Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat, Inc.
4 *
5 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 *
7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
8 *
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
13 * access behavior.
14 */
15
16#include "dm-verity.h"
17#include "dm-verity-fec.h"
18#include "dm-verity-verify-sig.h"
19#include "dm-audit.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>
25#include <linux/security.h>
26
27#define DM_MSG_PREFIX "verity"
28
29#define DM_VERITY_ENV_LENGTH 42
30#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
31
32#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
33
34#define DM_VERITY_MAX_CORRUPTED_ERRS 100
35
36#define DM_VERITY_OPT_LOGGING "ignore_corruption"
37#define DM_VERITY_OPT_RESTART "restart_on_corruption"
38#define DM_VERITY_OPT_PANIC "panic_on_corruption"
39#define DM_VERITY_OPT_ERROR_RESTART "restart_on_error"
40#define DM_VERITY_OPT_ERROR_PANIC "panic_on_error"
41#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
42#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
43#define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
44
45#define DM_VERITY_OPTS_MAX (5 + DM_VERITY_OPTS_FEC + \
46 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
47
48static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
49
50module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
51
52static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
53
54/* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
55static DEFINE_STATIC_KEY_FALSE(ahash_enabled);
56
57struct dm_verity_prefetch_work {
58 struct work_struct work;
59 struct dm_verity *v;
60 unsigned short ioprio;
61 sector_t block;
62 unsigned int n_blocks;
63};
64
65/*
66 * Auxiliary structure appended to each dm-bufio buffer. If the value
67 * hash_verified is nonzero, hash of the block has been verified.
68 *
69 * The variable hash_verified is set to 0 when allocating the buffer, then
70 * it can be changed to 1 and it is never reset to 0 again.
71 *
72 * There is no lock around this value, a race condition can at worst cause
73 * that multiple processes verify the hash of the same buffer simultaneously
74 * and write 1 to hash_verified simultaneously.
75 * This condition is harmless, so we don't need locking.
76 */
77struct buffer_aux {
78 int hash_verified;
79};
80
81/*
82 * Initialize struct buffer_aux for a freshly created buffer.
83 */
84static void dm_bufio_alloc_callback(struct dm_buffer *buf)
85{
86 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
87
88 aux->hash_verified = 0;
89}
90
91/*
92 * Translate input sector number to the sector number on the target device.
93 */
94static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
95{
96 return dm_target_offset(v->ti, bi_sector);
97}
98
99/*
100 * Return hash position of a specified block at a specified tree level
101 * (0 is the lowest level).
102 * The lowest "hash_per_block_bits"-bits of the result denote hash position
103 * inside a hash block. The remaining bits denote location of the hash block.
104 */
105static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
106 int level)
107{
108 return block >> (level * v->hash_per_block_bits);
109}
110
111static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req,
112 const u8 *data, size_t len,
113 struct crypto_wait *wait)
114{
115 struct scatterlist sg;
116
117 if (likely(!is_vmalloc_addr(data))) {
118 sg_init_one(&sg, data, len);
119 ahash_request_set_crypt(req, &sg, NULL, len);
120 return crypto_wait_req(crypto_ahash_update(req), wait);
121 }
122
123 do {
124 int r;
125 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
126
127 flush_kernel_vmap_range((void *)data, this_step);
128 sg_init_table(&sg, 1);
129 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
130 ahash_request_set_crypt(req, &sg, NULL, this_step);
131 r = crypto_wait_req(crypto_ahash_update(req), wait);
132 if (unlikely(r))
133 return r;
134 data += this_step;
135 len -= this_step;
136 } while (len);
137
138 return 0;
139}
140
141/*
142 * Wrapper for crypto_ahash_init, which handles verity salting.
143 */
144static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req,
145 struct crypto_wait *wait, bool may_sleep)
146{
147 int r;
148
149 ahash_request_set_tfm(req, v->ahash_tfm);
150 ahash_request_set_callback(req,
151 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
152 crypto_req_done, (void *)wait);
153 crypto_init_wait(wait);
154
155 r = crypto_wait_req(crypto_ahash_init(req), wait);
156
157 if (unlikely(r < 0)) {
158 if (r != -ENOMEM)
159 DMERR("crypto_ahash_init failed: %d", r);
160 return r;
161 }
162
163 if (likely(v->salt_size && (v->version >= 1)))
164 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
165
166 return r;
167}
168
169static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req,
170 u8 *digest, struct crypto_wait *wait)
171{
172 int r;
173
174 if (unlikely(v->salt_size && (!v->version))) {
175 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
176
177 if (r < 0) {
178 DMERR("%s failed updating salt: %d", __func__, r);
179 goto out;
180 }
181 }
182
183 ahash_request_set_crypt(req, NULL, digest, 0);
184 r = crypto_wait_req(crypto_ahash_final(req), wait);
185out:
186 return r;
187}
188
189int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
190 const u8 *data, size_t len, u8 *digest, bool may_sleep)
191{
192 int r;
193
194 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) {
195 struct ahash_request *req = verity_io_hash_req(v, io);
196 struct crypto_wait wait;
197
198 r = verity_ahash_init(v, req, &wait, may_sleep) ?:
199 verity_ahash_update(v, req, data, len, &wait) ?:
200 verity_ahash_final(v, req, digest, &wait);
201 } else {
202 struct shash_desc *desc = verity_io_hash_req(v, io);
203
204 desc->tfm = v->shash_tfm;
205 r = crypto_shash_import(desc, v->initial_hashstate) ?:
206 crypto_shash_finup(desc, data, len, digest);
207 }
208 if (unlikely(r))
209 DMERR("Error hashing block: %d", r);
210 return r;
211}
212
213static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
214 sector_t *hash_block, unsigned int *offset)
215{
216 sector_t position = verity_position_at_level(v, block, level);
217 unsigned int idx;
218
219 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
220
221 if (!offset)
222 return;
223
224 idx = position & ((1 << v->hash_per_block_bits) - 1);
225 if (!v->version)
226 *offset = idx * v->digest_size;
227 else
228 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
229}
230
231/*
232 * Handle verification errors.
233 */
234static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
235 unsigned long long block)
236{
237 char verity_env[DM_VERITY_ENV_LENGTH];
238 char *envp[] = { verity_env, NULL };
239 const char *type_str = "";
240 struct mapped_device *md = dm_table_get_md(v->ti->table);
241
242 /* Corruption should be visible in device status in all modes */
243 v->hash_failed = true;
244
245 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
246 goto out;
247
248 v->corrupted_errs++;
249
250 switch (type) {
251 case DM_VERITY_BLOCK_TYPE_DATA:
252 type_str = "data";
253 break;
254 case DM_VERITY_BLOCK_TYPE_METADATA:
255 type_str = "metadata";
256 break;
257 default:
258 BUG();
259 }
260
261 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
262 type_str, block);
263
264 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
265 DMERR("%s: reached maximum errors", v->data_dev->name);
266 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
267 }
268
269 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
270 DM_VERITY_ENV_VAR_NAME, type, block);
271
272 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
273
274out:
275 if (v->mode == DM_VERITY_MODE_LOGGING)
276 return 0;
277
278 if (v->mode == DM_VERITY_MODE_RESTART)
279 kernel_restart("dm-verity device corrupted");
280
281 if (v->mode == DM_VERITY_MODE_PANIC)
282 panic("dm-verity device corrupted");
283
284 return 1;
285}
286
287/*
288 * Verify hash of a metadata block pertaining to the specified data block
289 * ("block" argument) at a specified level ("level" argument).
290 *
291 * On successful return, verity_io_want_digest(v, io) contains the hash value
292 * for a lower tree level or for the data block (if we're at the lowest level).
293 *
294 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
295 * If "skip_unverified" is false, unverified buffer is hashed and verified
296 * against current value of verity_io_want_digest(v, io).
297 */
298static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
299 sector_t block, int level, bool skip_unverified,
300 u8 *want_digest)
301{
302 struct dm_buffer *buf;
303 struct buffer_aux *aux;
304 u8 *data;
305 int r;
306 sector_t hash_block;
307 unsigned int offset;
308 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
309
310 verity_hash_at_level(v, block, level, &hash_block, &offset);
311
312 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
313 data = dm_bufio_get(v->bufio, hash_block, &buf);
314 if (data == NULL) {
315 /*
316 * In tasklet and the hash was not in the bufio cache.
317 * Return early and resume execution from a work-queue
318 * to read the hash from disk.
319 */
320 return -EAGAIN;
321 }
322 } else {
323 data = dm_bufio_read_with_ioprio(v->bufio, hash_block,
324 &buf, bio_prio(bio));
325 }
326
327 if (IS_ERR(data))
328 return PTR_ERR(data);
329
330 aux = dm_bufio_get_aux_data(buf);
331
332 if (!aux->hash_verified) {
333 if (skip_unverified) {
334 r = 1;
335 goto release_ret_r;
336 }
337
338 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits,
339 verity_io_real_digest(v, io), !io->in_bh);
340 if (unlikely(r < 0))
341 goto release_ret_r;
342
343 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
344 v->digest_size) == 0))
345 aux->hash_verified = 1;
346 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
347 /*
348 * Error handling code (FEC included) cannot be run in a
349 * tasklet since it may sleep, so fallback to work-queue.
350 */
351 r = -EAGAIN;
352 goto release_ret_r;
353 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
354 hash_block, data) == 0)
355 aux->hash_verified = 1;
356 else if (verity_handle_err(v,
357 DM_VERITY_BLOCK_TYPE_METADATA,
358 hash_block)) {
359 struct bio *bio;
360 io->had_mismatch = true;
361 bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
362 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
363 block, 0);
364 r = -EIO;
365 goto release_ret_r;
366 }
367 }
368
369 data += offset;
370 memcpy(want_digest, data, v->digest_size);
371 r = 0;
372
373release_ret_r:
374 dm_bufio_release(buf);
375 return r;
376}
377
378/*
379 * Find a hash for a given block, write it to digest and verify the integrity
380 * of the hash tree if necessary.
