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dm: don't save and restore bi_private
[linux-2.6-block.git] / drivers / md / dm-verity.c
CommitLineData
a4ffc152
MP		 1/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
7 *
8 * This file is released under the GPLv2.
9 *
10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
12 * hash device. Setting this greatly improves performance when data and hash
13 * are on the same disk on different partitions on devices with poor random
14 * access behavior.
15 */
16
17#include "dm-bufio.h"
18
19#include <linux/module.h>
20#include <linux/device-mapper.h>
65ff5b7d 21#include <linux/reboot.h>
a4ffc152
MP		 22#include <crypto/hash.h>
23
24#define DM_MSG_PREFIX "verity"
25
65ff5b7d
ST		 26#define DM_VERITY_ENV_LENGTH 42
27#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR"
28
a4ffc152
MP		 29#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
30
31#define DM_VERITY_MAX_LEVELS 63
65ff5b7d
ST		 32#define DM_VERITY_MAX_CORRUPTED_ERRS 100
33
34#define DM_VERITY_OPT_LOGGING "ignore_corruption"
35#define DM_VERITY_OPT_RESTART "restart_on_corruption"
a4ffc152
MP		 36
37static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
38
39module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
40
65ff5b7d
ST		 41enum verity_mode {
42 DM_VERITY_MODE_EIO,
43 DM_VERITY_MODE_LOGGING,
44 DM_VERITY_MODE_RESTART
45};
46
47enum verity_block_type {
48 DM_VERITY_BLOCK_TYPE_DATA,
49 DM_VERITY_BLOCK_TYPE_METADATA
50};
51
a4ffc152
MP		 52struct dm_verity {
53 struct dm_dev *data_dev;
54 struct dm_dev *hash_dev;
55 struct dm_target *ti;
56 struct dm_bufio_client *bufio;
57 char *alg_name;
58 struct crypto_shash *tfm;
59 u8 *root_digest; /* digest of the root block */
60 u8 *salt; /* salt: its size is salt_size */
61 unsigned salt_size;
62 sector_t data_start; /* data offset in 512-byte sectors */
63 sector_t hash_start; /* hash start in blocks */
64 sector_t data_blocks; /* the number of data blocks */
65 sector_t hash_blocks; /* the number of hash blocks */
66 unsigned char data_dev_block_bits; /* log2(data blocksize) */
67 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
68 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
69 unsigned char levels; /* the number of tree levels */
70 unsigned char version;
71 unsigned digest_size; /* digest size for the current hash algorithm */
72 unsigned shash_descsize;/* the size of temporary space for crypto */
73 int hash_failed; /* set to 1 if hash of any block failed */
65ff5b7d
ST		 74 enum verity_mode mode; /* mode for handling verification errors */
75 unsigned corrupted_errs;/* Number of errors for corrupted blocks */
a4ffc152 76
a4ffc152
MP		 77 struct workqueue_struct *verify_wq;
78
79 /* starting blocks for each tree level. 0 is the lowest level. */
80 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
81};
82
83struct dm_verity_io {
84 struct dm_verity *v;
a4ffc152 85
fe3265b1 86 /* original value of bio->bi_end_io */
a4ffc152 87 bio_end_io_t *orig_bi_end_io;
a4ffc152
MP		 88
89 sector_t block;
90 unsigned n_blocks;
91
003b5c57 92 struct bvec_iter iter;
a4ffc152
MP		 93
94 struct work_struct work;
95
a4ffc152
MP		 96 /*
97 * Three variably-size fields follow this struct:
98 *
99 * u8 hash_desc[v->shash_descsize];
100 * u8 real_digest[v->digest_size];
101 * u8 want_digest[v->digest_size];
102 *
103 * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
104 */
105};
106
3b6b7813
MP		 107struct dm_verity_prefetch_work {
108 struct work_struct work;
109 struct dm_verity *v;
110 sector_t block;
111 unsigned n_blocks;
112};
113
a4ffc152
MP		 114static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
115{
116 return (struct shash_desc *)(io + 1);
117}
118
119static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
120{
121 return (u8 *)(io + 1) + v->shash_descsize;
122}
123
124static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
125{
126 return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
127}
128
129/*
130 * Auxiliary structure appended to each dm-bufio buffer. If the value
131 * hash_verified is nonzero, hash of the block has been verified.
