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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/aes.h>
#include <crypto/algapi.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/cpufeature.h>
#include <linux/crypto.h>
#include <linux/module.h>
MODULE_DESCRIPTION("GHASH and AES-GCM using ARMv8 Crypto Extensions");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("ghash");
#define GHASH_BLOCK_SIZE 16
#define GHASH_DIGEST_SIZE 16
#define GCM_IV_SIZE 12
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;
};
struct gcm_aes_ctx {
struct crypto_aes_ctx aes_key;
struct ghash_key ghash_key;
};
asmlinkage void pmull_ghash_update_p64(int blocks, u64 dg[], const char *src,
struct ghash_key const *k,
const char *head);
asmlinkage void pmull_ghash_update_p8(int blocks, u64 dg[], const char *src,
struct ghash_key const *k,
const char *head);
static void (*pmull_ghash_update)(int blocks, u64 dg[], const char *src,
struct ghash_key const *k,
const char *head);
asmlinkage void pmull_gcm_encrypt(int blocks, u64 dg[], u8 dst[],
const u8 src[], struct ghash_key const *k,
u8 ctr[], u32 const rk[], int rounds,
u8 ks[]);
asmlinkage void pmull_gcm_decrypt(int blocks, u64 dg[], u8 dst[],
const u8 src[], struct ghash_key const *k,
u8 ctr[], u32 const rk[], int rounds);
asmlinkage void pmull_gcm_encrypt_block(u8 dst[], u8 const src[],
u32 const rk[], int rounds);
asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
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 ghash_key *key,
const u8 *inkey, unsigned int keylen)
{
u64 a, b;
/* 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 int ghash_setkey(struct crypto_shash *tfm,
const u8 *inkey, unsigned int keylen)
{
struct ghash_key *key = crypto_shash_ctx(tfm);
if (keylen != GHASH_BLOCK_SIZE) {
crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
return -EINVAL;
}
return __ghash_setkey(key, inkey, keylen);
}
static struct shash_alg ghash_alg = {
.base.cra_name = "ghash",
.base.cra_driver_name = "ghash-ce",
.base.cra_priority = 200,
.base.cra_flags = CRYPTO_ALG_TYPE_SHASH,
.base.cra_blocksize = GHASH_BLOCK_SIZE,
.base.cra_ctxsize = sizeof(struct ghash_key),
.base.cra_module = THIS_MODULE,
.digestsize = GHASH_DIGEST_SIZE,
.init = ghash_init,
.update = ghash_update,
.final = ghash_final,
.setkey = ghash_setkey,
.descsize = sizeof(struct ghash_desc_ctx),
};
static int num_rounds(struct crypto_aes_ctx *ctx)
{
/*
* # of rounds specified by AES:
* 128 bit key 10 rounds
* 192 bit key 12 rounds
* 256 bit key 14 rounds
* => n byte key => 6 + (n/4) rounds
*/
return 6 + ctx->key_length / 4;
}
static int gcm_setkey(struct crypto_aead *tfm, const u8 *inkey,
unsigned int keylen)
{
struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
u8 key[GHASH_BLOCK_SIZE];
int ret;
ret = crypto_aes_expand_key(&ctx->aes_key, inkey, keylen);
if (ret) {
tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
__aes_arm64_encrypt(ctx->aes_key.key_enc, key, (u8[AES_BLOCK_SIZE]){},
num_rounds(&ctx->aes_key));
return __ghash_setkey(&ctx->ghash_key, key, sizeof(key));
}
static int gcm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
switch (authsize) {
case 4:
case 8:
case 12 ... 16:
break;
default:
return -EINVAL;
}
return 0;
}
static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
int *buf_count, struct gcm_aes_ctx *ctx)
{
if (*buf_count > 0) {
int buf_added = min(count, GHASH_BLOCK_SIZE - *buf_count);
memcpy(&buf[*buf_count], src, buf_added);
*buf_count += buf_added;
src += buf_added;
count -= buf_added;
}
if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
int blocks = count / GHASH_BLOCK_SIZE;
ghash_do_update(blocks, dg, src, &ctx->ghash_key,
