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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* SM4-GCM AEAD Algorithm using ARMv8 Crypto Extensions
* as specified in rfc8998
* https://datatracker.ietf.org/doc/html/rfc8998
*
* Copyright (C) 2022 Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
*/
#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/cpufeature.h>
#include <asm/neon.h>
#include <crypto/b128ops.h>
#include <crypto/scatterwalk.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/sm4.h>
#include "sm4-ce.h"
asmlinkage void sm4_ce_pmull_ghash_setup(const u32 *rkey_enc, u8 *ghash_table);
asmlinkage void pmull_ghash_update(const u8 *ghash_table, u8 *ghash,
const u8 *src, unsigned int nblocks);
asmlinkage void sm4_ce_pmull_gcm_enc(const u32 *rkey_enc, u8 *dst,
const u8 *src, u8 *iv,
unsigned int nbytes, u8 *ghash,
const u8 *ghash_table, const u8 *lengths);
asmlinkage void sm4_ce_pmull_gcm_dec(const u32 *rkey_enc, u8 *dst,
const u8 *src, u8 *iv,
unsigned int nbytes, u8 *ghash,
const u8 *ghash_table, const u8 *lengths);
#define GHASH_BLOCK_SIZE 16
#define GCM_IV_SIZE 12
struct sm4_gcm_ctx {
struct sm4_ctx key;
u8 ghash_table[16 * 4];
};
static int gcm_setkey(struct crypto_aead *tfm, const u8 *key,
unsigned int key_len)
{
struct sm4_gcm_ctx *ctx = crypto_aead_ctx(tfm);
if (key_len != SM4_KEY_SIZE)
return -EINVAL;
kernel_neon_begin();
sm4_ce_expand_key(key, ctx->key.rkey_enc, ctx->key.rkey_dec,
crypto_sm4_fk, crypto_sm4_ck);
sm4_ce_pmull_ghash_setup(ctx->key.rkey_enc, ctx->ghash_table);
kernel_neon_end();
return 0;
}
static int gcm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
switch (authsize) {
case 4:
case 8:
case 12 ... 16:
return 0;
default:
return -EINVAL;
}
}
static void gcm_calculate_auth_mac(struct aead_request *req, u8 ghash[])
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead);
u8 __aligned(8) buffer[GHASH_BLOCK_SIZE];
u32 assoclen = req->assoclen;
struct scatter_walk walk;
unsigned int buflen = 0;
scatterwalk_start(&walk, req->src);
do {
u32 n = scatterwalk_clamp(&walk, assoclen);
u8 *p, *ptr;
if (!n) {
scatterwalk_start(&walk, sg_next(walk.sg));
n = scatterwalk_clamp(&walk, assoclen);
}
p = ptr = scatterwalk_map(&walk);
assoclen -= n;
scatterwalk_advance(&walk, n);
if (n + buflen < GHASH_BLOCK_SIZE) {
memcpy(&buffer[buflen], ptr, n);
buflen += n;
} else {
unsigned int nblocks;
if (buflen) {
unsigned int l = GHASH_BLOCK_SIZE - buflen;
memcpy(&buffer[buflen], ptr, l);
ptr += l;
n -= l;
pmull_ghash_update(ctx->ghash_table, ghash,
buffer, 1);
}
nblocks = n / GHASH_BLOCK_SIZE;
if (nblocks) {
pmull_ghash_update(ctx->ghash_table, ghash,
ptr, nblocks);
ptr += nblocks * GHASH_BLOCK_SIZE;
}
buflen = n % GHASH_BLOCK_SIZE;
if (buflen)
memcpy(&buffer[0], ptr, buflen);
}
scatterwalk_unmap(p);
scatterwalk_done(&walk, 0, assoclen);
} while (assoclen);
/* padding with '0' */
if (buflen) {
memset(&buffer[buflen], 0, GHASH_BLOCK_SIZE - buflen);
pmull_ghash_update(ctx->ghash_table, ghash, buffer, 1);
}
}
static int gcm_crypt(struct aead_request *req, struct skcipher_walk *walk,
struct sm4_gcm_ctx *ctx, u8 ghash[],
void (*sm4_ce_pmull_gcm_crypt)(const u32 *rkey_enc,
u8 *dst, const u8 *src, u8 *iv,
