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
48 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
49
50 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
51
52 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
53
54 /* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
55 static DEFINE_STATIC_KEY_FALSE(ahash_enabled);
56
57 struct 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 */
77 struct buffer_aux {
78 int hash_verified;
79 };
80
81 /*
82 * Initialize struct buffer_aux for a freshly created buffer.
83 */
dm_bufio_alloc_callback(struct dm_buffer * buf)84 static 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 */
verity_map_sector(struct dm_verity * v,sector_t bi_sector)94 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
95 {
96 return v->data_start + 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 */
verity_position_at_level(struct dm_verity * v,sector_t block,int level)105 static 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
verity_ahash_update(struct dm_verity * v,struct ahash_request * req,const u8 * data,size_t len,struct crypto_wait * wait)111 static 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 */
verity_ahash_init(struct dm_verity * v,struct ahash_request * req,struct crypto_wait * wait,bool may_sleep)144 static 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
verity_ahash_final(struct dm_verity * v,struct ahash_request * req,u8 * digest,struct crypto_wait * wait)169 static 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);
185 out:
186 return r;
187 }
188
verity_hash(struct dm_verity * v,struct dm_verity_io * io,const u8 * data,size_t len,u8 * digest,bool may_sleep)189 int 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
verity_hash_at_level(struct dm_verity * v,sector_t block,int level,sector_t * hash_block,unsigned int * offset)213 static 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 */
verity_handle_err(struct dm_verity * v,enum verity_block_type type,unsigned long long block)234 static 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
274 out:
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 */
verity_verify_level(struct dm_verity * v,struct dm_verity_io * io,sector_t block,int level,bool skip_unverified,u8 * want_digest)298 static 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
373 release_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 */
verity_hash_for_block(struct dm_verity * v,struct dm_verity_io * io,sector_t block,u8 * digest,bool * is_zero)382 int 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 }
407 out:
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
verity_recheck(struct dm_verity * v,struct dm_verity_io * io,sector_t cur_block,u8 * dest)416 static 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;
453 free_ret:
454 mempool_free(page, &v->recheck_pool);
455
456 return r;
457 }
458
verity_handle_data_hash_mismatch(struct dm_verity * v,struct dm_verity_io * io,struct bio * bio,sector_t blkno,u8 * data)459 static 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 */
verity_verify_io(struct dm_verity_io * io)495 static 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 */
verity_is_system_shutting_down(void)583 static 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
restart_io_error(struct work_struct * w)589 static 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 */
verity_finish_io(struct dm_verity_io * io,blk_status_t status)597 static 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
verity_work(struct work_struct * w)629 static 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
verity_bh_work(struct work_struct * w)638 static 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
verity_end_io(struct bio * bio)655 static 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 */
verity_prefetch_io(struct work_struct * work)681 static 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 }
710 no_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
verity_submit_prefetch(struct dm_verity * v,struct dm_verity_io * io,unsigned short ioprio)719 static 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 */
verity_map(struct dm_target * ti,struct bio * bio)756 static 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 */
verity_status(struct dm_target * ti,status_type_t type,unsigned int status_flags,char * result,unsigned int maxlen)802 static 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
verity_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev)949 static 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 (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
956 return 1;
957 return 0;
958 }
959
verity_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)960 static 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, v->data_start, ti->len, data);
966 }
967
verity_io_hints(struct dm_target * ti,struct queue_limits * limits)968 static 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
verity_init_sig(struct dm_verity * v,const void * sig,size_t sig_size)991 static 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
verity_free_sig(struct dm_verity * v)1005 static void verity_free_sig(struct dm_verity *v)
1006 {
1007 kfree(v->root_digest_sig);
1008 }
1009
1010 #else
1011
verity_init_sig(struct dm_verity * v,const void * sig,size_t sig_size)1012 static inline int verity_init_sig(struct dm_verity *v, const void *sig,
1013 size_t sig_size)
1014 {
1015 return 0;
1016 }
1017
verity_free_sig(struct dm_verity * v)1018 static inline void verity_free_sig(struct dm_verity *v)
1019 {
1020 }
1021
1022 #endif /* CONFIG_SECURITY */
1023
verity_dtr(struct dm_target * ti)1024 static 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
verity_alloc_most_once(struct dm_verity * v)1072 static 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
verity_alloc_zero_digest(struct dm_verity * v)1093 static 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
1117 out:
1118 kfree(io);
1119 kfree(zero_data);
1120
1121 return r;
1122 }
1123
verity_is_verity_mode(const char * arg_name)1124 static 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
verity_parse_verity_mode(struct dm_verity * v,const char * arg_name)1131 static 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
verity_is_verity_error_mode(const char * arg_name)1146 static 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
verity_parse_verity_error_mode(struct dm_verity * v,const char * arg_name)1152 static 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
verity_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,struct dm_verity_sig_opts * verify_args,bool only_modifier_opts)1165 static 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
verity_setup_hash_alg(struct dm_verity * v,const char * alg_name)1268 static 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
verity_setup_salt_and_hashstate(struct dm_verity * v,const char * arg)1332 static 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 */
verity_ctr(struct dm_target * ti,unsigned int argc,char ** argv)1389 static 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
1643 bad:
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 */
dm_verity_get_mode(struct dm_target * ti)1658 int 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 */
dm_verity_get_root_digest(struct dm_target * ti,u8 ** root_digest,unsigned int * digest_size)1674 int 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
verity_security_set_signature(struct block_device * bdev,struct dm_verity * v)1694 static 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
verity_security_set_signature(struct block_device * bdev,struct dm_verity * v)1711 static 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 */
verity_preresume(struct dm_target * ti)1724 static 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
1751 bad:
1752
1753 security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0);
1754
1755 return r;
1756 }
1757
1758 #endif /* CONFIG_SECURITY */
1759
1760 static 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 };
1777 module_dm(verity);
1778
1779 /*
1780 * Check whether a DM target is a verity target.
1781 */
dm_is_verity_target(struct dm_target * ti)1782 bool dm_is_verity_target(struct dm_target *ti)
1783 {
1784 return ti->type == &verity_target;
1785 }
1786
1787 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1788 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1789 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1790 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1791 MODULE_LICENSE("GPL");
1792