/*
   * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
   * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>

   * Copyright (C) 2006-2009 Red Hat, Inc. All rights reserved.

   *
   * This file is released under the GPL.
   */

  #include <linux/completion.h>

  #include <linux/err.h>

  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/bio.h>
  #include <linux/blkdev.h>
  #include <linux/mempool.h>
  #include <linux/slab.h>
  #include <linux/crypto.h>
  #include <linux/workqueue.h>

  #include <linux/backing-dev.h>

  #include <asm/atomic.h>

  #include <linux/scatterlist.h>

  #include <asm/page.h>

  #include <asm/unaligned.h>

  #include <linux/device-mapper.h>

  #define DM_MSG_PREFIX "crypt"

  #define MESG_STR(x) x, sizeof(x)

  
  /*

   * context holding the current state of a multi-part conversion
   */
  struct convert_context {

  	struct completion restart;

  	struct bio *bio_in;
  	struct bio *bio_out;
  	unsigned int offset_in;
  	unsigned int offset_out;
  	unsigned int idx_in;
  	unsigned int idx_out;
  	sector_t sector;

  	atomic_t pending;

  };

  /*
   * per bio private data
   */
  struct dm_crypt_io {
  	struct dm_target *target;
  	struct bio *base_bio;
  	struct work_struct work;
  
  	struct convert_context ctx;
  
  	atomic_t pending;
  	int error;

  	sector_t sector;

  	struct dm_crypt_io *base_io;

  };

  struct dm_crypt_request {

  	struct convert_context *ctx;

  	struct scatterlist sg_in;
  	struct scatterlist sg_out;
  };

  struct crypt_config;
  
  struct crypt_iv_operations {
  	int (*ctr)(struct crypt_config *cc, struct dm_target *ti,

  		   const char *opts);

  	void (*dtr)(struct crypt_config *cc);

  	int (*init)(struct crypt_config *cc);

  	int (*wipe)(struct crypt_config *cc);

  	int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
  };

  struct iv_essiv_private {
  	struct crypto_cipher *tfm;

  	struct crypto_hash *hash_tfm;
  	u8 *salt;

  };
  
  struct iv_benbi_private {
  	int shift;
  };

  /*
   * Crypt: maps a linear range of a block device
   * and encrypts / decrypts at the same time.
   */

  enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };

  struct crypt_config {
  	struct dm_dev *dev;
  	sector_t start;
  
  	/*

  	 * pool for per bio private data, crypto requests and
  	 * encryption requeusts/buffer pages

  	 */
  	mempool_t *io_pool;

  	mempool_t *req_pool;

  	mempool_t *page_pool;

  	struct bio_set *bs;

  	struct workqueue_struct *io_queue;
  	struct workqueue_struct *crypt_queue;

  	char *cipher;
  	char *cipher_mode;

  	struct crypt_iv_operations *iv_gen_ops;

  	union {

  		struct iv_essiv_private essiv;
  		struct iv_benbi_private benbi;

  	} iv_gen_private;

  	sector_t iv_offset;
  	unsigned int iv_size;

  	/*
  	 * Layout of each crypto request:
  	 *
  	 *   struct ablkcipher_request
  	 *      context
  	 *      padding
  	 *   struct dm_crypt_request
  	 *      padding
  	 *   IV
  	 *
  	 * The padding is added so that dm_crypt_request and the IV are
  	 * correctly aligned.
  	 */
  	unsigned int dmreq_start;
  	struct ablkcipher_request *req;

  	struct crypto_ablkcipher *tfm;

  	unsigned long flags;

  	unsigned int key_size;
  	u8 key[0];
  };

  #define MIN_IOS        16

  #define MIN_POOL_PAGES 32
  #define MIN_BIO_PAGES  8

  static struct kmem_cache *_crypt_io_pool;

  static void clone_init(struct dm_crypt_io *, struct bio *);

  static void kcryptd_queue_crypt(struct dm_crypt_io *io);

  /*

   * Different IV generation algorithms:
   *

   * plain: the initial vector is the 32-bit little-endian version of the sector

   *        number, padded with zeros if necessary.

   *

   * plain64: the initial vector is the 64-bit little-endian version of the sector
   *        number, padded with zeros if necessary.
   *

   * essiv: "encrypted sector|salt initial vector", the sector number is
   *        encrypted with the bulk cipher using a salt as key. The salt
   *        should be derived from the bulk cipher's key via hashing.

   *

   * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
   *        (needed for LRW-32-AES and possible other narrow block modes)
   *

   * null: the initial vector is always zero.  Provides compatibility with
   *       obsolete loop_fish2 devices.  Do not use for new devices.
   *

   * plumb: unimplemented, see:
   * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
   */
  
  static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
  {
  	memset(iv, 0, cc->iv_size);
  	*(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
  
  	return 0;
  }

  static int crypt_iv_plain64_gen(struct crypt_config *cc, u8 *iv,
  				sector_t sector)
  {
  	memset(iv, 0, cc->iv_size);
  	*(u64 *)iv = cpu_to_le64(sector);
  
  	return 0;
  }

  /* Initialise ESSIV - compute salt but no local memory allocations */
  static int crypt_iv_essiv_init(struct crypt_config *cc)
  {
  	struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
  	struct hash_desc desc;
  	struct scatterlist sg;
  	int err;
  
  	sg_init_one(&sg, cc->key, cc->key_size);
  	desc.tfm = essiv->hash_tfm;
  	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
  
  	err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt);
  	if (err)
  		return err;
  
  	return crypto_cipher_setkey(essiv->tfm, essiv->salt,
  				    crypto_hash_digestsize(essiv->hash_tfm));
  }

