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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/*
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#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
36
37#define DM_VERITY_OPTS_MAX (2 + DM_VERITY_OPTS_FEC)
38
39static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
40
41module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
42
43struct dm_verity_prefetch_work {
44 struct work_struct work;
45 struct dm_verity *v;
46 sector_t block;
47 unsigned n_blocks;
48};
49
50/*
51 * Auxiliary structure appended to each dm-bufio buffer. If the value
52 * hash_verified is nonzero, hash of the block has been verified.
53 *
54 * The variable hash_verified is set to 0 when allocating the buffer, then
55 * it can be changed to 1 and it is never reset to 0 again.
56 *
57 * There is no lock around this value, a race condition can at worst cause
58 * that multiple processes verify the hash of the same buffer simultaneously
59 * and write 1 to hash_verified simultaneously.
60 * This condition is harmless, so we don't need locking.
61 */
62struct buffer_aux {
63 int hash_verified;
64};
65
66/*
67 * Initialize struct buffer_aux for a freshly created buffer.
68 */
69static void dm_bufio_alloc_callback(struct dm_buffer *buf)
70{
71 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
72
73 aux->hash_verified = 0;
74}
75
76/*
77 * Translate input sector number to the sector number on the target device.
78 */
79static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
80{
81 return v->data_start + dm_target_offset(v->ti, bi_sector);
82}
83
84/*
85 * Return hash position of a specified block at a specified tree level
86 * (0 is the lowest level).
87 * The lowest "hash_per_block_bits"-bits of the result denote hash position
88 * inside a hash block. The remaining bits denote location of the hash block.
89 */
90static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
91 int level)
92{
93 return block >> (level * v->hash_per_block_bits);
94}
95
96static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
97 const u8 *data, size_t len,
98 struct crypto_wait *wait)
99{
100 struct scatterlist sg;
101
102 sg_init_one(&sg, data, len);
103 ahash_request_set_crypt(req, &sg, NULL, len);
104
105 return crypto_wait_req(crypto_ahash_update(req), wait);
106}
107
108/*
109 * Wrapper for crypto_ahash_init, which handles verity salting.
110 */
111static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
112 struct crypto_wait *wait)
113{
114 int r;
115
116 ahash_request_set_tfm(req, v->tfm);
117 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
118 CRYPTO_TFM_REQ_MAY_BACKLOG,
119 crypto_req_done, (void *)wait);
120 crypto_init_wait(wait);
121
122 r = crypto_wait_req(crypto_ahash_init(req), wait);
123
124 if (unlikely(r < 0)) {
125 DMERR("crypto_ahash_init failed: %d", r);
126 return r;
127 }
128
129 if (likely(v->salt_size && (v->version >= 1)))
130 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
131
132 return r;
133}
134
135static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
136 u8 *digest, struct crypto_wait *wait)
137{
138 int r;
139
140 if (unlikely(v->salt_size && (!v->version))) {
141 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
142
143 if (r < 0) {
144 DMERR("verity_hash_final failed updating salt: %d", r);
145 goto out;
146 }
147 }
148
149 ahash_request_set_crypt(req, NULL, digest, 0);
150 r = crypto_wait_req(crypto_ahash_final(req), wait);
151out:
152 return r;
153}
154
155int verity_hash(struct dm_verity *v, struct ahash_request *req,
156 const u8 *data, size_t len, u8 *digest)
157{
158 int r;
159 struct crypto_wait wait;
160
161 r = verity_hash_init(v, req, &wait);
162 if (unlikely(r < 0))
163 goto out;
164
165 r = verity_hash_update(v, req, data, len, &wait);
166 if (unlikely(r < 0))
167 goto out;
168
169 r = verity_hash_final(v, req, digest, &wait);
170
171out:
172 return r;
173}
174
175static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
176 sector_t *hash_block, unsigned *offset)
177{
178 sector_t position = verity_position_at_level(v, block, level);
179 unsigned idx;
180
181 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
182
183 if (!offset)
184 return;
185
186 idx = position & ((1 << v->hash_per_block_bits) - 1);
187 if (!v->version)
188 *offset = idx * v->digest_size;
189 else
190 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
191}
192
193/*
194 * Handle verification errors.
