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a4ffc152 MP |
1 | /* |
2 | * Copyright (C) 2012 Red Hat, Inc. | |
3 | * | |
4 | * Author: Mikulas Patocka <mpatocka@redhat.com> | |
5 | * | |
6 | * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors | |
7 | * | |
8 | * This file is released under the GPLv2. | |
9 | * | |
10 | * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set | |
11 | * default prefetch value. Data are read in "prefetch_cluster" chunks from the | |
12 | * hash device. Setting this greatly improves performance when data and hash | |
13 | * are on the same disk on different partitions on devices with poor random | |
14 | * access behavior. | |
15 | */ | |
16 | ||
17 | #include "dm-bufio.h" | |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/device-mapper.h> | |
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 | ||
31 | static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; | |
32 | ||
33 | module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR); | |
34 | ||
35 | struct 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 | ||
a4ffc152 MP |
58 | 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 | ||
66 | struct dm_verity_io { | |
67 | struct dm_verity *v; | |
a4ffc152 MP |
68 | |
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 | ||
96 | static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io) | |
97 | { | |
98 | return (struct shash_desc *)(io + 1); | |
99 | } | |
100 | ||
101 | static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io) | |
102 | { | |
103 | return (u8 *)(io + 1) + v->shash_descsize; | |
104 | } | |
105 | ||
106 | static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io) | |
107 | { | |
108 | return (u8 *)(io + 1) + v->shash_descsize + v->digest_size; | |
109 | } | |
110 | ||
111 | /* | |
112 | * Auxiliary structure appended to each dm-bufio buffer. If the value | |
113 | * hash_verified is nonzero, hash of the block has been verified. | |
114 | * | |
115 | * The variable hash_verified is set to 0 when allocating the buffer, then | |
116 | * it can be changed to 1 and it is never reset to 0 again. | |
117 | * | |
118 | * There is no lock around this value, a race condition can at worst cause | |
119 | * that multiple processes verify the hash of the same buffer simultaneously | |
120 | * and write 1 to hash_verified simultaneously. | |
121 | * This condition is harmless, so we don't need locking. | |
122 | */ | |
123 | struct buffer_aux { | |
124 | int hash_verified; | |
125 | }; | |
126 | ||
127 | /* | |
128 | * Initialize struct buffer_aux for a freshly created buffer. | |
129 | */ | |
130 | static void dm_bufio_alloc_callback(struct dm_buffer *buf) | |
131 | { | |
132 | struct buffer_aux *aux = dm_bufio_get_aux_data(buf); | |
133 | ||
134 | aux->hash_verified = 0; | |
135 | } | |
136 | ||
137 | /* | |
138 | * Translate input sector number to the sector number on the target device. | |
139 | */ | |
140 | static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) | |
141 | { | |
142 | return v->data_start + dm_target_offset(v->ti, bi_sector); | |
143 | } | |
144 | ||
145 | /* | |
146 | * Return hash position of a specified block at a specified tree level | |
147 | * (0 is the lowest level). | |
148 | * The lowest "hash_per_block_bits"-bits of the result denote hash position | |
149 | * inside a hash block. The remaining bits denote location of the hash block. | |
150 | */ | |
151 | static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, | |
