1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * authencesn.c - AEAD wrapper for IPsec with extended sequence numbers,
4  *                 derived from authenc.c
5  *
6  * Copyright (C) 2010 secunet Security Networks AG
7  * Copyright (C) 2010 Steffen Klassert <steffen.klassert@secunet.com>
8  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
9  */
10 
11 #include <crypto/internal/aead.h>
12 #include <crypto/internal/hash.h>
13 #include <crypto/internal/skcipher.h>
14 #include <crypto/authenc.h>
15 #include <crypto/null.h>
16 #include <crypto/scatterwalk.h>
17 #include <linux/err.h>
18 #include <linux/init.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/rtnetlink.h>
22 #include <linux/slab.h>
23 #include <linux/spinlock.h>
24 
25 struct authenc_esn_instance_ctx {
26 	struct crypto_ahash_spawn auth;
27 	struct crypto_skcipher_spawn enc;
28 };
29 
30 struct crypto_authenc_esn_ctx {
31 	unsigned int reqoff;
32 	struct crypto_ahash *auth;
33 	struct crypto_skcipher *enc;
34 	struct crypto_sync_skcipher *null;
35 };
36 
37 struct authenc_esn_request_ctx {
38 	struct scatterlist src[2];
39 	struct scatterlist dst[2];
40 	char tail[];
41 };
42 
authenc_esn_request_complete(struct aead_request * req,int err)43 static void authenc_esn_request_complete(struct aead_request *req, int err)
44 {
45 	if (err != -EINPROGRESS)
46 		aead_request_complete(req, err);
47 }
48 
crypto_authenc_esn_setauthsize(struct crypto_aead * authenc_esn,unsigned int authsize)49 static int crypto_authenc_esn_setauthsize(struct crypto_aead *authenc_esn,
50 					  unsigned int authsize)
51 {
52 	if (authsize > 0 && authsize < 4)
53 		return -EINVAL;
54 
55 	return 0;
56 }
57 
crypto_authenc_esn_setkey(struct crypto_aead * authenc_esn,const u8 * key,unsigned int keylen)58 static int crypto_authenc_esn_setkey(struct crypto_aead *authenc_esn, const u8 *key,
59 				     unsigned int keylen)
60 {
61 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
62 	struct crypto_ahash *auth = ctx->auth;
63 	struct crypto_skcipher *enc = ctx->enc;
64 	struct crypto_authenc_keys keys;
65 	int err = -EINVAL;
66 
67 	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
68 		goto out;
69 
70 	crypto_ahash_clear_flags(auth, CRYPTO_TFM_REQ_MASK);
71 	crypto_ahash_set_flags(auth, crypto_aead_get_flags(authenc_esn) &
72 				     CRYPTO_TFM_REQ_MASK);
73 	err = crypto_ahash_setkey(auth, keys.authkey, keys.authkeylen);
74 	if (err)
75 		goto out;
76 
77 	crypto_skcipher_clear_flags(enc, CRYPTO_TFM_REQ_MASK);
78 	crypto_skcipher_set_flags(enc, crypto_aead_get_flags(authenc_esn) &
79 					 CRYPTO_TFM_REQ_MASK);
80 	err = crypto_skcipher_setkey(enc, keys.enckey, keys.enckeylen);
81 out:
82 	memzero_explicit(&keys, sizeof(keys));
83 	return err;
84 }
85 
crypto_authenc_esn_genicv_tail(struct aead_request * req,unsigned int flags)86 static int crypto_authenc_esn_genicv_tail(struct aead_request *req,
87 					  unsigned int flags)
88 {
89 	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
90 	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
91 	u8 *hash = areq_ctx->tail;
92 	unsigned int authsize = crypto_aead_authsize(authenc_esn);
93 	unsigned int assoclen = req->assoclen;
94 	unsigned int cryptlen = req->cryptlen;
95 	struct scatterlist *dst = req->dst;
96 	u32 tmp[2];
97 
98 	/* Move high-order bits of sequence number back. */
