/*
   * 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.
   * Copyright (C) 2013 Milan Broz <gmazyland@gmail.com>
   *
   * 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 <linux/atomic.h>
  #include <linux/scatterlist.h>
  #include <asm/page.h>
  #include <asm/unaligned.h>
  #include <crypto/hash.h>
  #include <crypto/md5.h>
  #include <crypto/algapi.h>
  
  #include <linux/device-mapper.h>
  
  #define DM_MSG_PREFIX "crypt"
  
  /*
   * context holding the current state of a multi-part conversion
   */
  struct convert_context {
  	struct completion restart;
  	struct bio *bio_in;
  	struct bio *bio_out;
  	struct bvec_iter iter_in;
  	struct bvec_iter iter_out;
  	sector_t cc_sector;
  	atomic_t cc_pending;
  	struct ablkcipher_request *req;
  };
  
  /*
   * per bio private data
   */
  struct dm_crypt_io {
  	struct crypt_config *cc;
  	struct bio *base_bio;
  	struct work_struct work;
  
  	struct convert_context ctx;
  
  	atomic_t io_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;
  	sector_t iv_sector;
  };
  
  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,
  			 struct dm_crypt_request *dmreq);
  	int (*post)(struct crypt_config *cc, u8 *iv,
  		    struct dm_crypt_request *dmreq);
  };
  
  struct iv_essiv_private {
  	struct crypto_hash *hash_tfm;
  	u8 *salt;
  };
  
  struct iv_benbi_private {
  	int shift;
  };
  
  #define LMK_SEED_SIZE 64 /* hash + 0 */
  struct iv_lmk_private {
  	struct crypto_shash *hash_tfm;
  	u8 *seed;
  };
  
  #define TCW_WHITENING_SIZE 16
  struct iv_tcw_private {
  	struct crypto_shash *crc32_tfm;
  	u8 *iv_seed;
  	u8 *whitening;
  };
  
  /*
   * 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 };
  
  /*
   * The fields in here must be read only after initialization.
   */
  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_string;
  
  	struct crypt_iv_operations *iv_gen_ops;
  	union {
  		struct iv_essiv_private essiv;
  		struct iv_benbi_private benbi;
  		struct iv_lmk_private lmk;
  		struct iv_tcw_private tcw;
  	} iv_gen_private;
  	sector_t iv_offset;
  	unsigned int iv_size;
  
  	/* ESSIV: struct crypto_cipher *essiv_tfm */
  	void *iv_private;
  	struct crypto_ablkcipher **tfms;
  	unsigned tfms_count;
  
  	/*
  	 * 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;
  
  	unsigned long flags;
  	unsigned int key_size;
  	unsigned int key_parts;      /* independent parts in key buffer */
  	unsigned int key_extra_size; /* additional keys length */
  	u8 key[0];
  };
  
  #define MIN_IOS        16
  #define MIN_POOL_PAGES 32
  
  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);
  static u8 *iv_of_dmreq(struct crypt_config *cc, struct dm_crypt_request *dmreq);
  
  /*
   * Use this to access cipher attributes that are the same for each CPU.
   */
  static struct crypto_ablkcipher *any_tfm(struct crypt_config *cc)
  {
  	return cc->tfms[0];
  }
  
  /*
   * 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.
   *
   * lmk:  Compatible implementation of the block chaining mode used
   *       by the Loop-AES block device encryption system
   *       designed by Jari Ruusu. See http://loop-aes.sourceforge.net/
   *       It operates on full 512 byte sectors and uses CBC
   *       with an IV derived from the sector number, the data and
   *       optionally extra IV seed.
   *       This means that after decryption the first block
   *       of sector must be tweaked according to decrypted data.
   *       Loop-AES can use three encryption schemes:
   *         version 1: is plain aes-cbc mode
   *         version 2: uses 64 multikey scheme with lmk IV generator
   *         version 3: the same as version 2 with additional IV seed
   *                   (it uses 65 keys, last key is used as IV seed)
   *
   * tcw:  Compatible implementation of the block chaining mode used
   *       by the TrueCrypt device encryption system (prior to version 4.1).
   *       For more info see: http://www.truecrypt.org
   *       It operates on full 512 byte sectors and uses CBC
   *       with an IV derived from initial key and the sector number.
   *       In addition, whitening value is applied on every sector, whitening
   *       is calculated from initial key, sector number and mixed using CRC32.
   *       Note that this encryption scheme is vulnerable to watermarking attacks
   *       and should be used for old compatible containers access only.
   *
   * 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,
  			      struct dm_crypt_request *dmreq)
  {
  	memset(iv, 0, cc->iv_size);
  	*(__le32 *)iv = cpu_to_le32(dmreq->iv_sector & 0xffffffff);
  
  	return 0;
  }
  
  static int crypt_iv_plain64_gen(struct crypt_config *cc, u8 *iv,
  				struct dm_crypt_request *dmreq)
  {
  	memset(iv, 0, cc->iv_size);
  	*(__le64 *)iv = cpu_to_le64(dmreq->iv_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;
  	struct crypto_cipher *essiv_tfm;
  	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;
  
