xref: /linux/crypto/authenc.c (revision b1a54551dd9ed5ef1763b97b35a0999ca002b95c)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Authenc: Simple AEAD wrapper for IPsec
4  *
5  * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
6  */
7 
8 #include <crypto/internal/aead.h>
9 #include <crypto/internal/hash.h>
10 #include <crypto/internal/skcipher.h>
11 #include <crypto/authenc.h>
12 #include <crypto/null.h>
13 #include <crypto/scatterwalk.h>
14 #include <linux/err.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/rtnetlink.h>
19 #include <linux/slab.h>
20 #include <linux/spinlock.h>
21 
22 struct authenc_instance_ctx {
23 	struct crypto_ahash_spawn auth;
24 	struct crypto_skcipher_spawn enc;
25 	unsigned int reqoff;
26 };
27 
28 struct crypto_authenc_ctx {
29 	struct crypto_ahash *auth;
30 	struct crypto_skcipher *enc;
31 	struct crypto_sync_skcipher *null;
32 };
33 
34 struct authenc_request_ctx {
35 	struct scatterlist src[2];
36 	struct scatterlist dst[2];
37 	char tail[];
38 };
39 
40 static void authenc_request_complete(struct aead_request *req, int err)
41 {
42 	if (err != -EINPROGRESS)
43 		aead_request_complete(req, err);
44 }
45 
46 int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
47 			       unsigned int keylen)
48 {
49 	struct rtattr *rta = (struct rtattr *)key;
50 	struct crypto_authenc_key_param *param;
51 
52 	if (!RTA_OK(rta, keylen))
53 		return -EINVAL;
54 	if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
55 		return -EINVAL;
56 
57 	/*
58 	 * RTA_OK() didn't align the rtattr's payload when validating that it
59 	 * fits in the buffer.  Yet, the keys should start on the next 4-byte
60 	 * aligned boundary.  To avoid confusion, require that the rtattr
61 	 * payload be exactly the param struct, which has a 4-byte aligned size.
62 	 */
63 	if (RTA_PAYLOAD(rta) != sizeof(*param))
64 		return -EINVAL;
65 	BUILD_BUG_ON(sizeof(*param) % RTA_ALIGNTO);
66 
67 	param = RTA_DATA(rta);
68 	keys->enckeylen = be32_to_cpu(param->enckeylen);
69 
70 	key += rta->rta_len;
71 	keylen -= rta->rta_len;
72 
73 	if (keylen < keys->enckeylen)
74 		return -EINVAL;
75 
76 	keys->authkeylen = keylen - keys->enckeylen;
77 	keys->authkey = key;
78 	keys->enckey = key + keys->authkeylen;
79 
80 	return 0;
81 }
82 EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
83 
84 static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
85 				 unsigned int keylen)
86 {
87 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
88 	struct crypto_ahash *auth = ctx->auth;
89 	struct crypto_skcipher *enc = ctx->enc;
90 	struct crypto_authenc_keys keys;
91 	int err = -EINVAL;
92 
93 	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
94 		goto out;
95 
96 	crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
97 	crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
98 				    CRYPTO_TFM_REQ_MASK);
99 	err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
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 out:
108 	memzero_explicit(&keys, sizeof(keys));
109 	return err;
110 }
111 
112 static void authenc_geniv_ahash_done(void *data, int err)
113 {
114 	struct aead_request *req = data;
115 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
116 	struct aead_instance *inst = aead_alg_instance(authenc);
117 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
118 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
119 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
120 
121 	if (err)
122 		goto out;
123 
124 	scatterwalk_map_and_copy(ahreq->result, req->dst,
125 				 req->assoclen + req->cryptlen,
126 				 crypto_aead_authsize(authenc), 1);
127 
128 out:
129 	aead_request_complete(req, err);
130 }
131 
132 static int crypto_authenc_genicv(struct aead_request *req, unsigned int flags)
133 {
134 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
135 	struct aead_instance *inst = aead_alg_instance(authenc);
136 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
137 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
138 	struct crypto_ahash *auth = ctx->auth;
139 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
140 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
141 	u8 *hash = areq_ctx->tail;
142 	int err;
143 
144 	ahash_request_set_tfm(ahreq, auth);
145 	ahash_request_set_crypt(ahreq, req->dst, hash,
146 				req->assoclen + req->cryptlen);
147 	ahash_request_set_callback(ahreq, flags,
148 				   authenc_geniv_ahash_done, req);
149 
150 	err = crypto_ahash_digest(ahreq);
151 	if (err)
152 		return err;
153 
154 	scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
155 				 crypto_aead_authsize(authenc), 1);
156 
157 	return 0;
158 }
