xref: /linux-6.15/include/linux/string.h (revision c8a950d0) 
1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_STRING_H_
3 #define _LINUX_STRING_H_
4 
5 
6 #include <linux/compiler.h>	/* for inline */
7 #include <linux/types.h>	/* for size_t */
8 #include <linux/stddef.h>	/* for NULL */
9 #include <stdarg.h>
10 #include <uapi/linux/string.h>
11 
12 extern char *strndup_user(const char __user *, long);
13 extern void *memdup_user(const void __user *, size_t);
14 extern void *vmemdup_user(const void __user *, size_t);
15 extern void *memdup_user_nul(const void __user *, size_t);
16 
17 /*
18  * Include machine specific inline routines
19  */
20 #include <asm/string.h>
21 
22 #ifndef __HAVE_ARCH_STRCPY
23 extern char * strcpy(char *,const char *);
24 #endif
25 #ifndef __HAVE_ARCH_STRNCPY
26 extern char * strncpy(char *,const char *, __kernel_size_t);
27 #endif
28 #ifndef __HAVE_ARCH_STRLCPY
29 size_t strlcpy(char *, const char *, size_t);
30 #endif
31 #ifndef __HAVE_ARCH_STRSCPY
32 ssize_t strscpy(char *, const char *, size_t);
33 #endif
34 
35 /* Wraps calls to strscpy()/memset(), no arch specific code required */
36 ssize_t strscpy_pad(char *dest, const char *src, size_t count);
37 
38 #ifndef __HAVE_ARCH_STRCAT
39 extern char * strcat(char *, const char *);
40 #endif
41 #ifndef __HAVE_ARCH_STRNCAT
42 extern char * strncat(char *, const char *, __kernel_size_t);
43 #endif
44 #ifndef __HAVE_ARCH_STRLCAT
45 extern size_t strlcat(char *, const char *, __kernel_size_t);
46 #endif
47 #ifndef __HAVE_ARCH_STRCMP
48 extern int strcmp(const char *,const char *);
49 #endif
50 #ifndef __HAVE_ARCH_STRNCMP
51 extern int strncmp(const char *,const char *,__kernel_size_t);
52 #endif
53 #ifndef __HAVE_ARCH_STRCASECMP
54 extern int strcasecmp(const char *s1, const char *s2);
55 #endif
56 #ifndef __HAVE_ARCH_STRNCASECMP
57 extern int strncasecmp(const char *s1, const char *s2, size_t n);
58 #endif
59 #ifndef __HAVE_ARCH_STRCHR
60 extern char * strchr(const char *,int);
61 #endif
62 #ifndef __HAVE_ARCH_STRCHRNUL
63 extern char * strchrnul(const char *,int);
64 #endif
65 extern char * strnchrnul(const char *, size_t, int);
66 #ifndef __HAVE_ARCH_STRNCHR
67 extern char * strnchr(const char *, size_t, int);
68 #endif
69 #ifndef __HAVE_ARCH_STRRCHR
70 extern char * strrchr(const char *,int);
71 #endif
72 extern char * __must_check skip_spaces(const char *);
73 
74 extern char *strim(char *);
75 
76 static inline __must_check char *strstrip(char *str)
77 {
78 	return strim(str);
79 }
80 
81 #ifndef __HAVE_ARCH_STRSTR
82 extern char * strstr(const char *, const char *);
83 #endif
84 #ifndef __HAVE_ARCH_STRNSTR
85 extern char * strnstr(const char *, const char *, size_t);
86 #endif
87 #ifndef __HAVE_ARCH_STRLEN
88 extern __kernel_size_t strlen(const char *);
89 #endif
90 #ifndef __HAVE_ARCH_STRNLEN
91 extern __kernel_size_t strnlen(const char *,__kernel_size_t);
92 #endif
93 #ifndef __HAVE_ARCH_STRPBRK
94 extern char * strpbrk(const char *,const char *);
95 #endif
96 #ifndef __HAVE_ARCH_STRSEP
97 extern char * strsep(char **,const char *);
98 #endif
99 #ifndef __HAVE_ARCH_STRSPN
100 extern __kernel_size_t strspn(const char *,const char *);
101 #endif
102 #ifndef __HAVE_ARCH_STRCSPN
103 extern __kernel_size_t strcspn(const char *,const char *);
104 #endif
105 
106 #ifndef __HAVE_ARCH_MEMSET
107 extern void * memset(void *,int,__kernel_size_t);
108 #endif
109 
110 #ifndef __HAVE_ARCH_MEMSET16
111 extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
112 #endif
