1 /*
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_WAIT_DEV_TIMEOUT_MS (2000)
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 };
27
28 enum verity_block_type {
29 DM_VERITY_BLOCK_TYPE_DATA,
30 DM_VERITY_BLOCK_TYPE_METADATA
31 };
32
33 struct dm_verity_fec;
34
35 struct dm_verity {
36 struct dm_dev *data_dev;
37 struct dm_dev *hash_dev;
38 struct dm_target *ti;
39 struct dm_bufio_client *bufio;
40 char *alg_name;
41 struct crypto_shash *tfm;
42 u8 *root_digest; /* digest of the root block */
43 u8 *salt; /* salt: its size is salt_size */
44 u8 *zero_digest; /* digest for a zero block */
45 unsigned salt_size;
46 sector_t data_start; /* data offset in 512-byte sectors */
47 sector_t hash_start; /* hash start in blocks */
48 sector_t data_blocks; /* the number of data blocks */
49 sector_t hash_blocks; /* the number of hash blocks */
50 unsigned char data_dev_block_bits; /* log2(data blocksize) */
51 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
52 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
53 unsigned char levels; /* the number of tree levels */
54 unsigned char version;
55 unsigned digest_size; /* digest size for the current hash algorithm */
56 unsigned shash_descsize;/* the size of temporary space for crypto */
57 int hash_failed; /* set to 1 if hash of any block failed */
58 enum verity_mode mode; /* mode for handling verification errors */
59 unsigned corrupted_errs;/* Number of errors for corrupted blocks */
60
61 struct workqueue_struct *verify_wq;
62
63 /* starting blocks for each tree level. 0 is the lowest level. */
64 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
65
66 struct dm_verity_fec *fec; /* forward error correction */
67 };
68
69 struct dm_verity_io {
70 struct dm_verity *v;
71
72 /* original values of bio->bi_end_io and bio->bi_private */
73 bio_end_io_t *orig_bi_end_io;
74 void *orig_bi_private;
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_desc[v->shash_descsize];
87 * u8 real_digest[v->digest_size];
88 * u8 want_digest[v->digest_size];
89 *
90 * To access them use: verity_io_hash_desc(), verity_io_real_digest()
91 * and verity_io_want_digest().
92 */
93 };
94
verity_io_hash_desc(struct dm_verity * v,struct dm_verity_io * io)95 static inline struct shash_desc *verity_io_hash_desc(struct dm_verity *v,
96 struct dm_verity_io *io)
97 {
98 return (struct shash_desc *)(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->shash_descsize;
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->shash_descsize + 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 shash_desc *desc,
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 extern void verity_status(struct dm_target *ti, status_type_t type,
132 unsigned status_flags, char *result, unsigned maxlen);
133 extern int verity_ioctl(struct dm_target *ti, unsigned cmd,
134 unsigned long arg);
135 extern int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
136 struct bio_vec *biovec, int max_size);
137 extern int verity_iterate_devices(struct dm_target *ti,
138 iterate_devices_callout_fn fn, void *data);
139 extern void verity_io_hints(struct dm_target *ti, struct queue_limits *limits);
140 extern void verity_dtr(struct dm_target *ti);
141 extern int verity_ctr(struct dm_target *ti, unsigned argc, char **argv);
142 extern int verity_map(struct dm_target *ti, struct bio *bio);
143 #endif /* DM_VERITY_H */
144