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 #define DM_VERITY_USE_BH_DEFAULT_BYTES 8192
34
35 #define DM_VERITY_MAX_CORRUPTED_ERRS 100
36
37 #define DM_VERITY_OPT_LOGGING "ignore_corruption"
38 #define DM_VERITY_OPT_RESTART "restart_on_corruption"
39 #define DM_VERITY_OPT_PANIC "panic_on_corruption"
40 #define DM_VERITY_OPT_ERROR_RESTART "restart_on_error"
41 #define DM_VERITY_OPT_ERROR_PANIC "panic_on_error"
42 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks"
43 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once"
44 #define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet"
45
46 #define DM_VERITY_OPTS_MAX (5 + DM_VERITY_OPTS_FEC + \
47 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
48
49 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
50
51 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
52
53 static unsigned int dm_verity_use_bh_bytes[4] = {
54 DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_NONE
55 DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_RT
56 DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_BE
57 0 // IOPRIO_CLASS_IDLE
58 };
59
60 module_param_array_named(use_bh_bytes, dm_verity_use_bh_bytes, uint, NULL, 0644);
61
62 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
63
64 /* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
65 static DEFINE_STATIC_KEY_FALSE(ahash_enabled);
66
67 struct dm_verity_prefetch_work {
68 struct work_struct work;
69 struct dm_verity *v;
70 unsigned short ioprio;
71 sector_t block;
72 unsigned int n_blocks;
73 };
74
75 /*
76 * Auxiliary structure appended to each dm-bufio buffer. If the value
77 * hash_verified is nonzero, hash of the block has been verified.
78 *
79 * The variable hash_verified is set to 0 when allocating the buffer, then
80 * it can be changed to 1 and it is never reset to 0 again.
81 *
82 * There is no lock around this value, a race condition can at worst cause
83 * that multiple processes verify the hash of the same buffer simultaneously
84 * and write 1 to hash_verified simultaneously.
85 * This condition is harmless, so we don't need locking.
86 */
87 struct buffer_aux {
88 int hash_verified;
89 };
90
91 /*
92 * Initialize struct buffer_aux for a freshly created buffer.
93 */
dm_bufio_alloc_callback(struct dm_buffer * buf)94 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
95 {
96 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
97
98 aux->hash_verified = 0;
99 }
100
101 /*
102 * Translate input sector number to the sector number on the target device.
103 */
verity_map_sector(struct dm_verity * v,sector_t bi_sector)104 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
105 {
106 return dm_target_offset(v->ti, bi_sector);
107 }
108
109 /*
110 * Return hash position of a specified block at a specified tree level
111 * (0 is the lowest level).
112 * The lowest "hash_per_block_bits"-bits of the result denote hash position
113 * inside a hash block. The remaining bits denote location of the hash block.
114 */
verity_position_at_level(struct dm_verity * v,sector_t block,int level)115 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
116 int level)
117 {
118 return block >> (level * v->hash_per_block_bits);
119 }
120
verity_ahash_update(struct dm_verity * v,struct ahash_request * req,const u8 * data,size_t len,struct crypto_wait * wait)121 static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req,
122 const u8 *data, size_t len,
123 struct crypto_wait *wait)
124 {
125 struct scatterlist sg;
126
127 if (likely(!is_vmalloc_addr(data))) {
128 sg_init_one(&sg, data, len);
129 ahash_request_set_crypt(req, &sg, NULL, len);
130 return crypto_wait_req(crypto_ahash_update(req), wait);
131 }
132
133 do {
134 int r;
135 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
136
137 flush_kernel_vmap_range((void *)data, this_step);
138 sg_init_table(&sg, 1);
139 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
140 ahash_request_set_crypt(req, &sg, NULL, this_step);
141 r = crypto_wait_req(crypto_ahash_update(req), wait);
142 if (unlikely(r))
143 return r;
144 data += this_step;
145 len -= this_step;
146 } while (len);
147
148 return 0;
149 }
150
151 /*
152 * Wrapper for crypto_ahash_init, which handles verity salting.
153 */
verity_ahash_init(struct dm_verity * v,struct ahash_request * req,struct crypto_wait * wait,bool may_sleep)154 static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req,
155 struct crypto_wait *wait, bool may_sleep)
156 {
157 int r;
158
159 ahash_request_set_tfm(req, v->ahash_tfm);
160 ahash_request_set_callback(req,
161 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
162 crypto_req_done, (void *)wait);
163 crypto_init_wait(wait);
164
165 r = crypto_wait_req(crypto_ahash_init(req), wait);
166
167 if (unlikely(r < 0)) {
168 if (r != -ENOMEM)
169 DMERR("crypto_ahash_init failed: %d", r);
170 return r;
171 }
172
173 if (likely(v->salt_size && (v->version >= 1)))
174 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
175
176 return r;
177 }
178
verity_ahash_final(struct dm_verity * v,struct ahash_request * req,u8 * digest,struct crypto_wait * wait)179 static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req,
180 u8 *digest, struct crypto_wait *wait)
181 {
182 int r;
183
184 if (unlikely(v->salt_size && (!v->version))) {
185 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
186
187 if (r < 0) {
188 DMERR("%s failed updating salt: %d", __func__, r);
189 goto out;
190 }
191 }
192
193 ahash_request_set_crypt(req, NULL, digest, 0);
194 r = crypto_wait_req(crypto_ahash_final(req), wait);
195 out:
196 return r;
197 }
198
verity_hash(struct dm_verity * v,struct dm_verity_io * io,const u8 * data,size_t len,u8 * digest,bool may_sleep)199 int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
200 const u8 *data, size_t len, u8 *digest, bool may_sleep)
201 {
202 int r;
203
204 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) {
205 struct ahash_request *req = verity_io_hash_req(v, io);
206 struct crypto_wait wait;
207
208 r = verity_ahash_init(v, req, &wait, may_sleep) ?:
209 verity_ahash_update(v, req, data, len, &wait) ?:
210 verity_ahash_final(v, req, digest, &wait);
211 } else {
212 struct shash_desc *desc = verity_io_hash_req(v, io);
213
214 desc->tfm = v->shash_tfm;
215 r = crypto_shash_import(desc, v->initial_hashstate) ?:
216 crypto_shash_finup(desc, data, len, digest);
217 }
218 if (unlikely(r))
219 DMERR("Error hashing block: %d", r);
220 return r;
221 }
222
verity_hash_at_level(struct dm_verity * v,sector_t block,int level,sector_t * hash_block,unsigned int * offset)223 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
224 sector_t *hash_block, unsigned int *offset)
225 {
226 sector_t position = verity_position_at_level(v, block, level);
227 unsigned int idx;
228
229 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
230
231 if (!offset)
232 return;
233
234 idx = position & ((1 << v->hash_per_block_bits) - 1);
235 if (!v->version)
236 *offset = idx * v->digest_size;
237 else
238 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
239 }
240
241 /*
242 * Handle verification errors.
