text: /*
   * Copyright (C) 2012 Red Hat, Inc.
   *
   * Author: Mikulas Patocka <mpatocka@redhat.com>
   *
   * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   *
   * This file is released under the GPLv2.
   *
   * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
   * default prefetch value. Data are read in "prefetch_cluster" chunks from the
   * hash device. Setting this greatly improves performance when data and hash
   * are on the same disk on different partitions on devices with poor random
   * access behavior.
   */
  
  #include "dm-verity.h"
  #include "dm-verity-fec.h"
  #include "dm-verity-debug.h"
  
  #include <linux/module.h>
  #include <linux/reboot.h>
  #include <linux/vmalloc.h>
  
  #include <linux/ctype.h>
  
  #define DM_MSG_PREFIX			"verity"
  
  #define DM_VERITY_ENV_LENGTH		42
  #define DM_VERITY_ENV_VAR_NAME		"DM_VERITY_ERR_BLOCK_NR"
  
  #define DM_VERITY_DEFAULT_PREFETCH_SIZE	262144
  
  #define DM_VERITY_MAX_CORRUPTED_ERRS	100
  
  #define DM_VERITY_OPT_LOGGING		"ignore_corruption"
  #define DM_VERITY_OPT_RESTART		"restart_on_corruption"
  #define DM_VERITY_OPT_IGN_ZEROES	"ignore_zero_blocks"
  #define DM_VERITY_OPT_AT_MOST_ONCE	"check_at_most_once"
  
  #define DM_VERITY_OPTS_MAX		(2 + DM_VERITY_OPTS_FEC)
  
  static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  
  module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
  
  extern int ignore_fs_panic;
  
  struct dm_verity_prefetch_work {
  	struct work_struct work;
  	struct dm_verity *v;
  	sector_t block;
  	unsigned n_blocks;
  };
  
  /*
   * Auxiliary structure appended to each dm-bufio buffer. If the value
   * hash_verified is nonzero, hash of the block has been verified.
   *
   * The variable hash_verified is set to 0 when allocating the buffer, then
   * it can be changed to 1 and it is never reset to 0 again.
   *
   * There is no lock around this value, a race condition can at worst cause
   * that multiple processes verify the hash of the same buffer simultaneously
   * and write 1 to hash_verified simultaneously.
   * This condition is harmless, so we don't need locking.
   */
  struct buffer_aux {
  	int hash_verified;
  };
  
  /*
   * Initialize struct buffer_aux for a freshly created buffer.
   */
  static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  {
  	struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  
  	aux->hash_verified = 0;
  }
  
  /*
   * Translate input sector number to the sector number on the target device.
   */
  static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  {
  	return v->data_start + dm_target_offset(v->ti, bi_sector);
  }
  
  /*
   * Return hash position of a specified block at a specified tree level
   * (0 is the lowest level).
   * The lowest "hash_per_block_bits"-bits of the result denote hash position
   * inside a hash block. The remaining bits denote location of the hash block.
   */
  static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
  					 int level)
  {
  	return block >> (level * v->hash_per_block_bits);
  }
  
  /*
   * Wrapper for crypto_shash_init, which handles verity salting.
   */
  static int verity_hash_init(struct dm_verity *v, struct shash_desc *desc)
  {
  	int r;
  
  	desc->tfm = v->tfm;
  	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
  
  	r = crypto_shash_init(desc);
  
  	if (unlikely(r < 0)) {
  		DMERR("crypto_shash_init failed: %d", r);
  		return r;
  	}
  
  	if (likely(v->version >= 1)) {
  		r = crypto_shash_update(desc, v->salt, v->salt_size);
  
  		if (unlikely(r < 0)) {
  			DMERR("crypto_shash_update failed: %d", r);
  			return r;
  		}
  	}
  
  	return 0;
  }
  
  static int verity_hash_update(struct dm_verity *v, struct shash_desc *desc,
  			      const u8 *data, size_t len)
  {
  	int r = crypto_shash_update(desc, data, len);
  
  	if (unlikely(r < 0))
  		DMERR("crypto_shash_update failed: %d", r);
  
  	return r;
  }
  
  static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc,
  			     u8 *digest)
  {
  	int r;
  
  	if (unlikely(!v->version)) {
  		r = crypto_shash_update(desc, v->salt, v->salt_size);
  
  		if (r < 0) {
  			DMERR("crypto_shash_update failed: %d", r);
  			return r;
  		}
  	}
  
  	r = crypto_shash_final(desc, digest);
  
  	if (unlikely(r < 0))
  		DMERR("crypto_shash_final failed: %d", r);
  
  	return r;
  }
  
  int verity_hash(struct dm_verity *v, struct shash_desc *desc,
  		const u8 *data, size_t len, u8 *digest)
  {
  	int r;
  
  	r = verity_hash_init(v, desc);
  	if (unlikely(r < 0))
  		return r;
  
  	r = verity_hash_update(v, desc, data, len);
  	if (unlikely(r < 0))
  		return r;
  
  	return verity_hash_final(v, desc, digest);
  }
  
  static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
  				 sector_t *hash_block, unsigned *offset)
  {
  	sector_t position = verity_position_at_level(v, block, level);
  	unsigned idx;
  
