1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * SHA1 routine optimized to do word accesses rather than byte accesses,
4 * and to avoid unnecessary copies into the context array.
5 *
6 * This was based on the git SHA1 implementation.
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/export.h>
11 #include <linux/bitops.h>
12 #include <linux/cryptohash.h>
13 #include <linux/string.h>
14 #include <asm/unaligned.h>
15
16 /*
17 * If you have 32 registers or more, the compiler can (and should)
18 * try to change the array[] accesses into registers. However, on
19 * machines with less than ~25 registers, that won't really work,
20 * and at least gcc will make an unholy mess of it.
21 *
22 * So to avoid that mess which just slows things down, we force
23 * the stores to memory to actually happen (we might be better off
24 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
25 * suggested by Artur Skawina - that will also make gcc unable to
26 * try to do the silly "optimize away loads" part because it won't
27 * see what the value will be).
28 *
29 * Ben Herrenschmidt reports that on PPC, the C version comes close
30 * to the optimized asm with this (ie on PPC you don't want that
31 * 'volatile', since there are lots of registers).
32 *
33 * On ARM we get the best code generation by forcing a full memory barrier
34 * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
35 * the stack frame size simply explode and performance goes down the drain.
36 */
37
38 #ifdef CONFIG_X86
39 #define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
40 #elif defined(CONFIG_ARM)
41 #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
42 #else
43 #define setW(x, val) (W(x) = (val))
44 #endif
45
46 /* This "rolls" over the 512-bit array */
47 #define W(x) (array[(x)&15])
48
49 /*
50 * Where do we get the source from? The first 16 iterations get it from
51 * the input data, the next mix it from the 512-bit array.
52 */
53 #define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
54 #define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
55
56 #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
57 __u32 TEMP = input(t); setW(t, TEMP); \
58 E += TEMP + rol32(A,5) + (fn) + (constant); \
59 B = ror32(B, 2); \
60 TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0)
61
62 #define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
63 #define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
64 #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
65 #define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
66 #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
67
68 /**
69 * sha_transform - single block SHA1 transform
70 *
71 * @digest: 160 bit digest to update
72 * @data: 512 bits of data to hash
73 * @array: 16 words of workspace (see note)
74 *
75 * This function generates a SHA1 digest for a single 512-bit block.
76 * Be warned, it does not handle padding and message digest, do not
77 * confuse it with the full FIPS 180-1 digest algorithm for variable
78 * length messages.
79 *
80 * Note: If the hash is security sensitive, the caller should be sure
81 * to clear the workspace. This is left to the caller to avoid
82 * unnecessary clears between chained hashing operations.
83 */
sha_transform(__u32 * digest,const char * data,__u32 * array)84 void sha_transform(__u32 *digest, const char *data, __u32 *array)
85 {
86 __u32 A, B, C, D, E;
87 unsigned int i = 0;
88
89 A = digest[0];
90 B = digest[1];
91 C = digest[2];
92 D = digest[3];
93 E = digest[4];
94
95 /* Round 1 - iterations 0-16 take their input from 'data' */
96 for (; i < 16; ++i)
97 T_0_15(i, A, B, C, D, E);
98
99 /* Round 1 - tail. Input from 512-bit mixing array */
100 for (; i < 20; ++i)
101 T_16_19(i, A, B, C, D, E);
102
103 /* Round 2 */
104 for (; i < 40; ++i)
105 T_20_39(i, A, B, C, D, E);
106
107 /* Round 3 */
108 for (; i < 60; ++i)
109 T_40_59(i, A, B, C, D, E);
110
111 /* Round 4 */
112 for (; i < 80; ++i)
113 T_60_79(i, A, B, C, D, E);
114
115 digest[0] += A;
116 digest[1] += B;
117 digest[2] += C;
118 digest[3] += D;
119 digest[4] += E;
120 }
121 EXPORT_SYMBOL(sha_transform);
122
123 /**
124 * sha_init - initialize the vectors for a SHA1 digest
125 * @buf: vector to initialize
126 */
sha_init(__u32 * buf)127 void sha_init(__u32 *buf)
128 {
129 buf[0] = 0x67452301;
130 buf[1] = 0xefcdab89;
131 buf[2] = 0x98badcfe;
132 buf[3] = 0x10325476;
133 buf[4] = 0xc3d2e1f0;
134 }
135 EXPORT_SYMBOL(sha_init);
136