summaryrefslogtreecommitdiffstats
path: root/crypto/essiv.c
blob: 0e45f5b4f67f54689dfc02c73bbc688ea4135a92 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
// SPDX-License-Identifier: GPL-2.0
/*
 * ESSIV skcipher and aead template for block encryption
 *
 * This template encapsulates the ESSIV IV generation algorithm used by
 * dm-crypt and fscrypt, which converts the initial vector for the skcipher
 * used for block encryption, by encrypting it using the hash of the
 * skcipher key as encryption key. Usually, the input IV is a 64-bit sector
 * number in LE representation zero-padded to the size of the IV, but this
 * is not assumed by this driver.
 *
 * The typical use of this template is to instantiate the skcipher
 * 'essiv(cbc(aes),sha256)', which is the only instantiation used by
 * fscrypt, and the most relevant one for dm-crypt. However, dm-crypt
 * also permits ESSIV to be used in combination with the authenc template,
 * e.g., 'essiv(authenc(hmac(sha256),cbc(aes)),sha256)', in which case
 * we need to instantiate an aead that accepts the same special key format
 * as the authenc template, and deals with the way the encrypted IV is
 * embedded into the AAD area of the aead request. This means the AEAD
 * flavor produced by this template is tightly coupled to the way dm-crypt
 * happens to use it.
 *
 * Copyright (c) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
 *
 * Heavily based on:
 * adiantum length-preserving encryption mode
 *
 * Copyright 2018 Google LLC
 */

#include <crypto/authenc.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/module.h>

#include "internal.h"

struct essiv_instance_ctx {
	union {
		struct crypto_skcipher_spawn	skcipher_spawn;
		struct crypto_aead_spawn	aead_spawn;
	} u;
	char	essiv_cipher_name[CRYPTO_MAX_ALG_NAME];
	char	shash_driver_name[CRYPTO_MAX_ALG_NAME];
};

struct essiv_tfm_ctx {
	union {
		struct crypto_skcipher	*skcipher;
		struct crypto_aead	*aead;
	} u;
	struct crypto_cipher		*essiv_cipher;
	struct crypto_shash		*hash;
	int				ivoffset;
};

struct essiv_aead_request_ctx {
	struct scatterlist		sg[4];
	u8				*assoc;
	struct aead_request		aead_req;
};

static int essiv_skcipher_setkey(struct crypto_skcipher *tfm,
				 const u8 *key, unsigned int keylen)
{
	struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
	SHASH_DESC_ON_STACK(desc, tctx->hash);
	u8 salt[HASH_MAX_DIGESTSIZE];
	int err;

	crypto_skcipher_clear_flags(tctx->u.skcipher, CRYPTO_TFM_REQ_MASK);
	crypto_skcipher_set_flags(tctx->u.skcipher,
				  crypto_skcipher_get_flags(tfm) &
				  CRYPTO_TFM_REQ_MASK);
	err = crypto_skcipher_setkey(tctx->u.skcipher, key, keylen);
	if (err)
		return err;

	desc->tfm = tctx->hash;
	err = crypto_shash_digest(desc, key, keylen, salt);
	if (err)
		return err;

	crypto_cipher_clear_flags(tctx->essiv_cipher, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(tctx->essiv_cipher,
				crypto_skcipher_get_flags(tfm) &
				CRYPTO_TFM_REQ_MASK);
	return crypto_cipher_setkey(tctx->essiv_cipher, salt,
				    crypto_shash_digestsize(tctx->hash));
}

static int essiv_aead_setkey(struct crypto_aead *tfm, const u8 *key,
			     unsigned int keylen)
{
	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
	SHASH_DESC_ON_STACK(desc, tctx->hash);
	struct crypto_authenc_keys keys;
	u8 salt[HASH_MAX_DIGESTSIZE];
	int err;

	crypto_aead_clear_flags(tctx->u.aead, CRYPTO_TFM_REQ_MASK);
	crypto_aead_set_flags(tctx->u.aead, crypto_aead_get_flags(tfm) &
					    CRYPTO_TFM_REQ_MASK);
	err = crypto_aead_setkey(tctx->u.aead, key, keylen);
	if (err)
		return err;

	if (crypto_authenc_extractkeys(&keys, key, keylen) != 0)
		return -EINVAL;

	desc->tfm = tctx->hash;
	err = crypto_shash_init(desc) ?:
	      crypto_shash_update(desc, keys.enckey, keys.enckeylen) ?:
	      crypto_shash_finup(desc, keys.authkey, keys.authkeylen, salt);
	if (err)
		return err;

