LXR linux/include/linux/string.h

   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 <linux/errno.h>        /* for E2BIG */
  10#include <stdarg.h>
  11#include <uapi/linux/string.h>
  12
  13extern char *strndup_user(const char __user *, long);
  14extern void *memdup_user(const void __user *, size_t);
  15extern void *vmemdup_user(const void __user *, size_t);
  16extern void *memdup_user_nul(const void __user *, size_t);
  17
  18/*
  19 * Include machine specific inline routines
  20 */
  21#include <asm/string.h>
  22
  23#ifndef __HAVE_ARCH_STRCPY
  24extern char * strcpy(char *,const char *);
  25#endif
  26#ifndef __HAVE_ARCH_STRNCPY
  27extern char * strncpy(char *,const char *, __kernel_size_t);
  28#endif
  29#ifndef __HAVE_ARCH_STRLCPY
  30size_t strlcpy(char *, const char *, size_t);
  31#endif
  32#ifndef __HAVE_ARCH_STRSCPY
  33ssize_t strscpy(char *, const char *, size_t);
  34#endif
  35
  36/* Wraps calls to strscpy()/memset(), no arch specific code required */
  37ssize_t strscpy_pad(char *dest, const char *src, size_t count);
  38
  39#ifndef __HAVE_ARCH_STRCAT
  40extern char * strcat(char *, const char *);
  41#endif
  42#ifndef __HAVE_ARCH_STRNCAT
  43extern char * strncat(char *, const char *, __kernel_size_t);
  44#endif
  45#ifndef __HAVE_ARCH_STRLCAT
  46extern size_t strlcat(char *, const char *, __kernel_size_t);
  47#endif
  48#ifndef __HAVE_ARCH_STRCMP
  49extern int strcmp(const char *,const char *);
  50#endif
  51#ifndef __HAVE_ARCH_STRNCMP
  52extern int strncmp(const char *,const char *,__kernel_size_t);
  53#endif
  54#ifndef __HAVE_ARCH_STRCASECMP
  55extern int strcasecmp(const char *s1, const char *s2);
  56#endif
  57#ifndef __HAVE_ARCH_STRNCASECMP
  58extern int strncasecmp(const char *s1, const char *s2, size_t n);
  59#endif
  60#ifndef __HAVE_ARCH_STRCHR
  61extern char * strchr(const char *,int);
  62#endif
  63#ifndef __HAVE_ARCH_STRCHRNUL
  64extern char * strchrnul(const char *,int);
  65#endif
  66extern char * strnchrnul(const char *, size_t, int);
  67#ifndef __HAVE_ARCH_STRNCHR
  68extern char * strnchr(const char *, size_t, int);
  69#endif
  70#ifndef __HAVE_ARCH_STRRCHR
  71extern char * strrchr(const char *,int);
  72#endif
  73extern char * __must_check skip_spaces(const char *);
  74
  75extern char *strim(char *);
  76
  77static inline __must_check char *strstrip(char *str)
  78{
  79        return strim(str);
  80}
  81
  82#ifndef __HAVE_ARCH_STRSTR
  83extern char * strstr(const char *, const char *);
  84#endif
  85#ifndef __HAVE_ARCH_STRNSTR
  86extern char * strnstr(const char *, const char *, size_t);
  87#endif
  88#ifndef __HAVE_ARCH_STRLEN
  89extern __kernel_size_t strlen(const char *);
  90#endif
  91#ifndef __HAVE_ARCH_STRNLEN
  92extern __kernel_size_t strnlen(const char *,__kernel_size_t);
  93#endif
  94#ifndef __HAVE_ARCH_STRPBRK
  95extern char * strpbrk(const char *,const char *);
  96#endif
  97#ifndef __HAVE_ARCH_STRSEP
  98extern char * strsep(char **,const char *);
  99#endif
 100#ifndef __HAVE_ARCH_STRSPN
 101extern __kernel_size_t strspn(const char *,const char *);
 102#endif
 103#ifndef __HAVE_ARCH_STRCSPN
 104extern __kernel_size_t strcspn(const char *,const char *);
 105#endif
 106
 107#ifndef __HAVE_ARCH_MEMSET