381 */
382int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
383 sector_t block, u8 *digest, bool *is_zero)
384{
385 int r = 0, i;
386
387 if (likely(v->levels)) {
388 /*
389 * First, we try to get the requested hash for
390 * the current block. If the hash block itself is
391 * verified, zero is returned. If it isn't, this
392 * function returns 1 and we fall back to whole
393 * chain verification.
394 */
395 r = verity_verify_level(v, io, block, 0, true, digest);
396 if (likely(r <= 0))
397 goto out;
398 }
399
400 memcpy(digest, v->root_digest, v->digest_size);
401
402 for (i = v->levels - 1; i >= 0; i--) {
403 r = verity_verify_level(v, io, block, i, false, digest);
404 if (unlikely(r))
405 goto out;
406 }
407out:
408 if (!r && v->zero_digest)
409 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
410 else
411 *is_zero = false;
412
413 return r;
414}
415
416static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
417 sector_t cur_block, u8 *dest)
418{
419 struct page *page;
420 void *buffer;
421 int r;
422 struct dm_io_request io_req;
423 struct dm_io_region io_loc;
424
425 page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
426 buffer = page_to_virt(page);
427
428 io_req.bi_opf = REQ_OP_READ;
429 io_req.mem.type = DM_IO_KMEM;
430 io_req.mem.ptr.addr = buffer;
431 io_req.notify.fn = NULL;
432 io_req.client = v->io;
433 io_loc.bdev = v->data_dev->bdev;
434 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
435 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
436 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
437 if (unlikely(r))
438 goto free_ret;
439
440 r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
441 verity_io_real_digest(v, io), true);
442 if (unlikely(r))
443 goto free_ret;
444
445 if (memcmp(verity_io_real_digest(v, io),
446 verity_io_want_digest(v, io), v->digest_size)) {
447 r = -EIO;
448 goto free_ret;
449 }
450
451 memcpy(dest, buffer, 1 << v->data_dev_block_bits);
452 r = 0;
453free_ret:
454 mempool_free(page, &v->recheck_pool);
455
456 return r;
457}
458
459static int verity_handle_data_hash_mismatch(struct dm_verity *v,
460 struct dm_verity_io *io,
461 struct bio *bio, sector_t blkno,
462 u8 *data)
463{
464 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
465 /*
466 * Error handling code (FEC included) cannot be run in the
467 * BH workqueue, so fallback to a standard workqueue.
468 */
469 return -EAGAIN;
470 }
471 if (verity_recheck(v, io, blkno, data) == 0) {
472 if (v->validated_blocks)
473 set_bit(blkno, v->validated_blocks);
474 return 0;
475 }
476#if defined(CONFIG_DM_VERITY_FEC)
477 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno,
478 data) == 0)
479 return 0;
480#endif
481 if (bio->bi_status)
482 return -EIO; /* Error correction failed; Just return error */
483
484 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
485 io->had_mismatch = true;
486 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
487 return -EIO;
488 }
489 return 0;
490}
491
492/*
493 * Verify one "dm_verity_io" structure.
494 */
495static int verity_verify_io(struct dm_verity_io *io)
496{
497 struct dm_verity *v = io->v;
498 const unsigned int block_size = 1 << v->data_dev_block_bits;
499 struct bvec_iter iter_copy;
500 struct bvec_iter *iter;
501 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
502 unsigned int b;
503
504 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
505 /*
506 * Copy the iterator in case we need to restart
507 * verification in a work-queue.
508 */
509 iter_copy = io->iter;
510 iter = &iter_copy;
511 } else
512 iter = &io->iter;
513
514 for (b = 0; b < io->n_blocks;
515 b++, bio_advance_iter(bio, iter, block_size)) {
516 int r;
517 sector_t cur_block = io->block + b;
518 bool is_zero;
519 struct bio_vec bv;
520 void *data;
521
522 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
523 likely(test_bit(cur_block, v->validated_blocks)))
524 continue;
525
526 r = verity_hash_for_block(v, io, cur_block,
527 verity_io_want_digest(v, io),
528 &is_zero);
529 if (unlikely(r < 0))
530 return r;
531
532 bv = bio_iter_iovec(bio, *iter);
533 if (unlikely(bv.bv_len < block_size)) {
534 /*
535 * Data block spans pages. This should not happen,
536 * since dm-verity sets dma_alignment to the data block
537 * size minus 1, and dm-verity also doesn't allow the
538 * data block size to be greater than PAGE_SIZE.
539 */
540 DMERR_LIMIT("unaligned io (data block spans pages)");
541 return -EIO;
542 }
543
544 data = bvec_kmap_local(&bv);
545
546 if (is_zero) {
547 /*
548 * If we expect a zero block, don't validate, just
549 * return zeros.
550 */
551 memset(data, 0, block_size);
552 kunmap_local(data);
553 continue;
554 }
555
556 r = verity_hash(v, io, data, block_size,
557 verity_io_real_digest(v, io), !io->in_bh);
558 if (unlikely(r < 0)) {
559 kunmap_local(data);
560 return r;
561 }
562
563 if (likely(memcmp(verity_io_real_digest(v, io),
564 verity_io_want_digest(v, io), v->digest_size) == 0)) {
565 if (v->validated_blocks)
566 set_bit(cur_block, v->validated_blocks);
567 kunmap_local(data);
568 continue;
569 }
570 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block,
571 data);
572 kunmap_local(data);
573 if (unlikely(r))
574 return r;
575 }
576
577 return 0;
578}
579
580/*
581 * Skip verity work in response to I/O error when system is shutting down.
582 */
583static inline bool verity_is_system_shutting_down(void)
584{
585 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
586 || system_state == SYSTEM_RESTART;
587}
588
589static void restart_io_error(struct work_struct *w)
590{
591 kernel_restart("dm-verity device has I/O error");
592}
593
594/*
595 * End one "io" structure with a given error.
596 */
597static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
598{
599 struct dm_verity *v = io->v;
600 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
601
602 bio->bi_end_io = io->orig_bi_end_io;
603 bio->bi_status = status;
604
605 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
606 verity_fec_finish_io(io);
607
608 if (unlikely(status != BLK_STS_OK) &&
609 unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
610 !io->had_mismatch &&
611 !verity_is_system_shutting_down()) {
612 if (v->error_mode == DM_VERITY_MODE_PANIC) {
613 panic("dm-verity device has I/O error");
614 }
615 if (v->error_mode == DM_VERITY_MODE_RESTART) {
616 static DECLARE_WORK(restart_work, restart_io_error);
617 queue_work(v->verify_wq, &restart_work);
618 /*
619 * We deliberately don't call bio_endio here, because
620 * the machine will be restarted anyway.
621 */
622 return;
623 }
624 }
625
626 bio_endio(bio);
627}
628
629static void verity_work(struct work_struct *w)
630{
631 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
632
633 io->in_bh = false;
634
635 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
636}
637
638static void verity_bh_work(struct work_struct *w)
639{
640 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
641 int err;
642
643 io->in_bh = true;
644 err = verity_verify_io(io);
645 if (err == -EAGAIN || err == -ENOMEM) {
646 /* fallback to retrying with work-queue */
647 INIT_WORK(&io->work, verity_work);
648 queue_work(io->v->verify_wq, &io->work);
649 return;
650 }
651
652 verity_finish_io(io, errno_to_blk_status(err));
653}
654
655static void verity_end_io(struct bio *bio)
656{
657 struct dm_verity_io *io = bio->bi_private;
658
659 if (bio->bi_status &&
660 (!verity_fec_is_enabled(io->v) ||
661 verity_is_system_shutting_down() ||
662 (bio->bi_opf & REQ_RAHEAD))) {
663 verity_finish_io(io, bio->bi_status);
664 return;
665 }
666
667 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) {
668 INIT_WORK(&io->bh_work, verity_bh_work);
669 queue_work(system_bh_wq, &io->bh_work);
670 } else {
671 INIT_WORK(&io->work, verity_work);
672 queue_work(io->v->verify_wq, &io->work);
673 }
674}
675
676/*
677 * Prefetch buffers for the specified io.
678 * The root buffer is not prefetched, it is assumed that it will be cached
679 * all the time.
680 */
681static void verity_prefetch_io(struct work_struct *work)
682{
683 struct dm_verity_prefetch_work *pw =
684 container_of(work, struct dm_verity_prefetch_work, work);
685 struct dm_verity *v = pw->v;
686 int i;
687
688 for (i = v->levels - 2; i >= 0; i--) {
689 sector_t hash_block_start;
690 sector_t hash_block_end;
691
692 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
693 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
694
695 if (!i) {
696 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
697
698 cluster >>= v->data_dev_block_bits;
699 if (unlikely(!cluster))
700 goto no_prefetch_cluster;
701
702 if (unlikely(cluster & (cluster - 1)))
703 cluster = 1 << __fls(cluster);
704
705 hash_block_start &= ~(sector_t)(cluster - 1);
706 hash_block_end |= cluster - 1;
707 if (unlikely(hash_block_end >= v->hash_blocks))
708 hash_block_end = v->hash_blocks - 1;
709 }
710no_prefetch_cluster:
711 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start,
712 hash_block_end - hash_block_start + 1,
713 pw->ioprio);
714 }
715
716 kfree(pw);
717}
718
719static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
720 unsigned short ioprio)
721{
722 sector_t block = io->block;
723 unsigned int n_blocks = io->n_blocks;
724 struct dm_verity_prefetch_work *pw;
725
726 if (v->validated_blocks) {
727 while (n_blocks && test_bit(block, v->validated_blocks)) {
728 block++;
729 n_blocks--;
730 }
731 while (n_blocks && test_bit(block + n_blocks - 1,
732 v->validated_blocks))
733 n_blocks--;
734 if (!n_blocks)
735 return;
736 }
737
738 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
739 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
740
741 if (!pw)
742 return;
743
744 INIT_WORK(&pw->work, verity_prefetch_io);
745 pw->v = v;
746 pw->block = block;
747 pw->n_blocks = n_blocks;
748 pw->ioprio = ioprio;
749 queue_work(v->verify_wq, &pw->work);
750}
751
752/*
753 * Bio map function. It allocates dm_verity_io structure and bio vector and
754 * fills them. Then it issues prefetches and the I/O.
