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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
Kent Overstreet003b5c52013-10-11 15:45:43 -070076 struct bvec_iter iter;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +010077
78 struct work_struct work;
79
Mikulas Patockaa4ffc152012-03-28 18:43:38 +010080 /*
81 * Three variably-size fields follow this struct:
82 *
83 * u8 hash_desc[v->shash_descsize];
84 * u8 real_digest[v->digest_size];
85 * u8 want_digest[v->digest_size];
86 *
87 * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
88 */
89};
90
Mikulas Patocka3b6b7812013-03-20 17:21:25 +000091struct dm_verity_prefetch_work {
92 struct work_struct work;
93 struct dm_verity *v;
94 sector_t block;
95 unsigned n_blocks;
96};
97
Mikulas Patockaa4ffc152012-03-28 18:43:38 +010098static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
99{
100 return (struct shash_desc *)(io + 1);
101}
102
103static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
104{
105 return (u8 *)(io + 1) + v->shash_descsize;
106}
107
108static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
109{
110 return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
111}
112
113/*
114 * Auxiliary structure appended to each dm-bufio buffer. If the value
115 * hash_verified is nonzero, hash of the block has been verified.
116 *
117 * The variable hash_verified is set to 0 when allocating the buffer, then
118 * it can be changed to 1 and it is never reset to 0 again.
119 *
120 * There is no lock around this value, a race condition can at worst cause
121 * that multiple processes verify the hash of the same buffer simultaneously
122 * and write 1 to hash_verified simultaneously.
123 * This condition is harmless, so we don't need locking.
124 */
125struct buffer_aux {
126 int hash_verified;
127};
128
129/*
130 * Initialize struct buffer_aux for a freshly created buffer.
131 */
132static void dm_bufio_alloc_callback(struct dm_buffer *buf)
133{
134 struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
135
136 aux->hash_verified = 0;
137}
138
139/*
140 * Translate input sector number to the sector number on the target device.
141 */
142static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
143{
144 return v->data_start + dm_target_offset(v->ti, bi_sector);
145}
146
147/*
148 * Return hash position of a specified block at a specified tree level
149 * (0 is the lowest level).
150 * The lowest "hash_per_block_bits"-bits of the result denote hash position
151 * inside a hash block. The remaining bits denote location of the hash block.
152 */
153static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
154 int level)
155{
156 return block >> (level * v->hash_per_block_bits);
157}
158
159static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
160 sector_t *hash_block, unsigned *offset)
161{
162 sector_t position = verity_position_at_level(v, block, level);
163 unsigned idx;
164
165 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
166
167 if (!offset)
168 return;
169
170 idx = position & ((1 << v->hash_per_block_bits) - 1);
171 if (!v->version)
172 *offset = idx * v->digest_size;
173 else
174 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
175}
176
177/*
178 * Verify hash of a metadata block pertaining to the specified data block
179 * ("block" argument) at a specified level ("level" argument).
180 *
181 * On successful return, io_want_digest(v, io) contains the hash value for
182 * a lower tree level or for the data block (if we're at the lowest leve).
183 *
184 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
185 * If "skip_unverified" is false, unverified buffer is hashed and verified
186 * against current value of io_want_digest(v, io).
