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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#include <linux/security.h>
26
27#define DM_MSG_PREFIX "verity"
28
29#define DM_VERITY_ENV_LENGTH 42
30#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
31
32#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
33
34#define DM_VERITY_MAX_CORRUPTED_ERRS 100
35
36#define DM_VERITY_OPT_LOGGING "ignore_corruption"
37#define DM_VERITY_OPT_RESTART "restart_on_corruption"
38#define DM_VERITY_OPT_PANIC "panic_on_corruption"
39#define DM_VERITY_OPT_ERROR_RESTART "restart_on_error"
40#define DM_VERITY_OPT_ERROR_PANIC "panic_on_error"
41#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
42#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
43#define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
44
45#define DM_VERITY_OPTS_MAX (5 + DM_VERITY_OPTS_FEC + \
46 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
47
48static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
49
50module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
51
52static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
53
54/* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
55static DEFINE_STATIC_KEY_FALSE(ahash_enabled);
56
57struct dm_verity_prefetch_work {
58 struct work_struct work;
59 struct dm_verity *v;
60 unsigned short ioprio;
61 sector_t block;
62 unsigned int n_blocks;
63};
64
65/*
66 * Auxiliary structure appended to each dm-bufio buffer. If the value
67 * hash_verified is nonzero, hash of the block has been verified.
68 *
69 * The variable hash_verified is set to 0 when allocating the buffer, then
70 * it can be changed to 1 and it is never reset to 0 again.
71 *
72 * There is no lock around this value, a race condition can at worst cause
73 * that multiple processes verify the hash of the same buffer simultaneously
74 * and write 1 to hash_verified simultaneously.
75 * This condition is harmless, so we don't need locking.
76 */
77struct buffer_aux {
78 int hash_verified;
79};
80
81/*
82 * Initialize struct buffer_aux for a freshly created buffer.
83 */
84static void dm_bufio_alloc_callback(struct dm_buffer *buf)
85{
86 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
87
88 aux->hash_verified = 0;
89}
90
91/*
92 * Translate input sector number to the sector number on the target device.
93 */
94static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
95{
96 return dm_target_offset(v->ti, bi_sector);
97}
98
99/*
100 * Return hash position of a specified block at a specified tree level
101 * (0 is the lowest level).
102 * The lowest "hash_per_block_bits"-bits of the result denote hash position
103 * inside a hash block. The remaining bits denote location of the hash block.
104 */
105static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
106 int level)
107{
108 return block >> (level * v->hash_per_block_bits);
109}
110
111static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req,
112 const u8 *data, size_t len,
113 struct crypto_wait *wait)
114{
115 struct scatterlist sg;
116
117 if (likely(!is_vmalloc_addr(data))) {
118 sg_init_one(&sg, data, len);
119 ahash_request_set_crypt(req, &sg, NULL, len);
120 return crypto_wait_req(crypto_ahash_update(req), wait);
121 }
122
123 do {
124 int r;
125 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
126
127 flush_kernel_vmap_range((void *)data, this_step);
128 sg_init_table(&sg, 1);
129 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
130 ahash_request_set_crypt(req, &sg, NULL, this_step);
131 r = crypto_wait_req(crypto_ahash_update(req), wait);
132 if (unlikely(r))
133 return r;
134 data += this_step;
135 len -= this_step;
136 } while (len);
137
138 return 0;
139}
140
141/*
142 * Wrapper for crypto_ahash_init, which handles verity salting.
143 */
144static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req,
145 struct crypto_wait *wait, bool may_sleep)
146{
147 int r;
148
149 ahash_request_set_tfm(req, v->ahash_tfm);
150 ahash_request_set_callback(req,
151 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
152 crypto_req_done, (void *)wait);
153 crypto_init_wait(wait);
154
155 r = crypto_wait_req(crypto_ahash_init(req), wait);
156
157 if (unlikely(r < 0)) {
158 if (r != -ENOMEM)
159 DMERR("crypto_ahash_init failed: %d", r);
160 return r;
161 }
162
163 if (likely(v->salt_size && (v->version >= 1)))
164 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
165
166 return r;
167}
168
169static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req,
170 u8 *digest, struct crypto_wait *wait)
171{
172 int r;
173
174 if (unlikely(v->salt_size && (!v->version))) {
175 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
176
177 if (r < 0) {
178 DMERR("%s failed updating salt: %d", __func__, r);
179 goto out;
180 }
181 }
182
183 ahash_request_set_crypt(req, NULL, digest, 0);
184 r = crypto_wait_req(crypto_ahash_final(req), wait);
185out:
186 return r;
187}
188
189int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
190 const u8 *data, size_t len, u8 *digest, bool may_sleep)
191{
192 int r;
193
194 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) {
195 struct ahash_request *req = verity_io_hash_req(v, io);
196 struct crypto_wait wait;
197
198 r = verity_ahash_init(v, req, &wait, may_sleep) ?:
199 verity_ahash_update(v, req, data, len, &wait) ?:
200 verity_ahash_final(v, req, digest, &wait);
201 } else {
202 struct shash_desc *desc = verity_io_hash_req(v, io);
203
204 desc->tfm = v->shash_tfm;
205 r = crypto_shash_import(desc, v->initial_hashstate) ?:
206 crypto_shash_finup(desc, data, len, digest);
207 }
208 if (unlikely(r))
209 DMERR("Error hashing block: %d", r);
210 return r;
211}
212
213static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
214 sector_t *hash_block, unsigned int *offset)
215{
216 sector_t position = verity_position_at_level(v, block, level);
217 unsigned int idx;
218
219 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
220
221 if (!offset)
222 return;
223
224 idx = position & ((1 << v->hash_per_block_bits) - 1);
225 if (!v->version)
226 *offset = idx * v->digest_size;
227 else
228 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
229}
230
231/*
232 * Handle verification errors.
233 */
234static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
235 unsigned long long block)
236{
237 char verity_env[DM_VERITY_ENV_LENGTH];
238 char *envp[] = { verity_env, NULL };
239 const char *type_str = "";
240 struct mapped_device *md = dm_table_get_md(v->ti->table);
241
242 /* Corruption should be visible in device status in all modes */
243 v->hash_failed = true;
244
245 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
246 goto out;
247
248 v->corrupted_errs++;
249
250 switch (type) {
251 case DM_VERITY_BLOCK_TYPE_DATA:
252 type_str = "data";
253 break;
254 case DM_VERITY_BLOCK_TYPE_METADATA:
255 type_str = "metadata";
256 break;
257 default:
258 BUG();
259 }
260
261 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
262 type_str, block);
263
264 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
265 DMERR("%s: reached maximum errors", v->data_dev->name);
266 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
267 }
268
269 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
270 DM_VERITY_ENV_VAR_NAME, type, block);
271
272 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
273
274out:
275 if (v->mode == DM_VERITY_MODE_LOGGING)
276 return 0;
277
278 if (v->mode == DM_VERITY_MODE_RESTART)
279 kernel_restart("dm-verity device corrupted");
280
281 if (v->mode == DM_VERITY_MODE_PANIC)
282 panic("dm-verity device corrupted");
283
284 return 1;
285}
286
287/*
288 * Verify hash of a metadata block pertaining to the specified data block
289 * ("block" argument) at a specified level ("level" argument).
290 *
291 * On successful return, verity_io_want_digest(v, io) contains the hash value
292 * for a lower tree level or for the data block (if we're at the lowest level).
293 *
294 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
295 * If "skip_unverified" is false, unverified buffer is hashed and verified
296 * against current value of verity_io_want_digest(v, io).
297 */
298static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
299 sector_t block, int level, bool skip_unverified,
300 u8 *want_digest)
301{
302 struct dm_buffer *buf;
303 struct buffer_aux *aux;
304 u8 *data;
305 int r;
306 sector_t hash_block;
307 unsigned int offset;
308 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
309
310 verity_hash_at_level(v, block, level, &hash_block, &offset);
311
312 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
313 data = dm_bufio_get(v->bufio, hash_block, &buf);
314 if (data == NULL) {
315 /*
316 * In tasklet and the hash was not in the bufio cache.
317 * Return early and resume execution from a work-queue
318 * to read the hash from disk.
319 */
320 return -EAGAIN;
321 }
322 } else {
323 data = dm_bufio_read_with_ioprio(v->bufio, hash_block,
324 &buf, bio_prio(bio));
325 }
326
327 if (IS_ERR(data))
328 return PTR_ERR(data);
329
330 aux = dm_bufio_get_aux_data(buf);
331
332 if (!aux->hash_verified) {
333 if (skip_unverified) {
334 r = 1;
335 goto release_ret_r;
336 }
337
338 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits,
339 verity_io_real_digest(v, io), !io->in_bh);
340 if (unlikely(r < 0))
341 goto release_ret_r;
342
343 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
344 v->digest_size) == 0))
345 aux->hash_verified = 1;
346 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
347 /*
348 * Error handling code (FEC included) cannot be run in a
349 * tasklet since it may sleep, so fallback to work-queue.
350 */
351 r = -EAGAIN;
352 goto release_ret_r;
353 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
354 hash_block, data) == 0)
355 aux->hash_verified = 1;
356 else if (verity_handle_err(v,
357 DM_VERITY_BLOCK_TYPE_METADATA,
358 hash_block)) {
359 struct bio *bio;
360 io->had_mismatch = true;
361 bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
362 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
363 block, 0);
364 r = -EIO;
365 goto release_ret_r;
366 }
367 }
368
369 data += offset;
370 memcpy(want_digest, data, v->digest_size);
371 r = 0;
372
373release_ret_r:
374 dm_bufio_release(buf);
375 return r;
376}
377
378/*
379 * Find a hash for a given block, write it to digest and verify the integrity
380 * of the hash tree if necessary.
381 */
382int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
383 sector_t block, u8 *digest, bool *is_zero)
384{
385 int r = 0, i;
386
387 if (likely(v->levels)) {
388 /*
389 * First, we try to get the requested hash for
390 * the current block. If the hash block itself is
391 * verified, zero is returned. If it isn't, this
392 * function returns 1 and we fall back to whole
393 * chain verification.
