1 /* 2 * Copyright (C) 2012 Red Hat, Inc. 3 * 4 * Author: Mikulas Patocka <mpatocka@redhat.com> 5 * 6 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors 7 * 8 * This file is released under the GPLv2. 9 * 10 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set 11 * default prefetch value. Data are read in "prefetch_cluster" chunks from the 12 * hash device. Setting this greatly improves performance when data and hash 13 * are on the same disk on different partitions on devices with poor random 14 * access behavior. 15 */ 16 17 #include "dm-verity.h" 18 #include "dm-verity-fec.h" 19 20 #include <linux/module.h> 21 #include <linux/reboot.h> 22 23 #define DM_MSG_PREFIX "verity" 24 25 #define DM_VERITY_ENV_LENGTH 42 26 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 27 28 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 29 30 #define DM_VERITY_MAX_CORRUPTED_ERRS 100 31 32 #define DM_VERITY_OPT_LOGGING "ignore_corruption" 33 #define DM_VERITY_OPT_RESTART "restart_on_corruption" 34 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 35 36 #define DM_VERITY_OPTS_MAX (2 + DM_VERITY_OPTS_FEC) 37 38 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 39 40 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR); 41 42 struct dm_verity_prefetch_work { 43 struct work_struct work; 44 struct dm_verity *v; 45 sector_t block; 46 unsigned n_blocks; 47 }; 48 49 /* 50 * Auxiliary structure appended to each dm-bufio buffer. If the value 51 * hash_verified is nonzero, hash of the block has been verified. 52 * 53 * The variable hash_verified is set to 0 when allocating the buffer, then 54 * it can be changed to 1 and it is never reset to 0 again. 55 * 56 * There is no lock around this value, a race condition can at worst cause 57 * that multiple processes verify the hash of the same buffer simultaneously 58 * and write 1 to hash_verified simultaneously. 59 * This condition is harmless, so we don't need locking. 60 */ 61 struct buffer_aux { 62 int hash_verified; 63 }; 64 65 /* 66 * Initialize struct buffer_aux for a freshly created buffer. 67 */ 68 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 69 { 70 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 71 72 aux->hash_verified = 0; 73 } 74 75 /* 76 * Translate input sector number to the sector number on the target device. 77 */ 78 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 79 { 80 return v->data_start + dm_target_offset(v->ti, bi_sector); 81 } 82 83 /* 84 * Return hash position of a specified block at a specified tree level 85 * (0 is the lowest level). 86 * The lowest "hash_per_block_bits"-bits of the result denote hash position 87 * inside a hash block. The remaining bits denote location of the hash block. 88 */ 89 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 90 int level) 91 { 92 return block >> (level * v->hash_per_block_bits); 93 } 94 95 /* 96 * Wrapper for crypto_shash_init, which handles verity salting. 97 */ 98 static int verity_hash_init(struct dm_verity *v, struct shash_desc *desc) 99 { 100 int r; 101 102 desc->tfm = v->tfm; 103 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; 104 105 r = crypto_shash_init(desc); 106 107 if (unlikely(r < 0)) { 108 DMERR("crypto_shash_init failed: %d", r); 109 return r; 110 } 111 112 if (likely(v->version >= 1)) { 113 r = crypto_shash_update(desc, v->salt, v->salt_size); 114 115 if (unlikely(r < 0)) { 116 DMERR("crypto_shash_update failed: %d", r); 117 return r; 118 } 119 } 120 121 return 0; 122 } 123 124 static int verity_hash_update(struct dm_verity *v, struct shash_desc *desc, 125 const u8 *data, size_t len) 126 { 127 int r = crypto_shash_update(desc, data, len); 128 129 if (unlikely(r < 0)) 130 DMERR("crypto_shash_update failed: %d", r); 131 132 return r; 133 } 134 135 static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc, 136 u8 *digest) 137 { 138 int r; 139 140 if (unlikely(!v->version)) { 141 r = crypto_shash_update(desc, v->salt, v->salt_size); 142 143 if (r < 0) { 144 DMERR("crypto_shash_update failed: %d", r); 145 return r; 146 } 147 } 148 149 r = crypto_shash_final(desc, digest); 150 151 if (unlikely(r < 0)) 152 DMERR("crypto_shash_final failed: %d", r); 153 154 return r; 155 } 156 157 int verity_hash(struct dm_verity *v, struct shash_desc *desc, 158 const u8 *data, size_t len, u8 *digest) 159 { 160 int r; 161 162 r = verity_hash_init(v, desc); 163 if (unlikely(r < 0)) 164 return r; 165 166 r = verity_hash_update(v, desc, data, len); 167 if (unlikely(r < 0)) 168 return r; 169 170 return verity_hash_final(v, desc, digest); 171 } 172 173 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 174 sector_t *hash_block, unsigned *offset) 175 { 176 sector_t position = verity_position_at_level(v, block, level); 177 unsigned idx; 178 179 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 180 181 if (!offset) 182 return; 183 184 idx = position & ((1 << v->hash_per_block_bits) - 1); 185 if (!v->version) 186 *offset = idx * v->digest_size; 187 else 188 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 189 } 190 191 /* 192 * Handle verification errors. 