GNU Linux-libre 4.19.264-gnu1
[releases.git] / drivers / md / dm-verity-target.c
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-verity.h"
18 #include "dm-verity-fec.h"
19
20 #include <linux/module.h>
21 #include <linux/reboot.h>
22
23 #define DM_MSG_PREFIX                   "verity"
24
25 #define DM_VERITY_ENV_LENGTH            42
26 #define DM_VERITY_ENV_VAR_NAME          "DM_VERITY_ERR_BLOCK_NR"
27
28 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
29
30 #define DM_VERITY_MAX_CORRUPTED_ERRS    100
31
32 #define DM_VERITY_OPT_LOGGING           "ignore_corruption"
33 #define DM_VERITY_OPT_RESTART           "restart_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
39 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
40
41 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
42
43 struct dm_verity_prefetch_work {
44         struct work_struct work;
45         struct dm_verity *v;
46         sector_t block;
47         unsigned n_blocks;
48 };
49
50 /*
51  * Auxiliary structure appended to each dm-bufio buffer. If the value
52  * hash_verified is nonzero, hash of the block has been verified.
53  *
54  * The variable hash_verified is set to 0 when allocating the buffer, then
55  * it can be changed to 1 and it is never reset to 0 again.
56  *
57  * There is no lock around this value, a race condition can at worst cause
58  * that multiple processes verify the hash of the same buffer simultaneously
59  * and write 1 to hash_verified simultaneously.
60  * This condition is harmless, so we don't need locking.
61  */
62 struct buffer_aux {
63         int hash_verified;
64 };
65
66 /*
67  * Initialize struct buffer_aux for a freshly created buffer.
68  */
69 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
70 {
71         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
72
73         aux->hash_verified = 0;
74 }
75
76 /*
77  * Translate input sector number to the sector number on the target device.
78  */
79 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
80 {
81         return v->data_start + dm_target_offset(v->ti, bi_sector);
82 }
83
84 /*
85  * Return hash position of a specified block at a specified tree level
86  * (0 is the lowest level).
87  * The lowest "hash_per_block_bits"-bits of the result denote hash position
88  * inside a hash block. The remaining bits denote location of the hash block.
89  */
90 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
91                                          int level)
92 {
93         return block >> (level * v->hash_per_block_bits);
94 }
95
96 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
97                                 const u8 *data, size_t len,
98                                 struct crypto_wait *wait)
99 {
100         struct scatterlist sg;
101
102         if (likely(!is_vmalloc_addr(data))) {
103                 sg_init_one(&sg, data, len);
104                 ahash_request_set_crypt(req, &sg, NULL, len);
105                 return crypto_wait_req(crypto_ahash_update(req), wait);
106         } else {
107                 do {
108                         int r;
109                         size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
110                         flush_kernel_vmap_range((void *)data, this_step);
111                         sg_init_table(&sg, 1);
112                         sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
113                         ahash_request_set_crypt(req, &sg, NULL, this_step);
114                         r = crypto_wait_req(crypto_ahash_update(req), wait);
115                         if (unlikely(r))
116                                 return r;
117                         data += this_step;
118                         len -= this_step;
119                 } while (len);
120                 return 0;
121         }
122 }
123
124 /*
125  * Wrapper for crypto_ahash_init, which handles verity salting.
