xref: /linux/crypto/essiv.c (revision bf80eef2212a1e8451df13b52533f4bc31bb4f8e)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * ESSIV skcipher and aead template for block encryption
4  *
5  * This template encapsulates the ESSIV IV generation algorithm used by
6  * dm-crypt and fscrypt, which converts the initial vector for the skcipher
7  * used for block encryption, by encrypting it using the hash of the
8  * skcipher key as encryption key. Usually, the input IV is a 64-bit sector
9  * number in LE representation zero-padded to the size of the IV, but this
10  * is not assumed by this driver.
11  *
12  * The typical use of this template is to instantiate the skcipher
13  * 'essiv(cbc(aes),sha256)', which is the only instantiation used by
14  * fscrypt, and the most relevant one for dm-crypt. However, dm-crypt
15  * also permits ESSIV to be used in combination with the authenc template,
16  * e.g., 'essiv(authenc(hmac(sha256),cbc(aes)),sha256)', in which case
17  * we need to instantiate an aead that accepts the same special key format
18  * as the authenc template, and deals with the way the encrypted IV is
19  * embedded into the AAD area of the aead request. This means the AEAD
20  * flavor produced by this template is tightly coupled to the way dm-crypt
21  * happens to use it.
22  *
23  * Copyright (c) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
24  *
25  * Heavily based on:
26  * adiantum length-preserving encryption mode
27  *
28  * Copyright 2018 Google LLC
29  */
30 
31 #include <crypto/authenc.h>
32 #include <crypto/internal/aead.h>
33 #include <crypto/internal/cipher.h>
34 #include <crypto/internal/hash.h>
35 #include <crypto/internal/skcipher.h>
36 #include <crypto/scatterwalk.h>
37 #include <linux/module.h>
38 
39 #include "internal.h"
40 
41 struct essiv_instance_ctx {
42 	union {
43 		struct crypto_skcipher_spawn	skcipher_spawn;
44 		struct crypto_aead_spawn	aead_spawn;
45 	} u;
46 	char	essiv_cipher_name[CRYPTO_MAX_ALG_NAME];
47 	char	shash_driver_name[CRYPTO_MAX_ALG_NAME];
48 };
49 
50 struct essiv_tfm_ctx {
51 	union {
52 		struct crypto_skcipher	*skcipher;
53 		struct crypto_aead	*aead;
54 	} u;
55 	struct crypto_cipher		*essiv_cipher;
56 	struct crypto_shash		*hash;
57 	int				ivoffset;
58 };
59 
60 struct essiv_aead_request_ctx {
61 	struct scatterlist		sg[4];
62 	u8				*assoc;
63 	struct aead_request		aead_req;
64 };
65 
66 static int essiv_skcipher_setkey(struct crypto_skcipher *tfm,
67 				 const u8 *key, unsigned int keylen)
68 {
69 	struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
70 	u8 salt[HASH_MAX_DIGESTSIZE];
71 	int err;
72 
73 	crypto_skcipher_clear_flags(tctx->u.skcipher, CRYPTO_TFM_REQ_MASK);
74 	crypto_skcipher_set_flags(tctx->u.skcipher,
75 				  crypto_skcipher_get_flags(tfm) &
76 				  CRYPTO_TFM_REQ_MASK);
77 	err = crypto_skcipher_setkey(tctx->u.skcipher, key, keylen);
78 	if (err)
79 		return err;
80 
81 	err = crypto_shash_tfm_digest(tctx->hash, key, keylen, salt);
82 	if (err)
83 		return err;
84 
85 	crypto_cipher_clear_flags(tctx->essiv_cipher, CRYPTO_TFM_REQ_MASK);
86 	crypto_cipher_set_flags(tctx->essiv_cipher,
87 				crypto_skcipher_get_flags(tfm) &
88 				CRYPTO_TFM_REQ_MASK);
89 	return crypto_cipher_setkey(tctx->essiv_cipher, salt,
90 				    crypto_shash_digestsize(tctx->hash));
91 }
92 
93 static int essiv_aead_setkey(struct crypto_aead *tfm, const u8 *key,
94 			     unsigned int keylen)
95 {
96 	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
97 	SHASH_DESC_ON_STACK(desc, tctx->hash);
98 	struct crypto_authenc_keys keys;
99 	u8 salt[HASH_MAX_DIGESTSIZE];
100 	int err;
101 
102 	crypto_aead_clear_flags(tctx->u.aead, CRYPTO_TFM_REQ_MASK);
103 	crypto_aead_set_flags(tctx->u.aead, crypto_aead_get_flags(tfm) &
104 					    CRYPTO_TFM_REQ_MASK);
105 	err = crypto_aead_setkey(tctx->u.aead, key, keylen);