unsigned int nbytes, u8 *ghash,
const u8 *ghash_table, const u8 *lengths))
{
u8 __aligned(8) iv[SM4_BLOCK_SIZE];
be128 __aligned(8) lengths;
int err;
memset(ghash, 0, SM4_BLOCK_SIZE);
lengths.a = cpu_to_be64(req->assoclen * 8);
lengths.b = cpu_to_be64(walk->total * 8);
memcpy(iv, walk->iv, GCM_IV_SIZE);
put_unaligned_be32(2, iv + GCM_IV_SIZE);
kernel_neon_begin();
if (req->assoclen)
gcm_calculate_auth_mac(req, ghash);
do {
unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE;
const u8 *src = walk->src.virt.addr;
u8 *dst = walk->dst.virt.addr;
if (walk->nbytes == walk->total) {
tail = 0;
sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, dst, src, iv,
walk->nbytes, ghash,
ctx->ghash_table,
(const u8 *)&lengths);
} else if (walk->nbytes - tail) {
sm4_ce_pmull_gcm_crypt(ctx->key.rkey_enc, dst, src, iv,
walk->nbytes - tail, ghash,
ctx->ghash_table, NULL);
}
kernel_neon_end();
err = skcipher_walk_done(walk, tail);
if (err)
return err;
if (walk->nbytes)
kernel_neon_begin();
} while (walk->nbytes > 0);
return 0;
}
static int gcm_encrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead);
u8 __aligned(8) ghash[SM4_BLOCK_SIZE];
struct skcipher_walk walk;
int err;
err = skcipher_walk_aead_encrypt(&walk, req, false);
if (err)
return err;
err = gcm_crypt(req, &walk, ctx, ghash, sm4_ce_pmull_gcm_enc);
if (err)
return err;
/* copy authtag to end of dst */
scatterwalk_map_and_copy(ghash, 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);
unsigned int authsize = crypto_aead_authsize(aead);
struct sm4_gcm_ctx *ctx = crypto_aead_ctx(aead);
u8 __aligned(8) ghash[SM4_BLOCK_SIZE];
u8 authtag[SM4_BLOCK_SIZE];
struct skcipher_walk walk;
int err;
err = skcipher_walk_aead_decrypt(&walk, req, false);
if (err)
return err;
err = gcm_crypt(req, &walk, ctx, ghash, sm4_ce_pmull_gcm_dec);
if (err)
return err;
/* compare calculated auth tag with the stored one */
scatterwalk_map_and_copy(authtag, req->src,
req->assoclen + req->cryptlen - authsize,
authsize, 0);
if (crypto_memneq(authtag, ghash, authsize))
return -EBADMSG;
return 0;
}
static struct aead_alg sm4_gcm_alg = {
.base = {
.cra_name = "gcm(sm4)",
.cra_driver_name = "gcm-sm4-ce",
.cra_priority = 400,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct sm4_gcm_ctx),
.cra_module = THIS_MODULE,
},
.ivsize = GCM_IV_SIZE,
.chunksize = SM4_BLOCK_SIZE,
.maxauthsize = SM4_BLOCK_SIZE,
.setkey = gcm_setkey,
.setauthsize = gcm_setauthsize,
.encrypt = gcm_encrypt,
.decrypt = gcm_decrypt,
};
static int __init sm4_ce_gcm_init(void)
{
if (!cpu_have_named_feature(PMULL))
return -ENODEV;
return crypto_register_aead(&sm4_gcm_alg);
}
static void __exit sm4_ce_gcm_exit(void)
{
crypto_unregister_aead(&sm4_gcm_alg);
}
static const struct cpu_feature __maybe_unused sm4_ce_gcm_cpu_feature[] = {
{ cpu_feature(PMULL) },
{}
};
MODULE_DEVICE_TABLE(cpu, sm4_ce_gcm_cpu_feature);
module_cpu_feature_match(SM4, sm4_ce_gcm_init);
module_exit(sm4_ce_gcm_exit);
MODULE_DESCRIPTION("Synchronous SM4 in GCM mode using ARMv8 Crypto Extensions");
MODULE_ALIAS_CRYPTO("gcm(sm4)");
MODULE_AUTHOR("Tianjia Zhang <tianjia.zhang@linux.alibaba.com>");
MODULE_LICENSE("GPL v2");
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