1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2012 Red Hat, Inc.
5 * Author: Mikulas Patocka <mpatocka@redhat.com>
7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
9 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
10 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
11 * hash device. Setting this greatly improves performance when data and hash
12 * are on the same disk on different partitions on devices with poor random
16 #include "dm-verity.h"
17 #include "dm-verity-fec.h"
18 #include "dm-verity-verify-sig.h"
19 #include <linux/module.h>
20 #include <linux/reboot.h>
22 #define DM_MSG_PREFIX "verity"
24 #define DM_VERITY_ENV_LENGTH 42
25 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
27 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
29 #define DM_VERITY_MAX_CORRUPTED_ERRS 100
31 #define DM_VERITY_OPT_LOGGING "ignore_corruption"
32 #define DM_VERITY_OPT_RESTART "restart_on_corruption"
33 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
34 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
36 #define DM_VERITY_OPTS_MAX (3 + DM_VERITY_OPTS_FEC + \
37 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
39 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
41 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
43 struct dm_verity_prefetch_work {
44 struct work_struct work;
51 * Auxiliary structure appended to each dm-bufio buffer. If the value
52 * hash_verified is nonzero, hash of the block has been verified.
54 * The variable hash_verified is set to 0 when allocating the buffer, then
55 * it can be changed to 1 and it is never reset to 0 again.
57 * There is no lock around this value, a race condition can at worst cause
58 * that multiple processes verify the hash of the same buffer simultaneously
59 * and write 1 to hash_verified simultaneously.
60 * This condition is harmless, so we don't need locking.
67 * Initialize struct buffer_aux for a freshly created buffer.
69 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
71 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
73 aux->hash_verified = 0;
77 * Translate input sector number to the sector number on the target device.
79 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
81 return v->data_start + dm_target_offset(v->ti, bi_sector);
85 * Return hash position of a specified block at a specified tree level
86 * (0 is the lowest level).
87 * The lowest "hash_per_block_bits"-bits of the result denote hash position
88 * inside a hash block. The remaining bits denote location of the hash block.
90 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
93 return block >> (level * v->hash_per_block_bits);
96 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
97 const u8 *data, size_t len,
98 struct crypto_wait *wait)
100 struct scatterlist sg;
102 if (likely(!is_vmalloc_addr(data))) {
103 sg_init_one(&sg, data, len);
104 ahash_request_set_crypt(req, &sg, NULL, len);
105 return crypto_wait_req(crypto_ahash_update(req), wait);
109 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
110 flush_kernel_vmap_range((void *)data, this_step);
111 sg_init_table(&sg, 1);
112 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
113 ahash_request_set_crypt(req, &sg, NULL, this_step);
114 r = crypto_wait_req(crypto_ahash_update(req), wait);
125 * Wrapper for crypto_ahash_init, which handles verity salting.
127 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
128 struct crypto_wait *wait)
132 ahash_request_set_tfm(req, v->tfm);
133 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
134 CRYPTO_TFM_REQ_MAY_BACKLOG,
135 crypto_req_done, (void *)wait);
136 crypto_init_wait(wait);
138 r = crypto_wait_req(crypto_ahash_init(req), wait);
140 if (unlikely(r < 0)) {
141 DMERR("crypto_ahash_init failed: %d", r);
145 if (likely(v->salt_size && (v->version >= 1)))
146 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
151 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
152 u8 *digest, struct crypto_wait *wait)
156 if (unlikely(v->salt_size && (!v->version))) {
157 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
160 DMERR("verity_hash_final failed updating salt: %d", r);
165 ahash_request_set_crypt(req, NULL, digest, 0);
166 r = crypto_wait_req(crypto_ahash_final(req), wait);
171 int verity_hash(struct dm_verity *v, struct ahash_request *req,
172 const u8 *data, size_t len, u8 *digest)
175 struct crypto_wait wait;
177 r = verity_hash_init(v, req, &wait);
181 r = verity_hash_update(v, req, data, len, &wait);
185 r = verity_hash_final(v, req, digest, &wait);
191 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
192 sector_t *hash_block, unsigned *offset)
194 sector_t position = verity_position_at_level(v, block, level);
197 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
202 idx = position & ((1 << v->hash_per_block_bits) - 1);
204 *offset = idx * v->digest_size;
206 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
210 * Handle verification errors.
