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a28a6e86 FL |
1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _LINUX_FORTIFY_STRING_H_ | |
3 | #define _LINUX_FORTIFY_STRING_H_ | |
4 | ||
475ddf1f | 5 | #include <linux/bitfield.h> |
54d9469b | 6 | #include <linux/bug.h> |
67ebc3ab | 7 | #include <linux/const.h> |
311fb40a | 8 | #include <linux/limits.h> |
67ebc3ab | 9 | |
281d0c96 | 10 | #define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable |
c430f600 KC |
11 | #define __RENAME(x) __asm__(#x) |
12 | ||
475ddf1f KC |
13 | #define FORTIFY_REASON_DIR(r) FIELD_GET(BIT(0), r) |
14 | #define FORTIFY_REASON_FUNC(r) FIELD_GET(GENMASK(7, 1), r) | |
15 | #define FORTIFY_REASON(func, write) (FIELD_PREP(BIT(0), write) | \ | |
16 | FIELD_PREP(GENMASK(7, 1), func)) | |
17 | ||
26f812ba | 18 | /* Overridden by KUnit tests. */ |
4ce615e7 | 19 | #ifndef fortify_panic |
3d965b33 KC |
20 | # define fortify_panic(func, write, avail, size, retfail) \ |
21 | __fortify_panic(FORTIFY_REASON(func, write), avail, size) | |
4ce615e7 | 22 | #endif |
26f812ba KC |
23 | #ifndef fortify_warn_once |
24 | # define fortify_warn_once(x...) WARN_ONCE(x) | |
25 | #endif | |
475ddf1f KC |
26 | |
27 | #define FORTIFY_READ 0 | |
28 | #define FORTIFY_WRITE 1 | |
29 | ||
30 | #define EACH_FORTIFY_FUNC(macro) \ | |
31 | macro(strncpy), \ | |
32 | macro(strnlen), \ | |
33 | macro(strlen), \ | |
34 | macro(strscpy), \ | |
35 | macro(strlcat), \ | |
36 | macro(strcat), \ | |
37 | macro(strncat), \ | |
38 | macro(memset), \ | |
39 | macro(memcpy), \ | |
40 | macro(memmove), \ | |
41 | macro(memscan), \ | |
42 | macro(memcmp), \ | |
43 | macro(memchr), \ | |
44 | macro(memchr_inv), \ | |
45 | macro(kmemdup), \ | |
46 | macro(strcpy), \ | |
47 | macro(UNKNOWN), | |
48 | ||
49 | #define MAKE_FORTIFY_FUNC(func) FORTIFY_FUNC_##func | |
50 | ||
51 | enum fortify_func { | |
52 | EACH_FORTIFY_FUNC(MAKE_FORTIFY_FUNC) | |
53 | }; | |
54 | ||
3d965b33 KC |
55 | void __fortify_report(const u8 reason, const size_t avail, const size_t size); |
56 | void __fortify_panic(const u8 reason, const size_t avail, const size_t size) __cold __noreturn; | |
c430f600 KC |
57 | void __read_overflow(void) __compiletime_error("detected read beyond size of object (1st parameter)"); |
58 | void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)"); | |
f68f2ff9 | 59 | void __read_overflow2_field(size_t avail, size_t wanted) __compiletime_warning("detected read beyond size of field (2nd parameter); maybe use struct_group()?"); |
c430f600 | 60 | void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)"); |
f68f2ff9 | 61 | void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("detected write beyond size of field (1st parameter); maybe use struct_group()?"); |
a28a6e86 | 62 | |
95cadae3 QC |
63 | #define __compiletime_strlen(p) \ |
64 | ({ \ | |
e9a40e15 | 65 | char *__p = (char *)(p); \ |
311fb40a | 66 | size_t __ret = SIZE_MAX; \ |
21a2c74b | 67 | const size_t __p_size = __member_size(p); \ |
311fb40a | 68 | if (__p_size != SIZE_MAX && \ |
d07c0acb | 69 | __builtin_constant_p(*__p)) { \ |
95cadae3 QC |
70 | size_t __p_len = __p_size - 1; \ |
71 | if (__builtin_constant_p(__p[__p_len]) && \ | |
72 | __p[__p_len] == '\0') \ | |
73 | __ret = __builtin_strlen(__p); \ | |
74 | } \ | |
75 | __ret; \ | |
3009f891 KC |
76 | }) |
77 | ||
2e577732 AK |
78 | #if defined(__SANITIZE_ADDRESS__) |
79 | ||
80 | #if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY) | |
81 | extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset); | |
82 | extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove); | |
83 | extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy); | |
84 | #elif defined(CONFIG_KASAN_GENERIC) | |
85 | extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__asan_memset); | |
86 | extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memmove); | |
87 | extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__asan_memcpy); | |
88 | #else /* CONFIG_KASAN_SW_TAGS */ | |
89 | extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(__hwasan_memset); | |
90 | extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memmove); | |
91 | extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(__hwasan_memcpy); | |
92 | #endif | |
93 | ||
a28a6e86 FL |
94 | extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr); |
95 | extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp); | |
a28a6e86 FL |
96 | extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat); |
97 | extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy); | |
98 | extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen); | |