106 	if (err)
107 		return err;
108 
109 	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
110 		return -EINVAL;
111 
112 	desc->tfm = tctx->hash;
113 	err = crypto_shash_init(desc) ?:
114 	      crypto_shash_update(desc, keys.enckey, keys.enckeylen) ?:
115 	      crypto_shash_finup(desc, keys.authkey, keys.authkeylen, salt);
116 	if (err)
117 		return err;
118 
119 	crypto_cipher_clear_flags(tctx->essiv_cipher, CRYPTO_TFM_REQ_MASK);
120 	crypto_cipher_set_flags(tctx->essiv_cipher, crypto_aead_get_flags(tfm) &
121 						    CRYPTO_TFM_REQ_MASK);
122 	return crypto_cipher_setkey(tctx->essiv_cipher, salt,
123 				    crypto_shash_digestsize(tctx->hash));
124 }
125 
126 static int essiv_aead_setauthsize(struct crypto_aead *tfm,
127 				  unsigned int authsize)
128 {
129 	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
130 
131 	return crypto_aead_setauthsize(tctx->u.aead, authsize);
132 }
133 
134 static void essiv_skcipher_done(struct crypto_async_request *areq, int err)
135 {
136 	struct skcipher_request *req = areq->data;
137 
138 	skcipher_request_complete(req, err);
139 }
140 
141 static int essiv_skcipher_crypt(struct skcipher_request *req, bool enc)
142 {
143 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
144 	const struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
145 	struct skcipher_request *subreq = skcipher_request_ctx(req);
146 
147 	crypto_cipher_encrypt_one(tctx->essiv_cipher, req->iv, req->iv);
148 
149 	skcipher_request_set_tfm(subreq, tctx->u.skcipher);
150 	skcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
151 				   req->iv);
152 	skcipher_request_set_callback(subreq, skcipher_request_flags(req),
153 				      essiv_skcipher_done, req);
154 
155 	return enc ? crypto_skcipher_encrypt(subreq) :
156 		     crypto_skcipher_decrypt(subreq);
157 }
158 
159 static int essiv_skcipher_encrypt(struct skcipher_request *req)
160 {
161 	return essiv_skcipher_crypt(req, true);
162 }
163 
164 static int essiv_skcipher_decrypt(struct skcipher_request *req)
165 {
166 	return essiv_skcipher_crypt(req, false);
167 }
168 
169 static void essiv_aead_done(struct crypto_async_request *areq, int err)
170 {
171 	struct aead_request *req = areq->data;
172 	struct essiv_aead_request_ctx *rctx = aead_request_ctx(req);
173 
174 	kfree(rctx->assoc);
175 	aead_request_complete(req, err);
176 }
177 
178 static int essiv_aead_crypt(struct aead_request *req, bool enc)
179 {
180 	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
181 	const struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
182 	struct essiv_aead_request_ctx *rctx = aead_request_ctx(req);
183 	struct aead_request *subreq = &rctx->aead_req;
184 	struct scatterlist *src = req->src;
185 	int err;
186 
187 	crypto_cipher_encrypt_one(tctx->essiv_cipher, req->iv, req->iv);
188 
189 	/*
190 	 * dm-crypt embeds the sector number and the IV in the AAD region, so
191 	 * we have to copy the converted IV into the right scatterlist before
192 	 * we pass it on.
193 	 */
194 	rctx->assoc = NULL;
195 	if (req->src == req->dst || !enc) {
196 		scatterwalk_map_and_copy(req->iv, req->dst,
197 					 req->assoclen - crypto_aead_ivsize(tfm),
198 					 crypto_aead_ivsize(tfm), 1);
199 	} else {
200 		u8 *iv = (u8 *)aead_request_ctx(req) + tctx->ivoffset;
201 		int ivsize = crypto_aead_ivsize(tfm);
202 		int ssize = req->assoclen - ivsize;
203 		struct scatterlist *sg;
204 		int nents;
205 
206 		if (ssize < 0)
207 			return -EINVAL;
208 
209 		nents = sg_nents_for_len(req->src, ssize);
210 		if (nents < 0)
211 			return -EINVAL;
212 
213 		memcpy(iv, req->iv, ivsize);
214 		sg_init_table(rctx->sg, 4);
215 
216 		if (unlikely(nents > 1)) {
217 			/*
218 			 * This is a case that rarely occurs in practice, but
219 			 * for correctness, we have to deal with it nonetheless.
