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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 | ||
58 | mempool_t *io_mempool; /* mempool of struct dm_verity_io */ | |
59 | mempool_t *vec_mempool; /* mempool of bio vector */ | |
60 | ||
61 | struct workqueue_struct *verify_wq; | |
62 | ||
63 | /* starting blocks for each tree level. 0 is the lowest level. */ | |
64 | sector_t hash_level_block[DM_VERITY_MAX_LEVELS]; | |
65 | }; | |
66 | ||
67 | struct dm_verity_io { | |
68 | struct dm_verity *v; | |
69 | struct bio *bio; | |
70 | ||
71 | /* original values of bio->bi_end_io and bio->bi_private */ | |
72 | bio_end_io_t *orig_bi_end_io; | |
73 | void *orig_bi_private; | |
74 | ||
75 | sector_t block; | |
76 | unsigned n_blocks; | |
77 | ||
78 | /* saved bio vector */ | |
79 | struct bio_vec *io_vec; | |
80 | unsigned io_vec_size; | |
81 | ||
82 | struct work_struct work; | |
83 | ||
84 | /* A space for short vectors; longer vectors are allocated separately. */ | |
85 | struct bio_vec io_vec_inline[DM_VERITY_IO_VEC_INLINE]; | |
86 | ||
87 | /* | |
88 | * Three variably-size fields follow this struct: | |
89 | * | |
90 | * u8 hash_desc[v->shash_descsize]; | |
91 | * u8 real_digest[v->digest_size]; | |
92 | * u8 want_digest[v->digest_size]; | |
93 | * | |
94 | * To access them use: io_hash_desc(), io_real_digest() and io_want_digest(). | |
95 | */ | |
96 | }; | |
97 | ||
98 | static 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 | ||
103 | static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io) | |
104 | { | |
105 | return (u8 *)(io + 1) + v->shash_descsize; | |
106 | } | |
107 | ||
108 | static 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 | */ | |
125 | struct buffer_aux { | |
126 | int hash_verified; | |
127 | }; | |
128 | ||
129 | /* | |
130 | * Initialize struct buffer_aux for a freshly created buffer. | |
131 | */ | |
132 | static 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 | */ | |
142 | static 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 | */ | |
153 | static 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 | ||
159 | static 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 | */ | |
188 | static 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 | ||
270 | release_ret_r: | |
271 | dm_bufio_release(buf); | |
272 | ||
273 | return r; | |
274 | } | |
275 | ||
276 | /* | |
277 | * Verify one "dm_verity_io" structure. | |
278 | */ | |
279 | static int verity_verify_io(struct dm_verity_io *io) | |
280 | { | |
281 | struct dm_verity *v = io->v; | |
282 | unsigned b; | |
283 | int i; | |
284 | unsigned vector = 0, offset = 0; | |
285 | ||
286 | for (b = 0; b < io->n_blocks; b++) { | |
287 | struct shash_desc *desc; | |
288 | u8 *result; | |
289 | int r; | |
290 | unsigned todo; | |
291 | ||
292 | if (likely(v->levels)) { | |
293 | /* | |
294 | * First, we try to get the requested hash for | |
295 | * the current block. If the hash block itself is | |
296 | * verified, zero is returned. If it isn't, this | |
297 | * function returns 0 and we fall back to whole | |
298 | * chain verification. | |
299 | */ | |
300 | int r = verity_verify_level(io, io->block + b, 0, true); | |
301 | if (likely(!r)) | |
302 | goto test_block_hash; | |
303 | if (r < 0) | |
304 | return r; | |
305 | } | |
306 | ||
307 | memcpy(io_want_digest(v, io), v->root_digest, v->digest_size); | |
308 | ||
309 | for (i = v->levels - 1; i >= 0; i--) { | |
310 | int r = verity_verify_level(io, io->block + b, i, false); | |
311 | if (unlikely(r)) | |
312 | return r; | |
313 | } | |
314 | ||
315 | test_block_hash: | |
316 | desc = io_hash_desc(v, io); | |
317 | desc->tfm = v->tfm; | |
318 | desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; | |
319 | r = crypto_shash_init(desc); | |
320 | if (r < 0) { | |
