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

   1/* SPDX-License-Identifier: GPL-2.0-only */
   2/*
   3 * Copyright (C) 2012 Red Hat, Inc.
   4 * Copyright (C) 2015 Google, Inc.
   5 *
   6 * Author: Mikulas Patocka <mpatocka@redhat.com>
   7 *
   8 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   9 */
  10
  11#ifndef DM_VERITY_H
  12#define DM_VERITY_H
  13
  14#include <linux/dm-bufio.h>
  15#include <linux/device-mapper.h>
  16#include <crypto/hash.h>
  17
  18#define DM_VERITY_MAX_LEVELS            63
  19
  20enum verity_mode {
  21        DM_VERITY_MODE_EIO,
  22        DM_VERITY_MODE_LOGGING,
  23        DM_VERITY_MODE_RESTART,
  24        DM_VERITY_MODE_PANIC
  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_ahash *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 int ahash_reqsize;/* 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        unsigned long *validated_blocks; /* bitset blocks validated */
  67
  68        char *signature_key_desc; /* signature keyring reference */
  69};
  70
  71struct dm_verity_io {
  72        struct dm_verity *v;
  73
  74        /* original value of bio->bi_end_io */
  75        bio_end_io_t *orig_bi_end_io;
  76
  77        sector_t block;
  78        unsigned n_blocks;
  79
  80        struct bvec_iter iter;
  81
  82        struct work_struct work;
  83
  84        /*
  85         * Three variably-size fields follow this struct:
  86         *
  87         * u8 hash_req[v->ahash_reqsize];
  88         * u8 real_digest[v->digest_size];
  89         * u8 want_digest[v->digest_size];
  90         *
  91         * To access them use: verity_io_hash_req(), verity_io_real_digest()
  92         * and verity_io_want_digest().
  93         */
  94};
  95
  96static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
  97                                                     struct dm_verity_io *io)
  98{
  99        return (struct ahash_request *)(io + 1);
 100}
 101
 102static inline u8 *verity_io_real_digest(struct dm_verity *v,
 103                                        struct dm_verity_io *io)
 104{
 105        return (u8 *)(io + 1) + v->ahash_reqsize;
 106}
 107
 108static inline u8 *verity_io_want_digest(struct dm_verity *v,
 109                                        struct dm_verity_io *io)
 110{
 111        return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
 112}
 113
 114static inline u8 *verity_io_digest_end(struct dm_verity *v,
 115                                       struct dm_verity_io *io)
 116{
 117        return verity_io_want_digest(v, io) + v->digest_size;
 118}
 119
 120extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 121                               struct bvec_iter *iter,
 122                               int (*process)(struct dm_verity *v,
 123                                              struct dm_verity_io *io,
 124                                              u8 *data, size_t len));
 125
 126extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
 127                       const u8 *data, size_t len, u8 *digest);
 128
 129extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 130                                 sector_t block, u8 *digest, bool *is_zero);
 131
 132#endif /* DM_VERITY_H */
 133