legacy bitmap to writable. */
> > - if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
> > - GL(dl_x86_legacy_bitmap)[1],
> > - PROT_READ | PROT_WRITE) < 0)
> > - {
> > -mprotect_failure:
> > - if (program)
> > - _dl_fatal_printf ("%s: mprotect legacy bitmap failed\n",
> > - l->l_name);
> > - else
> > - _dl_signal_error (EINVAL, l->l_name, "dlopen",
> > - N_("mprotect legacy bitmap failed"));
> > - }
> > - }
> > - else
> > + if (enable_shstk != shstk_enabled)
>
> OK.
>
> > {
> > - /* Allocate legacy bitmap. */
> > - int res = dl_cet_allocate_legacy_bitmap
> > - (GL(dl_x86_legacy_bitmap));
> > - if (res != 0)
> > - {
> > - if (program)
> > - _dl_fatal_printf ("%s: legacy bitmap isn't available\n",
> > - l->l_name);
> > - else
> > - _dl_signal_error (EINVAL, l->l_name, "dlopen",
> > - N_("legacy bitmap isn't available"));
> > - }
> > + found_shstk_legacy = true;
> > + shstk_legacy = i;
>
> OK.
>
> > }
> > -
> > - /* Put legacy shared objects in legacy bitmap. */
> > - for (i = first_legacy; i <= last_legacy; i++)
> > - {
> > - l = m->l_initfini[i];
> > -
> > - if (l->l_init_called || (l->l_cet & lc_ibt))
> > - continue;
> > -
> > -#ifdef SHARED
> > - if (l == &GL(dl_rtld_map)
> > - || l->l_real == &GL(dl_rtld_map)
> > - || (program && l == m))
> > - continue;
> > -#endif
> > -
> > - /* If IBT is enabled in executable and IBT isn't enabled
> > - in this shard object, mark PT_LOAD segments with PF_X
> > - in legacy code page bitmap. */
> > - res = dl_cet_mark_legacy_region (l);
> > - if (res != 0)
> > - {
> > - if (program)
> > - _dl_fatal_printf ("%s: failed to mark legacy code region\n",
> > - l->l_name);
> > - else
> > - _dl_signal_error (-res, l->l_name, "dlopen",
> > - N_("failed to mark legacy code region"));
> > - }
> > - }
> > -
> > - /* Change legacy bitmap to read-only. */
> > - if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
> > - GL(dl_x86_legacy_bitmap)[1], PROT_READ) < 0)
> > - goto mprotect_failure;
>
> OK.
>
> > }
> > }
> >
> > @@ -259,23 +135,40 @@ mprotect_failure:
> >
> > if (enable_ibt != ibt_enabled || enable_shstk != shstk_enabled)
> > {
> > - if (!program
> > - && enable_shstk_type != CET_PERMISSIVE)
> > + if (!program)
> > {
> > - /* When SHSTK is enabled, we can't dlopening a shared
> > - object without SHSTK. */
> > - if (enable_shstk != shstk_enabled)
> > - _dl_signal_error (EINVAL, l->l_name, "dlopen",
> > - N_("shadow stack isn't enabled"));
> > - return;
> > + if (enable_ibt_type != CET_PERMISSIVE)
> > + {
> > + /* When IBT is enabled, we cannot dlopen a shared
> > + object without IBT. */
> > + if (found_ibt_legacy)
> > + _dl_signal_error (0,
> > + m->l_initfini[ibt_legacy]->l_name,
> > + "dlopen",
> > + N_("rebuilt with IBT support needed"));
> > + }
>
> Suggest:
> "rebuild shared object with IBT support enabled"
Fixed.
>
> > +
> > + if (enable_shstk_type != CET_PERMISSIVE)
> > + {
> > + /* When SHSTK is enabled, we cannot dlopen a shared
> > + object without SHSTK. */
> > + if (found_shstk_legacy)
> > + _dl_signal_error (0,
> > + m->l_initfini[shstk_legacy]->l_name,
> > + "dlopen",
> > + N_("rebuilt with SHSTK support needed"));
> > + }
>
> Suggest:
> "rebuild shared object with SHSTK support enabled"
>
Fixed.