  	essiv_tfm = cc->iv_private;
  
  	err = crypto_cipher_setkey(essiv_tfm, essiv->salt,
  			    crypto_hash_digestsize(essiv->hash_tfm));
  	if (err)
  		return err;
  
  	return 0;
  }
  
  /* 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);
  	struct crypto_cipher *essiv_tfm;
  	int r, err = 0;
  
  	memset(essiv->salt, 0, salt_size);
  
  	essiv_tfm = cc->iv_private;
  	r = crypto_cipher_setkey(essiv_tfm, essiv->salt, salt_size);
  	if (r)
  		err = r;
  
  	return err;
  }
  
  /* Set up per cpu cipher state */
  static struct crypto_cipher *setup_essiv_cpu(struct crypt_config *cc,
  					     struct dm_target *ti,
  					     u8 *salt, unsigned saltsize)
  {
  	struct crypto_cipher *essiv_tfm;
  	int err;
  
  	/* Setup the essiv_tfm with the given salt */
  	essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
  	if (IS_ERR(essiv_tfm)) {
  		ti->error = "Error allocating crypto tfm for ESSIV";
  		return essiv_tfm;
  	}
  
  	if (crypto_cipher_blocksize(essiv_tfm) !=
  	    crypto_ablkcipher_ivsize(any_tfm(cc))) {
  		ti->error = "Block size of ESSIV cipher does "
  			    "not match IV size of block cipher";
  		crypto_free_cipher(essiv_tfm);
  		return ERR_PTR(-EINVAL);
  	}
  
  	err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
  	if (err) {
  		ti->error = "Failed to set key for ESSIV cipher";
  		crypto_free_cipher(essiv_tfm);
  		return ERR_PTR(err);
  	}
  
  	return essiv_tfm;
  }
  
  static void crypt_iv_essiv_dtr(struct crypt_config *cc)
  {
  	struct crypto_cipher *essiv_tfm;
  	struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
  
  	crypto_free_hash(essiv->hash_tfm);
  	essiv->hash_tfm = NULL;
  
  	kzfree(essiv->salt);
  	essiv->salt = NULL;
  
  	essiv_tfm = cc->iv_private;
  
  	if (essiv_tfm)
  		crypto_free_cipher(essiv_tfm);
  
  	cc->iv_private = 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;
  	}
  
  	cc->iv_gen_private.essiv.salt = salt;
  	cc->iv_gen_private.essiv.hash_tfm = hash_tfm;
  
  	essiv_tfm = setup_essiv_cpu(cc, ti, salt,
  				crypto_hash_digestsize(hash_tfm));
  	if (IS_ERR(essiv_tfm)) {
  		crypt_iv_essiv_dtr(cc);
  		return PTR_ERR(essiv_tfm);
  	}
  	cc->iv_private = essiv_tfm;
  
  	return 0;
  
  bad:
  	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,
  			      struct dm_crypt_request *dmreq)
  {
  	struct crypto_cipher *essiv_tfm = cc->iv_private;
  
  	memset(iv, 0, cc->iv_size);
  	*(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);
  	crypto_cipher_encrypt_one(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(any_tfm(cc));
  	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,
  			      struct dm_crypt_request *dmreq)
  {
  	__be64 val;
  
  	memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
  
  	val = cpu_to_be64(((u64)dmreq->iv_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,
  			     struct dm_crypt_request *dmreq)
  {
  	memset(iv, 0, cc->iv_size);
  
  	return 0;
  }
  
  static void crypt_iv_lmk_dtr(struct crypt_config *cc)
  {
  	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
  
  	if (lmk->hash_tfm && !IS_ERR(lmk->hash_tfm))
  		crypto_free_shash(lmk->hash_tfm);
  	lmk->hash_tfm = NULL;
  
  	kzfree(lmk->seed);
  	lmk->seed = NULL;
  }
  
  static int crypt_iv_lmk_ctr(struct crypt_config *cc, struct dm_target *ti,
  			    const char *opts)
  {
  	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
  
  	lmk->hash_tfm = crypto_alloc_shash("md5", 0, 0);
  	if (IS_ERR(lmk->hash_tfm)) {
  		ti->error = "Error initializing LMK hash";
  		return PTR_ERR(lmk->hash_tfm);
  	}
  
  	/* No seed in LMK version 2 */
  	if (cc->key_parts == cc->tfms_count) {
  		lmk->seed = NULL;
  		return 0;
  	}
  
  	lmk->seed = kzalloc(LMK_SEED_SIZE, GFP_KERNEL);
  	if (!lmk->seed) {
  		crypt_iv_lmk_dtr(cc);
  		ti->error = "Error kmallocing seed storage in LMK";
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  static int crypt_iv_lmk_init(struct crypt_config *cc)
  {
  	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
  	int subkey_size = cc->key_size / cc->key_parts;
  
