crypto/skcipher.c - pub/scm/linux/kernel/git/jhogan/linux - Git at Google

 /*
  * Symmetric key cipher operations.
  *
  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
  * multiple page boundaries by using temporary blocks.  In user context,
  * the kernel is given a chance to schedule us once per page.
  *
  * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the Free
  * Software Foundation; either version 2 of the License, or (at your option)
  * any later version.
  *
  */

 #include <crypto/internal/skcipher.h>
 #include <linux/bug.h>
 #include <linux/cryptouser.h>
 #include <linux/module.h>
 #include <linux/rtnetlink.h>
 #include <linux/seq_file.h>
 #include <net/netlink.h>

 #include "internal.h"

 static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
 {
 	if (alg->cra_type == &crypto_blkcipher_type)
 		return sizeof(struct crypto_blkcipher *);

 	if (alg->cra_type == &crypto_ablkcipher_type ||
 	    alg->cra_type == &crypto_givcipher_type)
 		return sizeof(struct crypto_ablkcipher *);

 	return crypto_alg_extsize(alg);
 }

 static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
 				     const u8 *key, unsigned int keylen)
 {
 	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
 	struct crypto_blkcipher *blkcipher = *ctx;
 	int err;

 	crypto_blkcipher_clear_flags(blkcipher, ~0);
 	crypto_blkcipher_set_flags(blkcipher, crypto_skcipher_get_flags(tfm) &
 					      CRYPTO_TFM_REQ_MASK);
 	err = crypto_blkcipher_setkey(blkcipher, key, keylen);
 	crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
 				       CRYPTO_TFM_RES_MASK);

 	return err;
 }

 static int skcipher_crypt_blkcipher(struct skcipher_request *req,
 				    int (*crypt)(struct blkcipher_desc *,
 						 struct scatterlist *,
 						 struct scatterlist *,
 						 unsigned int))
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
 	struct blkcipher_desc desc = {
 		.tfm = *ctx,
 		.info = req->iv,
 		.flags = req->base.flags,
 	};


 	return crypt(&desc, req->dst, req->src, req->cryptlen);
 }

 static int skcipher_encrypt_blkcipher(struct skcipher_request *req)
 {
 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
 	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

 	return skcipher_crypt_blkcipher(req, alg->encrypt);
 }

 static int skcipher_decrypt_blkcipher(struct skcipher_request *req)
 {
 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
 	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

 	return skcipher_crypt_blkcipher(req, alg->decrypt);
 }

 static void crypto_exit_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
 {
 	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);

 	crypto_free_blkcipher(*ctx);
 }

 static int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
 {
 	struct crypto_alg *calg = tfm->__crt_alg;
 	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
 	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
 	struct crypto_blkcipher *blkcipher;
 	struct crypto_tfm *btfm;

 	if (!crypto_mod_get(calg))
 		return -EAGAIN;

 	btfm = __crypto_alloc_tfm(calg, CRYPTO_ALG_TYPE_BLKCIPHER,
 					CRYPTO_ALG_TYPE_MASK);
 	if (IS_ERR(btfm)) {
 		crypto_mod_put(calg);
 		return PTR_ERR(btfm);
 	}

 	blkcipher = __crypto_blkcipher_cast(btfm);
 	*ctx = blkcipher;
 	tfm->exit = crypto_exit_skcipher_ops_blkcipher;

 	skcipher->setkey = skcipher_setkey_blkcipher;
 	skcipher->encrypt = skcipher_encrypt_blkcipher;
 	skcipher->decrypt = skcipher_decrypt_blkcipher;

 	skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
 	skcipher->keysize = calg->cra_blkcipher.max_keysize;

 	return 0;
 }

 static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
 				      const u8 *key, unsigned int keylen)
 {
 	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
 	struct crypto_ablkcipher *ablkcipher = *ctx;
 	int err;

