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>
21 #include <linux/scatterlist.h>
22 #include <linux/string.h>
23 #include <linux/jump_label.h>
25 #define DM_MSG_PREFIX "verity"
27 #define DM_VERITY_ENV_LENGTH 42
28 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
30 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
32 #define DM_VERITY_MAX_CORRUPTED_ERRS 100
34 #define DM_VERITY_OPT_LOGGING "ignore_corruption"
35 #define DM_VERITY_OPT_RESTART "restart_on_corruption"
36 #define DM_VERITY_OPT_PANIC "panic_on_corruption"
37 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
38 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
39 #define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
41 #define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \
42 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
44 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
46 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
48 static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
50 struct dm_verity_prefetch_work {
51 struct work_struct work;
54 unsigned int n_blocks;
58 * Auxiliary structure appended to each dm-bufio buffer. If the value
59 * hash_verified is nonzero, hash of the block has been verified.
61 * The variable hash_verified is set to 0 when allocating the buffer, then
62 * it can be changed to 1 and it is never reset to 0 again.
64 * There is no lock around this value, a race condition can at worst cause
65 * that multiple processes verify the hash of the same buffer simultaneously
66 * and write 1 to hash_verified simultaneously.
67 * This condition is harmless, so we don't need locking.
74 * Initialize struct buffer_aux for a freshly created buffer.
76 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
78 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
80 aux->hash_verified = 0;
84 * Translate input sector number to the sector number on the target device.
86 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
88 return v->data_start + dm_target_offset(v->ti, bi_sector);
92 * Return hash position of a specified block at a specified tree level
93 * (0 is the lowest level).
94 * The lowest "hash_per_block_bits"-bits of the result denote hash position
95 * inside a hash block. The remaining bits denote location of the hash block.
97 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
100 return block >> (level * v->hash_per_block_bits);
103 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
104 const u8 *data, size_t len,
105 struct crypto_wait *wait)
107 struct scatterlist sg;
109 if (likely(!is_vmalloc_addr(data))) {
110 sg_init_one(&sg, data, len);
111 ahash_request_set_crypt(req, &sg, NULL, len);
112 return crypto_wait_req(crypto_ahash_update(req), wait);
117 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
119 flush_kernel_vmap_range((void *)data, this_step);
120 sg_init_table(&sg, 1);
121 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
122 ahash_request_set_crypt(req, &sg, NULL, this_step);
123 r = crypto_wait_req(crypto_ahash_update(req), wait);
134 * Wrapper for crypto_ahash_init, which handles verity salting.
136 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
137 struct crypto_wait *wait)
141 ahash_request_set_tfm(req, v->tfm);
142 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
143 CRYPTO_TFM_REQ_MAY_BACKLOG,
144 crypto_req_done, (void *)wait);
145 crypto_init_wait(wait);
147 r = crypto_wait_req(crypto_ahash_init(req), wait);
149 if (unlikely(r < 0)) {
150 DMERR("crypto_ahash_init failed: %d", r);
154 if (likely(v->salt_size && (v->version >= 1)))
155 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
160 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
161 u8 *digest, struct crypto_wait *wait)
165 if (unlikely(v->salt_size && (!v->version))) {
166 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
169 DMERR("%s failed updating salt: %d", __func__, r);
174 ahash_request_set_crypt(req, NULL, digest, 0);
175 r = crypto_wait_req(crypto_ahash_final(req), wait);
180 int verity_hash(struct dm_verity *v, struct ahash_request *req,
181 const u8 *data, size_t len, u8 *digest)
184 struct crypto_wait wait;
186 r = verity_hash_init(v, req, &wait);
190 r = verity_hash_update(v, req, data, len, &wait);
194 r = verity_hash_final(v, req, digest, &wait);
200 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
201 sector_t *hash_block, unsigned int *offset)
203 sector_t position = verity_position_at_level(v, block, level);
206 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
211 idx = position & ((1 << v->hash_per_block_bits) - 1);
213 *offset = idx * v->digest_size;
215 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
219 * Handle verification errors.
