LXR linux/lib/sha1.c

   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 <asm/unaligned.h>
  14
  15/*
  16 * If you have 32 registers or more, the compiler can (and should)
  17 * try to change the array[] accesses into registers. However, on
  18 * machines with less than ~25 registers, that won't really work,
  19 * and at least gcc will make an unholy mess of it.
  20 *
  21 * So to avoid that mess which just slows things down, we force
  22 * the stores to memory to actually happen (we might be better off
  23 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
  24 * suggested by Artur Skawina - that will also make gcc unable to
  25 * try to do the silly "optimize away loads" part because it won't
  26 * see what the value will be).
  27 *
  28 * Ben Herrenschmidt reports that on PPC, the C version comes close
  29 * to the optimized asm with this (ie on PPC you don't want that
  30 * 'volatile', since there are lots of registers).
  31 *
  32 * On ARM we get the best code generation by forcing a full memory barrier
  33 * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
  34 * the stack frame size simply explode and performance goes down the drain.
  35 */
  36
  37#ifdef CONFIG_X86
  38  #define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
  39#elif defined(CONFIG_ARM)
  40  #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
  41#else
  42  #define setW(x, val) (W(x) = (val))
  43#endif
  44
  45/* This "rolls" over the 512-bit array */
  46#define W(x) (array[(x)&15])
  47
  48/*
  49 * Where do we get the source from? The first 16 iterations get it from
  50 * the input data, the next mix it from the 512-bit array.
  51 */
  52#define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
  53#define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
  54
  55#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
  56        __u32 TEMP = input(t); setW(t, TEMP); \
  57        E += TEMP + rol32(A,5) + (fn) + (constant); \
  58        B = ror32(B, 2); } while (0)
  59
  60#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 )
  61#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 )
  62#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
  63#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 )
  64#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )
  65
  66/**
  67 * sha_transform - single block SHA1 transform
  68 *
  69 * @digest: 160 bit digest to update
  70 * @data:   512 bits of data to hash
  71 * @array:  16 words of workspace (see note)
  72 *
  73 * This function generates a SHA1 digest for a single 512-bit block.
  74 * Be warned, it does not handle padding and message digest, do not
  75 * confuse it with the full FIPS 180-1 digest algorithm for variable
  76 * length messages.
  77 *
  78 * Note: If the hash is security sensitive, the caller should be sure
  79 * to clear the workspace. This is left to the caller to avoid
  80 * unnecessary clears between chained hashing operations.
  81 */
  82void sha_transform(__u32 *digest, const char *data, __u32 *array)
  83{
  84        __u32 A, B, C, D, E;
  85
  86        A = digest[0];
  87        B = digest[1];
  88        C = digest[2];
  89        D = digest[3];
  90        E = digest[4];
  91
  92        /* Round 1 - iterations 0-16 take their input from 'data' */
  93        T_0_15( 0, A, B, C, D, E);
  94        T_0_15( 1, E, A, B, C, D);
  95        T_0_15( 2, D, E, A, B, C);
  96        T_0_15( 3, C, D, E, A, B);
  97        T_0_15( 4, B, C, D, E, A);
  98        T_0_15( 5, A, B, C, D, E);
  99        T_0_15( 6, E, A, B, C, D);