> > +
> > + if (enable_ibt_type != CET_PERMISSIVE
> > + && enable_shstk_type != CET_PERMISSIVE)
> > + return;
> > }
> >
> > /* Disable IBT and/or SHSTK if they are enabled by kernel, but
> > disabled in executable or shared objects. */
> > unsigned int cet_feature = 0;
> >
> > - /* Disable IBT only during program startup. */
> > - if (program && !enable_ibt)
> > + if (!enable_ibt)
>
> OK.
>
> > cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
> > if (!enable_shstk)
> > cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
> > @@ -286,8 +179,14 @@ mprotect_failure:
> > if (program)
> > _dl_fatal_printf ("%s: can't disable CET\n", program);
> > else
> > - _dl_signal_error (-res, l->l_name, "dlopen",
> > - N_("can't disable CET"));
> > + {
> > + if (found_ibt_legacy)
> > + l = m->l_initfini[ibt_legacy];
> > + else
> > + l = m->l_initfini[shstk_legacy];
> > + _dl_signal_error (-res, l->l_name, "dlopen",
> > + N_("can't disable CET"));
>
> OK.
>
> > + }
> > }
> >
> > /* Clear the disabled bits in dl_x86_feature_1. */
> > @@ -297,17 +196,21 @@ mprotect_failure:
> > }
> >
> > #ifdef SHARED
> > - if (program
> > - && (!shstk_enabled
> > - || enable_shstk_type != CET_PERMISSIVE)
> > - && (ibt_enabled || shstk_enabled))
> > + if (program && (ibt_enabled || shstk_enabled))
> > {
> > - /* Lock CET if IBT or SHSTK is enabled in executable. Don't
> > - lock CET if SHSTK is enabled permissively. */
> > - int res = dl_cet_lock_cet ();
> > - if (res != 0)
> > - _dl_fatal_printf ("%s: can't lock CET\n", program);
> > + if ((!ibt_enabled
> > + || enable_ibt_type != CET_PERMISSIVE)
> > + && (!shstk_enabled
> > + || enable_shstk_type != CET_PERMISSIVE))
> > + {
> > + /* Lock CET if IBT or SHSTK is enabled in executable unless
> > + IBT or SHSTK is enabled permissively. */
> > + int res = dl_cet_lock_cet ();
> > + if (res != 0)
> > + _dl_fatal_printf ("%s: can't lock CET\n", program);
>
> OK.
>
> > + }
> >
> > + /* Set feature_1 if IBT or SHSTK is enabled in executable. */
> > cet_feature_changed = true;
> > }
> > #endif
> > diff --git a/sysdeps/x86/dl-procruntime.c b/sysdeps/x86/dl-procruntime.c
> > index fb36801f3e..5e39a38133 100644
> > --- a/sysdeps/x86/dl-procruntime.c
> > +++ b/sysdeps/x86/dl-procruntime.c
> > @@ -54,15 +54,4 @@ PROCINFO_CLASS unsigned int _dl_x86_feature_1[2]
> > # else
> > ,
> > # endif
> > -
> > -# if !defined PROCINFO_DECL && defined SHARED
> > - ._dl_x86_legacy_bitmap
> > -# else
> > -PROCINFO_CLASS unsigned long _dl_x86_legacy_bitmap[2]
> > -# endif
> > -# if !defined SHARED || defined PROCINFO_DECL
> > -;
> > -# else
> > -,
> > -# endif
>
> OK.
