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 DM_VERITY_MODE_PANIC
25 };
26
27 enum verity_block_type {
28 DM_VERITY_BLOCK_TYPE_DATA,
29 DM_VERITY_BLOCK_TYPE_METADATA
30 };
31
32 struct dm_verity_fec;
33
34 struct 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_ahash *tfm;
41 u8 *root_digest; /* digest of the root block */
42 u8 *salt; /* salt: its size is salt_size */
43 u8 *zero_digest; /* digest for a zero block */
44 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 int ahash_reqsize;/* 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];
64
65 struct dm_verity_fec *fec; /* forward error correction */
66 unsigned long *validated_blocks; /* bitset blocks validated */
67
68 char *signature_key_desc; /* signature keyring reference */
69 };
70
71 struct dm_verity_io {
72 struct dm_verity *v;
73
74 /* original value of bio->bi_end_io */
75 bio_end_io_t *orig_bi_end_io;
76
77 sector_t block;
78 unsigned n_blocks;
79
80 struct bvec_iter iter;
81
82 struct work_struct work;
83
84 /*
85 * Three variably-size fields follow this struct:
86 *
87 * u8 hash_req[v->ahash_reqsize];
88 * u8 real_digest[v->digest_size];
89 * u8 want_digest[v->digest_size];
90 *
91 * To access them use: verity_io_hash_req(), verity_io_real_digest()
92 * and verity_io_want_digest().
93 */
94 };
95
verity_io_hash_req(struct dm_verity * v,struct dm_verity_io * io)96 static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
97 struct dm_verity_io *io)
98 {
99 return (struct ahash_request *)(io + 1);
100 }
101
verity_io_real_digest(struct dm_verity * v,struct dm_verity_io * io)102 static inline u8 *verity_io_real_digest(struct dm_verity *v,
103 struct dm_verity_io *io)
104 {
105 return (u8 *)(io + 1) + v->ahash_reqsize;
106 }
107
verity_io_want_digest(struct dm_verity * v,struct dm_verity_io * io)108 static inline u8 *verity_io_want_digest(struct dm_verity *v,
109 struct dm_verity_io *io)
110 {
111 return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
112 }
113
verity_io_digest_end(struct dm_verity * v,struct dm_verity_io * io)114 static inline u8 *verity_io_digest_end(struct dm_verity *v,
115 struct dm_verity_io *io)
116 {
117 return verity_io_want_digest(v, io) + v->digest_size;
118 }
119
120 extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
121 struct bvec_iter *iter,
122 int (*process)(struct dm_verity *v,
123 struct dm_verity_io *io,
124 u8 *data, size_t len));
125
126 extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
127 const u8 *data, size_t len, u8 *digest);
128
129 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
130 sector_t block, u8 *digest, bool *is_zero);
131
132 #endif /* DM_VERITY_H */
133