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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
26#define DM_MSG_PREFIX "verity"
27
28#define DM_VERITY_ENV_LENGTH 42
29#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
30
31#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
32
33#define DM_VERITY_MAX_CORRUPTED_ERRS 100
34
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"
41
42#define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \
43 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
44
45static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
46
47module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
48
49static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
50
51struct dm_verity_prefetch_work {
52 struct work_struct work;
53 struct dm_verity *v;
54 sector_t block;
55 unsigned int n_blocks;
56};
57
58/*
59 * Auxiliary structure appended to each dm-bufio buffer. If the value
60 * hash_verified is nonzero, hash of the block has been verified.
61 *
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.
64 *
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.
69 */
70struct buffer_aux {
71 int hash_verified;
72};
73
74/*
75 * Initialize struct buffer_aux for a freshly created buffer.
76 */
77static void dm_bufio_alloc_callback(struct dm_buffer *buf)
78{
79 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
80
81 aux->hash_verified = 0;
82}
83
84/*
85 * Translate input sector number to the sector number on the target device.
86 */
87static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
88{
89 return v->data_start + dm_target_offset(v->ti, bi_sector);
90}
91
92/*
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.
97 */
98static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
99 int level)
100{
101 return block >> (level * v->hash_per_block_bits);
102}
103
104static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
105 const u8 *data, size_t len,
106 struct crypto_wait *wait)
107{
108 struct scatterlist sg;
109
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);
114 }
115
116 do {
117 int r;
118 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
119
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);
125 if (unlikely(r))
126 return r;
127 data += this_step;
128 len -= this_step;
129 } while (len);
130
131 return 0;
132}
133
134/*
135 * Wrapper for crypto_ahash_init, which handles verity salting.
136 */
137static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
138 struct crypto_wait *wait, bool may_sleep)
139{
140 int r;
141
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);
147
148 r = crypto_wait_req(crypto_ahash_init(req), wait);
149
150 if (unlikely(r < 0)) {
151 if (r != -ENOMEM)
152 DMERR("crypto_ahash_init failed: %d", r);
153 return r;
154 }
155
156 if (likely(v->salt_size && (v->version >= 1)))
157 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
158
159 return r;
160}
161
162static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
163 u8 *digest, struct crypto_wait *wait)
164{
165 int r;
166
167 if (unlikely(v->salt_size && (!v->version))) {
168 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
169
170 if (r < 0) {
171 DMERR("%s failed updating salt: %d", __func__, r);
172 goto out;
173 }
174 }
175
176 ahash_request_set_crypt(req, NULL, digest, 0);
177 r = crypto_wait_req(crypto_ahash_final(req), wait);
178out:
179 return r;
180}
181
182int verity_hash(struct dm_verity *v, struct ahash_request *req,
183 const u8 *data, size_t len, u8 *digest, bool may_sleep)
184{
185 int r;
186 struct crypto_wait wait;
187
188 r = verity_hash_init(v, req, &wait, may_sleep);
189 if (unlikely(r < 0))
190 goto out;
191
192 r = verity_hash_update(v, req, data, len, &wait);
193 if (unlikely(r < 0))
194 goto out;
195
196 r = verity_hash_final(v, req, digest, &wait);
197
198out:
199 return r;
200}
201
202static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
203 sector_t *hash_block, unsigned int *offset)
204{
205 sector_t position = verity_position_at_level(v, block, level);
206 unsigned int idx;
207
208 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
209
210 if (!offset)
211 return;
212
213 idx = position & ((1 << v->hash_per_block_bits) - 1);
214 if (!v->version)
215 *offset = idx * v->digest_size;
216 else
217 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
218}
219
220/*
221 * Handle verification errors.
222 */
223static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
224 unsigned long long block)
225{
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);
230
231 /* Corruption should be visible in device status in all modes */
232 v->hash_failed = true;
233
234 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
235 goto out;
236
237 v->corrupted_errs++;
238
239 switch (type) {
240 case DM_VERITY_BLOCK_TYPE_DATA:
241 type_str = "data";
242 break;
243 case DM_VERITY_BLOCK_TYPE_METADATA:
244 type_str = "metadata";
245 break;
246 default:
247 BUG();
248 }
249
250 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
251 type_str, block);
252
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);
256 }
257
258 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
259 DM_VERITY_ENV_VAR_NAME, type, block);
260
261 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
262
263out:
264 if (v->mode == DM_VERITY_MODE_LOGGING)
265 return 0;
266
267 if (v->mode == DM_VERITY_MODE_RESTART)
268 kernel_restart("dm-verity device corrupted");
269
270 if (v->mode == DM_VERITY_MODE_PANIC)
271 panic("dm-verity device corrupted");
272
273 return 1;
274}
275
276/*
277 * Verify hash of a metadata block pertaining to the specified data block
278 * ("block" argument) at a specified level ("level" argument).
279 *
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).
282 *
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).
286 */
287static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
288 sector_t block, int level, bool skip_unverified,
289 u8 *want_digest)
290{
291 struct dm_buffer *buf;
292 struct buffer_aux *aux;
293 u8 *data;
294 int r;
295 sector_t hash_block;
296 unsigned int offset;
297
298 verity_hash_at_level(v, block, level, &hash_block, &offset);
299
300 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
301 data = dm_bufio_get(v->bufio, hash_block, &buf);
302 if (data == NULL) {
303 /*
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.
307 */
308 return -EAGAIN;
309 }
310 } else
311 data = dm_bufio_read(v->bufio, hash_block, &buf);
312
313 if (IS_ERR(data))
314 return PTR_ERR(data);
315
316 aux = dm_bufio_get_aux_data(buf);
317
318 if (!aux->hash_verified) {
319 if (skip_unverified) {
320 r = 1;
321 goto release_ret_r;
322 }
323
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);
327 if (unlikely(r < 0))
328 goto release_ret_r;
329
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) &&
334 io->in_tasklet) {
335 /*
336 * Error handling code (FEC included) cannot be run in a
337 * tasklet since it may sleep, so fallback to work-queue.
338 */
339 r = -EAGAIN;
340 goto release_ret_r;
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,
346 hash_block)) {
347 struct bio *bio =
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,
351 block, 0);
352 r = -EIO;
353 goto release_ret_r;
354 }
355 }
356
357 data += offset;
358 memcpy(want_digest, data, v->digest_size);
359 r = 0;
360
361release_ret_r:
362 dm_bufio_release(buf);
363 return r;
364}
365
366/*
367 * Find a hash for a given block, write it to digest and verify the integrity
368 * of the hash tree if necessary.
369 */
370int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
371 sector_t block, u8 *digest, bool *is_zero)
372{
373 int r = 0, i;
374
375 if (likely(v->levels)) {
376 /*
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.
382 */
383 r = verity_verify_level(v, io, block, 0, true, digest);
384 if (likely(r <= 0))
385 goto out;
386 }
387
388 memcpy(digest, v->root_digest, v->digest_size);
389
390 for (i = v->levels - 1; i >= 0; i--) {
391 r = verity_verify_level(v, io, block, i, false, digest);
392 if (unlikely(r))
393 goto out;
394 }
395out:
396 if (!r && v->zero_digest)
397 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
398 else
399 *is_zero = false;
400
401 return r;
402}
403
404/*
405 * Calculates the digest for the given bio
406 */
407static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
408 struct bvec_iter *iter, struct crypto_wait *wait)
409{
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);
414
415 do {
416 int r;
417 unsigned int len;
418 struct bio_vec bv = bio_iter_iovec(bio, *iter);
419
420 sg_init_table(&sg, 1);
421
422 len = bv.bv_len;
423
424 if (likely(len >= todo))
425 len = todo;
426 /*
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.
430 */
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);
434
435 if (unlikely(r < 0)) {
436 DMERR("%s crypto op failed: %d", __func__, r);
437 return r;
438 }
439
440 bio_advance_iter(bio, iter, len);
441 todo -= len;
442 } while (todo);
443
444 return 0;
445}
446
447/*
448 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
449 * starting from iter.