755 */
756static int verity_map(struct dm_target *ti, struct bio *bio)
757{
758 struct dm_verity *v = ti->private;
759 struct dm_verity_io *io;
760
761 bio_set_dev(bio, v->data_dev->bdev);
762 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
763
764 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
765 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
766 DMERR_LIMIT("unaligned io");
767 return DM_MAPIO_KILL;
768 }
769
770 if (bio_end_sector(bio) >>
771 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
772 DMERR_LIMIT("io out of range");
773 return DM_MAPIO_KILL;
774 }
775
776 if (bio_data_dir(bio) == WRITE)
777 return DM_MAPIO_KILL;
778
779 io = dm_per_bio_data(bio, ti->per_io_data_size);
780 io->v = v;
781 io->orig_bi_end_io = bio->bi_end_io;
782 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
783 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
784 io->had_mismatch = false;
785
786 bio->bi_end_io = verity_end_io;
787 bio->bi_private = io;
788 io->iter = bio->bi_iter;
789
790 verity_fec_init_io(io);
791
792 verity_submit_prefetch(v, io, bio_prio(bio));
793
794 submit_bio_noacct(bio);
795
796 return DM_MAPIO_SUBMITTED;
797}
798
799/*
800 * Status: V (valid) or C (corruption found)
801 */
802static void verity_status(struct dm_target *ti, status_type_t type,
803 unsigned int status_flags, char *result, unsigned int maxlen)
804{
805 struct dm_verity *v = ti->private;
806 unsigned int args = 0;
807 unsigned int sz = 0;
808 unsigned int x;
809
810 switch (type) {
811 case STATUSTYPE_INFO:
812 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
813 break;
814 case STATUSTYPE_TABLE:
815 DMEMIT("%u %s %s %u %u %llu %llu %s ",
816 v->version,
817 v->data_dev->name,
818 v->hash_dev->name,
819 1 << v->data_dev_block_bits,
820 1 << v->hash_dev_block_bits,
821 (unsigned long long)v->data_blocks,
822 (unsigned long long)v->hash_start,
823 v->alg_name
824 );
825 for (x = 0; x < v->digest_size; x++)
826 DMEMIT("%02x", v->root_digest[x]);
827 DMEMIT(" ");
828 if (!v->salt_size)
829 DMEMIT("-");
830 else
831 for (x = 0; x < v->salt_size; x++)
832 DMEMIT("%02x", v->salt[x]);
833 if (v->mode != DM_VERITY_MODE_EIO)
834 args++;
835 if (v->error_mode != DM_VERITY_MODE_EIO)
836 args++;
837 if (verity_fec_is_enabled(v))
838 args += DM_VERITY_OPTS_FEC;
839 if (v->zero_digest)
840 args++;
841 if (v->validated_blocks)
842 args++;
843 if (v->use_bh_wq)
844 args++;
845 if (v->signature_key_desc)
846 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
847 if (!args)
848 return;
849 DMEMIT(" %u", args);
850 if (v->mode != DM_VERITY_MODE_EIO) {
851 DMEMIT(" ");
852 switch (v->mode) {
853 case DM_VERITY_MODE_LOGGING:
854 DMEMIT(DM_VERITY_OPT_LOGGING);
855 break;
856 case DM_VERITY_MODE_RESTART:
857 DMEMIT(DM_VERITY_OPT_RESTART);
858 break;
859 case DM_VERITY_MODE_PANIC:
860 DMEMIT(DM_VERITY_OPT_PANIC);
861 break;
862 default:
863 BUG();
864 }
865 }
866 if (v->error_mode != DM_VERITY_MODE_EIO) {
867 DMEMIT(" ");
868 switch (v->error_mode) {
869 case DM_VERITY_MODE_RESTART:
870 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
871 break;
872 case DM_VERITY_MODE_PANIC:
873 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
874 break;
875 default:
876 BUG();
877 }
878 }
879 if (v->zero_digest)
880 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
881 if (v->validated_blocks)
882 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
883 if (v->use_bh_wq)
884 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
885 sz = verity_fec_status_table(v, sz, result, maxlen);
886 if (v->signature_key_desc)
887 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
888 " %s", v->signature_key_desc);
889 break;
890
891 case STATUSTYPE_IMA:
892 DMEMIT_TARGET_NAME_VERSION(ti->type);
893 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
894 DMEMIT(",verity_version=%u", v->version);
895 DMEMIT(",data_device_name=%s", v->data_dev->name);
896 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
897 DMEMIT(",verity_algorithm=%s", v->alg_name);
898
899 DMEMIT(",root_digest=");
900 for (x = 0; x < v->digest_size; x++)
901 DMEMIT("%02x", v->root_digest[x]);
902
903 DMEMIT(",salt=");
904 if (!v->salt_size)
905 DMEMIT("-");
906 else
907 for (x = 0; x < v->salt_size; x++)
908 DMEMIT("%02x", v->salt[x]);
909
910 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
911 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
912 if (v->signature_key_desc)
913 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
914
915 if (v->mode != DM_VERITY_MODE_EIO) {
916 DMEMIT(",verity_mode=");
917 switch (v->mode) {
918 case DM_VERITY_MODE_LOGGING:
919 DMEMIT(DM_VERITY_OPT_LOGGING);
920 break;
921 case DM_VERITY_MODE_RESTART:
922 DMEMIT(DM_VERITY_OPT_RESTART);
923 break;
924 case DM_VERITY_MODE_PANIC:
925 DMEMIT(DM_VERITY_OPT_PANIC);
926 break;
927 default:
928 DMEMIT("invalid");
929 }
930 }
931 if (v->error_mode != DM_VERITY_MODE_EIO) {
932 DMEMIT(",verity_error_mode=");
933 switch (v->error_mode) {
934 case DM_VERITY_MODE_RESTART:
935 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
936 break;
937 case DM_VERITY_MODE_PANIC:
938 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
939 break;
940 default:
941 DMEMIT("invalid");
942 }
943 }
944 DMEMIT(";");
945 break;
946 }
947}
948
949static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
950{
951 struct dm_verity *v = ti->private;
952
953 *bdev = v->data_dev->bdev;
954
955 if (ti->len != bdev_nr_sectors(v->data_dev->bdev))
956 return 1;
957 return 0;
958}
959
960static int verity_iterate_devices(struct dm_target *ti,
961 iterate_devices_callout_fn fn, void *data)
962{
963 struct dm_verity *v = ti->private;
964
965 return fn(ti, v->data_dev, 0, ti->len, data);
966}
967
968static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
969{
970 struct dm_verity *v = ti->private;
971
972 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
973 limits->logical_block_size = 1 << v->data_dev_block_bits;
974
975 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
976 limits->physical_block_size = 1 << v->data_dev_block_bits;
977
978 limits->io_min = limits->logical_block_size;
979
980 /*
981 * Similar to what dm-crypt does, opt dm-verity out of support for
982 * direct I/O that is aligned to less than the traditional direct I/O
983 * alignment requirement of logical_block_size. This prevents dm-verity
984 * data blocks from crossing pages, eliminating various edge cases.
