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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 <linux/module.h>
20#include <linux/reboot.h>
21#include <linux/scatterlist.h>
22#include <linux/string.h>
23#include <linux/jump_label.h>
24
25#define DM_MSG_PREFIX "verity"
26
27#define DM_VERITY_ENV_LENGTH 42
28#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
29
30#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
31
32#define DM_VERITY_MAX_CORRUPTED_ERRS 100
33
34#define DM_VERITY_OPT_LOGGING "ignore_corruption"
35#define DM_VERITY_OPT_RESTART "restart_on_corruption"
36#define DM_VERITY_OPT_PANIC "panic_on_corruption"
37#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
38#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
39#define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
40
41#define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \
42 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
43
44static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
45
46module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
47
48static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
49
50struct dm_verity_prefetch_work {
51 struct work_struct work;
52 struct dm_verity *v;
53 sector_t block;
54 unsigned n_blocks;
55};
56
57/*
58 * Auxiliary structure appended to each dm-bufio buffer. If the value
59 * hash_verified is nonzero, hash of the block has been verified.
60 *
61 * The variable hash_verified is set to 0 when allocating the buffer, then
62 * it can be changed to 1 and it is never reset to 0 again.
63 *
64 * There is no lock around this value, a race condition can at worst cause
65 * that multiple processes verify the hash of the same buffer simultaneously
66 * and write 1 to hash_verified simultaneously.
67 * This condition is harmless, so we don't need locking.
68 */
69struct buffer_aux {
70 int hash_verified;
71};
72
73/*
74 * Initialize struct buffer_aux for a freshly created buffer.
75 */
76static void dm_bufio_alloc_callback(struct dm_buffer *buf)
77{
78 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
79
80 aux->hash_verified = 0;
81}
82
83/*
84 * Translate input sector number to the sector number on the target device.
85 */
86static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
87{
88 return v->data_start + dm_target_offset(v->ti, bi_sector);
89}
90
91/*
92 * Return hash position of a specified block at a specified tree level
93 * (0 is the lowest level).
94 * The lowest "hash_per_block_bits"-bits of the result denote hash position
95 * inside a hash block. The remaining bits denote location of the hash block.
96 */
97static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
98 int level)
99{
100 return block >> (level * v->hash_per_block_bits);
101}
102
103static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
104 const u8 *data, size_t len,
105 struct crypto_wait *wait)
106{
107 struct scatterlist sg;
108
109 if (likely(!is_vmalloc_addr(data))) {
110 sg_init_one(&sg, data, len);
111 ahash_request_set_crypt(req, &sg, NULL, len);
112 return crypto_wait_req(crypto_ahash_update(req), wait);
113 } else {
114 do {
115 int r;
116 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
117 flush_kernel_vmap_range((void *)data, this_step);
118 sg_init_table(&sg, 1);
119 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
120 ahash_request_set_crypt(req, &sg, NULL, this_step);
121 r = crypto_wait_req(crypto_ahash_update(req), wait);
122 if (unlikely(r))
123 return r;
124 data += this_step;
125 len -= this_step;
126 } while (len);
127 return 0;
128 }
129}
130
131/*
132 * Wrapper for crypto_ahash_init, which handles verity salting.
133 */
134static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
135 struct crypto_wait *wait)
136{
137 int r;
138
139 ahash_request_set_tfm(req, v->tfm);
140 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
141 CRYPTO_TFM_REQ_MAY_BACKLOG,
142 crypto_req_done, (void *)wait);
143 crypto_init_wait(wait);
144
145 r = crypto_wait_req(crypto_ahash_init(req), wait);
146
147 if (unlikely(r < 0)) {
148 DMERR("crypto_ahash_init failed: %d", r);
149 return r;
150 }
151
152 if (likely(v->salt_size && (v->version >= 1)))
153 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
154
155 return r;
156}
157
158static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
159 u8 *digest, struct crypto_wait *wait)
160{
161 int r;
162
163 if (unlikely(v->salt_size && (!v->version))) {
164 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
165
166 if (r < 0) {
167 DMERR("verity_hash_final failed updating salt: %d", r);
168 goto out;
169 }
170 }
171
172 ahash_request_set_crypt(req, NULL, digest, 0);
173 r = crypto_wait_req(crypto_ahash_final(req), wait);
174out:
175 return r;
176}
177
178int verity_hash(struct dm_verity *v, struct ahash_request *req,
179 const u8 *data, size_t len, u8 *digest)
180{
181 int r;
182 struct crypto_wait wait;
183
184 r = verity_hash_init(v, req, &wait);
185 if (unlikely(r < 0))
186 goto out;
187
188 r = verity_hash_update(v, req, data, len, &wait);
189 if (unlikely(r < 0))
190 goto out;
191
192 r = verity_hash_final(v, req, digest, &wait);
193
194out:
195 return r;
196}
197
198static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
199 sector_t *hash_block, unsigned *offset)
200{
201 sector_t position = verity_position_at_level(v, block, level);
202 unsigned idx;
203
204 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
205
206 if (!offset)
207 return;
208
209 idx = position & ((1 << v->hash_per_block_bits) - 1);
210 if (!v->version)
211 *offset = idx * v->digest_size;
212 else
213 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
214}
215
216/*
217 * Handle verification errors.
218 */
219static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
220 unsigned long long block)
221{
222 char verity_env[DM_VERITY_ENV_LENGTH];
223 char *envp[] = { verity_env, NULL };
224 const char *type_str = "";
225 struct mapped_device *md = dm_table_get_md(v->ti->table);
226
227 /* Corruption should be visible in device status in all modes */
228 v->hash_failed = true;
229
230 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
231 goto out;
232
233 v->corrupted_errs++;
234
235 switch (type) {
236 case DM_VERITY_BLOCK_TYPE_DATA:
237 type_str = "data";
238 break;
239 case DM_VERITY_BLOCK_TYPE_METADATA:
240 type_str = "metadata";
241 break;
242 default:
243 BUG();
244 }
245
246 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
247 type_str, block);
248
249 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
250 DMERR("%s: reached maximum errors", v->data_dev->name);
251
252 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
253 DM_VERITY_ENV_VAR_NAME, type, block);
254
255 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
256
257out:
258 if (v->mode == DM_VERITY_MODE_LOGGING)
259 return 0;
260
261 if (v->mode == DM_VERITY_MODE_RESTART)
262 kernel_restart("dm-verity device corrupted");
263
264 if (v->mode == DM_VERITY_MODE_PANIC)
265 panic("dm-verity device corrupted");
266
267 return 1;
268}
269
270/*
271 * Verify hash of a metadata block pertaining to the specified data block
272 * ("block" argument) at a specified level ("level" argument).
273 *
274 * On successful return, verity_io_want_digest(v, io) contains the hash value
275 * for a lower tree level or for the data block (if we're at the lowest level).
276 *
277 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
278 * If "skip_unverified" is false, unverified buffer is hashed and verified
279 * against current value of verity_io_want_digest(v, io).
280 */
281static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
282 sector_t block, int level, bool skip_unverified,
283 u8 *want_digest)
284{
285 struct dm_buffer *buf;
286 struct buffer_aux *aux;
287 u8 *data;
288 int r;
289 sector_t hash_block;
290 unsigned offset;
291
292 verity_hash_at_level(v, block, level, &hash_block, &offset);
293
294 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
295 data = dm_bufio_get(v->bufio, hash_block, &buf);
296 if (data == NULL) {
297 /*
298 * In tasklet and the hash was not in the bufio cache.
299 * Return early and resume execution from a work-queue
300 * to read the hash from disk.
301 */
302 return -EAGAIN;
303 }
304 } else
305 data = dm_bufio_read(v->bufio, hash_block, &buf);
306
307 if (IS_ERR(data))
308 return PTR_ERR(data);
309
310 aux = dm_bufio_get_aux_data(buf);
311
312 if (!aux->hash_verified) {
313 if (skip_unverified) {
314 r = 1;
315 goto release_ret_r;
316 }
317
318 r = verity_hash(v, verity_io_hash_req(v, io),
319 data, 1 << v->hash_dev_block_bits,
320 verity_io_real_digest(v, io));
321 if (unlikely(r < 0))
322 goto release_ret_r;
323
324 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
325 v->digest_size) == 0))
326 aux->hash_verified = 1;
327 else if (static_branch_unlikely(&use_tasklet_enabled) &&
328 io->in_tasklet) {
329 /*
330 * Error handling code (FEC included) cannot be run in a
331 * tasklet since it may sleep, so fallback to work-queue.
