crypto/ctr.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * CTR: Counter mode
  *
  * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
  *
  * 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/algapi.h>
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/random.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>

 struct ctr_instance_ctx {
 	struct crypto_spawn alg;
 	unsigned int noncesize;
 	unsigned int ivsize;
 	unsigned int countersize;
 };

 struct crypto_ctr_ctx {
 	struct crypto_cipher *child;
 	u8 *nonce;
 };

 static inline void __ctr_inc_byte(u8 *a, unsigned int size)
 {
 	u8 *b = (a + size);
 	u8 c;

 	for (; size; size--) {
 		c = *--b + 1;
 		*b = c;
 		if (c)
 			break;
 	}
 }

 static void ctr_inc_quad(u8 *a, unsigned int size)
 {
 	__be32 *b = (__be32 *)(a + size);
 	u32 c;

 	for (; size >= 4; size -=4) {
 		c = be32_to_cpu(*--b) + 1;
 		*b = cpu_to_be32(c);
 		if (c)
 			return;
 	}

 	__ctr_inc_byte(a, size);
 }

 static void xor_byte(u8 *a, const u8 *b, unsigned int bs)
 {
 	for (; bs; bs--)
 		*a++ ^= *b++;
 }

 static void xor_quad(u8 *dst, const u8 *src, unsigned int bs)
 {
 	u32 *a = (u32 *)dst;
 	u32 *b = (u32 *)src;

 	for (; bs >= 4; bs -= 4)
 		*a++ ^= *b++;

 	xor_byte((u8 *)a, (u8 *)b, bs);
 }

 static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key,
 			     unsigned int keylen)
 {
 	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
 	struct crypto_cipher *child = ctx->child;
 	struct ctr_instance_ctx *ictx =
 		crypto_instance_ctx(crypto_tfm_alg_instance(parent));
 	unsigned int noncelen = ictx->noncesize;
 	int err = 0;

 	/* the nonce is stored in bytes at end of key */
 	if (keylen < noncelen)
 		return  -EINVAL;

 	memcpy(ctx->nonce, key + (keylen - noncelen), noncelen);

 	keylen -=  noncelen;

 	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
 				CRYPTO_TFM_REQ_MASK);
 	err = crypto_cipher_setkey(child, key, keylen);
 	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
 			     CRYPTO_TFM_RES_MASK);

 	return err;
 }

 static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
 				    struct crypto_cipher *tfm, u8 *ctrblk,
 				    unsigned int countersize)
 {
 	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 		   crypto_cipher_alg(tfm)->cia_encrypt;
 	unsigned int bsize = crypto_cipher_blocksize(tfm);
 	unsigned long alignmask = crypto_cipher_alignmask(tfm);
 	u8 ks[bsize + alignmask];
 	u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);
 	u8 *src = walk->src.virt.addr;
 	u8 *dst = walk->dst.virt.addr;
 	unsigned int nbytes = walk->nbytes;

 	do {
 		/* create keystream */
 		fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
 		xor_quad(keystream, src, min(nbytes, bsize));

 		/* copy result into dst */
 		memcpy(dst, keystream, min(nbytes, bsize));

 		/* increment counter in counterblock */
 		ctr_inc_quad(ctrblk + (bsize - countersize), countersize);

 		if (nbytes < bsize)
 			break;

 		src += bsize;
 		dst += bsize;
 		nbytes -= bsize;

 	} while (nbytes);

 	return 0;
 }

 static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
 				    struct crypto_cipher *tfm, u8 *ctrblk,
 				    unsigned int countersize)
 {
 	void (*fn)(struct crypto_tfm *, u8 *, const u8 *) =
 		   crypto_cipher_alg(tfm)->cia_encrypt;
 	unsigned int bsize = crypto_cipher_blocksize(tfm);
 	unsigned long alignmask = crypto_cipher_alignmask(tfm);
 	unsigned int nbytes = walk->nbytes;
 	u8 *src = walk->src.virt.addr;
 	u8 ks[bsize + alignmask];
 	u8 *keystream = (u8 *)ALIGN((unsigned long)ks, alignmask + 1);

 	do {
 		/* create keystream */
 		fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
 		xor_quad(src, keystream, min(nbytes, bsize));

