/*
   * Asynchronous block chaining cipher operations.

   *

   * This is the asynchronous version of blkcipher.c indicating completion
   * via a callback.
   *
   * 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/internal/skcipher.h>

  #include <linux/cpumask.h>

  #include <linux/err.h>

  #include <linux/kernel.h>

  #include <linux/rtnetlink.h>
  #include <linux/sched.h>

  #include <linux/slab.h>

  #include <linux/seq_file.h>

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

  #include <crypto/scatterwalk.h>

  #include "internal.h"

  struct ablkcipher_buffer {
  	struct list_head	entry;
  	struct scatter_walk	dst;
  	unsigned int		len;
  	void			*data;
  };
  
  enum {
  	ABLKCIPHER_WALK_SLOW = 1 << 0,
  };
  
  static inline void ablkcipher_buffer_write(struct ablkcipher_buffer *p)
  {
  	scatterwalk_copychunks(p->data, &p->dst, p->len, 1);
  }
  
  void __ablkcipher_walk_complete(struct ablkcipher_walk *walk)
  {
  	struct ablkcipher_buffer *p, *tmp;
  
  	list_for_each_entry_safe(p, tmp, &walk->buffers, entry) {
  		ablkcipher_buffer_write(p);
  		list_del(&p->entry);
  		kfree(p);
  	}
  }
  EXPORT_SYMBOL_GPL(__ablkcipher_walk_complete);
  
  static inline void ablkcipher_queue_write(struct ablkcipher_walk *walk,
  					  struct ablkcipher_buffer *p)
  {
  	p->dst = walk->out;
  	list_add_tail(&p->entry, &walk->buffers);
  }
  
  /* 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 *ablkcipher_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 ablkcipher_done_slow(struct ablkcipher_walk *walk,
  						unsigned int bsize)
  {
  	unsigned int n = bsize;
  
  	for (;;) {
  		unsigned int len_this_page = scatterwalk_pagelen(&walk->out);
  
  		if (len_this_page > n)
  			len_this_page = n;
  		scatterwalk_advance(&walk->out, n);
  		if (n == len_this_page)
  			break;
  		n -= len_this_page;

  		scatterwalk_start(&walk->out, sg_next(walk->out.sg));

  	}
  
  	return bsize;
  }
  
  static inline unsigned int ablkcipher_done_fast(struct ablkcipher_walk *walk,
  						unsigned int n)
  {
  	scatterwalk_advance(&walk->in, n);
  	scatterwalk_advance(&walk->out, n);
  
  	return n;
  }
  
  static int ablkcipher_walk_next(struct ablkcipher_request *req,
  				struct ablkcipher_walk *walk);
  
  int ablkcipher_walk_done(struct ablkcipher_request *req,
  			 struct ablkcipher_walk *walk, int err)
  {
  	struct crypto_tfm *tfm = req->base.tfm;
  	unsigned int nbytes = 0;
  
  	if (likely(err >= 0)) {
  		unsigned int n = walk->nbytes - err;
  
  		if (likely(!(walk->flags & ABLKCIPHER_WALK_SLOW)))
  			n = ablkcipher_done_fast(walk, n);
  		else if (WARN_ON(err)) {
  			err = -EINVAL;
  			goto err;
  		} else
  			n = ablkcipher_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(req->base.flags);
  		return ablkcipher_walk_next(req, walk);
  	}
  
  	if (walk->iv != req->info)
  		memcpy(req->info, walk->iv, tfm->crt_ablkcipher.ivsize);

  	kfree(walk->iv_buffer);

  
  	return err;
  }
  EXPORT_SYMBOL_GPL(ablkcipher_walk_done);
  
  static inline int ablkcipher_next_slow(struct ablkcipher_request *req,
  				       struct ablkcipher_walk *walk,
  				       unsigned int bsize,
  				       unsigned int alignmask,
  				       void **src_p, void **dst_p)
  {
  	unsigned aligned_bsize = ALIGN(bsize, alignmask + 1);
  	struct ablkcipher_buffer *p;
  	void *src, *dst, *base;
  	unsigned int n;
  
  	n = ALIGN(sizeof(struct ablkcipher_buffer), alignmask + 1);
  	n += (aligned_bsize * 3 - (alignmask + 1) +
  	      (alignmask & ~(crypto_tfm_ctx_alignment() - 1)));
  
