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/module.h> 12 #include <linux/bitops.h> 13 #include <linux/string.h> 14 #include <crypto/sha1.h> 15 #include <asm/unaligned.h> 16 17 /* 18 * If you have 32 registers or more, the compiler can (and should) 19 * try to change the array[] accesses into registers. However, on 20 * machines with less than ~25 registers, that won't really work, 21 * and at least gcc will make an unholy mess of it. 22 * 23 * So to avoid that mess which just slows things down, we force 24 * the stores to memory to actually happen (we might be better off 25 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as 26 * suggested by Artur Skawina - that will also make gcc unable to 27 * try to do the silly "optimize away loads" part because it won't 28 * see what the value will be). 29 * 30 * Ben Herrenschmidt reports that on PPC, the C version comes close 31 * to the optimized asm with this (ie on PPC you don't want that 32 * 'volatile', since there are lots of registers). 33 * 34 * On ARM we get the best code generation by forcing a full memory barrier 35 * between each SHA_ROUND, otherwise gcc happily get wild with spilling and 36 * the stack frame size simply explode and performance goes down the drain. 37 */ 38 39 #ifdef CONFIG_X86 40 #define setW(x, val) (*(volatile __u32 *)&W(x) = (val)) 41 #elif defined(CONFIG_ARM) 42 #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0) 43 #else 44 #define setW(x, val) (W(x) = (val)) 45 #endif 46 47 /* This "rolls" over the 512-bit array */ 48 #define W(x) (array[(x)&15]) 49 50 /* 51 * Where do we get the source from? The first 16 iterations get it from 52 * the input data, the next mix it from the 512-bit array. 53 */ 54 #define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t) 55 #define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1) 56 57 #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \ 58 __u32 TEMP = input(t); setW(t, TEMP); \ 59 E += TEMP + rol32(A,5) + (fn) + (constant); \ 60 B = ror32(B, 2); \ 61 TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0) 62 63 #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 ) 64 #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 ) 65 #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E ) 66 #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 ) 67 #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E ) 68 69 /** 70 * sha1_transform - single block SHA1 transform (deprecated) 71 * 72 * @digest: 160 bit digest to update 73 * @data: 512 bits of data to hash 74 * @array: 16 words of workspace (see note) 75 * 76 * This function executes SHA-1's internal compression function. It updates the 77 * 160-bit internal state (@digest) with a single 512-bit data block (@data). 78 * 79 * Don't use this function. SHA-1 is no longer considered secure. And even if 80 * you do have to use SHA-1, this isn't the correct way to hash something with 81 * SHA-1 as this doesn't handle padding and finalization. 82 * 83 * Note: If the hash is security sensitive, the caller should be sure 84 * to clear the workspace. This is left to the caller to avoid 85 * unnecessary clears between chained hashing operations. 86 */ sha1_transform(__u32 * digest,const char * data,__u32 * array)87 void sha1_transform(__u32 *digest, const char *data, __u32 *array) 88 { 89 __u32 A, B, C, D, E; 90 unsigned int i = 0; 91 92 A = digest[0]; 93 B = digest[1]; 94 C = digest[2]; 95 D = digest[3]; 96 E = digest[4]; 97 98 /* Round 1 - iterations 0-16 take their input from 'data' */ 99 for (; i < 16; ++i) 100 T_0_15(i, A, B, C, D, E); 101 102 /* Round 1 - tail. Input from 512-bit mixing array */ 103 for (; i < 20; ++i) 104 T_16_19(i, A, B, C, D, E); 105 106 /* Round 2 */ 107 for (; i < 40; ++i) 108 T_20_39(i, A, B, C, D, E); 109 110 /* Round 3 */ 111 for (; i < 60; ++i) 112 T_40_59(i, A, B, C, D, E); 113 114 /* Round 4 */ 115 for (; i < 80; ++i) 116 T_60_79(i, A, B, C, D, E); 117 118 digest[0] += A; 119 digest[1] += B; 120 digest[2] += C; 121 digest[3] += D; 122 digest[4] += E; 123 } 124 EXPORT_SYMBOL(sha1_transform); 125 126 /** 127 * sha1_init - initialize the vectors for a SHA1 digest 128 * @buf: vector to initialize 129 */ sha1_init(__u32 * buf)130 void sha1_init(__u32 *buf) 131 { 132 buf[0] = 0x67452301; 133 buf[1] = 0xefcdab89; 134 buf[2] = 0x98badcfe; 135 buf[3] = 0x10325476; 136 buf[4] = 0xc3d2e1f0; 137 } 138 EXPORT_SYMBOL(sha1_init); 139 140 MODULE_LICENSE("GPL"); 141