 108extern void * memset(void *,int,__kernel_size_t);
 109#endif
 110
 111#ifndef __HAVE_ARCH_MEMSET16
 112extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
 113#endif
 114
 115#ifndef __HAVE_ARCH_MEMSET32
 116extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
 117#endif
 118
 119#ifndef __HAVE_ARCH_MEMSET64
 120extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
 121#endif
 122
 123static inline void *memset_l(unsigned long *p, unsigned long v,
 124                __kernel_size_t n)
 125{
 126        if (BITS_PER_LONG == 32)
 127                return memset32((uint32_t *)p, v, n);
 128        else
 129                return memset64((uint64_t *)p, v, n);
 130}
 131
 132static inline void *memset_p(void **p, void *v, __kernel_size_t n)
 133{
 134        if (BITS_PER_LONG == 32)
 135                return memset32((uint32_t *)p, (uintptr_t)v, n);
 136        else
 137                return memset64((uint64_t *)p, (uintptr_t)v, n);
 138}
 139
 140extern void **__memcat_p(void **a, void **b);
 141#define memcat_p(a, b) ({                                       \
 142        BUILD_BUG_ON_MSG(!__same_type(*(a), *(b)),              \
 143                         "type mismatch in memcat_p()");        \
 144        (typeof(*a) *)__memcat_p((void **)(a), (void **)(b));   \
 145})
 146
 147#ifndef __HAVE_ARCH_MEMCPY
 148extern void * memcpy(void *,const void *,__kernel_size_t);
 149#endif
 150#ifndef __HAVE_ARCH_MEMMOVE
 151extern void * memmove(void *,const void *,__kernel_size_t);
 152#endif
 153#ifndef __HAVE_ARCH_MEMSCAN
 154extern void * memscan(void *,int,__kernel_size_t);
 155#endif
 156#ifndef __HAVE_ARCH_MEMCMP
 157extern int memcmp(const void *,const void *,__kernel_size_t);
 158#endif
 159#ifndef __HAVE_ARCH_BCMP
 160extern int bcmp(const void *,const void *,__kernel_size_t);
 161#endif
 162#ifndef __HAVE_ARCH_MEMCHR
 163extern void * memchr(const void *,int,__kernel_size_t);
 164#endif
 165#ifndef __HAVE_ARCH_MEMCPY_FLUSHCACHE
 166static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
 167{
 168        memcpy(dst, src, cnt);
 169}
 170#endif
 171
 172void *memchr_inv(const void *s, int c, size_t n);
 173char *strreplace(char *s, char old, char new);
 174
 175extern void kfree_const(const void *x);
 176
 177extern char *kstrdup(const char *s, gfp_t gfp) __malloc;
 178extern const char *kstrdup_const(const char *s, gfp_t gfp);
 179extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
 180extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
 181extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp);
 182
 183extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
 184extern void argv_free(char **argv);
 185
 186extern bool sysfs_streq(const char *s1, const char *s2);
 187extern int kstrtobool(const char *s, bool *res);
 188static inline int strtobool(const char *s, bool *res)
 189{
 190        return kstrtobool(s, res);
 191}
 192
 193int match_string(const char * const *array, size_t n, const char *string);
 194int __sysfs_match_string(const char * const *array, size_t n, const char *s);
 195
 196/**
 197 * sysfs_match_string - matches given string in an array
 198 * @_a: array of strings
 199 * @_s: string to match with
 200 *
 201 * Helper for __sysfs_match_string(). Calculates the size of @a automatically.