  	/* LMK seed is on the position of LMK_KEYS + 1 key */
  	if (lmk->seed)
  		memcpy(lmk->seed, cc->key + (cc->tfms_count * subkey_size),
  		       crypto_shash_digestsize(lmk->hash_tfm));
  
  	return 0;
  }
  
  static int crypt_iv_lmk_wipe(struct crypt_config *cc)
  {
  	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
  
  	if (lmk->seed)
  		memset(lmk->seed, 0, LMK_SEED_SIZE);
  
  	return 0;
  }
  
  static int crypt_iv_lmk_one(struct crypt_config *cc, u8 *iv,
  			    struct dm_crypt_request *dmreq,
  			    u8 *data)
  {
  	struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
  	struct {
  		struct shash_desc desc;
  		char ctx[crypto_shash_descsize(lmk->hash_tfm)];
  	} sdesc;
  	struct md5_state md5state;
  	__le32 buf[4];
  	int i, r;
  
  	sdesc.desc.tfm = lmk->hash_tfm;
  	sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
  
  	r = crypto_shash_init(&sdesc.desc);
  	if (r)
  		return r;
  
  	if (lmk->seed) {
  		r = crypto_shash_update(&sdesc.desc, lmk->seed, LMK_SEED_SIZE);
  		if (r)
  			return r;
  	}
  
  	/* Sector is always 512B, block size 16, add data of blocks 1-31 */
  	r = crypto_shash_update(&sdesc.desc, data + 16, 16 * 31);
  	if (r)
  		return r;
  
  	/* Sector is cropped to 56 bits here */
  	buf[0] = cpu_to_le32(dmreq->iv_sector & 0xFFFFFFFF);
  	buf[1] = cpu_to_le32((((u64)dmreq->iv_sector >> 32) & 0x00FFFFFF) | 0x80000000);
  	buf[2] = cpu_to_le32(4024);
  	buf[3] = 0;
  	r = crypto_shash_update(&sdesc.desc, (u8 *)buf, sizeof(buf));
  	if (r)
  		return r;
  
  	/* No MD5 padding here */
  	r = crypto_shash_export(&sdesc.desc, &md5state);
  	if (r)
  		return r;
  
  	for (i = 0; i < MD5_HASH_WORDS; i++)
  		__cpu_to_le32s(&md5state.hash[i]);
  	memcpy(iv, &md5state.hash, cc->iv_size);
  
  	return 0;
  }
  
  static int crypt_iv_lmk_gen(struct crypt_config *cc, u8 *iv,
  			    struct dm_crypt_request *dmreq)
  {
  	u8 *src;
  	int r = 0;
  
  	if (bio_data_dir(dmreq->ctx->bio_in) == WRITE) {
  		src = kmap_atomic(sg_page(&dmreq->sg_in));
  		r = crypt_iv_lmk_one(cc, iv, dmreq, src + dmreq->sg_in.offset);
  		kunmap_atomic(src);
  	} else
  		memset(iv, 0, cc->iv_size);
  
  	return r;
  }
  
  static int crypt_iv_lmk_post(struct crypt_config *cc, u8 *iv,
  			     struct dm_crypt_request *dmreq)
  {
  	u8 *dst;
  	int r;
  
  	if (bio_data_dir(dmreq->ctx->bio_in) == WRITE)
  		return 0;
  
  	dst = kmap_atomic(sg_page(&dmreq->sg_out));
  	r = crypt_iv_lmk_one(cc, iv, dmreq, dst + dmreq->sg_out.offset);
  
  	/* Tweak the first block of plaintext sector */
  	if (!r)
  		crypto_xor(dst + dmreq->sg_out.offset, iv, cc->iv_size);
  
  	kunmap_atomic(dst);
  	return r;
  }
  
  static void crypt_iv_tcw_dtr(struct crypt_config *cc)
  {
  	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
  
  	kzfree(tcw->iv_seed);
  	tcw->iv_seed = NULL;
  	kzfree(tcw->whitening);
  	tcw->whitening = NULL;
  
  	if (tcw->crc32_tfm && !IS_ERR(tcw->crc32_tfm))
  		crypto_free_shash(tcw->crc32_tfm);
  	tcw->crc32_tfm = NULL;
  }
  
  static int crypt_iv_tcw_ctr(struct crypt_config *cc, struct dm_target *ti,
  			    const char *opts)
  {
  	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
  
  	if (cc->key_size <= (cc->iv_size + TCW_WHITENING_SIZE)) {
  		ti->error = "Wrong key size for TCW";
  		return -EINVAL;
  	}
  
  	tcw->crc32_tfm = crypto_alloc_shash("crc32", 0, 0);
  	if (IS_ERR(tcw->crc32_tfm)) {
  		ti->error = "Error initializing CRC32 in TCW";
  		return PTR_ERR(tcw->crc32_tfm);
  	}
  