  	*hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
  
  	if (!offset)
  		return;
  
  	idx = position & ((1 << v->hash_per_block_bits) - 1);
  	if (!v->version)
  		*offset = idx * v->digest_size;
  	else
  		*offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
  }
  
  /*
   * Handle verification errors.
   */
  #ifndef SEC_HEX_DEBUG
  static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
  			     unsigned long long block)
  {
  	char verity_env[DM_VERITY_ENV_LENGTH];
  	char *envp[] = { verity_env, NULL };
  	const char *type_str = "";
  	struct mapped_device *md = dm_table_get_md(v->ti->table);
  
  	/* Corruption should be visible in device status in all modes */
  	v->hash_failed = 1;
  
  	if (ignore_fs_panic) {
  		DMERR("%s: Don't trigger a panic during cleanup for shutdown. Skipping %s",
  				v->data_dev->name, __func__);
  		return 0;
  	}
  
  	if (block == 0) {
  		DMERR("%s: block 0 is superblock. Skipping %s", v->data_dev->name, __func__);
  		return 0;
  	}
  
  	if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
  		goto out;
  
  	v->corrupted_errs++;
  
  	switch (type) {
  	case DM_VERITY_BLOCK_TYPE_DATA:
  		type_str = "data";
  		break;
  	case DM_VERITY_BLOCK_TYPE_METADATA:
  		type_str = "metadata";
  		break;
  	default:
  		BUG();
  	}
  
  	DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
  		block);
  
  	if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
  		DMERR("%s: reached maximum errors", v->data_dev->name);
  
  	snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
  		DM_VERITY_ENV_VAR_NAME, type, block);
  
  	kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
  
  out:
  	if (v->mode == DM_VERITY_MODE_LOGGING)
  		return 0;
  
  	if (v->mode == DM_VERITY_MODE_RESTART)
  		kernel_restart("dm-verity device corrupted");
  
  	return 1;
  }
  #endif
  /*
   * Verify hash of a metadata block pertaining to the specified data block
   * ("block" argument) at a specified level ("level" argument).
   *
   * On successful return, verity_io_want_digest(v, io) contains the hash value
   * for a lower tree level or for the data block (if we're at the lowest level).
   *
   * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
   * If "skip_unverified" is false, unverified buffer is hashed and verified
   * against current value of verity_io_want_digest(v, io).
   */
  static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
  			       sector_t block, int level, bool skip_unverified,
  			       u8 *want_digest)
  {
  	struct dm_buffer *buf;
  	struct buffer_aux *aux;
  	u8 *data;
  	int r;
  	sector_t hash_block;
  	unsigned offset;
  
  	verity_hash_at_level(v, block, level, &hash_block, &offset);
  
  	data = dm_bufio_read(v->bufio, hash_block, &buf);
  	if (IS_ERR(data))
  		return PTR_ERR(data);
  
  	aux = dm_bufio_get_aux_data(buf);
  
  	if (!aux->hash_verified) {
  		if (skip_unverified) {
  			r = 1;
  			goto release_ret_r;
  		}
  
  		r = verity_hash(v, verity_io_hash_desc(v, io),
  				data, 1 << v->hash_dev_block_bits,
  				verity_io_real_digest(v, io));
  		if (unlikely(r < 0))
  			goto release_ret_r;
  
  		if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
  				  v->digest_size) == 0))
  			aux->hash_verified = 1;
  		else if (verity_fec_decode(v, io,
  					   DM_VERITY_BLOCK_TYPE_METADATA,
  					   hash_block, data, NULL) == 0){
  #ifdef SEC_HEX_DEBUG
  			add_fec_correct_blks();
  			add_fc_blks_entry(hash_block,v->data_dev->name);
  #endif
  			aux->hash_verified = 1;
  		}
  #ifdef SEC_HEX_DEBUG
  		else if (verity_handle_err_hex_debug(v,
  					   DM_VERITY_BLOCK_TYPE_METADATA,
  					   hash_block, io, NULL)) {
  			add_corrupted_blks();
  #else
  		else if (verity_handle_err(v,
  					   DM_VERITY_BLOCK_TYPE_METADATA,
  					   hash_block)) {
  #endif
  				r = -EIO;
  			goto release_ret_r;
  		}
  	}
  