>
> > #endif
> > diff --git a/sysdeps/x86/tst-cet-legacy-4.c b/sysdeps/x86/tst-cet-legacy-4.c
> > index a77078afc9..a922339333 100644
> > --- a/sysdeps/x86/tst-cet-legacy-4.c
> > +++ b/sysdeps/x86/tst-cet-legacy-4.c
> > @@ -20,6 +20,9 @@
> > #include <dlfcn.h>
> > #include <stdio.h>
> > #include <stdlib.h>
> > +#include <string.h>
> > +
> > +#include <support/check.h>
> >
> > static int
> > do_test (void)
> > @@ -31,22 +34,18 @@ do_test (void)
> > h = dlopen (modname, RTLD_LAZY);
> > if (h == NULL)
> > {
> > - printf ("cannot open '%s': %s\n", modname, dlerror ());
> > - exit (1);
> > + const char *err = dlerror ();
> > + if (!strstr (err, "rebuilt with IBT support needed"))
>
> OK (needs adjustment if string is changed).
>
Fixed.
> > + FAIL_EXIT1 ("incorrect dlopen '%s' error: %s\n", modname, err);
> > + return 0;
> > }
> >
> > fp = dlsym (h, "test");
> > if (fp == NULL)
> > - {
> > - printf ("cannot get symbol 'test': %s\n", dlerror ());
> > - exit (1);
> > - }
> > + FAIL_EXIT1 ("cannot get symbol 'test': %s\n", dlerror ());
> >
> > if (fp () != 0)
> > - {
> > - puts ("test () != 0");
> > - exit (1);
> > - }
> > + FAIL_EXIT1 ("test () != 0");
> >
> > dlclose (h);
> >
> > diff --git a/sysdeps/x86/tst-cet-legacy-5.c b/sysdeps/x86/tst-cet-legacy-5.c
> > index 6c9bba06f5..350c7e41df 100644
> > --- a/sysdeps/x86/tst-cet-legacy-5.c
> > +++ b/sysdeps/x86/tst-cet-legacy-5.c
> > @@ -35,7 +35,7 @@ do_test_1 (const char *modname, bool fail)
> > if (fail)
> > {
> > const char *err = dlerror ();
> > - if (strstr (err, "shadow stack isn't enabled") == NULL)
> > + if (strstr (err, "rebuilt with SHSTK support needed") == NULL)
>
> OK (also needs adjustment)
Fixed.
>
> > {
> > printf ("incorrect dlopen '%s' error: %s\n", modname,
> > err);
> > diff --git a/sysdeps/x86/tst-cet-legacy-6.c b/sysdeps/x86/tst-cet-legacy-6.c
> > index 877e77747d..9f2748fcb6 100644
> > --- a/sysdeps/x86/tst-cet-legacy-6.c
> > +++ b/sysdeps/x86/tst-cet-legacy-6.c
> > @@ -35,7 +35,7 @@ do_test_1 (const char *modname, bool fail)
> > if (fail)
> > {
> > const char *err = dlerror ();
> > - if (strstr (err, "shadow stack isn't enabled") == NULL)
> > + if (strstr (err, "rebuilt with SHSTK support needed") == NULL)
>
> OK. (also needs adjustment)
Fixed.
>
> > {
> > printf ("incorrect dlopen '%s' error: %s\n", modname,
> > err);
> > diff --git a/sysdeps/x86/tst-cet-legacy-7.c b/sysdeps/x86/tst-cet-legacy-7.c
> > new file mode 100644
> > index 0000000000..cf4c2779ce
> > --- /dev/null
> > +++ b/sysdeps/x86/tst-cet-legacy-7.c
> > @@ -0,0 +1,36 @@
> > +/* Check compatibility of legacy executable with a JIT engine.
> > + Copyright (C) 2020 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 <sys/mman.h>
> > +#include <support/xunistd.h>
> > +
>
> Needs a pargraph explaining what this test is supposed to do.
>
Done.
> I expect this test is supposed to just pass and not fail because it's
> run with -fcf-protection=none.
Yes.
>
> What about the equivalent test to test for failure?
Added.
>
> > +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 0;
>
> OK.
>
> > +}
> > +
> > +#include <support/test-driver.c>
> > -- 2.24.1
>
>
OK for master?
Thanks.
H.J.