332 */
333 r = -EAGAIN;
334 goto release_ret_r;
335 }
336 else if (verity_fec_decode(v, io,
337 DM_VERITY_BLOCK_TYPE_METADATA,
338 hash_block, data, NULL) == 0)
339 aux->hash_verified = 1;
340 else if (verity_handle_err(v,
341 DM_VERITY_BLOCK_TYPE_METADATA,
342 hash_block)) {
343 r = -EIO;
344 goto release_ret_r;
345 }
346 }
347
348 data += offset;
349 memcpy(want_digest, data, v->digest_size);
350 r = 0;
351
352release_ret_r:
353 dm_bufio_release(buf);
354 return r;
355}
356
357/*
358 * Find a hash for a given block, write it to digest and verify the integrity
359 * of the hash tree if necessary.
360 */
361int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
362 sector_t block, u8 *digest, bool *is_zero)
363{
364 int r = 0, i;
365
366 if (likely(v->levels)) {
367 /*
368 * First, we try to get the requested hash for
369 * the current block. If the hash block itself is
370 * verified, zero is returned. If it isn't, this
371 * function returns 1 and we fall back to whole
372 * chain verification.
373 */
374 r = verity_verify_level(v, io, block, 0, true, digest);
375 if (likely(r <= 0))
376 goto out;
377 }
378
379 memcpy(digest, v->root_digest, v->digest_size);
380
381 for (i = v->levels - 1; i >= 0; i--) {
382 r = verity_verify_level(v, io, block, i, false, digest);
383 if (unlikely(r))
384 goto out;
385 }
386out:
387 if (!r && v->zero_digest)
388 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
389 else
390 *is_zero = false;
391
392 return r;
393}
394
395/*
396 * Calculates the digest for the given bio
397 */
398static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
399 struct bvec_iter *iter, struct crypto_wait *wait)
400{
401 unsigned int todo = 1 << v->data_dev_block_bits;
402 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
403 struct scatterlist sg;
404 struct ahash_request *req = verity_io_hash_req(v, io);
405
406 do {
407 int r;
408 unsigned int len;
409 struct bio_vec bv = bio_iter_iovec(bio, *iter);
410
411 sg_init_table(&sg, 1);
412
413 len = bv.bv_len;
414
415 if (likely(len >= todo))
416 len = todo;
417 /*
418 * Operating on a single page at a time looks suboptimal
419 * until you consider the typical block size is 4,096B.
420 * Going through this loops twice should be very rare.
421 */
422 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
423 ahash_request_set_crypt(req, &sg, NULL, len);
424 r = crypto_wait_req(crypto_ahash_update(req), wait);
425
426 if (unlikely(r < 0)) {
427 DMERR("verity_for_io_block crypto op failed: %d", r);
428 return r;
429 }
430
431 bio_advance_iter(bio, iter, len);
432 todo -= len;
433 } while (todo);
434
435 return 0;
436}
437
438/*
439 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
440 * starting from iter.
441 */
442int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
443 struct bvec_iter *iter,
444 int (*process)(struct dm_verity *v,
445 struct dm_verity_io *io, u8 *data,
446 size_t len))
447{
448 unsigned todo = 1 << v->data_dev_block_bits;
449 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
450
451 do {
452 int r;
453 u8 *page;
454 unsigned len;
455 struct bio_vec bv = bio_iter_iovec(bio, *iter);
456
457 page = bvec_kmap_local(&bv);
458 len = bv.bv_len;
459
460 if (likely(len >= todo))
461 len = todo;
462
463 r = process(v, io, page, len);
464 kunmap_local(page);
465
466 if (r < 0)
467 return r;
468
469 bio_advance_iter(bio, iter, len);
470 todo -= len;
471 } while (todo);
472
473 return 0;
474}
475
476static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
477 u8 *data, size_t len)
478{
479 memset(data, 0, len);
480 return 0;
481}
482
483/*
484 * Moves the bio iter one data block forward.
485 */
486static inline void verity_bv_skip_block(struct dm_verity *v,
487 struct dm_verity_io *io,
488 struct bvec_iter *iter)
489{
490 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
491
492 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
493}
494
495/*
496 * Verify one "dm_verity_io" structure.
497 */
498static int verity_verify_io(struct dm_verity_io *io)
499{
500 bool is_zero;
501 struct dm_verity *v = io->v;
502#if defined(CONFIG_DM_VERITY_FEC)
503 struct bvec_iter start;
504#endif
505 struct bvec_iter iter_copy;
506 struct bvec_iter *iter;
507 struct crypto_wait wait;
508 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
509 unsigned int b;
510
511 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
512 /*
513 * Copy the iterator in case we need to restart
514 * verification in a work-queue.
515 */
516 iter_copy = io->iter;
517 iter = &iter_copy;
518 } else
519 iter = &io->iter;
520
521 for (b = 0; b < io->n_blocks; b++) {
522 int r;
523 sector_t cur_block = io->block + b;
524 struct ahash_request *req = verity_io_hash_req(v, io);
525
526 if (v->validated_blocks &&
527 likely(test_bit(cur_block, v->validated_blocks))) {
528 verity_bv_skip_block(v, io, iter);
529 continue;
530 }
531
532 r = verity_hash_for_block(v, io, cur_block,
533 verity_io_want_digest(v, io),
534 &is_zero);
535 if (unlikely(r < 0))
536 return r;
537
538 if (is_zero) {
539 /*
540 * If we expect a zero block, don't validate, just
541 * return zeros.
542 */
543 r = verity_for_bv_block(v, io, iter,
544 verity_bv_zero);
545 if (unlikely(r < 0))
546 return r;
547
548 continue;
549 }
550
551 r = verity_hash_init(v, req, &wait);
552 if (unlikely(r < 0))
553 return r;
554
555#if defined(CONFIG_DM_VERITY_FEC)
556 if (verity_fec_is_enabled(v))
557 start = *iter;
558#endif
559 r = verity_for_io_block(v, io, iter, &wait);
560 if (unlikely(r < 0))
561 return r;
562
563 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
564 &wait);
565 if (unlikely(r < 0))
566 return r;
567
568 if (likely(memcmp(verity_io_real_digest(v, io),
569 verity_io_want_digest(v, io), v->digest_size) == 0)) {
570 if (v->validated_blocks)
571 set_bit(cur_block, v->validated_blocks);
572 continue;
573 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
574 io->in_tasklet) {
575 /*
576 * Error handling code (FEC included) cannot be run in a
577 * tasklet since it may sleep, so fallback to work-queue.
578 */
579 return -EAGAIN;
580#if defined(CONFIG_DM_VERITY_FEC)
581 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
582 cur_block, NULL, &start) == 0) {
583 continue;
584#endif
585 } else {
586 if (bio->bi_status) {
587 /*
588 * Error correction failed; Just return error
589 */
590 return -EIO;
591 }
592 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
593 cur_block))
594 return -EIO;
595 }
596 }
597
598 return 0;
599}
600
601/*
602 * Skip verity work in response to I/O error when system is shutting down.
603 */
604static inline bool verity_is_system_shutting_down(void)
605{
606 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
607 || system_state == SYSTEM_RESTART;
608}
609
610/*
611 * End one "io" structure with a given error.
612 */
613static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
614{
615 struct dm_verity *v = io->v;
616 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
617
618 bio->bi_end_io = io->orig_bi_end_io;
619 bio->bi_status = status;
620
621 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
622 verity_fec_finish_io(io);
623
624 bio_endio(bio);
625}
626
627static void verity_work(struct work_struct *w)
628{
629 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
630
631 io->in_tasklet = false;
632
633 verity_fec_init_io(io);
634 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
635}
636
637static void verity_tasklet(unsigned long data)
638{
639 struct dm_verity_io *io = (struct dm_verity_io *)data;
640 int err;
641
642 io->in_tasklet = true;
643 err = verity_verify_io(io);
644 if (err == -EAGAIN) {
645 /* fallback to retrying with work-queue */
646 INIT_WORK(&io->work, verity_work);
647 queue_work(io->v->verify_wq, &io->work);
648 return;
649 }
650
651 verity_finish_io(io, errno_to_blk_status(err));
652}
653
654static void verity_end_io(struct bio *bio)
655{
656 struct dm_verity_io *io = bio->bi_private;
657
658 if (bio->bi_status &&
659 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
660 verity_finish_io(io, bio->bi_status);
661 return;
662 }
663
664 if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
665 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
666 tasklet_schedule(&io->tasklet);
667 } else {
668 INIT_WORK(&io->work, verity_work);
669 queue_work(io->v->verify_wq, &io->work);
670 }
671}
672
673/*
674 * Prefetch buffers for the specified io.
675 * The root buffer is not prefetched, it is assumed that it will be cached
676 * all the time.
