blob: 4b7941db3aff33223481464f24a162d101ab7698 [file] [log] [blame]
Mikulas Patockaa4ffc152012-03-28 18:43:38 +01001/*
2 * Copyright (C) 2012 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
7 *
8 * This file is released under the GPLv2.
9 *
10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the
12 * hash device. Setting this greatly improves performance when data and hash
13 * are on the same disk on different partitions on devices with poor random
14 * access behavior.
15 */
16
17#include "dm-bufio.h"
18
19#include <linux/module.h>
20#include <linux/device-mapper.h>
21#include <crypto/hash.h>
22
23#define DM_MSG_PREFIX "verity"
24
25#define DM_VERITY_IO_VEC_INLINE 16
26#define DM_VERITY_MEMPOOL_SIZE 4
27#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
28
29#define DM_VERITY_MAX_LEVELS 63
30
31static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
32
33module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
34
35struct dm_verity {
36 struct dm_dev *data_dev;
37 struct dm_dev *hash_dev;
38 struct dm_target *ti;
39 struct dm_bufio_client *bufio;
40 char *alg_name;
41 struct crypto_shash *tfm;
42 u8 *root_digest; /* digest of the root block */
43 u8 *salt; /* salt: its size is salt_size */
44 unsigned salt_size;
45 sector_t data_start; /* data offset in 512-byte sectors */
46 sector_t hash_start; /* hash start in blocks */
47 sector_t data_blocks; /* the number of data blocks */
48 sector_t hash_blocks; /* the number of hash blocks */
49 unsigned char data_dev_block_bits; /* log2(data blocksize) */
50 unsigned char hash_dev_block_bits; /* log2(hash blocksize) */
51 unsigned char hash_per_block_bits; /* log2(hashes in hash block) */
52 unsigned char levels; /* the number of tree levels */
53 unsigned char version;
54 unsigned digest_size; /* digest size for the current hash algorithm */
55 unsigned shash_descsize;/* the size of temporary space for crypto */
56 int hash_failed; /* set to 1 if hash of any block failed */
57
Mikulas Patockaa4ffc152012-03-28 18:43:38 +010058 mempool_t *vec_mempool; /* mempool of bio vector */
59
60 struct workqueue_struct *verify_wq;
61
62 /* starting blocks for each tree level. 0 is the lowest level. */
63 sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
64};
65
66struct dm_verity_io {
67 struct dm_verity *v;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +010068
69 /* original values of bio->bi_end_io and bio->bi_private */
70 bio_end_io_t *orig_bi_end_io;
71 void *orig_bi_private;
72
73 sector_t block;
74 unsigned n_blocks;
75
76 /* saved bio vector */
77 struct bio_vec *io_vec;
78 unsigned io_vec_size;
79
80 struct work_struct work;
81
82 /* A space for short vectors; longer vectors are allocated separately. */
83 struct bio_vec io_vec_inline[DM_VERITY_IO_VEC_INLINE];
84
85 /*
86 * Three variably-size fields follow this struct:
87 *
88 * u8 hash_desc[v->shash_descsize];
89 * u8 real_digest[v->digest_size];
90 * u8 want_digest[v->digest_size];
91 *
92 * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
93 */
94};
95
Mikulas Patocka3b6b7812013-03-20 17:21:25 +000096struct dm_verity_prefetch_work {
97 struct work_struct work;
98 struct dm_verity *v;
99 sector_t block;
100 unsigned n_blocks;
101};
102
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100103static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
104{
105 return (struct shash_desc *)(io + 1);
106}
107
108static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
109{
110 return (u8 *)(io + 1) + v->shash_descsize;
111}
112
113static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
114{
115 return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
116}
117
118/*
119 * Auxiliary structure appended to each dm-bufio buffer. If the value
120 * hash_verified is nonzero, hash of the block has been verified.