99 | extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat); | |
100 | extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy); | |
2e577732 | 101 | |
a28a6e86 | 102 | #else |
78a498c3 AP |
103 | |
104 | #if defined(__SANITIZE_MEMORY__) | |
105 | /* | |
106 | * For KMSAN builds all memcpy/memset/memmove calls should be replaced by the | |
107 | * corresponding __msan_XXX functions. | |
108 | */ | |
109 | #include <linux/kmsan_string.h> | |
110 | #define __underlying_memcpy __msan_memcpy | |
111 | #define __underlying_memmove __msan_memmove | |
112 | #define __underlying_memset __msan_memset | |
113 | #else | |
a28a6e86 FL |
114 | #define __underlying_memcpy __builtin_memcpy |
115 | #define __underlying_memmove __builtin_memmove | |
116 | #define __underlying_memset __builtin_memset | |
78a498c3 AP |
117 | #endif |
118 | ||
119 | #define __underlying_memchr __builtin_memchr | |
120 | #define __underlying_memcmp __builtin_memcmp | |
a28a6e86 FL |
121 | #define __underlying_strcat __builtin_strcat |
122 | #define __underlying_strcpy __builtin_strcpy | |
123 | #define __underlying_strlen __builtin_strlen | |
124 | #define __underlying_strncat __builtin_strncat | |
125 | #define __underlying_strncpy __builtin_strncpy | |
2e577732 | 126 | |
a28a6e86 FL |
127 | #endif |
128 | ||
43213dae KC |
129 | /** |
130 | * unsafe_memcpy - memcpy implementation with no FORTIFY bounds checking | |
131 | * | |
132 | * @dst: Destination memory address to write to | |
133 | * @src: Source memory address to read from | |
134 | * @bytes: How many bytes to write to @dst from @src | |
135 | * @justification: Free-form text or comment describing why the use is needed | |
136 | * | |
137 | * This should be used for corner cases where the compiler cannot do the | |
138 | * right thing, or during transitions between APIs, etc. It should be used | |
139 | * very rarely, and includes a place for justification detailing where bounds | |
140 | * checking has happened, and why existing solutions cannot be employed. | |
141 | */ | |
142 | #define unsafe_memcpy(dst, src, bytes, justification) \ | |
143 | __underlying_memcpy(dst, src, bytes) | |
144 | ||
281d0c96 | 145 | /* |
9f7d69c5 KC |
146 | * Clang's use of __builtin_*object_size() within inlines needs hinting via |
147 | * __pass_*object_size(). The preference is to only ever use type 1 (member | |
281d0c96 KC |
148 | * size, rather than struct size), but there remain some stragglers using |
149 | * type 0 that will be converted in the future. | |
150 | */ | |
439a1bca KC |
151 | #if __has_builtin(__builtin_dynamic_object_size) |
152 | #define POS __pass_dynamic_object_size(1) | |
153 | #define POS0 __pass_dynamic_object_size(0) | |
439a1bca | 154 | #else |
9f7d69c5 KC |
155 | #define POS __pass_object_size(1) |
156 | #define POS0 __pass_object_size(0) | |
439a1bca | 157 | #endif |
281d0c96 | 158 | |
fa35198f KC |
159 | #define __compiletime_lessthan(bounds, length) ( \ |
160 | __builtin_constant_p((bounds) < (length)) && \ | |
161 | (bounds) < (length) \ | |
162 | ) | |
163 | ||
dfbafa70 KC |
164 | /** |
165 | * strncpy - Copy a string to memory with non-guaranteed NUL padding | |
166 | * | |
167 | * @p: pointer to destination of copy | |
168 | * @q: pointer to NUL-terminated source string to copy | |
169 | * @size: bytes to write at @p | |
170 | * | |
171 | * If strlen(@q) >= @size, the copy of @q will stop after @size bytes, | |
172 | * and @p will NOT be NUL-terminated | |
173 | * | |
174 | * If strlen(@q) < @size, following the copy of @q, trailing NUL bytes | |
175 | * will be written to @p until @size total bytes have been written. | |
176 | * | |
177 | * Do not use this function. While FORTIFY_SOURCE tries to avoid | |
178 | * over-reads of @q, it cannot defend against writing unterminated | |
179 | * results to @p. Using strncpy() remains ambiguous and fragile. | |
180 | * Instead, please choose an alternative, so that the expectation | |
181 | * of @p's contents is unambiguous: | |
182 | * | |
03699f27 KC |
183 | * +--------------------+--------------------+------------+ |
184 | * | **p** needs to be: | padded to **size** | not padded | | |
185 | * +====================+====================+============+ | |
186 | * | NUL-terminated | strscpy_pad() | strscpy() | | |
187 | * +--------------------+--------------------+------------+ | |
188 | * | not NUL-terminated | strtomem_pad() | strtomem() | | |
189 | * +--------------------+--------------------+------------+ | |
dfbafa70 KC |
190 | * |
191 | * Note strscpy*()'s differing return values for detecting truncation, | |
192 | * and strtomem*()'s expectation that the destination is marked with | |
193 | * __nonstring when it is a character array. | |
