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 *ahash_tfm; /* either this or shash_tfm is set */
43 struct crypto_shash *shash_tfm; /* either this or ahash_tfm is set */
44 u8 *root_digest; /* digest of the root block */
45 u8 *salt; /* salt: its size is salt_size */
46 u8 *initial_hashstate; /* salted initial state, if shash_tfm is set */
47 u8 *zero_digest; /* digest for a zero block */
48 #ifdef CONFIG_SECURITY
49 u8 *root_digest_sig; /* signature of the root digest */
50 unsigned int sig_size; /* root digest signature size */
51 #endif /* CONFIG_SECURITY */
52 unsigned int salt_size;
53 sector_t data_start; /* data offset in 512-byte sectors */
54 sector_t hash_start; /* hash start in blocks */
55 sector_t data_blocks; /* the number of data blocks */
56 sector_t hash_blocks; /* the number of hash blocks */
57 unsigned char data_dev_block_bits; /* log2(data blocksize) */
58 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
59 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
60 unsigned char levels; /* the number of tree levels */
61 unsigned char version;
62 bool hash_failed:1; /* set if hash of any block failed */
63 bool use_bh_wq:1; /* try to verify in BH wq before normal work-queue */
64 unsigned char mb_max_msgs; /* max multibuffer hashing interleaving factor */
65 unsigned int digest_size; /* digest size for the current hash algorithm */
66 unsigned int hash_reqsize; /* the size of temporary space for crypto */
67 enum verity_mode mode; /* mode for handling verification errors */
68 enum verity_mode error_mode;/* mode for handling I/O errors */
69 unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
70
71 struct workqueue_struct *verify_wq;
72
73 /* starting blocks for each tree level. 0 is the lowest level. */
74 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
75
76 struct dm_verity_fec *fec; /* forward error correction */
77 unsigned long *validated_blocks; /* bitset blocks validated */
78
79 char *signature_key_desc; /* signature keyring reference */
80
81 struct dm_io_client *io;
82 mempool_t recheck_pool;
83 };
84
85 #define DM_VERITY_MAX_PENDING_DATA_BLOCKS HASH_MAX_MB_MSGS
86
87 struct pending_block {
88 void *data;
89 sector_t blkno;
90 u8 want_digest[HASH_MAX_DIGESTSIZE];
91 u8 real_digest[HASH_MAX_DIGESTSIZE];
92 };
93
94 struct dm_verity_io {
95 struct dm_verity *v;
96
97 /* original value of bio->bi_end_io */
98 bio_end_io_t *orig_bi_end_io;
99
100 struct bvec_iter iter;
101
102 sector_t block;
103 unsigned int n_blocks;
104 bool in_bh;
105 bool had_mismatch;
106
107 struct work_struct work;
108 struct work_struct bh_work;
109
110 u8 tmp_digest[HASH_MAX_DIGESTSIZE];
111
112 /*
113 * This is the queue of data blocks that are pending verification. We
114 * allow multiple blocks to be queued up in order to support multibuffer
115 * hashing, i.e. interleaving the hashing of multiple messages. On many
116 * CPUs this improves performance significantly.
117 */
118 int num_pending;
119 struct pending_block pending_blocks[DM_VERITY_MAX_PENDING_DATA_BLOCKS];
120
121 /*
122 * This struct is followed by a variable-sized hash request of size
123 * v->hash_reqsize, either a struct ahash_request or a struct shash_desc
124 * (depending on whether ahash_tfm or shash_tfm is being used). To
125 * access it, use verity_io_hash_req().
126 */
127 };
128
verity_io_hash_req(struct dm_verity * v,struct dm_verity_io * io)129 static inline void *verity_io_hash_req(struct dm_verity *v,
130 struct dm_verity_io *io)
131 {
132 return io + 1;
133 }
134
135 extern int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
136 const u8 *data, size_t len, u8 *digest, bool may_sleep);
137
138 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
139 sector_t block, u8 *digest, bool *is_zero);
140
141 extern bool dm_is_verity_target(struct dm_target *ti);
142 extern int dm_verity_get_mode(struct dm_target *ti);
143 extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest,
144 unsigned int *digest_size);
145
146 #endif /* DM_VERITY_H */
147