*buf_count ? buf : NULL);
src += blocks * GHASH_BLOCK_SIZE;
count %= GHASH_BLOCK_SIZE;
*buf_count = 0;
}
if (count > 0) {
memcpy(buf, src, count);
*buf_count = count;
}
}
static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[])
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
u8 buf[GHASH_BLOCK_SIZE];
struct scatter_walk walk;
u32 len = req->assoclen;
int buf_count = 0;
scatterwalk_start(&walk, req->src);
do {
u32 n = scatterwalk_clamp(&walk, len);
u8 *p;
if (!n) {
scatterwalk_start(&walk, sg_next(walk.sg));
n = scatterwalk_clamp(&walk, len);
}
p = scatterwalk_map(&walk);
gcm_update_mac(dg, p, n, buf, &buf_count, ctx);
len -= n;
scatterwalk_unmap(p);
scatterwalk_advance(&walk, n);
scatterwalk_done(&walk, 0, len);
} while (len);
if (buf_count) {
memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL);
}
}
static void gcm_final(struct aead_request *req, struct gcm_aes_ctx *ctx,
u64 dg[], u8 tag[], int cryptlen)
{
u8 mac[AES_BLOCK_SIZE];
u128 lengths;
lengths.a = cpu_to_be64(req->assoclen * 8);
lengths.b = cpu_to_be64(cryptlen * 8);
ghash_do_update(1, dg, (void *)&lengths, &ctx->ghash_key, NULL);
put_unaligned_be64(dg[1], mac);
put_unaligned_be64(dg[0], mac + 8);
crypto_xor(tag, mac, AES_BLOCK_SIZE);
}
static int gcm_encrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
struct skcipher_walk walk;
u8 iv[AES_BLOCK_SIZE];
u8 ks[AES_BLOCK_SIZE];
u8 tag[AES_BLOCK_SIZE];
u64 dg[2] = {};
int err;
if (req->assoclen)
gcm_calculate_auth_mac(req, dg);
memcpy(iv, req->iv, GCM_IV_SIZE);
put_unaligned_be32(1, iv + GCM_IV_SIZE);
if (likely(may_use_simd())) {
kernel_neon_begin();
pmull_gcm_encrypt_block(tag, iv, ctx->aes_key.key_enc,
num_rounds(&ctx->aes_key));
put_unaligned_be32(2, iv + GCM_IV_SIZE);
pmull_gcm_encrypt_block(ks, iv, NULL,
num_rounds(&ctx->aes_key));
put_unaligned_be32(3, iv + GCM_IV_SIZE);
kernel_neon_end();
err = skcipher_walk_aead_encrypt(&walk, req, false);
while (walk.nbytes >= AES_BLOCK_SIZE) {
int blocks = walk.nbytes / AES_BLOCK_SIZE;
kernel_neon_begin();
pmull_gcm_encrypt(blocks, dg, walk.dst.virt.addr,
walk.src.virt.addr, &ctx->ghash_key,
iv, ctx->aes_key.key_enc,
num_rounds(&ctx->aes_key), ks);
kernel_neon_end();
err = skcipher_walk_done(&walk,
walk.nbytes % AES_BLOCK_SIZE);
}
} else {
__aes_arm64_encrypt(ctx->aes_key.key_enc, tag, iv,
num_rounds(&ctx->aes_key));
put_unaligned_be32(2, iv + GCM_IV_SIZE);
err = skcipher_walk_aead_encrypt(&walk, req, false);
while (walk.nbytes >= AES_BLOCK_SIZE) {
int blocks = walk.nbytes / AES_BLOCK_SIZE;
u8 *dst = walk.dst.virt.addr;
u8 *src = walk.src.virt.addr;
do {
__aes_arm64_encrypt(ctx->aes_key.key_enc,
ks, iv,
num_rounds(&ctx->aes_key));
crypto_xor_cpy(dst, src, ks, AES_BLOCK_SIZE);
crypto_inc(iv, AES_BLOCK_SIZE);
dst += AES_BLOCK_SIZE;
src += AES_BLOCK_SIZE;
} while (--blocks > 0);
ghash_do_update(walk.nbytes / AES_BLOCK_SIZE, dg,
walk.dst.virt.addr, &ctx->ghash_key,
NULL);
err = skcipher_walk_done(&walk,
walk.nbytes % AES_BLOCK_SIZE);
}
if (walk.nbytes)
__aes_arm64_encrypt(ctx->aes_key.key_enc, ks, iv,
num_rounds(&ctx->aes_key));
}
/* handle the tail */
if (walk.nbytes) {
u8 buf[GHASH_BLOCK_SIZE];
crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, ks,
walk.nbytes);
memcpy(buf, walk.dst.virt.addr, walk.nbytes);
memset(buf + walk.nbytes, 0, GHASH_BLOCK_SIZE - walk.nbytes);
ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL);
err = skcipher_walk_done(&walk, 0);
}
if (err)
return err;
gcm_final(req, ctx, dg, tag, req->cryptlen);
/* copy authtag to end of dst */
scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen,
crypto_aead_authsize(aead), 1);
return 0;
}