 		/* increment counter in counterblock */
 		ctr_inc_quad(ctrblk + (bsize - countersize), countersize);

 		if (nbytes < bsize)
 			break;

 		src += bsize;
 		nbytes -= bsize;

 	} while (nbytes);

 	return 0;
 }

 static int crypto_ctr_crypt(struct blkcipher_desc *desc,
 			      struct scatterlist *dst, struct scatterlist *src,
 			      unsigned int nbytes)
 {
 	struct blkcipher_walk walk;
 	struct crypto_blkcipher *tfm = desc->tfm;
 	struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
 	struct crypto_cipher *child = ctx->child;
 	unsigned int bsize = crypto_cipher_blocksize(child);
 	struct ctr_instance_ctx *ictx =
 		crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
 	unsigned long alignmask = crypto_cipher_alignmask(child);
 	u8 cblk[bsize + alignmask];
 	u8 *counterblk = (u8 *)ALIGN((unsigned long)cblk, alignmask + 1);
 	int err;

 	blkcipher_walk_init(&walk, dst, src, nbytes);
 	err = blkcipher_walk_virt_block(desc, &walk, bsize);

 	/* set up counter block */
 	memset(counterblk, 0 , bsize);
 	memcpy(counterblk, ctx->nonce, ictx->noncesize);
 	memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize);

 	/* initialize counter portion of counter block */
 	ctr_inc_quad(counterblk + (bsize - ictx->countersize),
 		     ictx->countersize);

 	while (walk.nbytes) {
 		if (walk.src.virt.addr == walk.dst.virt.addr)
 			nbytes = crypto_ctr_crypt_inplace(&walk, child,
 							  counterblk,
 							  ictx->countersize);
 		else
 			nbytes = crypto_ctr_crypt_segment(&walk, child,
 							  counterblk,
 							  ictx->countersize);

 		err = blkcipher_walk_done(desc, &walk, nbytes);
 	}
 	return err;
 }

 static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_instance *inst = (void *)tfm->__crt_alg;
 	struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
 	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
 	struct crypto_cipher *cipher;

 	ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL);
 	if (!ctx->nonce)
 		return -ENOMEM;

 	cipher = crypto_spawn_cipher(&ictx->alg);
 	if (IS_ERR(cipher))
 		return PTR_ERR(cipher);

 	ctx->child = cipher;

 	return 0;
 }

 static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
 {
 	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);

 	kfree(ctx->nonce);
 	crypto_free_cipher(ctx->child);
 }

 static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb)
 {
 	struct crypto_instance *inst;
 	struct crypto_alg *alg;
 	struct ctr_instance_ctx *ictx;
 	unsigned int noncesize;
 	unsigned int ivsize;
 	unsigned int countersize;
 	int err;

 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
 	if (err)
 		return ERR_PTR(err);

 	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
 				  CRYPTO_ALG_TYPE_MASK);
 	if (IS_ERR(alg))
 		return ERR_PTR(PTR_ERR(alg));

 	err = crypto_attr_u32(tb[2], &noncesize);
 	if (err)
 		goto out_put_alg;

 	err = crypto_attr_u32(tb[3], &ivsize);
 	if (err)
 		goto out_put_alg;

 	err = crypto_attr_u32(tb[4], &countersize);
 	if (err)
 		goto out_put_alg;

 	/* verify size of nonce + iv + counter
 	 * counter must be >= 4 bytes.
 	 */
 	err = -EINVAL;
 	if (((noncesize + ivsize + countersize) < alg->cra_blocksize) ||
 	    ((noncesize + ivsize) > alg->cra_blocksize) ||
 	    (countersize > alg->cra_blocksize) || (countersize < 4))
 		goto out_put_alg;

 	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
 	err = -ENOMEM;
 	if (!inst)
 		goto out_put_alg;

 	err = -ENAMETOOLONG;
 	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
 		     "ctr(%s,%u,%u,%u)", alg->cra_name, noncesize,
 		     ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
 		goto err_free_inst;
 	}