450 */
451int 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,
455 size_t len))
456{
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);
459
460 do {
461 int r;
462 u8 *page;
463 unsigned int len;
464 struct bio_vec bv = bio_iter_iovec(bio, *iter);
465
466 page = bvec_kmap_local(&bv);
467 len = bv.bv_len;
468
469 if (likely(len >= todo))
470 len = todo;
471
472 r = process(v, io, page, len);
473 kunmap_local(page);
474
475 if (r < 0)
476 return r;
477
478 bio_advance_iter(bio, iter, len);
479 todo -= len;
480 } while (todo);
481
482 return 0;
483}
484
485static int verity_recheck_copy(struct dm_verity *v, struct dm_verity_io *io,
486 u8 *data, size_t len)
487{
488 memcpy(data, io->recheck_buffer, len);
489 io->recheck_buffer += len;
490
491 return 0;
492}
493
494static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
495 struct bvec_iter start, sector_t cur_block)
496{
497 struct page *page;
498 void *buffer;
499 int r;
500 struct dm_io_request io_req;
501 struct dm_io_region io_loc;
502
503 page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
504 buffer = page_to_virt(page);
505
506 io_req.bi_opf = REQ_OP_READ;
507 io_req.mem.type = DM_IO_KMEM;
508 io_req.mem.ptr.addr = buffer;
509 io_req.notify.fn = NULL;
510 io_req.client = v->io;
511 io_loc.bdev = v->data_dev->bdev;
512 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
513 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
514 r = dm_io(&io_req, 1, &io_loc, NULL);
515 if (unlikely(r))
516 goto free_ret;
517
518 r = verity_hash(v, verity_io_hash_req(v, io), buffer,
519 1 << v->data_dev_block_bits,
520 verity_io_real_digest(v, io), true);
521 if (unlikely(r))
522 goto free_ret;
523
524 if (memcmp(verity_io_real_digest(v, io),
525 verity_io_want_digest(v, io), v->digest_size)) {
526 r = -EIO;
527 goto free_ret;
528 }
529
530 io->recheck_buffer = buffer;
531 r = verity_for_bv_block(v, io, &start, verity_recheck_copy);
532 if (unlikely(r))
533 goto free_ret;
534
535 r = 0;
536free_ret:
537 mempool_free(page, &v->recheck_pool);
538
539 return r;
540}
541
542static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
543 u8 *data, size_t len)
544{
545 memset(data, 0, len);
546 return 0;
547}
548
549/*
550 * Moves the bio iter one data block forward.
551 */
552static inline void verity_bv_skip_block(struct dm_verity *v,
553 struct dm_verity_io *io,
554 struct bvec_iter *iter)
555{
556 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
557
558 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
559}
560
561/*
562 * Verify one "dm_verity_io" structure.
563 */
564static int verity_verify_io(struct dm_verity_io *io)
565{
566 bool is_zero;
567 struct dm_verity *v = io->v;
568 struct bvec_iter start;
569 struct bvec_iter iter_copy;
570 struct bvec_iter *iter;
571 struct crypto_wait wait;
572 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
573 unsigned int b;
574
575 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
576 /*
577 * Copy the iterator in case we need to restart
578 * verification in a work-queue.
579 */
580 iter_copy = io->iter;
581 iter = &iter_copy;
582 } else
583 iter = &io->iter;
584
585 for (b = 0; b < io->n_blocks; b++) {
586 int r;
587 sector_t cur_block = io->block + b;
588 struct ahash_request *req = verity_io_hash_req(v, io);
589
590 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
591 likely(test_bit(cur_block, v->validated_blocks))) {
592 verity_bv_skip_block(v, io, iter);
593 continue;
594 }
595
596 r = verity_hash_for_block(v, io, cur_block,
597 verity_io_want_digest(v, io),
598 &is_zero);
599 if (unlikely(r < 0))
600 return r;
601
602 if (is_zero) {
603 /*
604 * If we expect a zero block, don't validate, just
605 * return zeros.
606 */
607 r = verity_for_bv_block(v, io, iter,
608 verity_bv_zero);
609 if (unlikely(r < 0))
610 return r;
611
612 continue;
613 }
614
615 r = verity_hash_init(v, req, &wait, !io->in_tasklet);
616 if (unlikely(r < 0))
617 return r;
618
619 start = *iter;
620 r = verity_for_io_block(v, io, iter, &wait);
621 if (unlikely(r < 0))
622 return r;
623
624 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
625 &wait);
626 if (unlikely(r < 0))
627 return r;
628
629 if (likely(memcmp(verity_io_real_digest(v, io),
630 verity_io_want_digest(v, io), v->digest_size) == 0)) {
631 if (v->validated_blocks)
632 set_bit(cur_block, v->validated_blocks);
633 continue;
634 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
635 io->in_tasklet) {
636 /*
637 * Error handling code (FEC included) cannot be run in a
638 * tasklet since it may sleep, so fallback to work-queue.
639 */
640 return -EAGAIN;
641 } else if (verity_recheck(v, io, start, cur_block) == 0) {
642 if (v->validated_blocks)
643 set_bit(cur_block, v->validated_blocks);
644 continue;
645#if defined(CONFIG_DM_VERITY_FEC)
646 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
647 cur_block, NULL, &start) == 0) {
648 continue;
649#endif
650 } else {
651 if (bio->bi_status) {
652 /*
653 * Error correction failed; Just return error
654 */
655 return -EIO;
656 }
657 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
658 cur_block)) {
659 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
660 bio, cur_block, 0);
661 return -EIO;
662 }
663 }
664 }
665
666 return 0;
667}
668
669/*
670 * Skip verity work in response to I/O error when system is shutting down.
671 */
672static inline bool verity_is_system_shutting_down(void)
673{
674 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
675 || system_state == SYSTEM_RESTART;
676}
677
678/*
679 * End one "io" structure with a given error.
680 */
681static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
682{
683 struct dm_verity *v = io->v;
684 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
685
686 bio->bi_end_io = io->orig_bi_end_io;
687 bio->bi_status = status;
688
689 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
690 verity_fec_finish_io(io);
691
692 bio_endio(bio);
693}
694
695static void verity_work(struct work_struct *w)
696{
697 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
698
699 io->in_tasklet = false;
700
701 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
702}
703
704static void verity_end_io(struct bio *bio)
705{
706 struct dm_verity_io *io = bio->bi_private;
707
708 if (bio->bi_status &&
709 (!verity_fec_is_enabled(io->v) ||
710 verity_is_system_shutting_down() ||
711 (bio->bi_opf & REQ_RAHEAD))) {
712 verity_finish_io(io, bio->bi_status);
713 return;
714 }
715
716 INIT_WORK(&io->work, verity_work);
717 queue_work(io->v->verify_wq, &io->work);
718}
719
720/*
721 * Prefetch buffers for the specified io.
722 * The root buffer is not prefetched, it is assumed that it will be cached
723 * all the time.
724 */
725static void verity_prefetch_io(struct work_struct *work)
726{
727 struct dm_verity_prefetch_work *pw =
728 container_of(work, struct dm_verity_prefetch_work, work);
729 struct dm_verity *v = pw->v;
730 int i;
731
732 for (i = v->levels - 2; i >= 0; i--) {
733 sector_t hash_block_start;
734 sector_t hash_block_end;
735
736 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
737 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
738
739 if (!i) {
740 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
741
742 cluster >>= v->data_dev_block_bits;
743 if (unlikely(!cluster))
744 goto no_prefetch_cluster;
745
746 if (unlikely(cluster & (cluster - 1)))
747 cluster = 1 << __fls(cluster);
748
749 hash_block_start &= ~(sector_t)(cluster - 1);
750 hash_block_end |= cluster - 1;
751 if (unlikely(hash_block_end >= v->hash_blocks))
752 hash_block_end = v->hash_blocks - 1;
753 }
754no_prefetch_cluster:
755 dm_bufio_prefetch(v->bufio, hash_block_start,
756 hash_block_end - hash_block_start + 1);
757 }
758
759 kfree(pw);
760}
761
762static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
763{
764 sector_t block = io->block;
765 unsigned int n_blocks = io->n_blocks;
766 struct dm_verity_prefetch_work *pw;
767
768 if (v->validated_blocks) {
769 while (n_blocks && test_bit(block, v->validated_blocks)) {
770 block++;
771 n_blocks--;
772 }
773 while (n_blocks && test_bit(block + n_blocks - 1,
774 v->validated_blocks))
775 n_blocks--;
776 if (!n_blocks)
777 return;
778 }
779
780 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
781 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
782
783 if (!pw)
784 return;
785
786 INIT_WORK(&pw->work, verity_prefetch_io);
787 pw->v = v;
788 pw->block = block;
789 pw->n_blocks = n_blocks;
790 queue_work(v->verify_wq, &pw->work);
791}
792
793/*
794 * Bio map function. It allocates dm_verity_io structure and bio vector and
795 * fills them. Then it issues prefetches and the I/O.
