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 
authenc_request_complete(struct aead_request * req,int err)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 
crypto_authenc_extractkeys(struct crypto_authenc_keys * keys,const u8 * key,unsigned int keylen)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 
crypto_authenc_setkey(struct crypto_aead * authenc,const u8 * key,unsigned int keylen)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 
authenc_geniv_ahash_done(void * data,int err)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 
crypto_authenc_genicv(struct aead_request * req,unsigned int flags)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 	hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
145 			   crypto_ahash_alignmask(auth) + 1);
146 
147 	ahash_request_set_tfm(ahreq, auth);
148 	ahash_request_set_crypt(ahreq, req->dst, hash,
149 				req->assoclen + req->cryptlen);
150 	ahash_request_set_callback(ahreq, flags,
151 				   authenc_geniv_ahash_done, req);
152 
153 	err = crypto_ahash_digest(ahreq);
154 	if (err)
155 		return err;
156 
157 	scatterwalk_map_and_copy(hash, req->dst, req->assoclen + req->cryptlen,
158 				 crypto_aead_authsize(authenc), 1);
159 
160 	return 0;
161 }
162 
crypto_authenc_encrypt_done(void * data,int err)163 static void crypto_authenc_encrypt_done(void *data, int err)
164 {
165 	struct aead_request *areq = data;
166 
167 	if (err)
168 		goto out;
169 
170 	err = crypto_authenc_genicv(areq, 0);
171 
172 out:
173 	authenc_request_complete(areq, err);
174 }
175 
crypto_authenc_copy_assoc(struct aead_request * req)176 static int crypto_authenc_copy_assoc(struct aead_request *req)
177 {
178 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
179 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
180 	SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
181 
182 	skcipher_request_set_sync_tfm(skreq, ctx->null);
183 	skcipher_request_set_callback(skreq, aead_request_flags(req),
184 				      NULL, NULL);
185 	skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
186 				   NULL);
187 
188 	return crypto_skcipher_encrypt(skreq);
189 }
190 
crypto_authenc_encrypt(struct aead_request * req)191 static int crypto_authenc_encrypt(struct aead_request *req)
192 {
193 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
194 	struct aead_instance *inst = aead_alg_instance(authenc);
195 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
196 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
197 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
198 	struct crypto_skcipher *enc = ctx->enc;
199 	unsigned int cryptlen = req->cryptlen;
200 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
201 						  ictx->reqoff);
202 	struct scatterlist *src, *dst;
203 	int err;
204 
205 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
206 	dst = src;
207 
208 	if (req->src != req->dst) {
209 		err = crypto_authenc_copy_assoc(req);
210 		if (err)
211 			return err;
212 
213 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
214 	}
215 
216 	skcipher_request_set_tfm(skreq, enc);
217 	skcipher_request_set_callback(skreq, aead_request_flags(req),
218 				      crypto_authenc_encrypt_done, req);
219 	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
220 
221 	err = crypto_skcipher_encrypt(skreq);
222 	if (err)
223 		return err;
224 
225 	return crypto_authenc_genicv(req, aead_request_flags(req));
226 }
227 
crypto_authenc_decrypt_tail(struct aead_request * req,unsigned int flags)228 static int crypto_authenc_decrypt_tail(struct aead_request *req,
229 				       unsigned int flags)
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 	u8 *ihash = ahreq->result + authsize;
241 	struct scatterlist *src, *dst;
242 
243 	scatterwalk_map_and_copy(ihash, req->src, ahreq->nbytes, authsize, 0);
244 
245 	if (crypto_memneq(ihash, ahreq->result, authsize))
246 		return -EBADMSG;
247 
248 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
249 	dst = src;
250 
251 	if (req->src != req->dst)
252 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
253 
254 	skcipher_request_set_tfm(skreq, ctx->enc);
255 	skcipher_request_set_callback(skreq, flags,
256 				      req->base.complete, req->base.data);
257 	skcipher_request_set_crypt(skreq, src, dst,
258 				   req->cryptlen - authsize, req->iv);
259 
260 	return crypto_skcipher_decrypt(skreq);
261 }
262 
authenc_verify_ahash_done(void * data,int err)263 static void authenc_verify_ahash_done(void *data, int err)
264 {
265 	struct aead_request *req = data;
266 
267 	if (err)
268 		goto out;
269 
270 	err = crypto_authenc_decrypt_tail(req, 0);
271 
272 out:
273 	authenc_request_complete(req, err);
274 }
275 
crypto_authenc_decrypt(struct aead_request * req)276 static int crypto_authenc_decrypt(struct aead_request *req)
277 {
278 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
279 	unsigned int authsize = crypto_aead_authsize(authenc);
280 	struct aead_instance *inst = aead_alg_instance(authenc);
281 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
282 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
283 	struct crypto_ahash *auth = ctx->auth;
284 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
285 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
286 	u8 *hash = areq_ctx->tail;
287 	int err;
288 
289 	hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
290 			   crypto_ahash_alignmask(auth) + 1);
291 
292 	ahash_request_set_tfm(ahreq, auth);