132 *
133 * The variable hash_verified is set to 0 when allocating the buffer, then
134 * it can be changed to 1 and it is never reset to 0 again.
135 *
136 * There is no lock around this value, a race condition can at worst cause
137 * that multiple processes verify the hash of the same buffer simultaneously
138 * and write 1 to hash_verified simultaneously.
139 * This condition is harmless, so we don't need locking.
140 */
141struct buffer_aux {
142 int hash_verified;
143};
144
145/*
146 * Initialize struct buffer_aux for a freshly created buffer.
147 */
148static void dm_bufio_alloc_callback(struct dm_buffer *buf)
149{
150 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
151
152 aux->hash_verified = 0;
153}
154
155/*
156 * Translate input sector number to the sector number on the target device.
157 */
158static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
159{
160 return v->data_start + dm_target_offset(v->ti, bi_sector);
161}
162
163/*
164 * Return hash position of a specified block at a specified tree level
165 * (0 is the lowest level).
166 * The lowest "hash_per_block_bits"-bits of the result denote hash position
167 * inside a hash block. The remaining bits denote location of the hash block.
168 */
169static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
170 int level)
171{
172 return block >> (level * v->hash_per_block_bits);
173}
174
175static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
176 sector_t *hash_block, unsigned *offset)
177{
178 sector_t position = verity_position_at_level(v, block, level);
179 unsigned idx;
180
181 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
182
183 if (!offset)
184 return;
185
186 idx = position & ((1 << v->hash_per_block_bits) - 1);
187 if (!v->version)
188 *offset = idx * v->digest_size;
189 else
190 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
191}
192
65ff5b7d
ST		 193/*
194 * Handle verification errors.
195 */
196static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
197 unsigned long long block)
198{
199 char verity_env[DM_VERITY_ENV_LENGTH];
200 char *envp[] = { verity_env, NULL };
201 const char *type_str = "";
202 struct mapped_device *md = dm_table_get_md(v->ti->table);
203
204 /* Corruption should be visible in device status in all modes */
205 v->hash_failed = 1;
206
207 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
208 goto out;
209
210 v->corrupted_errs++;
211
212 switch (type) {
213 case DM_VERITY_BLOCK_TYPE_DATA:
214 type_str = "data";
215 break;
216 case DM_VERITY_BLOCK_TYPE_METADATA:
217 type_str = "metadata";
218 break;
219 default:
220 BUG();
221 }
222
223 DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
224 block);
225
226 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
227 DMERR("%s: reached maximum errors", v->data_dev->name);
228
229 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
230 DM_VERITY_ENV_VAR_NAME, type, block);
231
232 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
233
234out:
235 if (v->mode == DM_VERITY_MODE_LOGGING)
236 return 0;
237
238 if (v->mode == DM_VERITY_MODE_RESTART)
239 kernel_restart("dm-verity device corrupted");
240
241 return 1;
242}
243
a4ffc152
MP		 244/*
245 * Verify hash of a metadata block pertaining to the specified data block
246 * ("block" argument) at a specified level ("level" argument).
247 *
248 * On successful return, io_want_digest(v, io) contains the hash value for
249 * a lower tree level or for the data block (if we're at the lowest leve).
250 *
251 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
252 * If "skip_unverified" is false, unverified buffer is hashed and verified
253 * against current value of io_want_digest(v, io).