187 */
188static int verity_verify_level(struct dm_verity_io *io, sector_t block,
189 int level, bool skip_unverified)
190{
191 struct dm_verity *v = io->v;
192 struct dm_buffer *buf;
193 struct buffer_aux *aux;
194 u8 *data;
195 int r;
196 sector_t hash_block;
197 unsigned offset;
198
199 verity_hash_at_level(v, block, level, &hash_block, &offset);
200
201 data = dm_bufio_read(v->bufio, hash_block, &buf);
202 if (unlikely(IS_ERR(data)))
203 return PTR_ERR(data);
204
205 aux = dm_bufio_get_aux_data(buf);
206
207 if (!aux->hash_verified) {
208 struct shash_desc *desc;
209 u8 *result;
210
211 if (skip_unverified) {
212 r = 1;
213 goto release_ret_r;
214 }
215
216 desc = io_hash_desc(v, io);
217 desc->tfm = v->tfm;
218 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
219 r = crypto_shash_init(desc);
220 if (r < 0) {
221 DMERR("crypto_shash_init failed: %d", r);
222 goto release_ret_r;
223 }
224
225 if (likely(v->version >= 1)) {
226 r = crypto_shash_update(desc, v->salt, v->salt_size);
227 if (r < 0) {
228 DMERR("crypto_shash_update failed: %d", r);
229 goto release_ret_r;
230 }
231 }
232
233 r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
234 if (r < 0) {
235 DMERR("crypto_shash_update failed: %d", r);
236 goto release_ret_r;
237 }
238
239 if (!v->version) {
240 r = crypto_shash_update(desc, v->salt, v->salt_size);
241 if (r < 0) {
242 DMERR("crypto_shash_update failed: %d", r);
243 goto release_ret_r;
244 }
245 }
246
247 result = io_real_digest(v, io);
248 r = crypto_shash_final(desc, result);
249 if (r < 0) {
250 DMERR("crypto_shash_final failed: %d", r);
251 goto release_ret_r;
252 }
253 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
254 DMERR_LIMIT("metadata block %llu is corrupted",
255 (unsigned long long)hash_block);
256 v->hash_failed = 1;
257 r = -EIO;
258 goto release_ret_r;
259 } else
260 aux->hash_verified = 1;
261 }
262
263 data += offset;
264
265 memcpy(io_want_digest(v, io), data, v->digest_size);
266
267 dm_bufio_release(buf);
268 return 0;
269
270release_ret_r:
271 dm_bufio_release(buf);
272
273 return r;
274}
275
276/*
277 * Verify one "dm_verity_io" structure.
278 */
279static int verity_verify_io(struct dm_verity_io *io)
280{
281 struct dm_verity *v = io->v;
Kent Overstreet003b5c52013-10-11 15:45:43 -0700282 struct bio *bio = dm_bio_from_per_bio_data(io,
283 v->ti->per_bio_data_size);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100284 unsigned b;
285 int i;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100286
287 for (b = 0; b < io->n_blocks; b++) {
288 struct shash_desc *desc;
289 u8 *result;
290 int r;
291 unsigned todo;
292
293 if (likely(v->levels)) {
294 /*
295 * First, we try to get the requested hash for
296 * the current block. If the hash block itself is
297 * verified, zero is returned. If it isn't, this
298 * function returns 0 and we fall back to whole
299 * chain verification.
300 */
301 int r = verity_verify_level(io, io->block + b, 0, true);
302 if (likely(!r))
303 goto test_block_hash;
304 if (r < 0)
305 return r;
306 }
307
308 memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
309
310 for (i = v->levels - 1; i >= 0; i--) {
311 int r = verity_verify_level(io, io->block + b, i, false);
312 if (unlikely(r))
313 return r;
314 }
315
316test_block_hash:
317 desc = io_hash_desc(v, io);
318 desc->tfm = v->tfm;
319 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
320 r = crypto_shash_init(desc);
321 if (r < 0) {
322 DMERR("crypto_shash_init failed: %d", r);
323 return r;
324 }
325
326 if (likely(v->version >= 1)) {
327 r = crypto_shash_update(desc, v->salt, v->salt_size);
328 if (r < 0) {
329 DMERR("crypto_shash_update failed: %d", r);
330 return r;
331 }
332 }
333
334 todo = 1 << v->data_dev_block_bits;
Kent Overstreet003b5c52013-10-11 15:45:43 -0700335 while (io->iter.bi_size) {
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100336 u8 *page;
Kent Overstreet003b5c52013-10-11 15:45:43 -0700337 struct bio_vec bv = bio_iter_iovec(bio, io->iter);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100338
Kent Overstreet003b5c52013-10-11 15:45:43 -0700339 page = kmap_atomic(bv.bv_page);
340 r = crypto_shash_update(desc, page + bv.bv_offset,
341 bv.bv_len);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100342 kunmap_atomic(page);
Kent Overstreet003b5c52013-10-11 15:45:43 -0700343
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100344 if (r < 0) {
345 DMERR("crypto_shash_update failed: %d", r);
346 return r;
347 }
Kent Overstreet003b5c52013-10-11 15:45:43 -0700348
349 bio_advance_iter(bio, &io->iter, bv.bv_len);
350 }
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100351
352 if (!v->version) {
353 r = crypto_shash_update(desc, v->salt, v->salt_size);
354 if (r < 0) {
355 DMERR("crypto_shash_update failed: %d", r);
356 return r;
357 }
358 }
359
360 result = io_real_digest(v, io);
361 r = crypto_shash_final(desc, result);
362 if (r < 0) {
363 DMERR("crypto_shash_final failed: %d", r);
364 return r;
365 }
366 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
367 DMERR_LIMIT("data block %llu is corrupted",
368 (unsigned long long)(io->block + b));
369 v->hash_failed = 1;
370 return -EIO;
371 }
372 }
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100373
374 return 0;
375}
376
377/*
378 * End one "io" structure with a given error.