126  */
127 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
128                                 struct crypto_wait *wait)
129 {
130         int r;
131
132         ahash_request_set_tfm(req, v->tfm);
133         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
134                                         CRYPTO_TFM_REQ_MAY_BACKLOG,
135                                         crypto_req_done, (void *)wait);
136         crypto_init_wait(wait);
137
138         r = crypto_wait_req(crypto_ahash_init(req), wait);
139
140         if (unlikely(r < 0)) {
141                 DMERR("crypto_ahash_init failed: %d", r);
142                 return r;
143         }
144
145         if (likely(v->salt_size && (v->version >= 1)))
146                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
147
148         return r;
149 }
150
151 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
152                              u8 *digest, struct crypto_wait *wait)
153 {
154         int r;
155
156         if (unlikely(v->salt_size && (!v->version))) {
157                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
158
159                 if (r < 0) {
160                         DMERR("verity_hash_final failed updating salt: %d", r);
161                         goto out;
162                 }
163         }
164
165         ahash_request_set_crypt(req, NULL, digest, 0);
166         r = crypto_wait_req(crypto_ahash_final(req), wait);
167 out:
168         return r;
169 }
170
171 int verity_hash(struct dm_verity *v, struct ahash_request *req,
172                 const u8 *data, size_t len, u8 *digest)
173 {
174         int r;
175         struct crypto_wait wait;
176
177         r = verity_hash_init(v, req, &wait);
178         if (unlikely(r < 0))
179                 goto out;
180
181         r = verity_hash_update(v, req, data, len, &wait);
182         if (unlikely(r < 0))
183                 goto out;
184
185         r = verity_hash_final(v, req, digest, &wait);
186
187 out:
188         return r;
189 }
190
191 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
192                                  sector_t *hash_block, unsigned *offset)
193 {
194         sector_t position = verity_position_at_level(v, block, level);
195         unsigned idx;
196
197         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
198
199         if (!offset)
200                 return;
201
202         idx = position & ((1 << v->hash_per_block_bits) - 1);
203         if (!v->version)
204                 *offset = idx * v->digest_size;
205         else
206                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
207 }
208
209 /*
210  * Handle verification errors.
211  */
212 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
213                              unsigned long long block)
214 {
215         char verity_env[DM_VERITY_ENV_LENGTH];
216         char *envp[] = { verity_env, NULL };
217         const char *type_str = "";
218         struct mapped_device *md = dm_table_get_md(v->ti->table);
219
220         /* Corruption should be visible in device status in all modes */
221         v->hash_failed = 1;
222
223         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
224                 goto out;
225
226         v->corrupted_errs++;
227
228         switch (type) {
229         case DM_VERITY_BLOCK_TYPE_DATA:
230                 type_str = "data";
231                 break;
232         case DM_VERITY_BLOCK_TYPE_METADATA:
233                 type_str = "metadata";
234                 break;
235         default:
236                 BUG();
237         }
238
239         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
240                     type_str, block);
241
242         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
243                 DMERR("%s: reached maximum errors", v->data_dev->name);
244
245         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
246                 DM_VERITY_ENV_VAR_NAME, type, block);
247
248         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
249
250 out:
251         if (v->mode == DM_VERITY_MODE_LOGGING)
252                 return 0;
253
254         if (v->mode == DM_VERITY_MODE_RESTART)
255                 kernel_restart("dm-verity device corrupted");
256
257         return 1;
258 }
259
260 /*
261  * Verify hash of a metadata block pertaining to the specified data block
262  * ("block" argument) at a specified level ("level" argument).
263  *
264  * On successful return, verity_io_want_digest(v, io) contains the hash value
265  * for a lower tree level or for the data block (if we're at the lowest level).
266  *
267  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
268  * If "skip_unverified" is false, unverified buffer is hashed and verified
269  * against current value of verity_io_want_digest(v, io).
270  */
271 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
272                                sector_t block, int level, bool skip_unverified,
273                                u8 *want_digest)
274 {
275         struct dm_buffer *buf;
276         struct buffer_aux *aux;
277         u8 *data;
278         int r;
279         sector_t hash_block;
280         unsigned offset;
281
282         verity_hash_at_level(v, block, level, &hash_block, &offset);
283
284         data = dm_bufio_read(v->bufio, hash_block, &buf);
285         if (IS_ERR(data))
286                 return PTR_ERR(data);
287
288         aux = dm_bufio_get_aux_data(buf);
289
290         if (!aux->hash_verified) {
291                 if (skip_unverified) {
292                         r = 1;
293                         goto release_ret_r;
294                 }
295
296                 r = verity_hash(v, verity_io_hash_req(v, io),
297                                 data, 1 << v->hash_dev_block_bits,
298                                 verity_io_real_digest(v, io));
299                 if (unlikely(r < 0))
300                         goto release_ret_r;
301
302                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
303                                   v->digest_size) == 0))
304                         aux->hash_verified = 1;
305                 else if (verity_fec_decode(v, io,
306                                            DM_VERITY_BLOCK_TYPE_METADATA,
307                                            hash_block, data, NULL) == 0)
308                         aux->hash_verified = 1;
309                 else if (verity_handle_err(v,
310                                            DM_VERITY_BLOCK_TYPE_METADATA,
311                                            hash_block)) {
312                         r = -EIO;
313                         goto release_ret_r;
314                 }
315         }
316
317         data += offset;
318         memcpy(want_digest, data, v->digest_size);
319         r = 0;
320
321 release_ret_r:
322         dm_bufio_release(buf);
323         return r;
324 }
325
326 /*
327  * Find a hash for a given block, write it to digest and verify the integrity
328  * of the hash tree if necessary.