254 */
255static int verity_verify_level(struct dm_verity_io *io, sector_t block,
256 int level, bool skip_unverified)
257{
258 struct dm_verity *v = io->v;
259 struct dm_buffer *buf;
260 struct buffer_aux *aux;
261 u8 *data;
262 int r;
263 sector_t hash_block;
264 unsigned offset;
265
266 verity_hash_at_level(v, block, level, &hash_block, &offset);
267
268 data = dm_bufio_read(v->bufio, hash_block, &buf);
fc0a4461 269 if (IS_ERR(data))
a4ffc152
MP		 270 return PTR_ERR(data);
271
272 aux = dm_bufio_get_aux_data(buf);
273
274 if (!aux->hash_verified) {
275 struct shash_desc *desc;
276 u8 *result;
277
278 if (skip_unverified) {
279 r = 1;
280 goto release_ret_r;
281 }
282
283 desc = io_hash_desc(v, io);
284 desc->tfm = v->tfm;
285 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
286 r = crypto_shash_init(desc);
287 if (r < 0) {
288 DMERR("crypto_shash_init failed: %d", r);
289 goto release_ret_r;
290 }
291
292 if (likely(v->version >= 1)) {
293 r = crypto_shash_update(desc, v->salt, v->salt_size);
294 if (r < 0) {
295 DMERR("crypto_shash_update failed: %d", r);
296 goto release_ret_r;
297 }
298 }
299
300 r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
301 if (r < 0) {
302 DMERR("crypto_shash_update failed: %d", r);
303 goto release_ret_r;
304 }
305
306 if (!v->version) {
307 r = crypto_shash_update(desc, v->salt, v->salt_size);
308 if (r < 0) {
309 DMERR("crypto_shash_update failed: %d", r);
310 goto release_ret_r;
311 }
312 }
313
314 result = io_real_digest(v, io);
315 r = crypto_shash_final(desc, result);
316 if (r < 0) {
317 DMERR("crypto_shash_final failed: %d", r);
318 goto release_ret_r;
319 }
320 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
65ff5b7d
ST		 321 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_METADATA,
322 hash_block)) {
323 r = -EIO;
324 goto release_ret_r;
325 }
a4ffc152
MP		 326 } else
327 aux->hash_verified = 1;
328 }
329
330 data += offset;
331
332 memcpy(io_want_digest(v, io), data, v->digest_size);
333
334 dm_bufio_release(buf);
335 return 0;
336
337release_ret_r:
338 dm_bufio_release(buf);
339
340 return r;
341}
342
343/*
344 * Verify one "dm_verity_io" structure.
345 */
346static int verity_verify_io(struct dm_verity_io *io)
347{
348 struct dm_verity *v = io->v;
003b5c57
KO		 349 struct bio *bio = dm_bio_from_per_bio_data(io,
350 v->ti->per_bio_data_size);
a4ffc152
MP		 351 unsigned b;
352 int i;
a4ffc152
MP		 353
354 for (b = 0; b < io->n_blocks; b++) {
355 struct shash_desc *desc;
356 u8 *result;
357 int r;
358 unsigned todo;
359
360 if (likely(v->levels)) {
361 /*
362 * First, we try to get the requested hash for
363 * the current block. If the hash block itself is
364 * verified, zero is returned. If it isn't, this
365 * function returns 0 and we fall back to whole
366 * chain verification.
367 */
368 int r = verity_verify_level(io, io->block + b, 0, true);
369 if (likely(!r))
370 goto test_block_hash;
371 if (r < 0)
372 return r;
373 }
374
375 memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
376
377 for (i = v->levels - 1; i >= 0; i--) {
378 int r = verity_verify_level(io, io->block + b, i, false);
379 if (unlikely(r))
380 return r;
381 }
382
383test_block_hash:
384 desc = io_hash_desc(v, io);
385 desc->tfm = v->tfm;
386 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
387 r = crypto_shash_init(desc);
388 if (r < 0) {
389 DMERR("crypto_shash_init failed: %d", r);
390 return r;
391 }
392
393 if (likely(v->version >= 1)) {
394 r = crypto_shash_update(desc, v->salt, v->salt_size);
395 if (r < 0) {
396 DMERR("crypto_shash_update failed: %d", r);
397 return r;
398 }
399 }
a4ffc152 400 todo = 1 << v->data_dev_block_bits;
3a774521 401 do {
a4ffc152 402 u8 *page;
3a774521 403 unsigned len;
003b5c57
KO		 404 struct bio_vec bv = bio_iter_iovec(bio, io->iter);
405
406 page = kmap_atomic(bv.bv_page);
3a774521
MB		 407 len = bv.bv_len;
408 if (likely(len >= todo))
409 len = todo;
410 r = crypto_shash_update(desc, page + bv.bv_offset, len);
a4ffc152 411 kunmap_atomic(page);
003b5c57 412
a4ffc152
MP		 413 if (r < 0) {
414 DMERR("crypto_shash_update failed: %d", r);
415 return r;
416 }
003b5c57 417
3a774521
MB		 418 bio_advance_iter(bio, &io->iter, len);
419 todo -= len;
420 } while (todo);
a4ffc152
MP		 421
422 if (!v->version) {
423 r = crypto_shash_update(desc, v->salt, v->salt_size);
424 if (r < 0) {
425 DMERR("crypto_shash_update failed: %d", r);
426 return r;
427 }
428 }
429
430 result = io_real_digest(v, io);
431 r = crypto_shash_final(desc, result);
432 if (r < 0) {
433 DMERR("crypto_shash_final failed: %d", r);
434 return r;
435 }
436 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
65ff5b7d
ST		 437 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
438 io->block + b))
439 return -EIO;
a4ffc152
MP		 440 }
441 }
a4ffc152
MP		 442
443 return 0;
444}
445
446/*
447 * End one "io" structure with a given error.
