dm verity: move dm-verity.c to dm-verity-target.c

Prepare for extending dm-verity with an optional object.  Follows the
naming convention used by other DM targets (e.g. dm-cache and dm-era).

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 0 insertions, 1039 deletions

diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
deleted file mode 100644
index b0a53c3b926d..000000000000
--- a/drivers/md/dm-verity.c
+++ /dev/null
@@ -1,1039 +0,0 @@
-/*
- * 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-bufio.h"
-
-#include <linux/module.h>
-#include <linux/device-mapper.h>
-#include <linux/reboot.h>
-#include <crypto/hash.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_LEVELS		63
-#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_OPTS_MAX		1
-
-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);
-
-enum verity_mode {
-	DM_VERITY_MODE_EIO,
-	DM_VERITY_MODE_LOGGING,
-	DM_VERITY_MODE_RESTART
-};
-
-enum verity_block_type {
-	DM_VERITY_BLOCK_TYPE_DATA,
-	DM_VERITY_BLOCK_TYPE_METADATA
-};
-
-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 *tfm;
-	u8 *root_digest;	/* digest of the root block */
-	u8 *salt;		/* salt: its size is salt_size */
-	unsigned 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;
-	unsigned digest_size;	/* digest size for the current hash algorithm */
-	unsigned shash_descsize;/* the size of temporary space for crypto */
-	int hash_failed;	/* set to 1 if hash of any block failed */
-	enum verity_mode mode;	/* mode for handling verification errors */
-	unsigned 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_io {
-	struct dm_verity *v;
-
-	/* original value of bio->bi_end_io */
-	bio_end_io_t *orig_bi_end_io;
-
-	sector_t block;
-	unsigned n_blocks;
-
-	struct bvec_iter iter;
-
-	struct work_struct work;
-
-	/*
-	 * Three variably-size fields follow this struct:
-	 *
-	 * u8 hash_desc[v->shash_descsize];
-	 * u8 real_digest[v->digest_size];
-	 * u8 want_digest[v->digest_size];
-	 *
-	 * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
-	 */
-};
-
-struct dm_verity_prefetch_work {
-	struct work_struct work;
-	struct dm_verity *v;
-	sector_t block;
-	unsigned n_blocks;
-};
-
-static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
-{
-	return (struct shash_desc *)(io + 1);
-}
-
-static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
-{
-	return (u8 *)(io + 1) + v->shash_descsize;
-}
-
-static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
-{
-	return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
-}
-
-/*
- * 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;
-}
-
-static 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.
- */
-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 (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;
-}
-
-/*
- * Verify hash of a metadata block pertaining to the specified data block
- * ("block" argument) at a specified level ("level" argument).
- *
- * On successful return, 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 leve).
- *
- * 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 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, io_hash_desc(v, io),
-				data, 1 << v->hash_dev_block_bits,
-				io_real_digest(v, io));
-		if (unlikely(r < 0))
-			goto release_ret_r;
-
-		if (likely(memcmp(io_real_digest(v, io), want_digest,
-				  v->digest_size) == 0))
-			aux->hash_verified = 1;
-		else if (verity_handle_err(v,
-					   DM_VERITY_BLOCK_TYPE_METADATA,
-					   hash_block)) {
-			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.
- */
-static int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
-				 sector_t block, u8 *digest)
-{
-	int i;
-	int r;
-
-	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))
-			return r;
-	}
-
-	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))
-			return r;
-	}
-
-	return 0;
-}
-
-/*
- * Verify one "dm_verity_io" structure.
- */
-static int verity_verify_io(struct dm_verity_io *io)
-{
-	struct dm_verity *v = io->v;
-	struct bio *bio = dm_bio_from_per_bio_data(io,