121 *
122 * The variable hash_verified is set to 0 when allocating the buffer, then
123 * it can be changed to 1 and it is never reset to 0 again.
124 *
125 * There is no lock around this value, a race condition can at worst cause
126 * that multiple processes verify the hash of the same buffer simultaneously
127 * and write 1 to hash_verified simultaneously.
128 * This condition is harmless, so we don't need locking.
129 */
130struct buffer_aux {
131 int hash_verified;
132};
133
134/*
135 * Initialize struct buffer_aux for a freshly created buffer.
136 */
137static void dm_bufio_alloc_callback(struct dm_buffer *buf)
138{
139 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
140
141 aux->hash_verified = 0;
142}
143
144/*
145 * Translate input sector number to the sector number on the target device.
146 */
147static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
148{
149 return v->data_start + dm_target_offset(v->ti, bi_sector);
150}
151
152/*
153 * Return hash position of a specified block at a specified tree level
154 * (0 is the lowest level).
155 * The lowest "hash_per_block_bits"-bits of the result denote hash position
156 * inside a hash block. The remaining bits denote location of the hash block.
157 */
158static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
159 int level)
160{
161 return block >> (level * v->hash_per_block_bits);
162}
163
164static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
165 sector_t *hash_block, unsigned *offset)
166{
167 sector_t position = verity_position_at_level(v, block, level);
168 unsigned idx;
169
170 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
171
172 if (!offset)
173 return;
174
175 idx = position & ((1 << v->hash_per_block_bits) - 1);
176 if (!v->version)
177 *offset = idx * v->digest_size;
178 else
179 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
180}
181
182/*
183 * Verify hash of a metadata block pertaining to the specified data block
184 * ("block" argument) at a specified level ("level" argument).
185 *
186 * On successful return, io_want_digest(v, io) contains the hash value for
187 * a lower tree level or for the data block (if we're at the lowest leve).
188 *
189 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
190 * If "skip_unverified" is false, unverified buffer is hashed and verified
191 * against current value of io_want_digest(v, io).
192 */
193static int verity_verify_level(struct dm_verity_io *io, sector_t block,
194 int level, bool skip_unverified)
195{
196 struct dm_verity *v = io->v;
197 struct dm_buffer *buf;
198 struct buffer_aux *aux;
199 u8 *data;
200 int r;
201 sector_t hash_block;
202 unsigned offset;
203
204 verity_hash_at_level(v, block, level, &hash_block, &offset);
205
206 data = dm_bufio_read(v->bufio, hash_block, &buf);
207 if (unlikely(IS_ERR(data)))
208 return PTR_ERR(data);
209
210 aux = dm_bufio_get_aux_data(buf);
211
212 if (!aux->hash_verified) {
213 struct shash_desc *desc;
214 u8 *result;
215
216 if (skip_unverified) {
217 r = 1;
218 goto release_ret_r;
219 }
220
221 desc = io_hash_desc(v, io);
222 desc->tfm = v->tfm;
223 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
224 r = crypto_shash_init(desc);
225 if (r < 0) {
226 DMERR("crypto_shash_init failed: %d", r);
227 goto release_ret_r;
228 }
229
230 if (likely(v->version >= 1)) {
231 r = crypto_shash_update(desc, v->salt, v->salt_size);
232 if (r < 0) {
233 DMERR("crypto_shash_update failed: %d", r);
234 goto release_ret_r;
235 }
236 }
237
238 r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
239 if (r < 0) {
240 DMERR("crypto_shash_update failed: %d", r);
241 goto release_ret_r;
242 }
243
244 if (!v->version) {
245 r = crypto_shash_update(desc, v->salt, v->salt_size);
246 if (r < 0) {
247 DMERR("crypto_shash_update failed: %d", r);
248 goto release_ret_r;
249 }
250 }
251
252 result = io_real_digest(v, io);
253 r = crypto_shash_final(desc, result);
254 if (r < 0) {
255 DMERR("crypto_shash_final failed: %d", r);
256 goto release_ret_r;
257 }
258 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
259 DMERR_LIMIT("metadata block %llu is corrupted",
260 (unsigned long long)hash_block);
261 v->hash_failed = 1;
262 r = -EIO;
263 goto release_ret_r;
264 } else
265 aux->hash_verified = 1;
266 }
267
268 data += offset;
269
270 memcpy(io_want_digest(v, io), data, v->digest_size);
271
272 dm_bufio_release(buf);
273 return 0;
274
275release_ret_r:
276 dm_bufio_release(buf);
277
278 return r;
279}
280
281/*
282 * Verify one "dm_verity_io" structure.