394 */
395 r = verity_verify_level(v, io, block, 0, true, digest);
396 if (likely(r <= 0))
397 goto out;
398 }
399
400 memcpy(digest, v->root_digest, v->digest_size);
401
402 for (i = v->levels - 1; i >= 0; i--) {
403 r = verity_verify_level(v, io, block, i, false, digest);
404 if (unlikely(r))
405 goto out;
406 }
407out:
408 if (!r && v->zero_digest)
409 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
410 else
411 *is_zero = false;
412
413 return r;
414}
415
416static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
417 sector_t cur_block, u8 *dest)
418{
419 struct page *page;
420 void *buffer;
421 int r;
422 struct dm_io_request io_req;
423 struct dm_io_region io_loc;
424
425 page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
426 buffer = page_to_virt(page);
427
428 io_req.bi_opf = REQ_OP_READ;
429 io_req.mem.type = DM_IO_KMEM;
430 io_req.mem.ptr.addr = buffer;
431 io_req.notify.fn = NULL;
432 io_req.client = v->io;
433 io_loc.bdev = v->data_dev->bdev;
434 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
435 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
436 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
437 if (unlikely(r))
438 goto free_ret;
439
440 r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
441 verity_io_real_digest(v, io), true);
442 if (unlikely(r))
443 goto free_ret;
444
445 if (memcmp(verity_io_real_digest(v, io),
446 verity_io_want_digest(v, io), v->digest_size)) {
447 r = -EIO;
448 goto free_ret;
449 }
450
451 memcpy(dest, buffer, 1 << v->data_dev_block_bits);
452 r = 0;
453free_ret:
454 mempool_free(page, &v->recheck_pool);
455
456 return r;
457}
458
459static int verity_handle_data_hash_mismatch(struct dm_verity *v,
460 struct dm_verity_io *io,
461 struct bio *bio, sector_t blkno,
462 u8 *data)
463{
464 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
465 /*
466 * Error handling code (FEC included) cannot be run in the
467 * BH workqueue, so fallback to a standard workqueue.
468 */
469 return -EAGAIN;
470 }
471 if (verity_recheck(v, io, blkno, data) == 0) {
472 if (v->validated_blocks)
473 set_bit(blkno, v->validated_blocks);
474 return 0;
475 }
476#if defined(CONFIG_DM_VERITY_FEC)
477 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno,
478 data) == 0)
479 return 0;
480#endif
481 if (bio->bi_status)
482 return -EIO; /* Error correction failed; Just return error */
483
484 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
485 io->had_mismatch = true;
486 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
487 return -EIO;
488 }
489 return 0;
490}
491
492/*
493 * Verify one "dm_verity_io" structure.
494 */
495static int verity_verify_io(struct dm_verity_io *io)
496{
497 struct dm_verity *v = io->v;
498 const unsigned int block_size = 1 << v->data_dev_block_bits;
499 struct bvec_iter iter_copy;
500 struct bvec_iter *iter;
501 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
502 unsigned int b;
503
504 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
505 /*
506 * Copy the iterator in case we need to restart
507 * verification in a work-queue.
508 */
509 iter_copy = io->iter;
510 iter = &iter_copy;
511 } else
512 iter = &io->iter;
513
514 for (b = 0; b < io->n_blocks;
515 b++, bio_advance_iter(bio, iter, block_size)) {
516 int r;
517 sector_t cur_block = io->block + b;
518 bool is_zero;
519 struct bio_vec bv;
520 void *data;
521
522 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
523 likely(test_bit(cur_block, v->validated_blocks)))
524 continue;
525
526 r = verity_hash_for_block(v, io, cur_block,
527 verity_io_want_digest(v, io),
528 &is_zero);
529 if (unlikely(r < 0))
530 return r;
531
532 bv = bio_iter_iovec(bio, *iter);
533 if (unlikely(bv.bv_len < block_size)) {
534 /*
535 * Data block spans pages. This should not happen,
536 * since dm-verity sets dma_alignment to the data block
537 * size minus 1, and dm-verity also doesn't allow the
538 * data block size to be greater than PAGE_SIZE.
539 */
540 DMERR_LIMIT("unaligned io (data block spans pages)");
541 return -EIO;
542 }
543
544 data = bvec_kmap_local(&bv);
545
546 if (is_zero) {
547 /*
548 * If we expect a zero block, don't validate, just
549 * return zeros.
550 */
551 memset(data, 0, block_size);
552 kunmap_local(data);
553 continue;
554 }
555
556 r = verity_hash(v, io, data, block_size,
557 verity_io_real_digest(v, io), !io->in_bh);
558 if (unlikely(r < 0)) {
559 kunmap_local(data);
560 return r;
561 }
562
563 if (likely(memcmp(verity_io_real_digest(v, io),
564 verity_io_want_digest(v, io), v->digest_size) == 0)) {
565 if (v->validated_blocks)
566 set_bit(cur_block, v->validated_blocks);
567 kunmap_local(data);
568 continue;
569 }
570 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block,
571 data);
572 kunmap_local(data);
573 if (unlikely(r))
574 return r;
575 }
576
577 return 0;
578}
579
580/*
581 * Skip verity work in response to I/O error when system is shutting down.
582 */
583static inline bool verity_is_system_shutting_down(void)
584{
585 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
586 || system_state == SYSTEM_RESTART;
587}
588
589static void restart_io_error(struct work_struct *w)
590{
591 kernel_restart("dm-verity device has I/O error");
592}
593
594/*
595 * End one "io" structure with a given error.
596 */
597static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
598{
599 struct dm_verity *v = io->v;
600 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
601
602 bio->bi_end_io = io->orig_bi_end_io;
603 bio->bi_status = status;
604
605 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
606 verity_fec_finish_io(io);
607
608 if (unlikely(status != BLK_STS_OK) &&
609 unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
610 !io->had_mismatch &&
611 !verity_is_system_shutting_down()) {
612 if (v->error_mode == DM_VERITY_MODE_PANIC) {
613 panic("dm-verity device has I/O error");
614 }
615 if (v->error_mode == DM_VERITY_MODE_RESTART) {
616 static DECLARE_WORK(restart_work, restart_io_error);
617 queue_work(v->verify_wq, &restart_work);
618 /*
619 * We deliberately don't call bio_endio here, because
620 * the machine will be restarted anyway.
621 */
622 return;
623 }
624 }
625
626 bio_endio(bio);
627}
628
629static void verity_work(struct work_struct *w)
630{
631 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
632
633 io->in_bh = false;
634
635 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
636}
637
638static void verity_bh_work(struct work_struct *w)
639{
640 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
641 int err;
642
643 io->in_bh = true;
644 err = verity_verify_io(io);
645 if (err == -EAGAIN || err == -ENOMEM) {
646 /* fallback to retrying with work-queue */
647 INIT_WORK(&io->work, verity_work);
648 queue_work(io->v->verify_wq, &io->work);
649 return;
650 }
651
652 verity_finish_io(io, errno_to_blk_status(err));
653}
654
655static void verity_end_io(struct bio *bio)
656{
657 struct dm_verity_io *io = bio->bi_private;
658
659 if (bio->bi_status &&
660 (!verity_fec_is_enabled(io->v) ||
661 verity_is_system_shutting_down() ||
662 (bio->bi_opf & REQ_RAHEAD))) {
663 verity_finish_io(io, bio->bi_status);
664 return;
665 }
666
667 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) {
668 INIT_WORK(&io->bh_work, verity_bh_work);
669 queue_work(system_bh_wq, &io->bh_work);
670 } else {
671 INIT_WORK(&io->work, verity_work);
672 queue_work(io->v->verify_wq, &io->work);
673 }
674}
675
676/*
677 * Prefetch buffers for the specified io.
678 * The root buffer is not prefetched, it is assumed that it will be cached
679 * all the time.
680 */
681static void verity_prefetch_io(struct work_struct *work)
682{
683 struct dm_verity_prefetch_work *pw =
684 container_of(work, struct dm_verity_prefetch_work, work);
685 struct dm_verity *v = pw->v;
686 int i;
687
688 for (i = v->levels - 2; i >= 0; i--) {
689 sector_t hash_block_start;
690 sector_t hash_block_end;
691
692 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
693 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
694
695 if (!i) {
696 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
697
698 cluster >>= v->data_dev_block_bits;
699 if (unlikely(!cluster))
700 goto no_prefetch_cluster;
701
702 if (unlikely(cluster & (cluster - 1)))
703 cluster = 1 << __fls(cluster);
704
705 hash_block_start &= ~(sector_t)(cluster - 1);
706 hash_block_end |= cluster - 1;
707 if (unlikely(hash_block_end >= v->hash_blocks))
708 hash_block_end = v->hash_blocks - 1;
709 }
710no_prefetch_cluster:
711 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start,
712 hash_block_end - hash_block_start + 1,
713 pw->ioprio);
714 }
715
716 kfree(pw);
717}
718
719static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
720 unsigned short ioprio)
721{
722 sector_t block = io->block;
723 unsigned int n_blocks = io->n_blocks;
724 struct dm_verity_prefetch_work *pw;
725
726 if (v->validated_blocks) {
727 while (n_blocks && test_bit(block, v->validated_blocks)) {
728 block++;
729 n_blocks--;
730 }
731 while (n_blocks && test_bit(block + n_blocks - 1,
732 v->validated_blocks))
733 n_blocks--;
734 if (!n_blocks)
735 return;
736 }
737
738 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
739 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
740
741 if (!pw)
742 return;
743
744 INIT_WORK(&pw->work, verity_prefetch_io);
745 pw->v = v;
746 pw->block = block;
747 pw->n_blocks = n_blocks;
748 pw->ioprio = ioprio;
749 queue_work(v->verify_wq, &pw->work);
750}
751
752/*
753 * Bio map function. It allocates dm_verity_io structure and bio vector and
754 * fills them. Then it issues prefetches and the I/O.
