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 <linux/interrupt.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         DM_VERITY_MODE_PANIC
  26 };
  27
  28 enum verity_block_type {
  29         DM_VERITY_BLOCK_TYPE_DATA,
  30         DM_VERITY_BLOCK_TYPE_METADATA
  31 };
  32
  33 struct dm_verity_fec;
  34
  35 struct dm_verity {
  36         struct dm_dev *data_dev;
  37         struct dm_dev *hash_dev;
  38         struct dm_target *ti;
  39         struct dm_bufio_client *bufio;
  40         char *alg_name;
  41         struct crypto_ahash *tfm;
  42         u8 *root_digest;        /* digest of the root block */
  43         u8 *salt;               /* salt: its size is salt_size */
  44         u8 *zero_digest;        /* digest for a zero block */
  45         unsigned salt_size;
  46         sector_t data_start;    /* data offset in 512-byte sectors */
  47         sector_t hash_start;    /* hash start in blocks */
  48         sector_t data_blocks;   /* the number of data blocks */
  49         sector_t hash_blocks;   /* the number of hash blocks */
  50         unsigned char data_dev_block_bits;      /* log2(data blocksize) */
  51         unsigned char hash_dev_block_bits;      /* log2(hash blocksize) */
  52         unsigned char hash_per_block_bits;      /* log2(hashes in hash block) */
  53         unsigned char levels;   /* the number of tree levels */
  54         unsigned char version;
  55         bool hash_failed:1;     /* set if hash of any block failed */
  56         bool use_tasklet:1;     /* try to verify in tasklet before work-queue */
  57         unsigned digest_size;   /* digest size for the current hash algorithm */
  58         unsigned int ahash_reqsize;/* the size of temporary space for crypto */
  59         enum verity_mode mode;  /* mode for handling verification errors */
  60         unsigned corrupted_errs;/* Number of errors for corrupted blocks */
  61
  62         struct workqueue_struct *verify_wq;
  63
  64         /* starting blocks for each tree level. 0 is the lowest level. */
  65         sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
  66
  67         struct dm_verity_fec *fec;      /* forward error correction */
  68         unsigned long *validated_blocks; /* bitset blocks validated */
  69
  70         char *signature_key_desc; /* signature keyring reference */
  71 };
  72
  73 struct dm_verity_io {
  74         struct dm_verity *v;
  75
  76         /* original value of bio->bi_end_io */
  77         bio_end_io_t *orig_bi_end_io;
  78
  79         sector_t block;
  80         unsigned n_blocks;
  81         bool in_tasklet;
  82
  83         struct bvec_iter iter;
  84
  85         struct work_struct work;
  86         struct tasklet_struct tasklet;
  87
  88         /*
  89          * Three variably-size fields follow this struct:
  90          *
  91          * u8 hash_req[v->ahash_reqsize];
  92          * u8 real_digest[v->digest_size];
  93          * u8 want_digest[v->digest_size];
  94          *
  95          * To access them use: verity_io_hash_req(), verity_io_real_digest()
  96          * and verity_io_want_digest().
  97          */
  98 };
  99
 100 static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
 101                                                      struct dm_verity_io *io)
 102 {
 103         return (struct ahash_request *)(io + 1);
 104 }
 105
 106 static inline u8 *verity_io_real_digest(struct dm_verity *v,
 107                                         struct dm_verity_io *io)
 108 {
 109         return (u8 *)(io + 1) + v->ahash_reqsize;
 110 }
 111
 112 static inline u8 *verity_io_want_digest(struct dm_verity *v,
 113                                         struct dm_verity_io *io)
 114 {
 115         return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
 116 }
 117
 118 static inline u8 *verity_io_digest_end(struct dm_verity *v,
 119                                        struct dm_verity_io *io)
 120 {
 121         return verity_io_want_digest(v, io) + 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);
 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_root_digest(struct dm_target *ti, u8 **root_digest,
 138                                      unsigned int *digest_size);
 139
 140 #endif /* DM_VERITY_H */