1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_FORTIFY_STRING_H_
3 #define _LINUX_FORTIFY_STRING_H_
4 
5 #include <linux/bug.h>
6 #include <linux/const.h>
7 #include <linux/limits.h>
8 
9 #define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable
10 #define __RENAME(x) __asm__(#x)
11 
12 void fortify_panic(const char *name) __noreturn __cold;
13 void __read_overflow(void) __compiletime_error("detected read beyond size of object (1st parameter)");
14 void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)");
15 void __read_overflow2_field(size_t avail, size_t wanted) __compiletime_warning("detected read beyond size of field (2nd parameter); maybe use struct_group()?");
16 void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)");
17 void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("detected write beyond size of field (1st parameter); maybe use struct_group()?");
18 
19 #define __compiletime_strlen(p)					\
20 ({								\
21 	unsigned char *__p = (unsigned char *)(p);		\
22 	size_t __ret = SIZE_MAX;				\
23 	size_t __p_size = __member_size(p);			\
24 	if (__p_size != SIZE_MAX &&				\
25 	    __builtin_constant_p(*__p)) {			\
26 		size_t __p_len = __p_size - 1;			\
27 		if (__builtin_constant_p(__p[__p_len]) &&	\
28 		    __p[__p_len] == '\0')			\
29 			__ret = __builtin_strlen(__p);		\
30 	}							\
31 	__ret;							\
32 })
33 
34 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
35 extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
36 extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
37 extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
38 extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
39 extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
40 extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
41 extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
42 extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
43 extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
44 extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
45 #else
46 
47 #if defined(__SANITIZE_MEMORY__)
48 /*
49  * For KMSAN builds all memcpy/memset/memmove calls should be replaced by the
50  * corresponding __msan_XXX functions.
51  */
52 #include <linux/kmsan_string.h>
53 #define __underlying_memcpy	__msan_memcpy
54 #define __underlying_memmove	__msan_memmove
55 #define __underlying_memset	__msan_memset
56 #else
57 #define __underlying_memcpy	__builtin_memcpy
58 #define __underlying_memmove	__builtin_memmove
59 #define __underlying_memset	__builtin_memset
60 #endif
61 
62 #define __underlying_memchr	__builtin_memchr
63 #define __underlying_memcmp	__builtin_memcmp
64 #define __underlying_strcat	__builtin_strcat
65 #define __underlying_strcpy	__builtin_strcpy
66 #define __underlying_strlen	__builtin_strlen
67 #define __underlying_strncat	__builtin_strncat
68 #define __underlying_strncpy	__builtin_strncpy
69 #endif
70 
71 /**
72  * unsafe_memcpy - memcpy implementation with no FORTIFY bounds checking
73  *
74  * @dst: Destination memory address to write to
75  * @src: Source memory address to read from
76  * @bytes: How many bytes to write to @dst from @src
77  * @justification: Free-form text or comment describing why the use is needed
78  *
79  * This should be used for corner cases where the compiler cannot do the
80  * right thing, or during transitions between APIs, etc. It should be used
81  * very rarely, and includes a place for justification detailing where bounds
82  * checking has happened, and why existing solutions cannot be employed.
83  */
84 #define unsafe_memcpy(dst, src, bytes, justification)		\
85 	__underlying_memcpy(dst, src, bytes)
86 
87 /*
88  * Clang's use of __builtin_*object_size() within inlines needs hinting via
89  * __pass_*object_size(). The preference is to only ever use type 1 (member
90  * size, rather than struct size), but there remain some stragglers using
91  * type 0 that will be converted in the future.
92  */
93 #define POS			__pass_object_size(1)
94 #define POS0			__pass_object_size(0)
95 #define __struct_size(p)	__builtin_object_size(p, 0)
96 #define __member_size(p)	__builtin_object_size(p, 1)
97 
98 #define __compiletime_lessthan(bounds, length)	(	\
99 	__builtin_constant_p((bounds) < (length)) &&	\
100 	(bounds) < (length)				\
101 )
102 
103 /**
104  * strncpy - Copy a string to memory with non-guaranteed NUL padding
105  *
106  * @p: pointer to destination of copy
107  * @q: pointer to NUL-terminated source string to copy
108  * @size: bytes to write at @p
109  *
110  * If strlen(@q) >= @size, the copy of @q will stop after @size bytes,
111  * and @p will NOT be NUL-terminated
112  *
113  * If strlen(@q) < @size, following the copy of @q, trailing NUL bytes
114  * will be written to @p until @size total bytes have been written.
