1 /*
2 * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
3 *
4 * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
5 *
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.
9 */
10
11 #include <asm/neon.h>
12 #include <asm/simd.h>
13 #include <asm/unaligned.h>
14 #include <crypto/aes.h>
15 #include <crypto/scatterwalk.h>
16 #include <crypto/internal/aead.h>
17 #include <crypto/internal/skcipher.h>
18 #include <linux/module.h>
19
20 #include "aes-ce-setkey.h"
21
num_rounds(struct crypto_aes_ctx * ctx)22 static int num_rounds(struct crypto_aes_ctx *ctx)
23 {
24 /*
25 * # of rounds specified by AES:
26 * 128 bit key 10 rounds
27 * 192 bit key 12 rounds
28 * 256 bit key 14 rounds
29 * => n byte key => 6 + (n/4) rounds
30 */
31 return 6 + ctx->key_length / 4;
32 }
33
34 asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
35 u32 *macp, u32 const rk[], u32 rounds);
36
37 asmlinkage void ce_aes_ccm_encrypt(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_decrypt(u8 out[], u8 const in[], u32 cbytes,
42 u32 const rk[], u32 rounds, u8 mac[],
43 u8 ctr[]);
44
45 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
46 u32 rounds);
47
48 asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
49
ccm_setkey(struct crypto_aead * tfm,const u8 * in_key,unsigned int key_len)50 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
51 unsigned int key_len)
52 {
53 struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
54 int ret;
55
56 ret = ce_aes_expandkey(ctx, in_key, key_len);
57 if (!ret)
58 return 0;
59
60 tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
61 return -EINVAL;
62 }
63
ccm_setauthsize(struct crypto_aead * tfm,unsigned int authsize)64 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
65 {
66 if ((authsize & 1) || authsize < 4)
67 return -EINVAL;
68 return 0;
69 }
70
ccm_init_mac(struct aead_request * req,u8 maciv[],u32 msglen)71 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
72 {
73 struct crypto_aead *aead = crypto_aead_reqtfm(req);
74 __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
75 u32 l = req->iv[0] + 1;
76
77 /* verify that CCM dimension 'L' is set correctly in the IV */
78 if (l < 2 || l > 8)
79 return -EINVAL;
80
81 /* verify that msglen can in fact be represented in L bytes */
82 if (l < 4 && msglen >> (8 * l))
83 return -EOVERFLOW;
84
85 /*
86 * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
87 * uses a u32 type to represent msglen so the top 4 bytes are always 0.
88 */
89 n[0] = 0;
90 n[1] = cpu_to_be32(msglen);
91
92 memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
93
94 /*
95 * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
96 * - bits 0..2 : max # of bytes required to represent msglen, minus 1
97 * (already set by caller)
98 * - bits 3..5 : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
99 * - bit 6 : indicates presence of authenticate-only data
100 */
101 maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
102 if (req->assoclen)
103 maciv[0] |= 0x40;
104
105 memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
106 return 0;
107 }
108
ccm_update_mac(struct crypto_aes_ctx * key,u8 mac[],u8 const in[],u32 abytes,u32 * macp,bool use_neon)109 static void ccm_update_mac(struct crypto_aes_ctx *key, u8 mac[], u8 const in[],
110 u32 abytes, u32 *macp, bool use_neon)
111 {
112 if (likely(use_neon)) {
113 ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc,
114 num_rounds(key));
115 } else {
116 if (*macp > 0 && *macp < AES_BLOCK_SIZE) {
117 int added = min(abytes, AES_BLOCK_SIZE - *macp);
118
119 crypto_xor(&mac[*macp], in, added);
120
