diff options
Diffstat (limited to 'include/linux/string.h')
| -rw-r--r-- | include/linux/string.h | 77 |
1 files changed, 65 insertions, 12 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index b1f3894a0a3e..4fcfb56abcf5 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -6,6 +6,7 @@ #include <linux/compiler.h> /* for inline */ #include <linux/types.h> /* for size_t */ #include <linux/stddef.h> /* for NULL */ +#include <linux/errno.h> /* for E2BIG */ #include <stdarg.h> #include <uapi/linux/string.h> @@ -266,7 +267,7 @@ void __write_overflow(void) __compiletime_error("detected write beyond size of o #if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE) -#ifdef CONFIG_KASAN +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr); extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp); extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy); @@ -292,7 +293,7 @@ extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __builtin_object_size(p, 1); if (__builtin_constant_p(size) && p_size < size) __write_overflow(); if (p_size < size) @@ -302,7 +303,7 @@ __FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size) __FORTIFY_INLINE char *strcat(char *p, const char *q) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __builtin_object_size(p, 1); if (p_size == (size_t)-1) return __underlying_strcat(p, q); if (strlcat(p, q, p_size) >= p_size) @@ -313,7 +314,7 @@ __FORTIFY_INLINE char *strcat(char *p, const char *q) __FORTIFY_INLINE __kernel_size_t strlen(const char *p) { __kernel_size_t ret; - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __builtin_object_size(p, 1); /* Work around gcc excess stack consumption issue */ if (p_size == (size_t)-1 || @@ -328,7 +329,7 @@ __FORTIFY_INLINE __kernel_size_t strlen(const char *p) 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) { - size_t p_size = __builtin_object_size(p, 0); + size_t p_size = __builtin_object_size(p, 1); __kernel_size_t ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size); if (p_size <= ret && maxlen != ret) fortify_panic(__func__); @@ -340,8 +341,8 @@ 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) { size_t ret; - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); + size_t p_size = __builtin_object_size(p, 1); + size_t q_size = __builtin_object_size(q, 1); if (p_size == (size_t)-1 && q_size == (size_t)-1) return __real_strlcpy(p, q, size); ret = strlen(q); @@ -357,12 +358,59 @@ __FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size) return ret; } +/* 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) +{ + 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); + + /* If we cannot get size of p and q default to call strscpy. */ + if (p_size == (size_t) -1 && q_size == (size_t) -1) + return __real_strscpy(p, q, size); + + /* + * If size can be known at compile time and is greater than + * p_size, generate a compile time write overflow error. + */ + if (__builtin_constant_p(size) && size > p_size) + __write_overflow(); + + /* + * This call protects from read overflow, because len will default to q + * length if it smaller than size. + */ + len = strnlen(q, size); + /* + * If len equals size, we will copy only size bytes which leads to + * -E2BIG being returned. + * Otherwise we will copy len + 1 because of the final '\O'. + */ + len = len == size ? size : len + 1; + + /* + * Generate a runtime write overflow error if len is greater than + * p_size. + */ + if (len > p_size) + fortify_panic(__func__); + + /* + * We can now safely call vanilla strscpy because we are protected from: + * 1. Read overflow thanks to call to strnlen(). + * 2. Write overflow thanks to above ifs. + */ + return __real_strscpy(p, q, len); +} + /* defined after fortified strlen and strnlen to reuse them */ __FORTIFY_INLINE char *strncat(char *p, const char *q, __kernel_size_t count) { size_t p_len, copy_len; - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); + size_t p_size = __builtin_object_size(p, 1); + size_t q_size = __builtin_object_size(q, 1); if (p_size == (size_t)-1 && q_size == (size_t)-1) return __underlying_strncat(p, q, count); p_len = strlen(p); @@ -475,11 +523,16 @@ __FORTIFY_INLINE void *kmemdup(const void *p, size_t size, gfp_t gfp) /* defined after fortified strlen and memcpy to reuse them */ __FORTIFY_INLINE char *strcpy(char *p, const char *q) { - size_t p_size = __builtin_object_size(p, 0); - size_t q_size = __builtin_object_size(q, 0); + size_t p_size = __builtin_object_size(p, 1); + size_t q_size = __builtin_object_size(q, 1); + size_t size; if (p_size == (size_t)-1 && q_size == (size_t)-1) return __underlying_strcpy(p, q); - memcpy(p, q, strlen(q) + 1); + size = strlen(q) + 1; + /* test here to use the more stringent object size */ + if (p_size < size) + fortify_panic(__func__); + memcpy(p, q, size); return p; } |