  	data += offset;
  	memcpy(want_digest, data, v->digest_size);
  	r = 0;
  
  release_ret_r:
  	dm_bufio_release(buf);
  	return r;
  }
  
  /*
   * Find a hash for a given block, write it to digest and verify the integrity
   * of the hash tree if necessary.
   */
  int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
  			  sector_t block, u8 *digest, bool *is_zero)
  {
  	int r = 0, i;
  
  	if (likely(v->levels)) {
  		/*
  		 * First, we try to get the requested hash for
  		 * the current block. If the hash block itself is
  		 * verified, zero is returned. If it isn't, this
  		 * function returns 1 and we fall back to whole
  		 * chain verification.
  		 */
  		r = verity_verify_level(v, io, block, 0, true, digest);
  		if (likely(r <= 0))
  			goto out;
  	}
  
  	memcpy(digest, v->root_digest, v->digest_size);
  
  	for (i = v->levels - 1; i >= 0; i--) {
  		r = verity_verify_level(v, io, block, i, false, digest);
  		if (unlikely(r))
  			goto out;
  	}
  out:
  	if (!r && v->zero_digest)
  		*is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
  	else
  		*is_zero = false;
  
  	return r;
  }
  
  /*
   * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
   * starting from iter.
   */
  int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
  			struct bvec_iter *iter,
  			int (*process)(struct dm_verity *v,
  				       struct dm_verity_io *io, u8 *data,
  				       size_t len))
  {
  	unsigned todo = 1 << v->data_dev_block_bits;
  	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
  
  	do {
  		int r;
  		u8 *page;
  		unsigned len;
  		struct bio_vec bv = bio_iter_iovec(bio, *iter);
  
  		page = kmap_atomic(bv.bv_page);
  		len = bv.bv_len;
  
  		if (likely(len >= todo))
  			len = todo;
  
  		r = process(v, io, page + bv.bv_offset, len);
  		kunmap_atomic(page);
  
  		if (r < 0)
  			return r;
  
  		bio_advance_iter(bio, iter, len);
  		todo -= len;
  	} while (todo);
  
  	return 0;
  }
  
  static int verity_bv_hash_update(struct dm_verity *v, struct dm_verity_io *io,
  				 u8 *data, size_t len)
  {
  	return verity_hash_update(v, verity_io_hash_desc(v, io), data, len);
  }
  
  static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
  			  u8 *data, size_t len)
  {
  	memset(data, 0, len);
  	return 0;
  }
  
  /*
   * Moves the bio iter one data block forward.
   */
  static inline void verity_bv_skip_block(struct dm_verity *v,
  					struct dm_verity_io *io,
  					struct bvec_iter *iter)
  {
  	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
  
  	bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
  }
  
  /*
   * Verify one "dm_verity_io" structure.
   */
  static int verity_verify_io(struct dm_verity_io *io)
  {
  	bool is_zero;
  	struct dm_verity *v = io->v;
  	struct bvec_iter start;
  	unsigned b;
  
  	for (b = 0; b < io->n_blocks; b++) {
  		int r;
  		sector_t cur_block = io->block + b;
  		struct shash_desc *desc = verity_io_hash_desc(v, io);
  
  		if (v->validated_blocks &&
  		    likely(test_bit(cur_block, v->validated_blocks))) {
  			verity_bv_skip_block(v, io, &io->iter);
  #ifdef SEC_HEX_DEBUG
  			add_skipped_blks();
  #endif
  			continue;
  		}
  
  		r = verity_hash_for_block(v, io, cur_block,
  					  verity_io_want_digest(v, io),
  					  &is_zero);
  		if (unlikely(r < 0))
  			return r;
  
  		if (is_zero) {
  			/*
  			 * If we expect a zero block, don't validate, just
  			 * return zeros.
  			 */
  			r = verity_for_bv_block(v, io, &io->iter,
  						verity_bv_zero);
  			if (unlikely(r < 0))
  				return r;
  
  			continue;
  		}
  
  		r = verity_hash_init(v, desc);
  		if (unlikely(r < 0))
  			return r;
  
  		start = io->iter;
  		r = verity_for_bv_block(v, io, &io->iter, verity_bv_hash_update);
  		if (unlikely(r < 0))
  			return r;
  