  /* Wipe salt and reset key derived from volume key */
  static int crypt_iv_essiv_wipe(struct crypt_config *cc)
  {
  	struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
  	unsigned salt_size = crypto_hash_digestsize(essiv->hash_tfm);
  
  	memset(essiv->salt, 0, salt_size);
  
  	return crypto_cipher_setkey(essiv->tfm, essiv->salt, salt_size);
  }

  static void crypt_iv_essiv_dtr(struct crypt_config *cc)
  {
  	struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
  
  	crypto_free_cipher(essiv->tfm);
  	essiv->tfm = NULL;

  
  	crypto_free_hash(essiv->hash_tfm);
  	essiv->hash_tfm = NULL;
  
  	kzfree(essiv->salt);
  	essiv->salt = NULL;

  }

  static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,

  			      const char *opts)

  {

  	struct crypto_cipher *essiv_tfm = NULL;
  	struct crypto_hash *hash_tfm = NULL;

  	u8 *salt = NULL;

  	int err;

  	if (!opts) {

  		ti->error = "Digest algorithm missing for ESSIV mode";

  		return -EINVAL;
  	}

  	/* Allocate hash algorithm */

  	hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
  	if (IS_ERR(hash_tfm)) {

  		ti->error = "Error initializing ESSIV hash";

  		err = PTR_ERR(hash_tfm);
  		goto bad;

  	}

  	salt = kzalloc(crypto_hash_digestsize(hash_tfm), GFP_KERNEL);

  	if (!salt) {

  		ti->error = "Error kmallocing salt storage in ESSIV";

  		err = -ENOMEM;
  		goto bad;

  	}

  	/* Allocate essiv_tfm */

  	essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
  	if (IS_ERR(essiv_tfm)) {

  		ti->error = "Error allocating crypto tfm for ESSIV";

  		err = PTR_ERR(essiv_tfm);
  		goto bad;

  	}

  	if (crypto_cipher_blocksize(essiv_tfm) !=

  	    crypto_ablkcipher_ivsize(cc->tfm)) {

  		ti->error = "Block size of ESSIV cipher does "

  			    "not match IV size of block cipher";

  		err = -EINVAL;
  		goto bad;

  	}

  	cc->iv_gen_private.essiv.salt = salt;

  	cc->iv_gen_private.essiv.tfm = essiv_tfm;

  	cc->iv_gen_private.essiv.hash_tfm = hash_tfm;

  	return 0;

  
  bad:
  	if (essiv_tfm && !IS_ERR(essiv_tfm))
  		crypto_free_cipher(essiv_tfm);
  	if (hash_tfm && !IS_ERR(hash_tfm))
  		crypto_free_hash(hash_tfm);

  	kfree(salt);

  	return err;

  }

  static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
  {

  	memset(iv, 0, cc->iv_size);
  	*(u64 *)iv = cpu_to_le64(sector);

  	crypto_cipher_encrypt_one(cc->iv_gen_private.essiv.tfm, iv, iv);

  	return 0;
  }

  static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
  			      const char *opts)
  {

  	unsigned bs = crypto_ablkcipher_blocksize(cc->tfm);

  	int log = ilog2(bs);

  
  	/* we need to calculate how far we must shift the sector count
  	 * to get the cipher block count, we use this shift in _gen */
  
  	if (1 << log != bs) {
  		ti->error = "cypher blocksize is not a power of 2";
  		return -EINVAL;
  	}
  
  	if (log > 9) {
  		ti->error = "cypher blocksize is > 512";
  		return -EINVAL;
  	}

  	cc->iv_gen_private.benbi.shift = 9 - log;

  
  	return 0;
  }
  
  static void crypt_iv_benbi_dtr(struct crypt_config *cc)
  {

  }
  
  static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
  {

  	__be64 val;

  	memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */

  	val = cpu_to_be64(((u64)sector << cc->iv_gen_private.benbi.shift) + 1);

  	put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));

  	return 0;
  }

  static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
  {
  	memset(iv, 0, cc->iv_size);
  
  	return 0;
  }

  static struct crypt_iv_operations crypt_iv_plain_ops = {
  	.generator = crypt_iv_plain_gen
  };

  static struct crypt_iv_operations crypt_iv_plain64_ops = {
  	.generator = crypt_iv_plain64_gen
  };

  static struct crypt_iv_operations crypt_iv_essiv_ops = {
  	.ctr       = crypt_iv_essiv_ctr,
  	.dtr       = crypt_iv_essiv_dtr,

  	.init      = crypt_iv_essiv_init,

  	.wipe      = crypt_iv_essiv_wipe,

  	.generator = crypt_iv_essiv_gen
  };

  static struct crypt_iv_operations crypt_iv_benbi_ops = {
  	.ctr	   = crypt_iv_benbi_ctr,
  	.dtr	   = crypt_iv_benbi_dtr,
  	.generator = crypt_iv_benbi_gen
  };

  static struct crypt_iv_operations crypt_iv_null_ops = {
  	.generator = crypt_iv_null_gen
  };

  static void crypt_convert_init(struct crypt_config *cc,
  			       struct convert_context *ctx,
  			       struct bio *bio_out, struct bio *bio_in,

  			       sector_t sector)