113 
114 #ifndef __HAVE_ARCH_MEMSET32
115 extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
116 #endif
117 
118 #ifndef __HAVE_ARCH_MEMSET64
119 extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
120 #endif
121 
122 static inline void *memset_l(unsigned long *p, unsigned long v,
123 		__kernel_size_t n)
124 {
125 	if (BITS_PER_LONG == 32)
126 		return memset32((uint32_t *)p, v, n);
127 	else
128 		return memset64((uint64_t *)p, v, n);
129 }
130 
131 static inline void *memset_p(void **p, void *v, __kernel_size_t n)
132 {
133 	if (BITS_PER_LONG == 32)
134 		return memset32((uint32_t *)p, (uintptr_t)v, n);
135 	else
136 		return memset64((uint64_t *)p, (uintptr_t)v, n);
137 }
138 
139 extern void **__memcat_p(void **a, void **b);
140 #define memcat_p(a, b) ({					\
141 	BUILD_BUG_ON_MSG(!__same_type(*(a), *(b)),		\
142 			 "type mismatch in memcat_p()");	\
143 	(typeof(*a) *)__memcat_p((void **)(a), (void **)(b));	\
144 })
145 
146 #ifndef __HAVE_ARCH_MEMCPY
147 extern void * memcpy(void *,const void *,__kernel_size_t);
148 #endif
149 #ifndef __HAVE_ARCH_MEMMOVE
150 extern void * memmove(void *,const void *,__kernel_size_t);
151 #endif
152 #ifndef __HAVE_ARCH_MEMSCAN
153 extern void * memscan(void *,int,__kernel_size_t);
154 #endif
155 #ifndef __HAVE_ARCH_MEMCMP
156 extern int memcmp(const void *,const void *,__kernel_size_t);
157 #endif
158 #ifndef __HAVE_ARCH_BCMP
159 extern int bcmp(const void *,const void *,__kernel_size_t);
160 #endif
161 #ifndef __HAVE_ARCH_MEMCHR
162 extern void * memchr(const void *,int,__kernel_size_t);
163 #endif
164 #ifndef __HAVE_ARCH_MEMCPY_FLUSHCACHE
165 static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
166 {
167 	memcpy(dst, src, cnt);
168 }
169 #endif
170 
171 void *memchr_inv(const void *s, int c, size_t n);
172 char *strreplace(char *s, char old, char new);
173 
174 extern void kfree_const(const void *x);
175 
176 extern char *kstrdup(const char *s, gfp_t gfp) __malloc;
177 extern const char *kstrdup_const(const char *s, gfp_t gfp);
178 extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
179 extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
180 extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp);
181 
182 extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
183 extern void argv_free(char **argv);
184 
185 extern bool sysfs_streq(const char *s1, const char *s2);
186 extern int kstrtobool(const char *s, bool *res);
187 static inline int strtobool(const char *s, bool *res)
188 {
189 	return kstrtobool(s, res);
190 }
191 
192 int match_string(const char * const *array, size_t n, const char *string);
193 int __sysfs_match_string(const char * const *array, size_t n, const char *s);
194 
195 /**
196  * sysfs_match_string - matches given string in an array
197  * @_a: array of strings
198  * @_s: string to match with
199  *
200  * Helper for __sysfs_match_string(). Calculates the size of @a automatically.
201  */
202 #define sysfs_match_string(_a, _s) __sysfs_match_string(_a, ARRAY_SIZE(_a), _s)
203 
204 #ifdef CONFIG_BINARY_PRINTF
205 int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
206 int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);
207 int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
208 #endif
209 
210 extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
211 				       const void *from, size_t available);
212 
213 int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);
214 
215 /**
216  * strstarts - does @str start with @prefix?
