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
  21 enum verity_mode {
  22         DM_VERITY_MODE_EIO,
  23         DM_VERITY_MODE_LOGGING,
  24         DM_VERITY_MODE_RESTART
  25 };
  26
  27 enum verity_block_type {
  28         DM_VERITY_BLOCK_TYPE_DATA,
  29         DM_VERITY_BLOCK_TYPE_METADATA
  30 };
  31
  32 struct dm_verity_fec;
  33
  34 struct 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
  68 struct 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
  93 static 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
  99 static 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
 105 static 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
 111 static 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
 117 extern 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
 123 extern int verity_hash(struct dm_verity *v, struct shash_desc *desc,
 124                        const u8 *data, size_t len, u8 *digest);
 125
 126 extern 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 */