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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat, Inc.
4 *
5 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 *
7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
8 *
9 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
10 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
11 * hash device. Setting this greatly improves performance when data and hash
12 * are on the same disk on different partitions on devices with poor random
13 * access behavior.
14 */
15
16#include "dm-verity.h"
17#include "dm-verity-fec.h"
18#include "dm-verity-verify-sig.h"
19#include "dm-audit.h"
20#include <linux/module.h>
21#include <linux/reboot.h>
22#include <linux/scatterlist.h>
23#include <linux/string.h>
24#include <linux/jump_label.h>
25
26#define DM_MSG_PREFIX "verity"
27
28#define DM_VERITY_ENV_LENGTH 42
29#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
30
31#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
32
33#define DM_VERITY_MAX_CORRUPTED_ERRS 100
34
35#define DM_VERITY_OPT_LOGGING "ignore_corruption"
36#define DM_VERITY_OPT_RESTART "restart_on_corruption"
37#define DM_VERITY_OPT_PANIC "panic_on_corruption"
38#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
39#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
40#define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
41
42#define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \
43 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
44
45static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
46
47module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
48
49static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
50
51struct dm_verity_prefetch_work {
52 struct work_struct work;
53 struct dm_verity *v;
54 sector_t block;
55 unsigned int n_blocks;
56};
57
58/*
59 * Auxiliary structure appended to each dm-bufio buffer. If the value
60 * hash_verified is nonzero, hash of the block has been verified.
61 *
62 * The variable hash_verified is set to 0 when allocating the buffer, then
63 * it can be changed to 1 and it is never reset to 0 again.
64 *
65 * There is no lock around this value, a race condition can at worst cause
66 * that multiple processes verify the hash of the same buffer simultaneously
67 * and write 1 to hash_verified simultaneously.
68 * This condition is harmless, so we don't need locking.
69 */
70struct buffer_aux {
71 int hash_verified;
72};
73
74/*
75 * Initialize struct buffer_aux for a freshly created buffer.
76 */
77static void dm_bufio_alloc_callback(struct dm_buffer *buf)
78{
79 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
80
81 aux->hash_verified = 0;
82}
83
84/*
85 * Translate input sector number to the sector number on the target device.
86 */
87static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
88{
89 return v->data_start + dm_target_offset(v->ti, bi_sector);
90}
91
92/*
93 * Return hash position of a specified block at a specified tree level
94 * (0 is the lowest level).
95 * The lowest "hash_per_block_bits"-bits of the result denote hash position
96 * inside a hash block. The remaining bits denote location of the hash block.
97 */
98static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
99 int level)
100{
101 return block >> (level * v->hash_per_block_bits);
102}
103
104static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
105 const u8 *data, size_t len,
106 struct crypto_wait *wait)
107{
108 struct scatterlist sg;
109
110 if (likely(!is_vmalloc_addr(data))) {
111 sg_init_one(&sg, data, len);
112 ahash_request_set_crypt(req, &sg, NULL, len);
113 return crypto_wait_req(crypto_ahash_update(req), wait);
114 }
115
116 do {
117 int r;
118 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
119
120 flush_kernel_vmap_range((void *)data, this_step);
121 sg_init_table(&sg, 1);
122 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
123 ahash_request_set_crypt(req, &sg, NULL, this_step);
124 r = crypto_wait_req(crypto_ahash_update(req), wait);
125 if (unlikely(r))
126 return r;
127 data += this_step;
128 len -= this_step;
129 } while (len);
130
131 return 0;
132}
133
134/*
135 * Wrapper for crypto_ahash_init, which handles verity salting.
136 */
137static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
138 struct crypto_wait *wait, bool may_sleep)
139{
140 int r;
141
142 ahash_request_set_tfm(req, v->tfm);
143 ahash_request_set_callback(req,
144 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
145 crypto_req_done, (void *)wait);
146 crypto_init_wait(wait);
147
148 r = crypto_wait_req(crypto_ahash_init(req), wait);
149
150 if (unlikely(r < 0)) {
151 if (r != -ENOMEM)
152 DMERR("crypto_ahash_init failed: %d", r);
153 return r;
154 }
155
156 if (likely(v->salt_size && (v->version >= 1)))
157 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
158
159 return r;
160}
161
162static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
163 u8 *digest, struct crypto_wait *wait)
164{
165 int r;
166
167 if (unlikely(v->salt_size && (!v->version))) {
168 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
169
170 if (r < 0) {
171 DMERR("%s failed updating salt: %d", __func__, r);
172 goto out;
173 }
174 }
175
176 ahash_request_set_crypt(req, NULL, digest, 0);
177 r = crypto_wait_req(crypto_ahash_final(req), wait);
178out:
179 return r;
180}
181
182int verity_hash(struct dm_verity *v, struct ahash_request *req,
183 const u8 *data, size_t len, u8 *digest, bool may_sleep)
184{
185 int r;
186 struct crypto_wait wait;
187
188 r = verity_hash_init(v, req, &wait, may_sleep);
189 if (unlikely(r < 0))
190 goto out;
191
192 r = verity_hash_update(v, req, data, len, &wait);
193 if (unlikely(r < 0))
194 goto out;
195
196 r = verity_hash_final(v, req, digest, &wait);
197
198out:
199 return r;
200}
201
202static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
203 sector_t *hash_block, unsigned int *offset)
204{
205 sector_t position = verity_position_at_level(v, block, level);
206 unsigned int idx;
207
208 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
209
210 if (!offset)
211 return;
212
213 idx = position & ((1 << v->hash_per_block_bits) - 1);
214 if (!v->version)
215 *offset = idx * v->digest_size;
216 else
217 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
218}
219
220/*
221 * Handle verification errors.