 	crypto_ablkcipher_clear_flags(ablkcipher, ~0);
 	crypto_ablkcipher_set_flags(ablkcipher,
 				    crypto_skcipher_get_flags(tfm) &
 				    CRYPTO_TFM_REQ_MASK);
 	err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
 	crypto_skcipher_set_flags(tfm,
 				  crypto_ablkcipher_get_flags(ablkcipher) &
 				  CRYPTO_TFM_RES_MASK);

 	return err;
 }

 static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
 				     int (*crypt)(struct ablkcipher_request *))
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
 	struct ablkcipher_request *subreq = skcipher_request_ctx(req);

 	ablkcipher_request_set_tfm(subreq, *ctx);
 	ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
 					req->base.complete, req->base.data);
 	ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
 				     req->iv);

 	return crypt(subreq);
 }

 static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
 {
 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
 	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;

 	return skcipher_crypt_ablkcipher(req, alg->encrypt);
 }

 static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
 {
 	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
 	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
 	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;

 	return skcipher_crypt_ablkcipher(req, alg->decrypt);
 }

 static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
 {
 	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);

 	crypto_free_ablkcipher(*ctx);
 }

 static int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
 {
 	struct crypto_alg *calg = tfm->__crt_alg;
 	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
 	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
 	struct crypto_ablkcipher *ablkcipher;
 	struct crypto_tfm *abtfm;

 	if (!crypto_mod_get(calg))
 		return -EAGAIN;

 	abtfm = __crypto_alloc_tfm(calg, 0, 0);
 	if (IS_ERR(abtfm)) {
 		crypto_mod_put(calg);
 		return PTR_ERR(abtfm);
 	}

 	ablkcipher = __crypto_ablkcipher_cast(abtfm);
 	*ctx = ablkcipher;
 	tfm->exit = crypto_exit_skcipher_ops_ablkcipher;

 	skcipher->setkey = skcipher_setkey_ablkcipher;
 	skcipher->encrypt = skcipher_encrypt_ablkcipher;
 	skcipher->decrypt = skcipher_decrypt_ablkcipher;

 	skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
 	skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
 			    sizeof(struct ablkcipher_request);
 	skcipher->keysize = calg->cra_ablkcipher.max_keysize;

 	return 0;
 }

 static void crypto_skcipher_exit_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
 	struct skcipher_alg *alg = crypto_skcipher_alg(skcipher);

 	alg->exit(skcipher);
 }

 static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
 	struct skcipher_alg *alg = crypto_skcipher_alg(skcipher);

 	if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
 		return crypto_init_skcipher_ops_blkcipher(tfm);

 	if (tfm->__crt_alg->cra_type == &crypto_ablkcipher_type ||
 	    tfm->__crt_alg->cra_type == &crypto_givcipher_type)
 		return crypto_init_skcipher_ops_ablkcipher(tfm);

 	skcipher->setkey = alg->setkey;
 	skcipher->encrypt = alg->encrypt;
 	skcipher->decrypt = alg->decrypt;
 	skcipher->ivsize = alg->ivsize;
 	skcipher->keysize = alg->max_keysize;

 	if (alg->exit)
 		skcipher->base.exit = crypto_skcipher_exit_tfm;

 	if (alg->init)
 		return alg->init(skcipher);

 	return 0;
 }

 static void crypto_skcipher_free_instance(struct crypto_instance *inst)
 {
 	struct skcipher_instance *skcipher =
 		container_of(inst, struct skcipher_instance, s.base);

 	skcipher->free(skcipher);
 }

 static void crypto_skcipher_show(struct seq_file *m, struct crypto_alg *alg)
 	__attribute__ ((unused));
 static void crypto_skcipher_show(struct seq_file *m, struct crypto_alg *alg)
 {
 	struct skcipher_alg *skcipher = container_of(alg, struct skcipher_alg,
 						     base);

 	seq_printf(m, "type         : skcipher\n");
 	seq_printf(m, "async        : %s\n",
 		   alg->cra_flags & CRYPTO_ALG_ASYNC ?  "yes" : "no");
 	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
 	seq_printf(m, "min keysize  : %u\n", skcipher->min_keysize);
 	seq_printf(m, "max keysize  : %u\n", skcipher->max_keysize);
 	seq_printf(m, "ivsize       : %u\n", skcipher->ivsize);
 	seq_printf(m, "chunksize    : %u\n", skcipher->chunksize);
 }