329  */
330 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
331                           sector_t block, u8 *digest, bool *is_zero)
332 {
333         int r = 0, i;
334
335         if (likely(v->levels)) {
336                 /*
337                  * First, we try to get the requested hash for
338                  * the current block. If the hash block itself is
339                  * verified, zero is returned. If it isn't, this
340                  * function returns 1 and we fall back to whole
341                  * chain verification.
342                  */
343                 r = verity_verify_level(v, io, block, 0, true, digest);
344                 if (likely(r <= 0))
345                         goto out;
346         }
347
348         memcpy(digest, v->root_digest, v->digest_size);
349
350         for (i = v->levels - 1; i >= 0; i--) {
351                 r = verity_verify_level(v, io, block, i, false, digest);
352                 if (unlikely(r))
353                         goto out;
354         }
355 out:
356         if (!r && v->zero_digest)
357                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
358         else
359                 *is_zero = false;
360
361         return r;
362 }
363
364 /*
365  * Calculates the digest for the given bio
366  */
367 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
368                                struct bvec_iter *iter, struct crypto_wait *wait)
369 {
370         unsigned int todo = 1 << v->data_dev_block_bits;
371         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
372         struct scatterlist sg;
373         struct ahash_request *req = verity_io_hash_req(v, io);
374
375         do {
376                 int r;
377                 unsigned int len;
378                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
379
380                 sg_init_table(&sg, 1);
381
382                 len = bv.bv_len;
383
384                 if (likely(len >= todo))
385                         len = todo;
386                 /*
387                  * Operating on a single page at a time looks suboptimal
388                  * until you consider the typical block size is 4,096B.
389                  * Going through this loops twice should be very rare.
390                  */
391                 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
392                 ahash_request_set_crypt(req, &sg, NULL, len);
393                 r = crypto_wait_req(crypto_ahash_update(req), wait);
394
395                 if (unlikely(r < 0)) {
396                         DMERR("verity_for_io_block crypto op failed: %d", r);
397                         return r;
398                 }
399
400                 bio_advance_iter(bio, iter, len);
401                 todo -= len;
402         } while (todo);
403
404         return 0;
405 }
406
407 /*
408  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
409  * starting from iter.
410  */
411 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
412                         struct bvec_iter *iter,
413                         int (*process)(struct dm_verity *v,
414                                        struct dm_verity_io *io, u8 *data,
415                                        size_t len))
416 {
417         unsigned todo = 1 << v->data_dev_block_bits;
418         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
419
420         do {
421                 int r;
422                 u8 *page;
423                 unsigned len;
424                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
425
426                 page = kmap_atomic(bv.bv_page);
427                 len = bv.bv_len;
428
429                 if (likely(len >= todo))
430                         len = todo;
431
432                 r = process(v, io, page + bv.bv_offset, len);
433                 kunmap_atomic(page);
434
435                 if (r < 0)
436                         return r;
437
438                 bio_advance_iter(bio, iter, len);
439                 todo -= len;
440         } while (todo);
441
442         return 0;
443 }
444
445 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
446                           u8 *data, size_t len)
447 {
448         memset(data, 0, len);
449         return 0;
450 }
451
452 /*
453  * Moves the bio iter one data block forward.
454  */
455 static inline void verity_bv_skip_block(struct dm_verity *v,
456                                         struct dm_verity_io *io,
457                                         struct bvec_iter *iter)
458 {
459         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
460
461         bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
462 }
463
464 /*
465  * Verify one "dm_verity_io" structure.