379 */
380static void verity_finish_io(struct dm_verity_io *io, int error)
381{
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100382 struct dm_verity *v = io->v;
Mikulas Patockae42c3f92012-12-21 20:23:38 +0000383 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100384
385 bio->bi_end_io = io->orig_bi_end_io;
386 bio->bi_private = io->orig_bi_private;
387
Kent Overstreet196d38b2013-11-23 18:34:15 -0800388 bio_endio_nodec(bio, error);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100389}
390
391static void verity_work(struct work_struct *w)
392{
393 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
394
395 verity_finish_io(io, verity_verify_io(io));
396}
397
398static void verity_end_io(struct bio *bio, int error)
399{
400 struct dm_verity_io *io = bio->bi_private;
401
402 if (error) {
403 verity_finish_io(io, error);
404 return;
405 }
406
407 INIT_WORK(&io->work, verity_work);
408 queue_work(io->v->verify_wq, &io->work);
409}
410
411/*
412 * Prefetch buffers for the specified io.
413 * The root buffer is not prefetched, it is assumed that it will be cached
414 * all the time.
415 */
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000416static void verity_prefetch_io(struct work_struct *work)
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100417{
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000418 struct dm_verity_prefetch_work *pw =
419 container_of(work, struct dm_verity_prefetch_work, work);
420 struct dm_verity *v = pw->v;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100421 int i;
422
423 for (i = v->levels - 2; i >= 0; i--) {
424 sector_t hash_block_start;
425 sector_t hash_block_end;
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000426 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
427 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100428 if (!i) {
Mikulas Patockafe5fe902012-10-12 16:59:46 +0100429 unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100430
431 cluster >>= v->data_dev_block_bits;
432 if (unlikely(!cluster))
433 goto no_prefetch_cluster;
434
435 if (unlikely(cluster & (cluster - 1)))
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100436 cluster = 1 << __fls(cluster);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100437
438 hash_block_start &= ~(sector_t)(cluster - 1);
439 hash_block_end |= cluster - 1;
440 if (unlikely(hash_block_end >= v->hash_blocks))
441 hash_block_end = v->hash_blocks - 1;
442 }
443no_prefetch_cluster:
444 dm_bufio_prefetch(v->bufio, hash_block_start,
445 hash_block_end - hash_block_start + 1);
446 }
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000447
448 kfree(pw);
449}
450
451static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
452{
453 struct dm_verity_prefetch_work *pw;
454
455 pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
456 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
457
458 if (!pw)
459 return;
460
461 INIT_WORK(&pw->work, verity_prefetch_io);
462 pw->v = v;
463 pw->block = io->block;
464 pw->n_blocks = io->n_blocks;
465 queue_work(v->verify_wq, &pw->work);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100466}
467
468/*
469 * Bio map function. It allocates dm_verity_io structure and bio vector and
470 * fills them. Then it issues prefetches and the I/O.