  		r = verity_hash_final(v, desc, verity_io_real_digest(v, io));
  		if (unlikely(r < 0))
  			return r;
  
  		if (likely(memcmp(verity_io_real_digest(v, io),
  				  verity_io_want_digest(v, io), v->digest_size) == 0)) {
  			if (v->validated_blocks)
  				set_bit(cur_block, v->validated_blocks);
  #ifdef DMV_ALTA
  			set_bit(cur_block, (volatile unsigned long *)io->v->verity_bitmap);
  #endif
  			continue;
  		}
  		else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
  					   cur_block, NULL, &start) == 0){
  #ifdef SEC_HEX_DEBUG
  			add_fec_correct_blks();
  			add_fc_blks_entry(cur_block,v->data_dev->name);
  #endif
  			continue;
  		}
  #ifdef SEC_HEX_DEBUG
  			else if (verity_handle_err_hex_debug(v, DM_VERITY_BLOCK_TYPE_DATA,
  						cur_block, io , &start)) 
  #else
  			else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
  						cur_block)) 
  #endif
  			return -EIO;
  	}
  
  	return 0;
  }
  
  /*
   * End one "io" structure with a given error.
   */
  static void verity_finish_io(struct dm_verity_io *io, int error)
  {
  	struct dm_verity *v = io->v;
  	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
  
  	bio->bi_end_io = io->orig_bi_end_io;
  	bio->bi_private = io->orig_bi_private;
  
  	verity_fec_finish_io(io);
  
  	bio_endio_nodec(bio, error);
  }
  
  static void verity_work(struct work_struct *w)
  {
  	struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
  
  	verity_finish_io(io, verity_verify_io(io));
  }
  
  static void verity_end_io(struct bio *bio, int error)
  {
  	struct dm_verity_io *io = bio->bi_private;
  
  	if (error && !verity_fec_is_enabled(io->v)) {
  		verity_finish_io(io, error);
  		return;
  	}
  
  	INIT_WORK(&io->work, verity_work);
  	queue_work(io->v->verify_wq, &io->work);
  }
  
  /*
   * Prefetch buffers for the specified io.
   * The root buffer is not prefetched, it is assumed that it will be cached
   * all the time.
   */
  static void verity_prefetch_io(struct work_struct *work)
  {
  	struct dm_verity_prefetch_work *pw =
  		container_of(work, struct dm_verity_prefetch_work, work);
  	struct dm_verity *v = pw->v;
  	int i;
  
  	for (i = v->levels - 2; i >= 0; i--) {
  		sector_t hash_block_start;
  		sector_t hash_block_end;
  		verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
  		verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
  		if (!i) {
  			unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
  
  			cluster >>= v->data_dev_block_bits;
  			if (unlikely(!cluster))
  				goto no_prefetch_cluster;
  
  			if (unlikely(cluster & (cluster - 1)))
  				cluster = 1 << __fls(cluster);
  
  			hash_block_start &= ~(sector_t)(cluster - 1);
  			hash_block_end |= cluster - 1;
  			if (unlikely(hash_block_end >= v->hash_blocks))
  				hash_block_end = v->hash_blocks - 1;
  		}
  no_prefetch_cluster:
  		dm_bufio_prefetch(v->bufio, hash_block_start,
  				  hash_block_end - hash_block_start + 1);
  	}
  
  	kfree(pw);
  }
  
  static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
  {
  	struct dm_verity_prefetch_work *pw;
  
  	pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
  		GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
  
  	if (!pw)
  		return;
  
  	INIT_WORK(&pw->work, verity_prefetch_io);
  	pw->v = v;
  	pw->block = io->block;
  	pw->n_blocks = io->n_blocks;
  	queue_work(v->verify_wq, &pw->work);
  }
  
  /*
   * Bio map function. It allocates dm_verity_io structure and bio vector and
   * fills them. Then it issues prefetches and the I/O.
   */
  int verity_map(struct dm_target *ti, struct bio *bio)
  {
  	struct dm_verity *v = ti->private;
  	struct dm_verity_io *io;
  #ifdef DMV_ALTA
  	bool skip = true;
  	sector_t bitpos, nblks;
  #endif
  
  	bio->bi_bdev = v->data_dev->bdev;
  	bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
  
  	if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
  	    ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
  		DMERR_LIMIT("unaligned io");
  		return -EIO;
  	}
  
  	if (bio_end_sector(bio) >>
  	    (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
  		DMERR_LIMIT("io out of range");
  		return -EIO;
  	}
  
  	if (bio_data_dir(bio) == WRITE)
  		return -EIO;
  