466  */
467 static int verity_verify_io(struct dm_verity_io *io)
468 {
469         bool is_zero;
470         struct dm_verity *v = io->v;
471         struct bvec_iter start;
472         unsigned b;
473         struct crypto_wait wait;
474
475         for (b = 0; b < io->n_blocks; b++) {
476                 int r;
477                 sector_t cur_block = io->block + b;
478                 struct ahash_request *req = verity_io_hash_req(v, io);
479
480                 if (v->validated_blocks &&
481                     likely(test_bit(cur_block, v->validated_blocks))) {
482                         verity_bv_skip_block(v, io, &io->iter);
483                         continue;
484                 }
485
486                 r = verity_hash_for_block(v, io, cur_block,
487                                           verity_io_want_digest(v, io),
488                                           &is_zero);
489                 if (unlikely(r < 0))
490                         return r;
491
492                 if (is_zero) {
493                         /*
494                          * If we expect a zero block, don't validate, just
495                          * return zeros.
496                          */
497                         r = verity_for_bv_block(v, io, &io->iter,
498                                                 verity_bv_zero);
499                         if (unlikely(r < 0))
500                                 return r;
501
502                         continue;
503                 }
504
505                 r = verity_hash_init(v, req, &wait);
506                 if (unlikely(r < 0))
507                         return r;
508
509                 start = io->iter;
510                 r = verity_for_io_block(v, io, &io->iter, &wait);
511                 if (unlikely(r < 0))
512                         return r;
513
514                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
515                                         &wait);
516                 if (unlikely(r < 0))
517                         return r;
518
519                 if (likely(memcmp(verity_io_real_digest(v, io),
520                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
521                         if (v->validated_blocks)
522                                 set_bit(cur_block, v->validated_blocks);
523                         continue;
524                 }
525                 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
526                                            cur_block, NULL, &start) == 0)
527                         continue;
528                 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
529                                            cur_block))
530                         return -EIO;
531         }
532
533         return 0;
534 }
535
536 /*
537  * Skip verity work in response to I/O error when system is shutting down.
538  */
539 static inline bool verity_is_system_shutting_down(void)
540 {
541         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
542                 || system_state == SYSTEM_RESTART;
543 }
544
545 /*
546  * End one "io" structure with a given error.
547  */
548 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
549 {
550         struct dm_verity *v = io->v;
551         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
552
553         bio->bi_end_io = io->orig_bi_end_io;
554         bio->bi_status = status;
555
556         verity_fec_finish_io(io);
557
558         bio_endio(bio);
559 }
560
561 static void verity_work(struct work_struct *w)
562 {
563         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
564
565         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
566 }
567
568 static void verity_end_io(struct bio *bio)
569 {
570         struct dm_verity_io *io = bio->bi_private;
571
572         if (bio->bi_status &&
573             (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
574                 verity_finish_io(io, bio->bi_status);
575                 return;
576         }
577
578         INIT_WORK(&io->work, verity_work);
579         queue_work(io->v->verify_wq, &io->work);
580 }
581
582 /*
583  * Prefetch buffers for the specified io.
584  * The root buffer is not prefetched, it is assumed that it will be cached
585  * all the time.
586  */
587 static void verity_prefetch_io(struct work_struct *work)
588 {
589         struct dm_verity_prefetch_work *pw =
590                 container_of(work, struct dm_verity_prefetch_work, work);
591         struct dm_verity *v = pw->v;
592         int i;
593
594         for (i = v->levels - 2; i >= 0; i--) {
595                 sector_t hash_block_start;
596                 sector_t hash_block_end;
597                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
598                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
599                 if (!i) {
600                         unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
601
602                         cluster >>= v->data_dev_block_bits;
603                         if (unlikely(!cluster))
604                                 goto no_prefetch_cluster;
605
606                         if (unlikely(cluster & (cluster - 1)))
607                                 cluster = 1 << __fls(cluster);
608
609                         hash_block_start &= ~(sector_t)(cluster - 1);
610                         hash_block_end |= cluster - 1;
611                         if (unlikely(hash_block_end >= v->hash_blocks))
612                                 hash_block_end = v->hash_blocks - 1;
613                 }
614 no_prefetch_cluster:
615                 dm_bufio_prefetch(v->bufio, hash_block_start,
616                                   hash_block_end - hash_block_start + 1);
617         }
618
619         kfree(pw);
620 }
621
622 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
623 {
624         struct dm_verity_prefetch_work *pw;
625
626         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
627                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
628
629         if (!pw)
630                 return;
631
632         INIT_WORK(&pw->work, verity_prefetch_io);
633         pw->v = v;
634         pw->block = io->block;
635         pw->n_blocks = io->n_blocks;
636         queue_work(v->verify_wq, &pw->work);
637 }
638
639 /*
640  * Bio map function. It allocates dm_verity_io structure and bio vector and
641  * fills them. Then it issues prefetches and the I/O.