471 */
Mikulas Patocka7de3ee52012-12-21 20:23:41 +0000472static int verity_map(struct dm_target *ti, struct bio *bio)
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100473{
474 struct dm_verity *v = ti->private;
475 struct dm_verity_io *io;
476
477 bio->bi_bdev = v->data_dev->bdev;
Kent Overstreet4f024f32013-10-11 15:44:27 -0700478 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100479
Kent Overstreet4f024f32013-10-11 15:44:27 -0700480 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100481 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
482 DMERR_LIMIT("unaligned io");
483 return -EIO;
484 }
485
Kent Overstreetf73a1c72012-09-25 15:05:12 -0700486 if (bio_end_sector(bio) >>
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100487 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
488 DMERR_LIMIT("io out of range");
489 return -EIO;
490 }
491
492 if (bio_data_dir(bio) == WRITE)
493 return -EIO;
494
Mikulas Patockae42c3f92012-12-21 20:23:38 +0000495 io = dm_per_bio_data(bio, ti->per_bio_data_size);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100496 io->v = v;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100497 io->orig_bi_end_io = bio->bi_end_io;
498 io->orig_bi_private = bio->bi_private;
Kent Overstreet4f024f32013-10-11 15:44:27 -0700499 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
500 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100501
502 bio->bi_end_io = verity_end_io;
503 bio->bi_private = io;
Kent Overstreet003b5c52013-10-11 15:45:43 -0700504 io->iter = bio->bi_iter;
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100505
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000506 verity_submit_prefetch(v, io);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100507
508 generic_make_request(bio);
509
510 return DM_MAPIO_SUBMITTED;
511}
512
513/*
514 * Status: V (valid) or C (corruption found)
515 */
Mikulas Patockafd7c0922013-03-01 22:45:44 +0000516static void verity_status(struct dm_target *ti, status_type_t type,
517 unsigned status_flags, char *result, unsigned maxlen)
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100518{
519 struct dm_verity *v = ti->private;
520 unsigned sz = 0;
521 unsigned x;
522
523 switch (type) {
524 case STATUSTYPE_INFO:
525 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
526 break;
527 case STATUSTYPE_TABLE:
528 DMEMIT("%u %s %s %u %u %llu %llu %s ",
529 v->version,
530 v->data_dev->name,
531 v->hash_dev->name,
532 1 << v->data_dev_block_bits,
533 1 << v->hash_dev_block_bits,
534 (unsigned long long)v->data_blocks,
535 (unsigned long long)v->hash_start,
536 v->alg_name
537 );
538 for (x = 0; x < v->digest_size; x++)
539 DMEMIT("%02x", v->root_digest[x]);
540 DMEMIT(" ");
541 if (!v->salt_size)
542 DMEMIT("-");
543 else
544 for (x = 0; x < v->salt_size; x++)
545 DMEMIT("%02x", v->salt[x]);
546 break;
547 }
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100548}
549
550static int verity_ioctl(struct dm_target *ti, unsigned cmd,
551 unsigned long arg)
552{
553 struct dm_verity *v = ti->private;
554 int r = 0;
555
556 if (v->data_start ||
557 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
558 r = scsi_verify_blk_ioctl(NULL, cmd);
559
560 return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
561 cmd, arg);
562}
563
564static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
565 struct bio_vec *biovec, int max_size)
566{
567 struct dm_verity *v = ti->private;
568 struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
569
570 if (!q->merge_bvec_fn)
571 return max_size;
572
573 bvm->bi_bdev = v->data_dev->bdev;
574 bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
575
576 return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
577}
578
579static int verity_iterate_devices(struct dm_target *ti,
580 iterate_devices_callout_fn fn, void *data)
581{
582 struct dm_verity *v = ti->private;
583
584 return fn(ti, v->data_dev, v->data_start, ti->len, data);
585}
586
587static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
588{
589 struct dm_verity *v = ti->private;
590
591 if (limits->logical_block_size < 1 << v->data_dev_block_bits)
592 limits->logical_block_size = 1 << v->data_dev_block_bits;
593
594 if (limits->physical_block_size < 1 << v->data_dev_block_bits)
595 limits->physical_block_size = 1 << v->data_dev_block_bits;
596
597 blk_limits_io_min(limits, limits->logical_block_size);
598}
599
600static void verity_dtr(struct dm_target *ti)
601{
602 struct dm_verity *v = ti->private;
603
604 if (v->verify_wq)
605 destroy_workqueue(v->verify_wq);
606
607 if (v->vec_mempool)
608 mempool_destroy(v->vec_mempool);
609
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100610 if (v->bufio)
611 dm_bufio_client_destroy(v->bufio);
612
613 kfree(v->salt);
614 kfree(v->root_digest);
615
616 if (v->tfm)
617 crypto_free_shash(v->tfm);
618
619 kfree(v->alg_name);
620
621 if (v->hash_dev)
622 dm_put_device(ti, v->hash_dev);
623
624 if (v->data_dev)
625 dm_put_device(ti, v->data_dev);
626
627 kfree(v);
628}
629
630/*
631 * Target parameters:
632 * <version> The current format is version 1.
