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// SPDX-License-Identifier: GPL-2.0
/*
* SHA1 routine optimized to do word accesses rather than byte accesses,
* and to avoid unnecessary copies into the context array.
*
* This was based on the git SHA1 implementation.
*/
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/bitops.h>
#include <linux/cryptohash.h>
#include <linux/string.h>
#include <asm/unaligned.h>
/*
* If you have 32 registers or more, the compiler can (and should)
* try to change the array[] accesses into registers. However, on
* machines with less than ~25 registers, that won't really work,
* and at least gcc will make an unholy mess of it.
*
* So to avoid that mess which just slows things down, we force
* the stores to memory to actually happen (we might be better off
* with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
* suggested by Artur Skawina - that will also make gcc unable to
* try to do the silly "optimize away loads" part because it won't
* see what the value will be).
*
* Ben Herrenschmidt reports that on PPC, the C version comes close
* to the optimized asm with this (ie on PPC you don't want that
* 'volatile', since there are lots of registers).
*
* On ARM we get the best code generation by forcing a full memory barrier
* between each SHA_ROUND, otherwise gcc happily get wild with spilling and
* the stack frame size simply explode and performance goes down the drain.
*/
#ifdef CONFIG_X86
#define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
#elif defined(CONFIG_ARM)
#define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
#else
#define setW(x, val) (W(x) = (val))
#endif
/* This "rolls" over the 512-bit array */
#define W(x) (array[(x)&15])
/*
* Where do we get the source from? The first 16 iterations get it from
* the input data, the next mix it from the 512-bit array.
*/
#define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
#define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
__u32 TEMP = input(t); setW(t, TEMP); \
E += TEMP + rol32(A,5) + (fn) + (constant); \
B = ror32(B, 2); \
TEMP = E; E = D; D = C; C = B; B = A; A = TEMP; } while (0)
#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 )
#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 )
#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
#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 )
#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
/**
* sha_transform - single block SHA1 transform
*
* @digest: 160 bit digest to update
* @data: 512 bits of data to hash
* @array: 16 words of workspace (see note)
*
* This function generates a SHA1 digest for a single 512-bit block.
* Be warned, it does not handle padding and message digest, do not
* confuse it with the full FIPS 180-1 digest algorithm for variable
* length messages.
*
* Note: If the hash is security sensitive, the caller should be sure
* to clear the workspace. This is left to the caller to avoid
* unnecessary clears between chained hashing operations.
*/
void sha_transform(__u32 *digest, const char *data, __u32 *array)
{
__u32 A, B, C, D, E;
unsigned int i = 0;
A = digest[0];
B = digest[1];
C = digest[2];
D = digest[3];
E = digest[4];
/* Round 1 - iterations 0-16 take their input from 'data' */
for (; i < 16; ++i)
T_0_15(i, A, B, C, D, E);
/* Round 1 - tail. Input from 512-bit mixing array */
for (; i < 20; ++i)
T_16_19(i, A, B, C, D, E);
/* Round 2 */
for (; i < 40; ++i)
T_20_39(i, A, B, C, D, E);
/* Round 3 */
for (; i < 60; ++i)
T_40_59(i, A, B, C, D, E);
/* Round 4 */
for (; i < 80; ++i)
T_60_79(i, A, B, C, D, E);
digest[0] += A;
digest[1] += B;
digest[2] += C;
digest[3] += D;
digest[4] += E;
}
EXPORT_SYMBOL(sha_transform);
/**
* sha_init - initialize the vectors for a SHA1 digest
* @buf: vector to initialize
*/
void sha_init(__u32 *buf)
{
buf[0] = 0x67452301;
buf[1] = 0xefcdab89;
buf[2] = 0x98badcfe;
buf[3] = 0x10325476;
buf[4] = 0xc3d2e1f0;
}
EXPORT_SYMBOL(sha_init);
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