/*
   * Block chaining 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) 2006 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/aead.h>

  #include <crypto/internal/skcipher.h>

  #include <crypto/scatterwalk.h>

  #include <linux/errno.h>

  #include <linux/hardirq.h>

  #include <linux/kernel.h>

  #include <linux/module.h>
  #include <linux/scatterlist.h>
  #include <linux/seq_file.h>
  #include <linux/slab.h>
  #include <linux/string.h>

  #include <linux/cryptouser.h>
  #include <net/netlink.h>

  
  #include "internal.h"

  
  enum {
  	BLKCIPHER_WALK_PHYS = 1 << 0,
  	BLKCIPHER_WALK_SLOW = 1 << 1,
  	BLKCIPHER_WALK_COPY = 1 << 2,
  	BLKCIPHER_WALK_DIFF = 1 << 3,
  };
  
  static int blkcipher_walk_next(struct blkcipher_desc *desc,
  			       struct blkcipher_walk *walk);
  static int blkcipher_walk_first(struct blkcipher_desc *desc,
  				struct blkcipher_walk *walk);
  
  static inline void blkcipher_map_src(struct blkcipher_walk *walk)
  {

  	walk->src.virt.addr = scatterwalk_map(&walk->in);

  }
  
  static inline void blkcipher_map_dst(struct blkcipher_walk *walk)
  {

  	walk->dst.virt.addr = scatterwalk_map(&walk->out);

  }
  
  static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)
  {

  	scatterwalk_unmap(walk->src.virt.addr);

  }
  
  static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)
  {

  	scatterwalk_unmap(walk->dst.virt.addr);

  }

  /* Get a spot of the specified length that does not straddle a page.
   * The caller needs to ensure that there is enough space for this operation.
   */

  static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
  {

  	u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);

  	return max(start, end_page);

  }

  static inline unsigned int blkcipher_done_slow(struct blkcipher_walk *walk,

  					       unsigned int bsize)
  {
  	u8 *addr;

  	addr = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);

  	addr = blkcipher_get_spot(addr, bsize);
  	scatterwalk_copychunks(addr, &walk->out, bsize, 1);
  	return bsize;
  }
  
  static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,
  					       unsigned int n)
  {

  	if (walk->flags & BLKCIPHER_WALK_COPY) {
  		blkcipher_map_dst(walk);
  		memcpy(walk->dst.virt.addr, walk->page, n);
  		blkcipher_unmap_dst(walk);
  	} else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {

  		if (walk->flags & BLKCIPHER_WALK_DIFF)
  			blkcipher_unmap_dst(walk);

  		blkcipher_unmap_src(walk);

  	}
  
  	scatterwalk_advance(&walk->in, n);
  	scatterwalk_advance(&walk->out, n);
  
  	return n;
  }
  
  int blkcipher_walk_done(struct blkcipher_desc *desc,
  			struct blkcipher_walk *walk, int err)
  {

  	unsigned int nbytes = 0;
  
  	if (likely(err >= 0)) {

  		unsigned int n = walk->nbytes - err;

  
  		if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))

  			n = blkcipher_done_fast(walk, n);
  		else if (WARN_ON(err)) {
  			err = -EINVAL;
  			goto err;
  		} else

  			n = blkcipher_done_slow(walk, n);

  
  		nbytes = walk->total - n;
  		err = 0;
  	}
  
  	scatterwalk_done(&walk->in, 0, nbytes);
  	scatterwalk_done(&walk->out, 1, nbytes);

  err:

  	walk->total = nbytes;
  	walk->nbytes = nbytes;
  
  	if (nbytes) {
  		crypto_yield(desc->flags);
  		return blkcipher_walk_next(desc, walk);
  	}
  
  	if (walk->iv != desc->info)

  		memcpy(desc->info, walk->iv, walk->ivsize);

  	if (walk->buffer != walk->page)
  		kfree(walk->buffer);
  	if (walk->page)
  		free_page((unsigned long)walk->page);
  
  	return err;
  }
  EXPORT_SYMBOL_GPL(blkcipher_walk_done);
  
  static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
  				      struct blkcipher_walk *walk,
  				      unsigned int bsize,
  				      unsigned int alignmask)
  {
  	unsigned int n;

