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(struct crypto_async_request * areq,int err)112 static void authenc_geniv_ahash_done(struct crypto_async_request *areq, int err)
113 {
114 	struct aead_request *req = areq->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(struct crypto_async_request * req,int err)163 static void crypto_authenc_encrypt_done(struct crypto_async_request *req,
164 					int err)
165 {
166 	struct aead_request *areq = req->data;
167 
168 	if (err)
169 		goto out;
170 
171 	err = crypto_authenc_genicv(areq, 0);
172 
173 out:
174 	authenc_request_complete(areq, err);
175 }
176 
crypto_authenc_copy_assoc(struct aead_request * req)177 static int crypto_authenc_copy_assoc(struct aead_request *req)
178 {
179 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
180 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
181 	SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
182 
183 	skcipher_request_set_sync_tfm(skreq, ctx->null);
184 	skcipher_request_set_callback(skreq, aead_request_flags(req),
185 				      NULL, NULL);
186 	skcipher_request_set_crypt(skreq, req->src, req->dst, req->assoclen,
187 				   NULL);
188 
189 	return crypto_skcipher_encrypt(skreq);
190 }
191 
crypto_authenc_encrypt(struct aead_request * req)192 static int crypto_authenc_encrypt(struct aead_request *req)
193 {
194 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
195 	struct aead_instance *inst = aead_alg_instance(authenc);
196 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
197 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
198 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
199 	struct crypto_skcipher *enc = ctx->enc;
200 	unsigned int cryptlen = req->cryptlen;
201 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
202 						  ictx->reqoff);
203 	struct scatterlist *src, *dst;
204 	int err;
205 
206 	src = scatterwalk_ffwd(areq_ctx->src, req->src, req->assoclen);
207 	dst = src;
208 
209 	if (req->src != req->dst) {
210 		err = crypto_authenc_copy_assoc(req);
211 		if (err)
212 			return err;
213 
214 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, req->assoclen);
215 	}
216 
217 	skcipher_request_set_tfm(skreq, enc);
218 	skcipher_request_set_callback(skreq, aead_request_flags(req),
219 				      crypto_authenc_encrypt_done, req);
220 	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
221 
222 	err = crypto_skcipher_encrypt(skreq);
223 	if (err)
224 		return err;
225 
226 	return crypto_authenc_genicv(req, aead_request_flags(req));
227 }
228 
crypto_authenc_decrypt_tail(struct aead_request * req,unsigned int flags)229 static int crypto_authenc_decrypt_tail(struct aead_request *req,
230 				       unsigned int flags)
231 {
232 	struct crypto_aead *authenc = crypto_aead_reqtfm(req);
233 	struct aead_instance *inst = aead_alg_instance(authenc);
234 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(authenc);
235 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
236 	struct authenc_request_ctx *areq_ctx = aead_request_ctx(req);
237 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ictx->reqoff);
238 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
239 						  ictx->reqoff);
240 	unsigned int authsize = crypto_aead_authsize(authenc);
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 				      req->base.complete, req->base.data);
258 	skcipher_request_set_crypt(skreq, src, dst,
259 				   req->cryptlen - authsize, req->iv);
260 
261 	return crypto_skcipher_decrypt(skreq);
262 }
263 
authenc_verify_ahash_done(struct crypto_async_request * areq,int err)264 static void authenc_verify_ahash_done(struct crypto_async_request *areq,
265 				      int err)
266 {
267 	struct aead_request *req = areq->data;
268 
269 	if (err)
270 		goto out;
271 
272 	err = crypto_authenc_decrypt_tail(req, 0);
273 
274 out:
275 	authenc_request_complete(req, err);
276 }
277 
crypto_authenc_decrypt(struct aead_request * req)278 static 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 	hash = (u8 *)ALIGN((unsigned long)hash + crypto_ahash_alignmask(auth),
292 			   crypto_ahash_alignmask(auth) + 1);
293 
294 	ahash_request_set_tfm(ahreq, auth);
295 	ahash_request_set_crypt(ahreq, req->src, hash,
296 				req->assoclen + req->cryptlen - authsize);
297 	ahash_request_set_callback(ahreq, aead_request_flags(req),
298 				   authenc_verify_ahash_done, req);
299 
300 	err = crypto_ahash_digest(ahreq);
301 	if (err)
302 		return err;
303 
304 	return crypto_authenc_decrypt_tail(req, aead_request_flags(req));
305 }
306 
crypto_authenc_init_tfm(struct crypto_aead * tfm)307 static int crypto_authenc_init_tfm(struct crypto_aead *tfm)
308 {
309 	struct aead_instance *inst = aead_alg_instance(tfm);
310 	struct authenc_instance_ctx *ictx = aead_instance_ctx(inst);
311 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
312 	struct crypto_ahash *auth;
