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/*
* Accelerated GHASH implementation with ARMv8 PMULL instructions.
*
* Copyright (C) 2014 - 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
#include <asm/neon.h>
#include <asm/simd.h>
#include <asm/unaligned.h>
#include <crypto/gf128mul.h>
#include <crypto/internal/hash.h>
#include <linux/cpufeature.h>
#include <linux/crypto.h>
#include <linux/module.h>
MODULE_DESCRIPTION("GHASH secure hash using ARMv8 Crypto Extensions");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
#define GHASH_BLOCK_SIZE 16
#define GHASH_DIGEST_SIZE 16
struct ghash_key {
u64 a;
u64 b;
be128 k;
};
struct ghash_desc_ctx {
u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
u8 buf[GHASH_BLOCK_SIZE];
u32 count;
};
asmlinkage void pmull_ghash_update(int blocks, u64 dg[], const char *src,
struct ghash_key const *k, const char *head);
static int ghash_init(struct shash_desc *desc)
{
struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
*ctx = (struct ghash_desc_ctx){};
return 0;
}
static void ghash_do_update(int blocks, u64 dg[], const char *src,
struct ghash_key *key, const char *head)
{
if (likely(may_use_simd())) {
kernel_neon_begin();
pmull_ghash_update(blocks, dg, src, key, head);
kernel_neon_end();
} else {
be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
do {
const u8 *in = src;
if (head) {
in = head;
blocks++;
head = NULL;
} else {
src += GHASH_BLOCK_SIZE;
}
crypto_xor((u8 *)&dst, in, GHASH_BLOCK_SIZE);
gf128mul_lle(&dst, &key->k);
} while (--blocks);
dg[0] = be64_to_cpu(dst.b);
dg[1] = be64_to_cpu(dst.a);
}
}
static int ghash_update(struct shash_desc *desc, const u8 *src,
unsigned int len)
{
struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
ctx->count += len;
if ((partial + len) >= GHASH_BLOCK_SIZE) {
struct ghash_key *key = crypto_shash_ctx(desc->tfm);
int blocks;
if (partial) {
int p = GHASH_BLOCK_SIZE - partial;
memcpy(ctx->buf + partial, src, p);
src += p;
len -= p;
}
blocks = len / GHASH_BLOCK_SIZE;
len %= GHASH_BLOCK_SIZE;
ghash_do_update(blocks, ctx->digest, src, key,
partial ? ctx->buf : NULL);
src += blocks * GHASH_BLOCK_SIZE;
partial = 0;
}
if (len)
memcpy(ctx->buf + partial, src, len);
return 0;
}
static int ghash_final(struct shash_desc *desc, u8 *dst)
{
struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
if (partial) {
struct ghash_key *key = crypto_shash_ctx(desc->tfm);
memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
ghash_do_update(1, ctx->digest, ctx->buf, key, NULL);
}
put_unaligned_be64(ctx->digest[1], dst);
put_unaligned_be64(ctx->digest[0], dst + 8);
*ctx = (struct ghash_desc_ctx){};
return 0;
}
static int ghash_setkey(struct crypto_shash *tfm,
const u8 *inkey, unsigned int keylen)
{
struct ghash_key *key = crypto_shash_ctx(tfm);
u64 a, b;
if (keylen != GHASH_BLOCK_SIZE) {
crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
return -EINVAL;
}
/* needed for the fallback */
memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
/* perform multiplication by 'x' in GF(2^128) */
b = get_unaligned_be64(inkey);
a = get_unaligned_be64(inkey + 8);
key->a = (a << 1) | (b >> 63);
key->b = (b << 1) | (a >> 63);
if (b >> 63)
key->b ^= 0xc200000000000000UL;
return 0;
}
static struct shash_alg ghash_alg = {
.digestsize = GHASH_DIGEST_SIZE,
.init = ghash_init,
.update = ghash_update,
.final = ghash_final,
.setkey = ghash_setkey,
.descsize = sizeof(struct ghash_desc_ctx),
.base = {
.cra_name = "ghash",
.cra_driver_name = "ghash-ce",
.cra_priority = 200,
.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.cra_blocksize = GHASH_BLOCK_SIZE,
.cra_ctxsize = sizeof(struct ghash_key),
.cra_module = THIS_MODULE,
},
};
static int __init ghash_ce_mod_init(void)
{
return crypto_register_shash(&ghash_alg);
}
static void __exit ghash_ce_mod_exit(void)
{
crypto_unregister_shash(&ghash_alg);
}
module_cpu_feature_match(PMULL, ghash_ce_mod_init);
module_exit(ghash_ce_mod_exit);
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