2 * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
4 * Copyright (C) 2013 - 2014 Linaro Ltd <ard.biesheuvel@linaro.org>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
12 #include <asm/unaligned.h>
13 #include <crypto/aes.h>
14 #include <crypto/scatterwalk.h>
15 #include <crypto/internal/aead.h>
16 #include <crypto/internal/skcipher.h>
17 #include <linux/module.h>
19 #include "aes-ce-setkey.h"
21 static int num_rounds(struct crypto_aes_ctx *ctx)
24 * # of rounds specified by AES:
25 * 128 bit key 10 rounds
26 * 192 bit key 12 rounds
27 * 256 bit key 14 rounds
28 * => n byte key => 6 + (n/4) rounds
30 return 6 + ctx->key_length / 4;
33 asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
34 u32 *macp, u32 const rk[], u32 rounds);
36 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
37 u32 const rk[], u32 rounds, u8 mac[],
40 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
41 u32 const rk[], u32 rounds, u8 mac[],
44 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
47 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
50 struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
53 ret = ce_aes_expandkey(ctx, in_key, key_len);
57 tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
61 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
63 if ((authsize & 1) || authsize < 4)
68 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
70 struct crypto_aead *aead = crypto_aead_reqtfm(req);
71 __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
72 u32 l = req->iv[0] + 1;
74 /* verify that CCM dimension 'L' is set correctly in the IV */
78 /* verify that msglen can in fact be represented in L bytes */
79 if (l < 4 && msglen >> (8 * l))
83 * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
84 * uses a u32 type to represent msglen so the top 4 bytes are always 0.
87 n[1] = cpu_to_be32(msglen);
89 memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
92 * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
93 * - bits 0..2 : max # of bytes required to represent msglen, minus 1
94 * (already set by caller)
95 * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
96 * - bit 6 : indicates presence of authenticate-only data
98 maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
102 memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
106 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
108 struct crypto_aead *aead = crypto_aead_reqtfm(req);
109 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
110 struct __packed { __be16 l; __be32 h; u16 len; } ltag;
111 struct scatter_walk walk;
112 u32 len = req->assoclen;
115 /* prepend the AAD with a length tag */
117 ltag.l = cpu_to_be16(len);
120 ltag.l = cpu_to_be16(0xfffe);
121 put_unaligned_be32(len, <ag.h);
125 ce_aes_ccm_auth_data(mac, (u8 *)<ag, ltag.len, &macp, ctx->key_enc,
127 scatterwalk_start(&walk, req->src);
130 u32 n = scatterwalk_clamp(&walk, len);
134 scatterwalk_start(&walk, sg_next(walk.sg));
135 n = scatterwalk_clamp(&walk, len);
137 p = scatterwalk_map(&walk);
138 ce_aes_ccm_auth_data(mac, p, n, &macp, ctx->key_enc,
142 scatterwalk_unmap(p);
143 scatterwalk_advance(&walk, n);
144 scatterwalk_done(&walk, 0, len);
148 static int ccm_encrypt(struct aead_request *req)
150 struct crypto_aead *aead = crypto_aead_reqtfm(req);
151 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
152 struct skcipher_walk walk;
153 u8 __aligned(8) mac[AES_BLOCK_SIZE];
154 u8 buf[AES_BLOCK_SIZE];
155 u32 len = req->cryptlen;
158 err = ccm_init_mac(req, mac, len);
162 kernel_neon_begin_partial(6);
165 ccm_calculate_auth_mac(req, mac);
167 /* preserve the original iv for the final round */
168 memcpy(buf, req->iv, AES_BLOCK_SIZE);
170 err = skcipher_walk_aead_encrypt(&walk, req, true);
172 while (walk.nbytes) {
173 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
175 if (walk.nbytes == walk.total)
178 ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
179 walk.nbytes - tail, ctx->key_enc,
180 num_rounds(ctx), mac, walk.iv);
182 err = skcipher_walk_done(&walk, tail);
185 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
192 /* copy authtag to end of dst */
193 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
194 crypto_aead_authsize(aead), 1);
199 static int ccm_decrypt(struct aead_request *req)
201 struct crypto_aead *aead = crypto_aead_reqtfm(req);
202 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
203 unsigned int authsize = crypto_aead_authsize(aead);
204 struct skcipher_walk walk;
205 u8 __aligned(8) mac[AES_BLOCK_SIZE];
206 u8 buf[AES_BLOCK_SIZE];
207 u32 len = req->cryptlen - authsize;
210 err = ccm_init_mac(req, mac, len);
214 kernel_neon_begin_partial(6);
217 ccm_calculate_auth_mac(req, mac);
219 /* preserve the original iv for the final round */
220 memcpy(buf, req->iv, AES_BLOCK_SIZE);
222 err = skcipher_walk_aead_decrypt(&walk, req, true);
224 while (walk.nbytes) {
225 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
227 if (walk.nbytes == walk.total)
230 ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
231 walk.nbytes - tail, ctx->key_enc,
232 num_rounds(ctx), mac, walk.iv);
234 err = skcipher_walk_done(&walk, tail);
237 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
244 /* compare calculated auth tag with the stored one */
245 scatterwalk_map_and_copy(buf, req->src,
246 req->assoclen + req->cryptlen - authsize,
249 if (crypto_memneq(mac, buf, authsize))
254 static struct aead_alg ccm_aes_alg = {
256 .cra_name = "ccm(aes)",
257 .cra_driver_name = "ccm-aes-ce",
260 .cra_ctxsize = sizeof(struct crypto_aes_ctx),
262 .cra_module = THIS_MODULE,
264 .ivsize = AES_BLOCK_SIZE,
265 .chunksize = AES_BLOCK_SIZE,
266 .maxauthsize = AES_BLOCK_SIZE,
267 .setkey = ccm_setkey,
268 .setauthsize = ccm_setauthsize,
269 .encrypt = ccm_encrypt,
270 .decrypt = ccm_decrypt,
273 static int __init aes_mod_init(void)
275 if (!(elf_hwcap & HWCAP_AES))
277 return crypto_register_aead(&ccm_aes_alg);
280 static void __exit aes_mod_exit(void)
282 crypto_unregister_aead(&ccm_aes_alg);
285 module_init(aes_mod_init);
286 module_exit(aes_mod_exit);
288 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
289 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
290 MODULE_LICENSE("GPL v2");
291 MODULE_ALIAS_CRYPTO("ccm(aes)");