283 */
284static int verity_verify_io(struct dm_verity_io *io)
285{
286 struct dm_verity *v = io->v;
287 unsigned b;
288 int i;
289 unsigned vector = 0, offset = 0;
290
291 for (b = 0; b < io->n_blocks; b++) {
292 struct shash_desc *desc;
293 u8 *result;
294 int r;
295 unsigned todo;
296
297 if (likely(v->levels)) {
298 /*
299 * First, we try to get the requested hash for
300 * the current block. If the hash block itself is
301 * verified, zero is returned. If it isn't, this
302 * function returns 0 and we fall back to whole
303 * chain verification.
304 */
305 int r = verity_verify_level(io, io->block + b, 0, true);
306 if (likely(!r))
307 goto test_block_hash;
308 if (r < 0)
309 return r;
310 }
311
312 memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
313
314 for (i = v->levels - 1; i >= 0; i--) {
315 int r = verity_verify_level(io, io->block + b, i, false);
316 if (unlikely(r))
317 return r;
318 }
319
320test_block_hash:
321 desc = io_hash_desc(v, io);
322 desc->tfm = v->tfm;
323 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
324 r = crypto_shash_init(desc);
325 if (r < 0) {
326 DMERR("crypto_shash_init failed: %d", r);
327 return r;
328 }
329
330 if (likely(v->version >= 1)) {
331 r = crypto_shash_update(desc, v->salt, v->salt_size);
332 if (r < 0) {
333 DMERR("crypto_shash_update failed: %d", r);
334 return r;
335 }
336 }
337
338 todo = 1 << v->data_dev_block_bits;
339 do {
340 struct bio_vec *bv;
341 u8 *page;
342 unsigned len;
343
344 BUG_ON(vector >= io->io_vec_size);
345 bv = &io->io_vec[vector];
346 page = kmap_atomic(bv->bv_page);
347 len = bv->bv_len - offset;
348 if (likely(len >= todo))
349 len = todo;
350 r = crypto_shash_update(desc,
351 page + bv->bv_offset + offset, len);
352 kunmap_atomic(page);
353 if (r < 0) {
354 DMERR("crypto_shash_update failed: %d", r);
355 return r;
356 }
357 offset += len;
358 if (likely(offset == bv->bv_len)) {
359 offset = 0;
360 vector++;
361 }
362 todo -= len;
363 } while (todo);
364
365 if (!v->version) {
366 r = crypto_shash_update(desc, v->salt, v->salt_size);
367 if (r < 0) {
368 DMERR("crypto_shash_update failed: %d", r);
369 return r;
370 }
371 }
372
373 result = io_real_digest(v, io);
374 r = crypto_shash_final(desc, result);
375 if (r < 0) {
376 DMERR("crypto_shash_final failed: %d", r);
377 return r;
378 }
379 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
380 DMERR_LIMIT("data block %llu is corrupted",
381 (unsigned long long)(io->block + b));
382 v->hash_failed = 1;
383 return -EIO;
384 }
385 }
386 BUG_ON(vector != io->io_vec_size);
387 BUG_ON(offset);
388
389 return 0;
390}
391
392/*
393 * End one "io" structure with a given error.