243 */
verity_handle_err(struct dm_verity * v,enum verity_block_type type,unsigned long long block)244 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
245 unsigned long long block)
246 {
247 char verity_env[DM_VERITY_ENV_LENGTH];
248 char *envp[] = { verity_env, NULL };
249 const char *type_str = "";
250 struct mapped_device *md = dm_table_get_md(v->ti->table);
251
252 /* Corruption should be visible in device status in all modes */
253 v->hash_failed = true;
254
255 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
256 goto out;
257
258 v->corrupted_errs++;
259
260 switch (type) {
261 case DM_VERITY_BLOCK_TYPE_DATA:
262 type_str = "data";
263 break;
264 case DM_VERITY_BLOCK_TYPE_METADATA:
265 type_str = "metadata";
266 break;
267 default:
268 BUG();
269 }
270
271 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
272 type_str, block);
273
274 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
275 DMERR("%s: reached maximum errors", v->data_dev->name);
276 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
277 }
278
279 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
280 DM_VERITY_ENV_VAR_NAME, type, block);
281
282 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
283
284 out:
285 if (v->mode == DM_VERITY_MODE_LOGGING)
286 return 0;
287
288 if (v->mode == DM_VERITY_MODE_RESTART)
289 kernel_restart("dm-verity device corrupted");
290
291 if (v->mode == DM_VERITY_MODE_PANIC)
292 panic("dm-verity device corrupted");
293
294 return 1;
295 }
296
297 /*
298 * Verify hash of a metadata block pertaining to the specified data block
299 * ("block" argument) at a specified level ("level" argument).
300 *
301 * On successful return, verity_io_want_digest(v, io) contains the hash value
302 * for a lower tree level or for the data block (if we're at the lowest level).
303 *
304 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
305 * If "skip_unverified" is false, unverified buffer is hashed and verified
306 * against current value of verity_io_want_digest(v, io).
307 */
verity_verify_level(struct dm_verity * v,struct dm_verity_io * io,sector_t block,int level,bool skip_unverified,u8 * want_digest)308 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
309 sector_t block, int level, bool skip_unverified,
310 u8 *want_digest)
311 {
312 struct dm_buffer *buf;
313 struct buffer_aux *aux;
314 u8 *data;
315 int r;
316 sector_t hash_block;
317 unsigned int offset;
318 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
319
320 verity_hash_at_level(v, block, level, &hash_block, &offset);
321
322 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
323 data = dm_bufio_get(v->bufio, hash_block, &buf);
324 if (IS_ERR_OR_NULL(data)) {
325 /*
326 * In tasklet and the hash was not in the bufio cache.
327 * Return early and resume execution from a work-queue
328 * to read the hash from disk.
329 */
330 return -EAGAIN;
331 }
332 } else {
333 data = dm_bufio_read_with_ioprio(v->bufio, hash_block,
334 &buf, bio->bi_ioprio);
335 }
336
337 if (IS_ERR(data)) {
338 if (skip_unverified)
339 return 1;
340 r = PTR_ERR(data);
341 data = dm_bufio_new(v->bufio, hash_block, &buf);
342 if (IS_ERR(data))
343 return r;
344 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
345 hash_block, data) == 0) {
346 aux = dm_bufio_get_aux_data(buf);
347 aux->hash_verified = 1;
348 goto release_ok;
349 } else {
350 dm_bufio_release(buf);
351 dm_bufio_forget(v->bufio, hash_block);
352 return r;
353 }
354 }
355
356 aux = dm_bufio_get_aux_data(buf);
357
358 if (!aux->hash_verified) {
359 if (skip_unverified) {
360 r = 1;
361 goto release_ret_r;
362 }
363
364 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits,
365 verity_io_real_digest(v, io), !io->in_bh);
366 if (unlikely(r < 0))
367 goto release_ret_r;
368
369 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
370 v->digest_size) == 0))
371 aux->hash_verified = 1;
372 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
373 /*
374 * Error handling code (FEC included) cannot be run in a
375 * tasklet since it may sleep, so fallback to work-queue.
376 */
377 r = -EAGAIN;
378 goto release_ret_r;
379 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
380 hash_block, data) == 0)
381 aux->hash_verified = 1;
382 else if (verity_handle_err(v,
383 DM_VERITY_BLOCK_TYPE_METADATA,
384 hash_block)) {
385 struct bio *bio;
386 io->had_mismatch = true;
387 bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
388 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
389 block, 0);
390 r = -EIO;
391 goto release_ret_r;
392 }
393 }
394
395 release_ok:
396 data += offset;
397 memcpy(want_digest, data, v->digest_size);
398 r = 0;
399
400 release_ret_r:
401 dm_bufio_release(buf);
402 return r;
403 }
404
405 /*
406 * Find a hash for a given block, write it to digest and verify the integrity
407 * of the hash tree if necessary.
408 */
verity_hash_for_block(struct dm_verity * v,struct dm_verity_io * io,sector_t block,u8 * digest,bool * is_zero)409 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
410 sector_t block, u8 *digest, bool *is_zero)
411 {
412 int r = 0, i;
413
414 if (likely(v->levels)) {
415 /*
416 * First, we try to get the requested hash for
417 * the current block. If the hash block itself is
418 * verified, zero is returned. If it isn't, this
419 * function returns 1 and we fall back to whole
420 * chain verification.
421 */
422 r = verity_verify_level(v, io, block, 0, true, digest);
423 if (likely(r <= 0))
424 goto out;
425 }
426
427 memcpy(digest, v->root_digest, v->digest_size);
428
429 for (i = v->levels - 1; i >= 0; i--) {
430 r = verity_verify_level(v, io, block, i, false, digest);
431 if (unlikely(r))
432 goto out;
433 }
434 out:
435 if (!r && v->zero_digest)
436 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
437 else
438 *is_zero = false;
439
440 return r;
441 }
442
verity_recheck(struct dm_verity * v,struct dm_verity_io * io,sector_t cur_block,u8 * dest)443 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
444 sector_t cur_block, u8 *dest)
445 {
446 struct page *page;
447 void *buffer;
448 int r;
449 struct dm_io_request io_req;
450 struct dm_io_region io_loc;
451
452 page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
453 buffer = page_to_virt(page);
454
455 io_req.bi_opf = REQ_OP_READ;
456 io_req.mem.type = DM_IO_KMEM;
457 io_req.mem.ptr.addr = buffer;
458 io_req.notify.fn = NULL;
459 io_req.client = v->io;
460 io_loc.bdev = v->data_dev->bdev;
461 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
462 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
463 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
464 if (unlikely(r))
465 goto free_ret;
466
467 r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
468 verity_io_real_digest(v, io), true);
469 if (unlikely(r))
470 goto free_ret;
471
472 if (memcmp(verity_io_real_digest(v, io),
473 verity_io_want_digest(v, io), v->digest_size)) {
474 r = -EIO;
475 goto free_ret;
476 }
477
478 memcpy(dest, buffer, 1 << v->data_dev_block_bits);
479 r = 0;
480 free_ret:
481 mempool_free(page, &v->recheck_pool);
482
483 return r;
484 }
485
verity_handle_data_hash_mismatch(struct dm_verity * v,struct dm_verity_io * io,struct bio * bio,sector_t blkno,u8 * data)486 static int verity_handle_data_hash_mismatch(struct dm_verity *v,
487 struct dm_verity_io *io,
488 struct bio *bio, sector_t blkno,
489 u8 *data)
490 {
491 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
492 /*
493 * Error handling code (FEC included) cannot be run in the
494 * BH workqueue, so fallback to a standard workqueue.