212 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
213 unsigned long long block)
215 char verity_env[DM_VERITY_ENV_LENGTH];
216 char *envp[] = { verity_env, NULL };
217 const char *type_str = "";
218 struct mapped_device *md = dm_table_get_md(v->ti->table);
220 /* Corruption should be visible in device status in all modes */
223 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
229 case DM_VERITY_BLOCK_TYPE_DATA:
232 case DM_VERITY_BLOCK_TYPE_METADATA:
233 type_str = "metadata";
239 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
242 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
243 DMERR("%s: reached maximum errors", v->data_dev->name);
245 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
246 DM_VERITY_ENV_VAR_NAME, type, block);
248 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
251 if (v->mode == DM_VERITY_MODE_LOGGING)
254 if (v->mode == DM_VERITY_MODE_RESTART)
255 kernel_restart("dm-verity device corrupted");
261 * Verify hash of a metadata block pertaining to the specified data block
262 * ("block" argument) at a specified level ("level" argument).
264 * On successful return, verity_io_want_digest(v, io) contains the hash value
265 * for a lower tree level or for the data block (if we're at the lowest level).
267 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
268 * If "skip_unverified" is false, unverified buffer is hashed and verified
269 * against current value of verity_io_want_digest(v, io).
271 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
272 sector_t block, int level, bool skip_unverified,
275 struct dm_buffer *buf;
276 struct buffer_aux *aux;
282 verity_hash_at_level(v, block, level, &hash_block, &offset);
284 data = dm_bufio_read(v->bufio, hash_block, &buf);
286 return PTR_ERR(data);
288 aux = dm_bufio_get_aux_data(buf);
290 if (!aux->hash_verified) {
291 if (skip_unverified) {
296 r = verity_hash(v, verity_io_hash_req(v, io),
297 data, 1 << v->hash_dev_block_bits,
298 verity_io_real_digest(v, io));
302 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
303 v->digest_size) == 0))
304 aux->hash_verified = 1;
305 else if (verity_fec_decode(v, io,
306 DM_VERITY_BLOCK_TYPE_METADATA,
307 hash_block, data, NULL) == 0)
308 aux->hash_verified = 1;
309 else if (verity_handle_err(v,
310 DM_VERITY_BLOCK_TYPE_METADATA,
318 memcpy(want_digest, data, v->digest_size);
322 dm_bufio_release(buf);
327 * Find a hash for a given block, write it to digest and verify the integrity
328 * of the hash tree if necessary.
330 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
331 sector_t block, u8 *digest, bool *is_zero)
335 if (likely(v->levels)) {
337 * First, we try to get the requested hash for
338 * the current block. If the hash block itself is
339 * verified, zero is returned. If it isn't, this
340 * function returns 1 and we fall back to whole
341 * chain verification.
343 r = verity_verify_level(v, io, block, 0, true, digest);
348 memcpy(digest, v->root_digest, v->digest_size);
350 for (i = v->levels - 1; i >= 0; i--) {
351 r = verity_verify_level(v, io, block, i, false, digest);
356 if (!r && v->zero_digest)
357 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
365 * Calculates the digest for the given bio
367 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
368 struct bvec_iter *iter, struct crypto_wait *wait)
370 unsigned int todo = 1 << v->data_dev_block_bits;
371 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
372 struct scatterlist sg;
373 struct ahash_request *req = verity_io_hash_req(v, io);
378 struct bio_vec bv = bio_iter_iovec(bio, *iter);
380 sg_init_table(&sg, 1);
384 if (likely(len >= todo))
387 * Operating on a single page at a time looks suboptimal
388 * until you consider the typical block size is 4,096B.