 202 */
 203#define sysfs_match_string(_a, _s) __sysfs_match_string(_a, ARRAY_SIZE(_a), _s)
 204
 205#ifdef CONFIG_BINARY_PRINTF
 206int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
 207int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);
 208int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
 209#endif
 210
 211extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
 212                                       const void *from, size_t available);
 213
 214int ptr_to_hashval(const void *ptr, unsigned long *hashval_out);
 215
 216/**
 217 * strstarts - does @str start with @prefix?
 218 * @str: string to examine
 219 * @prefix: prefix to look for.
 220 */
 221static inline bool strstarts(const char *str, const char *prefix)
 222{
 223        return strncmp(str, prefix, strlen(prefix)) == 0;
 224}
 225
 226size_t memweight(const void *ptr, size_t bytes);
 227
 228/**
 229 * memzero_explicit - Fill a region of memory (e.g. sensitive
 230 *                    keying data) with 0s.
 231 * @s: Pointer to the start of the area.
 232 * @count: The size of the area.
 233 *
 234 * Note: usually using memset() is just fine (!), but in cases
 235 * where clearing out _local_ data at the end of a scope is
 236 * necessary, memzero_explicit() should be used instead in
 237 * order to prevent the compiler from optimising away zeroing.
 238 *
 239 * memzero_explicit() doesn't need an arch-specific version as
 240 * it just invokes the one of memset() implicitly.
 241 */
 242static inline void memzero_explicit(void *s, size_t count)
 243{
 244        memset(s, 0, count);
 245        barrier_data(s);
 246}
 247
 248/**
 249 * kbasename - return the last part of a pathname.
 250 *
 251 * @path: path to extract the filename from.
 252 */
 253static inline const char *kbasename(const char *path)
 254{
 255        const char *tail = strrchr(path, '/');
 256        return tail ? tail + 1 : path;
 257}
 258
 259#define __FORTIFY_INLINE extern __always_inline __attribute__((gnu_inline))
 260#define __RENAME(x) __asm__(#x)
 261
 262void fortify_panic(const char *name) __noreturn __cold;
 263void __read_overflow(void) __compiletime_error("detected read beyond size of object passed as 1st parameter");
 264void __read_overflow2(void) __compiletime_error("detected read beyond size of object passed as 2nd parameter");
 265void __read_overflow3(void) __compiletime_error("detected read beyond size of object passed as 3rd parameter");
 266void __write_overflow(void) __compiletime_error("detected write beyond size of object passed as 1st parameter");
 267
 268#if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE)
 269
 270#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 271extern void *__underlying_memchr(const void *p, int c, __kernel_size_t size) __RENAME(memchr);
 272extern int __underlying_memcmp(const void *p, const void *q, __kernel_size_t size) __RENAME(memcmp);
 273extern void *__underlying_memcpy(void *p, const void *q, __kernel_size_t size) __RENAME(memcpy);
 274extern void *__underlying_memmove(void *p, const void *q, __kernel_size_t size) __RENAME(memmove);
 275extern void *__underlying_memset(void *p, int c, __kernel_size_t size) __RENAME(memset);
 276extern char *__underlying_strcat(char *p, const char *q) __RENAME(strcat);
 277extern char *__underlying_strcpy(char *p, const char *q) __RENAME(strcpy);
 278extern __kernel_size_t __underlying_strlen(const char *p) __RENAME(strlen);
 279extern char *__underlying_strncat(char *p, const char *q, __kernel_size_t count) __RENAME(strncat);
 280extern char *__underlying_strncpy(char *p, const char *q, __kernel_size_t size) __RENAME(strncpy);
 281#else
 282#define __underlying_memchr     __builtin_memchr
 283#define __underlying_memcmp     __builtin_memcmp
 284#define __underlying_memcpy     __builtin_memcpy
 285#define __underlying_memmove    __builtin_memmove
 286#define __underlying_memset     __builtin_memset
 287#define __underlying_strcat     __builtin_strcat
 288#define __underlying_strcpy     __builtin_strcpy