  {
  	ctx->bio_in = bio_in;
  	ctx->bio_out = bio_out;
  	ctx->offset_in = 0;
  	ctx->offset_out = 0;
  	ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
  	ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
  	ctx->sector = sector + cc->iv_offset;

  	init_completion(&ctx->restart);

  }

  static struct dm_crypt_request *dmreq_of_req(struct crypt_config *cc,
  					     struct ablkcipher_request *req)
  {
  	return (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
  }
  
  static struct ablkcipher_request *req_of_dmreq(struct crypt_config *cc,
  					       struct dm_crypt_request *dmreq)
  {
  	return (struct ablkcipher_request *)((char *)dmreq - cc->dmreq_start);
  }

  static int crypt_convert_block(struct crypt_config *cc,

  			       struct convert_context *ctx,
  			       struct ablkcipher_request *req)

  {
  	struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
  	struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);

  	struct dm_crypt_request *dmreq;
  	u8 *iv;
  	int r = 0;

  	dmreq = dmreq_of_req(cc, req);

  	iv = (u8 *)ALIGN((unsigned long)(dmreq + 1),
  			 crypto_ablkcipher_alignmask(cc->tfm) + 1);

  	dmreq->ctx = ctx;

  	sg_init_table(&dmreq->sg_in, 1);
  	sg_set_page(&dmreq->sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,

  		    bv_in->bv_offset + ctx->offset_in);

  	sg_init_table(&dmreq->sg_out, 1);
  	sg_set_page(&dmreq->sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT,

  		    bv_out->bv_offset + ctx->offset_out);
  
  	ctx->offset_in += 1 << SECTOR_SHIFT;
  	if (ctx->offset_in >= bv_in->bv_len) {
  		ctx->offset_in = 0;
  		ctx->idx_in++;
  	}
  
  	ctx->offset_out += 1 << SECTOR_SHIFT;
  	if (ctx->offset_out >= bv_out->bv_len) {
  		ctx->offset_out = 0;
  		ctx->idx_out++;
  	}

  	if (cc->iv_gen_ops) {
  		r = cc->iv_gen_ops->generator(cc, iv, ctx->sector);
  		if (r < 0)
  			return r;
  	}
  
  	ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out,
  				     1 << SECTOR_SHIFT, iv);
  
  	if (bio_data_dir(ctx->bio_in) == WRITE)
  		r = crypto_ablkcipher_encrypt(req);
  	else
  		r = crypto_ablkcipher_decrypt(req);
  
  	return r;

  }

  static void kcryptd_async_done(struct crypto_async_request *async_req,
  			       int error);

  static void crypt_alloc_req(struct crypt_config *cc,
  			    struct convert_context *ctx)
  {
  	if (!cc->req)
  		cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);

  	ablkcipher_request_set_tfm(cc->req, cc->tfm);
  	ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG |

  					CRYPTO_TFM_REQ_MAY_SLEEP,
  					kcryptd_async_done,
  					dmreq_of_req(cc, cc->req));

  }

  /*
   * Encrypt / decrypt data from one bio to another one (can be the same one)
   */
  static int crypt_convert(struct crypt_config *cc,

  			 struct convert_context *ctx)

  {

  	int r;

  	atomic_set(&ctx->pending, 1);

  	while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
  	      ctx->idx_out < ctx->bio_out->bi_vcnt) {

  		crypt_alloc_req(cc, ctx);

  		atomic_inc(&ctx->pending);

  		r = crypt_convert_block(cc, ctx, cc->req);
  
  		switch (r) {

  		/* async */

  		case -EBUSY:
  			wait_for_completion(&ctx->restart);
  			INIT_COMPLETION(ctx->restart);
  			/* fall through*/
  		case -EINPROGRESS:

  			cc->req = NULL;

  			ctx->sector++;
  			continue;
  
  		/* sync */

  		case 0:

  			atomic_dec(&ctx->pending);

  			ctx->sector++;

  			cond_resched();

  			continue;

  		/* error */
  		default:
  			atomic_dec(&ctx->pending);
  			return r;
  		}

  	}

  	return 0;

  }

  static void dm_crypt_bio_destructor(struct bio *bio)
  {

  	struct dm_crypt_io *io = bio->bi_private;

  	struct crypt_config *cc = io->target->private;
  
  	bio_free(bio, cc->bs);

  }

  /*
   * Generate a new unfragmented bio with the given size
   * This should never violate the device limitations

   * May return a smaller bio when running out of pages, indicated by
   * *out_of_pages set to 1.