---
Since legacy bitmap doesn't cover jitted code generated by legacy JIT
engine, it isn't very useful. This patch removes ARCH_CET_LEGACY_BITMAP
and treats indirect branch tracking similar to shadow stack by removing
legacy bitmap support.
---
sysdeps/unix/sysv/linux/x86/dl-cet.h | 20 --
.../unix/sysv/linux/x86/include/asm/prctl.h | 5 -
sysdeps/x86/Makefile | 9 +-
sysdeps/x86/dl-cet.c | 217 +++++-------------
sysdeps/x86/dl-procruntime.c | 11 -
sysdeps/x86/tst-cet-legacy-4.c | 19 +-
sysdeps/x86/tst-cet-legacy-5.c | 3 +-
sysdeps/x86/tst-cet-legacy-6.c | 3 +-
sysdeps/x86/tst-cet-legacy-7.c | 38 +++
sysdeps/x86/tst-cet-legacy-8.c | 55 +++++
10 files changed, 172 insertions(+), 208 deletions(-)
create mode 100644 sysdeps/x86/tst-cet-legacy-7.c
create mode 100644 sysdeps/x86/tst-cet-legacy-8.c
diff --git a/sysdeps/unix/sysv/linux/x86/dl-cet.h b/sysdeps/unix/sysv/linux/x86/dl-cet.h
index 9b2aaa238c..ae97a433a2 100644
--- a/sysdeps/unix/sysv/linux/x86/dl-cet.h
+++ b/sysdeps/unix/sysv/linux/x86/dl-cet.h
@@ -18,26 +18,6 @@
#include <sys/prctl.h>
#include <asm/prctl.h>
-static inline int __attribute__ ((always_inline))
-dl_cet_allocate_legacy_bitmap (unsigned long *legacy_bitmap)
-{
- /* Allocate legacy bitmap. */
-#ifdef __LP64__
- return (int) INTERNAL_SYSCALL_CALL (arch_prctl,
- ARCH_CET_LEGACY_BITMAP, legacy_bitmap);
-#else
- unsigned long long legacy_bitmap_u64[2];
- int res = INTERNAL_SYSCALL_CALL (arch_prctl,
- ARCH_CET_LEGACY_BITMAP, legacy_bitmap_u64);
- if (res == 0)
- {
- legacy_bitmap[0] = legacy_bitmap_u64[0];
- legacy_bitmap[1] = legacy_bitmap_u64[1];
- }
- return res;
-#endif
-}
-
static inline int __attribute__ ((always_inline))
dl_cet_disable_cet (unsigned int cet_feature)
{
diff --git a/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
index f67f3299b9..45ad0b052f 100644
--- a/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
+++ b/sysdeps/unix/sysv/linux/x86/include/asm/prctl.h
@@ -24,9 +24,4 @@
OUT: allocated shadow stack address: *addr.
*/
# define ARCH_CET_ALLOC_SHSTK 0x3004
-/* Return legacy region bitmap info in unsigned long long *addr:
- address: addr[0].
- size: addr[1].