220 			 */
221 			rctx->assoc = kmalloc(ssize, GFP_ATOMIC);
222 			if (!rctx->assoc)
223 				return -ENOMEM;
224 
225 			scatterwalk_map_and_copy(rctx->assoc, req->src, 0,
226 						 ssize, 0);
227 			sg_set_buf(rctx->sg, rctx->assoc, ssize);
228 		} else {
229 			sg_set_page(rctx->sg, sg_page(req->src), ssize,
230 				    req->src->offset);
231 		}
232 
233 		sg_set_buf(rctx->sg + 1, iv, ivsize);
234 		sg = scatterwalk_ffwd(rctx->sg + 2, req->src, req->assoclen);
235 		if (sg != rctx->sg + 2)
236 			sg_chain(rctx->sg, 3, sg);
237 
238 		src = rctx->sg;
239 	}
240 
241 	aead_request_set_tfm(subreq, tctx->u.aead);
242 	aead_request_set_ad(subreq, req->assoclen);
243 	aead_request_set_callback(subreq, aead_request_flags(req),
244 				  essiv_aead_done, req);
245 	aead_request_set_crypt(subreq, src, req->dst, req->cryptlen, req->iv);
246 
247 	err = enc ? crypto_aead_encrypt(subreq) :
248 		    crypto_aead_decrypt(subreq);
249 
250 	if (rctx->assoc && err != -EINPROGRESS)
251 		kfree(rctx->assoc);
252 	return err;
253 }
254 
255 static int essiv_aead_encrypt(struct aead_request *req)
256 {
257 	return essiv_aead_crypt(req, true);
258 }
259 
260 static int essiv_aead_decrypt(struct aead_request *req)
261 {
262 	return essiv_aead_crypt(req, false);
263 }
264 
265 static int essiv_init_tfm(struct essiv_instance_ctx *ictx,
266 			  struct essiv_tfm_ctx *tctx)
267 {
268 	struct crypto_cipher *essiv_cipher;
269 	struct crypto_shash *hash;
270 	int err;
271 
272 	essiv_cipher = crypto_alloc_cipher(ictx->essiv_cipher_name, 0, 0);
273 	if (IS_ERR(essiv_cipher))
274 		return PTR_ERR(essiv_cipher);
275 
276 	hash = crypto_alloc_shash(ictx->shash_driver_name, 0, 0);
277 	if (IS_ERR(hash)) {
278 		err = PTR_ERR(hash);
279 		goto err_free_essiv_cipher;
280 	}
281 
282 	tctx->essiv_cipher = essiv_cipher;
283 	tctx->hash = hash;
284 
285 	return 0;
286 
287 err_free_essiv_cipher:
288 	crypto_free_cipher(essiv_cipher);
289 	return err;
290 }
291 
292 static int essiv_skcipher_init_tfm(struct crypto_skcipher *tfm)
293 {
294 	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
295 	struct essiv_instance_ctx *ictx = skcipher_instance_ctx(inst);
296 	struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
297 	struct crypto_skcipher *skcipher;
298 	int err;
299 
300 	skcipher = crypto_spawn_skcipher(&ictx->u.skcipher_spawn);
301 	if (IS_ERR(skcipher))
302 		return PTR_ERR(skcipher);
303 
304 	crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
305 				         crypto_skcipher_reqsize(skcipher));
306 
307 	err = essiv_init_tfm(ictx, tctx);
308 	if (err) {
309 		crypto_free_skcipher(skcipher);
310 		return err;
311 	}
312 
313 	tctx->u.skcipher = skcipher;
314 	return 0;
315 }
316 
317 static int essiv_aead_init_tfm(struct crypto_aead *tfm)
318 {
319 	struct aead_instance *inst = aead_alg_instance(tfm);
320 	struct essiv_instance_ctx *ictx = aead_instance_ctx(inst);
321 	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
322 	struct crypto_aead *aead;
323 	unsigned int subreq_size;
324 	int err;
325 
326 	BUILD_BUG_ON(offsetofend(struct essiv_aead_request_ctx, aead_req) !=
327 		     sizeof(struct essiv_aead_request_ctx));
328 
329 	aead = crypto_spawn_aead(&ictx->u.aead_spawn);
330 	if (IS_ERR(aead))
331 		return PTR_ERR(aead);
332 
333 	subreq_size = sizeof_field(struct essiv_aead_request_ctx, aead_req) +
334 		      crypto_aead_reqsize(aead);
335 
