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"
20 #include <linux/module.h>
21 #include <linux/reboot.h>
22 #include <linux/scatterlist.h>
23 #include <linux/string.h>
24 #include <linux/jump_label.h>
26 #define DM_MSG_PREFIX "verity"
28 #define DM_VERITY_ENV_LENGTH 42
29 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
31 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
33 #define DM_VERITY_MAX_CORRUPTED_ERRS 100
35 #define DM_VERITY_OPT_LOGGING "ignore_corruption"
36 #define DM_VERITY_OPT_RESTART "restart_on_corruption"
37 #define DM_VERITY_OPT_PANIC "panic_on_corruption"
38 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
39 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
40 #define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
42 #define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \
43 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
45 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
47 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
49 static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
51 struct dm_verity_prefetch_work {
52 struct work_struct work;
55 unsigned int n_blocks;
59 * Auxiliary structure appended to each dm-bufio buffer. If the value
60 * hash_verified is nonzero, hash of the block has been verified.
62 * The variable hash_verified is set to 0 when allocating the buffer, then
63 * it can be changed to 1 and it is never reset to 0 again.
65 * There is no lock around this value, a race condition can at worst cause
66 * that multiple processes verify the hash of the same buffer simultaneously
67 * and write 1 to hash_verified simultaneously.
68 * This condition is harmless, so we don't need locking.
75 * Initialize struct buffer_aux for a freshly created buffer.
77 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
79 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
81 aux->hash_verified = 0;
85 * Translate input sector number to the sector number on the target device.
87 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
89 return v->data_start + dm_target_offset(v->ti, bi_sector);
93 * Return hash position of a specified block at a specified tree level
94 * (0 is the lowest level).
95 * The lowest "hash_per_block_bits"-bits of the result denote hash position
96 * inside a hash block. The remaining bits denote location of the hash block.
98 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
101 return block >> (level * v->hash_per_block_bits);
104 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
105 const u8 *data, size_t len,
106 struct crypto_wait *wait)
108 struct scatterlist sg;
110 if (likely(!is_vmalloc_addr(data))) {
111 sg_init_one(&sg, data, len);
112 ahash_request_set_crypt(req, &sg, NULL, len);
113 return crypto_wait_req(crypto_ahash_update(req), wait);
118 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
120 flush_kernel_vmap_range((void *)data, this_step);
121 sg_init_table(&sg, 1);
122 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
123 ahash_request_set_crypt(req, &sg, NULL, this_step);
124 r = crypto_wait_req(crypto_ahash_update(req), wait);
135 * Wrapper for crypto_ahash_init, which handles verity salting.
137 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
138 struct crypto_wait *wait, bool may_sleep)
142 ahash_request_set_tfm(req, v->tfm);
143 ahash_request_set_callback(req,
144 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
145 crypto_req_done, (void *)wait);
146 crypto_init_wait(wait);
148 r = crypto_wait_req(crypto_ahash_init(req), wait);
150 if (unlikely(r < 0)) {
152 DMERR("crypto_ahash_init failed: %d", r);
156 if (likely(v->salt_size && (v->version >= 1)))
157 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
162 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
163 u8 *digest, struct crypto_wait *wait)
167 if (unlikely(v->salt_size && (!v->version))) {
168 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
171 DMERR("%s failed updating salt: %d", __func__, r);
176 ahash_request_set_crypt(req, NULL, digest, 0);
177 r = crypto_wait_req(crypto_ahash_final(req), wait);
182 int verity_hash(struct dm_verity *v, struct ahash_request *req,
183 const u8 *data, size_t len, u8 *digest, bool may_sleep)
186 struct crypto_wait wait;
188 r = verity_hash_init(v, req, &wait, may_sleep);
192 r = verity_hash_update(v, req, data, len, &wait);
196 r = verity_hash_final(v, req, digest, &wait);
202 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
203 sector_t *hash_block, unsigned int *offset)
205 sector_t position = verity_position_at_level(v, block, level);
208 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
213 idx = position & ((1 << v->hash_per_block_bits) - 1);
215 *offset = idx * v->digest_size;
217 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
221 * Handle verification errors.