- */
-# define ARCH_CET_LEGACY_BITMAP 0x3005
#endif /* ARCH_CET_STATUS */
diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
index 95182a508c..4ffa699e5f 100644
--- a/sysdeps/x86/Makefile
+++ b/sysdeps/x86/Makefile
@@ -20,7 +20,8 @@ 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-5a tst-cet-legacy-6a tst-cet-legacy-7 \
+ tst-cet-legacy-8
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 \
@@ -43,14 +44,16 @@ CFLAGS-tst-cet-legacy-4b.c += -fcf-protection
CFLAGS-tst-cet-legacy-mod-4.c += -fcf-protection=none
CFLAGS-tst-cet-legacy-5a.c += -fcf-protection
CFLAGS-tst-cet-legacy-5b.c += -fcf-protection
-CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=none
+CFLAGS-tst-cet-legacy-mod-5a.c += -fcf-protection=branch
CFLAGS-tst-cet-legacy-mod-5b.c += -fcf-protection
CFLAGS-tst-cet-legacy-mod-5c.c += -fcf-protection
CFLAGS-tst-cet-legacy-6a.c += -fcf-protection
CFLAGS-tst-cet-legacy-6b.c += -fcf-protection
-CFLAGS-tst-cet-legacy-mod-6a.c += -fcf-protection=none
+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
$(objpfx)tst-cet-legacy-1: $(objpfx)tst-cet-legacy-mod-1.so \
$(objpfx)tst-cet-legacy-mod-2.so
diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
index ca3b5849bc..c7029f1b51 100644
--- a/sysdeps/x86/dl-cet.c
+++ b/sysdeps/x86/dl-cet.c
@@ -33,63 +33,6 @@
# error GNU_PROPERTY_X86_FEATURE_1_SHSTK != X86_FEATURE_1_SHSTK
#endif
-static int
-dl_cet_mark_legacy_region (struct link_map *l)
-{
- /* Mark PT_LOAD segments with PF_X in legacy code page bitmap. */
- size_t i, phnum = l->l_phnum;
- const ElfW(Phdr) *phdr = l->l_phdr;
-#ifdef __x86_64__
- typedef unsigned long long word_t;
-#else
- typedef unsigned long word_t;
-#endif
- unsigned int bits_to_set;
- word_t mask_to_set;
-#define BITS_PER_WORD (sizeof (word_t) * 8)
-#define BITMAP_FIRST_WORD_MASK(start) \
- (~((word_t) 0) << ((start) & (BITS_PER_WORD - 1)))
-#define BITMAP_LAST_WORD_MASK(nbits) \
- (~((word_t) 0) >> (-(nbits) & (BITS_PER_WORD - 1)))
-
- word_t *bitmap = (word_t *) GL(dl_x86_legacy_bitmap)[0];
- word_t bitmap_size = GL(dl_x86_legacy_bitmap)[1];
- word_t *p;
- size_t page_size = GLRO(dl_pagesize);
-
- for (i = 0; i < phnum; i++)
- if (phdr[i].p_type == PT_LOAD && (phdr[i].p_flags & PF_X))
- {
- /* One bit in legacy bitmap represents a page. */
- ElfW(Addr) start = (phdr[i].p_vaddr + l->l_addr) / page_size;
- ElfW(Addr) len = (phdr[i].p_memsz + page_size - 1) / page_size;
- ElfW(Addr) end = start + len;
-
- if ((end / 8) > bitmap_size)
- return -EINVAL;
-
- p = bitmap + (start / BITS_PER_WORD);
- bits_to_set = BITS_PER_WORD - (start % BITS_PER_WORD);
- mask_to_set = BITMAP_FIRST_WORD_MASK (start);
-
- while (len >= bits_to_set)
- {
- *p |= mask_to_set;
- len -= bits_to_set;
- bits_to_set = BITS_PER_WORD;
- mask_to_set = ~((word_t) 0);
- p++;
- }
- if (len)
- {
- mask_to_set &= BITMAP_LAST_WORD_MASK (end);
- *p |= mask_to_set;
- }
- }
-
- return 0;
-}
-
/* Check if object M is compatible with CET. */
static void
@@ -117,6 +60,8 @@ dl_cet_check (struct link_map *m, const char *program)
if (ibt_enabled || shstk_enabled)
{
struct link_map *l = NULL;
+ unsigned int ibt_legacy = 0, shstk_legacy = 0;
