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_ahash *tfm;
43 u8 *root_digest; /* digest of the root block */
44 u8 *salt; /* salt: its size is salt_size */
45 u8 *zero_digest; /* digest for a zero block */
46 unsigned int salt_size;
47 sector_t data_start; /* data offset in 512-byte sectors */
48 sector_t hash_start; /* hash start in blocks */
49 sector_t data_blocks; /* the number of data blocks */
50 sector_t hash_blocks; /* the number of hash blocks */
51 unsigned char data_dev_block_bits; /* log2(data blocksize) */
52 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
53 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
54 unsigned char levels; /* the number of tree levels */
55 unsigned char version;
56 bool hash_failed:1; /* set if hash of any block failed */
57 bool use_tasklet:1; /* try to verify in tasklet before work-queue */
58 unsigned int digest_size; /* digest size for the current hash algorithm */
59 unsigned int ahash_reqsize;/* the size of temporary space for crypto */
60 enum verity_mode mode; /* mode for handling verification errors */
61 unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
62
63 struct workqueue_struct *verify_wq;
64
65 /* starting blocks for each tree level. 0 is the lowest level. */
66 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
67
68 struct dm_verity_fec *fec; /* forward error correction */
69 unsigned long *validated_blocks; /* bitset blocks validated */
70
71 char *signature_key_desc; /* signature keyring reference */
72
73 struct dm_io_client *io;
74 mempool_t recheck_pool;
75 };
76
77 struct dm_verity_io {
78 struct dm_verity *v;
79
80 /* original value of bio->bi_end_io */
81 bio_end_io_t *orig_bi_end_io;
82
83 struct bvec_iter iter;
84
85 sector_t block;
86 unsigned int n_blocks;
87 bool in_tasklet;
88
89 struct work_struct work;
90
91 char *recheck_buffer;
92
93 /*
94 * Three variably-size fields follow this struct:
95 *
96 * u8 hash_req[v->ahash_reqsize];
97 * u8 real_digest[v->digest_size];
98 * u8 want_digest[v->digest_size];
99 *
100 * To access them use: verity_io_hash_req(), verity_io_real_digest()
101 * and verity_io_want_digest().
102 */
103 };
104
verity_io_hash_req(struct dm_verity * v,struct dm_verity_io * io)105 static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
106 struct dm_verity_io *io)
107 {
108 return (struct ahash_request *)(io + 1);
109 }
110
verity_io_real_digest(struct dm_verity * v,struct dm_verity_io * io)111 static inline u8 *verity_io_real_digest(struct dm_verity *v,
112 struct dm_verity_io *io)
113 {
114 return (u8 *)(io + 1) + v->ahash_reqsize;
115 }
116
verity_io_want_digest(struct dm_verity * v,struct dm_verity_io * io)117 static inline u8 *verity_io_want_digest(struct dm_verity *v,
118 struct dm_verity_io *io)
119 {
120 return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
121 }
122
123 extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
124 struct bvec_iter *iter,
125 int (*process)(struct dm_verity *v,
126 struct dm_verity_io *io,
127 u8 *data, size_t len));
128
129 extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
130 const u8 *data, size_t len, u8 *digest, bool may_sleep);
131
132 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
133 sector_t block, u8 *digest, bool *is_zero);
134
135 extern bool dm_is_verity_target(struct dm_target *ti);
136 extern int dm_verity_get_mode(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 */
141