115  *
116  * Do not use this function. While FORTIFY_SOURCE tries to avoid
117  * over-reads of @q, it cannot defend against writing unterminated
118  * results to @p. Using strncpy() remains ambiguous and fragile.
119  * Instead, please choose an alternative, so that the expectation
120  * of @p's contents is unambiguous:
121  *
122  * +--------------------+-----------------+------------+
123  * | @p needs to be:    | padded to @size | not padded |
124  * +====================+=================+============+
125  * |     NUL-terminated | strscpy_pad()   | strscpy()  |
126  * +--------------------+-----------------+------------+
127  * | not NUL-terminated | strtomem_pad()  | strtomem() |
128  * +--------------------+-----------------+------------+
129  *
130  * Note strscpy*()'s differing return values for detecting truncation,
131  * and strtomem*()'s expectation that the destination is marked with
132  * __nonstring when it is a character array.
133  *
134  */
135 __FORTIFY_INLINE __diagnose_as(__builtin_strncpy, 1, 2, 3)
strncpy(char * const POS p,const char * q,__kernel_size_t size)136 char *strncpy(char * const POS p, const char *q, __kernel_size_t size)
137 {
138 	size_t p_size = __member_size(p);
139 
140 	if (__compiletime_lessthan(p_size, size))
141 		__write_overflow();
142 	if (p_size < size)
143 		fortify_panic(__func__);
144 	return __underlying_strncpy(p, q, size);
145 }
146 
147 __FORTIFY_INLINE __diagnose_as(__builtin_strcat, 1, 2)
strcat(char * const POS p,const char * q)148 char *strcat(char * const POS p, const char *q)
149 {
150 	size_t p_size = __member_size(p);
151 
152 	if (p_size == SIZE_MAX)
153 		return __underlying_strcat(p, q);
154 	if (strlcat(p, q, p_size) >= p_size)
155 		fortify_panic(__func__);
156 	return p;
157 }
158 
159 extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
strnlen(const char * const POS p,__kernel_size_t maxlen)160 __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size_t maxlen)
161 {
162 	size_t p_size = __member_size(p);
163 	size_t p_len = __compiletime_strlen(p);
164 	size_t ret;
165 
166 	/* We can take compile-time actions when maxlen is const. */
167 	if (__builtin_constant_p(maxlen) && p_len != SIZE_MAX) {
168 		/* If p is const, we can use its compile-time-known len. */
169 		if (maxlen >= p_size)
170 			return p_len;
171 	}
172 
173 	/* Do not check characters beyond the end of p. */
174 	ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size);
175 	if (p_size <= ret && maxlen != ret)
176 		fortify_panic(__func__);
177 	return ret;
178 }
179 
180 /*
181  * Defined after fortified strnlen to reuse it. However, it must still be
182  * possible for strlen() to be used on compile-time strings for use in
183  * static initializers (i.e. as a constant expression).
184  */
185 #define strlen(p)							\
186 	__builtin_choose_expr(__is_constexpr(__builtin_strlen(p)),	\
187 		__builtin_strlen(p), __fortify_strlen(p))
188 __FORTIFY_INLINE __diagnose_as(__builtin_strlen, 1)
__fortify_strlen(const char * const POS p)189 __kernel_size_t __fortify_strlen(const char * const POS p)
190 {
191 	__kernel_size_t ret;
192 	size_t p_size = __member_size(p);
193 
194 	/* Give up if we don't know how large p is. */
195 	if (p_size == SIZE_MAX)
196 		return __underlying_strlen(p);
197 	ret = strnlen(p, p_size);
198 	if (p_size <= ret)
199 		fortify_panic(__func__);
200 	return ret;
201 }
202 
203 /* defined after fortified strlen to reuse it */
204 extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
strlcpy(char * const POS p,const char * const POS q,size_t size)205 __FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size)
206 {
207 	size_t p_size = __member_size(p);
208 	size_t q_size = __member_size(q);
209 	size_t q_len;	/* Full count of source string length. */
210 	size_t len;	/* Count of characters going into destination. */
211 
212 	if (p_size == SIZE_MAX && q_size == SIZE_MAX)
213 		return __real_strlcpy(p, q, size);
214 	q_len = strlen(q);
215 	len = (q_len >= size) ? size - 1 : q_len;
216 	if (__builtin_constant_p(size) && __builtin_constant_p(q_len) && size) {
217 		/* Write size is always larger than destination. */
218 		if (len >= p_size)
219 			__write_overflow();
220 	}
221 	if (size) {
222 		if (len >= p_size)
223 			fortify_panic(__func__);
224 		__underlying_memcpy(p, q, len);
225 		p[len] = '\0';
226 	}
227 	return q_len;
228 }
229 
230 /* defined after fortified strnlen to reuse it */
231 extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);
strscpy(char * const POS p,const char * const POS q,size_t size)232 __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, size_t size)
233 {
234 	size_t len;
235 	/* Use string size rather than possible enclosing struct size. */
236 	size_t p_size = __member_size(p);
237 	size_t q_size = __member_size(q);
238 
239 	/* If we cannot get size of p and q default to call strscpy. */
240 	if (p_size == SIZE_MAX && q_size == SIZE_MAX)
241 		return __real_strscpy(p, q, size);
242 
243 	/*
244 	 * If size can be known at compile time and is greater than
245 	 * p_size, generate a compile time write overflow error.
