Commit 92df138a authored by Kees Cook's avatar Kees Cook
Browse files

fortify: Use __diagnose_as() for better diagnostic coverage 



In preparation for using Clang's __pass_object_size, add __diagnose_as()
attributes to mark the functions as being the same as the indicated
builtins. When __daignose_as() is available, Clang will have a more
complete ability to apply its own diagnostic analysis to callers of these
functions, as if they were the builtins themselves. Without __diagnose_as,
Clang's compile time diagnostic messages won't be as precise as they
could be, but at least users of older toolchains will still benefit from
having fortified routines.

Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20220208225350.1331628-7-keescook@chromium.org
parent 0a2b782a

include/linux/fortify-string.h

+14 −7
Original line number Diff line number Diff line
@@ -50,7 +50,8 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) 
#define __underlying_strncpy	__builtin_strncpy

#endif



__FORTIFY_INLINE char *strncpy(char * const p, const char *q, __kernel_size_t size)

__FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3)

char *strncpy(char * const p, const char *q, __kernel_size_t size)

{

	size_t p_size = __builtin_object_size(p, 1);
@@ -61,7 +62,8 @@ __FORTIFY_INLINE char *strncpy(char * const p, const char *q, __kernel_size_t si 
	return __underlying_strncpy(p, q, size);

}



__FORTIFY_INLINE char *strcat(char * const p, const char *q)

__FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2)

char *strcat(char * const p, const char *q)

{

	size_t p_size = __builtin_object_size(p, 1);
@@ -94,7 +96,8 @@ __FORTIFY_INLINE __kernel_size_t strnlen(const char * const p, __kernel_size_t m 
}



/* defined after fortified strnlen to reuse it. */

__FORTIFY_INLINE __kernel_size_t strlen(const char * const p)

__FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1)

__kernel_size_t strlen(const char * const p)

{

	__kernel_size_t ret;

	size_t p_size = __builtin_object_size(p, 1);
@@ -183,7 +186,8 @@ __FORTIFY_INLINE ssize_t strscpy(char * const p, const char * const q, size_t si 
}



/* defined after fortified strlen and strnlen to reuse them */

__FORTIFY_INLINE char *strncat(char * const p, const char * const q, __kernel_size_t count)

__FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3)

char *strncat(char * const p, const char * const q, __kernel_size_t count)

{

	size_t p_len, copy_len;

	size_t p_size = __builtin_object_size(p, 1);
@@ -365,7 +369,8 @@ __FORTIFY_INLINE void *memscan(void * const p, int c, __kernel_size_t size) 
	return __real_memscan(p, c, size);

}



__FORTIFY_INLINE int memcmp(const void * const p, const void * const q, __kernel_size_t size)

__FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3)

int memcmp(const void * const p, const void * const q, __kernel_size_t size)

{

	size_t p_size = __builtin_object_size(p, 0);

	size_t q_size = __builtin_object_size(q, 0);
@@ -381,7 +386,8 @@ __FORTIFY_INLINE int memcmp(const void * const p, const void * const q, __kernel 
	return __underlying_memcmp(p, q, size);

}



__FORTIFY_INLINE void *memchr(const void * const p, int c, __kernel_size_t size)

__FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3)

void *memchr(const void * const p, int c, __kernel_size_t size)

{

	size_t p_size = __builtin_object_size(p, 0);
@@ -417,7 +423,8 @@ __FORTIFY_INLINE void *kmemdup(const void * const p, size_t size, gfp_t gfp) 
}



/* Defined after fortified strlen to reuse it. */

__FORTIFY_INLINE char *strcpy(char * const p, const char * const q)

__FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2)

char *strcpy(char * const p, const char * const q)

{

	size_t p_size = __builtin_object_size(p, 1);

	size_t q_size = __builtin_object_size(q, 1);