217  * @str: string to examine
218  * @prefix: prefix to look for.
219  */
220 static inline bool strstarts(const char *str, const char *prefix)
221 {
222 	return strncmp(str, prefix, strlen(prefix)) == 0;
223 }
224 
225 size_t memweight(const void *ptr, size_t bytes);
226 
227 /**
228  * memzero_explicit - Fill a region of memory (e.g. sensitive
229  *		      keying data) with 0s.
230  * @s: Pointer to the start of the area.
231  * @count: The size of the area.
232  *
233  * Note: usually using memset() is just fine (!), but in cases
234  * where clearing out _local_ data at the end of a scope is
235  * necessary, memzero_explicit() should be used instead in
236  * order to prevent the compiler from optimising away zeroing.
237  *
238  * memzero_explicit() doesn't need an arch-specific version as
239  * it just invokes the one of memset() implicitly.
240  */
241 static inline void memzero_explicit(void *s, size_t count)
242 {
243 	memset(s, 0, count);
244 	barrier_data(s);
245 }
246 
247 /**
248  * kbasename - return the last part of a pathname.
249  *
250  * @path: path to extract the filename from.
251  */
252 static inline const char *kbasename(const char *path)
253 {
254 	const char *tail = strrchr(path, '/');
255 	return tail ? tail + 1 : path;
256 }
257 
258 #define __FORTIFY_INLINE extern __always_inline __attribute__((gnu_inline))
259 #define __RENAME(x) __asm__(#x)
260 
261 void fortify_panic(const char *name) __noreturn __cold;
262 void __read_overflow(void) __compiletime_error("detected read beyond size of object passed as 1st parameter");
263 void __read_overflow2(void) __compiletime_error("detected read beyond size of object passed as 2nd parameter");
264 void __read_overflow3(void) __compiletime_error("detected read beyond size of object passed as 3rd parameter");
265 void __write_overflow(void) __compiletime_error("detected write beyond size of object passed as 1st parameter");
266 
267 #if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
268 
269 #ifdef CONFIG_KASAN
270 extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
271 extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
272 extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
273 extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
274 extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
275 extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
276 extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
277 extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
278 extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
279 extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
280 #else
281 #define __underlying_memchr	__builtin_memchr
282 #define __underlying_memcmp	__builtin_memcmp
283 #define __underlying_memcpy	__builtin_memcpy
284 #define __underlying_memmove	__builtin_memmove
285 #define __underlying_memset	__builtin_memset
286 #define __underlying_strcat	__builtin_strcat
287 #define __underlying_strcpy	__builtin_strcpy
288 #define __underlying_strlen	__builtin_strlen
289 #define __underlying_strncat	__builtin_strncat
290 #define __underlying_strncpy	__builtin_strncpy
291 #endif
292 
293 __FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size)
294 {
295 	size_t p_size = __builtin_object_size(p, 0);
296 	if (__builtin_constant_p(size) && p_size < size)
297 		__write_overflow();
298 	if (p_size < size)
299 		fortify_panic(__func__);
300 	return __underlying_strncpy(p, q, size);
301 }
302 
303 __FORTIFY_INLINE char *strcat(char *p, const char *q)
304 {
305 	size_t p_size = __builtin_object_size(p, 0);
306 	if (p_size == (size_t)-1)
307 		return __underlying_strcat(p, q);
308 	if (strlcat(p, q, p_size) >= p_size)
309 		fortify_panic(__func__);
310 	return p;