633 * Vsn 0 is compatible with original Chromium OS releases.
634 * <data device>
635 * <hash device>
636 * <data block size>
637 * <hash block size>
638 * <the number of data blocks>
639 * <hash start block>
640 * <algorithm>
641 * <digest>
642 * <salt> Hex string or "-" if no salt.
643 */
644static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
645{
646 struct dm_verity *v;
647 unsigned num;
648 unsigned long long num_ll;
649 int r;
650 int i;
651 sector_t hash_position;
652 char dummy;
653
654 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
655 if (!v) {
656 ti->error = "Cannot allocate verity structure";
657 return -ENOMEM;
658 }
659 ti->private = v;
660 v->ti = ti;
661
662 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
663 ti->error = "Device must be readonly";
664 r = -EINVAL;
665 goto bad;
666 }
667
668 if (argc != 10) {
669 ti->error = "Invalid argument count: exactly 10 arguments required";
670 r = -EINVAL;
671 goto bad;
672 }
673
Mikulas Patocka5d8be842013-07-10 23:41:17 +0100674 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
675 num > 1) {
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100676 ti->error = "Invalid version";
677 r = -EINVAL;
678 goto bad;
679 }
680 v->version = num;
681
682 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
683 if (r) {
684 ti->error = "Data device lookup failed";
685 goto bad;
686 }
687
688 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
689 if (r) {
690 ti->error = "Data device lookup failed";
691 goto bad;
692 }
693
694 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
695 !num || (num & (num - 1)) ||
696 num < bdev_logical_block_size(v->data_dev->bdev) ||
697 num > PAGE_SIZE) {
698 ti->error = "Invalid data device block size";
699 r = -EINVAL;
700 goto bad;
701 }
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100702 v->data_dev_block_bits = __ffs(num);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100703
704 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
705 !num || (num & (num - 1)) ||
706 num < bdev_logical_block_size(v->hash_dev->bdev) ||
707 num > INT_MAX) {
708 ti->error = "Invalid hash device block size";
709 r = -EINVAL;
710 goto bad;
711 }
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100712 v->hash_dev_block_bits = __ffs(num);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100713
714 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
Mikulas Patocka1d55f6b2012-09-26 23:45:48 +0100715 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
716 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100717 ti->error = "Invalid data blocks";
718 r = -EINVAL;
719 goto bad;
720 }
721 v->data_blocks = num_ll;
722
723 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
724 ti->error = "Data device is too small";
725 r = -EINVAL;
726 goto bad;
727 }
728
729 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
Mikulas Patocka1d55f6b2012-09-26 23:45:48 +0100730 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
731 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100732 ti->error = "Invalid hash start";
733 r = -EINVAL;
734 goto bad;
735 }
736 v->hash_start = num_ll;
737
738 v->alg_name = kstrdup(argv[7], GFP_KERNEL);
739 if (!v->alg_name) {
740 ti->error = "Cannot allocate algorithm name";
741 r = -ENOMEM;
742 goto bad;
743 }
744
745 v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
746 if (IS_ERR(v->tfm)) {
747 ti->error = "Cannot initialize hash function";
748 r = PTR_ERR(v->tfm);
749 v->tfm = NULL;
750 goto bad;
751 }
752 v->digest_size = crypto_shash_digestsize(v->tfm);
753 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
754 ti->error = "Digest size too big";
755 r = -EINVAL;
756 goto bad;
757 }
758 v->shash_descsize =
759 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
760
761 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