  	unsigned aligned_bsize = ALIGN(bsize, alignmask + 1);

  
  	if (walk->buffer)
  		goto ok;
  
  	walk->buffer = walk->page;
  	if (walk->buffer)
  		goto ok;

  	n = aligned_bsize * 3 - (alignmask + 1) +

  	    (alignmask & ~(crypto_tfm_ctx_alignment() - 1));

  	walk->buffer = kmalloc(n, GFP_ATOMIC);
  	if (!walk->buffer)
  		return blkcipher_walk_done(desc, walk, -ENOMEM);
  
  ok:
  	walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
  					  alignmask + 1);
  	walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);

  	walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr +
  						 aligned_bsize, bsize);

  
  	scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
  
  	walk->nbytes = bsize;
  	walk->flags |= BLKCIPHER_WALK_SLOW;
  
  	return 0;
  }
  
  static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
  {
  	u8 *tmp = walk->page;
  
  	blkcipher_map_src(walk);
  	memcpy(tmp, walk->src.virt.addr, walk->nbytes);
  	blkcipher_unmap_src(walk);
  
  	walk->src.virt.addr = tmp;
  	walk->dst.virt.addr = tmp;
  
  	return 0;
  }
  
  static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
  				      struct blkcipher_walk *walk)
  {
  	unsigned long diff;
  
  	walk->src.phys.page = scatterwalk_page(&walk->in);
  	walk->src.phys.offset = offset_in_page(walk->in.offset);
  	walk->dst.phys.page = scatterwalk_page(&walk->out);
  	walk->dst.phys.offset = offset_in_page(walk->out.offset);
  
  	if (walk->flags & BLKCIPHER_WALK_PHYS)
  		return 0;
  
  	diff = walk->src.phys.offset - walk->dst.phys.offset;
  	diff |= walk->src.virt.page - walk->dst.virt.page;
  
  	blkcipher_map_src(walk);
  	walk->dst.virt.addr = walk->src.virt.addr;
  
  	if (diff) {
  		walk->flags |= BLKCIPHER_WALK_DIFF;
  		blkcipher_map_dst(walk);
  	}
  
  	return 0;
  }
  
  static int blkcipher_walk_next(struct blkcipher_desc *desc,
  			       struct blkcipher_walk *walk)
  {

  	unsigned int bsize;

  	unsigned int n;
  	int err;
  
  	n = walk->total;

  	if (unlikely(n < walk->cipher_blocksize)) {

  		desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
  		return blkcipher_walk_done(desc, walk, -EINVAL);
  	}
  
  	walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
  			 BLKCIPHER_WALK_DIFF);

  	if (!scatterwalk_aligned(&walk->in, walk->alignmask) ||
  	    !scatterwalk_aligned(&walk->out, walk->alignmask)) {

  		walk->flags |= BLKCIPHER_WALK_COPY;
  		if (!walk->page) {
  			walk->page = (void *)__get_free_page(GFP_ATOMIC);
  			if (!walk->page)
  				n = 0;
  		}
  	}

  	bsize = min(walk->walk_blocksize, n);

  	n = scatterwalk_clamp(&walk->in, n);
  	n = scatterwalk_clamp(&walk->out, n);
  
  	if (unlikely(n < bsize)) {

  		err = blkcipher_next_slow(desc, walk, bsize, walk->alignmask);

  		goto set_phys_lowmem;
  	}
  
  	walk->nbytes = n;
  	if (walk->flags & BLKCIPHER_WALK_COPY) {
  		err = blkcipher_next_copy(walk);
  		goto set_phys_lowmem;
  	}
  
  	return blkcipher_next_fast(desc, walk);
  
  set_phys_lowmem:
  	if (walk->flags & BLKCIPHER_WALK_PHYS) {
  		walk->src.phys.page = virt_to_page(walk->src.virt.addr);
  		walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
  		walk->src.phys.offset &= PAGE_SIZE - 1;
  		walk->dst.phys.offset &= PAGE_SIZE - 1;
  	}
  	return err;
  }

  static inline int blkcipher_copy_iv(struct blkcipher_walk *walk)