194 | * | |
195 | */ | |
92df138a | 196 | __FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3) |
281d0c96 | 197 | char *strncpy(char * const POS p, const char *q, __kernel_size_t size) |
a28a6e86 | 198 | { |
21a2c74b | 199 | const size_t p_size = __member_size(p); |
a28a6e86 | 200 | |
fa35198f | 201 | if (__compiletime_lessthan(p_size, size)) |
a28a6e86 FL |
202 | __write_overflow(); |
203 | if (p_size < size) | |
3d965b33 | 204 | fortify_panic(FORTIFY_FUNC_strncpy, FORTIFY_WRITE, p_size, size, p); |
a28a6e86 FL |
205 | return __underlying_strncpy(p, q, size); |
206 | } | |
207 | ||
369cd216 | 208 | extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen); |
03699f27 KC |
209 | /** |
210 | * strnlen - Return bounded count of characters in a NUL-terminated string | |
211 | * | |
212 | * @p: pointer to NUL-terminated string to count. | |
213 | * @maxlen: maximum number of characters to count. | |
214 | * | |
215 | * Returns number of characters in @p (NOT including the final NUL), or | |
216 | * @maxlen, if no NUL has been found up to there. | |
217 | * | |
218 | */ | |
281d0c96 | 219 | __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen) |
369cd216 | 220 | { |
21a2c74b KC |
221 | const size_t p_size = __member_size(p); |
222 | const size_t p_len = __compiletime_strlen(p); | |
3009f891 KC |
223 | size_t ret; |
224 | ||
225 | /* We can take compile-time actions when maxlen is const. */ | |
311fb40a | 226 | if (__builtin_constant_p(maxlen) && p_len != SIZE_MAX) { |
3009f891 KC |
227 | /* If p is const, we can use its compile-time-known len. */ |
228 | if (maxlen >= p_size) | |
229 | return p_len; | |
230 | } | |
369cd216 | 231 | |
3009f891 KC |
232 | /* Do not check characters beyond the end of p. */ |
233 | ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size); | |
369cd216 | 234 | if (p_size <= ret && maxlen != ret) |
3d965b33 | 235 | fortify_panic(FORTIFY_FUNC_strnlen, FORTIFY_READ, p_size, ret + 1, ret); |
369cd216 KC |
236 | return ret; |
237 | } | |
238 | ||
67ebc3ab KC |
239 | /* |
240 | * Defined after fortified strnlen to reuse it. However, it must still be | |
241 | * possible for strlen() to be used on compile-time strings for use in | |
242 | * static initializers (i.e. as a constant expression). | |
243 | */ | |
03699f27 KC |
244 | /** |
245 | * strlen - Return count of characters in a NUL-terminated string | |
246 | * | |
247 | * @p: pointer to NUL-terminated string to count. | |
248 | * | |
249 | * Do not use this function unless the string length is known at | |
250 | * compile-time. When @p is unterminated, this function may crash | |
251 | * or return unexpected counts that could lead to memory content | |
252 | * exposures. Prefer strnlen(). | |
253 | * | |
254 | * Returns number of characters in @p (NOT including the final NUL). | |
255 | * | |
256 | */ | |
67ebc3ab KC |
257 | #define strlen(p) \ |
258 | __builtin_choose_expr(__is_constexpr(__builtin_strlen(p)), \ | |
259 | __builtin_strlen(p), __fortify_strlen(p)) | |
92df138a | 260 | __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1) |
281d0c96 | 261 | __kernel_size_t __fortify_strlen(const char * const POS p) |
a28a6e86 | 262 | { |
21a2c74b | 263 | const size_t p_size = __member_size(p); |
a28a6e86 | 264 | __kernel_size_t ret; |
a28a6e86 | 265 | |
3009f891 | 266 | /* Give up if we don't know how large p is. */ |
311fb40a | 267 | if (p_size == SIZE_MAX) |
a28a6e86 FL |
268 | return __underlying_strlen(p); |
269 | ret = strnlen(p, p_size); | |
270 | if (p_size <= ret) | |
3d965b33 | 271 | fortify_panic(FORTIFY_FUNC_strlen, FORTIFY_READ, p_size, ret + 1, ret); |
a28a6e86 FL |
272 | return ret; |
273 | } | |
274 | ||
03699f27 | 275 | /* Defined after fortified strnlen() to reuse it. */ |
e6584c39 KC |
276 | extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(sized_strscpy); |
277 | __FORTIFY_INLINE ssize_t sized_strscpy(char * const POS p, const char * const POS q, size_t size) | |
a28a6e86 | 278 | { |
a28a6e86 | 279 | /* Use string size rather than possible enclosing struct size. */ |
21a2c74b KC |
280 | const size_t p_size = __member_size(p); |
281 | const size_t q_size = __member_size(q); | |
282 | size_t len; | |
a28a6e86 FL |
283 | |
284 | /* If we cannot get size of p and q default to call strscpy. */ | |
311fb40a | 285 | if (p_size == SIZE_MAX && q_size == SIZE_MAX) |
a28a6e86 FL |
286 | return __real_strscpy(p, q, size); |
287 | ||
288 | /* | |
289 | * If size can be known at compile time and is greater than | |
290 | * p_size, generate a compile time write overflow error. | |
291 | */ | |
fa35198f | 292 | if (__compiletime_lessthan(p_size, size)) |