394 */
395static void verity_finish_io(struct dm_verity_io *io, int error)
396{
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100397 struct dm_verity *v = io->v;
Mikulas Patockae42c3f92012-12-21 20:23:38 +0000398 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100399
400 bio->bi_end_io = io->orig_bi_end_io;
401 bio->bi_private = io->orig_bi_private;
402
403 if (io->io_vec != io->io_vec_inline)
404 mempool_free(io->io_vec, v->vec_mempool);
405
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100406 bio_endio(bio, error);
407}
408
409static void verity_work(struct work_struct *w)
410{
411 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
412
413 verity_finish_io(io, verity_verify_io(io));
414}
415
416static void verity_end_io(struct bio *bio, int error)
417{
418 struct dm_verity_io *io = bio->bi_private;
419
420 if (error) {
421 verity_finish_io(io, error);
422 return;
423 }
424
425 INIT_WORK(&io->work, verity_work);
426 queue_work(io->v->verify_wq, &io->work);
427}
428
429/*
430 * Prefetch buffers for the specified io.
431 * The root buffer is not prefetched, it is assumed that it will be cached
432 * all the time.
433 */
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000434static void verity_prefetch_io(struct work_struct *work)
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100435{
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000436 struct dm_verity_prefetch_work *pw =
437 container_of(work, struct dm_verity_prefetch_work, work);
438 struct dm_verity *v = pw->v;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100439 int i;
440
441 for (i = v->levels - 2; i >= 0; i--) {
442 sector_t hash_block_start;
443 sector_t hash_block_end;
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000444 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
445 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100446 if (!i) {
Mikulas Patockafe5fe902012-10-12 16:59:46 +0100447 unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100448
449 cluster >>= v->data_dev_block_bits;
450 if (unlikely(!cluster))
451 goto no_prefetch_cluster;
452
453 if (unlikely(cluster & (cluster - 1)))
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100454 cluster = 1 << __fls(cluster);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100455
456 hash_block_start &= ~(sector_t)(cluster - 1);
457 hash_block_end |= cluster - 1;
458 if (unlikely(hash_block_end >= v->hash_blocks))
459 hash_block_end = v->hash_blocks - 1;
460 }
461no_prefetch_cluster:
462 dm_bufio_prefetch(v->bufio, hash_block_start,
463 hash_block_end - hash_block_start + 1);
464 }
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000465
466 kfree(pw);
467}
468
469static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
470{
471 struct dm_verity_prefetch_work *pw;
472
473 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
474 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
475
476 if (!pw)
477 return;
478
479 INIT_WORK(&pw->work, verity_prefetch_io);
480 pw->v = v;
481 pw->block = io->block;
482 pw->n_blocks = io->n_blocks;
483 queue_work(v->verify_wq, &pw->work);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100484}
485
486/*
487 * Bio map function. It allocates dm_verity_io structure and bio vector and
488 * fills them. Then it issues prefetches and the I/O.