311 }
312 
313 __FORTIFY_INLINE __kernel_size_t strlen(const char *p)
314 {
315 	__kernel_size_t ret;
316 	size_t p_size = __builtin_object_size(p, 0);
317 
318 	/* Work around gcc excess stack consumption issue */
319 	if (p_size == (size_t)-1 ||
320 	    (__builtin_constant_p(p[p_size - 1]) && p[p_size - 1] == '\0'))
321 		return __underlying_strlen(p);
322 	ret = strnlen(p, p_size);
323 	if (p_size <= ret)
324 		fortify_panic(__func__);
325 	return ret;
326 }
327 
328 extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
329 __FORTIFY_INLINE __kernel_size_t strnlen(const char *p, __kernel_size_t maxlen)
330 {
331 	size_t p_size = __builtin_object_size(p, 0);
332 	__kernel_size_t ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size);
333 	if (p_size <= ret && maxlen != ret)
334 		fortify_panic(__func__);
335 	return ret;
336 }
337 
338 /* defined after fortified strlen to reuse it */
339 extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
340 __FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size)
341 {
342 	size_t ret;
343 	size_t p_size = __builtin_object_size(p, 0);
344 	size_t q_size = __builtin_object_size(q, 0);
345 	if (p_size == (size_t)-1 && q_size == (size_t)-1)
346 		return __real_strlcpy(p, q, size);
347 	ret = strlen(q);
348 	if (size) {
349 		size_t len = (ret >= size) ? size - 1 : ret;
350 		if (__builtin_constant_p(len) && len >= p_size)
351 			__write_overflow();
352 		if (len >= p_size)
353 			fortify_panic(__func__);
354 		__underlying_memcpy(p, q, len);
355 		p[len] = '\0';
356 	}
357 	return ret;
358 }
359 
360 /* defined after fortified strlen and strnlen to reuse them */
361 __FORTIFY_INLINE char *strncat(char *p, const char *q, __kernel_size_t count)
362 {
363 	size_t p_len, copy_len;
364 	size_t p_size = __builtin_object_size(p, 0);
365 	size_t q_size = __builtin_object_size(q, 0);
366 	if (p_size == (size_t)-1 && q_size == (size_t)-1)
367 		return __underlying_strncat(p, q, count);
368 	p_len = strlen(p);
369 	copy_len = strnlen(q, count);
370 	if (p_size < p_len + copy_len + 1)
371 		fortify_panic(__func__);
372 	__underlying_memcpy(p + p_len, q, copy_len);
373 	p[p_len + copy_len] = '\0';
374 	return p;
375 }
376 
377 __FORTIFY_INLINE void *memset(void *p, int c, __kernel_size_t size)
378 {
379 	size_t p_size = __builtin_object_size(p, 0);
380 	if (__builtin_constant_p(size) && p_size < size)
381 		__write_overflow();
382 	if (p_size < size)
383 		fortify_panic(__func__);
384 	return __underlying_memset(p, c, size);
385 }
386 
387 __FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size)
388 {
389 	size_t p_size = __builtin_object_size(p, 0);
390 	size_t q_size = __builtin_object_size(q, 0);
391 	if (__builtin_constant_p(size)) {
392 		if (p_size < size)
393 			__write_overflow();
394 		if (q_size < size)
395 			__read_overflow2();
396 	}
397 	if (p_size < size || q_size < size)
398 		fortify_panic(__func__);
399 	return __underlying_memcpy(p, q, size);
400 }
401 
402 __FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size)
403 {
404 	size_t p_size = __builtin_object_size(p, 0);
405 	size_t q_size = __builtin_object_size(q, 0);
406 	if (__builtin_constant_p(size)) {
407 		if (p_size < size)
408 			__write_overflow();
409 		if (q_size < size)
410 			__read_overflow2();
411 	}
412 	if (p_size < size || q_size < size)
413 		fortify_panic(__func__);
414 	return __underlying_memmove(p, q, size);
415 }
416 
417 extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
418 __FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size)
419 {
420 	size_t p_size = __builtin_object_size(p, 0);
421 	if (__builtin_constant_p(size) && p_size < size)
422 		__read_overflow();
423 	if (p_size < size)
424 		fortify_panic(__func__);
