1 // SPDX-License-Identifier: GPL-2.0-only
3 * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
5 * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
9 #include <asm/unaligned.h>
10 #include <crypto/aes.h>
11 #include <crypto/scatterwalk.h>
12 #include <crypto/internal/aead.h>
13 #include <crypto/internal/skcipher.h>
14 #include <linux/module.h>
16 #include "aes-ce-setkey.h"
18 static int num_rounds(struct crypto_aes_ctx *ctx)
21 * # of rounds specified by AES:
22 * 128 bit key 10 rounds
23 * 192 bit key 12 rounds
24 * 256 bit key 14 rounds
25 * => n byte key => 6 + (n/4) rounds
27 return 6 + ctx->key_length / 4;
30 asmlinkage u32 ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
31 u32 macp, u32 const rk[], u32 rounds);
33 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
34 u32 const rk[], u32 rounds, u8 mac[],
37 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
38 u32 const rk[], u32 rounds, u8 mac[],
41 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
44 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
47 struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
49 return ce_aes_expandkey(ctx, in_key, key_len);
52 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
54 if ((authsize & 1) || authsize < 4)
59 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
61 struct crypto_aead *aead = crypto_aead_reqtfm(req);
62 __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
63 u32 l = req->iv[0] + 1;
65 /* verify that CCM dimension 'L' is set correctly in the IV */
69 /* verify that msglen can in fact be represented in L bytes */
70 if (l < 4 && msglen >> (8 * l))
74 * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
75 * uses a u32 type to represent msglen so the top 4 bytes are always 0.
78 n[1] = cpu_to_be32(msglen);
80 memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
83 * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
84 * - bits 0..2 : max # of bytes required to represent msglen, minus 1
85 * (already set by caller)
86 * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
87 * - bit 6 : indicates presence of authenticate-only data
89 maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
93 memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
97 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
99 struct crypto_aead *aead = crypto_aead_reqtfm(req);
100 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
101 struct __packed { __be16 l; __be32 h; u16 len; } ltag;
102 struct scatter_walk walk;
103 u32 len = req->assoclen;
106 /* prepend the AAD with a length tag */
108 ltag.l = cpu_to_be16(len);
111 ltag.l = cpu_to_be16(0xfffe);
112 put_unaligned_be32(len, <ag.h);
116 macp = ce_aes_ccm_auth_data(mac, (u8 *)<ag, ltag.len, macp,
117 ctx->key_enc, num_rounds(ctx));
118 scatterwalk_start(&walk, req->src);
121 u32 n = scatterwalk_clamp(&walk, len);
125 scatterwalk_start(&walk, sg_next(walk.sg));
126 n = scatterwalk_clamp(&walk, len);
128 n = min_t(u32, n, SZ_4K); /* yield NEON at least every 4k */
129 p = scatterwalk_map(&walk);
131 macp = ce_aes_ccm_auth_data(mac, p, n, macp, ctx->key_enc,
134 if (len / SZ_4K > (len - n) / SZ_4K) {
140 scatterwalk_unmap(p);
141 scatterwalk_advance(&walk, n);
142 scatterwalk_done(&walk, 0, len);
146 static int ccm_encrypt(struct aead_request *req)
148 struct crypto_aead *aead = crypto_aead_reqtfm(req);
149 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
150 struct skcipher_walk walk;
151 u8 __aligned(8) mac[AES_BLOCK_SIZE];
152 u8 buf[AES_BLOCK_SIZE];
153 u32 len = req->cryptlen;
156 err = ccm_init_mac(req, mac, len);
160 /* preserve the original iv for the final round */
161 memcpy(buf, req->iv, AES_BLOCK_SIZE);
163 err = skcipher_walk_aead_encrypt(&walk, req, false);
170 ccm_calculate_auth_mac(req, mac);
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 if (walk.nbytes == walk.total)
183 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
188 err = skcipher_walk_done(&walk, tail);
191 if (unlikely(walk.nbytes))
194 } while (walk.nbytes);
196 /* copy authtag to end of dst */
197 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
198 crypto_aead_authsize(aead), 1);
203 static int ccm_decrypt(struct aead_request *req)
205 struct crypto_aead *aead = crypto_aead_reqtfm(req);
206 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
207 unsigned int authsize = crypto_aead_authsize(aead);
208 struct skcipher_walk walk;
209 u8 __aligned(8) mac[AES_BLOCK_SIZE];
210 u8 buf[AES_BLOCK_SIZE];
211 u32 len = req->cryptlen - authsize;
214 err = ccm_init_mac(req, mac, len);
218 /* preserve the original iv for the final round */
219 memcpy(buf, req->iv, AES_BLOCK_SIZE);
221 err = skcipher_walk_aead_decrypt(&walk, req, false);
228 ccm_calculate_auth_mac(req, mac);
231 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
233 if (walk.nbytes == walk.total)
236 ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
237 walk.nbytes - tail, ctx->key_enc,
238 num_rounds(ctx), mac, walk.iv);
240 if (walk.nbytes == walk.total)
241 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
246 err = skcipher_walk_done(&walk, tail);
249 if (unlikely(walk.nbytes))
252 } while (walk.nbytes);
254 /* compare calculated auth tag with the stored one */
255 scatterwalk_map_and_copy(buf, req->src,
256 req->assoclen + req->cryptlen - authsize,
259 if (crypto_memneq(mac, buf, authsize))
264 static struct aead_alg ccm_aes_alg = {
266 .cra_name = "ccm(aes)",
267 .cra_driver_name = "ccm-aes-ce",
270 .cra_ctxsize = sizeof(struct crypto_aes_ctx),
271 .cra_module = THIS_MODULE,
273 .ivsize = AES_BLOCK_SIZE,
274 .chunksize = AES_BLOCK_SIZE,
275 .maxauthsize = AES_BLOCK_SIZE,
276 .setkey = ccm_setkey,
277 .setauthsize = ccm_setauthsize,
278 .encrypt = ccm_encrypt,
279 .decrypt = ccm_decrypt,
282 static int __init aes_mod_init(void)
284 if (!cpu_have_named_feature(AES))
286 return crypto_register_aead(&ccm_aes_alg);
289 static void __exit aes_mod_exit(void)
291 crypto_unregister_aead(&ccm_aes_alg);
294 module_init(aes_mod_init);
295 module_exit(aes_mod_exit);
297 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
298 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
299 MODULE_LICENSE("GPL v2");
300 MODULE_ALIAS_CRYPTO("ccm(aes)");