  #ifdef DMV_ALTA
  	bitpos = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
  	nblks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
  
  	while (nblks) {
  		if (!test_bit(bitpos, (const volatile unsigned long *)v->verity_bitmap)) {
  			skip = false;
  			break;
  		}
  		bitpos++;
  		nblks--;
  	}
  
  	if (skip == true) {
  		goto skip_verity;
  	}
  #endif
  
  	io = dm_per_bio_data(bio, ti->per_bio_data_size);
  	io->v = v;
  	io->orig_bi_end_io = bio->bi_end_io;
  	io->orig_bi_private = bio->bi_private;
  	io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
  	io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
  	
  #ifdef SEC_HEX_DEBUG
      add_total_blks(io->n_blocks);
  
      if (get_total_blks() - get_prev_total_blks() > 0x4000){
          set_prev_total_blks(get_total_blks());
          print_blks_cnt(v->data_dev->name);
      }
  #endif
  
  	bio->bi_end_io = verity_end_io;
  	bio->bi_private = io;
  	io->iter = bio->bi_iter;
  
  	verity_fec_init_io(io);
  
  	verity_submit_prefetch(v, io);
  
  #ifdef DMV_ALTA
  skip_verity:
  #endif
  	generic_make_request(bio);
  
  	return DM_MAPIO_SUBMITTED;
  }
  EXPORT_SYMBOL_GPL(verity_map);
  
  /*
   * Status: V (valid) or C (corruption found)
   */
  void verity_status(struct dm_target *ti, status_type_t type,
  			  unsigned status_flags, char *result, unsigned maxlen)
  {
  	struct dm_verity *v = ti->private;
  	unsigned args = 0;
  	unsigned sz = 0;
  	unsigned x;
  
  	switch (type) {
  	case STATUSTYPE_INFO:
  		DMEMIT("%c", v->hash_failed ? 'C' : 'V');
  		break;
  	case STATUSTYPE_TABLE:
  		DMEMIT("%u %s %s %u %u %llu %llu %s ",
  			v->version,
  			v->data_dev->name,
  			v->hash_dev->name,
  			1 << v->data_dev_block_bits,
  			1 << v->hash_dev_block_bits,
  			(unsigned long long)v->data_blocks,
  			(unsigned long long)v->hash_start,
  			v->alg_name
  			);
  		for (x = 0; x < v->digest_size; x++)
  			DMEMIT("%02x", v->root_digest[x]);
  		DMEMIT(" ");
  		if (!v->salt_size)
  			DMEMIT("-");
  		else
  			for (x = 0; x < v->salt_size; x++)
  				DMEMIT("%02x", v->salt[x]);
  		if (v->mode != DM_VERITY_MODE_EIO)
  			args++;
  		if (verity_fec_is_enabled(v))
  			args += DM_VERITY_OPTS_FEC;
  		if (v->zero_digest)
  			args++;
  		if (v->validated_blocks)
  			args++;
  		if (!args)
  			return;
  		DMEMIT(" %u", args);
  		if (v->mode != DM_VERITY_MODE_EIO) {
  			DMEMIT(" ");
  			switch (v->mode) {
  			case DM_VERITY_MODE_LOGGING:
  				DMEMIT(DM_VERITY_OPT_LOGGING);
  				break;
  			case DM_VERITY_MODE_RESTART:
  				DMEMIT(DM_VERITY_OPT_RESTART);
  				break;
  			default:
  				BUG();
  			}
  		}
  		if (v->zero_digest)
  			DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
  		if (v->validated_blocks)
  			DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
  		sz = verity_fec_status_table(v, sz, result, maxlen);
  		break;
  	}
  }
  EXPORT_SYMBOL_GPL(verity_status);
  
  int verity_ioctl(struct dm_target *ti, unsigned cmd,
  			unsigned long arg)
  {
  	struct dm_verity *v = ti->private;
  	int r = 0;
  
  	if (v->data_start ||
  	    ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
  		r = scsi_verify_blk_ioctl(NULL, cmd);
  
  	return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
  				     cmd, arg);
  }
  EXPORT_SYMBOL_GPL(verity_ioctl);
  
  int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
  			struct bio_vec *biovec, int max_size)
  {
  	struct dm_verity *v = ti->private;
  	struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
  
  	if (!q->merge_bvec_fn)
  		return max_size;
  
  	bvm->bi_bdev = v->data_dev->bdev;
  	bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
  
