diff options
Diffstat (limited to 'lib/hexdump.c')
-rw-r--r-- | lib/hexdump.c | 63 |
1 files changed, 32 insertions, 31 deletions
diff --git a/lib/hexdump.c b/lib/hexdump.c index b1d55b669ae2..06833d404398 100644 --- a/lib/hexdump.c +++ b/lib/hexdump.c @@ -7,6 +7,7 @@ #include <linux/ctype.h> #include <linux/errno.h> #include <linux/kernel.h> +#include <linux/minmax.h> #include <linux/export.h> #include <asm/unaligned.h> @@ -21,15 +22,33 @@ EXPORT_SYMBOL(hex_asc_upper); * * hex_to_bin() converts one hex digit to its actual value or -1 in case of bad * input. + * + * This function is used to load cryptographic keys, so it is coded in such a + * way that there are no conditions or memory accesses that depend on data. + * + * Explanation of the logic: + * (ch - '9' - 1) is negative if ch <= '9' + * ('0' - 1 - ch) is negative if ch >= '0' + * we "and" these two values, so the result is negative if ch is in the range + * '0' ... '9' + * we are only interested in the sign, so we do a shift ">> 8"; note that right + * shift of a negative value is implementation-defined, so we cast the + * value to (unsigned) before the shift --- we have 0xffffff if ch is in + * the range '0' ... '9', 0 otherwise + * we "and" this value with (ch - '0' + 1) --- we have a value 1 ... 10 if ch is + * in the range '0' ... '9', 0 otherwise + * we add this value to -1 --- we have a value 0 ... 9 if ch is in the range '0' + * ... '9', -1 otherwise + * the next line is similar to the previous one, but we need to decode both + * uppercase and lowercase letters, so we use (ch & 0xdf), which converts + * lowercase to uppercase */ -int hex_to_bin(char ch) +int hex_to_bin(unsigned char ch) { - if ((ch >= '0') && (ch <= '9')) - return ch - '0'; - ch = tolower(ch); - if ((ch >= 'a') && (ch <= 'f')) - return ch - 'a' + 10; - return -1; + unsigned char cu = ch & 0xdf; + return -1 + + ((ch - '0' + 1) & (unsigned)((ch - '9' - 1) & ('0' - 1 - ch)) >> 8) + + ((cu - 'A' + 11) & (unsigned)((cu - 'F' - 1) & ('A' - 1 - cu)) >> 8); } EXPORT_SYMBOL(hex_to_bin); @@ -44,10 +63,13 @@ EXPORT_SYMBOL(hex_to_bin); int hex2bin(u8 *dst, const char *src, size_t count) { while (count--) { - int hi = hex_to_bin(*src++); - int lo = hex_to_bin(*src++); + int hi, lo; - if ((hi < 0) || (lo < 0)) + hi = hex_to_bin(*src++); + if (unlikely(hi < 0)) + return -EINVAL; + lo = hex_to_bin(*src++); + if (unlikely(lo < 0)) return -EINVAL; *dst++ = (hi << 4) | lo; @@ -270,25 +292,4 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type, } EXPORT_SYMBOL(print_hex_dump); -#if !defined(CONFIG_DYNAMIC_DEBUG) -/** - * print_hex_dump_bytes - shorthand form of print_hex_dump() with default params - * @prefix_str: string to prefix each line with; - * caller supplies trailing spaces for alignment if desired - * @prefix_type: controls whether prefix of an offset, address, or none - * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE) - * @buf: data blob to dump - * @len: number of bytes in the @buf - * - * Calls print_hex_dump(), with log level of KERN_DEBUG, - * rowsize of 16, groupsize of 1, and ASCII output included. - */ -void print_hex_dump_bytes(const char *prefix_str, int prefix_type, - const void *buf, size_t len) -{ - print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, 16, 1, - buf, len, true); -} -EXPORT_SYMBOL(print_hex_dump_bytes); -#endif /* !defined(CONFIG_DYNAMIC_DEBUG) */ #endif /* defined(CONFIG_PRINTK) */ |