  	tcw->iv_seed = kzalloc(cc->iv_size, GFP_KERNEL);
  	tcw->whitening = kzalloc(TCW_WHITENING_SIZE, GFP_KERNEL);
  	if (!tcw->iv_seed || !tcw->whitening) {
  		crypt_iv_tcw_dtr(cc);
  		ti->error = "Error allocating seed storage in TCW";
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  static int crypt_iv_tcw_init(struct crypt_config *cc)
  {
  	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
  	int key_offset = cc->key_size - cc->iv_size - TCW_WHITENING_SIZE;
  
  	memcpy(tcw->iv_seed, &cc->key[key_offset], cc->iv_size);
  	memcpy(tcw->whitening, &cc->key[key_offset + cc->iv_size],
  	       TCW_WHITENING_SIZE);
  
  	return 0;
  }
  
  static int crypt_iv_tcw_wipe(struct crypt_config *cc)
  {
  	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
  
  	memset(tcw->iv_seed, 0, cc->iv_size);
  	memset(tcw->whitening, 0, TCW_WHITENING_SIZE);
  
  	return 0;
  }
  
  static int crypt_iv_tcw_whitening(struct crypt_config *cc,
  				  struct dm_crypt_request *dmreq,
  				  u8 *data)
  {
  	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
  	u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
  	u8 buf[TCW_WHITENING_SIZE];
  	struct {
  		struct shash_desc desc;
  		char ctx[crypto_shash_descsize(tcw->crc32_tfm)];
  	} sdesc;
  	int i, r;
  
  	/* xor whitening with sector number */
  	memcpy(buf, tcw->whitening, TCW_WHITENING_SIZE);
  	crypto_xor(buf, (u8 *)&sector, 8);
  	crypto_xor(&buf[8], (u8 *)&sector, 8);
  
  	/* calculate crc32 for every 32bit part and xor it */
  	sdesc.desc.tfm = tcw->crc32_tfm;
  	sdesc.desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
  	for (i = 0; i < 4; i++) {
  		r = crypto_shash_init(&sdesc.desc);
  		if (r)
  			goto out;
  		r = crypto_shash_update(&sdesc.desc, &buf[i * 4], 4);
  		if (r)
  			goto out;
  		r = crypto_shash_final(&sdesc.desc, &buf[i * 4]);
  		if (r)
  			goto out;
  	}
  	crypto_xor(&buf[0], &buf[12], 4);
  	crypto_xor(&buf[4], &buf[8], 4);
  
  	/* apply whitening (8 bytes) to whole sector */
  	for (i = 0; i < ((1 << SECTOR_SHIFT) / 8); i++)
  		crypto_xor(data + i * 8, buf, 8);
  out:
  	memzero_explicit(buf, sizeof(buf));
  	return r;
  }
  
  static int crypt_iv_tcw_gen(struct crypt_config *cc, u8 *iv,
  			    struct dm_crypt_request *dmreq)
  {
  	struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
  	u64 sector = cpu_to_le64((u64)dmreq->iv_sector);
  	u8 *src;
  	int r = 0;
  
  	/* Remove whitening from ciphertext */
  	if (bio_data_dir(dmreq->ctx->bio_in) != WRITE) {
  		src = kmap_atomic(sg_page(&dmreq->sg_in));
  		r = crypt_iv_tcw_whitening(cc, dmreq, src + dmreq->sg_in.offset);
  		kunmap_atomic(src);
  	}
  
  	/* Calculate IV */
  	memcpy(iv, tcw->iv_seed, cc->iv_size);
  	crypto_xor(iv, (u8 *)&sector, 8);
  	if (cc->iv_size > 8)
  		crypto_xor(&iv[8], (u8 *)&sector, cc->iv_size - 8);
  
  	return r;
  }
  
  static int crypt_iv_tcw_post(struct crypt_config *cc, u8 *iv,
  			     struct dm_crypt_request *dmreq)
  {
  	u8 *dst;
  	int r;
  
  	if (bio_data_dir(dmreq->ctx->bio_in) != WRITE)
  		return 0;
  
  	/* Apply whitening on ciphertext */
  	dst = kmap_atomic(sg_page(&dmreq->sg_out));
  	r = crypt_iv_tcw_whitening(cc, dmreq, dst + dmreq->sg_out.offset);
  	kunmap_atomic(dst);
  
  	return r;
  }
  
  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 struct crypt_iv_operations crypt_iv_lmk_ops = {
  	.ctr	   = crypt_iv_lmk_ctr,
  	.dtr	   = crypt_iv_lmk_dtr,
  	.init	   = crypt_iv_lmk_init,
  	.wipe	   = crypt_iv_lmk_wipe,
  	.generator = crypt_iv_lmk_gen,
  	.post	   = crypt_iv_lmk_post
  };
  
  static struct crypt_iv_operations crypt_iv_tcw_ops = {
  	.ctr	   = crypt_iv_tcw_ctr,
  	.dtr	   = crypt_iv_tcw_dtr,
  	.init	   = crypt_iv_tcw_init,
  	.wipe	   = crypt_iv_tcw_wipe,
  	.generator = crypt_iv_tcw_gen,
  	.post	   = crypt_iv_tcw_post
  };
  