  	p = kmalloc(n, GFP_ATOMIC);
  	if (!p)

  		return ablkcipher_walk_done(req, walk, -ENOMEM);

  
  	base = p + 1;
  
  	dst = (u8 *)ALIGN((unsigned long)base, alignmask + 1);
  	src = dst = ablkcipher_get_spot(dst, bsize);
  
  	p->len = bsize;
  	p->data = dst;
  
  	scatterwalk_copychunks(src, &walk->in, bsize, 0);
  
  	ablkcipher_queue_write(walk, p);
  
  	walk->nbytes = bsize;
  	walk->flags |= ABLKCIPHER_WALK_SLOW;
  
  	*src_p = src;
  	*dst_p = dst;
  
  	return 0;
  }
  
  static inline int ablkcipher_copy_iv(struct ablkcipher_walk *walk,
  				     struct crypto_tfm *tfm,
  				     unsigned int alignmask)
  {
  	unsigned bs = walk->blocksize;
  	unsigned int ivsize = tfm->crt_ablkcipher.ivsize;
  	unsigned aligned_bs = ALIGN(bs, alignmask + 1);
  	unsigned int size = aligned_bs * 2 + ivsize + max(aligned_bs, ivsize) -
  			    (alignmask + 1);
  	u8 *iv;
  
  	size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
  	walk->iv_buffer = kmalloc(size, GFP_ATOMIC);
  	if (!walk->iv_buffer)
  		return -ENOMEM;
  
  	iv = (u8 *)ALIGN((unsigned long)walk->iv_buffer, alignmask + 1);
  	iv = ablkcipher_get_spot(iv, bs) + aligned_bs;
  	iv = ablkcipher_get_spot(iv, bs) + aligned_bs;
  	iv = ablkcipher_get_spot(iv, ivsize);
  
  	walk->iv = memcpy(iv, walk->iv, ivsize);
  	return 0;
  }
  
  static inline int ablkcipher_next_fast(struct ablkcipher_request *req,
  				       struct ablkcipher_walk *walk)
  {
  	walk->src.page = scatterwalk_page(&walk->in);
  	walk->src.offset = offset_in_page(walk->in.offset);
  	walk->dst.page = scatterwalk_page(&walk->out);
  	walk->dst.offset = offset_in_page(walk->out.offset);
  
  	return 0;
  }
  
  static int ablkcipher_walk_next(struct ablkcipher_request *req,
  				struct ablkcipher_walk *walk)
  {
  	struct crypto_tfm *tfm = req->base.tfm;
  	unsigned int alignmask, bsize, n;
  	void *src, *dst;
  	int err;
  
  	alignmask = crypto_tfm_alg_alignmask(tfm);
  	n = walk->total;
  	if (unlikely(n < crypto_tfm_alg_blocksize(tfm))) {
  		req->base.flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
  		return ablkcipher_walk_done(req, walk, -EINVAL);
  	}
  
  	walk->flags &= ~ABLKCIPHER_WALK_SLOW;
  	src = dst = NULL;
  
  	bsize = min(walk->blocksize, n);
  	n = scatterwalk_clamp(&walk->in, n);
  	n = scatterwalk_clamp(&walk->out, n);
  
  	if (n < bsize ||
  	    !scatterwalk_aligned(&walk->in, alignmask) ||
  	    !scatterwalk_aligned(&walk->out, alignmask)) {
  		err = ablkcipher_next_slow(req, walk, bsize, alignmask,
  					   &src, &dst);
  		goto set_phys_lowmem;
  	}
  
  	walk->nbytes = n;
  
  	return ablkcipher_next_fast(req, walk);
  
  set_phys_lowmem:
  	if (err >= 0) {
  		walk->src.page = virt_to_page(src);
  		walk->dst.page = virt_to_page(dst);
  		walk->src.offset = ((unsigned long)src & (PAGE_SIZE - 1));
  		walk->dst.offset = ((unsigned long)dst & (PAGE_SIZE - 1));
  	}
  
  	return err;
  }
  
  static int ablkcipher_walk_first(struct ablkcipher_request *req,
  				 struct ablkcipher_walk *walk)
  {
  	struct crypto_tfm *tfm = req->base.tfm;
  	unsigned int alignmask;
  