99 	scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
100 	scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
101 	scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
102 
103 	scatterwalk_map_and_copy(hash, dst, assoclen + cryptlen, authsize, 1);
104 	return 0;
105 }
106 
authenc_esn_geniv_ahash_done(void * data,int err)107 static void authenc_esn_geniv_ahash_done(void *data, int err)
108 {
109 	struct aead_request *req = data;
110 
111 	err = err ?: crypto_authenc_esn_genicv_tail(req, 0);
112 	aead_request_complete(req, err);
113 }
114 
crypto_authenc_esn_genicv(struct aead_request * req,unsigned int flags)115 static int crypto_authenc_esn_genicv(struct aead_request *req,
116 				     unsigned int flags)
117 {
118 	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
119 	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
120 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
121 	struct crypto_ahash *auth = ctx->auth;
122 	u8 *hash = areq_ctx->tail;
123 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
124 	unsigned int authsize = crypto_aead_authsize(authenc_esn);
125 	unsigned int assoclen = req->assoclen;
126 	unsigned int cryptlen = req->cryptlen;
127 	struct scatterlist *dst = req->dst;
128 	u32 tmp[2];
129 
130 	if (!authsize)
131 		return 0;
132 
133 	/* Move high-order bits of sequence number to the end. */
134 	scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
135 	scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
136 	scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
137 
138 	sg_init_table(areq_ctx->dst, 2);
139 	dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
140 
141 	ahash_request_set_tfm(ahreq, auth);
142 	ahash_request_set_crypt(ahreq, dst, hash, assoclen + cryptlen);
143 	ahash_request_set_callback(ahreq, flags,
144 				   authenc_esn_geniv_ahash_done, req);
145 
146 	return crypto_ahash_digest(ahreq) ?:
147 	       crypto_authenc_esn_genicv_tail(req, aead_request_flags(req));
148 }
149 
150 
crypto_authenc_esn_encrypt_done(void * data,int err)151 static void crypto_authenc_esn_encrypt_done(void *data, int err)
152 {
153 	struct aead_request *areq = data;
154 
155 	if (!err)
156 		err = crypto_authenc_esn_genicv(areq, 0);
157 
158 	authenc_esn_request_complete(areq, err);
159 }
160 
crypto_authenc_esn_copy(struct aead_request * req,unsigned int len)161 static int crypto_authenc_esn_copy(struct aead_request *req, unsigned int len)
162 {
163 	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
164 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
165 	SYNC_SKCIPHER_REQUEST_ON_STACK(skreq, ctx->null);
166 
167 	skcipher_request_set_sync_tfm(skreq, ctx->null);
168 	skcipher_request_set_callback(skreq, aead_request_flags(req),
169 				      NULL, NULL);
170 	skcipher_request_set_crypt(skreq, req->src, req->dst, len, NULL);
171 
172 	return crypto_skcipher_encrypt(skreq);
173 }
174 
crypto_authenc_esn_encrypt(struct aead_request * req)175 static int crypto_authenc_esn_encrypt(struct aead_request *req)
176 {
177 	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
178 	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
179 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
180 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
181 						  ctx->reqoff);