321 | DMERR("crypto_shash_init failed: %d", r); | |
322 | return r; | |
323 | } | |
324 | ||
325 | if (likely(v->version >= 1)) { | |
326 | r = crypto_shash_update(desc, v->salt, v->salt_size); | |
327 | if (r < 0) { | |
328 | DMERR("crypto_shash_update failed: %d", r); | |
329 | return r; | |
330 | } | |
331 | } | |
332 | ||
333 | todo = 1 << v->data_dev_block_bits; | |
334 | do { | |
335 | struct bio_vec *bv; | |
336 | u8 *page; | |
337 | unsigned len; | |
338 | ||
339 | BUG_ON(vector >= io->io_vec_size); | |
340 | bv = &io->io_vec[vector]; | |
341 | page = kmap_atomic(bv->bv_page); | |
342 | len = bv->bv_len - offset; | |
343 | if (likely(len >= todo)) | |
344 | len = todo; | |
345 | r = crypto_shash_update(desc, | |
346 | page + bv->bv_offset + offset, len); | |
347 | kunmap_atomic(page); | |
348 | if (r < 0) { | |
349 | DMERR("crypto_shash_update failed: %d", r); | |
350 | return r; | |
351 | } | |
352 | offset += len; | |
353 | if (likely(offset == bv->bv_len)) { | |
354 | offset = 0; | |
355 | vector++; | |
356 | } | |
357 | todo -= len; | |
358 | } while (todo); | |
359 | ||
360 | if (!v->version) { | |
361 | r = crypto_shash_update(desc, v->salt, v->salt_size); | |
362 | if (r < 0) { | |
363 | DMERR("crypto_shash_update failed: %d", r); | |
364 | return r; | |
365 | } | |
366 | } | |
367 | ||
368 | result = io_real_digest(v, io); | |
369 | r = crypto_shash_final(desc, result); | |
370 | if (r < 0) { | |
371 | DMERR("crypto_shash_final failed: %d", r); | |
372 | return r; | |
373 | } | |
374 | if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { | |
375 | DMERR_LIMIT("data block %llu is corrupted", | |
376 | (unsigned long long)(io->block + b)); | |
377 | v->hash_failed = 1; | |
378 | return -EIO; | |
379 | } | |
380 | } | |
381 | BUG_ON(vector != io->io_vec_size); | |
382 | BUG_ON(offset); | |
383 | ||
384 | return 0; | |
385 | } | |
386 | ||
387 | /* | |
388 | * End one "io" structure with a given error. | |
389 | */ | |
390 | static void verity_finish_io(struct dm_verity_io *io, int error) | |
391 | { | |
392 | struct bio *bio = io->bio; | |
393 | struct dm_verity *v = io->v; | |
394 | ||
395 | bio->bi_end_io = io->orig_bi_end_io; | |
396 | bio->bi_private = io->orig_bi_private; | |
397 | ||
398 | if (io->io_vec != io->io_vec_inline) | |
399 | mempool_free(io->io_vec, v->vec_mempool); | |
400 | ||
401 | mempool_free(io, v->io_mempool); | |
402 | ||
403 | bio_endio(bio, error); | |
404 | } | |
405 | ||
406 | static void verity_work(struct work_struct *w) | |
407 | { | |
408 | struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); | |
409 | ||
410 | verity_finish_io(io, verity_verify_io(io)); | |
411 | } | |
412 | ||
413 | static void verity_end_io(struct bio *bio, int error) | |
414 | { | |
415 | struct dm_verity_io *io = bio->bi_private; | |
416 | ||
417 | if (error) { | |
418 | verity_finish_io(io, error); | |
419 | return; | |
420 | } | |
421 | ||
422 | INIT_WORK(&io->work, verity_work); | |
423 | queue_work(io->v->verify_wq, &io->work); | |
424 | } | |
425 | ||
426 | /* | |
427 | * Prefetch buffers for the specified io. | |
428 | * The root buffer is not prefetched, it is assumed that it will be cached | |
429 | * all the time. | |
430 | */ | |
431 | static void verity_prefetch_io(struct dm_verity *v, struct dm_verity_io *io) | |
432 | { | |
433 | int i; | |
434 | ||
435 | for (i = v->levels - 2; i >= 0; i--) { | |
436 | sector_t hash_block_start; | |
437 | sector_t hash_block_end; | |
438 | verity_hash_at_level(v, io->block, i, &hash_block_start, NULL); | |
439 | verity_hash_at_level(v, io->block + io->n_blocks - 1, i, &hash_block_end, NULL); | |
440 | if (!i) { | |
441 | unsigned cluster = *(volatile unsigned *)&dm_verity_prefetch_cluster; | |
442 | ||
443 | cluster >>= v->data_dev_block_bits; | |
444 | if (unlikely(!cluster)) | |
