xref: /linux/include/linux/siphash.h (revision fd7d598270724cc787982ea48bbe17ad383a8b7f)
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)
19 typedef struct {
20 	u64 key[2];
21 } siphash_key_t;
22 
23 #define siphash_aligned_key_t siphash_key_t __aligned(16)
24 
25 static inline bool siphash_key_is_zero(const siphash_key_t *key)
26 {
27 	return !(key->key[0] | key->key[1]);
28 }
29 
30 u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key);
31 u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key);
32 
33 u64 siphash_1u64(const u64 a, const siphash_key_t *key);
34 u64 siphash_2u64(const u64 a, const u64 b, const siphash_key_t *key);
35 u64 siphash_3u64(const u64 a, const u64 b, const u64 c,
36 		 const siphash_key_t *key);
37 u64 siphash_4u64(const u64 a, const u64 b, const u64 c, const u64 d,
38 		 const siphash_key_t *key);
39 u64 siphash_1u32(const u32 a, const siphash_key_t *key);
40 u64 siphash_3u32(const u32 a, const u32 b, const u32 c,
41 		 const siphash_key_t *key);
42 
43 static 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 }
48 static 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 
55 static 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  */
81 static 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)
91 typedef struct {
92 	unsigned long key[2];
93 } hsiphash_key_t;
94 
95 u32 __hsiphash_aligned(const void *data, size_t len,
96 		       const hsiphash_key_t *key);
97 u32 __hsiphash_unaligned(const void *data, size_t len,
98 			 const hsiphash_key_t *key);
99 
100 u32 hsiphash_1u32(const u32 a, const hsiphash_key_t *key);
101 u32 hsiphash_2u32(const u32 a, const u32 b, const hsiphash_key_t *key);
102 u32 hsiphash_3u32(const u32 a, const u32 b, const u32 c,
103 		  const hsiphash_key_t *key);
104 u32 hsiphash_4u32(const u32 a, const u32 b, const u32 c, const u32 d,
105 		  const hsiphash_key_t *key);
106 
107 static 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  */
131 static 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 */
169