495 */
496 return -EAGAIN;
497 }
498 if (verity_recheck(v, io, blkno, data) == 0) {
499 if (v->validated_blocks)
500 set_bit(blkno, v->validated_blocks);
501 return 0;
502 }
503 #if defined(CONFIG_DM_VERITY_FEC)
504 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno,
505 data) == 0)
506 return 0;
507 #endif
508 if (bio->bi_status)
509 return -EIO; /* Error correction failed; Just return error */
510
511 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
512 io->had_mismatch = true;
513 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
514 return -EIO;
515 }
516 return 0;
517 }
518
519 /*
520 * Verify one "dm_verity_io" structure.
521 */
verity_verify_io(struct dm_verity_io * io)522 static int verity_verify_io(struct dm_verity_io *io)
523 {
524 struct dm_verity *v = io->v;
525 const unsigned int block_size = 1 << v->data_dev_block_bits;
526 struct bvec_iter iter_copy;
527 struct bvec_iter *iter;
528 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
529 unsigned int b;
530
531 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
532 /*
533 * Copy the iterator in case we need to restart
534 * verification in a work-queue.
535 */
536 iter_copy = io->iter;
537 iter = &iter_copy;
538 } else
539 iter = &io->iter;
540
541 for (b = 0; b < io->n_blocks;
542 b++, bio_advance_iter(bio, iter, block_size)) {
543 int r;
544 sector_t cur_block = io->block + b;
545 bool is_zero;
546 struct bio_vec bv;
547 void *data;
548
549 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
550 likely(test_bit(cur_block, v->validated_blocks)))
551 continue;
552
553 r = verity_hash_for_block(v, io, cur_block,
554 verity_io_want_digest(v, io),
555 &is_zero);
556 if (unlikely(r < 0))
557 return r;
558
559 bv = bio_iter_iovec(bio, *iter);
560 if (unlikely(bv.bv_len < block_size)) {
561 /*
562 * Data block spans pages. This should not happen,
563 * since dm-verity sets dma_alignment to the data block
564 * size minus 1, and dm-verity also doesn't allow the
565 * data block size to be greater than PAGE_SIZE.
566 */
567 DMERR_LIMIT("unaligned io (data block spans pages)");
568 return -EIO;
569 }
570
571 data = bvec_kmap_local(&bv);
572
573 if (is_zero) {
574 /*
575 * If we expect a zero block, don't validate, just
576 * return zeros.
577 */
578 memset(data, 0, block_size);
579 kunmap_local(data);
580 continue;
581 }
582
583 r = verity_hash(v, io, data, block_size,
584 verity_io_real_digest(v, io), !io->in_bh);
585 if (unlikely(r < 0)) {
586 kunmap_local(data);
587 return r;
588 }
589
590 if (likely(memcmp(verity_io_real_digest(v, io),
591 verity_io_want_digest(v, io), v->digest_size) == 0)) {
592 if (v->validated_blocks)
593 set_bit(cur_block, v->validated_blocks);
594 kunmap_local(data);
595 continue;
596 }
597 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block,
598 data);
599 kunmap_local(data);
600 if (unlikely(r))
601 return r;
602 }
603
604 return 0;
605 }
606
607 /*
608 * Skip verity work in response to I/O error when system is shutting down.
609 */
verity_is_system_shutting_down(void)610 static inline bool verity_is_system_shutting_down(void)
611 {
612 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
613 || system_state == SYSTEM_RESTART;
614 }
615
restart_io_error(struct work_struct * w)616 static void restart_io_error(struct work_struct *w)
617 {
618 kernel_restart("dm-verity device has I/O error");
619 }
620
621 /*
622 * End one "io" structure with a given error.
623 */
verity_finish_io(struct dm_verity_io * io,blk_status_t status)624 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
625 {
626 struct dm_verity *v = io->v;
627 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
628
629 bio->bi_end_io = io->orig_bi_end_io;
630 bio->bi_status = status;
631
632 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
633 verity_fec_finish_io(io);
634
635 if (unlikely(status != BLK_STS_OK) &&
636 unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
637 !io->had_mismatch &&
638 !verity_is_system_shutting_down()) {
639 if (v->error_mode == DM_VERITY_MODE_PANIC) {
640 panic("dm-verity device has I/O error");
641 }
642 if (v->error_mode == DM_VERITY_MODE_RESTART) {
643 static DECLARE_WORK(restart_work, restart_io_error);
644 queue_work(v->verify_wq, &restart_work);
645 /*
646 * We deliberately don't call bio_endio here, because
647 * the machine will be restarted anyway.
648 */
649 return;
650 }
651 }
652
653 bio_endio(bio);
654 }
655
verity_work(struct work_struct * w)656 static void verity_work(struct work_struct *w)
657 {
658 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
659
660 io->in_bh = false;
661
662 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
663 }
664
verity_bh_work(struct work_struct * w)665 static void verity_bh_work(struct work_struct *w)
666 {
667 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
668 int err;
669
670 io->in_bh = true;
671 err = verity_verify_io(io);
672 if (err == -EAGAIN || err == -ENOMEM) {
673 /* fallback to retrying with work-queue */
674 INIT_WORK(&io->work, verity_work);
675 queue_work(io->v->verify_wq, &io->work);
676 return;
677 }
678
679 verity_finish_io(io, errno_to_blk_status(err));
680 }
681
verity_use_bh(unsigned int bytes,unsigned short ioprio)682 static inline bool verity_use_bh(unsigned int bytes, unsigned short ioprio)
683 {
684 return ioprio <= IOPRIO_CLASS_IDLE &&
685 bytes <= READ_ONCE(dm_verity_use_bh_bytes[ioprio]) &&
686 !need_resched();
687 }
688
verity_end_io(struct bio * bio)689 static void verity_end_io(struct bio *bio)
690 {
691 struct dm_verity_io *io = bio->bi_private;
692 unsigned short ioprio = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
693 unsigned int bytes = io->n_blocks << io->v->data_dev_block_bits;
694
695 if (bio->bi_status &&
696 (!verity_fec_is_enabled(io->v) ||
697 verity_is_system_shutting_down() ||
698 (bio->bi_opf & REQ_RAHEAD))) {
699 verity_finish_io(io, bio->bi_status);
700 return;
701 }
702
703 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq &&
704 verity_use_bh(bytes, ioprio)) {
705 if (in_hardirq() || irqs_disabled()) {
706 INIT_WORK(&io->bh_work, verity_bh_work);
707 queue_work(system_bh_wq, &io->bh_work);
708 } else {
709 verity_bh_work(&io->bh_work);
710 }
711 } else {
712 INIT_WORK(&io->work, verity_work);
713 queue_work(io->v->verify_wq, &io->work);
714 }
715 }
716
717 /*
718 * Prefetch buffers for the specified io.