313 	struct crypto_skcipher *enc;
314 	struct crypto_sync_skcipher *null;
315 	int err;
316 
317 	auth = crypto_spawn_ahash(&ictx->auth);
318 	if (IS_ERR(auth))
319 		return PTR_ERR(auth);
320 
321 	enc = crypto_spawn_skcipher(&ictx->enc);
322 	err = PTR_ERR(enc);
323 	if (IS_ERR(enc))
324 		goto err_free_ahash;
325 
326 	null = crypto_get_default_null_skcipher();
327 	err = PTR_ERR(null);
328 	if (IS_ERR(null))
329 		goto err_free_skcipher;
330 
331 	ctx->auth = auth;
332 	ctx->enc = enc;
333 	ctx->null = null;
334 
335 	crypto_aead_set_reqsize(
336 		tfm,
337 		sizeof(struct authenc_request_ctx) +
338 		ictx->reqoff +
339 		max_t(unsigned int,
340 		      crypto_ahash_reqsize(auth) +
341 		      sizeof(struct ahash_request),
342 		      sizeof(struct skcipher_request) +
343 		      crypto_skcipher_reqsize(enc)));
344 
345 	return 0;
346 
347 err_free_skcipher:
348 	crypto_free_skcipher(enc);
349 err_free_ahash:
350 	crypto_free_ahash(auth);
351 	return err;
352 }
353 
crypto_authenc_exit_tfm(struct crypto_aead * tfm)354 static void crypto_authenc_exit_tfm(struct crypto_aead *tfm)
355 {
356 	struct crypto_authenc_ctx *ctx = crypto_aead_ctx(tfm);
357 
358 	crypto_free_ahash(ctx->auth);
359 	crypto_free_skcipher(ctx->enc);
360 	crypto_put_default_null_skcipher();
361 }
362 
crypto_authenc_free(struct aead_instance * inst)363 static void crypto_authenc_free(struct aead_instance *inst)
364 {
365 	struct authenc_instance_ctx *ctx = aead_instance_ctx(inst);
366 
367 	crypto_drop_skcipher(&ctx->enc);
368 	crypto_drop_ahash(&ctx->auth);
369 	kfree(inst);
370 }
371 
crypto_authenc_create(struct crypto_template * tmpl,struct rtattr ** tb)372 static int crypto_authenc_create(struct crypto_template *tmpl,
373 				 struct rtattr **tb)
374 {
375 	u32 mask;
376 	struct aead_instance *inst;
377 	struct authenc_instance_ctx *ctx;
378 	struct hash_alg_common *auth;
379 	struct crypto_alg *auth_base;
380 	struct skcipher_alg *enc;
381 	int err;
382 
383 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
384 	if (err)
385 		return err;
386 
387 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
388 	if (!inst)
389 		return -ENOMEM;
390 	ctx = aead_instance_ctx(inst);
391 
392 	err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
393 				crypto_attr_alg_name(tb[1]), 0, mask);
394 	if (err)
395 		goto err_free_inst;
396 	auth = crypto_spawn_ahash_alg(&ctx->auth);
397 	auth_base = &auth->base;
398 
399 	err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
400 				   crypto_attr_alg_name(tb[2]), 0, mask);
401 	if (err)
402 		goto err_free_inst;
403 	enc = crypto_spawn_skcipher_alg(&ctx->enc);
404 
405 	ctx->reqoff = ALIGN(2 * auth->digestsize + auth_base->cra_alignmask,
406 			    auth_base->cra_alignmask + 1);
407 
408 	err = -ENAMETOOLONG;
409 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
410 		     "authenc(%s,%s)", auth_base->cra_name,
411 		     enc->base.cra_name) >=
412 	    CRYPTO_MAX_ALG_NAME)
413 		goto err_free_inst;
414 
415 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
416 		     "authenc(%s,%s)", auth_base->cra_driver_name,
417 		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
418 		goto err_free_inst;
419 
420 	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
421 				      auth_base->cra_priority;
422 	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
423 	inst->alg.base.cra_alignmask = auth_base->cra_alignmask |
424 				       enc->base.cra_alignmask;
425 	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_ctx);
426 
427 	inst->alg.ivsize = crypto_skcipher_alg_ivsize(enc);
428 	inst->alg.chunksize = crypto_skcipher_alg_chunksize(enc);
429 	inst->alg.maxauthsize = auth->digestsize;
430 
431 	inst->alg.init = crypto_authenc_init_tfm;
432 	inst->alg.exit = crypto_authenc_exit_tfm;
433 
434 	inst->alg.setkey = crypto_authenc_setkey;
435 	inst->alg.encrypt = crypto_authenc_encrypt;
436 	inst->alg.decrypt = crypto_authenc_decrypt;
437 
438 	inst->free = crypto_authenc_free;
439 
440 	err = aead_register_instance(tmpl, inst);
441 	if (err) {
442 err_free_inst:
443 		crypto_authenc_free(inst);
444 	}
445 	return err;
446 }
447 
448 static struct crypto_template crypto_authenc_tmpl = {
449 	.name = "authenc",
450 	.create = crypto_authenc_create,
451 	.module = THIS_MODULE,
452 };
453 
crypto_authenc_module_init(void)454 static int __init crypto_authenc_module_init(void)
455 {
456 	return crypto_register_template(&crypto_authenc_tmpl);
457 }
458 
crypto_authenc_module_exit(void)459 static void __exit crypto_authenc_module_exit(void)
460 {
461 	crypto_unregister_template(&crypto_authenc_tmpl);
462 }
463 
464 subsys_initcall(crypto_authenc_module_init);
465 module_exit(crypto_authenc_module_exit);
466 
467 MODULE_LICENSE("GPL");
468 MODULE_DESCRIPTION("Simple AEAD wrapper for IPsec");
469 MODULE_ALIAS_CRYPTO("authenc");
470