195 */
196static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
197 unsigned long long block)
198{
199 char verity_env[DM_VERITY_ENV_LENGTH];
200 char *envp[] = { verity_env, NULL };
201 const char *type_str = "";
202 struct mapped_device *md = dm_table_get_md(v->ti->table);
203
204 /* Corruption should be visible in device status in all modes */
205 v->hash_failed = 1;
206
207 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
208 goto out;
209
210 v->corrupted_errs++;
211
212 switch (type) {
213 case DM_VERITY_BLOCK_TYPE_DATA:
214 type_str = "data";
215 break;
216 case DM_VERITY_BLOCK_TYPE_METADATA:
217 type_str = "metadata";
218 break;
219 default:
220 BUG();
221 }
222
223 DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
224 block);
225
226 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
227 DMERR("%s: reached maximum errors", v->data_dev->name);
228
229 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
230 DM_VERITY_ENV_VAR_NAME, type, block);
231
232 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
233
234out:
235 if (v->mode == DM_VERITY_MODE_LOGGING)
236 return 0;
237
238 if (v->mode == DM_VERITY_MODE_RESTART)
239 kernel_restart("dm-verity device corrupted");
240
241 return 1;
242}
243
244/*
245 * Verify hash of a metadata block pertaining to the specified data block
246 * ("block" argument) at a specified level ("level" argument).
247 *
248 * On successful return, verity_io_want_digest(v, io) contains the hash value
249 * for a lower tree level or for the data block (if we're at the lowest level).
250 *
251 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
252 * If "skip_unverified" is false, unverified buffer is hashed and verified
253 * against current value of verity_io_want_digest(v, io).
254 */
255static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
256 sector_t block, int level, bool skip_unverified,
257 u8 *want_digest)
258{
259 struct dm_buffer *buf;
260 struct buffer_aux *aux;
261 u8 *data;
262 int r;
263 sector_t hash_block;
264 unsigned offset;
265
266 verity_hash_at_level(v, block, level, &hash_block, &offset);
267
268 data = dm_bufio_read(v->bufio, hash_block, &buf);
269 if (IS_ERR(data))
270 return PTR_ERR(data);
271
272 aux = dm_bufio_get_aux_data(buf);
273
274 if (!aux->hash_verified) {
275 if (skip_unverified) {
276 r = 1;
277 goto release_ret_r;
278 }
279
280 r = verity_hash(v, verity_io_hash_req(v, io),
281 data, 1 << v->hash_dev_block_bits,
282 verity_io_real_digest(v, io));
283 if (unlikely(r < 0))
284 goto release_ret_r;
285
286 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
287 v->digest_size) == 0))
288 aux->hash_verified = 1;
289 else if (verity_fec_decode(v, io,
290 DM_VERITY_BLOCK_TYPE_METADATA,
291 hash_block, data, NULL) == 0)
292 aux->hash_verified = 1;
293 else if (verity_handle_err(v,
294 DM_VERITY_BLOCK_TYPE_METADATA,
295 hash_block)) {
296 r = -EIO;
297 goto release_ret_r;
298 }
299 }
300
301 data += offset;
302 memcpy(want_digest, data, v->digest_size);
303 r = 0;
304
305release_ret_r:
306 dm_bufio_release(buf);
307 return r;
308}
309
310/*
311 * Find a hash for a given block, write it to digest and verify the integrity
312 * of the hash tree if necessary.
313 */
314int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
315 sector_t block, u8 *digest, bool *is_zero)
316{
317 int r = 0, i;
318
319 if (likely(v->levels)) {
320 /*
321 * First, we try to get the requested hash for
322 * the current block. If the hash block itself is
323 * verified, zero is returned. If it isn't, this
324 * function returns 1 and we fall back to whole
325 * chain verification.
326 */
327 r = verity_verify_level(v, io, block, 0, true, digest);
328 if (likely(r <= 0))
329 goto out;
330 }
331
332 memcpy(digest, v->root_digest, v->digest_size);
333
334 for (i = v->levels - 1; i >= 0; i--) {
335 r = verity_verify_level(v, io, block, i, false, digest);
336 if (unlikely(r))
337 goto out;
338 }
339out:
340 if (!r && v->zero_digest)
341 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
342 else
343 *is_zero = false;
344
345 return r;
346}
347
348/*
349 * Calculates the digest for the given bio
350 */
351static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
352 struct bvec_iter *iter, struct crypto_wait *wait)
353{
354 unsigned int todo = 1 << v->data_dev_block_bits;
355 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
356 struct scatterlist sg;
357 struct ahash_request *req = verity_io_hash_req(v, io);
358
359 do {
360 int r;
361 unsigned int len;
362 struct bio_vec bv = bio_iter_iovec(bio, *iter);
363
364 sg_init_table(&sg, 1);
365
366 len = bv.bv_len;
367
368 if (likely(len >= todo))
369 len = todo;
370 /*
371 * Operating on a single page at a time looks suboptimal
372 * until you consider the typical block size is 4,096B.