	crypto_cipher_clear_flags(tctx->essiv_cipher, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(tctx->essiv_cipher, crypto_aead_get_flags(tfm) &
						    CRYPTO_TFM_REQ_MASK);
	return crypto_cipher_setkey(tctx->essiv_cipher, salt,
				    crypto_shash_digestsize(tctx->hash));
}

static int essiv_aead_setauthsize(struct crypto_aead *tfm,
				  unsigned int authsize)
{
	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);

	return crypto_aead_setauthsize(tctx->u.aead, authsize);
}

static void essiv_skcipher_done(struct crypto_async_request *areq, int err)
{
	struct skcipher_request *req = areq->data;

	skcipher_request_complete(req, err);
}

static int essiv_skcipher_crypt(struct skcipher_request *req, bool enc)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	const struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
	struct skcipher_request *subreq = skcipher_request_ctx(req);

	crypto_cipher_encrypt_one(tctx->essiv_cipher, req->iv, req->iv);

	skcipher_request_set_tfm(subreq, tctx->u.skcipher);
	skcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
				   req->iv);
	skcipher_request_set_callback(subreq, skcipher_request_flags(req),
				      essiv_skcipher_done, req);

	return enc ? crypto_skcipher_encrypt(subreq) :
		     crypto_skcipher_decrypt(subreq);
}

static int essiv_skcipher_encrypt(struct skcipher_request *req)
{
	return essiv_skcipher_crypt(req, true);
}

static int essiv_skcipher_decrypt(struct skcipher_request *req)
{
	return essiv_skcipher_crypt(req, false);
}

static void essiv_aead_done(struct crypto_async_request *areq, int err)
{
	struct aead_request *req = areq->data;
	struct essiv_aead_request_ctx *rctx = aead_request_ctx(req);

	kfree(rctx->assoc);
	aead_request_complete(req, err);
}

static int essiv_aead_crypt(struct aead_request *req, bool enc)
{
	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
	const struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
	struct essiv_aead_request_ctx *rctx = aead_request_ctx(req);
	struct aead_request *subreq = &rctx->aead_req;
	struct scatterlist *src = req->src;
	int err;

	crypto_cipher_encrypt_one(tctx->essiv_cipher, req->iv, req->iv);

	/*
	 * dm-crypt embeds the sector number and the IV in the AAD region, so
	 * we have to copy the converted IV into the right scatterlist before
	 * we pass it on.
	 */
	rctx->assoc = NULL;
	if (req->src == req->dst || !enc) {
		scatterwalk_map_and_copy(req->iv, req->dst,
					 req->assoclen - crypto_aead_ivsize(tfm),
					 crypto_aead_ivsize(tfm), 1);
	} else {
		u8 *iv = (u8 *)aead_request_ctx(req) + tctx->ivoffset;
		int ivsize = crypto_aead_ivsize(tfm);
		int ssize = req->assoclen - ivsize;
		struct scatterlist *sg;
		int nents;

		if (ssize < 0)
			return -EINVAL;

		nents = sg_nents_for_len(req->src, ssize);
		if (nents < 0)
			return -EINVAL;

		memcpy(iv, req->iv, ivsize);
		sg_init_table(rctx->sg, 4);

		if (unlikely(nents > 1)) {
			/*
			 * This is a case that rarely occurs in practice, but
			 * for correctness, we have to deal with it nonetheless.
			 */
			rctx->assoc = kmalloc(ssize, GFP_ATOMIC);
			if (!rctx->assoc)
				return -ENOMEM;

			scatterwalk_map_and_copy(rctx->assoc, req->src, 0,
						 ssize, 0);
			sg_set_buf(rctx->sg, rctx->assoc, ssize);
		} else {
			sg_set_page(rctx->sg, sg_page(req->src), ssize,
				    req->src->offset);
		}

		sg_set_buf(rctx->sg + 1, iv, ivsize);
		sg = scatterwalk_ffwd(rctx->sg + 2, req->src, req->assoclen);
		if (sg != rctx->sg + 2)
			sg_chain(rctx->sg, 3, sg);

		src = rctx->sg;
	}

	aead_request_set_tfm(subreq, tctx->u.aead);
	aead_request_set_ad(subreq, req->assoclen);
	aead_request_set_callback(subreq, aead_request_flags(req),
				  essiv_aead_done, req);
	aead_request_set_crypt(subreq, src, req->dst, req->cryptlen, req->iv);

	err = enc ? crypto_aead_encrypt(subreq) :
		    crypto_aead_decrypt(subreq);