246 	 */
247 	if (__compiletime_lessthan(p_size, size))
248 		__write_overflow();
249 
250 	/*
251 	 * This call protects from read overflow, because len will default to q
252 	 * length if it smaller than size.
253 	 */
254 	len = strnlen(q, size);
255 	/*
256 	 * If len equals size, we will copy only size bytes which leads to
257 	 * -E2BIG being returned.
258 	 * Otherwise we will copy len + 1 because of the final '\O'.
259 	 */
260 	len = len == size ? size : len + 1;
261 
262 	/*
263 	 * Generate a runtime write overflow error if len is greater than
264 	 * p_size.
265 	 */
266 	if (len > p_size)
267 		fortify_panic(__func__);
268 
269 	/*
270 	 * We can now safely call vanilla strscpy because we are protected from:
271 	 * 1. Read overflow thanks to call to strnlen().
272 	 * 2. Write overflow thanks to above ifs.
273 	 */
274 	return __real_strscpy(p, q, len);
275 }
276 
277 /* defined after fortified strlen and strnlen to reuse them */
278 __FORTIFY_INLINE __diagnose_as(__builtin_strncat, 1, 2, 3)
strncat(char * const POS p,const char * const POS q,__kernel_size_t count)279 char *strncat(char * const POS p, const char * const POS q, __kernel_size_t count)
280 {
281 	size_t p_len, copy_len;
282 	size_t p_size = __member_size(p);
283 	size_t q_size = __member_size(q);
284 
285 	if (p_size == SIZE_MAX && q_size == SIZE_MAX)
286 		return __underlying_strncat(p, q, count);
287 	p_len = strlen(p);
288 	copy_len = strnlen(q, count);
289 	if (p_size < p_len + copy_len + 1)
290 		fortify_panic(__func__);
291 	__underlying_memcpy(p + p_len, q, copy_len);
292 	p[p_len + copy_len] = '\0';
293 	return p;
294 }
295 
fortify_memset_chk(__kernel_size_t size,const size_t p_size,const size_t p_size_field)296 __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size,
297 					 const size_t p_size,
298 					 const size_t p_size_field)
299 {
300 	if (__builtin_constant_p(size)) {
301 		/*
302 		 * Length argument is a constant expression, so we
303 		 * can perform compile-time bounds checking where
304 		 * buffer sizes are also known at compile time.
305 		 */
306 
307 		/* Error when size is larger than enclosing struct. */
308 		if (__compiletime_lessthan(p_size_field, p_size) &&
309 		    __compiletime_lessthan(p_size, size))
310 			__write_overflow();
311 
312 		/* Warn when write size is larger than dest field. */
313 		if (__compiletime_lessthan(p_size_field, size))
314 			__write_overflow_field(p_size_field, size);
315 	}
316 	/*
317 	 * At this point, length argument may not be a constant expression,
318 	 * so run-time bounds checking can be done where buffer sizes are
319 	 * known. (This is not an "else" because the above checks may only
320 	 * be compile-time warnings, and we want to still warn for run-time
321 	 * overflows.)
