xref: /openbmc/linux/crypto/authenc.c (revision 3ac14b39)
1 /*
2  * Authenc: Simple AEAD wrapper for IPsec
3  *
4  * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  */
12 
13 #include <crypto/internal/aead.h>
14 #include <crypto/internal/hash.h>
15 #include <crypto/internal/skcipher.h>
16 #include <crypto/authenc.h>
17 #include <crypto/null.h>
18 #include <crypto/scatterwalk.h>
19 #include <linux/err.h>
20 #include <linux/init.h>
21 #include <linux/kernel.h>
22 #include <linux/module.h>
23 #include <linux/rtnetlink.h>
24 #include <linux/slab.h>
25 #include <linux/spinlock.h>
26 
27 struct authenc_instance_ctx {
28 	struct crypto_ahash_spawn auth;
29 	struct crypto_skcipher_spawn enc;
30 	unsigned int reqoff;
31 };
32 
33 struct crypto_authenc_ctx {
34 	struct crypto_ahash *auth;
35 	struct crypto_skcipher *enc;
36 	struct crypto_skcipher *null;
37 };
38 
39 struct authenc_request_ctx {
40 	struct scatterlist src[2];
41 	struct scatterlist dst[2];
42 	char tail[];
43 };
44 
45 static void authenc_request_complete(struct aead_request *req, int err)
46 {
47 	if (err != -EINPROGRESS)
48 		aead_request_complete(req, err);
49 }
50 
51 int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
52 			       unsigned int keylen)
53 {
54 	struct rtattr *rta = (struct rtattr *)key;
55 	struct crypto_authenc_key_param *param;
56 
57 	if (!RTA_OK(rta, keylen))
58 		return -EINVAL;
59 	if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
60 		return -EINVAL;
61 	if (RTA_PAYLOAD(rta) < sizeof(*param))
62 		return -EINVAL;
63 
64 	param = RTA_DATA(rta);
65 	keys->enckeylen = be32_to_cpu(param->enckeylen);
66 
67 	key += RTA_ALIGN(rta->rta_len);
68 	keylen -= RTA_ALIGN(rta->rta_len);
69 
70 	if (keylen < keys->enckeylen)
71 		return -EINVAL;
72 
73 	keys->authkeylen = keylen - keys->enckeylen;
74 	keys->authkey = key;
75 	keys->enckey = key + keys->authkeylen;
76 
77 	return 0;
78 }
79 EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
80 
81 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
82 				 unsigned int keylen)
83 {
84 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
85 	struct crypto_ahash *auth = ctx->auth;
86 	struct crypto_skcipher *enc = ctx->enc;
87 	struct crypto_authenc_keys keys;
88 	int err = -EINVAL;
89 
90 	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
91 		goto badkey;
92 
93 	crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
94 	crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
95 				    CRYPTO_TFM_REQ_MASK);
96 	err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
97 	crypto_aead_set_flags(authenc, crypto_ahash_get_flags(auth) &
98 				       CRYPTO_TFM_RES_MASK);
99 
100 	if (err)
101 		goto out;
102 
103 	crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
104 	crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
105 				       CRYPTO_TFM_REQ_MASK);
106 	err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
107 	crypto_aead_set_flags(authenc, crypto_skcipher_get_flags(enc) &
108 				       CRYPTO_TFM_RES_MASK);
109 
110 out:
111 	memzero_explicit(&keys, sizeof(keys));
112 	return err;
113 
114 badkey:
115 	crypto_aead_set_flags(authenc, CRYPTO_TFM_RES_BAD_KEY_LEN);
116 	goto out;
117 }
118 
119 static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
120 {
121 	struct aead_request *req = areq->data;
122 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
123 	struct aead_instance *inst = aead_alg_instance(authenc);
124 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
125 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
126 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
127 
128 	if (err)
129 		goto out;
130 
131 	scatterwalk_map_and_copy(ahreq->result, req->dst,
132 				 req->assoclen + req->cryptlen,
133 				 crypto_aead_authsize(authenc), 1);
134 
135 out:
136 	aead_request_complete(req, err);