  {

  	unsigned bs = walk->walk_blocksize;
  	unsigned aligned_bs = ALIGN(bs, walk->alignmask + 1);
  	unsigned int size = aligned_bs * 2 +
  			    walk->ivsize + max(aligned_bs, walk->ivsize) -
  			    (walk->alignmask + 1);

  	u8 *iv;

  	size += walk->alignmask & ~(crypto_tfm_ctx_alignment() - 1);

  	walk->buffer = kmalloc(size, GFP_ATOMIC);
  	if (!walk->buffer)
  		return -ENOMEM;

  	iv = (u8 *)ALIGN((unsigned long)walk->buffer, walk->alignmask + 1);

  	iv = blkcipher_get_spot(iv, bs) + aligned_bs;
  	iv = blkcipher_get_spot(iv, bs) + aligned_bs;

  	iv = blkcipher_get_spot(iv, walk->ivsize);

  	walk->iv = memcpy(iv, walk->iv, walk->ivsize);

  	return 0;
  }
  
  int blkcipher_walk_virt(struct blkcipher_desc *desc,
  			struct blkcipher_walk *walk)
  {
  	walk->flags &= ~BLKCIPHER_WALK_PHYS;

  	walk->walk_blocksize = crypto_blkcipher_blocksize(desc->tfm);
  	walk->cipher_blocksize = walk->walk_blocksize;
  	walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
  	walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);

  	return blkcipher_walk_first(desc, walk);
  }
  EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
  
  int blkcipher_walk_phys(struct blkcipher_desc *desc,
  			struct blkcipher_walk *walk)
  {
  	walk->flags |= BLKCIPHER_WALK_PHYS;

  	walk->walk_blocksize = crypto_blkcipher_blocksize(desc->tfm);
  	walk->cipher_blocksize = walk->walk_blocksize;
  	walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
  	walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);

  	return blkcipher_walk_first(desc, walk);
  }
  EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
  
  static int blkcipher_walk_first(struct blkcipher_desc *desc,
  				struct blkcipher_walk *walk)
  {

  	if (WARN_ON_ONCE(in_irq()))
  		return -EDEADLK;

  	walk->nbytes = walk->total;
  	if (unlikely(!walk->total))
  		return 0;
  
  	walk->buffer = NULL;
  	walk->iv = desc->info;

  	if (unlikely(((unsigned long)walk->iv & walk->alignmask))) {
  		int err = blkcipher_copy_iv(walk);

  		if (err)
  			return err;
  	}
  
  	scatterwalk_start(&walk->in, walk->in.sg);
  	scatterwalk_start(&walk->out, walk->out.sg);
  	walk->page = NULL;
  
  	return blkcipher_walk_next(desc, walk);
  }

  int blkcipher_walk_virt_block(struct blkcipher_desc *desc,
  			      struct blkcipher_walk *walk,
  			      unsigned int blocksize)
  {
  	walk->flags &= ~BLKCIPHER_WALK_PHYS;

  	walk->walk_blocksize = blocksize;
  	walk->cipher_blocksize = crypto_blkcipher_blocksize(desc->tfm);
  	walk->ivsize = crypto_blkcipher_ivsize(desc->tfm);
  	walk->alignmask = crypto_blkcipher_alignmask(desc->tfm);

  	return blkcipher_walk_first(desc, walk);
  }
  EXPORT_SYMBOL_GPL(blkcipher_walk_virt_block);

  int blkcipher_aead_walk_virt_block(struct blkcipher_desc *desc,
  				   struct blkcipher_walk *walk,
  				   struct crypto_aead *tfm,
  				   unsigned int blocksize)
  {
  	walk->flags &= ~BLKCIPHER_WALK_PHYS;
  	walk->walk_blocksize = blocksize;
  	walk->cipher_blocksize = crypto_aead_blocksize(tfm);
  	walk->ivsize = crypto_aead_ivsize(tfm);
  	walk->alignmask = crypto_aead_alignmask(tfm);
  	return blkcipher_walk_first(desc, walk);
  }
  EXPORT_SYMBOL_GPL(blkcipher_aead_walk_virt_block);

  static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
  			    unsigned int keylen)

  {
  	struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
  	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
  	int ret;
  	u8 *buffer, *alignbuffer;
  	unsigned long absize;
  
  	absize = keylen + alignmask;
  	buffer = kmalloc(absize, GFP_ATOMIC);
  	if (!buffer)
  		return -ENOMEM;
  