389 * Going through this loops twice should be very rare.
391 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
392 ahash_request_set_crypt(req, &sg, NULL, len);
393 r = crypto_wait_req(crypto_ahash_update(req), wait);
395 if (unlikely(r < 0)) {
396 DMERR("verity_for_io_block crypto op failed: %d", r);
400 bio_advance_iter(bio, iter, len);
408 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
409 * starting from iter.
411 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
412 struct bvec_iter *iter,
413 int (*process)(struct dm_verity *v,
414 struct dm_verity_io *io, u8 *data,
417 unsigned todo = 1 << v->data_dev_block_bits;
418 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
424 struct bio_vec bv = bio_iter_iovec(bio, *iter);
426 page = kmap_atomic(bv.bv_page);
429 if (likely(len >= todo))
432 r = process(v, io, page + bv.bv_offset, len);
438 bio_advance_iter(bio, iter, len);
445 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
446 u8 *data, size_t len)
448 memset(data, 0, len);
453 * Moves the bio iter one data block forward.
455 static inline void verity_bv_skip_block(struct dm_verity *v,
456 struct dm_verity_io *io,
457 struct bvec_iter *iter)
459 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
461 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
465 * Verify one "dm_verity_io" structure.
467 static int verity_verify_io(struct dm_verity_io *io)
470 struct dm_verity *v = io->v;
471 struct bvec_iter start;
473 struct crypto_wait wait;
475 for (b = 0; b < io->n_blocks; b++) {
477 sector_t cur_block = io->block + b;
478 struct ahash_request *req = verity_io_hash_req(v, io);
480 if (v->validated_blocks &&
481 likely(test_bit(cur_block, v->validated_blocks))) {
482 verity_bv_skip_block(v, io, &io->iter);
486 r = verity_hash_for_block(v, io, cur_block,
487 verity_io_want_digest(v, io),
494 * If we expect a zero block, don't validate, just
497 r = verity_for_bv_block(v, io, &io->iter,
505 r = verity_hash_init(v, req, &wait);
510 r = verity_for_io_block(v, io, &io->iter, &wait);
514 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
519 if (likely(memcmp(verity_io_real_digest(v, io),
520 verity_io_want_digest(v, io), v->digest_size) == 0)) {
521 if (v->validated_blocks)
522 set_bit(cur_block, v->validated_blocks);
525 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
526 cur_block, NULL, &start) == 0)
528 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
537 * Skip verity work in response to I/O error when system is shutting down.
539 static inline bool verity_is_system_shutting_down(void)
541 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
542 || system_state == SYSTEM_RESTART;
546 * End one "io" structure with a given error.
548 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
550 struct dm_verity *v = io->v;
551 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
553 bio->bi_end_io = io->orig_bi_end_io;
554 bio->bi_status = status;
556 verity_fec_finish_io(io);
561 static void verity_work(struct work_struct *w)
563 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
565 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
568 static void verity_end_io(struct bio *bio)
570 struct dm_verity_io *io = bio->bi_private;
572 if (bio->bi_status &&
573 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
574 verity_finish_io(io, bio->bi_status);
578 INIT_WORK(&io->work, verity_work);
579 queue_work(io->v->verify_wq, &io->work);
583 * Prefetch buffers for the specified io.