  	alignmask = crypto_tfm_alg_alignmask(tfm);
  	if (WARN_ON_ONCE(in_irq()))
  		return -EDEADLK;
  
  	walk->nbytes = walk->total;
  	if (unlikely(!walk->total))
  		return 0;
  
  	walk->iv_buffer = NULL;
  	walk->iv = req->info;
  	if (unlikely(((unsigned long)walk->iv & alignmask))) {
  		int err = ablkcipher_copy_iv(walk, tfm, alignmask);

  		if (err)
  			return err;
  	}
  
  	scatterwalk_start(&walk->in, walk->in.sg);
  	scatterwalk_start(&walk->out, walk->out.sg);
  
  	return ablkcipher_walk_next(req, walk);
  }
  
  int ablkcipher_walk_phys(struct ablkcipher_request *req,
  			 struct ablkcipher_walk *walk)
  {
  	walk->blocksize = crypto_tfm_alg_blocksize(req->base.tfm);
  	return ablkcipher_walk_first(req, walk);
  }
  EXPORT_SYMBOL_GPL(ablkcipher_walk_phys);

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

  {
  	struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);
  	unsigned long alignmask = crypto_ablkcipher_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_ablkcipher *tfm, const u8 *key,
  		  unsigned int keylen)
  {
  	struct ablkcipher_alg *cipher = crypto_ablkcipher_alg(tfm);

  	unsigned long alignmask = crypto_ablkcipher_alignmask(tfm);

  
  	if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
  		crypto_ablkcipher_set_flags(tfm, 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 unsigned int crypto_ablkcipher_ctxsize(struct crypto_alg *alg, u32 type,
  					      u32 mask)
  {
  	return alg->cra_ctxsize;
  }

  int skcipher_null_givencrypt(struct skcipher_givcrypt_request *req)
  {
  	return crypto_ablkcipher_encrypt(&req->creq);
  }
  
  int skcipher_null_givdecrypt(struct skcipher_givcrypt_request *req)
  {
  	return crypto_ablkcipher_decrypt(&req->creq);
  }

  static int crypto_init_ablkcipher_ops(struct crypto_tfm *tfm, u32 type,
  				      u32 mask)
  {
  	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
  	struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;
  
  	if (alg->ivsize > PAGE_SIZE / 8)
  		return -EINVAL;
  
  	crt->setkey = setkey;
  	crt->encrypt = alg->encrypt;
  	crt->decrypt = alg->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;
  }

  #ifdef CONFIG_NET

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

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

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

  static void crypto_ablkcipher_show(struct seq_file *m, struct crypto_alg *alg)
  	__attribute__ ((unused));
  static void crypto_ablkcipher_show(struct seq_file *m, struct crypto_alg *alg)
  {
  	struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;
  
  	seq_printf(m, "type         : ablkcipher
  ");

  	seq_printf(m, "async        : %s
  ", alg->cra_flags & CRYPTO_ALG_ASYNC ?
  					     "yes" : "no");

  	seq_printf(m, "blocksize    : %u
  ", alg->cra_blocksize);
  	seq_printf(m, "min keysize  : %u
  ", ablkcipher->min_keysize);
  	seq_printf(m, "max keysize  : %u
  ", ablkcipher->max_keysize);
  	seq_printf(m, "ivsize       : %u
  ", ablkcipher->ivsize);

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

  }
  
  const struct crypto_type crypto_ablkcipher_type = {
  	.ctxsize = crypto_ablkcipher_ctxsize,
  	.init = crypto_init_ablkcipher_ops,
  #ifdef CONFIG_PROC_FS
  	.show = crypto_ablkcipher_show,
  #endif