373 * Going through this loops twice should be very rare.
374 */
375 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
376 ahash_request_set_crypt(req, &sg, NULL, len);
377 r = crypto_wait_req(crypto_ahash_update(req), wait);
378
379 if (unlikely(r < 0)) {
380 DMERR("verity_for_io_block crypto op failed: %d", r);
381 return r;
382 }
383
384 bio_advance_iter(bio, iter, len);
385 todo -= len;
386 } while (todo);
387
388 return 0;
389}
390
391/*
392 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
393 * starting from iter.
394 */
395int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
396 struct bvec_iter *iter,
397 int (*process)(struct dm_verity *v,
398 struct dm_verity_io *io, u8 *data,
399 size_t len))
400{
401 unsigned todo = 1 << v->data_dev_block_bits;
402 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
403
404 do {
405 int r;
406 u8 *page;
407 unsigned len;
408 struct bio_vec bv = bio_iter_iovec(bio, *iter);
409
410 page = kmap_atomic(bv.bv_page);
411 len = bv.bv_len;
412
413 if (likely(len >= todo))
414 len = todo;
415
416 r = process(v, io, page + bv.bv_offset, len);
417 kunmap_atomic(page);
418
419 if (r < 0)
420 return r;
421
422 bio_advance_iter(bio, iter, len);
423 todo -= len;
424 } while (todo);
425
426 return 0;
427}
428
429static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
430 u8 *data, size_t len)
431{
432 memset(data, 0, len);
433 return 0;
434}
435
436/*
437 * Moves the bio iter one data block forward.
438 */
439static inline void verity_bv_skip_block(struct dm_verity *v,
440 struct dm_verity_io *io,
441 struct bvec_iter *iter)
442{
443 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
444
445 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
446}
447
448/*
449 * Verify one "dm_verity_io" structure.
450 */
451static int verity_verify_io(struct dm_verity_io *io)
452{
453 bool is_zero;
454 struct dm_verity *v = io->v;
455 struct bvec_iter start;
456 unsigned b;
457 struct crypto_wait wait;
458
459 for (b = 0; b < io->n_blocks; b++) {
460 int r;
461 sector_t cur_block = io->block + b;
462 struct ahash_request *req = verity_io_hash_req(v, io);
463
464 if (v->validated_blocks &&
465 likely(test_bit(cur_block, v->validated_blocks))) {
466 verity_bv_skip_block(v, io, &io->iter);
467 continue;
468 }
469
470 r = verity_hash_for_block(v, io, cur_block,
471 verity_io_want_digest(v, io),
472 &is_zero);
473 if (unlikely(r < 0))
474 return r;
475
476 if (is_zero) {
477 /*
478 * If we expect a zero block, don't validate, just
479 * return zeros.
480 */
481 r = verity_for_bv_block(v, io, &io->iter,
482 verity_bv_zero);
483 if (unlikely(r < 0))
484 return r;
485
486 continue;
487 }
488
489 r = verity_hash_init(v, req, &wait);
490 if (unlikely(r < 0))
491 return r;
492
493 start = io->iter;
494 r = verity_for_io_block(v, io, &io->iter, &wait);
495 if (unlikely(r < 0))
496 return r;
497
498 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
499 &wait);
500 if (unlikely(r < 0))
501 return r;
502
503 if (likely(memcmp(verity_io_real_digest(v, io),
504 verity_io_want_digest(v, io), v->digest_size) == 0)) {
505 if (v->validated_blocks)
506 set_bit(cur_block, v->validated_blocks);
507 continue;
508 }
509 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
510 cur_block, NULL, &start) == 0)
511 continue;
512 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
513 cur_block))
514 return -EIO;
515 }
516
517 return 0;
518}
519
520/*
521 * End one "io" structure with a given error.