152 | int level) | |
153 | { | |
154 | return block >> (level * v->hash_per_block_bits); | |
155 | } | |
156 | ||
157 | static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, | |
158 | sector_t *hash_block, unsigned *offset) | |
159 | { | |
160 | sector_t position = verity_position_at_level(v, block, level); | |
161 | unsigned idx; | |
162 | ||
163 | *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); | |
164 | ||
165 | if (!offset) | |
166 | return; | |
167 | ||
168 | idx = position & ((1 << v->hash_per_block_bits) - 1); | |
169 | if (!v->version) | |
170 | *offset = idx * v->digest_size; | |
171 | else | |
172 | *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); | |
173 | } | |
174 | ||
175 | /* | |
176 | * Verify hash of a metadata block pertaining to the specified data block | |
177 | * ("block" argument) at a specified level ("level" argument). | |
178 | * | |
179 | * On successful return, io_want_digest(v, io) contains the hash value for | |
180 | * a lower tree level or for the data block (if we're at the lowest leve). | |
181 | * | |
182 | * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. | |
183 | * If "skip_unverified" is false, unverified buffer is hashed and verified | |
184 | * against current value of io_want_digest(v, io). | |
185 | */ | |
186 | static int verity_verify_level(struct dm_verity_io *io, sector_t block, | |
187 | int level, bool skip_unverified) | |
188 | { | |
189 | struct dm_verity *v = io->v; | |
190 | struct dm_buffer *buf; | |
191 | struct buffer_aux *aux; | |
192 | u8 *data; | |
193 | int r; | |
194 | sector_t hash_block; | |
195 | unsigned offset; | |
196 | ||
197 | verity_hash_at_level(v, block, level, &hash_block, &offset); | |
198 | ||
199 | data = dm_bufio_read(v->bufio, hash_block, &buf); | |
200 | if (unlikely(IS_ERR(data))) | |
201 | return PTR_ERR(data); | |
202 | ||
203 | aux = dm_bufio_get_aux_data(buf); | |
204 | ||
205 | if (!aux->hash_verified) { | |
206 | struct shash_desc *desc; | |
207 | u8 *result; | |
208 | ||
209 | if (skip_unverified) { | |
210 | r = 1; | |
211 | goto release_ret_r; | |
212 | } | |
213 | ||
214 | desc = io_hash_desc(v, io); | |
215 | desc->tfm = v->tfm; | |
216 | desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; | |
217 | r = crypto_shash_init(desc); | |
218 | if (r < 0) { | |
219 | DMERR("crypto_shash_init failed: %d", r); | |
220 | goto release_ret_r; | |
221 | } | |
222 | ||
223 | if (likely(v->version >= 1)) { | |
224 | r = crypto_shash_update(desc, v->salt, v->salt_size); | |
225 | if (r < 0) { | |
226 | DMERR("crypto_shash_update failed: %d", r); | |
227 | goto release_ret_r; | |
228 | } | |
229 | } | |
230 | ||
231 | r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits); | |
232 | if (r < 0) { | |
233 | DMERR("crypto_shash_update failed: %d", r); | |
234 | goto release_ret_r; | |
235 | } | |
236 | ||
237 | if (!v->version) { | |
238 | r = crypto_shash_update(desc, v->salt, v->salt_size); | |
239 | if (r < 0) { | |
240 | DMERR("crypto_shash_update failed: %d", r); | |
241 | goto release_ret_r; | |
242 | } | |
243 | } | |
244 | ||
245 | result = io_real_digest(v, io); | |
246 | r = crypto_shash_final(desc, result); | |
247 | if (r < 0) { | |
248 | DMERR("crypto_shash_final failed: %d", r); | |
249 | goto release_ret_r; | |
250 | } | |
251 | if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { | |
252 | DMERR_LIMIT("metadata block %llu is corrupted", | |