  	.report = crypto_ablkcipher_report,

  };
  EXPORT_SYMBOL_GPL(crypto_ablkcipher_type);

  static int no_givdecrypt(struct skcipher_givcrypt_request *req)
  {
  	return -ENOSYS;
  }
  
  static int crypto_init_givcipher_ops(struct crypto_tfm *tfm, u32 type,
  				      u32 mask)
  {
  	struct ablkcipher_alg *alg = &tfm->__crt_alg->cra_ablkcipher;
  	struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;
  
  	if (alg->ivsize > PAGE_SIZE / 8)
  		return -EINVAL;

  	crt->setkey = tfm->__crt_alg->cra_flags & CRYPTO_ALG_GENIV ?
  		      alg->setkey : setkey;

  	crt->encrypt = alg->encrypt;
  	crt->decrypt = alg->decrypt;

  	crt->givencrypt = alg->givencrypt ?: no_givdecrypt;

  	crt->givdecrypt = alg->givdecrypt ?: no_givdecrypt;

  	crt->base = __crypto_ablkcipher_cast(tfm);

  	crt->ivsize = alg->ivsize;
  
  	return 0;
  }

  #ifdef CONFIG_NET

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

  	strncpy(rblkcipher.type, "givcipher", sizeof(rblkcipher.type));
  	strncpy(rblkcipher.geniv, alg->cra_ablkcipher.geniv ?: "<built-in>",
  		sizeof(rblkcipher.geniv));

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

  static void crypto_givcipher_show(struct seq_file *m, struct crypto_alg *alg)
  	__attribute__ ((unused));
  static void crypto_givcipher_show(struct seq_file *m, struct crypto_alg *alg)
  {
  	struct ablkcipher_alg *ablkcipher = &alg->cra_ablkcipher;
  
  	seq_printf(m, "type         : givcipher
  ");

  	seq_printf(m, "async        : %s
  ", alg->cra_flags & CRYPTO_ALG_ASYNC ?
  					     "yes" : "no");

  	seq_printf(m, "blocksize    : %u
  ", alg->cra_blocksize);
  	seq_printf(m, "min keysize  : %u
  ", ablkcipher->min_keysize);
  	seq_printf(m, "max keysize  : %u
  ", ablkcipher->max_keysize);
  	seq_printf(m, "ivsize       : %u
  ", ablkcipher->ivsize);

  	seq_printf(m, "geniv        : %s
  ", ablkcipher->geniv ?: "<built-in>");

  }
  
  const struct crypto_type crypto_givcipher_type = {
  	.ctxsize = crypto_ablkcipher_ctxsize,
  	.init = crypto_init_givcipher_ops,
  #ifdef CONFIG_PROC_FS
  	.show = crypto_givcipher_show,
  #endif

  	.report = crypto_givcipher_report,

  };
  EXPORT_SYMBOL_GPL(crypto_givcipher_type);

  const char *crypto_default_geniv(const struct crypto_alg *alg)
  {

  	if (((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
  	     CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
  					 alg->cra_ablkcipher.ivsize) !=
  	    alg->cra_blocksize)
  		return "chainiv";

  	return "eseqiv";

  }

  static int crypto_givcipher_default(struct crypto_alg *alg, u32 type, u32 mask)
  {
  	struct rtattr *tb[3];
  	struct {
  		struct rtattr attr;
  		struct crypto_attr_type data;
  	} ptype;
  	struct {
  		struct rtattr attr;
  		struct crypto_attr_alg data;
  	} palg;
  	struct crypto_template *tmpl;
  	struct crypto_instance *inst;
  	struct crypto_alg *larval;
  	const char *geniv;
  	int err;
  
  	larval = crypto_larval_lookup(alg->cra_driver_name,

  				      (type & ~CRYPTO_ALG_TYPE_MASK) |

  				      CRYPTO_ALG_TYPE_GIVCIPHER,

  				      mask | CRYPTO_ALG_TYPE_MASK);

  	err = PTR_ERR(larval);
  	if (IS_ERR(larval))
  		goto out;
  
  	err = -EAGAIN;
  	if (!crypto_is_larval(larval))
  		goto drop_larval;
  
  	ptype.attr.rta_len = sizeof(ptype);
  	ptype.attr.rta_type = CRYPTOA_TYPE;
  	ptype.data.type = type | CRYPTO_ALG_GENIV;
  	/* GENIV tells the template that we're making a default geniv. */
  	ptype.data.mask = mask | CRYPTO_ALG_GENIV;
  	tb[0] = &ptype.attr;
  
  	palg.attr.rta_len = sizeof(palg);
  	palg.attr.rta_type = CRYPTOA_ALG;
  	/* Must use the exact name to locate ourselves. */
  	memcpy(palg.data.name, alg->cra_driver_name, CRYPTO_MAX_ALG_NAME);
  	tb[1] = &palg.attr;
  
  	tb[2] = NULL;
  