 #ifdef CONFIG_NET
 static int crypto_skcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
 {
 	struct crypto_report_blkcipher rblkcipher;
 	struct skcipher_alg *skcipher = container_of(alg, struct skcipher_alg,
 						     base);

 	strncpy(rblkcipher.type, "skcipher", sizeof(rblkcipher.type));
 	strncpy(rblkcipher.geniv, "<none>", sizeof(rblkcipher.geniv));

 	rblkcipher.blocksize = alg->cra_blocksize;
 	rblkcipher.min_keysize = skcipher->min_keysize;
 	rblkcipher.max_keysize = skcipher->max_keysize;
 	rblkcipher.ivsize = skcipher->ivsize;

 	if (nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
 		    sizeof(struct crypto_report_blkcipher), &rblkcipher))
 		goto nla_put_failure;
 	return 0;

 nla_put_failure:
 	return -EMSGSIZE;
 }
 #else
 static int crypto_skcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
 {
 	return -ENOSYS;
 }
 #endif

 static const struct crypto_type crypto_skcipher_type2 = {
 	.extsize = crypto_skcipher_extsize,
 	.init_tfm = crypto_skcipher_init_tfm,
 	.free = crypto_skcipher_free_instance,
 #ifdef CONFIG_PROC_FS
 	.show = crypto_skcipher_show,
 #endif
 	.report = crypto_skcipher_report,
 	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
 	.maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
 	.type = CRYPTO_ALG_TYPE_SKCIPHER,
 	.tfmsize = offsetof(struct crypto_skcipher, base),
 };

 int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn,
 			  const char *name, u32 type, u32 mask)
 {
 	spawn->base.frontend = &crypto_skcipher_type2;
 	return crypto_grab_spawn(&spawn->base, name, type, mask);
 }
 EXPORT_SYMBOL_GPL(crypto_grab_skcipher);

 struct crypto_skcipher *crypto_alloc_skcipher(const char *alg_name,
 					      u32 type, u32 mask)
 {
 	return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
 }
 EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);

 int crypto_has_skcipher2(const char *alg_name, u32 type, u32 mask)
 {
 	return crypto_type_has_alg(alg_name, &crypto_skcipher_type2,
 				   type, mask);
 }
 EXPORT_SYMBOL_GPL(crypto_has_skcipher2);

 static int skcipher_prepare_alg(struct skcipher_alg *alg)
 {
 	struct crypto_alg *base = &alg->base;

 	if (alg->ivsize > PAGE_SIZE / 8 || alg->chunksize > PAGE_SIZE / 8)
 		return -EINVAL;

 	if (!alg->chunksize)
 		alg->chunksize = base->cra_blocksize;

 	base->cra_type = &crypto_skcipher_type2;
 	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 	base->cra_flags |= CRYPTO_ALG_TYPE_SKCIPHER;

 	return 0;
 }

 int crypto_register_skcipher(struct skcipher_alg *alg)
 {
 	struct crypto_alg *base = &alg->base;
 	int err;

 	err = skcipher_prepare_alg(alg);
 	if (err)
 		return err;

 	return crypto_register_alg(base);
 }
 EXPORT_SYMBOL_GPL(crypto_register_skcipher);

 void crypto_unregister_skcipher(struct skcipher_alg *alg)
 {
 	crypto_unregister_alg(&alg->base);
 }
 EXPORT_SYMBOL_GPL(crypto_unregister_skcipher);

 int crypto_register_skciphers(struct skcipher_alg *algs, int count)
 {
 	int i, ret;