796 */
797static int verity_map(struct dm_target *ti, struct bio *bio)
798{
799 struct dm_verity *v = ti->private;
800 struct dm_verity_io *io;
801
802 bio_set_dev(bio, v->data_dev->bdev);
803 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
804
805 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
806 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
807 DMERR_LIMIT("unaligned io");
808 return DM_MAPIO_KILL;
809 }
810
811 if (bio_end_sector(bio) >>
812 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
813 DMERR_LIMIT("io out of range");
814 return DM_MAPIO_KILL;
815 }
816
817 if (bio_data_dir(bio) == WRITE)
818 return DM_MAPIO_KILL;
819
820 io = dm_per_bio_data(bio, ti->per_io_data_size);
821 io->v = v;
822 io->orig_bi_end_io = bio->bi_end_io;
823 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
824 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
825
826 bio->bi_end_io = verity_end_io;
827 bio->bi_private = io;
828 io->iter = bio->bi_iter;
829
830 verity_fec_init_io(io);
831
832 verity_submit_prefetch(v, io);
833
834 submit_bio_noacct(bio);
835
836 return DM_MAPIO_SUBMITTED;
837}
838
839/*
840 * Status: V (valid) or C (corruption found)
841 */
842static void verity_status(struct dm_target *ti, status_type_t type,
843 unsigned int status_flags, char *result, unsigned int maxlen)
844{
845 struct dm_verity *v = ti->private;
846 unsigned int args = 0;
847 unsigned int sz = 0;
848 unsigned int x;
849
850 switch (type) {
851 case STATUSTYPE_INFO:
852 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
853 break;
854 case STATUSTYPE_TABLE:
855 DMEMIT("%u %s %s %u %u %llu %llu %s ",
856 v->version,
857 v->data_dev->name,
858 v->hash_dev->name,
859 1 << v->data_dev_block_bits,
860 1 << v->hash_dev_block_bits,
861 (unsigned long long)v->data_blocks,
862 (unsigned long long)v->hash_start,
863 v->alg_name
864 );
865 for (x = 0; x < v->digest_size; x++)
866 DMEMIT("%02x", v->root_digest[x]);
867 DMEMIT(" ");
868 if (!v->salt_size)
869 DMEMIT("-");
870 else
871 for (x = 0; x < v->salt_size; x++)
872 DMEMIT("%02x", v->salt[x]);
873 if (v->mode != DM_VERITY_MODE_EIO)
874 args++;
875 if (verity_fec_is_enabled(v))
876 args += DM_VERITY_OPTS_FEC;
877 if (v->zero_digest)
878 args++;
879 if (v->validated_blocks)
880 args++;
881 if (v->use_tasklet)
882 args++;
883 if (v->signature_key_desc)
884 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
885 if (!args)
886 return;
887 DMEMIT(" %u", args);
888 if (v->mode != DM_VERITY_MODE_EIO) {
889 DMEMIT(" ");
890 switch (v->mode) {
891 case DM_VERITY_MODE_LOGGING:
892 DMEMIT(DM_VERITY_OPT_LOGGING);
893 break;
894 case DM_VERITY_MODE_RESTART:
895 DMEMIT(DM_VERITY_OPT_RESTART);
896 break;
897 case DM_VERITY_MODE_PANIC:
898 DMEMIT(DM_VERITY_OPT_PANIC);
899 break;
900 default:
901 BUG();
902 }
903 }
904 if (v->zero_digest)
905 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
906 if (v->validated_blocks)
907 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
908 if (v->use_tasklet)
909 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
910 sz = verity_fec_status_table(v, sz, result, maxlen);
911 if (v->signature_key_desc)
912 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
913 " %s", v->signature_key_desc);
914 break;
915
916 case STATUSTYPE_IMA:
917 DMEMIT_TARGET_NAME_VERSION(ti->type);
918 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
919 DMEMIT(",verity_version=%u", v->version);
920 DMEMIT(",data_device_name=%s", v->data_dev->name);
921 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
922 DMEMIT(",verity_algorithm=%s", v->alg_name);
923
924 DMEMIT(",root_digest=");
925 for (x = 0; x < v->digest_size; x++)
926 DMEMIT("%02x", v->root_digest[x]);
927
928 DMEMIT(",salt=");
929 if (!v->salt_size)
930 DMEMIT("-");
931 else
932 for (x = 0; x < v->salt_size; x++)
933 DMEMIT("%02x", v->salt[x]);
934
935 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
936 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
937 if (v->signature_key_desc)
938 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
939
940 if (v->mode != DM_VERITY_MODE_EIO) {
941 DMEMIT(",verity_mode=");
942 switch (v->mode) {
943 case DM_VERITY_MODE_LOGGING:
944 DMEMIT(DM_VERITY_OPT_LOGGING);
945 break;
946 case DM_VERITY_MODE_RESTART:
947 DMEMIT(DM_VERITY_OPT_RESTART);
948 break;
949 case DM_VERITY_MODE_PANIC:
950 DMEMIT(DM_VERITY_OPT_PANIC);
951 break;
952 default:
953 DMEMIT("invalid");
954 }
955 }
956 DMEMIT(";");
957 break;
958 }
959}
960
961static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
962{
963 struct dm_verity *v = ti->private;
964
965 *bdev = v->data_dev->bdev;
966
967 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
968 return 1;
969 return 0;
970}
971
972static int verity_iterate_devices(struct dm_target *ti,
973 iterate_devices_callout_fn fn, void *data)
974{
975 struct dm_verity *v = ti->private;
976
977 return fn(ti, v->data_dev, v->data_start, ti->len, data);
978}
979
980static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
981{
982 struct dm_verity *v = ti->private;
983
984 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
985 limits->logical_block_size = 1 << v->data_dev_block_bits;
986
987 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
988 limits->physical_block_size = 1 << v->data_dev_block_bits;
989
990 blk_limits_io_min(limits, limits->logical_block_size);
991}
992
993static void verity_dtr(struct dm_target *ti)
994{
995 struct dm_verity *v = ti->private;
996
997 if (v->verify_wq)
998 destroy_workqueue(v->verify_wq);
999
1000 mempool_exit(&v->recheck_pool);
1001 if (v->io)
1002 dm_io_client_destroy(v->io);
1003
1004 if (v->bufio)
1005 dm_bufio_client_destroy(v->bufio);
1006
1007 kvfree(v->validated_blocks);
1008 kfree(v->salt);
1009 kfree(v->root_digest);
1010 kfree(v->zero_digest);
1011
1012 if (v->tfm)
1013 crypto_free_ahash(v->tfm);
1014
1015 kfree(v->alg_name);
1016
1017 if (v->hash_dev)
1018 dm_put_device(ti, v->hash_dev);
1019
1020 if (v->data_dev)
1021 dm_put_device(ti, v->data_dev);
1022
1023 verity_fec_dtr(v);
1024
1025 kfree(v->signature_key_desc);
1026
1027 if (v->use_tasklet)
1028 static_branch_dec(&use_tasklet_enabled);
1029
1030 kfree(v);
1031
1032 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1033}
1034
1035static int verity_alloc_most_once(struct dm_verity *v)
1036{
1037 struct dm_target *ti = v->ti;
1038
1039 /* the bitset can only handle INT_MAX blocks */
1040 if (v->data_blocks > INT_MAX) {
1041 ti->error = "device too large to use check_at_most_once";
1042 return -E2BIG;
1043 }
1044
1045 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1046 sizeof(unsigned long),
1047 GFP_KERNEL);
1048 if (!v->validated_blocks) {
1049 ti->error = "failed to allocate bitset for check_at_most_once";
1050 return -ENOMEM;
1051 }
1052
1053 return 0;
1054}
1055
1056static int verity_alloc_zero_digest(struct dm_verity *v)
1057{
1058 int r = -ENOMEM;
1059 struct ahash_request *req;
1060 u8 *zero_data;
1061
1062 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1063
1064 if (!v->zero_digest)
1065 return r;
1066
1067 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1068
1069 if (!req)
1070 return r; /* verity_dtr will free zero_digest */
1071
1072 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1073
1074 if (!zero_data)
1075 goto out;
1076
1077 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1078 v->zero_digest, true);
1079
1080out:
1081 kfree(req);
1082 kfree(zero_data);
1083
1084 return r;
1085}
1086
1087static inline bool verity_is_verity_mode(const char *arg_name)
1088{
1089 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1090 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1091 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1092}
1093
1094static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1095{
1096 if (v->mode)
1097 return -EINVAL;
1098
1099 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1100 v->mode = DM_VERITY_MODE_LOGGING;
1101 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1102 v->mode = DM_VERITY_MODE_RESTART;
1103 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1104 v->mode = DM_VERITY_MODE_PANIC;
1105
1106 return 0;
1107}
1108
1109static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1110 struct dm_verity_sig_opts *verify_args,
1111 bool only_modifier_opts)
1112{
1113 int r = 0;
1114 unsigned int argc;
1115 struct dm_target *ti = v->ti;
1116 const char *arg_name;
1117
1118 static const struct dm_arg _args[] = {
1119 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1120 };
1121
1122 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1123 if (r)
1124 return -EINVAL;
1125
1126 if (!argc)
1127 return 0;
1128
1129 do {
1130 arg_name = dm_shift_arg(as);
1131 argc--;
1132
1133 if (verity_is_verity_mode(arg_name)) {
1134 if (only_modifier_opts)
1135 continue;
1136 r = verity_parse_verity_mode(v, arg_name);
1137 if (r) {
1138 ti->error = "Conflicting error handling parameters";
1139 return r;
1140 }
1141 continue;
1142
1143 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1144 if (only_modifier_opts)
1145 continue;
1146 r = verity_alloc_zero_digest(v);
1147 if (r) {
1148 ti->error = "Cannot allocate zero digest";
1149 return r;
1150 }
1151 continue;
1152
1153 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1154 if (only_modifier_opts)
1155 continue;
1156 r = verity_alloc_most_once(v);
1157 if (r)
1158 return r;
1159 continue;
1160
1161 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1162 v->use_tasklet = true;
1163 static_branch_inc(&use_tasklet_enabled);
1164 continue;
1165
1166 } else if (verity_is_fec_opt_arg(arg_name)) {
1167 if (only_modifier_opts)
1168 continue;
1169 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1170 if (r)
1171 return r;
1172 continue;
1173
1174 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1175 if (only_modifier_opts)
1176 continue;
1177 r = verity_verify_sig_parse_opt_args(as, v,
1178 verify_args,
1179 &argc, arg_name);
1180 if (r)
1181 return r;
1182 continue;
1183
1184 } else if (only_modifier_opts) {
1185 /*
1186 * Ignore unrecognized opt, could easily be an extra
1187 * argument to an option whose parsing was skipped.