322 	 */
323 
324 	/*
325 	 * Always stop accesses beyond the struct that contains the
326 	 * field, when the buffer's remaining size is known.
327 	 * (The SIZE_MAX test is to optimize away checks where the buffer
328 	 * lengths are unknown.)
329 	 */
330 	if (p_size != SIZE_MAX && p_size < size)
331 		fortify_panic("memset");
332 }
333 
334 #define __fortify_memset_chk(p, c, size, p_size, p_size_field) ({	\
335 	size_t __fortify_size = (size_t)(size);				\
336 	fortify_memset_chk(__fortify_size, p_size, p_size_field),	\
337 	__underlying_memset(p, c, __fortify_size);			\
338 })
339 
340 /*
341  * __struct_size() vs __member_size() must be captured here to avoid
342  * evaluating argument side-effects further into the macro layers.
343  */
344 #ifndef CONFIG_KMSAN
345 #define memset(p, c, s) __fortify_memset_chk(p, c, s,			\
346 		__struct_size(p), __member_size(p))
347 #endif
348 
349 /*
350  * To make sure the compiler can enforce protection against buffer overflows,
351  * memcpy(), memmove(), and memset() must not be used beyond individual
352  * struct members. If you need to copy across multiple members, please use
353  * struct_group() to create a named mirror of an anonymous struct union.
354  * (e.g. see struct sk_buff.) Read overflow checking is currently only
355  * done when a write overflow is also present, or when building with W=1.
356  *
357  * Mitigation coverage matrix
358  *					Bounds checking at:
359  *					+-------+-------+-------+-------+
360  *					| Compile time  |   Run time    |
361  * memcpy() argument sizes:		| write | read  | write | read  |
362  *        dest     source   length      +-------+-------+-------+-------+
363  * memcpy(known,   known,   constant)	|   y   |   y   |  n/a  |  n/a  |
364  * memcpy(known,   unknown, constant)	|   y   |   n   |  n/a  |   V   |
365  * memcpy(known,   known,   dynamic)	|   n   |   n   |   B   |   B   |
366  * memcpy(known,   unknown, dynamic)	|   n   |   n   |   B   |   V   |
367  * memcpy(unknown, known,   constant)	|   n   |   y   |   V   |  n/a  |
368  * memcpy(unknown, unknown, constant)	|   n   |   n   |   V   |   V   |
369  * memcpy(unknown, known,   dynamic)	|   n   |   n   |   V   |   B   |
370  * memcpy(unknown, unknown, dynamic)	|   n   |   n   |   V   |   V   |
371  *					+-------+-------+-------+-------+
372  *
373  * y = perform deterministic compile-time bounds checking
374  * n = cannot perform deterministic compile-time bounds checking
375  * n/a = no run-time bounds checking needed since compile-time deterministic
376  * B = can perform run-time bounds checking (currently unimplemented)
377  * V = vulnerable to run-time overflow (will need refactoring to solve)
378  *
379  */
fortify_memcpy_chk(__kernel_size_t size,const size_t p_size,const size_t q_size,const size_t p_size_field,const size_t q_size_field,const char * func)380 __FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size,
381 					 const size_t p_size,
382 					 const size_t q_size,
383 					 const size_t p_size_field,
384 					 const size_t q_size_field,
385 					 const char *func)
386 {
387 	if (__builtin_constant_p(size)) {
388 		/*
389 		 * Length argument is a constant expression, so we
390 		 * can perform compile-time bounds checking where
391 		 * buffer sizes are also known at compile time.
392 		 */
393 
394 		/* Error when size is larger than enclosing struct. */
395 		if (__compiletime_lessthan(p_size_field, p_size) &&
396 		    __compiletime_lessthan(p_size, size))
397 			__write_overflow();
398 		if (__compiletime_lessthan(q_size_field, q_size) &&
399 		    __compiletime_lessthan(q_size, size))
400 			__read_overflow2();
401 
402 		/* Warn when write size argument larger than dest field. */
403 		if (__compiletime_lessthan(p_size_field, size))
404 			__write_overflow_field(p_size_field, size);
405 		/*
406 		 * Warn for source field over-read when building with W=1
407 		 * or when an over-write happened, so both can be fixed at
408 		 * the same time.