  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;
  	if (bio_in)
  		ctx->iter_in = bio_in->bi_iter;
  	if (bio_out)
  		ctx->iter_out = bio_out->bi_iter;
  	ctx->cc_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 u8 *iv_of_dmreq(struct crypt_config *cc,
  		       struct dm_crypt_request *dmreq)
  {
  	return (u8 *)ALIGN((unsigned long)(dmreq + 1),
  		crypto_ablkcipher_alignmask(any_tfm(cc)) + 1);
  }
  
  static int crypt_convert_block(struct crypt_config *cc,
  			       struct convert_context *ctx,
  			       struct ablkcipher_request *req)
  {
  	struct bio_vec bv_in = bio_iter_iovec(ctx->bio_in, ctx->iter_in);
  	struct bio_vec bv_out = bio_iter_iovec(ctx->bio_out, ctx->iter_out);
  	struct dm_crypt_request *dmreq;
  	u8 *iv;
  	int r;
  
  	dmreq = dmreq_of_req(cc, req);
  	iv = iv_of_dmreq(cc, dmreq);
  
  	dmreq->iv_sector = ctx->cc_sector;
  	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);
  
  	sg_init_table(&dmreq->sg_out, 1);
  	sg_set_page(&dmreq->sg_out, bv_out.bv_page, 1 << SECTOR_SHIFT,
  		    bv_out.bv_offset);
  
  	bio_advance_iter(ctx->bio_in, &ctx->iter_in, 1 << SECTOR_SHIFT);
  	bio_advance_iter(ctx->bio_out, &ctx->iter_out, 1 << SECTOR_SHIFT);
  
  	if (cc->iv_gen_ops) {
  		r = cc->iv_gen_ops->generator(cc, iv, dmreq);
  		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);
  
  	if (!r && cc->iv_gen_ops && cc->iv_gen_ops->post)
  		r = cc->iv_gen_ops->post(cc, iv, dmreq);
  
  	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)
  {
  	unsigned key_index = ctx->cc_sector & (cc->tfms_count - 1);
  
  	if (!ctx->req)
  		ctx->req = mempool_alloc(cc->req_pool, GFP_NOIO);
  
  	ablkcipher_request_set_tfm(ctx->req, cc->tfms[key_index]);
  	ablkcipher_request_set_callback(ctx->req,
  	    CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
  	    kcryptd_async_done, dmreq_of_req(cc, ctx->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->cc_pending, 1);
  
  	while (ctx->iter_in.bi_size && ctx->iter_out.bi_size) {
  
  		crypt_alloc_req(cc, ctx);
  
  		atomic_inc(&ctx->cc_pending);
  
  		r = crypt_convert_block(cc, ctx, ctx->req);
  
  		switch (r) {
  		/* async */
  		case -EBUSY:
  			wait_for_completion(&ctx->restart);
  			reinit_completion(&ctx->restart);
  			/* fall through*/
  		case -EINPROGRESS:
  			ctx->req = NULL;
  			ctx->cc_sector++;
  			continue;
  
  		/* sync */
  		case 0:
  			atomic_dec(&ctx->cc_pending);
  			ctx->cc_sector++;
  			cond_resched();
  			continue;
  
  		/* error */
  		default:
  			atomic_dec(&ctx->cc_pending);
  			return r;
  		}
  	}
  
  	return 0;
  }
  
  /*
   * 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->cc;
  	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 more bios while submitting this partial bio.
  		 */
  		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_iter.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;
  
  	bio_for_each_segment_all(bv, 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 crypt_config *cc,
  					  struct bio *bio, sector_t sector)
  {
  	struct dm_crypt_io *io;
  
  	io = mempool_alloc(cc->io_pool, GFP_NOIO);
  	io->cc = cc;
  	io->base_bio = bio;
  	io->sector = sector;
  	io->error = 0;
  	io->base_io = NULL;
  	io->ctx.req = NULL;
  	atomic_set(&io->io_pending, 0);
  
  	return io;
  }
  
  static void crypt_inc_pending(struct dm_crypt_io *io)
  {
  	atomic_inc(&io->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->cc;
  	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->io_pending))
  		return;
  
  	if (io->ctx.req)
  		mempool_free(io->ctx.req, cc->req_pool);
  	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.
   *
   * The work is done per CPU global for all dm-crypt instances.
   * They should not depend on each other and do not block.
   */
  static void crypt_endio(struct bio *clone, int error)
  {
  	struct dm_crypt_io *io = clone->bi_private;
  	struct crypt_config *cc = io->cc;
  	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->cc;
  
  	clone->bi_private = io;
  	clone->bi_end_io  = crypt_endio;
  	clone->bi_bdev    = cc->dev->bdev;
  	clone->bi_rw      = io->base_bio->bi_rw;
  }
  
  static int kcryptd_io_read(struct dm_crypt_io *io, gfp_t gfp)
  {
  	struct crypt_config *cc = io->cc;
  	struct bio *base_bio = io->base_bio;
  	struct bio *clone;
  
