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-bufio.h>
 15#include <linux/device-mapper.h>
 16#include <linux/interrupt.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	DM_VERITY_MODE_PANIC
 26};
 27
 28enum verity_block_type {
 29	DM_VERITY_BLOCK_TYPE_DATA,
 30	DM_VERITY_BLOCK_TYPE_METADATA
 31};
 32
 33struct dm_verity_fec;
 34
 35struct dm_verity {
 36	struct dm_dev *data_dev;
 37	struct dm_dev *hash_dev;
 38	struct dm_target *ti;
 39	struct dm_bufio_client *bufio;
 40	char *alg_name;
 41	struct crypto_ahash *tfm;
 42	u8 *root_digest;	/* digest of the root block */
 43	u8 *salt;		/* salt: its size is salt_size */
 44	u8 *zero_digest;	/* digest for a zero block */
 45	unsigned salt_size;
 46	sector_t data_start;	/* data offset in 512-byte sectors */
 47	sector_t hash_start;	/* hash start in blocks */
 48	sector_t data_blocks;	/* the number of data blocks */
 49	sector_t hash_blocks;	/* the number of hash blocks */
 50	unsigned char data_dev_block_bits;	/* log2(data blocksize) */
 51	unsigned char hash_dev_block_bits;	/* log2(hash blocksize) */
 52	unsigned char hash_per_block_bits;	/* log2(hashes in hash block) */
 53	unsigned char levels;	/* the number of tree levels */
 54	unsigned char version;
 55	bool hash_failed:1;	/* set if hash of any block failed */
 56	bool use_tasklet:1;	/* try to verify in tasklet before work-queue */
 57	unsigned digest_size;	/* digest size for the current hash algorithm */
 58	unsigned int ahash_reqsize;/* the size of temporary space for crypto */
 59	enum verity_mode mode;	/* mode for handling verification errors */
 60	unsigned corrupted_errs;/* Number of errors for corrupted blocks */
 61
 62	struct workqueue_struct *verify_wq;
 63
 64	/* starting blocks for each tree level. 0 is the lowest level. */
 65	sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
 66
 67	struct dm_verity_fec *fec;	/* forward error correction */
 68	unsigned long *validated_blocks; /* bitset blocks validated */
 69
 70	char *signature_key_desc; /* signature keyring reference */
 71};
 72
 73struct dm_verity_io {
 74	struct dm_verity *v;
 75
 76	/* original value of bio->bi_end_io */
 77	bio_end_io_t *orig_bi_end_io;
 78
 79	sector_t block;
 80	unsigned n_blocks;
 81	bool in_tasklet;
 82
 83	struct bvec_iter iter;
 84
 85	struct work_struct work;
 86	struct tasklet_struct tasklet;
 87
 88	/*
 89	 * Three variably-size fields follow this struct:
 90	 *
 91	 * u8 hash_req[v->ahash_reqsize];
 92	 * u8 real_digest[v->digest_size];
 93	 * u8 want_digest[v->digest_size];
 94	 *
 95	 * To access them use: verity_io_hash_req(), verity_io_real_digest()
 96	 * and verity_io_want_digest().
 97	 */
 98};
 99
100static inline struct ahash_request *verity_io_hash_req(struct dm_verity *v,
101						     struct dm_verity_io *io)
102{
103	return (struct ahash_request *)(io + 1);
104}
105
106static inline u8 *verity_io_real_digest(struct dm_verity *v,
107					struct dm_verity_io *io)
108{
109	return (u8 *)(io + 1) + v->ahash_reqsize;
110}
111
112static inline u8 *verity_io_want_digest(struct dm_verity *v,
113					struct dm_verity_io *io)
114{
115	return (u8 *)(io + 1) + v->ahash_reqsize + v->digest_size;
116}
117
118static inline u8 *verity_io_digest_end(struct dm_verity *v,
119				       struct dm_verity_io *io)
120{
121	return verity_io_want_digest(v, io) + 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);
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 */