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_shash *shash_tfm;
43 u8 *root_digest; /* digest of the root block */
44 u8 *salt; /* salt: its size is salt_size */
45 u8 *initial_hashstate; /* salted initial state, if version >= 1 */
46 u8 *zero_digest; /* digest for a zero block */
47 #ifdef CONFIG_SECURITY
48 u8 *root_digest_sig; /* signature of the root digest */
49 unsigned int sig_size; /* root digest signature size */
50 #endif /* CONFIG_SECURITY */
51 unsigned int salt_size;
52 sector_t hash_start; /* hash start in blocks */
53 sector_t data_blocks; /* the number of data blocks */
54 sector_t hash_blocks; /* the number of hash blocks */
55 unsigned char data_dev_block_bits; /* log2(data blocksize) */
56 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
57 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
58 unsigned char levels; /* the number of tree levels */
59 unsigned char version;
60 bool hash_failed:1; /* set if hash of any block failed */
61 bool use_bh_wq:1; /* try to verify in BH wq before normal work-queue */
62 unsigned int digest_size; /* digest size for the current hash algorithm */
63 enum verity_mode mode; /* mode for handling verification errors */
64 enum verity_mode error_mode;/* mode for handling I/O errors */
65 unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
66
67 struct workqueue_struct *verify_wq;
68
69 /* starting blocks for each tree level. 0 is the lowest level. */
70 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
71
72 struct dm_verity_fec *fec; /* forward error correction */
73 unsigned long *validated_blocks; /* bitset blocks validated */
74
75 char *signature_key_desc; /* signature keyring reference */
76
77 struct dm_io_client *io;
78 mempool_t recheck_pool;
79 };
80
81 struct dm_verity_io {
82 struct dm_verity *v;
83
84 /* original value of bio->bi_end_io */
85 bio_end_io_t *orig_bi_end_io;
86
87 struct bvec_iter iter;
88
89 sector_t block;
90 unsigned int n_blocks;
91 bool in_bh;
92 bool had_mismatch;
93
94 struct work_struct work;
95 struct work_struct bh_work;
96
97 u8 real_digest[HASH_MAX_DIGESTSIZE];
98 u8 want_digest[HASH_MAX_DIGESTSIZE];
99
100 /*
101 * Temporary space for hashing. This is variable-length and must be at
102 * the end of the struct. struct shash_desc is just the fixed part;
103 * it's followed by a context of size crypto_shash_descsize(shash_tfm).
104 */
105 struct shash_desc hash_desc;
106 };
107
verity_io_real_digest(struct dm_verity * v,struct dm_verity_io * io)108 static inline u8 *verity_io_real_digest(struct dm_verity *v,
109 struct dm_verity_io *io)
110 {
111 return io->real_digest;
112 }
113
verity_io_want_digest(struct dm_verity * v,struct dm_verity_io * io)114 static inline u8 *verity_io_want_digest(struct dm_verity *v,
115 struct dm_verity_io *io)
116 {
117 return io->want_digest;
118 }
119
120 extern int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
121 const u8 *data, size_t len, u8 *digest);
122
123 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
124 sector_t block, u8 *digest, bool *is_zero);
125
126 extern bool dm_is_verity_target(struct dm_target *ti);
127 extern int dm_verity_get_mode(struct dm_target *ti);
128 extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest,
129 unsigned int *digest_size);
130
131 #endif /* DM_VERITY_H */
132