642  */
643 static int verity_map(struct dm_target *ti, struct bio *bio)
644 {
645         struct dm_verity *v = ti->private;
646         struct dm_verity_io *io;
647
648         bio_set_dev(bio, v->data_dev->bdev);
649         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
650
651         if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
652             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
653                 DMERR_LIMIT("unaligned io");
654                 return DM_MAPIO_KILL;
655         }
656
657         if (bio_end_sector(bio) >>
658             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
659                 DMERR_LIMIT("io out of range");
660                 return DM_MAPIO_KILL;
661         }
662
663         if (bio_data_dir(bio) == WRITE)
664                 return DM_MAPIO_KILL;
665
666         io = dm_per_bio_data(bio, ti->per_io_data_size);
667         io->v = v;
668         io->orig_bi_end_io = bio->bi_end_io;
669         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
670         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
671
672         bio->bi_end_io = verity_end_io;
673         bio->bi_private = io;
674         io->iter = bio->bi_iter;
675
676         verity_fec_init_io(io);
677
678         verity_submit_prefetch(v, io);
679
680         generic_make_request(bio);
681
682         return DM_MAPIO_SUBMITTED;
683 }
684
685 /*
686  * Status: V (valid) or C (corruption found)
687  */
688 static void verity_status(struct dm_target *ti, status_type_t type,
689                           unsigned status_flags, char *result, unsigned maxlen)
690 {
691         struct dm_verity *v = ti->private;
692         unsigned args = 0;
693         unsigned sz = 0;
694         unsigned x;
695
696         switch (type) {
697         case STATUSTYPE_INFO:
698                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
699                 break;
700         case STATUSTYPE_TABLE:
701                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
702                         v->version,
703                         v->data_dev->name,
704                         v->hash_dev->name,
705                         1 << v->data_dev_block_bits,
706                         1 << v->hash_dev_block_bits,
707                         (unsigned long long)v->data_blocks,
708                         (unsigned long long)v->hash_start,
709                         v->alg_name
710                         );
711                 for (x = 0; x < v->digest_size; x++)
712                         DMEMIT("%02x", v->root_digest[x]);
713                 DMEMIT(" ");
714                 if (!v->salt_size)
715                         DMEMIT("-");
716                 else
717                         for (x = 0; x < v->salt_size; x++)
718                                 DMEMIT("%02x", v->salt[x]);
719                 if (v->mode != DM_VERITY_MODE_EIO)
720                         args++;
721                 if (verity_fec_is_enabled(v))
722                         args += DM_VERITY_OPTS_FEC;
723                 if (v->zero_digest)
724                         args++;
725                 if (v->validated_blocks)
726                         args++;
727                 if (!args)
728                         return;
729                 DMEMIT(" %u", args);
730                 if (v->mode != DM_VERITY_MODE_EIO) {
731                         DMEMIT(" ");
732                         switch (v->mode) {
733                         case DM_VERITY_MODE_LOGGING:
734                                 DMEMIT(DM_VERITY_OPT_LOGGING);
735                                 break;
736                         case DM_VERITY_MODE_RESTART:
737                                 DMEMIT(DM_VERITY_OPT_RESTART);
738                                 break;
739                         default:
740                                 BUG();
741                         }
742                 }
743                 if (v->zero_digest)
744                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
745                 if (v->validated_blocks)
746                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
747                 sz = verity_fec_status_table(v, sz, result, maxlen);
748                 break;
749         }
750 }
751
752 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
753 {
754         struct dm_verity *v = ti->private;
755
756         *bdev = v->data_dev->bdev;
757
758         if (v->data_start ||
759             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
760                 return 1;
761         return 0;
762 }
763
764 static int verity_iterate_devices(struct dm_target *ti,
765                                   iterate_devices_callout_fn fn, void *data)
766 {
767         struct dm_verity *v = ti->private;
768
769         return fn(ti, v->data_dev, v->data_start, ti->len, data);
770 }
771
772 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