677 */
678static void verity_prefetch_io(struct work_struct *work)
679{
680 struct dm_verity_prefetch_work *pw =
681 container_of(work, struct dm_verity_prefetch_work, work);
682 struct dm_verity *v = pw->v;
683 int i;
684
685 for (i = v->levels - 2; i >= 0; i--) {
686 sector_t hash_block_start;
687 sector_t hash_block_end;
688 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
689 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
690 if (!i) {
691 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
692
693 cluster >>= v->data_dev_block_bits;
694 if (unlikely(!cluster))
695 goto no_prefetch_cluster;
696
697 if (unlikely(cluster & (cluster - 1)))
698 cluster = 1 << __fls(cluster);
699
700 hash_block_start &= ~(sector_t)(cluster - 1);
701 hash_block_end |= cluster - 1;
702 if (unlikely(hash_block_end >= v->hash_blocks))
703 hash_block_end = v->hash_blocks - 1;
704 }
705no_prefetch_cluster:
706 dm_bufio_prefetch(v->bufio, hash_block_start,
707 hash_block_end - hash_block_start + 1);
708 }
709
710 kfree(pw);
711}
712
713static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
714{
715 sector_t block = io->block;
716 unsigned int n_blocks = io->n_blocks;
717 struct dm_verity_prefetch_work *pw;
718
719 if (v->validated_blocks) {
720 while (n_blocks && test_bit(block, v->validated_blocks)) {
721 block++;
722 n_blocks--;
723 }
724 while (n_blocks && test_bit(block + n_blocks - 1,
725 v->validated_blocks))
726 n_blocks--;
727 if (!n_blocks)
728 return;
729 }
730
731 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
732 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
733
734 if (!pw)
735 return;
736
737 INIT_WORK(&pw->work, verity_prefetch_io);
738 pw->v = v;
739 pw->block = block;
740 pw->n_blocks = n_blocks;
741 queue_work(v->verify_wq, &pw->work);
742}
743
744/*
745 * Bio map function. It allocates dm_verity_io structure and bio vector and
746 * fills them. Then it issues prefetches and the I/O.
747 */
748static int verity_map(struct dm_target *ti, struct bio *bio)
749{
750 struct dm_verity *v = ti->private;
751 struct dm_verity_io *io;
752
753 bio_set_dev(bio, v->data_dev->bdev);
754 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
755
756 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
757 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
758 DMERR_LIMIT("unaligned io");
759 return DM_MAPIO_KILL;
760 }
761
762 if (bio_end_sector(bio) >>
763 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
764 DMERR_LIMIT("io out of range");
765 return DM_MAPIO_KILL;
766 }
767
768 if (bio_data_dir(bio) == WRITE)
769 return DM_MAPIO_KILL;
770
771 io = dm_per_bio_data(bio, ti->per_io_data_size);
772 io->v = v;
773 io->orig_bi_end_io = bio->bi_end_io;
774 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
775 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
776
777 bio->bi_end_io = verity_end_io;
778 bio->bi_private = io;
779 io->iter = bio->bi_iter;
780
781 verity_submit_prefetch(v, io);
782
783 submit_bio_noacct(bio);
784
785 return DM_MAPIO_SUBMITTED;
786}
787
788/*
789 * Status: V (valid) or C (corruption found)
790 */
791static void verity_status(struct dm_target *ti, status_type_t type,
792 unsigned status_flags, char *result, unsigned maxlen)
793{
794 struct dm_verity *v = ti->private;
795 unsigned args = 0;
796 unsigned sz = 0;
797 unsigned x;
798
799 switch (type) {
800 case STATUSTYPE_INFO:
801 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
802 break;
803 case STATUSTYPE_TABLE:
804 DMEMIT("%u %s %s %u %u %llu %llu %s ",
805 v->version,
806 v->data_dev->name,
807 v->hash_dev->name,
808 1 << v->data_dev_block_bits,
809 1 << v->hash_dev_block_bits,
810 (unsigned long long)v->data_blocks,
811 (unsigned long long)v->hash_start,
812 v->alg_name
813 );
814 for (x = 0; x < v->digest_size; x++)
815 DMEMIT("%02x", v->root_digest[x]);
816 DMEMIT(" ");
817 if (!v->salt_size)
818 DMEMIT("-");
819 else
820 for (x = 0; x < v->salt_size; x++)
821 DMEMIT("%02x", v->salt[x]);
822 if (v->mode != DM_VERITY_MODE_EIO)
823 args++;
824 if (verity_fec_is_enabled(v))
825 args += DM_VERITY_OPTS_FEC;
826 if (v->zero_digest)
827 args++;
828 if (v->validated_blocks)
829 args++;
830 if (v->use_tasklet)
831 args++;
832 if (v->signature_key_desc)
833 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
834 if (!args)
835 return;
836 DMEMIT(" %u", args);
837 if (v->mode != DM_VERITY_MODE_EIO) {
838 DMEMIT(" ");
839 switch (v->mode) {
840 case DM_VERITY_MODE_LOGGING:
841 DMEMIT(DM_VERITY_OPT_LOGGING);
842 break;
843 case DM_VERITY_MODE_RESTART:
844 DMEMIT(DM_VERITY_OPT_RESTART);
845 break;
846 case DM_VERITY_MODE_PANIC:
847 DMEMIT(DM_VERITY_OPT_PANIC);
848 break;
849 default:
850 BUG();
851 }
852 }
853 if (v->zero_digest)
854 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
855 if (v->validated_blocks)
856 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
857 if (v->use_tasklet)
858 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
859 sz = verity_fec_status_table(v, sz, result, maxlen);
860 if (v->signature_key_desc)
861 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
862 " %s", v->signature_key_desc);
863 break;
864
865 case STATUSTYPE_IMA:
866 DMEMIT_TARGET_NAME_VERSION(ti->type);
867 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
868 DMEMIT(",verity_version=%u", v->version);
869 DMEMIT(",data_device_name=%s", v->data_dev->name);
870 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
871 DMEMIT(",verity_algorithm=%s", v->alg_name);
872
873 DMEMIT(",root_digest=");
874 for (x = 0; x < v->digest_size; x++)
875 DMEMIT("%02x", v->root_digest[x]);
876
877 DMEMIT(",salt=");
878 if (!v->salt_size)
879 DMEMIT("-");
880 else
881 for (x = 0; x < v->salt_size; x++)
882 DMEMIT("%02x", v->salt[x]);
883
884 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
885 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
886 if (v->signature_key_desc)
887 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
888
889 if (v->mode != DM_VERITY_MODE_EIO) {
890 DMEMIT(",verity_mode=");
891 switch (v->mode) {
892 case DM_VERITY_MODE_LOGGING:
893 DMEMIT(DM_VERITY_OPT_LOGGING);
894 break;
895 case DM_VERITY_MODE_RESTART:
896 DMEMIT(DM_VERITY_OPT_RESTART);
897 break;
898 case DM_VERITY_MODE_PANIC:
899 DMEMIT(DM_VERITY_OPT_PANIC);
900 break;
901 default:
902 DMEMIT("invalid");
903 }
904 }
905 DMEMIT(";");
906 break;
907 }
908}
909
910static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
911{
912 struct dm_verity *v = ti->private;
913
914 *bdev = v->data_dev->bdev;
915
916 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
917 return 1;
918 return 0;
919}
920
921static int verity_iterate_devices(struct dm_target *ti,
922 iterate_devices_callout_fn fn, void *data)
923{
924 struct dm_verity *v = ti->private;
925
926 return fn(ti, v->data_dev, v->data_start, ti->len, data);
927}
928
929static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
930{
931 struct dm_verity *v = ti->private;
932
933 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
934 limits->logical_block_size = 1 << v->data_dev_block_bits;
935
936 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
937 limits->physical_block_size = 1 << v->data_dev_block_bits;
938
939 blk_limits_io_min(limits, limits->logical_block_size);
940}
941
942static void verity_dtr(struct dm_target *ti)
943{
944 struct dm_verity *v = ti->private;
945
946 if (v->verify_wq)
947 destroy_workqueue(v->verify_wq);
948
949 if (v->bufio)
950 dm_bufio_client_destroy(v->bufio);
951
952 kvfree(v->validated_blocks);
953 kfree(v->salt);
954 kfree(v->root_digest);
955 kfree(v->zero_digest);
956
957 if (v->tfm)
958 crypto_free_ahash(v->tfm);
959
960 kfree(v->alg_name);
961
962 if (v->hash_dev)
963 dm_put_device(ti, v->hash_dev);
964
965 if (v->data_dev)
966 dm_put_device(ti, v->data_dev);
967
968 verity_fec_dtr(v);
969
970 kfree(v->signature_key_desc);
971
972 if (v->use_tasklet)
973 static_branch_dec(&use_tasklet_enabled);
974
975 kfree(v);
976}
977
978static int verity_alloc_most_once(struct dm_verity *v)
979{
980 struct dm_target *ti = v->ti;
981