221 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
222 unsigned long long block)
224 char verity_env[DM_VERITY_ENV_LENGTH];
225 char *envp[] = { verity_env, NULL };
226 const char *type_str = "";
227 struct mapped_device *md = dm_table_get_md(v->ti->table);
229 /* Corruption should be visible in device status in all modes */
230 v->hash_failed = true;
232 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
238 case DM_VERITY_BLOCK_TYPE_DATA:
241 case DM_VERITY_BLOCK_TYPE_METADATA:
242 type_str = "metadata";
248 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
251 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
252 DMERR("%s: reached maximum errors", v->data_dev->name);
254 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
255 DM_VERITY_ENV_VAR_NAME, type, block);
257 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
260 if (v->mode == DM_VERITY_MODE_LOGGING)
263 if (v->mode == DM_VERITY_MODE_RESTART)
264 kernel_restart("dm-verity device corrupted");
266 if (v->mode == DM_VERITY_MODE_PANIC)
267 panic("dm-verity device corrupted");
273 * Verify hash of a metadata block pertaining to the specified data block
274 * ("block" argument) at a specified level ("level" argument).
276 * On successful return, verity_io_want_digest(v, io) contains the hash value
277 * for a lower tree level or for the data block (if we're at the lowest level).
279 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
280 * If "skip_unverified" is false, unverified buffer is hashed and verified
281 * against current value of verity_io_want_digest(v, io).
283 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
284 sector_t block, int level, bool skip_unverified,
287 struct dm_buffer *buf;
288 struct buffer_aux *aux;
294 verity_hash_at_level(v, block, level, &hash_block, &offset);
296 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
297 data = dm_bufio_get(v->bufio, hash_block, &buf);
300 * In tasklet and the hash was not in the bufio cache.
301 * Return early and resume execution from a work-queue
302 * to read the hash from disk.
307 data = dm_bufio_read(v->bufio, hash_block, &buf);
310 return PTR_ERR(data);
312 aux = dm_bufio_get_aux_data(buf);
314 if (!aux->hash_verified) {
315 if (skip_unverified) {
320 r = verity_hash(v, verity_io_hash_req(v, io),
321 data, 1 << v->hash_dev_block_bits,
322 verity_io_real_digest(v, io));
326 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
327 v->digest_size) == 0))
328 aux->hash_verified = 1;
329 else if (static_branch_unlikely(&use_tasklet_enabled) &&
332 * Error handling code (FEC included) cannot be run in a
333 * tasklet since it may sleep, so fallback to work-queue.
337 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
338 hash_block, data, NULL) == 0)
339 aux->hash_verified = 1;
340 else if (verity_handle_err(v,
341 DM_VERITY_BLOCK_TYPE_METADATA,
349 memcpy(want_digest, data, v->digest_size);
353 dm_bufio_release(buf);
358 * Find a hash for a given block, write it to digest and verify the integrity
359 * of the hash tree if necessary.
361 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
362 sector_t block, u8 *digest, bool *is_zero)
366 if (likely(v->levels)) {
368 * First, we try to get the requested hash for
369 * the current block. If the hash block itself is
370 * verified, zero is returned. If it isn't, this
371 * function returns 1 and we fall back to whole
372 * chain verification.
374 r = verity_verify_level(v, io, block, 0, true, digest);
379 memcpy(digest, v->root_digest, v->digest_size);
381 for (i = v->levels - 1; i >= 0; i--) {
382 r = verity_verify_level(v, io, block, i, false, digest);
387 if (!r && v->zero_digest)
388 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
396 * Calculates the digest for the given bio
398 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
399 struct bvec_iter *iter, struct crypto_wait *wait)
401 unsigned int todo = 1 << v->data_dev_block_bits;
402 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
403 struct scatterlist sg;
404 struct ahash_request *req = verity_io_hash_req(v, io);
409 struct bio_vec bv = bio_iter_iovec(bio, *iter);
411 sg_init_table(&sg, 1);
415 if (likely(len >= todo))
418 * Operating on a single page at a time looks suboptimal
419 * until you consider the typical block size is 4,096B.
420 * Going through this loops twice should be very rare.