222 */
223static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
224 unsigned long long block)
225{
226 char verity_env[DM_VERITY_ENV_LENGTH];
227 char *envp[] = { verity_env, NULL };
228 const char *type_str = "";
229 struct mapped_device *md = dm_table_get_md(v->ti->table);
230
231 /* Corruption should be visible in device status in all modes */
232 v->hash_failed = true;
233
234 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
235 goto out;
236
237 v->corrupted_errs++;
238
239 switch (type) {
240 case DM_VERITY_BLOCK_TYPE_DATA:
241 type_str = "data";
242 break;
243 case DM_VERITY_BLOCK_TYPE_METADATA:
244 type_str = "metadata";
245 break;
246 default:
247 BUG();
248 }
249
250 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
251 type_str, block);
252
253 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
254 DMERR("%s: reached maximum errors", v->data_dev->name);
255 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
256 }
257
258 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
259 DM_VERITY_ENV_VAR_NAME, type, block);
260
261 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
262
263out:
264 if (v->mode == DM_VERITY_MODE_LOGGING)
265 return 0;
266
267 if (v->mode == DM_VERITY_MODE_RESTART)
268 kernel_restart("dm-verity device corrupted");
269
270 if (v->mode == DM_VERITY_MODE_PANIC)
271 panic("dm-verity device corrupted");
272
273 return 1;
274}
275
276/*
277 * Verify hash of a metadata block pertaining to the specified data block
278 * ("block" argument) at a specified level ("level" argument).
279 *
280 * On successful return, verity_io_want_digest(v, io) contains the hash value
281 * for a lower tree level or for the data block (if we're at the lowest level).
282 *
283 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
284 * If "skip_unverified" is false, unverified buffer is hashed and verified
285 * against current value of verity_io_want_digest(v, io).
286 */
287static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
288 sector_t block, int level, bool skip_unverified,
289 u8 *want_digest)
290{
291 struct dm_buffer *buf;
292 struct buffer_aux *aux;
293 u8 *data;
294 int r;
295 sector_t hash_block;
296 unsigned int offset;
297
298 verity_hash_at_level(v, block, level, &hash_block, &offset);
299
300 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
301 data = dm_bufio_get(v->bufio, hash_block, &buf);
302 if (data == NULL) {
303 /*
304 * In tasklet and the hash was not in the bufio cache.
305 * Return early and resume execution from a work-queue
306 * to read the hash from disk.
307 */
308 return -EAGAIN;
309 }
310 } else
311 data = dm_bufio_read(v->bufio, hash_block, &buf);
312
313 if (IS_ERR(data))
314 return PTR_ERR(data);
315
316 aux = dm_bufio_get_aux_data(buf);
317
318 if (!aux->hash_verified) {
319 if (skip_unverified) {
320 r = 1;
321 goto release_ret_r;
322 }
323
324 r = verity_hash(v, verity_io_hash_req(v, io),
325 data, 1 << v->hash_dev_block_bits,
326 verity_io_real_digest(v, io), !io->in_tasklet);
327 if (unlikely(r < 0))
328 goto release_ret_r;
329
330 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
331 v->digest_size) == 0))
332 aux->hash_verified = 1;
333 else if (static_branch_unlikely(&use_tasklet_enabled) &&
334 io->in_tasklet) {
335 /*
336 * Error handling code (FEC included) cannot be run in a
337 * tasklet since it may sleep, so fallback to work-queue.
338 */
339 r = -EAGAIN;
340 goto release_ret_r;
341 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
342 hash_block, data, NULL) == 0)
343 aux->hash_verified = 1;
344 else if (verity_handle_err(v,
345 DM_VERITY_BLOCK_TYPE_METADATA,
346 hash_block)) {
347 struct bio *bio =
348 dm_bio_from_per_bio_data(io,
349 v->ti->per_io_data_size);
350 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
351 block, 0);
352 r = -EIO;
353 goto release_ret_r;
354 }
355 }
356
357 data += offset;
358 memcpy(want_digest, data, v->digest_size);
359 r = 0;
360
361release_ret_r:
362 dm_bufio_release(buf);
363 return r;
364}
365
366/*
367 * Find a hash for a given block, write it to digest and verify the integrity
368 * of the hash tree if necessary.
369 */
370int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
371 sector_t block, u8 *digest, bool *is_zero)
372{
373 int r = 0, i;
374
375 if (likely(v->levels)) {
376 /*
377 * First, we try to get the requested hash for
378 * the current block. If the hash block itself is
379 * verified, zero is returned. If it isn't, this
380 * function returns 1 and we fall back to whole
381 * chain verification.
382 */
383 r = verity_verify_level(v, io, block, 0, true, digest);
384 if (likely(r <= 0))
385 goto out;
386 }
387
388 memcpy(digest, v->root_digest, v->digest_size);
389
390 for (i = v->levels - 1; i >= 0; i--) {
391 r = verity_verify_level(v, io, block, i, false, digest);
392 if (unlikely(r))
393 goto out;
394 }
395out:
396 if (!r && v->zero_digest)
397 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
398 else
399 *is_zero = false;
400
401 return r;
402}
403
404/*
405 * Calculates the digest for the given bio
406 */
407static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
408 struct bvec_iter *iter, struct crypto_wait *wait)
409{
410 unsigned int todo = 1 << v->data_dev_block_bits;
411 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
412 struct scatterlist sg;
413 struct ahash_request *req = verity_io_hash_req(v, io);
414
415 do {
416 int r;
417 unsigned int len;
418 struct bio_vec bv = bio_iter_iovec(bio, *iter);
419
420 sg_init_table(&sg, 1);
421
422 len = bv.bv_len;
423
424 if (likely(len >= todo))
425 len = todo;
426 /*
427 * Operating on a single page at a time looks suboptimal
428 * until you consider the typical block size is 4,096B.