a28a6e86 FL |
293 | __write_overflow(); |
294 | ||
62e1cbfc KC |
295 | /* Short-circuit for compile-time known-safe lengths. */ |
296 | if (__compiletime_lessthan(p_size, SIZE_MAX)) { | |
297 | len = __compiletime_strlen(q); | |
298 | ||
299 | if (len < SIZE_MAX && __compiletime_lessthan(len, size)) { | |
300 | __underlying_memcpy(p, q, len + 1); | |
301 | return len; | |
302 | } | |
303 | } | |
304 | ||
a28a6e86 FL |
305 | /* |
306 | * This call protects from read overflow, because len will default to q | |
307 | * length if it smaller than size. | |
308 | */ | |
309 | len = strnlen(q, size); | |
310 | /* | |
311 | * If len equals size, we will copy only size bytes which leads to | |
312 | * -E2BIG being returned. | |
313 | * Otherwise we will copy len + 1 because of the final '\O'. | |
314 | */ | |
315 | len = len == size ? size : len + 1; | |
316 | ||
317 | /* | |
318 | * Generate a runtime write overflow error if len is greater than | |
319 | * p_size. | |
320 | */ | |
3d965b33 KC |
321 | if (p_size < len) |
322 | fortify_panic(FORTIFY_FUNC_strscpy, FORTIFY_WRITE, p_size, len, -E2BIG); | |
a28a6e86 FL |
323 | |
324 | /* | |
325 | * We can now safely call vanilla strscpy because we are protected from: | |
326 | * 1. Read overflow thanks to call to strnlen(). | |
327 | * 2. Write overflow thanks to above ifs. | |
328 | */ | |
329 | return __real_strscpy(p, q, len); | |
330 | } | |
331 | ||
605395cd KC |
332 | /* Defined after fortified strlen() to reuse it. */ |
333 | extern size_t __real_strlcat(char *p, const char *q, size_t avail) __RENAME(strlcat); | |
334 | /** | |
335 | * strlcat - Append a string to an existing string | |
336 | * | |
337 | * @p: pointer to %NUL-terminated string to append to | |
338 | * @q: pointer to %NUL-terminated string to append from | |
339 | * @avail: Maximum bytes available in @p | |
340 | * | |
341 | * Appends %NUL-terminated string @q after the %NUL-terminated | |
342 | * string at @p, but will not write beyond @avail bytes total, | |
343 | * potentially truncating the copy from @q. @p will stay | |
344 | * %NUL-terminated only if a %NUL already existed within | |
345 | * the @avail bytes of @p. If so, the resulting number of | |
346 | * bytes copied from @q will be at most "@avail - strlen(@p) - 1". | |
347 | * | |
348 | * Do not use this function. While FORTIFY_SOURCE tries to avoid | |
349 | * read and write overflows, this is only possible when the sizes | |
350 | * of @p and @q are known to the compiler. Prefer building the | |
351 | * string with formatting, via scnprintf(), seq_buf, or similar. | |
352 | * | |
353 | * Returns total bytes that _would_ have been contained by @p | |
354 | * regardless of truncation, similar to snprintf(). If return | |
355 | * value is >= @avail, the string has been truncated. | |
356 | * | |
357 | */ | |
358 | __FORTIFY_INLINE | |
359 | size_t strlcat(char * const POS p, const char * const POS q, size_t avail) | |
360 | { | |
361 | const size_t p_size = __member_size(p); | |
362 | const size_t q_size = __member_size(q); | |
363 | size_t p_len, copy_len; | |
364 | size_t actual, wanted; | |
365 | ||
366 | /* Give up immediately if both buffer sizes are unknown. */ | |
367 | if (p_size == SIZE_MAX && q_size == SIZE_MAX) | |
368 | return __real_strlcat(p, q, avail); | |
369 | ||
370 | p_len = strnlen(p, avail); | |
371 | copy_len = strlen(q); | |
372 | wanted = actual = p_len + copy_len; | |
373 | ||
374 | /* Cannot append any more: report truncation. */ | |
375 | if (avail <= p_len) | |
376 | return wanted; | |
377 | ||
378 | /* Give up if string is already overflowed. */ | |
379 | if (p_size <= p_len) | |
3d965b33 | 380 | fortify_panic(FORTIFY_FUNC_strlcat, FORTIFY_READ, p_size, p_len + 1, wanted); |
605395cd KC |
381 | |
382 | if (actual >= avail) { | |
383 | copy_len = avail - p_len - 1; | |
384 | actual = p_len + copy_len; | |
385 | } | |
386 | ||
387 | /* Give up if copy will overflow. */ | |
388 | if (p_size <= actual) | |
3d965b33 | 389 | fortify_panic(FORTIFY_FUNC_strlcat, FORTIFY_WRITE, p_size, actual + 1, wanted); |
605395cd KC |
390 | __underlying_memcpy(p + p_len, q, copy_len); |
391 | p[actual] = '\0'; | |
392 | ||
393 | return wanted; | |
394 | } | |
395 | ||
55c84a5c KC |
396 | /* Defined after fortified strlcat() to reuse it. */ |
397 | /** | |
398 | * strcat - Append a string to an existing string | |
399 | * | |
400 | * @p: pointer to NUL-terminated string to append to | |
401 | * @q: pointer to NUL-terminated source string to append from | |
402 | * | |
403 | * Do not use this function. While FORTIFY_SOURCE tries to avoid | |
404 | * read and write overflows, this is only possible when the | |