 	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 		     "ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize,
 		     ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
 		goto err_free_inst;
 	}

 	ictx = crypto_instance_ctx(inst);
 	ictx->noncesize = noncesize;
 	ictx->ivsize = ivsize;
 	ictx->countersize = countersize;

 	err = crypto_init_spawn(&ictx->alg, alg, inst,
 		CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_ASYNC);
 	if (err)
 		goto err_free_inst;

 	err = 0;
 	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
 	inst->alg.cra_priority = alg->cra_priority;
 	inst->alg.cra_blocksize = 1;
 	inst->alg.cra_alignmask = 3;
 	inst->alg.cra_type = &crypto_blkcipher_type;

 	inst->alg.cra_blkcipher.ivsize = ivsize;
 	inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize
 					      + noncesize;
 	inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
 					      + noncesize;

 	inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);

 	inst->alg.cra_init = crypto_ctr_init_tfm;
 	inst->alg.cra_exit = crypto_ctr_exit_tfm;

 	inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
 	inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
 	inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;

 err_free_inst:
 	if (err)
 		kfree(inst);

 out_put_alg:
 	crypto_mod_put(alg);

 	if (err)
 		inst = ERR_PTR(err);

 	return inst;
 }

 static void crypto_ctr_free(struct crypto_instance *inst)
 {
 	struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);

 	crypto_drop_spawn(&ictx->alg);
 	kfree(inst);
 }

 static struct crypto_template crypto_ctr_tmpl = {
 	.name = "ctr",
 	.alloc = crypto_ctr_alloc,
 	.free = crypto_ctr_free,
 	.module = THIS_MODULE,
 };

 static int __init crypto_ctr_module_init(void)
 {
 	return crypto_register_template(&crypto_ctr_tmpl);
 }

 static void __exit crypto_ctr_module_exit(void)
 {
 	crypto_unregister_template(&crypto_ctr_tmpl);
 }

 module_init(crypto_ctr_module_init);
 module_exit(crypto_ctr_module_exit);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("CTR Counter block mode");
	/*
	* CTR: Counter mode
	*
	* (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com>
	*
	* 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/algapi.h>
	#include <linux/err.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/random.h>
	#include <linux/scatterlist.h>
	#include <linux/slab.h>

	struct ctr_instance_ctx {
	struct crypto_spawn alg;
	unsigned int noncesize;
	unsigned int ivsize;
	unsigned int countersize;
	};

	struct crypto_ctr_ctx {
	struct crypto_cipher *child;
	u8 *nonce;
	};

	static inline void __ctr_inc_byte(u8 *a, unsigned int size)
	{
	u8 *b = (a + size);
	u8 c;

	for (; size; size--) {
	c = *--b + 1;
	*b = c;
	if (c)
	break;
	}
	}

	static void ctr_inc_quad(u8 *a, unsigned int size)
	{
	__be32 b = (__be32 )(a + size);
	u32 c;

	for (; size >= 4; size -=4) {
	c = be32_to_cpu(*--b) + 1;
	*b = cpu_to_be32(c);
	if (c)
	return;
	}

	__ctr_inc_byte(a, size);
	}

	static void xor_byte(u8 a, const u8 b, unsigned int bs)
	{
	for (; bs; bs--)
	a++ ^= b++;
	}

	static void xor_quad(u8 dst, const u8 src, unsigned int bs)
	{
	u32 a = (u32 )dst;
	u32 b = (u32 )src;

	for (; bs >= 4; bs -= 4)
	a++ ^= b++;

	xor_byte((u8 )a, (u8 )b, bs);
	}

	static int crypto_ctr_setkey(struct crypto_tfm parent, const u8 key,
	unsigned int keylen)
	{
	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent);
	struct crypto_cipher *child = ctx->child;
	struct ctr_instance_ctx *ictx =
	crypto_instance_ctx(crypto_tfm_alg_instance(parent));
	unsigned int noncelen = ictx->noncesize;
	int err = 0;

	/* the nonce is stored in bytes at end of key */
	if (keylen < noncelen)
	return -EINVAL;

	memcpy(ctx->nonce, key + (keylen - noncelen), noncelen);

	keylen -= noncelen;

