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Sami Tolvanenffa39382015-12-03 16:01:51 -05001/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 * Copyright (C) 2015 Google, Inc.
4 *
5 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 *
7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
8 *
9 * This file is released under the GPLv2.
10 */
11
12#ifndef DM_VERITY_H
13#define DM_VERITY_H
14
15#include "dm-bufio.h"
16#include <linux/device-mapper.h>
17#include <crypto/hash.h>
18
19#define DM_VERITY_MAX_LEVELS 63
20
21enum verity_mode {
22 DM_VERITY_MODE_EIO,
23 DM_VERITY_MODE_LOGGING,
24 DM_VERITY_MODE_RESTART
25};
26
27enum verity_block_type {
28 DM_VERITY_BLOCK_TYPE_DATA,
29 DM_VERITY_BLOCK_TYPE_METADATA
30};
31
Sami Tolvanena739ff32015-12-03 14:26:30 +000032struct dm_verity_fec;
33
Sami Tolvanenffa39382015-12-03 16:01:51 -050034struct 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_shash *tfm;
41 u8 *root_digest; /* digest of the root block */
42 u8 *salt; /* salt: its size is salt_size */
Sami Tolvanen0cc37c22015-12-03 14:26:31 +000043 u8 *zero_digest; /* digest for a zero block */
Sami Tolvanenffa39382015-12-03 16:01:51 -050044 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 shash_descsize;/* 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];
Sami Tolvanena739ff32015-12-03 14:26:30 +000064
65 struct dm_verity_fec *fec; /* forward error correction */
Sami Tolvanenffa39382015-12-03 16:01:51 -050066};
67
68struct dm_verity_io {
69 struct dm_verity *v;
70
71 /* original value of bio->bi_end_io */
72 bio_end_io_t *orig_bi_end_io;
73
74 sector_t block;
75 unsigned n_blocks;
76
77 struct bvec_iter iter;
78
79 struct work_struct work;
80
81 /*
82 * Three variably-size fields follow this struct:
83 *
84 * u8 hash_desc[v->shash_descsize];
85 * u8 real_digest[v->digest_size];
86 * u8 want_digest[v->digest_size];
87 *
88 * To access them use: verity_io_hash_desc(), verity_io_real_digest()
89 * and verity_io_want_digest().
90 */
91};
92
93static inline struct shash_desc *verity_io_hash_desc(struct dm_verity *v,
94 struct dm_verity_io *io)
95{
96 return (struct shash_desc *)(io + 1);
97}
98
99static inline u8 *verity_io_real_digest(struct dm_verity *v,
100 struct dm_verity_io *io)
101{
102 return (u8 *)(io + 1) + v->shash_descsize;
103}
104
105static inline u8 *verity_io_want_digest(struct dm_verity *v,
106 struct dm_verity_io *io)
107{
108 return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
109}
110
Sami Tolvanena739ff32015-12-03 14:26:30 +0000111static inline u8 *verity_io_digest_end(struct dm_verity *v,
112 struct dm_verity_io *io)
113{
114 return verity_io_want_digest(v, io) + v->digest_size;
115}
116
Sami Tolvanenbb4d73a2015-12-03 16:30:36 -0500117extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
118 struct bvec_iter *iter,
119 int (*process)(struct dm_verity *v,
120 struct dm_verity_io *io,
121 u8 *data, size_t len));
122
Sami Tolvanenffa39382015-12-03 16:01:51 -0500123extern int verity_hash(struct dm_verity *v, struct shash_desc *desc,
124 const u8 *data, size_t len, u8 *digest);
125
126extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
Sami Tolvanen0cc37c22015-12-03 14:26:31 +0000127 sector_t block, u8 *digest, bool *is_zero);
Sami Tolvanenffa39382015-12-03 16:01:51 -0500128
129#endif /* DM_VERITY_H */