+ bool found_ibt_legacy = false, found_shstk_legacy = false;
/* Check if IBT and SHSTK are enabled in object. */
bool enable_ibt = (ibt_enabled
@@ -142,10 +87,7 @@ dl_cet_check (struct link_map *m, const char *program)
support IBT nor SHSTK. */
if (enable_ibt || enable_shstk)
{
- int res;
unsigned int i;
- unsigned int first_legacy, last_legacy;
- bool need_legacy_bitmap = false;
i = m->l_searchlist.r_nlist;
while (i-- > 0)
@@ -167,91 +109,25 @@ dl_cet_check (struct link_map *m, const char *program)
continue;
#endif
- if (enable_ibt
- && enable_ibt_type != CET_ALWAYS_ON
- && !(l->l_cet & lc_ibt))
+ /* IBT is enabled only if it is enabled in executable as
+ well as all shared objects. */
+ enable_ibt &= (enable_ibt_type == CET_ALWAYS_ON
+ || (l->l_cet & lc_ibt) != 0);
+ if (!found_ibt_legacy && enable_ibt != ibt_enabled)
{
- /* Remember the first and last legacy objects. */
- if (!need_legacy_bitmap)
- last_legacy = i;
- first_legacy = i;
- need_legacy_bitmap = true;
+ found_ibt_legacy = true;
+ ibt_legacy = i;
}
/* SHSTK is enabled only if it is enabled in executable as
well as all shared objects. */
enable_shstk &= (enable_shstk_type == CET_ALWAYS_ON
|| (l->l_cet & lc_shstk) != 0);
- }
-
- if (need_legacy_bitmap)
- {
- if (GL(dl_x86_legacy_bitmap)[0])
- {
- /* Change legacy bitmap to writable. */
- if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
- GL(dl_x86_legacy_bitmap)[1],
- PROT_READ | PROT_WRITE) < 0)
- {
-mprotect_failure:
- if (program)
- _dl_fatal_printf ("%s: mprotect legacy bitmap failed\n",
- l->l_name);
- else
- _dl_signal_error (EINVAL, l->l_name, "dlopen",
- N_("mprotect legacy bitmap failed"));
- }
- }
- else
+ if (enable_shstk != shstk_enabled)
{
- /* Allocate legacy bitmap. */
- int res = dl_cet_allocate_legacy_bitmap
- (GL(dl_x86_legacy_bitmap));
- if (res != 0)
- {
- if (program)
- _dl_fatal_printf ("%s: legacy bitmap isn't available\n",
- l->l_name);
- else
- _dl_signal_error (EINVAL, l->l_name, "dlopen",
- N_("legacy bitmap isn't available"));
- }
+ found_shstk_legacy = true;
+ shstk_legacy = i;
}
-
- /* Put legacy shared objects in legacy bitmap. */
- for (i = first_legacy; i <= last_legacy; i++)
- {
- l = m->l_initfini[i];
-
- if (l->l_init_called || (l->l_cet & lc_ibt))
- continue;
-
-#ifdef SHARED
- if (l == &GL(dl_rtld_map)
- || l->l_real == &GL(dl_rtld_map)
- || (program && l == m))
- continue;
-#endif
-
- /* If IBT is enabled in executable and IBT isn't enabled
- in this shard object, mark PT_LOAD segments with PF_X
- in legacy code page bitmap. */
- res = dl_cet_mark_legacy_region (l);
- if (res != 0)
- {
- if (program)
- _dl_fatal_printf ("%s: failed to mark legacy code region\n",
- l->l_name);
- else
- _dl_signal_error (-res, l->l_name, "dlopen",
- N_("failed to mark legacy code region"));
- }
- }
-
- /* Change legacy bitmap to read-only. */
- if (__mprotect ((void *) GL(dl_x86_legacy_bitmap)[0],
- GL(dl_x86_legacy_bitmap)[1], PROT_READ) < 0)
- goto mprotect_failure;
}
}
@@ -259,23 +135,40 @@ mprotect_failure:
if (enable_ibt != ibt_enabled || enable_shstk != shstk_enabled)
{
- if (!program
- && enable_shstk_type != CET_PERMISSIVE)
+ if (!program)
{
- /* When SHSTK is enabled, we can't dlopening a shared