1188 * Normal parsing (@only_modifier_opts=false) will
1189 * properly parse all options (and their extra args).
1190 */
1191 continue;
1192 }
1193
1194 DMERR("Unrecognized verity feature request: %s", arg_name);
1195 ti->error = "Unrecognized verity feature request";
1196 return -EINVAL;
1197 } while (argc && !r);
1198
1199 return r;
1200}
1201
1202/*
1203 * Target parameters:
1204 * <version> The current format is version 1.
1205 * Vsn 0 is compatible with original Chromium OS releases.
1206 * <data device>
1207 * <hash device>
1208 * <data block size>
1209 * <hash block size>
1210 * <the number of data blocks>
1211 * <hash start block>
1212 * <algorithm>
1213 * <digest>
1214 * <salt> Hex string or "-" if no salt.
1215 */
1216static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1217{
1218 struct dm_verity *v;
1219 struct dm_verity_sig_opts verify_args = {0};
1220 struct dm_arg_set as;
1221 unsigned int num;
1222 unsigned long long num_ll;
1223 int r;
1224 int i;
1225 sector_t hash_position;
1226 char dummy;
1227 char *root_hash_digest_to_validate;
1228
1229 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1230 if (!v) {
1231 ti->error = "Cannot allocate verity structure";
1232 return -ENOMEM;
1233 }
1234 ti->private = v;
1235 v->ti = ti;
1236
1237 r = verity_fec_ctr_alloc(v);
1238 if (r)
1239 goto bad;
1240
1241 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1242 ti->error = "Device must be readonly";
1243 r = -EINVAL;
1244 goto bad;
1245 }
1246
1247 if (argc < 10) {
1248 ti->error = "Not enough arguments";
1249 r = -EINVAL;
1250 goto bad;
1251 }
1252
1253 /* Parse optional parameters that modify primary args */
1254 if (argc > 10) {
1255 as.argc = argc - 10;
1256 as.argv = argv + 10;
1257 r = verity_parse_opt_args(&as, v, &verify_args, true);
1258 if (r < 0)
1259 goto bad;
1260 }
1261
1262 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1263 num > 1) {
1264 ti->error = "Invalid version";
1265 r = -EINVAL;
1266 goto bad;
1267 }
1268 v->version = num;
1269
1270 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1271 if (r) {
1272 ti->error = "Data device lookup failed";
1273 goto bad;
1274 }
1275
1276 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1277 if (r) {
1278 ti->error = "Hash device lookup failed";
1279 goto bad;
1280 }
1281
1282 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1283 !num || (num & (num - 1)) ||
1284 num < bdev_logical_block_size(v->data_dev->bdev) ||
1285 num > PAGE_SIZE) {
1286 ti->error = "Invalid data device block size";
1287 r = -EINVAL;
1288 goto bad;
1289 }
1290 v->data_dev_block_bits = __ffs(num);
1291
1292 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1293 !num || (num & (num - 1)) ||
1294 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1295 num > INT_MAX) {
1296 ti->error = "Invalid hash device block size";
1297 r = -EINVAL;
1298 goto bad;
1299 }
1300 v->hash_dev_block_bits = __ffs(num);
1301
1302 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1303 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1304 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1305 ti->error = "Invalid data blocks";
1306 r = -EINVAL;
1307 goto bad;
1308 }
1309 v->data_blocks = num_ll;
1310
1311 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1312 ti->error = "Data device is too small";
1313 r = -EINVAL;
1314 goto bad;
1315 }
1316
1317 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1318 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1319 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1320 ti->error = "Invalid hash start";
1321 r = -EINVAL;
1322 goto bad;
1323 }
1324 v->hash_start = num_ll;
1325
1326 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1327 if (!v->alg_name) {
1328 ti->error = "Cannot allocate algorithm name";
1329 r = -ENOMEM;
1330 goto bad;
1331 }
1332
1333 v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1334 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1335 if (IS_ERR(v->tfm)) {
1336 ti->error = "Cannot initialize hash function";
1337 r = PTR_ERR(v->tfm);
1338 v->tfm = NULL;
1339 goto bad;
1340 }
1341
1342 /*
1343 * dm-verity performance can vary greatly depending on which hash
1344 * algorithm implementation is used. Help people debug performance
1345 * problems by logging the ->cra_driver_name.
1346 */
1347 DMINFO("%s using implementation \"%s\"", v->alg_name,
1348 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1349
1350 v->digest_size = crypto_ahash_digestsize(v->tfm);
1351 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1352 ti->error = "Digest size too big";
1353 r = -EINVAL;
1354 goto bad;
1355 }
1356 v->ahash_reqsize = sizeof(struct ahash_request) +
1357 crypto_ahash_reqsize(v->tfm);
1358
1359 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1360 if (!v->root_digest) {
1361 ti->error = "Cannot allocate root digest";
1362 r = -ENOMEM;
1363 goto bad;
1364 }
1365 if (strlen(argv[8]) != v->digest_size * 2 ||
1366 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1367 ti->error = "Invalid root digest";
1368 r = -EINVAL;
1369 goto bad;
1370 }
1371 root_hash_digest_to_validate = argv[8];
1372
1373 if (strcmp(argv[9], "-")) {
1374 v->salt_size = strlen(argv[9]) / 2;
1375 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1376 if (!v->salt) {
1377 ti->error = "Cannot allocate salt";
1378 r = -ENOMEM;
1379 goto bad;
1380 }
1381 if (strlen(argv[9]) != v->salt_size * 2 ||
1382 hex2bin(v->salt, argv[9], v->salt_size)) {
1383 ti->error = "Invalid salt";
1384 r = -EINVAL;
1385 goto bad;
1386 }
1387 }
1388
1389 argv += 10;
1390 argc -= 10;
1391
1392 /* Optional parameters */
1393 if (argc) {
1394 as.argc = argc;
1395 as.argv = argv;
1396 r = verity_parse_opt_args(&as, v, &verify_args, false);
1397 if (r < 0)
1398 goto bad;
1399 }
1400
1401 /* Root hash signature is a optional parameter*/
1402 r = verity_verify_root_hash(root_hash_digest_to_validate,
1403 strlen(root_hash_digest_to_validate),
1404 verify_args.sig,
1405 verify_args.sig_size);
1406 if (r < 0) {
1407 ti->error = "Root hash verification failed";
1408 goto bad;
1409 }
1410 v->hash_per_block_bits =
1411 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1412
1413 v->levels = 0;
1414 if (v->data_blocks)
1415 while (v->hash_per_block_bits * v->levels < 64 &&
1416 (unsigned long long)(v->data_blocks - 1) >>
1417 (v->hash_per_block_bits * v->levels))
1418 v->levels++;
1419
1420 if (v->levels > DM_VERITY_MAX_LEVELS) {
1421 ti->error = "Too many tree levels";
1422 r = -E2BIG;
1423 goto bad;
1424 }
1425
1426 hash_position = v->hash_start;
1427 for (i = v->levels - 1; i >= 0; i--) {
1428 sector_t s;
1429
1430 v->hash_level_block[i] = hash_position;
1431 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1432 >> ((i + 1) * v->hash_per_block_bits);
1433 if (hash_position + s < hash_position) {
1434 ti->error = "Hash device offset overflow";
1435 r = -E2BIG;
1436 goto bad;
1437 }
1438 hash_position += s;
1439 }
1440 v->hash_blocks = hash_position;
1441
1442 r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1443 if (unlikely(r)) {
1444 ti->error = "Cannot allocate mempool";
1445 goto bad;
1446 }
1447
1448 v->io = dm_io_client_create();
1449 if (IS_ERR(v->io)) {
1450 r = PTR_ERR(v->io);
1451 v->io = NULL;
1452 ti->error = "Cannot allocate dm io";
1453 goto bad;
1454 }
1455
1456 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1457 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1458 dm_bufio_alloc_callback, NULL,
1459 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1460 if (IS_ERR(v->bufio)) {
1461 ti->error = "Cannot initialize dm-bufio";
1462 r = PTR_ERR(v->bufio);
1463 v->bufio = NULL;
1464 goto bad;
1465 }
1466
1467 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1468 ti->error = "Hash device is too small";
1469 r = -E2BIG;
1470 goto bad;
1471 }
1472
1473 /*
1474 * Using WQ_HIGHPRI improves throughput and completion latency by
1475 * reducing wait times when reading from a dm-verity device.
1476 *
1477 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1478 * allows verify_wq to preempt softirq since verification in tasklet
1479 * will fall-back to using it for error handling (or if the bufio cache
1480 * doesn't have required hashes).