985 */
986 limits->dma_alignment = limits->logical_block_size - 1;
987}
988
989#ifdef CONFIG_SECURITY
990
991static int verity_init_sig(struct dm_verity *v, const void *sig,
992 size_t sig_size)
993{
994 v->sig_size = sig_size;
995
996 if (sig) {
997 v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL);
998 if (!v->root_digest_sig)
999 return -ENOMEM;
1000 }
1001
1002 return 0;
1003}
1004
1005static void verity_free_sig(struct dm_verity *v)
1006{
1007 kfree(v->root_digest_sig);
1008}
1009
1010#else
1011
1012static inline int verity_init_sig(struct dm_verity *v, const void *sig,
1013 size_t sig_size)
1014{
1015 return 0;
1016}
1017
1018static inline void verity_free_sig(struct dm_verity *v)
1019{
1020}
1021
1022#endif /* CONFIG_SECURITY */
1023
1024static void verity_dtr(struct dm_target *ti)
1025{
1026 struct dm_verity *v = ti->private;
1027
1028 if (v->verify_wq)
1029 destroy_workqueue(v->verify_wq);
1030
1031 mempool_exit(&v->recheck_pool);
1032 if (v->io)
1033 dm_io_client_destroy(v->io);
1034
1035 if (v->bufio)
1036 dm_bufio_client_destroy(v->bufio);
1037
1038 kvfree(v->validated_blocks);
1039 kfree(v->salt);
1040 kfree(v->initial_hashstate);
1041 kfree(v->root_digest);
1042 kfree(v->zero_digest);
1043 verity_free_sig(v);
1044
1045 if (v->ahash_tfm) {
1046 static_branch_dec(&ahash_enabled);
1047 crypto_free_ahash(v->ahash_tfm);
1048 } else {
1049 crypto_free_shash(v->shash_tfm);
1050 }
1051
1052 kfree(v->alg_name);
1053
1054 if (v->hash_dev)
1055 dm_put_device(ti, v->hash_dev);
1056
1057 if (v->data_dev)
1058 dm_put_device(ti, v->data_dev);
1059
1060 verity_fec_dtr(v);
1061
1062 kfree(v->signature_key_desc);
1063
1064 if (v->use_bh_wq)
1065 static_branch_dec(&use_bh_wq_enabled);
1066
1067 kfree(v);
1068
1069 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1070}
1071
1072static int verity_alloc_most_once(struct dm_verity *v)
1073{
1074 struct dm_target *ti = v->ti;
1075
1076 /* the bitset can only handle INT_MAX blocks */
1077 if (v->data_blocks > INT_MAX) {
1078 ti->error = "device too large to use check_at_most_once";
1079 return -E2BIG;
1080 }
1081
1082 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1083 sizeof(unsigned long),
1084 GFP_KERNEL);
1085 if (!v->validated_blocks) {
1086 ti->error = "failed to allocate bitset for check_at_most_once";
1087 return -ENOMEM;
1088 }
1089
1090 return 0;
1091}
1092
1093static int verity_alloc_zero_digest(struct dm_verity *v)
1094{
1095 int r = -ENOMEM;
1096 struct dm_verity_io *io;
1097 u8 *zero_data;
1098
1099 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1100
1101 if (!v->zero_digest)
1102 return r;
1103
1104 io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL);
1105
1106 if (!io)
1107 return r; /* verity_dtr will free zero_digest */
1108
1109 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1110
1111 if (!zero_data)
1112 goto out;
1113
1114 r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits,
1115 v->zero_digest, true);
1116
1117out:
1118 kfree(io);
1119 kfree(zero_data);
1120
1121 return r;
1122}
1123
1124static inline bool verity_is_verity_mode(const char *arg_name)
1125{
1126 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1127 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1128 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1129}
1130
1131static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1132{
1133 if (v->mode)
1134 return -EINVAL;
1135
1136 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1137 v->mode = DM_VERITY_MODE_LOGGING;
1138 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1139 v->mode = DM_VERITY_MODE_RESTART;
1140 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1141 v->mode = DM_VERITY_MODE_PANIC;
1142
1143 return 0;
1144}
1145
1146static inline bool verity_is_verity_error_mode(const char *arg_name)
1147{
1148 return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) ||
1149 !strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC));
1150}
1151
1152static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name)
1153{
1154 if (v->error_mode)
1155 return -EINVAL;
1156
1157 if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART))
1158 v->error_mode = DM_VERITY_MODE_RESTART;
1159 else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC))
1160 v->error_mode = DM_VERITY_MODE_PANIC;
1161
1162 return 0;
1163}
1164
1165static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1166 struct dm_verity_sig_opts *verify_args,
1167 bool only_modifier_opts)
1168{
1169 int r = 0;
1170 unsigned int argc;
1171 struct dm_target *ti = v->ti;
1172 const char *arg_name;
1173
1174 static const struct dm_arg _args[] = {
1175 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1176 };
1177
1178 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1179 if (r)
1180 return -EINVAL;
1181
1182 if (!argc)
1183 return 0;
1184
1185 do {
1186 arg_name = dm_shift_arg(as);
1187 argc--;
1188
1189 if (verity_is_verity_mode(arg_name)) {
1190 if (only_modifier_opts)
1191 continue;
1192 r = verity_parse_verity_mode(v, arg_name);
1193 if (r) {
1194 ti->error = "Conflicting error handling parameters";
1195 return r;
1196 }
1197 continue;
1198
1199 } else if (verity_is_verity_error_mode(arg_name)) {
1200 if (only_modifier_opts)
1201 continue;
1202 r = verity_parse_verity_error_mode(v, arg_name);
1203 if (r) {
1204 ti->error = "Conflicting error handling parameters";
1205 return r;
1206 }
1207 continue;
1208
1209 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1210 if (only_modifier_opts)
1211 continue;
1212 r = verity_alloc_zero_digest(v);
1213 if (r) {
1214 ti->error = "Cannot allocate zero digest";
1215 return r;
1216 }
1217 continue;
1218
1219 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1220 if (only_modifier_opts)
1221 continue;
1222 r = verity_alloc_most_once(v);
1223 if (r)
1224 return r;
1225 continue;
1226
1227 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1228 v->use_bh_wq = true;
1229 static_branch_inc(&use_bh_wq_enabled);
1230 continue;
1231
1232 } else if (verity_is_fec_opt_arg(arg_name)) {
1233 if (only_modifier_opts)
1234 continue;
1235 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1236 if (r)
1237 return r;
1238 continue;
1239
1240 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1241 if (only_modifier_opts)
1242 continue;
1243 r = verity_verify_sig_parse_opt_args(as, v,
1244 verify_args,
1245 &argc, arg_name);
1246 if (r)
1247 return r;
1248 continue;
1249
1250 } else if (only_modifier_opts) {
1251 /*
1252 * Ignore unrecognized opt, could easily be an extra
1253 * argument to an option whose parsing was skipped.
1254 * Normal parsing (@only_modifier_opts=false) will
1255 * properly parse all options (and their extra args).
1256 */
1257 continue;
1258 }
1259
1260 DMERR("Unrecognized verity feature request: %s", arg_name);
1261 ti->error = "Unrecognized verity feature request";
1262 return -EINVAL;
1263 } while (argc && !r);
1264
1265 return r;
1266}
1267
1268static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name)
1269{
1270 struct dm_target *ti = v->ti;
1271 struct crypto_ahash *ahash;
1272 struct crypto_shash *shash = NULL;
1273 const char *driver_name;
1274
1275 v->alg_name = kstrdup(alg_name, GFP_KERNEL);
1276 if (!v->alg_name) {
1277 ti->error = "Cannot allocate algorithm name";
1278 return -ENOMEM;
1279 }
1280
1281 /*
1282 * Allocate the hash transformation object that this dm-verity instance
1283 * will use. The vast majority of dm-verity users use CPU-based
1284 * hashing, so when possible use the shash API to minimize the crypto
1285 * API overhead. If the ahash API resolves to a different driver
1286 * (likely an off-CPU hardware offload), use ahash instead. Also use
1287 * ahash if the obsolete dm-verity format with the appended salt is
1288 * being used, so that quirk only needs to be handled in one place.
1289 */
1290 ahash = crypto_alloc_ahash(alg_name, 0,
1291 v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
1292 if (IS_ERR(ahash)) {
1293 ti->error = "Cannot initialize hash function";
1294 return PTR_ERR(ahash);
1295 }
1296 driver_name = crypto_ahash_driver_name(ahash);
1297 if (v->version >= 1 /* salt prepended, not appended? */) {
1298 shash = crypto_alloc_shash(alg_name, 0, 0);
1299 if (!IS_ERR(shash) &&
1300 strcmp(crypto_shash_driver_name(shash), driver_name) != 0) {
1301 /*
1302 * ahash gave a different driver than shash, so probably
1303 * this is a case of real hardware offload. Use ahash.
1304 */
1305 crypto_free_shash(shash);
1306 shash = NULL;
1307 }
1308 }
1309 if (!IS_ERR_OR_NULL(shash)) {
1310 crypto_free_ahash(ahash);
1311 ahash = NULL;
1312 v->shash_tfm = shash;
1313 v->digest_size = crypto_shash_digestsize(shash);
1314 v->hash_reqsize = sizeof(struct shash_desc) +
1315 crypto_shash_descsize(shash);
1316 DMINFO("%s using shash \"%s\"", alg_name, driver_name);
1317 } else {
1318 v->ahash_tfm = ahash;
1319 static_branch_inc(&ahash_enabled);
1320 v->digest_size = crypto_ahash_digestsize(ahash);
1321 v->hash_reqsize = sizeof(struct ahash_request) +
1322 crypto_ahash_reqsize(ahash);
1323 DMINFO("%s using ahash \"%s\"", alg_name, driver_name);
1324 }
1325 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1326 ti->error = "Digest size too big";
1327 return -EINVAL;
1328 }
1329 return 0;
1330}
1331
1332static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg)
1333{
1334 struct dm_target *ti = v->ti;
1335
1336 if (strcmp(arg, "-") != 0) {
1337 v->salt_size = strlen(arg) / 2;
1338 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1339 if (!v->salt) {
1340 ti->error = "Cannot allocate salt";
1341 return -ENOMEM;
1342 }
1343 if (strlen(arg) != v->salt_size * 2 ||
1344 hex2bin(v->salt, arg, v->salt_size)) {
1345 ti->error = "Invalid salt";
1346 return -EINVAL;
1347 }
1348 }
1349 if (v->shash_tfm) {
1350 SHASH_DESC_ON_STACK(desc, v->shash_tfm);
1351 int r;
1352
1353 /*
1354 * Compute the pre-salted hash state that can be passed to
1355 * crypto_shash_import() for each block later.
1356 */
1357 v->initial_hashstate = kmalloc(
1358 crypto_shash_statesize(v->shash_tfm), GFP_KERNEL);
1359 if (!v->initial_hashstate) {
1360 ti->error = "Cannot allocate initial hash state";
1361 return -ENOMEM;
1362 }
1363 desc->tfm = v->shash_tfm;
1364 r = crypto_shash_init(desc) ?:
1365 crypto_shash_update(desc, v->salt, v->salt_size) ?:
1366 crypto_shash_export(desc, v->initial_hashstate);
1367 if (r) {
1368 ti->error = "Cannot set up initial hash state";
1369 return r;
1370 }
1371 }
1372 return 0;
1373}
1374
1375/*
1376 * Target parameters:
1377 * <version> The current format is version 1.
1378 * Vsn 0 is compatible with original Chromium OS releases.
1379 * <data device>
1380 * <hash device>
1381 * <data block size>
1382 * <hash block size>
1383 * <the number of data blocks>
1384 * <hash start block>
1385 * <algorithm>
1386 * <digest>
1387 * <salt> Hex string or "-" if no salt.