121 *macp += added;
122 in += added;
123 abytes -= added;
124 }
125
126 while (abytes >= AES_BLOCK_SIZE) {
127 __aes_arm64_encrypt(key->key_enc, mac, mac,
128 num_rounds(key));
129 crypto_xor(mac, in, AES_BLOCK_SIZE);
130
131 in += AES_BLOCK_SIZE;
132 abytes -= AES_BLOCK_SIZE;
133 }
134
135 if (abytes > 0) {
136 __aes_arm64_encrypt(key->key_enc, mac, mac,
137 num_rounds(key));
138 crypto_xor(mac, in, abytes);
139 *macp = abytes;
140 }
141 }
142 }
143
ccm_calculate_auth_mac(struct aead_request * req,u8 mac[],bool use_neon)144 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[],
145 bool use_neon)
146 {
147 struct crypto_aead *aead = crypto_aead_reqtfm(req);
148 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
149 struct __packed { __be16 l; __be32 h; u16 len; } ltag;
150 struct scatter_walk walk;
151 u32 len = req->assoclen;
152 u32 macp = 0;
153
154 /* prepend the AAD with a length tag */
155 if (len < 0xff00) {
156 ltag.l = cpu_to_be16(len);
157 ltag.len = 2;
158 } else {
159 ltag.l = cpu_to_be16(0xfffe);
160 put_unaligned_be32(len, <ag.h);
161 ltag.len = 6;
162 }
163
164 ccm_update_mac(ctx, mac, (u8 *)<ag, ltag.len, &macp, use_neon);
165 scatterwalk_start(&walk, req->src);
166
167 do {
168 u32 n = scatterwalk_clamp(&walk, len);
169 u8 *p;
170
171 if (!n) {
172 scatterwalk_start(&walk, sg_next(walk.sg));
173 n = scatterwalk_clamp(&walk, len);
174 }
175 p = scatterwalk_map(&walk);
176 ccm_update_mac(ctx, mac, p, n, &macp, use_neon);
177 len -= n;
178
179 scatterwalk_unmap(p);
180 scatterwalk_advance(&walk, n);
181 scatterwalk_done(&walk, 0, len);
182 } while (len);
183 }
184
ccm_crypt_fallback(struct skcipher_walk * walk,u8 mac[],u8 iv0[],struct crypto_aes_ctx * ctx,bool enc)185 static int ccm_crypt_fallback(struct skcipher_walk *walk, u8 mac[], u8 iv0[],
186 struct crypto_aes_ctx *ctx, bool enc)
187 {
188 u8 buf[AES_BLOCK_SIZE];
189 int err = 0;
190
191 while (walk->nbytes) {
192 int blocks = walk->nbytes / AES_BLOCK_SIZE;
193 u32 tail = walk->nbytes % AES_BLOCK_SIZE;
194 u8 *dst = walk->dst.virt.addr;
195 u8 *src = walk->src.virt.addr;
196 u32 nbytes = walk->nbytes;
197
198 if (nbytes == walk->total && tail > 0) {
199 blocks++;
200 tail = 0;
201 }
202
203 do {
204 u32 bsize = AES_BLOCK_SIZE;
205
206 if (nbytes < AES_BLOCK_SIZE)
207 bsize = nbytes;
208
209 crypto_inc(walk->iv, AES_BLOCK_SIZE);
210 __aes_arm64_encrypt(ctx->key_enc, buf, walk->iv,
211 num_rounds(ctx));
212 __aes_arm64_encrypt(ctx->key_enc, mac, mac,
213 num_rounds(ctx));
214 if (enc)
215 crypto_xor(mac, src, bsize);
216 crypto_xor_cpy(dst, src, buf, bsize);
217 if (!enc)
218 crypto_xor(mac, dst, bsize);
219 dst += bsize;
220 src += bsize;
221 nbytes -= bsize;
222 } while (--blocks);
223
224 err = skcipher_walk_done(walk, tail);
225 }
226
227 if (!err) {
228 __aes_arm64_encrypt(ctx->key_enc, buf, iv0, num_rounds(ctx));
229 __aes_arm64_encrypt(ctx->key_enc, mac, mac, num_rounds(ctx));
230 crypto_xor(mac, buf, AES_BLOCK_SIZE);
231 }
232 return err;
233 }
234
ccm_encrypt(struct aead_request * req)235 static int ccm_encrypt(struct aead_request *req)
236 {
237 struct crypto_aead *aead = crypto_aead_reqtfm(req);
238 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
239 struct skcipher_walk walk;
240 u8 __aligned(8) mac[AES_BLOCK_SIZE];
241 u8 buf[AES_BLOCK_SIZE];
242 u32 len = req->cryptlen;
243 bool use_neon = may_use_simd();
244 int err;
245
246 err = ccm_init_mac(req, mac, len);
247 if (err)
248 return err;
249
250 if (likely(use_neon))
251 kernel_neon_begin();
252
253 if (req->assoclen)
254 ccm_calculate_auth_mac(req, mac, use_neon);
255
