authenc.c

  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/scatterwalk.h>
 13#include <linux/err.h>
 14#include <linux/init.h>
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <linux/rtnetlink.h>
 18#include <linux/slab.h>
 19#include <linux/spinlock.h>
 20
 21struct authenc_instance_ctx {
 22	struct crypto_ahash_spawn auth;
 23	struct crypto_skcipher_spawn enc;
 24	unsigned int reqoff;
 25};
 26
 27struct crypto_authenc_ctx {
 28	struct crypto_ahash *auth;
 29	struct crypto_skcipher *enc;
 30};
 31
 32struct authenc_request_ctx {
 33	struct scatterlist src[2];
 34	struct scatterlist dst[2];
 35	char tail[];
 36};
 37
 38static void authenc_request_complete(struct aead_request *req, int err)
 39{
 40	if (err != -EINPROGRESS && err != -EBUSY)
 41		aead_request_complete(req, err);
 42}
 43
 44int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key,
 45			       unsigned int keylen)
 46{
 47	struct rtattr *rta = (struct rtattr *)key;
 48	struct crypto_authenc_key_param *param;
 49
 50	if (!RTA_OK(rta, keylen))
 51		return -EINVAL;
 52	if (rta->rta_type != CRYPTO_AUTHENC_KEYA_PARAM)
 53		return -EINVAL;
 54
 55	/*
 56	 * RTA_OK() didn't align the rtattr's payload when validating that it
 57	 * fits in the buffer.  Yet, the keys should start on the next 4-byte
 58	 * aligned boundary.  To avoid confusion, require that the rtattr
 59	 * payload be exactly the param struct, which has a 4-byte aligned size.
 60	 */
 61	if (RTA_PAYLOAD(rta) != sizeof(*param))
 62		return -EINVAL;
 63	BUILD_BUG_ON(sizeof(*param) % RTA_ALIGNTO);
 64
 65	param = RTA_DATA(rta);
 66	keys->enckeylen = be32_to_cpu(param->enckeylen);
 67
 68	key += rta->rta_len;
 69	keylen -= rta->rta_len;
 70
 71	if (keylen < keys->enckeylen)
 72		return -EINVAL;
 73
 74	keys->authkeylen = keylen - keys->enckeylen;
 75	keys->authkey = key;
 76	keys->enckey = key + keys->authkeylen;
 77
 78	return 0;
 79}
 80EXPORT_SYMBOL_GPL(crypto_authenc_extractkeys);
 81
 82static int crypto_authenc_setkey(struct crypto_aead *authenc, const u8 *key,
 83				 unsigned int keylen)
 84{
 85	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
 86	struct crypto_ahash *auth = ctx->auth;
 87	struct crypto_skcipher *enc = ctx->enc;
 88	struct crypto_authenc_keys keys;
 89	int err = -EINVAL;
 90
 91	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
 92		goto out;
 93
 94	crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
 95	crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc) &
 96				    CRYPTO_TFM_REQ_MASK);
 97	err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
 98	if (err)
 99		goto out;
100
101	crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
102	crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc) &
103				       CRYPTO_TFM_REQ_MASK);
104	err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
105out:
106	memzero_explicit(&keys, sizeof(keys));
107	return err;
108}
109
110static void authenc_geniv_ahash_finish(struct aead_request *req)
111{
112	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
113	struct aead_instance *inst = aead_alg_instance(authenc);
114	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
115	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
116	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
117
118	scatterwalk_map_and_copy(ahreq->result, req->dst,
119				 req->assoclen + req->cryptlen,
120				 crypto_aead_authsize(authenc), 1);
121}
122
123static void authenc_geniv_ahash_done(void *data, int err)
124{
125	struct aead_request *req = data;
126
127	if (!err)
128		authenc_geniv_ahash_finish(req);
129	aead_request_complete(req, err);
130}
131
132/*
133 * Used when the ahash request was invoked in the async callback context
134 * of the previous skcipher request.  Eat any EINPROGRESS notifications.