223 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
224 unsigned long long block)
226 char verity_env[DM_VERITY_ENV_LENGTH];
227 char *envp[] = { verity_env, NULL };
228 const char *type_str = "";
229 struct mapped_device *md = dm_table_get_md(v->ti->table);
231 /* Corruption should be visible in device status in all modes */
232 v->hash_failed = true;
234 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
240 case DM_VERITY_BLOCK_TYPE_DATA:
243 case DM_VERITY_BLOCK_TYPE_METADATA:
244 type_str = "metadata";
250 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
253 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
254 DMERR("%s: reached maximum errors", v->data_dev->name);
255 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
258 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
259 DM_VERITY_ENV_VAR_NAME, type, block);
261 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
264 if (v->mode == DM_VERITY_MODE_LOGGING)
267 if (v->mode == DM_VERITY_MODE_RESTART)
268 kernel_restart("dm-verity device corrupted");
270 if (v->mode == DM_VERITY_MODE_PANIC)
271 panic("dm-verity device corrupted");
277 * Verify hash of a metadata block pertaining to the specified data block
278 * ("block" argument) at a specified level ("level" argument).
280 * On successful return, verity_io_want_digest(v, io) contains the hash value
281 * for a lower tree level or for the data block (if we're at the lowest level).
283 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
284 * If "skip_unverified" is false, unverified buffer is hashed and verified
285 * against current value of verity_io_want_digest(v, io).
287 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
288 sector_t block, int level, bool skip_unverified,
291 struct dm_buffer *buf;
292 struct buffer_aux *aux;
298 verity_hash_at_level(v, block, level, &hash_block, &offset);
300 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
301 data = dm_bufio_get(v->bufio, hash_block, &buf);
304 * In tasklet and the hash was not in the bufio cache.
305 * Return early and resume execution from a work-queue
306 * to read the hash from disk.
311 data = dm_bufio_read(v->bufio, hash_block, &buf);
314 return PTR_ERR(data);
316 aux = dm_bufio_get_aux_data(buf);
318 if (!aux->hash_verified) {
319 if (skip_unverified) {
324 r = verity_hash(v, verity_io_hash_req(v, io),
325 data, 1 << v->hash_dev_block_bits,
326 verity_io_real_digest(v, io), !io->in_tasklet);
330 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
331 v->digest_size) == 0))
332 aux->hash_verified = 1;
333 else if (static_branch_unlikely(&use_tasklet_enabled) &&
336 * Error handling code (FEC included) cannot be run in a
337 * tasklet since it may sleep, so fallback to work-queue.
341 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
342 hash_block, data, NULL) == 0)
343 aux->hash_verified = 1;
344 else if (verity_handle_err(v,
345 DM_VERITY_BLOCK_TYPE_METADATA,
348 dm_bio_from_per_bio_data(io,
349 v->ti->per_io_data_size);
350 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
358 memcpy(want_digest, data, v->digest_size);
362 dm_bufio_release(buf);
367 * Find a hash for a given block, write it to digest and verify the integrity
368 * of the hash tree if necessary.
370 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
371 sector_t block, u8 *digest, bool *is_zero)
375 if (likely(v->levels)) {
377 * First, we try to get the requested hash for
378 * the current block. If the hash block itself is
379 * verified, zero is returned. If it isn't, this
380 * function returns 1 and we fall back to whole
381 * chain verification.
383 r = verity_verify_level(v, io, block, 0, true, digest);
388 memcpy(digest, v->root_digest, v->digest_size);
390 for (i = v->levels - 1; i >= 0; i--) {
391 r = verity_verify_level(v, io, block, i, false, digest);
396 if (!r && v->zero_digest)
397 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
405 * Calculates the digest for the given bio
407 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
408 struct bvec_iter *iter, struct crypto_wait *wait)
410 unsigned int todo = 1 << v->data_dev_block_bits;
411 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
412 struct scatterlist sg;
413 struct ahash_request *req = verity_io_hash_req(v, io);
418 struct bio_vec bv = bio_iter_iovec(bio, *iter);
420 sg_init_table(&sg, 1);
424 if (likely(len >= todo))
427 * Operating on a single page at a time looks suboptimal
428 * until you consider the typical block size is 4,096B.
