diff options
Diffstat (limited to 'lib/string.c')
| -rw-r--r-- | lib/string.c | 507 |
1 files changed, 201 insertions, 306 deletions
diff --git a/lib/string.c b/lib/string.c index ebbb99c775bd..b632c71df1a5 100644 --- a/lib/string.c +++ b/lib/string.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0 /* * linux/lib/string.c * @@ -5,31 +6,29 @@ */ /* - * stupid library routines.. The optimized versions should generally be found - * as inline code in <asm-xx/string.h> + * This file should be used only for "library" routines that may have + * alternative implementations on specific architectures (generally + * found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE. + * (Specifically, this file is built with __NO_FORTIFY.) * - * These are buggy as well.. - * - * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de> - * - Added strsep() which will replace strtok() soon (because strsep() is - * reentrant and should be faster). Use only strsep() in new code, please. - * - * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>, - * Matthew Hawkins <matt@mh.dropbear.id.au> - * - Kissed strtok() goodbye + * Other helper functions should live in string_helpers.c. */ -#include <linux/types.h> -#include <linux/string.h> -#include <linux/ctype.h> -#include <linux/kernel.h> -#include <linux/export.h> +#define __NO_FORTIFY +#include <linux/bits.h> #include <linux/bug.h> +#include <linux/ctype.h> #include <linux/errno.h> +#include <linux/limits.h> +#include <linux/linkage.h> +#include <linux/stddef.h> +#include <linux/string.h> +#include <linux/types.h> -#include <asm/byteorder.h> -#include <asm/word-at-a-time.h> #include <asm/page.h> +#include <asm/rwonce.h> +#include <linux/unaligned.h> +#include <asm/word-at-a-time.h> #ifndef __HAVE_ARCH_STRNCASECMP /** @@ -78,12 +77,6 @@ EXPORT_SYMBOL(strcasecmp); #endif #ifndef __HAVE_ARCH_STRCPY -/** - * strcpy - Copy a %NUL terminated string - * @dest: Where to copy the string to - * @src: Where to copy the string from - */ -#undef strcpy char *strcpy(char *dest, const char *src) { char *tmp = dest; @@ -96,19 +89,6 @@ EXPORT_SYMBOL(strcpy); #endif #ifndef __HAVE_ARCH_STRNCPY -/** - * strncpy - Copy a length-limited, C-string - * @dest: Where to copy the string to - * @src: Where to copy the string from - * @count: The maximum number of bytes to copy - * - * The result is not %NUL-terminated if the source exceeds - * @count bytes. - * - * In the case where the length of @src is less than that of - * count, the remainder of @dest will be padded with %NUL. - * - */ char *strncpy(char *dest, const char *src, size_t count) { char *tmp = dest; @@ -124,65 +104,22 @@ char *strncpy(char *dest, const char *src, size_t count) EXPORT_SYMBOL(strncpy); #endif -#ifndef __HAVE_ARCH_STRLCPY -/** - * strlcpy - Copy a C-string into a sized buffer - * @dest: Where to copy the string to - * @src: Where to copy the string from - * @size: size of destination buffer - * - * Compatible with ``*BSD``: the result is always a valid - * NUL-terminated string that fits in the buffer (unless, - * of course, the buffer size is zero). It does not pad - * out the result like strncpy() does. - */ -size_t strlcpy(char *dest, const char *src, size_t size) -{ - size_t ret = strlen(src); - - if (size) { - size_t len = (ret >= size) ? size - 1 : ret; - memcpy(dest, src, len); - dest[len] = '\0'; - } - return ret; -} -EXPORT_SYMBOL(strlcpy); +#ifdef __BIG_ENDIAN +# define ALLBUTLAST_BYTE_MASK (~255ul) +#else +# define ALLBUTLAST_BYTE_MASK (~0ul >> 8) #endif -#ifndef __HAVE_ARCH_STRSCPY -/** - * strscpy - Copy a C-string into a sized buffer - * @dest: Where to copy the string to - * @src: Where to copy the string from - * @count: Size of destination buffer - * - * Copy the string, or as much of it as fits, into the dest buffer. - * The routine returns the number of characters copied (not including - * the trailing NUL) or -E2BIG if the destination buffer wasn't big enough. - * The behavior is undefined if the string buffers overlap. - * The destination buffer is always NUL terminated, unless it's zero-sized. - * - * Preferred