445 | goto no_prefetch_cluster; | |
446 | ||
447 | if (unlikely(cluster & (cluster - 1))) | |
448 | cluster = 1 << (fls(cluster) - 1); | |
449 | ||
450 | hash_block_start &= ~(sector_t)(cluster - 1); | |
451 | hash_block_end |= cluster - 1; | |
452 | if (unlikely(hash_block_end >= v->hash_blocks)) | |
453 | hash_block_end = v->hash_blocks - 1; | |
454 | } | |
455 | no_prefetch_cluster: | |
456 | dm_bufio_prefetch(v->bufio, hash_block_start, | |
457 | hash_block_end - hash_block_start + 1); | |
458 | } | |
459 | } | |
460 | ||
461 | /* | |
462 | * Bio map function. It allocates dm_verity_io structure and bio vector and | |
463 | * fills them. Then it issues prefetches and the I/O. | |
464 | */ | |
465 | static int verity_map(struct dm_target *ti, struct bio *bio, | |
466 | union map_info *map_context) | |
467 | { | |
468 | struct dm_verity *v = ti->private; | |
469 | struct dm_verity_io *io; | |
470 | ||
471 | bio->bi_bdev = v->data_dev->bdev; | |
472 | bio->bi_sector = verity_map_sector(v, bio->bi_sector); | |
473 | ||
474 | if (((unsigned)bio->bi_sector | bio_sectors(bio)) & | |
475 | ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { | |
476 | DMERR_LIMIT("unaligned io"); | |
477 | return -EIO; | |
478 | } | |
479 | ||
480 | if ((bio->bi_sector + bio_sectors(bio)) >> | |
481 | (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { | |
482 | DMERR_LIMIT("io out of range"); | |
483 | return -EIO; | |
484 | } | |
485 | ||
486 | if (bio_data_dir(bio) == WRITE) | |
487 | return -EIO; | |
488 | ||
489 | io = mempool_alloc(v->io_mempool, GFP_NOIO); | |
490 | io->v = v; | |
491 | io->bio = bio; | |
492 | io->orig_bi_end_io = bio->bi_end_io; | |
493 | io->orig_bi_private = bio->bi_private; | |
494 | io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); | |
495 | io->n_blocks = bio->bi_size >> v->data_dev_block_bits; | |
496 | ||
497 | bio->bi_end_io = verity_end_io; | |
498 | bio->bi_private = io; | |
499 | io->io_vec_size = bio->bi_vcnt - bio->bi_idx; | |
500 | if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE) | |
501 | io->io_vec = io->io_vec_inline; | |
502 | else | |
503 | io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO); | |
504 | memcpy(io->io_vec, bio_iovec(bio), | |
505 | io->io_vec_size * sizeof(struct bio_vec)); | |
506 | ||
507 | verity_prefetch_io(v, io); | |
508 | ||
509 | generic_make_request(bio); | |
510 | ||
511 | return DM_MAPIO_SUBMITTED; | |
512 | } | |
513 | ||
514 | /* | |
515 | * Status: V (valid) or C (corruption found) | |
516 | */ | |
517 | static int verity_status(struct dm_target *ti, status_type_t type, | |
518 | char *result, unsigned maxlen) | |
519 | { | |
520 | struct dm_verity *v = ti->private; | |
521 | unsigned sz = 0; | |
522 | unsigned x; | |
523 | ||
524 | switch (type) { | |
525 | case STATUSTYPE_INFO: | |
526 | DMEMIT("%c", v->hash_failed ? 'C' : 'V'); | |
527 | break; | |
528 | case STATUSTYPE_TABLE: | |
529 | DMEMIT("%u %s %s %u %u %llu %llu %s ", | |
530 | v->version, | |
531 | v->data_dev->name, | |
532 | v->hash_dev->name, | |
533 | 1 << v->data_dev_block_bits, | |
534 | 1 << v->hash_dev_block_bits, | |
535 | (unsigned long long)v->data_blocks, | |
536 | (unsigned long long)v->hash_start, | |
537 | v->alg_name | |
538 | ); | |
539 | for (x = 0; x < v->digest_size; x++) | |
540 | DMEMIT("%02x", v->root_digest[x]); | |
541 | DMEMIT(" "); | |
542 | if (!v->salt_size) | |
543 | DMEMIT("-"); | |
544 | else | |
545 | for (x = 0; x < v->salt_size; x++) | |
546 | DMEMIT("%02x", v->salt[x]); | |
547 | break; | |
548 | } | |
549 | ||
550 | return 0; | |
551 | } | |
552 | ||
553 | static int verity_ioctl(struct dm_target *ti, unsigned cmd, | |
554 | unsigned long arg) | |
555 | { | |
556 | struct dm_verity *v = ti->private; | |
557 | int r = 0; | |
558 | ||
559 | if (v->data_start || | |