253 | (unsigned long long)hash_block); | |
254 | v->hash_failed = 1; | |
255 | r = -EIO; | |
256 | goto release_ret_r; | |
257 | } else | |
258 | aux->hash_verified = 1; | |
259 | } | |
260 | ||
261 | data += offset; | |
262 | ||
263 | memcpy(io_want_digest(v, io), data, v->digest_size); | |
264 | ||
265 | dm_bufio_release(buf); | |
266 | return 0; | |
267 | ||
268 | release_ret_r: | |
269 | dm_bufio_release(buf); | |
270 | ||
271 | return r; | |
272 | } | |
273 | ||
274 | /* | |
275 | * Verify one "dm_verity_io" structure. | |
276 | */ | |
277 | static int verity_verify_io(struct dm_verity_io *io) | |
278 | { | |
279 | struct dm_verity *v = io->v; | |
280 | unsigned b; | |
281 | int i; | |
282 | unsigned vector = 0, offset = 0; | |
283 | ||
284 | for (b = 0; b < io->n_blocks; b++) { | |
285 | struct shash_desc *desc; | |
286 | u8 *result; | |
287 | int r; | |
288 | unsigned todo; | |
289 | ||
290 | if (likely(v->levels)) { | |
291 | /* | |
292 | * First, we try to get the requested hash for | |
293 | * the current block. If the hash block itself is | |
294 | * verified, zero is returned. If it isn't, this | |
295 | * function returns 0 and we fall back to whole | |
296 | * chain verification. | |
297 | */ | |
298 | int r = verity_verify_level(io, io->block + b, 0, true); | |
299 | if (likely(!r)) | |
300 | goto test_block_hash; | |
301 | if (r < 0) | |
302 | return r; | |
303 | } | |
304 | ||
305 | memcpy(io_want_digest(v, io), v->root_digest, v->digest_size); | |
306 | ||
307 | for (i = v->levels - 1; i >= 0; i--) { | |
308 | int r = verity_verify_level(io, io->block + b, i, false); | |
309 | if (unlikely(r)) | |
310 | return r; | |
311 | } | |
312 | ||
313 | test_block_hash: | |
314 | desc = io_hash_desc(v, io); | |
315 | desc->tfm = v->tfm; | |
316 | desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; | |
317 | r = crypto_shash_init(desc); | |
318 | if (r < 0) { | |
319 | DMERR("crypto_shash_init failed: %d", r); | |
320 | return r; | |
321 | } | |
322 | ||
323 | if (likely(v->version >= 1)) { | |
324 | r = crypto_shash_update(desc, v->salt, v->salt_size); | |
325 | if (r < 0) { | |
326 | DMERR("crypto_shash_update failed: %d", r); | |
327 | return r; | |
328 | } | |
329 | } | |
330 | ||
331 | todo = 1 << v->data_dev_block_bits; | |
332 | do { | |
333 | struct bio_vec *bv; | |
334 | u8 *page; | |
335 | unsigned len; | |
336 | ||
337 | BUG_ON(vector >= io->io_vec_size); | |
338 | bv = &io->io_vec[vector]; | |
339 | page = kmap_atomic(bv->bv_page); | |
340 | len = bv->bv_len - offset; | |
341 | if (likely(len >= todo)) | |
342 | len = todo; | |
343 | r = crypto_shash_update(desc, | |
344 | page + bv->bv_offset + offset, len); | |
345 | kunmap_atomic(page); | |
346 | if (r < 0) { | |
347 | DMERR("crypto_shash_update failed: %d", r); | |
348 | return r; | |
349 | } | |
350 | offset += len; | |
351 | if (likely(offset == bv->bv_len)) { | |
352 | offset = 0; | |
353 | vector++; | |
354 | } | |
355 | todo -= len; | |
356 | } while (todo); | |
357 | ||
358 | if (!v->version) { | |
359 | r = crypto_shash_update(desc, v->salt, v->salt_size); | |
360 | if (r < 0) { | |
361 | DMERR("crypto_shash_update failed: %d", r); | |
362 | return r; | |
363 | } | |
364 | } | |
365 | ||
366 | result = io_real_digest(v, io); | |
367 | r = crypto_shash_final(desc, result); | |
368 | if (r < 0) { | |
369 | DMERR("crypto_shash_final failed: %d", r); | |
370 | return r; | |
371 | } | |
372 | if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { | |
373 | DMERR_LIMIT("data block %llu is corrupted", | |
374 | (unsigned long long)(io->block + b)); | |
375 | v->hash_failed = 1; | |
376 | return -EIO; | |
377 | } | |
378 | } | |
379 | BUG_ON(vector != io->io_vec_size); | |
380 | BUG_ON(offset); | |
381 | ||
382 | return 0; | |
383 | } | |
384 | ||
385 | /* | |
386 | * End one "io" structure with a given error. | |
387 | */ | |
388 | static void verity_finish_io(struct dm_verity_io *io, int error) | |
389 | { | |
a4ffc152 | 390 | struct dm_verity *v = io->v; |
e42c3f91 | 391 | struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size); |
a4ffc152 MP |
392 | |
393 | bio->bi_end_io = io->orig_bi_end_io; | |
394 | bio->bi_private = io->orig_bi_private; | |
395 | ||
396 | if (io->io_vec != io->io_vec_inline) | |
397 | mempool_free(io->io_vec, v->vec_mempool); | |
398 | ||
a4ffc152 MP |
399 | bio_endio(bio, error); |
400 | } | |
401 | ||
402 | static void verity_work(struct work_struct *w) | |
403 | { | |
404 | struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); | |
405 | ||
406 | verity_finish_io(io, verity_verify_io(io)); | |
407 | } | |
408 | ||
409 | static void verity_end_io(struct bio *bio, int error) | |
410 | { | |
411 | struct dm_verity_io *io = bio->bi_private; | |
412 | ||
413 | if (error) { | |
414 | verity_finish_io(io, error); | |
415 | return; | |
416 | } | |
417 | ||
418 | INIT_WORK(&io->work, verity_work); | |
419 | queue_work(io->v->verify_wq, &io->work); | |
420 | } | |
421 | ||
422 | /* | |
423 | * Prefetch buffers for the specified io. | |
424 | * The root buffer is not prefetched, it is assumed that it will be cached | |
425 | * all the time. | |
426 | */ | |
427 | static void verity_prefetch_io(struct dm_verity *v, struct dm_verity_io *io) | |
428 | { | |
429 | int i; | |
430 | ||
431 | for (i = v->levels - 2; i >= 0; i--) { | |
432 | sector_t hash_block_start; | |
433 | sector_t hash_block_end; | |
434 | verity_hash_at_level(v, io->block, i, &hash_block_start, NULL); | |
435 | verity_hash_at_level(v, io->block + io->n_blocks - 1, i, &hash_block_end, NULL); | |
436 | if (!i) { | |
fe5fe906 | 437 | unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster); |
a4ffc152 MP |
438 | |
439 | cluster >>= v->data_dev_block_bits; | |
440 | if (unlikely(!cluster)) | |
441 | goto no_prefetch_cluster; | |
442 | ||
443 | if (unlikely(cluster & (cluster - 1))) | |
444 | cluster = 1 << (fls(cluster) - 1); | |
445 | ||
446 | hash_block_start &= ~(sector_t)(cluster - 1); | |
447 | hash_block_end |= cluster - 1; | |
448 | if (unlikely(hash_block_end >= v->hash_blocks)) | |
449 | hash_block_end = v->hash_blocks - 1; | |
450 | } | |
451 | no_prefetch_cluster: | |
452 | dm_bufio_prefetch(v->bufio, hash_block_start, | |
453 | hash_block_end - hash_block_start + 1); | |
454 | } | |
455 | } | |
456 | ||
457 | /* | |
458 | * Bio map function. It allocates dm_verity_io structure and bio vector and | |
459 | * fills them. Then it issues prefetches and the I/O. | |
460 | */ | |
7de3ee57 | 461 | static int verity_map(struct dm_target *ti, struct bio *bio) |
a4ffc152 MP |
462 | { |
463 | struct dm_verity *v = ti->private; | |
464 | struct dm_verity_io *io; | |
465 | ||
466 | bio->bi_bdev = v->data_dev->bdev; | |
467 | bio->bi_sector = verity_map_sector(v, bio->bi_sector); | |
468 | ||
469 | if (((unsigned)bio->bi_sector | bio_sectors(bio)) & | |
470 | ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { | |
471 | DMERR_LIMIT("unaligned io"); | |