159 
160 static void crypto_authenc_encrypt_done(void *data, int err)
161 {
162 	struct aead_request *areq = data;
163 
164 	if (err)
165 		goto out;
166 
167 	err = crypto_authenc_genicv(areq, 0);
168 
169 out:
170 	authenc_request_complete(areq, err);
171 }
172 
173 static int crypto_authenc_copy_assoc(struct aead_request *req)
174 {
175 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
176 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
177 	SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
178 
179 	skcipher_request_set_sync_tfm(skreq, ctx->null);
180 	skcipher_request_set_callback(skreq, aead_request_flags(req),
181 				      NULL, NULL);
182 	skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
183 				   NULL);
184 
185 	return crypto_skcipher_encrypt(skreq);
186 }
187 
188 static int crypto_authenc_encrypt(struct aead_request *req)
189 {
190 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
191 	struct aead_instance *inst = aead_alg_instance(authenc);
192 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
193 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
194 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
195 	struct crypto_skcipher *enc = ctx->enc;
196 	unsigned int cryptlen = req->cryptlen;
197 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
198 						  ictx->reqoff);
199 	struct scatterlist *src, *dst;
200 	int err;
201 
202 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
203 	dst = src;
204 
205 	if (req->src != req->dst) {
206 		err = crypto_authenc_copy_assoc(req);
207 		if (err)
208 			return err;
209 
210 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
211 	}
212 
213 	skcipher_request_set_tfm(skreq, enc);
214 	skcipher_request_set_callback(skreq, aead_request_flags(req),
215 				      crypto_authenc_encrypt_done, req);
216 	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
217 
218 	err = crypto_skcipher_encrypt(skreq);
219 	if (err)
220 		return err;
221 
222 	return crypto_authenc_genicv(req, aead_request_flags(req));
223 }
224 
225 static int crypto_authenc_decrypt_tail(struct aead_request *req,
226 				       unsigned int flags)
227 {
228 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
229 	struct aead_instance *inst = aead_alg_instance(authenc);
230 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
231 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
232 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
233 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
234 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
235 						  ictx->reqoff);
236 	unsigned int authsize = crypto_aead_authsize(authenc);
237 	u8 *ihash = ahreq->result + authsize;
238 	struct scatterlist *src, *dst;
239 
240 	scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
241 
242 	if (crypto_memneq(ihash, ahreq->result, authsize))
243 		return -EBADMSG;
244 
245 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
246 	dst = src;
247 
248 	if (req->src != req->dst)
249 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
250 
251 	skcipher_request_set_tfm(skreq, ctx->enc);
252 	skcipher_request_set_callback(skreq, flags,
253 				      req->base.complete, req->base.data);
254 	skcipher_request_set_crypt(skreq, src, dst,
255 				   req->cryptlen - authsize, req->iv);
256 
257 	return crypto_skcipher_decrypt(skreq);
258 }
259 
260 static void authenc_verify_ahash_done(void *data, int err)
261 {
262 	struct aead_request *req = data;
263 
264 	if (err)
265 		goto out;
266 
267 	err = crypto_authenc_decrypt_tail(req, 0);
268 
269 out:
270 	authenc_request_complete(req, err);
271 }
272 
273 static int crypto_authenc_decrypt(struct aead_request *req)
274 {
275 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
276 	unsigned int authsize = crypto_aead_authsize(authenc);
277 	struct aead_instance *inst = aead_alg_instance(authenc);
278 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
279 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
280 	struct crypto_ahash *auth = ctx->auth;
281 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
282 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
283 	u8 *hash = areq_ctx->tail;
284 	int err;
285 
286 	ahash_request_set_tfm(ahreq, auth);
287 	ahash_request_set_crypt(ahreq, req->src, hash,
288 				req->assoclen + req->cryptlen - authsize);
289 	ahash_request_set_callback(ahreq, aead_request_flags(req),
290 				   authenc_verify_ahash_done, req);
291 
292 	err = crypto_ahash_digest(ahreq);
293 	if (err)
294 		return err;
295 
296 	return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
297 }
298 
299 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