719 * The root buffer is not prefetched, it is assumed that it will be cached
720 * all the time.
721 */
verity_prefetch_io(struct work_struct * work)722 static void verity_prefetch_io(struct work_struct *work)
723 {
724 struct dm_verity_prefetch_work *pw =
725 container_of(work, struct dm_verity_prefetch_work, work);
726 struct dm_verity *v = pw->v;
727 int i;
728
729 for (i = v->levels - 2; i >= 0; i--) {
730 sector_t hash_block_start;
731 sector_t hash_block_end;
732
733 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
734 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
735
736 if (!i) {
737 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
738
739 cluster >>= v->data_dev_block_bits;
740 if (unlikely(!cluster))
741 goto no_prefetch_cluster;
742
743 if (unlikely(cluster & (cluster - 1)))
744 cluster = 1 << __fls(cluster);
745
746 hash_block_start &= ~(sector_t)(cluster - 1);
747 hash_block_end |= cluster - 1;
748 if (unlikely(hash_block_end >= v->hash_blocks))
749 hash_block_end = v->hash_blocks - 1;
750 }
751 no_prefetch_cluster:
752 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start,
753 hash_block_end - hash_block_start + 1,
754 pw->ioprio);
755 }
756
757 kfree(pw);
758 }
759
verity_submit_prefetch(struct dm_verity * v,struct dm_verity_io * io,unsigned short ioprio)760 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
761 unsigned short ioprio)
762 {
763 sector_t block = io->block;
764 unsigned int n_blocks = io->n_blocks;
765 struct dm_verity_prefetch_work *pw;
766
767 if (v->validated_blocks) {
768 while (n_blocks && test_bit(block, v->validated_blocks)) {
769 block++;
770 n_blocks--;
771 }
772 while (n_blocks && test_bit(block + n_blocks - 1,
773 v->validated_blocks))
774 n_blocks--;
775 if (!n_blocks)
776 return;
777 }
778
779 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
780 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
781
782 if (!pw)
783 return;
784
785 INIT_WORK(&pw->work, verity_prefetch_io);
786 pw->v = v;
787 pw->block = block;
788 pw->n_blocks = n_blocks;
789 pw->ioprio = ioprio;
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 */
verity_map(struct dm_target * ti,struct bio * bio)797 static 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 io->had_mismatch = false;
826
827 bio->bi_end_io = verity_end_io;
828 bio->bi_private = io;
829 io->iter = bio->bi_iter;
830
831 verity_fec_init_io(io);
832
833 verity_submit_prefetch(v, io, bio->bi_ioprio);
834
835 submit_bio_noacct(bio);
836
837 return DM_MAPIO_SUBMITTED;
838 }
839
verity_postsuspend(struct dm_target * ti)840 static void verity_postsuspend(struct dm_target *ti)
841 {
842 struct dm_verity *v = ti->private;
843 flush_workqueue(v->verify_wq);
844 dm_bufio_client_reset(v->bufio);
845 }
846
847 /*
848 * Status: V (valid) or C (corruption found)
849 */
verity_status(struct dm_target * ti,status_type_t type,unsigned int status_flags,char * result,unsigned int maxlen)850 static void verity_status(struct dm_target *ti, status_type_t type,
851 unsigned int status_flags, char *result, unsigned int maxlen)
852 {
853 struct dm_verity *v = ti->private;
854 unsigned int args = 0;
855 unsigned int sz = 0;
856 unsigned int x;
857
858 switch (type) {
859 case STATUSTYPE_INFO:
860 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
861 break;
862 case STATUSTYPE_TABLE:
863 DMEMIT("%u %s %s %u %u %llu %llu %s ",
864 v->version,
865 v->data_dev->name,
866 v->hash_dev->name,
867 1 << v->data_dev_block_bits,
868 1 << v->hash_dev_block_bits,
869 (unsigned long long)v->data_blocks,
870 (unsigned long long)v->hash_start,
871 v->alg_name
872 );
873 for (x = 0; x < v->digest_size; x++)
874 DMEMIT("%02x", v->root_digest[x]);
875 DMEMIT(" ");
876 if (!v->salt_size)
877 DMEMIT("-");
878 else
879 for (x = 0; x < v->salt_size; x++)
880 DMEMIT("%02x", v->salt[x]);
881 if (v->mode != DM_VERITY_MODE_EIO)
882 args++;
883 if (v->error_mode != DM_VERITY_MODE_EIO)
884 args++;
885 if (verity_fec_is_enabled(v))
886 args += DM_VERITY_OPTS_FEC;
887 if (v->zero_digest)
888 args++;
889 if (v->validated_blocks)
890 args++;
891 if (v->use_bh_wq)
892 args++;
893 if (v->signature_key_desc)
894 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
895 if (!args)
896 return;
897 DMEMIT(" %u", args);
898 if (v->mode != DM_VERITY_MODE_EIO) {
899 DMEMIT(" ");
900 switch (v->mode) {
901 case DM_VERITY_MODE_LOGGING:
902 DMEMIT(DM_VERITY_OPT_LOGGING);
903 break;
904 case DM_VERITY_MODE_RESTART:
905 DMEMIT(DM_VERITY_OPT_RESTART);
906 break;
907 case DM_VERITY_MODE_PANIC:
908 DMEMIT(DM_VERITY_OPT_PANIC);
909 break;
910 default:
911 BUG();
912 }
913 }
914 if (v->error_mode != DM_VERITY_MODE_EIO) {
915 DMEMIT(" ");
916 switch (v->error_mode) {
917 case DM_VERITY_MODE_RESTART:
918 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
919 break;
920 case DM_VERITY_MODE_PANIC:
921 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
922 break;
923 default:
924 BUG();
925 }
926 }
927 if (v->zero_digest)
928 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
929 if (v->validated_blocks)
930 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
931 if (v->use_bh_wq)
932 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
933 sz = verity_fec_status_table(v, sz, result, maxlen);
934 if (v->signature_key_desc)
935 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
936 " %s", v->signature_key_desc);
937 break;
938
939 case STATUSTYPE_IMA:
940 DMEMIT_TARGET_NAME_VERSION(ti->type);
941 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
942 DMEMIT(",verity_version=%u", v->version);
943 DMEMIT(",data_device_name=%s", v->data_dev->name);
944 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
945 DMEMIT(",verity_algorithm=%s", v->alg_name);
946
947 DMEMIT(",root_digest=");
948 for (x = 0; x < v->digest_size; x++)
949 DMEMIT("%02x", v->root_digest[x]);
950
951 DMEMIT(",salt=");
952 if (!v->salt_size)
953 DMEMIT("-");
954 else
955 for (x = 0; x < v->salt_size; x++)
956 DMEMIT("%02x", v->salt[x]);
957
958 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
959 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
960 if (v->signature_key_desc)
961 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
962
963 if (v->mode != DM_VERITY_MODE_EIO) {
964 DMEMIT(",verity_mode=");
965 switch (v->mode) {
966 case DM_VERITY_MODE_LOGGING:
967 DMEMIT(DM_VERITY_OPT_LOGGING);
968 break;
969 case DM_VERITY_MODE_RESTART:
970 DMEMIT(DM_VERITY_OPT_RESTART);
971 break;
972 case DM_VERITY_MODE_PANIC:
