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