489 */
Mikulas Patocka7de3ee52012-12-21 20:23:41 +0000490static int verity_map(struct dm_target *ti, struct bio *bio)
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100491{
492 struct dm_verity *v = ti->private;
493 struct dm_verity_io *io;
494
495 bio->bi_bdev = v->data_dev->bdev;
496 bio->bi_sector = verity_map_sector(v, bio->bi_sector);
497
498 if (((unsigned)bio->bi_sector | bio_sectors(bio)) &
499 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
500 DMERR_LIMIT("unaligned io");
501 return -EIO;
502 }
503
Kent Overstreetf73a1c72012-09-25 15:05:12 -0700504 if (bio_end_sector(bio) >>
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100505 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
506 DMERR_LIMIT("io out of range");
507 return -EIO;
508 }
509
510 if (bio_data_dir(bio) == WRITE)
511 return -EIO;
512
Mikulas Patockae42c3f92012-12-21 20:23:38 +0000513 io = dm_per_bio_data(bio, ti->per_bio_data_size);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100514 io->v = v;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100515 io->orig_bi_end_io = bio->bi_end_io;
516 io->orig_bi_private = bio->bi_private;
517 io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
518 io->n_blocks = bio->bi_size >> v->data_dev_block_bits;
519
520 bio->bi_end_io = verity_end_io;
521 bio->bi_private = io;
Kent Overstreet4f2ac932012-09-04 15:23:14 -0700522 io->io_vec_size = bio_segments(bio);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100523 if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE)
524 io->io_vec = io->io_vec_inline;
525 else
526 io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO);
527 memcpy(io->io_vec, bio_iovec(bio),
528 io->io_vec_size * sizeof(struct bio_vec));
529
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000530 verity_submit_prefetch(v, io);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100531
532 generic_make_request(bio);
533
534 return DM_MAPIO_SUBMITTED;
535}
536
537/*
538 * Status: V (valid) or C (corruption found)
539 */
Mikulas Patockafd7c0922013-03-01 22:45:44 +0000540static void verity_status(struct dm_target *ti, status_type_t type,
541 unsigned status_flags, char *result, unsigned maxlen)
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100542{
543 struct dm_verity *v = ti->private;
544 unsigned sz = 0;
545 unsigned x;
546
547 switch (type) {
548 case STATUSTYPE_INFO:
549 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
550 break;
551 case STATUSTYPE_TABLE:
552 DMEMIT("%u %s %s %u %u %llu %llu %s ",
553 v->version,
554 v->data_dev->name,
555 v->hash_dev->name,
556 1 << v->data_dev_block_bits,
557 1 << v->hash_dev_block_bits,
558 (unsigned long long)v->data_blocks,
559 (unsigned long long)v->hash_start,
560 v->alg_name
561 );
562 for (x = 0; x < v->digest_size; x++)
563 DMEMIT("%02x", v->root_digest[x]);
564 DMEMIT(" ");
565 if (!v->salt_size)
566 DMEMIT("-");
567 else
568 for (x = 0; x < v->salt_size; x++)
569 DMEMIT("%02x", v->salt[x]);
570 break;
571 }
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100572}
573
574static int verity_ioctl(struct dm_target *ti, unsigned cmd,
575 unsigned long arg)
576{
577 struct dm_verity *v = ti->private;
578 int r = 0;
579
580 if (v->data_start ||
581 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
582 r = scsi_verify_blk_ioctl(NULL, cmd);
583
584 return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
585 cmd, arg);
586}
587
588static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
589 struct bio_vec *biovec, int max_size)
590{
591 struct dm_verity *v = ti->private;
592 struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
593
594 if (!q->merge_bvec_fn)
595 return max_size;
596
597 bvm->bi_bdev = v->data_dev->bdev;
598 bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
599
600 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
601}
602
603static int verity_iterate_devices(struct dm_target *ti,
604 iterate_devices_callout_fn fn, void *data)
605{
606 struct dm_verity *v = ti->private;
607
608 return fn(ti, v->data_dev, v->data_start, ti->len, data);
609}
610
611static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
612{
613 struct dm_verity *v = ti->private;
614
615 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
616 limits->logical_block_size = 1 << v->data_dev_block_bits;
617
618 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
619 limits->physical_block_size = 1 << v->data_dev_block_bits;
620
621 blk_limits_io_min(limits, limits->logical_block_size);
622}
623
624static void verity_dtr(struct dm_target *ti)
625{
626 struct dm_verity *v = ti->private;
627
628 if (v->verify_wq)
629 destroy_workqueue(v->verify_wq);
630
631 if (v->vec_mempool)
632 mempool_destroy(v->vec_mempool);
633
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100634 if (v->bufio)
635 dm_bufio_client_destroy(v->bufio);
636
637 kfree(v->salt);
638 kfree(v->root_digest);
639
640 if (v->tfm)
641 crypto_free_shash(v->tfm);
642
643 kfree(v->alg_name);
644
645 if (v->hash_dev)
646 dm_put_device(ti, v->hash_dev);
647
648 if (v->data_dev)
649 dm_put_device(ti, v->data_dev);
650
651 kfree(v);
652}
653
654/*
655 * Target parameters:
656 * <version> The current format is version 1.
