Re: [PATCH v7 5/8] fortify: Make pointer arguments const

[Nick Desaulniers]

On Tue, Feb 8, 2022 at 2:53 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>
> In preparation for using Clang's __pass_object_size attribute, make all
> the pointer arguments to the fortified string functions const. Nothing
> was changing their values anyway, so this added requirement (needed by
> __pass_object_size) requires no code changes and has no impact on
> the binary instruction output.

Gracias Señor!
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>

>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  include/linux/fortify-string.h | 26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
> index 439aad24ab3b..f874ada4b9af 100644
> --- a/include/linux/fortify-string.h
> +++ b/include/linux/fortify-string.h
> @@ -50,7 +50,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size)
>  #define __underlying_strncpy   __builtin_strncpy
>  #endif
>
> -__FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size)
> +__FORTIFY_INLINE char *strncpy(char * const p, const char *q, __kernel_size_t size)
>  {
>         size_t p_size = __builtin_object_size(p, 1);
>
> @@ -61,7 +61,7 @@ __FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size)
>         return __underlying_strncpy(p, q, size);
>  }
>
> -__FORTIFY_INLINE char *strcat(char *p, const char *q)
> +__FORTIFY_INLINE char *strcat(char * const p, const char *q)
>  {
>         size_t p_size = __builtin_object_size(p, 1);
>
> @@ -73,7 +73,7 @@ __FORTIFY_INLINE char *strcat(char *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 *p, __kernel_size_t maxlen)
> +__FORTIFY_INLINE __kernel_size_t strnlen(const char * const p, __kernel_size_t maxlen)
>  {
>         size_t p_size = __builtin_object_size(p, 1);
>         size_t p_len = __compiletime_strlen(p);
> @@ -94,7 +94,7 @@ __FORTIFY_INLINE __kernel_size_t strnlen(const char *p, __kernel_size_t maxlen)
>  }
>
>  /* defined after fortified strnlen to reuse it. */
> -__FORTIFY_INLINE __kernel_size_t strlen(const char *p)
> +__FORTIFY_INLINE __kernel_size_t strlen(const char * const p)
>  {
>         __kernel_size_t ret;
>         size_t p_size = __builtin_object_size(p, 1);
> @@ -110,7 +110,7 @@ __FORTIFY_INLINE __kernel_size_t strlen(const char *p)
>
>  /* defined after fortified strlen to reuse it */
>  extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
> -__FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size)
> +__FORTIFY_INLINE size_t strlcpy(char * const p, const char * const q, size_t size)
>  {
>         size_t p_size = __builtin_object_size(p, 1);
>         size_t q_size = __builtin_object_size(q, 1);
> @@ -137,7 +137,7 @@ __FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size)
>
>  /* defined after fortified strnlen to reuse it */
>  extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);
> -__FORTIFY_INLINE ssize_t strscpy(char *p, const char *q, size_t size)
> +__FORTIFY_INLINE ssize_t strscpy(char * const p, const char * const q, size_t size)
>  {
>         size_t len;
>         /* Use string size rather than possible enclosing struct size. */
> @@ -183,7 +183,7 @@ __FORTIFY_INLINE ssize_t strscpy(char *p, const char *q, size_t size)
>  }
>
>  /* defined after fortified strlen and strnlen to reuse them */
> -__FORTIFY_INLINE char *strncat(char *p, const char *q, __kernel_size_t count)
> +__FORTIFY_INLINE 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);
> @@ -354,7 +354,7 @@ __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size,
>                 memmove)
>
>  extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
> -__FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size)
> +__FORTIFY_INLINE void *memscan(void * const p, int c, __kernel_size_t size)
>  {
>         size_t p_size = __builtin_object_size(p, 0);
>
> @@ -365,7 +365,7 @@ __FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size)
>         return __real_memscan(p, c, size);
>  }
>
> -__FORTIFY_INLINE int memcmp(const void *p, const void *q, __kernel_size_t size)
> +__FORTIFY_INLINE 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 +381,7 @@ __FORTIFY_INLINE int memcmp(const void *p, const void *q, __kernel_size_t size)
>         return __underlying_memcmp(p, q, size);
>  }
>
> -__FORTIFY_INLINE void *memchr(const void *p, int c, __kernel_size_t size)
> +__FORTIFY_INLINE void *memchr(const void * const p, int c, __kernel_size_t size)
>  {
>         size_t p_size = __builtin_object_size(p, 0);
>
> @@ -393,7 +393,7 @@ __FORTIFY_INLINE void *memchr(const void *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 *p, int c, size_t size)
> +__FORTIFY_INLINE void *memchr_inv(const void * const p, int c, size_t size)
>  {
>         size_t p_size = __builtin_object_size(p, 0);
>
> @@ -405,7 +405,7 @@ __FORTIFY_INLINE void *memchr_inv(const void *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 *p, size_t size, gfp_t gfp)
> +__FORTIFY_INLINE void *kmemdup(const void * const p, size_t size, gfp_t gfp)
>  {
>         size_t p_size = __builtin_object_size(p, 0);
>
> @@ -417,7 +417,7 @@ __FORTIFY_INLINE void *kmemdup(const void *p, size_t size, gfp_t gfp)
>  }
>
>  /* Defined after fortified strlen to reuse it. */
> -__FORTIFY_INLINE char *strcpy(char *p, const char *q)
> +__FORTIFY_INLINE 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);
> --
> 2.30.2
>
>


-- 
Thanks,
~Nick Desaulniers