1481 */
1482 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1483 if (!v->verify_wq) {
1484 ti->error = "Cannot allocate workqueue";
1485 r = -ENOMEM;
1486 goto bad;
1487 }
1488
1489 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1490 v->ahash_reqsize + v->digest_size * 2;
1491
1492 r = verity_fec_ctr(v);
1493 if (r)
1494 goto bad;
1495
1496 ti->per_io_data_size = roundup(ti->per_io_data_size,
1497 __alignof__(struct dm_verity_io));
1498
1499 verity_verify_sig_opts_cleanup(&verify_args);
1500
1501 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1502
1503 return 0;
1504
1505bad:
1506
1507 verity_verify_sig_opts_cleanup(&verify_args);
1508 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1509 verity_dtr(ti);
1510
1511 return r;
1512}
1513
1514/*
1515 * Check whether a DM target is a verity target.
1516 */
1517bool dm_is_verity_target(struct dm_target *ti)
1518{
1519 return ti->type->module == THIS_MODULE;
1520}
1521
1522/*
1523 * Get the verity mode (error behavior) of a verity target.
1524 *
1525 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1526 * target.
1527 */
1528int dm_verity_get_mode(struct dm_target *ti)
1529{
1530 struct dm_verity *v = ti->private;
1531
1532 if (!dm_is_verity_target(ti))
1533 return -EINVAL;
1534
1535 return v->mode;
1536}
1537
1538/*
1539 * Get the root digest of a verity target.
1540 *
1541 * Returns a copy of the root digest, the caller is responsible for
1542 * freeing the memory of the digest.
1543 */
1544int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1545{
1546 struct dm_verity *v = ti->private;
1547
1548 if (!dm_is_verity_target(ti))
1549 return -EINVAL;
1550
1551 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1552 if (*root_digest == NULL)
1553 return -ENOMEM;
1554
1555 *digest_size = v->digest_size;
1556
1557 return 0;
1558}
1559
1560static struct target_type verity_target = {
1561 .name = "verity",
1562 .features = DM_TARGET_IMMUTABLE,
1563 .version = {1, 10, 0},
1564 .module = THIS_MODULE,
1565 .ctr = verity_ctr,
1566 .dtr = verity_dtr,
1567 .map = verity_map,
1568 .status = verity_status,
1569 .prepare_ioctl = verity_prepare_ioctl,
1570 .iterate_devices = verity_iterate_devices,
1571 .io_hints = verity_io_hints,
1572};
1573module_dm(verity);
1574
1575MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1576MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1577MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1578MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1579MODULE_LICENSE("GPL");
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 <linux/module.h>
20#include <linux/reboot.h>
21
22#define DM_MSG_PREFIX "verity"
23
24#define DM_VERITY_ENV_LENGTH 42
25#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
26
27#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
28
29#define DM_VERITY_MAX_CORRUPTED_ERRS 100
30
31#define DM_VERITY_OPT_LOGGING "ignore_corruption"
32#define DM_VERITY_OPT_RESTART "restart_on_corruption"
33#define DM_VERITY_OPT_PANIC "panic_on_corruption"
34#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
35#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
36
37#define DM_VERITY_OPTS_MAX (3 + DM_VERITY_OPTS_FEC + \
38 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
39
40static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
41
42module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
43
44struct dm_verity_prefetch_work {
45 struct work_struct work;
46 struct dm_verity *v;
47 sector_t block;
48 unsigned n_blocks;
49};
50
51/*
52 * Auxiliary structure appended to each dm-bufio buffer. If the value
53 * hash_verified is nonzero, hash of the block has been verified.
54 *
55 * The variable hash_verified is set to 0 when allocating the buffer, then
56 * it can be changed to 1 and it is never reset to 0 again.
57 *
58 * There is no lock around this value, a race condition can at worst cause
59 * that multiple processes verify the hash of the same buffer simultaneously
60 * and write 1 to hash_verified simultaneously.
61 * This condition is harmless, so we don't need locking.
62 */
63struct buffer_aux {
64 int hash_verified;
65};
66
67/*
68 * Initialize struct buffer_aux for a freshly created buffer.
69 */
70static void dm_bufio_alloc_callback(struct dm_buffer *buf)
71{
72 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
73
74 aux->hash_verified = 0;
75}
76
77/*
78 * Translate input sector number to the sector number on the target device.
79 */
80static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
81{
82 return v->data_start + dm_target_offset(v->ti, bi_sector);
83}
84
85/*
86 * Return hash position of a specified block at a specified tree level
87 * (0 is the lowest level).
88 * The lowest "hash_per_block_bits"-bits of the result denote hash position
89 * inside a hash block. The remaining bits denote location of the hash block.
90 */
91static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
92 int level)
93{
94 return block >> (level * v->hash_per_block_bits);
95}
96
97static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
98 const u8 *data, size_t len,
99 struct crypto_wait *wait)
100{
101 struct scatterlist sg;
102
103 if (likely(!is_vmalloc_addr(data))) {
104 sg_init_one(&sg, data, len);
105 ahash_request_set_crypt(req, &sg, NULL, len);
106 return crypto_wait_req(crypto_ahash_update(req), wait);
107 } else {
108 do {
109 int r;
110 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
111 flush_kernel_vmap_range((void *)data, this_step);
112 sg_init_table(&sg, 1);
113 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
114 ahash_request_set_crypt(req, &sg, NULL, this_step);
115 r = crypto_wait_req(crypto_ahash_update(req), wait);
116 if (unlikely(r))
117 return r;
118 data += this_step;
119 len -= this_step;
120 } while (len);
121 return 0;
122 }
123}
124
125/*
126 * Wrapper for crypto_ahash_init, which handles verity salting.
127 */
128static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
129 struct crypto_wait *wait)
130{
131 int r;
132
133 ahash_request_set_tfm(req, v->tfm);
134 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
135 CRYPTO_TFM_REQ_MAY_BACKLOG,
136 crypto_req_done, (void *)wait);
137 crypto_init_wait(wait);
138
139 r = crypto_wait_req(crypto_ahash_init(req), wait);
140
141 if (unlikely(r < 0)) {
142 DMERR("crypto_ahash_init failed: %d", r);
143 return r;
144 }
145
146 if (likely(v->salt_size && (v->version >= 1)))
147 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
148
149 return r;
150}
151
152static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
153 u8 *digest, struct crypto_wait *wait)
154{
155 int r;
156
157 if (unlikely(v->salt_size && (!v->version))) {
158 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
159
160 if (r < 0) {
161 DMERR("verity_hash_final failed updating salt: %d", r);
162 goto out;
163 }
164 }
165
166 ahash_request_set_crypt(req, NULL, digest, 0);
167 r = crypto_wait_req(crypto_ahash_final(req), wait);
168out:
169 return r;
170}
171
172int verity_hash(struct dm_verity *v, struct ahash_request *req,
173 const u8 *data, size_t len, u8 *digest)
174{
175 int r;
176 struct crypto_wait wait;
177
178 r = verity_hash_init(v, req, &wait);
179 if (unlikely(r < 0))
180 goto out;
181
182 r = verity_hash_update(v, req, data, len, &wait);
183 if (unlikely(r < 0))
184 goto out;
185
186 r = verity_hash_final(v, req, digest, &wait);
187
188out:
189 return r;
190}
191
192static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
193 sector_t *hash_block, unsigned *offset)
194{
195 sector_t position = verity_position_at_level(v, block, level);
196 unsigned idx;
197
198 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
199
200 if (!offset)
201 return;
202
203 idx = position & ((1 << v->hash_per_block_bits) - 1);
204 if (!v->version)
205 *offset = idx * v->digest_size;
206 else
207 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
208}
209
210/*
211 * Handle verification errors.
212 */
213static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
214 unsigned long long block)
215{
216 char verity_env[DM_VERITY_ENV_LENGTH];
217 char *envp[] = { verity_env, NULL };
218 const char *type_str = "";
219 struct mapped_device *md = dm_table_get_md(v->ti->table);
220
221 /* Corruption should be visible in device status in all modes */
222 v->hash_failed = 1;
223
224 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
225 goto out;
226
227 v->corrupted_errs++;
228
229 switch (type) {
230 case DM_VERITY_BLOCK_TYPE_DATA:
231 type_str = "data";
232 break;
233 case DM_VERITY_BLOCK_TYPE_METADATA:
234 type_str = "metadata";
235 break;
236 default:
237 BUG();
238 }
239
240 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
241 type_str, block);
242
243 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
244 DMERR("%s: reached maximum errors", v->data_dev->name);
245
246 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
247 DM_VERITY_ENV_VAR_NAME, type, block);
248
249 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
250
251out:
252 if (v->mode == DM_VERITY_MODE_LOGGING)
253 return 0;
254
255 if (v->mode == DM_VERITY_MODE_RESTART)
256 kernel_restart("dm-verity device corrupted");
257
258 if (v->mode == DM_VERITY_MODE_PANIC)
259 panic("dm-verity device corrupted");
260
261 return 1;
262}
263
264/*
265 * Verify hash of a metadata block pertaining to the specified data block
266 * ("block" argument) at a specified level ("level" argument).
267 *
268 * On successful return, verity_io_want_digest(v, io) contains the hash value
269 * for a lower tree level or for the data block (if we're at the lowest level).