293 	ahash_request_set_crypt(ahreq, req->src, hash,
294 				req->assoclen + req->cryptlen - authsize);
295 	ahash_request_set_callback(ahreq, aead_request_flags(req),
296 				   authenc_verify_ahash_done, req);
297 
298 	err = crypto_ahash_digest(ahreq);
299 	if (err)
300 		return err;
301 
302 	return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
303 }
304 
crypto_authenc_init_tfm(struct crypto_aead * tfm)305 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
306 {
307 	struct aead_instance *inst = aead_alg_instance(tfm);
308 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
309 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
310 	struct crypto_ahash *auth;
311 	struct crypto_skcipher *enc;
312 	struct crypto_sync_skcipher *null;
313 	int err;
314 
315 	auth = crypto_spawn_ahash(&ictx->auth);
316 	if (IS_ERR(auth))
317 		return PTR_ERR(auth);
318 
319 	enc = crypto_spawn_skcipher(&ictx->enc);
320 	err = PTR_ERR(enc);
321 	if (IS_ERR(enc))
322 		goto err_free_ahash;
323 
324 	null = crypto_get_default_null_skcipher();
325 	err = PTR_ERR(null);
326 	if (IS_ERR(null))
327 		goto err_free_skcipher;
328 
329 	ctx->auth = auth;
330 	ctx->enc = enc;
331 	ctx->null = null;
332 
333 	crypto_aead_set_reqsize(
334 		tfm,
335 		sizeof(struct authenc_request_ctx) +
336 		ictx->reqoff +
337 		max_t(unsigned int,
338 		      crypto_ahash_reqsize(auth) +
339 		      sizeof(struct ahash_request),
340 		      sizeof(struct skcipher_request) +
341 		      crypto_skcipher_reqsize(enc)));
342 
343 	return 0;
344 
345 err_free_skcipher:
346 	crypto_free_skcipher(enc);
347 err_free_ahash:
348 	crypto_free_ahash(auth);
349 	return err;
350 }
351 
crypto_authenc_exit_tfm(struct crypto_aead * tfm)352 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
353 {
354 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
355 
356 	crypto_free_ahash(ctx->auth);
357 	crypto_free_skcipher(ctx->enc);
358 	crypto_put_default_null_skcipher();
359 }
360 
crypto_authenc_free(struct aead_instance * inst)361 static void crypto_authenc_free(struct aead_instance *inst)
362 {
363 	struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
364 
365 	crypto_drop_skcipher(&ctx->enc);
366 	crypto_drop_ahash(&ctx->auth);
367 	kfree(inst);
368 }
369 
crypto_authenc_create(struct crypto_template * tmpl,struct rtattr ** tb)370 static int crypto_authenc_create(struct crypto_template *tmpl,
371 				 struct rtattr **tb)
372 {
373 	u32 mask;
374 	struct aead_instance *inst;
375 	struct authenc_instance_ctx *ctx;
376 	struct hash_alg_common *auth;
377 	struct crypto_alg *auth_base;
378 	struct skcipher_alg *enc;
379 	int err;
380 
381 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
382 	if (err)
383 		return err;
384 
385 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
386 	if (!inst)
387 		return -ENOMEM;
388 	ctx = aead_instance_ctx(inst);
389 
390 	err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
391 				crypto_attr_alg_name(tb[1]), 0, mask);
392 	if (err)
393 		goto err_free_inst;
394 	auth = crypto_spawn_ahash_alg(&ctx->auth);
395 	auth_base = &auth->base;
396 
397 	err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
398 				   crypto_attr_alg_name(tb[2]), 0, mask);
399 	if (err)
400 		goto err_free_inst;
401 	enc = crypto_spawn_skcipher_alg(&ctx->enc);
402 
403 	ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
404 			    auth_base->cra_alignmask + 1);
405 
406 	err = -ENAMETOOLONG;
407 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
408 		     "authenc(%s,%s)", auth_base->cra_name,
409 		     enc->base.cra_name) >=
410 	    CRYPTO_MAX_ALG_NAME)
411 		goto err_free_inst;
412 
413 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
414 		     "authenc(%s,%s)", auth_base->cra_driver_name,
415 		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
416 		goto err_free_inst;
417 
418 	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
419 				      auth_base->cra_priority;
420 	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
421 	inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
422 				       enc->base.cra_alignmask;
423 	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
424 
425 	inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
426 	inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
427 	inst->alg.maxauthsize = auth->digestsize;
428 
429 	inst->alg.init = crypto_authenc_init_tfm;
430 	inst->alg.exit = crypto_authenc_exit_tfm;
431 
432 	inst->alg.setkey = crypto_authenc_setkey;
433 	inst->alg.encrypt = crypto_authenc_encrypt;
434 	inst->alg.decrypt = crypto_authenc_decrypt;
435 
436 	inst->free = crypto_authenc_free;
437 
438 	err = aead_register_instance(tmpl, inst);
439 	if (err) {
440 err_free_inst:
441 		crypto_authenc_free(inst);
442 	}
443 	return err;
444 }
445 
446 static struct crypto_template crypto_authenc_tmpl = {
447 	.name = "authenc",
448 	.create = crypto_authenc_create,
449 	.module = THIS_MODULE,
450 };
451 
crypto_authenc_module_init(void)452 static int __init crypto_authenc_module_init(void)
453 {
454 	return crypto_register_template(&crypto_authenc_tmpl);
455 }
456 
crypto_authenc_module_exit(void)457 static void __exit crypto_authenc_module_exit(void)
458 {
459 	crypto_unregister_template(&crypto_authenc_tmpl);
460 }
461 
462 subsys_initcall(crypto_authenc_module_init);
463 module_exit(crypto_authenc_module_exit);
464 
465 MODULE_LICENSE("GPL");
466 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
467 MODULE_ALIAS_CRYPTO("authenc");
468