	if (rctx->assoc && err != -EINPROGRESS)
		kfree(rctx->assoc);
	return err;
}

static int essiv_aead_encrypt(struct aead_request *req)
{
	return essiv_aead_crypt(req, true);
}

static int essiv_aead_decrypt(struct aead_request *req)
{
	return essiv_aead_crypt(req, false);
}

static int essiv_init_tfm(struct essiv_instance_ctx *ictx,
			  struct essiv_tfm_ctx *tctx)
{
	struct crypto_cipher *essiv_cipher;
	struct crypto_shash *hash;
	int err;

	essiv_cipher = crypto_alloc_cipher(ictx->essiv_cipher_name, 0, 0);
	if (IS_ERR(essiv_cipher))
		return PTR_ERR(essiv_cipher);

	hash = crypto_alloc_shash(ictx->shash_driver_name, 0, 0);
	if (IS_ERR(hash)) {
		err = PTR_ERR(hash);
		goto err_free_essiv_cipher;
	}

	tctx->essiv_cipher = essiv_cipher;
	tctx->hash = hash;

	return 0;

err_free_essiv_cipher:
	crypto_free_cipher(essiv_cipher);
	return err;
}

static int essiv_skcipher_init_tfm(struct crypto_skcipher *tfm)
{
	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
	struct essiv_instance_ctx *ictx = skcipher_instance_ctx(inst);
	struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
	struct crypto_skcipher *skcipher;
	int err;

	skcipher = crypto_spawn_skcipher(&ictx->u.skcipher_spawn);
	if (IS_ERR(skcipher))
		return PTR_ERR(skcipher);

	crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
				         crypto_skcipher_reqsize(skcipher));

	err = essiv_init_tfm(ictx, tctx);
	if (err) {
		crypto_free_skcipher(skcipher);
		return err;
	}

	tctx->u.skcipher = skcipher;
	return 0;
}

static int essiv_aead_init_tfm(struct crypto_aead *tfm)
{
	struct aead_instance *inst = aead_alg_instance(tfm);
	struct essiv_instance_ctx *ictx = aead_instance_ctx(inst);
	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);
	struct crypto_aead *aead;
	unsigned int subreq_size;
	int err;

	BUILD_BUG_ON(offsetofend(struct essiv_aead_request_ctx, aead_req) !=
		     sizeof(struct essiv_aead_request_ctx));

	aead = crypto_spawn_aead(&ictx->u.aead_spawn);
	if (IS_ERR(aead))
		return PTR_ERR(aead);

	subreq_size = FIELD_SIZEOF(struct essiv_aead_request_ctx, aead_req) +
		      crypto_aead_reqsize(aead);

	tctx->ivoffset = offsetof(struct essiv_aead_request_ctx, aead_req) +
			 subreq_size;
	crypto_aead_set_reqsize(tfm, tctx->ivoffset + crypto_aead_ivsize(aead));

	err = essiv_init_tfm(ictx, tctx);
	if (err) {
		crypto_free_aead(aead);
		return err;
	}

	tctx->u.aead = aead;
	return 0;
}

static void essiv_skcipher_exit_tfm(struct crypto_skcipher *tfm)
{
	struct essiv_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);

	crypto_free_skcipher(tctx->u.skcipher);
	crypto_free_cipher(tctx->essiv_cipher);
	crypto_free_shash(tctx->hash);
}

static void essiv_aead_exit_tfm(struct crypto_aead *tfm)
{
	struct essiv_tfm_ctx *tctx = crypto_aead_ctx(tfm);

	crypto_free_aead(tctx->u.aead);
	crypto_free_cipher(tctx->essiv_cipher);
	crypto_free_shash(tctx->hash);
}

static void essiv_skcipher_free_instance(struct skcipher_instance *inst)
{
	struct essiv_instance_ctx *ictx = skcipher_instance_ctx(inst);

	crypto_drop_skcipher(&ictx->u.skcipher_spawn);
	kfree(inst);
}

static void essiv_aead_free_instance(struct aead_instance *inst)
{
	struct essiv_instance_ctx *ictx = aead_instance_ctx(inst);

	crypto_drop_aead(&ictx->u.aead_spawn);
	kfree(inst);
}

static bool parse_cipher_name(char *essiv_cipher_name, const char *cra_name)
{
	const char *p, *q;
	int len;

	/* find the last opening parens */
	p = strrchr(cra_name, '(');
	if (!p++)
		return false;