755 */
756static int verity_map(struct dm_target *ti, struct bio *bio)
757{
758 struct dm_verity *v = ti->private;
759 struct dm_verity_io *io;
760
761 bio_set_dev(bio, v->data_dev->bdev);
762 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
763
764 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
765 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
766 DMERR_LIMIT("unaligned io");
767 return DM_MAPIO_KILL;
768 }
769
770 if (bio_end_sector(bio) >>
771 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
772 DMERR_LIMIT("io out of range");
773 return DM_MAPIO_KILL;
774 }
775
776 if (bio_data_dir(bio) == WRITE)
777 return DM_MAPIO_KILL;
778
779 io = dm_per_bio_data(bio, ti->per_io_data_size);
780 io->v = v;
781 io->orig_bi_end_io = bio->bi_end_io;
782 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
783 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
784 io->had_mismatch = false;
785
786 bio->bi_end_io = verity_end_io;
787 bio->bi_private = io;
788 io->iter = bio->bi_iter;
789
790 verity_fec_init_io(io);
791
792 verity_submit_prefetch(v, io, bio_prio(bio));
793
794 submit_bio_noacct(bio);
795
796 return DM_MAPIO_SUBMITTED;
797}
798
799/*
800 * Status: V (valid) or C (corruption found)
801 */
802static void verity_status(struct dm_target *ti, status_type_t type,
803 unsigned int status_flags, char *result, unsigned int maxlen)
804{
805 struct dm_verity *v = ti->private;
806 unsigned int args = 0;
807 unsigned int sz = 0;
808 unsigned int x;
809
810 switch (type) {
811 case STATUSTYPE_INFO:
812 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
813 break;
814 case STATUSTYPE_TABLE:
815 DMEMIT("%u %s %s %u %u %llu %llu %s ",
816 v->version,
817 v->data_dev->name,
818 v->hash_dev->name,
819 1 << v->data_dev_block_bits,
820 1 << v->hash_dev_block_bits,
821 (unsigned long long)v->data_blocks,
822 (unsigned long long)v->hash_start,
823 v->alg_name
824 );
825 for (x = 0; x < v->digest_size; x++)
826 DMEMIT("%02x", v->root_digest[x]);
827 DMEMIT(" ");
828 if (!v->salt_size)
829 DMEMIT("-");
830 else
831 for (x = 0; x < v->salt_size; x++)
832 DMEMIT("%02x", v->salt[x]);
833 if (v->mode != DM_VERITY_MODE_EIO)
834 args++;
835 if (v->error_mode != DM_VERITY_MODE_EIO)
836 args++;
837 if (verity_fec_is_enabled(v))
838 args += DM_VERITY_OPTS_FEC;
839 if (v->zero_digest)
840 args++;
841 if (v->validated_blocks)
842 args++;
843 if (v->use_bh_wq)
844 args++;
845 if (v->signature_key_desc)
846 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
847 if (!args)
848 return;
849 DMEMIT(" %u", args);
850 if (v->mode != DM_VERITY_MODE_EIO) {
851 DMEMIT(" ");
852 switch (v->mode) {
853 case DM_VERITY_MODE_LOGGING:
854 DMEMIT(DM_VERITY_OPT_LOGGING);
855 break;
856 case DM_VERITY_MODE_RESTART:
857 DMEMIT(DM_VERITY_OPT_RESTART);
858 break;
859 case DM_VERITY_MODE_PANIC:
860 DMEMIT(DM_VERITY_OPT_PANIC);
861 break;
862 default:
863 BUG();
864 }
865 }
866 if (v->error_mode != DM_VERITY_MODE_EIO) {
867 DMEMIT(" ");
868 switch (v->error_mode) {
869 case DM_VERITY_MODE_RESTART:
870 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
871 break;
872 case DM_VERITY_MODE_PANIC:
873 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
874 break;
875 default:
876 BUG();
877 }
878 }
879 if (v->zero_digest)
880 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
881 if (v->validated_blocks)
882 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
883 if (v->use_bh_wq)
884 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
885 sz = verity_fec_status_table(v, sz, result, maxlen);
886 if (v->signature_key_desc)
887 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
888 " %s", v->signature_key_desc);
889 break;
890
891 case STATUSTYPE_IMA:
892 DMEMIT_TARGET_NAME_VERSION(ti->type);
893 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
894 DMEMIT(",verity_version=%u", v->version);
895 DMEMIT(",data_device_name=%s", v->data_dev->name);
896 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
897 DMEMIT(",verity_algorithm=%s", v->alg_name);
898
899 DMEMIT(",root_digest=");
900 for (x = 0; x < v->digest_size; x++)
901 DMEMIT("%02x", v->root_digest[x]);
902
903 DMEMIT(",salt=");
904 if (!v->salt_size)
905 DMEMIT("-");
906 else
907 for (x = 0; x < v->salt_size; x++)
908 DMEMIT("%02x", v->salt[x]);
909
910 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
911 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
912 if (v->signature_key_desc)
913 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
914
915 if (v->mode != DM_VERITY_MODE_EIO) {
916 DMEMIT(",verity_mode=");
917 switch (v->mode) {
918 case DM_VERITY_MODE_LOGGING:
919 DMEMIT(DM_VERITY_OPT_LOGGING);
920 break;
921 case DM_VERITY_MODE_RESTART:
922 DMEMIT(DM_VERITY_OPT_RESTART);
923 break;
924 case DM_VERITY_MODE_PANIC:
925 DMEMIT(DM_VERITY_OPT_PANIC);
926 break;
927 default:
928 DMEMIT("invalid");
929 }
930 }
931 if (v->error_mode != DM_VERITY_MODE_EIO) {
932 DMEMIT(",verity_error_mode=");
933 switch (v->error_mode) {
934 case DM_VERITY_MODE_RESTART:
935 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
936 break;
937 case DM_VERITY_MODE_PANIC:
938 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
939 break;
940 default:
941 DMEMIT("invalid");
942 }
943 }
944 DMEMIT(";");
945 break;
946 }
947}
948
949static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
950{
951 struct dm_verity *v = ti->private;
952
953 *bdev = v->data_dev->bdev;
954
955 if (ti->len != bdev_nr_sectors(v->data_dev->bdev))
956 return 1;
957 return 0;
958}
959
960static int verity_iterate_devices(struct dm_target *ti,
961 iterate_devices_callout_fn fn, void *data)
962{
963 struct dm_verity *v = ti->private;
964
965 return fn(ti, v->data_dev, 0, ti->len, data);
966}
967
968static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
969{
970 struct dm_verity *v = ti->private;
971
972 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
973 limits->logical_block_size = 1 << v->data_dev_block_bits;
974
975 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
976 limits->physical_block_size = 1 << v->data_dev_block_bits;
977
978 limits->io_min = limits->logical_block_size;
979
980 /*
981 * Similar to what dm-crypt does, opt dm-verity out of support for
982 * direct I/O that is aligned to less than the traditional direct I/O
983 * alignment requirement of logical_block_size. This prevents dm-verity
984 * data blocks from crossing pages, eliminating various edge cases.
985 */
986 limits->dma_alignment = limits->logical_block_size - 1;
987}
988
989#ifdef CONFIG_SECURITY
990
991static int verity_init_sig(struct dm_verity *v, const void *sig,
992 size_t sig_size)
993{
994 v->sig_size = sig_size;
995
996 if (sig) {
997 v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL);
998 if (!v->root_digest_sig)
999 return -ENOMEM;
1000 }
1001
1002 return 0;
1003}
1004
1005static void verity_free_sig(struct dm_verity *v)
1006{
1007 kfree(v->root_digest_sig);
1008}
1009
1010#else
1011
1012static inline int verity_init_sig(struct dm_verity *v, const void *sig,
1013 size_t sig_size)
1014{
1015 return 0;
1016}
1017
1018static inline void verity_free_sig(struct dm_verity *v)
1019{
1020}
1021
1022#endif /* CONFIG_SECURITY */
1023
1024static void verity_dtr(struct dm_target *ti)
1025{
1026 struct dm_verity *v = ti->private;
1027
1028 if (v->verify_wq)
1029 destroy_workqueue(v->verify_wq);
1030
1031 mempool_exit(&v->recheck_pool);
1032 if (v->io)
1033 dm_io_client_destroy(v->io);
1034
1035 if (v->bufio)
1036 dm_bufio_client_destroy(v->bufio);
1037
1038 kvfree(v->validated_blocks);
1039 kfree(v->salt);
1040 kfree(v->initial_hashstate);
1041 kfree(v->root_digest);
1042 kfree(v->zero_digest);
1043 verity_free_sig(v);
1044
1045 if (v->ahash_tfm) {
1046 static_branch_dec(&ahash_enabled);
1047 crypto_free_ahash(v->ahash_tfm);
1048 } else {
1049 crypto_free_shash(v->shash_tfm);
1050 }
1051
1052 kfree(v->alg_name);
1053
1054 if (v->hash_dev)
1055 dm_put_device(ti, v->hash_dev);
1056
1057 if (v->data_dev)
1058 dm_put_device(ti, v->data_dev);
1059
1060 verity_fec_dtr(v);
1061
1062 kfree(v->signature_key_desc);
1063
1064 if (v->use_bh_wq)
1065 static_branch_dec(&use_bh_wq_enabled);
1066
1067 kfree(v);
1068
1069 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1070}
1071
1072static int verity_alloc_most_once(struct dm_verity *v)
1073{
1074 struct dm_target *ti = v->ti;
1075
1076 /* the bitset can only handle INT_MAX blocks */
1077 if (v->data_blocks > INT_MAX) {
1078 ti->error = "device too large to use check_at_most_once";
1079 return -E2BIG;
1080 }
1081
1082 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1083 sizeof(unsigned long),
1084 GFP_KERNEL);
1085 if (!v->validated_blocks) {
1086 ti->error = "failed to allocate bitset for check_at_most_once";
1087 return -ENOMEM;
1088 }
1089
1090 return 0;
1091}
1092
1093static int verity_alloc_zero_digest(struct dm_verity *v)
1094{
1095 int r = -ENOMEM;
1096 struct dm_verity_io *io;
1097 u8 *zero_data;
1098
1099 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1100
1101 if (!v->zero_digest)
1102 return r;
1103
1104 io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL);
1105
1106 if (!io)
1107 return r; /* verity_dtr will free zero_digest */
1108
1109 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1110
1111 if (!zero_data)
1112 goto out;
1113
1114 r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits,
1115 v->zero_digest, true);
1116
1117out:
1118 kfree(io);
1119 kfree(zero_data);
1120
1121 return r;
1122}
1123
1124static inline bool verity_is_verity_mode(const char *arg_name)
1125{
1126 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1127 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1128 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1129}
1130
1131static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1132{
1133 if (v->mode)
1134 return -EINVAL;
1135
1136 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1137 v->mode = DM_VERITY_MODE_LOGGING;
1138 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1139 v->mode = DM_VERITY_MODE_RESTART;
1140 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1141 v->mode = DM_VERITY_MODE_PANIC;
1142
1143 return 0;
1144}
1145
1146static inline bool verity_is_verity_error_mode(const char *arg_name)
1147{
1148 return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) ||
1149 !strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC));
1150}
1151
1152static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name)
1153{
1154 if (v->error_mode)
1155 return -EINVAL;
1156
1157 if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART))
1158 v->error_mode = DM_VERITY_MODE_RESTART;
1159 else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC))
1160 v->error_mode = DM_VERITY_MODE_PANIC;
1161
1162 return 0;
1163}
1164
1165static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1166 struct dm_verity_sig_opts *verify_args,
1167 bool only_modifier_opts)
1168{
1169 int r = 0;
1170 unsigned int argc;
1171 struct dm_target *ti = v->ti;
1172 const char *arg_name;
1173
1174 static const struct dm_arg _args[] = {
1175 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1176 };
1177
1178 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1179 if (r)
1180 return -EINVAL;
1181
1182 if (!argc)
1183 return 0;
1184
1185 do {
1186 arg_name = dm_shift_arg(as);
1187 argc--;
1188
1189 if (verity_is_verity_mode(arg_name)) {
1190 if (only_modifier_opts)
1191 continue;
1192 r = verity_parse_verity_mode(v, arg_name);
1193 if (r) {
1194 ti->error = "Conflicting error handling parameters";
1195 return r;
1196 }
1197 continue;
1198
1199 } else if (verity_is_verity_error_mode(arg_name)) {
1200 if (only_modifier_opts)
1201 continue;
1202 r = verity_parse_verity_error_mode(v, arg_name);
1203 if (r) {
1204 ti->error = "Conflicting error handling parameters";
1205 return r;
1206 }
1207 continue;
1208
1209 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1210 if (only_modifier_opts)
1211 continue;
1212 r = verity_alloc_zero_digest(v);
1213 if (r) {
1214 ti->error = "Cannot allocate zero digest";
1215 return r;
1216 }
1217 continue;
1218
1219 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1220 if (only_modifier_opts)
1221 continue;
1222 r = verity_alloc_most_once(v);
1223 if (r)
1224 return r;
1225 continue;
1226
1227 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1228 v->use_bh_wq = true;
1229 static_branch_inc(&use_bh_wq_enabled);
1230 continue;
1231
1232 } else if (verity_is_fec_opt_arg(arg_name)) {
1233 if (only_modifier_opts)
1234 continue;
1235 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1236 if (r)
1237 return r;
1238 continue;
1239
1240 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1241 if (only_modifier_opts)
1242 continue;
1243 r = verity_verify_sig_parse_opt_args(as, v,
1244 verify_args,
1245 &argc, arg_name);
1246 if (r)
1247 return r;
1248 continue;
1249
1250 } else if (only_modifier_opts) {
1251 /*
1252 * Ignore unrecognized opt, could easily be an extra
1253 * argument to an option whose parsing was skipped.