 	for (i = 0; i < count; i++) {
 		ret = crypto_register_skcipher(&algs[i]);
 		if (ret)
 			goto err;
 	}

 	return 0;

 err:
 	for (--i; i >= 0; --i)
 		crypto_unregister_skcipher(&algs[i]);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(crypto_register_skciphers);

 void crypto_unregister_skciphers(struct skcipher_alg *algs, int count)
 {
 	int i;

 	for (i = count - 1; i >= 0; --i)
 		crypto_unregister_skcipher(&algs[i]);
 }
 EXPORT_SYMBOL_GPL(crypto_unregister_skciphers);

 int skcipher_register_instance(struct crypto_template *tmpl,
 			   struct skcipher_instance *inst)
 {
 	int err;

 	err = skcipher_prepare_alg(&inst->alg);
 	if (err)
 		return err;

 	return crypto_register_instance(tmpl, skcipher_crypto_instance(inst));
 }
 EXPORT_SYMBOL_GPL(skcipher_register_instance);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Symmetric key cipher type");
	/*
	* Symmetric key cipher operations.
	*
	* Generic encrypt/decrypt wrapper for ciphers, handles operations across
	* multiple page boundaries by using temporary blocks. In user context,
	* the kernel is given a chance to schedule us once per page.
	*
	* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License as published by the Free
	* Software Foundation; either version 2 of the License, or (at your option)
	* any later version.
	*
	*/

	#include <crypto/internal/skcipher.h>
	#include <linux/bug.h>
	#include <linux/cryptouser.h>
	#include <linux/module.h>
	#include <linux/rtnetlink.h>
	#include <linux/seq_file.h>
	#include <net/netlink.h>

	#include "internal.h"

	static unsigned int crypto_skcipher_extsize(struct crypto_alg *alg)
	{
	if (alg->cra_type == &crypto_blkcipher_type)
	return sizeof(struct crypto_blkcipher *);

	if (alg->cra_type == &crypto_ablkcipher_type \|\|
	alg->cra_type == &crypto_givcipher_type)
	return sizeof(struct crypto_ablkcipher *);

	return crypto_alg_extsize(alg);
	}

	static int skcipher_setkey_blkcipher(struct crypto_skcipher *tfm,
	const u8 *key, unsigned int keylen)
	{
	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
	struct crypto_blkcipher blkcipher = ctx;
	int err;

	crypto_blkcipher_clear_flags(blkcipher, ~0);
	crypto_blkcipher_set_flags(blkcipher, crypto_skcipher_get_flags(tfm) &
	CRYPTO_TFM_REQ_MASK);
	err = crypto_blkcipher_setkey(blkcipher, key, keylen);
	crypto_skcipher_set_flags(tfm, crypto_blkcipher_get_flags(blkcipher) &
	CRYPTO_TFM_RES_MASK);

	return err;
	}

	static int skcipher_crypt_blkcipher(struct skcipher_request *req,
	int (crypt)(struct blkcipher_desc ,
	struct scatterlist *,
	struct scatterlist *,
	unsigned int))
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct crypto_blkcipher **ctx = crypto_skcipher_ctx(tfm);
	struct blkcipher_desc desc = {
	.tfm = *ctx,
	.info = req->iv,
	.flags = req->base.flags,
	};


	return crypt(&desc, req->dst, req->src, req->cryptlen);
	}

	static int skcipher_encrypt_blkcipher(struct skcipher_request *req)
	{
	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

	return skcipher_crypt_blkcipher(req, alg->encrypt);
	}

	static int skcipher_decrypt_blkcipher(struct skcipher_request *req)
	{
	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;

	return skcipher_crypt_blkcipher(req, alg->decrypt);
	}

	static void crypto_exit_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
	{
	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);

