/*
   * Asynchronous Cryptographic Hash operations.
   *
   * This is the asynchronous version of hash.c with notification of
   * completion via a callback.
   *
   * Copyright (c) 2008 Loc Ho <lho@amcc.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/internal/hash.h>
  #include <crypto/scatterwalk.h>

  #include <linux/err.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/seq_file.h>
  
  #include "internal.h"

  static int hash_walk_next(struct crypto_hash_walk *walk)
  {
  	unsigned int alignmask = walk->alignmask;
  	unsigned int offset = walk->offset;
  	unsigned int nbytes = min(walk->entrylen,
  				  ((unsigned int)(PAGE_SIZE)) - offset);
  
  	walk->data = crypto_kmap(walk->pg, 0);
  	walk->data += offset;
  
  	if (offset & alignmask)
  		nbytes = alignmask + 1 - (offset & alignmask);
  
  	walk->entrylen -= nbytes;
  	return nbytes;
  }
  
  static int hash_walk_new_entry(struct crypto_hash_walk *walk)
  {
  	struct scatterlist *sg;
  
  	sg = walk->sg;
  	walk->pg = sg_page(sg);
  	walk->offset = sg->offset;
  	walk->entrylen = sg->length;
  
  	if (walk->entrylen > walk->total)
  		walk->entrylen = walk->total;
  	walk->total -= walk->entrylen;
  
  	return hash_walk_next(walk);
  }
  
  int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
  {
  	unsigned int alignmask = walk->alignmask;
  	unsigned int nbytes = walk->entrylen;
  
  	walk->data -= walk->offset;
  
  	if (nbytes && walk->offset & alignmask && !err) {
  		walk->offset += alignmask - 1;
  		walk->offset = ALIGN(walk->offset, alignmask + 1);
  		walk->data += walk->offset;
  
  		nbytes = min(nbytes,
  			     ((unsigned int)(PAGE_SIZE)) - walk->offset);
  		walk->entrylen -= nbytes;
  
  		return nbytes;
  	}
  
  	crypto_kunmap(walk->data, 0);
  	crypto_yield(walk->flags);
  
  	if (err)
  		return err;

  	if (nbytes) {
  		walk->offset = 0;
  		walk->pg++;

  		return hash_walk_next(walk);

  	}

  
  	if (!walk->total)
  		return 0;
  
  	walk->sg = scatterwalk_sg_next(walk->sg);
  
  	return hash_walk_new_entry(walk);
  }
  EXPORT_SYMBOL_GPL(crypto_hash_walk_done);
  
  int crypto_hash_walk_first(struct ahash_request *req,
  			   struct crypto_hash_walk *walk)
  {
  	walk->total = req->nbytes;
  
  	if (!walk->total)
  		return 0;
  
  	walk->alignmask = crypto_ahash_alignmask(crypto_ahash_reqtfm(req));
  	walk->sg = req->src;
  	walk->flags = req->base.flags;
  
  	return hash_walk_new_entry(walk);
  }
  EXPORT_SYMBOL_GPL(crypto_hash_walk_first);

  int crypto_hash_walk_first_compat(struct hash_desc *hdesc,
  				  struct crypto_hash_walk *walk,
  				  struct scatterlist *sg, unsigned int len)
  {
  	walk->total = len;
  
  	if (!walk->total)
  		return 0;
  
  	walk->alignmask = crypto_hash_alignmask(hdesc->tfm);
  	walk->sg = sg;
  	walk->flags = hdesc->flags;
  
  	return hash_walk_new_entry(walk);
  }

  static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key,
  				unsigned int keylen)
  {
  	struct ahash_alg *ahash = crypto_ahash_alg(tfm);
  	unsigned long alignmask = crypto_ahash_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 = ahash->setkey(tfm, alignbuffer, keylen);
  	memset(alignbuffer, 0, keylen);
  	kfree(buffer);
  	return ret;
  }
  
  static int ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
  			unsigned int keylen)
  {
  	struct ahash_alg *ahash = crypto_ahash_alg(tfm);
  	unsigned long alignmask = crypto_ahash_alignmask(tfm);
  
  	if ((unsigned long)key & alignmask)
  		return ahash_setkey_unaligned(tfm, key, keylen);
  
  	return ahash->setkey(tfm, key, keylen);
  }

  static int ahash_nosetkey(struct crypto_ahash *tfm, const u8 *key,
  			  unsigned int keylen)
  {
  	return -ENOSYS;
  }

  int crypto_ahash_import(struct ahash_request *req, const u8 *in)
  {
  	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
  	struct ahash_alg *alg = crypto_ahash_alg(tfm);
  
  	memcpy(ahash_request_ctx(req), in, crypto_ahash_reqsize(tfm));
  
  	if (alg->reinit)
  		alg->reinit(req);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(crypto_ahash_import);

  static unsigned int crypto_ahash_ctxsize(struct crypto_alg *alg, u32 type,
  					u32 mask)
  {
  	return alg->cra_ctxsize;
  }
  
  static int crypto_init_ahash_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
  {
  	struct ahash_alg *alg = &tfm->__crt_alg->cra_ahash;
  	struct ahash_tfm *crt   = &tfm->crt_ahash;

  	if (alg->digestsize > PAGE_SIZE / 8)

  		return -EINVAL;
  
  	crt->init = alg->init;
  	crt->update = alg->update;
  	crt->final  = alg->final;
  	crt->digest = alg->digest;

  	crt->setkey = alg->setkey ? ahash_setkey : ahash_nosetkey;

  	crt->digestsize = alg->digestsize;
  
  	return 0;
  }
  
  static void crypto_ahash_show(struct seq_file *m, struct crypto_alg *alg)
  	__attribute__ ((unused));
  static void crypto_ahash_show(struct seq_file *m, struct crypto_alg *alg)
  {
  	seq_printf(m, "type         : ahash
  ");
  	seq_printf(m, "async        : %s
  ", alg->cra_flags & CRYPTO_ALG_ASYNC ?
  					     "yes" : "no");
  	seq_printf(m, "blocksize    : %u
  ", alg->cra_blocksize);

  	seq_printf(m, "digestsize   : %u
  ", alg->cra_ahash.digestsize);

  }
  
  const struct crypto_type crypto_ahash_type = {
  	.ctxsize = crypto_ahash_ctxsize,
  	.init = crypto_init_ahash_ops,
  #ifdef CONFIG_PROC_FS
  	.show = crypto_ahash_show,
  #endif
  };
  EXPORT_SYMBOL_GPL(crypto_ahash_type);
  
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Asynchronous cryptographic hash type");