522 */
523static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
524{
525 struct dm_verity *v = io->v;
526 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
527
528 bio->bi_end_io = io->orig_bi_end_io;
529 bio->bi_status = status;
530
531 verity_fec_finish_io(io);
532
533 bio_endio(bio);
534}
535
536static void verity_work(struct work_struct *w)
537{
538 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
539
540 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
541}
542
543static void verity_end_io(struct bio *bio)
544{
545 struct dm_verity_io *io = bio->bi_private;
546
547 if (bio->bi_status && !verity_fec_is_enabled(io->v)) {
548 verity_finish_io(io, bio->bi_status);
549 return;
550 }
551
552 INIT_WORK(&io->work, verity_work);
553 queue_work(io->v->verify_wq, &io->work);
554}
555
556/*
557 * Prefetch buffers for the specified io.
558 * The root buffer is not prefetched, it is assumed that it will be cached
559 * all the time.
560 */
561static void verity_prefetch_io(struct work_struct *work)
562{
563 struct dm_verity_prefetch_work *pw =
564 container_of(work, struct dm_verity_prefetch_work, work);
565 struct dm_verity *v = pw->v;
566 int i;
567
568 for (i = v->levels - 2; i >= 0; i--) {
569 sector_t hash_block_start;
570 sector_t hash_block_end;
571 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
572 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
573 if (!i) {
574 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
575
576 cluster >>= v->data_dev_block_bits;
577 if (unlikely(!cluster))
578 goto no_prefetch_cluster;
579
580 if (unlikely(cluster & (cluster - 1)))
581 cluster = 1 << __fls(cluster);
582
583 hash_block_start &= ~(sector_t)(cluster - 1);
584 hash_block_end |= cluster - 1;
585 if (unlikely(hash_block_end >= v->hash_blocks))
586 hash_block_end = v->hash_blocks - 1;
587 }
588no_prefetch_cluster:
589 dm_bufio_prefetch(v->bufio, hash_block_start,
590 hash_block_end - hash_block_start + 1);
591 }
592
593 kfree(pw);
594}
595
596static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
597{
598 struct dm_verity_prefetch_work *pw;
599
600 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
601 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
602
603 if (!pw)
604 return;
605
606 INIT_WORK(&pw->work, verity_prefetch_io);
607 pw->v = v;
608 pw->block = io->block;
609 pw->n_blocks = io->n_blocks;
610 queue_work(v->verify_wq, &pw->work);
611}
612
613/*
614 * Bio map function. It allocates dm_verity_io structure and bio vector and
615 * fills them. Then it issues prefetches and the I/O.
616 */
617static int verity_map(struct dm_target *ti, struct bio *bio)
618{
619 struct dm_verity *v = ti->private;
620 struct dm_verity_io *io;
621
622 bio_set_dev(bio, v->data_dev->bdev);
623 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
624
625 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
626 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
627 DMERR_LIMIT("unaligned io");
628 return DM_MAPIO_KILL;
629 }
630
631 if (bio_end_sector(bio) >>
632 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
633 DMERR_LIMIT("io out of range");
634 return DM_MAPIO_KILL;
635 }
636
637 if (bio_data_dir(bio) == WRITE)
638 return DM_MAPIO_KILL;
639
640 io = dm_per_bio_data(bio, ti->per_io_data_size);
641 io->v = v;
642 io->orig_bi_end_io = bio->bi_end_io;
643 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
644 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
645
646 bio->bi_end_io = verity_end_io;
647 bio->bi_private = io;
648 io->iter = bio->bi_iter;
649
650 verity_fec_init_io(io);
651
652 verity_submit_prefetch(v, io);
653
654 generic_make_request(bio);
655
656 return DM_MAPIO_SUBMITTED;
657}
658
659/*
660 * Status: V (valid) or C (corruption found)
661 */
662static void verity_status(struct dm_target *ti, status_type_t type,
663 unsigned status_flags, char *result, unsigned maxlen)
664{
665 struct dm_verity *v = ti->private;
666 unsigned args = 0;
667 unsigned sz = 0;
668 unsigned x;
669
670 switch (type) {
671 case STATUSTYPE_INFO:
672 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
673 break;
674 case STATUSTYPE_TABLE:
675 DMEMIT("%u %s %s %u %u %llu %llu %s ",
676 v->version,
677 v->data_dev->name,
678 v->hash_dev->name,
679 1 << v->data_dev_block_bits,
680 1 << v->hash_dev_block_bits,
681 (unsigned long long)v->data_blocks,
682 (unsigned long long)v->hash_start,
683 v->alg_name
684 );
685 for (x = 0; x < v->digest_size; x++)
686 DMEMIT("%02x", v->root_digest[x]);
687 DMEMIT(" ");
688 if (!v->salt_size)
689 DMEMIT("-");
690 else
691 for (x = 0; x < v->salt_size; x++)
692 DMEMIT("%02x", v->salt[x]);
693 if (v->mode != DM_VERITY_MODE_EIO)
694 args++;
695 if (verity_fec_is_enabled(v))
