/* 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 <crypto/sha2.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_shash *shash_tfm;
	u8 *root_digest;	/* digest of the root block */
	u8 *salt;		/* salt: its size is salt_size */
	union {
		struct sha256_ctx *sha256;	/* for use_sha256_lib=1 */
		u8 *shash;			/* for use_sha256_lib=0 */
	} initial_hashstate; /* salted initial state, if version >= 1 */
	u8 *zero_digest;	/* digest for a zero block */
#ifdef CONFIG_SECURITY
	u8 *root_digest_sig;	/* signature of the root digest */
	unsigned int sig_size;	/* root digest signature size */
#endif /* CONFIG_SECURITY */
	unsigned int salt_size;
	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_bh_wq:1;	/* try to verify in BH wq before normal work-queue */
	bool use_sha256_lib:1;	/* use SHA-256 library instead of generic crypto API */
	bool use_sha256_finup_2x:1; /* use interleaved hashing optimization */
	unsigned int digest_size;	/* digest size for the current hash algorithm */
	enum verity_mode mode;	/* mode for handling verification errors */
	enum verity_mode error_mode;/* mode for handling I/O errors */
	unsigned int corrupted_errs;/* Number of errors for corrupted blocks */

	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;
};

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_bh;
	bool had_mismatch;

	struct work_struct work;
	struct work_struct bh_work;

	u8 tmp_digest[HASH_MAX_DIGESTSIZE];

	/*
	 * This is the queue of data blocks that are pending verification.  When
	 * the crypto layer supports interleaved hashing, we allow multiple
	 * blocks to be queued up in order to utilize it.  This can improve
	 * performance significantly vs. sequential hashing of each block.
	 */
	int num_pending;
	struct pending_block pending_blocks[2];

	/*
	 * Temporary space for hashing.  Either sha256 or shash is used,
	 * depending on the value of use_sha256_lib.  If shash is used,
	 * then this field is variable-length, with total size
	 * sizeof(struct shash_desc) + crypto_shash_descsize(shash_tfm).
	 * For this reason, this field must be the end of the struct.
	 */
	union {
		struct sha256_ctx sha256;
		struct shash_desc shash;
	} hash_ctx;
};

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

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 */