ssp: add support for _FORTIFY_SOURCE=3

If specified, use __builtin_dynamic_object_size() instead of
__builtin_object_size() if supported (GCC 12.0 or later).
This enables buffer overflow checks if the buffer size is non-const
but known during runtime.
Use new macro __ssp_bos_known() instead of the (bos(p) != (size_t)-1)
checks.  The latter is no longer a compile time constant in all cases.
This avoids the generation of unused code.

Signed-off-by: Christian Franke <christian.franke@t-online.de>
This commit is contained in:
Christian Franke 2024-01-26 17:20:37 +01:00 committed by Corinna Vinschen
parent 030a762535
commit 497e6eb2c0
4 changed files with 23 additions and 8 deletions

View File

@ -43,11 +43,20 @@
#define __ssp_inline extern __inline__ __attribute__((__always_inline__, __gnu_inline__))
#if __SSP_FORTIFY_LEVEL > 2
#define __ssp_bos(ptr) __builtin_dynamic_object_size(ptr, 1)
#define __ssp_bos0(ptr) __builtin_dynamic_object_size(ptr, 0)
#define __ssp_bos_known(ptr) \
(__builtin_object_size(ptr, 0) != (size_t)-1 \
|| !__builtin_constant_p(__ssp_bos(ptr)))
#else
#define __ssp_bos(ptr) __builtin_object_size(ptr, __SSP_FORTIFY_LEVEL > 1)
#define __ssp_bos0(ptr) __builtin_object_size(ptr, 0)
#define __ssp_bos_known(ptr) (__ssp_bos0(ptr) != (size_t)-1)
#endif
#define __ssp_check(buf, len, bos) \
if (bos(buf) != (size_t)-1 && len > bos(buf)) \
if (__ssp_bos_known(buf) && len > bos(buf)) \
__chk_fail()
#define __ssp_decl(rtype, fun, args) \
rtype __ssp_real_(fun) args __asm__(__ASMNAME(#fun)); \

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@ -49,12 +49,12 @@ __END_DECLS
#if __SSP_FORTIFY_LEVEL > 0
#define __ssp_bos_check3(fun, dst, src, len) \
((__ssp_bos0(dst) != (size_t)-1) ? \
(__ssp_bos_known(dst) ? \
__builtin___ ## fun ## _chk(dst, src, len, __ssp_bos0(dst)) : \
__ ## fun ## _ichk(dst, src, len))
#define __ssp_bos_check2(fun, dst, src) \
((__ssp_bos0(dst) != (size_t)-1) ? \
(__ssp_bos_known(dst) ? \
__builtin___ ## fun ## _chk(dst, src, __ssp_bos0(dst)) : \
__ ## fun ## _ichk(dst, src))

View File

@ -37,11 +37,11 @@
#if __BSD_VISIBLE || __POSIX_VISIBLE <= 200112
#define bcopy(src, dst, len) \
((__ssp_bos0(dst) != (size_t)-1) ? \
(__ssp_bos_known(dst) ? \
__builtin___memmove_chk(dst, src, len, __ssp_bos0(dst)) : \
__memmove_ichk(dst, src, len))
#define bzero(dst, len) \
((__ssp_bos0(dst) != (size_t)-1) ? \
(__ssp_bos_known(dst) ? \
__builtin___memset_chk(dst, 0, len, __ssp_bos0(dst)) : \
__memset_ichk(dst, 0, len))
#endif

View File

@ -104,7 +104,7 @@ extern "C" {
* _DEFAULT_SOURCE (or none of the above)
* POSIX-1.2008 with BSD and SVr4 extensions
*
* _FORTIFY_SOURCE = 1 or 2
* _FORTIFY_SOURCE = 1, 2 or 3
* Object Size Checking function wrappers
*/
@ -247,7 +247,7 @@ extern "C" {
* GNU extensions; enabled with _GNU_SOURCE.
*
* __SSP_FORTIFY_LEVEL
* Object Size Checking; defined to 0 (off), 1, or 2.
* Object Size Checking; defined to 0 (off), 1, 2 or 3.
*
* In all cases above, "enabled by default" means either by defining
* _DEFAULT_SOURCE, or by not defining any of the public feature test macros.
@ -335,7 +335,13 @@ extern "C" {
#if _FORTIFY_SOURCE > 0 && !defined(__cplusplus) && !defined(__lint__) && \
(__OPTIMIZE__ > 0 || defined(__clang__)) && __GNUC_PREREQ__(4, 1) && \
!defined(_LIBC)
# if _FORTIFY_SOURCE > 1
# if _FORTIFY_SOURCE > 2 && defined(__has_builtin)
# if __has_builtin(__builtin_dynamic_object_size)
# define __SSP_FORTIFY_LEVEL 3
# else
# define __SSP_FORTIFY_LEVEL 2
# endif
# elif _FORTIFY_SOURCE > 1
# define __SSP_FORTIFY_LEVEL 2
# else
# define __SSP_FORTIFY_LEVEL 1