to strlcpy() since the API doesn't require reading memory - * from the src string beyond the specified "count" bytes, and since - * the return value is easier to error-check than strlcpy()'s. - * In addition, the implementation is robust to the string changing out - * from underneath it, unlike the current strlcpy() implementation. - * - * Preferred to strncpy() since it always returns a valid string, and - * doesn't unnecessarily force the tail of the destination buffer to be - * zeroed. If the zeroing is desired, it's likely cleaner to use strscpy() - * with an overflow test, then just memset() the tail of the dest buffer. - */ -ssize_t strscpy(char *dest, const char *src, size_t count) +ssize_t sized_strscpy(char *dest, const char *src, size_t count) { const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; size_t max = count; long res = 0; - if (count == 0) + if (count == 0 || WARN_ON_ONCE(count > INT_MAX)) return -E2BIG; +#ifndef CONFIG_DCACHE_WORD_ACCESS #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS /* * If src is unaligned, don't cross a page boundary, @@ -198,24 +135,43 @@ ssize_t strscpy(char *dest, const char *src, size_t count) if (((long) dest | (long) src) & (sizeof(long) - 1)) max = 0; #endif +#endif + + /* + * load_unaligned_zeropad() or read_word_at_a_time() below may read + * uninitialized bytes after the trailing zero and use them in + * comparisons. Disable this optimization under KMSAN to prevent + * false positive reports. + */ + if (IS_ENABLED(CONFIG_KMSAN)) + max = 0; while (max >= sizeof(unsigned long)) { unsigned long c, data; - c = *(unsigned long *)(src+res); +#ifdef CONFIG_DCACHE_WORD_ACCESS + c = load_unaligned_zeropad(src+res); +#else + c = read_word_at_a_time(src+res); +#endif if (has_zero(c, &data, &constants)) { data = prep_zero_mask(c, data, &constants); data = create_zero_mask(data); *(unsigned long *)(dest+res) = c & zero_bytemask(data); return res + find_zero(data); } + count -= sizeof(unsigned long); + if (unlikely(!count)) { + c &= ALLBUTLAST_BYTE_MASK; + *(unsigned long *)(dest+res) = c; + return -E2BIG; + } *(unsigned long *)(dest+res) = c; res += sizeof(unsigned long); - count -= sizeof(unsigned long); max -= sizeof(unsigned long); } - while (count) { + while (count > 1) { char c; c = src[res]; @@ -226,22 +182,39 @@ ssize_t strscpy(char *dest, const char *src, size_t count) count--; } - /* Hit buffer length without finding a NUL; force NUL-termination. */ - if (res) - dest[res-1] = '\0'; + /* Force NUL-termination. */ + dest[res] = '\0'; - return -E2BIG; + /* Return E2BIG if the source didn't stop */ + return src[res] ? -E2BIG : res; } -EXPORT_SYMBOL(strscpy); -#endif +EXPORT_SYMBOL(sized_strscpy); -#ifndef __HAVE_ARCH_STRCAT /** - * strcat - Append one %NUL-terminated string to another - * @dest: The string to be appended to - * @src: The string to append to it + * stpcpy - copy a string from src to dest returning a pointer to the new end + * of dest, including src's %NUL-terminator. May overrun dest. + * @dest: pointer to end of string being copied into. Must be large enough + * to receive copy. + * @src: pointer to the beginning of string being copied from. Must not overlap + * dest. + * + * stpcpy differs from strcpy in a key way: the return value is a pointer + * to the new %NUL-terminating character in @dest. (For strcpy, the return + * value is a pointer to the start of @dest). This interface is considered + * unsafe as it doesn't perform bounds checking of the inputs. As such it's + * not recommended for usage. Instead, its definition is provided in case + * the compiler lowers other libcalls to stpcpy. */ -#undef strcat +char *stpcpy(char *__restrict__ dest, const char *__restrict__ src); +char *stpcpy(char *__restrict__ dest, const char *__restrict__ src) +{ + while ((*dest++ = *src++) != '\0') + /* nothing */; + return --dest; +} +EXPORT_SYMBOL(stpcpy); + +#ifndef __HAVE_ARCH_STRCAT char *strcat(char *dest, const char *src) { char *tmp = dest; @@ -256,15 +229,6 @@ EXPORT_SYMBOL(strcat); #endif #ifndef __HAVE_ARCH_STRNCAT -/** - * strncat - Append a length-limited, C-string to another - * @dest: The string to be appended to - * @src: The string to append to it - * @count: The maximum numbers of bytes to copy - * - * Note that in contrast to strncpy(), strncat() ensures the result is - * terminated. - */ char *strncat(char *dest, const char *src, size_t count) { char *tmp = dest; @@ -285,12 +249,6 @@ EXPORT_SYMBOL(strncat); #endif #ifndef __HAVE_ARCH_STRLCAT -/** - * strlcat - Append a length-limited, C-string to another - * @dest: The string to be appended to - * @src: The string to append to it - * @count: The size of the destination buffer. - */ size_t strlcat(char *dest, const char *src, size_t count) { size_t dsize = strlen(dest); @@ -304,7 +262,7 @@ size_t strlcat(char *dest, const char *src, size_t count) count -= dsize; if (len >= count) len = count-1; - memcpy(dest, src, len); + __builtin_memcpy(dest, src, len); dest[len] = 0; return res; } @@ -317,7 +275,6 @@ EXPORT_SYMBOL(strlcat); * @cs: One string * @ct: Another string */ -#undef strcmp int strcmp(const char *cs, const char *ct) { unsigned char c1, c2; @@ -365,6 +322,9 @@ EXPORT_SYMBOL(strncmp); * strchr - Find the first occurrence of a character in a string * @s: The string to be searched * @c: The character to search for + * + * Note that the %NUL-terminator is considered part of the string, and can + * be searched for. */ char *strchr(const char *s, int c) { @@ -394,6 +354,23 @@ char *strchrnul(const char *s, int c) EXPORT_SYMBOL(strchrnul); #endif +/** + * strnchrnul - Find and return a character in a length limited string, + * or end of string + * @s: The string to be searched + * @count: The number of characters to be searched + * @c: The character to search for + * + * Returns pointer to the first occurrence of 'c' in s. If c is not found, + * then return a pointer to the last character of the string. + */ +char *strnchrnul(const char *s, size_t count, int c) +{ + while (count-- && *s && *s != (char)c) + s++; + return (char *)s; +} + #ifndef __HAVE_ARCH_STRRCHR /** * strrchr - Find the last occurrence of a character in a string @@ -418,62 +395,24 @@ EXPORT_SYMBOL(strrchr); * @s: The string to be searched * @count: The number of characters to be searched * @c: The character to search for + * + * Note that the %NUL-terminator is considered part of the string, and can + * be searched for. */ char *strnchr(const char *s, size_t count, int c) { - for (; count-- && *s != '\0'; ++s) + while (count--) { if (*s == (char)c) return (char *)s; + if (*s++ == '\0') + break; + } return NULL; } EXPORT_SYMBOL(strnchr); #endif -/** - * skip_spaces - Removes leading whitespace from @str. - * @str: The string to be stripped. - * - * Returns a pointer to the first non-whitespace character in @str. - */ -char *skip_spaces(const char *str) -{ - while (isspace(*str)) - ++str; - return (char *)str; -} -EXPORT_SYMBOL(skip_spaces); - -/** - * strim - Removes leading and trailing whitespace from @s. - * @s: The string to be stripped. - * - * Note that the first trailing whitespace is replaced with a %NUL-terminator - * in the given string @s. Returns a pointer to the first non-whitespace - * character in @s. - */ -char *strim(char *s) -{ - size_t size; - char *end; - - size = strlen(s); - if (!size) - return s; - - end = s + size - 1; - while (end >= s && isspace(*end)) - end--; - *(end + 1) = '\0'; - - return skip_spaces(s); -} -EXPORT_SYMBOL(strim); - #ifndef __HAVE_ARCH_STRLEN -/** - * strlen - Find the length of a string - * @s: The string to be sized - */ size_t strlen(const char *s) { const char *sc; @@ -486,11 +425,6 @@ EXPORT_SYMBOL(strlen); #endif #ifndef __HAVE_ARCH_STRNLEN -/** - * strnlen - Find the length of a length-limited string - * @s: The string to be sized - * @count: The maximum number of bytes to search - */ size_t strnlen(const char *s, size_t count) { const char *sc; @@ -511,21 +445,13 @@ EXPORT_SYMBOL(strnlen); size_t strspn(const char *s, const char *accept) { const char *p; - const char *a; - size_t count = 0; for (p = s; *p != '\0'; ++p) { - for (a = accept; *a != '\0'; ++a) { - if (*p == *a) - break; - } - if (*a == '\0') - return count; - ++count; + if (!strchr(accept, *p)) + break; } - return count; + return p - s; } - EXPORT_SYMBOL(strspn); #endif @@ -538,17 +464,12 @@ EXPORT_SYMBOL(strspn); size_t strcspn(const char *s, const char *reject) { const char *p; - const char *r; - size_t count = 0; for (p = s; *p != '\0'; ++p) { - for (r = reject; *r != '\0'; ++r) { - if (*p == *r) - return count; - } - ++count; + if (strchr(reject, *p)) + break; } - return count; + return p - s; } EXPORT_SYMBOL(strcspn); #endif @@ -561,13 +482,11 @@ EXPORT_SYMBOL(strcspn); */ char *strpbrk(const char *cs, const char *ct) { - const char *sc1, *sc2; + const char *sc; - for (sc1 = cs; *sc1 != '\0'; ++sc1) { - for (sc2 = ct; *sc2 != '\0'; ++sc2) { - if (*sc1 == *sc2) - return (char *)sc1; - } + for (sc = cs; *sc != '\0'; ++sc) { + if (strchr(ct, *sc)) + return (char *)sc; } return NULL; } @@ -603,125 +522,91 @@ char *strsep(char **s, const char *ct) EXPORT_SYMBOL(strsep); #endif +#ifndef __HAVE_ARCH_MEMSET /** - * sysfs_streq - return true if strings are equal, modulo trailing newline - * @s1: one string - * @s2: another string - * - * This routine returns true iff two strings are equal, treating both - * NUL and newline-then-NUL as equivalent string terminations. It's - * geared for use with sysfs input strings, which generally terminate - * with newlines but are compared against values without newlines. - */ -bool sysfs_streq(const char *s1, const char *s2) -{ - while (*s1 && *s1 == *s2) { - s1++; - s2++; - } - - if (*s1 == *s2) - return true; - if (!*s1 && *s2 == '\n' && !s2[1]) - return true; - if (*s1 == '\n' && !s1[1] && !*s2) - return true; - return false; -} -EXPORT_SYMBOL(sysfs_streq); - -/** - * match_string - matches given string in an array - * @array: array of strings - * @n: number of strings in the array or -1 for NULL terminated arrays - * @string: string to match with + * memset - Fill a region of memory with the given value + * @s: Pointer to the start of the area. + * @c: The byte to fill the area with + * @count: The size of the area. * - * Return: - * index of a @string in the @array if matches, or %-EINVAL otherwise. + * Do not use memset() to access IO space, use memset_io() instead. */ -int match_string(const char * const *array, size_t n, const char *string) +void *memset(void *s, int c, size_t count) { - int index; - const char *item; - - for (index = 0; index < n; index++) { - item = array[index]; - if (!item) - break; - if (!strcmp(item, string)) - return index; - } + char *xs = s; - return -EINVAL; + while (count--) + *xs++ = c; + return s; } -EXPORT_SYMBOL(match_string); +EXPORT_SYMBOL(memset); +#endif +#ifndef __HAVE_ARCH_MEMSET16 /** - * __sysfs_match_string - matches given string in an array - * @array: array of strings - * @n: number of strings in the array or -1 for NULL terminated arrays - * @str: string to match with + * memset16() - Fill a memory area with a uint16_t + * @s: Pointer to the start of the area. + * @v: The value to fill the area with + * @count: The number of values to store * - * Returns index of @str in the @array or -EINVAL, just like match_string(). - * Uses sysfs_streq instead of strcmp for matching. + * Differs from memset() in that it fills with a uint16_t instead + * of a byte. Remember that @count is the number of uint16_ts to + * store, not the number of bytes. */ -int __sysfs_match_string(const char * const *array, size_t n, const char *str) +void *memset16(uint16_t *s, uint16_t v, size_t count) { - const char *item; - int index; + uint16_t *xs = s; - for (index = 0; index < n; index++) { - item = array[index]; - if (!item) - break; - if (sysfs_streq(item, str)) - return index; - } - - return -EINVAL; + while (count--) + *xs++ = v; + return s; } -EXPORT_SYMBOL(__sysfs_match_string); +EXPORT_SYMBOL(memset16); +#endif -#ifndef __HAVE_ARCH_MEMSET +#ifndef __HAVE_ARCH_MEMSET32 /** - * memset - Fill a region of memory with the given value + * memset32() - Fill a memory area with a uint32_t * @s: Pointer to the start of the area. - * @c: The byte to fill