982 /* the bitset can only handle INT_MAX blocks */
983 if (v->data_blocks > INT_MAX) {
984 ti->error = "device too large to use check_at_most_once";
985 return -E2BIG;
986 }
987
988 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
989 sizeof(unsigned long),
990 GFP_KERNEL);
991 if (!v->validated_blocks) {
992 ti->error = "failed to allocate bitset for check_at_most_once";
993 return -ENOMEM;
994 }
995
996 return 0;
997}
998
999static int verity_alloc_zero_digest(struct dm_verity *v)
1000{
1001 int r = -ENOMEM;
1002 struct ahash_request *req;
1003 u8 *zero_data;
1004
1005 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1006
1007 if (!v->zero_digest)
1008 return r;
1009
1010 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1011
1012 if (!req)
1013 return r; /* verity_dtr will free zero_digest */
1014
1015 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1016
1017 if (!zero_data)
1018 goto out;
1019
1020 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1021 v->zero_digest);
1022
1023out:
1024 kfree(req);
1025 kfree(zero_data);
1026
1027 return r;
1028}
1029
1030static inline bool verity_is_verity_mode(const char *arg_name)
1031{
1032 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1033 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1034 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1035}
1036
1037static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1038{
1039 if (v->mode)
1040 return -EINVAL;
1041
1042 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1043 v->mode = DM_VERITY_MODE_LOGGING;
1044 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1045 v->mode = DM_VERITY_MODE_RESTART;
1046 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1047 v->mode = DM_VERITY_MODE_PANIC;
1048
1049 return 0;
1050}
1051
1052static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1053 struct dm_verity_sig_opts *verify_args,
1054 bool only_modifier_opts)
1055{
1056 int r = 0;
1057 unsigned argc;
1058 struct dm_target *ti = v->ti;
1059 const char *arg_name;
1060
1061 static const struct dm_arg _args[] = {
1062 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1063 };
1064
1065 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1066 if (r)
1067 return -EINVAL;
1068
1069 if (!argc)
1070 return 0;
1071
1072 do {
1073 arg_name = dm_shift_arg(as);
1074 argc--;
1075
1076 if (verity_is_verity_mode(arg_name)) {
1077 if (only_modifier_opts)
1078 continue;
1079 r = verity_parse_verity_mode(v, arg_name);
1080 if (r) {
1081 ti->error = "Conflicting error handling parameters";
1082 return r;
1083 }
1084 continue;
1085
1086 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1087 if (only_modifier_opts)
1088 continue;
1089 r = verity_alloc_zero_digest(v);
1090 if (r) {
1091 ti->error = "Cannot allocate zero digest";
1092 return r;
1093 }
1094 continue;
1095
1096 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1097 if (only_modifier_opts)
1098 continue;
1099 r = verity_alloc_most_once(v);
1100 if (r)
1101 return r;
1102 continue;
1103
1104 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1105 v->use_tasklet = true;
1106 static_branch_inc(&use_tasklet_enabled);
1107 continue;
1108
1109 } else if (verity_is_fec_opt_arg(arg_name)) {
1110 if (only_modifier_opts)
1111 continue;
1112 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1113 if (r)
1114 return r;
1115 continue;
1116
1117 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1118 if (only_modifier_opts)
1119 continue;
1120 r = verity_verify_sig_parse_opt_args(as, v,
1121 verify_args,
1122 &argc, arg_name);
1123 if (r)
1124 return r;
1125 continue;
1126
1127 } else if (only_modifier_opts) {
1128 /*
1129 * Ignore unrecognized opt, could easily be an extra
1130 * argument to an option whose parsing was skipped.
1131 * Normal parsing (@only_modifier_opts=false) will
1132 * properly parse all options (and their extra args).
1133 */
1134 continue;
1135 }
1136
1137 DMERR("Unrecognized verity feature request: %s", arg_name);
1138 ti->error = "Unrecognized verity feature request";
1139 return -EINVAL;
1140 } while (argc && !r);
1141
1142 return r;
1143}
1144
1145/*
1146 * Target parameters:
1147 * <version> The current format is version 1.
1148 * Vsn 0 is compatible with original Chromium OS releases.
1149 * <data device>
1150 * <hash device>
1151 * <data block size>
1152 * <hash block size>
1153 * <the number of data blocks>
1154 * <hash start block>
1155 * <algorithm>
1156 * <digest>
1157 * <salt> Hex string or "-" if no salt.
1158 */
1159static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
1160{
1161 struct dm_verity *v;
1162 struct dm_verity_sig_opts verify_args = {0};
1163 struct dm_arg_set as;
1164 unsigned int num;
1165 unsigned int wq_flags;
1166 unsigned long long num_ll;
1167 int r;
1168 int i;
1169 sector_t hash_position;
1170 char dummy;
1171 char *root_hash_digest_to_validate;
1172
1173 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1174 if (!v) {
1175 ti->error = "Cannot allocate verity structure";
1176 return -ENOMEM;
1177 }
1178 ti->private = v;
1179 v->ti = ti;
1180
1181 r = verity_fec_ctr_alloc(v);
1182 if (r)
1183 goto bad;
1184
1185 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
1186 ti->error = "Device must be readonly";
1187 r = -EINVAL;
1188 goto bad;
1189 }
1190
1191 if (argc < 10) {
1192 ti->error = "Not enough arguments";
1193 r = -EINVAL;
1194 goto bad;
1195 }
1196
1197 /* Parse optional parameters that modify primary args */
1198 if (argc > 10) {
1199 as.argc = argc - 10;
1200 as.argv = argv + 10;
1201 r = verity_parse_opt_args(&as, v, &verify_args, true);
1202 if (r < 0)
1203 goto bad;
1204 }
1205
1206 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1207 num > 1) {
1208 ti->error = "Invalid version";
1209 r = -EINVAL;
1210 goto bad;
1211 }
1212 v->version = num;
1213
1214 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1215 if (r) {
1216 ti->error = "Data device lookup failed";
1217 goto bad;
1218 }
1219
1220 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1221 if (r) {
1222 ti->error = "Hash device lookup failed";
1223 goto bad;
1224 }
1225
1226 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1227 !num || (num & (num - 1)) ||
1228 num < bdev_logical_block_size(v->data_dev->bdev) ||
1229 num > PAGE_SIZE) {
1230 ti->error = "Invalid data device block size";
1231 r = -EINVAL;
1232 goto bad;
1233 }
1234 v->data_dev_block_bits = __ffs(num);
1235
1236 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1237 !num || (num & (num - 1)) ||
1238 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1239 num > INT_MAX) {
1240 ti->error = "Invalid hash device block size";
1241 r = -EINVAL;
1242 goto bad;
1243 }
1244 v->hash_dev_block_bits = __ffs(num);
1245
1246 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1247 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1248 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1249 ti->error = "Invalid data blocks";
1250 r = -EINVAL;
1251 goto bad;
1252 }
1253 v->data_blocks = num_ll;
1254
1255 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1256 ti->error = "Data device is too small";
1257 r = -EINVAL;
1258 goto bad;
1259 }
1260
1261 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1262 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1263 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1264 ti->error = "Invalid hash start";
1265 r = -EINVAL;
1266 goto bad;
1267 }
1268 v->hash_start = num_ll;
1269
1270 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1271 if (!v->alg_name) {
1272 ti->error = "Cannot allocate algorithm name";
1273 r = -ENOMEM;
1274 goto bad;
1275 }
1276
1277 v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1278 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1279 if (IS_ERR(v->tfm)) {
1280 ti->error = "Cannot initialize hash function";
1281 r = PTR_ERR(v->tfm);
1282 v->tfm = NULL;
1283 goto bad;
1284 }
1285
1286 /*
1287 * dm-verity performance can vary greatly depending on which hash
1288 * algorithm implementation is used. Help people debug performance
1289 * problems by logging the ->cra_driver_name.
