340 lines
10 KiB
C
340 lines
10 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_FORTIFY_STRING_H_
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#define _LINUX_FORTIFY_STRING_H_
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#define __FORTIFY_INLINE extern __always_inline __attribute__((gnu_inline))
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#define __RENAME(x) __asm__(#x)
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void fortify_panic(const char *name) __noreturn __cold;
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void __read_overflow(void) __compiletime_error("detected read beyond size of object (1st parameter)");
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void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)");
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void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)");
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#define __compiletime_strlen(p) \
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({ \
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unsigned char *__p = (unsigned char *)(p); \
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size_t __ret = (size_t)-1; \
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size_t __p_size = __builtin_object_size(p, 1); \
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if (__p_size != (size_t)-1) { \
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size_t __p_len = __p_size - 1; \
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if (__builtin_constant_p(__p[__p_len]) && \
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__p[__p_len] == '\0') \
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__ret = __builtin_strlen(__p); \
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} \
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__ret; \
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})
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#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
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extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
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extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
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extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
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extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
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extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
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extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
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extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
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extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
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extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
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extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
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#else
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#define __underlying_memchr __builtin_memchr
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#define __underlying_memcmp __builtin_memcmp
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#define __underlying_memcpy __builtin_memcpy
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#define __underlying_memmove __builtin_memmove
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#define __underlying_memset __builtin_memset
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#define __underlying_strcat __builtin_strcat
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#define __underlying_strcpy __builtin_strcpy
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#define __underlying_strlen __builtin_strlen
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#define __underlying_strncat __builtin_strncat
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#define __underlying_strncpy __builtin_strncpy
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#endif
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__FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 1);
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if (__builtin_constant_p(size) && p_size < size)
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__write_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __underlying_strncpy(p, q, size);
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}
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__FORTIFY_INLINE char *strcat(char *p, const char *q)
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{
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size_t p_size = __builtin_object_size(p, 1);
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if (p_size == (size_t)-1)
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return __underlying_strcat(p, q);
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if (strlcat(p, q, p_size) >= p_size)
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fortify_panic(__func__);
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return p;
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}
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extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
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__FORTIFY_INLINE __kernel_size_t strnlen(const char *p, __kernel_size_t maxlen)
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{
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size_t p_size = __builtin_object_size(p, 1);
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size_t p_len = __compiletime_strlen(p);
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size_t ret;
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/* We can take compile-time actions when maxlen is const. */
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if (__builtin_constant_p(maxlen) && p_len != (size_t)-1) {
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/* If p is const, we can use its compile-time-known len. */
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if (maxlen >= p_size)
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return p_len;
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}
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/* Do not check characters beyond the end of p. */
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ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size);
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if (p_size <= ret && maxlen != ret)
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fortify_panic(__func__);
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return ret;
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}
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/* defined after fortified strnlen to reuse it. */
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__FORTIFY_INLINE __kernel_size_t strlen(const char *p)
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{
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__kernel_size_t ret;
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size_t p_size = __builtin_object_size(p, 1);
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/* Give up if we don't know how large p is. */
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if (p_size == (size_t)-1)
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return __underlying_strlen(p);
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ret = strnlen(p, p_size);
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if (p_size <= ret)
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fortify_panic(__func__);
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return ret;
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}
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/* defined after fortified strlen to reuse it */
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extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
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__FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size)
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{
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size_t p_size = __builtin_object_size(p, 1);
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size_t q_size = __builtin_object_size(q, 1);
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size_t q_len; /* Full count of source string length. */
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size_t len; /* Count of characters going into destination. */
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if (p_size == (size_t)-1 && q_size == (size_t)-1)
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return __real_strlcpy(p, q, size);
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q_len = strlen(q);
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len = (q_len >= size) ? size - 1 : q_len;
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if (__builtin_constant_p(size) && __builtin_constant_p(q_len) && size) {
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/* Write size is always larger than destination. */
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if (len >= p_size)
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__write_overflow();
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}
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if (size) {
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if (len >= p_size)
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fortify_panic(__func__);
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__underlying_memcpy(p, q, len);
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p[len] = '\0';
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}
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return q_len;
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}
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/* defined after fortified strnlen to reuse it */
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extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);
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__FORTIFY_INLINE ssize_t strscpy(char *p, const char *q, size_t size)
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{
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size_t len;
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/* Use string size rather than possible enclosing struct size. */
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size_t p_size = __builtin_object_size(p, 1);
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size_t q_size = __builtin_object_size(q, 1);
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/* If we cannot get size of p and q default to call strscpy. */
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if (p_size == (size_t) -1 && q_size == (size_t) -1)
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return __real_strscpy(p, q, size);
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/*
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* If size can be known at compile time and is greater than
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* p_size, generate a compile time write overflow error.