422 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
423 ahash_request_set_crypt(req, &sg, NULL, len);
424 r = crypto_wait_req(crypto_ahash_update(req), wait);
426 if (unlikely(r < 0)) {
427 DMERR("%s crypto op failed: %d", __func__, r);
431 bio_advance_iter(bio, iter, len);
439 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
440 * starting from iter.
442 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
443 struct bvec_iter *iter,
444 int (*process)(struct dm_verity *v,
445 struct dm_verity_io *io, u8 *data,
448 unsigned int todo = 1 << v->data_dev_block_bits;
449 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
455 struct bio_vec bv = bio_iter_iovec(bio, *iter);
457 page = bvec_kmap_local(&bv);
460 if (likely(len >= todo))
463 r = process(v, io, page, len);
469 bio_advance_iter(bio, iter, len);
476 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
477 u8 *data, size_t len)
479 memset(data, 0, len);
484 * Moves the bio iter one data block forward.
486 static inline void verity_bv_skip_block(struct dm_verity *v,
487 struct dm_verity_io *io,
488 struct bvec_iter *iter)
490 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
492 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
496 * Verify one "dm_verity_io" structure.
498 static int verity_verify_io(struct dm_verity_io *io)
501 struct dm_verity *v = io->v;
502 #if defined(CONFIG_DM_VERITY_FEC)
503 struct bvec_iter start;
505 struct bvec_iter iter_copy;
506 struct bvec_iter *iter;
507 struct crypto_wait wait;
508 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
511 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
513 * Copy the iterator in case we need to restart
514 * verification in a work-queue.
516 iter_copy = io->iter;
521 for (b = 0; b < io->n_blocks; b++) {
523 sector_t cur_block = io->block + b;
524 struct ahash_request *req = verity_io_hash_req(v, io);
526 if (v->validated_blocks &&
527 likely(test_bit(cur_block, v->validated_blocks))) {
528 verity_bv_skip_block(v, io, iter);
532 r = verity_hash_for_block(v, io, cur_block,
533 verity_io_want_digest(v, io),
540 * If we expect a zero block, don't validate, just
543 r = verity_for_bv_block(v, io, iter,
551 r = verity_hash_init(v, req, &wait);
555 #if defined(CONFIG_DM_VERITY_FEC)
556 if (verity_fec_is_enabled(v))
559 r = verity_for_io_block(v, io, iter, &wait);
563 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
568 if (likely(memcmp(verity_io_real_digest(v, io),
569 verity_io_want_digest(v, io), v->digest_size) == 0)) {
570 if (v->validated_blocks)
571 set_bit(cur_block, v->validated_blocks);
573 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
576 * Error handling code (FEC included) cannot be run in a
577 * tasklet since it may sleep, so fallback to work-queue.
580 #if defined(CONFIG_DM_VERITY_FEC)
581 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
582 cur_block, NULL, &start) == 0) {
586 if (bio->bi_status) {
588 * Error correction failed; Just return error
592 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
602 * Skip verity work in response to I/O error when system is shutting down.
604 static inline bool verity_is_system_shutting_down(void)
606 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
607 || system_state == SYSTEM_RESTART;
611 * End one "io" structure with a given error.
613 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
615 struct dm_verity *v = io->v;
616 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
618 bio->bi_end_io = io->orig_bi_end_io;
619 bio->bi_status = status;
621 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
622 verity_fec_finish_io(io);
627 static void verity_work(struct work_struct *w)
629 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
631 io->in_tasklet = false;
633 verity_fec_init_io(io);
634 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
637 static void verity_tasklet(unsigned long data)
639 struct dm_verity_io *io = (struct dm_verity_io *)data;
642 io->in_tasklet = true;
643 err = verity_verify_io(io);
644 if (err == -EAGAIN) {
645 /* fallback to retrying with work-queue */
646 INIT_WORK(&io->work, verity_work);
647 queue_work(io->v->verify_wq, &io->work);
651 verity_finish_io(io, errno_to_blk_status(err));
654 static void verity_end_io(struct bio *bio)
656 struct dm_verity_io *io = bio->bi_private;
658 if (bio->bi_status &&
659 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
660 verity_finish_io(io, bio->bi_status);
664 if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
665 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
666 tasklet_schedule(&io->tasklet);
668 INIT_WORK(&io->work, verity_work);
669 queue_work(io->v->verify_wq, &io->work);
674 * Prefetch buffers for the specified io.