182 	struct crypto_skcipher *enc = ctx->enc;
183 	unsigned int assoclen = req->assoclen;
184 	unsigned int cryptlen = req->cryptlen;
185 	struct scatterlist *src, *dst;
186 	int err;
187 
188 	sg_init_table(areq_ctx->src, 2);
189 	src = scatterwalk_ffwd(areq_ctx->src, req->src, assoclen);
190 	dst = src;
191 
192 	if (req->src != req->dst) {
193 		err = crypto_authenc_esn_copy(req, assoclen);
194 		if (err)
195 			return err;
196 
197 		sg_init_table(areq_ctx->dst, 2);
198 		dst = scatterwalk_ffwd(areq_ctx->dst, req->dst, assoclen);
199 	}
200 
201 	skcipher_request_set_tfm(skreq, enc);
202 	skcipher_request_set_callback(skreq, aead_request_flags(req),
203 				      crypto_authenc_esn_encrypt_done, req);
204 	skcipher_request_set_crypt(skreq, src, dst, cryptlen, req->iv);
205 
206 	err = crypto_skcipher_encrypt(skreq);
207 	if (err)
208 		return err;
209 
210 	return crypto_authenc_esn_genicv(req, aead_request_flags(req));
211 }
212 
crypto_authenc_esn_decrypt_tail(struct aead_request * req,unsigned int flags)213 static int crypto_authenc_esn_decrypt_tail(struct aead_request *req,
214 					   unsigned int flags)
215 {
216 	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
217 	unsigned int authsize = crypto_aead_authsize(authenc_esn);
218 	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
219 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
220 	struct skcipher_request *skreq = (void *)(areq_ctx->tail +
221 						  ctx->reqoff);
222 	struct crypto_ahash *auth = ctx->auth;
223 	u8 *ohash = areq_ctx->tail;
224 	unsigned int cryptlen = req->cryptlen - authsize;
225 	unsigned int assoclen = req->assoclen;
226 	struct scatterlist *dst = req->dst;
227 	u8 *ihash = ohash + crypto_ahash_digestsize(auth);
228 	u32 tmp[2];
229 
230 	if (!authsize)
231 		goto decrypt;
232 
233 	/* Move high-order bits of sequence number back. */
234 	scatterwalk_map_and_copy(tmp, dst, 4, 4, 0);
235 	scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 0);
236 	scatterwalk_map_and_copy(tmp, dst, 0, 8, 1);
237 
238 	if (crypto_memneq(ihash, ohash, authsize))
239 		return -EBADMSG;
240 
241 decrypt:
242 
243 	sg_init_table(areq_ctx->dst, 2);
244 	dst = scatterwalk_ffwd(areq_ctx->dst, dst, assoclen);
245 
246 	skcipher_request_set_tfm(skreq, ctx->enc);
247 	skcipher_request_set_callback(skreq, flags,
248 				      req->base.complete, req->base.data);
249 	skcipher_request_set_crypt(skreq, dst, dst, cryptlen, req->iv);
250 
251 	return crypto_skcipher_decrypt(skreq);
252 }
253 
authenc_esn_verify_ahash_done(void * data,int err)254 static void authenc_esn_verify_ahash_done(void *data, int err)
255 {
256 	struct aead_request *req = data;
257 
258 	err = err ?: crypto_authenc_esn_decrypt_tail(req, 0);
259 	authenc_esn_request_complete(req, err);
260 }
261 
crypto_authenc_esn_decrypt(struct aead_request * req)262 static int crypto_authenc_esn_decrypt(struct aead_request *req)
263 {
264 	struct crypto_aead *authenc_esn = crypto_aead_reqtfm(req);
265 	struct authenc_esn_request_ctx *areq_ctx = aead_request_ctx(req);
266 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(authenc_esn);
267 	struct ahash_request *ahreq = (void *)(areq_ctx->tail + ctx->reqoff);
268 	unsigned int authsize = crypto_aead_authsize(authenc_esn);
269 	struct crypto_ahash *auth = ctx->auth;
270 	u8 *ohash = areq_ctx->tail;
