From 95bd8aadf02ee95bbc9a05f37e88c78430027733 Mon Sep 17 00:00:00 2001 From: Christian Franke Date: Fri, 26 Jan 2024 17:20:37 +0100 Subject: [PATCH] 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 --- newlib/libc/include/ssp/ssp.h | 11 ++++++++++- newlib/libc/include/ssp/string.h | 4 ++-- newlib/libc/include/ssp/strings.h | 4 ++-- newlib/libc/include/sys/features.h | 12 +++++++++--- 4 files changed, 23 insertions(+), 8 deletions(-) diff --git a/newlib/libc/include/ssp/ssp.h b/newlib/libc/include/ssp/ssp.h index 922908659..49ea5f2dd 100644 --- a/newlib/libc/include/ssp/ssp.h +++ b/newlib/libc/include/ssp/ssp.h @@ -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)); \ diff --git a/newlib/libc/include/ssp/string.h b/newlib/libc/include/ssp/string.h index 85c4512ac..22b52097c 100644 --- a/newlib/libc/include/ssp/string.h +++ b/newlib/libc/include/ssp/string.h @@ -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)) diff --git a/newlib/libc/include/ssp/strings.h b/newlib/libc/include/ssp/strings.h index 13adba175..be59882eb 100644 --- a/newlib/libc/include/ssp/strings.h +++ b/newlib/libc/include/ssp/strings.h @@ -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 diff --git a/newlib/libc/include/sys/features.h b/newlib/libc/include/sys/features.h index a7d4bc52d..6a925c87e 100644 --- a/newlib/libc/include/sys/features.h +++ b/newlib/libc/include/sys/features.h @@ -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 -- 2.43.0