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