On Mon, Mar 9, 2020 at 3:05 AM Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * H. J. Lu:
>
> > diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
> > index ca3b5849bc..2be7a3a49f 100644
> > --- a/sysdeps/x86/dl-cet.c
> > +++ b/sysdeps/x86/dl-cet.c
>
> > + /* 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);
>
> As a general comment, I think we should add more logging as to way
> processes lose protection. But that does not need to happen with this
> patch.
>
> > + /* When IBT is enabled, we can't dlopening a shared
> > + object without IBT. */
>
> “we cannot dlopen”
Fixed.
> > + if (enable_ibt != ibt_enabled)
> > + _dl_signal_error (EINVAL, l->l_name, "dlopen",
> > + N_("indirect branch tracking isn't enabled"));
>
> 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
>
> > + /* 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"));
>
> See above.
Also fixed.
> > diff --git a/sysdeps/x86/tst-cet-legacy-7.c b/sysdeps/x86/tst-cet-legacy-7.c
> > new file mode 100644
> > index 0000000000..e6f5d6f145
> > --- /dev/null
> > +++ b/sysdeps/x86/tst-cet-legacy-7.c
>
> > + funcp = mmap (NULL, 0x1000, PROT_EXEC | PROT_READ | PROT_WRITE,
> > + MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
> > + if (funcp == MAP_FAILED)
> > + FAIL_EXIT1 ("mmap failed (errno=%d)", errno);
>
> You could use xmmap here.
Fixed,
> Rest of the patch looks okay to me.
Here is the updated patch. OK for master?
Thanks.
--
H.J.
From 3fdfdca97bc103f633ff1f9ee7aa0a5bc9fa5748 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 25 Jun 2019 09:50:52 -0700
Subject: [PATCH] x86: Remove ARCH_CET_LEGACY_BITMAP [BZ #25397]
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
(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.
---
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-7.c | 36 +++
7 files changed, 109 insertions(+), 206 deletions(-)
create mode 100644 sysdeps/x86/tst-cet-legacy-7.c
@@ -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)
{
@@ -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 */
@@ -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
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
$(objpfx)tst-cet-legacy-1: $(objpfx)tst-cet-legacy-mod-1.so \
$(objpfx)tst-cet-legacy-mod-2.so
@@ -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 (EINVAL,
+ m->l_initfini[ibt_legacy]->l_name,
+ "dlopen",
+ N_("indirect branch tracking isn't 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 (EINVAL,
+ m->l_initfini[shstk_legacy]->l_name,
+ "dlopen",
+ N_("shadow stack isn't 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
@@ -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
@@ -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, "indirect branch tracking isn't 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);
new file mode 100644
@@ -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>
+
+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>
--
2.24.1