 100        T_0_15( 7, D, E, A, B, C);
 101        T_0_15( 8, C, D, E, A, B);
 102        T_0_15( 9, B, C, D, E, A);
 103        T_0_15(10, A, B, C, D, E);
 104        T_0_15(11, E, A, B, C, D);
 105        T_0_15(12, D, E, A, B, C);
 106        T_0_15(13, C, D, E, A, B);
 107        T_0_15(14, B, C, D, E, A);
 108        T_0_15(15, A, B, C, D, E);
 109
 110        /* Round 1 - tail. Input from 512-bit mixing array */
 111        T_16_19(16, E, A, B, C, D);
 112        T_16_19(17, D, E, A, B, C);
 113        T_16_19(18, C, D, E, A, B);
 114        T_16_19(19, B, C, D, E, A);
 115
 116        /* Round 2 */
 117        T_20_39(20, A, B, C, D, E);
 118        T_20_39(21, E, A, B, C, D);
 119        T_20_39(22, D, E, A, B, C);
 120        T_20_39(23, C, D, E, A, B);
 121        T_20_39(24, B, C, D, E, A);
 122        T_20_39(25, A, B, C, D, E);
 123        T_20_39(26, E, A, B, C, D);
 124        T_20_39(27, D, E, A, B, C);
 125        T_20_39(28, C, D, E, A, B);
 126        T_20_39(29, B, C, D, E, A);
 127        T_20_39(30, A, B, C, D, E);
 128        T_20_39(31, E, A, B, C, D);
 129        T_20_39(32, D, E, A, B, C);
 130        T_20_39(33, C, D, E, A, B);
 131        T_20_39(34, B, C, D, E, A);
 132        T_20_39(35, A, B, C, D, E);
 133        T_20_39(36, E, A, B, C, D);
 134        T_20_39(37, D, E, A, B, C);
 135        T_20_39(38, C, D, E, A, B);
 136        T_20_39(39, B, C, D, E, A);
 137
 138        /* Round 3 */
 139        T_40_59(40, A, B, C, D, E);
 140        T_40_59(41, E, A, B, C, D);
 141        T_40_59(42, D, E, A, B, C);
 142        T_40_59(43, C, D, E, A, B);
 143        T_40_59(44, B, C, D, E, A);
 144        T_40_59(45, A, B, C, D, E);
 145        T_40_59(46, E, A, B, C, D);
 146        T_40_59(47, D, E, A, B, C);
 147        T_40_59(48, C, D, E, A, B);
 148        T_40_59(49, B, C, D, E, A);
 149        T_40_59(50, A, B, C, D, E);
 150        T_40_59(51, E, A, B, C, D);
 151        T_40_59(52, D, E, A, B, C);
 152        T_40_59(53, C, D, E, A, B);
 153        T_40_59(54, B, C, D, E, A);
 154        T_40_59(55, A, B, C, D, E);
 155        T_40_59(56, E, A, B, C, D);
 156        T_40_59(57, D, E, A, B, C);
 157        T_40_59(58, C, D, E, A, B);
 158        T_40_59(59, B, C, D, E, A);
 159
 160        /* Round 4 */
 161        T_60_79(60, A, B, C, D, E);
 162        T_60_79(61, E, A, B, C, D);
 163        T_60_79(62, D, E, A, B, C);
 164        T_60_79(63, C, D, E, A, B);
 165        T_60_79(64, B, C, D, E, A);
 166        T_60_79(65, A, B, C, D, E);
 167        T_60_79(66, E, A, B, C, D);
 168        T_60_79(67, D, E, A, B, C);
 169        T_60_79(68, C, D, E, A, B);
 170        T_60_79(69, B, C, D, E, A);
 171        T_60_79(70, A, B, C, D, E);
 172        T_60_79(71, E, A, B, C, D);
 173        T_60_79(72, D, E, A, B, C);
 174        T_60_79(73, C, D, E, A, B);
 175        T_60_79(74, B, C, D, E, A);
 176        T_60_79(75, A, B, C, D, E);
 177        T_60_79(76, E, A, B, C, D);
 178        T_60_79(77, D, E, A, B, C);
 179        T_60_79(78, C, D, E, A, B);
 180        T_60_79(79, B, C, D, E, A);
 181
 182        digest[0] += A;
 183        digest[1] += B;
 184        digest[2] += C;
 185        digest[3] += D;
 186        digest[4] += E;
 187}
 188EXPORT_SYMBOL(sha_transform);
 189
 190/**
 191 * sha_init - initialize the vectors for a SHA1 digest
 192 * @buf: vector to initialize
 193 */
 194void sha_init(__u32 *buf)
 195{
 196        buf[0] = 0x67452301;
 197        buf[1] = 0xefcdab89;
 198        buf[2] = 0x98badcfe;
 199        buf[3] = 0x10325476;
 200        buf[4] = 0xc3d2e1f0;
 201}
 202EXPORT_SYMBOL(sha_init);
 203