1290 */
1291 DMINFO("%s using implementation \"%s\"", v->alg_name,
1292 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1293
1294 v->digest_size = crypto_ahash_digestsize(v->tfm);
1295 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1296 ti->error = "Digest size too big";
1297 r = -EINVAL;
1298 goto bad;
1299 }
1300 v->ahash_reqsize = sizeof(struct ahash_request) +
1301 crypto_ahash_reqsize(v->tfm);
1302
1303 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1304 if (!v->root_digest) {
1305 ti->error = "Cannot allocate root digest";
1306 r = -ENOMEM;
1307 goto bad;
1308 }
1309 if (strlen(argv[8]) != v->digest_size * 2 ||
1310 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1311 ti->error = "Invalid root digest";
1312 r = -EINVAL;
1313 goto bad;
1314 }
1315 root_hash_digest_to_validate = argv[8];
1316
1317 if (strcmp(argv[9], "-")) {
1318 v->salt_size = strlen(argv[9]) / 2;
1319 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1320 if (!v->salt) {
1321 ti->error = "Cannot allocate salt";
1322 r = -ENOMEM;
1323 goto bad;
1324 }
1325 if (strlen(argv[9]) != v->salt_size * 2 ||
1326 hex2bin(v->salt, argv[9], v->salt_size)) {
1327 ti->error = "Invalid salt";
1328 r = -EINVAL;
1329 goto bad;
1330 }
1331 }
1332
1333 argv += 10;
1334 argc -= 10;
1335
1336 /* Optional parameters */
1337 if (argc) {
1338 as.argc = argc;
1339 as.argv = argv;
1340 r = verity_parse_opt_args(&as, v, &verify_args, false);
1341 if (r < 0)
1342 goto bad;
1343 }
1344
1345 /* Root hash signature is a optional parameter*/
1346 r = verity_verify_root_hash(root_hash_digest_to_validate,
1347 strlen(root_hash_digest_to_validate),
1348 verify_args.sig,
1349 verify_args.sig_size);
1350 if (r < 0) {
1351 ti->error = "Root hash verification failed";
1352 goto bad;
1353 }
1354 v->hash_per_block_bits =
1355 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1356
1357 v->levels = 0;
1358 if (v->data_blocks)
1359 while (v->hash_per_block_bits * v->levels < 64 &&
1360 (unsigned long long)(v->data_blocks - 1) >>
1361 (v->hash_per_block_bits * v->levels))
1362 v->levels++;
1363
1364 if (v->levels > DM_VERITY_MAX_LEVELS) {
1365 ti->error = "Too many tree levels";
1366 r = -E2BIG;
1367 goto bad;
1368 }
1369
1370 hash_position = v->hash_start;
1371 for (i = v->levels - 1; i >= 0; i--) {
1372 sector_t s;
1373 v->hash_level_block[i] = hash_position;
1374 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1375 >> ((i + 1) * v->hash_per_block_bits);
1376 if (hash_position + s < hash_position) {
1377 ti->error = "Hash device offset overflow";
1378 r = -E2BIG;
1379 goto bad;
1380 }
1381 hash_position += s;
1382 }
1383 v->hash_blocks = hash_position;
1384
1385 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1386 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1387 dm_bufio_alloc_callback, NULL,
1388 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1389 if (IS_ERR(v->bufio)) {
1390 ti->error = "Cannot initialize dm-bufio";
1391 r = PTR_ERR(v->bufio);
1392 v->bufio = NULL;
1393 goto bad;
1394 }
1395
1396 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1397 ti->error = "Hash device is too small";
1398 r = -E2BIG;
1399 goto bad;
1400 }
1401
1402 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1403 wq_flags = WQ_MEM_RECLAIM | WQ_UNBOUND;
1404 /*
1405 * Using WQ_HIGHPRI improves throughput and completion latency by
1406 * reducing wait times when reading from a dm-verity device.
1407 *
1408 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1409 * allows verify_wq to preempt softirq since verification in tasklet
1410 * will fall-back to using it for error handling (or if the bufio cache
1411 * doesn't have required hashes).
1412 */
1413 wq_flags |= WQ_HIGHPRI;
1414 v->verify_wq = alloc_workqueue("kverityd", wq_flags, num_online_cpus());
1415 if (!v->verify_wq) {
1416 ti->error = "Cannot allocate workqueue";
1417 r = -ENOMEM;
1418 goto bad;
1419 }
1420
1421 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1422 v->ahash_reqsize + v->digest_size * 2;
1423
1424 r = verity_fec_ctr(v);
1425 if (r)
1426 goto bad;
1427
1428 ti->per_io_data_size = roundup(ti->per_io_data_size,
1429 __alignof__(struct dm_verity_io));
1430
1431 verity_verify_sig_opts_cleanup(&verify_args);
1432
1433 return 0;
1434
1435bad:
1436
1437 verity_verify_sig_opts_cleanup(&verify_args);
1438 verity_dtr(ti);
1439
1440 return r;
1441}
1442
1443/*
1444 * Check whether a DM target is a verity target.
1445 */
1446bool dm_is_verity_target(struct dm_target *ti)
1447{
1448 return ti->type->module == THIS_MODULE;
1449}
1450
1451/*
1452 * Get the verity mode (error behavior) of a verity target.
1453 *
1454 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1455 * target.
1456 */
1457int dm_verity_get_mode(struct dm_target *ti)
1458{
1459 struct dm_verity *v = ti->private;
1460
1461 if (!dm_is_verity_target(ti))
1462 return -EINVAL;
1463
1464 return v->mode;
1465}
1466
1467/*
1468 * Get the root digest of a verity target.
1469 *
1470 * Returns a copy of the root digest, the caller is responsible for
1471 * freeing the memory of the digest.
1472 */
1473int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1474{
1475 struct dm_verity *v = ti->private;
1476
1477 if (!dm_is_verity_target(ti))
1478 return -EINVAL;
1479
1480 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1481 if (*root_digest == NULL)
1482 return -ENOMEM;
1483
1484 *digest_size = v->digest_size;
1485
1486 return 0;
1487}
1488
1489static struct target_type verity_target = {
1490 .name = "verity",
1491 .features = DM_TARGET_IMMUTABLE,
1492 .version = {1, 9, 0},
1493 .module = THIS_MODULE,
1494 .ctr = verity_ctr,
1495 .dtr = verity_dtr,
1496 .map = verity_map,
1497 .status = verity_status,
1498 .prepare_ioctl = verity_prepare_ioctl,
1499 .iterate_devices = verity_iterate_devices,
1500 .io_hints = verity_io_hints,
1501};
1502
1503static int __init dm_verity_init(void)
1504{
1505 int r;
1506
1507 r = dm_register_target(&verity_target);
1508 if (r < 0)
1509 DMERR("register failed %d", r);
1510
1511 return r;
1512}
1513
1514static void __exit dm_verity_exit(void)
1515{
1516 dm_unregister_target(&verity_target);
1517}
1518
1519module_init(dm_verity_init);
1520module_exit(dm_verity_exit);
1521
1522MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1523MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1524MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1525MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1526MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
7 *
8 * This file is released under the GPLv2.
9 *
10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
12 * hash device. Setting this greatly improves performance when data and hash
13 * are on the same disk on different partitions on devices with poor random
14 * access behavior.
15 */
16
17#include "dm-verity.h"
18#include "dm-verity-fec.h"
19
20#include <linux/module.h>
21#include <linux/reboot.h>
22
23#define DM_MSG_PREFIX "verity"
24
25#define DM_VERITY_ENV_LENGTH 42
26#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
27
28#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
29
30#define DM_VERITY_MAX_CORRUPTED_ERRS 100
31
32#define DM_VERITY_OPT_LOGGING "ignore_corruption"
33#define DM_VERITY_OPT_RESTART "restart_on_corruption"
34#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
35
36#define DM_VERITY_OPTS_MAX (2 + DM_VERITY_OPTS_FEC)
37
38static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
39
40module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
41
42struct dm_verity_prefetch_work {
43 struct work_struct work;
44 struct dm_verity *v;
45 sector_t block;
46 unsigned n_blocks;
47};
48
49/*
50 * Auxiliary structure appended to each dm-bufio buffer. If the value
51 * hash_verified is nonzero, hash of the block has been verified.
52 *
53 * The variable hash_verified is set to 0 when allocating the buffer, then
54 * it can be changed to 1 and it is never reset to 0 again.
55 *
56 * There is no lock around this value, a race condition can at worst cause
57 * that multiple processes verify the hash of the same buffer simultaneously
58 * and write 1 to hash_verified simultaneously.
59 * This condition is harmless, so we don't need locking.
60 */
61struct buffer_aux {
62 int hash_verified;
63};
64
65/*
66 * Initialize struct buffer_aux for a freshly created buffer.
67 */
68static void dm_bufio_alloc_callback(struct dm_buffer *buf)
69{
70 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
71
72 aux->hash_verified = 0;
73}
74
75/*
76 * Translate input sector number to the sector number on the target device.
77 */
78static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
79{
80 return v->data_start + dm_target_offset(v->ti, bi_sector);
81}
82
83/*
84 * Return hash position of a specified block at a specified tree level
85 * (0 is the lowest level).
86 * The lowest "hash_per_block_bits"-bits of the result denote hash position
87 * inside a hash block. The remaining bits denote location of the hash block.
88 */
89static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
90 int level)
91{
92 return block >> (level * v->hash_per_block_bits);
93}
94
95/*
96 * Wrapper for crypto_shash_init, which handles verity salting.