429 * Going through this loops twice should be very rare.
430 */
431 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
432 ahash_request_set_crypt(req, &sg, NULL, len);
433 r = crypto_wait_req(crypto_ahash_update(req), wait);
434
435 if (unlikely(r < 0)) {
436 DMERR("%s crypto op failed: %d", __func__, r);
437 return r;
438 }
439
440 bio_advance_iter(bio, iter, len);
441 todo -= len;
442 } while (todo);
443
444 return 0;
445}
446
447/*
448 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
449 * starting from iter.
450 */
451int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
452 struct bvec_iter *iter,
453 int (*process)(struct dm_verity *v,
454 struct dm_verity_io *io, u8 *data,
455 size_t len))
456{
457 unsigned int todo = 1 << v->data_dev_block_bits;
458 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
459
460 do {
461 int r;
462 u8 *page;
463 unsigned int len;
464 struct bio_vec bv = bio_iter_iovec(bio, *iter);
465
466 page = bvec_kmap_local(&bv);
467 len = bv.bv_len;
468
469 if (likely(len >= todo))
470 len = todo;
471
472 r = process(v, io, page, len);
473 kunmap_local(page);
474
475 if (r < 0)
476 return r;
477
478 bio_advance_iter(bio, iter, len);
479 todo -= len;
480 } while (todo);
481
482 return 0;
483}
484
485static int verity_recheck_copy(struct dm_verity *v, struct dm_verity_io *io,
486 u8 *data, size_t len)
487{
488 memcpy(data, io->recheck_buffer, len);
489 io->recheck_buffer += len;
490
491 return 0;
492}
493
494static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
495 struct bvec_iter start, sector_t cur_block)
496{
497 struct page *page;
498 void *buffer;
499 int r;
500 struct dm_io_request io_req;
501 struct dm_io_region io_loc;
502
503 page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
504 buffer = page_to_virt(page);
505
506 io_req.bi_opf = REQ_OP_READ;
507 io_req.mem.type = DM_IO_KMEM;
508 io_req.mem.ptr.addr = buffer;
509 io_req.notify.fn = NULL;
510 io_req.client = v->io;
511 io_loc.bdev = v->data_dev->bdev;
512 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
513 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
514 r = dm_io(&io_req, 1, &io_loc, NULL);
515 if (unlikely(r))
516 goto free_ret;
517
518 r = verity_hash(v, verity_io_hash_req(v, io), buffer,
519 1 << v->data_dev_block_bits,
520 verity_io_real_digest(v, io), true);
521 if (unlikely(r))
522 goto free_ret;
523
524 if (memcmp(verity_io_real_digest(v, io),
525 verity_io_want_digest(v, io), v->digest_size)) {
526 r = -EIO;
527 goto free_ret;
528 }
529
530 io->recheck_buffer = buffer;
531 r = verity_for_bv_block(v, io, &start, verity_recheck_copy);
532 if (unlikely(r))
533 goto free_ret;
534
535 r = 0;
536free_ret:
537 mempool_free(page, &v->recheck_pool);
538
539 return r;
540}
541
542static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
543 u8 *data, size_t len)
544{
545 memset(data, 0, len);
546 return 0;
547}
548
549/*
550 * Moves the bio iter one data block forward.
551 */
552static inline void verity_bv_skip_block(struct dm_verity *v,
553 struct dm_verity_io *io,
554 struct bvec_iter *iter)
555{
556 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
557
558 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
559}
560
561/*
562 * Verify one "dm_verity_io" structure.
563 */
564static int verity_verify_io(struct dm_verity_io *io)
565{
566 bool is_zero;
567 struct dm_verity *v = io->v;
568 struct bvec_iter start;
569 struct bvec_iter iter_copy;
570 struct bvec_iter *iter;
571 struct crypto_wait wait;
572 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
573 unsigned int b;
574
575 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
576 /*
577 * Copy the iterator in case we need to restart
578 * verification in a work-queue.
579 */
580 iter_copy = io->iter;
581 iter = &iter_copy;
582 } else
583 iter = &io->iter;
584
585 for (b = 0; b < io->n_blocks; b++) {
586 int r;
587 sector_t cur_block = io->block + b;
588 struct ahash_request *req = verity_io_hash_req(v, io);
589
590 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
591 likely(test_bit(cur_block, v->validated_blocks))) {
592 verity_bv_skip_block(v, io, iter);
593 continue;
594 }
595
596 r = verity_hash_for_block(v, io, cur_block,
597 verity_io_want_digest(v, io),
598 &is_zero);
599 if (unlikely(r < 0))
600 return r;
601
602 if (is_zero) {
603 /*
604 * If we expect a zero block, don't validate, just
605 * return zeros.