the area with - * @count: The size of the area. + * @v: The value to fill the area with + * @count: The number of values to store * - * Do not use memset() to access IO space, use memset_io() instead. + * Differs from memset() in that it fills with a uint32_t instead + * of a byte. Remember that @count is the number of uint32_ts to + * store, not the number of bytes. */ -void *memset(void *s, int c, size_t count) +void *memset32(uint32_t *s, uint32_t v, size_t count) { - char *xs = s; + uint32_t *xs = s; while (count--) - *xs++ = c; + *xs++ = v; return s; } -EXPORT_SYMBOL(memset); +EXPORT_SYMBOL(memset32); #endif +#ifndef __HAVE_ARCH_MEMSET64 /** - * memzero_explicit - Fill a region of memory (e.g. sensitive - * keying data) with 0s. + * memset64() - Fill a memory area with a uint64_t * @s: Pointer to the start of the area. - * @count: The size of the area. - * - * Note: usually using memset() is just fine (!), but in cases - * where clearing out _local_ data at the end of a scope is - * necessary, memzero_explicit() should be used instead in - * order to prevent the compiler from optimising away zeroing. + * @v: The value to fill the area with + * @count: The number of values to store * - * memzero_explicit() doesn't need an arch-specific version as - * it just invokes the one of memset() implicitly. + * Differs from memset() in that it fills with a uint64_t instead + * of a byte. Remember that @count is the number of uint64_ts to + * store, not the number of bytes. */ -void memzero_explicit(void *s, size_t count) +void *memset64(uint64_t *s, uint64_t v, size_t count) { - memset(s, 0, count); - barrier_data(s); + uint64_t *xs = s; + + while (count--) + *xs++ = v; + return s; } -EXPORT_SYMBOL(memzero_explicit); +EXPORT_SYMBOL(memset64); +#endif #ifndef __HAVE_ARCH_MEMCPY /** @@ -790,6 +675,21 @@ __visible int memcmp(const void *cs, const void *ct, size_t count) const unsigned char *su1, *su2; int res = 0; +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS + if (count >= sizeof(unsigned long)) { + const unsigned long *u1 = cs; + const unsigned long *u2 = ct; + do { + if (get_unaligned(u1) != get_unaligned(u2)) + break; + u1++; + u2++; + count -= sizeof(unsigned long); + } while (count >= sizeof(unsigned long)); + cs = u1; + ct = u2; + } +#endif for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--) if ((res = *su1 - *su2) != 0) break; @@ -798,6 +698,25 @@ __visible int memcmp(const void *cs, const void *ct, size_t count) EXPORT_SYMBOL(memcmp); #endif +#ifndef __HAVE_ARCH_BCMP +/** + * bcmp - returns 0 if and only if the buffers have identical contents. + * @a: pointer to first buffer. + * @b: pointer to second buffer. + * @len: size of buffers. + * + * The sign or magnitude of a non-zero return value has no particular + * meaning, and architectures may implement their own more efficient bcmp(). So + * while this particular implementation is a simple (tail) call to memcmp, do + * not rely on anything but whether the return value is zero or non-zero. + */ +int bcmp(const void *a, const void *b, size_t len) +{ + return memcmp(a, b, len); +} +EXPORT_SYMBOL(bcmp); +#endif + #ifndef __HAVE_ARCH_MEMSCAN /** * memscan - Find a character in an area of memory. @@ -813,7 +732,7 @@ void *memscan(void *addr, int c, size_t size) unsigned char *p = addr; while (size) { - if (*p == c) + if (*p == (unsigned char)c) return (void *)p; p++; size--; @@ -961,27 +880,3 @@ void *memchr_inv(const void *start, int c, size_t bytes) return check_bytes8(start, value, bytes % 8); } EXPORT_SYMBOL(memchr_inv); - -/** - * strreplace - Replace all occurrences of character in string. - * @s: The string to operate on. - * @old: The character being replaced. - * @new: The character @old is replaced with. - * - * Returns pointer to the nul byte at the end of @s. - */ -char *strreplace(char *s, char old, char new) -{ - for (; *s; ++s) - if (*s == old) - *s = new; - return s; -} -EXPORT_SYMBOL(strreplace); - -void fortify_panic(const char *name) -{ - pr_emerg("detected buffer overflow in %s\n", name); - BUG(); -} -EXPORT_SYMBOL(fortify_panic); |