drivers/md/dm-verity.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2012 Red Hat, Inc.
 * Copyright (C) 2015 Google, Inc.
 *
 * Author: Mikulas Patocka <mpatocka@redhat.com>
 *
 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
 */

#ifndef DM_VERITY_H
#define DM_VERITY_H

#include <linux/dm-io.h>
#include <linux/dm-bufio.h>
#include <linux/device-mapper.h>
#include <linux/interrupt.h>
#include <crypto/hash.h>
#include <linux/notifier.h>

#define DM_VERITY_MAX_LEVELS		63

enum verity_mode {
	DM_VERITY_MODE_EIO,
	DM_VERITY_MODE_LOGGING,
	DM_VERITY_MODE_RESTART,
	DM_VERITY_MODE_PANIC
};

enum verity_block_type {
	DM_VERITY_BLOCK_TYPE_DATA,
	DM_VERITY_BLOCK_TYPE_METADATA
};

struct dm_verity_fec;

struct dm_verity {
	struct dm_dev *data_dev;
	struct dm_dev *hash_dev;
	struct dm_target *ti;
	struct dm_bufio_client *bufio;
	char *alg_name;
	struct crypto_ahash *ahash_tfm; /* either this or shash_tfm is set */
	struct crypto_shash *shash_tfm; /* either this or ahash_tfm is set */
	u8 *root_digest;	/* digest of the root block */
	u8 *salt;		/* salt: its size is salt_size */
	u8 *initial_hashstate;	/* salted initial state, if shash_tfm is set */
	u8 *zero_digest;	/* digest for a zero block */
	unsigned int salt_size;
	sector_t data_start;	/* data offset in 512-byte sectors */
	sector_t hash_start;	/* hash start in blocks */
	sector_t data_blocks;	/* the number of data blocks */
	sector_t hash_blocks;	/* the number of hash blocks */
	unsigned char data_dev_block_bits;	/* log2(data blocksize) */
	unsigned char hash_dev_block_bits;	/* log2(hash blocksize) */
	unsigned char hash_per_block_bits;	/* log2(hashes in hash block) */
	unsigned char levels;	/* the number of tree levels */
	unsigned char version;
	bool hash_failed:1;	/* set if hash of any block failed */
	bool use_tasklet:1;	/* try to verify in tasklet before work-queue */
	unsigned char mb_max_msgs; /* max multibuffer hashing interleaving factor */
	unsigned int digest_size;	/* digest size for the current hash algorithm */
	unsigned int hash_reqsize; /* the size of temporary space for crypto */
	enum verity_mode mode;	/* mode for handling verification errors */
	unsigned int corrupted_errs;/* Number of errors for corrupted blocks */
	int error_behavior;	/* selects error behavior on io errors */

	struct workqueue_struct *verify_wq;

	/* starting blocks for each tree level. 0 is the lowest level. */
	sector_t hash_level_block[DM_VERITY_MAX_LEVELS];

	struct dm_verity_fec *fec;	/* forward error correction */
	unsigned long *validated_blocks; /* bitset blocks validated */

	char *signature_key_desc; /* signature keyring reference */

	struct dm_io_client *io;
	mempool_t recheck_pool;
};

#define DM_VERITY_MAX_PENDING_DATA_BLOCKS	HASH_MAX_MB_MSGS

struct pending_block {
	void *data;
	sector_t blkno;
	u8 want_digest[HASH_MAX_DIGESTSIZE];
	u8 real_digest[HASH_MAX_DIGESTSIZE];
};

struct dm_verity_io {
	struct dm_verity *v;

	/* original value of bio->bi_end_io */
	bio_end_io_t *orig_bi_end_io;

	struct bvec_iter iter;

	sector_t block;
	unsigned int n_blocks;
	bool in_tasklet;

	struct work_struct work;

	u8 tmp_digest[HASH_MAX_DIGESTSIZE];

	/*
	 * This is the queue of data blocks that are pending verification.  We
	 * allow multiple blocks to be queued up in order to support multibuffer
	 * hashing, i.e. interleaving the hashing of multiple messages.  On many
	 * CPUs this improves performance significantly.
	 */
	int num_pending;
	struct pending_block pending_blocks[DM_VERITY_MAX_PENDING_DATA_BLOCKS];

	/*
	 * This struct is followed by a variable-sized hash request of size
	 * v->hash_reqsize, either a struct ahash_request or a struct shash_desc
	 * (depending on whether ahash_tfm or shash_tfm is being used).  To
	 * access it, use verity_io_hash_req().
	 */
};

struct verity_result {
	struct completion completion;
	int err;
};

struct dm_verity_error_state {
	int code;
	int transient;  /* Likely to not happen after a reboot */
	u64 block;
	const char *message;

	sector_t dev_start;
	sector_t dev_len;
	struct block_device *dev;

	sector_t hash_dev_start;
	sector_t hash_dev_len;
	struct block_device *hash_dev;

	/* Final behavior after all notifications are completed. */
	int behavior;
};

/* This enum must be matched to allowed_error_behaviors in dm-verity.c */
enum dm_verity_error_behavior {
	DM_VERITY_ERROR_BEHAVIOR_EIO = 0,
	DM_VERITY_ERROR_BEHAVIOR_PANIC,
	DM_VERITY_ERROR_BEHAVIOR_NONE,
	DM_VERITY_ERROR_BEHAVIOR_NOTIFY
};

int dm_verity_register_error_notifier(struct notifier_block *nb);
int dm_verity_unregister_error_notifier(struct notifier_block *nb);

static inline void *verity_io_hash_req(struct dm_verity *v,
				       struct dm_verity_io *io)
{
	return io + 1;
}

extern int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
		       const u8 *data, size_t len, u8 *digest, bool may_sleep);

extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
				 sector_t block, u8 *digest, bool *is_zero);

extern bool dm_is_verity_target(struct dm_target *ti);
extern int dm_verity_get_mode(struct dm_target *ti);
extern int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest,
				     unsigned int *digest_size);

#endif /* DM_VERITY_H */