560 | ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) | |
561 | r = scsi_verify_blk_ioctl(NULL, cmd); | |
562 | ||
563 | return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode, | |
564 | cmd, arg); | |
565 | } | |
566 | ||
567 | static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm, | |
568 | struct bio_vec *biovec, int max_size) | |
569 | { | |
570 | struct dm_verity *v = ti->private; | |
571 | struct request_queue *q = bdev_get_queue(v->data_dev->bdev); | |
572 | ||
573 | if (!q->merge_bvec_fn) | |
574 | return max_size; | |
575 | ||
576 | bvm->bi_bdev = v->data_dev->bdev; | |
577 | bvm->bi_sector = verity_map_sector(v, bvm->bi_sector); | |
578 | ||
579 | return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); | |
580 | } | |
581 | ||
582 | static int verity_iterate_devices(struct dm_target *ti, | |
583 | iterate_devices_callout_fn fn, void *data) | |
584 | { | |
585 | struct dm_verity *v = ti->private; | |
586 | ||
587 | return fn(ti, v->data_dev, v->data_start, ti->len, data); | |
588 | } | |
589 | ||
590 | static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) | |
591 | { | |
592 | struct dm_verity *v = ti->private; | |
593 | ||
594 | if (limits->logical_block_size < 1 << v->data_dev_block_bits) | |
595 | limits->logical_block_size = 1 << v->data_dev_block_bits; | |
596 | ||
597 | if (limits->physical_block_size < 1 << v->data_dev_block_bits) | |
598 | limits->physical_block_size = 1 << v->data_dev_block_bits; | |
599 | ||
600 | blk_limits_io_min(limits, limits->logical_block_size); | |
601 | } | |
602 | ||
603 | static void verity_dtr(struct dm_target *ti) | |
604 | { | |
605 | struct dm_verity *v = ti->private; | |
606 | ||
607 | if (v->verify_wq) | |
608 | destroy_workqueue(v->verify_wq); | |
609 | ||
610 | if (v->vec_mempool) | |
611 | mempool_destroy(v->vec_mempool); | |
612 | ||
613 | if (v->io_mempool) | |
614 | mempool_destroy(v->io_mempool); | |
615 | ||
616 | if (v->bufio) | |
617 | dm_bufio_client_destroy(v->bufio); | |
618 | ||
619 | kfree(v->salt); | |
620 | kfree(v->root_digest); | |
621 | ||
622 | if (v->tfm) | |
623 | crypto_free_shash(v->tfm); | |
624 | ||
625 | kfree(v->alg_name); | |
626 | ||
627 | if (v->hash_dev) | |
628 | dm_put_device(ti, v->hash_dev); | |
629 | ||
630 | if (v->data_dev) | |
631 | dm_put_device(ti, v->data_dev); | |
632 | ||
633 | kfree(v); | |
634 | } | |
635 | ||
636 | /* | |
637 | * Target parameters: | |
638 | * <version> The current format is version 1. | |
639 | * Vsn 0 is compatible with original Chromium OS releases. | |
640 | * <data device> | |
641 | * <hash device> | |
642 | * <data block size> | |
643 | * <hash block size> | |
644 | * <the number of data blocks> | |
645 | * <hash start block> | |
646 | * <algorithm> | |
647 | * <digest> | |
648 | * <salt> Hex string or "-" if no salt. | |
649 | */ | |
650 | static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) | |
651 | { | |
652 | struct dm_verity *v; | |
653 | unsigned num; | |
654 | unsigned long long num_ll; | |
655 | int r; | |
656 | int i; | |
657 | sector_t hash_position; | |
658 | char dummy; | |
659 | ||
660 | v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); | |
661 | if (!v) { | |
662 | ti->error = "Cannot allocate verity structure"; | |
663 | return -ENOMEM; | |
664 | } | |
665 | ti->private = v; | |
666 | v->ti = ti; | |
667 | ||
668 | if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { | |
669 | ti->error = "Device must be readonly"; | |
670 | r = -EINVAL; | |
671 | goto bad; | |
672 | } | |
673 | ||
674 | if (argc != 10) { | |
675 | ti->error = "Invalid argument count: exactly 10 arguments required"; | |
676 | r = -EINVAL; | |
677 | goto bad; | |
678 | } | |
679 | ||
680 | if (sscanf(argv[0], "%d%c", &num, &dummy) != 1 || | |
681 | num < 0 || num > 1) { | |