	crypto_free_blkcipher(*ctx);
	}

	static int crypto_init_skcipher_ops_blkcipher(struct crypto_tfm *tfm)
	{
	struct crypto_alg *calg = tfm->__crt_alg;
	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
	struct crypto_blkcipher **ctx = crypto_tfm_ctx(tfm);
	struct crypto_blkcipher *blkcipher;
	struct crypto_tfm *btfm;

	if (!crypto_mod_get(calg))
	return -EAGAIN;

	btfm = __crypto_alloc_tfm(calg, CRYPTO_ALG_TYPE_BLKCIPHER,
	CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(btfm)) {
	crypto_mod_put(calg);
	return PTR_ERR(btfm);
	}

	blkcipher = __crypto_blkcipher_cast(btfm);
	*ctx = blkcipher;
	tfm->exit = crypto_exit_skcipher_ops_blkcipher;

	skcipher->setkey = skcipher_setkey_blkcipher;
	skcipher->encrypt = skcipher_encrypt_blkcipher;
	skcipher->decrypt = skcipher_decrypt_blkcipher;

	skcipher->ivsize = crypto_blkcipher_ivsize(blkcipher);
	skcipher->keysize = calg->cra_blkcipher.max_keysize;

	return 0;
	}

	static int skcipher_setkey_ablkcipher(struct crypto_skcipher *tfm,
	const u8 *key, unsigned int keylen)
	{
	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
	struct crypto_ablkcipher ablkcipher = ctx;
	int err;

	crypto_ablkcipher_clear_flags(ablkcipher, ~0);
	crypto_ablkcipher_set_flags(ablkcipher,
	crypto_skcipher_get_flags(tfm) &
	CRYPTO_TFM_REQ_MASK);
	err = crypto_ablkcipher_setkey(ablkcipher, key, keylen);
	crypto_skcipher_set_flags(tfm,
	crypto_ablkcipher_get_flags(ablkcipher) &
	CRYPTO_TFM_RES_MASK);

	return err;
	}

	static int skcipher_crypt_ablkcipher(struct skcipher_request *req,
	int (crypt)(struct ablkcipher_request ))
	{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct crypto_ablkcipher **ctx = crypto_skcipher_ctx(tfm);
	struct ablkcipher_request *subreq = skcipher_request_ctx(req);

	ablkcipher_request_set_tfm(subreq, *ctx);
	ablkcipher_request_set_callback(subreq, skcipher_request_flags(req),
	req->base.complete, req->base.data);
	ablkcipher_request_set_crypt(subreq, req->src, req->dst, req->cryptlen,
	req->iv);

	return crypt(subreq);
	}

	static int skcipher_encrypt_ablkcipher(struct skcipher_request *req)
	{
	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;

	return skcipher_crypt_ablkcipher(req, alg->encrypt);
	}

	static int skcipher_decrypt_ablkcipher(struct skcipher_request *req)
	{
	struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
	struct crypto_tfm *tfm = crypto_skcipher_tfm(skcipher);
	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;

	return skcipher_crypt_ablkcipher(req, alg->decrypt);
	}

	static void crypto_exit_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
	{
	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);

	crypto_free_ablkcipher(*ctx);
	}

	static int crypto_init_skcipher_ops_ablkcipher(struct crypto_tfm *tfm)
	{
	struct crypto_alg *calg = tfm->__crt_alg;
	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
	struct crypto_ablkcipher **ctx = crypto_tfm_ctx(tfm);
	struct crypto_ablkcipher *ablkcipher;
	struct crypto_tfm *abtfm;

	if (!crypto_mod_get(calg))
	return -EAGAIN;

	abtfm = __crypto_alloc_tfm(calg, 0, 0);
	if (IS_ERR(abtfm)) {
	crypto_mod_put(calg);
	return PTR_ERR(abtfm);
	}

	ablkcipher = __crypto_ablkcipher_cast(abtfm);
	*ctx = ablkcipher;
	tfm->exit = crypto_exit_skcipher_ops_ablkcipher;