1254 * Normal parsing (@only_modifier_opts=false) will
1255 * properly parse all options (and their extra args).
1256 */
1257 continue;
1258 }
1259
1260 DMERR("Unrecognized verity feature request: %s", arg_name);
1261 ti->error = "Unrecognized verity feature request";
1262 return -EINVAL;
1263 } while (argc && !r);
1264
1265 return r;
1266}
1267
1268static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name)
1269{
1270 struct dm_target *ti = v->ti;
1271 struct crypto_ahash *ahash;
1272 struct crypto_shash *shash = NULL;
1273 const char *driver_name;
1274
1275 v->alg_name = kstrdup(alg_name, GFP_KERNEL);
1276 if (!v->alg_name) {
1277 ti->error = "Cannot allocate algorithm name";
1278 return -ENOMEM;
1279 }
1280
1281 /*
1282 * Allocate the hash transformation object that this dm-verity instance
1283 * will use. The vast majority of dm-verity users use CPU-based
1284 * hashing, so when possible use the shash API to minimize the crypto
1285 * API overhead. If the ahash API resolves to a different driver
1286 * (likely an off-CPU hardware offload), use ahash instead. Also use
1287 * ahash if the obsolete dm-verity format with the appended salt is
1288 * being used, so that quirk only needs to be handled in one place.
1289 */
1290 ahash = crypto_alloc_ahash(alg_name, 0,
1291 v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
1292 if (IS_ERR(ahash)) {
1293 ti->error = "Cannot initialize hash function";
1294 return PTR_ERR(ahash);
1295 }
1296 driver_name = crypto_ahash_driver_name(ahash);
1297 if (v->version >= 1 /* salt prepended, not appended? */) {
1298 shash = crypto_alloc_shash(alg_name, 0, 0);
1299 if (!IS_ERR(shash) &&
1300 strcmp(crypto_shash_driver_name(shash), driver_name) != 0) {
1301 /*
1302 * ahash gave a different driver than shash, so probably
1303 * this is a case of real hardware offload. Use ahash.
1304 */
1305 crypto_free_shash(shash);
1306 shash = NULL;
1307 }
1308 }
1309 if (!IS_ERR_OR_NULL(shash)) {
1310 crypto_free_ahash(ahash);
1311 ahash = NULL;
1312 v->shash_tfm = shash;
1313 v->digest_size = crypto_shash_digestsize(shash);
1314 v->hash_reqsize = sizeof(struct shash_desc) +
1315 crypto_shash_descsize(shash);
1316 DMINFO("%s using shash \"%s\"", alg_name, driver_name);
1317 } else {
1318 v->ahash_tfm = ahash;
1319 static_branch_inc(&ahash_enabled);
1320 v->digest_size = crypto_ahash_digestsize(ahash);
1321 v->hash_reqsize = sizeof(struct ahash_request) +
1322 crypto_ahash_reqsize(ahash);
1323 DMINFO("%s using ahash \"%s\"", alg_name, driver_name);
1324 }
1325 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1326 ti->error = "Digest size too big";
1327 return -EINVAL;
1328 }
1329 return 0;
1330}
1331
1332static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg)
1333{
1334 struct dm_target *ti = v->ti;
1335
1336 if (strcmp(arg, "-") != 0) {
1337 v->salt_size = strlen(arg) / 2;
1338 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1339 if (!v->salt) {
1340 ti->error = "Cannot allocate salt";
1341 return -ENOMEM;
1342 }
1343 if (strlen(arg) != v->salt_size * 2 ||
1344 hex2bin(v->salt, arg, v->salt_size)) {
1345 ti->error = "Invalid salt";
1346 return -EINVAL;
1347 }
1348 }
1349 if (v->shash_tfm) {
1350 SHASH_DESC_ON_STACK(desc, v->shash_tfm);
1351 int r;
1352
1353 /*
1354 * Compute the pre-salted hash state that can be passed to
1355 * crypto_shash_import() for each block later.
1356 */
1357 v->initial_hashstate = kmalloc(
1358 crypto_shash_statesize(v->shash_tfm), GFP_KERNEL);
1359 if (!v->initial_hashstate) {
1360 ti->error = "Cannot allocate initial hash state";
1361 return -ENOMEM;
1362 }
1363 desc->tfm = v->shash_tfm;
1364 r = crypto_shash_init(desc) ?:
1365 crypto_shash_update(desc, v->salt, v->salt_size) ?:
1366 crypto_shash_export(desc, v->initial_hashstate);
1367 if (r) {
1368 ti->error = "Cannot set up initial hash state";
1369 return r;
1370 }
1371 }
1372 return 0;
1373}
1374
1375/*
1376 * Target parameters:
1377 * <version> The current format is version 1.
1378 * Vsn 0 is compatible with original Chromium OS releases.
1379 * <data device>
1380 * <hash device>
1381 * <data block size>
1382 * <hash block size>
1383 * <the number of data blocks>
1384 * <hash start block>
1385 * <algorithm>
1386 * <digest>
1387 * <salt> Hex string or "-" if no salt.