300 {
301 	struct aead_instance *inst = aead_alg_instance(tfm);
302 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
303 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
304 	struct crypto_ahash *auth;
305 	struct crypto_skcipher *enc;
306 	struct crypto_sync_skcipher *null;
307 	int err;
308 
309 	auth = crypto_spawn_ahash(&ictx->auth);
310 	if (IS_ERR(auth))
311 		return PTR_ERR(auth);
312 
313 	enc = crypto_spawn_skcipher(&ictx->enc);
314 	err = PTR_ERR(enc);
315 	if (IS_ERR(enc))
316 		goto err_free_ahash;
317 
318 	null = crypto_get_default_null_skcipher();
319 	err = PTR_ERR(null);
320 	if (IS_ERR(null))
321 		goto err_free_skcipher;
322 
323 	ctx->auth = auth;
324 	ctx->enc = enc;
325 	ctx->null = null;
326 
327 	crypto_aead_set_reqsize(
328 		tfm,
329 		sizeof(struct authenc_request_ctx) +
330 		ictx->reqoff +
331 		max_t(unsigned int,
332 		      crypto_ahash_reqsize(auth) +
333 		      sizeof(struct ahash_request),
334 		      sizeof(struct skcipher_request) +
335 		      crypto_skcipher_reqsize(enc)));
336 
337 	return 0;
338 
339 err_free_skcipher:
340 	crypto_free_skcipher(enc);
341 err_free_ahash:
342 	crypto_free_ahash(auth);
343 	return err;
344 }
345 
346 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
347 {
348 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
349 
350 	crypto_free_ahash(ctx->auth);
351 	crypto_free_skcipher(ctx->enc);
352 	crypto_put_default_null_skcipher();
353 }
354 
355 static void crypto_authenc_free(struct aead_instance *inst)
356 {
357 	struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
358 
359 	crypto_drop_skcipher(&ctx->enc);
360 	crypto_drop_ahash(&ctx->auth);
361 	kfree(inst);
362 }
363 
364 static int crypto_authenc_create(struct crypto_template *tmpl,
365 				 struct rtattr **tb)
366 {
367 	u32 mask;
368 	struct aead_instance *inst;
369 	struct authenc_instance_ctx *ctx;
370 	struct skcipher_alg_common *enc;
371 	struct hash_alg_common *auth;
372 	struct crypto_alg *auth_base;
373 	int err;
374 
375 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
376 	if (err)
377 		return err;
378 
379 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
380 	if (!inst)
381 		return -ENOMEM;
382 	ctx = aead_instance_ctx(inst);
383 
384 	err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
385 				crypto_attr_alg_name(tb[1]), 0, mask);
386 	if (err)
387 		goto err_free_inst;
388 	auth = crypto_spawn_ahash_alg(&ctx->auth);
389 	auth_base = &auth->base;
390 
391 	err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
392 				   crypto_attr_alg_name(tb[2]), 0, mask);
393 	if (err)
394 		goto err_free_inst;
395 	enc = crypto_spawn_skcipher_alg_common(&ctx->enc);
396 
397 	ctx->reqoff = 2 * auth->digestsize;
398 
399 	err = -ENAMETOOLONG;
400 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
401 		     "authenc(%s,%s)", auth_base->cra_name,
402 		     enc->base.cra_name) >=
403 	    CRYPTO_MAX_ALG_NAME)
404 		goto err_free_inst;
405 
406 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
407 		     "authenc(%s,%s)", auth_base->cra_driver_name,
408 		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
409 		goto err_free_inst;
410 
411 	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
412 				      auth_base->cra_priority;
413 	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
414 	inst->alg.base.cra_alignmask = enc->base.cra_alignmask;
415 	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
416 
417 	inst->alg.ivsize = enc->ivsize;
418 	inst->alg.chunksize = enc->chunksize;
419 	inst->alg.maxauthsize = auth->digestsize;
420 
421 	inst->alg.init = crypto_authenc_init_tfm;
422 	inst->alg.exit = crypto_authenc_exit_tfm;
423 
424 	inst->alg.setkey = crypto_authenc_setkey;
425 	inst->alg.encrypt = crypto_authenc_encrypt;
426 	inst->alg.decrypt = crypto_authenc_decrypt;
427 
428 	inst->free = crypto_authenc_free;
429 
430 	err = aead_register_instance(tmpl, inst);
431 	if (err) {
432 err_free_inst:
433 		crypto_authenc_free(inst);
434 	}
435 	return err;
436 }
437 
438 static struct crypto_template crypto_authenc_tmpl = {
439 	.name = "authenc",
440 	.create = crypto_authenc_create,
441 	.module = THIS_MODULE,
442 };
443 
444 static int __init crypto_authenc_module_init(void)
445 {
446 	return crypto_register_template(&crypto_authenc_tmpl);
447 }
448 
449 static void __exit crypto_authenc_module_exit(void)
450 {
451 	crypto_unregister_template(&crypto_authenc_tmpl);
452 }
453 
454 subsys_initcall(crypto_authenc_module_init);
455 module_exit(crypto_authenc_module_exit);
456 
457 MODULE_LICENSE("GPL");
458 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
459 MODULE_ALIAS_CRYPTO("authenc");
460