	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
	CRYPTO_TFM_REQ_MASK);
	err = crypto_cipher_setkey(child, key, keylen);
	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
	CRYPTO_TFM_RES_MASK);

	return err;
	}

	static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk,
	struct crypto_cipher tfm, u8 ctrblk,
	unsigned int countersize)
	{
	void (fn)(struct crypto_tfm , u8 , const u8 ) =
	crypto_cipher_alg(tfm)->cia_encrypt;
	unsigned int bsize = crypto_cipher_blocksize(tfm);
	unsigned long alignmask = crypto_cipher_alignmask(tfm);
	u8 ks[bsize + alignmask];
	u8 keystream = (u8 )ALIGN((unsigned long)ks, alignmask + 1);
	u8 *src = walk->src.virt.addr;
	u8 *dst = walk->dst.virt.addr;
	unsigned int nbytes = walk->nbytes;

	do {
	/* create keystream */
	fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
	xor_quad(keystream, src, min(nbytes, bsize));

	/* copy result into dst */
	memcpy(dst, keystream, min(nbytes, bsize));

	/* increment counter in counterblock */
	ctr_inc_quad(ctrblk + (bsize - countersize), countersize);

	if (nbytes < bsize)
	break;

	src += bsize;
	dst += bsize;
	nbytes -= bsize;

	} while (nbytes);

	return 0;
	}

	static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk,
	struct crypto_cipher tfm, u8 ctrblk,
	unsigned int countersize)
	{
	void (fn)(struct crypto_tfm , u8 , const u8 ) =
	crypto_cipher_alg(tfm)->cia_encrypt;
	unsigned int bsize = crypto_cipher_blocksize(tfm);
	unsigned long alignmask = crypto_cipher_alignmask(tfm);
	unsigned int nbytes = walk->nbytes;
	u8 *src = walk->src.virt.addr;
	u8 ks[bsize + alignmask];
	u8 keystream = (u8 )ALIGN((unsigned long)ks, alignmask + 1);

	do {
	/* create keystream */
	fn(crypto_cipher_tfm(tfm), keystream, ctrblk);
	xor_quad(src, keystream, min(nbytes, bsize));

	/* increment counter in counterblock */
	ctr_inc_quad(ctrblk + (bsize - countersize), countersize);

	if (nbytes < bsize)
	break;

	src += bsize;
	nbytes -= bsize;

	} while (nbytes);

	return 0;
	}

	static int crypto_ctr_crypt(struct blkcipher_desc *desc,
	struct scatterlist dst, struct scatterlist src,
	unsigned int nbytes)
	{
	struct blkcipher_walk walk;
	struct crypto_blkcipher *tfm = desc->tfm;
	struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm);
	struct crypto_cipher *child = ctx->child;
	unsigned int bsize = crypto_cipher_blocksize(child);
	struct ctr_instance_ctx *ictx =
	crypto_instance_ctx(crypto_tfm_alg_instance(&tfm->base));
	unsigned long alignmask = crypto_cipher_alignmask(child);
	u8 cblk[bsize + alignmask];
	u8 counterblk = (u8 )ALIGN((unsigned long)cblk, alignmask + 1);
	int err;

	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt_block(desc, &walk, bsize);

	/* set up counter block */
	memset(counterblk, 0 , bsize);
	memcpy(counterblk, ctx->nonce, ictx->noncesize);
	memcpy(counterblk + ictx->noncesize, walk.iv, ictx->ivsize);

	/* initialize counter portion of counter block */
	ctr_inc_quad(counterblk + (bsize - ictx->countersize),
	ictx->countersize);

	while (walk.nbytes) {
	if (walk.src.virt.addr == walk.dst.virt.addr)
	nbytes = crypto_ctr_crypt_inplace(&walk, child,
	counterblk,
	ictx->countersize);
	else
	nbytes = crypto_ctr_crypt_segment(&walk, child,
	counterblk,
	ictx->countersize);

	err = blkcipher_walk_done(desc, &walk, nbytes);
	}
	return err;
	}

	static int crypto_ctr_init_tfm(struct crypto_tfm *tfm)
	{
	struct crypto_instance inst = (void )tfm->__crt_alg;
	struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);
	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
	struct crypto_cipher *cipher;