429 * Going through this loops twice should be very rare.
431 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
432 ahash_request_set_crypt(req, &sg, NULL, len);
433 r = crypto_wait_req(crypto_ahash_update(req), wait);
435 if (unlikely(r < 0)) {
436 DMERR("%s crypto op failed: %d", __func__, r);
440 bio_advance_iter(bio, iter, len);
448 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
449 * starting from iter.
451 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
452 struct bvec_iter *iter,
453 int (*process)(struct dm_verity *v,
454 struct dm_verity_io *io, u8 *data,
457 unsigned int todo = 1 << v->data_dev_block_bits;
458 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
464 struct bio_vec bv = bio_iter_iovec(bio, *iter);
466 page = bvec_kmap_local(&bv);
469 if (likely(len >= todo))
472 r = process(v, io, page, len);
478 bio_advance_iter(bio, iter, len);
485 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
486 u8 *data, size_t len)
488 memset(data, 0, len);
493 * Moves the bio iter one data block forward.
495 static inline void verity_bv_skip_block(struct dm_verity *v,
496 struct dm_verity_io *io,
497 struct bvec_iter *iter)
499 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
501 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
505 * Verify one "dm_verity_io" structure.
507 static int verity_verify_io(struct dm_verity_io *io)
510 struct dm_verity *v = io->v;
511 #if defined(CONFIG_DM_VERITY_FEC)
512 struct bvec_iter start;
514 struct bvec_iter iter_copy;
515 struct bvec_iter *iter;
516 struct crypto_wait wait;
517 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
520 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
522 * Copy the iterator in case we need to restart
523 * verification in a work-queue.
525 iter_copy = io->iter;
530 for (b = 0; b < io->n_blocks; b++) {
532 sector_t cur_block = io->block + b;
533 struct ahash_request *req = verity_io_hash_req(v, io);
535 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
536 likely(test_bit(cur_block, v->validated_blocks))) {
537 verity_bv_skip_block(v, io, iter);
541 r = verity_hash_for_block(v, io, cur_block,
542 verity_io_want_digest(v, io),
549 * If we expect a zero block, don't validate, just
552 r = verity_for_bv_block(v, io, iter,
560 r = verity_hash_init(v, req, &wait, !io->in_tasklet);
564 #if defined(CONFIG_DM_VERITY_FEC)
565 if (verity_fec_is_enabled(v))
568 r = verity_for_io_block(v, io, iter, &wait);
572 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
577 if (likely(memcmp(verity_io_real_digest(v, io),
578 verity_io_want_digest(v, io), v->digest_size) == 0)) {
579 if (v->validated_blocks)
580 set_bit(cur_block, v->validated_blocks);
582 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
585 * Error handling code (FEC included) cannot be run in a
586 * tasklet since it may sleep, so fallback to work-queue.
589 #if defined(CONFIG_DM_VERITY_FEC)
590 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
591 cur_block, NULL, &start) == 0) {
595 if (bio->bi_status) {
597 * Error correction failed; Just return error
601 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
603 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
614 * Skip verity work in response to I/O error when system is shutting down.
616 static inline bool verity_is_system_shutting_down(void)
618 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
619 || system_state == SYSTEM_RESTART;
623 * End one "io" structure with a given error.
625 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
627 struct dm_verity *v = io->v;
628 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
630 bio->bi_end_io = io->orig_bi_end_io;
631 bio->bi_status = status;
633 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
634 verity_fec_finish_io(io);
639 static void verity_work(struct work_struct *w)
641 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
643 io->in_tasklet = false;
645 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
648 static void verity_tasklet(unsigned long data)
650 struct dm_verity_io *io = (struct dm_verity_io *)data;
653 io->in_tasklet = true;
654 err = verity_verify_io(io);
655 if (err == -EAGAIN || err == -ENOMEM) {
656 /* fallback to retrying with work-queue */
657 INIT_WORK(&io->work, verity_work);
658 queue_work(io->v->verify_wq, &io->work);
662 verity_finish_io(io, errno_to_blk_status(err));
665 static void verity_end_io(struct bio *bio)
667 struct dm_verity_io *io = bio->bi_private;
669 if (bio->bi_status &&
670 (!verity_fec_is_enabled(io->v) ||
671 verity_is_system_shutting_down() ||
672 (bio->bi_opf & REQ_RAHEAD))) {
673 verity_finish_io(io, bio->bi_status);
677 if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
678 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
679 tasklet_schedule(&io->tasklet);
681 INIT_WORK(&io->work, verity_work);
682 queue_work(io->v->verify_wq, &io->work);
687 * Prefetch buffers for the specified io.