448 */
449static void verity_finish_io(struct dm_verity_io *io, int error)
450{
a4ffc152 451 struct dm_verity *v = io->v;
e42c3f91 452 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
a4ffc152
MP		 453
454 bio->bi_end_io = io->orig_bi_end_io;
4246a0b6 455 bio->bi_error = error;
a4ffc152 456
4246a0b6 457 bio_endio(bio);
a4ffc152
MP		 458}
459
460static void verity_work(struct work_struct *w)
461{
462 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
463
464 verity_finish_io(io, verity_verify_io(io));
465}
466
4246a0b6 467static void verity_end_io(struct bio *bio)
a4ffc152
MP		 468{
469 struct dm_verity_io *io = bio->bi_private;
470
4246a0b6
CH		 471 if (bio->bi_error) {
472 verity_finish_io(io, bio->bi_error);
a4ffc152
MP		 473 return;
474 }
475
476 INIT_WORK(&io->work, verity_work);
477 queue_work(io->v->verify_wq, &io->work);
478}
479
480/*
481 * Prefetch buffers for the specified io.
482 * The root buffer is not prefetched, it is assumed that it will be cached
483 * all the time.
484 */
3b6b7813 485static void verity_prefetch_io(struct work_struct *work)
a4ffc152 486{
3b6b7813
MP		 487 struct dm_verity_prefetch_work *pw =
488 container_of(work, struct dm_verity_prefetch_work, work);
489 struct dm_verity *v = pw->v;
a4ffc152
MP		 490 int i;
491
492 for (i = v->levels - 2; i >= 0; i--) {
493 sector_t hash_block_start;
494 sector_t hash_block_end;
3b6b7813
MP		 495 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
496 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
a4ffc152 497 if (!i) {
fe5fe906 498 unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
a4ffc152
MP		 499
500 cluster >>= v->data_dev_block_bits;
501 if (unlikely(!cluster))
502 goto no_prefetch_cluster;
503
504 if (unlikely(cluster & (cluster - 1)))
553d8fe0 505 cluster = 1 << __fls(cluster);
a4ffc152
MP		 506
507 hash_block_start &= ~(sector_t)(cluster - 1);
508 hash_block_end |= cluster - 1;
509 if (unlikely(hash_block_end >= v->hash_blocks))
510 hash_block_end = v->hash_blocks - 1;
511 }
512no_prefetch_cluster:
513 dm_bufio_prefetch(v->bufio, hash_block_start,
514 hash_block_end - hash_block_start + 1);
515 }
3b6b7813
MP		 516
517 kfree(pw);
518}
519
520static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
521{
522 struct dm_verity_prefetch_work *pw;
523
524 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
525 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
526
527 if (!pw)
528 return;
529
530 INIT_WORK(&pw->work, verity_prefetch_io);
531 pw->v = v;
532 pw->block = io->block;
533 pw->n_blocks = io->n_blocks;
534 queue_work(v->verify_wq, &pw->work);
a4ffc152
MP		 535}
536
537/*
538 * Bio map function. It allocates dm_verity_io structure and bio vector and
539 * fills them. Then it issues prefetches and the I/O.