  	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
  }
  EXPORT_SYMBOL_GPL(verity_merge);
  
  int verity_iterate_devices(struct dm_target *ti,
  				  iterate_devices_callout_fn fn, void *data)
  {
  	struct dm_verity *v = ti->private;
  
  	return fn(ti, v->data_dev, v->data_start, ti->len, data);
  }
  EXPORT_SYMBOL_GPL(verity_iterate_devices);
  
  void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
  {
  	struct dm_verity *v = ti->private;
  
  	if (limits->logical_block_size < 1 << v->data_dev_block_bits)
  		limits->logical_block_size = 1 << v->data_dev_block_bits;
  
  	if (limits->physical_block_size < 1 << v->data_dev_block_bits)
  		limits->physical_block_size = 1 << v->data_dev_block_bits;
  
  	blk_limits_io_min(limits, limits->logical_block_size);
  }
  EXPORT_SYMBOL_GPL(verity_io_hints);
  
  void verity_dtr(struct dm_target *ti)
  {
  	struct dm_verity *v = ti->private;
  #ifdef DMV_ALTA
  	if (v->verity_bitmap) {
  		kfree(v->verity_bitmap);
  	}
  #endif
  
  	if (v->verify_wq)
  		destroy_workqueue(v->verify_wq);
  
  	if (v->bufio)
  		dm_bufio_client_destroy(v->bufio);
  
  	vfree(v->validated_blocks);
  	kfree(v->salt);
  	kfree(v->root_digest);
  	kfree(v->zero_digest);
  
  	if (v->tfm)
  		crypto_free_shash(v->tfm);
  
  	kfree(v->alg_name);
  
  	if (v->hash_dev)
  		dm_put_device(ti, v->hash_dev);
  
  	if (v->data_dev)
  		dm_put_device(ti, v->data_dev);
  
  	verity_fec_dtr(v);
  
  	kfree(v);
  }
  EXPORT_SYMBOL_GPL(verity_dtr);
  
  static int verity_alloc_most_once(struct dm_verity *v)
  {
  	struct dm_target *ti = v->ti;
  
  	/* the bitset can only handle INT_MAX blocks */
  	if (v->data_blocks > INT_MAX) {
  		ti->error = "device too large to use check_at_most_once";
  		return -E2BIG;
  	}
  
  	v->validated_blocks = vzalloc(BITS_TO_LONGS(v->data_blocks) *
  				       sizeof(unsigned long));
  	if (!v->validated_blocks) {
  		ti->error = "failed to allocate bitset for check_at_most_once";
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  static int verity_alloc_zero_digest(struct dm_verity *v)
  {
  	int r = -ENOMEM;
  	struct shash_desc *desc;
  	u8 *zero_data;
  
  	v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
  
  	if (!v->zero_digest)
  		return r;
  
  	desc = kmalloc(v->shash_descsize, GFP_KERNEL);
  
  	if (!desc)
  		return r; /* verity_dtr will free zero_digest */
  
  	zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
  
  	if (!zero_data)
  		goto out;
  
  	r = verity_hash(v, desc, zero_data, 1 << v->data_dev_block_bits,
  			v->zero_digest);
  
  out:
  	kfree(desc);
  	kfree(zero_data);
  
  	return r;
  }
  
  static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
  {
  	int r;
  	unsigned argc;
  	struct dm_target *ti = v->ti;
  	const char *arg_name;
  
  	static struct dm_arg _args[] = {
  		{0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
  	};
  
  	r = dm_read_arg_group(_args, as, &argc, &ti->error);
  	if (r)
  		return -EINVAL;
  
  	if (!argc)
  		return 0;
  
  	do {
  		arg_name = dm_shift_arg(as);
  		argc--;
  
  		if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
  			v->mode = DM_VERITY_MODE_LOGGING;
  			continue;
  
  		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
  			v->mode = DM_VERITY_MODE_RESTART;
  			continue;
  
  		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
  			r = verity_alloc_zero_digest(v);
  			if (r) {
  				ti->error = "Cannot allocate zero digest";
  				return r;
  			}
  			continue;
  
  		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
  			r = verity_alloc_most_once(v);
  			if (r)
  				return r;
  			continue;
  