584 * The root buffer is not prefetched, it is assumed that it will be cached
587 static void verity_prefetch_io(struct work_struct *work)
589 struct dm_verity_prefetch_work *pw =
590 container_of(work, struct dm_verity_prefetch_work, work);
591 struct dm_verity *v = pw->v;
594 for (i = v->levels - 2; i >= 0; i--) {
595 sector_t hash_block_start;
596 sector_t hash_block_end;
597 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
598 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
600 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
602 cluster >>= v->data_dev_block_bits;
603 if (unlikely(!cluster))
604 goto no_prefetch_cluster;
606 if (unlikely(cluster & (cluster - 1)))
607 cluster = 1 << __fls(cluster);
609 hash_block_start &= ~(sector_t)(cluster - 1);
610 hash_block_end |= cluster - 1;
611 if (unlikely(hash_block_end >= v->hash_blocks))
612 hash_block_end = v->hash_blocks - 1;
615 dm_bufio_prefetch(v->bufio, hash_block_start,
616 hash_block_end - hash_block_start + 1);
622 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
624 struct dm_verity_prefetch_work *pw;
626 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
627 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
632 INIT_WORK(&pw->work, verity_prefetch_io);
634 pw->block = io->block;
635 pw->n_blocks = io->n_blocks;
636 queue_work(v->verify_wq, &pw->work);
640 * Bio map function. It allocates dm_verity_io structure and bio vector and
641 * fills them. Then it issues prefetches and the I/O.
643 static int verity_map(struct dm_target *ti, struct bio *bio)
645 struct dm_verity *v = ti->private;
646 struct dm_verity_io *io;
648 bio_set_dev(bio, v->data_dev->bdev);
649 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
651 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
652 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
653 DMERR_LIMIT("unaligned io");
654 return DM_MAPIO_KILL;
657 if (bio_end_sector(bio) >>
658 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
659 DMERR_LIMIT("io out of range");
660 return DM_MAPIO_KILL;
663 if (bio_data_dir(bio) == WRITE)
664 return DM_MAPIO_KILL;
666 io = dm_per_bio_data(bio, ti->per_io_data_size);
668 io->orig_bi_end_io = bio->bi_end_io;
669 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
670 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
672 bio->bi_end_io = verity_end_io;
673 bio->bi_private = io;
674 io->iter = bio->bi_iter;
676 verity_fec_init_io(io);
678 verity_submit_prefetch(v, io);
680 generic_make_request(bio);
682 return DM_MAPIO_SUBMITTED;
686 * Status: V (valid) or C (corruption found)
688 static void verity_status(struct dm_target *ti, status_type_t type,
689 unsigned status_flags, char *result, unsigned maxlen)
691 struct dm_verity *v = ti->private;
697 case STATUSTYPE_INFO:
698 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
700 case STATUSTYPE_TABLE:
701 DMEMIT("%u %s %s %u %u %llu %llu %s ",
705 1 << v->data_dev_block_bits,
706 1 << v->hash_dev_block_bits,
707 (unsigned long long)v->data_blocks,
708 (unsigned long long)v->hash_start,
711 for (x = 0; x < v->digest_size; x++)
712 DMEMIT("%02x", v->root_digest[x]);
717 for (x = 0; x < v->salt_size; x++)
718 DMEMIT("%02x", v->salt[x]);
719 if (v->mode != DM_VERITY_MODE_EIO)
721 if (verity_fec_is_enabled(v))
722 args += DM_VERITY_OPTS_FEC;
725 if (v->validated_blocks)
727 if (v->signature_key_desc)
728 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
732 if (v->mode != DM_VERITY_MODE_EIO) {
735 case DM_VERITY_MODE_LOGGING:
736 DMEMIT(DM_VERITY_OPT_LOGGING);
738 case DM_VERITY_MODE_RESTART:
739 DMEMIT(DM_VERITY_OPT_RESTART);
746 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
747 if (v->validated_blocks)
748 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
749 sz = verity_fec_status_table(v, sz, result, maxlen);
750 if (v->signature_key_desc)
751 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
752 " %s", v->signature_key_desc);
757 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
759 struct dm_verity *v = ti->private;
761 *bdev = v->data_dev->bdev;
764 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
769 static int verity_iterate_devices(struct dm_target *ti,
770 iterate_devices_callout_fn fn, void *data)
772 struct dm_verity *v = ti->private;
774 return fn(ti, v->data_dev, v->data_start, ti->len, data);
777 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
779 struct dm_verity *v = ti->private;
781 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
782 limits->logical_block_size = 1 << v->data_dev_block_bits;
784 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
785 limits->physical_block_size = 1 << v->data_dev_block_bits;
787 blk_limits_io_min(limits, limits->logical_block_size);
790 static void verity_dtr(struct dm_target *ti)