	skcipher->setkey = skcipher_setkey_ablkcipher;
	skcipher->encrypt = skcipher_encrypt_ablkcipher;
	skcipher->decrypt = skcipher_decrypt_ablkcipher;

	skcipher->ivsize = crypto_ablkcipher_ivsize(ablkcipher);
	skcipher->reqsize = crypto_ablkcipher_reqsize(ablkcipher) +
	sizeof(struct ablkcipher_request);
	skcipher->keysize = calg->cra_ablkcipher.max_keysize;

	return 0;
	}

	static void crypto_skcipher_exit_tfm(struct crypto_tfm *tfm)
	{
	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
	struct skcipher_alg *alg = crypto_skcipher_alg(skcipher);

	alg->exit(skcipher);
	}

	static int crypto_skcipher_init_tfm(struct crypto_tfm *tfm)
	{
	struct crypto_skcipher *skcipher = __crypto_skcipher_cast(tfm);
	struct skcipher_alg *alg = crypto_skcipher_alg(skcipher);

	if (tfm->__crt_alg->cra_type == &crypto_blkcipher_type)
	return crypto_init_skcipher_ops_blkcipher(tfm);

	if (tfm->__crt_alg->cra_type == &crypto_ablkcipher_type \|\|
	tfm->__crt_alg->cra_type == &crypto_givcipher_type)
	return crypto_init_skcipher_ops_ablkcipher(tfm);

	skcipher->setkey = alg->setkey;
	skcipher->encrypt = alg->encrypt;
	skcipher->decrypt = alg->decrypt;
	skcipher->ivsize = alg->ivsize;
	skcipher->keysize = alg->max_keysize;

	if (alg->exit)
	skcipher->base.exit = crypto_skcipher_exit_tfm;

	if (alg->init)
	return alg->init(skcipher);

	return 0;
	}

	static void crypto_skcipher_free_instance(struct crypto_instance *inst)
	{
	struct skcipher_instance *skcipher =
	container_of(inst, struct skcipher_instance, s.base);

	skcipher->free(skcipher);
	}

	static void crypto_skcipher_show(struct seq_file m, struct crypto_alg alg)
	__attribute__ ((unused));
	static void crypto_skcipher_show(struct seq_file m, struct crypto_alg alg)
	{
	struct skcipher_alg *skcipher = container_of(alg, struct skcipher_alg,
	base);

	seq_printf(m, "type : skcipher\n");
	seq_printf(m, "async : %s\n",
	alg->cra_flags & CRYPTO_ALG_ASYNC ? "yes" : "no");
	seq_printf(m, "blocksize : %u\n", alg->cra_blocksize);
	seq_printf(m, "min keysize : %u\n", skcipher->min_keysize);
	seq_printf(m, "max keysize : %u\n", skcipher->max_keysize);
	seq_printf(m, "ivsize : %u\n", skcipher->ivsize);
	seq_printf(m, "chunksize : %u\n", skcipher->chunksize);
	}

	#ifdef CONFIG_NET
	static int crypto_skcipher_report(struct sk_buff skb, struct crypto_alg alg)
	{
	struct crypto_report_blkcipher rblkcipher;
	struct skcipher_alg *skcipher = container_of(alg, struct skcipher_alg,
	base);

	strncpy(rblkcipher.type, "skcipher", sizeof(rblkcipher.type));
	strncpy(rblkcipher.geniv, "<none>", sizeof(rblkcipher.geniv));

	rblkcipher.blocksize = alg->cra_blocksize;
	rblkcipher.min_keysize = skcipher->min_keysize;
	rblkcipher.max_keysize = skcipher->max_keysize;
	rblkcipher.ivsize = skcipher->ivsize;

	if (nla_put(skb, CRYPTOCFGA_REPORT_BLKCIPHER,
	sizeof(struct crypto_report_blkcipher), &rblkcipher))
	goto nla_put_failure;
	return 0;