97 */
98static int verity_hash_init(struct dm_verity *v, struct shash_desc *desc)
99{
100 int r;
101
102 desc->tfm = v->tfm;
103 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
104
105 r = crypto_shash_init(desc);
106
107 if (unlikely(r < 0)) {
108 DMERR("crypto_shash_init failed: %d", r);
109 return r;
110 }
111
112 if (likely(v->version >= 1)) {
113 r = crypto_shash_update(desc, v->salt, v->salt_size);
114
115 if (unlikely(r < 0)) {
116 DMERR("crypto_shash_update failed: %d", r);
117 return r;
118 }
119 }
120
121 return 0;
122}
123
124static int verity_hash_update(struct dm_verity *v, struct shash_desc *desc,
125 const u8 *data, size_t len)
126{
127 int r = crypto_shash_update(desc, data, len);
128
129 if (unlikely(r < 0))
130 DMERR("crypto_shash_update failed: %d", r);
131
132 return r;
133}
134
135static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc,
136 u8 *digest)
137{
138 int r;
139
140 if (unlikely(!v->version)) {
141 r = crypto_shash_update(desc, v->salt, v->salt_size);
142
143 if (r < 0) {
144 DMERR("crypto_shash_update failed: %d", r);
145 return r;
146 }
147 }
148
149 r = crypto_shash_final(desc, digest);
150
151 if (unlikely(r < 0))
152 DMERR("crypto_shash_final failed: %d", r);
153
154 return r;
155}
156
157int verity_hash(struct dm_verity *v, struct shash_desc *desc,
158 const u8 *data, size_t len, u8 *digest)
159{
160 int r;
161
162 r = verity_hash_init(v, desc);
163 if (unlikely(r < 0))
164 return r;
165
166 r = verity_hash_update(v, desc, data, len);
167 if (unlikely(r < 0))
168 return r;
169
170 return verity_hash_final(v, desc, digest);
171}
172
173static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
174 sector_t *hash_block, unsigned *offset)
175{
176 sector_t position = verity_position_at_level(v, block, level);
177 unsigned idx;
178
179 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
180
181 if (!offset)
182 return;
183
184 idx = position & ((1 << v->hash_per_block_bits) - 1);
185 if (!v->version)
186 *offset = idx * v->digest_size;
187 else
188 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
189}
190
191/*
192 * Handle verification errors.
193 */
194static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
195 unsigned long long block)
196{
197 char verity_env[DM_VERITY_ENV_LENGTH];
198 char *envp[] = { verity_env, NULL };
199 const char *type_str = "";
200 struct mapped_device *md = dm_table_get_md(v->ti->table);
201
202 /* Corruption should be visible in device status in all modes */
203 v->hash_failed = 1;
204
205 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
206 goto out;
207
208 v->corrupted_errs++;
209
210 switch (type) {
211 case DM_VERITY_BLOCK_TYPE_DATA:
212 type_str = "data";
213 break;
214 case DM_VERITY_BLOCK_TYPE_METADATA:
215 type_str = "metadata";
216 break;
217 default:
218 BUG();
219 }
220
221 DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
222 block);
223
224 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
225 DMERR("%s: reached maximum errors", v->data_dev->name);
226
227 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
228 DM_VERITY_ENV_VAR_NAME, type, block);
229
230 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
231
232out:
233 if (v->mode == DM_VERITY_MODE_LOGGING)
234 return 0;
235
236 if (v->mode == DM_VERITY_MODE_RESTART)
237 kernel_restart("dm-verity device corrupted");
238
239 return 1;
240}
241
242/*
243 * Verify hash of a metadata block pertaining to the specified data block
244 * ("block" argument) at a specified level ("level" argument).
245 *
246 * On successful return, verity_io_want_digest(v, io) contains the hash value
247 * for a lower tree level or for the data block (if we're at the lowest level).
248 *
249 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
250 * If "skip_unverified" is false, unverified buffer is hashed and verified
251 * against current value of verity_io_want_digest(v, io).
252 */
253static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
254 sector_t block, int level, bool skip_unverified,
255 u8 *want_digest)
256{
257 struct dm_buffer *buf;
258 struct buffer_aux *aux;
259 u8 *data;
260 int r;
261 sector_t hash_block;
262 unsigned offset;
263
264 verity_hash_at_level(v, block, level, &hash_block, &offset);
265
266 data = dm_bufio_read(v->bufio, hash_block, &buf);
267 if (IS_ERR(data))
268 return PTR_ERR(data);
269
270 aux = dm_bufio_get_aux_data(buf);
271
272 if (!aux->hash_verified) {
273 if (skip_unverified) {
274 r = 1;
275 goto release_ret_r;
276 }
277
278 r = verity_hash(v, verity_io_hash_desc(v, io),
279 data, 1 << v->hash_dev_block_bits,
280 verity_io_real_digest(v, io));
281 if (unlikely(r < 0))
282 goto release_ret_r;
283
284 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
285 v->digest_size) == 0))
286 aux->hash_verified = 1;
287 else if (verity_fec_decode(v, io,
288 DM_VERITY_BLOCK_TYPE_METADATA,
289 hash_block, data, NULL) == 0)
290 aux->hash_verified = 1;
291 else if (verity_handle_err(v,
292 DM_VERITY_BLOCK_TYPE_METADATA,
293 hash_block)) {
294 r = -EIO;
295 goto release_ret_r;
296 }
297 }
298
299 data += offset;
300 memcpy(want_digest, data, v->digest_size);
301 r = 0;
302
303release_ret_r:
304 dm_bufio_release(buf);
305 return r;
306}
307
308/*
309 * Find a hash for a given block, write it to digest and verify the integrity
310 * of the hash tree if necessary.
311 */
312int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
313 sector_t block, u8 *digest, bool *is_zero)
314{
315 int r = 0, i;
316
317 if (likely(v->levels)) {
318 /*
319 * First, we try to get the requested hash for
320 * the current block. If the hash block itself is
321 * verified, zero is returned. If it isn't, this
322 * function returns 1 and we fall back to whole
323 * chain verification.
324 */
325 r = verity_verify_level(v, io, block, 0, true, digest);
326 if (likely(r <= 0))
327 goto out;
328 }
329
330 memcpy(digest, v->root_digest, v->digest_size);
331
332 for (i = v->levels - 1; i >= 0; i--) {
333 r = verity_verify_level(v, io, block, i, false, digest);
334 if (unlikely(r))
335 goto out;
336 }
337out:
338 if (!r && v->zero_digest)
339 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
340 else
341 *is_zero = false;
342
343 return r;
344}
345
346/*
347 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
348 * starting from iter.
349 */
350int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
351 struct bvec_iter *iter,
352 int (*process)(struct dm_verity *v,
353 struct dm_verity_io *io, u8 *data,
354 size_t len))
355{
356 unsigned todo = 1 << v->data_dev_block_bits;
357 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
358
359 do {
360 int r;
361 u8 *page;
362 unsigned len;
363 struct bio_vec bv = bio_iter_iovec(bio, *iter);
364
365 page = kmap_atomic(bv.bv_page);
366 len = bv.bv_len;
367
368 if (likely(len >= todo))
369 len = todo;
370
371 r = process(v, io, page + bv.bv_offset, len);
372 kunmap_atomic(page);
373
374 if (r < 0)
375 return r;
376
377 bio_advance_iter(bio, iter, len);
378 todo -= len;
379 } while (todo);
380
381 return 0;
382}
383
384static int verity_bv_hash_update(struct dm_verity *v, struct dm_verity_io *io,
385 u8 *data, size_t len)
386{
387 return verity_hash_update(v, verity_io_hash_desc(v, io), data, len);
388}
389
390static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
391 u8 *data, size_t len)
392{
393 memset(data, 0, len);
394 return 0;
395}
396
397/*
398 * Verify one "dm_verity_io" structure.
399 */
400static int verity_verify_io(struct dm_verity_io *io)
401{
402 bool is_zero;
403 struct dm_verity *v = io->v;
404 struct bvec_iter start;
405 unsigned b;
406
407 for (b = 0; b < io->n_blocks; b++) {
408 int r;
409 struct shash_desc *desc = verity_io_hash_desc(v, io);
410
411 r = verity_hash_for_block(v, io, io->block + b,
412 verity_io_want_digest(v, io),
413 &is_zero);
414 if (unlikely(r < 0))
415 return r;
416
417 if (is_zero) {
418 /*
419 * If we expect a zero block, don't validate, just
420 * return zeros.