256 /* preserve the original iv for the final round */
257 memcpy(buf, req->iv, AES_BLOCK_SIZE);
258
259 err = skcipher_walk_aead_encrypt(&walk, req, true);
260
261 if (likely(use_neon)) {
262 while (walk.nbytes) {
263 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
264
265 if (walk.nbytes == walk.total)
266 tail = 0;
267
268 ce_aes_ccm_encrypt(walk.dst.virt.addr,
269 walk.src.virt.addr,
270 walk.nbytes - tail, ctx->key_enc,
271 num_rounds(ctx), mac, walk.iv);
272
273 err = skcipher_walk_done(&walk, tail);
274 }
275 if (!err)
276 ce_aes_ccm_final(mac, buf, ctx->key_enc,
277 num_rounds(ctx));
278
279 kernel_neon_end();
280 } else {
281 err = ccm_crypt_fallback(&walk, mac, buf, ctx, true);
282 }
283 if (err)
284 return err;
285
286 /* copy authtag to end of dst */
287 scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
288 crypto_aead_authsize(aead), 1);
289
290 return 0;
291 }
292
ccm_decrypt(struct aead_request * req)293 static int ccm_decrypt(struct aead_request *req)
294 {
295 struct crypto_aead *aead = crypto_aead_reqtfm(req);
296 struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
297 unsigned int authsize = crypto_aead_authsize(aead);
298 struct skcipher_walk walk;
299 u8 __aligned(8) mac[AES_BLOCK_SIZE];
300 u8 buf[AES_BLOCK_SIZE];
301 u32 len = req->cryptlen - authsize;
302 bool use_neon = may_use_simd();
303 int err;
304
305 err = ccm_init_mac(req, mac, len);
306 if (err)
307 return err;
308
309 if (likely(use_neon))
310 kernel_neon_begin();
311
312 if (req->assoclen)
313 ccm_calculate_auth_mac(req, mac, use_neon);
314
315 /* preserve the original iv for the final round */
316 memcpy(buf, req->iv, AES_BLOCK_SIZE);
317
318 err = skcipher_walk_aead_decrypt(&walk, req, true);
319
320 if (likely(use_neon)) {
321 while (walk.nbytes) {
322 u32 tail = walk.nbytes % AES_BLOCK_SIZE;
323
324 if (walk.nbytes == walk.total)
325 tail = 0;
326
327 ce_aes_ccm_decrypt(walk.dst.virt.addr,
328 walk.src.virt.addr,
329 walk.nbytes - tail, ctx->key_enc,
330 num_rounds(ctx), mac, walk.iv);
331
332 err = skcipher_walk_done(&walk, tail);
333 }
334 if (!err)
335 ce_aes_ccm_final(mac, buf, ctx->key_enc,
336 num_rounds(ctx));
337
338 kernel_neon_end();
339 } else {
340 err = ccm_crypt_fallback(&walk, mac, buf, ctx, false);
341 }
342
343 if (err)
344 return err;
345
346 /* compare calculated auth tag with the stored one */
347 scatterwalk_map_and_copy(buf, req->src,
348 req->assoclen + req->cryptlen - authsize,
349 authsize, 0);
350
351 if (crypto_memneq(mac, buf, authsize))
352 return -EBADMSG;
353 return 0;
354 }
355
356 static struct aead_alg ccm_aes_alg = {
357 .base = {
358 .cra_name = "ccm(aes)",
359 .cra_driver_name = "ccm-aes-ce",
360 .cra_priority = 300,
361 .cra_blocksize = 1,
362 .cra_ctxsize = sizeof(struct crypto_aes_ctx),
363 .cra_module = THIS_MODULE,
364 },
365 .ivsize = AES_BLOCK_SIZE,
366 .chunksize = AES_BLOCK_SIZE,
367 .maxauthsize = AES_BLOCK_SIZE,
368 .setkey = ccm_setkey,
369 .setauthsize = ccm_setauthsize,
370 .encrypt = ccm_encrypt,
371 .decrypt = ccm_decrypt,
372 };
373
aes_mod_init(void)374 static int __init aes_mod_init(void)
375 {
376 if (!(elf_hwcap & HWCAP_AES))
377 return -ENODEV;
378 return crypto_register_aead(&ccm_aes_alg);
379 }
380
aes_mod_exit(void)381 static void __exit aes_mod_exit(void)
382 {
383 crypto_unregister_aead(&ccm_aes_alg);
384 }
385
386 module_init(aes_mod_init);
387 module_exit(aes_mod_exit);
388
389 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
390 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
391 MODULE_LICENSE("GPL v2");
392 MODULE_ALIAS_CRYPTO("ccm(aes)");
393