137 }
138 
139 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
140 {
141 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
142 	struct aead_instance *inst = aead_alg_instance(authenc);
143 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
144 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
145 	struct crypto_ahash *auth = ctx->auth;
146 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
147 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
148 	u8 *hash = areq_ctx->tail;
149 	int err;
150 
151 	hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
152 			   crypto_ahash_alignmask(auth) + 1);
153 
154 	ahash_request_set_tfm(ahreq, auth);
155 	ahash_request_set_crypt(ahreq, req->dst, hash,
156 				req->assoclen + req->cryptlen);
157 	ahash_request_set_callback(ahreq, flags,
158 				   authenc_geniv_ahash_done, req);
159 
160 	err = crypto_ahash_digest(ahreq);
161 	if (err)
162 		return err;
163 
164 	scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
165 				 crypto_aead_authsize(authenc), 1);
166 
167 	return 0;
168 }
169 
170 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
171 					int err)
172 {
173 	struct aead_request *areq = req->data;
174 
175 	if (err)
176 		goto out;
177 
178 	err = crypto_authenc_genicv(areq, 0);
179 
180 out:
181 	authenc_request_complete(areq, err);
182 }
183 
184 static int crypto_authenc_copy_assoc(struct aead_request *req)
185 {
186 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
187 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
188 	SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
189 
190 	skcipher_request_set_tfm(skreq, ctx->null);
191 	skcipher_request_set_callback(skreq, aead_request_flags(req),
192 				      NULL, NULL);
193 	skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
194 				   NULL);
195 
196 	return crypto_skcipher_encrypt(skreq);
197 }
198 
199 static int crypto_authenc_encrypt(struct aead_request *req)
200 {
201 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
202 	struct aead_instance *inst = aead_alg_instance(authenc);
203 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
204 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
205 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
206 	struct crypto_skcipher *enc = ctx->enc;
207 	unsigned int cryptlen = req->cryptlen;
208 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
209 						  ictx->reqoff);
210 	struct scatterlist *src, *dst;
211 	int err;
212 
213 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
214 	dst = src;
215 
216 	if (req->src != req->dst) {
217 		err = crypto_authenc_copy_assoc(req);
218 		if (err)
219 			return err;
220 
221 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
222 	}
223 
224 	skcipher_request_set_tfm(skreq, enc);
225 	skcipher_request_set_callback(skreq, aead_request_flags(req),
226 				      crypto_authenc_encrypt_done, req);
227 	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
228 
229 	err = crypto_skcipher_encrypt(skreq);
230 	if (err)
231 		return err;
232 
233 	return crypto_authenc_genicv(req, aead_request_flags(req));
234 }
235 
236 static int crypto_authenc_decrypt_tail(struct aead_request *req,
237 				       unsigned int flags)
238 {
239 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
240 	struct aead_instance *inst = aead_alg_instance(authenc);
241 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
242 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
243 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
244 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
245 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
246 						  ictx->reqoff);
247 	unsigned int authsize = crypto_aead_authsize(authenc);
248 	u8 *ihash = ahreq->result + authsize;
249 	struct scatterlist *src, *dst;
250 
251 	scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