773 {
774         struct dm_verity *v = ti->private;
775
776         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
777                 limits->logical_block_size = 1 << v->data_dev_block_bits;
778
779         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
780                 limits->physical_block_size = 1 << v->data_dev_block_bits;
781
782         blk_limits_io_min(limits, limits->logical_block_size);
783 }
784
785 static void verity_dtr(struct dm_target *ti)
786 {
787         struct dm_verity *v = ti->private;
788
789         if (v->verify_wq)
790                 destroy_workqueue(v->verify_wq);
791
792         if (v->bufio)
793                 dm_bufio_client_destroy(v->bufio);
794
795         kvfree(v->validated_blocks);
796         kfree(v->salt);
797         kfree(v->root_digest);
798         kfree(v->zero_digest);
799
800         if (v->tfm)
801                 crypto_free_ahash(v->tfm);
802
803         kfree(v->alg_name);
804
805         if (v->hash_dev)
806                 dm_put_device(ti, v->hash_dev);
807
808         if (v->data_dev)
809                 dm_put_device(ti, v->data_dev);
810
811         verity_fec_dtr(v);
812
813         kfree(v);
814 }
815
816 static int verity_alloc_most_once(struct dm_verity *v)
817 {
818         struct dm_target *ti = v->ti;
819
820         /* the bitset can only handle INT_MAX blocks */
821         if (v->data_blocks > INT_MAX) {
822                 ti->error = "device too large to use check_at_most_once";
823                 return -E2BIG;
824         }
825
826         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
827                                        sizeof(unsigned long),
828                                        GFP_KERNEL);
829         if (!v->validated_blocks) {
830                 ti->error = "failed to allocate bitset for check_at_most_once";
831                 return -ENOMEM;
832         }
833
834         return 0;
835 }
836
837 static int verity_alloc_zero_digest(struct dm_verity *v)
838 {
839         int r = -ENOMEM;
840         struct ahash_request *req;
841         u8 *zero_data;
842
843         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
844
845         if (!v->zero_digest)
846                 return r;
847
848         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
849
850         if (!req)
851                 return r; /* verity_dtr will free zero_digest */
852
853         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
854
855         if (!zero_data)
856                 goto out;
857
858         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
859                         v->zero_digest);
860
861 out:
862         kfree(req);
863         kfree(zero_data);
864
865         return r;
866 }
867
868 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
869 {
870         int r;
871         unsigned argc;
872         struct dm_target *ti = v->ti;
873         const char *arg_name;
874
875         static const struct dm_arg _args[] = {
876                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
877         };
878
879         r = dm_read_arg_group(_args, as, &argc, &ti->error);
880         if (r)
881                 return -EINVAL;
882
883         if (!argc)
884                 return 0;
885
886         do {
887                 arg_name = dm_shift_arg(as);
888                 argc--;
889
890                 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
891                         v->mode = DM_VERITY_MODE_LOGGING;
892                         continue;
893
894                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
895                         v->mode = DM_VERITY_MODE_RESTART;
896                         continue;
897
898                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
899                         r = verity_alloc_zero_digest(v);
900                         if (r) {
901                                 ti->error = "Cannot allocate zero digest";
902                                 return r;
903                         }
904                         continue;
905
906                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
907                         r = verity_alloc_most_once(v);
908                         if (r)
909                                 return r;
910                         continue;
911
912                 } else if (verity_is_fec_opt_arg(arg_name)) {
913                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
914                         if (r)
915                                 return r;
916                         continue;
917                 }
918
919                 ti->error = "Unrecognized verity feature request";
920                 return -EINVAL;
921         } while (argc && !r);
922
923         return r;
924 }
925
926 /*
927  * Target parameters:
928  *      <version>       The current format is version 1.