409 		 */
410 		if ((IS_ENABLED(KBUILD_EXTRA_WARN1) ||
411 		     __compiletime_lessthan(p_size_field, size)) &&
412 		    __compiletime_lessthan(q_size_field, size))
413 			__read_overflow2_field(q_size_field, size);
414 	}
415 	/*
416 	 * At this point, length argument may not be a constant expression,
417 	 * so run-time bounds checking can be done where buffer sizes are
418 	 * known. (This is not an "else" because the above checks may only
419 	 * be compile-time warnings, and we want to still warn for run-time
420 	 * overflows.)
421 	 */
422 
423 	/*
424 	 * Always stop accesses beyond the struct that contains the
425 	 * field, when the buffer's remaining size is known.
426 	 * (The SIZE_MAX test is to optimize away checks where the buffer
427 	 * lengths are unknown.)
428 	 */
429 	if ((p_size != SIZE_MAX && p_size < size) ||
430 	    (q_size != SIZE_MAX && q_size < size))
431 		fortify_panic(func);
432 
433 	/*
434 	 * Warn when writing beyond destination field size.
435 	 *
436 	 * We must ignore p_size_field == 0 for existing 0-element
437 	 * fake flexible arrays, until they are all converted to
438 	 * proper flexible arrays.
439 	 *
440 	 * The implementation of __builtin_*object_size() behaves
441 	 * like sizeof() when not directly referencing a flexible
442 	 * array member, which means there will be many bounds checks
443 	 * that will appear at run-time, without a way for them to be
444 	 * detected at compile-time (as can be done when the destination
445 	 * is specifically the flexible array member).
446 	 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101832
447 	 */
448 	if (p_size_field != 0 && p_size_field != SIZE_MAX &&
449 	    p_size != p_size_field && p_size_field < size)
450 		return true;
451 
452 	return false;
453 }
454 
455 #define __fortify_memcpy_chk(p, q, size, p_size, q_size,		\
456 			     p_size_field, q_size_field, op) ({		\
457 	const size_t __fortify_size = (size_t)(size);			\
458 	const size_t __p_size = (p_size);				\
459 	const size_t __q_size = (q_size);				\
460 	const size_t __p_size_field = (p_size_field);			\
461 	const size_t __q_size_field = (q_size_field);			\
462 	WARN_ONCE(fortify_memcpy_chk(__fortify_size, __p_size,		\
463 				     __q_size, __p_size_field,		\
464 				     __q_size_field, #op),		\
465 		  #op ": detected field-spanning write (size %zu) of single %s (size %zu)\n", \
466 		  __fortify_size,					\
467 		  "field \"" #p "\" at " __FILE__ ":" __stringify(__LINE__), \
468 		  __p_size_field);					\
469 	__underlying_##op(p, q, __fortify_size);			\
470 })
471 
472 /*
473  * Notes about compile-time buffer size detection:
474  *
475  * With these types...
476  *
477  *	struct middle {
478  *		u16 a;
479  *		u8 middle_buf[16];
480  *		int b;
481  *	};
482  *	struct end {
483  *		u16 a;
484  *		u8 end_buf[16];
485  *	};
486  *	struct flex {
487  *		int a;
488  *		u8 flex_buf[];
489  *	};
490  *
491  *	void func(TYPE *ptr) { ... }
492  *
493  * Cases where destination size cannot be currently detected:
494  * - the size of ptr's object (seemingly by design, gcc & clang fail):
495  *	__builtin_object_size(ptr, 1) == SIZE_MAX
496  * - the size of flexible arrays in ptr's obj (by design, dynamic size):
497  *	__builtin_object_size(ptr->flex_buf, 1) == SIZE_MAX
498  * - the size of ANY array at the end of ptr's obj (gcc and clang bug):
499  *	__builtin_object_size(ptr->end_buf, 1) == SIZE_MAX
500  *	https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836
501  *
502  * Cases where destination size is currently detected:
503  * - the size of non-array members within ptr's object:
504  *	__builtin_object_size(ptr->a, 1) == 2
505  * - the size of non-flexible-array in the middle of ptr's obj:
506  *	__builtin_object_size(ptr->middle_buf, 1) == 16
507  *
508  */
509 
510 /*
511  * __struct_size() vs __member_size() must be captured here to avoid
512  * evaluating argument side-effects further into the macro layers.