688 * The root buffer is not prefetched, it is assumed that it will be cached
691 static void verity_prefetch_io(struct work_struct *work)
693 struct dm_verity_prefetch_work *pw =
694 container_of(work, struct dm_verity_prefetch_work, work);
695 struct dm_verity *v = pw->v;
698 for (i = v->levels - 2; i >= 0; i--) {
699 sector_t hash_block_start;
700 sector_t hash_block_end;
702 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
703 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
706 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
708 cluster >>= v->data_dev_block_bits;
709 if (unlikely(!cluster))
710 goto no_prefetch_cluster;
712 if (unlikely(cluster & (cluster - 1)))
713 cluster = 1 << __fls(cluster);
715 hash_block_start &= ~(sector_t)(cluster - 1);
716 hash_block_end |= cluster - 1;
717 if (unlikely(hash_block_end >= v->hash_blocks))
718 hash_block_end = v->hash_blocks - 1;
721 dm_bufio_prefetch(v->bufio, hash_block_start,
722 hash_block_end - hash_block_start + 1);
728 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
730 sector_t block = io->block;
731 unsigned int n_blocks = io->n_blocks;
732 struct dm_verity_prefetch_work *pw;
734 if (v->validated_blocks) {
735 while (n_blocks && test_bit(block, v->validated_blocks)) {
739 while (n_blocks && test_bit(block + n_blocks - 1,
740 v->validated_blocks))
746 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
747 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
752 INIT_WORK(&pw->work, verity_prefetch_io);
755 pw->n_blocks = n_blocks;
756 queue_work(v->verify_wq, &pw->work);
760 * Bio map function. It allocates dm_verity_io structure and bio vector and
761 * fills them. Then it issues prefetches and the I/O.
763 static int verity_map(struct dm_target *ti, struct bio *bio)
765 struct dm_verity *v = ti->private;
766 struct dm_verity_io *io;
768 bio_set_dev(bio, v->data_dev->bdev);
769 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
771 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
772 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
773 DMERR_LIMIT("unaligned io");
774 return DM_MAPIO_KILL;
777 if (bio_end_sector(bio) >>
778 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
779 DMERR_LIMIT("io out of range");
780 return DM_MAPIO_KILL;
783 if (bio_data_dir(bio) == WRITE)
784 return DM_MAPIO_KILL;
786 io = dm_per_bio_data(bio, ti->per_io_data_size);
788 io->orig_bi_end_io = bio->bi_end_io;
789 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
790 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
792 bio->bi_end_io = verity_end_io;
793 bio->bi_private = io;
794 io->iter = bio->bi_iter;
796 verity_fec_init_io(io);
798 verity_submit_prefetch(v, io);
800 submit_bio_noacct(bio);
802 return DM_MAPIO_SUBMITTED;
806 * Status: V (valid) or C (corruption found)
808 static void verity_status(struct dm_target *ti, status_type_t type,
809 unsigned int status_flags, char *result, unsigned int maxlen)
811 struct dm_verity *v = ti->private;
812 unsigned int args = 0;
817 case STATUSTYPE_INFO:
818 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
820 case STATUSTYPE_TABLE:
821 DMEMIT("%u %s %s %u %u %llu %llu %s ",
825 1 << v->data_dev_block_bits,
826 1 << v->hash_dev_block_bits,
827 (unsigned long long)v->data_blocks,
828 (unsigned long long)v->hash_start,
831 for (x = 0; x < v->digest_size; x++)
832 DMEMIT("%02x", v->root_digest[x]);
837 for (x = 0; x < v->salt_size; x++)
838 DMEMIT("%02x", v->salt[x]);
839 if (v->mode != DM_VERITY_MODE_EIO)
841 if (verity_fec_is_enabled(v))
842 args += DM_VERITY_OPTS_FEC;
845 if (v->validated_blocks)
849 if (v->signature_key_desc)
850 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
854 if (v->mode != DM_VERITY_MODE_EIO) {
857 case DM_VERITY_MODE_LOGGING:
858 DMEMIT(DM_VERITY_OPT_LOGGING);
860 case DM_VERITY_MODE_RESTART:
861 DMEMIT(DM_VERITY_OPT_RESTART);
863 case DM_VERITY_MODE_PANIC:
864 DMEMIT(DM_VERITY_OPT_PANIC);
871 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
872 if (v->validated_blocks)
873 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
875 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
876 sz = verity_fec_status_table(v, sz, result, maxlen);
