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
  20 enum verity_mode {
  21         DM_VERITY_MODE_EIO,
  22         DM_VERITY_MODE_LOGGING,
  23         DM_VERITY_MODE_RESTART
  24 };
  25
  26 enum verity_block_type {
  27         DM_VERITY_BLOCK_TYPE_DATA,
  28         DM_VERITY_BLOCK_TYPE_METADATA
  29 };
  30
  31 struct dm_verity_fec;
  32
  33 struct 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
  70 struct 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
  95 static 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
 101 static 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
 107 static 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
 113 static 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
 119 extern 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
 125 extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
 126                        const u8 *data, size_t len, u8 *digest);
 127
 128 extern 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 */