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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* SM4-CCM 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/scatterwalk.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/sm4.h>
#include "sm4-ce.h"
asmlinkage void sm4_ce_cbcmac_update(const u32 *rkey_enc, u8 *mac,
const u8 *src, unsigned int nblocks);
asmlinkage void sm4_ce_ccm_enc(const u32 *rkey_enc, u8 *dst, const u8 *src,
u8 *iv, unsigned int nbytes, u8 *mac);
asmlinkage void sm4_ce_ccm_dec(const u32 *rkey_enc, u8 *dst, const u8 *src,
u8 *iv, unsigned int nbytes, u8 *mac);
asmlinkage void sm4_ce_ccm_final(const u32 *rkey_enc, u8 *iv, u8 *mac);
static int ccm_setkey(struct crypto_aead *tfm, const u8 *key,
unsigned int key_len)
{
struct sm4_ctx *ctx = crypto_aead_ctx(tfm);
if (key_len != SM4_KEY_SIZE)
return -EINVAL;
kernel_neon_begin();
sm4_ce_expand_key(key, ctx->rkey_enc, ctx->rkey_dec,
crypto_sm4_fk, crypto_sm4_ck);
kernel_neon_end();
return 0;
}
static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
if ((authsize & 1) || authsize < 4)
return -EINVAL;
return 0;
}
static int ccm_format_input(u8 info[], struct aead_request *req,
unsigned int msglen)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
unsigned int l = req->iv[0] + 1;
unsigned int m;
__be32 len;
/* verify that CCM dimension 'L': 2 <= L <= 8 */
if (l < 2 || l > 8)
return -EINVAL;
if (l < 4 && msglen >> (8 * l))
return -EOVERFLOW;
memset(&req->iv[SM4_BLOCK_SIZE - l], 0, l);
memcpy(info, req->iv, SM4_BLOCK_SIZE);
m = crypto_aead_authsize(aead);
/* format flags field per RFC 3610/NIST 800-38C */
*info |= ((m - 2) / 2) << 3;
if (req->assoclen)
*info |= (1 << 6);
/*
* format message length field,
* Linux uses a u32 type to represent msglen
*/
if (l >= 4)
l = 4;
len = cpu_to_be32(msglen);
memcpy(&info[SM4_BLOCK_SIZE - l], (u8 *)&len + 4 - l, l);
return 0;
}
static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct sm4_ctx *ctx = crypto_aead_ctx(aead);
struct __packed { __be16 l; __be32 h; } aadlen;
u32 assoclen = req->assoclen;
struct scatter_walk walk;
unsigned int len;
if (assoclen < 0xff00) {
aadlen.l = cpu_to_be16(assoclen);
len = 2;
} else {
aadlen.l = cpu_to_be16(0xfffe);
put_unaligned_be32(assoclen, &aadlen.h);
len = 6;
}
sm4_ce_crypt_block(ctx->rkey_enc, mac, mac);
crypto_xor(mac, (const u8 *)&aadlen, len);
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);
while (n > 0) {
unsigned int l, nblocks;
if (len == SM4_BLOCK_SIZE) {
if (n < SM4_BLOCK_SIZE) {
sm4_ce_crypt_block(ctx->rkey_enc,
mac, mac);
len = 0;
} else {
nblocks = n / SM4_BLOCK_SIZE;
sm4_ce_cbcmac_update(ctx->rkey_enc,
mac, ptr, nblocks);
ptr += nblocks * SM4_BLOCK_SIZE;
n %= SM4_BLOCK_SIZE;
continue;
}
}
l = min(n, SM4_BLOCK_SIZE - len);
if (l) {
crypto_xor(mac + len, ptr, l);
len += l;
ptr += l;
n -= l;
}
}
scatterwalk_unmap(p);
scatterwalk_done(&walk, 0, assoclen);
} while (assoclen);
}
static int ccm_crypt(struct aead_request *req, struct skcipher_walk *walk,
u32 *rkey_enc, u8 mac[],