 289#define __underlying_strlen     __builtin_strlen
 290#define __underlying_strncat    __builtin_strncat
 291#define __underlying_strncpy    __builtin_strncpy
 292#endif
 293
 294__FORTIFY_INLINE char *strncpy(char *p, const char *q, __kernel_size_t size)
 295{
 296        size_t p_size = __builtin_object_size(p, 1);
 297        if (__builtin_constant_p(size) && p_size < size)
 298                __write_overflow();
 299        if (p_size < size)
 300                fortify_panic(__func__);
 301        return __underlying_strncpy(p, q, size);
 302}
 303
 304__FORTIFY_INLINE char *strcat(char *p, const char *q)
 305{
 306        size_t p_size = __builtin_object_size(p, 1);
 307        if (p_size == (size_t)-1)
 308                return __underlying_strcat(p, q);
 309        if (strlcat(p, q, p_size) >= p_size)
 310                fortify_panic(__func__);
 311        return p;
 312}
 313
 314__FORTIFY_INLINE __kernel_size_t strlen(const char *p)
 315{
 316        __kernel_size_t ret;
 317        size_t p_size = __builtin_object_size(p, 1);
 318
 319        /* Work around gcc excess stack consumption issue */
 320        if (p_size == (size_t)-1 ||
 321            (__builtin_constant_p(p[p_size - 1]) && p[p_size - 1] == '\0'))
 322                return __underlying_strlen(p);
 323        ret = strnlen(p, p_size);
 324        if (p_size <= ret)
 325                fortify_panic(__func__);
 326        return ret;
 327}
 328
 329extern __kernel_size_t __real_strnlen(const char *, __kernel_size_t) __RENAME(strnlen);
 330__FORTIFY_INLINE __kernel_size_t strnlen(const char *p, __kernel_size_t maxlen)
 331{
 332        size_t p_size = __builtin_object_size(p, 1);
 333        __kernel_size_t ret = __real_strnlen(p, maxlen < p_size ? maxlen : p_size);
 334        if (p_size <= ret && maxlen != ret)
 335                fortify_panic(__func__);
 336        return ret;
 337}
 338
 339/* defined after fortified strlen to reuse it */
 340extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
 341__FORTIFY_INLINE size_t strlcpy(char *p, const char *q, size_t size)
 342{
 343        size_t ret;
 344        size_t p_size = __builtin_object_size(p, 1);
 345        size_t q_size = __builtin_object_size(q, 1);
 346        if (p_size == (size_t)-1 && q_size == (size_t)-1)
 347                return __real_strlcpy(p, q, size);
 348        ret = strlen(q);
 349        if (size) {
 350                size_t len = (ret >= size) ? size - 1 : ret;
 351                if (__builtin_constant_p(len) && len >= p_size)
 352                        __write_overflow();
 353                if (len >= p_size)
 354                        fortify_panic(__func__);
 355                __underlying_memcpy(p, q, len);
 356                p[len] = '\0';
 357        }
 358        return ret;
 359}
 360
 361/* defined after fortified strnlen to reuse it */
 362extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);
 363__FORTIFY_INLINE ssize_t strscpy(char *p, const char *q, size_t size)
 364{
 365        size_t len;
 366        /* Use string size rather than possible enclosing struct size. */
 367        size_t p_size = __builtin_object_size(p, 1);
 368        size_t q_size = __builtin_object_size(q, 1);
 369
 370        /* If we cannot get size of p and q default to call strscpy. */
 371        if (p_size == (size_t) -1 && q_size == (size_t) -1)
 372                return __real_strscpy(p, q, size);
 373
 374        /*
 375         * If size can be known at compile time and is greater than
 376         * p_size, generate a compile time write overflow error.
 377         */
 378        if (__builtin_constant_p(size) && size > p_size)
 379                __write_overflow();
 380
 381        /*
 382         * This call protects from read overflow, because len will default to q
 383         * length if it smaller than size.
 384         */
 385        len = strnlen(q, size);
 386        /*
 387         * If len equals size, we will copy only size bytes which leads to
 388         * -E2BIG being returned.
