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};
  25
  26enum verity_block_type {
  27        DM_VERITY_BLOCK_TYPE_DATA,
  28        DM_VERITY_BLOCK_TYPE_METADATA
  29};
  30
  31struct dm_verity_fec;
  32
  33struct dm_verity {
  34        struct dm_dev *data_dev;
  35        struct dm_dev *hash_dev;
  36        struct dm_target *ti;
  37        struct dm_bufio_client *bufio;
  38        char *alg_name;
  39        struct crypto_ahash *tfm;
  40        u8 *root_digest;        /* digest of the root block */
  41        u8 *salt;               /* salt: its size is salt_size */
  42        u8 *zero_digest;        /* digest for a zero block */
  43        unsigned salt_size;
  44        sector_t data_start;    /* data offset in 512-byte sectors */
  45        sector_t hash_start;    /* hash start in blocks */
  46        sector_t data_blocks;   /* the number of data blocks */
  47        sector_t hash_blocks;   /* the number of hash blocks */
  48        unsigned char data_dev_block_bits;      /* log2(data blocksize) */
  49        unsigned char hash_dev_block_bits;      /* log2(hash blocksize) */
  50        unsigned char hash_per_block_bits;      /* log2(hashes in hash block) */
  51        unsigned char levels;   /* the number of tree levels */
  52        unsigned char version;
  53        unsigned digest_size;   /* digest size for the current hash algorithm */
  54        unsigned int ahash_reqsize;/* the size of temporary space for crypto */
  55        int hash_failed;        /* set to 1 if hash of any block failed */
  56        enum verity_mode mode;  /* mode for handling verification errors */
  57        unsigned corrupted_errs;/* Number of errors for corrupted blocks */
  58
  59        struct workqueue_struct *verify_wq;
  60
  61        /* starting blocks for each tree level. 0 is the lowest level. */
  62        sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
  63
  64        struct dm_verity_fec *fec;      /* forward error correction */
  65        unsigned long *validated_blocks; /* bitset blocks validated */
  66
  67        char *signature_key_desc; /* signature keyring reference */
  68};
  69
  70struct dm_verity_io {
  71        struct dm_verity *v;
  72
  73        /* original value of bio->bi_end_io */
  74        bio_end_io_t *orig_bi_end_io;
  75
  76        sector_t block;
  77        unsigned n_blocks;
  78
  79        struct bvec_iter iter;
  80
  81        struct work_struct work;
  82
  83        /*
  84         * Three variably-size fields follow this struct:
  85         *
  86         * u8 hash_req[v->ahash_reqsize];
  87         * u8 real_digest[v->digest_size];
  88         * u8 want_digest[v->digest_size];
  89         *
  90         * To access them use: verity_io_hash_req(), verity_io_real_digest()
  91         * and verity_io_want_digest().
  92         */
  93};
  94
  95static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
  96                                                     struct dm_verity_io *io)
  97{
  98        return (struct ahash_request *)(io + 1);
  99}
 100
 101static inline u8 *verity_io_real_digest(struct dm_verity *v,
 102                                        struct dm_verity_io *io)
 103{
 104        return (u8 *)(io + 1) + v->ahash_reqsize;
 105}
 106
 107static inline u8 *verity_io_want_digest(struct dm_verity *v,
 108                                        struct dm_verity_io *io)
 109{
 110        return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
 111}
 112
 113static inline u8 *verity_io_digest_end(struct dm_verity *v,
 114                                       struct dm_verity_io *io)
 115{
 116        return verity_io_want_digest(v, io) + v->digest_size;
 117}
 118
 119extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 120                               struct bvec_iter *iter,
 121                               int (*process)(struct dm_verity *v,
 122                                              struct dm_verity_io *io,
 123                                              u8 *data, size_t len));
 124
 125extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
 126                       const u8 *data, size_t len, u8 *digest);
 127
 128extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 129                                 sector_t block, u8 *digest, bool *is_zero);
 130
 131#endif /* DM_VERITY_H */
 132