1388 */
1389static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1390{
1391 struct dm_verity *v;
1392 struct dm_verity_sig_opts verify_args = {0};
1393 struct dm_arg_set as;
1394 unsigned int num;
1395 unsigned long long num_ll;
1396 int r;
1397 int i;
1398 sector_t hash_position;
1399 char dummy;
1400 char *root_hash_digest_to_validate;
1401
1402 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1403 if (!v) {
1404 ti->error = "Cannot allocate verity structure";
1405 return -ENOMEM;
1406 }
1407 ti->private = v;
1408 v->ti = ti;
1409
1410 r = verity_fec_ctr_alloc(v);
1411 if (r)
1412 goto bad;
1413
1414 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1415 ti->error = "Device must be readonly";
1416 r = -EINVAL;
1417 goto bad;
1418 }
1419
1420 if (argc < 10) {
1421 ti->error = "Not enough arguments";
1422 r = -EINVAL;
1423 goto bad;
1424 }
1425
1426 /* Parse optional parameters that modify primary args */
1427 if (argc > 10) {
1428 as.argc = argc - 10;
1429 as.argv = argv + 10;
1430 r = verity_parse_opt_args(&as, v, &verify_args, true);
1431 if (r < 0)
1432 goto bad;
1433 }
1434
1435 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1436 num > 1) {
1437 ti->error = "Invalid version";
1438 r = -EINVAL;
1439 goto bad;
1440 }
1441 v->version = num;
1442
1443 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1444 if (r) {
1445 ti->error = "Data device lookup failed";
1446 goto bad;
1447 }
1448
1449 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1450 if (r) {
1451 ti->error = "Hash device lookup failed";
1452 goto bad;
1453 }
1454
1455 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1456 !num || (num & (num - 1)) ||
1457 num < bdev_logical_block_size(v->data_dev->bdev) ||
1458 num > PAGE_SIZE) {
1459 ti->error = "Invalid data device block size";
1460 r = -EINVAL;
1461 goto bad;
1462 }
1463 v->data_dev_block_bits = __ffs(num);
1464
1465 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1466 !num || (num & (num - 1)) ||
1467 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1468 num > INT_MAX) {
1469 ti->error = "Invalid hash device block size";
1470 r = -EINVAL;
1471 goto bad;
1472 }
1473 v->hash_dev_block_bits = __ffs(num);
1474
1475 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1476 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1477 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1478 ti->error = "Invalid data blocks";
1479 r = -EINVAL;
1480 goto bad;
1481 }
1482 v->data_blocks = num_ll;
1483
1484 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1485 ti->error = "Data device is too small";
1486 r = -EINVAL;
1487 goto bad;
1488 }
1489
1490 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1491 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1492 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1493 ti->error = "Invalid hash start";
1494 r = -EINVAL;
1495 goto bad;
1496 }
1497 v->hash_start = num_ll;
1498
1499 r = verity_setup_hash_alg(v, argv[7]);
1500 if (r)
1501 goto bad;
1502
1503 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1504 if (!v->root_digest) {
1505 ti->error = "Cannot allocate root digest";
1506 r = -ENOMEM;
1507 goto bad;
1508 }
1509 if (strlen(argv[8]) != v->digest_size * 2 ||
1510 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1511 ti->error = "Invalid root digest";
1512 r = -EINVAL;
1513 goto bad;
1514 }
1515 root_hash_digest_to_validate = argv[8];
1516
1517 r = verity_setup_salt_and_hashstate(v, argv[9]);
1518 if (r)
1519 goto bad;
1520
1521 argv += 10;
1522 argc -= 10;
1523
1524 /* Optional parameters */
1525 if (argc) {
1526 as.argc = argc;
1527 as.argv = argv;
1528 r = verity_parse_opt_args(&as, v, &verify_args, false);
1529 if (r < 0)
1530 goto bad;
1531 }
1532
1533 /* Root hash signature is a optional parameter*/
1534 r = verity_verify_root_hash(root_hash_digest_to_validate,
1535 strlen(root_hash_digest_to_validate),
1536 verify_args.sig,
1537 verify_args.sig_size);
1538 if (r < 0) {
1539 ti->error = "Root hash verification failed";
1540 goto bad;
1541 }
1542
1543 r = verity_init_sig(v, verify_args.sig, verify_args.sig_size);
1544 if (r < 0) {
1545 ti->error = "Cannot allocate root digest signature";
1546 goto bad;
1547 }
1548
1549 v->hash_per_block_bits =
1550 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1551
1552 v->levels = 0;
1553 if (v->data_blocks)
1554 while (v->hash_per_block_bits * v->levels < 64 &&
1555 (unsigned long long)(v->data_blocks - 1) >>
1556 (v->hash_per_block_bits * v->levels))
1557 v->levels++;
1558
1559 if (v->levels > DM_VERITY_MAX_LEVELS) {
1560 ti->error = "Too many tree levels";
1561 r = -E2BIG;
1562 goto bad;
1563 }
1564
1565 hash_position = v->hash_start;
1566 for (i = v->levels - 1; i >= 0; i--) {
1567 sector_t s;
1568
1569 v->hash_level_block[i] = hash_position;
1570 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1571 >> ((i + 1) * v->hash_per_block_bits);
1572 if (hash_position + s < hash_position) {
1573 ti->error = "Hash device offset overflow";
1574 r = -E2BIG;
1575 goto bad;
1576 }
1577 hash_position += s;
1578 }
1579 v->hash_blocks = hash_position;
1580
1581 r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1582 if (unlikely(r)) {
1583 ti->error = "Cannot allocate mempool";
1584 goto bad;
1585 }
1586
1587 v->io = dm_io_client_create();
1588 if (IS_ERR(v->io)) {
1589 r = PTR_ERR(v->io);
1590 v->io = NULL;
1591 ti->error = "Cannot allocate dm io";
1592 goto bad;
1593 }
1594
1595 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1596 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1597 dm_bufio_alloc_callback, NULL,
1598 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1599 if (IS_ERR(v->bufio)) {
1600 ti->error = "Cannot initialize dm-bufio";
1601 r = PTR_ERR(v->bufio);
1602 v->bufio = NULL;
1603 goto bad;
1604 }
1605
1606 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1607 ti->error = "Hash device is too small";
1608 r = -E2BIG;
1609 goto bad;
1610 }
1611
1612 /*
1613 * Using WQ_HIGHPRI improves throughput and completion latency by
1614 * reducing wait times when reading from a dm-verity device.
1615 *
1616 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1617 * allows verify_wq to preempt softirq since verification in BH workqueue
1618 * will fall-back to using it for error handling (or if the bufio cache
1619 * doesn't have required hashes).
1620 */
1621 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1622 if (!v->verify_wq) {
1623 ti->error = "Cannot allocate workqueue";
1624 r = -ENOMEM;
1625 goto bad;
1626 }
1627
1628 ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize;
1629
1630 r = verity_fec_ctr(v);
1631 if (r)
1632 goto bad;
1633
1634 ti->per_io_data_size = roundup(ti->per_io_data_size,
1635 __alignof__(struct dm_verity_io));
1636
1637 verity_verify_sig_opts_cleanup(&verify_args);
1638
1639 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1640
1641 return 0;
1642
1643bad:
1644
1645 verity_verify_sig_opts_cleanup(&verify_args);
1646 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1647 verity_dtr(ti);
1648
1649 return r;
1650}
1651
1652/*
1653 * Get the verity mode (error behavior) of a verity target.
1654 *
1655 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1656 * target.
1657 */
1658int dm_verity_get_mode(struct dm_target *ti)
1659{
1660 struct dm_verity *v = ti->private;
1661
1662 if (!dm_is_verity_target(ti))
1663 return -EINVAL;
1664
1665 return v->mode;
1666}
1667
1668/*
1669 * Get the root digest of a verity target.
1670 *
1671 * Returns a copy of the root digest, the caller is responsible for
1672 * freeing the memory of the digest.
1673 */
1674int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1675{
1676 struct dm_verity *v = ti->private;
1677
1678 if (!dm_is_verity_target(ti))
1679 return -EINVAL;
1680
1681 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1682 if (*root_digest == NULL)
1683 return -ENOMEM;
1684
1685 *digest_size = v->digest_size;
1686
1687 return 0;
1688}
1689
1690#ifdef CONFIG_SECURITY
1691
1692#ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG
1693
1694static int verity_security_set_signature(struct block_device *bdev,
1695 struct dm_verity *v)
1696{
1697 /*
1698 * if the dm-verity target is unsigned, v->root_digest_sig will
1699 * be NULL, and the hook call is still required to let LSMs mark
1700 * the device as unsigned. This information is crucial for LSMs to
1701 * block operations such as execution on unsigned files
1702 */
1703 return security_bdev_setintegrity(bdev,
1704 LSM_INT_DMVERITY_SIG_VALID,
1705 v->root_digest_sig,
1706 v->sig_size);
1707}
1708
1709#else
1710
1711static inline int verity_security_set_signature(struct block_device *bdev,
1712 struct dm_verity *v)
1713{
1714 return 0;
1715}
1716
1717#endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */
1718
1719/*
1720 * Expose verity target's root hash and signature data to LSMs before resume.
1721 *
1722 * Returns 0 on success, or -ENOMEM if the system is out of memory.
1723 */
1724static int verity_preresume(struct dm_target *ti)
1725{
1726 struct block_device *bdev;
1727 struct dm_verity_digest root_digest;
1728 struct dm_verity *v;
1729 int r;
1730
1731 v = ti->private;
1732 bdev = dm_disk(dm_table_get_md(ti->table))->part0;
1733 root_digest.digest = v->root_digest;
1734 root_digest.digest_len = v->digest_size;
1735 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm)
1736 root_digest.alg = crypto_ahash_alg_name(v->ahash_tfm);
1737 else
1738 root_digest.alg = crypto_shash_alg_name(v->shash_tfm);
1739
1740 r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest,
1741 sizeof(root_digest));
1742 if (r)
1743 return r;
1744
1745 r = verity_security_set_signature(bdev, v);
1746 if (r)
1747 goto bad;
1748
1749 return 0;
1750
1751bad:
1752
1753 security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0);
1754
1755 return r;
1756}
1757
1758#endif /* CONFIG_SECURITY */
1759
1760static struct target_type verity_target = {
1761 .name = "verity",
1762/* Note: the LSMs depend on the singleton and immutable features */
1763 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1764 .version = {1, 10, 0},
1765 .module = THIS_MODULE,
1766 .ctr = verity_ctr,
1767 .dtr = verity_dtr,
1768 .map = verity_map,
1769 .status = verity_status,
1770 .prepare_ioctl = verity_prepare_ioctl,
1771 .iterate_devices = verity_iterate_devices,
1772 .io_hints = verity_io_hints,
1773#ifdef CONFIG_SECURITY
1774 .preresume = verity_preresume,
1775#endif /* CONFIG_SECURITY */
1776};
1777module_dm(verity);
1778
1779/*
1780 * Check whether a DM target is a verity target.