-						   v->ti->per_bio_data_size);
-	unsigned b;
-
-	for (b = 0; b < io->n_blocks; b++) {
-		int r;
-		unsigned todo;
-		struct shash_desc *desc = io_hash_desc(v, io);
-
-		r = verity_hash_for_block(v, io, io->block + b,
-					  io_want_digest(v, io));
-		if (unlikely(r < 0))
-			return r;
-
-		r = verity_hash_init(v, desc);
-		if (unlikely(r < 0))
-			return r;
-
-		todo = 1 << v->data_dev_block_bits;
-		do {
-			u8 *page;
-			unsigned len;
-			struct bio_vec bv = bio_iter_iovec(bio, io->iter);
-
-			page = kmap_atomic(bv.bv_page);
-			len = bv.bv_len;
-			if (likely(len >= todo))
-				len = todo;
-			r = verity_hash_update(v, desc,  page + bv.bv_offset,
-					       len);
-			kunmap_atomic(page);
-
-			if (unlikely(r < 0))
-				return r;
-
-			bio_advance_iter(bio, &io->iter, len);
-			todo -= len;
-		} while (todo);
-
-		r = verity_hash_final(v, desc, io_real_digest(v, io));
-		if (unlikely(r < 0))
-			return r;
-
-		if (likely(memcmp(io_real_digest(v, io),
-				io_want_digest(v, io), v->digest_size) == 0))
-			continue;
-		else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
-				io->block + b))
-			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_error = error;
-
-	bio_endio(bio);
-}
-
-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)
-{
-	struct dm_verity_io *io = bio->bi_private;
-
-	if (bio->bi_error) {
-		verity_finish_io(io, bio->bi_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.
- */
-static int verity_map(struct dm_target *ti, struct bio *bio)
-{
-	struct dm_verity *v = ti->private;
-	struct dm_verity_io *io;
-
-	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;
-
-	io = dm_per_bio_data(bio, ti->per_bio_data_size);
-	io->v = v;
-	io->orig_bi_end_io = bio->bi_end_io;
-	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;
-
-	bio->bi_end_io = verity_end_io;
-	bio->bi_private = io;
-	io->iter = bio->bi_iter;
-
-	verity_submit_prefetch(v, io);
-
-	generic_make_request(bio);
-
-	return DM_MAPIO_SUBMITTED;
-}
-
-/*
- * Status: V (valid) or C (corruption found)
- */
-static 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 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) {
-			DMEMIT(" 1 ");
-			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();
-			}
-		}
-		break;
-	}
-}
-
-static int verity_prepare_ioctl(struct dm_target *ti,
-		struct block_device **bdev, fmode_t *mode)
-{
-	struct dm_verity *v = ti->private;
-
-	*bdev = v->data_dev->bdev;
-
-	if (v->data_start ||
-	    ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
-		return 1;
-	return 0;
-}
-
-static 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);
-}
-
-static 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);
-}
-
-static void verity_dtr(struct dm_target *ti)
-{
-	struct dm_verity *v = ti->private;
-
-	if (v->verify_wq)
-		destroy_workqueue(v->verify_wq);
-
-	if (v->bufio)
-		dm_bufio_client_destroy(v->bufio);
-
-	kfree(v->salt);
-	kfree(v->root_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);
-
-	kfree(v);
-}
-
-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;
-		}
-
-		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.
- */
-static 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;
-
-	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;
-	}
-
-	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;
-	}
-
-	ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
-
-	/* WQ_UNBOUND greatly improves performance when running on ramdisk */
-	v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
-	if (!v->verify_wq) {
-		ti->error = "Cannot allocate workqueue";
-		r = -ENOMEM;
-		goto bad;
-	}
-
-	return 0;
-
-bad:
-	verity_dtr(ti);
-
-	return r;
-}
-
-static struct target_type verity_target = {
-	.name		= "verity",
-	.version	= {1, 2, 0},
-	.module		= THIS_MODULE,
-	.ctr		= verity_ctr,
-	.dtr		= verity_dtr,
-	.map		= verity_map,
-	.status		= verity_status,
-	.prepare_ioctl	= verity_prepare_ioctl,
-	.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");