1/* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
  2 *
  3 * This file is provided under a dual BSD/GPLv2 license.
  4 *
  5 * SipHash: a fast short-input PRF
  6 * https://131002.net/siphash/
  7 *
  8 * This implementation is specifically for SipHash2-4 for a secure PRF
  9 * and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
 10 * hashtables.
 11 */
 12
 13#ifndef _LINUX_SIPHASH_H
 14#define _LINUX_SIPHASH_H
 15
 16#include <linux/types.h>
 17#include <linux/kernel.h>
 18
 19#define SIPHASH_ALIGNMENT __alignof__(u64)
 20typedef struct {
 21	u64 key[2];
 22} siphash_key_t;
 23
 24static inline bool siphash_key_is_zero(const siphash_key_t *key)
 25{
 26	return !(key->key[0] | key->key[1]);
 27}
 28
 29u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key);
 30#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 31u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key);
 32#endif
 33
 34u64 siphash_1u64(const u64 a, const siphash_key_t *key);
 35u64 siphash_2u64(const u64 a, const u64 b, const siphash_key_t *key);
 36u64 siphash_3u64(const u64 a, const u64 b, const u64 c,
 37		 const siphash_key_t *key);
 38u64 siphash_4u64(const u64 a, const u64 b, const u64 c, const u64 d,
 39		 const siphash_key_t *key);
 40u64 siphash_1u32(const u32 a, const siphash_key_t *key);
 41u64 siphash_3u32(const u32 a, const u32 b, const u32 c,
 42		 const siphash_key_t *key);
 43
 44static inline u64 siphash_2u32(const u32 a, const u32 b,
 45			       const siphash_key_t *key)
 46{
 47	return siphash_1u64((u64)b << 32 | a, key);
 48}
 49static inline u64 siphash_4u32(const u32 a, const u32 b, const u32 c,
 50			       const u32 d, const siphash_key_t *key)
 51{
 52	return siphash_2u64((u64)b << 32 | a, (u64)d << 32 | c, key);
 53}
 54
 55
 56static inline u64 ___siphash_aligned(const __le64 *data, size_t len,
 57				     const siphash_key_t *key)
 58{
 59	if (__builtin_constant_p(len) && len == 4)
 60		return siphash_1u32(le32_to_cpup((const __le32 *)data), key);
 61	if (__builtin_constant_p(len) && len == 8)
 62		return siphash_1u64(le64_to_cpu(data[0]), key);
 63	if (__builtin_constant_p(len) && len == 16)
 64		return siphash_2u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
 65				    key);
 66	if (__builtin_constant_p(len) && len == 24)
 67		return siphash_3u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
 68				    le64_to_cpu(data[2]), key);
 69	if (__builtin_constant_p(len) && len == 32)
 70		return siphash_4u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
 71				    le64_to_cpu(data[2]), le64_to_cpu(data[3]),
 72				    key);
 73	return __siphash_aligned(data, len, key);
 74}
 75
 76/**
 77 * siphash - compute 64-bit siphash PRF value
 78 * @data: buffer to hash
 79 * @size: size of @data
 80 * @key: the siphash key
 81 */
 82static inline u64 siphash(const void *data, size_t len,
 83			  const siphash_key_t *key)
 84{
 85#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 86	if (!IS_ALIGNED((unsigned long)data, SIPHASH_ALIGNMENT))
 87		return __siphash_unaligned(data, len, key);
 88#endif
 89	return ___siphash_aligned(data, len, key);
 90}
 91
 92#define HSIPHASH_ALIGNMENT __alignof__(unsigned long)
 93typedef struct {
 94	unsigned long key[2];
 95} hsiphash_key_t;
 96
 97u32 __hsiphash_aligned(const void *data, size_t len,
 98		       const hsiphash_key_t *key);
 99#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
100u32 __hsiphash_unaligned(const void *data, size_t len,
101			 const hsiphash_key_t *key);
102#endif
103
104u32 hsiphash_1u32(const u32 a, const hsiphash_key_t *key);
105u32 hsiphash_2u32(const u32 a, const u32 b, const hsiphash_key_t *key);
106u32 hsiphash_3u32(const u32 a, const u32 b, const u32 c,
107		  const hsiphash_key_t *key);
108u32 hsiphash_4u32(const u32 a, const u32 b, const u32 c, const u32 d,
109		  const hsiphash_key_t *key);
110
111static inline u32 ___hsiphash_aligned(const __le32 *data, size_t len,
112				      const hsiphash_key_t *key)
113{
114	if (__builtin_constant_p(len) && len == 4)
115		return hsiphash_1u32(le32_to_cpu(data[0]), key);
116	if (__builtin_constant_p(len) && len == 8)
117		return hsiphash_2u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
118				     key);
119	if (__builtin_constant_p(len) && len == 12)
120		return hsiphash_3u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
121				     le32_to_cpu(data[2]), key);
122	if (__builtin_constant_p(len) && len == 16)
123		return hsiphash_4u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
124				     le32_to_cpu(data[2]), le32_to_cpu(data[3]),
125				     key);
126	return __hsiphash_aligned(data, len, key);
127}
128
129/**
130 * hsiphash - compute 32-bit hsiphash PRF value
131 * @data: buffer to hash
132 * @size: size of @data
133 * @key: the hsiphash key
134 */
135static inline u32 hsiphash(const void *data, size_t len,
136			   const hsiphash_key_t *key)
137{
138#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
139	if (!IS_ALIGNED((unsigned long)data, HSIPHASH_ALIGNMENT))
140		return __hsiphash_unaligned(data, len, key);
141#endif
142	return ___hsiphash_aligned(data, len, key);
143}
144
145#endif /* _LINUX_SIPHASH_H */