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[PATCH 02/12] Do not stack-protect ifunc resolvers.
- From: Nix <nix at esperi dot org dot uk>
- To: libc-alpha at sourceware dot org
- Cc: fweimer at redhat dot com, Nick Alcock <nick dot alcock at oracle dot com>
- Date: Mon, 28 Nov 2016 12:32:18 +0000
- Subject: [PATCH 02/12] Do not stack-protect ifunc resolvers.
- Authentication-results: sourceware.org; auth=none
- References: <20161128123228.30856-1-nix@esperi.org.uk>
From: Nick Alcock <nick.alcock@oracle.com>
When dynamically linking, ifunc resolvers are called before TLS is
initialized, so they cannot be safely stack-protected.
We avoid disabling stack-protection on large numbers of files by
using __attribute__ ((__optimize__ ("-fno-stack-protector")))
to turn it off just for the resolvers themselves. (We provide
the attribute even when statically linking, because we will later
use it elsewhere too.)
v4: New.
v5: Comment fix.
v6: Don't check for __attribute__((__optimize__)).
v7: Tiny context adjustments for revisions in earlier patches.
v9: Rebase atop new ifunc_resolver work.
* config.h.in (HAVE_CC_NO_STACK_PROTECTOR): New macro.
* include/libc-symbols.h (inhibit_stack_protector): New macro.
(__ifunc_resolver): Use it.
* elf/ifuncdep2.c (foo1_ifunc): Add inhibit_stack_protector.
(foo2_ifunc): Likewise.
(foo3_ifunc): Likewise.
* elf/ifuncmain6pie.c (foo_ifunc): Likewise.
* elf/ifuncmain7.c (foo_ifunc): Likewise.
* elf/ifuncmod1.c (foo_ifunc): Likewise.
(foo_hidden_ifunc): Likewise.
(foo_protected_ifunc): Likewise.
* elf/ifuncmod5.c (foo_ifunc): Likewise.
(foo_hidden_ifunc): Likewise.
(foo_protected_ifunc): Likewise.
* sysdeps/x86_64/ifuncmod8.c (foo_ifunc): Likewise.
* sysdeps/generic/ifunc-sel.h (ifunc_sel): Likewise.
(ifunc_one): Likewise.
* sysdeps/nacl/nacl_interface_query.c [SHARED]
(nacl_interface_query_ifunc): Likewise.
* sysdeps/powerpc/ifunc-sel.h (ifunc_sel): Likewise.
(ifunc_one): Likewise.
* sysdeps/unix/make-syscalls.sh: Likewise.
* sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
(gettimeofday_ifunc): Likewise.
* sysdeps/unix/sysv/linux/x86/gettimeofday.c (gettimeofday_ifunc):
Likewise.
* sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c (getcpu_ifunc):
Likewise.
---
config.h.in | 4 ++++
configure.ac | 1 +
elf/ifuncdep2.c | 3 +++
elf/ifuncmain6pie.c | 1 +
elf/ifuncmain7.c | 1 +
elf/ifuncmod1.c | 3 +++
elf/ifuncmod5.c | 3 +++
include/libc-symbols.h | 12 +++++++++++-
sysdeps/generic/ifunc-sel.h | 2 ++
sysdeps/nacl/nacl_interface_query.c | 1 +
sysdeps/powerpc/ifunc-sel.h | 2 ++
sysdeps/unix/make-syscalls.sh | 1 +
sysdeps/unix/sysv/linux/powerpc/gettimeofday.c | 1 +
sysdeps/unix/sysv/linux/x86/gettimeofday.c | 1 +
sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c | 1 +
sysdeps/x86_64/ifuncmod8.c | 1 +
16 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/config.h.in b/config.h.in
index 1b58612..b42c4d8 100644
--- a/config.h.in
+++ b/config.h.in
@@ -48,6 +48,10 @@
/* Define if compiler accepts -ftree-loop-distribute-patterns. */
#undef HAVE_CC_INHIBIT_LOOP_TO_LIBCALL
+/* Define if compiler accepts -fno-stack-protector in an
+ __attribute__((__optimize__)). */
+#undef HAVE_CC_NO_STACK_PROTECTOR
+
/* The level of stack protection in use for glibc as a whole. */
#undef STACK_PROTECTOR_LEVEL
diff --git a/configure.ac b/configure.ac
index 859f90b..da37319 100644
--- a/configure.ac
+++ b/configure.ac
@@ -639,6 +639,7 @@ stack_protector=
no_stack_protector=
if test "$libc_cv_ssp" = yes; then
no_stack_protector="-fno-stack-protector"
+ AC_DEFINE(HAVE_CC_NO_STACK_PROTECTOR)