1388 */
1389static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1390{
1391 struct dm_verity *v;
1392 struct dm_verity_sig_opts verify_args = {0};
1393 struct dm_arg_set as;
1394 unsigned int num;
1395 unsigned long long num_ll;
1396 int r;
1397 int i;
1398 sector_t hash_position;
1399 char dummy;
1400 char *root_hash_digest_to_validate;
1401
1402 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1403 if (!v) {
1404 ti->error = "Cannot allocate verity structure";
1405 return -ENOMEM;
1406 }
1407 ti->private = v;
1408 v->ti = ti;
1409
1410 r = verity_fec_ctr_alloc(v);
1411 if (r)
1412 goto bad;
1413
1414 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1415 ti->error = "Device must be readonly";
1416 r = -EINVAL;
1417 goto bad;
1418 }
1419
1420 if (argc < 10) {
1421 ti->error = "Not enough arguments";
1422 r = -EINVAL;
1423 goto bad;
1424 }
1425
1426 /* Parse optional parameters that modify primary args */
1427 if (argc > 10) {
1428 as.argc = argc - 10;
1429 as.argv = argv + 10;
1430 r = verity_parse_opt_args(&as, v, &verify_args, true);
1431 if (r < 0)
1432 goto bad;
1433 }
1434
1435 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1436 num > 1) {
1437 ti->error = "Invalid version";
1438 r = -EINVAL;
1439 goto bad;
1440 }
1441 v->version = num;
1442
1443 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1444 if (r) {
1445 ti->error = "Data device lookup failed";
1446 goto bad;
1447 }
1448
1449 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1450 if (r) {
1451 ti->error = "Hash device lookup failed";
1452 goto bad;
1453 }
1454
1455 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1456 !num || (num & (num - 1)) ||
1457 num < bdev_logical_block_size(v->data_dev->bdev) ||
1458 num > PAGE_SIZE) {
1459 ti->error = "Invalid data device block size";
1460 r = -EINVAL;
1461 goto bad;
1462 }
1463 v->data_dev_block_bits = __ffs(num);
1464
1465 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1466 !num || (num & (num - 1)) ||
1467 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1468 num > INT_MAX) {
1469 ti->error = "Invalid hash device block size";
1470 r = -EINVAL;
1471 goto bad;
1472 }
1473 v->hash_dev_block_bits = __ffs(num);
1474
1475 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1476 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1477 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1478 ti->error = "Invalid data blocks";
1479 r = -EINVAL;
1480 goto bad;
1481 }
1482 v->data_blocks = num_ll;
1483
1484 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1485 ti->error = "Data device is too small";
1486 r = -EINVAL;
1487 goto bad;
1488 }
1489
1490 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1491 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1492 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1493 ti->error = "Invalid hash start";
1494 r = -EINVAL;
1495 goto bad;
1496 }
1497 v->hash_start = num_ll;
1498
1499 r = verity_setup_hash_alg(v, argv[7]);
1500 if (r)
1501 goto bad;
1502
1503 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1504 if (!v->root_digest) {
1505 ti->error = "Cannot allocate root digest";
1506 r = -ENOMEM;
1507 goto bad;
1508 }
1509 if (strlen(argv[8]) != v->digest_size * 2 ||
1510 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1511 ti->error = "Invalid root digest";
1512 r = -EINVAL;
1513 goto bad;
1514 }
1515 root_hash_digest_to_validate = argv[8];
1516
1517 r = verity_setup_salt_and_hashstate(v, argv[9]);
1518 if (r)
1519 goto bad;
1520
1521 argv += 10;
1522 argc -= 10;
1523
1524 /* Optional parameters */
1525 if (argc) {
1526 as.argc = argc;
1527 as.argv = argv;
1528 r = verity_parse_opt_args(&as, v, &verify_args, false);
1529 if (r < 0)
1530 goto bad;
1531 }
1532
1533 /* Root hash signature is a optional parameter*/
1534 r = verity_verify_root_hash(root_hash_digest_to_validate,
1535 strlen(root_hash_digest_to_validate),
1536 verify_args.sig,
1537 verify_args.sig_size);
1538 if (r < 0) {
1539 ti->error = "Root hash verification failed";
1540 goto bad;
1541 }
1542
1543 r = verity_init_sig(v, verify_args.sig, verify_args.sig_size);
1544 if (r < 0) {
1545 ti->error = "Cannot allocate root digest signature";
1546 goto bad;
1547 }
1548
1549 v->hash_per_block_bits =
1550 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1551
1552 v->levels = 0;
1553 if (v->data_blocks)
1554 while (v->hash_per_block_bits * v->levels < 64 &&
1555 (unsigned long long)(v->data_blocks - 1) >>
1556 (v->hash_per_block_bits * v->levels))
1557 v->levels++;
1558
1559 if (v->levels > DM_VERITY_MAX_LEVELS) {
1560 ti->error = "Too many tree levels";
1561 r = -E2BIG;
1562 goto bad;
1563 }
1564
1565 hash_position = v->hash_start;
1566 for (i = v->levels - 1; i >= 0; i--) {
1567 sector_t s;
1568
1569 v->hash_level_block[i] = hash_position;
1570 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1571 >> ((i + 1) * v->hash_per_block_bits);
1572 if (hash_position + s < hash_position) {
1573 ti->error = "Hash device offset overflow";
1574 r = -E2BIG;
1575 goto bad;
1576 }
1577 hash_position += s;
1578 }
1579 v->hash_blocks = hash_position;
1580
1581 r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1582 if (unlikely(r)) {
1583 ti->error = "Cannot allocate mempool";
1584 goto bad;
1585 }
1586
1587 v->io = dm_io_client_create();
1588 if (IS_ERR(v->io)) {
1589 r = PTR_ERR(v->io);
1590 v->io = NULL;
1591 ti->error = "Cannot allocate dm io";
1592 goto bad;
1593 }
1594
1595 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1596 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1597 dm_bufio_alloc_callback, NULL,
1598 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1599 if (IS_ERR(v->bufio)) {
1600 ti->error = "Cannot initialize dm-bufio";
1601 r = PTR_ERR(v->bufio);
1602 v->bufio = NULL;
1603 goto bad;
1604 }
1605
1606 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1607 ti->error = "Hash device is too small";
1608 r = -E2BIG;
1609 goto bad;
1610 }
1611
1612 /*
1613 * Using WQ_HIGHPRI improves throughput and completion latency by
1614 * reducing wait times when reading from a dm-verity device.
1615 *
1616 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1617 * allows verify_wq to preempt softirq since verification in BH workqueue
1618 * will fall-back to using it for error handling (or if the bufio cache
1619 * doesn't have required hashes).
1620 */
1621 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1622 if (!v->verify_wq) {
1623 ti->error = "Cannot allocate workqueue";
1624 r = -ENOMEM;
1625 goto bad;
1626 }
1627
1628 ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize;
1629
1630 r = verity_fec_ctr(v);
1631 if (r)
1632 goto bad;
1633
1634 ti->per_io_data_size = roundup(ti->per_io_data_size,
1635 __alignof__(struct dm_verity_io));
1636
1637 verity_verify_sig_opts_cleanup(&verify_args);
1638
1639 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1640
1641 return 0;
1642
1643bad:
1644
1645 verity_verify_sig_opts_cleanup(&verify_args);
1646 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1647 verity_dtr(ti);
1648
1649 return r;
1650}
1651
1652/*
1653 * Get the verity mode (error behavior) of a verity target.
1654 *
1655 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1656 * target.
1657 */
1658int dm_verity_get_mode(struct dm_target *ti)
1659{
1660 struct dm_verity *v = ti->private;
1661
1662 if (!dm_is_verity_target(ti))
1663 return -EINVAL;
1664
1665 return v->mode;
1666}
1667
1668/*
1669 * Get the root digest of a verity target.
1670 *
1671 * Returns a copy of the root digest, the caller is responsible for
1672 * freeing the memory of the digest.
1673 */
1674int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1675{
1676 struct dm_verity *v = ti->private;
1677
1678 if (!dm_is_verity_target(ti))
1679 return -EINVAL;
1680
1681 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1682 if (*root_digest == NULL)
1683 return -ENOMEM;
1684
1685 *digest_size = v->digest_size;
1686
1687 return 0;
1688}
1689
1690#ifdef CONFIG_SECURITY
1691
1692#ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG
1693
1694static int verity_security_set_signature(struct block_device *bdev,
1695 struct dm_verity *v)
1696{
1697 /*
1698 * if the dm-verity target is unsigned, v->root_digest_sig will
1699 * be NULL, and the hook call is still required to let LSMs mark
1700 * the device as unsigned. This information is crucial for LSMs to
1701 * block operations such as execution on unsigned files
1702 */
1703 return security_bdev_setintegrity(bdev,
1704 LSM_INT_DMVERITY_SIG_VALID,
1705 v->root_digest_sig,
1706 v->sig_size);
1707}
1708
1709#else
1710
1711static inline int verity_security_set_signature(struct block_device *bdev,
1712 struct dm_verity *v)
1713{
1714 return 0;
1715}
1716
1717#endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */
1718
1719/*
1720 * Expose verity target's root hash and signature data to LSMs before resume.
1721 *
1722 * Returns 0 on success, or -ENOMEM if the system is out of memory.
1723 */
1724static int verity_preresume(struct dm_target *ti)
1725{
1726 struct block_device *bdev;
1727 struct dm_verity_digest root_digest;
1728 struct dm_verity *v;
1729 int r;
1730
1731 v = ti->private;
1732 bdev = dm_disk(dm_table_get_md(ti->table))->part0;
1733 root_digest.digest = v->root_digest;
1734 root_digest.digest_len = v->digest_size;
1735 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm)
1736 root_digest.alg = crypto_ahash_alg_name(v->ahash_tfm);
1737 else
1738 root_digest.alg = crypto_shash_alg_name(v->shash_tfm);
1739
1740 r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest,
1741 sizeof(root_digest));
1742 if (r)
1743 return r;
1744
1745 r = verity_security_set_signature(bdev, v);
1746 if (r)
1747 goto bad;
1748
1749 return 0;
1750
1751bad:
1752
1753 security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0);
1754
1755 return r;
1756}
1757
1758#endif /* CONFIG_SECURITY */
1759
1760static struct target_type verity_target = {
1761 .name = "verity",
1762/* Note: the LSMs depend on the singleton and immutable features */
1763 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1764 .version = {1, 10, 0},
1765 .module = THIS_MODULE,
1766 .ctr = verity_ctr,
1767 .dtr = verity_dtr,
1768 .map = verity_map,
1769 .status = verity_status,
1770 .prepare_ioctl = verity_prepare_ioctl,
1771 .iterate_devices = verity_iterate_devices,
1772 .io_hints = verity_io_hints,
1773#ifdef CONFIG_SECURITY
1774 .preresume = verity_preresume,
1775#endif /* CONFIG_SECURITY */
1776};
1777module_dm(verity);
1778
1779/*
1780 * Check whether a DM target is a verity target.
1781 */
1782bool dm_is_verity_target(struct dm_target *ti)
1783{
1784 return ti->type == &verity_target;
1785}
1786
1787MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1788MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1789MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1790MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1791MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat, Inc.
4 *
5 * Author: Mikulas Patocka <mpatocka@redhat.com>
6 *
7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
8 *
9 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
10 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
11 * hash device. Setting this greatly improves performance when data and hash
12 * are on the same disk on different partitions on devices with poor random
13 * access behavior.
14 */
15
16#include "dm-verity.h"
17#include "dm-verity-fec.h"
18#include "dm-verity-verify-sig.h"
19#include <linux/module.h>
20#include <linux/reboot.h>
21
22#define DM_MSG_PREFIX "verity"
23
24#define DM_VERITY_ENV_LENGTH 42
25#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
26
27#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
28
29#define DM_VERITY_MAX_CORRUPTED_ERRS 100
30
31#define DM_VERITY_OPT_LOGGING "ignore_corruption"
32#define DM_VERITY_OPT_RESTART "restart_on_corruption"
33#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
34#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
35
36#define DM_VERITY_OPTS_MAX (2 + DM_VERITY_OPTS_FEC + \
37 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
38
39static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
40
41module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
42
43struct dm_verity_prefetch_work {
44 struct work_struct work;
45 struct dm_verity *v;
46 sector_t block;
47 unsigned n_blocks;
48};
49
50/*
51 * Auxiliary structure appended to each dm-bufio buffer. If the value
52 * hash_verified is nonzero, hash of the block has been verified.
53 *
54 * The variable hash_verified is set to 0 when allocating the buffer, then
55 * it can be changed to 1 and it is never reset to 0 again.
56 *
57 * There is no lock around this value, a race condition can at worst cause
58 * that multiple processes verify the hash of the same buffer simultaneously
59 * and write 1 to hash_verified simultaneously.
60 * This condition is harmless, so we don't need locking.
61 */
62struct buffer_aux {
63 int hash_verified;
64};
65
66/*
67 * Initialize struct buffer_aux for a freshly created buffer.