   */

  static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size,
  				      unsigned *out_of_pages)

  {

  	struct crypt_config *cc = io->target->private;

  	struct bio *clone;

  	unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;

  	gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;

  	unsigned i, len;
  	struct page *page;

  	clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);

  	if (!clone)

  		return NULL;

  	clone_init(io, clone);

  	*out_of_pages = 0;

  	for (i = 0; i < nr_iovecs; i++) {

  		page = mempool_alloc(cc->page_pool, gfp_mask);

  		if (!page) {
  			*out_of_pages = 1;

  			break;

  		}

  
  		/*
  		 * if additional pages cannot be allocated without waiting,
  		 * return a partially allocated bio, the caller will then try
  		 * to allocate additional bios while submitting this partial bio
  		 */

  		if (i == (MIN_BIO_PAGES - 1))

  			gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;

  		len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
  
  		if (!bio_add_page(clone, page, len, 0)) {
  			mempool_free(page, cc->page_pool);
  			break;
  		}

  		size -= len;

  	}

  	if (!clone->bi_size) {
  		bio_put(clone);

  		return NULL;
  	}

  	return clone;

  }

  static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)

  {

  	unsigned int i;

  	struct bio_vec *bv;

  	for (i = 0; i < clone->bi_vcnt; i++) {

  		bv = bio_iovec_idx(clone, i);

  		BUG_ON(!bv->bv_page);
  		mempool_free(bv->bv_page, cc->page_pool);
  		bv->bv_page = NULL;
  	}
  }

  static struct dm_crypt_io *crypt_io_alloc(struct dm_target *ti,
  					  struct bio *bio, sector_t sector)
  {
  	struct crypt_config *cc = ti->private;
  	struct dm_crypt_io *io;
  
  	io = mempool_alloc(cc->io_pool, GFP_NOIO);
  	io->target = ti;
  	io->base_bio = bio;
  	io->sector = sector;
  	io->error = 0;

  	io->base_io = NULL;

  	atomic_set(&io->pending, 0);
  
  	return io;
  }

  static void crypt_inc_pending(struct dm_crypt_io *io)
  {
  	atomic_inc(&io->pending);
  }

  /*
   * One of the bios was finished. Check for completion of
   * the whole request and correctly clean up the buffer.

   * If base_io is set, wait for the last fragment to complete.

   */

  static void crypt_dec_pending(struct dm_crypt_io *io)

  {

  	struct crypt_config *cc = io->target->private;

  	struct bio *base_bio = io->base_bio;
  	struct dm_crypt_io *base_io = io->base_io;
  	int error = io->error;

  
  	if (!atomic_dec_and_test(&io->pending))
  		return;

  	mempool_free(io, cc->io_pool);
  
  	if (likely(!base_io))
  		bio_endio(base_bio, error);

  	else {

  		if (error && !base_io->error)
  			base_io->error = error;
  		crypt_dec_pending(base_io);

  	}

  }
  
  /*

   * kcryptd/kcryptd_io:

   *
   * Needed because it would be very unwise to do decryption in an

   * interrupt context.

   *
   * kcryptd performs the actual encryption or decryption.
   *
   * kcryptd_io performs the IO submission.
   *
   * They must be separated as otherwise the final stages could be
   * starved by new requests which can block in the first stages due
   * to memory allocation.

   */

  static void crypt_endio(struct bio *clone, int error)

  {

  	struct dm_crypt_io *io = clone->bi_private;

  	struct crypt_config *cc = io->target->private;

  	unsigned rw = bio_data_dir(clone);

  	if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
  		error = -EIO;

  	/*

  	 * free the processed pages

  	 */

  	if (rw == WRITE)

  		crypt_free_buffer_pages(cc, clone);

  
  	bio_put(clone);

  	if (rw == READ && !error) {
  		kcryptd_queue_crypt(io);
  		return;
  	}

  
  	if (unlikely(error))
  		io->error = error;
  
  	crypt_dec_pending(io);

  }

  static void clone_init(struct dm_crypt_io *io, struct bio *clone)

  {
  	struct crypt_config *cc = io->target->private;
  
  	clone->bi_private = io;
  	clone->bi_end_io  = crypt_endio;
  	clone->bi_bdev    = cc->dev->bdev;
  	clone->bi_rw      = io->base_bio->bi_rw;

  	clone->bi_destructor = dm_crypt_bio_destructor;

  }

  static void kcryptd_io_read(struct dm_crypt_io *io)

  {
  	struct crypt_config *cc = io->target->private;
  	struct bio *base_bio = io->base_bio;
  	struct bio *clone;

  	crypt_inc_pending(io);

  
  	/*
  	 * The block layer might modify the bvec array, so always
  	 * copy the required bvecs because we need the original
  	 * one in order to decrypt the whole bio data *afterwards*.
  	 */

  	clone = bio_alloc_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);

  	if (unlikely(!clone)) {

  		io->error = -ENOMEM;
  		crypt_dec_pending(io);

  		return;

  	}

  
  	clone_init(io, clone);
  	clone->bi_idx = 0;
  	clone->bi_vcnt = bio_segments(base_bio);
  	clone->bi_size = base_bio->bi_size;

  	clone->bi_sector = cc->start + io->sector;

  	memcpy(clone->bi_io_vec, bio_iovec(base_bio),
  	       sizeof(struct bio_vec) * clone->bi_vcnt);

  	generic_make_request(clone);

  }

  static void kcryptd_io_write(struct dm_crypt_io *io)
  {

  	struct bio *clone = io->ctx.bio_out;

  	generic_make_request(clone);

  }

  static void kcryptd_io(struct work_struct *work)
  {
  	struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);
  
  	if (bio_data_dir(io->base_bio) == READ)
  		kcryptd_io_read(io);
  	else
  		kcryptd_io_write(io);
  }
  
  static void kcryptd_queue_io(struct dm_crypt_io *io)
  {
  	struct crypt_config *cc = io->target->private;
  