1781 */
1782bool dm_is_verity_target(struct dm_target *ti)
1783{
1784 return ti->type == &verity_target;
1785}
1786
1787MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1788MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1789MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1790MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1791MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
7 *
8 * This file is released under the GPLv2.
9 *
10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
12 * hash device. Setting this greatly improves performance when data and hash
13 * are on the same disk on different partitions on devices with poor random
14 * access behavior.
15 */
16
17#include "dm-verity.h"
18#include "dm-verity-fec.h"
19
20#include <linux/module.h>
21#include <linux/reboot.h>
22
23#define DM_MSG_PREFIX "verity"
24
25#define DM_VERITY_ENV_LENGTH 42
26#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
27
28#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
29
30#define DM_VERITY_MAX_CORRUPTED_ERRS 100
31
32#define DM_VERITY_OPT_LOGGING "ignore_corruption"
33#define DM_VERITY_OPT_RESTART "restart_on_corruption"
34#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
35
36#define DM_VERITY_OPTS_MAX (2 + DM_VERITY_OPTS_FEC)
37
38static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
39
40module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
41
42struct dm_verity_prefetch_work {
43 struct work_struct work;
44 struct dm_verity *v;
45 sector_t block;
46 unsigned n_blocks;
47};
48
49/*
50 * Auxiliary structure appended to each dm-bufio buffer. If the value
51 * hash_verified is nonzero, hash of the block has been verified.
52 *
53 * The variable hash_verified is set to 0 when allocating the buffer, then
54 * it can be changed to 1 and it is never reset to 0 again.
55 *
56 * There is no lock around this value, a race condition can at worst cause
57 * that multiple processes verify the hash of the same buffer simultaneously
58 * and write 1 to hash_verified simultaneously.
59 * This condition is harmless, so we don't need locking.
60 */
61struct buffer_aux {
62 int hash_verified;
63};
64
65/*
66 * Initialize struct buffer_aux for a freshly created buffer.
67 */
68static void dm_bufio_alloc_callback(struct dm_buffer *buf)
69{
70 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
71
72 aux->hash_verified = 0;
73}
74
75/*
76 * Translate input sector number to the sector number on the target device.
77 */
78static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
79{
80 return v->data_start + dm_target_offset(v->ti, bi_sector);
81}
82
83/*
84 * Return hash position of a specified block at a specified tree level
85 * (0 is the lowest level).
86 * The lowest "hash_per_block_bits"-bits of the result denote hash position
87 * inside a hash block. The remaining bits denote location of the hash block.
88 */
89static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
90 int level)
91{
92 return block >> (level * v->hash_per_block_bits);
93}
94
95/*
96 * Wrapper for crypto_shash_init, which handles verity salting.
97 */
98static int verity_hash_init(struct dm_verity *v, struct shash_desc *desc)
99{
100 int r;
101
102 desc->tfm = v->tfm;
103 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
104
105 r = crypto_shash_init(desc);
106
107 if (unlikely(r < 0)) {
108 DMERR("crypto_shash_init failed: %d", r);
109 return r;
110 }
111
112 if (likely(v->version >= 1)) {
113 r = crypto_shash_update(desc, v->salt, v->salt_size);
114
115 if (unlikely(r < 0)) {
116 DMERR("crypto_shash_update failed: %d", r);
117 return r;
118 }
119 }
120
121 return 0;
122}
123
124static int verity_hash_update(struct dm_verity *v, struct shash_desc *desc,
125 const u8 *data, size_t len)
126{
127 int r = crypto_shash_update(desc, data, len);
128
129 if (unlikely(r < 0))
130 DMERR("crypto_shash_update failed: %d", r);
131
132 return r;
133}
134
135static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc,
136 u8 *digest)
137{
138 int r;
139
140 if (unlikely(!v->version)) {
141 r = crypto_shash_update(desc, v->salt, v->salt_size);
142
143 if (r < 0) {
144 DMERR("crypto_shash_update failed: %d", r);
145 return r;
146 }
147 }
148
149 r = crypto_shash_final(desc, digest);
150
151 if (unlikely(r < 0))
152 DMERR("crypto_shash_final failed: %d", r);
153
154 return r;
155}
156
157int verity_hash(struct dm_verity *v, struct shash_desc *desc,
158 const u8 *data, size_t len, u8 *digest)
159{
160 int r;
161
162 r = verity_hash_init(v, desc);
163 if (unlikely(r < 0))
164 return r;
165
166 r = verity_hash_update(v, desc, data, len);
167 if (unlikely(r < 0))
168 return r;
169
170 return verity_hash_final(v, desc, digest);
171}
172
173static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
174 sector_t *hash_block, unsigned *offset)
175{
176 sector_t position = verity_position_at_level(v, block, level);
177 unsigned idx;
178
179 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
180
181 if (!offset)
182 return;
183
184 idx = position & ((1 << v->hash_per_block_bits) - 1);
185 if (!v->version)
186 *offset = idx * v->digest_size;
187 else
188 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
189}
190
191/*
192 * Handle verification errors.
193 */
194static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
195 unsigned long long block)
196{
197 char verity_env[DM_VERITY_ENV_LENGTH];
198 char *envp[] = { verity_env, NULL };
199 const char *type_str = "";
200 struct mapped_device *md = dm_table_get_md(v->ti->table);
201
202 /* Corruption should be visible in device status in all modes */
203 v->hash_failed = 1;
204
205 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
206 goto out;
207
208 v->corrupted_errs++;
209
210 switch (type) {
211 case DM_VERITY_BLOCK_TYPE_DATA:
212 type_str = "data";
213 break;
214 case DM_VERITY_BLOCK_TYPE_METADATA:
215 type_str = "metadata";
216 break;
217 default:
218 BUG();
219 }
220
221 DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
222 block);
223
224 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
225 DMERR("%s: reached maximum errors", v->data_dev->name);
226
227 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
228 DM_VERITY_ENV_VAR_NAME, type, block);
229
230 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
231
232out:
233 if (v->mode == DM_VERITY_MODE_LOGGING)
234 return 0;
235
236 if (v->mode == DM_VERITY_MODE_RESTART)
237 kernel_restart("dm-verity device corrupted");
238
239 return 1;
240}
241
242/*
243 * Verify hash of a metadata block pertaining to the specified data block
244 * ("block" argument) at a specified level ("level" argument).
245 *
246 * On successful return, verity_io_want_digest(v, io) contains the hash value
247 * for a lower tree level or for the data block (if we're at the lowest level).
248 *
249 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
250 * If "skip_unverified" is false, unverified buffer is hashed and verified
251 * against current value of verity_io_want_digest(v, io).
252 */
253static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
254 sector_t block, int level, bool skip_unverified,
255 u8 *want_digest)
256{
257 struct dm_buffer *buf;
258 struct buffer_aux *aux;
259 u8 *data;
260 int r;
261 sector_t hash_block;
262 unsigned offset;
263
264 verity_hash_at_level(v, block, level, &hash_block, &offset);
265
266 data = dm_bufio_read(v->bufio, hash_block, &buf);
267 if (IS_ERR(data))
268 return PTR_ERR(data);
269
270 aux = dm_bufio_get_aux_data(buf);
271
272 if (!aux->hash_verified) {
273 if (skip_unverified) {
274 r = 1;
275 goto release_ret_r;
276 }
277
278 r = verity_hash(v, verity_io_hash_desc(v, io),
279 data, 1 << v->hash_dev_block_bits,
280 verity_io_real_digest(v, io));
281 if (unlikely(r < 0))
282 goto release_ret_r;
283
284 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
285 v->digest_size) == 0))
286 aux->hash_verified = 1;
287 else if (verity_fec_decode(v, io,
288 DM_VERITY_BLOCK_TYPE_METADATA,
289 hash_block, data, NULL) == 0)
290 aux->hash_verified = 1;
291 else if (verity_handle_err(v,
292 DM_VERITY_BLOCK_TYPE_METADATA,
293 hash_block)) {
294 r = -EIO;
295 goto release_ret_r;
296 }
297 }
298
299 data += offset;
300 memcpy(want_digest, data, v->digest_size);
301 r = 0;
302
303release_ret_r:
304 dm_bufio_release(buf);
305 return r;
306}
307
308/*
309 * Find a hash for a given block, write it to digest and verify the integrity
310 * of the hash tree if necessary.
311 */
312int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
313 sector_t block, u8 *digest, bool *is_zero)
314{
315 int r = 0, i;
316
317 if (likely(v->levels)) {
318 /*
319 * First, we try to get the requested hash for
320 * the current block. If the hash block itself is
321 * verified, zero is returned. If it isn't, this
322 * function returns 1 and we fall back to whole
323 * chain verification.
324 */
325 r = verity_verify_level(v, io, block, 0, true, digest);
326 if (likely(r <= 0))
327 goto out;
328 }
329
330 memcpy(digest, v->root_digest, v->digest_size);
331
332 for (i = v->levels - 1; i >= 0; i--) {
333 r = verity_verify_level(v, io, block, i, false, digest);
334 if (unlikely(r))
335 goto out;
336 }
337out:
338 if (!r && v->zero_digest)
339 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
340 else
341 *is_zero = false;
342
343 return r;
344}
345
346/*
347 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
348 * starting from iter.