973 DMEMIT(DM_VERITY_OPT_PANIC);
974 break;
975 default:
976 DMEMIT("invalid");
977 }
978 }
979 if (v->error_mode != DM_VERITY_MODE_EIO) {
980 DMEMIT(",verity_error_mode=");
981 switch (v->error_mode) {
982 case DM_VERITY_MODE_RESTART:
983 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
984 break;
985 case DM_VERITY_MODE_PANIC:
986 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
987 break;
988 default:
989 DMEMIT("invalid");
990 }
991 }
992 DMEMIT(";");
993 break;
994 }
995 }
996
verity_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev,unsigned int cmd,unsigned long arg,bool * forward)997 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev,
998 unsigned int cmd, unsigned long arg,
999 bool *forward)
1000 {
1001 struct dm_verity *v = ti->private;
1002
1003 *bdev = v->data_dev->bdev;
1004
1005 if (ti->len != bdev_nr_sectors(v->data_dev->bdev))
1006 return 1;
1007 return 0;
1008 }
1009
verity_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)1010 static int verity_iterate_devices(struct dm_target *ti,
1011 iterate_devices_callout_fn fn, void *data)
1012 {
1013 struct dm_verity *v = ti->private;
1014
1015 return fn(ti, v->data_dev, 0, ti->len, data);
1016 }
1017
verity_io_hints(struct dm_target * ti,struct queue_limits * limits)1018 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
1019 {
1020 struct dm_verity *v = ti->private;
1021
1022 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
1023 limits->logical_block_size = 1 << v->data_dev_block_bits;
1024
1025 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
1026 limits->physical_block_size = 1 << v->data_dev_block_bits;
1027
1028 limits->io_min = limits->logical_block_size;
1029
1030 /*
1031 * Similar to what dm-crypt does, opt dm-verity out of support for
1032 * direct I/O that is aligned to less than the traditional direct I/O
1033 * alignment requirement of logical_block_size. This prevents dm-verity
1034 * data blocks from crossing pages, eliminating various edge cases.
1035 */
1036 limits->dma_alignment = limits->logical_block_size - 1;
1037 }
1038
1039 #ifdef CONFIG_SECURITY
1040
verity_init_sig(struct dm_verity * v,const void * sig,size_t sig_size)1041 static int verity_init_sig(struct dm_verity *v, const void *sig,
1042 size_t sig_size)
1043 {
1044 v->sig_size = sig_size;
1045
1046 if (sig) {
1047 v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL);
1048 if (!v->root_digest_sig)
1049 return -ENOMEM;
1050 }
1051
1052 return 0;
1053 }
1054
verity_free_sig(struct dm_verity * v)1055 static void verity_free_sig(struct dm_verity *v)
1056 {
1057 kfree(v->root_digest_sig);
1058 }
1059
1060 #else
1061
verity_init_sig(struct dm_verity * v,const void * sig,size_t sig_size)1062 static inline int verity_init_sig(struct dm_verity *v, const void *sig,
1063 size_t sig_size)
1064 {
1065 return 0;
1066 }
1067
verity_free_sig(struct dm_verity * v)1068 static inline void verity_free_sig(struct dm_verity *v)
1069 {
1070 }
1071
1072 #endif /* CONFIG_SECURITY */
1073
verity_dtr(struct dm_target * ti)1074 static void verity_dtr(struct dm_target *ti)
1075 {
1076 struct dm_verity *v = ti->private;
1077
1078 if (v->verify_wq)
1079 destroy_workqueue(v->verify_wq);
1080
1081 mempool_exit(&v->recheck_pool);
1082 if (v->io)
1083 dm_io_client_destroy(v->io);
1084
1085 if (v->bufio)
1086 dm_bufio_client_destroy(v->bufio);
1087
1088 kvfree(v->validated_blocks);
1089 kfree(v->salt);
1090 kfree(v->initial_hashstate);
1091 kfree(v->root_digest);
1092 kfree(v->zero_digest);
1093 verity_free_sig(v);
1094
1095 if (v->ahash_tfm) {
1096 static_branch_dec(&ahash_enabled);
1097 crypto_free_ahash(v->ahash_tfm);
1098 } else {
1099 crypto_free_shash(v->shash_tfm);
1100 }
1101
1102 kfree(v->alg_name);
1103
1104 if (v->hash_dev)
1105 dm_put_device(ti, v->hash_dev);
1106
1107 if (v->data_dev)
1108 dm_put_device(ti, v->data_dev);
1109
1110 verity_fec_dtr(v);
1111
1112 kfree(v->signature_key_desc);
1113
1114 if (v->use_bh_wq)
1115 static_branch_dec(&use_bh_wq_enabled);
1116
1117 kfree(v);
1118
1119 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1120 }
1121
verity_alloc_most_once(struct dm_verity * v)1122 static int verity_alloc_most_once(struct dm_verity *v)
1123 {
1124 struct dm_target *ti = v->ti;
1125
1126 if (v->validated_blocks)
1127 return 0;
1128
1129 /* the bitset can only handle INT_MAX blocks */
1130 if (v->data_blocks > INT_MAX) {
1131 ti->error = "device too large to use check_at_most_once";
1132 return -E2BIG;
1133 }
1134
1135 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1136 sizeof(unsigned long),
1137 GFP_KERNEL);
1138 if (!v->validated_blocks) {
1139 ti->error = "failed to allocate bitset for check_at_most_once";
1140 return -ENOMEM;
1141 }
1142
1143 return 0;
1144 }
1145
verity_alloc_zero_digest(struct dm_verity * v)1146 static int verity_alloc_zero_digest(struct dm_verity *v)
1147 {
1148 int r = -ENOMEM;
1149 struct dm_verity_io *io;
1150 u8 *zero_data;
1151
1152 if (v->zero_digest)
1153 return 0;
1154
1155 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1156
1157 if (!v->zero_digest)
1158 return r;
1159
1160 io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL);
1161
1162 if (!io)
1163 return r; /* verity_dtr will free zero_digest */
1164
1165 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1166
1167 if (!zero_data)
1168 goto out;
1169
1170 r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits,
1171 v->zero_digest, true);
1172
1173 out:
1174 kfree(io);
1175 kfree(zero_data);
1176
1177 return r;
1178 }
1179
verity_is_verity_mode(const char * arg_name)1180 static inline bool verity_is_verity_mode(const char *arg_name)
1181 {
1182 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1183 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1184 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1185 }
1186
verity_parse_verity_mode(struct dm_verity * v,const char * arg_name)1187 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1188 {
1189 if (v->mode)
1190 return -EINVAL;
1191
1192 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1193 v->mode = DM_VERITY_MODE_LOGGING;
1194 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1195 v->mode = DM_VERITY_MODE_RESTART;
1196 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1197 v->mode = DM_VERITY_MODE_PANIC;
1198
1199 return 0;
1200 }
1201
verity_is_verity_error_mode(const char * arg_name)1202 static inline bool verity_is_verity_error_mode(const char *arg_name)
1203 {