270 *
271 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
272 * If "skip_unverified" is false, unverified buffer is hashed and verified
273 * against current value of verity_io_want_digest(v, io).
274 */
275static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
276 sector_t block, int level, bool skip_unverified,
277 u8 *want_digest)
278{
279 struct dm_buffer *buf;
280 struct buffer_aux *aux;
281 u8 *data;
282 int r;
283 sector_t hash_block;
284 unsigned offset;
285
286 verity_hash_at_level(v, block, level, &hash_block, &offset);
287
288 data = dm_bufio_read(v->bufio, hash_block, &buf);
289 if (IS_ERR(data))
290 return PTR_ERR(data);
291
292 aux = dm_bufio_get_aux_data(buf);
293
294 if (!aux->hash_verified) {
295 if (skip_unverified) {
296 r = 1;
297 goto release_ret_r;
298 }
299
300 r = verity_hash(v, verity_io_hash_req(v, io),
301 data, 1 << v->hash_dev_block_bits,
302 verity_io_real_digest(v, io));
303 if (unlikely(r < 0))
304 goto release_ret_r;
305
306 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
307 v->digest_size) == 0))
308 aux->hash_verified = 1;
309 else if (verity_fec_decode(v, io,
310 DM_VERITY_BLOCK_TYPE_METADATA,
311 hash_block, data, NULL) == 0)
312 aux->hash_verified = 1;
313 else if (verity_handle_err(v,
314 DM_VERITY_BLOCK_TYPE_METADATA,
315 hash_block)) {
316 r = -EIO;
317 goto release_ret_r;
318 }
319 }
320
321 data += offset;
322 memcpy(want_digest, data, v->digest_size);
323 r = 0;
324
325release_ret_r:
326 dm_bufio_release(buf);
327 return r;
328}
329
330/*
331 * Find a hash for a given block, write it to digest and verify the integrity
332 * of the hash tree if necessary.
333 */
334int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
335 sector_t block, u8 *digest, bool *is_zero)
336{
337 int r = 0, i;
338
339 if (likely(v->levels)) {
340 /*
341 * First, we try to get the requested hash for
342 * the current block. If the hash block itself is
343 * verified, zero is returned. If it isn't, this
344 * function returns 1 and we fall back to whole
345 * chain verification.
346 */
347 r = verity_verify_level(v, io, block, 0, true, digest);
348 if (likely(r <= 0))
349 goto out;
350 }
351
352 memcpy(digest, v->root_digest, v->digest_size);
353
354 for (i = v->levels - 1; i >= 0; i--) {
355 r = verity_verify_level(v, io, block, i, false, digest);
356 if (unlikely(r))
357 goto out;
358 }
359out:
360 if (!r && v->zero_digest)
361 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
362 else
363 *is_zero = false;
364
365 return r;
366}
367
368/*
369 * Calculates the digest for the given bio
370 */
371static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
372 struct bvec_iter *iter, struct crypto_wait *wait)
373{
374 unsigned int todo = 1 << v->data_dev_block_bits;
375 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
376 struct scatterlist sg;
377 struct ahash_request *req = verity_io_hash_req(v, io);
378
379 do {
380 int r;
381 unsigned int len;
382 struct bio_vec bv = bio_iter_iovec(bio, *iter);
383
384 sg_init_table(&sg, 1);
385
386 len = bv.bv_len;
387
388 if (likely(len >= todo))
389 len = todo;
390 /*
391 * Operating on a single page at a time looks suboptimal
392 * until you consider the typical block size is 4,096B.
393 * Going through this loops twice should be very rare.
394 */
395 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
396 ahash_request_set_crypt(req, &sg, NULL, len);
397 r = crypto_wait_req(crypto_ahash_update(req), wait);
398
399 if (unlikely(r < 0)) {
400 DMERR("verity_for_io_block crypto op failed: %d", r);
401 return r;
402 }
403
404 bio_advance_iter(bio, iter, len);
405 todo -= len;
406 } while (todo);
407
408 return 0;
409}
410
411/*
412 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
413 * starting from iter.
414 */
415int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
416 struct bvec_iter *iter,
417 int (*process)(struct dm_verity *v,
418 struct dm_verity_io *io, u8 *data,
419 size_t len))
420{
421 unsigned todo = 1 << v->data_dev_block_bits;
422 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
423
424 do {
425 int r;
426 u8 *page;
427 unsigned len;
428 struct bio_vec bv = bio_iter_iovec(bio, *iter);
429
430 page = kmap_atomic(bv.bv_page);
431 len = bv.bv_len;
432
433 if (likely(len >= todo))
434 len = todo;
435
436 r = process(v, io, page + bv.bv_offset, len);
437 kunmap_atomic(page);
438
439 if (r < 0)
440 return r;
441
442 bio_advance_iter(bio, iter, len);
443 todo -= len;
444 } while (todo);
445
446 return 0;
447}
448
449static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
450 u8 *data, size_t len)
451{
452 memset(data, 0, len);
453 return 0;
454}
455
456/*
457 * Moves the bio iter one data block forward.
458 */
459static inline void verity_bv_skip_block(struct dm_verity *v,
460 struct dm_verity_io *io,
461 struct bvec_iter *iter)
462{
463 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
464
465 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
466}
467
468/*
469 * Verify one "dm_verity_io" structure.
470 */
471static int verity_verify_io(struct dm_verity_io *io)
472{
473 bool is_zero;
474 struct dm_verity *v = io->v;
475 struct bvec_iter start;
476 unsigned b;
477 struct crypto_wait wait;
478
479 for (b = 0; b < io->n_blocks; b++) {
480 int r;
481 sector_t cur_block = io->block + b;
482 struct ahash_request *req = verity_io_hash_req(v, io);
483
484 if (v->validated_blocks &&
485 likely(test_bit(cur_block, v->validated_blocks))) {
486 verity_bv_skip_block(v, io, &io->iter);
487 continue;
488 }
489
490 r = verity_hash_for_block(v, io, cur_block,
491 verity_io_want_digest(v, io),
492 &is_zero);
493 if (unlikely(r < 0))
494 return r;
495
496 if (is_zero) {
497 /*
498 * If we expect a zero block, don't validate, just
499 * return zeros.
500 */
501 r = verity_for_bv_block(v, io, &io->iter,
502 verity_bv_zero);
503 if (unlikely(r < 0))
504 return r;
505
506 continue;
507 }
508
509 r = verity_hash_init(v, req, &wait);
510 if (unlikely(r < 0))
511 return r;
512
513 start = io->iter;
514 r = verity_for_io_block(v, io, &io->iter, &wait);
515 if (unlikely(r < 0))
516 return r;
517
518 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
519 &wait);
520 if (unlikely(r < 0))
521 return r;
522
523 if (likely(memcmp(verity_io_real_digest(v, io),
524 verity_io_want_digest(v, io), v->digest_size) == 0)) {
525 if (v->validated_blocks)
526 set_bit(cur_block, v->validated_blocks);
527 continue;
528 }
529 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
530 cur_block, NULL, &start) == 0)
531 continue;
532 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
533 cur_block))
534 return -EIO;
535 }
536
537 return 0;
538}
539
540/*
541 * Skip verity work in response to I/O error when system is shutting down.
542 */
543static inline bool verity_is_system_shutting_down(void)
544{
545 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
546 || system_state == SYSTEM_RESTART;
547}
548
549/*
550 * End one "io" structure with a given error.
551 */
552static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
553{
554 struct dm_verity *v = io->v;
555 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
556
557 bio->bi_end_io = io->orig_bi_end_io;
558 bio->bi_status = status;
559
560 verity_fec_finish_io(io);
561
562 bio_endio(bio);
563}
564
565static void verity_work(struct work_struct *w)
566{
567 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
568
569 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
570}
571
572static void verity_end_io(struct bio *bio)
573{
574 struct dm_verity_io *io = bio->bi_private;
575
576 if (bio->bi_status &&
577 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
578 verity_finish_io(io, bio->bi_status);
579 return;
580 }
581
582 INIT_WORK(&io->work, verity_work);
583 queue_work(io->v->verify_wq, &io->work);
584}
585
586/*
587 * Prefetch buffers for the specified io.
588 * The root buffer is not prefetched, it is assumed that it will be cached
589 * all the time.