675 * The root buffer is not prefetched, it is assumed that it will be cached
678 static void verity_prefetch_io(struct work_struct *work)
680 struct dm_verity_prefetch_work *pw =
681 container_of(work, struct dm_verity_prefetch_work, work);
682 struct dm_verity *v = pw->v;
685 for (i = v->levels - 2; i >= 0; i--) {
686 sector_t hash_block_start;
687 sector_t hash_block_end;
689 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
690 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
693 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
695 cluster >>= v->data_dev_block_bits;
696 if (unlikely(!cluster))
697 goto no_prefetch_cluster;
699 if (unlikely(cluster & (cluster - 1)))
700 cluster = 1 << __fls(cluster);
702 hash_block_start &= ~(sector_t)(cluster - 1);
703 hash_block_end |= cluster - 1;
704 if (unlikely(hash_block_end >= v->hash_blocks))
705 hash_block_end = v->hash_blocks - 1;
708 dm_bufio_prefetch(v->bufio, hash_block_start,
709 hash_block_end - hash_block_start + 1);
715 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
717 sector_t block = io->block;
718 unsigned int n_blocks = io->n_blocks;
719 struct dm_verity_prefetch_work *pw;
721 if (v->validated_blocks) {
722 while (n_blocks && test_bit(block, v->validated_blocks)) {
726 while (n_blocks && test_bit(block + n_blocks - 1,
727 v->validated_blocks))
733 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
734 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
739 INIT_WORK(&pw->work, verity_prefetch_io);
742 pw->n_blocks = n_blocks;
743 queue_work(v->verify_wq, &pw->work);
747 * Bio map function. It allocates dm_verity_io structure and bio vector and
748 * fills them. Then it issues prefetches and the I/O.
750 static int verity_map(struct dm_target *ti, struct bio *bio)
752 struct dm_verity *v = ti->private;
753 struct dm_verity_io *io;
755 bio_set_dev(bio, v->data_dev->bdev);
756 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
758 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
759 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
760 DMERR_LIMIT("unaligned io");
761 return DM_MAPIO_KILL;
764 if (bio_end_sector(bio) >>
765 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
766 DMERR_LIMIT("io out of range");
767 return DM_MAPIO_KILL;
770 if (bio_data_dir(bio) == WRITE)
771 return DM_MAPIO_KILL;
773 io = dm_per_bio_data(bio, ti->per_io_data_size);
775 io->orig_bi_end_io = bio->bi_end_io;
776 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
777 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
779 bio->bi_end_io = verity_end_io;
780 bio->bi_private = io;
781 io->iter = bio->bi_iter;
783 verity_submit_prefetch(v, io);
785 submit_bio_noacct(bio);
787 return DM_MAPIO_SUBMITTED;
791 * Status: V (valid) or C (corruption found)
793 static void verity_status(struct dm_target *ti, status_type_t type,
794 unsigned int status_flags, char *result, unsigned int maxlen)
796 struct dm_verity *v = ti->private;
797 unsigned int args = 0;
802 case STATUSTYPE_INFO:
803 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
805 case STATUSTYPE_TABLE:
806 DMEMIT("%u %s %s %u %u %llu %llu %s ",
810 1 << v->data_dev_block_bits,
811 1 << v->hash_dev_block_bits,
812 (unsigned long long)v->data_blocks,
813 (unsigned long long)v->hash_start,
816 for (x = 0; x < v->digest_size; x++)
817 DMEMIT("%02x", v->root_digest[x]);
822 for (x = 0; x < v->salt_size; x++)
823 DMEMIT("%02x", v->salt[x]);
824 if (v->mode != DM_VERITY_MODE_EIO)
826 if (verity_fec_is_enabled(v))
827 args += DM_VERITY_OPTS_FEC;
830 if (v->validated_blocks)
834 if (v->signature_key_desc)
835 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
839 if (v->mode != DM_VERITY_MODE_EIO) {
842 case DM_VERITY_MODE_LOGGING:
843 DMEMIT(DM_VERITY_OPT_LOGGING);
845 case DM_VERITY_MODE_RESTART:
846 DMEMIT(DM_VERITY_OPT_RESTART);
848 case DM_VERITY_MODE_PANIC:
849 DMEMIT(DM_VERITY_OPT_PANIC);
856 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
857 if (v->validated_blocks)
858 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
860 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
861 sz = verity_fec_status_table(v, sz, result, maxlen);
862 if (v->signature_key_desc)
863 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
864 " %s", v->signature_key_desc);
868 DMEMIT_TARGET_NAME_VERSION(ti->type);
869 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
870 DMEMIT(",verity_version=%u", v->version);
871 DMEMIT(",data_device_name=%s", v->data_dev->name);
872 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
873 DMEMIT(",verity_algorithm=%s", v->alg_name);
875 DMEMIT(",root_digest=");
876 for (x = 0; x < v->digest_size; x++)