696 args += DM_VERITY_OPTS_FEC;
697 if (v->zero_digest)
698 args++;
699 if (v->validated_blocks)
700 args++;
701 if (!args)
702 return;
703 DMEMIT(" %u", args);
704 if (v->mode != DM_VERITY_MODE_EIO) {
705 DMEMIT(" ");
706 switch (v->mode) {
707 case DM_VERITY_MODE_LOGGING:
708 DMEMIT(DM_VERITY_OPT_LOGGING);
709 break;
710 case DM_VERITY_MODE_RESTART:
711 DMEMIT(DM_VERITY_OPT_RESTART);
712 break;
713 default:
714 BUG();
715 }
716 }
717 if (v->zero_digest)
718 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
719 if (v->validated_blocks)
720 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
721 sz = verity_fec_status_table(v, sz, result, maxlen);
722 break;
723 }
724}
725
726static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
727{
728 struct dm_verity *v = ti->private;
729
730 *bdev = v->data_dev->bdev;
731
732 if (v->data_start ||
733 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
734 return 1;
735 return 0;
736}
737
738static int verity_iterate_devices(struct dm_target *ti,
739 iterate_devices_callout_fn fn, void *data)
740{
741 struct dm_verity *v = ti->private;
742
743 return fn(ti, v->data_dev, v->data_start, ti->len, data);
744}
745
746static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
747{
748 struct dm_verity *v = ti->private;
749
750 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
751 limits->logical_block_size = 1 << v->data_dev_block_bits;
752
753 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
754 limits->physical_block_size = 1 << v->data_dev_block_bits;
755
756 blk_limits_io_min(limits, limits->logical_block_size);
757}
758
759static void verity_dtr(struct dm_target *ti)
760{
761 struct dm_verity *v = ti->private;
762
763 if (v->verify_wq)
764 destroy_workqueue(v->verify_wq);
765
766 if (v->bufio)
767 dm_bufio_client_destroy(v->bufio);
768
769 kvfree(v->validated_blocks);
770 kfree(v->salt);
771 kfree(v->root_digest);
772 kfree(v->zero_digest);
773
774 if (v->tfm)
775 crypto_free_ahash(v->tfm);
776
777 kfree(v->alg_name);
778
779 if (v->hash_dev)
780 dm_put_device(ti, v->hash_dev);
781
782 if (v->data_dev)
783 dm_put_device(ti, v->data_dev);
784
785 verity_fec_dtr(v);
786
787 kfree(v);
788}
789
790static int verity_alloc_most_once(struct dm_verity *v)
791{
792 struct dm_target *ti = v->ti;
793
794 /* the bitset can only handle INT_MAX blocks */
795 if (v->data_blocks > INT_MAX) {
796 ti->error = "device too large to use check_at_most_once";
797 return -E2BIG;
798 }
799
800 v->validated_blocks = kvzalloc(BITS_TO_LONGS(v->data_blocks) *
801 sizeof(unsigned long), GFP_KERNEL);
802 if (!v->validated_blocks) {
803 ti->error = "failed to allocate bitset for check_at_most_once";
804 return -ENOMEM;
805 }
806
807 return 0;
808}
809
810static int verity_alloc_zero_digest(struct dm_verity *v)
811{
812 int r = -ENOMEM;
813 struct ahash_request *req;
814 u8 *zero_data;
815
816 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
817
818 if (!v->zero_digest)
819 return r;
820
821 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
822
823 if (!req)
824 return r; /* verity_dtr will free zero_digest */
825
826 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
827
828 if (!zero_data)
829 goto out;
830
831 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
832 v->zero_digest);
833
834out:
835 kfree(req);
836 kfree(zero_data);
837
838 return r;
839}
840
841static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
842{
843 int r;
844 unsigned argc;
845 struct dm_target *ti = v->ti;
846 const char *arg_name;
847
848 static const struct dm_arg _args[] = {
849 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
850 };
851
852 r = dm_read_arg_group(_args, as, &argc, &ti->error);
853 if (r)
854 return -EINVAL;
855
856 if (!argc)
857 return 0;
858
859 do {
860 arg_name = dm_shift_arg(as);
861 argc--;
862
863 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
864 v->mode = DM_VERITY_MODE_LOGGING;
865 continue;
866
867 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
868 v->mode = DM_VERITY_MODE_RESTART;
869 continue;
870
871 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
872 r = verity_alloc_zero_digest(v);
873 if (r) {
874 ti->error = "Cannot allocate zero digest";
875 return r;
876 }
877 continue;
878
879 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
880 r = verity_alloc_most_once(v);
881 if (r)
882 return r;
883 continue;
884
885 } else if (verity_is_fec_opt_arg(arg_name)) {
886 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
887 if (r)
888 return r;
889 continue;
890 }
891
892 ti->error = "Unrecognized verity feature request";
893 return -EINVAL;
894 } while (argc && !r);
895
896 return r;
897}
898
899/*
900 * Target parameters:
901 * <version> The current format is version 1.