1204 return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) ||
1205 !strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC));
1206 }
1207
verity_parse_verity_error_mode(struct dm_verity * v,const char * arg_name)1208 static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name)
1209 {
1210 if (v->error_mode)
1211 return -EINVAL;
1212
1213 if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART))
1214 v->error_mode = DM_VERITY_MODE_RESTART;
1215 else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC))
1216 v->error_mode = DM_VERITY_MODE_PANIC;
1217
1218 return 0;
1219 }
1220
verity_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,struct dm_verity_sig_opts * verify_args,bool only_modifier_opts)1221 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1222 struct dm_verity_sig_opts *verify_args,
1223 bool only_modifier_opts)
1224 {
1225 int r = 0;
1226 unsigned int argc;
1227 struct dm_target *ti = v->ti;
1228 const char *arg_name;
1229
1230 static const struct dm_arg _args[] = {
1231 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1232 };
1233
1234 r = dm_read_arg_group(_args, as, &argc, &ti->error);
1235 if (r)
1236 return -EINVAL;
1237
1238 if (!argc)
1239 return 0;
1240
1241 do {
1242 arg_name = dm_shift_arg(as);
1243 argc--;
1244
1245 if (verity_is_verity_mode(arg_name)) {
1246 if (only_modifier_opts)
1247 continue;
1248 r = verity_parse_verity_mode(v, arg_name);
1249 if (r) {
1250 ti->error = "Conflicting error handling parameters";
1251 return r;
1252 }
1253 continue;
1254
1255 } else if (verity_is_verity_error_mode(arg_name)) {
1256 if (only_modifier_opts)
1257 continue;
1258 r = verity_parse_verity_error_mode(v, arg_name);
1259 if (r) {
1260 ti->error = "Conflicting error handling parameters";
1261 return r;
1262 }
1263 continue;
1264
1265 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1266 if (only_modifier_opts)
1267 continue;
1268 r = verity_alloc_zero_digest(v);
1269 if (r) {
1270 ti->error = "Cannot allocate zero digest";
1271 return r;
1272 }
1273 continue;
1274
1275 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1276 if (only_modifier_opts)
1277 continue;
1278 r = verity_alloc_most_once(v);
1279 if (r)
1280 return r;
1281 continue;
1282
1283 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1284 v->use_bh_wq = true;
1285 static_branch_inc(&use_bh_wq_enabled);
1286 continue;
1287
1288 } else if (verity_is_fec_opt_arg(arg_name)) {
1289 if (only_modifier_opts)
1290 continue;
1291 r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1292 if (r)
1293 return r;
1294 continue;
1295
1296 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1297 if (only_modifier_opts)
1298 continue;
1299 r = verity_verify_sig_parse_opt_args(as, v,
1300 verify_args,
1301 &argc, arg_name);
1302 if (r)
1303 return r;
1304 continue;
1305
1306 } else if (only_modifier_opts) {
1307 /*
1308 * Ignore unrecognized opt, could easily be an extra
1309 * argument to an option whose parsing was skipped.
1310 * Normal parsing (@only_modifier_opts=false) will
1311 * properly parse all options (and their extra args).
1312 */
1313 continue;
1314 }
1315
1316 DMERR("Unrecognized verity feature request: %s", arg_name);
1317 ti->error = "Unrecognized verity feature request";
1318 return -EINVAL;
1319 } while (argc && !r);
1320
1321 return r;
1322 }
1323
verity_setup_hash_alg(struct dm_verity * v,const char * alg_name)1324 static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name)
1325 {
1326 struct dm_target *ti = v->ti;
1327 struct crypto_ahash *ahash;
1328 struct crypto_shash *shash = NULL;
1329 const char *driver_name;
1330
1331 v->alg_name = kstrdup(alg_name, GFP_KERNEL);
1332 if (!v->alg_name) {
1333 ti->error = "Cannot allocate algorithm name";
1334 return -ENOMEM;
1335 }
1336
1337 /*
1338 * Allocate the hash transformation object that this dm-verity instance
1339 * will use. The vast majority of dm-verity users use CPU-based
1340 * hashing, so when possible use the shash API to minimize the crypto
1341 * API overhead. If the ahash API resolves to a different driver
1342 * (likely an off-CPU hardware offload), use ahash instead. Also use
1343 * ahash if the obsolete dm-verity format with the appended salt is
1344 * being used, so that quirk only needs to be handled in one place.
1345 */
1346 ahash = crypto_alloc_ahash(alg_name, 0,
1347 v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
1348 if (IS_ERR(ahash)) {
1349 ti->error = "Cannot initialize hash function";
1350 return PTR_ERR(ahash);
1351 }
1352 driver_name = crypto_ahash_driver_name(ahash);
1353 if (v->version >= 1 /* salt prepended, not appended? */) {
1354 shash = crypto_alloc_shash(alg_name, 0, 0);
1355 if (!IS_ERR(shash) &&
1356 strcmp(crypto_shash_driver_name(shash), driver_name) != 0) {
1357 /*
1358 * ahash gave a different driver than shash, so probably
1359 * this is a case of real hardware offload. Use ahash.
1360 */
1361 crypto_free_shash(shash);
1362 shash = NULL;
1363 }
1364 }
1365 if (!IS_ERR_OR_NULL(shash)) {
1366 crypto_free_ahash(ahash);
1367 ahash = NULL;
1368 v->shash_tfm = shash;
1369 v->digest_size = crypto_shash_digestsize(shash);
1370 v->hash_reqsize = sizeof(struct shash_desc) +
1371 crypto_shash_descsize(shash);
1372 DMINFO("%s using shash \"%s\"", alg_name, driver_name);
1373 } else {
1374 v->ahash_tfm = ahash;
1375 static_branch_inc(&ahash_enabled);
1376 v->digest_size = crypto_ahash_digestsize(ahash);
1377 v->hash_reqsize = sizeof(struct ahash_request) +
1378 crypto_ahash_reqsize(ahash);
1379 DMINFO("%s using ahash \"%s\"", alg_name, driver_name);
1380 }
1381 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1382 ti->error = "Digest size too big";
1383 return -EINVAL;
1384 }
1385 return 0;
1386 }
1387
verity_setup_salt_and_hashstate(struct dm_verity * v,const char * arg)1388 static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg)
1389 {
1390 struct dm_target *ti = v->ti;
1391
1392 if (strcmp(arg, "-") != 0) {
1393 v->salt_size = strlen(arg) / 2;
1394 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1395 if (!v->salt) {
1396 ti->error = "Cannot allocate salt";
1397 return -ENOMEM;
1398 }
1399 if (strlen(arg) != v->salt_size * 2 ||
1400 hex2bin(v->salt, arg, v->salt_size)) {
1401 ti->error = "Invalid salt";
1402 return -EINVAL;
1403 }
1404 }
1405 if (v->shash_tfm) {
1406 SHASH_DESC_ON_STACK(desc, v->shash_tfm);
1407 int r;
1408
1409 /*
1410 * Compute the pre-salted hash state that can be passed to
1411 * crypto_shash_import() for each block later.