336 	tctx->ivoffset = offsetof(struct essiv_aead_request_ctx, aead_req) +
337 			 subreq_size;
338 	crypto_aead_set_reqsize(tfm, tctx->ivoffset + crypto_aead_ivsize(aead));
339 
340 	err = essiv_init_tfm(ictx, tctx);
341 	if (err) {
342 		crypto_free_aead(aead);
343 		return err;
344 	}
345 
346 	tctx->u.aead = aead;
347 	return 0;
348 }
349 
350 static void essiv_skcipher_exit_tfm(struct crypto_skcipher *tfm)
351 {
352 	struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
353 
354 	crypto_free_skcipher(tctx->u.skcipher);
355 	crypto_free_cipher(tctx->essiv_cipher);
356 	crypto_free_shash(tctx->hash);
357 }
358 
359 static void essiv_aead_exit_tfm(struct crypto_aead *tfm)
360 {
361 	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
362 
363 	crypto_free_aead(tctx->u.aead);
364 	crypto_free_cipher(tctx->essiv_cipher);
365 	crypto_free_shash(tctx->hash);
366 }
367 
368 static void essiv_skcipher_free_instance(struct skcipher_instance *inst)
369 {
370 	struct essiv_instance_ctx *ictx = skcipher_instance_ctx(inst);
371 
372 	crypto_drop_skcipher(&ictx->u.skcipher_spawn);
373 	kfree(inst);
374 }
375 
376 static void essiv_aead_free_instance(struct aead_instance *inst)
377 {
378 	struct essiv_instance_ctx *ictx = aead_instance_ctx(inst);
379 
380 	crypto_drop_aead(&ictx->u.aead_spawn);
381 	kfree(inst);
382 }
383 
384 static bool parse_cipher_name(char *essiv_cipher_name, const char *cra_name)
385 {
386 	const char *p, *q;
387 	int len;
388 
389 	/* find the last opening parens */
390 	p = strrchr(cra_name, '(');
391 	if (!p++)
392 		return false;
393 
394 	/* find the first closing parens in the tail of the string */
395 	q = strchr(p, ')');
396 	if (!q)
397 		return false;
398 
399 	len = q - p;
400 	if (len >= CRYPTO_MAX_ALG_NAME)
401 		return false;
402 
403 	memcpy(essiv_cipher_name, p, len);
404 	essiv_cipher_name[len] = '\0';
405 	return true;
406 }
407 
408 static bool essiv_supported_algorithms(const char *essiv_cipher_name,
409 				       struct shash_alg *hash_alg,
410 				       int ivsize)
411 {
412 	struct crypto_alg *alg;
413 	bool ret = false;
414 
415 	alg = crypto_alg_mod_lookup(essiv_cipher_name,
416 				    CRYPTO_ALG_TYPE_CIPHER,
417 				    CRYPTO_ALG_TYPE_MASK);
418 	if (IS_ERR(alg))
419 		return false;
420 
421 	if (hash_alg->digestsize < alg->cra_cipher.cia_min_keysize ||
422 	    hash_alg->digestsize > alg->cra_cipher.cia_max_keysize)
423 		goto out;
424 
425 	if (ivsize != alg->cra_blocksize)
426 		goto out;
427 
428 	if (crypto_shash_alg_needs_key(hash_alg))
429 		goto out;
430 
431 	ret = true;
432 
433 out:
434 	crypto_mod_put(alg);
435 	return ret;
436 }
437 
438 static int essiv_create(struct crypto_template *tmpl, struct rtattr **tb)
439 {
440 	struct crypto_attr_type *algt;
441 	const char *inner_cipher_name;
442 	const char *shash_name;
443 	struct skcipher_instance *skcipher_inst = NULL;
444 	struct aead_instance *aead_inst = NULL;
445 	struct crypto_instance *inst;
446 	struct crypto_alg *base, *block_base;
447 	struct essiv_instance_ctx *ictx;
448 	struct skcipher_alg *skcipher_alg = NULL;
449 	struct aead_alg *aead_alg = NULL;
450 	struct crypto_alg *_hash_alg;
451 	struct shash_alg *hash_alg;
452 	int ivsize;
453 	u32 type;
454 	u32 mask;
455 	int err;
456 
457 	algt = crypto_get_attr_type(tb);
458 	if (IS_ERR(algt))
459 		return PTR_ERR(algt);
460 
461 	inner_cipher_name = crypto_attr_alg_name(tb[1]);
462 	if (IS_ERR(inner_cipher_name))
463 		return PTR_ERR(inner_cipher_name);