792 struct dm_verity *v = ti->private;
795 destroy_workqueue(v->verify_wq);
798 dm_bufio_client_destroy(v->bufio);
800 kvfree(v->validated_blocks);
802 kfree(v->root_digest);
803 kfree(v->zero_digest);
806 crypto_free_ahash(v->tfm);
811 dm_put_device(ti, v->hash_dev);
814 dm_put_device(ti, v->data_dev);
818 kfree(v->signature_key_desc);
823 static int verity_alloc_most_once(struct dm_verity *v)
825 struct dm_target *ti = v->ti;
827 /* the bitset can only handle INT_MAX blocks */
828 if (v->data_blocks > INT_MAX) {
829 ti->error = "device too large to use check_at_most_once";
833 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
834 sizeof(unsigned long),
836 if (!v->validated_blocks) {
837 ti->error = "failed to allocate bitset for check_at_most_once";
844 static int verity_alloc_zero_digest(struct dm_verity *v)
847 struct ahash_request *req;
850 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
855 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
858 return r; /* verity_dtr will free zero_digest */
860 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
865 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
875 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
876 struct dm_verity_sig_opts *verify_args)
880 struct dm_target *ti = v->ti;
881 const char *arg_name;
883 static const struct dm_arg _args[] = {
884 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
887 r = dm_read_arg_group(_args, as, &argc, &ti->error);
895 arg_name = dm_shift_arg(as);
898 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
899 v->mode = DM_VERITY_MODE_LOGGING;
902 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
903 v->mode = DM_VERITY_MODE_RESTART;
906 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
907 r = verity_alloc_zero_digest(v);
909 ti->error = "Cannot allocate zero digest";
914 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
915 r = verity_alloc_most_once(v);
920 } else if (verity_is_fec_opt_arg(arg_name)) {
921 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
925 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
926 r = verity_verify_sig_parse_opt_args(as, v,
935 ti->error = "Unrecognized verity feature request";
937 } while (argc && !r);
944 * <version> The current format is version 1.
945 * Vsn 0 is compatible with original Chromium OS releases.
950 * <the number of data blocks>
954 * <salt> Hex string or "-" if no salt.
956 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
959 struct dm_verity_sig_opts verify_args = {0};
960 struct dm_arg_set as;
962 unsigned long long num_ll;
965 sector_t hash_position;
967 char *root_hash_digest_to_validate;
969 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
971 ti->error = "Cannot allocate verity structure";
977 r = verity_fec_ctr_alloc(v);
981 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
982 ti->error = "Device must be readonly";
988 ti->error = "Not enough arguments";
993 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
995 ti->error = "Invalid version";
1001 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1003 ti->error = "Data device lookup failed";
1007 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1009 ti->error = "Hash device lookup failed";
1013 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1014 !num || (num & (num - 1)) ||
1015 num < bdev_logical_block_size(v->data_dev->bdev) ||
1017 ti->error = "Invalid data device block size";
1021 v->data_dev_block_bits = __ffs(num);
1023 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1024 !num || (num & (num - 1)) ||
1025 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1027 ti->error = "Invalid hash device block size";
1031 v->hash_dev_block_bits = __ffs(num);
1033 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1034 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1035 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1036 ti->error = "Invalid data blocks";
1040 v->data_blocks = num_ll;
1042 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1043 ti->error = "Data device is too small";
1048 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1049 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1050 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1051 ti->error = "Invalid hash start";
1055 v->hash_start = num_ll;
1057 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1059 ti->error = "Cannot allocate algorithm name";
1064 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1065 if (IS_ERR(v->tfm)) {
1066 ti->error = "Cannot initialize hash function";
1067 r = PTR_ERR(v->tfm);
1073 * dm-verity performance can vary greatly depending on which hash
1074 * algorithm implementation is used. Help people debug performance
1075 * problems by logging the ->cra_driver_name.