682 | ti->error = "Invalid version"; | |
683 | r = -EINVAL; | |
684 | goto bad; | |
685 | } | |
686 | v->version = num; | |
687 | ||
688 | r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); | |
689 | if (r) { | |
690 | ti->error = "Data device lookup failed"; | |
691 | goto bad; | |
692 | } | |
693 | ||
694 | r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); | |
695 | if (r) { | |
696 | ti->error = "Data device lookup failed"; | |
697 | goto bad; | |
698 | } | |
699 | ||
700 | if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || | |
701 | !num || (num & (num - 1)) || | |
702 | num < bdev_logical_block_size(v->data_dev->bdev) || | |
703 | num > PAGE_SIZE) { | |
704 | ti->error = "Invalid data device block size"; | |
705 | r = -EINVAL; | |
706 | goto bad; | |
707 | } | |
708 | v->data_dev_block_bits = ffs(num) - 1; | |
709 | ||
710 | if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || | |
711 | !num || (num & (num - 1)) || | |
712 | num < bdev_logical_block_size(v->hash_dev->bdev) || | |
713 | num > INT_MAX) { | |
714 | ti->error = "Invalid hash device block size"; | |
715 | r = -EINVAL; | |
716 | goto bad; | |
717 | } | |
718 | v->hash_dev_block_bits = ffs(num) - 1; | |
719 | ||
720 | if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || | |
721 | num_ll << (v->data_dev_block_bits - SECTOR_SHIFT) != | |
722 | (sector_t)num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) { | |
723 | ti->error = "Invalid data blocks"; | |
724 | r = -EINVAL; | |
725 | goto bad; | |
726 | } | |
727 | v->data_blocks = num_ll; | |
728 | ||
729 | if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { | |
730 | ti->error = "Data device is too small"; | |
731 | r = -EINVAL; | |
732 | goto bad; | |
733 | } | |
734 | ||
735 | if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || | |
736 | num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT) != | |
737 | (sector_t)num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) { | |
738 | ti->error = "Invalid hash start"; | |
739 | r = -EINVAL; | |
740 | goto bad; | |
741 | } | |
742 | v->hash_start = num_ll; | |
743 | ||
744 | v->alg_name = kstrdup(argv[7], GFP_KERNEL); | |
745 | if (!v->alg_name) { | |
746 | ti->error = "Cannot allocate algorithm name"; | |
747 | r = -ENOMEM; | |
748 | goto bad; | |
749 | } | |
750 | ||
751 | v->tfm = crypto_alloc_shash(v->alg_name, 0, 0); | |
752 | if (IS_ERR(v->tfm)) { | |
753 | ti->error = "Cannot initialize hash function"; | |
754 | r = PTR_ERR(v->tfm); | |
755 | v->tfm = NULL; | |
756 | goto bad; | |
757 | } | |
758 | v->digest_size = crypto_shash_digestsize(v->tfm); | |
759 | if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { | |
760 | ti->error = "Digest size too big"; | |
761 | r = -EINVAL; | |
762 | goto bad; | |
763 | } | |
764 | v->shash_descsize = | |
765 | sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm); | |
766 | ||
767 | v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); | |
768 | if (!v->root_digest) { | |
769 | ti->error = "Cannot allocate root digest"; | |
770 | r = -ENOMEM; | |
771 | goto bad; | |
772 | } | |
773 | if (strlen(argv[8]) != v->digest_size * 2 || | |
774 | hex2bin(v->root_digest, argv[8], v->digest_size)) { | |
775 | ti->error = "Invalid root digest"; | |
776 | r = -EINVAL; | |
777 | goto bad; | |
778 | } | |
779 | ||
780 | if (strcmp(argv[9], "-")) { | |
781 | v->salt_size = strlen(argv[9]) / 2; | |
782 | v->salt = kmalloc(v->salt_size, GFP_KERNEL); | |
783 | if (!v->salt) { | |
784 | ti->error = "Cannot allocate salt"; | |
785 | r = -ENOMEM; | |
786 | goto bad; | |
787 | } | |
788 | if (strlen(argv[9]) != v->salt_size * 2 || | |
789 | hex2bin(v->salt, argv[9], v->salt_size)) { | |
790 | ti->error = "Invalid salt"; | |
791 | r = -EINVAL; | |
792 | goto bad; | |
793 | } | |
794 | } | |
795 | ||