405 | * destination buffer size is known to the compiler. Prefer | |
406 | * building the string with formatting, via scnprintf() or similar. | |
407 | * At the very least, use strncat(). | |
408 | * | |
409 | * Returns @p. | |
410 | * | |
411 | */ | |
412 | __FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2) | |
413 | char *strcat(char * const POS p, const char *q) | |
414 | { | |
415 | const size_t p_size = __member_size(p); | |
3d965b33 | 416 | const size_t wanted = strlcat(p, q, p_size); |
55c84a5c | 417 | |
3d965b33 KC |
418 | if (p_size <= wanted) |
419 | fortify_panic(FORTIFY_FUNC_strcat, FORTIFY_WRITE, p_size, wanted + 1, p); | |
55c84a5c KC |
420 | return p; |
421 | } | |
422 | ||
03699f27 KC |
423 | /** |
424 | * strncat - Append a string to an existing string | |
425 | * | |
426 | * @p: pointer to NUL-terminated string to append to | |
427 | * @q: pointer to source string to append from | |
428 | * @count: Maximum bytes to read from @q | |
429 | * | |
430 | * Appends at most @count bytes from @q (stopping at the first | |
431 | * NUL byte) after the NUL-terminated string at @p. @p will be | |
432 | * NUL-terminated. | |
433 | * | |
434 | * Do not use this function. While FORTIFY_SOURCE tries to avoid | |
435 | * read and write overflows, this is only possible when the sizes | |
436 | * of @p and @q are known to the compiler. Prefer building the | |
437 | * string with formatting, via scnprintf() or similar. | |
438 | * | |
439 | * Returns @p. | |
440 | * | |
441 | */ | |
442 | /* Defined after fortified strlen() and strnlen() to reuse them. */ | |
92df138a | 443 | __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3) |
281d0c96 | 444 | char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count) |
a28a6e86 | 445 | { |
21a2c74b KC |
446 | const size_t p_size = __member_size(p); |
447 | const size_t q_size = __member_size(q); | |
3d965b33 | 448 | size_t p_len, copy_len, total; |
a28a6e86 | 449 | |
311fb40a | 450 | if (p_size == SIZE_MAX && q_size == SIZE_MAX) |
a28a6e86 FL |
451 | return __underlying_strncat(p, q, count); |
452 | p_len = strlen(p); | |
453 | copy_len = strnlen(q, count); | |
3d965b33 KC |
454 | total = p_len + copy_len + 1; |
455 | if (p_size < total) | |
456 | fortify_panic(FORTIFY_FUNC_strncat, FORTIFY_WRITE, p_size, total, p); | |
a28a6e86 FL |
457 | __underlying_memcpy(p + p_len, q, copy_len); |
458 | p[p_len + copy_len] = '\0'; | |
459 | return p; | |
460 | } | |
461 | ||
4ce615e7 | 462 | __FORTIFY_INLINE bool fortify_memset_chk(__kernel_size_t size, |
28e77cc1 KC |
463 | const size_t p_size, |
464 | const size_t p_size_field) | |
a28a6e86 | 465 | { |
28e77cc1 KC |
466 | if (__builtin_constant_p(size)) { |
467 | /* | |
468 | * Length argument is a constant expression, so we | |
469 | * can perform compile-time bounds checking where | |
fa35198f | 470 | * buffer sizes are also known at compile time. |
28e77cc1 | 471 | */ |
a28a6e86 | 472 | |
28e77cc1 | 473 | /* Error when size is larger than enclosing struct. */ |
fa35198f KC |
474 | if (__compiletime_lessthan(p_size_field, p_size) && |
475 | __compiletime_lessthan(p_size, size)) | |
28e77cc1 KC |
476 | __write_overflow(); |
477 | ||
478 | /* Warn when write size is larger than dest field. */ | |
fa35198f | 479 | if (__compiletime_lessthan(p_size_field, size)) |
28e77cc1 KC |
480 | __write_overflow_field(p_size_field, size); |
481 | } | |
482 | /* | |
483 | * At this point, length argument may not be a constant expression, | |
484 | * so run-time bounds checking can be done where buffer sizes are | |
485 | * known. (This is not an "else" because the above checks may only | |
486 | * be compile-time warnings, and we want to still warn for run-time | |
487 | * overflows.) | |
488 | */ | |
489 | ||
490 | /* | |
491 | * Always stop accesses beyond the struct that contains the | |
492 | * field, when the buffer's remaining size is known. | |
311fb40a | 493 | * (The SIZE_MAX test is to optimize away checks where the buffer |
28e77cc1 KC |
494 | * lengths are unknown.) |
495 | */ | |
311fb40a | 496 | if (p_size != SIZE_MAX && p_size < size) |
3d965b33 | 497 | fortify_panic(FORTIFY_FUNC_memset, FORTIFY_WRITE, p_size, size, true); |
4ce615e7 | 498 | return false; |
a28a6e86 FL |
499 | } |
500 | ||
28e77cc1 KC |
501 | #define __fortify_memset_chk(p, c, size, p_size, p_size_field) ({ \ |
502 | size_t __fortify_size = (size_t)(size); \ | |
503 | fortify_memset_chk(__fortify_size, p_size, p_size_field), \ | |
504 | __underlying_memset(p, c, __fortify_size); \ | |
505 | }) | |
506 | ||
507 | /* | |
9f7d69c5 KC |
508 | * __struct_size() vs __member_size() must be captured here to avoid |