271 	unsigned int assoclen = req->assoclen;
272 	unsigned int cryptlen = req->cryptlen;
273 	u8 *ihash = ohash + crypto_ahash_digestsize(auth);
274 	struct scatterlist *dst = req->dst;
275 	u32 tmp[2];
276 	int err;
277 
278 	cryptlen -= authsize;
279 
280 	if (req->src != dst) {
281 		err = crypto_authenc_esn_copy(req, assoclen + cryptlen);
282 		if (err)
283 			return err;
284 	}
285 
286 	scatterwalk_map_and_copy(ihash, req->src, assoclen + cryptlen,
287 				 authsize, 0);
288 
289 	if (!authsize)
290 		goto tail;
291 
292 	/* Move high-order bits of sequence number to the end. */
293 	scatterwalk_map_and_copy(tmp, dst, 0, 8, 0);
294 	scatterwalk_map_and_copy(tmp, dst, 4, 4, 1);
295 	scatterwalk_map_and_copy(tmp + 1, dst, assoclen + cryptlen, 4, 1);
296 
297 	sg_init_table(areq_ctx->dst, 2);
298 	dst = scatterwalk_ffwd(areq_ctx->dst, dst, 4);
299 
300 	ahash_request_set_tfm(ahreq, auth);
301 	ahash_request_set_crypt(ahreq, dst, ohash, assoclen + cryptlen);
302 	ahash_request_set_callback(ahreq, aead_request_flags(req),
303 				   authenc_esn_verify_ahash_done, req);
304 
305 	err = crypto_ahash_digest(ahreq);
306 	if (err)
307 		return err;
308 
309 tail:
310 	return crypto_authenc_esn_decrypt_tail(req, aead_request_flags(req));
311 }
312 
crypto_authenc_esn_init_tfm(struct crypto_aead * tfm)313 static int crypto_authenc_esn_init_tfm(struct crypto_aead *tfm)
314 {
315 	struct aead_instance *inst = aead_alg_instance(tfm);
316 	struct authenc_esn_instance_ctx *ictx = aead_instance_ctx(inst);
317 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
318 	struct crypto_ahash *auth;
319 	struct crypto_skcipher *enc;
320 	struct crypto_sync_skcipher *null;
321 	int err;
322 
323 	auth = crypto_spawn_ahash(&ictx->auth);
324 	if (IS_ERR(auth))
325 		return PTR_ERR(auth);
326 
327 	enc = crypto_spawn_skcipher(&ictx->enc);
328 	err = PTR_ERR(enc);
329 	if (IS_ERR(enc))
330 		goto err_free_ahash;
331 
332 	null = crypto_get_default_null_skcipher();
333 	err = PTR_ERR(null);
334 	if (IS_ERR(null))
335 		goto err_free_skcipher;
336 
337 	ctx->auth = auth;
338 	ctx->enc = enc;
339 	ctx->null = null;
340 
341 	ctx->reqoff = 2 * crypto_ahash_digestsize(auth);
342 
343 	crypto_aead_set_reqsize(
344 		tfm,
345 		sizeof(struct authenc_esn_request_ctx) +
346 		ctx->reqoff +
347 		max_t(unsigned int,
348 		      crypto_ahash_reqsize(auth) +
349 		      sizeof(struct ahash_request),
350 		      sizeof(struct skcipher_request) +
351 		      crypto_skcipher_reqsize(enc)));
352 
353 	return 0;
354 
355 err_free_skcipher:
356 	crypto_free_skcipher(enc);
357 err_free_ahash:
358 	crypto_free_ahash(auth);
359 	return err;
360 }
361 
crypto_authenc_esn_exit_tfm(struct crypto_aead * tfm)362 static void crypto_authenc_esn_exit_tfm(struct crypto_aead *tfm)
363 {
364 	struct crypto_authenc_esn_ctx *ctx = crypto_aead_ctx(tfm);
365 
366 	crypto_free_ahash(ctx->auth);
367 	crypto_free_skcipher(ctx->enc);
368 	crypto_put_default_null_skcipher();
369 }
370 
crypto_authenc_esn_free(struct aead_instance * inst)371 static void crypto_authenc_esn_free(struct aead_instance *inst)
372 {
373 	struct authenc_esn_instance_ctx *ctx = aead_instance_ctx(inst);
374 
375 	crypto_drop_skcipher(&ctx->enc);
376 	crypto_drop_ahash(&ctx->auth);
377 	kfree(inst);
378 }
379 
