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