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