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#include <crypto/sha2.h>
20
21#define DM_VERITY_MAX_LEVELS 63
22
23enum verity_mode {
24 DM_VERITY_MODE_EIO,
25 DM_VERITY_MODE_LOGGING,
26 DM_VERITY_MODE_RESTART,
27 DM_VERITY_MODE_PANIC
28};
29
30enum verity_block_type {
31 DM_VERITY_BLOCK_TYPE_DATA,
32 DM_VERITY_BLOCK_TYPE_METADATA
33};
34
35struct dm_verity_fec;
36
37struct dm_verity {
38 struct dm_dev *data_dev;
39 struct dm_dev *hash_dev;
40 struct dm_target *ti;
41 struct dm_bufio_client *bufio;
42 char *alg_name;
43 struct crypto_shash *shash_tfm;
44 u8 *root_digest; /* digest of the root block */
45 u8 *salt; /* salt: its size is salt_size */
46 union {
47 struct sha256_ctx *sha256; /* for use_sha256_lib=1 */
48 u8 *shash; /* for use_sha256_lib=0 */
49 } initial_hashstate; /* salted initial state, if version >= 1 */
50 u8 *zero_digest; /* digest for a zero block */
51#ifdef CONFIG_SECURITY
52 u8 *root_digest_sig; /* signature of the root digest */
53 unsigned int sig_size; /* root digest signature size */
54#endif /* CONFIG_SECURITY */
55 unsigned int salt_size;
56 sector_t hash_start; /* hash start in blocks */
57 sector_t data_blocks; /* the number of data blocks */
58 sector_t hash_blocks; /* the number of hash blocks */
59 unsigned char data_dev_block_bits; /* log2(data blocksize) */
60 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
61 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
62 unsigned char levels; /* the number of tree levels */
63 unsigned char version;
64 bool hash_failed:1; /* set if hash of any block failed */
65 bool use_bh_wq:1; /* try to verify in BH wq before normal work-queue */
66 bool use_sha256_lib:1; /* use SHA-256 library instead of generic crypto API */
67 bool use_sha256_finup_2x:1; /* use interleaved hashing optimization */
68 unsigned int digest_size; /* digest size for the current hash algorithm */
69 enum verity_mode mode; /* mode for handling verification errors */
70 enum verity_mode error_mode;/* mode for handling I/O errors */
71 unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
72
73 struct workqueue_struct *verify_wq;
74
75 /* starting blocks for each tree level. 0 is the lowest level. */
76 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
77
78 struct dm_verity_fec *fec; /* forward error correction */
79 unsigned long *validated_blocks; /* bitset blocks validated */
80
81 char *signature_key_desc; /* signature keyring reference */
82
83 struct dm_io_client *io;
84 mempool_t recheck_pool;
85};
86
87struct 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
94struct 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. When
114 * the crypto layer supports interleaved hashing, we allow multiple
115 * blocks to be queued up in order to utilize it. This can improve
116 * performance significantly vs. sequential hashing of each block.
117 */
118 int num_pending;
119 struct pending_block pending_blocks[2];
120
121 /*
122 * Temporary space for hashing. Either sha256 or shash is used,
123 * depending on the value of use_sha256_lib. If shash is used,
124 * then this field is variable-length, with total size
125 * sizeof(struct shash_desc) + crypto_shash_descsize(shash_tfm).
126 * For this reason, this field must be the end of the struct.
127 */
128 union {
129 struct sha256_ctx sha256;
130 struct shash_desc shash;
131 } hash_ctx;
132};
133
134extern int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
135 const u8 *data, size_t len, u8 *digest);
136
137extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
138 sector_t block, u8 *digest, bool *is_zero);
139
140extern bool dm_is_verity_target(struct dm_target *ti);
141extern int dm_verity_get_mode(struct dm_target *ti);
142extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest,
143 unsigned int *digest_size);
144
145#endif /* DM_VERITY_H */
146

source code of linux/drivers/md/dm-verity.h