	/* find the first closing parens in the tail of the string */
	q = strchr(p, ')');
	if (!q)
		return false;

	len = q - p;
	if (len >= CRYPTO_MAX_ALG_NAME)
		return false;

	memcpy(essiv_cipher_name, p, len);
	essiv_cipher_name[len] = '\0';
	return true;
}

static bool essiv_supported_algorithms(const char *essiv_cipher_name,
				       struct shash_alg *hash_alg,
				       int ivsize)
{
	struct crypto_alg *alg;
	bool ret = false;

	alg = crypto_alg_mod_lookup(essiv_cipher_name,
				    CRYPTO_ALG_TYPE_CIPHER,
				    CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
		return false;

	if (hash_alg->digestsize < alg->cra_cipher.cia_min_keysize ||
	    hash_alg->digestsize > alg->cra_cipher.cia_max_keysize)
		goto out;

	if (ivsize != alg->cra_blocksize)
		goto out;

	if (crypto_shash_alg_needs_key(hash_alg))
		goto out;

	ret = true;

out:
	crypto_mod_put(alg);
	return ret;
}

static int essiv_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct crypto_attr_type *algt;
	const char *inner_cipher_name;
	const char *shash_name;
	struct skcipher_instance *skcipher_inst = NULL;
	struct aead_instance *aead_inst = NULL;
	struct crypto_instance *inst;
	struct crypto_alg *base, *block_base;
	struct essiv_instance_ctx *ictx;
	struct skcipher_alg *skcipher_alg = NULL;
	struct aead_alg *aead_alg = NULL;
	struct crypto_alg *_hash_alg;
	struct shash_alg *hash_alg;
	int ivsize;
	u32 type;
	u32 mask;
	int err;

	algt = crypto_get_attr_type(tb);
	if (IS_ERR(algt))
		return PTR_ERR(algt);

	inner_cipher_name = crypto_attr_alg_name(tb[1]);
	if (IS_ERR(inner_cipher_name))
		return PTR_ERR(inner_cipher_name);

	shash_name = crypto_attr_alg_name(tb[2]);
	if (IS_ERR(shash_name))
		return PTR_ERR(shash_name);

	type = algt->type & algt->mask;
	mask = crypto_requires_sync(algt->type, algt->mask);

	switch (type) {
	case CRYPTO_ALG_TYPE_SKCIPHER:
		skcipher_inst = kzalloc(sizeof(*skcipher_inst) +
					sizeof(*ictx), GFP_KERNEL);
		if (!skcipher_inst)
			return -ENOMEM;
		inst = skcipher_crypto_instance(skcipher_inst);
		base = &skcipher_inst->alg.base;
		ictx = crypto_instance_ctx(inst);

		/* Symmetric cipher, e.g., "cbc(aes)" */
		err = crypto_grab_skcipher(&ictx->u.skcipher_spawn, inst,
					   inner_cipher_name, 0, mask);
		if (err)
			goto out_free_inst;
		skcipher_alg = crypto_spawn_skcipher_alg(&ictx->u.skcipher_spawn);
		block_base = &skcipher_alg->base;
		ivsize = crypto_skcipher_alg_ivsize(skcipher_alg);
		break;

	case CRYPTO_ALG_TYPE_AEAD:
		aead_inst = kzalloc(sizeof(*aead_inst) +
				    sizeof(*ictx), GFP_KERNEL);
		if (!aead_inst)
			return -ENOMEM;
		inst = aead_crypto_instance(aead_inst);
		base = &aead_inst->alg.base;
		ictx = crypto_instance_ctx(inst);

		/* AEAD cipher, e.g., "authenc(hmac(sha256),cbc(aes))" */
		crypto_set_aead_spawn(&ictx->u.aead_spawn, inst);
		err = crypto_grab_aead(&ictx->u.aead_spawn,
				       inner_cipher_name, 0, mask);
		if (err)
			goto out_free_inst;
		aead_alg = crypto_spawn_aead_alg(&ictx->u.aead_spawn);
		block_base = &aead_alg->base;
		if (!strstarts(block_base->cra_name, "authenc(")) {
			pr_warn("Only authenc() type AEADs are supported by ESSIV\n");
			err = -EINVAL;
			goto out_drop_skcipher;
		}
		ivsize = aead_alg->ivsize;
		break;

	default:
		return -EINVAL;
	}

	if (!parse_cipher_name(ictx->essiv_cipher_name, block_base->cra_name)) {
		pr_warn("Failed to parse ESSIV cipher name from skcipher cra_name\n");
		err = -EINVAL;
		goto out_drop_skcipher;
	}

	/* Synchronous hash, e.g., "sha256" */
	_hash_alg = crypto_alg_mod_lookup(shash_name,
					  CRYPTO_ALG_TYPE_SHASH,
					  CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(_hash_alg)) {
		err = PTR_ERR(_hash_alg);
		goto out_drop_skcipher;
	}
	hash_alg = __crypto_shash_alg(_hash_alg);