606 */
607 r = verity_for_bv_block(v, io, iter,
608 verity_bv_zero);
609 if (unlikely(r < 0))
610 return r;
611
612 continue;
613 }
614
615 r = verity_hash_init(v, req, &wait, !io->in_tasklet);
616 if (unlikely(r < 0))
617 return r;
618
619 start = *iter;
620 r = verity_for_io_block(v, io, iter, &wait);
621 if (unlikely(r < 0))
622 return r;
623
624 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
625 &wait);
626 if (unlikely(r < 0))
627 return r;
628
629 if (likely(memcmp(verity_io_real_digest(v, io),
630 verity_io_want_digest(v, io), v->digest_size) == 0)) {
631 if (v->validated_blocks)
632 set_bit(cur_block, v->validated_blocks);
633 continue;
634 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
635 io->in_tasklet) {
636 /*
637 * Error handling code (FEC included) cannot be run in a
638 * tasklet since it may sleep, so fallback to work-queue.
639 */
640 return -EAGAIN;
641 } else if (verity_recheck(v, io, start, cur_block) == 0) {
642 if (v->validated_blocks)
643 set_bit(cur_block, v->validated_blocks);
644 continue;
645#if defined(CONFIG_DM_VERITY_FEC)
646 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
647 cur_block, NULL, &start) == 0) {
648 continue;
649#endif
650 } else {
651 if (bio->bi_status) {
652 /*
653 * Error correction failed; Just return error
654 */
655 return -EIO;
656 }
657 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
658 cur_block)) {
659 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
660 bio, cur_block, 0);
661 return -EIO;
662 }
663 }
664 }
665
666 return 0;
667}
668
669/*
670 * Skip verity work in response to I/O error when system is shutting down.
671 */
672static inline bool verity_is_system_shutting_down(void)
673{
674 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
675 || system_state == SYSTEM_RESTART;
676}
677
678/*
679 * End one "io" structure with a given error.
680 */
681static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
682{
683 struct dm_verity *v = io->v;
684 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
685
686 bio->bi_end_io = io->orig_bi_end_io;
687 bio->bi_status = status;
688
689 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
690 verity_fec_finish_io(io);
691
692 bio_endio(bio);
693}
694
695static void verity_work(struct work_struct *w)
696{
697 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
698
699 io->in_tasklet = false;
700
701 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
702}
703
704static void verity_end_io(struct bio *bio)
705{
706 struct dm_verity_io *io = bio->bi_private;
707
708 if (bio->bi_status &&
709 (!verity_fec_is_enabled(io->v) ||
710 verity_is_system_shutting_down() ||
711 (bio->bi_opf & REQ_RAHEAD))) {
712 verity_finish_io(io, bio->bi_status);
713 return;
714 }
715
716 INIT_WORK(&io->work, verity_work);
717 queue_work(io->v->verify_wq, &io->work);
718}
719
720/*
721 * Prefetch buffers for the specified io.
722 * The root buffer is not prefetched, it is assumed that it will be cached
723 * all the time.
724 */
725static void verity_prefetch_io(struct work_struct *work)
726{
727 struct dm_verity_prefetch_work *pw =
728 container_of(work, struct dm_verity_prefetch_work, work);
729 struct dm_verity *v = pw->v;
730 int i;
731
732 for (i = v->levels - 2; i >= 0; i--) {
733 sector_t hash_block_start;
734 sector_t hash_block_end;
735
736 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
737 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
738
739 if (!i) {
740 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
741
742 cluster >>= v->data_dev_block_bits;
743 if (unlikely(!cluster))
744 goto no_prefetch_cluster;
745
746 if (unlikely(cluster & (cluster - 1)))
747 cluster = 1 << __fls(cluster);
748
749 hash_block_start &= ~(sector_t)(cluster - 1);
750 hash_block_end |= cluster - 1;
751 if (unlikely(hash_block_end >= v->hash_blocks))
752 hash_block_end = v->hash_blocks - 1;
753 }
754no_prefetch_cluster:
755 dm_bufio_prefetch(v->bufio, hash_block_start,
756 hash_block_end - hash_block_start + 1);
757 }
758
759 kfree(pw);
760}
761
762static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
763{
764 sector_t block = io->block;
765 unsigned int n_blocks = io->n_blocks;
766 struct dm_verity_prefetch_work *pw;
767
768 if (v->validated_blocks) {
769 while (n_blocks && test_bit(block, v->validated_blocks)) {
770 block++;
771 n_blocks--;
772 }
773 while (n_blocks && test_bit(block + n_blocks - 1,
774 v->validated_blocks))
775 n_blocks--;
776 if (!n_blocks)
777 return;
778 }
779
780 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
781 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
782
783 if (!pw)
784 return;
785
786 INIT_WORK(&pw->work, verity_prefetch_io);
787 pw->v = v;
788 pw->block = block;
789 pw->n_blocks = n_blocks;
790 queue_work(v->verify_wq, &pw->work);
791}
792
793/*
794 * Bio map function. It allocates dm_verity_io structure and bio vector and
795 * fills them. Then it issues prefetches and the I/O.