513  */
514 #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,			\
515 		__struct_size(p), __struct_size(q),			\
516 		__member_size(p), __member_size(q),			\
517 		memcpy)
518 #define memmove(p, q, s)  __fortify_memcpy_chk(p, q, s,			\
519 		__struct_size(p), __struct_size(q),			\
520 		__member_size(p), __member_size(q),			\
521 		memmove)
522 
523 extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
memscan(void * const POS0 p,int c,__kernel_size_t size)524 __FORTIFY_INLINE void *memscan(void * const POS0 p, int c, __kernel_size_t size)
525 {
526 	size_t p_size = __struct_size(p);
527 
528 	if (__compiletime_lessthan(p_size, size))
529 		__read_overflow();
530 	if (p_size < size)
531 		fortify_panic(__func__);
532 	return __real_memscan(p, c, size);
533 }
534 
535 __FORTIFY_INLINE __diagnose_as(__builtin_memcmp, 1, 2, 3)
memcmp(const void * const POS0 p,const void * const POS0 q,__kernel_size_t size)536 int memcmp(const void * const POS0 p, const void * const POS0 q, __kernel_size_t size)
537 {
538 	size_t p_size = __struct_size(p);
539 	size_t q_size = __struct_size(q);
540 
541 	if (__builtin_constant_p(size)) {
542 		if (__compiletime_lessthan(p_size, size))
543 			__read_overflow();
544 		if (__compiletime_lessthan(q_size, size))
545 			__read_overflow2();
546 	}
547 	if (p_size < size || q_size < size)
548 		fortify_panic(__func__);
549 	return __underlying_memcmp(p, q, size);
550 }
551 
552 __FORTIFY_INLINE __diagnose_as(__builtin_memchr, 1, 2, 3)
memchr(const void * const POS0 p,int c,__kernel_size_t size)553 void *memchr(const void * const POS0 p, int c, __kernel_size_t size)
554 {
555 	size_t p_size = __struct_size(p);
556 
557 	if (__compiletime_lessthan(p_size, size))
558 		__read_overflow();
559 	if (p_size < size)
560 		fortify_panic(__func__);
561 	return __underlying_memchr(p, c, size);
562 }
563 
564 void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
memchr_inv(const void * const POS0 p,int c,size_t size)565 __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size)
566 {
567 	size_t p_size = __struct_size(p);
568 
569 	if (__compiletime_lessthan(p_size, size))
570 		__read_overflow();
571 	if (p_size < size)
572 		fortify_panic(__func__);
573 	return __real_memchr_inv(p, c, size);
574 }
575 
576 extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup);
kmemdup(const void * const POS0 p,size_t size,gfp_t gfp)577 __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp)
578 {
579 	size_t p_size = __struct_size(p);
580 
581 	if (__compiletime_lessthan(p_size, size))
582 		__read_overflow();
583 	if (p_size < size)
584 		fortify_panic(__func__);
585 	return __real_kmemdup(p, size, gfp);
586 }
587 
588 /* Defined after fortified strlen to reuse it. */
589 __FORTIFY_INLINE __diagnose_as(__builtin_strcpy, 1, 2)
strcpy(char * const POS p,const char * const POS q)590 char *strcpy(char * const POS p, const char * const POS q)
591 {
592 	size_t p_size = __member_size(p);
593 	size_t q_size = __member_size(q);
594 	size_t size;
595 
596 	/* If neither buffer size is known, immediately give up. */
597 	if (__builtin_constant_p(p_size) &&
598 	    __builtin_constant_p(q_size) &&
599 	    p_size == SIZE_MAX && q_size == SIZE_MAX)
600 		return __underlying_strcpy(p, q);
601 	size = strlen(q) + 1;
602 	/* Compile-time check for const size overflow. */
603 	if (__compiletime_lessthan(p_size, size))
604 		__write_overflow();
605 	/* Run-time check for dynamic size overflow. */
606 	if (p_size < size)
607 		fortify_panic(__func__);
608 	__underlying_memcpy(p, q, size);
609 	return p;
610 }
611 
612 /* Don't use these outside the FORITFY_SOURCE implementation */
613 #undef __underlying_memchr
614 #undef __underlying_memcmp
615 #undef __underlying_strcat
616 #undef __underlying_strcpy
617 #undef __underlying_strlen
618 #undef __underlying_strncat
619 #undef __underlying_strncpy
620 
621 #undef POS
622 #undef POS0
623 
624 #endif /* _LINUX_FORTIFY_STRING_H_ */
625