762 if (!v->root_digest) {
763 ti->error = "Cannot allocate root digest";
764 r = -ENOMEM;
765 goto bad;
766 }
767 if (strlen(argv[8]) != v->digest_size * 2 ||
768 hex2bin(v->root_digest, argv[8], v->digest_size)) {
769 ti->error = "Invalid root digest";
770 r = -EINVAL;
771 goto bad;
772 }
773
774 if (strcmp(argv[9], "-")) {
775 v->salt_size = strlen(argv[9]) / 2;
776 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
777 if (!v->salt) {
778 ti->error = "Cannot allocate salt";
779 r = -ENOMEM;
780 goto bad;
781 }
782 if (strlen(argv[9]) != v->salt_size * 2 ||
783 hex2bin(v->salt, argv[9], v->salt_size)) {
784 ti->error = "Invalid salt";
785 r = -EINVAL;
786 goto bad;
787 }
788 }
789
790 v->hash_per_block_bits =
Mikulas Patocka553d8fe2013-07-10 23:41:17 +0100791 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100792
793 v->levels = 0;
794 if (v->data_blocks)
795 while (v->hash_per_block_bits * v->levels < 64 &&
796 (unsigned long long)(v->data_blocks - 1) >>
797 (v->hash_per_block_bits * v->levels))
798 v->levels++;
799
800 if (v->levels > DM_VERITY_MAX_LEVELS) {
801 ti->error = "Too many tree levels";
802 r = -E2BIG;
803 goto bad;
804 }
805
806 hash_position = v->hash_start;
807 for (i = v->levels - 1; i >= 0; i--) {
808 sector_t s;
809 v->hash_level_block[i] = hash_position;
Mikulas Patockab1bf2de2013-07-10 23:41:16 +0100810 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
811 >> ((i + 1) * v->hash_per_block_bits);
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100812 if (hash_position + s < hash_position) {
813 ti->error = "Hash device offset overflow";
814 r = -E2BIG;
815 goto bad;
816 }
817 hash_position += s;
818 }
819 v->hash_blocks = hash_position;
820
821 v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
822 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
823 dm_bufio_alloc_callback, NULL);
824 if (IS_ERR(v->bufio)) {
825 ti->error = "Cannot initialize dm-bufio";
826 r = PTR_ERR(v->bufio);
827 v->bufio = NULL;
828 goto bad;
829 }
830
831 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
832 ti->error = "Hash device is too small";
833 r = -E2BIG;
834 goto bad;
835 }
836
Mikulas Patockae42c3f92012-12-21 20:23:38 +0000837 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 +0100838
839 v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
840 BIO_MAX_PAGES * sizeof(struct bio_vec));
841 if (!v->vec_mempool) {
842 ti->error = "Cannot allocate vector mempool";
843 r = -ENOMEM;
844 goto bad;
845 }
846
847 /* WQ_UNBOUND greatly improves performance when running on ramdisk */
848 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
849 if (!v->verify_wq) {
850 ti->error = "Cannot allocate workqueue";
851 r = -ENOMEM;
852 goto bad;
853 }
854
855 return 0;
856
857bad:
858 verity_dtr(ti);
859
860 return r;
861}
862
863static struct target_type verity_target = {
864 .name = "verity",
Mikulas Patocka3b6b7812013-03-20 17:21:25 +0000865 .version = {1, 2, 0},
Mikulas Patockaa4ffc152012-03-28 18:43:38 +0100866 .module = THIS_MODULE,
867 .ctr = verity_ctr,
868 .dtr = verity_dtr,
869 .map = verity_map,
870 .status = verity_status,
871 .ioctl = verity_ioctl,
872 .merge = verity_merge,
873 .iterate_devices = verity_iterate_devices,
874 .io_hints = verity_io_hints,
875};
876
877static int __init dm_verity_init(void)
878{
879 int r;
880
881 r = dm_register_target(&verity_target);
882 if (r < 0)
883 DMERR("register failed %d", r);
884
885 return r;
886}
887
888static void __exit dm_verity_exit(void)
889{
890 dm_unregister_target(&verity_target);
891}
892
893module_init(dm_verity_init);
894module_exit(dm_verity_exit);
895
896MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
897MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
898MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
899MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
900MODULE_LICENSE("GPL");