877 DMEMIT("%02x", v->root_digest[x]);
883 for (x = 0; x < v->salt_size; x++)
884 DMEMIT("%02x", v->salt[x]);
886 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
887 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
888 if (v->signature_key_desc)
889 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
891 if (v->mode != DM_VERITY_MODE_EIO) {
892 DMEMIT(",verity_mode=");
894 case DM_VERITY_MODE_LOGGING:
895 DMEMIT(DM_VERITY_OPT_LOGGING);
897 case DM_VERITY_MODE_RESTART:
898 DMEMIT(DM_VERITY_OPT_RESTART);
900 case DM_VERITY_MODE_PANIC:
901 DMEMIT(DM_VERITY_OPT_PANIC);
912 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
914 struct dm_verity *v = ti->private;
916 *bdev = v->data_dev->bdev;
918 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
923 static int verity_iterate_devices(struct dm_target *ti,
924 iterate_devices_callout_fn fn, void *data)
926 struct dm_verity *v = ti->private;
928 return fn(ti, v->data_dev, v->data_start, ti->len, data);
931 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
933 struct dm_verity *v = ti->private;
935 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
936 limits->logical_block_size = 1 << v->data_dev_block_bits;
938 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
939 limits->physical_block_size = 1 << v->data_dev_block_bits;
941 blk_limits_io_min(limits, limits->logical_block_size);
944 static void verity_dtr(struct dm_target *ti)
946 struct dm_verity *v = ti->private;
949 destroy_workqueue(v->verify_wq);
952 dm_bufio_client_destroy(v->bufio);
954 kvfree(v->validated_blocks);
956 kfree(v->root_digest);
957 kfree(v->zero_digest);
960 crypto_free_ahash(v->tfm);
965 dm_put_device(ti, v->hash_dev);
968 dm_put_device(ti, v->data_dev);
972 kfree(v->signature_key_desc);
975 static_branch_dec(&use_tasklet_enabled);
980 static int verity_alloc_most_once(struct dm_verity *v)
982 struct dm_target *ti = v->ti;
984 /* the bitset can only handle INT_MAX blocks */
985 if (v->data_blocks > INT_MAX) {
986 ti->error = "device too large to use check_at_most_once";
990 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
991 sizeof(unsigned long),
993 if (!v->validated_blocks) {
994 ti->error = "failed to allocate bitset for check_at_most_once";
1001 static int verity_alloc_zero_digest(struct dm_verity *v)
1004 struct ahash_request *req;
1007 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1009 if (!v->zero_digest)
1012 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1015 return r; /* verity_dtr will free zero_digest */
1017 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1022 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1032 static inline bool verity_is_verity_mode(const char *arg_name)
1034 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1035 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1036 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1039 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1044 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1045 v->mode = DM_VERITY_MODE_LOGGING;
1046 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1047 v->mode = DM_VERITY_MODE_RESTART;
1048 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1049 v->mode = DM_VERITY_MODE_PANIC;
1054 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1055 struct dm_verity_sig_opts *verify_args,
1056 bool only_modifier_opts)
1060 struct dm_target *ti = v->ti;
1061 const char *arg_name;
1063 static const struct dm_arg _args[] = {
1064 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1067 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1075 arg_name = dm_shift_arg(as);
1078 if (verity_is_verity_mode(arg_name)) {
1079 if (only_modifier_opts)
1081 r = verity_parse_verity_mode(v, arg_name);
1083 ti->error = "Conflicting error handling parameters";
1088 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1089 if (only_modifier_opts)
1091 r = verity_alloc_zero_digest(v);
1093 ti->error = "Cannot allocate zero digest";
1098 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1099 if (only_modifier_opts)
1101 r = verity_alloc_most_once(v);
1106 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1107 v->use_tasklet = true;
1108 static_branch_inc(&use_tasklet_enabled);
1111 } else if (verity_is_fec_opt_arg(arg_name)) {
1112 if (only_modifier_opts)
1114 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1119 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1120 if (only_modifier_opts)
1122 r = verity_verify_sig_parse_opt_args(as, v,
1129 } else if (only_modifier_opts) {
1131 * Ignore unrecognized opt, could easily be an extra
1132 * argument to an option whose parsing was skipped.