421 */
422 r = verity_for_bv_block(v, io, &io->iter,
423 verity_bv_zero);
424 if (unlikely(r < 0))
425 return r;
426
427 continue;
428 }
429
430 r = verity_hash_init(v, desc);
431 if (unlikely(r < 0))
432 return r;
433
434 start = io->iter;
435 r = verity_for_bv_block(v, io, &io->iter, verity_bv_hash_update);
436 if (unlikely(r < 0))
437 return r;
438
439 r = verity_hash_final(v, desc, verity_io_real_digest(v, io));
440 if (unlikely(r < 0))
441 return r;
442
443 if (likely(memcmp(verity_io_real_digest(v, io),
444 verity_io_want_digest(v, io), v->digest_size) == 0))
445 continue;
446 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
447 io->block + b, NULL, &start) == 0)
448 continue;
449 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
450 io->block + b))
451 return -EIO;
452 }
453
454 return 0;
455}
456
457/*
458 * End one "io" structure with a given error.
459 */
460static void verity_finish_io(struct dm_verity_io *io, int error)
461{
462 struct dm_verity *v = io->v;
463 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
464
465 bio->bi_end_io = io->orig_bi_end_io;
466 bio->bi_error = error;
467
468 verity_fec_finish_io(io);
469
470 bio_endio(bio);
471}
472
473static void verity_work(struct work_struct *w)
474{
475 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
476
477 verity_finish_io(io, verity_verify_io(io));
478}
479
480static void verity_end_io(struct bio *bio)
481{
482 struct dm_verity_io *io = bio->bi_private;
483
484 if (bio->bi_error && !verity_fec_is_enabled(io->v)) {
485 verity_finish_io(io, bio->bi_error);
486 return;
487 }
488
489 INIT_WORK(&io->work, verity_work);
490 queue_work(io->v->verify_wq, &io->work);
491}
492
493/*
494 * Prefetch buffers for the specified io.
495 * The root buffer is not prefetched, it is assumed that it will be cached
496 * all the time.
497 */
498static void verity_prefetch_io(struct work_struct *work)
499{
500 struct dm_verity_prefetch_work *pw =
501 container_of(work, struct dm_verity_prefetch_work, work);
502 struct dm_verity *v = pw->v;
503 int i;
504
505 for (i = v->levels - 2; i >= 0; i--) {
506 sector_t hash_block_start;
507 sector_t hash_block_end;
508 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
509 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
510 if (!i) {
511 unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
512
513 cluster >>= v->data_dev_block_bits;
514 if (unlikely(!cluster))
515 goto no_prefetch_cluster;
516
517 if (unlikely(cluster & (cluster - 1)))
518 cluster = 1 << __fls(cluster);
519
520 hash_block_start &= ~(sector_t)(cluster - 1);
521 hash_block_end |= cluster - 1;
522 if (unlikely(hash_block_end >= v->hash_blocks))
523 hash_block_end = v->hash_blocks - 1;
524 }
525no_prefetch_cluster:
526 dm_bufio_prefetch(v->bufio, hash_block_start,
527 hash_block_end - hash_block_start + 1);
528 }
529
530 kfree(pw);
531}
532
533static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
534{
535 struct dm_verity_prefetch_work *pw;
536
537 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
538 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
539
540 if (!pw)
541 return;
542
543 INIT_WORK(&pw->work, verity_prefetch_io);
544 pw->v = v;
545 pw->block = io->block;
546 pw->n_blocks = io->n_blocks;
547 queue_work(v->verify_wq, &pw->work);
548}
549
550/*
551 * Bio map function. It allocates dm_verity_io structure and bio vector and
552 * fills them. Then it issues prefetches and the I/O.
553 */
554static int verity_map(struct dm_target *ti, struct bio *bio)
555{
556 struct dm_verity *v = ti->private;
557 struct dm_verity_io *io;
558
559 bio->bi_bdev = v->data_dev->bdev;
560 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
561
562 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
563 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
564 DMERR_LIMIT("unaligned io");
565 return -EIO;
566 }
567
568 if (bio_end_sector(bio) >>
569 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
570 DMERR_LIMIT("io out of range");
571 return -EIO;
572 }
573
574 if (bio_data_dir(bio) == WRITE)
575 return -EIO;
576
577 io = dm_per_bio_data(bio, ti->per_io_data_size);
578 io->v = v;
579 io->orig_bi_end_io = bio->bi_end_io;
580 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
581 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
582
583 bio->bi_end_io = verity_end_io;
584 bio->bi_private = io;
585 io->iter = bio->bi_iter;
586
587 verity_fec_init_io(io);
588
589 verity_submit_prefetch(v, io);
590
591 generic_make_request(bio);
592
593 return DM_MAPIO_SUBMITTED;
594}
595
596/*
597 * Status: V (valid) or C (corruption found)
598 */
599static void verity_status(struct dm_target *ti, status_type_t type,
600 unsigned status_flags, char *result, unsigned maxlen)
601{
602 struct dm_verity *v = ti->private;
603 unsigned args = 0;
604 unsigned sz = 0;
605 unsigned x;
606
607 switch (type) {
608 case STATUSTYPE_INFO:
609 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
610 break;
611 case STATUSTYPE_TABLE:
612 DMEMIT("%u %s %s %u %u %llu %llu %s ",
613 v->version,
614 v->data_dev->name,
615 v->hash_dev->name,
616 1 << v->data_dev_block_bits,
617 1 << v->hash_dev_block_bits,
618 (unsigned long long)v->data_blocks,
619 (unsigned long long)v->hash_start,
620 v->alg_name
621 );
622 for (x = 0; x < v->digest_size; x++)
623 DMEMIT("%02x", v->root_digest[x]);
624 DMEMIT(" ");
625 if (!v->salt_size)
626 DMEMIT("-");
627 else
628 for (x = 0; x < v->salt_size; x++)
629 DMEMIT("%02x", v->salt[x]);
630 if (v->mode != DM_VERITY_MODE_EIO)
631 args++;
632 if (verity_fec_is_enabled(v))
633 args += DM_VERITY_OPTS_FEC;
634 if (v->zero_digest)
635 args++;
636 if (!args)
637 return;
638 DMEMIT(" %u", args);
639 if (v->mode != DM_VERITY_MODE_EIO) {
640 DMEMIT(" ");
641 switch (v->mode) {
642 case DM_VERITY_MODE_LOGGING:
643 DMEMIT(DM_VERITY_OPT_LOGGING);
644 break;
645 case DM_VERITY_MODE_RESTART:
646 DMEMIT(DM_VERITY_OPT_RESTART);
647 break;
648 default:
649 BUG();
650 }
651 }
652 if (v->zero_digest)
653 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
654 sz = verity_fec_status_table(v, sz, result, maxlen);
655 break;
656 }
657}
658
659static int verity_prepare_ioctl(struct dm_target *ti,
660 struct block_device **bdev, fmode_t *mode)
661{
662 struct dm_verity *v = ti->private;
663
664 *bdev = v->data_dev->bdev;
665
666 if (v->data_start ||
667 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
668 return 1;
669 return 0;
670}
671
672static int verity_iterate_devices(struct dm_target *ti,
673 iterate_devices_callout_fn fn, void *data)
674{
675 struct dm_verity *v = ti->private;
676
677 return fn(ti, v->data_dev, v->data_start, ti->len, data);
678}
679
680static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
681{
682 struct dm_verity *v = ti->private;
683
684 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
685 limits->logical_block_size = 1 << v->data_dev_block_bits;
686
687 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
688 limits->physical_block_size = 1 << v->data_dev_block_bits;
689
690 blk_limits_io_min(limits, limits->logical_block_size);
691}
692
693static void verity_dtr(struct dm_target *ti)
694{
695 struct dm_verity *v = ti->private;
696
697 if (v->verify_wq)
698 destroy_workqueue(v->verify_wq);
699
700 if (v->bufio)
701 dm_bufio_client_destroy(v->bufio);
702
703 kfree(v->salt);
704 kfree(v->root_digest);
705 kfree(v->zero_digest);
706
707 if (v->tfm)
708 crypto_free_shash(v->tfm);
709
710 kfree(v->alg_name);
711
712 if (v->hash_dev)
713 dm_put_device(ti, v->hash_dev);
714
715 if (v->data_dev)
716 dm_put_device(ti, v->data_dev);
717
718 verity_fec_dtr(v);
719
720 kfree(v);
721}
722
723static int verity_alloc_zero_digest(struct dm_verity *v)
724{
725 int r = -ENOMEM;
726 struct shash_desc *desc;
727 u8 *zero_data;
728
729 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
730
731 if (!v->zero_digest)
732 return r;
733
734 desc = kmalloc(v->shash_descsize, GFP_KERNEL);
735
736 if (!desc)
737 return r; /* verity_dtr will free zero_digest */
738
739 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
740
741 if (!zero_data)
742 goto out;
743
744 r = verity_hash(v, desc, zero_data, 1 << v->data_dev_block_bits,
745 v->zero_digest);
746
747out:
748 kfree(desc);
749 kfree(zero_data);
750
751 return r;
752}
753
754static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
755{
756 int r;
757 unsigned argc;
758 struct dm_target *ti = v->ti;
759 const char *arg_name;
760
761 static struct dm_arg _args[] = {
762 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
763 };
764
765 r = dm_read_arg_group(_args, as, &argc, &ti->error);
766 if (r)
767 return -EINVAL;
768
769 if (!argc)
770 return 0;
771
772 do {
773 arg_name = dm_shift_arg(as);
774 argc--;
775
776 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
777 v->mode = DM_VERITY_MODE_LOGGING;
778 continue;
779
780 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
781 v->mode = DM_VERITY_MODE_RESTART;
782 continue;
783
784 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
785 r = verity_alloc_zero_digest(v);
786 if (r) {
787 ti->error = "Cannot allocate zero digest";
788 return r;
789 }
790 continue;
791
792 } else if (verity_is_fec_opt_arg(arg_name)) {
793 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
794 if (r)
795 return r;
796 continue;
797 }
798
799 ti->error = "Unrecognized verity feature request";
800 return -EINVAL;
801 } while (argc && !r);
802
803 return r;
804}
805
806/*
807 * Target parameters:
808 * <version> The current format is version 1.