902 * Vsn 0 is compatible with original Chromium OS releases.
903 * <data device>
904 * <hash device>
905 * <data block size>
906 * <hash block size>
907 * <the number of data blocks>
908 * <hash start block>
909 * <algorithm>
910 * <digest>
911 * <salt> Hex string or "-" if no salt.
912 */
913static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
914{
915 struct dm_verity *v;
916 struct dm_arg_set as;
917 unsigned int num;
918 unsigned long long num_ll;
919 int r;
920 int i;
921 sector_t hash_position;
922 char dummy;
923
924 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
925 if (!v) {
926 ti->error = "Cannot allocate verity structure";
927 return -ENOMEM;
928 }
929 ti->private = v;
930 v->ti = ti;
931
932 r = verity_fec_ctr_alloc(v);
933 if (r)
934 goto bad;
935
936 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
937 ti->error = "Device must be readonly";
938 r = -EINVAL;
939 goto bad;
940 }
941
942 if (argc < 10) {
943 ti->error = "Not enough arguments";
944 r = -EINVAL;
945 goto bad;
946 }
947
948 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
949 num > 1) {
950 ti->error = "Invalid version";
951 r = -EINVAL;
952 goto bad;
953 }
954 v->version = num;
955
956 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
957 if (r) {
958 ti->error = "Data device lookup failed";
959 goto bad;
960 }
961
962 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
963 if (r) {
964 ti->error = "Hash device lookup failed";
965 goto bad;
966 }
967
968 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
969 !num || (num & (num - 1)) ||
970 num < bdev_logical_block_size(v->data_dev->bdev) ||
971 num > PAGE_SIZE) {
972 ti->error = "Invalid data device block size";
973 r = -EINVAL;
974 goto bad;
975 }
976 v->data_dev_block_bits = __ffs(num);
977
978 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
979 !num || (num & (num - 1)) ||
980 num < bdev_logical_block_size(v->hash_dev->bdev) ||
981 num > INT_MAX) {
982 ti->error = "Invalid hash device block size";
983 r = -EINVAL;
984 goto bad;
985 }
986 v->hash_dev_block_bits = __ffs(num);
987
988 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
989 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
990 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
991 ti->error = "Invalid data blocks";
992 r = -EINVAL;
993 goto bad;
994 }
995 v->data_blocks = num_ll;
996
997 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
998 ti->error = "Data device is too small";
999 r = -EINVAL;
1000 goto bad;
1001 }
1002
1003 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1004 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1005 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1006 ti->error = "Invalid hash start";
1007 r = -EINVAL;
1008 goto bad;
1009 }
1010 v->hash_start = num_ll;
1011
1012 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1013 if (!v->alg_name) {
1014 ti->error = "Cannot allocate algorithm name";
1015 r = -ENOMEM;
1016 goto bad;
1017 }
1018
1019 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1020 if (IS_ERR(v->tfm)) {
1021 ti->error = "Cannot initialize hash function";
1022 r = PTR_ERR(v->tfm);
1023 v->tfm = NULL;
1024 goto bad;
1025 }
1026 v->digest_size = crypto_ahash_digestsize(v->tfm);
1027 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1028 ti->error = "Digest size too big";
1029 r = -EINVAL;
1030 goto bad;
1031 }
1032 v->ahash_reqsize = sizeof(struct ahash_request) +
1033 crypto_ahash_reqsize(v->tfm);
1034
1035 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1036 if (!v->root_digest) {
1037 ti->error = "Cannot allocate root digest";
1038 r = -ENOMEM;
1039 goto bad;
1040 }
1041 if (strlen(argv[8]) != v->digest_size * 2 ||
