include/linux/siphash.h

0001 /* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
0002 /* Copyright (C) 2016-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
0003  *
0004  * SipHash: a fast short-input PRF
0005  * https://131002.net/siphash/
0006  *
0007  * This implementation is specifically for SipHash2-4 for a secure PRF
0008  * and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
0009  * hashtables.
0010  */
0011
0012 #ifndef _LINUX_SIPHASH_H
0013 #define _LINUX_SIPHASH_H
0014
0015 #include <linux/types.h>
0016 #include <linux/kernel.h>
0017
0018 #define SIPHASH_ALIGNMENT __alignof__(u64)
0019 typedef struct {
0020     u64 key[2];
0021 } siphash_key_t;
0022
0023 #define siphash_aligned_key_t siphash_key_t __aligned(16)
0024
0025 static inline bool siphash_key_is_zero(const siphash_key_t *key)
0026 {
0027     return !(key->key[0] | key->key[1]);
0028 }
0029
0030 u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key);
0031 u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key);
0032
0033 u64 siphash_1u64(const u64 a, const siphash_key_t *key);
0034 u64 siphash_2u64(const u64 a, const u64 b, const siphash_key_t *key);
0035 u64 siphash_3u64(const u64 a, const u64 b, const u64 c,
0036          const siphash_key_t *key);
0037 u64 siphash_4u64(const u64 a, const u64 b, const u64 c, const u64 d,
0038          const siphash_key_t *key);
0039 u64 siphash_1u32(const u32 a, const siphash_key_t *key);
0040 u64 siphash_3u32(const u32 a, const u32 b, const u32 c,
0041          const siphash_key_t *key);
0042
0043 static inline u64 siphash_2u32(const u32 a, const u32 b,
0044                    const siphash_key_t *key)
0045 {
0046     return siphash_1u64((u64)b << 32 | a, key);
0047 }
0048 static inline u64 siphash_4u32(const u32 a, const u32 b, const u32 c,
0049                    const u32 d, const siphash_key_t *key)
0050 {
0051     return siphash_2u64((u64)b << 32 | a, (u64)d << 32 | c, key);
0052 }
0053
0054
0055 static inline u64 ___siphash_aligned(const __le64 *data, size_t len,
0056                      const siphash_key_t *key)
0057 {
0058     if (__builtin_constant_p(len) && len == 4)
0059         return siphash_1u32(le32_to_cpup((const __le32 *)data), key);
0060     if (__builtin_constant_p(len) && len == 8)
0061         return siphash_1u64(le64_to_cpu(data[0]), key);
0062     if (__builtin_constant_p(len) && len == 16)
0063         return siphash_2u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
0064                     key);
0065     if (__builtin_constant_p(len) && len == 24)
0066         return siphash_3u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
0067                     le64_to_cpu(data[2]), key);
0068     if (__builtin_constant_p(len) && len == 32)
0069         return siphash_4u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
0070                     le64_to_cpu(data[2]), le64_to_cpu(data[3]),
0071                     key);
0072     return __siphash_aligned(data, len, key);
0073 }
0074
0075 /**
0076  * siphash - compute 64-bit siphash PRF value
0077  * @data: buffer to hash
0078  * @size: size of @data
0079  * @key: the siphash key
0080  */
0081 static inline u64 siphash(const void *data, size_t len,
0082               const siphash_key_t *key)
0083 {
0084     if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
0085         !IS_ALIGNED((unsigned long)data, SIPHASH_ALIGNMENT))
0086         return __siphash_unaligned(data, len, key);
0087     return ___siphash_aligned(data, len, key);