  		} else if (verity_is_fec_opt_arg(arg_name)) {
  			r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
  			if (r)
  				return r;
  			continue;
  		}
  
  		ti->error = "Unrecognized verity feature request";
  		return -EINVAL;
  	} while (argc && !r);
  
  	return r;
  }
  
  /*
   * Target parameters:
   *	<version>	The current format is version 1.
   *			Vsn 0 is compatible with original Chromium OS releases.
   *	<data device>
   *	<hash device>
   *	<data block size>
   *	<hash block size>
   *	<the number of data blocks>
   *	<hash start block>
   *	<algorithm>
   *	<digest>
   *	<salt>		Hex string or "-" if no salt.
   */
  int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
  {
  	struct dm_verity *v;
  	struct dm_arg_set as;
  	unsigned int num;
  	unsigned long long num_ll;
  	int r;
  	int i;
  	sector_t hash_position;
  	char dummy;
  
  	v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
  	if (!v) {
  		ti->error = "Cannot allocate verity structure";
  		return -ENOMEM;
  	}
  	ti->private = v;
  	v->ti = ti;
  
  	r = verity_fec_ctr_alloc(v);
  	if (r)
  		goto bad;
  
  	if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
  		ti->error = "Device must be readonly";
  		r = -EINVAL;
  		goto bad;
  	}
  
  	if (argc < 10) {
  		ti->error = "Not enough arguments";
  		r = -EINVAL;
  		goto bad;
  	}
  
  	if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
  	    num > 1) {
  		ti->error = "Invalid version";
  		r = -EINVAL;
  		goto bad;
  	}
  	v->version = num;
  
  	r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
  	if (r) {
  		ti->error = "Data device lookup failed";
  		goto bad;
  	}
  
  	r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
  	if (r) {
  		ti->error = "Data device lookup failed";
  		goto bad;
  	}
  
  	if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
  	    !num || (num & (num - 1)) ||
  	    num < bdev_logical_block_size(v->data_dev->bdev) ||
  	    num > PAGE_SIZE) {
  		ti->error = "Invalid data device block size";
  		r = -EINVAL;
  		goto bad;
  	}
  	v->data_dev_block_bits = __ffs(num);
  
  	if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
  	    !num || (num & (num - 1)) ||
  	    num < bdev_logical_block_size(v->hash_dev->bdev) ||
  	    num > INT_MAX) {
  		ti->error = "Invalid hash device block size";
  		r = -EINVAL;
  		goto bad;
  	}
  	v->hash_dev_block_bits = __ffs(num);
  
  	if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
  	    (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
  	    >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
  		ti->error = "Invalid data blocks";
  		r = -EINVAL;
  		goto bad;
  	}
  	v->data_blocks = num_ll;
  
  	if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
  		ti->error = "Data device is too small";
  		r = -EINVAL;
  		goto bad;
  	}
  
  	if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
  	    (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
  	    >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
  		ti->error = "Invalid hash start";
  		r = -EINVAL;
  		goto bad;
  	}
  	v->hash_start = num_ll;
  
  	v->alg_name = kstrdup(argv[7], GFP_KERNEL);
  	if (!v->alg_name) {
  		ti->error = "Cannot allocate algorithm name";
  		r = -ENOMEM;
  		goto bad;
  	}
  
  	v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
  	if (IS_ERR(v->tfm)) {
  		ti->error = "Cannot initialize hash function";
  		r = PTR_ERR(v->tfm);
  		v->tfm = NULL;
  		goto bad;
  	}
  	v->digest_size = crypto_shash_digestsize(v->tfm);
  	if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
  		ti->error = "Digest size too big";
  		r = -EINVAL;
  		goto bad;
  	}
  	v->shash_descsize =
  		sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
  
  	v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
  	if (!v->root_digest) {
  		ti->error = "Cannot allocate root digest";
  		r = -ENOMEM;
  		goto bad;
  	}
  	if (strlen(argv[8]) != v->digest_size * 2 ||
  	    hex2bin(v->root_digest, argv[8], v->digest_size)) {
  		ti->error = "Invalid root digest";
  		r = -EINVAL;
  		goto bad;
  	}
  
  	if (strcmp(argv[9], "-")) {
  		v->salt_size = strlen(argv[9]) / 2;
  		v->salt = kmalloc(v->salt_size, GFP_KERNEL);
  		if (!v->salt) {
  			ti->error = "Cannot allocate salt";
  			r = -ENOMEM;
  			goto bad;
  		}
  		if (strlen(argv[9]) != v->salt_size * 2 ||
  		    hex2bin(v->salt, argv[9], v->salt_size)) {
  			ti->error = "Invalid salt";
  			r = -EINVAL;
  			goto bad;
  		}
  	}
  
  	argv += 10;
  	argc -= 10;
  