  	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
  	memcpy(alignbuffer, key, keylen);
  	ret = cipher->setkey(tfm, alignbuffer, keylen);

  	memset(alignbuffer, 0, keylen);

  	kfree(buffer);
  	return ret;
  }

  static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)

  {
  	struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;

  	unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);

  
  	if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
  		tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  		return -EINVAL;
  	}

  	if ((unsigned long)key & alignmask)
  		return setkey_unaligned(tfm, key, keylen);

  	return cipher->setkey(tfm, key, keylen);
  }

  static int async_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
  			unsigned int keylen)
  {
  	return setkey(crypto_ablkcipher_tfm(tfm), key, keylen);
  }
  
  static int async_encrypt(struct ablkcipher_request *req)
  {
  	struct crypto_tfm *tfm = req->base.tfm;
  	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
  	struct blkcipher_desc desc = {
  		.tfm = __crypto_blkcipher_cast(tfm),
  		.info = req->info,
  		.flags = req->base.flags,
  	};
  
  
  	return alg->encrypt(&desc, req->dst, req->src, req->nbytes);
  }
  
  static int async_decrypt(struct ablkcipher_request *req)
  {
  	struct crypto_tfm *tfm = req->base.tfm;
  	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
  	struct blkcipher_desc desc = {
  		.tfm = __crypto_blkcipher_cast(tfm),
  		.info = req->info,
  		.flags = req->base.flags,
  	};
  
  	return alg->decrypt(&desc, req->dst, req->src, req->nbytes);
  }

  static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg, u32 type,
  					     u32 mask)

  {
  	struct blkcipher_alg *cipher = &alg->cra_blkcipher;
  	unsigned int len = alg->cra_ctxsize;

  	if ((mask & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_MASK &&
  	    cipher->ivsize) {

  		len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
  		len += cipher->ivsize;
  	}
  
  	return len;
  }

  static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
  {
  	struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;
  	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
  
  	crt->setkey = async_setkey;
  	crt->encrypt = async_encrypt;
  	crt->decrypt = async_decrypt;

  	if (!alg->ivsize) {
  		crt->givencrypt = skcipher_null_givencrypt;
  		crt->givdecrypt = skcipher_null_givdecrypt;
  	}

  	crt->base = __crypto_ablkcipher_cast(tfm);

  	crt->ivsize = alg->ivsize;
  
  	return 0;
  }
  
  static int crypto_init_blkcipher_ops_sync(struct crypto_tfm *tfm)

  {
  	struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
  	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
  	unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
  	unsigned long addr;

  	crt->setkey = setkey;
  	crt->encrypt = alg->encrypt;
  	crt->decrypt = alg->decrypt;
  
  	addr = (unsigned long)crypto_tfm_ctx(tfm);
  	addr = ALIGN(addr, align);
  	addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
  	crt->iv = (void *)addr;
  
  	return 0;
  }

  static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
  {
  	struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
  
  	if (alg->ivsize > PAGE_SIZE / 8)
  		return -EINVAL;

  	if ((mask & CRYPTO_ALG_TYPE_MASK) == CRYPTO_ALG_TYPE_MASK)

  		return crypto_init_blkcipher_ops_sync(tfm);
  	else
  		return crypto_init_blkcipher_ops_async(tfm);
  }

  #ifdef CONFIG_NET

  static int crypto_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
  {
  	struct crypto_report_blkcipher rblkcipher;

  	strncpy(rblkcipher.type, "blkcipher", sizeof(rblkcipher.type));
  	strncpy(rblkcipher.geniv, alg->cra_blkcipher.geniv ?: "<default>",
  		sizeof(rblkcipher.geniv));

  
  	rblkcipher.blocksize = alg->cra_blocksize;
  	rblkcipher.min_keysize = alg->cra_blkcipher.min_keysize;
  	rblkcipher.max_keysize = alg->cra_blkcipher.max_keysize;
  	rblkcipher.ivsize = alg->cra_blkcipher.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_blkcipher_report(struct sk_buff *skb, struct crypto_alg *alg)
  {
  	return -ENOSYS;
  }
  #endif

  static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)