1133 * Normal parsing (@only_modifier_opts=false) will
1134 * properly parse all options (and their extra args).
1139 DMERR("Unrecognized verity feature request: %s", arg_name);
1140 ti->error = "Unrecognized verity feature request";
1142 } while (argc && !r);
1148 * Target parameters:
1149 * <version> The current format is version 1.
1150 * Vsn 0 is compatible with original Chromium OS releases.
1155 * <the number of data blocks>
1156 * <hash start block>
1159 * <salt> Hex string or "-" if no salt.
1161 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1163 struct dm_verity *v;
1164 struct dm_verity_sig_opts verify_args = {0};
1165 struct dm_arg_set as;
1167 unsigned long long num_ll;
1170 sector_t hash_position;
1172 char *root_hash_digest_to_validate;
1174 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1176 ti->error = "Cannot allocate verity structure";
1182 r = verity_fec_ctr_alloc(v);
1186 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
1187 ti->error = "Device must be readonly";
1193 ti->error = "Not enough arguments";
1198 /* Parse optional parameters that modify primary args */
1200 as.argc = argc - 10;
1201 as.argv = argv + 10;
1202 r = verity_parse_opt_args(&as, v, &verify_args, true);
1207 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1209 ti->error = "Invalid version";
1215 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1217 ti->error = "Data device lookup failed";
1221 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1223 ti->error = "Hash device lookup failed";
1227 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1228 !num || (num & (num - 1)) ||
1229 num < bdev_logical_block_size(v->data_dev->bdev) ||
1231 ti->error = "Invalid data device block size";
1235 v->data_dev_block_bits = __ffs(num);
1237 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1238 !num || (num & (num - 1)) ||
1239 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1241 ti->error = "Invalid hash device block size";
1245 v->hash_dev_block_bits = __ffs(num);
1247 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1248 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1249 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1250 ti->error = "Invalid data blocks";
1254 v->data_blocks = num_ll;
1256 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1257 ti->error = "Data device is too small";
1262 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1263 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1264 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1265 ti->error = "Invalid hash start";
1269 v->hash_start = num_ll;
1271 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1273 ti->error = "Cannot allocate algorithm name";
1278 v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1279 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1280 if (IS_ERR(v->tfm)) {
1281 ti->error = "Cannot initialize hash function";
1282 r = PTR_ERR(v->tfm);
1288 * dm-verity performance can vary greatly depending on which hash
1289 * algorithm implementation is used. Help people debug performance
1290 * problems by logging the ->cra_driver_name.