	/* Check the set of algorithms */
	if (!essiv_supported_algorithms(ictx->essiv_cipher_name, hash_alg,
					ivsize)) {
		pr_warn("Unsupported essiv instantiation: essiv(%s,%s)\n",
			block_base->cra_name, hash_alg->base.cra_name);
		err = -EINVAL;
		goto out_free_hash;
	}

	/* record the driver name so we can instantiate this exact algo later */
	strlcpy(ictx->shash_driver_name, hash_alg->base.cra_driver_name,
		CRYPTO_MAX_ALG_NAME);

	/* Instance fields */

	err = -ENAMETOOLONG;
	if (snprintf(base->cra_name, CRYPTO_MAX_ALG_NAME,
		     "essiv(%s,%s)", block_base->cra_name,
		     hash_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
		goto out_free_hash;
	if (snprintf(base->cra_driver_name, CRYPTO_MAX_ALG_NAME,
		     "essiv(%s,%s)", block_base->cra_driver_name,
		     hash_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
		goto out_free_hash;

	base->cra_flags		= block_base->cra_flags & CRYPTO_ALG_ASYNC;
	base->cra_blocksize	= block_base->cra_blocksize;
	base->cra_ctxsize	= sizeof(struct essiv_tfm_ctx);
	base->cra_alignmask	= block_base->cra_alignmask;
	base->cra_priority	= block_base->cra_priority;

	if (type == CRYPTO_ALG_TYPE_SKCIPHER) {
		skcipher_inst->alg.setkey	= essiv_skcipher_setkey;
		skcipher_inst->alg.encrypt	= essiv_skcipher_encrypt;
		skcipher_inst->alg.decrypt	= essiv_skcipher_decrypt;
		skcipher_inst->alg.init		= essiv_skcipher_init_tfm;
		skcipher_inst->alg.exit		= essiv_skcipher_exit_tfm;

		skcipher_inst->alg.min_keysize	= crypto_skcipher_alg_min_keysize(skcipher_alg);
		skcipher_inst->alg.max_keysize	= crypto_skcipher_alg_max_keysize(skcipher_alg);
		skcipher_inst->alg.ivsize	= ivsize;
		skcipher_inst->alg.chunksize	= crypto_skcipher_alg_chunksize(skcipher_alg);
		skcipher_inst->alg.walksize	= crypto_skcipher_alg_walksize(skcipher_alg);

		skcipher_inst->free		= essiv_skcipher_free_instance;

		err = skcipher_register_instance(tmpl, skcipher_inst);
	} else {
		aead_inst->alg.setkey		= essiv_aead_setkey;
		aead_inst->alg.setauthsize	= essiv_aead_setauthsize;
		aead_inst->alg.encrypt		= essiv_aead_encrypt;
		aead_inst->alg.decrypt		= essiv_aead_decrypt;
		aead_inst->alg.init		= essiv_aead_init_tfm;
		aead_inst->alg.exit		= essiv_aead_exit_tfm;

		aead_inst->alg.ivsize		= ivsize;
		aead_inst->alg.maxauthsize	= crypto_aead_alg_maxauthsize(aead_alg);
		aead_inst->alg.chunksize	= crypto_aead_alg_chunksize(aead_alg);

		aead_inst->free			= essiv_aead_free_instance;

		err = aead_register_instance(tmpl, aead_inst);
	}

	if (err)
		goto out_free_hash;

	crypto_mod_put(_hash_alg);
	return 0;

out_free_hash:
	crypto_mod_put(_hash_alg);
out_drop_skcipher:
	if (type == CRYPTO_ALG_TYPE_SKCIPHER)
		crypto_drop_skcipher(&ictx->u.skcipher_spawn);
	else
		crypto_drop_aead(&ictx->u.aead_spawn);
out_free_inst:
	kfree(skcipher_inst);
	kfree(aead_inst);
	return err;
}

/* essiv(cipher_name, shash_name) */
static struct crypto_template essiv_tmpl = {
	.name	= "essiv",
	.create	= essiv_create,
	.module	= THIS_MODULE,
};

static int __init essiv_module_init(void)
{
	return crypto_register_template(&essiv_tmpl);
}

static void __exit essiv_module_exit(void)
{
	crypto_unregister_template(&essiv_tmpl);
}

subsys_initcall(essiv_module_init);
module_exit(essiv_module_exit);

MODULE_DESCRIPTION("ESSIV skcipher/aead wrapper for block encryption");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("essiv");