135 */
136static void authenc_geniv_ahash_done2(void *data, int err)
137{
138	struct aead_request *req = data;
139
140	if (!err)
141		authenc_geniv_ahash_finish(req);
142	authenc_request_complete(req, err);
143}
144
145static int crypto_authenc_genicv(struct aead_request *req, unsigned int mask)
146{
147	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
148	struct aead_instance *inst = aead_alg_instance(authenc);
149	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
150	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
151	struct crypto_ahash *auth = ctx->auth;
152	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
153	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
154	unsigned int flags = aead_request_flags(req) & ~mask;
155	u8 *hash = areq_ctx->tail;
156	int err;
157
158	ahash_request_set_tfm(ahreq, auth);
159	ahash_request_set_crypt(ahreq, req->dst, hash,
160				req->assoclen + req->cryptlen);
161	ahash_request_set_callback(ahreq, flags,
162				   mask ? authenc_geniv_ahash_done2 :
163					  authenc_geniv_ahash_done, req);
164
165	err = crypto_ahash_digest(ahreq);
166	if (err)
167		return err;
168
169	scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
170				 crypto_aead_authsize(authenc), 1);
171
172	return 0;
173}
174
175static void crypto_authenc_encrypt_done(void *data, int err)
176{
177	struct aead_request *areq = data;
178
179	if (err) {
180		aead_request_complete(areq, err);
181		return;
182	}
183	err = crypto_authenc_genicv(areq, CRYPTO_TFM_REQ_MAY_SLEEP);
184	authenc_request_complete(areq, err);
185}
186
187static int crypto_authenc_encrypt(struct aead_request *req)
188{
189	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
190	struct aead_instance *inst = aead_alg_instance(authenc);
191	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
192	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
193	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
194	struct crypto_skcipher *enc = ctx->enc;
195	unsigned int cryptlen = req->cryptlen;
196	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
197						  ictx->reqoff);
198	struct scatterlist *src, *dst;
199	int err;
200
201	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
202	dst = src;
203
204	if (req->src != req->dst) {
205		memcpy_sglist(req->dst, req->src, req->assoclen);
206		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
207	}
208
209	skcipher_request_set_tfm(skreq, enc);
210	skcipher_request_set_callback(skreq, aead_request_flags(req),
211				      crypto_authenc_encrypt_done, req);
212	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
213
214	err = crypto_skcipher_encrypt(skreq);
215	if (err)
216		return err;
217
218	return crypto_authenc_genicv(req, 0);
219}
220
221static void authenc_decrypt_tail_done(void *data, int err)
222{
223	struct aead_request *req = data;
224
225	authenc_request_complete(req, err);
226}
227
228static int crypto_authenc_decrypt_tail(struct aead_request *req,
229				       unsigned int mask)
230{
231	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
232	struct aead_instance *inst = aead_alg_instance(authenc);
233	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
234	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
235	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
236	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
237	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
238						  ictx->reqoff);
239	unsigned int authsize = crypto_aead_authsize(authenc);
240	unsigned int flags = aead_request_flags(req) & ~mask;
241	u8 *ihash = ahreq->result + authsize;
242	struct scatterlist *src, *dst;
243
244	scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
245
246	if (crypto_memneq(ihash, ahreq->result, authsize))
247		return -EBADMSG;
248
249	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
250	dst = src;
251
252	if (req->src != req->dst)
253		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
254
255	skcipher_request_set_tfm(skreq, ctx->enc);
256	skcipher_request_set_callback(skreq, flags,
257				      mask ? authenc_decrypt_tail_done :
258					     req->base.complete,
259				      mask ? req : req->base.data);
260	skcipher_request_set_crypt(skreq, src, dst,
261				   req->cryptlen - authsize, req->iv);
262
263	return crypto_skcipher_decrypt(skreq);
264}
265
266static void authenc_verify_ahash_done(void *data, int err)
267{
268	struct aead_request *req = data;
269
270	if (err) {
271		aead_request_complete(req, err);
272		return;
273	}
274	err = crypto_authenc_decrypt_tail(req, CRYPTO_TFM_REQ_MAY_SLEEP);
275	authenc_request_complete(req, err);
276}
277
278static int crypto_authenc_decrypt(struct aead_request *req)
279{
280	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
281	unsigned int authsize = crypto_aead_authsize(authenc);
282	struct aead_instance *inst = aead_alg_instance(authenc);
283	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
