// 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);

  	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;

  	err = crypto_shash_tfm_digest(tctx->hash, 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 = sizeof_field(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_algt_inherited_mask(algt);

  
  	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))" */

  		err = crypto_grab_aead(&ictx->u.aead_spawn, inst,

  				       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
  ");
  			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
  ");
  		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 | 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)
  ",
  			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;

  	/*
  	 * hash_alg wasn't gotten via crypto_grab*(), so we need to inherit its
  	 * flags manually.
  	 */
  	base->cra_flags        |= (hash_alg->base.cra_flags &
  				   CRYPTO_ALG_INHERITED_FLAGS);

  	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");