877 if (v->signature_key_desc)
878 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
879 " %s", v->signature_key_desc);
883 DMEMIT_TARGET_NAME_VERSION(ti->type);
884 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
885 DMEMIT(",verity_version=%u", v->version);
886 DMEMIT(",data_device_name=%s", v->data_dev->name);
887 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
888 DMEMIT(",verity_algorithm=%s", v->alg_name);
890 DMEMIT(",root_digest=");
891 for (x = 0; x < v->digest_size; x++)
892 DMEMIT("%02x", v->root_digest[x]);
898 for (x = 0; x < v->salt_size; x++)
899 DMEMIT("%02x", v->salt[x]);
901 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
902 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
903 if (v->signature_key_desc)
904 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
906 if (v->mode != DM_VERITY_MODE_EIO) {
907 DMEMIT(",verity_mode=");
909 case DM_VERITY_MODE_LOGGING:
910 DMEMIT(DM_VERITY_OPT_LOGGING);
912 case DM_VERITY_MODE_RESTART:
913 DMEMIT(DM_VERITY_OPT_RESTART);
915 case DM_VERITY_MODE_PANIC:
916 DMEMIT(DM_VERITY_OPT_PANIC);
927 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
929 struct dm_verity *v = ti->private;
931 *bdev = v->data_dev->bdev;
933 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
938 static int verity_iterate_devices(struct dm_target *ti,
939 iterate_devices_callout_fn fn, void *data)
941 struct dm_verity *v = ti->private;
943 return fn(ti, v->data_dev, v->data_start, ti->len, data);
946 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
948 struct dm_verity *v = ti->private;
950 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
951 limits->logical_block_size = 1 << v->data_dev_block_bits;
953 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
954 limits->physical_block_size = 1 << v->data_dev_block_bits;
956 blk_limits_io_min(limits, limits->logical_block_size);
959 static void verity_dtr(struct dm_target *ti)
961 struct dm_verity *v = ti->private;
964 destroy_workqueue(v->verify_wq);
967 dm_bufio_client_destroy(v->bufio);
969 kvfree(v->validated_blocks);
971 kfree(v->root_digest);
972 kfree(v->zero_digest);
975 crypto_free_ahash(v->tfm);
980 dm_put_device(ti, v->hash_dev);
983 dm_put_device(ti, v->data_dev);
987 kfree(v->signature_key_desc);
990 static_branch_dec(&use_tasklet_enabled);
994 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
997 static int verity_alloc_most_once(struct dm_verity *v)
999 struct dm_target *ti = v->ti;
1001 /* the bitset can only handle INT_MAX blocks */
1002 if (v->data_blocks > INT_MAX) {
1003 ti->error = "device too large to use check_at_most_once";
1007 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1008 sizeof(unsigned long),
1010 if (!v->validated_blocks) {
1011 ti->error = "failed to allocate bitset for check_at_most_once";
1018 static int verity_alloc_zero_digest(struct dm_verity *v)
1021 struct ahash_request *req;
1024 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1026 if (!v->zero_digest)
1029 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1032 return r; /* verity_dtr will free zero_digest */
1034 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1039 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1040 v->zero_digest, true);
1049 static inline bool verity_is_verity_mode(const char *arg_name)
1051 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1052 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1053 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1056 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1061 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1062 v->mode = DM_VERITY_MODE_LOGGING;
1063 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1064 v->mode = DM_VERITY_MODE_RESTART;
1065 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1066 v->mode = DM_VERITY_MODE_PANIC;
1071 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1072 struct dm_verity_sig_opts *verify_args,
1073 bool only_modifier_opts)
1077 struct dm_target *ti = v->ti;
1078 const char *arg_name;
1080 static const struct dm_arg _args[] = {
1081 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1084 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1092 arg_name = dm_shift_arg(as);