252 
253 	if (crypto_memneq(ihash, ahreq->result, authsize))
254 		return -EBADMSG;
255 
256 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
257 	dst = src;
258 
259 	if (req->src != req->dst)
260 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
261 
262 	skcipher_request_set_tfm(skreq, ctx->enc);
263 	skcipher_request_set_callback(skreq, aead_request_flags(req),
264 				      req->base.complete, req->base.data);
265 	skcipher_request_set_crypt(skreq, src, dst,
266 				   req->cryptlen - authsize, req->iv);
267 
268 	return crypto_skcipher_decrypt(skreq);
269 }
270 
271 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
272 				      int err)
273 {
274 	struct aead_request *req = areq->data;
275 
276 	if (err)
277 		goto out;
278 
279 	err = crypto_authenc_decrypt_tail(req, 0);
280 
281 out:
282 	authenc_request_complete(req, err);
283 }
284 
285 static int crypto_authenc_decrypt(struct aead_request *req)
286 {
287 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
288 	unsigned int authsize = crypto_aead_authsize(authenc);
289 	struct aead_instance *inst = aead_alg_instance(authenc);
290 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
291 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
292 	struct crypto_ahash *auth = ctx->auth;
293 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
294 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
295 	u8 *hash = areq_ctx->tail;
296 	int err;
297 
298 	hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
299 			   crypto_ahash_alignmask(auth) + 1);
300 
301 	ahash_request_set_tfm(ahreq, auth);
302 	ahash_request_set_crypt(ahreq, req->src, hash,
303 				req->assoclen + req->cryptlen - authsize);
304 	ahash_request_set_callback(ahreq, aead_request_flags(req),
305 				   authenc_verify_ahash_done, req);
306 
307 	err = crypto_ahash_digest(ahreq);
308 	if (err)
309 		return err;
310 
311 	return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
312 }
313 
314 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
315 {
316 	struct aead_instance *inst = aead_alg_instance(tfm);
317 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
318 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
319 	struct crypto_ahash *auth;
320 	struct crypto_skcipher *enc;
321 	struct crypto_skcipher *null;
322 	int err;
323 
324 	auth = crypto_spawn_ahash(&ictx->auth);
325 	if (IS_ERR(auth))
326 		return PTR_ERR(auth);
327 
328 	enc = crypto_spawn_skcipher(&ictx->enc);
329 	err = PTR_ERR(enc);
330 	if (IS_ERR(enc))
331 		goto err_free_ahash;
332 
333 	null = crypto_get_default_null_skcipher();
334 	err = PTR_ERR(null);
335 	if (IS_ERR(null))
336 		goto err_free_skcipher;
337 
338 	ctx->auth = auth;
339 	ctx->enc = enc;
340 	ctx->null = null;
341 
342 	crypto_aead_set_reqsize(
343 		tfm,
344 		sizeof(struct authenc_request_ctx) +
345 		ictx->reqoff +
346 		max_t(unsigned int,
347 		      crypto_ahash_reqsize(auth) +
348 		      sizeof(struct ahash_request),
349 		      sizeof(struct skcipher_request) +
350 		      crypto_skcipher_reqsize(enc)));
351 
352 	return 0;
353 
354 err_free_skcipher:
355 	crypto_free_skcipher(enc);
356 err_free_ahash:
357 	crypto_free_ahash(auth);
358 	return err;
359 }
360 
361 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
362 {
363 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
364 
365 	crypto_free_ahash(ctx->auth);
366 	crypto_free_skcipher(ctx->enc);
367 	crypto_put_default_null_skcipher();
368 }
369 
370 static void crypto_authenc_free(struct aead_instance *inst)
371 {
372 	struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
373 
374 	crypto_drop_skcipher(&ctx->enc);
375 	crypto_drop_ahash(&ctx->auth);
376 	kfree(inst);
377 }
378 
379 static int crypto_authenc_create(struct crypto_template *tmpl,
380 				 struct rtattr **tb)
381 {