929  *                      Vsn 0 is compatible with original Chromium OS releases.
930  *      <data device>
931  *      <hash device>
932  *      <data block size>
933  *      <hash block size>
934  *      <the number of data blocks>
935  *      <hash start block>
936  *      <algorithm>
937  *      <digest>
938  *      <salt>          Hex string or "-" if no salt.
939  */
940 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
941 {
942         struct dm_verity *v;
943         struct dm_arg_set as;
944         unsigned int num;
945         unsigned long long num_ll;
946         int r;
947         int i;
948         sector_t hash_position;
949         char dummy;
950
951         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
952         if (!v) {
953                 ti->error = "Cannot allocate verity structure";
954                 return -ENOMEM;
955         }
956         ti->private = v;
957         v->ti = ti;
958
959         r = verity_fec_ctr_alloc(v);
960         if (r)
961                 goto bad;
962
963         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
964                 ti->error = "Device must be readonly";
965                 r = -EINVAL;
966                 goto bad;
967         }
968
969         if (argc < 10) {
970                 ti->error = "Not enough arguments";
971                 r = -EINVAL;
972                 goto bad;
973         }
974
975         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
976             num > 1) {
977                 ti->error = "Invalid version";
978                 r = -EINVAL;
979                 goto bad;
980         }
981         v->version = num;
982
983         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
984         if (r) {
985                 ti->error = "Data device lookup failed";
986                 goto bad;
987         }
988
989         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
990         if (r) {
991                 ti->error = "Hash device lookup failed";
992                 goto bad;
993         }
994
995         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
996             !num || (num & (num - 1)) ||
997             num < bdev_logical_block_size(v->data_dev->bdev) ||
998             num > PAGE_SIZE) {
999                 ti->error = "Invalid data device block size";
1000                 r = -EINVAL;
1001                 goto bad;
1002         }
1003         v->data_dev_block_bits = __ffs(num);
1004
1005         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1006             !num || (num & (num - 1)) ||
1007             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1008             num > INT_MAX) {
1009                 ti->error = "Invalid hash device block size";
1010                 r = -EINVAL;
1011                 goto bad;
1012         }
1013         v->hash_dev_block_bits = __ffs(num);
1014
1015         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1016             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1017             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1018                 ti->error = "Invalid data blocks";
1019                 r = -EINVAL;
1020                 goto bad;
1021         }
1022         v->data_blocks = num_ll;
1023
1024         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1025                 ti->error = "Data device is too small";
1026                 r = -EINVAL;
1027                 goto bad;
1028         }
1029
1030         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1031             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1032             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1033                 ti->error = "Invalid hash start";
1034                 r = -EINVAL;
1035                 goto bad;
1036         }
1037         v->hash_start = num_ll;
1038
1039         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1040         if (!v->alg_name) {
1041                 ti->error = "Cannot allocate algorithm name";
1042                 r = -ENOMEM;
1043                 goto bad;
1044         }
1045
1046         v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1047         if (IS_ERR(v->tfm)) {
1048                 ti->error = "Cannot initialize hash function";
1049                 r = PTR_ERR(v->tfm);
1050                 v->tfm = NULL;
1051                 goto bad;
1052         }
1053         v->digest_size = crypto_ahash_digestsize(v->tfm);
1054         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1055                 ti->error = "Digest size too big";
1056                 r = -EINVAL;
1057                 goto bad;
1058         }
1059         v->ahash_reqsize = sizeof(struct ahash_request) +
1060                 crypto_ahash_reqsize(v->tfm);
1061
1062         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1063         if (!v->root_digest) {
1064                 ti->error = "Cannot allocate root digest";
1065                 r = -ENOMEM;
1066                 goto bad;
1067         }
1068         if (strlen(argv[8]) != v->digest_size * 2 ||
1069             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1070                 ti->error = "Invalid root digest";
