/* 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;

#ifdef CONFIG_DM_VERITY_FEC
        struct dm_verity_fec_io *fec_io;
#endif

        struct work_struct 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 */