1412 */
1413 v->initial_hashstate = kmalloc(
1414 crypto_shash_statesize(v->shash_tfm), GFP_KERNEL);
1415 if (!v->initial_hashstate) {
1416 ti->error = "Cannot allocate initial hash state";
1417 return -ENOMEM;
1418 }
1419 desc->tfm = v->shash_tfm;
1420 r = crypto_shash_init(desc) ?:
1421 crypto_shash_update(desc, v->salt, v->salt_size) ?:
1422 crypto_shash_export(desc, v->initial_hashstate);
1423 if (r) {
1424 ti->error = "Cannot set up initial hash state";
1425 return r;
1426 }
1427 }
1428 return 0;
1429 }
1430
1431 /*
1432 * Target parameters:
1433 * <version> The current format is version 1.
1434 * Vsn 0 is compatible with original Chromium OS releases.
1435 * <data device>
1436 * <hash device>
1437 * <data block size>
1438 * <hash block size>
1439 * <the number of data blocks>
1440 * <hash start block>
1441 * <algorithm>
1442 * <digest>
1443 * <salt> Hex string or "-" if no salt.
1444 */
verity_ctr(struct dm_target * ti,unsigned int argc,char ** argv)1445 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1446 {
1447 struct dm_verity *v;
1448 struct dm_verity_sig_opts verify_args = {0};
1449 struct dm_arg_set as;
1450 unsigned int num;
1451 unsigned long long num_ll;
1452 int r;
1453 int i;
1454 sector_t hash_position;
1455 char dummy;
1456 char *root_hash_digest_to_validate;
1457
1458 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1459 if (!v) {
1460 ti->error = "Cannot allocate verity structure";
1461 return -ENOMEM;
1462 }
1463 ti->private = v;
1464 v->ti = ti;
1465
1466 r = verity_fec_ctr_alloc(v);
1467 if (r)
1468 goto bad;
1469
1470 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1471 ti->error = "Device must be readonly";
1472 r = -EINVAL;
1473 goto bad;
1474 }
1475
1476 if (argc < 10) {
1477 ti->error = "Not enough arguments";
1478 r = -EINVAL;
1479 goto bad;
1480 }
1481
1482 /* Parse optional parameters that modify primary args */
1483 if (argc > 10) {
1484 as.argc = argc - 10;
1485 as.argv = argv + 10;
1486 r = verity_parse_opt_args(&as, v, &verify_args, true);
1487 if (r < 0)
1488 goto bad;
1489 }
1490
1491 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1492 num > 1) {
1493 ti->error = "Invalid version";
1494 r = -EINVAL;
1495 goto bad;
1496 }
1497 v->version = num;
1498
1499 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1500 if (r) {
1501 ti->error = "Data device lookup failed";
1502 goto bad;
1503 }
1504
1505 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1506 if (r) {
1507 ti->error = "Hash device lookup failed";
1508 goto bad;
1509 }
1510
1511 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1512 !num || (num & (num - 1)) ||
1513 num < bdev_logical_block_size(v->data_dev->bdev) ||
1514 num > PAGE_SIZE) {
1515 ti->error = "Invalid data device block size";
1516 r = -EINVAL;
1517 goto bad;
1518 }
1519 v->data_dev_block_bits = __ffs(num);
1520
1521 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1522 !num || (num & (num - 1)) ||
1523 num < bdev_logical_block_size(v->hash_dev->bdev) ||
1524 num > INT_MAX) {
1525 ti->error = "Invalid hash device block size";
1526 r = -EINVAL;
1527 goto bad;
1528 }
1529 v->hash_dev_block_bits = __ffs(num);
1530
1531 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1532 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1533 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1534 ti->error = "Invalid data blocks";
1535 r = -EINVAL;
1536 goto bad;
1537 }
1538 v->data_blocks = num_ll;
1539
1540 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1541 ti->error = "Data device is too small";
1542 r = -EINVAL;
1543 goto bad;
1544 }
1545
1546 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1547 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1548 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1549 ti->error = "Invalid hash start";
1550 r = -EINVAL;
1551 goto bad;
1552 }
1553 v->hash_start = num_ll;
1554
1555 r = verity_setup_hash_alg(v, argv[7]);
1556 if (r)
1557 goto bad;
1558
1559 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1560 if (!v->root_digest) {
1561 ti->error = "Cannot allocate root digest";
1562 r = -ENOMEM;
1563 goto bad;
1564 }
1565 if (strlen(argv[8]) != v->digest_size * 2 ||
1566 hex2bin(v->root_digest, argv[8], v->digest_size)) {
1567 ti->error = "Invalid root digest";
1568 r = -EINVAL;
1569 goto bad;
1570 }
1571 root_hash_digest_to_validate = argv[8];
1572
1573 r = verity_setup_salt_and_hashstate(v, argv[9]);
1574 if (r)
1575 goto bad;
1576
1577 argv += 10;
1578 argc -= 10;
1579
1580 /* Optional parameters */
1581 if (argc) {
1582 as.argc = argc;
1583 as.argv = argv;
1584 r = verity_parse_opt_args(&as, v, &verify_args, false);
1585 if (r < 0)
1586 goto bad;
1587 }
1588
1589 /* Root hash signature is an optional parameter */
1590 r = verity_verify_root_hash(root_hash_digest_to_validate,
1591 strlen(root_hash_digest_to_validate),
1592 verify_args.sig,
1593 verify_args.sig_size);
1594 if (r < 0) {
1595 ti->error = "Root hash verification failed";
1596 goto bad;
1597 }
1598
1599 r = verity_init_sig(v, verify_args.sig, verify_args.sig_size);
1600 if (r < 0) {
1601 ti->error = "Cannot allocate root digest signature";
1602 goto bad;
1603 }
1604
1605 v->hash_per_block_bits =
1606 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1607
1608 v->levels = 0;
1609 if (v->data_blocks)
1610 while (v->hash_per_block_bits * v->levels < 64 &&
1611 (unsigned long long)(v->data_blocks - 1) >>
1612 (v->hash_per_block_bits * v->levels))
1613 v->levels++;
1614
1615 if (v->levels > DM_VERITY_MAX_LEVELS) {
1616 ti->error = "Too many tree levels";
1617 r = -E2BIG;
1618 goto bad;
1619 }
1620
1621 hash_position = v->hash_start;
1622 for (i = v->levels - 1; i >= 0; i--) {
1623 sector_t s;
1624
1625 v->hash_level_block[i] = hash_position;
1626 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1627 >> ((i + 1) * v->hash_per_block_bits);
1628 if (hash_position + s < hash_position) {
1629 ti->error = "Hash device offset overflow";
1630 r = -E2BIG;
1631 goto bad;
1632 }
1633 hash_position += s;
1634 }
1635 v->hash_blocks = hash_position;
1636
1637 r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1638 if (unlikely(r)) {
1639 ti->error = "Cannot allocate mempool";
1640 goto bad;
1641 }
1642
1643 v->io = dm_io_client_create();
1644 if (IS_ERR(v->io)) {
1645 r = PTR_ERR(v->io);
1646 v->io = NULL;
1647 ti->error = "Cannot allocate dm io";
1648 goto bad;
1649 }
1650
1651 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1652 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1653 dm_bufio_alloc_callback, NULL,
1654 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1655 if (IS_ERR(v->bufio)) {
1656 ti->error = "Cannot initialize dm-bufio";
1657 r = PTR_ERR(v->bufio);
1658 v->bufio = NULL;
1659 goto bad;
1660 }
1661
1662 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1663 ti->error = "Hash device is too small";
1664 r = -E2BIG;
1665 goto bad;
1666 }
1667
1668 /*
1669 * Using WQ_HIGHPRI improves throughput and completion latency by
1670 * reducing wait times when reading from a dm-verity device.
