/*
   * Copyright (C) 2012 Red Hat, Inc.
   * Copyright (C) 2015 Google, Inc.
   *
   * Author: Mikulas Patocka <mpatocka@redhat.com>
   *
   * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   *
   * This file is released under the GPLv2.
   */
  
  #ifndef DM_VERITY_H
  #define DM_VERITY_H
  
  #include "dm-bufio.h"
  #include <linux/device-mapper.h>
  #include <crypto/hash.h>
  
  #define DM_VERITY_MAX_LEVELS		63
  
  enum verity_mode {
  	DM_VERITY_MODE_EIO,
  	DM_VERITY_MODE_LOGGING,
  	DM_VERITY_MODE_RESTART
  };
  
  enum verity_block_type {
  	DM_VERITY_BLOCK_TYPE_DATA,
  	DM_VERITY_BLOCK_TYPE_METADATA
  };

  struct dm_verity_fec;

  struct dm_verity {
  	struct dm_dev *data_dev;
  	struct dm_dev *hash_dev;
  	struct dm_target *ti;
  	struct dm_bufio_client *bufio;
  	char *alg_name;

  	struct crypto_ahash *tfm;

  	u8 *root_digest;	/* digest of the root block */
  	u8 *salt;		/* salt: its size is salt_size */

  	u8 *zero_digest;	/* digest for a zero block */

  	unsigned salt_size;
  	sector_t data_start;	/* data offset in 512-byte sectors */
  	sector_t hash_start;	/* hash start in blocks */
  	sector_t data_blocks;	/* the number of data blocks */
  	sector_t hash_blocks;	/* the number of hash blocks */
  	unsigned char data_dev_block_bits;	/* log2(data blocksize) */
  	unsigned char hash_dev_block_bits;	/* log2(hash blocksize) */
  	unsigned char hash_per_block_bits;	/* log2(hashes in hash block) */
  	unsigned char levels;	/* the number of tree levels */
  	unsigned char version;
  	unsigned digest_size;	/* digest size for the current hash algorithm */

  	unsigned int ahash_reqsize;/* the size of temporary space for crypto */

  	int hash_failed;	/* set to 1 if hash of any block failed */
  	enum verity_mode mode;	/* mode for handling verification errors */
  	unsigned corrupted_errs;/* Number of errors for corrupted blocks */
  
  	struct workqueue_struct *verify_wq;
  
  	/* starting blocks for each tree level. 0 is the lowest level. */
  	sector_t hash_level_block[DM_VERITY_MAX_LEVELS];

  
  	struct dm_verity_fec *fec;	/* forward error correction */

  };
  
  struct dm_verity_io {
  	struct dm_verity *v;
  
  	/* original value of bio->bi_end_io */
  	bio_end_io_t *orig_bi_end_io;
  
  	sector_t block;
  	unsigned n_blocks;
  
  	struct bvec_iter iter;
  
  	struct work_struct work;
  
  	/*
  	 * Three variably-size fields follow this struct:
  	 *

  	 * u8 hash_req[v->ahash_reqsize];

  	 * u8 real_digest[v->digest_size];
  	 * u8 want_digest[v->digest_size];
  	 *

  	 * To access them use: verity_io_hash_req(), verity_io_real_digest()

  	 * and verity_io_want_digest().
  	 */
  };

  struct verity_result {
  	struct completion completion;
  	int err;
  };
  
  static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,

  						     struct dm_verity_io *io)
  {

  	return (struct ahash_request *)(io + 1);

  }
  
  static inline u8 *verity_io_real_digest(struct dm_verity *v,
  					struct dm_verity_io *io)
  {

  	return (u8 *)(io + 1) + v->ahash_reqsize;

  }
  
  static inline u8 *verity_io_want_digest(struct dm_verity *v,
  					struct dm_verity_io *io)
  {

  	return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;

  }

  static inline u8 *verity_io_digest_end(struct dm_verity *v,
  				       struct dm_verity_io *io)
  {
  	return verity_io_want_digest(v, io) + v->digest_size;
  }

  extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
  			       struct bvec_iter *iter,
  			       int (*process)(struct dm_verity *v,
  					      struct dm_verity_io *io,
  					      u8 *data, size_t len));

  extern int verity_hash(struct dm_verity *v, struct ahash_request *req,

  		       const u8 *data, size_t len, u8 *digest);
  
  extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,

  				 sector_t block, u8 *digest, bool *is_zero);

  
  #endif /* DM_VERITY_H */