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
 22enum verity_mode {
 23	DM_VERITY_MODE_EIO,
 24	DM_VERITY_MODE_LOGGING,
 25	DM_VERITY_MODE_RESTART,
 26	DM_VERITY_MODE_PANIC
 27};
 28
 29enum verity_block_type {
 30	DM_VERITY_BLOCK_TYPE_DATA,
 31	DM_VERITY_BLOCK_TYPE_METADATA
 32};
 33
 34struct dm_verity_fec;
 35
 36struct 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_bh_wq:1;	/* try to verify in BH wq before normal 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
 77struct 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_bh;
 88
 89	struct work_struct work;
 90	struct work_struct bh_work;
 91
 92	char *recheck_buffer;
 93
 94	/*
 95	 * Three variably-size fields follow this struct:
 96	 *
 97	 * u8 hash_req[v->ahash_reqsize];
 98	 * u8 real_digest[v->digest_size];
 99	 * u8 want_digest[v->digest_size];
100	 *
101	 * To access them use: verity_io_hash_req(), verity_io_real_digest()
102	 * and verity_io_want_digest().
103	 */
104};
105
106static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
107						     struct dm_verity_io *io)
108{
109	return (struct ahash_request *)(io + 1);
110}
111
112static inline u8 *verity_io_real_digest(struct dm_verity *v,
113					struct dm_verity_io *io)
114{
115	return (u8 *)(io + 1) + v->ahash_reqsize;
116}
117
118static inline u8 *verity_io_want_digest(struct dm_verity *v,
119					struct dm_verity_io *io)
120{
121	return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
122}
123
124extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
125			       struct bvec_iter *iter,
126			       int (*process)(struct dm_verity *v,
127					      struct dm_verity_io *io,
128					      u8 *data, size_t len));
129
130extern int verity_hash(struct dm_verity *v, struct ahash_request *req,
131		       const u8 *data, size_t len, u8 *digest, bool may_sleep);
132
133extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
134				 sector_t block, u8 *digest, bool *is_zero);
135
136extern bool dm_is_verity_target(struct dm_target *ti);
137extern int dm_verity_get_mode(struct dm_target *ti);
138extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest,
139				     unsigned int *digest_size);
140
141#endif /* DM_VERITY_H */