796 */
797static int verity_map(struct dm_target *ti, struct bio *bio)
798{
799 struct dm_verity *v = ti->private;
800 struct dm_verity_io *io;
801
802 bio_set_dev(bio, v->data_dev->bdev);
803 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
804
805 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
806 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
807 DMERR_LIMIT("unaligned io");
808 return DM_MAPIO_KILL;
809 }
810
811 if (bio_end_sector(bio) >>
812 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
813 DMERR_LIMIT("io out of range");
814 return DM_MAPIO_KILL;
815 }
816
817 if (bio_data_dir(bio) == WRITE)
818 return DM_MAPIO_KILL;
819
820 io = dm_per_bio_data(bio, ti->per_io_data_size);
821 io->v = v;
822 io->orig_bi_end_io = bio->bi_end_io;
823 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
824 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
825
826 bio->bi_end_io = verity_end_io;
827 bio->bi_private = io;
828 io->iter = bio->bi_iter;
829
830 verity_fec_init_io(io);
831
832 verity_submit_prefetch(v, io);
833
834 submit_bio_noacct(bio);
835
836 return DM_MAPIO_SUBMITTED;
837}
838
839/*
840 * Status: V (valid) or C (corruption found)
841 */
842static void verity_status(struct dm_target *ti, status_type_t type,
843 unsigned int status_flags, char *result, unsigned int maxlen)
844{
845 struct dm_verity *v = ti->private;
846 unsigned int args = 0;
847 unsigned int sz = 0;
848 unsigned int x;
849
850 switch (type) {
851 case STATUSTYPE_INFO:
852 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
853 break;
854 case STATUSTYPE_TABLE:
855 DMEMIT("%u %s %s %u %u %llu %llu %s ",
856 v->version,
857 v->data_dev->name,
858 v->hash_dev->name,
859 1 << v->data_dev_block_bits,
860 1 << v->hash_dev_block_bits,
861 (unsigned long long)v->data_blocks,
862 (unsigned long long)v->hash_start,
863 v->alg_name
864 );
865 for (x = 0; x < v->digest_size; x++)
866 DMEMIT("%02x", v->root_digest[x]);
867 DMEMIT(" ");
868 if (!v->salt_size)
869 DMEMIT("-");
870 else
871 for (x = 0; x < v->salt_size; x++)
872 DMEMIT("%02x", v->salt[x]);
873 if (v->mode != DM_VERITY_MODE_EIO)
874 args++;
875 if (verity_fec_is_enabled(v))
876 args += DM_VERITY_OPTS_FEC;
877 if (v->zero_digest)
878 args++;
879 if (v->validated_blocks)
880 args++;
881 if (v->use_tasklet)
882 args++;
883 if (v->signature_key_desc)
884 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
885 if (!args)
886 return;
887 DMEMIT(" %u", args);
888 if (v->mode != DM_VERITY_MODE_EIO) {
889 DMEMIT(" ");
890 switch (v->mode) {
891 case DM_VERITY_MODE_LOGGING:
892 DMEMIT(DM_VERITY_OPT_LOGGING);
893 break;
894 case DM_VERITY_MODE_RESTART:
895 DMEMIT(DM_VERITY_OPT_RESTART);
896 break;
897 case DM_VERITY_MODE_PANIC:
898 DMEMIT(DM_VERITY_OPT_PANIC);
899 break;
900 default:
901 BUG();
902 }
903 }
904 if (v->zero_digest)
905 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
906 if (v->validated_blocks)
907 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
908 if (v->use_tasklet)
909 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
910 sz = verity_fec_status_table(v, sz, result, maxlen);
911 if (v->signature_key_desc)
912 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
913 " %s", v->signature_key_desc);
914 break;
915
916 case STATUSTYPE_IMA:
917 DMEMIT_TARGET_NAME_VERSION(ti->type);
918 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
919 DMEMIT(",verity_version=%u", v->version);
920 DMEMIT(",data_device_name=%s", v->data_dev->name);
921 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
922 DMEMIT(",verity_algorithm=%s", v->alg_name);
923
924 DMEMIT(",root_digest=");
925 for (x = 0; x < v->digest_size; x++)
926 DMEMIT("%02x", v->root_digest[x]);
927
928 DMEMIT(",salt=");
929 if (!v->salt_size)
930 DMEMIT("-");
931 else
932 for (x = 0; x < v->salt_size; x++)
933 DMEMIT("%02x", v->salt[x]);
934
935 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
936 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
937 if (v->signature_key_desc)
938 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
939
940 if (v->mode != DM_VERITY_MODE_EIO) {
941 DMEMIT(",verity_mode=");
942 switch (v->mode) {
943 case DM_VERITY_MODE_LOGGING:
944 DMEMIT(DM_VERITY_OPT_LOGGING);
945 break;
946 case DM_VERITY_MODE_RESTART:
947 DMEMIT(DM_VERITY_OPT_RESTART);
948 break;
949 case DM_VERITY_MODE_PANIC:
950 DMEMIT(DM_VERITY_OPT_PANIC);
951 break;
952 default:
953 DMEMIT("invalid");
954 }
955 }
956 DMEMIT(";");
957 break;
958 }
959}
960
961static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
962{
963 struct dm_verity *v = ti->private;
964
965 *bdev = v->data_dev->bdev;
966
967 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
968 return 1;
969 return 0;
970}
971
972static int verity_iterate_devices(struct dm_target *ti,
973 iterate_devices_callout_fn fn, void *data)
974{
975 struct dm_verity *v = ti->private;
976
977 return fn(ti, v->data_dev, v->data_start, ti->len, data);
978}
979
980static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
981{
982 struct dm_verity *v = ti->private;
983
984 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
985 limits->logical_block_size = 1 << v->data_dev_block_bits;
986
987 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
988 limits->physical_block_size = 1 << v->data_dev_block_bits;
989
990 blk_limits_io_min(limits, limits->logical_block_size);
991}
992
993static void verity_dtr(struct dm_target *ti)
994{