464 
465 	shash_name = crypto_attr_alg_name(tb[2]);
466 	if (IS_ERR(shash_name))
467 		return PTR_ERR(shash_name);
468 
469 	type = algt->type & algt->mask;
470 	mask = crypto_algt_inherited_mask(algt);
471 
472 	switch (type) {
473 	case CRYPTO_ALG_TYPE_SKCIPHER:
474 		skcipher_inst = kzalloc(sizeof(*skcipher_inst) +
475 					sizeof(*ictx), GFP_KERNEL);
476 		if (!skcipher_inst)
477 			return -ENOMEM;
478 		inst = skcipher_crypto_instance(skcipher_inst);
479 		base = &skcipher_inst->alg.base;
480 		ictx = crypto_instance_ctx(inst);
481 
482 		/* Symmetric cipher, e.g., "cbc(aes)" */
483 		err = crypto_grab_skcipher(&ictx->u.skcipher_spawn, inst,
484 					   inner_cipher_name, 0, mask);
485 		if (err)
486 			goto out_free_inst;
487 		skcipher_alg = crypto_spawn_skcipher_alg(&ictx->u.skcipher_spawn);
488 		block_base = &skcipher_alg->base;
489 		ivsize = crypto_skcipher_alg_ivsize(skcipher_alg);
490 		break;
491 
492 	case CRYPTO_ALG_TYPE_AEAD:
493 		aead_inst = kzalloc(sizeof(*aead_inst) +
494 				    sizeof(*ictx), GFP_KERNEL);
495 		if (!aead_inst)
496 			return -ENOMEM;
497 		inst = aead_crypto_instance(aead_inst);
498 		base = &aead_inst->alg.base;
499 		ictx = crypto_instance_ctx(inst);
500 
501 		/* AEAD cipher, e.g., "authenc(hmac(sha256),cbc(aes))" */
502 		err = crypto_grab_aead(&ictx->u.aead_spawn, inst,
503 				       inner_cipher_name, 0, mask);
504 		if (err)
505 			goto out_free_inst;
506 		aead_alg = crypto_spawn_aead_alg(&ictx->u.aead_spawn);
507 		block_base = &aead_alg->base;
508 		if (!strstarts(block_base->cra_name, "authenc(")) {
509 			pr_warn("Only authenc() type AEADs are supported by ESSIV\n");
510 			err = -EINVAL;
511 			goto out_drop_skcipher;
512 		}
513 		ivsize = aead_alg->ivsize;
514 		break;
515 
516 	default:
517 		return -EINVAL;
518 	}
519 
520 	if (!parse_cipher_name(ictx->essiv_cipher_name, block_base->cra_name)) {
521 		pr_warn("Failed to parse ESSIV cipher name from skcipher cra_name\n");
522 		err = -EINVAL;
523 		goto out_drop_skcipher;
524 	}
525 
526 	/* Synchronous hash, e.g., "sha256" */
527 	_hash_alg = crypto_alg_mod_lookup(shash_name,
528 					  CRYPTO_ALG_TYPE_SHASH,
529 					  CRYPTO_ALG_TYPE_MASK | mask);
530 	if (IS_ERR(_hash_alg)) {
531 		err = PTR_ERR(_hash_alg);
532 		goto out_drop_skcipher;
533 	}
534 	hash_alg = __crypto_shash_alg(_hash_alg);
535 
536 	/* Check the set of algorithms */
537 	if (!essiv_supported_algorithms(ictx->essiv_cipher_name, hash_alg,
538 					ivsize)) {
539 		pr_warn("Unsupported essiv instantiation: essiv(%s,%s)\n",
540 			block_base->cra_name, hash_alg->base.cra_name);
541 		err = -EINVAL;
542 		goto out_free_hash;
543 	}
544 
545 	/* record the driver name so we can instantiate this exact algo later */
546 	strscpy(ictx->shash_driver_name, hash_alg->base.cra_driver_name,
547 		CRYPTO_MAX_ALG_NAME);
548 
549 	/* Instance fields */
550 
551 	err = -ENAMETOOLONG;
552 	if (snprintf(base->cra_name, CRYPTO_MAX_ALG_NAME,
553 		     "essiv(%s,%s)", block_base->cra_name,
554 		     hash_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
555 		goto out_free_hash;
556 	if (snprintf(base->cra_driver_name, CRYPTO_MAX_ALG_NAME,
557 		     "essiv(%s,%s)", block_base->cra_driver_name,
558 		     hash_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
559 		goto out_free_hash;
560 
561 	/*
562 	 * hash_alg wasn't gotten via crypto_grab*(), so we need to inherit its
563 	 * flags manually.
