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-io.h>
  15 #include <linux/dm-bufio.h>
  16 #include <linux/device-mapper.h>
  17 #include <linux/interrupt.h>
  18 #include <crypto/hash.h>
  19
  20 #define DM_VERITY_MAX_LEVELS            63
  21
  22 enum verity_mode {
  23         DM_VERITY_MODE_EIO,
  24         DM_VERITY_MODE_LOGGING,
  25         DM_VERITY_MODE_RESTART,
  26         DM_VERITY_MODE_PANIC
  27 };
  28
  29 enum verity_block_type {
  30         DM_VERITY_BLOCK_TYPE_DATA,
  31         DM_VERITY_BLOCK_TYPE_METADATA
  32 };
  33
  34 struct dm_verity_fec;
  35
  36 struct dm_verity {
  37         struct dm_dev *data_dev;
  38         struct dm_dev *hash_dev;
  39         struct dm_target *ti;
  40         struct dm_bufio_client *bufio;
  41         char *alg_name;
  42         struct crypto_ahash *tfm;
  43         u8 *root_digest;        /* digest of the root block */
  44         u8 *salt;               /* salt: its size is salt_size */
  45         u8 *zero_digest;        /* digest for a zero block */
  46         unsigned int salt_size;
  47         sector_t data_start;    /* data offset in 512-byte sectors */
  48         sector_t hash_start;    /* hash start in blocks */
  49         sector_t data_blocks;   /* the number of data blocks */
  50         sector_t hash_blocks;   /* the number of hash blocks */
  51         unsigned char data_dev_block_bits;      /* log2(data blocksize) */
  52         unsigned char hash_dev_block_bits;      /* log2(hash blocksize) */
  53         unsigned char hash_per_block_bits;      /* log2(hashes in hash block) */
  54         unsigned char levels;   /* the number of tree levels */
  55         unsigned char version;
  56         bool hash_failed:1;     /* set if hash of any block failed */
  57         bool use_bh_wq:1;       /* try to verify in BH wq before normal work-queue */
  58         unsigned int digest_size;       /* digest size for the current hash algorithm */
  59         unsigned int ahash_reqsize;/* the size of temporary space for crypto */
  60         enum verity_mode mode;  /* mode for handling verification errors */
  61         unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
  62
  63         struct workqueue_struct *verify_wq;
  64
  65         /* starting blocks for each tree level. 0 is the lowest level. */
  66         sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
  67
  68         struct dm_verity_fec *fec;      /* forward error correction */
  69         unsigned long *validated_blocks; /* bitset blocks validated */
  70
  71         char *signature_key_desc; /* signature keyring reference */
  72
  73         struct dm_io_client *io;
  74         mempool_t recheck_pool;
  75 };
  76
  77 struct dm_verity_io {
  78         struct dm_verity *v;
  79
  80         /* original value of bio->bi_end_io */
  81         bio_end_io_t *orig_bi_end_io;
  82
  83         struct bvec_iter iter;
  84
  85         sector_t block;
  86         unsigned int n_blocks;
  87         bool in_bh;
  88
  89         struct work_struct work;
  90         struct work_struct bh_work;
  91
  92         char *recheck_buffer;
  93
  94         /*
  95          * Three variably-size fields follow this struct:
  96          *
  97          * u8 hash_req[v->ahash_reqsize];
  98          * u8 real_digest[v->digest_size];
  99          * u8 want_digest[v->digest_size];
 100          *
 101          * To access them use: verity_io_hash_req(), verity_io_real_digest()
 102          * and verity_io_want_digest().
 103          */
 104 };
 105
 106 static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
 107                                                      struct dm_verity_io *io)
 108 {
 109         return (struct ahash_request *)(io + 1);
 110 }
 111
 112 static inline u8 *verity_io_real_digest(struct dm_verity *v,
 113                                         struct dm_verity_io *io)
 114 {
 115         return (u8 *)(io + 1) + v->ahash_reqsize;
 116 }
 117
 118 static inline u8 *verity_io_want_digest(struct dm_verity *v,
 119                                         struct dm_verity_io *io)
 120 {
 121         return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
 122 }
 123
 124 extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 125                                struct bvec_iter *iter,
 126                                int (*process)(struct dm_verity *v,
 127                                               struct dm_verity_io *io,
 128                                               u8 *data, size_t len));
 129
 130 extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
 131                        const u8 *data, size_t len, u8 *digest, bool may_sleep);
 132
 133 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 134                                  sector_t block, u8 *digest, bool *is_zero);
 135
 136 extern bool dm_is_verity_target(struct dm_target *ti);
 137 extern int dm_verity_get_mode(struct dm_target *ti);
 138 extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest,
 139                                      unsigned int *digest_size);
 140
 141 #endif /* DM_VERITY_H */