fi
if test "$enable_stack_protector" = yes && test "$libc_cv_ssp" = yes; then
diff --git a/elf/ifuncdep2.c b/elf/ifuncdep2.c
index 6e66d31..d87d61d 100644
--- a/elf/ifuncdep2.c
+++ b/elf/ifuncdep2.c
@@ -32,6 +32,7 @@ void * foo1_ifunc (void) __asm__ ("foo1");
__asm__(".type foo1, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo1_ifunc (void)
{
return ifunc_sel (one, minus_one, zero);
@@ -41,6 +42,7 @@ void * foo2_ifunc (void) __asm__ ("foo2");
__asm__(".type foo2, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo2_ifunc (void)
{
return ifunc_sel (minus_one, one, zero);
@@ -50,6 +52,7 @@ void * foo3_ifunc (void) __asm__ ("foo3");
__asm__(".type foo3, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo3_ifunc (void)
{
return ifunc_sel (one, zero, minus_one);
diff --git a/elf/ifuncmain6pie.c b/elf/ifuncmain6pie.c
index 8478d4c..04faeb8 100644
--- a/elf/ifuncmain6pie.c
+++ b/elf/ifuncmain6pie.c
@@ -21,6 +21,7 @@ void * foo_ifunc (void) __asm__ ("foo");
__asm__(".type foo, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo_ifunc (void)
{
return ifunc_one (one);
diff --git a/elf/ifuncmain7.c b/elf/ifuncmain7.c
index 617a596..1e8f7ea 100644
--- a/elf/ifuncmain7.c
+++ b/elf/ifuncmain7.c
@@ -20,6 +20,7 @@ __asm__(".type foo, %gnu_indirect_function");
static void *
__attribute__ ((used))
+inhibit_stack_protector
foo_ifunc (void)
{
return ifunc_one (one);
diff --git a/elf/ifuncmod1.c b/elf/ifuncmod1.c
index 0b61380..f0bf5fb 100644
--- a/elf/ifuncmod1.c
+++ b/elf/ifuncmod1.c
@@ -36,6 +36,7 @@ void * foo_ifunc (void) __asm__ ("foo");
__asm__(".type foo, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo_ifunc (void)
{
return ifunc_sel (one, minus_one, zero);
@@ -45,6 +46,7 @@ void * foo_hidden_ifunc (void) __asm__ ("foo_hidden");
__asm__(".type foo_hidden, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo_hidden_ifunc (void)
{
return ifunc_sel (minus_one, one, zero);
@@ -54,6 +56,7 @@ void * foo_protected_ifunc (void) __asm__ ("foo_protected");
__asm__(".type foo_protected, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo_protected_ifunc (void)
{
return ifunc_sel (one, zero, minus_one);
diff --git a/elf/ifuncmod5.c b/elf/ifuncmod5.c
index 0e65a63..5a95780 100644
--- a/elf/ifuncmod5.c
+++ b/elf/ifuncmod5.c
@@ -31,6 +31,7 @@ void * foo_ifunc (void) __asm__ ("foo");
__asm__(".type foo, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo_ifunc (void)
{
return ifunc_sel (one, minus_one, zero);
@@ -40,6 +41,7 @@ void * foo_hidden_ifunc (void) __asm__ ("foo_hidden");
__asm__(".type foo_hidden, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo_hidden_ifunc (void)
{
return ifunc_sel (minus_one, one, zero);
@@ -49,6 +51,7 @@ void * foo_protected_ifunc (void) __asm__ ("foo_protected");
__asm__(".type foo_protected, %gnu_indirect_function");
void *
+inhibit_stack_protector
foo_protected_ifunc (void)
{
return ifunc_sel (one, zero, minus_one);
diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index 1c91f2e..d2f3d3a 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -338,6 +338,16 @@ for linking")
#define attribute_relro __attribute__ ((section (".data.rel.ro")))
+
+/* Used to disable stack protection in sensitive places, like ifunc
+ resolvers and early static TLS init. */
+#ifdef HAVE_CC_NO_STACK_PROTECTOR
+# define inhibit_stack_protector \
+ __attribute__ ((__optimize__ ("-fno-stack-protector")))
+#else
+# define inhibit_stack_protector
+#endif
+
/* The following macros are used for PLT bypassing within libc.so
(and if needed other libraries similarly).