  	__attribute__ ((unused));

  static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
  {
  	seq_printf(m, "type         : blkcipher
  ");
  	seq_printf(m, "blocksize    : %u
  ", alg->cra_blocksize);
  	seq_printf(m, "min keysize  : %u
  ", alg->cra_blkcipher.min_keysize);
  	seq_printf(m, "max keysize  : %u
  ", alg->cra_blkcipher.max_keysize);
  	seq_printf(m, "ivsize       : %u
  ", alg->cra_blkcipher.ivsize);

  	seq_printf(m, "geniv        : %s
  ", alg->cra_blkcipher.geniv ?:
  					     "<default>");

  }
  
  const struct crypto_type crypto_blkcipher_type = {
  	.ctxsize = crypto_blkcipher_ctxsize,
  	.init = crypto_init_blkcipher_ops,
  #ifdef CONFIG_PROC_FS
  	.show = crypto_blkcipher_show,
  #endif

  	.report = crypto_blkcipher_report,

  };
  EXPORT_SYMBOL_GPL(crypto_blkcipher_type);

  static int crypto_grab_nivcipher(struct crypto_skcipher_spawn *spawn,
  				const char *name, u32 type, u32 mask)
  {
  	struct crypto_alg *alg;
  	int err;
  
  	type = crypto_skcipher_type(type);

  	mask = crypto_skcipher_mask(mask)| CRYPTO_ALG_GENIV;

  
  	alg = crypto_alg_mod_lookup(name, type, mask);
  	if (IS_ERR(alg))
  		return PTR_ERR(alg);
  
  	err = crypto_init_spawn(&spawn->base, alg, spawn->base.inst, mask);
  	crypto_mod_put(alg);
  	return err;
  }
  
  struct crypto_instance *skcipher_geniv_alloc(struct crypto_template *tmpl,
  					     struct rtattr **tb, u32 type,
  					     u32 mask)
  {
  	struct {
  		int (*setkey)(struct crypto_ablkcipher *tfm, const u8 *key,
  			      unsigned int keylen);
  		int (*encrypt)(struct ablkcipher_request *req);
  		int (*decrypt)(struct ablkcipher_request *req);
  
  		unsigned int min_keysize;
  		unsigned int max_keysize;
  		unsigned int ivsize;
  
  		const char *geniv;
  	} balg;
  	const char *name;
  	struct crypto_skcipher_spawn *spawn;
  	struct crypto_attr_type *algt;
  	struct crypto_instance *inst;
  	struct crypto_alg *alg;
  	int err;
  
  	algt = crypto_get_attr_type(tb);

  	if (IS_ERR(algt))

  		return ERR_CAST(algt);

  
  	if ((algt->type ^ (CRYPTO_ALG_TYPE_GIVCIPHER | CRYPTO_ALG_GENIV)) &
  	    algt->mask)
  		return ERR_PTR(-EINVAL);
  
  	name = crypto_attr_alg_name(tb[1]);

  	if (IS_ERR(name))

  		return ERR_CAST(name);

  
  	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
  	if (!inst)
  		return ERR_PTR(-ENOMEM);
  
  	spawn = crypto_instance_ctx(inst);
  
  	/* Ignore async algorithms if necessary. */
  	mask |= crypto_requires_sync(algt->type, algt->mask);
  
  	crypto_set_skcipher_spawn(spawn, inst);
  	err = crypto_grab_nivcipher(spawn, name, type, mask);
  	if (err)
  		goto err_free_inst;
  
  	alg = crypto_skcipher_spawn_alg(spawn);
  
  	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
  	    CRYPTO_ALG_TYPE_BLKCIPHER) {
  		balg.ivsize = alg->cra_blkcipher.ivsize;
  		balg.min_keysize = alg->cra_blkcipher.min_keysize;
  		balg.max_keysize = alg->cra_blkcipher.max_keysize;
  
  		balg.setkey = async_setkey;
  		balg.encrypt = async_encrypt;
  		balg.decrypt = async_decrypt;
  
  		balg.geniv = alg->cra_blkcipher.geniv;
  	} else {
  		balg.ivsize = alg->cra_ablkcipher.ivsize;
  		balg.min_keysize = alg->cra_ablkcipher.min_keysize;
  		balg.max_keysize = alg->cra_ablkcipher.max_keysize;
  
  		balg.setkey = alg->cra_ablkcipher.setkey;
  		balg.encrypt = alg->cra_ablkcipher.encrypt;
  		balg.decrypt = alg->cra_ablkcipher.decrypt;
  
  		balg.geniv = alg->cra_ablkcipher.geniv;
  	}
  
  	err = -EINVAL;
  	if (!balg.ivsize)
  		goto err_drop_alg;
  