  	/*
  	 * 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_clone_bioset(base_bio, gfp, cc->bs);
  	if (!clone)
  		return 1;
  
  	crypt_inc_pending(io);
  
  	clone_init(io, clone);
  	clone->bi_iter.bi_sector = cc->start + io->sector;
  
  	generic_make_request(clone);
  	return 0;
  }
  
  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) {
  		crypt_inc_pending(io);
  		if (kcryptd_io_read(io, GFP_NOIO))
  			io->error = -ENOMEM;
  		crypt_dec_pending(io);
  	} else
  		kcryptd_io_write(io);
  }
  
  static void kcryptd_queue_io(struct dm_crypt_io *io)
  {
  	struct crypt_config *cc = io->cc;
  
  	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 async)
  {
  	struct bio *clone = io->ctx.bio_out;
  	struct crypt_config *cc = io->cc;
  
  	if (unlikely(io->error < 0)) {
  		crypt_free_buffer_pages(cc, clone);
  		bio_put(clone);
  		crypt_dec_pending(io);
  		return;
  	}
  
  	/* crypt_convert should have filled the clone bio */
  	BUG_ON(io->ctx.iter_out.bi_size);
  
  	clone->bi_iter.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->cc;
  	struct bio *clone;
  	struct dm_crypt_io *new_io;
  	int crypt_finished;
  	unsigned out_of_pages = 0;
  	unsigned remaining = io->base_bio->bi_iter.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.iter_out = clone->bi_iter;
  
  		remaining -= clone->bi_iter.bi_size;
  		sector += bio_sectors(clone);
  
  		crypt_inc_pending(io);
  
  		r = crypt_convert(cc, &io->ctx);
  		if (r < 0)
  			io->error = -EIO;
  
  		crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending);
  
  		/* Encryption was already finished, submit io now */
  		if (crypt_finished) {
  			kcryptd_crypt_write_io_submit(io, 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->cc, io->base_bio,
  						sector);
  			crypt_inc_pending(new_io);
  			crypt_convert_init(cc, &new_io->ctx, NULL,
  					   io->base_bio, sector);
  			new_io->ctx.iter_in = io->ctx.iter_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)
  {
  	crypt_dec_pending(io);
  }
  
  static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
  {
  	struct crypt_config *cc = io->cc;
  	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 (r < 0)
  		io->error = -EIO;
  
  	if (atomic_dec_and_test(&io->ctx.cc_pending))
  		kcryptd_crypt_read_done(io);
  
  	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->cc;
  
  	if (error == -EINPROGRESS) {
  		complete(&ctx->restart);
  		return;
  	}
  
  	if (!error && cc->iv_gen_ops && cc->iv_gen_ops->post)
  		error = cc->iv_gen_ops->post(cc, iv_of_dmreq(cc, dmreq), dmreq);
  
  	if (error < 0)
  		io->error = -EIO;
  
  	mempool_free(req_of_dmreq(cc, dmreq), cc->req_pool);
  
  	if (!atomic_dec_and_test(&ctx->cc_pending))
  		return;
  
  	if (bio_data_dir(io->base_bio) == READ)
  		kcryptd_crypt_read_done(io);
  	else
  		kcryptd_crypt_write_io_submit(io, 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->cc;
  
  	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];
  	unsigned int i;
  
  	buffer[2] = '\0';
  
  	for (i = 0; i < size; i++) {
  		buffer[0] = *hex++;
  		buffer[1] = *hex++;
  
  		if (kstrtou8(buffer, 16, &key[i]))
  			return -EINVAL;
  	}
  
  	if (*hex != '\0')
  		return -EINVAL;
  
  	return 0;
  }
  
  static void crypt_free_tfms(struct crypt_config *cc)
  {
  	unsigned i;
  
  	if (!cc->tfms)
  		return;
  
  	for (i = 0; i < cc->tfms_count; i++)
  		if (cc->tfms[i] && !IS_ERR(cc->tfms[i])) {
  			crypto_free_ablkcipher(cc->tfms[i]);
  			cc->tfms[i] = NULL;
  		}
  
  	kfree(cc->tfms);
  	cc->tfms = NULL;
  }
  
  static int crypt_alloc_tfms(struct crypt_config *cc, char *ciphermode)
  {
  	unsigned i;
  	int err;
  
  	cc->tfms = kmalloc(cc->tfms_count * sizeof(struct crypto_ablkcipher *),
  			   GFP_KERNEL);
  	if (!cc->tfms)
  		return -ENOMEM;
  
  	for (i = 0; i < cc->tfms_count; i++) {
  		cc->tfms[i] = crypto_alloc_ablkcipher(ciphermode, 0, 0);
  		if (IS_ERR(cc->tfms[i])) {
  			err = PTR_ERR(cc->tfms[i]);
  			crypt_free_tfms(cc);
  			return err;
  		}
  	}
  
  	return 0;
  }
  
  static int crypt_setkey_allcpus(struct crypt_config *cc)
  {
  	unsigned subkey_size;
  	int err = 0, i, r;
  