  	/* Optional parameters */
  	if (argc) {
  		as.argc = argc;
  		as.argv = argv;
  
  		r = verity_parse_opt_args(&as, v);
  		if (r < 0)
  			goto bad;
  	}
  
  #ifdef SEC_HEX_DEBUG
  	get_b_info(v->data_dev->name);
  #endif
  
  #ifdef CONFIG_DM_ANDROID_VERITY_AT_MOST_ONCE_DEFAULT_ENABLED
  	if (!v->validated_blocks) {
  		r = verity_alloc_most_once(v);
  		if (r)
  			goto bad;
  	}
  #endif
  
  	v->hash_per_block_bits =
  		__fls((1 << v->hash_dev_block_bits) / v->digest_size);
  
  	v->levels = 0;
  	if (v->data_blocks)
  		while (v->hash_per_block_bits * v->levels < 64 &&
  		       (unsigned long long)(v->data_blocks - 1) >>
  		       (v->hash_per_block_bits * v->levels))
  			v->levels++;
  
  	if (v->levels > DM_VERITY_MAX_LEVELS) {
  		ti->error = "Too many tree levels";
  		r = -E2BIG;
  		goto bad;
  	}
  
  	hash_position = v->hash_start;
  	for (i = v->levels - 1; i >= 0; i--) {
  		sector_t s;
  		v->hash_level_block[i] = hash_position;
  		s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
  					>> ((i + 1) * v->hash_per_block_bits);
  		if (hash_position + s < hash_position) {
  			ti->error = "Hash device offset overflow";
  			r = -E2BIG;
  			goto bad;
  		}
  		hash_position += s;
  	}
  	v->hash_blocks = hash_position;
  
  	v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
  		1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
  		dm_bufio_alloc_callback, NULL);
  	if (IS_ERR(v->bufio)) {
  		ti->error = "Cannot initialize dm-bufio";
  		r = PTR_ERR(v->bufio);
  		v->bufio = NULL;
  		goto bad;
  	}
  
  	if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
  		ti->error = "Hash device is too small";
  		r = -E2BIG;
  		goto bad;
  	}
  
  	/* WQ_UNBOUND greatly improves performance when running on ramdisk */
  	v->verify_wq = alloc_workqueue("kverityd",
  				       WQ_HIGHPRI | WQ_MEM_RECLAIM | WQ_UNBOUND,
  				       num_online_cpus());
  	if (!v->verify_wq) {
  		ti->error = "Cannot allocate workqueue";
  		r = -ENOMEM;
  		goto bad;
  	}
  
  	ti->per_bio_data_size = sizeof(struct dm_verity_io) +
  				v->shash_descsize + v->digest_size * 2;
  
  	r = verity_fec_ctr(v);
  	if (r)
  		goto bad;
  
  	ti->per_bio_data_size = roundup(ti->per_bio_data_size,
  					__alignof__(struct dm_verity_io));
  
  #ifdef SEC_HEX_DEBUG
  	if (!verity_fec_is_enabled(v))
  		add_fec_off_cnt(v->data_dev->name);
  #endif
  
  #ifdef DMV_ALTA
  	v->verity_bitmap = kmalloc(round_up(v->data_blocks, 8) >> 3, GFP_KERNEL);
  	if (v->verity_bitmap == NULL) {
  		ti->error = "Cannot allocate verity_bitmap";
  		r = -ENOMEM;
  		goto bad;
  	}
  	memset(v->verity_bitmap, 0, round_up(v->data_blocks, 8) >> 3);
  #endif
  
  	return 0;
  
  bad:
  
  #ifdef SEC_HEX_DEBUG
  	add_fec_off_cnt("bad");
  #endif
  
  	verity_dtr(ti);
  
  	return r;
  }
  EXPORT_SYMBOL_GPL(verity_ctr);
  
  static struct target_type verity_target = {
  	.name		= "verity",
  	.version	= {1, 4, 0},
  	.module		= THIS_MODULE,
  	.ctr		= verity_ctr,
  	.dtr		= verity_dtr,
  	.map		= verity_map,
  	.status		= verity_status,
  	.ioctl		= verity_ioctl,
  	.merge		= verity_merge,
  	.iterate_devices = verity_iterate_devices,
  	.io_hints	= verity_io_hints,
  };
  
  static int __init dm_verity_init(void)
  {
  	int r;
  
  	r = dm_register_target(&verity_target);
  	if (r < 0)
  		DMERR("register failed %d", r);
  
  	return r;
  }
  
  static void __exit dm_verity_exit(void)
  {
  	dm_unregister_target(&verity_target);
  }
  
  module_init(dm_verity_init);
  module_exit(dm_verity_exit);
  
  MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
  MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
  MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
  MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
  MODULE_LICENSE("GPL");
  