  	INIT_WORK(&io->work, kcryptd_io);
  	queue_work(cc->io_queue, &io->work);
  }

  static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io,
  					  int error, int async)

  {

  	struct bio *clone = io->ctx.bio_out;
  	struct crypt_config *cc = io->target->private;
  
  	if (unlikely(error < 0)) {
  		crypt_free_buffer_pages(cc, clone);
  		bio_put(clone);
  		io->error = -EIO;

  		crypt_dec_pending(io);

  		return;
  	}
  
  	/* crypt_convert should have filled the clone bio */
  	BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
  
  	clone->bi_sector = cc->start + io->sector;

  	if (async)
  		kcryptd_queue_io(io);

  	else

  		generic_make_request(clone);

  }

  static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)

  {
  	struct crypt_config *cc = io->target->private;

  	struct bio *clone;

  	struct dm_crypt_io *new_io;

  	int crypt_finished;

  	unsigned out_of_pages = 0;

  	unsigned remaining = io->base_bio->bi_size;

  	sector_t sector = io->sector;

  	int r;

  	/*

  	 * Prevent io from disappearing until this function completes.
  	 */
  	crypt_inc_pending(io);

  	crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);

  
  	/*

  	 * The allocated buffers can be smaller than the whole bio,
  	 * so repeat the whole process until all the data can be handled.
  	 */
  	while (remaining) {

  		clone = crypt_alloc_buffer(io, remaining, &out_of_pages);

  		if (unlikely(!clone)) {

  			io->error = -ENOMEM;

  			break;

  		}

  		io->ctx.bio_out = clone;
  		io->ctx.idx_out = 0;

  		remaining -= clone->bi_size;

  		sector += bio_sectors(clone);

  		crypt_inc_pending(io);

  		r = crypt_convert(cc, &io->ctx);

  		crypt_finished = atomic_dec_and_test(&io->ctx.pending);

  		/* Encryption was already finished, submit io now */
  		if (crypt_finished) {

  			kcryptd_crypt_write_io_submit(io, r, 0);

  
  			/*
  			 * If there was an error, do not try next fragments.
  			 * For async, error is processed in async handler.
  			 */

  			if (unlikely(r < 0))

  				break;

  
  			io->sector = sector;

  		}

  		/*
  		 * Out of memory -> run queues
  		 * But don't wait if split was due to the io size restriction
  		 */
  		if (unlikely(out_of_pages))

  			congestion_wait(BLK_RW_ASYNC, HZ/100);

  		/*
  		 * With async crypto it is unsafe to share the crypto context
  		 * between fragments, so switch to a new dm_crypt_io structure.
  		 */
  		if (unlikely(!crypt_finished && remaining)) {
  			new_io = crypt_io_alloc(io->target, io->base_bio,
  						sector);
  			crypt_inc_pending(new_io);
  			crypt_convert_init(cc, &new_io->ctx, NULL,
  					   io->base_bio, sector);
  			new_io->ctx.idx_in = io->ctx.idx_in;
  			new_io->ctx.offset_in = io->ctx.offset_in;
  
  			/*
  			 * Fragments after the first use the base_io
  			 * pending count.
  			 */
  			if (!io->base_io)
  				new_io->base_io = io;
  			else {
  				new_io->base_io = io->base_io;
  				crypt_inc_pending(io->base_io);
  				crypt_dec_pending(io);
  			}
  
  			io = new_io;
  		}

  	}

  
  	crypt_dec_pending(io);

  }

  static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error)

  {
  	if (unlikely(error < 0))
  		io->error = -EIO;
  
  	crypt_dec_pending(io);
  }

  static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)

  {
  	struct crypt_config *cc = io->target->private;

  	int r = 0;

  	crypt_inc_pending(io);

  	crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,

  			   io->sector);

  	r = crypt_convert(cc, &io->ctx);

  	if (atomic_dec_and_test(&io->ctx.pending))

  		kcryptd_crypt_read_done(io, r);
  
  	crypt_dec_pending(io);

  }

  static void kcryptd_async_done(struct crypto_async_request *async_req,
  			       int error)
  {

  	struct dm_crypt_request *dmreq = async_req->data;
  	struct convert_context *ctx = dmreq->ctx;

  	struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
  	struct crypt_config *cc = io->target->private;
  
  	if (error == -EINPROGRESS) {
  		complete(&ctx->restart);
  		return;
  	}

  	mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);

  
  	if (!atomic_dec_and_test(&ctx->pending))
  		return;
  
  	if (bio_data_dir(io->base_bio) == READ)
  		kcryptd_crypt_read_done(io, error);
  	else
  		kcryptd_crypt_write_io_submit(io, error, 1);
  }

  static void kcryptd_crypt(struct work_struct *work)

  {

  	struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);

  	if (bio_data_dir(io->base_bio) == READ)

  		kcryptd_crypt_read_convert(io);

  	else

  		kcryptd_crypt_write_convert(io);

  }

  static void kcryptd_queue_crypt(struct dm_crypt_io *io)

  {

  	struct crypt_config *cc = io->target->private;

