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Message-Id: <20220920192202.190793-4-keescook@chromium.org> Date: Tue, 20 Sep 2022 12:22:01 -0700 From: Kees Cook <keescook@...omium.org> To: linux-hardening@...r.kernel.org Cc: Kees Cook <keescook@...omium.org>, Nathan Chancellor <nathan@...nel.org>, Nick Desaulniers <ndesaulniers@...gle.com>, Tom Rix <trix@...hat.com>, llvm@...ts.linux.dev, Siddhesh Poyarekar <siddhesh@...plt.org>, Arnd Bergmann <arnd@...db.de>, Juergen Gross <jgross@...e.com>, Boris Ostrovsky <boris.ostrovsky@...cle.com>, Miguel Ojeda <ojeda@...nel.org>, linux-kernel@...r.kernel.org Subject: [PATCH 3/4] fortify: Convert to struct vs member helpers In preparation for adding support for __builtin_dynamic_object_size(), wrap each instance of __builtin_object_size(p, N) with either the new __struct_size(p) as __bos(p, 0), or __member_size(p) as __bos(p, 1). This will allow us to replace the definitions with __bdos() next. There are no binary differences from this change. Cc: Nathan Chancellor <nathan@...nel.org> Cc: Nick Desaulniers <ndesaulniers@...gle.com> Cc: Tom Rix <trix@...hat.com> Cc: linux-hardening@...r.kernel.org Cc: llvm@...ts.linux.dev Signed-off-by: Kees Cook <keescook@...omium.org> --- include/linux/fortify-string.h | 68 +++++++++++++++++----------------- 1 file changed, 35 insertions(+), 33 deletions(-) diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index 71c0a432c638..3f1178584d7b 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -20,7 +20,7 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning(" ({ \ unsigned char *__p = (unsigned char *)(p); \ size_t __ret = SIZE_MAX; \ - size_t __p_size = __builtin_object_size(p, 1); \ + size_t __p_size = __member_size(p); \ if (__p_size != SIZE_MAX && \ __builtin_constant_p(*__p)) { \ size_t __p_len = __p_size - 1; \ @@ -72,13 +72,15 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __underlying_memcpy(dst, src, bytes) /* - * Clang's use of __builtin_object_size() within inlines needs hinting via - * __pass_object_size(). The preference is to only ever use type 1 (member + * Clang's use of __builtin_*object_size() within inlines needs hinting via + * __pass_*object_size(). The preference is to only ever use type 1 (member * size, rather than struct size), but there remain some stragglers using * type 0 that will be converted in the future. */ -#define POS __pass_object_size(1) -#define POS0 __pass_object_size(0) +#define POS __pass_object_size(1) +#define POS0 __pass_object_size(0) +#define __struct_size(p) __builtin_object_size(p, 0) +#define __member_size(p) __builtin_object_size(p, 1) #define __compiletime_lessthan(bounds, length) ( \ __builtin_constant_p(length) && \ @@ -121,7 +123,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3) char *strncpy(char * const POS p, const char *q, __kernel_size_t size) { - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); if (__compiletime_lessthan(p_size, size)) __write_overflow(); @@ -133,7 +135,7 @@ char *strncpy(char * const POS p, const char *q, __kernel_size_t size) __FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2) char *strcat(char * const POS p, const char *q) { - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); if (p_size == SIZE_MAX) return __underlying_strcat(p, q); @@ -145,7 +147,7 @@ char *strcat(char * const POS p, const char *q) extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen); __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen) { - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); size_t p_len = __compiletime_strlen(p); size_t ret; @@ -175,7 +177,7 @@ __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1) __kernel_size_t __fortify_strlen(const char * const POS p) { __kernel_size_t ret; - size_t p_size = __builtin_object_size(p, 1); + size_t p_size = __member_size(p); /* Give up if we don't know how large p is. */ if (p_size == SIZE_MAX) @@ -190,8 +192,8 @@ __kernel_size_t __fortify_strlen(const char * const POS p) extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy); __FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size) { - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + size_t q_size = __member_size(q); size_t q_len; /* Full count of source string length. */ size_t len; /* Count of characters going into destination. */ @@ -219,8 +221,8 @@ __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, s { size_t len; /* Use string size rather than possible enclosing struct size. */ - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + size_t q_size = __member_size(q); /* If we cannot get size of p and q default to call strscpy. */ if (p_size == SIZE_MAX && q_size == SIZE_MAX) @@ -265,8 +267,8 @@ __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3) char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count) { size_t p_len, copy_len; - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + size_t q_size = __member_size(q); if (p_size == SIZE_MAX && q_size == SIZE_MAX) return __underlying_strncat(p, q, count); @@ -324,11 +326,11 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, }) /* - * __builtin_object_size() must be captured here to avoid evaluating argument - * side-effects further into the macro layers. + * __struct_size() vs __member_size() must be captured here to avoid + * evaluating argument side-effects further into the macro layers. */ #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ - __builtin_object_size(p, 0), __builtin_object_size(p, 1)) + __struct_size(p), __member_size(p)) /* * To make sure the compiler can enforce protection against buffer overflows, @@ -421,7 +423,7 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size, * fake flexible arrays, until they are all converted to * proper flexible arrays. * - * The implementation of __builtin_object_size() behaves + * The implementation of __builtin_*object_size() behaves * like sizeof() when not directly referencing a flexible * array member, which means there will be many bounds checks * that will appear at run-time, without a way for them to be @@ -487,22 +489,22 @@ __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size, */ /* - * __builtin_object_size() must be captured here to avoid evaluating argument - * side-effects further into the macro layers. + * __struct_size() vs __member_size() must be captured here to avoid + * evaluating argument side-effects further into the macro layers. */ #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ - __builtin_object_size(p, 0), __builtin_object_size(q, 0), \ - __builtin_object_size(p, 1), __builtin_object_size(q, 1), \ + __struct_size(p), __struct_size(q), \ + __member_size(p), __member_size(q), \ memcpy) #define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \ - __builtin_object_size(p, 0), __builtin_object_size(q, 0), \ - __builtin_object_size(p, 1), __builtin_object_size(q, 1), \ + __struct_size(p), __struct_size(q), \ + __member_size(p), __member_size(q), \ memmove) extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan); __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); @@ -514,8 +516,8 @@ __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size) __FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3) int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size) { - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); + size_t p_size = __struct_size(p); + size_t q_size = __struct_size(q); if (__builtin_constant_p(size)) { if (__compiletime_lessthan(p_size, size)) @@ -531,7 +533,7 @@ int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3) void *memchr(const void * const POS0 p, int c, __kernel_size_t size) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); @@ -543,7 +545,7 @@ void *memchr(const void * const POS0 p, int c, __kernel_size_t size) void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv); __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); @@ -555,7 +557,7 @@ __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup); __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __struct_size(p); if (__compiletime_lessthan(p_size, size)) __read_overflow(); @@ -568,8 +570,8 @@ __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp __FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2) char *strcpy(char * const POS p, const char * const POS q) { - size_t p_size = __builtin_object_size(p, 1); - size_t q_size = __builtin_object_size(q, 1); + size_t p_size = __member_size(p); + size_t q_size = __member_size(q); size_t size; /* If neither buffer size is known, immediately give up. */ -- 2.34.1
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