590 */
591static void verity_prefetch_io(struct work_struct *work)
592{
593 struct dm_verity_prefetch_work *pw =
594 container_of(work, struct dm_verity_prefetch_work, work);
595 struct dm_verity *v = pw->v;
596 int i;
597
598 for (i = v->levels - 2; i >= 0; i--) {
599 sector_t hash_block_start;
600 sector_t hash_block_end;
601 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
602 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
603 if (!i) {
604 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
605
606 cluster >>= v->data_dev_block_bits;
607 if (unlikely(!cluster))
608 goto no_prefetch_cluster;
609
610 if (unlikely(cluster & (cluster - 1)))
611 cluster = 1 << __fls(cluster);
612
613 hash_block_start &= ~(sector_t)(cluster - 1);
614 hash_block_end |= cluster - 1;
615 if (unlikely(hash_block_end >= v->hash_blocks))
616 hash_block_end = v->hash_blocks - 1;
617 }
618no_prefetch_cluster:
619 dm_bufio_prefetch(v->bufio, hash_block_start,
620 hash_block_end - hash_block_start + 1);
621 }
622
623 kfree(pw);
624}
625
626static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
627{
628 sector_t block = io->block;
629 unsigned int n_blocks = io->n_blocks;
630 struct dm_verity_prefetch_work *pw;
631
632 if (v->validated_blocks) {
633 while (n_blocks && test_bit(block, v->validated_blocks)) {
634 block++;
635 n_blocks--;
636 }
637 while (n_blocks && test_bit(block + n_blocks - 1,
638 v->validated_blocks))
639 n_blocks--;
640 if (!n_blocks)
641 return;
642 }
643
644 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
645 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
646
647 if (!pw)
648 return;
649
650 INIT_WORK(&pw->work, verity_prefetch_io);
651 pw->v = v;
652 pw->block = block;
653 pw->n_blocks = n_blocks;
654 queue_work(v->verify_wq, &pw->work);
655}
656
657/*
658 * Bio map function. It allocates dm_verity_io structure and bio vector and
659 * fills them. Then it issues prefetches and the I/O.
660 */
661static int verity_map(struct dm_target *ti, struct bio *bio)
662{
663 struct dm_verity *v = ti->private;
664 struct dm_verity_io *io;
665
666 bio_set_dev(bio, v->data_dev->bdev);
667 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
668
669 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
670 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
671 DMERR_LIMIT("unaligned io");
672 return DM_MAPIO_KILL;
673 }
674
675 if (bio_end_sector(bio) >>
676 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
677 DMERR_LIMIT("io out of range");
678 return DM_MAPIO_KILL;
679 }
680
681 if (bio_data_dir(bio) == WRITE)
682 return DM_MAPIO_KILL;
683
684 io = dm_per_bio_data(bio, ti->per_io_data_size);
685 io->v = v;
686 io->orig_bi_end_io = bio->bi_end_io;
687 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
688 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
689
690 bio->bi_end_io = verity_end_io;
691 bio->bi_private = io;
692 io->iter = bio->bi_iter;
693
694 verity_fec_init_io(io);
695
696 verity_submit_prefetch(v, io);
697
698 submit_bio_noacct(bio);
699
700 return DM_MAPIO_SUBMITTED;
701}
702
703/*
704 * Status: V (valid) or C (corruption found)
705 */
706static void verity_status(struct dm_target *ti, status_type_t type,
707 unsigned status_flags, char *result, unsigned maxlen)
708{
709 struct dm_verity *v = ti->private;
710 unsigned args = 0;
711 unsigned sz = 0;
712 unsigned x;
713
714 switch (type) {
715 case STATUSTYPE_INFO:
716 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
717 break;
718 case STATUSTYPE_TABLE:
719 DMEMIT("%u %s %s %u %u %llu %llu %s ",
720 v->version,
721 v->data_dev->name,
722 v->hash_dev->name,
723 1 << v->data_dev_block_bits,
724 1 << v->hash_dev_block_bits,
725 (unsigned long long)v->data_blocks,
726 (unsigned long long)v->hash_start,
727 v->alg_name
728 );
729 for (x = 0; x < v->digest_size; x++)
730 DMEMIT("%02x", v->root_digest[x]);
731 DMEMIT(" ");
732 if (!v->salt_size)
733 DMEMIT("-");
734 else
735 for (x = 0; x < v->salt_size; x++)
736 DMEMIT("%02x", v->salt[x]);
737 if (v->mode != DM_VERITY_MODE_EIO)
738 args++;
739 if (verity_fec_is_enabled(v))
740 args += DM_VERITY_OPTS_FEC;
741 if (v->zero_digest)
742 args++;
743 if (v->validated_blocks)
744 args++;
745 if (v->signature_key_desc)
746 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
747 if (!args)
748 return;
749 DMEMIT(" %u", args);
750 if (v->mode != DM_VERITY_MODE_EIO) {
751 DMEMIT(" ");
752 switch (v->mode) {
753 case DM_VERITY_MODE_LOGGING:
754 DMEMIT(DM_VERITY_OPT_LOGGING);
755 break;
756 case DM_VERITY_MODE_RESTART:
757 DMEMIT(DM_VERITY_OPT_RESTART);
758 break;
759 case DM_VERITY_MODE_PANIC:
760 DMEMIT(DM_VERITY_OPT_PANIC);
761 break;
762 default:
763 BUG();
764 }
765 }
766 if (v->zero_digest)
767 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
768 if (v->validated_blocks)
769 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
770 sz = verity_fec_status_table(v, sz, result, maxlen);
771 if (v->signature_key_desc)
772 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
773 " %s", v->signature_key_desc);
774 break;
775 }
776}
777
778static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
779{
780 struct dm_verity *v = ti->private;
781
782 *bdev = v->data_dev->bdev;
783
784 if (v->data_start ||
785 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
786 return 1;
787 return 0;
788}
789
790static int verity_iterate_devices(struct dm_target *ti,
791 iterate_devices_callout_fn fn, void *data)
792{
793 struct dm_verity *v = ti->private;
794
795 return fn(ti, v->data_dev, v->data_start, ti->len, data);
796}
797
798static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
799{
800 struct dm_verity *v = ti->private;
801
802 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
803 limits->logical_block_size = 1 << v->data_dev_block_bits;
804
805 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
806 limits->physical_block_size = 1 << v->data_dev_block_bits;
807
808 blk_limits_io_min(limits, limits->logical_block_size);
809}
810
811static void verity_dtr(struct dm_target *ti)
812{
813 struct dm_verity *v = ti->private;
814
815 if (v->verify_wq)
816 destroy_workqueue(v->verify_wq);
817
818 if (v->bufio)
819 dm_bufio_client_destroy(v->bufio);
820
821 kvfree(v->validated_blocks);
822 kfree(v->salt);
823 kfree(v->root_digest);
824 kfree(v->zero_digest);
825
826 if (v->tfm)
827 crypto_free_ahash(v->tfm);
828
829 kfree(v->alg_name);
830
831 if (v->hash_dev)
832 dm_put_device(ti, v->hash_dev);
833
834 if (v->data_dev)
835 dm_put_device(ti, v->data_dev);
836
837 verity_fec_dtr(v);
838
839 kfree(v->signature_key_desc);
840
841 kfree(v);
842}
843
844static int verity_alloc_most_once(struct dm_verity *v)
845{
846 struct dm_target *ti = v->ti;
847
848 /* the bitset can only handle INT_MAX blocks */
849 if (v->data_blocks > INT_MAX) {
850 ti->error = "device too large to use check_at_most_once";
851 return -E2BIG;
852 }
853
854 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
855 sizeof(unsigned long),
856 GFP_KERNEL);
857 if (!v->validated_blocks) {
858 ti->error = "failed to allocate bitset for check_at_most_once";
859 return -ENOMEM;
860 }
861
862 return 0;
863}
864
865static int verity_alloc_zero_digest(struct dm_verity *v)
866{
867 int r = -ENOMEM;
868 struct ahash_request *req;
869 u8 *zero_data;
870
871 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
872
873 if (!v->zero_digest)
874 return r;
875
876 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
877
878 if (!req)
879 return r; /* verity_dtr will free zero_digest */
880
881 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
882
883 if (!zero_data)
884 goto out;
885
886 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
887 v->zero_digest);
888
889out:
890 kfree(req);
891 kfree(zero_data);
892
893 return r;
894}
895
896static inline bool verity_is_verity_mode(const char *arg_name)
897{
898 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
899 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
900 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
901}
902
903static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
904{
905 if (v->mode)
906 return -EINVAL;
907
908 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
909 v->mode = DM_VERITY_MODE_LOGGING;
910 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
911 v->mode = DM_VERITY_MODE_RESTART;
912 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
913 v->mode = DM_VERITY_MODE_PANIC;
914
915 return 0;
916}
917
918static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
919 struct dm_verity_sig_opts *verify_args)
920{
921 int r;
922 unsigned argc;
923 struct dm_target *ti = v->ti;
924 const char *arg_name;
925
926 static const struct dm_arg _args[] = {
927 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
928 };
929
930 r = dm_read_arg_group(_args, as, &argc, &ti->error);
931 if (r)
932 return -EINVAL;
933
934 if (!argc)
935 return 0;
936
937 do {
938 arg_name = dm_shift_arg(as);
939 argc--;
940
941 if (verity_is_verity_mode(arg_name)) {
942 r = verity_parse_verity_mode(v, arg_name);
943 if (r) {
944 ti->error = "Conflicting error handling parameters";
945 return r;
946 }
947 continue;
948
949 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
950 r = verity_alloc_zero_digest(v);
951 if (r) {
952 ti->error = "Cannot allocate zero digest";
953 return r;
954 }
955 continue;
956
957 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
958 r = verity_alloc_most_once(v);
959 if (r)
960 return r;
961 continue;
962
963 } else if (verity_is_fec_opt_arg(arg_name)) {
964 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
965 if (r)
966 return r;
967 continue;
968 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
969 r = verity_verify_sig_parse_opt_args(as, v,
970 verify_args,
971 &argc, arg_name);
972 if (r)
973 return r;
974 continue;
975
976 }
977
978 ti->error = "Unrecognized verity feature request";
979 return -EINVAL;
980 } while (argc && !r);
981
982 return r;
983}
984
985/*
986 * Target parameters:
987 * <version> The current format is version 1.