540 */
7de3ee57 541static int verity_map(struct dm_target *ti, struct bio *bio)
a4ffc152
MP		 542{
543 struct dm_verity *v = ti->private;
544 struct dm_verity_io *io;
545
546 bio->bi_bdev = v->data_dev->bdev;
4f024f37 547 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
a4ffc152 548
4f024f37 549 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
a4ffc152
MP		 550 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
551 DMERR_LIMIT("unaligned io");
552 return -EIO;
553 }
554
f73a1c7d 555 if (bio_end_sector(bio) >>
a4ffc152
MP		 556 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
557 DMERR_LIMIT("io out of range");
558 return -EIO;
559 }
560
561 if (bio_data_dir(bio) == WRITE)
562 return -EIO;
563
e42c3f91 564 io = dm_per_bio_data(bio, ti->per_bio_data_size);
a4ffc152 565 io->v = v;
a4ffc152 566 io->orig_bi_end_io = bio->bi_end_io;
4f024f37
KO		 567 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
568 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
a4ffc152
MP		 569
570 bio->bi_end_io = verity_end_io;
571 bio->bi_private = io;
003b5c57 572 io->iter = bio->bi_iter;
a4ffc152 573
3b6b7813 574 verity_submit_prefetch(v, io);
a4ffc152
MP		 575
576 generic_make_request(bio);
577
578 return DM_MAPIO_SUBMITTED;
579}
580
581/*
582 * Status: V (valid) or C (corruption found)
583 */
fd7c092e
MP		 584static void verity_status(struct dm_target *ti, status_type_t type,
585 unsigned status_flags, char *result, unsigned maxlen)
a4ffc152
MP		 586{
587 struct dm_verity *v = ti->private;
588 unsigned sz = 0;
589 unsigned x;
590
591 switch (type) {
592 case STATUSTYPE_INFO:
593 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
594 break;
595 case STATUSTYPE_TABLE:
596 DMEMIT("%u %s %s %u %u %llu %llu %s ",
597 v->version,
598 v->data_dev->name,
599 v->hash_dev->name,
600 1 << v->data_dev_block_bits,
601 1 << v->hash_dev_block_bits,
602 (unsigned long long)v->data_blocks,
603 (unsigned long long)v->hash_start,
604 v->alg_name
605 );
606 for (x = 0; x < v->digest_size; x++)
607 DMEMIT("%02x", v->root_digest[x]);
608 DMEMIT(" ");
609 if (!v->salt_size)
610 DMEMIT("-");
611 else
612 for (x = 0; x < v->salt_size; x++)
613 DMEMIT("%02x", v->salt[x]);
65ff5b7d
ST		 614 if (v->mode != DM_VERITY_MODE_EIO) {
615 DMEMIT(" 1 ");
616 switch (v->mode) {
617 case DM_VERITY_MODE_LOGGING:
618 DMEMIT(DM_VERITY_OPT_LOGGING);
619 break;
620 case DM_VERITY_MODE_RESTART:
621 DMEMIT(DM_VERITY_OPT_RESTART);
622 break;
623 default:
624 BUG();
625 }
626 }
a4ffc152
MP		 627 break;
628 }
a4ffc152
MP		 629}
630
e56f81e0
CH		 631static int verity_prepare_ioctl(struct dm_target *ti,
632 struct block_device **bdev, fmode_t *mode)
a4ffc152
MP		 633{
634 struct dm_verity *v = ti->private;
e56f81e0
CH		 635
636 *bdev = v->data_dev->bdev;
a4ffc152
MP		 637
638 if (v->data_start ||
639 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
e56f81e0
CH		 640 return 1;
641 return 0;
a4ffc152
MP		 642}
643
a4ffc152
MP		 644static int verity_iterate_devices(struct dm_target *ti,
645 iterate_devices_callout_fn fn, void *data)
646{
647 struct dm_verity *v = ti->private;
648
649 return fn(ti, v->data_dev, v->data_start, ti->len, data);
650}
651
652static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
653{
654 struct dm_verity *v = ti->private;
655
656 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
657 limits->logical_block_size = 1 << v->data_dev_block_bits;
658
659 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
660 limits->physical_block_size = 1 << v->data_dev_block_bits;
661
662 blk_limits_io_min(limits, limits->logical_block_size);
663}
664
665static void verity_dtr(struct dm_target *ti)
666{
667 struct dm_verity *v = ti->private;
668
669 if (v->verify_wq)
670 destroy_workqueue(v->verify_wq);
671
a4ffc152
MP		 672 if (v->bufio)
673 dm_bufio_client_destroy(v->bufio);
674
675 kfree(v->salt);
676 kfree(v->root_digest);
677
678 if (v->tfm)
679 crypto_free_shash(v->tfm);
680
681 kfree(v->alg_name);
682
683 if (v->hash_dev)
684 dm_put_device(ti, v->hash_dev);
685
686 if (v->data_dev)
687 dm_put_device(ti, v->data_dev);
688
689 kfree(v);
690}
691
692/*
693 * Target parameters:
694 * <version> The current format is version 1.