472 | return -EIO; | |
473 | } | |
474 | ||
475 | if ((bio->bi_sector + bio_sectors(bio)) >> | |
476 | (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { | |
477 | DMERR_LIMIT("io out of range"); | |
478 | return -EIO; | |
479 | } | |
480 | ||
481 | if (bio_data_dir(bio) == WRITE) | |
482 | return -EIO; | |
483 | ||
e42c3f91 | 484 | io = dm_per_bio_data(bio, ti->per_bio_data_size); |
a4ffc152 | 485 | io->v = v; |
a4ffc152 MP |
486 | io->orig_bi_end_io = bio->bi_end_io; |
487 | io->orig_bi_private = bio->bi_private; | |
488 | io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); | |
489 | io->n_blocks = bio->bi_size >> v->data_dev_block_bits; | |
490 | ||
491 | bio->bi_end_io = verity_end_io; | |
492 | bio->bi_private = io; | |
493 | io->io_vec_size = bio->bi_vcnt - bio->bi_idx; | |
494 | if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE) | |
495 | io->io_vec = io->io_vec_inline; | |
496 | else | |
497 | io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO); | |
498 | memcpy(io->io_vec, bio_iovec(bio), | |
499 | io->io_vec_size * sizeof(struct bio_vec)); | |
500 | ||
501 | verity_prefetch_io(v, io); | |
502 | ||
503 | generic_make_request(bio); | |
504 | ||
505 | return DM_MAPIO_SUBMITTED; | |
506 | } | |
507 | ||
508 | /* | |
509 | * Status: V (valid) or C (corruption found) | |
510 | */ | |
511 | static int verity_status(struct dm_target *ti, status_type_t type, | |
1f4e0ff0 | 512 | unsigned status_flags, char *result, unsigned maxlen) |
a4ffc152 MP |
513 | { |
514 | struct dm_verity *v = ti->private; | |
515 | unsigned sz = 0; | |
516 | unsigned x; | |
517 | ||
518 | switch (type) { | |
519 | case STATUSTYPE_INFO: | |
520 | DMEMIT("%c", v->hash_failed ? 'C' : 'V'); | |
521 | break; | |
522 | case STATUSTYPE_TABLE: | |
523 | DMEMIT("%u %s %s %u %u %llu %llu %s ", | |
524 | v->version, | |
525 | v->data_dev->name, | |
526 | v->hash_dev->name, | |
527 | 1 << v->data_dev_block_bits, | |
528 | 1 << v->hash_dev_block_bits, | |
529 | (unsigned long long)v->data_blocks, | |
530 | (unsigned long long)v->hash_start, | |
531 | v->alg_name | |
532 | ); | |
533 | for (x = 0; x < v->digest_size; x++) | |
534 | DMEMIT("%02x", v->root_digest[x]); | |
535 | DMEMIT(" "); | |
536 | if (!v->salt_size) | |
537 | DMEMIT("-"); | |
538 | else | |
539 | for (x = 0; x < v->salt_size; x++) | |
540 | DMEMIT("%02x", v->salt[x]); | |
541 | break; | |
542 | } | |
543 | ||
544 | return 0; | |
545 | } | |
546 | ||
547 | static int verity_ioctl(struct dm_target *ti, unsigned cmd, | |
548 | unsigned long arg) | |
549 | { | |
550 | struct dm_verity *v = ti->private; | |
551 | int r = 0; | |
552 | ||
553 | if (v->data_start || | |
554 | ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) | |
555 | r = scsi_verify_blk_ioctl(NULL, cmd); | |
556 | ||
557 | return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode, | |
558 | cmd, arg); | |
559 | } | |
560 | ||
561 | static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm, | |
562 | struct bio_vec *biovec, int max_size) | |
563 | { | |
564 | struct dm_verity *v = ti->private; | |
565 | struct request_queue *q = bdev_get_queue(v->data_dev->bdev); | |
566 | ||
567 | if (!q->merge_bvec_fn) | |
568 | return max_size; | |
569 | ||
570 | bvm->bi_bdev = v->data_dev->bdev; | |
571 | bvm->bi_sector = verity_map_sector(v, bvm->bi_sector); | |
572 | ||
573 | return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); | |
574 | } | |
575 | ||