509 | * evaluating argument side-effects further into the macro layers. | |
28e77cc1 | 510 | */ |
ff901d80 | 511 | #ifndef CONFIG_KMSAN |
28e77cc1 | 512 | #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ |
9f7d69c5 | 513 | __struct_size(p), __member_size(p)) |
ff901d80 | 514 | #endif |
28e77cc1 | 515 | |
f68f2ff9 KC |
516 | /* |
517 | * To make sure the compiler can enforce protection against buffer overflows, | |
518 | * memcpy(), memmove(), and memset() must not be used beyond individual | |
519 | * struct members. If you need to copy across multiple members, please use | |
520 | * struct_group() to create a named mirror of an anonymous struct union. | |
521 | * (e.g. see struct sk_buff.) Read overflow checking is currently only | |
522 | * done when a write overflow is also present, or when building with W=1. | |
523 | * | |
524 | * Mitigation coverage matrix | |
525 | * Bounds checking at: | |
526 | * +-------+-------+-------+-------+ | |
527 | * | Compile time | Run time | | |
528 | * memcpy() argument sizes: | write | read | write | read | | |
529 | * dest source length +-------+-------+-------+-------+ | |
530 | * memcpy(known, known, constant) | y | y | n/a | n/a | | |
531 | * memcpy(known, unknown, constant) | y | n | n/a | V | | |
532 | * memcpy(known, known, dynamic) | n | n | B | B | | |
533 | * memcpy(known, unknown, dynamic) | n | n | B | V | | |
534 | * memcpy(unknown, known, constant) | n | y | V | n/a | | |
535 | * memcpy(unknown, unknown, constant) | n | n | V | V | | |
536 | * memcpy(unknown, known, dynamic) | n | n | V | B | | |
537 | * memcpy(unknown, unknown, dynamic) | n | n | V | V | | |
538 | * +-------+-------+-------+-------+ | |
539 | * | |
540 | * y = perform deterministic compile-time bounds checking | |
541 | * n = cannot perform deterministic compile-time bounds checking | |
542 | * n/a = no run-time bounds checking needed since compile-time deterministic | |
543 | * B = can perform run-time bounds checking (currently unimplemented) | |
544 | * V = vulnerable to run-time overflow (will need refactoring to solve) | |
545 | * | |
546 | */ | |
54d9469b | 547 | __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size, |
f68f2ff9 KC |
548 | const size_t p_size, |
549 | const size_t q_size, | |
550 | const size_t p_size_field, | |
551 | const size_t q_size_field, | |
475ddf1f | 552 | const u8 func) |
a28a6e86 | 553 | { |
a28a6e86 | 554 | if (__builtin_constant_p(size)) { |
f68f2ff9 KC |
555 | /* |
556 | * Length argument is a constant expression, so we | |
557 | * can perform compile-time bounds checking where | |
fa35198f | 558 | * buffer sizes are also known at compile time. |
f68f2ff9 KC |
559 | */ |
560 | ||
561 | /* Error when size is larger than enclosing struct. */ | |
fa35198f KC |
562 | if (__compiletime_lessthan(p_size_field, p_size) && |
563 | __compiletime_lessthan(p_size, size)) | |
a28a6e86 | 564 | __write_overflow(); |
fa35198f KC |
565 | if (__compiletime_lessthan(q_size_field, q_size) && |
566 | __compiletime_lessthan(q_size, size)) | |
a28a6e86 | 567 | __read_overflow2(); |
f68f2ff9 KC |
568 | |
569 | /* Warn when write size argument larger than dest field. */ | |
fa35198f | 570 | if (__compiletime_lessthan(p_size_field, size)) |
f68f2ff9 KC |
571 | __write_overflow_field(p_size_field, size); |
572 | /* | |
573 | * Warn for source field over-read when building with W=1 | |
574 | * or when an over-write happened, so both can be fixed at | |
575 | * the same time. | |
576 | */ | |
fa35198f KC |
577 | if ((IS_ENABLED(KBUILD_EXTRA_WARN1) || |
578 | __compiletime_lessthan(p_size_field, size)) && | |
579 | __compiletime_lessthan(q_size_field, size)) | |
f68f2ff9 | 580 | __read_overflow2_field(q_size_field, size); |
a28a6e86 | 581 | } |
f68f2ff9 KC |
582 | /* |
583 | * At this point, length argument may not be a constant expression, | |
584 | * so run-time bounds checking can be done where buffer sizes are | |
585 | * known. (This is not an "else" because the above checks may only | |
586 | * be compile-time warnings, and we want to still warn for run-time | |
587 | * overflows.) | |
588 | */ | |
589 | ||
590 | /* | |
591 | * Always stop accesses beyond the struct that contains the | |
592 | * field, when the buffer's remaining size is known. | |
311fb40a | 593 | * (The SIZE_MAX test is to optimize away checks where the buffer |
f68f2ff9 KC |
594 | * lengths are unknown.) |
595 | */ | |
475ddf1f | 596 | if (p_size != SIZE_MAX && p_size < size) |
3d965b33 | 597 | fortify_panic(func, FORTIFY_WRITE, p_size, size, true); |
475ddf1f | 598 | else if (q_size != SIZE_MAX && q_size < size) |
3d965b33 | 599 | fortify_panic(func, FORTIFY_READ, p_size, size, true); |