349 */
350int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
351 struct bvec_iter *iter,
352 int (*process)(struct dm_verity *v,
353 struct dm_verity_io *io, u8 *data,
354 size_t len))
355{
356 unsigned todo = 1 << v->data_dev_block_bits;
357 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
358
359 do {
360 int r;
361 u8 *page;
362 unsigned len;
363 struct bio_vec bv = bio_iter_iovec(bio, *iter);
364
365 page = kmap_atomic(bv.bv_page);
366 len = bv.bv_len;
367
368 if (likely(len >= todo))
369 len = todo;
370
371 r = process(v, io, page + bv.bv_offset, len);
372 kunmap_atomic(page);
373
374 if (r < 0)
375 return r;
376
377 bio_advance_iter(bio, iter, len);
378 todo -= len;
379 } while (todo);
380
381 return 0;
382}
383
384static int verity_bv_hash_update(struct dm_verity *v, struct dm_verity_io *io,
385 u8 *data, size_t len)
386{
387 return verity_hash_update(v, verity_io_hash_desc(v, io), data, len);
388}
389
390static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
391 u8 *data, size_t len)
392{
393 memset(data, 0, len);
394 return 0;
395}
396
397/*
398 * Verify one "dm_verity_io" structure.
399 */
400static int verity_verify_io(struct dm_verity_io *io)
401{
402 bool is_zero;
403 struct dm_verity *v = io->v;
404 struct bvec_iter start;
405 unsigned b;
406
407 for (b = 0; b < io->n_blocks; b++) {
408 int r;
409 struct shash_desc *desc = verity_io_hash_desc(v, io);
410
411 r = verity_hash_for_block(v, io, io->block + b,
412 verity_io_want_digest(v, io),
413 &is_zero);
414 if (unlikely(r < 0))
415 return r;
416
417 if (is_zero) {
418 /*
419 * If we expect a zero block, don't validate, just
420 * return zeros.
421 */
422 r = verity_for_bv_block(v, io, &io->iter,
423 verity_bv_zero);
424 if (unlikely(r < 0))
425 return r;
426
427 continue;
428 }
429
430 r = verity_hash_init(v, desc);
431 if (unlikely(r < 0))
432 return r;
433
434 start = io->iter;
435 r = verity_for_bv_block(v, io, &io->iter, verity_bv_hash_update);
436 if (unlikely(r < 0))
437 return r;
438
439 r = verity_hash_final(v, desc, verity_io_real_digest(v, io));
440 if (unlikely(r < 0))
441 return r;
442
443 if (likely(memcmp(verity_io_real_digest(v, io),
444 verity_io_want_digest(v, io), v->digest_size) == 0))
445 continue;
446 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
447 io->block + b, NULL, &start) == 0)
448 continue;
449 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
450 io->block + b))
451 return -EIO;
452 }
453
454 return 0;
455}
456
457/*
458 * End one "io" structure with a given error.
459 */
460static void verity_finish_io(struct dm_verity_io *io, int error)
461{
462 struct dm_verity *v = io->v;
463 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
464
465 bio->bi_end_io = io->orig_bi_end_io;
466 bio->bi_error = error;
467
468 verity_fec_finish_io(io);
469
470 bio_endio(bio);
471}
472
473static void verity_work(struct work_struct *w)
474{
475 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
476
477 verity_finish_io(io, verity_verify_io(io));
478}
479
480static void verity_end_io(struct bio *bio)
481{
482 struct dm_verity_io *io = bio->bi_private;
483
484 if (bio->bi_error && !verity_fec_is_enabled(io->v)) {
485 verity_finish_io(io, bio->bi_error);
486 return;
487 }
488
489 INIT_WORK(&io->work, verity_work);
490 queue_work(io->v->verify_wq, &io->work);
491}
492
493/*
494 * Prefetch buffers for the specified io.
495 * The root buffer is not prefetched, it is assumed that it will be cached
496 * all the time.
497 */
498static void verity_prefetch_io(struct work_struct *work)
499{
500 struct dm_verity_prefetch_work *pw =
501 container_of(work, struct dm_verity_prefetch_work, work);
502 struct dm_verity *v = pw->v;
503 int i;
504
505 for (i = v->levels - 2; i >= 0; i--) {
506 sector_t hash_block_start;
507 sector_t hash_block_end;
508 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
509 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
510 if (!i) {
511 unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
512
513 cluster >>= v->data_dev_block_bits;
514 if (unlikely(!cluster))
515 goto no_prefetch_cluster;
516
517 if (unlikely(cluster & (cluster - 1)))
518 cluster = 1 << __fls(cluster);
519
520 hash_block_start &= ~(sector_t)(cluster - 1);
521 hash_block_end |= cluster - 1;
522 if (unlikely(hash_block_end >= v->hash_blocks))
523 hash_block_end = v->hash_blocks - 1;
524 }
525no_prefetch_cluster:
526 dm_bufio_prefetch(v->bufio, hash_block_start,
527 hash_block_end - hash_block_start + 1);
528 }
529
530 kfree(pw);
531}
532
533static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
534{
535 struct dm_verity_prefetch_work *pw;
536
537 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
538 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
539
540 if (!pw)
541 return;
542
543 INIT_WORK(&pw->work, verity_prefetch_io);
544 pw->v = v;
545 pw->block = io->block;
546 pw->n_blocks = io->n_blocks;
547 queue_work(v->verify_wq, &pw->work);
548}
549
550/*
551 * Bio map function. It allocates dm_verity_io structure and bio vector and
552 * fills them. Then it issues prefetches and the I/O.
553 */
554static int verity_map(struct dm_target *ti, struct bio *bio)
555{
556 struct dm_verity *v = ti->private;
557 struct dm_verity_io *io;
558
559 bio->bi_bdev = v->data_dev->bdev;
560 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
561
562 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
563 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
564 DMERR_LIMIT("unaligned io");
565 return -EIO;
566 }
567
568 if (bio_end_sector(bio) >>
569 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
570 DMERR_LIMIT("io out of range");
571 return -EIO;
572 }
573
574 if (bio_data_dir(bio) == WRITE)
575 return -EIO;
576
577 io = dm_per_bio_data(bio, ti->per_io_data_size);
578 io->v = v;
579 io->orig_bi_end_io = bio->bi_end_io;
580 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
581 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
582
583 bio->bi_end_io = verity_end_io;
584 bio->bi_private = io;
585 io->iter = bio->bi_iter;
586
587 verity_fec_init_io(io);
588
589 verity_submit_prefetch(v, io);
590
591 generic_make_request(bio);
592
593 return DM_MAPIO_SUBMITTED;
594}
595
596/*
597 * Status: V (valid) or C (corruption found)
598 */
599static void verity_status(struct dm_target *ti, status_type_t type,
600 unsigned status_flags, char *result, unsigned maxlen)
601{
602 struct dm_verity *v = ti->private;
603 unsigned args = 0;
604 unsigned sz = 0;
605 unsigned x;
606
607 switch (type) {
608 case STATUSTYPE_INFO:
609 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
610 break;
611 case STATUSTYPE_TABLE:
612 DMEMIT("%u %s %s %u %u %llu %llu %s ",
613 v->version,
614 v->data_dev->name,
615 v->hash_dev->name,
616 1 << v->data_dev_block_bits,
617 1 << v->hash_dev_block_bits,
618 (unsigned long long)v->data_blocks,
619 (unsigned long long)v->hash_start,
620 v->alg_name
621 );
622 for (x = 0; x < v->digest_size; x++)
623 DMEMIT("%02x", v->root_digest[x]);
624 DMEMIT(" ");
625 if (!v->salt_size)
626 DMEMIT("-");
627 else
628 for (x = 0; x < v->salt_size; x++)
629 DMEMIT("%02x", v->salt[x]);
630 if (v->mode != DM_VERITY_MODE_EIO)
631 args++;
632 if (verity_fec_is_enabled(v))
633 args += DM_VERITY_OPTS_FEC;
634 if (v->zero_digest)
635 args++;
636 if (!args)
637 return;
638 DMEMIT(" %u", args);
639 if (v->mode != DM_VERITY_MODE_EIO) {
640 DMEMIT(" ");
641 switch (v->mode) {
642 case DM_VERITY_MODE_LOGGING:
643 DMEMIT(DM_VERITY_OPT_LOGGING);
644 break;
645 case DM_VERITY_MODE_RESTART:
646 DMEMIT(DM_VERITY_OPT_RESTART);
647 break;
648 default:
649 BUG();
650 }
651 }
652 if (v->zero_digest)
653 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
654 sz = verity_fec_status_table(v, sz, result, maxlen);
655 break;
656 }
657}
658
659static int verity_prepare_ioctl(struct dm_target *ti,
660 struct block_device **bdev, fmode_t *mode)
661{
662 struct dm_verity *v = ti->private;
663
664 *bdev = v->data_dev->bdev;
665
666 if (v->data_start ||
667 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
668 return 1;
669 return 0;
670}
671
672static int verity_iterate_devices(struct dm_target *ti,
673 iterate_devices_callout_fn fn, void *data)
674{
675 struct dm_verity *v = ti->private;
676
677 return fn(ti, v->data_dev, v->data_start, ti->len, data);
678}
679
680static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
681{
682 struct dm_verity *v = ti->private;
683
684 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
685 limits->logical_block_size = 1 << v->data_dev_block_bits;
686
687 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
688 limits->physical_block_size = 1 << v->data_dev_block_bits;
689
690 blk_limits_io_min(limits, limits->logical_block_size);
691}
692
693static void verity_dtr(struct dm_target *ti)
694{
695 struct dm_verity *v = ti->private;
696
697 if (v->verify_wq)
698 destroy_workqueue(v->verify_wq);
699
700 if (v->bufio)
701 dm_bufio_client_destroy(v->bufio);
702
703 kfree(v->salt);
704 kfree(v->root_digest);
705 kfree(v->zero_digest);
706
707 if (v->tfm)
708 crypto_free_shash(v->tfm);
709
710 kfree(v->alg_name);
711
712 if (v->hash_dev)
713 dm_put_device(ti, v->hash_dev);
714
715 if (v->data_dev)
716 dm_put_device(ti, v->data_dev);
717
718 verity_fec_dtr(v);
719
720 kfree(v);
721}
722
723static int verity_alloc_zero_digest(struct dm_verity *v)
724{
725 int r = -ENOMEM;
726 struct shash_desc *desc;
727 u8 *zero_data;
728
729 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
730
731 if (!v->zero_digest)
732 return r;
733
734 desc = kmalloc(v->shash_descsize, GFP_KERNEL);
735
736 if (!desc)
737 return r; /* verity_dtr will free zero_digest */
738
739 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
740
741 if (!zero_data)
742 goto out;
743
744 r = verity_hash(v, desc, zero_data, 1 << v->data_dev_block_bits,
745 v->zero_digest);
746
747out:
748 kfree(desc);
749 kfree(zero_data);
750
751 return r;
752}
753
754static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
755{
756 int r;
757 unsigned argc;
758 struct dm_target *ti = v->ti;
759 const char *arg_name;
760
761 static struct dm_arg _args[] = {
762 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
763 };
764
765 r = dm_read_arg_group(_args, as, &argc, &ti->error);
766 if (r)
767 return -EINVAL;
768
769 if (!argc)
770 return 0;
771
772 do {
773 arg_name = dm_shift_arg(as);
774 argc--;
775
776 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
777 v->mode = DM_VERITY_MODE_LOGGING;
778 continue;
779
780 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
781 v->mode = DM_VERITY_MODE_RESTART;
782 continue;
783
784 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
785 r = verity_alloc_zero_digest(v);
786 if (r) {
787 ti->error = "Cannot allocate zero digest";
788 return r;
789 }
790 continue;
791
792 } else if (verity_is_fec_opt_arg(arg_name)) {
793 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
794 if (r)
795 return r;
796 continue;
797 }
798
799 ti->error = "Unrecognized verity feature request";
800 return -EINVAL;
801 } while (argc && !r);
802
803 return r;
804}
805
806/*
807 * Target parameters:
808 * <version> The current format is version 1.