1077 DMINFO("%s using implementation \"%s\"", v->alg_name,
1078 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1080 v->digest_size = crypto_ahash_digestsize(v->tfm);
1081 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1082 ti->error = "Digest size too big";
1086 v->ahash_reqsize = sizeof(struct ahash_request) +
1087 crypto_ahash_reqsize(v->tfm);
1089 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1090 if (!v->root_digest) {
1091 ti->error = "Cannot allocate root digest";
1095 if (strlen(argv[8]) != v->digest_size * 2 ||
1096 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1097 ti->error = "Invalid root digest";
1101 root_hash_digest_to_validate = argv[8];
1103 if (strcmp(argv[9], "-")) {
1104 v->salt_size = strlen(argv[9]) / 2;
1105 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1107 ti->error = "Cannot allocate salt";
1111 if (strlen(argv[9]) != v->salt_size * 2 ||
1112 hex2bin(v->salt, argv[9], v->salt_size)) {
1113 ti->error = "Invalid salt";
1122 /* Optional parameters */
1127 r = verity_parse_opt_args(&as, v, &verify_args);
1132 /* Root hash signature is a optional parameter*/
1133 r = verity_verify_root_hash(root_hash_digest_to_validate,
1134 strlen(root_hash_digest_to_validate),
1136 verify_args.sig_size);
1138 ti->error = "Root hash verification failed";
1141 v->hash_per_block_bits =
1142 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1146 while (v->hash_per_block_bits * v->levels < 64 &&
1147 (unsigned long long)(v->data_blocks - 1) >>
1148 (v->hash_per_block_bits * v->levels))
1151 if (v->levels > DM_VERITY_MAX_LEVELS) {
1152 ti->error = "Too many tree levels";
1157 hash_position = v->hash_start;
1158 for (i = v->levels - 1; i >= 0; i--) {
1160 v->hash_level_block[i] = hash_position;
1161 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1162 >> ((i + 1) * v->hash_per_block_bits);
1163 if (hash_position + s < hash_position) {
1164 ti->error = "Hash device offset overflow";
1170 v->hash_blocks = hash_position;
1172 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1173 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1174 dm_bufio_alloc_callback, NULL);
1175 if (IS_ERR(v->bufio)) {
1176 ti->error = "Cannot initialize dm-bufio";
1177 r = PTR_ERR(v->bufio);
1182 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1183 ti->error = "Hash device is too small";
1188 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1189 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1190 if (!v->verify_wq) {
1191 ti->error = "Cannot allocate workqueue";
1196 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1197 v->ahash_reqsize + v->digest_size * 2;
1199 r = verity_fec_ctr(v);
1203 ti->per_io_data_size = roundup(ti->per_io_data_size,
1204 __alignof__(struct dm_verity_io));
1206 verity_verify_sig_opts_cleanup(&verify_args);
1212 verity_verify_sig_opts_cleanup(&verify_args);
1218 static struct target_type verity_target = {
1220 .features = DM_TARGET_IMMUTABLE,
1221 .version = {1, 5, 0},
1222 .module = THIS_MODULE,
1226 .status = verity_status,
1227 .prepare_ioctl = verity_prepare_ioctl,
1228 .iterate_devices = verity_iterate_devices,
1229 .io_hints = verity_io_hints,
1232 static int __init dm_verity_init(void)
1236 r = dm_register_target(&verity_target);
1238 DMERR("register failed %d", r);
1243 static void __exit dm_verity_exit(void)
1245 dm_unregister_target(&verity_target);
1248 module_init(dm_verity_init);
1249 module_exit(dm_verity_exit);
1251 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1252 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1253 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1254 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1255 MODULE_LICENSE("GPL");