1042 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1043 ti->error = "Invalid root digest";
1044 r = -EINVAL;
1045 goto bad;
1046 }
1047
1048 if (strcmp(argv[9], "-")) {
1049 v->salt_size = strlen(argv[9]) / 2;
1050 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1051 if (!v->salt) {
1052 ti->error = "Cannot allocate salt";
1053 r = -ENOMEM;
1054 goto bad;
1055 }
1056 if (strlen(argv[9]) != v->salt_size * 2 ||
1057 hex2bin(v->salt, argv[9], v->salt_size)) {
1058 ti->error = "Invalid salt";
1059 r = -EINVAL;
1060 goto bad;
1061 }
1062 }
1063
1064 argv += 10;
1065 argc -= 10;
1066
1067 /* Optional parameters */
1068 if (argc) {
1069 as.argc = argc;
1070 as.argv = argv;
1071
1072 r = verity_parse_opt_args(&as, v);
1073 if (r < 0)
1074 goto bad;
1075 }
1076
1077 v->hash_per_block_bits =
1078 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1079
1080 v->levels = 0;
1081 if (v->data_blocks)
1082 while (v->hash_per_block_bits * v->levels < 64 &&
1083 (unsigned long long)(v->data_blocks - 1) >>
1084 (v->hash_per_block_bits * v->levels))
1085 v->levels++;
1086
1087 if (v->levels > DM_VERITY_MAX_LEVELS) {
1088 ti->error = "Too many tree levels";
1089 r = -E2BIG;
1090 goto bad;
1091 }
1092
1093 hash_position = v->hash_start;
1094 for (i = v->levels - 1; i >= 0; i--) {
1095 sector_t s;
1096 v->hash_level_block[i] = hash_position;
1097 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1098 >> ((i + 1) * v->hash_per_block_bits);
1099 if (hash_position + s < hash_position) {
1100 ti->error = "Hash device offset overflow";
1101 r = -E2BIG;
1102 goto bad;
1103 }
1104 hash_position += s;
1105 }
1106 v->hash_blocks = hash_position;
1107
1108 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1109 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1110 dm_bufio_alloc_callback, NULL);
1111 if (IS_ERR(v->bufio)) {
1112 ti->error = "Cannot initialize dm-bufio";
1113 r = PTR_ERR(v->bufio);
1114 v->bufio = NULL;
1115 goto bad;
1116 }
1117
1118 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1119 ti->error = "Hash device is too small";
1120 r = -E2BIG;
1121 goto bad;
1122 }
1123
1124 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1125 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1126 if (!v->verify_wq) {
1127 ti->error = "Cannot allocate workqueue";
1128 r = -ENOMEM;
1129 goto bad;
1130 }
1131
1132 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1133 v->ahash_reqsize + v->digest_size * 2;
1134
1135 r = verity_fec_ctr(v);
1136 if (r)
1137 goto bad;
1138
1139 ti->per_io_data_size = roundup(ti->per_io_data_size,
1140 __alignof__(struct dm_verity_io));
1141
1142 return 0;
1143
1144bad:
1145 verity_dtr(ti);
1146
1147 return r;
1148}
1149
1150static struct target_type verity_target = {
1151 .name = "verity",
1152 .version = {1, 4, 0},
1153 .module = THIS_MODULE,
1154 .ctr = verity_ctr,
1155 .dtr = verity_dtr,
1156 .map = verity_map,
1157 .status = verity_status,
1158 .prepare_ioctl = verity_prepare_ioctl,
1159 .iterate_devices = verity_iterate_devices,
1160 .io_hints = verity_io_hints,
1161};
1162
1163static int __init dm_verity_init(void)
1164{
1165 int r;
1166
1167 r = dm_register_target(&verity_target);
1168 if (r < 0)
1169 DMERR("register failed %d", r);
1170
1171 return r;
1172}
1173
1174static void __exit dm_verity_exit(void)
1175{
1176 dm_unregister_target(&verity_target);
1177}
1178
1179module_init(dm_verity_init);
1180module_exit(dm_verity_exit);
1181
1182MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1183MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1184MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1185MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1186MODULE_LICENSE("GPL");