68 */
69static void dm_bufio_alloc_callback(struct dm_buffer *buf)
70{
71 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
72
73 aux->hash_verified = 0;
74}
75
76/*
77 * Translate input sector number to the sector number on the target device.
78 */
79static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
80{
81 return v->data_start + dm_target_offset(v->ti, bi_sector);
82}
83
84/*
85 * Return hash position of a specified block at a specified tree level
86 * (0 is the lowest level).
87 * The lowest "hash_per_block_bits"-bits of the result denote hash position
88 * inside a hash block. The remaining bits denote location of the hash block.
89 */
90static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
91 int level)
92{
93 return block >> (level * v->hash_per_block_bits);
94}
95
96static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
97 const u8 *data, size_t len,
98 struct crypto_wait *wait)
99{
100 struct scatterlist sg;
101
102 if (likely(!is_vmalloc_addr(data))) {
103 sg_init_one(&sg, data, len);
104 ahash_request_set_crypt(req, &sg, NULL, len);
105 return crypto_wait_req(crypto_ahash_update(req), wait);
106 } else {
107 do {
108 int r;
109 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
110 flush_kernel_vmap_range((void *)data, this_step);
111 sg_init_table(&sg, 1);
112 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
113 ahash_request_set_crypt(req, &sg, NULL, this_step);
114 r = crypto_wait_req(crypto_ahash_update(req), wait);
115 if (unlikely(r))
116 return r;
117 data += this_step;
118 len -= this_step;
119 } while (len);
120 return 0;
121 }
122}
123
124/*
125 * Wrapper for crypto_ahash_init, which handles verity salting.
126 */
127static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
128 struct crypto_wait *wait)
129{
130 int r;
131
132 ahash_request_set_tfm(req, v->tfm);
133 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
134 CRYPTO_TFM_REQ_MAY_BACKLOG,
135 crypto_req_done, (void *)wait);
136 crypto_init_wait(wait);
137
138 r = crypto_wait_req(crypto_ahash_init(req), wait);
139
140 if (unlikely(r < 0)) {
141 DMERR("crypto_ahash_init failed: %d", r);
142 return r;
143 }
144
145 if (likely(v->salt_size && (v->version >= 1)))
146 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
147
148 return r;
149}
150
151static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
152 u8 *digest, struct crypto_wait *wait)
153{
154 int r;
155
156 if (unlikely(v->salt_size && (!v->version))) {
157 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
158
159 if (r < 0) {
160 DMERR("verity_hash_final failed updating salt: %d", r);
161 goto out;
162 }
163 }
164
165 ahash_request_set_crypt(req, NULL, digest, 0);
166 r = crypto_wait_req(crypto_ahash_final(req), wait);
167out:
168 return r;
169}
170
171int verity_hash(struct dm_verity *v, struct ahash_request *req,
172 const u8 *data, size_t len, u8 *digest)
173{
174 int r;
175 struct crypto_wait wait;
176
177 r = verity_hash_init(v, req, &wait);
178 if (unlikely(r < 0))
179 goto out;
180
181 r = verity_hash_update(v, req, data, len, &wait);
182 if (unlikely(r < 0))
183 goto out;
184
185 r = verity_hash_final(v, req, digest, &wait);
186
187out:
188 return r;
189}
190
191static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
192 sector_t *hash_block, unsigned *offset)
193{
194 sector_t position = verity_position_at_level(v, block, level);
195 unsigned idx;
196
197 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
198
199 if (!offset)
200 return;
201
202 idx = position & ((1 << v->hash_per_block_bits) - 1);
203 if (!v->version)
204 *offset = idx * v->digest_size;
205 else
206 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
207}
208
209/*
210 * Handle verification errors.
211 */
212static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
213 unsigned long long block)
214{
215 char verity_env[DM_VERITY_ENV_LENGTH];
216 char *envp[] = { verity_env, NULL };
217 const char *type_str = "";
218 struct mapped_device *md = dm_table_get_md(v->ti->table);
219
220 /* Corruption should be visible in device status in all modes */
221 v->hash_failed = 1;
222
223 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
224 goto out;
225
226 v->corrupted_errs++;
227
228 switch (type) {
229 case DM_VERITY_BLOCK_TYPE_DATA:
230 type_str = "data";
231 break;
232 case DM_VERITY_BLOCK_TYPE_METADATA:
233 type_str = "metadata";
234 break;
235 default:
236 BUG();
237 }
238
239 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
240 type_str, block);
241
242 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
243 DMERR("%s: reached maximum errors", v->data_dev->name);
244
245 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
246 DM_VERITY_ENV_VAR_NAME, type, block);
247
248 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
249
250out:
251 if (v->mode == DM_VERITY_MODE_LOGGING)
252 return 0;
253
254 if (v->mode == DM_VERITY_MODE_RESTART)
255 kernel_restart("dm-verity device corrupted");
256
257 return 1;
258}
259
260/*
261 * Verify hash of a metadata block pertaining to the specified data block
262 * ("block" argument) at a specified level ("level" argument).
263 *
264 * On successful return, verity_io_want_digest(v, io) contains the hash value
265 * for a lower tree level or for the data block (if we're at the lowest level).
266 *
267 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
268 * If "skip_unverified" is false, unverified buffer is hashed and verified
269 * against current value of verity_io_want_digest(v, io).
270 */
271static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
272 sector_t block, int level, bool skip_unverified,
273 u8 *want_digest)
274{
275 struct dm_buffer *buf;
276 struct buffer_aux *aux;
277 u8 *data;
278 int r;
279 sector_t hash_block;
280 unsigned offset;
281
282 verity_hash_at_level(v, block, level, &hash_block, &offset);
283
284 data = dm_bufio_read(v->bufio, hash_block, &buf);
285 if (IS_ERR(data))
286 return PTR_ERR(data);
287
288 aux = dm_bufio_get_aux_data(buf);
289
290 if (!aux->hash_verified) {
291 if (skip_unverified) {
292 r = 1;
293 goto release_ret_r;
294 }
295
296 r = verity_hash(v, verity_io_hash_req(v, io),
297 data, 1 << v->hash_dev_block_bits,
298 verity_io_real_digest(v, io));
299 if (unlikely(r < 0))
300 goto release_ret_r;
301
302 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
303 v->digest_size) == 0))
304 aux->hash_verified = 1;
305 else if (verity_fec_decode(v, io,
306 DM_VERITY_BLOCK_TYPE_METADATA,
307 hash_block, data, NULL) == 0)
308 aux->hash_verified = 1;
309 else if (verity_handle_err(v,
310 DM_VERITY_BLOCK_TYPE_METADATA,
311 hash_block)) {
312 r = -EIO;
313 goto release_ret_r;
314 }
315 }
316
317 data += offset;
318 memcpy(want_digest, data, v->digest_size);
319 r = 0;
320
321release_ret_r:
322 dm_bufio_release(buf);
323 return r;
324}
325
326/*
327 * Find a hash for a given block, write it to digest and verify the integrity
328 * of the hash tree if necessary.
329 */
330int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
331 sector_t block, u8 *digest, bool *is_zero)
332{
333 int r = 0, i;
334
335 if (likely(v->levels)) {
336 /*
337 * First, we try to get the requested hash for
338 * the current block. If the hash block itself is
339 * verified, zero is returned. If it isn't, this
340 * function returns 1 and we fall back to whole
341 * chain verification.
342 */
343 r = verity_verify_level(v, io, block, 0, true, digest);
344 if (likely(r <= 0))
345 goto out;
346 }
347
348 memcpy(digest, v->root_digest, v->digest_size);
349
350 for (i = v->levels - 1; i >= 0; i--) {
351 r = verity_verify_level(v, io, block, i, false, digest);
352 if (unlikely(r))
353 goto out;
354 }
355out:
356 if (!r && v->zero_digest)
357 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
358 else
359 *is_zero = false;
360
361 return r;
362}
363
364/*
365 * Calculates the digest for the given bio
366 */
367static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
368 struct bvec_iter *iter, struct crypto_wait *wait)
369{
370 unsigned int todo = 1 << v->data_dev_block_bits;
371 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
372 struct scatterlist sg;
373 struct ahash_request *req = verity_io_hash_req(v, io);
374
375 do {
376 int r;
377 unsigned int len;
378 struct bio_vec bv = bio_iter_iovec(bio, *iter);
379
380 sg_init_table(&sg, 1);
381
382 len = bv.bv_len;
383
384 if (likely(len >= todo))
385 len = todo;
386 /*
387 * Operating on a single page at a time looks suboptimal
388 * until you consider the typical block size is 4,096B.
389 * Going through this loops twice should be very rare.
390 */
391 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
392 ahash_request_set_crypt(req, &sg, NULL, len);
393 r = crypto_wait_req(crypto_ahash_update(req), wait);
394
395 if (unlikely(r < 0)) {
396 DMERR("verity_for_io_block crypto op failed: %d", r);
397 return r;
398 }
399
400 bio_advance_iter(bio, iter, len);
401 todo -= len;
402 } while (todo);
403
404 return 0;
405}
406
407/*
408 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
409 * starting from iter.
410 */
411int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
412 struct bvec_iter *iter,
413 int (*process)(struct dm_verity *v,
414 struct dm_verity_io *io, u8 *data,
415 size_t len))
416{
417 unsigned todo = 1 << v->data_dev_block_bits;
418 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
419
420 do {
421 int r;
422 u8 *page;
423 unsigned len;
424 struct bio_vec bv = bio_iter_iovec(bio, *iter);
425
426 page = kmap_atomic(bv.bv_page);
427 len = bv.bv_len;
428
429 if (likely(len >= todo))
430 len = todo;
431
432 r = process(v, io, page + bv.bv_offset, len);
433 kunmap_atomic(page);
434
435 if (r < 0)
436 return r;
437
438 bio_advance_iter(bio, iter, len);
439 todo -= len;
440 } while (todo);
441
442 return 0;
443}
444
445static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
446 u8 *data, size_t len)
447{
448 memset(data, 0, len);
449 return 0;
450}
451
452/*
453 * Moves the bio iter one data block forward.
454 */
455static inline void verity_bv_skip_block(struct dm_verity *v,
456 struct dm_verity_io *io,
457 struct bvec_iter *iter)
458{
459 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
460
461 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
462}
463
464/*
465 * Verify one "dm_verity_io" structure.