809 * Vsn 0 is compatible with original Chromium OS releases.
810 * <data device>
811 * <hash device>
812 * <data block size>
813 * <hash block size>
814 * <the number of data blocks>
815 * <hash start block>
816 * <algorithm>
817 * <digest>
818 * <salt> Hex string or "-" if no salt.
819 */
820static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
821{
822 struct dm_verity *v;
823 struct dm_arg_set as;
824 unsigned int num;
825 unsigned long long num_ll;
826 int r;
827 int i;
828 sector_t hash_position;
829 char dummy;
830
831 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
832 if (!v) {
833 ti->error = "Cannot allocate verity structure";
834 return -ENOMEM;
835 }
836 ti->private = v;
837 v->ti = ti;
838
839 r = verity_fec_ctr_alloc(v);
840 if (r)
841 goto bad;
842
843 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
844 ti->error = "Device must be readonly";
845 r = -EINVAL;
846 goto bad;
847 }
848
849 if (argc < 10) {
850 ti->error = "Not enough arguments";
851 r = -EINVAL;
852 goto bad;
853 }
854
855 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
856 num > 1) {
857 ti->error = "Invalid version";
858 r = -EINVAL;
859 goto bad;
860 }
861 v->version = num;
862
863 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
864 if (r) {
865 ti->error = "Data device lookup failed";
866 goto bad;
867 }
868
869 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
870 if (r) {
871 ti->error = "Hash device lookup failed";
872 goto bad;
873 }
874
875 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
876 !num || (num & (num - 1)) ||
877 num < bdev_logical_block_size(v->data_dev->bdev) ||
878 num > PAGE_SIZE) {
879 ti->error = "Invalid data device block size";
880 r = -EINVAL;
881 goto bad;
882 }
883 v->data_dev_block_bits = __ffs(num);
884
885 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
886 !num || (num & (num - 1)) ||
887 num < bdev_logical_block_size(v->hash_dev->bdev) ||
888 num > INT_MAX) {
889 ti->error = "Invalid hash device block size";
890 r = -EINVAL;
891 goto bad;
892 }
893 v->hash_dev_block_bits = __ffs(num);
894
895 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
896 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
897 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
898 ti->error = "Invalid data blocks";
899 r = -EINVAL;
900 goto bad;
901 }
902 v->data_blocks = num_ll;
903
904 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
905 ti->error = "Data device is too small";
906 r = -EINVAL;
907 goto bad;
908 }
909
910 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
911 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
912 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
913 ti->error = "Invalid hash start";
914 r = -EINVAL;
915 goto bad;
916 }
917 v->hash_start = num_ll;
918
919 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
920 if (!v->alg_name) {
921 ti->error = "Cannot allocate algorithm name";
922 r = -ENOMEM;
923 goto bad;
924 }
925
926 v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
927 if (IS_ERR(v->tfm)) {
928 ti->error = "Cannot initialize hash function";
929 r = PTR_ERR(v->tfm);
930 v->tfm = NULL;
931 goto bad;
932 }
933 v->digest_size = crypto_shash_digestsize(v->tfm);
934 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
935 ti->error = "Digest size too big";
936 r = -EINVAL;
937 goto bad;
938 }
939 v->shash_descsize =
940 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
941
942 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
943 if (!v->root_digest) {
944 ti->error = "Cannot allocate root digest";
945 r = -ENOMEM;
946 goto bad;
947 }
948 if (strlen(argv[8]) != v->digest_size * 2 ||
949 hex2bin(v->root_digest, argv[8], v->digest_size)) {
950 ti->error = "Invalid root digest";
951 r = -EINVAL;
952 goto bad;
953 }
954
955 if (strcmp(argv[9], "-")) {
956 v->salt_size = strlen(argv[9]) / 2;
957 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
958 if (!v->salt) {
959 ti->error = "Cannot allocate salt";
960 r = -ENOMEM;
961 goto bad;
962 }
963 if (strlen(argv[9]) != v->salt_size * 2 ||
964 hex2bin(v->salt, argv[9], v->salt_size)) {
965 ti->error = "Invalid salt";
966 r = -EINVAL;
967 goto bad;
968 }
969 }
970
971 argv += 10;
972 argc -= 10;
973
974 /* Optional parameters */
975 if (argc) {
976 as.argc = argc;
977 as.argv = argv;
978
979 r = verity_parse_opt_args(&as, v);
980 if (r < 0)
981 goto bad;
982 }
983
984 v->hash_per_block_bits =
985 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
986
987 v->levels = 0;
988 if (v->data_blocks)
989 while (v->hash_per_block_bits * v->levels < 64 &&
990 (unsigned long long)(v->data_blocks - 1) >>
991 (v->hash_per_block_bits * v->levels))
992 v->levels++;
993
994 if (v->levels > DM_VERITY_MAX_LEVELS) {
995 ti->error = "Too many tree levels";
996 r = -E2BIG;
997 goto bad;
998 }
999
1000 hash_position = v->hash_start;
1001 for (i = v->levels - 1; i >= 0; i--) {
1002 sector_t s;
1003 v->hash_level_block[i] = hash_position;
1004 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1005 >> ((i + 1) * v->hash_per_block_bits);
1006 if (hash_position + s < hash_position) {
1007 ti->error = "Hash device offset overflow";
1008 r = -E2BIG;
1009 goto bad;
1010 }
1011 hash_position += s;
1012 }
1013 v->hash_blocks = hash_position;
1014
1015 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1016 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1017 dm_bufio_alloc_callback, NULL);
1018 if (IS_ERR(v->bufio)) {
1019 ti->error = "Cannot initialize dm-bufio";
1020 r = PTR_ERR(v->bufio);
1021 v->bufio = NULL;
1022 goto bad;
1023 }
1024
1025 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1026 ti->error = "Hash device is too small";
1027 r = -E2BIG;
1028 goto bad;
1029 }
1030
1031 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1032 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1033 if (!v->verify_wq) {
1034 ti->error = "Cannot allocate workqueue";
1035 r = -ENOMEM;
1036 goto bad;
1037 }
1038
1039 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1040 v->shash_descsize + v->digest_size * 2;
1041
1042 r = verity_fec_ctr(v);
1043 if (r)
1044 goto bad;
1045
1046 ti->per_io_data_size = roundup(ti->per_io_data_size,
1047 __alignof__(struct dm_verity_io));
1048
1049 return 0;
1050
1051bad:
1052 verity_dtr(ti);
1053
1054 return r;
1055}
1056
1057static struct target_type verity_target = {
1058 .name = "verity",
1059 .version = {1, 3, 0},
1060 .module = THIS_MODULE,
1061 .ctr = verity_ctr,
1062 .dtr = verity_dtr,
1063 .map = verity_map,
1064 .status = verity_status,
1065 .prepare_ioctl = verity_prepare_ioctl,
1066 .iterate_devices = verity_iterate_devices,
1067 .io_hints = verity_io_hints,
1068};
1069
1070static int __init dm_verity_init(void)
1071{
1072 int r;
1073
1074 r = dm_register_target(&verity_target);
1075 if (r < 0)
1076 DMERR("register failed %d", r);
1077
1078 return r;
1079}
1080
1081static void __exit dm_verity_exit(void)
1082{
1083 dm_unregister_target(&verity_target);
1084}
1085
1086module_init(dm_verity_init);
1087module_exit(dm_verity_exit);
1088
1089MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1090MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1091MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1092MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1093MODULE_LICENSE("GPL");