dm-verity.h

  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 */