siphash.h

  1/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-3-Clause) */
  2/* Copyright (C) 2016-2022 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
  3 *
  4 * SipHash: a fast short-input PRF
  5 * https://131002.net/siphash/
  6 *
  7 * This implementation is specifically for SipHash2-4 for a secure PRF
  8 * and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
  9 * hashtables.
 10 */
 11
 12#ifndef _LINUX_SIPHASH_H
 13#define _LINUX_SIPHASH_H
 14
 15#include <linux/types.h>
 16#include <linux/kernel.h>
 17
 18#define SIPHASH_ALIGNMENT __alignof__(u64)
 19typedef struct {
 20	u64 key[2];
 21} siphash_key_t;
 22
 23#define siphash_aligned_key_t siphash_key_t __aligned(16)
 24
 25static inline bool siphash_key_is_zero(const siphash_key_t *key)
 26{
 27	return !(key->key[0] | key->key[1]);
 28}
 29
 30u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key);
 31u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key);
 32
 33u64 siphash_1u64(const u64 a, const siphash_key_t *key);
 34u64 siphash_2u64(const u64 a, const u64 b, const siphash_key_t *key);
 35u64 siphash_3u64(const u64 a, const u64 b, const u64 c,
 36		 const siphash_key_t *key);
 37u64 siphash_4u64(const u64 a, const u64 b, const u64 c, const u64 d,
 38		 const siphash_key_t *key);
 39u64 siphash_1u32(const u32 a, const siphash_key_t *key);
 40u64 siphash_3u32(const u32 a, const u32 b, const u32 c,
 41		 const siphash_key_t *key);
 42
 43static inline u64 siphash_2u32(const u32 a, const u32 b,
 44			       const siphash_key_t *key)
 45{
 46	return siphash_1u64((u64)b << 32 | a, key);
 47}
 48static inline u64 siphash_4u32(const u32 a, const u32 b, const u32 c,
 49			       const u32 d, const siphash_key_t *key)
 50{
 51	return siphash_2u64((u64)b << 32 | a, (u64)d << 32 | c, key);
 52}
 53
 54
 55static inline u64 ___siphash_aligned(const __le64 *data, size_t len,
 56				     const siphash_key_t *key)
 57{
 58	if (__builtin_constant_p(len) && len == 4)
 59		return siphash_1u32(le32_to_cpup((const __le32 *)data), key);
 60	if (__builtin_constant_p(len) && len == 8)
 61		return siphash_1u64(le64_to_cpu(data[0]), key);
 62	if (__builtin_constant_p(len) && len == 16)
 63		return siphash_2u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
 64				    key);
 65	if (__builtin_constant_p(len) && len == 24)
 66		return siphash_3u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
 67				    le64_to_cpu(data[2]), key);
 68	if (__builtin_constant_p(len) && len == 32)
 69		return siphash_4u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
 70				    le64_to_cpu(data[2]), le64_to_cpu(data[3]),
 71				    key);
 72	return __siphash_aligned(data, len, key);
 73}
 74
 75/**
 76 * siphash - compute 64-bit siphash PRF value
 77 * @data: buffer to hash
 78 * @size: size of @data
 79 * @key: the siphash key
 80 */
 81static inline u64 siphash(const void *data, size_t len,
 82			  const siphash_key_t *key)
 83{
 84	if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
 85	    !IS_ALIGNED((unsigned long)data, SIPHASH_ALIGNMENT))
 86		return __siphash_unaligned(data, len, key);
 87	return ___siphash_aligned(data, len, key);
 88}
 89
 90#define HSIPHASH_ALIGNMENT __alignof__(unsigned long)
 91typedef struct {
 92	unsigned long key[2];
 93} hsiphash_key_t;
 94
 95u32 __hsiphash_aligned(const void *data, size_t len,
 96		       const hsiphash_key_t *key);
 97u32 __hsiphash_unaligned(const void *data, size_t len,
 98			 const hsiphash_key_t *key);
 99
100u32 hsiphash_1u32(const u32 a, const hsiphash_key_t *key);
101u32 hsiphash_2u32(const u32 a, const u32 b, const hsiphash_key_t *key);
102u32 hsiphash_3u32(const u32 a, const u32 b, const u32 c,
103		  const hsiphash_key_t *key);
104u32 hsiphash_4u32(const u32 a, const u32 b, const u32 c, const u32 d,
105		  const hsiphash_key_t *key);
106
107static inline u32 ___hsiphash_aligned(const __le32 *data, size_t len,
108				      const hsiphash_key_t *key)
109{
110	if (__builtin_constant_p(len) && len == 4)
111		return hsiphash_1u32(le32_to_cpu(data[0]), key);
112	if (__builtin_constant_p(len) && len == 8)
113		return hsiphash_2u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
114				     key);
115	if (__builtin_constant_p(len) && len == 12)
116		return hsiphash_3u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
117				     le32_to_cpu(data[2]), key);
118	if (__builtin_constant_p(len) && len == 16)
119		return hsiphash_4u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
120				     le32_to_cpu(data[2]), le32_to_cpu(data[3]),
121				     key);
122	return __hsiphash_aligned(data, len, key);
123}
124
125/**
126 * hsiphash - compute 32-bit hsiphash PRF value
127 * @data: buffer to hash
128 * @size: size of @data
129 * @key: the hsiphash key
130 */
131static inline u32 hsiphash(const void *data, size_t len,
132			   const hsiphash_key_t *key)
133{
134	if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
135	    !IS_ALIGNED((unsigned long)data, HSIPHASH_ALIGNMENT))
136		return __hsiphash_unaligned(data, len, key);
137	return ___hsiphash_aligned(data, len, key);
138}
139
140/*
141 * These macros expose the raw SipHash and HalfSipHash permutations.
142 * Do not use them directly! If you think you have a use for them,
143 * be sure to CC the maintainer of this file explaining why.
144 */
145
146#define SIPHASH_PERMUTATION(a, b, c, d) ( \
147	(a) += (b), (b) = rol64((b), 13), (b) ^= (a), (a) = rol64((a), 32), \
148	(c) += (d), (d) = rol64((d), 16), (d) ^= (c), \
149	(a) += (d), (d) = rol64((d), 21), (d) ^= (a), \
150	(c) += (b), (b) = rol64((b), 17), (b) ^= (c), (c) = rol64((c), 32))
151
152#define SIPHASH_CONST_0 0x736f6d6570736575ULL
153#define SIPHASH_CONST_1 0x646f72616e646f6dULL
154#define SIPHASH_CONST_2 0x6c7967656e657261ULL
155#define SIPHASH_CONST_3 0x7465646279746573ULL
156
157#define HSIPHASH_PERMUTATION(a, b, c, d) ( \
158	(a) += (b), (b) = rol32((b), 5), (b) ^= (a), (a) = rol32((a), 16), \
159	(c) += (d), (d) = rol32((d), 8), (d) ^= (c), \
160	(a) += (d), (d) = rol32((d), 7), (d) ^= (a), \
161	(c) += (b), (b) = rol32((b), 13), (b) ^= (c), (c) = rol32((c), 16))
162
163#define HSIPHASH_CONST_0 0U
164#define HSIPHASH_CONST_1 0U
165#define HSIPHASH_CONST_2 0x6c796765U
166#define HSIPHASH_CONST_3 0x74656462U
167
168#endif /* _LINUX_SIPHASH_H */