- object without SHSTK. */
- if (enable_shstk != shstk_enabled)
- _dl_signal_error (EINVAL, l->l_name, "dlopen",
- N_("shadow stack isn't enabled"));
- return;
+ if (enable_ibt_type != CET_PERMISSIVE)
+ {
+ /* When IBT is enabled, we cannot dlopen a shared
+ object without IBT. */
+ if (found_ibt_legacy)
+ _dl_signal_error (0,
+ m->l_initfini[ibt_legacy]->l_name,
+ "dlopen",
+ N_("rebuild shared object with IBT support enabled"));
+ }
+
+ if (enable_shstk_type != CET_PERMISSIVE)
+ {
+ /* When SHSTK is enabled, we cannot dlopen a shared
+ object without SHSTK. */
+ if (found_shstk_legacy)
+ _dl_signal_error (0,
+ m->l_initfini[shstk_legacy]->l_name,
+ "dlopen",
+ N_("rebuild shared object with SHSTK support enabled"));
+ }
+
+ if (enable_ibt_type != CET_PERMISSIVE
+ && enable_shstk_type != CET_PERMISSIVE)
+ return;
}
/* Disable IBT and/or SHSTK if they are enabled by kernel, but
disabled in executable or shared objects. */
unsigned int cet_feature = 0;
- /* Disable IBT only during program startup. */
- if (program && !enable_ibt)
+ if (!enable_ibt)
cet_feature |= GNU_PROPERTY_X86_FEATURE_1_IBT;
if (!enable_shstk)
cet_feature |= GNU_PROPERTY_X86_FEATURE_1_SHSTK;
@@ -286,8 +179,14 @@ mprotect_failure:
if (program)
_dl_fatal_printf ("%s: can't disable CET\n", program);
else
- _dl_signal_error (-res, l->l_name, "dlopen",
- N_("can't disable CET"));
+ {
+ if (found_ibt_legacy)
+ l = m->l_initfini[ibt_legacy];
+ else
+ l = m->l_initfini[shstk_legacy];
+ _dl_signal_error (-res, l->l_name, "dlopen",
+ N_("can't disable CET"));
+ }
}
/* Clear the disabled bits in dl_x86_feature_1. */
@@ -297,17 +196,21 @@ mprotect_failure:
}
#ifdef SHARED
- if (program
- && (!shstk_enabled
- || enable_shstk_type != CET_PERMISSIVE)
- && (ibt_enabled || shstk_enabled))
+ if (program && (ibt_enabled || shstk_enabled))
{
- /* Lock CET if IBT or SHSTK is enabled in executable. Don't
- lock CET if SHSTK is enabled permissively. */
- int res = dl_cet_lock_cet ();
- if (res != 0)
- _dl_fatal_printf ("%s: can't lock CET\n", program);
+ if ((!ibt_enabled
+ || enable_ibt_type != CET_PERMISSIVE)
+ && (!shstk_enabled
+ || enable_shstk_type != CET_PERMISSIVE))
+ {
+ /* Lock CET if IBT or SHSTK is enabled in executable unless
+ IBT or SHSTK is enabled permissively. */
+ int res = dl_cet_lock_cet ();
+ if (res != 0)
+ _dl_fatal_printf ("%s: can't lock CET\n", program);
+ }
+ /* Set feature_1 if IBT or SHSTK is enabled in executable. */
cet_feature_changed = true;
}
#endif
diff --git a/sysdeps/x86/dl-procruntime.c b/sysdeps/x86/dl-procruntime.c
index fb36801f3e..5e39a38133 100644
--- a/sysdeps/x86/dl-procruntime.c
+++ b/sysdeps/x86/dl-procruntime.c
@@ -54,15 +54,4 @@ PROCINFO_CLASS unsigned int _dl_x86_feature_1[2]
# else
,
# endif
-
-# if !defined PROCINFO_DECL && defined SHARED
- ._dl_x86_legacy_bitmap
-# else
-PROCINFO_CLASS unsigned long _dl_x86_legacy_bitmap[2]
-# endif
-# if !defined SHARED || defined PROCINFO_DECL
-;
-# else
-,
-# endif
#endif
diff --git a/sysdeps/x86/tst-cet-legacy-4.c b/sysdeps/x86/tst-cet-legacy-4.c
index a77078afc9..ee54b878ed 100644
--- a/sysdeps/x86/tst-cet-legacy-4.c
+++ b/sysdeps/x86/tst-cet-legacy-4.c