54d9469b KC |
600 | |
601 | /* | |
602 | * Warn when writing beyond destination field size. | |
603 | * | |
2003e483 | 604 | * Note the implementation of __builtin_*object_size() behaves |
54d9469b KC |
605 | * like sizeof() when not directly referencing a flexible |
606 | * array member, which means there will be many bounds checks | |
607 | * that will appear at run-time, without a way for them to be | |
608 | * detected at compile-time (as can be done when the destination | |
609 | * is specifically the flexible array member). | |
610 | * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832 | |
611 | */ | |
2003e483 | 612 | if (p_size_field != SIZE_MAX && |
54d9469b KC |
613 | p_size != p_size_field && p_size_field < size) |
614 | return true; | |
615 | ||
616 | return false; | |
a28a6e86 FL |
617 | } |
618 | ||
f68f2ff9 KC |
619 | #define __fortify_memcpy_chk(p, q, size, p_size, q_size, \ |
620 | p_size_field, q_size_field, op) ({ \ | |
6f7630b1 KC |
621 | const size_t __fortify_size = (size_t)(size); \ |
622 | const size_t __p_size = (p_size); \ | |
623 | const size_t __q_size = (q_size); \ | |
624 | const size_t __p_size_field = (p_size_field); \ | |
625 | const size_t __q_size_field = (q_size_field); \ | |
26f812ba | 626 | fortify_warn_once(fortify_memcpy_chk(__fortify_size, __p_size, \ |
6f7630b1 | 627 | __q_size, __p_size_field, \ |
475ddf1f | 628 | __q_size_field, FORTIFY_FUNC_ ##op), \ |
54d9469b KC |
629 | #op ": detected field-spanning write (size %zu) of single %s (size %zu)\n", \ |
630 | __fortify_size, \ | |
5097a69d | 631 | "field \"" #p "\" at " FILE_LINE, \ |
6f7630b1 | 632 | __p_size_field); \ |
f68f2ff9 KC |
633 | __underlying_##op(p, q, __fortify_size); \ |
634 | }) | |
635 | ||
54d9469b KC |
636 | /* |
637 | * Notes about compile-time buffer size detection: | |
638 | * | |
639 | * With these types... | |
640 | * | |
641 | * struct middle { | |
642 | * u16 a; | |
643 | * u8 middle_buf[16]; | |
644 | * int b; | |
645 | * }; | |
646 | * struct end { | |
647 | * u16 a; | |
648 | * u8 end_buf[16]; | |
649 | * }; | |
650 | * struct flex { | |
651 | * int a; | |
652 | * u8 flex_buf[]; | |
653 | * }; | |
654 | * | |
655 | * void func(TYPE *ptr) { ... } | |
656 | * | |
657 | * Cases where destination size cannot be currently detected: | |
658 | * - the size of ptr's object (seemingly by design, gcc & clang fail): | |
659 | * __builtin_object_size(ptr, 1) == SIZE_MAX | |
660 | * - the size of flexible arrays in ptr's obj (by design, dynamic size): | |
661 | * __builtin_object_size(ptr->flex_buf, 1) == SIZE_MAX | |
662 | * - the size of ANY array at the end of ptr's obj (gcc and clang bug): | |
663 | * __builtin_object_size(ptr->end_buf, 1) == SIZE_MAX | |
664 | * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836 | |
665 | * | |
666 | * Cases where destination size is currently detected: | |
667 | * - the size of non-array members within ptr's object: | |
668 | * __builtin_object_size(ptr->a, 1) == 2 | |
669 | * - the size of non-flexible-array in the middle of ptr's obj: | |
670 | * __builtin_object_size(ptr->middle_buf, 1) == 16 | |
671 | * | |
672 | */ | |
673 | ||
f68f2ff9 | 674 | /* |
9f7d69c5 KC |
675 | * __struct_size() vs __member_size() must be captured here to avoid |
676 | * evaluating argument side-effects further into the macro layers. | |
f68f2ff9 KC |
677 | */ |
678 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ | |
9f7d69c5 KC |
679 | __struct_size(p), __struct_size(q), \ |
680 | __member_size(p), __member_size(q), \ | |
f68f2ff9 | 681 | memcpy) |
938a000e | 682 | #define memmove(p, q, s) __fortify_memcpy_chk(p, q, s, \ |
9f7d69c5 KC |
683 | __struct_size(p), __struct_size(q), \ |
684 | __member_size(p), __member_size(q), \ | |
938a000e | 685 | memmove) |
a28a6e86 FL |
686 | |
687 | extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan); | |
281d0c96 | 688 | __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size) |
a28a6e86 | 689 | { |
21a2c74b | 690 | const size_t p_size = __struct_size(p); |
a28a6e86 | 691 | |
fa35198f | 692 | if (__compiletime_lessthan(p_size, size)) |
a28a6e86 FL |
693 | __read_overflow(); |
694 | if (p_size < size) | |
3d965b33 | 695 | fortify_panic(FORTIFY_FUNC_memscan, FORTIFY_READ, p_size, size, NULL); |
a28a6e86 FL |
696 | return __real_memscan(p, c, size); |
697 | } | |
698 | ||
92df138a | 699 | __FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3) |
281d0c96 | 700 | int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size) |
a28a6e86 | 701 | { |
21a2c74b KC |
702 | const size_t p_size = __struct_size(p); |
703 | const size_t q_size = __struct_size(q); | |
a28a6e86 FL |
704 | |
