/* * Copyright (C) 2012 Red Hat, Inc. * * Author: Mikulas Patocka * * 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 #include #include #define DM_MSG_PREFIX "verity" #define DM_VERITY_IO_VEC_INLINE 16 #define DM_VERITY_MEMPOOL_SIZE 4 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 #define DM_VERITY_MAX_LEVELS 63 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); 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 */ mempool_t *vec_mempool; /* mempool of bio vector */ 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 values of bio->bi_end_io and bio->bi_private */ bio_end_io_t *orig_bi_end_io; void *orig_bi_private; sector_t block; unsigned n_blocks; /* saved bio vector */ struct bio_vec *io_vec; unsigned io_vec_size; struct work_struct work; /* A space for short vectors; longer vectors are allocated separately. */ struct bio_vec io_vec_inline[DM_VERITY_IO_VEC_INLINE]; /* * 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); } 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); } /* * 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_io *io, sector_t block, int level, bool skip_unverified) { struct dm_verity *v = io->v; 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 (unlikely(IS_ERR(data))) return PTR_ERR(data); aux = dm_bufio_get_aux_data(buf); if (!aux->hash_verified) { struct shash_desc *desc; u8 *result; if (skip_unverified) { r = 1; goto release_ret_r; } desc = io_hash_desc(v, io); desc->tfm = v->tfm; desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; r = crypto_shash_init(desc); if (r < 0) { DMERR("crypto_shash_init failed: %d", r); goto release_ret_r; } if (likely(v->version >= 1)) { r = crypto_shash_update(desc, v->salt, v->salt_size); if (r < 0) { DMERR("crypto_shash_update failed: %d", r); goto release_ret_r; } } r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits); if (r < 0) { DMERR("crypto_shash_update failed: %d", r); goto release_ret_r; } if (!v->version) { r = crypto_shash_update(desc, v->salt, v->salt_size); if (r < 0) { DMERR("crypto_shash_update failed: %d", r); goto release_ret_r; } } result = io_real_digest(v, io); r = crypto_shash_final(desc, result); if (r < 0) { DMERR("crypto_shash_final failed: %d", r); goto release_ret_r; } if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { DMERR_LIMIT("metadata block %llu is corrupted", (unsigned long long)hash_block); v->hash_failed = 1; r = -EIO; goto release_ret_r; } else aux->hash_verified = 1; } data += offset; memcpy(io_want_digest(v, io), data, v->digest_size); dm_bufio_release(buf); return 0; release_ret_r: dm_bufio_release(buf); return r; } /* * Verify one "dm_verity_io" structure. */ static int verity_verify_io(struct dm_verity_io *io) { struct dm_verity *v = io->v; unsigned b; int i; unsigned vector = 0, offset = 0; for (b = 0; b < io->n_blocks; b++) { struct shash_desc *desc; u8 *result; int r; unsigned todo; 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 0 and we fall back to whole * chain verification. */ int r = verity_verify_level(io, io->block + b, 0, true); if (likely(!r)) goto test_block_hash; if (r < 0) return r; } memcpy(io_want_digest(v, io), v->root_digest, v->digest_size); for (i = v->levels - 1; i >= 0; i--) { int r = verity_verify_level(io, io->block + b, i, false); if (unlikely(r)) return r; } test_block_hash: desc = io_hash_desc(v, io); desc->tfm = v->tfm; desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; r = crypto_shash_init(desc); if (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 (r < 0) { DMERR("crypto_shash_update failed: %d", r); return r; } } todo = 1 << v->data_dev_block_bits; do { struct bio_vec *bv; u8 *page; unsigned len; BUG_ON(vector >= io->io_vec_size); bv = &io->io_vec[vector]; page = kmap_atomic(bv->bv_page); len = bv->bv_len - offset; if (likely(len >= todo)) len = todo; r = crypto_shash_update(desc, page + bv->bv_offset + offset, len); kunmap_atomic(page); if (r < 0) { DMERR("crypto_shash_update failed: %d", r); return r; } offset += len; if (likely(offset == bv->bv_len)) { offset = 0; vector++; } todo -= len; } while (todo); if (!v->version) { r = crypto_shash_update(desc, v->salt, v->salt_size); if (r < 0) { DMERR("crypto_shash_update failed: %d", r); return r; } } result = io_real_digest(v, io); r = crypto_shash_final(desc, result); if (r < 0) { DMERR("crypto_shash_final failed: %d", r); return r; } if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { DMERR_LIMIT("data block %llu is corrupted", (unsigned long long)(io->block + b)); v->hash_failed = 1; return -EIO; } } BUG_ON(vector != io->io_vec_size); BUG_ON(offset); 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; if (io->io_vec != io->io_vec_inline) mempool_free(io->io_vec, v->vec_mempool); bio_endio(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_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. */ 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->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; bio->bi_end_io = verity_end_io; bio->bi_private = io; io->io_vec_size = bio_segments(bio); if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE) io->io_vec = io->io_vec_inline; else io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO); memcpy(io->io_vec, __bio_iovec(bio), io->io_vec_size * sizeof(struct bio_vec)); 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]); break; } } static 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); } static 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)); } 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->vec_mempool) mempool_destroy(v->vec_mempool); 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); } /* * Target parameters: * The current format is version 1. * Vsn 0 is compatible with original Chromium OS releases. * * * * * * * * * Hex string or "-" if no salt. */ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) { struct dm_verity *v; unsigned 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 = "Invalid argument count: exactly 10 arguments required"; 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; } } 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)); v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE, BIO_MAX_PAGES * sizeof(struct bio_vec)); if (!v->vec_mempool) { ti->error = "Cannot allocate vector mempool"; r = -ENOMEM; goto bad; } /* 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, .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 "); MODULE_AUTHOR("Mandeep Baines "); MODULE_AUTHOR("Will Drewry "); MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); MODULE_LICENSE("GPL");