First of all, you need to have the function prototyped somewhere,
@@ -739,7 +749,7 @@ for linking")
/* Helper / base macros for indirect function symbols. */
#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
- classifier void *name##_ifunc (arg) \
+ classifier inhibit_stack_protector void *name##_ifunc (arg) \
{ \
init (); \
__typeof (type_name) *res = expr; \
diff --git a/sysdeps/generic/ifunc-sel.h b/sysdeps/generic/ifunc-sel.h
index 6a27b69..1fff405 100644
--- a/sysdeps/generic/ifunc-sel.h
+++ b/sysdeps/generic/ifunc-sel.h
@@ -5,6 +5,7 @@
extern int global;
static inline void *
+inhibit_stack_protector
ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
{
switch (global)
@@ -19,6 +20,7 @@ ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
}
static inline void *
+inhibit_stack_protector
ifunc_one (int (*f1) (void))
{
return f1;
diff --git a/sysdeps/nacl/nacl_interface_query.c b/sysdeps/nacl/nacl_interface_query.c
index adf1dd4..dbaa88b 100644
--- a/sysdeps/nacl/nacl_interface_query.c
+++ b/sysdeps/nacl/nacl_interface_query.c
@@ -29,6 +29,7 @@ extern TYPE_nacl_irt_query nacl_interface_query_ifunc (void)
asm ("nacl_interface_query");
TYPE_nacl_irt_query
+inhibit_stack_protector
nacl_interface_query_ifunc (void)
{
return &__nacl_irt_query;
diff --git a/sysdeps/powerpc/ifunc-sel.h b/sysdeps/powerpc/ifunc-sel.h
index ac589bd..bdb00bf 100644
--- a/sysdeps/powerpc/ifunc-sel.h
+++ b/sysdeps/powerpc/ifunc-sel.h
@@ -5,6 +5,7 @@
extern int global;
static inline void *
+inhibit_stack_protector
ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
{
register void *ret __asm__ ("r3");
@@ -32,6 +33,7 @@ ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
}
static inline void *
+inhibit_stack_protector
ifunc_one (int (*f1) (void))
{
register void *ret __asm__ ("r3");
diff --git a/sysdeps/unix/make-syscalls.sh b/sysdeps/unix/make-syscalls.sh
index 58d165e..123553c 100644
--- a/sysdeps/unix/make-syscalls.sh
+++ b/sysdeps/unix/make-syscalls.sh
@@ -287,6 +287,7 @@ while read file srcfile caller syscall args strong weak; do
(echo '#include <dl-vdso.h>'; \\
echo 'extern void *${strong}_ifunc (void) __asm ("${strong}");'; \\
echo 'void *'; \\
+ echo 'inhibit_stack_protector'; \\
echo '${strong}_ifunc (void)'; \\
echo '{'; \\
echo ' PREPARE_VERSION_KNOWN (symver, ${vdso_symver});'; \\
diff --git a/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c b/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
index 16c00d7..46608ee 100644
--- a/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/powerpc/gettimeofday.c
@@ -33,6 +33,7 @@
# undef __gettimeofday
int
+inhibit_stack_protector
__gettimeofday_vsyscall (struct timeval *tv, struct timezone *tz)
{
return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
diff --git a/sysdeps/unix/sysv/linux/x86/gettimeofday.c b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
index c82452f..a419c4d 100644
--- a/sysdeps/unix/sysv/linux/x86/gettimeofday.c
+++ b/sysdeps/unix/sysv/linux/x86/gettimeofday.c
@@ -24,6 +24,7 @@
# include <errno.h>
static int
+inhibit_stack_protector
__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
{
return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c b/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c
index cbac4b3..8436f9d 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c
@@ -21,6 +21,7 @@
void *getcpu_ifunc (void) __asm__ ("__getcpu");
void *
+inhibit_stack_protector
getcpu_ifunc (void)
{
PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
diff --git a/sysdeps/x86_64/ifuncmod8.c b/sysdeps/x86_64/ifuncmod8.c
index c004367..7c06562 100644
--- a/sysdeps/x86_64/ifuncmod8.c
+++ b/sysdeps/x86_64/ifuncmod8.c
@@ -28,6 +28,7 @@ foo_impl (float x)
}
void *
+inhibit_stack_protector
foo_ifunc (void)
{
__m128i xmm = _mm_set1_epi32 (-1);
--
2.10.1.208.gbec66bc