657 * Vsn 0 is compatible with original Chromium OS releases.
658 * <data device>
659 * <hash device>
660 * <data block size>
661 * <hash block size>
662 * <the number of data blocks>
663 * <hash start block>
664 * <algorithm>
665 * <digest>
666 * <salt> Hex string or "-" if no salt.
667 */
668static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
669{
670 struct dm_verity *v;
671 unsigned num;
672 unsigned long long num_ll;
673 int r;
674 int i;
675 sector_t hash_position;
676 char dummy;
677
678 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
679 if (!v) {
680 ti->error = "Cannot allocate verity structure";
681 return -ENOMEM;
682 }
683 ti->private = v;
684 v->ti = ti;
685
686 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
687 ti->error = "Device must be readonly";
688 r = -EINVAL;
689 goto bad;
690 }
691
692 if (argc != 10) {
693 ti->error = "Invalid argument count: exactly 10 arguments required";
694 r = -EINVAL;
695 goto bad;
696 }
697
Mikulas Patocka5d8be842013-07-10 23:41:17 +0100698 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
699 num > 1) {
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100700 ti->error = "Invalid version";
701 r = -EINVAL;
702 goto bad;
703 }
704 v->version = num;
705
706 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
707 if (r) {
708 ti->error = "Data device lookup failed";
709 goto bad;
710 }
711
712 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
713 if (r) {
714 ti->error = "Data device lookup failed";
715 goto bad;
716 }
717
718 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
719 !num || (num & (num - 1)) ||
720 num < bdev_logical_block_size(v->data_dev->bdev) ||
721 num > PAGE_SIZE) {
722 ti->error = "Invalid data device block size";
723 r = -EINVAL;
724 goto bad;
725 }
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100726 v->data_dev_block_bits = __ffs(num);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100727
728 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
729 !num || (num & (num - 1)) ||
730 num < bdev_logical_block_size(v->hash_dev->bdev) ||
731 num > INT_MAX) {
732 ti->error = "Invalid hash device block size";
733 r = -EINVAL;
734 goto bad;
735 }
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100736 v->hash_dev_block_bits = __ffs(num);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100737
738 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
Mikulas Patocka1d55f6b2012-09-26 23:45:48 +0100739 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
740 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100741 ti->error = "Invalid data blocks";
742 r = -EINVAL;
743 goto bad;
744 }
745 v->data_blocks = num_ll;
746
747 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
748 ti->error = "Data device is too small";
749 r = -EINVAL;
750 goto bad;
751 }
752
753 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
Mikulas Patocka1d55f6b2012-09-26 23:45:48 +0100754 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
755 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100756 ti->error = "Invalid hash start";
757 r = -EINVAL;
758 goto bad;
759 }
760 v->hash_start = num_ll;
761
762 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
763 if (!v->alg_name) {
764 ti->error = "Cannot allocate algorithm name";
765 r = -ENOMEM;
766 goto bad;
767 }
768
769 v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
770 if (IS_ERR(v->tfm)) {
771 ti->error = "Cannot initialize hash function";
772 r = PTR_ERR(v->tfm);
773 v->tfm = NULL;
774 goto bad;
775 }
776 v->digest_size = crypto_shash_digestsize(v->tfm);
777 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
778 ti->error = "Digest size too big";
779 r = -EINVAL;
780 goto bad;
781 }
782 v->shash_descsize =
783 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
784
785 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