static int gcm_decrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
unsigned int authsize = crypto_aead_authsize(aead);
struct skcipher_walk walk;
u8 iv[AES_BLOCK_SIZE];
u8 tag[AES_BLOCK_SIZE];
u8 buf[GHASH_BLOCK_SIZE];
u64 dg[2] = {};
int err;
if (req->assoclen)
gcm_calculate_auth_mac(req, dg);
memcpy(iv, req->iv, GCM_IV_SIZE);
put_unaligned_be32(1, iv + GCM_IV_SIZE);
if (likely(may_use_simd())) {
kernel_neon_begin();
pmull_gcm_encrypt_block(tag, iv, ctx->aes_key.key_enc,
num_rounds(&ctx->aes_key));
put_unaligned_be32(2, iv + GCM_IV_SIZE);
kernel_neon_end();
err = skcipher_walk_aead_decrypt(&walk, req, false);
while (walk.nbytes >= AES_BLOCK_SIZE) {
int blocks = walk.nbytes / AES_BLOCK_SIZE;
kernel_neon_begin();
pmull_gcm_decrypt(blocks, dg, walk.dst.virt.addr,
walk.src.virt.addr, &ctx->ghash_key,
iv, ctx->aes_key.key_enc,
num_rounds(&ctx->aes_key));
kernel_neon_end();
err = skcipher_walk_done(&walk,
walk.nbytes % AES_BLOCK_SIZE);
}
if (walk.nbytes) {
kernel_neon_begin();
pmull_gcm_encrypt_block(iv, iv, ctx->aes_key.key_enc,
num_rounds(&ctx->aes_key));
kernel_neon_end();
}
} else {
__aes_arm64_encrypt(ctx->aes_key.key_enc, tag, iv,
num_rounds(&ctx->aes_key));
put_unaligned_be32(2, iv + GCM_IV_SIZE);
err = skcipher_walk_aead_decrypt(&walk, req, false);
while (walk.nbytes >= AES_BLOCK_SIZE) {
int blocks = walk.nbytes / AES_BLOCK_SIZE;
u8 *dst = walk.dst.virt.addr;
u8 *src = walk.src.virt.addr;
ghash_do_update(blocks, dg, walk.src.virt.addr,
&ctx->ghash_key, NULL);
do {
__aes_arm64_encrypt(ctx->aes_key.key_enc,
buf, iv,
num_rounds(&ctx->aes_key));
crypto_xor_cpy(dst, src, buf, AES_BLOCK_SIZE);
crypto_inc(iv, AES_BLOCK_SIZE);
dst += AES_BLOCK_SIZE;
src += AES_BLOCK_SIZE;
} while (--blocks > 0);
err = skcipher_walk_done(&walk,
walk.nbytes % AES_BLOCK_SIZE);
}
if (walk.nbytes)
__aes_arm64_encrypt(ctx->aes_key.key_enc, iv, iv,
num_rounds(&ctx->aes_key));
}
/* handle the tail */
if (walk.nbytes) {
memcpy(buf, walk.src.virt.addr, walk.nbytes);
memset(buf + walk.nbytes, 0, GHASH_BLOCK_SIZE - walk.nbytes);
ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL);
crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, iv,
walk.nbytes);
err = skcipher_walk_done(&walk, 0);
}
if (err)
return err;
gcm_final(req, ctx, dg, tag, req->cryptlen - authsize);
/* compare calculated auth tag with the stored one */
scatterwalk_map_and_copy(buf, req->src,
req->assoclen + req->cryptlen - authsize,
authsize, 0);
if (crypto_memneq(tag, buf, authsize))
return -EBADMSG;
return 0;
}
static struct aead_alg gcm_aes_alg = {
.ivsize = GCM_IV_SIZE,
.chunksize = AES_BLOCK_SIZE,
.maxauthsize = AES_BLOCK_SIZE,
.setkey = gcm_setkey,
.setauthsize = gcm_setauthsize,
.encrypt = gcm_encrypt,
.decrypt = gcm_decrypt,
.base.cra_name = "gcm(aes)",
.base.cra_driver_name = "gcm-aes-ce",
.base.cra_priority = 300,
.base.cra_blocksize = 1,
.base.cra_ctxsize = sizeof(struct gcm_aes_ctx),
.base.cra_module = THIS_MODULE,
};
static int __init ghash_ce_mod_init(void)
{
int ret;
if (!(elf_hwcap & HWCAP_ASIMD))
return -ENODEV;
if (elf_hwcap & HWCAP_PMULL)
pmull_ghash_update = pmull_ghash_update_p64;
else
pmull_ghash_update = pmull_ghash_update_p8;
ret = crypto_register_shash(&ghash_alg);
if (ret)
return ret;
if (elf_hwcap & HWCAP_PMULL) {
ret = crypto_register_aead(&gcm_aes_alg);
if (ret)
crypto_unregister_shash(&ghash_alg);
}
return ret;
}
static void __exit ghash_ce_mod_exit(void)
{
crypto_unregister_shash(&ghash_alg);
crypto_unregister_aead(&gcm_aes_alg);
}
static const struct cpu_feature ghash_cpu_feature[] = {
{ cpu_feature(PMULL) }, { }
};
MODULE_DEVICE_TABLE(cpu, ghash_cpu_feature);
module_init(ghash_ce_mod_init);
module_exit(ghash_ce_mod_exit);