1671 *
1672 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1673 * allows verify_wq to preempt softirq since verification in BH workqueue
1674 * will fall-back to using it for error handling (or if the bufio cache
1675 * doesn't have required hashes).
1676 */
1677 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1678 if (!v->verify_wq) {
1679 ti->error = "Cannot allocate workqueue";
1680 r = -ENOMEM;
1681 goto bad;
1682 }
1683
1684 ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize;
1685
1686 r = verity_fec_ctr(v);
1687 if (r)
1688 goto bad;
1689
1690 ti->per_io_data_size = roundup(ti->per_io_data_size,
1691 __alignof__(struct dm_verity_io));
1692
1693 verity_verify_sig_opts_cleanup(&verify_args);
1694
1695 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1696
1697 return 0;
1698
1699 bad:
1700
1701 verity_verify_sig_opts_cleanup(&verify_args);
1702 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1703 verity_dtr(ti);
1704
1705 return r;
1706 }
1707
1708 /*
1709 * Get the verity mode (error behavior) of a verity target.
1710 *
1711 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1712 * target.
1713 */
dm_verity_get_mode(struct dm_target * ti)1714 int dm_verity_get_mode(struct dm_target *ti)
1715 {
1716 struct dm_verity *v = ti->private;
1717
1718 if (!dm_is_verity_target(ti))
1719 return -EINVAL;
1720
1721 return v->mode;
1722 }
1723
1724 /*
1725 * Get the root digest of a verity target.
1726 *
1727 * Returns a copy of the root digest, the caller is responsible for
1728 * freeing the memory of the digest.
1729 */
dm_verity_get_root_digest(struct dm_target * ti,u8 ** root_digest,unsigned int * digest_size)1730 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1731 {
1732 struct dm_verity *v = ti->private;
1733
1734 if (!dm_is_verity_target(ti))
1735 return -EINVAL;
1736
1737 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1738 if (*root_digest == NULL)
1739 return -ENOMEM;
1740
1741 *digest_size = v->digest_size;
1742
1743 return 0;
1744 }
1745
1746 #ifdef CONFIG_SECURITY
1747
1748 #ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG
1749
verity_security_set_signature(struct block_device * bdev,struct dm_verity * v)1750 static int verity_security_set_signature(struct block_device *bdev,
1751 struct dm_verity *v)
1752 {
1753 /*
1754 * if the dm-verity target is unsigned, v->root_digest_sig will
1755 * be NULL, and the hook call is still required to let LSMs mark
1756 * the device as unsigned. This information is crucial for LSMs to
1757 * block operations such as execution on unsigned files
1758 */
1759 return security_bdev_setintegrity(bdev,
1760 LSM_INT_DMVERITY_SIG_VALID,
1761 v->root_digest_sig,
1762 v->sig_size);
1763 }
1764
1765 #else
1766
verity_security_set_signature(struct block_device * bdev,struct dm_verity * v)1767 static inline int verity_security_set_signature(struct block_device *bdev,
1768 struct dm_verity *v)
1769 {
1770 return 0;
1771 }
1772
1773 #endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */
1774
1775 /*
1776 * Expose verity target's root hash and signature data to LSMs before resume.
1777 *
1778 * Returns 0 on success, or -ENOMEM if the system is out of memory.
1779 */
verity_preresume(struct dm_target * ti)1780 static int verity_preresume(struct dm_target *ti)
1781 {
1782 struct block_device *bdev;
1783 struct dm_verity_digest root_digest;
1784 struct dm_verity *v;
1785 int r;
1786
1787 v = ti->private;
1788 bdev = dm_disk(dm_table_get_md(ti->table))->part0;
1789 root_digest.digest = v->root_digest;
1790 root_digest.digest_len = v->digest_size;
1791 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm)
1792 root_digest.alg = crypto_ahash_alg_name(v->ahash_tfm);
1793 else
1794 root_digest.alg = crypto_shash_alg_name(v->shash_tfm);
1795
1796 r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest,
1797 sizeof(root_digest));
1798 if (r)
1799 return r;
1800
1801 r = verity_security_set_signature(bdev, v);
1802 if (r)
1803 goto bad;
1804
1805 return 0;
1806
1807 bad:
1808
1809 security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0);
1810
1811 return r;
1812 }
1813
1814 #endif /* CONFIG_SECURITY */
1815
1816 static struct target_type verity_target = {
1817 .name = "verity",
1818 /* Note: the LSMs depend on the singleton and immutable features */
1819 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1820 .version = {1, 11, 0},
1821 .module = THIS_MODULE,
1822 .ctr = verity_ctr,
1823 .dtr = verity_dtr,
1824 .map = verity_map,
1825 .postsuspend = verity_postsuspend,
1826 .status = verity_status,
1827 .prepare_ioctl = verity_prepare_ioctl,
1828 .iterate_devices = verity_iterate_devices,
1829 .io_hints = verity_io_hints,
1830 #ifdef CONFIG_SECURITY
1831 .preresume = verity_preresume,
1832 #endif /* CONFIG_SECURITY */
1833 };
1834 module_dm(verity);
1835
1836 /*
1837 * Check whether a DM target is a verity target.
1838 */
dm_is_verity_target(struct dm_target * ti)1839 bool dm_is_verity_target(struct dm_target *ti)
1840 {
1841 return ti->type == &verity_target;
1842 }
1843
1844 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1845 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1846 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1847 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1848 MODULE_LICENSE("GPL");
1849