284	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
285	struct crypto_ahash *auth = ctx->auth;
286	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
287	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
288	u8 *hash = areq_ctx->tail;
289	int err;
290
291	ahash_request_set_tfm(ahreq, auth);
292	ahash_request_set_crypt(ahreq, req->src, hash,
293				req->assoclen + req->cryptlen - authsize);
294	ahash_request_set_callback(ahreq, aead_request_flags(req),
295				   authenc_verify_ahash_done, req);
296
297	err = crypto_ahash_digest(ahreq);
298	if (err)
299		return err;
300
301	return crypto_authenc_decrypt_tail(req, 0);
302}
303
304static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
305{
306	struct aead_instance *inst = aead_alg_instance(tfm);
307	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
308	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
309	struct crypto_ahash *auth;
310	struct crypto_skcipher *enc;
311	int err;
312
313	auth = crypto_spawn_ahash(&ictx->auth);
314	if (IS_ERR(auth))
315		return PTR_ERR(auth);
316
317	enc = crypto_spawn_skcipher(&ictx->enc);
318	err = PTR_ERR(enc);
319	if (IS_ERR(enc))
320		goto err_free_ahash;
321
322	ctx->auth = auth;
323	ctx->enc = enc;
324
325	crypto_aead_set_reqsize(
326		tfm,
327		sizeof(struct authenc_request_ctx) +
328		ictx->reqoff +
329		max_t(unsigned int,
330		      crypto_ahash_reqsize(auth) +
331		      sizeof(struct ahash_request),
332		      sizeof(struct skcipher_request) +
333		      crypto_skcipher_reqsize(enc)));
334
335	return 0;
336
337err_free_ahash:
338	crypto_free_ahash(auth);
339	return err;
340}
341
342static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
343{
344	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
345
346	crypto_free_ahash(ctx->auth);
347	crypto_free_skcipher(ctx->enc);
348}
349
350static void crypto_authenc_free(struct aead_instance *inst)
351{
352	struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
353
354	crypto_drop_skcipher(&ctx->enc);
355	crypto_drop_ahash(&ctx->auth);
356	kfree(inst);
357}
358
359static int crypto_authenc_create(struct crypto_template *tmpl,
360				 struct rtattr **tb)
361{
362	u32 mask;
363	struct aead_instance *inst;
364	struct authenc_instance_ctx *ctx;
365	struct skcipher_alg_common *enc;
366	struct hash_alg_common *auth;
367	struct crypto_alg *auth_base;
368	int err;
369
370	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
371	if (err)
372		return err;
373
374	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
375	if (!inst)
376		return -ENOMEM;
377	ctx = aead_instance_ctx(inst);
378
379	err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
380				crypto_attr_alg_name(tb[1]), 0, mask);
381	if (err)
382		goto err_free_inst;
383	auth = crypto_spawn_ahash_alg(&ctx->auth);
384	auth_base = &auth->base;
385
386	err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
387				   crypto_attr_alg_name(tb[2]), 0, mask);
388	if (err)
389		goto err_free_inst;
390	enc = crypto_spawn_skcipher_alg_common(&ctx->enc);
391
392	ctx->reqoff = 2 * auth->digestsize;
393
394	err = -ENAMETOOLONG;
395	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
396		     "authenc(%s,%s)", auth_base->cra_name,
397		     enc->base.cra_name) >=
398	    CRYPTO_MAX_ALG_NAME)
399		goto err_free_inst;
400
401	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
402		     "authenc(%s,%s)", auth_base->cra_driver_name,
403		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
404		goto err_free_inst;
405
406	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
407				      auth_base->cra_priority;
408	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
409	inst->alg.base.cra_alignmask = enc->base.cra_alignmask;
410	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
411
412	inst->alg.ivsize = enc->ivsize;
413	inst->alg.chunksize = enc->chunksize;
414	inst->alg.maxauthsize = auth->digestsize;
415
416	inst->alg.init = crypto_authenc_init_tfm;
417	inst->alg.exit = crypto_authenc_exit_tfm;
418
419	inst->alg.setkey = crypto_authenc_setkey;
420	inst->alg.encrypt = crypto_authenc_encrypt;
421	inst->alg.decrypt = crypto_authenc_decrypt;
422
423	inst->free = crypto_authenc_free;
424
425	err = aead_register_instance(tmpl, inst);
426	if (err) {
427err_free_inst:
428		crypto_authenc_free(inst);
429	}
430	return err;
431}
432
433static struct crypto_template crypto_authenc_tmpl = {
434	.name = "authenc",
435	.create = crypto_authenc_create,
436	.module = THIS_MODULE,
437};
438
439static int __init crypto_authenc_module_init(void)
440{
441	return crypto_register_template(&crypto_authenc_tmpl);
442}
443
444static void __exit crypto_authenc_module_exit(void)
445{
446	crypto_unregister_template(&crypto_authenc_tmpl);
447}
448
449module_init(crypto_authenc_module_init);
450module_exit(crypto_authenc_module_exit);
451
452MODULE_LICENSE("GPL");
453MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
454MODULE_ALIAS_CRYPTO("authenc");