988 * Vsn 0 is compatible with original Chromium OS releases.
989 * <data device>
990 * <hash device>
991 * <data block size>
992 * <hash block size>
993 * <the number of data blocks>
994 * <hash start block>
995 * <algorithm>
996 * <digest>
997 * <salt> Hex string or "-" if no salt.
998 */
999static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
1000{
1001 struct dm_verity *v;
1002 struct dm_verity_sig_opts verify_args = {0};
1003 struct dm_arg_set as;
1004 unsigned int num;
1005 unsigned long long num_ll;
1006 int r;
1007 int i;
1008 sector_t hash_position;
1009 char dummy;
1010 char *root_hash_digest_to_validate;
1011
1012 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1013 if (!v) {
1014 ti->error = "Cannot allocate verity structure";
1015 return -ENOMEM;
1016 }
1017 ti->private = v;
1018 v->ti = ti;
1019
1020 r = verity_fec_ctr_alloc(v);
1021 if (r)
1022 goto bad;
1023
1024 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
1025 ti->error = "Device must be readonly";
1026 r = -EINVAL;
1027 goto bad;
1028 }
1029
1030 if (argc < 10) {
1031 ti->error = "Not enough arguments";
1032 r = -EINVAL;
1033 goto bad;
1034 }
1035
1036 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1037 num > 1) {
1038 ti->error = "Invalid version";
1039 r = -EINVAL;
1040 goto bad;
1041 }
1042 v->version = num;
1043
1044 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1045 if (r) {
1046 ti->error = "Data device lookup failed";
1047 goto bad;
1048 }
1049
1050 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1051 if (r) {
1052 ti->error = "Hash device lookup failed";
1053 goto bad;
1054 }
1055
1056 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1057 !num || (num & (num - 1)) ||
1058 num < bdev_logical_block_size(v->data_dev->bdev) ||
1059 num > PAGE_SIZE) {
1060 ti->error = "Invalid data device block size";
1061 r = -EINVAL;
1062 goto bad;
1063 }
1064 v->data_dev_block_bits = __ffs(num);
1065
1066 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1067 !num || (num & (num - 1)) ||
1068 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1069 num > INT_MAX) {
1070 ti->error = "Invalid hash device block size";
1071 r = -EINVAL;
1072 goto bad;
1073 }
1074 v->hash_dev_block_bits = __ffs(num);
1075
1076 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1077 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1078 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1079 ti->error = "Invalid data blocks";
1080 r = -EINVAL;
1081 goto bad;
1082 }
1083 v->data_blocks = num_ll;
1084
1085 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1086 ti->error = "Data device is too small";
1087 r = -EINVAL;
1088 goto bad;
1089 }
1090
1091 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1092 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1093 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1094 ti->error = "Invalid hash start";
1095 r = -EINVAL;
1096 goto bad;
1097 }
1098 v->hash_start = num_ll;
1099
1100 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1101 if (!v->alg_name) {
1102 ti->error = "Cannot allocate algorithm name";
1103 r = -ENOMEM;
1104 goto bad;
1105 }
1106
1107 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1108 if (IS_ERR(v->tfm)) {
1109 ti->error = "Cannot initialize hash function";
1110 r = PTR_ERR(v->tfm);
1111 v->tfm = NULL;
1112 goto bad;
1113 }
1114
1115 /*
1116 * dm-verity performance can vary greatly depending on which hash
1117 * algorithm implementation is used. Help people debug performance
1118 * problems by logging the ->cra_driver_name.
1119 */
1120 DMINFO("%s using implementation \"%s\"", v->alg_name,
1121 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1122
1123 v->digest_size = crypto_ahash_digestsize(v->tfm);
1124 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1125 ti->error = "Digest size too big";
1126 r = -EINVAL;
1127 goto bad;
1128 }
1129 v->ahash_reqsize = sizeof(struct ahash_request) +
1130 crypto_ahash_reqsize(v->tfm);
1131
1132 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1133 if (!v->root_digest) {
1134 ti->error = "Cannot allocate root digest";
1135 r = -ENOMEM;
1136 goto bad;
1137 }
1138 if (strlen(argv[8]) != v->digest_size * 2 ||
1139 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1140 ti->error = "Invalid root digest";
1141 r = -EINVAL;
1142 goto bad;
1143 }
1144 root_hash_digest_to_validate = argv[8];
1145
1146 if (strcmp(argv[9], "-")) {
1147 v->salt_size = strlen(argv[9]) / 2;
1148 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1149 if (!v->salt) {
1150 ti->error = "Cannot allocate salt";
1151 r = -ENOMEM;
1152 goto bad;
1153 }
1154 if (strlen(argv[9]) != v->salt_size * 2 ||
1155 hex2bin(v->salt, argv[9], v->salt_size)) {
1156 ti->error = "Invalid salt";
1157 r = -EINVAL;
1158 goto bad;
1159 }
1160 }
1161
1162 argv += 10;
1163 argc -= 10;
1164
1165 /* Optional parameters */
1166 if (argc) {
1167 as.argc = argc;
1168 as.argv = argv;
1169
1170 r = verity_parse_opt_args(&as, v, &verify_args);
1171 if (r < 0)
1172 goto bad;
1173 }
1174
1175 /* Root hash signature is a optional parameter*/
1176 r = verity_verify_root_hash(root_hash_digest_to_validate,
1177 strlen(root_hash_digest_to_validate),
1178 verify_args.sig,
1179 verify_args.sig_size);
1180 if (r < 0) {
1181 ti->error = "Root hash verification failed";
1182 goto bad;
1183 }
1184 v->hash_per_block_bits =
1185 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1186
1187 v->levels = 0;
1188 if (v->data_blocks)
1189 while (v->hash_per_block_bits * v->levels < 64 &&
1190 (unsigned long long)(v->data_blocks - 1) >>
1191 (v->hash_per_block_bits * v->levels))
1192 v->levels++;
1193
1194 if (v->levels > DM_VERITY_MAX_LEVELS) {
1195 ti->error = "Too many tree levels";
1196 r = -E2BIG;
1197 goto bad;
1198 }
1199
1200 hash_position = v->hash_start;
1201 for (i = v->levels - 1; i >= 0; i--) {
1202 sector_t s;
1203 v->hash_level_block[i] = hash_position;
1204 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1205 >> ((i + 1) * v->hash_per_block_bits);
1206 if (hash_position + s < hash_position) {
1207 ti->error = "Hash device offset overflow";
1208 r = -E2BIG;
1209 goto bad;
1210 }
1211 hash_position += s;
1212 }
1213 v->hash_blocks = hash_position;
1214
1215 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1216 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1217 dm_bufio_alloc_callback, NULL);
1218 if (IS_ERR(v->bufio)) {
1219 ti->error = "Cannot initialize dm-bufio";
1220 r = PTR_ERR(v->bufio);
1221 v->bufio = NULL;
1222 goto bad;
1223 }
1224
1225 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1226 ti->error = "Hash device is too small";
1227 r = -E2BIG;
1228 goto bad;
1229 }
1230
1231 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1232 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1233 if (!v->verify_wq) {
1234 ti->error = "Cannot allocate workqueue";
1235 r = -ENOMEM;
1236 goto bad;
1237 }
1238
1239 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1240 v->ahash_reqsize + v->digest_size * 2;
1241
1242 r = verity_fec_ctr(v);
1243 if (r)
1244 goto bad;
1245
1246 ti->per_io_data_size = roundup(ti->per_io_data_size,
1247 __alignof__(struct dm_verity_io));
1248
1249 verity_verify_sig_opts_cleanup(&verify_args);
1250
1251 return 0;
1252
1253bad:
1254
1255 verity_verify_sig_opts_cleanup(&verify_args);
1256 verity_dtr(ti);
1257
1258 return r;
1259}
1260
1261static struct target_type verity_target = {
1262 .name = "verity",
1263 .version = {1, 8, 0},
1264 .module = THIS_MODULE,
1265 .ctr = verity_ctr,
1266 .dtr = verity_dtr,
1267 .map = verity_map,
1268 .status = verity_status,
1269 .prepare_ioctl = verity_prepare_ioctl,
1270 .iterate_devices = verity_iterate_devices,
1271 .io_hints = verity_io_hints,
1272};
1273
1274static int __init dm_verity_init(void)
1275{
1276 int r;
1277
1278 r = dm_register_target(&verity_target);
1279 if (r < 0)
1280 DMERR("register failed %d", r);
1281
1282 return r;
1283}
1284
1285static void __exit dm_verity_exit(void)
1286{
1287 dm_unregister_target(&verity_target);
1288}
1289
1290module_init(dm_verity_init);
1291module_exit(dm_verity_exit);
1292
1293MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1294MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1295MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1296MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1297MODULE_LICENSE("GPL");