  	INIT_WORK(&io->work, kcryptd_crypt);
  	queue_work(cc->crypt_queue, &io->work);

  }
  
  /*
   * Decode key from its hex representation
   */
  static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
  {
  	char buffer[3];
  	char *endp;
  	unsigned int i;
  
  	buffer[2] = '\0';

  	for (i = 0; i < size; i++) {

  		buffer[0] = *hex++;
  		buffer[1] = *hex++;
  
  		key[i] = (u8)simple_strtoul(buffer, &endp, 16);
  
  		if (endp != &buffer[2])
  			return -EINVAL;
  	}
  
  	if (*hex != '\0')
  		return -EINVAL;
  
  	return 0;
  }
  
  /*
   * Encode key into its hex representation
   */
  static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
  {
  	unsigned int i;

  	for (i = 0; i < size; i++) {

  		sprintf(hex, "%02x", *key);
  		hex += 2;
  		key++;
  	}
  }

  static int crypt_set_key(struct crypt_config *cc, char *key)
  {
  	unsigned key_size = strlen(key) >> 1;
  
  	if (cc->key_size && cc->key_size != key_size)
  		return -EINVAL;
  
  	cc->key_size = key_size; /* initial settings */
  
  	if ((!key_size && strcmp(key, "-")) ||

  	   (key_size && crypt_decode_key(cc->key, key, key_size) < 0))

  		return -EINVAL;
  
  	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);

  	return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);

  }
  
  static int crypt_wipe_key(struct crypt_config *cc)
  {
  	clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
  	memset(&cc->key, 0, cc->key_size * sizeof(u8));

  	return crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);

  }

  static void crypt_dtr(struct dm_target *ti)
  {
  	struct crypt_config *cc = ti->private;
  
  	ti->private = NULL;
  
  	if (!cc)
  		return;
  
  	if (cc->io_queue)
  		destroy_workqueue(cc->io_queue);
  	if (cc->crypt_queue)
  		destroy_workqueue(cc->crypt_queue);
  
  	if (cc->bs)
  		bioset_free(cc->bs);
  
  	if (cc->page_pool)
  		mempool_destroy(cc->page_pool);
  	if (cc->req_pool)
  		mempool_destroy(cc->req_pool);
  	if (cc->io_pool)
  		mempool_destroy(cc->io_pool);
  
  	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
  		cc->iv_gen_ops->dtr(cc);
  
  	if (cc->tfm && !IS_ERR(cc->tfm))
  		crypto_free_ablkcipher(cc->tfm);
  
  	if (cc->dev)
  		dm_put_device(ti, cc->dev);

  	kzfree(cc->cipher);
  	kzfree(cc->cipher_mode);

  
  	/* Must zero key material before freeing */
  	kzfree(cc);
  }

  static int crypt_ctr_cipher(struct dm_target *ti,
  			    char *cipher_in, char *key)

  {

  	struct crypt_config *cc = ti->private;
  	char *tmp, *cipher, *chainmode, *ivmode, *ivopts;
  	char *cipher_api = NULL;

  	int ret = -EINVAL;

  	/* Convert to crypto api definition? */
  	if (strchr(cipher_in, '(')) {
  		ti->error = "Bad cipher specification";

  		return -EINVAL;
  	}

  	/*
  	 * Legacy dm-crypt cipher specification
  	 * cipher-mode-iv:ivopts
  	 */
  	tmp = cipher_in;

  	cipher = strsep(&tmp, "-");

  
  	cc->cipher = kstrdup(cipher, GFP_KERNEL);
  	if (!cc->cipher)
  		goto bad_mem;
  
  	if (tmp) {
  		cc->cipher_mode = kstrdup(tmp, GFP_KERNEL);
  		if (!cc->cipher_mode)
  			goto bad_mem;
  	}

  	chainmode = strsep(&tmp, "-");
  	ivopts = strsep(&tmp, "-");
  	ivmode = strsep(&ivopts, ":");
  
  	if (tmp)

  		DMWARN("Ignoring unexpected additional cipher options");

  	/* Compatibility mode for old dm-crypt mappings */
  	if (!chainmode || (!strcmp(chainmode, "plain") && !ivmode)) {
  		kfree(cc->cipher_mode);
  		cc->cipher_mode = kstrdup("cbc-plain", GFP_KERNEL);

  		chainmode = "cbc";
  		ivmode = "plain";
  	}

  	if (strcmp(chainmode, "ecb") && !ivmode) {

  		ti->error = "IV mechanism required";
  		return -EINVAL;

  	}

  	cipher_api = kmalloc(CRYPTO_MAX_ALG_NAME, GFP_KERNEL);
  	if (!cipher_api)
  		goto bad_mem;
  
  	ret = snprintf(cipher_api, CRYPTO_MAX_ALG_NAME,
  		       "%s(%s)", chainmode, cipher);
  	if (ret < 0) {
  		kfree(cipher_api);
  		goto bad_mem;

  	}

  	/* Allocate cipher */
  	cc->tfm = crypto_alloc_ablkcipher(cipher_api, 0, 0);

  	if (IS_ERR(cc->tfm)) {

  		ret = PTR_ERR(cc->tfm);

  		ti->error = "Error allocating crypto tfm";

  		goto bad;

  	}

  	/* Initialize and set key */
  	ret = crypt_set_key(cc, key);

  	if (ret < 0) {

  		ti->error = "Error decoding and setting key";

  		goto bad;