576 | static int verity_iterate_devices(struct dm_target *ti, | |
577 | iterate_devices_callout_fn fn, void *data) | |
578 | { | |
579 | struct dm_verity *v = ti->private; | |
580 | ||
581 | return fn(ti, v->data_dev, v->data_start, ti->len, data); | |
582 | } | |
583 | ||
584 | static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) | |
585 | { | |
586 | struct dm_verity *v = ti->private; | |
587 | ||
588 | if (limits->logical_block_size < 1 << v->data_dev_block_bits) | |
589 | limits->logical_block_size = 1 << v->data_dev_block_bits; | |
590 | ||
591 | if (limits->physical_block_size < 1 << v->data_dev_block_bits) | |
592 | limits->physical_block_size = 1 << v->data_dev_block_bits; | |
593 | ||
594 | blk_limits_io_min(limits, limits->logical_block_size); | |
595 | } | |
596 | ||
597 | static void verity_dtr(struct dm_target *ti) | |
598 | { | |
599 | struct dm_verity *v = ti->private; | |
600 | ||
601 | if (v->verify_wq) | |
602 | destroy_workqueue(v->verify_wq); | |
603 | ||
604 | if (v->vec_mempool) | |
605 | mempool_destroy(v->vec_mempool); | |
606 | ||
a4ffc152 MP |
607 | if (v->bufio) |
608 | dm_bufio_client_destroy(v->bufio); | |
609 | ||
610 | kfree(v->salt); | |
611 | kfree(v->root_digest); | |
612 | ||
613 | if (v->tfm) | |
614 | crypto_free_shash(v->tfm); | |
615 | ||
616 | kfree(v->alg_name); | |
617 | ||
618 | if (v->hash_dev) | |
619 | dm_put_device(ti, v->hash_dev); | |
620 | ||
621 | if (v->data_dev) | |
622 | dm_put_device(ti, v->data_dev); | |
623 | ||
624 | kfree(v); | |
625 | } | |
626 | ||
627 | /* | |
628 | * Target parameters: | |
629 | * <version> The current format is version 1. | |
630 | * Vsn 0 is compatible with original Chromium OS releases. | |
631 | * <data device> | |
632 | * <hash device> | |
633 | * <data block size> | |
634 | * <hash block size> | |
635 | * <the number of data blocks> | |
636 | * <hash start block> | |
637 | * <algorithm> | |
638 | * <digest> | |
639 | * <salt> Hex string or "-" if no salt. | |
640 | */ | |
641 | static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) | |
642 | { | |
643 | struct dm_verity *v; | |
644 | unsigned num; | |
645 | unsigned long long num_ll; | |
646 | int r; | |
647 | int i; | |
648 | sector_t hash_position; | |
649 | char dummy; | |
650 | ||
651 | v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); | |
652 | if (!v) { | |
653 | ti->error = "Cannot allocate verity structure"; | |
654 | return -ENOMEM; | |
655 | } | |
656 | ti->private = v; | |
657 | v->ti = ti; | |
658 | ||
659 | if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { | |
660 | ti->error = "Device must be readonly"; | |
661 | r = -EINVAL; | |
662 | goto bad; | |
663 | } | |
664 | ||
665 | if (argc != 10) { | |
666 | ti->error = "Invalid argument count: exactly 10 arguments required"; | |
667 | r = -EINVAL; | |
668 | goto bad; | |
669 | } | |
670 | ||
671 | if (sscanf(argv[0], "%d%c", &num, &dummy) != 1 || | |
672 | num < 0 || num > 1) { | |
673 | ti->error = "Invalid version"; | |
674 | r = -EINVAL; | |
675 | goto bad; | |
676 | } | |
677 | v->version = num; | |
678 | ||
679 | r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); | |
680 | if (r) { | |
681 | ti->error = "Data device lookup failed"; | |
682 | goto bad; | |
683 | } | |
684 | ||
685 | r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); | |
686 | if (r) { | |
687 | ti->error = "Data device lookup failed"; | |
688 | goto bad; | |
689 | } | |
690 | ||
691 | if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || | |
692 | !num || (num & (num - 1)) || | |
693 | num < bdev_logical_block_size(v->data_dev->bdev) || | |
694 | num > PAGE_SIZE) { | |
695 | ti->error = "Invalid data device block size"; | |
696 | r = -EINVAL; | |
697 | goto bad; | |
698 | } | |
699 | v->data_dev_block_bits = ffs(num) - 1; | |
700 | ||
701 | if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || | |
702 | !num || (num & (num - 1)) || | |
703 | num < bdev_logical_block_size(v->hash_dev->bdev) || | |
704 | num > INT_MAX) { | |
705 | ti->error = "Invalid hash device block size"; | |
706 | r = -EINVAL; | |
707 | goto bad; | |
708 | } | |
709 | v->hash_dev_block_bits = ffs(num) - 1; | |
710 | ||
711 | if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || | |
1d55f6bc MP |
712 | (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) |
713 | >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { | |
a4ffc152 MP |
714 | ti->error = "Invalid data blocks"; |
715 | r = -EINVAL; | |
716 | goto bad; | |
717 | } | |
718 | v->data_blocks = num_ll; | |
719 | ||
720 | if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { | |
721 | ti->error = "Data device is too small"; | |
722 | r = -EINVAL; | |
723 | goto bad; | |
724 | } | |
725 | ||
726 | if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || | |
1d55f6bc MP |
727 | (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) |
728 | >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { | |
a4ffc152 MP |
729 | ti->error = "Invalid hash start"; |
730 | r = -EINVAL; | |
731 | goto bad; | |
732 | } | |
733 | v->hash_start = num_ll; | |
734 | ||
735 | v->alg_name = kstrdup(argv[7], GFP_KERNEL); | |
736 | if (!v->alg_name) { | |
737 | ti->error = "Cannot allocate algorithm name"; | |
738 | r = -ENOMEM; | |
739 | goto bad; | |
740 | } | |
741 | ||
742 | v->tfm = crypto_alloc_shash(v->alg_name, 0, 0); | |
743 | if (IS_ERR(v->tfm)) { | |
744 | ti->error = "Cannot initialize hash function"; | |
745 | r = PTR_ERR(v->tfm); | |
746 | v->tfm = NULL; | |
747 | goto bad; | |
748 | } | |
749 | v->digest_size = crypto_shash_digestsize(v->tfm); | |
750 | if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { | |
751 | ti->error = "Digest size too big"; | |
752 | r = -EINVAL; | |
753 | goto bad; | |
754 | } | |
755 | v->shash_descsize = | |
756 | sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm); | |
757 | ||
758 | v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); | |
759 | if (!v->root_digest) { | |
760 | ti->error = "Cannot allocate root digest"; | |
761 | r = -ENOMEM; | |
762 | goto bad; | |
763 | } | |
764 | if (strlen(argv[8]) != v->digest_size * 2 || | |
765 | hex2bin(v->root_digest, argv[8], v->digest_size)) { | |
766 | ti->error = "Invalid root digest"; | |
767 | r = -EINVAL; | |
768 | goto bad; | |
769 | } | |
770 | ||
771 | if (strcmp(argv[9], "-")) { | |
772 | v->salt_size = strlen(argv[9]) / 2; | |
773 | v->salt = kmalloc(v->salt_size, GFP_KERNEL); | |
774 | if (!v->salt) { | |
775 | ti->error = "Cannot allocate salt"; | |
776 | r = -ENOMEM; | |
777 | goto bad; | |
778 | } | |
779 | if (strlen(argv[9]) != v->salt_size * 2 || | |
780 | hex2bin(v->salt, argv[9], v->salt_size)) { | |
781 | ti->error = "Invalid salt"; | |
782 | r = -EINVAL; | |
783 | goto bad; | |
784 | } | |
785 | } | |
786 | ||
787 | v->hash_per_block_bits = | |
788 | fls((1 << v->hash_dev_block_bits) / v->digest_size) - 1; | |
789 | ||
790 | v->levels = 0; | |
791 | if (v->data_blocks) | |