	ctx->nonce = kzalloc(ictx->noncesize, GFP_KERNEL);
	if (!ctx->nonce)
	return -ENOMEM;

	cipher = crypto_spawn_cipher(&ictx->alg);
	if (IS_ERR(cipher))
	return PTR_ERR(cipher);

	ctx->child = cipher;

	return 0;
	}

	static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm)
	{
	struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm);

	kfree(ctx->nonce);
	crypto_free_cipher(ctx->child);
	}

	static struct crypto_instance crypto_ctr_alloc(struct rtattr *tb)
	{
	struct crypto_instance *inst;
	struct crypto_alg *alg;
	struct ctr_instance_ctx *ictx;
	unsigned int noncesize;
	unsigned int ivsize;
	unsigned int countersize;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
	if (err)
	return ERR_PTR(err);

	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
	CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
	return ERR_PTR(PTR_ERR(alg));

	err = crypto_attr_u32(tb[2], &noncesize);
	if (err)
	goto out_put_alg;

	err = crypto_attr_u32(tb[3], &ivsize);
	if (err)
	goto out_put_alg;

	err = crypto_attr_u32(tb[4], &countersize);
	if (err)
	goto out_put_alg;

	/* verify size of nonce + iv + counter
	* counter must be >= 4 bytes.
	*/
	err = -EINVAL;
	if (((noncesize + ivsize + countersize) < alg->cra_blocksize) \|\|
	((noncesize + ivsize) > alg->cra_blocksize) \|\|
	(countersize > alg->cra_blocksize) \|\| (countersize < 4))
	goto out_put_alg;

	inst = kzalloc(sizeof(inst) + sizeof(ictx), GFP_KERNEL);
	err = -ENOMEM;
	if (!inst)
	goto out_put_alg;

	err = -ENAMETOOLONG;
	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
	"ctr(%s,%u,%u,%u)", alg->cra_name, noncesize,
	ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
	goto err_free_inst;
	}

	if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
	"ctr(%s,%u,%u,%u)", alg->cra_driver_name, noncesize,
	ivsize, countersize) >= CRYPTO_MAX_ALG_NAME) {
	goto err_free_inst;
	}

	ictx = crypto_instance_ctx(inst);
	ictx->noncesize = noncesize;
	ictx->ivsize = ivsize;
	ictx->countersize = countersize;

	err = crypto_init_spawn(&ictx->alg, alg, inst,
	CRYPTO_ALG_TYPE_MASK \| CRYPTO_ALG_ASYNC);
	if (err)
	goto err_free_inst;

	err = 0;
	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
	inst->alg.cra_priority = alg->cra_priority;
	inst->alg.cra_blocksize = 1;
	inst->alg.cra_alignmask = 3;
	inst->alg.cra_type = &crypto_blkcipher_type;

	inst->alg.cra_blkcipher.ivsize = ivsize;
	inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize
	+ noncesize;
	inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize
	+ noncesize;

	inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx);

	inst->alg.cra_init = crypto_ctr_init_tfm;
	inst->alg.cra_exit = crypto_ctr_exit_tfm;

	inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey;
	inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt;
	inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt;

	err_free_inst:
	if (err)
	kfree(inst);

	out_put_alg:
	crypto_mod_put(alg);

	if (err)
	inst = ERR_PTR(err);

	return inst;
	}

	static void crypto_ctr_free(struct crypto_instance *inst)
	{
	struct ctr_instance_ctx *ictx = crypto_instance_ctx(inst);

	crypto_drop_spawn(&ictx->alg);
	kfree(inst);
	}

	static struct crypto_template crypto_ctr_tmpl = {
	.name = "ctr",
	.alloc = crypto_ctr_alloc,
	.free = crypto_ctr_free,
	.module = THIS_MODULE,
	};

	static int __init crypto_ctr_module_init(void)
	{
	return crypto_register_template(&crypto_ctr_tmpl);
	}

	static void __exit crypto_ctr_module_exit(void)
	{
	crypto_unregister_template(&crypto_ctr_tmpl);
	}

	module_init(crypto_ctr_module_init);
	module_exit(crypto_ctr_module_exit);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("CTR Counter block mode");