695 * Vsn 0 is compatible with original Chromium OS releases.
696 * <data device>
697 * <hash device>
698 * <data block size>
699 * <hash block size>
700 * <the number of data blocks>
701 * <hash start block>
702 * <algorithm>
703 * <digest>
704 * <salt> Hex string or "-" if no salt.
705 */
706static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
707{
708 struct dm_verity *v;
65ff5b7d
ST		 709 struct dm_arg_set as;
710 const char *opt_string;
711 unsigned int num, opt_params;
a4ffc152
MP		 712 unsigned long long num_ll;
713 int r;
714 int i;
715 sector_t hash_position;
716 char dummy;
717
65ff5b7d
ST		 718 static struct dm_arg _args[] = {
719 {0, 1, "Invalid number of feature args"},
720 };
721
a4ffc152
MP		 722 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
723 if (!v) {
724 ti->error = "Cannot allocate verity structure";
725 return -ENOMEM;
726 }
727 ti->private = v;
728 v->ti = ti;
729
730 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
731 ti->error = "Device must be readonly";
732 r = -EINVAL;
733 goto bad;
734 }
735
65ff5b7d
ST		 736 if (argc < 10) {
737 ti->error = "Not enough arguments";
a4ffc152
MP		 738 r = -EINVAL;
739 goto bad;
740 }
741
5d8be843
MP		 742 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
743 num > 1) {
a4ffc152
MP		 744 ti->error = "Invalid version";
745 r = -EINVAL;
746 goto bad;
747 }
748 v->version = num;
749
750 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
751 if (r) {
752 ti->error = "Data device lookup failed";
753 goto bad;
754 }
755
756 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
757 if (r) {
758 ti->error = "Data device lookup failed";
759 goto bad;
760 }
761
762 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
763 !num || (num & (num - 1)) ||
764 num < bdev_logical_block_size(v->data_dev->bdev) ||
765 num > PAGE_SIZE) {
766 ti->error = "Invalid data device block size";
767 r = -EINVAL;
768 goto bad;
769 }
553d8fe0 770 v->data_dev_block_bits = __ffs(num);
a4ffc152
MP		 771
772 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
773 !num || (num & (num - 1)) ||
774 num < bdev_logical_block_size(v->hash_dev->bdev) ||
775 num > INT_MAX) {
776 ti->error = "Invalid hash device block size";
777 r = -EINVAL;
778 goto bad;
779 }
553d8fe0 780 v->hash_dev_block_bits = __ffs(num);
a4ffc152
MP		 781
782 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1d55f6bc
MP		 783 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
784 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
a4ffc152
MP		 785 ti->error = "Invalid data blocks";
786 r = -EINVAL;
787 goto bad;
788 }
789 v->data_blocks = num_ll;
790
791 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
792 ti->error = "Data device is too small";
793 r = -EINVAL;
794 goto bad;
795 }
796
797 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1d55f6bc
MP		 798 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
799 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
a4ffc152
MP		 800 ti->error = "Invalid hash start";
801 r = -EINVAL;
802 goto bad;
803 }
804 v->hash_start = num_ll;
805
806 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
807 if (!v->alg_name) {
808 ti->error = "Cannot allocate algorithm name";
809 r = -ENOMEM;
810 goto bad;
811 }
812
813 v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
814 if (IS_ERR(v->tfm)) {
815 ti->error = "Cannot initialize hash function";
816 r = PTR_ERR(v->tfm);
817 v->tfm = NULL;
818 goto bad;
819 }
820 v->digest_size = crypto_shash_digestsize(v->tfm);
821 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
822 ti->error = "Digest size too big";
823 r = -EINVAL;
824 goto bad;
825 }
826 v->shash_descsize =
827 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
828
829 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
830 if (!v->root_digest) {
831 ti->error = "Cannot allocate root digest";
832 r = -ENOMEM;
833 goto bad;
834 }
835 if (strlen(argv[8]) != v->digest_size * 2 ||
836 hex2bin(v->root_digest, argv[8], v->digest_size)) {