 389         * Otherwise we will copy len + 1 because of the final '\O'.
 390         */
 391        len = len == size ? size : len + 1;
 392
 393        /*
 394         * Generate a runtime write overflow error if len is greater than
 395         * p_size.
 396         */
 397        if (len > p_size)
 398                fortify_panic(__func__);
 399
 400        /*
 401         * We can now safely call vanilla strscpy because we are protected from:
 402         * 1. Read overflow thanks to call to strnlen().
 403         * 2. Write overflow thanks to above ifs.
 404         */
 405        return __real_strscpy(p, q, len);
 406}
 407
 408/* defined after fortified strlen and strnlen to reuse them */
 409__FORTIFY_INLINE char *strncat(char *p, const char *q, __kernel_size_t count)
 410{
 411        size_t p_len, copy_len;
 412        size_t p_size = __builtin_object_size(p, 1);
 413        size_t q_size = __builtin_object_size(q, 1);
 414        if (p_size == (size_t)-1 && q_size == (size_t)-1)
 415                return __underlying_strncat(p, q, count);
 416        p_len = strlen(p);
 417        copy_len = strnlen(q, count);
 418        if (p_size < p_len + copy_len + 1)
 419                fortify_panic(__func__);
 420        __underlying_memcpy(p + p_len, q, copy_len);
 421        p[p_len + copy_len] = '\0';
 422        return p;
 423}
 424
 425__FORTIFY_INLINE void *memset(void *p, int c, __kernel_size_t size)
 426{
 427        size_t p_size = __builtin_object_size(p, 0);
 428        if (__builtin_constant_p(size) && p_size < size)
 429                __write_overflow();
 430        if (p_size < size)
 431                fortify_panic(__func__);
 432        return __underlying_memset(p, c, size);
 433}
 434
 435__FORTIFY_INLINE void *memcpy(void *p, const void *q, __kernel_size_t size)
 436{
 437        size_t p_size = __builtin_object_size(p, 0);
 438        size_t q_size = __builtin_object_size(q, 0);
 439        if (__builtin_constant_p(size)) {
 440                if (p_size < size)
 441                        __write_overflow();
 442                if (q_size < size)
 443                        __read_overflow2();
 444        }
 445        if (p_size < size || q_size < size)
 446                fortify_panic(__func__);
 447        return __underlying_memcpy(p, q, size);
 448}
 449
 450__FORTIFY_INLINE void *memmove(void *p, const void *q, __kernel_size_t size)
 451{
 452        size_t p_size = __builtin_object_size(p, 0);
 453        size_t q_size = __builtin_object_size(q, 0);
 454        if (__builtin_constant_p(size)) {
 455                if (p_size < size)
 456                        __write_overflow();
 457                if (q_size < size)
 458                        __read_overflow2();
 459        }
 460        if (p_size < size || q_size < size)
 461                fortify_panic(__func__);
 462        return __underlying_memmove(p, q, size);
 463}
 464
 465extern void *__real_memscan(void *, int, __kernel_size_t) __RENAME(memscan);
 466__FORTIFY_INLINE void *memscan(void *p, int c, __kernel_size_t size)
 467{
 468        size_t p_size = __builtin_object_size(p, 0);
 469        if (__builtin_constant_p(size) && p_size < size)
 470                __read_overflow();
 471        if (p_size < size)
 472                fortify_panic(__func__);
 473        return __real_memscan(p, c, size);
 474}
 475
 476__FORTIFY_INLINE int memcmp(const void *p, const void *q, __kernel_size_t size)
 477{
 478        size_t p_size = __builtin_object_size(p, 0);
 479        size_t q_size = __builtin_object_size(q, 0);
 480        if (__builtin_constant_p(size)) {
 481                if (p_size < size)
 482                        __read_overflow();
 483                if (q_size < size)
 484                        __read_overflow2();
 485        }
 486        if (p_size < size || q_size < size)