0088 }
0089
0090 #define HSIPHASH_ALIGNMENT __alignof__(unsigned long)
0091 typedef struct {
0092     unsigned long key[2];
0093 } hsiphash_key_t;
0094
0095 u32 __hsiphash_aligned(const void *data, size_t len,
0096                const hsiphash_key_t *key);
0097 u32 __hsiphash_unaligned(const void *data, size_t len,
0098              const hsiphash_key_t *key);
0099
0100 u32 hsiphash_1u32(const u32 a, const hsiphash_key_t *key);
0101 u32 hsiphash_2u32(const u32 a, const u32 b, const hsiphash_key_t *key);
0102 u32 hsiphash_3u32(const u32 a, const u32 b, const u32 c,
0103           const hsiphash_key_t *key);
0104 u32 hsiphash_4u32(const u32 a, const u32 b, const u32 c, const u32 d,
0105           const hsiphash_key_t *key);
0106
0107 static inline u32 ___hsiphash_aligned(const __le32 *data, size_t len,
0108                       const hsiphash_key_t *key)
0109 {
0110     if (__builtin_constant_p(len) && len == 4)
0111         return hsiphash_1u32(le32_to_cpu(data[0]), key);
0112     if (__builtin_constant_p(len) && len == 8)
0113         return hsiphash_2u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
0114                      key);
0115     if (__builtin_constant_p(len) && len == 12)
0116         return hsiphash_3u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
0117                      le32_to_cpu(data[2]), key);
0118     if (__builtin_constant_p(len) && len == 16)
0119         return hsiphash_4u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
0120                      le32_to_cpu(data[2]), le32_to_cpu(data[3]),
0121                      key);
0122     return __hsiphash_aligned(data, len, key);
0123 }
0124
0125 /**
0126  * hsiphash - compute 32-bit hsiphash PRF value
0127  * @data: buffer to hash
0128  * @size: size of @data
0129  * @key: the hsiphash key
0130  */
0131 static inline u32 hsiphash(const void *data, size_t len,
0132                const hsiphash_key_t *key)
0133 {
0134     if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
0135         !IS_ALIGNED((unsigned long)data, HSIPHASH_ALIGNMENT))
0136         return __hsiphash_unaligned(data, len, key);
0137     return ___hsiphash_aligned(data, len, key);
0138 }
0139
0140 /*
0141  * These macros expose the raw SipHash and HalfSipHash permutations.
0142  * Do not use them directly! If you think you have a use for them,
0143  * be sure to CC the maintainer of this file explaining why.
0144  */
0145
0146 #define SIPHASH_PERMUTATION(a, b, c, d) ( \
0147     (a) += (b), (b) = rol64((b), 13), (b) ^= (a), (a) = rol64((a), 32), \
0148     (c) += (d), (d) = rol64((d), 16), (d) ^= (c), \
0149     (a) += (d), (d) = rol64((d), 21), (d) ^= (a), \
0150     (c) += (b), (b) = rol64((b), 17), (b) ^= (c), (c) = rol64((c), 32))
0151
0152 #define SIPHASH_CONST_0 0x736f6d6570736575ULL
0153 #define SIPHASH_CONST_1 0x646f72616e646f6dULL
0154 #define SIPHASH_CONST_2 0x6c7967656e657261ULL
0155 #define SIPHASH_CONST_3 0x7465646279746573ULL
0156
0157 #define HSIPHASH_PERMUTATION(a, b, c, d) ( \
0158     (a) += (b), (b) = rol32((b), 5), (b) ^= (a), (a) = rol32((a), 16), \
0159     (c) += (d), (d) = rol32((d), 8), (d) ^= (c), \
0160     (a) += (d), (d) = rol32((d), 7), (d) ^= (a), \
0161     (c) += (b), (b) = rol32((b), 13), (b) ^= (c), (c) = rol32((c), 16))
0162
0163 #define HSIPHASH_CONST_0 0U
0164 #define HSIPHASH_CONST_1 0U
0165 #define HSIPHASH_CONST_2 0x6c796765U
0166 #define HSIPHASH_CONST_3 0x74656462U
0167
0168 #endif /* _LINUX_SIPHASH_H */