1292 DMINFO("%s using implementation \"%s\"", v->alg_name,
1293 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1295 v->digest_size = crypto_ahash_digestsize(v->tfm);
1296 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1297 ti->error = "Digest size too big";
1301 v->ahash_reqsize = sizeof(struct ahash_request) +
1302 crypto_ahash_reqsize(v->tfm);
1304 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1305 if (!v->root_digest) {
1306 ti->error = "Cannot allocate root digest";
1310 if (strlen(argv[8]) != v->digest_size * 2 ||
1311 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1312 ti->error = "Invalid root digest";
1316 root_hash_digest_to_validate = argv[8];
1318 if (strcmp(argv[9], "-")) {
1319 v->salt_size = strlen(argv[9]) / 2;
1320 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1322 ti->error = "Cannot allocate salt";
1326 if (strlen(argv[9]) != v->salt_size * 2 ||
1327 hex2bin(v->salt, argv[9], v->salt_size)) {
1328 ti->error = "Invalid salt";
1337 /* Optional parameters */
1341 r = verity_parse_opt_args(&as, v, &verify_args, false);
1346 /* Root hash signature is a optional parameter*/
1347 r = verity_verify_root_hash(root_hash_digest_to_validate,
1348 strlen(root_hash_digest_to_validate),
1350 verify_args.sig_size);
1352 ti->error = "Root hash verification failed";
1355 v->hash_per_block_bits =
1356 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1360 while (v->hash_per_block_bits * v->levels < 64 &&
1361 (unsigned long long)(v->data_blocks - 1) >>
1362 (v->hash_per_block_bits * v->levels))
1365 if (v->levels > DM_VERITY_MAX_LEVELS) {
1366 ti->error = "Too many tree levels";
1371 hash_position = v->hash_start;
1372 for (i = v->levels - 1; i >= 0; i--) {
1375 v->hash_level_block[i] = hash_position;
1376 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1377 >> ((i + 1) * v->hash_per_block_bits);
1378 if (hash_position + s < hash_position) {
1379 ti->error = "Hash device offset overflow";
1385 v->hash_blocks = hash_position;
1387 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1388 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1389 dm_bufio_alloc_callback, NULL,
1390 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1391 if (IS_ERR(v->bufio)) {
1392 ti->error = "Cannot initialize dm-bufio";
1393 r = PTR_ERR(v->bufio);
1398 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1399 ti->error = "Hash device is too small";
1405 * Using WQ_HIGHPRI improves throughput and completion latency by
1406 * reducing wait times when reading from a dm-verity device.
1408 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1409 * allows verify_wq to preempt softirq since verification in tasklet
1410 * will fall-back to using it for error handling (or if the bufio cache
1411 * doesn't have required hashes).
1413 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1414 if (!v->verify_wq) {
1415 ti->error = "Cannot allocate workqueue";
1420 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1421 v->ahash_reqsize + v->digest_size * 2;
1423 r = verity_fec_ctr(v);
1427 ti->per_io_data_size = roundup(ti->per_io_data_size,
1428 __alignof__(struct dm_verity_io));
1430 verity_verify_sig_opts_cleanup(&verify_args);
1436 verity_verify_sig_opts_cleanup(&verify_args);
1443 * Check whether a DM target is a verity target.
1445 bool dm_is_verity_target(struct dm_target *ti)
1447 return ti->type->module == THIS_MODULE;
1451 * Get the verity mode (error behavior) of a verity target.
1453 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1456 int dm_verity_get_mode(struct dm_target *ti)
1458 struct dm_verity *v = ti->private;
1460 if (!dm_is_verity_target(ti))
1467 * Get the root digest of a verity target.
1469 * Returns a copy of the root digest, the caller is responsible for
1470 * freeing the memory of the digest.
1472 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1474 struct dm_verity *v = ti->private;
1476 if (!dm_is_verity_target(ti))
1479 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1480 if (*root_digest == NULL)
1483 *digest_size = v->digest_size;
1488 static struct target_type verity_target = {
1490 .features = DM_TARGET_IMMUTABLE,
1491 .version = {1, 9, 0},
1492 .module = THIS_MODULE,
1496 .status = verity_status,
1497 .prepare_ioctl = verity_prepare_ioctl,
1498 .iterate_devices = verity_iterate_devices,
1499 .io_hints = verity_io_hints,
1502 static int __init dm_verity_init(void)
1506 r = dm_register_target(&verity_target);
1508 DMERR("register failed %d", r);
1513 static void __exit dm_verity_exit(void)
1515 dm_unregister_target(&verity_target);
1518 module_init(dm_verity_init);
1519 module_exit(dm_verity_exit);
1521 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1522 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1523 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1524 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1525 MODULE_LICENSE("GPL");