  	/* Ignore extra keys (which are used for IV etc) */
  	subkey_size = (cc->key_size - cc->key_extra_size) >> ilog2(cc->tfms_count);
  
  	for (i = 0; i < cc->tfms_count; i++) {
  		r = crypto_ablkcipher_setkey(cc->tfms[i],
  					     cc->key + (i * subkey_size),
  					     subkey_size);
  		if (r)
  			err = r;
  	}
  
  	return err;
  }
  
  static int crypt_set_key(struct crypt_config *cc, char *key)
  {
  	int r = -EINVAL;
  	int key_string_len = strlen(key);
  
  	/* The key size may not be changed. */
  	if (cc->key_size != (key_string_len >> 1))
  		goto out;
  
  	/* Hyphen (which gives a key_size of zero) means there is no key. */
  	if (!cc->key_size && strcmp(key, "-"))
  		goto out;
  
  	if (cc->key_size && crypt_decode_key(cc->key, key, cc->key_size) < 0)
  		goto out;
  
  	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
  
  	r = crypt_setkey_allcpus(cc);
  
  out:
  	/* Hex key string not needed after here, so wipe it. */
  	memset(key, '0', key_string_len);
  
  	return r;
  }
  
  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 crypt_setkey_allcpus(cc);
  }
  
  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);
  
  	crypt_free_tfms(cc);
  
  	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->dev)
  		dm_put_device(ti, cc->dev);
  
  	kzfree(cc->cipher);
  	kzfree(cc->cipher_string);
  
  	/* 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, *keycount;
  	char *cipher_api = NULL;
  	int ret = -EINVAL;
  	char dummy;
  
  	/* Convert to crypto api definition? */
  	if (strchr(cipher_in, '(')) {
  		ti->error = "Bad cipher specification";
  		return -EINVAL;
  	}
  
  	cc->cipher_string = kstrdup(cipher_in, GFP_KERNEL);
  	if (!cc->cipher_string)
  		goto bad_mem;
  
  	/*
  	 * Legacy dm-crypt cipher specification
  	 * cipher[:keycount]-mode-iv:ivopts
  	 */
  	tmp = cipher_in;
  	keycount = strsep(&tmp, "-");
  	cipher = strsep(&keycount, ":");
  
  	if (!keycount)
  		cc->tfms_count = 1;
  	else if (sscanf(keycount, "%u%c", &cc->tfms_count, &dummy) != 1 ||
  		 !is_power_of_2(cc->tfms_count)) {
  		ti->error = "Bad cipher key count specification";
  		return -EINVAL;
  	}
  	cc->key_parts = cc->tfms_count;
  	cc->key_extra_size = 0;
  
  	cc->cipher = kstrdup(cipher, GFP_KERNEL);
  	if (!cc->cipher)
  		goto bad_mem;
  
  	chainmode = strsep(&tmp, "-");
  	ivopts = strsep(&tmp, "-");
  	ivmode = strsep(&ivopts, ":");
  
  	if (tmp)
  		DMWARN("Ignoring unexpected additional cipher options");
  
  	/*
  	 * For compatibility with the original dm-crypt mapping format, if
  	 * only the cipher name is supplied, use cbc-plain.
  	 */
  	if (!chainmode || (!strcmp(chainmode, "plain") && !ivmode)) {
  		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 */
  	ret = crypt_alloc_tfms(cc, cipher_api);
  	if (ret < 0) {
  		ti->error = "Error allocating crypto tfm";
  		goto bad;
  	}
  
  	/* Initialize IV */
  	cc->iv_size = crypto_ablkcipher_ivsize(any_tfm(cc));
  	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 if (strcmp(ivmode, "lmk") == 0) {
  		cc->iv_gen_ops = &crypt_iv_lmk_ops;
  		/*
  		 * Version 2 and 3 is recognised according
  		 * to length of provided multi-key string.
  		 * If present (version 3), last key is used as IV seed.
  		 * All keys (including IV seed) are always the same size.
  		 */
  		if (cc->key_size % cc->key_parts) {
  			cc->key_parts++;
  			cc->key_extra_size = cc->key_size / cc->key_parts;
  		}
  	} else if (strcmp(ivmode, "tcw") == 0) {
  		cc->iv_gen_ops = &crypt_iv_tcw_ops;
  		cc->key_parts += 2; /* IV + whitening */
  		cc->key_extra_size = cc->iv_size + TCW_WHITENING_SIZE;
  	} else {
  		ret = -EINVAL;
  		ti->error = "Invalid IV mode";
  		goto bad;
  	}
  
  	/* Initialize and set key */
  	ret = crypt_set_key(cc, key);
  	if (ret < 0) {
  		ti->error = "Error decoding and setting key";
  		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, opt_params;
  	unsigned long long tmpll;
  	int ret;
  	size_t iv_size_padding;
  	struct dm_arg_set as;
  	const char *opt_string;
  	char dummy;
  
  	static struct dm_arg _args[] = {
  		{0, 1, "Invalid number of feature args"},
  	};
  