564 	 */
565 	base->cra_flags        |= (hash_alg->base.cra_flags &
566 				   CRYPTO_ALG_INHERITED_FLAGS);
567 	base->cra_blocksize	= block_base->cra_blocksize;
568 	base->cra_ctxsize	= sizeof(struct essiv_tfm_ctx);
569 	base->cra_alignmask	= block_base->cra_alignmask;
570 	base->cra_priority	= block_base->cra_priority;
571 
572 	if (type == CRYPTO_ALG_TYPE_SKCIPHER) {
573 		skcipher_inst->alg.setkey	= essiv_skcipher_setkey;
574 		skcipher_inst->alg.encrypt	= essiv_skcipher_encrypt;
575 		skcipher_inst->alg.decrypt	= essiv_skcipher_decrypt;
576 		skcipher_inst->alg.init		= essiv_skcipher_init_tfm;
577 		skcipher_inst->alg.exit		= essiv_skcipher_exit_tfm;
578 
579 		skcipher_inst->alg.min_keysize	= crypto_skcipher_alg_min_keysize(skcipher_alg);
580 		skcipher_inst->alg.max_keysize	= crypto_skcipher_alg_max_keysize(skcipher_alg);
581 		skcipher_inst->alg.ivsize	= ivsize;
582 		skcipher_inst->alg.chunksize	= crypto_skcipher_alg_chunksize(skcipher_alg);
583 		skcipher_inst->alg.walksize	= crypto_skcipher_alg_walksize(skcipher_alg);
584 
585 		skcipher_inst->free		= essiv_skcipher_free_instance;
586 
587 		err = skcipher_register_instance(tmpl, skcipher_inst);
588 	} else {
589 		aead_inst->alg.setkey		= essiv_aead_setkey;
590 		aead_inst->alg.setauthsize	= essiv_aead_setauthsize;
591 		aead_inst->alg.encrypt		= essiv_aead_encrypt;
592 		aead_inst->alg.decrypt		= essiv_aead_decrypt;
593 		aead_inst->alg.init		= essiv_aead_init_tfm;
594 		aead_inst->alg.exit		= essiv_aead_exit_tfm;
595 
596 		aead_inst->alg.ivsize		= ivsize;
597 		aead_inst->alg.maxauthsize	= crypto_aead_alg_maxauthsize(aead_alg);
598 		aead_inst->alg.chunksize	= crypto_aead_alg_chunksize(aead_alg);
599 
600 		aead_inst->free			= essiv_aead_free_instance;
601 
602 		err = aead_register_instance(tmpl, aead_inst);
603 	}
604 
605 	if (err)
606 		goto out_free_hash;
607 
608 	crypto_mod_put(_hash_alg);
609 	return 0;
610 
611 out_free_hash:
612 	crypto_mod_put(_hash_alg);
613 out_drop_skcipher:
614 	if (type == CRYPTO_ALG_TYPE_SKCIPHER)
615 		crypto_drop_skcipher(&ictx->u.skcipher_spawn);
616 	else
617 		crypto_drop_aead(&ictx->u.aead_spawn);
618 out_free_inst:
619 	kfree(skcipher_inst);
620 	kfree(aead_inst);
621 	return err;
622 }
623 
624 /* essiv(cipher_name, shash_name) */
625 static struct crypto_template essiv_tmpl = {
626 	.name	= "essiv",
627 	.create	= essiv_create,
628 	.module	= THIS_MODULE,
629 };
630 
631 static int __init essiv_module_init(void)
632 {
633 	return crypto_register_template(&essiv_tmpl);
634 }
635 
636 static void __exit essiv_module_exit(void)
637 {
638 	crypto_unregister_template(&essiv_tmpl);
639 }
640 
641 subsys_initcall(essiv_module_init);
642 module_exit(essiv_module_exit);
643 
644 MODULE_DESCRIPTION("ESSIV skcipher/aead wrapper for block encryption");
645 MODULE_LICENSE("GPL v2");
646 MODULE_ALIAS_CRYPTO("essiv");
647 MODULE_IMPORT_NS(CRYPTO_INTERNAL);
648