466 */
467static int verity_verify_io(struct dm_verity_io *io)
468{
469 bool is_zero;
470 struct dm_verity *v = io->v;
471 struct bvec_iter start;
472 unsigned b;
473 struct crypto_wait wait;
474
475 for (b = 0; b < io->n_blocks; b++) {
476 int r;
477 sector_t cur_block = io->block + b;
478 struct ahash_request *req = verity_io_hash_req(v, io);
479
480 if (v->validated_blocks &&
481 likely(test_bit(cur_block, v->validated_blocks))) {
482 verity_bv_skip_block(v, io, &io->iter);
483 continue;
484 }
485
486 r = verity_hash_for_block(v, io, cur_block,
487 verity_io_want_digest(v, io),
488 &is_zero);
489 if (unlikely(r < 0))
490 return r;
491
492 if (is_zero) {
493 /*
494 * If we expect a zero block, don't validate, just
495 * return zeros.
496 */
497 r = verity_for_bv_block(v, io, &io->iter,
498 verity_bv_zero);
499 if (unlikely(r < 0))
500 return r;
501
502 continue;
503 }
504
505 r = verity_hash_init(v, req, &wait);
506 if (unlikely(r < 0))
507 return r;
508
509 start = io->iter;
510 r = verity_for_io_block(v, io, &io->iter, &wait);
511 if (unlikely(r < 0))
512 return r;
513
514 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
515 &wait);
516 if (unlikely(r < 0))
517 return r;
518
519 if (likely(memcmp(verity_io_real_digest(v, io),
520 verity_io_want_digest(v, io), v->digest_size) == 0)) {
521 if (v->validated_blocks)
522 set_bit(cur_block, v->validated_blocks);
523 continue;
524 }
525 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
526 cur_block, NULL, &start) == 0)
527 continue;
528 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
529 cur_block))
530 return -EIO;
531 }
532
533 return 0;
534}
535
536/*
537 * End one "io" structure with a given error.
538 */
539static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
540{
541 struct dm_verity *v = io->v;
542 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
543
544 bio->bi_end_io = io->orig_bi_end_io;
545 bio->bi_status = status;
546
547 verity_fec_finish_io(io);
548
549 bio_endio(bio);
550}
551
552static void verity_work(struct work_struct *w)
553{
554 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
555
556 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
557}
558
559static void verity_end_io(struct bio *bio)
560{
561 struct dm_verity_io *io = bio->bi_private;
562
563 if (bio->bi_status && !verity_fec_is_enabled(io->v)) {
564 verity_finish_io(io, bio->bi_status);
565 return;
566 }
567
568 INIT_WORK(&io->work, verity_work);
569 queue_work(io->v->verify_wq, &io->work);
570}
571
572/*
573 * Prefetch buffers for the specified io.
574 * The root buffer is not prefetched, it is assumed that it will be cached
575 * all the time.
576 */
577static void verity_prefetch_io(struct work_struct *work)
578{
579 struct dm_verity_prefetch_work *pw =
580 container_of(work, struct dm_verity_prefetch_work, work);
581 struct dm_verity *v = pw->v;
582 int i;
583
584 for (i = v->levels - 2; i >= 0; i--) {
585 sector_t hash_block_start;
586 sector_t hash_block_end;
587 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
588 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
589 if (!i) {
590 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
591
592 cluster >>= v->data_dev_block_bits;
593 if (unlikely(!cluster))
594 goto no_prefetch_cluster;
595
596 if (unlikely(cluster & (cluster - 1)))
597 cluster = 1 << __fls(cluster);
598
599 hash_block_start &= ~(sector_t)(cluster - 1);
600 hash_block_end |= cluster - 1;
601 if (unlikely(hash_block_end >= v->hash_blocks))
602 hash_block_end = v->hash_blocks - 1;
603 }
604no_prefetch_cluster:
605 dm_bufio_prefetch(v->bufio, hash_block_start,
606 hash_block_end - hash_block_start + 1);
607 }
608
609 kfree(pw);
610}
611
612static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
613{
614 struct dm_verity_prefetch_work *pw;
615
616 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
617 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
618
619 if (!pw)
620 return;
621
622 INIT_WORK(&pw->work, verity_prefetch_io);
623 pw->v = v;
624 pw->block = io->block;
625 pw->n_blocks = io->n_blocks;
626 queue_work(v->verify_wq, &pw->work);
627}
628
629/*
630 * Bio map function. It allocates dm_verity_io structure and bio vector and
631 * fills them. Then it issues prefetches and the I/O.
632 */
633static int verity_map(struct dm_target *ti, struct bio *bio)
634{
635 struct dm_verity *v = ti->private;
636 struct dm_verity_io *io;
637
638 bio_set_dev(bio, v->data_dev->bdev);
639 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
640
641 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
642 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
643 DMERR_LIMIT("unaligned io");
644 return DM_MAPIO_KILL;
645 }
646
647 if (bio_end_sector(bio) >>
648 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
649 DMERR_LIMIT("io out of range");
650 return DM_MAPIO_KILL;
651 }
652
653 if (bio_data_dir(bio) == WRITE)
654 return DM_MAPIO_KILL;
655
656 io = dm_per_bio_data(bio, ti->per_io_data_size);
657 io->v = v;
658 io->orig_bi_end_io = bio->bi_end_io;
659 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
660 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
661
662 bio->bi_end_io = verity_end_io;
663 bio->bi_private = io;
664 io->iter = bio->bi_iter;
665
666 verity_fec_init_io(io);
667
668 verity_submit_prefetch(v, io);
669
670 generic_make_request(bio);
671
672 return DM_MAPIO_SUBMITTED;
673}
674
675/*
676 * Status: V (valid) or C (corruption found)
677 */
678static void verity_status(struct dm_target *ti, status_type_t type,
679 unsigned status_flags, char *result, unsigned maxlen)
680{
681 struct dm_verity *v = ti->private;
682 unsigned args = 0;
683 unsigned sz = 0;
684 unsigned x;
685
686 switch (type) {
687 case STATUSTYPE_INFO:
688 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
689 break;
690 case STATUSTYPE_TABLE:
691 DMEMIT("%u %s %s %u %u %llu %llu %s ",
692 v->version,
693 v->data_dev->name,
694 v->hash_dev->name,
695 1 << v->data_dev_block_bits,
696 1 << v->hash_dev_block_bits,
697 (unsigned long long)v->data_blocks,
698 (unsigned long long)v->hash_start,
699 v->alg_name
700 );
701 for (x = 0; x < v->digest_size; x++)
702 DMEMIT("%02x", v->root_digest[x]);
703 DMEMIT(" ");
704 if (!v->salt_size)
705 DMEMIT("-");
706 else
707 for (x = 0; x < v->salt_size; x++)
708 DMEMIT("%02x", v->salt[x]);
709 if (v->mode != DM_VERITY_MODE_EIO)
710 args++;
711 if (verity_fec_is_enabled(v))
712 args += DM_VERITY_OPTS_FEC;
713 if (v->zero_digest)
714 args++;
715 if (v->validated_blocks)
716 args++;
717 if (v->signature_key_desc)
718 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
719 if (!args)
720 return;
721 DMEMIT(" %u", args);
722 if (v->mode != DM_VERITY_MODE_EIO) {
723 DMEMIT(" ");
724 switch (v->mode) {
725 case DM_VERITY_MODE_LOGGING:
726 DMEMIT(DM_VERITY_OPT_LOGGING);
727 break;
728 case DM_VERITY_MODE_RESTART:
729 DMEMIT(DM_VERITY_OPT_RESTART);
730 break;
731 default:
732 BUG();
733 }
734 }
735 if (v->zero_digest)
736 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
737 if (v->validated_blocks)
738 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
739 sz = verity_fec_status_table(v, sz, result, maxlen);
740 if (v->signature_key_desc)
741 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
742 " %s", v->signature_key_desc);
743 break;
744 }
745}
746
747static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
748{
749 struct dm_verity *v = ti->private;
750
751 *bdev = v->data_dev->bdev;
752
753 if (v->data_start ||
754 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
755 return 1;
756 return 0;
757}
758
759static int verity_iterate_devices(struct dm_target *ti,
760 iterate_devices_callout_fn fn, void *data)
761{
762 struct dm_verity *v = ti->private;
763
764 return fn(ti, v->data_dev, v->data_start, ti->len, data);
765}
766
767static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
768{
769 struct dm_verity *v = ti->private;
770
771 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
772 limits->logical_block_size = 1 << v->data_dev_block_bits;
773
774 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
775 limits->physical_block_size = 1 << v->data_dev_block_bits;
776
777 blk_limits_io_min(limits, limits->logical_block_size);
778}
779
780static void verity_dtr(struct dm_target *ti)
781{
782 struct dm_verity *v = ti->private;
783
784 if (v->verify_wq)
785 destroy_workqueue(v->verify_wq);
786
787 if (v->bufio)
788 dm_bufio_client_destroy(v->bufio);
789
790 kvfree(v->validated_blocks);
791 kfree(v->salt);
792 kfree(v->root_digest);
793 kfree(v->zero_digest);
794
795 if (v->tfm)
796 crypto_free_ahash(v->tfm);
797
798 kfree(v->alg_name);
799
800 if (v->hash_dev)
801 dm_put_device(ti, v->hash_dev);
802
803 if (v->data_dev)
804 dm_put_device(ti, v->data_dev);
805
806 verity_fec_dtr(v);
807
808 kfree(v->signature_key_desc);
809
810 kfree(v);
811}
812
813static int verity_alloc_most_once(struct dm_verity *v)
814{
815 struct dm_target *ti = v->ti;
816
817 /* the bitset can only handle INT_MAX blocks */
818 if (v->data_blocks > INT_MAX) {
819 ti->error = "device too large to use check_at_most_once";
820 return -E2BIG;
821 }
822
823 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
824 sizeof(unsigned long),
825 GFP_KERNEL);
826 if (!v->validated_blocks) {
827 ti->error = "failed to allocate bitset for check_at_most_once";
828 return -ENOMEM;
829 }
830
831 return 0;
832}
833
834static int verity_alloc_zero_digest(struct dm_verity *v)
835{
836 int r = -ENOMEM;
837 struct ahash_request *req;
838 u8 *zero_data;
839
840 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
841
842 if (!v->zero_digest)
843 return r;
844
845 req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
846
847 if (!req)
848 return r; /* verity_dtr will free zero_digest */
849
850 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
851
852 if (!zero_data)
853 goto out;
854
855 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
856 v->zero_digest);
857
858out:
859 kfree(req);
860 kfree(zero_data);
861
862 return r;
863}
864
865static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
866 struct dm_verity_sig_opts *verify_args)
867{
868 int r;
869 unsigned argc;
870 struct dm_target *ti = v->ti;
871 const char *arg_name;
872
873 static const struct dm_arg _args[] = {
874 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
875 };
876
877 r = dm_read_arg_group(_args, as, &argc, &ti->error);
878 if (r)
879 return -EINVAL;
880
881 if (!argc)
882 return 0;
883
884 do {
885 arg_name = dm_shift_arg(as);
886 argc--;
887
888 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
889 v->mode = DM_VERITY_MODE_LOGGING;
890 continue;
891
892 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
893 v->mode = DM_VERITY_MODE_RESTART;
894 continue;
895
896 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
897 r = verity_alloc_zero_digest(v);
898 if (r) {
899 ti->error = "Cannot allocate zero digest";
900 return r;
901 }
902 continue;
903
904 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
905 r = verity_alloc_most_once(v);
906 if (r)
907 return r;
908 continue;
909
910 } else if (verity_is_fec_opt_arg(arg_name)) {
911 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
912 if (r)
913 return r;
914 continue;
915 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
916 r = verity_verify_sig_parse_opt_args(as, v,
917 verify_args,
918 &argc, arg_name);
919 if (r)
920 return r;
921 continue;
922
923 }
924
925 ti->error = "Unrecognized verity feature request";
926 return -EINVAL;
927 } while (argc && !r);
928
929 return r;
930}
931
932/*
933 * Target parameters:
934 * <version> The current format is version 1.
