141 lines
4.4 KiB
C
141 lines
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* SHA1 routine optimized to do word accesses rather than byte accesses,
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* and to avoid unnecessary copies into the context array.
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*
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* This was based on the git SHA1 implementation.
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*/
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/module.h>
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#include <linux/bitops.h>
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#include <linux/string.h>
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#include <crypto/sha1.h>
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#include <asm/unaligned.h>
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/*
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* If you have 32 registers or more, the compiler can (and should)
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* try to change the array[] accesses into registers. However, on
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* machines with less than ~25 registers, that won't really work,
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* and at least gcc will make an unholy mess of it.
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*
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* So to avoid that mess which just slows things down, we force
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* the stores to memory to actually happen (we might be better off
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* with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
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* suggested by Artur Skawina - that will also make gcc unable to
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* try to do the silly "optimize away loads" part because it won't
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* see what the value will be).
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*
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* Ben Herrenschmidt reports that on PPC, the C version comes close
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* to the optimized asm with this (ie on PPC you don't want that
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* 'volatile', since there are lots of registers).
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*
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* On ARM we get the best code generation by forcing a full memory barrier
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* between each SHA_ROUND, otherwise gcc happily get wild with spilling and
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* the stack frame size simply explode and performance goes down the drain.
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*/
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#ifdef CONFIG_X86
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#define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
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#elif defined(CONFIG_ARM)
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#define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
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#else
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#define setW(x, val) (W(x) = (val))
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#endif
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/* This "rolls" over the 512-bit array */
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#define W(x) (array[(x)&15])
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/*
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* Where do we get the source from? The first 16 iterations get it from
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* the input data, the next mix it from the 512-bit array.
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*/
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#define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
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#define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
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#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
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__u32 TEMP = input(t); setW(t, TEMP); \
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E += TEMP + rol32(A,5) + (fn) + (constant); \
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B = ror32(B, 2); \
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TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0)
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#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 )
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#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 )
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#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
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#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 )
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#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
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/**
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* sha1_transform - single block SHA1 transform (deprecated)
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*
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* @digest: 160 bit digest to update
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* @data: 512 bits of data to hash
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* @array: 16 words of workspace (see note)
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*
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* This function executes SHA-1's internal compression function. It updates the
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* 160-bit internal state (@digest) with a single 512-bit data block (@data).
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*
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* Don't use this function. SHA-1 is no longer considered secure. And even if
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* you do have to use SHA-1, this isn't the correct way to hash something with
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* SHA-1 as this doesn't handle padding and finalization.
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*
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* Note: If the hash is security sensitive, the caller should be sure
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* to clear the workspace. This is left to the caller to avoid
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* unnecessary clears between chained hashing operations.
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*/
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void sha1_transform(__u32 *digest, const char *data, __u32 *array)
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{
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__u32 A, B, C, D, E;
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unsigned int i = 0;
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A = digest[0];
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B = digest[1];
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C = digest[2];
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D = digest[3];
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E = digest[4];
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/* Round 1 - iterations 0-16 take their input from 'data' */
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for (; i < 16; ++i)
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T_0_15(i, A, B, C, D, E);
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/* Round 1 - tail. Input from 512-bit mixing array */
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for (; i < 20; ++i)
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T_16_19(i, A, B, C, D, E);
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/* Round 2 */
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for (; i < 40; ++i)
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T_20_39(i, A, B, C, D, E);
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/* Round 3 */
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for (; i < 60; ++i)
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T_40_59(i, A, B, C, D, E);
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/* Round 4 */
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for (; i < 80; ++i)
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T_60_79(i, A, B, C, D, E);
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digest[0] += A;
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digest[1] += B;
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digest[2] += C;
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digest[3] += D;
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digest[4] += E;
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}
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EXPORT_SYMBOL(sha1_transform);
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/**
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* sha1_init - initialize the vectors for a SHA1 digest
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* @buf: vector to initialize
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*/
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void sha1_init(__u32 *buf)
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{
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buf[0] = 0x67452301;
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buf[1] = 0xefcdab89;
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buf[2] = 0x98badcfe;
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buf[3] = 0x10325476;
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buf[4] = 0xc3d2e1f0;
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}
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EXPORT_SYMBOL(sha1_init);
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MODULE_LICENSE("GPL");
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