1095 if (verity_is_verity_mode(arg_name)) {
1096 if (only_modifier_opts)
1098 r = verity_parse_verity_mode(v, arg_name);
1100 ti->error = "Conflicting error handling parameters";
1105 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1106 if (only_modifier_opts)
1108 r = verity_alloc_zero_digest(v);
1110 ti->error = "Cannot allocate zero digest";
1115 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1116 if (only_modifier_opts)
1118 r = verity_alloc_most_once(v);
1123 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1124 v->use_tasklet = true;
1125 static_branch_inc(&use_tasklet_enabled);
1128 } else if (verity_is_fec_opt_arg(arg_name)) {
1129 if (only_modifier_opts)
1131 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1136 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1137 if (only_modifier_opts)
1139 r = verity_verify_sig_parse_opt_args(as, v,
1146 } else if (only_modifier_opts) {
1148 * Ignore unrecognized opt, could easily be an extra
1149 * argument to an option whose parsing was skipped.
1150 * Normal parsing (@only_modifier_opts=false) will
1151 * properly parse all options (and their extra args).
1156 DMERR("Unrecognized verity feature request: %s", arg_name);
1157 ti->error = "Unrecognized verity feature request";
1159 } while (argc && !r);
1165 * Target parameters:
1166 * <version> The current format is version 1.
1167 * Vsn 0 is compatible with original Chromium OS releases.
1172 * <the number of data blocks>
1173 * <hash start block>
1176 * <salt> Hex string or "-" if no salt.
1178 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1180 struct dm_verity *v;
1181 struct dm_verity_sig_opts verify_args = {0};
1182 struct dm_arg_set as;
1184 unsigned long long num_ll;
1187 sector_t hash_position;
1189 char *root_hash_digest_to_validate;
1191 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1193 ti->error = "Cannot allocate verity structure";
1199 r = verity_fec_ctr_alloc(v);
1203 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1204 ti->error = "Device must be readonly";
1210 ti->error = "Not enough arguments";
1215 /* Parse optional parameters that modify primary args */
1217 as.argc = argc - 10;
1218 as.argv = argv + 10;
1219 r = verity_parse_opt_args(&as, v, &verify_args, true);
1224 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1226 ti->error = "Invalid version";
1232 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1234 ti->error = "Data device lookup failed";
1238 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1240 ti->error = "Hash device lookup failed";
1244 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1245 !num || (num & (num - 1)) ||
1246 num < bdev_logical_block_size(v->data_dev->bdev) ||
1248 ti->error = "Invalid data device block size";
1252 v->data_dev_block_bits = __ffs(num);
1254 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1255 !num || (num & (num - 1)) ||
1256 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1258 ti->error = "Invalid hash device block size";
1262 v->hash_dev_block_bits = __ffs(num);
1264 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1265 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1266 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1267 ti->error = "Invalid data blocks";
1271 v->data_blocks = num_ll;
1273 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1274 ti->error = "Data device is too small";
1279 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1280 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1281 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1282 ti->error = "Invalid hash start";
1286 v->hash_start = num_ll;
1288 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1290 ti->error = "Cannot allocate algorithm name";
1295 v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1296 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1297 if (IS_ERR(v->tfm)) {
1298 ti->error = "Cannot initialize hash function";
1299 r = PTR_ERR(v->tfm);
1305 * dm-verity performance can vary greatly depending on which hash
1306 * algorithm implementation is used. Help people debug performance
1307 * problems by logging the ->cra_driver_name.