	nla_put_failure:
	return -EMSGSIZE;
	}
	#else
	static int crypto_skcipher_report(struct sk_buff skb, struct crypto_alg alg)
	{
	return -ENOSYS;
	}
	#endif

	static const struct crypto_type crypto_skcipher_type2 = {
	.extsize = crypto_skcipher_extsize,
	.init_tfm = crypto_skcipher_init_tfm,
	.free = crypto_skcipher_free_instance,
	#ifdef CONFIG_PROC_FS
	.show = crypto_skcipher_show,
	#endif
	.report = crypto_skcipher_report,
	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
	.maskset = CRYPTO_ALG_TYPE_BLKCIPHER_MASK,
	.type = CRYPTO_ALG_TYPE_SKCIPHER,
	.tfmsize = offsetof(struct crypto_skcipher, base),
	};

	int crypto_grab_skcipher(struct crypto_skcipher_spawn *spawn,
	const char *name, u32 type, u32 mask)
	{
	spawn->base.frontend = &crypto_skcipher_type2;
	return crypto_grab_spawn(&spawn->base, name, type, mask);
	}
	EXPORT_SYMBOL_GPL(crypto_grab_skcipher);

	struct crypto_skcipher crypto_alloc_skcipher(const char alg_name,
	u32 type, u32 mask)
	{
	return crypto_alloc_tfm(alg_name, &crypto_skcipher_type2, type, mask);
	}
	EXPORT_SYMBOL_GPL(crypto_alloc_skcipher);

	int crypto_has_skcipher2(const char *alg_name, u32 type, u32 mask)
	{
	return crypto_type_has_alg(alg_name, &crypto_skcipher_type2,
	type, mask);
	}
	EXPORT_SYMBOL_GPL(crypto_has_skcipher2);

	static int skcipher_prepare_alg(struct skcipher_alg *alg)
	{
	struct crypto_alg *base = &alg->base;

	if (alg->ivsize > PAGE_SIZE / 8 \|\| alg->chunksize > PAGE_SIZE / 8)
	return -EINVAL;

	if (!alg->chunksize)
	alg->chunksize = base->cra_blocksize;

	base->cra_type = &crypto_skcipher_type2;
	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
	base->cra_flags \|= CRYPTO_ALG_TYPE_SKCIPHER;

	return 0;
	}

	int crypto_register_skcipher(struct skcipher_alg *alg)
	{
	struct crypto_alg *base = &alg->base;
	int err;

	err = skcipher_prepare_alg(alg);
	if (err)
	return err;

	return crypto_register_alg(base);
	}
	EXPORT_SYMBOL_GPL(crypto_register_skcipher);

	void crypto_unregister_skcipher(struct skcipher_alg *alg)
	{
	crypto_unregister_alg(&alg->base);
	}
	EXPORT_SYMBOL_GPL(crypto_unregister_skcipher);

	int crypto_register_skciphers(struct skcipher_alg *algs, int count)
	{
	int i, ret;

	for (i = 0; i < count; i++) {
	ret = crypto_register_skcipher(&algs[i]);
	if (ret)
	goto err;
	}

	return 0;

	err:
	for (--i; i >= 0; --i)
	crypto_unregister_skcipher(&algs[i]);

	return ret;
	}
	EXPORT_SYMBOL_GPL(crypto_register_skciphers);

	void crypto_unregister_skciphers(struct skcipher_alg *algs, int count)
	{
	int i;

	for (i = count - 1; i >= 0; --i)
	crypto_unregister_skcipher(&algs[i]);
	}
	EXPORT_SYMBOL_GPL(crypto_unregister_skciphers);

	int skcipher_register_instance(struct crypto_template *tmpl,
	struct skcipher_instance *inst)
	{
	int err;

	err = skcipher_prepare_alg(&inst->alg);
	if (err)
	return err;

	return crypto_register_instance(tmpl, skcipher_crypto_instance(inst));
	}
	EXPORT_SYMBOL_GPL(skcipher_register_instance);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("Symmetric key cipher type");