  	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;
  	}
  	cc->key_size = key_size;
  
  	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(any_tfm(cc));
  	cc->dmreq_start = ALIGN(cc->dmreq_start, __alignof__(struct dm_crypt_request));
  
  	if (crypto_ablkcipher_alignmask(any_tfm(cc)) < CRYPTO_MINALIGN) {
  		/* Allocate the padding exactly */
  		iv_size_padding = -(cc->dmreq_start + sizeof(struct dm_crypt_request))
  				& crypto_ablkcipher_alignmask(any_tfm(cc));
  	} else {
  		/*
  		 * If the cipher requires greater alignment than kmalloc
  		 * alignment, we don't know the exact position of the
  		 * initialization vector. We must assume worst case.
  		 */
  		iv_size_padding = crypto_ablkcipher_alignmask(any_tfm(cc));
  	}
  
  	cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
  			sizeof(struct dm_crypt_request) + iv_size_padding + cc->iv_size);
  	if (!cc->req_pool) {
  		ti->error = "Cannot allocate crypt request mempool";
  		goto bad;
  	}
  
  	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%c", &tmpll, &dummy) != 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%c", &tmpll, &dummy) != 1) {
  		ti->error = "Invalid device sector";
  		goto bad;
  	}
  	cc->start = tmpll;
  
  	argv += 5;
  	argc -= 5;
  
  	/* Optional parameters */
  	if (argc) {
  		as.argc = argc;
  		as.argv = argv;
  
  		ret = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
  		if (ret)
  			goto bad;
  
  		opt_string = dm_shift_arg(&as);
  
  		if (opt_params == 1 && opt_string &&
  		    !strcasecmp(opt_string, "allow_discards"))
  			ti->num_discard_bios = 1;
  		else if (opt_params) {
  			ret = -EINVAL;
  			ti->error = "Invalid feature arguments";
  			goto bad;
  		}
  	}
  
  	ret = -ENOMEM;
  	cc->io_queue = alloc_workqueue("kcryptd_io", WQ_MEM_RECLAIM, 1);
  	if (!cc->io_queue) {
  		ti->error = "Couldn't create kcryptd io queue";
  		goto bad;
  	}
  
  	cc->crypt_queue = alloc_workqueue("kcryptd",
  					  WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 1);
  	if (!cc->crypt_queue) {
  		ti->error = "Couldn't create kcryptd queue";
  		goto bad;
  	}
  
  	ti->num_flush_bios = 1;
  	ti->discard_zeroes_data_unsupported = true;
  
  	return 0;
  
  bad:
  	crypt_dtr(ti);
  	return ret;
  }
  
  static int crypt_map(struct dm_target *ti, struct bio *bio)
  {
  	struct dm_crypt_io *io;
  	struct crypt_config *cc = ti->private;
  
  	/*
  	 * If bio is REQ_FLUSH or REQ_DISCARD, just bypass crypt queues.
  	 * - for REQ_FLUSH device-mapper core ensures that no IO is in-flight
  	 * - for REQ_DISCARD caller must use flush if IO ordering matters
  	 */
  	if (unlikely(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD))) {
  		bio->bi_bdev = cc->dev->bdev;
  		if (bio_sectors(bio))
  			bio->bi_iter.bi_sector = cc->start +
  				dm_target_offset(ti, bio->bi_iter.bi_sector);
  		return DM_MAPIO_REMAPPED;
  	}
  
  	io = crypt_io_alloc(cc, bio, dm_target_offset(ti, bio->bi_iter.bi_sector));
  
  	if (bio_data_dir(io->base_bio) == READ) {
  		if (kcryptd_io_read(io, GFP_NOWAIT))
  			kcryptd_queue_io(io);
  	} else
  		kcryptd_queue_crypt(io);
  
  	return DM_MAPIO_SUBMITTED;
  }
  
  static void crypt_status(struct dm_target *ti, status_type_t type,
  			 unsigned status_flags, char *result, unsigned maxlen)
  {
  	struct crypt_config *cc = ti->private;
  	unsigned i, sz = 0;
  
  	switch (type) {
  	case STATUSTYPE_INFO:
  		result[0] = '\0';
  		break;
  
  	case STATUSTYPE_TABLE:
  		DMEMIT("%s ", cc->cipher_string);
  
  		if (cc->key_size > 0)
  			for (i = 0; i < cc->key_size; i++)
  				DMEMIT("%02x", cc->key[i]);
  		else
  			DMEMIT("-");
  
  		DMEMIT(" %llu %s %llu", (unsigned long long)cc->iv_offset,
  				cc->dev->name, (unsigned long long)cc->start);
  
  		if (ti->num_discard_bios)
  			DMEMIT(" 1 allow_discards");
  
  		break;
  	}
  }
  
  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 (!strcasecmp(argv[0], "key")) {
  		if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
  			DMWARN("not suspended during key manipulation.");
  			return -EINVAL;
  		}
  		if (argc == 3 && !strcasecmp(argv[1], "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 && !strcasecmp(argv[1], "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, 13, 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");