1309 DMINFO("%s using implementation \"%s\"", v->alg_name,
1310 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1312 v->digest_size = crypto_ahash_digestsize(v->tfm);
1313 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1314 ti->error = "Digest size too big";
1318 v->ahash_reqsize = sizeof(struct ahash_request) +
1319 crypto_ahash_reqsize(v->tfm);
1321 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1322 if (!v->root_digest) {
1323 ti->error = "Cannot allocate root digest";
1327 if (strlen(argv[8]) != v->digest_size * 2 ||
1328 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1329 ti->error = "Invalid root digest";
1333 root_hash_digest_to_validate = argv[8];
1335 if (strcmp(argv[9], "-")) {
1336 v->salt_size = strlen(argv[9]) / 2;
1337 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1339 ti->error = "Cannot allocate salt";
1343 if (strlen(argv[9]) != v->salt_size * 2 ||
1344 hex2bin(v->salt, argv[9], v->salt_size)) {
1345 ti->error = "Invalid salt";
1354 /* Optional parameters */
1358 r = verity_parse_opt_args(&as, v, &verify_args, false);
1363 /* Root hash signature is a optional parameter*/
1364 r = verity_verify_root_hash(root_hash_digest_to_validate,
1365 strlen(root_hash_digest_to_validate),
1367 verify_args.sig_size);
1369 ti->error = "Root hash verification failed";
1372 v->hash_per_block_bits =
1373 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1377 while (v->hash_per_block_bits * v->levels < 64 &&
1378 (unsigned long long)(v->data_blocks - 1) >>
1379 (v->hash_per_block_bits * v->levels))
1382 if (v->levels > DM_VERITY_MAX_LEVELS) {
1383 ti->error = "Too many tree levels";
1388 hash_position = v->hash_start;
1389 for (i = v->levels - 1; i >= 0; i--) {
1392 v->hash_level_block[i] = hash_position;
1393 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1394 >> ((i + 1) * v->hash_per_block_bits);
1395 if (hash_position + s < hash_position) {
1396 ti->error = "Hash device offset overflow";
1402 v->hash_blocks = hash_position;
1404 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1405 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1406 dm_bufio_alloc_callback, NULL,
1407 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1408 if (IS_ERR(v->bufio)) {
1409 ti->error = "Cannot initialize dm-bufio";
1410 r = PTR_ERR(v->bufio);
1415 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1416 ti->error = "Hash device is too small";
1422 * Using WQ_HIGHPRI improves throughput and completion latency by
1423 * reducing wait times when reading from a dm-verity device.
1425 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1426 * allows verify_wq to preempt softirq since verification in tasklet
1427 * will fall-back to using it for error handling (or if the bufio cache
1428 * doesn't have required hashes).
1430 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1431 if (!v->verify_wq) {
1432 ti->error = "Cannot allocate workqueue";
1437 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1438 v->ahash_reqsize + v->digest_size * 2;
1440 r = verity_fec_ctr(v);
1444 ti->per_io_data_size = roundup(ti->per_io_data_size,
1445 __alignof__(struct dm_verity_io));
1447 verity_verify_sig_opts_cleanup(&verify_args);
1449 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1455 verity_verify_sig_opts_cleanup(&verify_args);
1456 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1463 * Check whether a DM target is a verity target.
1465 bool dm_is_verity_target(struct dm_target *ti)
1467 return ti->type->module == THIS_MODULE;
1471 * Get the verity mode (error behavior) of a verity target.
1473 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1476 int dm_verity_get_mode(struct dm_target *ti)
1478 struct dm_verity *v = ti->private;
1480 if (!dm_is_verity_target(ti))
1487 * Get the root digest of a verity target.
1489 * Returns a copy of the root digest, the caller is responsible for
1490 * freeing the memory of the digest.
1492 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1494 struct dm_verity *v = ti->private;
1496 if (!dm_is_verity_target(ti))
1499 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1500 if (*root_digest == NULL)
1503 *digest_size = v->digest_size;
1508 static struct target_type verity_target = {
1510 .features = DM_TARGET_IMMUTABLE,
1511 .version = {1, 9, 0},
1512 .module = THIS_MODULE,
1516 .status = verity_status,
1517 .prepare_ioctl = verity_prepare_ioctl,
1518 .iterate_devices = verity_iterate_devices,
1519 .io_hints = verity_io_hints,
1523 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1524 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1525 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1526 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1527 MODULE_LICENSE("GPL");