995 struct dm_verity *v = ti->private;
996
997 if (v->verify_wq)
998 destroy_workqueue(v->verify_wq);
999
1000 mempool_exit(&v->recheck_pool);
1001 if (v->io)
1002 dm_io_client_destroy(v->io);
1003
1004 if (v->bufio)
1005 dm_bufio_client_destroy(v->bufio);
1006
1007 kvfree(v->validated_blocks);
1008 kfree(v->salt);
1009 kfree(v->root_digest);
1010 kfree(v->zero_digest);
1011
1012 if (v->tfm)
1013 crypto_free_ahash(v->tfm);
1014
1015 kfree(v->alg_name);
1016
1017 if (v->hash_dev)
1018 dm_put_device(ti, v->hash_dev);
1019
1020 if (v->data_dev)
1021 dm_put_device(ti, v->data_dev);
1022
1023 verity_fec_dtr(v);
1024
1025 kfree(v->signature_key_desc);
1026
1027 if (v->use_tasklet)
1028 static_branch_dec(&use_tasklet_enabled);
1029
1030 kfree(v);
1031
1032 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1033}
1034
1035static int verity_alloc_most_once(struct dm_verity *v)
1036{
1037 struct dm_target *ti = v->ti;
1038
1039 /* the bitset can only handle INT_MAX blocks */
1040 if (v->data_blocks > INT_MAX) {
1041 ti->error = "device too large to use check_at_most_once";
1042 return -E2BIG;
1043 }
1044
1045 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1046 sizeof(unsigned long),
1047 GFP_KERNEL);
1048 if (!v->validated_blocks) {
1049 ti->error = "failed to allocate bitset for check_at_most_once";
1050 return -ENOMEM;
1051 }
1052
1053 return 0;
1054}
1055
1056static int verity_alloc_zero_digest(struct dm_verity *v)
1057{
1058 int r = -ENOMEM;
1059 struct ahash_request *req;
1060 u8 *zero_data;
1061
1062 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1063
1064 if (!v->zero_digest)
1065 return r;
1066
1067 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1068
1069 if (!req)
1070 return r; /* verity_dtr will free zero_digest */
1071
1072 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1073
1074 if (!zero_data)
1075 goto out;
1076
1077 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1078 v->zero_digest, true);
1079
1080out:
1081 kfree(req);
1082 kfree(zero_data);
1083
1084 return r;
1085}
1086
1087static inline bool verity_is_verity_mode(const char *arg_name)
1088{
1089 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1090 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1091 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1092}
1093
1094static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1095{
1096 if (v->mode)
1097 return -EINVAL;
1098
1099 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1100 v->mode = DM_VERITY_MODE_LOGGING;
1101 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1102 v->mode = DM_VERITY_MODE_RESTART;
1103 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1104 v->mode = DM_VERITY_MODE_PANIC;
1105
1106 return 0;
1107}
1108
1109static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1110 struct dm_verity_sig_opts *verify_args,
1111 bool only_modifier_opts)
1112{
1113 int r = 0;
1114 unsigned int argc;
1115 struct dm_target *ti = v->ti;
1116 const char *arg_name;
1117
1118 static const struct dm_arg _args[] = {
1119 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1120 };
1121
1122 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1123 if (r)
1124 return -EINVAL;
1125
1126 if (!argc)
1127 return 0;
1128
1129 do {
1130 arg_name = dm_shift_arg(as);
1131 argc--;
1132
1133 if (verity_is_verity_mode(arg_name)) {
1134 if (only_modifier_opts)
1135 continue;
1136 r = verity_parse_verity_mode(v, arg_name);
1137 if (r) {
1138 ti->error = "Conflicting error handling parameters";
1139 return r;
1140 }
1141 continue;
1142
1143 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1144 if (only_modifier_opts)
1145 continue;
1146 r = verity_alloc_zero_digest(v);
1147 if (r) {
1148 ti->error = "Cannot allocate zero digest";
1149 return r;
1150 }
1151 continue;
1152
1153 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1154 if (only_modifier_opts)
1155 continue;
1156 r = verity_alloc_most_once(v);
1157 if (r)
1158 return r;
1159 continue;
1160
1161 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1162 v->use_tasklet = true;
1163 static_branch_inc(&use_tasklet_enabled);
1164 continue;
1165
1166 } else if (verity_is_fec_opt_arg(arg_name)) {
1167 if (only_modifier_opts)
1168 continue;
1169 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1170 if (r)
1171 return r;
1172 continue;
1173
1174 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1175 if (only_modifier_opts)
1176 continue;
1177 r = verity_verify_sig_parse_opt_args(as, v,
1178 verify_args,
1179 &argc, arg_name);
1180 if (r)
1181 return r;
1182 continue;
1183
1184 } else if (only_modifier_opts) {
1185 /*
1186 * Ignore unrecognized opt, could easily be an extra
1187 * argument to an option whose parsing was skipped.
1188 * Normal parsing (@only_modifier_opts=false) will
1189 * properly parse all options (and their extra args).
1190 */
1191 continue;
1192 }
1193
1194 DMERR("Unrecognized verity feature request: %s", arg_name);
1195 ti->error = "Unrecognized verity feature request";
1196 return -EINVAL;
1197 } while (argc && !r);
1198
1199 return r;
1200}
1201
1202/*
1203 * Target parameters:
1204 * <version> The current format is version 1.
1205 * Vsn 0 is compatible with original Chromium OS releases.
1206 * <data device>
1207 * <hash device>
1208 * <data block size>
1209 * <hash block size>
1210 * <the number of data blocks>
1211 * <hash start block>
1212 * <algorithm>
1213 * <digest>
1214 * <salt> Hex string or "-" if no salt.