crypto_authenc_esn_create(struct crypto_template * tmpl,struct rtattr ** tb)380 static int crypto_authenc_esn_create(struct crypto_template *tmpl,
381 				     struct rtattr **tb)
382 {
383 	u32 mask;
384 	struct aead_instance *inst;
385 	struct authenc_esn_instance_ctx *ctx;
386 	struct skcipher_alg_common *enc;
387 	struct hash_alg_common *auth;
388 	struct crypto_alg *auth_base;
389 	int err;
390 
391 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD, &mask);
392 	if (err)
393 		return err;
394 
395 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
396 	if (!inst)
397 		return -ENOMEM;
398 	ctx = aead_instance_ctx(inst);
399 
400 	err = crypto_grab_ahash(&ctx->auth, aead_crypto_instance(inst),
401 				crypto_attr_alg_name(tb[1]), 0, mask);
402 	if (err)
403 		goto err_free_inst;
404 	auth = crypto_spawn_ahash_alg(&ctx->auth);
405 	auth_base = &auth->base;
406 
407 	err = crypto_grab_skcipher(&ctx->enc, aead_crypto_instance(inst),
408 				   crypto_attr_alg_name(tb[2]), 0, mask);
409 	if (err)
410 		goto err_free_inst;
411 	enc = crypto_spawn_skcipher_alg_common(&ctx->enc);
412 
413 	err = -ENAMETOOLONG;
414 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
415 		     "authencesn(%s,%s)", auth_base->cra_name,
416 		     enc->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
417 		goto err_free_inst;
418 
419 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
420 		     "authencesn(%s,%s)", auth_base->cra_driver_name,
421 		     enc->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
422 		goto err_free_inst;
423 
424 	inst->alg.base.cra_priority = enc->base.cra_priority * 10 +
425 				      auth_base->cra_priority;
426 	inst->alg.base.cra_blocksize = enc->base.cra_blocksize;
427 	inst->alg.base.cra_alignmask = enc->base.cra_alignmask;
428 	inst->alg.base.cra_ctxsize = sizeof(struct crypto_authenc_esn_ctx);
429 
430 	inst->alg.ivsize = enc->ivsize;
431 	inst->alg.chunksize = enc->chunksize;
432 	inst->alg.maxauthsize = auth->digestsize;
433 
434 	inst->alg.init = crypto_authenc_esn_init_tfm;
435 	inst->alg.exit = crypto_authenc_esn_exit_tfm;
436 
437 	inst->alg.setkey = crypto_authenc_esn_setkey;
438 	inst->alg.setauthsize = crypto_authenc_esn_setauthsize;
439 	inst->alg.encrypt = crypto_authenc_esn_encrypt;
440 	inst->alg.decrypt = crypto_authenc_esn_decrypt;
441 
442 	inst->free = crypto_authenc_esn_free;
443 
444 	err = aead_register_instance(tmpl, inst);
445 	if (err) {
446 err_free_inst:
447 		crypto_authenc_esn_free(inst);
448 	}
449 	return err;
450 }
451 
452 static struct crypto_template crypto_authenc_esn_tmpl = {
453 	.name = "authencesn",
454 	.create = crypto_authenc_esn_create,
455 	.module = THIS_MODULE,
456 };
457 
crypto_authenc_esn_module_init(void)458 static int __init crypto_authenc_esn_module_init(void)
459 {
460 	return crypto_register_template(&crypto_authenc_esn_tmpl);
461 }
462 
crypto_authenc_esn_module_exit(void)463 static void __exit crypto_authenc_esn_module_exit(void)
464 {
465 	crypto_unregister_template(&crypto_authenc_esn_tmpl);
466 }
467 
468 subsys_initcall(crypto_authenc_esn_module_init);
469 module_exit(crypto_authenc_esn_module_exit);
470 
471 MODULE_LICENSE("GPL");
472 MODULE_AUTHOR("Steffen Klassert <steffen.klassert@secunet.com>");
473 MODULE_DESCRIPTION("AEAD wrapper for IPsec with extended sequence numbers");
474 MODULE_ALIAS_CRYPTO("authencesn");
475