LXR linux/drivers/md/dm-verity.h

   1/*
   2 * Copyright (C) 2012 Red Hat, Inc.
   3 * Copyright (C) 2015 Google, Inc.
   4 *
   5 * Author: Mikulas Patocka <mpatocka@redhat.com>
   6 *
   7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   8 *
   9 * This file is released under the GPLv2.
  10 */
  11
  12#ifndef DM_VERITY_H
  13#define DM_VERITY_H
  14
  15#include "dm-bufio.h"
  16#include <linux/device-mapper.h>
  17#include <crypto/hash.h>
  18
  19#define DM_VERITY_MAX_LEVELS            63
  20
  21enum verity_mode {
  22        DM_VERITY_MODE_EIO,
  23        DM_VERITY_MODE_LOGGING,
  24        DM_VERITY_MODE_RESTART
  25};
  26
  27enum verity_block_type {
  28        DM_VERITY_BLOCK_TYPE_DATA,
  29        DM_VERITY_BLOCK_TYPE_METADATA
  30};
  31
  32struct dm_verity_fec;
  33
  34struct dm_verity {
  35        struct dm_dev *data_dev;
  36        struct dm_dev *hash_dev;
  37        struct dm_target *ti;
  38        struct dm_bufio_client *bufio;
  39        char *alg_name;
  40        struct crypto_shash *tfm;
  41        u8 *root_digest;        /* digest of the root block */
  42        u8 *salt;               /* salt: its size is salt_size */
  43        u8 *zero_digest;        /* digest for a zero block */
  44        unsigned salt_size;
  45        sector_t data_start;    /* data offset in 512-byte sectors */
  46        sector_t hash_start;    /* hash start in blocks */
  47        sector_t data_blocks;   /* the number of data blocks */
  48        sector_t hash_blocks;   /* the number of hash blocks */
  49        unsigned char data_dev_block_bits;      /* log2(data blocksize) */
  50        unsigned char hash_dev_block_bits;      /* log2(hash blocksize) */
  51        unsigned char hash_per_block_bits;      /* log2(hashes in hash block) */
  52        unsigned char levels;   /* the number of tree levels */
  53        unsigned char version;
  54        unsigned digest_size;   /* digest size for the current hash algorithm */
  55        unsigned shash_descsize;/* the size of temporary space for crypto */
  56        int hash_failed;        /* set to 1 if hash of any block failed */
  57        enum verity_mode mode;  /* mode for handling verification errors */
  58        unsigned corrupted_errs;/* Number of errors for corrupted blocks */
  59
  60        struct workqueue_struct *verify_wq;
  61
  62        /* starting blocks for each tree level. 0 is the lowest level. */
  63        sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
  64
  65        struct dm_verity_fec *fec;      /* forward error correction */
  66};
  67
  68struct dm_verity_io {
  69        struct dm_verity *v;
  70
  71        /* original value of bio->bi_end_io */
  72        bio_end_io_t *orig_bi_end_io;
  73
  74        sector_t block;
  75        unsigned n_blocks;
  76
  77        struct bvec_iter iter;
  78
  79        struct work_struct work;
  80
  81        /*
  82         * Three variably-size fields follow this struct:
  83         *
  84         * u8 hash_desc[v->shash_descsize];
  85         * u8 real_digest[v->digest_size];
  86         * u8 want_digest[v->digest_size];
  87         *
  88         * To access them use: verity_io_hash_desc(), verity_io_real_digest()
  89         * and verity_io_want_digest().
  90         */
  91};
  92
  93static inline struct shash_desc *verity_io_hash_desc(struct dm_verity *v,
  94                                                     struct dm_verity_io *io)
  95{
  96        return (struct shash_desc *)(io + 1);
  97}
  98
  99static inline u8 *verity_io_real_digest(struct dm_verity *v,
 100                                        struct dm_verity_io *io)
 101{
 102        return (u8 *)(io + 1) + v->shash_descsize;
 103}
 104
 105static inline u8 *verity_io_want_digest(struct dm_verity *v,
 106                                        struct dm_verity_io *io)
 107{
 108        return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
 109}
 110
 111static inline u8 *verity_io_digest_end(struct dm_verity *v,
 112                                       struct dm_verity_io *io)
 113{
 114        return verity_io_want_digest(v, io) + v->digest_size;
 115}
 116
 117extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 118                               struct bvec_iter *iter,
 119                               int (*process)(struct dm_verity *v,
 120                                              struct dm_verity_io *io,
 121                                              u8 *data, size_t len));
 122
 123extern int verity_hash(struct dm_verity *v, struct shash_desc *desc,
 124                       const u8 *data, size_t len, u8 *digest);
 125
 126extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 127                                 sector_t block, u8 *digest, bool *is_zero);
 128
 129#endif /* DM_VERITY_H */
 130