/*
* aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
*
* Copyright (C) 2013 - 2014 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/unaligned.h>
#include <crypto/aes.h>
#include <crypto/algapi.h>
#include <crypto/scatterwalk.h>
#include <linux/crypto.h>
#include <linux/module.h>
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;
}
asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
u32 *macp, u32 const rk[], u32 rounds);
asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
u32 const rk[], u32 rounds, u8 mac[],
u8 ctr[]);
asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
u32 const rk[], u32 rounds, u8 mac[],
u8 ctr[]);
asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
u32 rounds);
static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
unsigned int key_len)
{
struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
int ret;
ret = crypto_aes_expand_key(ctx, in_key, key_len);
if (!ret)
return 0;
tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
return -EINVAL;
}
static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
if ((authsize & 1) || authsize < 4)
return -EINVAL;
return 0;
}
static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
__be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
u32 l = req->iv[0] + 1;
/* verify that CCM dimension 'L' is set correctly in the IV */
if (l < 2 || l > 8)
return -EINVAL;
/* verify that msglen can in fact be represented in L bytes */
if (l < 4 && msglen >> (8 * l))
return -EOVERFLOW;
/*
* Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
* uses a u32 type to represent msglen so the top 4 bytes are always 0.
*/
n[0] = 0;
n[1] = cpu_to_be32(msglen);
memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
/*
* Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
* - bits 0..2 : max # of bytes required to represent msglen, minus 1
* (already set by caller)
* - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
* - bit 6 : indicates presence of authenticate-only data
*/
maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
if (req->assoclen)
maciv[0] |= 0x40;
memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
return 0;
}
static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
struct __packed { __be16 l; __be32 h; u16 len; } ltag;
struct scatter_walk walk;
u32 len = req->assoclen;
u32 macp = 0;
/* prepend the AAD with a length tag */
if (len < 0xff00) {
ltag.l = cpu_to_be16(len);
ltag.len = 2;
} else {
ltag.l = cpu_to_be16(0xfffe);
put_unaligned_be32(len, <ag.h);
ltag.len = 6;
}
ce_aes_ccm_auth_data(mac, (u8 *)<ag, ltag.len, &macp, ctx->key_enc,
num_rounds(ctx));
scatterwalk_start(&walk, req->assoc);
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);
ce_aes_ccm_auth_data(mac, p, n, &macp, ctx->key_enc,
num_rounds(ctx));
len -= n;
scatterwalk_unmap(p);
scatterwalk_advance(&walk, n);
scatterwalk_done(&walk, 0, len);
} while (len);
}
static int ccm_encrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
struct blkcipher_desc desc = { .info = req->iv };
struct blkcipher_walk walk;
u8 __aligned(8) mac[AES_BLOCK_SIZE];
u8 buf[AES_BLOCK_SIZE];
u32 len = req->cryptlen;
int err;
err = ccm_init_mac(req, mac, len);
if (err)
return err;
kernel_neon_begin_partial(6);
if (req->assoclen)
ccm_calculate_auth_mac(req, mac);
/* preserve the original iv for the final round */
memcpy(buf, req->iv, AES_BLOCK_SIZE);
blkcipher_walk_init(&walk, req->dst, req->src, len);
err = blkcipher_aead_walk_virt_block(&desc, &walk, aead,
AES_BLOCK_SIZE);
while (walk.nbytes) {
u32 tail = walk.nbytes % AES_BLOCK_SIZE;
if (walk.nbytes == len)
tail = 0;
ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
walk.nbytes - tail, ctx->key_enc,
num_rounds(ctx), mac, walk.iv);
len -= walk.nbytes - tail;
err = blkcipher_walk_done(&desc, &walk, tail);
}
if (!err)
ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
kernel_neon_end();
if (err)
return err;
/* copy authtag to end of dst */
scatterwalk_map_and_copy(mac, req->dst, 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);
struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
unsigned int authsize = crypto_aead_authsize(aead);
struct blkcipher_desc desc = { .info = req->iv };
struct blkcipher_walk walk;
u8 __aligned(8) mac[AES_BLOCK_SIZE];
u8 buf[AES_BLOCK_SIZE];
u32 len = req->cryptlen - authsize;
int err;
err = ccm_init_mac(req, mac, len);
if (err)
return err;
kernel_neon_begin_partial(6);
if (req->assoclen)
ccm_calculate_auth_mac(req, mac);
/* preserve the original iv for the final round */
memcpy(buf, req->iv, AES_BLOCK_SIZE);
blkcipher_walk_init(&walk, req->dst, req->src, len);
err = blkcipher_aead_walk_virt_block(&desc, &walk, aead,
AES_BLOCK_SIZE);
while (walk.nbytes) {
u32 tail = walk.nbytes % AES_BLOCK_SIZE;
if (walk.nbytes == len)
tail = 0;
ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
walk.nbytes - tail, ctx->key_enc,
num_rounds(ctx), mac, walk.iv);
len -= walk.nbytes - tail;
err = blkcipher_walk_done(&desc, &walk, tail);
}
if (!err)
ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
kernel_neon_end();
if (err)
return err;
/* compare calculated auth tag with the stored one */
scatterwalk_map_and_copy(buf, req->src, req->cryptlen - authsize,
authsize, 0);
if (memcmp(mac, buf, authsize))
return -EBADMSG;
return 0;
}
static struct crypto_alg ccm_aes_alg = {
.cra_name = "ccm(aes)",
.cra_driver_name = "ccm-aes-ce",
.cra_priority = 300,
.cra_flags = CRYPTO_ALG_TYPE_AEAD,
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct crypto_aes_ctx),
.cra_alignmask = 7,
.cra_type = &crypto_aead_type,
.cra_module = THIS_MODULE,
.cra_aead = {
.ivsize = AES_BLOCK_SIZE,
.maxauthsize = AES_BLOCK_SIZE,
.setkey = ccm_setkey,
.setauthsize = ccm_setauthsize,
.encrypt = ccm_encrypt,
.decrypt = ccm_decrypt,
}
};
static int __init aes_mod_init(void)
{
if (!(elf_hwcap & HWCAP_AES))
return -ENODEV;
return crypto_register_alg(&ccm_aes_alg);
}
static void __exit aes_mod_exit(void)
{
crypto_unregister_alg(&ccm_aes_alg);
}
module_init(aes_mod_init);
module_exit(aes_mod_exit);
MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("ccm(aes)");