1071                 r = -EINVAL;
1072                 goto bad;
1073         }
1074
1075         if (strcmp(argv[9], "-")) {
1076                 v->salt_size = strlen(argv[9]) / 2;
1077                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1078                 if (!v->salt) {
1079                         ti->error = "Cannot allocate salt";
1080                         r = -ENOMEM;
1081                         goto bad;
1082                 }
1083                 if (strlen(argv[9]) != v->salt_size * 2 ||
1084                     hex2bin(v->salt, argv[9], v->salt_size)) {
1085                         ti->error = "Invalid salt";
1086                         r = -EINVAL;
1087                         goto bad;
1088                 }
1089         }
1090
1091         argv += 10;
1092         argc -= 10;
1093
1094         /* Optional parameters */
1095         if (argc) {
1096                 as.argc = argc;
1097                 as.argv = argv;
1098
1099                 r = verity_parse_opt_args(&as, v);
1100                 if (r < 0)
1101                         goto bad;
1102         }
1103
1104         v->hash_per_block_bits =
1105                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1106
1107         v->levels = 0;
1108         if (v->data_blocks)
1109                 while (v->hash_per_block_bits * v->levels < 64 &&
1110                        (unsigned long long)(v->data_blocks - 1) >>
1111                        (v->hash_per_block_bits * v->levels))
1112                         v->levels++;
1113
1114         if (v->levels > DM_VERITY_MAX_LEVELS) {
1115                 ti->error = "Too many tree levels";
1116                 r = -E2BIG;
1117                 goto bad;
1118         }
1119
1120         hash_position = v->hash_start;
1121         for (i = v->levels - 1; i >= 0; i--) {
1122                 sector_t s;
1123                 v->hash_level_block[i] = hash_position;
1124                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1125                                         >> ((i + 1) * v->hash_per_block_bits);
1126                 if (hash_position + s < hash_position) {
1127                         ti->error = "Hash device offset overflow";
1128                         r = -E2BIG;
1129                         goto bad;
1130                 }
1131                 hash_position += s;
1132         }
1133         v->hash_blocks = hash_position;
1134
1135         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1136                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1137                 dm_bufio_alloc_callback, NULL);
1138         if (IS_ERR(v->bufio)) {
1139                 ti->error = "Cannot initialize dm-bufio";
1140                 r = PTR_ERR(v->bufio);
1141                 v->bufio = NULL;
1142                 goto bad;
1143         }
1144
1145         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1146                 ti->error = "Hash device is too small";
1147                 r = -E2BIG;
1148                 goto bad;
1149         }
1150
1151         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1152         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1153         if (!v->verify_wq) {
1154                 ti->error = "Cannot allocate workqueue";
1155                 r = -ENOMEM;
1156                 goto bad;
1157         }
1158
1159         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1160                                 v->ahash_reqsize + v->digest_size * 2;
1161
1162         r = verity_fec_ctr(v);
1163         if (r)
1164                 goto bad;
1165
1166         ti->per_io_data_size = roundup(ti->per_io_data_size,
1167                                        __alignof__(struct dm_verity_io));
1168
1169         return 0;
1170
1171 bad:
1172         verity_dtr(ti);
1173
1174         return r;
1175 }
1176
1177 static struct target_type verity_target = {
1178         .name           = "verity",
1179         .features       = DM_TARGET_IMMUTABLE,
1180         .version        = {1, 4, 0},
1181         .module         = THIS_MODULE,
1182         .ctr            = verity_ctr,
1183         .dtr            = verity_dtr,
1184         .map            = verity_map,
1185         .status         = verity_status,
1186         .prepare_ioctl  = verity_prepare_ioctl,
1187         .iterate_devices = verity_iterate_devices,
1188         .io_hints       = verity_io_hints,
1189 };
1190
1191 static int __init dm_verity_init(void)
1192 {
1193         int r;
1194
1195         r = dm_register_target(&verity_target);
1196         if (r < 0)
1197                 DMERR("register failed %d", r);
1198
1199         return r;
1200 }
1201
1202 static void __exit dm_verity_exit(void)
1203 {
1204         dm_unregister_target(&verity_target);
1205 }
1206
1207 module_init(dm_verity_init);
1208 module_exit(dm_verity_exit);
1209
1210 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1211 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1212 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1213 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1214 MODULE_LICENSE("GPL");