425 	return __real_memscan(p, c, size);
426 }
427 
428 __FORTIFY_INLINE int memcmp(const void *p, const void *q, __kernel_size_t size)
429 {
430 	size_t p_size = __builtin_object_size(p, 0);
431 	size_t q_size = __builtin_object_size(q, 0);
432 	if (__builtin_constant_p(size)) {
433 		if (p_size < size)
434 			__read_overflow();
435 		if (q_size < size)
436 			__read_overflow2();
437 	}
438 	if (p_size < size || q_size < size)
439 		fortify_panic(__func__);
440 	return __underlying_memcmp(p, q, size);
441 }
442 
443 __FORTIFY_INLINE void *memchr(const void *p, int c, __kernel_size_t size)
444 {
445 	size_t p_size = __builtin_object_size(p, 0);
446 	if (__builtin_constant_p(size) && p_size < size)
447 		__read_overflow();
448 	if (p_size < size)
449 		fortify_panic(__func__);
450 	return __underlying_memchr(p, c, size);
451 }
452 
453 void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
454 __FORTIFY_INLINE void *memchr_inv(const void *p, int c, size_t size)
455 {
456 	size_t p_size = __builtin_object_size(p, 0);
457 	if (__builtin_constant_p(size) && p_size < size)
458 		__read_overflow();
459 	if (p_size < size)
460 		fortify_panic(__func__);
461 	return __real_memchr_inv(p, c, size);
462 }
463 
464 extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup);
465 __FORTIFY_INLINE void *kmemdup(const void *p, size_t size, gfp_t gfp)
466 {
467 	size_t p_size = __builtin_object_size(p, 0);
468 	if (__builtin_constant_p(size) && p_size < size)
469 		__read_overflow();
470 	if (p_size < size)
471 		fortify_panic(__func__);
472 	return __real_kmemdup(p, size, gfp);
473 }
474 
475 /* defined after fortified strlen and memcpy to reuse them */
476 __FORTIFY_INLINE char *strcpy(char *p, const char *q)
477 {
478 	size_t p_size = __builtin_object_size(p, 0);
479 	size_t q_size = __builtin_object_size(q, 0);
480 	if (p_size == (size_t)-1 && q_size == (size_t)-1)
481 		return __underlying_strcpy(p, q);
482 	memcpy(p, q, strlen(q) + 1);
483 	return p;
484 }
485 
486 /* Don't use these outside the FORITFY_SOURCE implementation */
487 #undef __underlying_memchr
488 #undef __underlying_memcmp
489 #undef __underlying_memcpy
490 #undef __underlying_memmove
491 #undef __underlying_memset
492 #undef __underlying_strcat
493 #undef __underlying_strcpy
494 #undef __underlying_strlen
495 #undef __underlying_strncat
496 #undef __underlying_strncpy
497 #endif
498 
499 /**
500  * memcpy_and_pad - Copy one buffer to another with padding
501  * @dest: Where to copy to
502  * @dest_len: The destination buffer size
503  * @src: Where to copy from
504  * @count: The number of bytes to copy
505  * @pad: Character to use for padding if space is left in destination.
506  */
507 static inline void memcpy_and_pad(void *dest, size_t dest_len,
508 				  const void *src, size_t count, int pad)
509 {
510 	if (dest_len > count) {
511 		memcpy(dest, src, count);
512 		memset(dest + count, pad,  dest_len - count);
513 	} else
514 		memcpy(dest, src, dest_len);
515 }
516 
517 /**
518  * str_has_prefix - Test if a string has a given prefix
519  * @str: The string to test
520  * @prefix: The string to see if @str starts with
521  *
522  * A common way to test a prefix of a string is to do:
523  *  strncmp(str, prefix, sizeof(prefix) - 1)
524  *
525  * But this can lead to bugs due to typos, or if prefix is a pointer
526  * and not a constant. Instead use str_has_prefix().
527  *
528  * Returns:
529  * * strlen(@prefix) if @str starts with @prefix
530  * * 0 if @str does not start with @prefix
531  */
532 static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
533 {
534 	size_t len = strlen(prefix);
535 	return strncmp(str, prefix, len) == 0 ? len : 0;
536 }
537 
538 #endif /* _LINUX_STRING_H_ */
539