  	/*
  	 * This is only true if we're constructing an algorithm with its
  	 * default IV generator.  For the default generator we elide the
  	 * template name and double-check the IV generator.
  	 */
  	if (algt->mask & CRYPTO_ALG_GENIV) {
  		if (!balg.geniv)
  			balg.geniv = crypto_default_geniv(alg);
  		err = -EAGAIN;
  		if (strcmp(tmpl->name, balg.geniv))
  			goto err_drop_alg;
  
  		memcpy(inst->alg.cra_name, alg->cra_name, CRYPTO_MAX_ALG_NAME);
  		memcpy(inst->alg.cra_driver_name, alg->cra_driver_name,
  		       CRYPTO_MAX_ALG_NAME);
  	} else {
  		err = -ENAMETOOLONG;
  		if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
  			     "%s(%s)", tmpl->name, alg->cra_name) >=
  		    CRYPTO_MAX_ALG_NAME)
  			goto err_drop_alg;
  		if (snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
  			     "%s(%s)", tmpl->name, alg->cra_driver_name) >=
  		    CRYPTO_MAX_ALG_NAME)
  			goto err_drop_alg;
  	}
  
  	inst->alg.cra_flags = CRYPTO_ALG_TYPE_GIVCIPHER | CRYPTO_ALG_GENIV;
  	inst->alg.cra_flags |= alg->cra_flags & CRYPTO_ALG_ASYNC;
  	inst->alg.cra_priority = alg->cra_priority;
  	inst->alg.cra_blocksize = alg->cra_blocksize;
  	inst->alg.cra_alignmask = alg->cra_alignmask;
  	inst->alg.cra_type = &crypto_givcipher_type;
  
  	inst->alg.cra_ablkcipher.ivsize = balg.ivsize;
  	inst->alg.cra_ablkcipher.min_keysize = balg.min_keysize;
  	inst->alg.cra_ablkcipher.max_keysize = balg.max_keysize;
  	inst->alg.cra_ablkcipher.geniv = balg.geniv;
  
  	inst->alg.cra_ablkcipher.setkey = balg.setkey;
  	inst->alg.cra_ablkcipher.encrypt = balg.encrypt;
  	inst->alg.cra_ablkcipher.decrypt = balg.decrypt;
  
  out:
  	return inst;
  
  err_drop_alg:
  	crypto_drop_skcipher(spawn);
  err_free_inst:
  	kfree(inst);
  	inst = ERR_PTR(err);
  	goto out;
  }
  EXPORT_SYMBOL_GPL(skcipher_geniv_alloc);
  
  void skcipher_geniv_free(struct crypto_instance *inst)
  {
  	crypto_drop_skcipher(crypto_instance_ctx(inst));
  	kfree(inst);
  }
  EXPORT_SYMBOL_GPL(skcipher_geniv_free);
  
  int skcipher_geniv_init(struct crypto_tfm *tfm)
  {
  	struct crypto_instance *inst = (void *)tfm->__crt_alg;
  	struct crypto_ablkcipher *cipher;
  
  	cipher = crypto_spawn_skcipher(crypto_instance_ctx(inst));
  	if (IS_ERR(cipher))
  		return PTR_ERR(cipher);
  
  	tfm->crt_ablkcipher.base = cipher;
  	tfm->crt_ablkcipher.reqsize += crypto_ablkcipher_reqsize(cipher);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(skcipher_geniv_init);
  
  void skcipher_geniv_exit(struct crypto_tfm *tfm)
  {
  	crypto_free_ablkcipher(tfm->crt_ablkcipher.base);
  }
  EXPORT_SYMBOL_GPL(skcipher_geniv_exit);

  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Generic block chaining cipher type");