935 * Vsn 0 is compatible with original Chromium OS releases.
936 * <data device>
937 * <hash device>
938 * <data block size>
939 * <hash block size>
940 * <the number of data blocks>
941 * <hash start block>
942 * <algorithm>
943 * <digest>
944 * <salt> Hex string or "-" if no salt.
945 */
946static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
947{
948 struct dm_verity *v;
949 struct dm_verity_sig_opts verify_args = {0};
950 struct dm_arg_set as;
951 unsigned int num;
952 unsigned long long num_ll;
953 int r;
954 int i;
955 sector_t hash_position;
956 char dummy;
957 char *root_hash_digest_to_validate;
958
959 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
960 if (!v) {
961 ti->error = "Cannot allocate verity structure";
962 return -ENOMEM;
963 }
964 ti->private = v;
965 v->ti = ti;
966
967 r = verity_fec_ctr_alloc(v);
968 if (r)
969 goto bad;
970
971 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
972 ti->error = "Device must be readonly";
973 r = -EINVAL;
974 goto bad;
975 }
976
977 if (argc < 10) {
978 ti->error = "Not enough arguments";
979 r = -EINVAL;
980 goto bad;
981 }
982
983 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
984 num > 1) {
985 ti->error = "Invalid version";
986 r = -EINVAL;
987 goto bad;
988 }
989 v->version = num;
990
991 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
992 if (r) {
993 ti->error = "Data device lookup failed";
994 goto bad;
995 }
996
997 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
998 if (r) {
999 ti->error = "Hash device lookup failed";
1000 goto bad;
1001 }
1002
1003 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1004 !num || (num & (num - 1)) ||
1005 num < bdev_logical_block_size(v->data_dev->bdev) ||
1006 num > PAGE_SIZE) {
1007 ti->error = "Invalid data device block size";
1008 r = -EINVAL;
1009 goto bad;
1010 }
1011 v->data_dev_block_bits = __ffs(num);
1012
1013 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1014 !num || (num & (num - 1)) ||
1015 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1016 num > INT_MAX) {
1017 ti->error = "Invalid hash device block size";
1018 r = -EINVAL;
1019 goto bad;
1020 }
1021 v->hash_dev_block_bits = __ffs(num);
1022
1023 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1024 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1025 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1026 ti->error = "Invalid data blocks";
1027 r = -EINVAL;
1028 goto bad;
1029 }
1030 v->data_blocks = num_ll;
1031
1032 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1033 ti->error = "Data device is too small";
1034 r = -EINVAL;
1035 goto bad;
1036 }
1037
1038 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1039 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1040 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1041 ti->error = "Invalid hash start";
1042 r = -EINVAL;
1043 goto bad;
1044 }
1045 v->hash_start = num_ll;
1046
1047 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1048 if (!v->alg_name) {
1049 ti->error = "Cannot allocate algorithm name";
1050 r = -ENOMEM;
1051 goto bad;
1052 }
1053
1054 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1055 if (IS_ERR(v->tfm)) {
1056 ti->error = "Cannot initialize hash function";
1057 r = PTR_ERR(v->tfm);
1058 v->tfm = NULL;
1059 goto bad;
1060 }
1061
1062 /*
1063 * dm-verity performance can vary greatly depending on which hash
1064 * algorithm implementation is used. Help people debug performance
1065 * problems by logging the ->cra_driver_name.
1066 */
1067 DMINFO("%s using implementation \"%s\"", v->alg_name,
1068 crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1069
1070 v->digest_size = crypto_ahash_digestsize(v->tfm);
1071 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1072 ti->error = "Digest size too big";
1073 r = -EINVAL;
1074 goto bad;
1075 }
1076 v->ahash_reqsize = sizeof(struct ahash_request) +
1077 crypto_ahash_reqsize(v->tfm);
1078
1079 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1080 if (!v->root_digest) {
1081 ti->error = "Cannot allocate root digest";
1082 r = -ENOMEM;
1083 goto bad;
1084 }
1085 if (strlen(argv[8]) != v->digest_size * 2 ||
1086 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1087 ti->error = "Invalid root digest";
1088 r = -EINVAL;
1089 goto bad;
1090 }
1091 root_hash_digest_to_validate = argv[8];
1092
1093 if (strcmp(argv[9], "-")) {
1094 v->salt_size = strlen(argv[9]) / 2;
1095 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1096 if (!v->salt) {
1097 ti->error = "Cannot allocate salt";
1098 r = -ENOMEM;
1099 goto bad;
1100 }
1101 if (strlen(argv[9]) != v->salt_size * 2 ||
1102 hex2bin(v->salt, argv[9], v->salt_size)) {
1103 ti->error = "Invalid salt";
1104 r = -EINVAL;
1105 goto bad;
1106 }
1107 }
1108
1109 argv += 10;
1110 argc -= 10;
1111
1112 /* Optional parameters */
1113 if (argc) {
1114 as.argc = argc;
1115 as.argv = argv;
1116
1117 r = verity_parse_opt_args(&as, v, &verify_args);
1118 if (r < 0)
1119 goto bad;
1120 }
1121
1122 /* Root hash signature is a optional parameter*/
1123 r = verity_verify_root_hash(root_hash_digest_to_validate,
1124 strlen(root_hash_digest_to_validate),
1125 verify_args.sig,
1126 verify_args.sig_size);
1127 if (r < 0) {
1128 ti->error = "Root hash verification failed";
1129 goto bad;
1130 }
1131 v->hash_per_block_bits =
1132 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1133
1134 v->levels = 0;
1135 if (v->data_blocks)
1136 while (v->hash_per_block_bits * v->levels < 64 &&
1137 (unsigned long long)(v->data_blocks - 1) >>
1138 (v->hash_per_block_bits * v->levels))
1139 v->levels++;
1140
1141 if (v->levels > DM_VERITY_MAX_LEVELS) {
1142 ti->error = "Too many tree levels";
1143 r = -E2BIG;
1144 goto bad;
1145 }
1146
1147 hash_position = v->hash_start;
1148 for (i = v->levels - 1; i >= 0; i--) {
1149 sector_t s;
1150 v->hash_level_block[i] = hash_position;
1151 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1152 >> ((i + 1) * v->hash_per_block_bits);
1153 if (hash_position + s < hash_position) {
1154 ti->error = "Hash device offset overflow";
1155 r = -E2BIG;
1156 goto bad;
1157 }
1158 hash_position += s;
1159 }
1160 v->hash_blocks = hash_position;
1161
1162 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1163 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1164 dm_bufio_alloc_callback, NULL);
1165 if (IS_ERR(v->bufio)) {
1166 ti->error = "Cannot initialize dm-bufio";
1167 r = PTR_ERR(v->bufio);
1168 v->bufio = NULL;
1169 goto bad;
1170 }
1171
1172 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1173 ti->error = "Hash device is too small";
1174 r = -E2BIG;
1175 goto bad;
1176 }
1177
1178 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1179 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1180 if (!v->verify_wq) {
1181 ti->error = "Cannot allocate workqueue";
1182 r = -ENOMEM;
1183 goto bad;
1184 }
1185
1186 ti->per_io_data_size = sizeof(struct dm_verity_io) +
1187 v->ahash_reqsize + v->digest_size * 2;
1188
1189 r = verity_fec_ctr(v);
1190 if (r)
1191 goto bad;
1192
1193 ti->per_io_data_size = roundup(ti->per_io_data_size,
1194 __alignof__(struct dm_verity_io));
1195
1196 verity_verify_sig_opts_cleanup(&verify_args);
1197
1198 return 0;
1199
1200bad:
1201
1202 verity_verify_sig_opts_cleanup(&verify_args);
1203 verity_dtr(ti);
1204
1205 return r;
1206}
1207
1208static struct target_type verity_target = {
1209 .name = "verity",
1210 .version = {1, 5, 0},
1211 .module = THIS_MODULE,
1212 .ctr = verity_ctr,
1213 .dtr = verity_dtr,
1214 .map = verity_map,
1215 .status = verity_status,
1216 .prepare_ioctl = verity_prepare_ioctl,
1217 .iterate_devices = verity_iterate_devices,
1218 .io_hints = verity_io_hints,
1219};
1220
1221static int __init dm_verity_init(void)
1222{
1223 int r;
1224
1225 r = dm_register_target(&verity_target);
1226 if (r < 0)
1227 DMERR("register failed %d", r);
1228
1229 return r;
1230}
1231
1232static void __exit dm_verity_exit(void)
1233{
1234 dm_unregister_target(&verity_target);
1235}
1236
1237module_init(dm_verity_init);
1238module_exit(dm_verity_exit);
1239
1240MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1241MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1242MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1243MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1244MODULE_LICENSE("GPL");