705 | if (__builtin_constant_p(size)) { | |
fa35198f | 706 | if (__compiletime_lessthan(p_size, size)) |
a28a6e86 | 707 | __read_overflow(); |
fa35198f | 708 | if (__compiletime_lessthan(q_size, size)) |
a28a6e86 FL |
709 | __read_overflow2(); |
710 | } | |
3d965b33 KC |
711 | if (p_size < size) |
712 | fortify_panic(FORTIFY_FUNC_memcmp, FORTIFY_READ, p_size, size, INT_MIN); | |
713 | else if (q_size < size) | |
714 | fortify_panic(FORTIFY_FUNC_memcmp, FORTIFY_READ, q_size, size, INT_MIN); | |
a28a6e86 FL |
715 | return __underlying_memcmp(p, q, size); |
716 | } | |
717 | ||
92df138a | 718 | __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3) |
281d0c96 | 719 | void *memchr(const void * const POS0 p, int c, __kernel_size_t size) |
a28a6e86 | 720 | { |
21a2c74b | 721 | const size_t p_size = __struct_size(p); |
a28a6e86 | 722 | |
fa35198f | 723 | if (__compiletime_lessthan(p_size, size)) |
a28a6e86 FL |
724 | __read_overflow(); |
725 | if (p_size < size) | |
3d965b33 | 726 | fortify_panic(FORTIFY_FUNC_memchr, FORTIFY_READ, p_size, size, NULL); |
a28a6e86 FL |
727 | return __underlying_memchr(p, c, size); |
728 | } | |
729 | ||
730 | void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv); | |
281d0c96 | 731 | __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) |
a28a6e86 | 732 | { |
21a2c74b | 733 | const size_t p_size = __struct_size(p); |
a28a6e86 | 734 | |
fa35198f | 735 | if (__compiletime_lessthan(p_size, size)) |
a28a6e86 FL |
736 | __read_overflow(); |
737 | if (p_size < size) | |
3d965b33 | 738 | fortify_panic(FORTIFY_FUNC_memchr_inv, FORTIFY_READ, p_size, size, NULL); |
a28a6e86 FL |
739 | return __real_memchr_inv(p, c, size); |
740 | } | |
741 | ||
7bd230a2 | 742 | extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup_noprof) |
9e4a6177 | 743 | __realloc_size(2); |
7bd230a2 | 744 | __FORTIFY_INLINE void *kmemdup_noprof(const void * const POS0 p, size_t size, gfp_t gfp) |
a28a6e86 | 745 | { |
21a2c74b | 746 | const size_t p_size = __struct_size(p); |
a28a6e86 | 747 | |
fa35198f | 748 | if (__compiletime_lessthan(p_size, size)) |
a28a6e86 FL |
749 | __read_overflow(); |
750 | if (p_size < size) | |
74df2245 KC |
751 | fortify_panic(FORTIFY_FUNC_kmemdup, FORTIFY_READ, p_size, size, |
752 | __real_kmemdup(p, 0, gfp)); | |
a28a6e86 FL |
753 | return __real_kmemdup(p, size, gfp); |
754 | } | |
7bd230a2 | 755 | #define kmemdup(...) alloc_hooks(kmemdup_noprof(__VA_ARGS__)) |
a28a6e86 | 756 | |
03699f27 KC |
757 | /** |
758 | * strcpy - Copy a string into another string buffer | |
759 | * | |
760 | * @p: pointer to destination of copy | |
761 | * @q: pointer to NUL-terminated source string to copy | |
762 | * | |
763 | * Do not use this function. While FORTIFY_SOURCE tries to avoid | |
764 | * overflows, this is only possible when the sizes of @q and @p are | |
765 | * known to the compiler. Prefer strscpy(), though note its different | |
766 | * return values for detecting truncation. | |
767 | * | |
768 | * Returns @p. | |
769 | * | |
770 | */ | |
f68f2ff9 | 771 | /* Defined after fortified strlen to reuse it. */ |
92df138a | 772 | __FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2) |
281d0c96 | 773 | char *strcpy(char * const POS p, const char * const POS q) |
a28a6e86 | 774 | { |
21a2c74b KC |
775 | const size_t p_size = __member_size(p); |
776 | const size_t q_size = __member_size(q); | |
a28a6e86 FL |
777 | size_t size; |
778 | ||
f68f2ff9 | 779 | /* If neither buffer size is known, immediately give up. */ |
fa35198f KC |
780 | if (__builtin_constant_p(p_size) && |
781 | __builtin_constant_p(q_size) && | |
782 | p_size == SIZE_MAX && q_size == SIZE_MAX) | |
a28a6e86 FL |
783 | return __underlying_strcpy(p, q); |
784 | size = strlen(q) + 1; | |
072af0c6 | 785 | /* Compile-time check for const size overflow. */ |
fa35198f | 786 | if (__compiletime_lessthan(p_size, size)) |
072af0c6 KC |
787 | __write_overflow(); |
788 | /* Run-time check for dynamic size overflow. */ | |
a28a6e86 | 789 | if (p_size < size) |
3d965b33 | 790 | fortify_panic(FORTIFY_FUNC_strcpy, FORTIFY_WRITE, p_size, size, p); |
f68f2ff9 | 791 | __underlying_memcpy(p, q, size); |
a28a6e86 FL |
792 | return p; |
793 | } | |
794 | ||
795 | /* Don't use these outside the FORITFY_SOURCE implementation */ | |
796 | #undef __underlying_memchr | |
797 | #undef __underlying_memcmp | |
a28a6e86 FL |
798 | #undef __underlying_strcat |
799 | #undef __underlying_strcpy | |
800 | #undef __underlying_strlen | |
801 | #undef __underlying_strncat | |
802 | #undef __underlying_strncpy | |
803 | ||
281d0c96 KC |
804 | #undef POS |
805 | #undef POS0 | |
806 | ||
a28a6e86 | 807 | #endif /* _LINUX_FORTIFY_STRING_H_ */ |