  	}

  	/* Initialize IV */
  	cc->iv_size = crypto_ablkcipher_ivsize(cc->tfm);
  	if (cc->iv_size)
  		/* at least a 64 bit sector number should fit in our buffer */
  		cc->iv_size = max(cc->iv_size,
  				  (unsigned int)(sizeof(u64) / sizeof(u8)));
  	else if (ivmode) {
  		DMWARN("Selected cipher does not support IVs");
  		ivmode = NULL;
  	}
  
  	/* Choose ivmode, see comments at iv code. */

  	if (ivmode == NULL)
  		cc->iv_gen_ops = NULL;
  	else if (strcmp(ivmode, "plain") == 0)
  		cc->iv_gen_ops = &crypt_iv_plain_ops;

  	else if (strcmp(ivmode, "plain64") == 0)
  		cc->iv_gen_ops = &crypt_iv_plain64_ops;

  	else if (strcmp(ivmode, "essiv") == 0)
  		cc->iv_gen_ops = &crypt_iv_essiv_ops;

  	else if (strcmp(ivmode, "benbi") == 0)
  		cc->iv_gen_ops = &crypt_iv_benbi_ops;

  	else if (strcmp(ivmode, "null") == 0)
  		cc->iv_gen_ops = &crypt_iv_null_ops;

  	else {

  		ret = -EINVAL;

  		ti->error = "Invalid IV mode";

  		goto bad;

  	}

  	/* Allocate IV */
  	if (cc->iv_gen_ops && cc->iv_gen_ops->ctr) {
  		ret = cc->iv_gen_ops->ctr(cc, ti, ivopts);
  		if (ret < 0) {
  			ti->error = "Error creating IV";
  			goto bad;
  		}
  	}

  	/* Initialize IV (set keys for ESSIV etc) */
  	if (cc->iv_gen_ops && cc->iv_gen_ops->init) {
  		ret = cc->iv_gen_ops->init(cc);
  		if (ret < 0) {
  			ti->error = "Error initialising IV";
  			goto bad;
  		}

  	}

  	ret = 0;
  bad:
  	kfree(cipher_api);
  	return ret;
  
  bad_mem:
  	ti->error = "Cannot allocate cipher strings";
  	return -ENOMEM;
  }
  
  /*
   * Construct an encryption mapping:
   * <cipher> <key> <iv_offset> <dev_path> <start>
   */
  static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  {
  	struct crypt_config *cc;
  	unsigned int key_size;
  	unsigned long long tmpll;
  	int ret;
  
  	if (argc != 5) {
  		ti->error = "Not enough arguments";
  		return -EINVAL;

  	}

  	key_size = strlen(argv[1]) >> 1;
  
  	cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
  	if (!cc) {
  		ti->error = "Cannot allocate encryption context";
  		return -ENOMEM;
  	}
  
  	ti->private = cc;
  	ret = crypt_ctr_cipher(ti, argv[0], argv[1]);
  	if (ret < 0)
  		goto bad;

  	ret = -ENOMEM;

  	cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);

  	if (!cc->io_pool) {

  		ti->error = "Cannot allocate crypt io mempool";

  		goto bad;

  	}

  	cc->dmreq_start = sizeof(struct ablkcipher_request);

  	cc->dmreq_start += crypto_ablkcipher_reqsize(cc->tfm);

  	cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());

  	cc->dmreq_start += crypto_ablkcipher_alignmask(cc->tfm) &

  			   ~(crypto_tfm_ctx_alignment() - 1);

  
  	cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
  			sizeof(struct dm_crypt_request) + cc->iv_size);
  	if (!cc->req_pool) {
  		ti->error = "Cannot allocate crypt request mempool";

  		goto bad;

  	}
  	cc->req = NULL;

  	cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);

  	if (!cc->page_pool) {

  		ti->error = "Cannot allocate page mempool";

  		goto bad;

  	}

  	cc->bs = bioset_create(MIN_IOS, 0);

  	if (!cc->bs) {
  		ti->error = "Cannot allocate crypt bioset";

  		goto bad;

  	}

  	ret = -EINVAL;

  	if (sscanf(argv[2], "%llu", &tmpll) != 1) {

  		ti->error = "Invalid iv_offset sector";

  		goto bad;

  	}

  	cc->iv_offset = tmpll;

  	if (dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &cc->dev)) {
  		ti->error = "Device lookup failed";
  		goto bad;
  	}

  	if (sscanf(argv[4], "%llu", &tmpll) != 1) {

  		ti->error = "Invalid device sector";

  		goto bad;

  	}

  	cc->start = tmpll;

  	ret = -ENOMEM;

  	cc->io_queue = create_singlethread_workqueue("kcryptd_io");
  	if (!cc->io_queue) {
  		ti->error = "Couldn't create kcryptd io queue";

  		goto bad;

  	}
  
  	cc->crypt_queue = create_singlethread_workqueue("kcryptd");
  	if (!cc->crypt_queue) {

  		ti->error = "Couldn't create kcryptd queue";

  		goto bad;

  	}

  	ti->num_flush_requests = 1;

  	return 0;

  bad:
  	crypt_dtr(ti);
  	return ret;