792 | while (v->hash_per_block_bits * v->levels < 64 && | |
793 | (unsigned long long)(v->data_blocks - 1) >> | |
794 | (v->hash_per_block_bits * v->levels)) | |
795 | v->levels++; | |
796 | ||
797 | if (v->levels > DM_VERITY_MAX_LEVELS) { | |
798 | ti->error = "Too many tree levels"; | |
799 | r = -E2BIG; | |
800 | goto bad; | |
801 | } | |
802 | ||
803 | hash_position = v->hash_start; | |
804 | for (i = v->levels - 1; i >= 0; i--) { | |
805 | sector_t s; | |
806 | v->hash_level_block[i] = hash_position; | |
807 | s = verity_position_at_level(v, v->data_blocks, i); | |
808 | s = (s >> v->hash_per_block_bits) + | |
809 | !!(s & ((1 << v->hash_per_block_bits) - 1)); | |
810 | if (hash_position + s < hash_position) { | |
811 | ti->error = "Hash device offset overflow"; | |
812 | r = -E2BIG; | |
813 | goto bad; | |
814 | } | |
815 | hash_position += s; | |
816 | } | |
817 | v->hash_blocks = hash_position; | |
818 | ||
819 | v->bufio = dm_bufio_client_create(v->hash_dev->bdev, | |
820 | 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), | |
821 | dm_bufio_alloc_callback, NULL); | |
822 | if (IS_ERR(v->bufio)) { | |
823 | ti->error = "Cannot initialize dm-bufio"; | |
824 | r = PTR_ERR(v->bufio); | |
825 | v->bufio = NULL; | |
826 | goto bad; | |
827 | } | |
828 | ||
829 | if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { | |
830 | ti->error = "Hash device is too small"; | |
831 | r = -E2BIG; | |
832 | goto bad; | |
833 | } | |
834 | ||
e42c3f91 | 835 | ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io)); |
a4ffc152 MP |
836 | |
837 | v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE, | |
838 | BIO_MAX_PAGES * sizeof(struct bio_vec)); | |
839 | if (!v->vec_mempool) { | |
840 | ti->error = "Cannot allocate vector mempool"; | |
841 | r = -ENOMEM; | |
842 | goto bad; | |
843 | } | |
844 | ||
845 | /* WQ_UNBOUND greatly improves performance when running on ramdisk */ | |
846 | v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); | |
847 | if (!v->verify_wq) { | |
848 | ti->error = "Cannot allocate workqueue"; | |
849 | r = -ENOMEM; | |
850 | goto bad; | |
851 | } | |
852 | ||
853 | return 0; | |
854 | ||
855 | bad: | |
856 | verity_dtr(ti); | |
857 | ||
858 | return r; | |
859 | } | |
860 | ||
861 | static struct target_type verity_target = { | |
862 | .name = "verity", | |
e42c3f91 | 863 | .version = {1, 1, 0}, |
a4ffc152 MP |
864 | .module = THIS_MODULE, |
865 | .ctr = verity_ctr, | |
866 | .dtr = verity_dtr, | |
867 | .map = verity_map, | |
868 | .status = verity_status, | |
869 | .ioctl = verity_ioctl, | |
870 | .merge = verity_merge, | |
871 | .iterate_devices = verity_iterate_devices, | |
872 | .io_hints = verity_io_hints, | |
873 | }; | |
874 | ||
875 | static int __init dm_verity_init(void) | |
876 | { | |
877 | int r; | |
878 | ||
879 | r = dm_register_target(&verity_target); | |
880 | if (r < 0) | |
881 | DMERR("register failed %d", r); | |
882 | ||
883 | return r; | |
884 | } | |
885 | ||
886 | static void __exit dm_verity_exit(void) | |
887 | { | |
888 | dm_unregister_target(&verity_target); | |
889 | } | |
890 | ||
891 | module_init(dm_verity_init); | |
892 | module_exit(dm_verity_exit); | |
893 | ||
894 | MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); | |
895 | MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); | |
896 | MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); | |
897 | MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); | |
898 | MODULE_LICENSE("GPL"); |