1215 */
1216static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1217{
1218 struct dm_verity *v;
1219 struct dm_verity_sig_opts verify_args = {0};
1220 struct dm_arg_set as;
1221 unsigned int num;
1222 unsigned long long num_ll;
1223 int r;
1224 int i;
1225 sector_t hash_position;
1226 char dummy;
1227 char *root_hash_digest_to_validate;
1228
1229 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1230 if (!v) {
1231 ti->error = "Cannot allocate verity structure";
1232 return -ENOMEM;
1233 }
1234 ti->private = v;
1235 v->ti = ti;
1236
1237 r = verity_fec_ctr_alloc(v);
1238 if (r)
1239 goto bad;
1240
1241 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1242 ti->error = "Device must be readonly";
1243 r = -EINVAL;
1244 goto bad;
1245 }
1246
1247 if (argc < 10) {
1248 ti->error = "Not enough arguments";
1249 r = -EINVAL;
1250 goto bad;
1251 }
1252
1253 /* Parse optional parameters that modify primary args */
1254 if (argc > 10) {
1255 as.argc = argc - 10;
1256 as.argv = argv + 10;
1257 r = verity_parse_opt_args(&as, v, &verify_args, true);
1258 if (r < 0)
1259 goto bad;
1260 }
1261
1262 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1263 num > 1) {
1264 ti->error = "Invalid version";
1265 r = -EINVAL;
1266 goto bad;
1267 }
1268 v->version = num;
1269
1270 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1271 if (r) {
1272 ti->error = "Data device lookup failed";
1273 goto bad;
1274 }
1275
1276 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1277 if (r) {
1278 ti->error = "Hash device lookup failed";
1279 goto bad;
1280 }
1281
1282 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1283 !num || (num & (num - 1)) ||
1284 num < bdev_logical_block_size(v->data_dev->bdev) ||
1285 num > PAGE_SIZE) {
1286 ti->error = "Invalid data device block size";
1287 r = -EINVAL;
1288 goto bad;
1289 }
1290 v->data_dev_block_bits = __ffs(num);
1291
1292 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1293 !num || (num & (num - 1)) ||
1294 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1295 num > INT_MAX) {
1296 ti->error = "Invalid hash device block size";
1297 r = -EINVAL;
1298 goto bad;
1299 }
1300 v->hash_dev_block_bits = __ffs(num);
1301
1302 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1303 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1304 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1305 ti->error = "Invalid data blocks";
1306 r = -EINVAL;
1307 goto bad;
1308 }
1309 v->data_blocks = num_ll;
1310
1311 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1312 ti->error = "Data device is too small";
1313 r = -EINVAL;
1314 goto bad;
1315 }
1316
1317 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1318 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1319 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1320 ti->error = "Invalid hash start";
1321 r = -EINVAL;
1322 goto bad;
1323 }
1324 v->hash_start = num_ll;
1325
1326 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1327 if (!v->alg_name) {
1328 ti->error = "Cannot allocate algorithm name";
1329 r = -ENOMEM;
1330 goto bad;
1331 }
1332
1333 v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1334 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1335 if (IS_ERR(v->tfm)) {
1336 ti->error = "Cannot initialize hash function";
1337 r = PTR_ERR(v->tfm);
1338 v->tfm = NULL;
1339 goto bad;
1340 }
1341
1342 /*
1343 * dm-verity performance can vary greatly depending on which hash
1344 * algorithm implementation is used. Help people debug performance
1345 * problems by logging the ->cra_driver_name.
1346 */
1347 DMINFO("%s using implementation \"%s\"", v->alg_name,
1348 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1349
1350 v->digest_size = crypto_ahash_digestsize(v->tfm);
1351 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1352 ti->error = "Digest size too big";
1353 r = -EINVAL;
1354 goto bad;
1355 }
1356 v->ahash_reqsize = sizeof(struct ahash_request) +
1357 crypto_ahash_reqsize(v->tfm);
1358
1359 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1360 if (!v->root_digest) {
1361 ti->error = "Cannot allocate root digest";
1362 r = -ENOMEM;
1363 goto bad;
1364 }
1365 if (strlen(argv[8]) != v->digest_size * 2 ||
1366 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1367 ti->error = "Invalid root digest";
1368 r = -EINVAL;
1369 goto bad;
1370 }
1371 root_hash_digest_to_validate = argv[8];
1372
1373 if (strcmp(argv[9], "-")) {
1374 v->salt_size = strlen(argv[9]) / 2;
1375 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1376 if (!v->salt) {
1377 ti->error = "Cannot allocate salt";
1378 r = -ENOMEM;
1379 goto bad;
1380 }
1381 if (strlen(argv[9]) != v->salt_size * 2 ||
1382 hex2bin(v->salt, argv[9], v->salt_size)) {
1383 ti->error = "Invalid salt";
1384 r = -EINVAL;
1385 goto bad;
1386 }
1387 }
1388
1389 argv += 10;
1390 argc -= 10;
1391
1392 /* Optional parameters */
1393 if (argc) {
1394 as.argc = argc;
1395 as.argv = argv;
1396 r = verity_parse_opt_args(&as, v, &verify_args, false);
1397 if (r < 0)
1398 goto bad;
1399 }
1400
1401 /* Root hash signature is a optional parameter*/
1402 r = verity_verify_root_hash(root_hash_digest_to_validate,
1403 strlen(root_hash_digest_to_validate),
1404 verify_args.sig,
1405 verify_args.sig_size);
1406 if (r < 0) {
1407 ti->error = "Root hash verification failed";
1408 goto bad;
1409 }
1410 v->hash_per_block_bits =
1411 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1412
1413 v->levels = 0;