  	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
  	    CRYPTO_ALG_TYPE_BLKCIPHER)
  		geniv = alg->cra_blkcipher.geniv;
  	else
  		geniv = alg->cra_ablkcipher.geniv;
  
  	if (!geniv)
  		geniv = crypto_default_geniv(alg);
  
  	tmpl = crypto_lookup_template(geniv);
  	err = -ENOENT;
  	if (!tmpl)
  		goto kill_larval;

  	if (tmpl->create) {
  		err = tmpl->create(tmpl, tb);
  		if (err)
  			goto put_tmpl;
  		goto ok;
  	}

  	inst = tmpl->alloc(tb);
  	err = PTR_ERR(inst);
  	if (IS_ERR(inst))
  		goto put_tmpl;

  	err = crypto_register_instance(tmpl, inst);
  	if (err) {

  		tmpl->free(inst);
  		goto put_tmpl;
  	}

  ok:

  	/* Redo the lookup to use the instance we just registered. */
  	err = -EAGAIN;
  
  put_tmpl:
  	crypto_tmpl_put(tmpl);
  kill_larval:
  	crypto_larval_kill(larval);
  drop_larval:
  	crypto_mod_put(larval);
  out:
  	crypto_mod_put(alg);
  	return err;
  }

  struct crypto_alg *crypto_lookup_skcipher(const char *name, u32 type, u32 mask)

  {
  	struct crypto_alg *alg;
  
  	alg = crypto_alg_mod_lookup(name, type, mask);
  	if (IS_ERR(alg))
  		return alg;
  
  	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
  	    CRYPTO_ALG_TYPE_GIVCIPHER)
  		return alg;
  
  	if (!((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
  	      CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
  					  alg->cra_ablkcipher.ivsize))
  		return alg;

  	crypto_mod_put(alg);
  	alg = crypto_alg_mod_lookup(name, type | CRYPTO_ALG_TESTED,
  				    mask & ~CRYPTO_ALG_TESTED);
  	if (IS_ERR(alg))
  		return alg;
  
  	if ((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
  	    CRYPTO_ALG_TYPE_GIVCIPHER) {

  		if (~alg->cra_flags & (type ^ ~mask) & CRYPTO_ALG_TESTED) {

  			crypto_mod_put(alg);
  			alg = ERR_PTR(-ENOENT);
  		}
  		return alg;
  	}
  
  	BUG_ON(!((alg->cra_flags & CRYPTO_ALG_TYPE_MASK) ==
  		 CRYPTO_ALG_TYPE_BLKCIPHER ? alg->cra_blkcipher.ivsize :
  					     alg->cra_ablkcipher.ivsize));

  	return ERR_PTR(crypto_givcipher_default(alg, type, mask));
  }

  EXPORT_SYMBOL_GPL(crypto_lookup_skcipher);

  int crypto_grab_skcipher(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);

  	alg = crypto_lookup_skcipher(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;
  }
  EXPORT_SYMBOL_GPL(crypto_grab_skcipher);

  struct crypto_ablkcipher *crypto_alloc_ablkcipher(const char *alg_name,
  						  u32 type, u32 mask)
  {
  	struct crypto_tfm *tfm;
  	int err;
  
  	type = crypto_skcipher_type(type);
  	mask = crypto_skcipher_mask(mask);
  
  	for (;;) {
  		struct crypto_alg *alg;
  
  		alg = crypto_lookup_skcipher(alg_name, type, mask);
  		if (IS_ERR(alg)) {
  			err = PTR_ERR(alg);
  			goto err;
  		}
  
  		tfm = __crypto_alloc_tfm(alg, type, mask);
  		if (!IS_ERR(tfm))
  			return __crypto_ablkcipher_cast(tfm);
  
  		crypto_mod_put(alg);
  		err = PTR_ERR(tfm);
  
  err:
  		if (err != -EAGAIN)
  			break;
  		if (signal_pending(current)) {
  			err = -EINTR;
  			break;
  		}
  	}
  
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL_GPL(crypto_alloc_ablkcipher);