 487                fortify_panic(__func__);
 488        return __underlying_memcmp(p, q, size);
 489}
 490
 491__FORTIFY_INLINE void *memchr(const void *p, int c, __kernel_size_t size)
 492{
 493        size_t p_size = __builtin_object_size(p, 0);
 494        if (__builtin_constant_p(size) && p_size < size)
 495                __read_overflow();
 496        if (p_size < size)
 497                fortify_panic(__func__);
 498        return __underlying_memchr(p, c, size);
 499}
 500
 501void *__real_memchr_inv(const void *s, int c, size_t n) __RENAME(memchr_inv);
 502__FORTIFY_INLINE void *memchr_inv(const void *p, int c, size_t size)
 503{
 504        size_t p_size = __builtin_object_size(p, 0);
 505        if (__builtin_constant_p(size) && p_size < size)
 506                __read_overflow();
 507        if (p_size < size)
 508                fortify_panic(__func__);
 509        return __real_memchr_inv(p, c, size);
 510}
 511
 512extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup);
 513__FORTIFY_INLINE void *kmemdup(const void *p, size_t size, gfp_t gfp)
 514{
 515        size_t p_size = __builtin_object_size(p, 0);
 516        if (__builtin_constant_p(size) && p_size < size)
 517                __read_overflow();
 518        if (p_size < size)
 519                fortify_panic(__func__);
 520        return __real_kmemdup(p, size, gfp);
 521}
 522
 523/* defined after fortified strlen and memcpy to reuse them */
 524__FORTIFY_INLINE char *strcpy(char *p, const char *q)
 525{
 526        size_t p_size = __builtin_object_size(p, 1);
 527        size_t q_size = __builtin_object_size(q, 1);
 528        size_t size;
 529        if (p_size == (size_t)-1 && q_size == (size_t)-1)
 530                return __underlying_strcpy(p, q);
 531        size = strlen(q) + 1;
 532        /* test here to use the more stringent object size */
 533        if (p_size < size)
 534                fortify_panic(__func__);
 535        memcpy(p, q, size);
 536        return p;
 537}
 538
 539/* Don't use these outside the FORITFY_SOURCE implementation */
 540#undef __underlying_memchr
 541#undef __underlying_memcmp
 542#undef __underlying_memcpy
 543#undef __underlying_memmove
 544#undef __underlying_memset
 545#undef __underlying_strcat
 546#undef __underlying_strcpy
 547#undef __underlying_strlen
 548#undef __underlying_strncat
 549#undef __underlying_strncpy
 550#endif
 551
 552/**
 553 * memcpy_and_pad - Copy one buffer to another with padding
 554 * @dest: Where to copy to
 555 * @dest_len: The destination buffer size
 556 * @src: Where to copy from
 557 * @count: The number of bytes to copy
 558 * @pad: Character to use for padding if space is left in destination.
 559 */
 560static inline void memcpy_and_pad(void *dest, size_t dest_len,
 561                                  const void *src, size_t count, int pad)
 562{
 563        if (dest_len > count) {
 564                memcpy(dest, src, count);
 565                memset(dest + count, pad,  dest_len - count);
 566        } else
 567                memcpy(dest, src, dest_len);
 568}
 569
 570/**
 571 * str_has_prefix - Test if a string has a given prefix
 572 * @str: The string to test
 573 * @prefix: The string to see if @str starts with
 574 *
 575 * A common way to test a prefix of a string is to do:
 576 *  strncmp(str, prefix, sizeof(prefix) - 1)
 577 *
 578 * But this can lead to bugs due to typos, or if prefix is a pointer
 579 * and not a constant. Instead use str_has_prefix().
 580 *
 581 * Returns:
 582 * * strlen(@prefix) if @str starts with @prefix
 583 * * 0 if @str does not start with @prefix
 584 */
 585static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
 586{
 587        size_t len = strlen(prefix);
 588        return strncmp(str, prefix, len) == 0 ? len : 0;
 589}
 590
 591#endif /* _LINUX_STRING_H_ */
 592