1414 if (v->data_blocks)
1415 while (v->hash_per_block_bits * v->levels < 64 &&
1416 (unsigned long long)(v->data_blocks - 1) >>
1417 (v->hash_per_block_bits * v->levels))
1418 v->levels++;
1419
1420 if (v->levels > DM_VERITY_MAX_LEVELS) {
1421 ti->error = "Too many tree levels";
1422 r = -E2BIG;
1423 goto bad;
1424 }
1425
1426 hash_position = v->hash_start;
1427 for (i = v->levels - 1; i >= 0; i--) {
1428 sector_t s;
1429
1430 v->hash_level_block[i] = hash_position;
1431 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1432 >> ((i + 1) * v->hash_per_block_bits);
1433 if (hash_position + s < hash_position) {
1434 ti->error = "Hash device offset overflow";
1435 r = -E2BIG;
1436 goto bad;
1437 }
1438 hash_position += s;
1439 }
1440 v->hash_blocks = hash_position;
1441
1442 r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1443 if (unlikely(r)) {
1444 ti->error = "Cannot allocate mempool";
1445 goto bad;
1446 }
1447
1448 v->io = dm_io_client_create();
1449 if (IS_ERR(v->io)) {
1450 r = PTR_ERR(v->io);
1451 v->io = NULL;
1452 ti->error = "Cannot allocate dm io";
1453 goto bad;
1454 }
1455
1456 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1457 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1458 dm_bufio_alloc_callback, NULL,
1459 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1460 if (IS_ERR(v->bufio)) {
1461 ti->error = "Cannot initialize dm-bufio";
1462 r = PTR_ERR(v->bufio);
1463 v->bufio = NULL;
1464 goto bad;
1465 }
1466
1467 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1468 ti->error = "Hash device is too small";
1469 r = -E2BIG;
1470 goto bad;
1471 }
1472
1473 /*
1474 * Using WQ_HIGHPRI improves throughput and completion latency by
1475 * reducing wait times when reading from a dm-verity device.
1476 *
1477 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1478 * allows verify_wq to preempt softirq since verification in tasklet
1479 * will fall-back to using it for error handling (or if the bufio cache
1480 * doesn't have required hashes).
1481 */
1482 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1483 if (!v->verify_wq) {
1484 ti->error = "Cannot allocate workqueue";
1485 r = -ENOMEM;
1486 goto bad;
1487 }
1488
1489 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1490 v->ahash_reqsize + v->digest_size * 2;
1491
1492 r = verity_fec_ctr(v);
1493 if (r)
1494 goto bad;
1495
1496 ti->per_io_data_size = roundup(ti->per_io_data_size,
1497 __alignof__(struct dm_verity_io));
1498
1499 verity_verify_sig_opts_cleanup(&verify_args);
1500
1501 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1502
1503 return 0;
1504
1505bad:
1506
1507 verity_verify_sig_opts_cleanup(&verify_args);
1508 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1509 verity_dtr(ti);
1510
1511 return r;
1512}
1513
1514/*
1515 * Check whether a DM target is a verity target.
1516 */
1517bool dm_is_verity_target(struct dm_target *ti)
1518{
1519 return ti->type->module == THIS_MODULE;
1520}
1521
1522/*
1523 * Get the verity mode (error behavior) of a verity target.
1524 *
1525 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1526 * target.
1527 */
1528int dm_verity_get_mode(struct dm_target *ti)
1529{
1530 struct dm_verity *v = ti->private;
1531
1532 if (!dm_is_verity_target(ti))
1533 return -EINVAL;
1534
1535 return v->mode;
1536}
1537
1538/*
1539 * Get the root digest of a verity target.
1540 *
1541 * Returns a copy of the root digest, the caller is responsible for
1542 * freeing the memory of the digest.
1543 */
1544int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1545{
1546 struct dm_verity *v = ti->private;
1547
1548 if (!dm_is_verity_target(ti))
1549 return -EINVAL;
1550
1551 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1552 if (*root_digest == NULL)
1553 return -ENOMEM;
1554
1555 *digest_size = v->digest_size;
1556
1557 return 0;
1558}
1559
1560static struct target_type verity_target = {
1561 .name = "verity",
1562 .features = DM_TARGET_IMMUTABLE,
1563 .version = {1, 10, 0},
1564 .module = THIS_MODULE,
1565 .ctr = verity_ctr,
1566 .dtr = verity_dtr,
1567 .map = verity_map,
1568 .status = verity_status,
1569 .prepare_ioctl = verity_prepare_ioctl,
1570 .iterate_devices = verity_iterate_devices,
1571 .io_hints = verity_io_hints,
1572};
1573module_dm(verity);
1574
1575MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1576MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1577MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1578MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1579MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
7 *
8 * This file is released under the GPLv2.
9 *
10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
12 * hash device. Setting this greatly improves performance when data and hash
13 * are on the same disk on different partitions on devices with poor random
14 * access behavior.
15 */
16
17#include "dm-verity.h"
18#include "dm-verity-fec.h"
19
20#include <linux/module.h>
21#include <linux/reboot.h>
22
23#define DM_MSG_PREFIX "verity"
24
25#define DM_VERITY_ENV_LENGTH 42
26#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
27
28#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
29
30#define DM_VERITY_MAX_CORRUPTED_ERRS 100
31
32#define DM_VERITY_OPT_LOGGING "ignore_corruption"
33#define DM_VERITY_OPT_RESTART "restart_on_corruption"
34#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
35
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");