@@ -20,6 +20,9 @@
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
+#include <string.h>
+
+#include <support/check.h>
static int
do_test (void)
@@ -31,22 +34,18 @@ do_test (void)
h = dlopen (modname, RTLD_LAZY);
if (h == NULL)
{
- printf ("cannot open '%s': %s\n", modname, dlerror ());
- exit (1);
+ const char *err = dlerror ();
+ if (!strstr (err, "rebuild shared object with IBT support enabled"))
+ FAIL_EXIT1 ("incorrect dlopen '%s' error: %s\n", modname, err);
+ return 0;
}
fp = dlsym (h, "test");
if (fp == NULL)
- {
- printf ("cannot get symbol 'test': %s\n", dlerror ());
- exit (1);
- }
+ FAIL_EXIT1 ("cannot get symbol 'test': %s\n", dlerror ());
if (fp () != 0)
- {
- puts ("test () != 0");
- exit (1);
- }
+ FAIL_EXIT1 ("test () != 0");
dlclose (h);
diff --git a/sysdeps/x86/tst-cet-legacy-5.c b/sysdeps/x86/tst-cet-legacy-5.c
index 6c9bba06f5..e2e95b6749 100644
--- a/sysdeps/x86/tst-cet-legacy-5.c
+++ b/sysdeps/x86/tst-cet-legacy-5.c
@@ -35,7 +35,8 @@ do_test_1 (const char *modname, bool fail)
if (fail)
{
const char *err = dlerror ();
- if (strstr (err, "shadow stack isn't enabled") == NULL)
+ if (strstr (err, "rebuild shared object with SHSTK support enabled")
+ == NULL)
{
printf ("incorrect dlopen '%s' error: %s\n", modname,
err);
diff --git a/sysdeps/x86/tst-cet-legacy-6.c b/sysdeps/x86/tst-cet-legacy-6.c
index 877e77747d..bdbbb9075f 100644
--- a/sysdeps/x86/tst-cet-legacy-6.c
+++ b/sysdeps/x86/tst-cet-legacy-6.c
@@ -35,7 +35,8 @@ do_test_1 (const char *modname, bool fail)
if (fail)
{
const char *err = dlerror ();
- if (strstr (err, "shadow stack isn't enabled") == NULL)
+ if (strstr (err, "rebuild shared object with SHSTK support enabled")
+ == NULL)
{
printf ("incorrect dlopen '%s' error: %s\n", modname,
err);
diff --git a/sysdeps/x86/tst-cet-legacy-7.c b/sysdeps/x86/tst-cet-legacy-7.c
new file mode 100644
index 0000000000..58bcb29a5f
--- /dev/null
+++ b/sysdeps/x86/tst-cet-legacy-7.c
@@ -0,0 +1,38 @@
+/* Check compatibility of legacy executable with a JIT engine.
+ Copyright (C) 2020 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 <sys/mman.h>
+#include <support/xunistd.h>
+
+/* Check that mmapped legacy code works with -fcf-protection=none. */
+
+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 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/x86/tst-cet-legacy-8.c b/sysdeps/x86/tst-cet-legacy-8.c
new file mode 100644
index 0000000000..b14b2a7290
--- /dev/null
+++ b/sysdeps/x86/tst-cet-legacy-8.c
@@ -0,0 +1,55 @@
+/* Check incompatibility with legacy JIT engine.
+ Copyright (C) 2020 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 <x86intrin.h>
+#include <sys/mman.h>
+#include <support/test-driver.h>
+#include <support/xsignal.h>
+#include <support/xunistd.h>
+
+/* Check that mmapped legacy code trigges segfault with -fcf-protection. */
+
+static void
+segfault_handler (int signo)
+{
+ exit (0);
+}
+
+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;
+
+ xsignal (SIGSEGV, segfault_handler);
+
+ 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_FAILURE;
+}
+
+#include <support/test-driver.c>
--
2.24.1
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