1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
4 *
5 * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
6 */
7
8 #include <asm/neon.h>
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>
15
16 #include "aes-ce-setkey.h"
17
num_rounds(struct crypto_aes_ctx * ctx)18 static int num_rounds(struct crypto_aes_ctx *ctx)
19 {
20 /*
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
26 */
27 return 6 + ctx->key_length / 4;
28 }
29
30 asmlinkage u32 ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
31 u32 macp, u32 const rk[], u32 rounds);
32
33 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
34 u32 const rk[], u32 rounds, u8 mac[],
35 u8 ctr[]);
36
37 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
38 u32 const rk[], u32 rounds, u8 mac[],
39 u8 ctr[]);
40
41 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
42 u32 rounds);
43
ccm_setkey(struct crypto_aead * tfm,const u8 * in_key,unsigned int key_len)44 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
45 unsigned int key_len)
46 {
47 struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
48
49 return ce_aes_expandkey(ctx, in_key, key_len);
50 }
51
ccm_setauthsize(struct crypto_aead * tfm,unsigned int authsize)52 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
53 {
54 if ((authsize & 1) || authsize < 4)
55 return -EINVAL;
56 return 0;
57 }
58
ccm_init_mac(struct aead_request * req,u8 maciv[],u32 msglen)59 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
60 {
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;
64
65 /* verify that CCM dimension 'L' is set correctly in the IV */
66 if (l < 2 || l > 8)
67 return -EINVAL;
68
69 /* verify that msglen can in fact be represented in L bytes */
70 if (l < 4 && msglen >> (8 * l))
71 return -EOVERFLOW;
72
73 /*
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.
76 */
77 n[0] = 0;
78 n[1] = cpu_to_be32(msglen);
79
80 memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
81
82 /*
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
88 */
89 maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
90 if (req->assoclen)
91 maciv[0] |= 0x40;
92
93 memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
94 return 0;
95 }
96
ccm_calculate_auth_mac(struct aead_request * req,u8 mac[])97 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
98 {
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;
104 u32 macp = 0;
105
106 /* prepend the AAD with a length tag */
107 if (len < 0xff00) {
108 ltag.l = cpu_to_be16(len);
109 ltag.len = 2;
110 } else {
111 ltag.l = cpu_to_be16(0xfffe);
112 put_unaligned_be32(len, <ag.h);
113 ltag.len = 6;
114 }
115
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);
119
120 do {
121 u32 n = scatterwalk_clamp(&walk, len);
122 u8 *p;
123
124 if (!n) {
125 scatterwalk_start(&walk, sg_next(walk.sg));
126 n = scatterwalk_clamp(&walk, len);
127 }
128 n = min_t(u32, n, SZ_4K); /* yield NEON at least every 4k */
129 p = scatterwalk_map(&walk);
130
131 macp = ce_aes_ccm_auth_data(mac, p, n, macp, ctx->key_enc,
132 num_rounds(ctx));
133
134 if (len / SZ_4K > (len - n) / SZ_4K) {
135 kernel_neon_end();
136 kernel_neon_begin();
137 }
138 len -= n;
139
140 scatterwalk_unmap(p);
141 scatterwalk_advance(&walk, n);
142 scatterwalk_done(&walk, 0, len);
143 } while (len);
144 }
145
ccm_encrypt(struct aead_request * req)146 static int ccm_encrypt(struct aead_request *req)
147 {
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;
154 int err;
155
156 err = ccm_init_mac(req, mac, len);
157 if (err)
158 return err;
159
160 /* preserve the original iv for the final round */
161 memcpy(buf, req->iv, AES_BLOCK_SIZE);
162
163 err = skcipher_walk_aead_encrypt(&walk, req, false);
164
165 kernel_neon_begin();
166
167 if (req->assoclen)
168 ccm_calculate_auth_mac(req, mac);
169
170 while (walk.nbytes) {
171 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
172 bool final = walk.nbytes == walk.total;
173
174 if (final)
175 tail = 0;
176
177 ce_aes_ccm_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
178 walk.nbytes - tail, ctx->key_enc,
179 num_rounds(ctx), mac, walk.iv);
180
181 if (!final)
182 kernel_neon_end();
183 err = skcipher_walk_done(&walk, tail);
184 if (!final)
185 kernel_neon_begin();
186 }
187
188 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
189
190 kernel_neon_end();
191
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);
195
196 return err;
197 }
198
ccm_decrypt(struct aead_request * req)199 static int ccm_decrypt(struct aead_request *req)
200 {
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;
208 int err;
209
210 err = ccm_init_mac(req, mac, len);
211 if (err)
212 return err;
213
214 /* preserve the original iv for the final round */
215 memcpy(buf, req->iv, AES_BLOCK_SIZE);
216
217 err = skcipher_walk_aead_decrypt(&walk, req, false);
218
219 kernel_neon_begin();
220
221 if (req->assoclen)
222 ccm_calculate_auth_mac(req, mac);
223
224 while (walk.nbytes) {
225 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
226 bool final = walk.nbytes == walk.total;
227
228 if (final)
229 tail = 0;
230
231 ce_aes_ccm_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
232 walk.nbytes - tail, ctx->key_enc,
233 num_rounds(ctx), mac, walk.iv);
234
235 if (!final)
236 kernel_neon_end();
237 err = skcipher_walk_done(&walk, tail);
238 if (!final)
239 kernel_neon_begin();
240 }
241
242 ce_aes_ccm_final(mac, buf, ctx->key_enc, num_rounds(ctx));
243
244 kernel_neon_end();
245
246 if (unlikely(err))
247 return err;
248
249 /* compare calculated auth tag with the stored one */
250 scatterwalk_map_and_copy(buf, req->src,
251 req->assoclen + req->cryptlen - authsize,
252 authsize, 0);
253
254 if (crypto_memneq(mac, buf, authsize))
255 return -EBADMSG;
256 return 0;
257 }
258
259 static struct aead_alg ccm_aes_alg = {
260 .base = {
261 .cra_name = "ccm(aes)",
262 .cra_driver_name = "ccm-aes-ce",
263 .cra_priority = 300,
264 .cra_blocksize = 1,
265 .cra_ctxsize = sizeof(struct crypto_aes_ctx),
266 .cra_module = THIS_MODULE,
267 },
268 .ivsize = AES_BLOCK_SIZE,
269 .chunksize = AES_BLOCK_SIZE,
270 .maxauthsize = AES_BLOCK_SIZE,
271 .setkey = ccm_setkey,
272 .setauthsize = ccm_setauthsize,
273 .encrypt = ccm_encrypt,
274 .decrypt = ccm_decrypt,
275 };
276
aes_mod_init(void)277 static int __init aes_mod_init(void)
278 {
279 if (!cpu_have_named_feature(AES))
280 return -ENODEV;
281 return crypto_register_aead(&ccm_aes_alg);
282 }
283
aes_mod_exit(void)284 static void __exit aes_mod_exit(void)
285 {
286 crypto_unregister_aead(&ccm_aes_alg);
287 }
288
289 module_init(aes_mod_init);
290 module_exit(aes_mod_exit);
291
292 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
293 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
294 MODULE_LICENSE("GPL v2");
295 MODULE_ALIAS_CRYPTO("ccm(aes)");
296