796 | v->hash_per_block_bits = | |
797 | fls((1 << v->hash_dev_block_bits) / v->digest_size) - 1; | |
798 | ||
799 | v->levels = 0; | |
800 | if (v->data_blocks) | |
801 | while (v->hash_per_block_bits * v->levels < 64 && | |
802 | (unsigned long long)(v->data_blocks - 1) >> | |
803 | (v->hash_per_block_bits * v->levels)) | |
804 | v->levels++; | |
805 | ||
806 | if (v->levels > DM_VERITY_MAX_LEVELS) { | |
807 | ti->error = "Too many tree levels"; | |
808 | r = -E2BIG; | |
809 | goto bad; | |
810 | } | |
811 | ||
812 | hash_position = v->hash_start; | |
813 | for (i = v->levels - 1; i >= 0; i--) { | |
814 | sector_t s; | |
815 | v->hash_level_block[i] = hash_position; | |
816 | s = verity_position_at_level(v, v->data_blocks, i); | |
817 | s = (s >> v->hash_per_block_bits) + | |
818 | !!(s & ((1 << v->hash_per_block_bits) - 1)); | |
819 | if (hash_position + s < hash_position) { | |
820 | ti->error = "Hash device offset overflow"; | |
821 | r = -E2BIG; | |
822 | goto bad; | |
823 | } | |
824 | hash_position += s; | |
825 | } | |
826 | v->hash_blocks = hash_position; | |
827 | ||
828 | v->bufio = dm_bufio_client_create(v->hash_dev->bdev, | |
829 | 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), | |
830 | dm_bufio_alloc_callback, NULL); | |
831 | if (IS_ERR(v->bufio)) { | |
832 | ti->error = "Cannot initialize dm-bufio"; | |
833 | r = PTR_ERR(v->bufio); | |
834 | v->bufio = NULL; | |
835 | goto bad; | |
836 | } | |
837 | ||
838 | if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { | |
839 | ti->error = "Hash device is too small"; | |
840 | r = -E2BIG; | |
841 | goto bad; | |
842 | } | |
843 | ||
844 | v->io_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE, | |
845 | sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2); | |
846 | if (!v->io_mempool) { | |
847 | ti->error = "Cannot allocate io mempool"; | |
848 | r = -ENOMEM; | |
849 | goto bad; | |
850 | } | |
851 | ||
852 | v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE, | |
853 | BIO_MAX_PAGES * sizeof(struct bio_vec)); | |
854 | if (!v->vec_mempool) { | |
855 | ti->error = "Cannot allocate vector mempool"; | |
856 | r = -ENOMEM; | |
857 | goto bad; | |
858 | } | |
859 | ||
860 | /* WQ_UNBOUND greatly improves performance when running on ramdisk */ | |
861 | v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); | |
862 | if (!v->verify_wq) { | |
863 | ti->error = "Cannot allocate workqueue"; | |
864 | r = -ENOMEM; | |
865 | goto bad; | |
866 | } | |
867 | ||
868 | return 0; | |
869 | ||
870 | bad: | |
871 | verity_dtr(ti); | |
872 | ||
873 | return r; | |
874 | } | |
875 | ||
876 | static struct target_type verity_target = { | |
877 | .name = "verity", | |
878 | .version = {1, 0, 0}, | |
879 | .module = THIS_MODULE, | |
880 | .ctr = verity_ctr, | |
881 | .dtr = verity_dtr, | |
882 | .map = verity_map, | |
883 | .status = verity_status, | |
884 | .ioctl = verity_ioctl, | |
885 | .merge = verity_merge, | |
886 | .iterate_devices = verity_iterate_devices, | |
887 | .io_hints = verity_io_hints, | |
888 | }; | |
889 | ||
890 | static int __init dm_verity_init(void) | |
891 | { | |
892 | int r; | |
893 | ||
894 | r = dm_register_target(&verity_target); | |
895 | if (r < 0) | |
896 | DMERR("register failed %d", r); | |
897 | ||
898 | return r; | |
899 | } | |
900 | ||
901 | static void __exit dm_verity_exit(void) | |
902 | { | |
903 | dm_unregister_target(&verity_target); | |
904 | } | |
905 | ||
906 | module_init(dm_verity_init); | |
907 | module_exit(dm_verity_exit); | |
908 | ||
909 | MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); | |
910 | MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); | |
911 | MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); | |
912 | MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); | |
913 | MODULE_LICENSE("GPL"); |