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_MAX_LEVELS		63
 20
 21enum verity_mode {
 22	DM_VERITY_MODE_EIO,
 23	DM_VERITY_MODE_LOGGING,
 24	DM_VERITY_MODE_RESTART
 25};
 26
 27enum verity_block_type {
 28	DM_VERITY_BLOCK_TYPE_DATA,
 29	DM_VERITY_BLOCK_TYPE_METADATA
 30};
 31
 32struct dm_verity_fec;
 33
 34struct dm_verity {
 35	struct dm_dev *data_dev;
 36	struct dm_dev *hash_dev;
 37	struct dm_target *ti;
 38	struct dm_bufio_client *bufio;
 39	char *alg_name;
 40	struct crypto_shash *tfm;
 41	u8 *root_digest;	/* digest of the root block */
 42	u8 *salt;		/* salt: its size is salt_size */
 43	u8 *zero_digest;	/* digest for a zero block */
 44	unsigned salt_size;
 45	sector_t data_start;	/* data offset in 512-byte sectors */
 46	sector_t hash_start;	/* hash start in blocks */
 47	sector_t data_blocks;	/* the number of data blocks */
 48	sector_t hash_blocks;	/* the number of hash blocks */
 49	unsigned char data_dev_block_bits;	/* log2(data blocksize) */
 50	unsigned char hash_dev_block_bits;	/* log2(hash blocksize) */
 51	unsigned char hash_per_block_bits;	/* log2(hashes in hash block) */
 52	unsigned char levels;	/* the number of tree levels */
 53	unsigned char version;
 54	unsigned digest_size;	/* digest size for the current hash algorithm */
 55	unsigned shash_descsize;/* the size of temporary space for crypto */
 56	int hash_failed;	/* set to 1 if hash of any block failed */
 57	enum verity_mode mode;	/* mode for handling verification errors */
 58	unsigned corrupted_errs;/* Number of errors for corrupted blocks */
 59
 60	struct workqueue_struct *verify_wq;
 61
 62	/* starting blocks for each tree level. 0 is the lowest level. */
 63	sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
 64
 65	struct dm_verity_fec *fec;	/* forward error correction */
 66};
 67
 68struct dm_verity_io {
 69	struct dm_verity *v;
 70
 71	/* original value of bio->bi_end_io */
 72	bio_end_io_t *orig_bi_end_io;
 73
 74	sector_t block;
 75	unsigned n_blocks;
 76
 77	struct bvec_iter iter;
 78
 79	struct work_struct work;
 80
 81	/*
 82	 * Three variably-size fields follow this struct:
 83	 *
 84	 * u8 hash_desc[v->shash_descsize];
 85	 * u8 real_digest[v->digest_size];
 86	 * u8 want_digest[v->digest_size];
 87	 *
 88	 * To access them use: verity_io_hash_desc(), verity_io_real_digest()
 89	 * and verity_io_want_digest().
 90	 */
 91};
 92
 93static inline struct shash_desc *verity_io_hash_desc(struct dm_verity *v,
 94						     struct dm_verity_io *io)
 95{
 96	return (struct shash_desc *)(io + 1);
 97}
 98
 99static inline u8 *verity_io_real_digest(struct dm_verity *v,
100					struct dm_verity_io *io)
101{
102	return (u8 *)(io + 1) + v->shash_descsize;
103}
104
105static inline u8 *verity_io_want_digest(struct dm_verity *v,
106					struct dm_verity_io *io)
107{
108	return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
109}
110
111static inline u8 *verity_io_digest_end(struct dm_verity *v,
112				       struct dm_verity_io *io)
113{
114	return verity_io_want_digest(v, io) + v->digest_size;
115}
116
117extern int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
118			       struct bvec_iter *iter,
119			       int (*process)(struct dm_verity *v,
120					      struct dm_verity_io *io,
121					      u8 *data, size_t len));
122
123extern int verity_hash(struct dm_verity *v, struct shash_desc *desc,
124		       const u8 *data, size_t len, u8 *digest);
125
126extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
127				 sector_t block, u8 *digest, bool *is_zero);
128
129#endif /* DM_VERITY_H */