382 	struct crypto_attr_type *algt;
383 	struct aead_instance *inst;
384 	struct hash_alg_common *auth;
385 	struct crypto_alg *auth_base;
386 	struct skcipher_alg *enc;
387 	struct authenc_instance_ctx *ctx;
388 	const char *enc_name;
389 	int err;
390 
391 	algt = crypto_get_attr_type(tb);
392 	if (IS_ERR(algt))
393 		return PTR_ERR(algt);
394 
395 	if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & algt->mask)
396 		return -EINVAL;
397 
398 	auth = ahash_attr_alg(tb[1], CRYPTO_ALG_TYPE_HASH,
399 			      CRYPTO_ALG_TYPE_AHASH_MASK |
400 			      crypto_requires_sync(algt->type, algt->mask));
401 	if (IS_ERR(auth))
402 		return PTR_ERR(auth);
403 
404 	auth_base = &auth->base;
405 
406 	enc_name = crypto_attr_alg_name(tb[2]);
407 	err = PTR_ERR(enc_name);
408 	if (IS_ERR(enc_name))
409 		goto out_put_auth;
410 
411 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
412 	err = -ENOMEM;
413 	if (!inst)
414 		goto out_put_auth;
415 
416 	ctx = aead_instance_ctx(inst);
417 
418 	err = crypto_init_ahash_spawn(&ctx->auth, auth,
419 				      aead_crypto_instance(inst));
420 	if (err)
421 		goto err_free_inst;
422 
423 	crypto_set_skcipher_spawn(&ctx->enc, aead_crypto_instance(inst));
424 	err = crypto_grab_skcipher(&ctx->enc, enc_name, 0,
425 				   crypto_requires_sync(algt->type,
426 							algt->mask));
427 	if (err)
428 		goto err_drop_auth;
429 
430 	enc = crypto_spawn_skcipher_alg(&ctx->enc);
431 
432 	ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
433 			    auth_base->cra_alignmask + 1);
434 
435 	err = -ENAMETOOLONG;
436 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
437 		     "authenc(%s,%s)", auth_base->cra_name,
438 		     enc->base.cra_name) >=
439 	    CRYPTO_MAX_ALG_NAME)
440 		goto err_drop_enc;
441 
442 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
443 		     "authenc(%s,%s)", auth_base->cra_driver_name,
444 		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
445 		goto err_drop_enc;
446 
447 	inst->alg.base.cra_flags = (auth_base->cra_flags |
448 				    enc->base.cra_flags) & CRYPTO_ALG_ASYNC;
449 	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
450 				      auth_base->cra_priority;
451 	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
452 	inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
453 				       enc->base.cra_alignmask;
454 	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
455 
456 	inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
457 	inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
458 	inst->alg.maxauthsize = auth->digestsize;
459 
460 	inst->alg.init = crypto_authenc_init_tfm;
461 	inst->alg.exit = crypto_authenc_exit_tfm;
462 
463 	inst->alg.setkey = crypto_authenc_setkey;
464 	inst->alg.encrypt = crypto_authenc_encrypt;
465 	inst->alg.decrypt = crypto_authenc_decrypt;
466 
467 	inst->free = crypto_authenc_free;
468 
469 	err = aead_register_instance(tmpl, inst);
470 	if (err)
471 		goto err_drop_enc;
472 
473 out:
474 	crypto_mod_put(auth_base);
475 	return err;
476 
477 err_drop_enc:
478 	crypto_drop_skcipher(&ctx->enc);
479 err_drop_auth:
480 	crypto_drop_ahash(&ctx->auth);
481 err_free_inst:
482 	kfree(inst);
483 out_put_auth:
484 	goto out;
485 }
486 
487 static struct crypto_template crypto_authenc_tmpl = {
488 	.name = "authenc",
489 	.create = crypto_authenc_create,
490 	.module = THIS_MODULE,
491 };
492 
493 static int __init crypto_authenc_module_init(void)
494 {
495 	return crypto_register_template(&crypto_authenc_tmpl);
496 }
497 
498 static void __exit crypto_authenc_module_exit(void)
499 {
500 	crypto_unregister_template(&crypto_authenc_tmpl);
501 }
502 
503 module_init(crypto_authenc_module_init);
504 module_exit(crypto_authenc_module_exit);
505 
506 MODULE_LICENSE("GPL");
507 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
508 MODULE_ALIAS_CRYPTO("authenc");
509