void (*sm4_ce_ccm_crypt)(const u32 *rkey_enc, u8 *dst,
const u8 *src, u8 *iv,
unsigned int nbytes, u8 *mac))
{
u8 __aligned(8) ctr0[SM4_BLOCK_SIZE];
int err = 0;
/* preserve the initial ctr0 for the TAG */
memcpy(ctr0, walk->iv, SM4_BLOCK_SIZE);
crypto_inc(walk->iv, SM4_BLOCK_SIZE);
kernel_neon_begin();
if (req->assoclen)
ccm_calculate_auth_mac(req, mac);
while (walk->nbytes && walk->nbytes != walk->total) {
unsigned int tail = walk->nbytes % SM4_BLOCK_SIZE;
sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr,
walk->src.virt.addr, walk->iv,
walk->nbytes - tail, mac);
kernel_neon_end();
err = skcipher_walk_done(walk, tail);
kernel_neon_begin();
}
if (walk->nbytes) {
sm4_ce_ccm_crypt(rkey_enc, walk->dst.virt.addr,
walk->src.virt.addr, walk->iv,
walk->nbytes, mac);
sm4_ce_ccm_final(rkey_enc, ctr0, mac);
kernel_neon_end();
err = skcipher_walk_done(walk, 0);
} else {
sm4_ce_ccm_final(rkey_enc, ctr0, mac);
kernel_neon_end();
}
return err;
}
static int ccm_encrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct sm4_ctx *ctx = crypto_aead_ctx(aead);
u8 __aligned(8) mac[SM4_BLOCK_SIZE];
struct skcipher_walk walk;
int err;
err = ccm_format_input(mac, req, req->cryptlen);
if (err)
return err;
err = skcipher_walk_aead_encrypt(&walk, req, false);
if (err)
return err;
err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_enc);
if (err)
return err;
/* copy authtag to end of dst */
scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
crypto_aead_authsize(aead), 1);
return 0;
}
static int ccm_decrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
unsigned int authsize = crypto_aead_authsize(aead);
struct sm4_ctx *ctx = crypto_aead_ctx(aead);
u8 __aligned(8) mac[SM4_BLOCK_SIZE];
u8 authtag[SM4_BLOCK_SIZE];
struct skcipher_walk walk;
int err;
err = ccm_format_input(mac, req, req->cryptlen - authsize);
if (err)
return err;
err = skcipher_walk_aead_decrypt(&walk, req, false);
if (err)
return err;
err = ccm_crypt(req, &walk, ctx->rkey_enc, mac, sm4_ce_ccm_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, mac, authsize))
return -EBADMSG;
return 0;
}
static struct aead_alg sm4_ccm_alg = {
.base = {
.cra_name = "ccm(sm4)",
.cra_driver_name = "ccm-sm4-ce",
.cra_priority = 400,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct sm4_ctx),
.cra_module = THIS_MODULE,
},
.ivsize = SM4_BLOCK_SIZE,
.chunksize = SM4_BLOCK_SIZE,
.maxauthsize = SM4_BLOCK_SIZE,
.setkey = ccm_setkey,
.setauthsize = ccm_setauthsize,
.encrypt = ccm_encrypt,
.decrypt = ccm_decrypt,
};
static int __init sm4_ce_ccm_init(void)
{
return crypto_register_aead(&sm4_ccm_alg);
}
static void __exit sm4_ce_ccm_exit(void)
{
crypto_unregister_aead(&sm4_ccm_alg);
}
module_cpu_feature_match(SM4, sm4_ce_ccm_init);
module_exit(sm4_ce_ccm_exit);
MODULE_DESCRIPTION("Synchronous SM4 in CCM mode using ARMv8 Crypto Extensions");
MODULE_ALIAS_CRYPTO("ccm(sm4)");
MODULE_AUTHOR("Tianjia Zhang <tianjia.zhang@linux.alibaba.com>");
MODULE_LICENSE("GPL v2");
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