837 ti->error = "Invalid root digest";
838 r = -EINVAL;
839 goto bad;
840 }
841
842 if (strcmp(argv[9], "-")) {
843 v->salt_size = strlen(argv[9]) / 2;
844 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
845 if (!v->salt) {
846 ti->error = "Cannot allocate salt";
847 r = -ENOMEM;
848 goto bad;
849 }
850 if (strlen(argv[9]) != v->salt_size * 2 ||
851 hex2bin(v->salt, argv[9], v->salt_size)) {
852 ti->error = "Invalid salt";
853 r = -EINVAL;
854 goto bad;
855 }
856 }
857
65ff5b7d
ST		 858 argv += 10;
859 argc -= 10;
860
861 /* Optional parameters */
862 if (argc) {
863 as.argc = argc;
864 as.argv = argv;
865
866 r = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
867 if (r)
868 goto bad;
869
870 while (opt_params) {
871 opt_params--;
872 opt_string = dm_shift_arg(&as);
873 if (!opt_string) {
874 ti->error = "Not enough feature arguments";
875 r = -EINVAL;
876 goto bad;
877 }
878
879 if (!strcasecmp(opt_string, DM_VERITY_OPT_LOGGING))
880 v->mode = DM_VERITY_MODE_LOGGING;
881 else if (!strcasecmp(opt_string, DM_VERITY_OPT_RESTART))
882 v->mode = DM_VERITY_MODE_RESTART;
883 else {
884 ti->error = "Invalid feature arguments";
885 r = -EINVAL;
886 goto bad;
887 }
888 }
889 }
890
a4ffc152 891 v->hash_per_block_bits =
553d8fe0 892 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
a4ffc152
MP		 893
894 v->levels = 0;
895 if (v->data_blocks)
896 while (v->hash_per_block_bits * v->levels < 64 &&
897 (unsigned long long)(v->data_blocks - 1) >>
898 (v->hash_per_block_bits * v->levels))
899 v->levels++;
900
901 if (v->levels > DM_VERITY_MAX_LEVELS) {
902 ti->error = "Too many tree levels";
903 r = -E2BIG;
904 goto bad;
905 }
906
907 hash_position = v->hash_start;
908 for (i = v->levels - 1; i >= 0; i--) {
909 sector_t s;
910 v->hash_level_block[i] = hash_position;
b1bf2de0
MP		 911 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
912 >> ((i + 1) * v->hash_per_block_bits);
a4ffc152
MP		 913 if (hash_position + s < hash_position) {
914 ti->error = "Hash device offset overflow";
915 r = -E2BIG;
916 goto bad;
917 }
918 hash_position += s;
919 }
920 v->hash_blocks = hash_position;
921
922 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
923 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
924 dm_bufio_alloc_callback, NULL);
925 if (IS_ERR(v->bufio)) {
926 ti->error = "Cannot initialize dm-bufio";
927 r = PTR_ERR(v->bufio);
928 v->bufio = NULL;
929 goto bad;
930 }
931
932 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
933 ti->error = "Hash device is too small";
934 r = -E2BIG;
935 goto bad;
936 }
937
e42c3f91 938 ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
a4ffc152 939
a4ffc152
MP		 940 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
941 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
942 if (!v->verify_wq) {
943 ti->error = "Cannot allocate workqueue";
944 r = -ENOMEM;
945 goto bad;
946 }
947
948 return 0;
949
950bad:
951 verity_dtr(ti);
952
953 return r;
954}
955
956static struct target_type verity_target = {
957 .name = "verity",
3b6b7813 958 .version = {1, 2, 0},
a4ffc152
MP		 959 .module = THIS_MODULE,
960 .ctr = verity_ctr,
961 .dtr = verity_dtr,
962 .map = verity_map,
963 .status = verity_status,
e56f81e0 964 .prepare_ioctl = verity_prepare_ioctl,
a4ffc152
MP		 965 .iterate_devices = verity_iterate_devices,
966 .io_hints = verity_io_hints,
967};
968
969static int __init dm_verity_init(void)
970{
971 int r;
972
973 r = dm_register_target(&verity_target);
974 if (r < 0)
975 DMERR("register failed %d", r);
976
977 return r;
978}
979
980static void __exit dm_verity_exit(void)
981{
982 dm_unregister_target(&verity_target);
983}
984
985module_init(dm_verity_init);
986module_exit(dm_verity_exit);
987
988MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
989MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
990MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
991MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
992MODULE_LICENSE("GPL");
Linux 6.x block layer and io_uring tree(s)