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
verity_io_hash_req(struct dm_verity * v,struct dm_verity_io * io)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
verity_io_real_digest(struct dm_verity * v,struct dm_verity_io * io)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
verity_io_want_digest(struct dm_verity * v,struct dm_verity_io * io)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
verity_io_digest_end(struct dm_verity * v,struct dm_verity_io * io)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 */
132