809 * Vsn 0 is compatible with original Chromium OS releases.
810 * <data device>
811 * <hash device>
812 * <data block size>
813 * <hash block size>
814 * <the number of data blocks>
815 * <hash start block>
816 * <algorithm>
817 * <digest>
818 * <salt> Hex string or "-" if no salt.
819 */
820static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
821{
822 struct dm_verity *v;
823 struct dm_arg_set as;
824 unsigned int num;
825 unsigned long long num_ll;
826 int r;
827 int i;
828 sector_t hash_position;
829 char dummy;
830
831 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
832 if (!v) {
833 ti->error = "Cannot allocate verity structure";
834 return -ENOMEM;
835 }
836 ti->private = v;
837 v->ti = ti;
838
839 r = verity_fec_ctr_alloc(v);
840 if (r)
841 goto bad;
842
843 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
844 ti->error = "Device must be readonly";
845 r = -EINVAL;
846 goto bad;
847 }
848
849 if (argc < 10) {
850 ti->error = "Not enough arguments";
851 r = -EINVAL;
852 goto bad;
853 }
854
855 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
856 num > 1) {
857 ti->error = "Invalid version";
858 r = -EINVAL;
859 goto bad;
860 }
861 v->version = num;
862
863 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
864 if (r) {
865 ti->error = "Data device lookup failed";
866 goto bad;
867 }
868
869 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
870 if (r) {
871 ti->error = "Hash device lookup failed";
872 goto bad;
873 }
874
875 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
876 !num || (num & (num - 1)) ||
877 num < bdev_logical_block_size(v->data_dev->bdev) ||
878 num > PAGE_SIZE) {
879 ti->error = "Invalid data device block size";
880 r = -EINVAL;
881 goto bad;
882 }
883 v->data_dev_block_bits = __ffs(num);
884
885 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
886 !num || (num & (num - 1)) ||
887 num < bdev_logical_block_size(v->hash_dev->bdev) ||
888 num > INT_MAX) {
889 ti->error = "Invalid hash device block size";
890 r = -EINVAL;
891 goto bad;
892 }
893 v->hash_dev_block_bits = __ffs(num);
894
895 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
896 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
897 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
898 ti->error = "Invalid data blocks";
899 r = -EINVAL;
900 goto bad;
901 }
902 v->data_blocks = num_ll;
903
904 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
905 ti->error = "Data device is too small";
906 r = -EINVAL;
907 goto bad;
908 }
909
910 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
911 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
912 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
913 ti->error = "Invalid hash start";
914 r = -EINVAL;
915 goto bad;
916 }
917 v->hash_start = num_ll;
918
919 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
920 if (!v->alg_name) {
921 ti->error = "Cannot allocate algorithm name";
922 r = -ENOMEM;
923 goto bad;
924 }
925
926 v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
927 if (IS_ERR(v->tfm)) {
928 ti->error = "Cannot initialize hash function";
929 r = PTR_ERR(v->tfm);
930 v->tfm = NULL;
931 goto bad;
932 }
933 v->digest_size = crypto_shash_digestsize(v->tfm);
934 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
935 ti->error = "Digest size too big";
936 r = -EINVAL;
937 goto bad;
938 }
939 v->shash_descsize =
940 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
941
942 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
943 if (!v->root_digest) {
944 ti->error = "Cannot allocate root digest";
945 r = -ENOMEM;
946 goto bad;
947 }
948 if (strlen(argv[8]) != v->digest_size * 2 ||
949 hex2bin(v->root_digest, argv[8], v->digest_size)) {
950 ti->error = "Invalid root digest";
951 r = -EINVAL;
952 goto bad;
953 }
954
955 if (strcmp(argv[9], "-")) {
956 v->salt_size = strlen(argv[9]) / 2;
957 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
958 if (!v->salt) {
959 ti->error = "Cannot allocate salt";
960 r = -ENOMEM;
961 goto bad;
962 }
963 if (strlen(argv[9]) != v->salt_size * 2 ||
964 hex2bin(v->salt, argv[9], v->salt_size)) {
965 ti->error = "Invalid salt";
966 r = -EINVAL;
967 goto bad;
968 }
969 }
970
971 argv += 10;
972 argc -= 10;
973
974 /* Optional parameters */
975 if (argc) {
976 as.argc = argc;
977 as.argv = argv;
978
979 r = verity_parse_opt_args(&as, v);
980 if (r < 0)
981 goto bad;
982 }
983
984 v->hash_per_block_bits =
985 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
986
987 v->levels = 0;
988 if (v->data_blocks)
989 while (v->hash_per_block_bits * v->levels < 64 &&
990 (unsigned long long)(v->data_blocks - 1) >>
991 (v->hash_per_block_bits * v->levels))
992 v->levels++;
993
994 if (v->levels > DM_VERITY_MAX_LEVELS) {
995 ti->error = "Too many tree levels";
996 r = -E2BIG;
997 goto bad;
998 }
999
1000 hash_position = v->hash_start;
1001 for (i = v->levels - 1; i >= 0; i--) {
1002 sector_t s;
1003 v->hash_level_block[i] = hash_position;
1004 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1005 >> ((i + 1) * v->hash_per_block_bits);
1006 if (hash_position + s < hash_position) {
1007 ti->error = "Hash device offset overflow";
1008 r = -E2BIG;
1009 goto bad;
1010 }
1011 hash_position += s;
1012 }
1013 v->hash_blocks = hash_position;
1014
1015 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1016 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1017 dm_bufio_alloc_callback, NULL);
1018 if (IS_ERR(v->bufio)) {
1019 ti->error = "Cannot initialize dm-bufio";
1020 r = PTR_ERR(v->bufio);
1021 v->bufio = NULL;
1022 goto bad;
1023 }
1024
1025 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1026 ti->error = "Hash device is too small";
1027 r = -E2BIG;
1028 goto bad;
1029 }
1030
1031 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1032 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1033 if (!v->verify_wq) {
1034 ti->error = "Cannot allocate workqueue";
1035 r = -ENOMEM;
1036 goto bad;
1037 }
1038
1039 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1040 v->shash_descsize + v->digest_size * 2;
1041
1042 r = verity_fec_ctr(v);
1043 if (r)
1044 goto bad;
1045
1046 ti->per_io_data_size = roundup(ti->per_io_data_size,
1047 __alignof__(struct dm_verity_io));
1048
1049 return 0;
1050
1051bad:
1052 verity_dtr(ti);
1053
1054 return r;
1055}
1056
1057static struct target_type verity_target = {
1058 .name = "verity",
1059 .version = {1, 3, 0},
1060 .module = THIS_MODULE,
1061 .ctr = verity_ctr,
1062 .dtr = verity_dtr,
1063 .map = verity_map,
1064 .status = verity_status,
1065 .prepare_ioctl = verity_prepare_ioctl,
1066 .iterate_devices = verity_iterate_devices,
1067 .io_hints = verity_io_hints,
1068};
1069
1070static int __init dm_verity_init(void)
1071{
1072 int r;
1073
1074 r = dm_register_target(&verity_target);
1075 if (r < 0)
1076 DMERR("register failed %d", r);
1077
1078 return r;
1079}
1080
1081static void __exit dm_verity_exit(void)
1082{
1083 dm_unregister_target(&verity_target);
1084}
1085
1086module_init(dm_verity_init);
1087module_exit(dm_verity_exit);
1088
1089MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1090MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1091MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1092MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1093MODULE_LICENSE("GPL");