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*/
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if (__builtin_constant_p(size) && size > p_size)
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__write_overflow();
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/*
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* This call protects from read overflow, because len will default to q
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* length if it smaller than size.
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*/
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len = strnlen(q, size);
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/*
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* If len equals size, we will copy only size bytes which leads to
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* -E2BIG being returned.
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* Otherwise we will copy len + 1 because of the final '\O'.
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*/
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len = len == size ? size : len + 1;
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/*
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* Generate a runtime write overflow error if len is greater than
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* p_size.
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*/
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if (len > p_size)
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fortify_panic(__func__);
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/*
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* We can now safely call vanilla strscpy because we are protected from:
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* 1. Read overflow thanks to call to strnlen().
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* 2. Write overflow thanks to above ifs.
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*/
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return __real_strscpy(p, q, len);
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}
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/* defined after fortified strlen and strnlen to reuse them */
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__FORTIFY_INLINE char *strncat(char *p, const char *q, __kernel_size_t count)
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{
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size_t p_len, copy_len;
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size_t p_size = __builtin_object_size(p, 1);
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size_t q_size = __builtin_object_size(q, 1);
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if (p_size == (size_t)-1 && q_size == (size_t)-1)
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return __underlying_strncat(p, q, count);
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p_len = strlen(p);
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copy_len = strnlen(q, count);
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if (p_size < p_len + copy_len + 1)
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fortify_panic(__func__);
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__underlying_memcpy(p + p_len, q, copy_len);
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p[p_len + copy_len] = '\0';
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return p;
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}
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__FORTIFY_INLINE void *memset(void *p, int c, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (__builtin_constant_p(size) && p_size < size)
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__write_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __underlying_memset(p, c, size);
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}
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__FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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size_t q_size = __builtin_object_size(q, 0);
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if (__builtin_constant_p(size)) {
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if (p_size < size)
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__write_overflow();
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if (q_size < size)
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__read_overflow2();
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}
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if (p_size < size || q_size < size)
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fortify_panic(__func__);
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return __underlying_memcpy(p, q, size);
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}
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__FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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size_t q_size = __builtin_object_size(q, 0);
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if (__builtin_constant_p(size)) {
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if (p_size < size)
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__write_overflow();
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if (q_size < size)
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__read_overflow2();
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}
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if (p_size < size || q_size < size)
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fortify_panic(__func__);
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return __underlying_memmove(p, q, size);
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}
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extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
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__FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (__builtin_constant_p(size) && p_size < size)
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__read_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __real_memscan(p, c, size);
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}
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__FORTIFY_INLINE int memcmp(const void *p, const void *q, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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size_t q_size = __builtin_object_size(q, 0);
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if (__builtin_constant_p(size)) {
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if (p_size < size)
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__read_overflow();
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if (q_size < size)
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__read_overflow2();
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}
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if (p_size < size || q_size < size)
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fortify_panic(__func__);
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return __underlying_memcmp(p, q, size);
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}
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__FORTIFY_INLINE void *memchr(const void *p, int c, __kernel_size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (__builtin_constant_p(size) && p_size < size)
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__read_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __underlying_memchr(p, c, size);
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}
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void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
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__FORTIFY_INLINE void *memchr_inv(const void *p, int c, size_t size)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (__builtin_constant_p(size) && p_size < size)
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__read_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __real_memchr_inv(p, c, size);
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}
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extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup);
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__FORTIFY_INLINE void *kmemdup(const void *p, size_t size, gfp_t gfp)
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{
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size_t p_size = __builtin_object_size(p, 0);
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if (__builtin_constant_p(size) && p_size < size)
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__read_overflow();
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if (p_size < size)
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fortify_panic(__func__);
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return __real_kmemdup(p, size, gfp);
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}
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/* defined after fortified strlen and memcpy to reuse them */
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__FORTIFY_INLINE char *strcpy(char *p, const char *q)
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{
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size_t p_size = __builtin_object_size(p, 1);
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size_t q_size = __builtin_object_size(q, 1);
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size_t size;
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if (p_size == (size_t)-1 && q_size == (size_t)-1)
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return __underlying_strcpy(p, q);
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size = strlen(q) + 1;
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/* Compile-time check for const size overflow. */
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if (__builtin_constant_p(size) && p_size < size)
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__write_overflow();
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/* Run-time check for dynamic size overflow. */
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if (p_size < size)
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fortify_panic(__func__);
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memcpy(p, q, size);
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return p;
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}
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/* Don't use these outside the FORITFY_SOURCE implementation */
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#undef __underlying_memchr
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#undef __underlying_memcmp
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#undef __underlying_memcpy
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#undef __underlying_memmove
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#undef __underlying_memset
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#undef __underlying_strcat
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#undef __underlying_strcpy
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#undef __underlying_strlen
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#undef __underlying_strncat
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#undef __underlying_strncpy
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#endif /* _LINUX_FORTIFY_STRING_H_ */
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