  }

  static int crypt_map(struct dm_target *ti, struct bio *bio,
  		     union map_info *map_context)
  {

  	struct dm_crypt_io *io;

  	struct crypt_config *cc;
  
  	if (unlikely(bio_empty_barrier(bio))) {
  		cc = ti->private;
  		bio->bi_bdev = cc->dev->bdev;
  		return DM_MAPIO_REMAPPED;
  	}

  	io = crypt_io_alloc(ti, bio, dm_target_offset(ti, bio->bi_sector));

  
  	if (bio_data_dir(io->base_bio) == READ)
  		kcryptd_queue_io(io);
  	else
  		kcryptd_queue_crypt(io);

  	return DM_MAPIO_SUBMITTED;

  }
  
  static int crypt_status(struct dm_target *ti, status_type_t type,
  			char *result, unsigned int maxlen)
  {

  	struct crypt_config *cc = ti->private;

  	unsigned int sz = 0;
  
  	switch (type) {
  	case STATUSTYPE_INFO:
  		result[0] = '\0';
  		break;
  
  	case STATUSTYPE_TABLE:

  		if (cc->cipher_mode)
  			DMEMIT("%s-%s ", cc->cipher, cc->cipher_mode);

  		else

  			DMEMIT("%s ", cc->cipher);

  
  		if (cc->key_size > 0) {
  			if ((maxlen - sz) < ((cc->key_size << 1) + 1))
  				return -ENOMEM;
  
  			crypt_encode_key(result + sz, cc->key, cc->key_size);
  			sz += cc->key_size << 1;
  		} else {
  			if (sz >= maxlen)
  				return -ENOMEM;
  			result[sz++] = '-';
  		}

  		DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
  				cc->dev->name, (unsigned long long)cc->start);

  		break;
  	}
  	return 0;
  }

  static void crypt_postsuspend(struct dm_target *ti)
  {
  	struct crypt_config *cc = ti->private;
  
  	set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
  }
  
  static int crypt_preresume(struct dm_target *ti)
  {
  	struct crypt_config *cc = ti->private;
  
  	if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
  		DMERR("aborting resume - crypt key is not set.");
  		return -EAGAIN;
  	}
  
  	return 0;
  }
  
  static void crypt_resume(struct dm_target *ti)
  {
  	struct crypt_config *cc = ti->private;
  
  	clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
  }
  
  /* Message interface
   *	key set <key>
   *	key wipe
   */
  static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
  {
  	struct crypt_config *cc = ti->private;

  	int ret = -EINVAL;

  
  	if (argc < 2)
  		goto error;
  
  	if (!strnicmp(argv[0], MESG_STR("key"))) {
  		if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
  			DMWARN("not suspended during key manipulation.");
  			return -EINVAL;
  		}

  		if (argc == 3 && !strnicmp(argv[1], MESG_STR("set"))) {
  			ret = crypt_set_key(cc, argv[2]);
  			if (ret)
  				return ret;
  			if (cc->iv_gen_ops && cc->iv_gen_ops->init)
  				ret = cc->iv_gen_ops->init(cc);
  			return ret;
  		}
  		if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) {
  			if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
  				ret = cc->iv_gen_ops->wipe(cc);
  				if (ret)
  					return ret;
  			}

  			return crypt_wipe_key(cc);

  		}

  	}
  
  error:
  	DMWARN("unrecognised message received.");
  	return -EINVAL;
  }

  static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
  		       struct bio_vec *biovec, int max_size)
  {
  	struct crypt_config *cc = ti->private;
  	struct request_queue *q = bdev_get_queue(cc->dev->bdev);
  
  	if (!q->merge_bvec_fn)
  		return max_size;
  
  	bvm->bi_bdev = cc->dev->bdev;

  	bvm->bi_sector = cc->start + dm_target_offset(ti, bvm->bi_sector);

  
  	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
  }

  static int crypt_iterate_devices(struct dm_target *ti,
  				 iterate_devices_callout_fn fn, void *data)
  {
  	struct crypt_config *cc = ti->private;

  	return fn(ti, cc->dev, cc->start, ti->len, data);

  }

  static struct target_type crypt_target = {
  	.name   = "crypt",

  	.version = {1, 7, 0},

  	.module = THIS_MODULE,
  	.ctr    = crypt_ctr,
  	.dtr    = crypt_dtr,
  	.map    = crypt_map,
  	.status = crypt_status,

  	.postsuspend = crypt_postsuspend,
  	.preresume = crypt_preresume,
  	.resume = crypt_resume,
  	.message = crypt_message,

  	.merge  = crypt_merge,

  	.iterate_devices = crypt_iterate_devices,

  };
  
  static int __init dm_crypt_init(void)
  {
  	int r;

  	_crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);

  	if (!_crypt_io_pool)
  		return -ENOMEM;

  	r = dm_register_target(&crypt_target);
  	if (r < 0) {

  		DMERR("register failed %d", r);

  		kmem_cache_destroy(_crypt_io_pool);

  	}

  	return r;
  }
  
  static void __exit dm_crypt_exit(void)
  {

  	dm_unregister_target(&crypt_target);

  	kmem_cache_destroy(_crypt_io_pool);
  }
  
  module_init(dm_crypt_init);
  module_exit(dm_crypt_exit);
  
  MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
  MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
  MODULE_LICENSE("GPL");