786 if (!v->root_digest) {
787 ti->error = "Cannot allocate root digest";
788 r = -ENOMEM;
789 goto bad;
790 }
791 if (strlen(argv[8]) != v->digest_size * 2 ||
792 hex2bin(v->root_digest, argv[8], v->digest_size)) {
793 ti->error = "Invalid root digest";
794 r = -EINVAL;
795 goto bad;
796 }
797
798 if (strcmp(argv[9], "-")) {
799 v->salt_size = strlen(argv[9]) / 2;
800 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
801 if (!v->salt) {
802 ti->error = "Cannot allocate salt";
803 r = -ENOMEM;
804 goto bad;
805 }
806 if (strlen(argv[9]) != v->salt_size * 2 ||
807 hex2bin(v->salt, argv[9], v->salt_size)) {
808 ti->error = "Invalid salt";
809 r = -EINVAL;
810 goto bad;
811 }
812 }
813
814 v->hash_per_block_bits =
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100815 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100816
817 v->levels = 0;
818 if (v->data_blocks)
819 while (v->hash_per_block_bits * v->levels < 64 &&
820 (unsigned long long)(v->data_blocks - 1) >>
821 (v->hash_per_block_bits * v->levels))
822 v->levels++;
823
824 if (v->levels > DM_VERITY_MAX_LEVELS) {
825 ti->error = "Too many tree levels";
826 r = -E2BIG;
827 goto bad;
828 }
829
830 hash_position = v->hash_start;
831 for (i = v->levels - 1; i >= 0; i--) {
832 sector_t s;
833 v->hash_level_block[i] = hash_position;
Mikulas Patockab1bf2de2013-07-10 23:41:16 +0100834 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
835 >> ((i + 1) * v->hash_per_block_bits);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100836 if (hash_position + s < hash_position) {
837 ti->error = "Hash device offset overflow";
838 r = -E2BIG;
839 goto bad;
840 }
841 hash_position += s;
842 }
843 v->hash_blocks = hash_position;
844
845 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
846 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
847 dm_bufio_alloc_callback, NULL);
848 if (IS_ERR(v->bufio)) {
849 ti->error = "Cannot initialize dm-bufio";
850 r = PTR_ERR(v->bufio);
851 v->bufio = NULL;
852 goto bad;
853 }
854
855 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
856 ti->error = "Hash device is too small";
857 r = -E2BIG;
858 goto bad;
859 }
860
Mikulas Patockae42c3f92012-12-21 20:23:38 +0000861 ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100862
863 v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
864 BIO_MAX_PAGES * sizeof(struct bio_vec));
865 if (!v->vec_mempool) {
866 ti->error = "Cannot allocate vector mempool";
867 r = -ENOMEM;
868 goto bad;
869 }
870
871 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
872 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
873 if (!v->verify_wq) {
874 ti->error = "Cannot allocate workqueue";
875 r = -ENOMEM;
876 goto bad;
877 }
878
879 return 0;
880
881bad:
882 verity_dtr(ti);
883
884 return r;
885}
886
887static struct target_type verity_target = {
888 .name = "verity",
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000889 .version = {1, 2, 0},
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100890 .module = THIS_MODULE,
891 .ctr = verity_ctr,
892 .dtr = verity_dtr,
893 .map = verity_map,
894 .status = verity_status,
895 .ioctl = verity_ioctl,
896 .merge = verity_merge,
897 .iterate_devices = verity_iterate_devices,
898 .io_hints = verity_io_hints,
899};
900
901static int __init dm_verity_init(void)
902{
903 int r;
904
905 r = dm_register_target(&verity_target);
906 if (r < 0)
907 DMERR("register failed %d", r);
908
909 return r;
910}
911
912static void __exit dm_verity_exit(void)
913{
914 dm_unregister_target(&verity_target);
915}
916
917module_init(dm_verity_init);
918module_exit(dm_verity_exit);
919
920MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
921MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
922MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
923MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
924MODULE_LICENSE("GPL");