193 */ 194 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 195 unsigned long long block) 196 { 197 char verity_env[DM_VERITY_ENV_LENGTH]; 198 char *envp[] = { verity_env, NULL }; 199 const char *type_str = ""; 200 struct mapped_device *md = dm_table_get_md(v->ti->table); 201 202 /* Corruption should be visible in device status in all modes */ 203 v->hash_failed = 1; 204 205 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 206 goto out; 207 208 v->corrupted_errs++; 209 210 switch (type) { 211 case DM_VERITY_BLOCK_TYPE_DATA: 212 type_str = "data"; 213 break; 214 case DM_VERITY_BLOCK_TYPE_METADATA: 215 type_str = "metadata"; 216 break; 217 default: 218 BUG(); 219 } 220 221 DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str, 222 block); 223 224 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) 225 DMERR("%s: reached maximum errors", v->data_dev->name); 226 227 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 228 DM_VERITY_ENV_VAR_NAME, type, block); 229 230 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 231 232 out: 233 if (v->mode == DM_VERITY_MODE_LOGGING) 234 return 0; 235 236 if (v->mode == DM_VERITY_MODE_RESTART) 237 kernel_restart("dm-verity device corrupted"); 238 239 return 1; 240 } 241 242 /* 243 * Verify hash of a metadata block pertaining to the specified data block 244 * ("block" argument) at a specified level ("level" argument). 245 * 246 * On successful return, verity_io_want_digest(v, io) contains the hash value 247 * for a lower tree level or for the data block (if we're at the lowest level). 248 * 249 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 250 * If "skip_unverified" is false, unverified buffer is hashed and verified 251 * against current value of verity_io_want_digest(v, io). 252 */ 253 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 254 sector_t block, int level, bool skip_unverified, 255 u8 *want_digest) 256 { 257 struct dm_buffer *buf; 258 struct buffer_aux *aux; 259 u8 *data; 260 int r; 261 sector_t hash_block; 262 unsigned offset; 263 264 verity_hash_at_level(v, block, level, &hash_block, &offset); 265 266 data = dm_bufio_read(v->bufio, hash_block, &buf); 267 if (IS_ERR(data)) 268 return PTR_ERR(data); 269 270 aux = dm_bufio_get_aux_data(buf); 271 272 if (!aux->hash_verified) { 273 if (skip_unverified) { 274 r = 1; 275 goto release_ret_r; 276 } 277 278 r = verity_hash(v, verity_io_hash_desc(v, io), 279 data, 1 << v->hash_dev_block_bits, 280 verity_io_real_digest(v, io)); 281 if (unlikely(r < 0)) 282 goto release_ret_r; 283 284 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 285 v->digest_size) == 0)) 286 aux->hash_verified = 1; 287 else if (verity_fec_decode(v, io, 288 DM_VERITY_BLOCK_TYPE_METADATA, 289 hash_block, data, NULL) == 0) 290 aux->hash_verified = 1; 291 else if (verity_handle_err(v, 292 DM_VERITY_BLOCK_TYPE_METADATA, 293 hash_block)) { 294 r = -EIO; 295 goto release_ret_r; 296 } 297 } 298 299 data += offset; 300 memcpy(want_digest, data, v->digest_size); 301 r = 0; 302 303 release_ret_r: 304 dm_bufio_release(buf); 305 return r; 306 } 307 308 /* 309 * Find a hash for a given block, write it to digest and verify the integrity 310 * of the hash tree if necessary. 311 */ 312 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 313 sector_t block, u8 *digest, bool *is_zero) 314 { 315 int r = 0, i; 316 317 if (likely(v->levels)) { 318 /* 319 * First, we try to get the requested hash for 320 * the current block. If the hash block itself is 321 * verified, zero is returned. If it isn't, this 322 * function returns 1 and we fall back to whole 323 * chain verification. 324 */ 325 r = verity_verify_level(v, io, block, 0, true, digest); 326 if (likely(r <= 0)) 327 goto out; 328 } 329 330 memcpy(digest, v->root_digest, v->digest_size); 331 332 for (i = v->levels - 1; i >= 0; i--) { 333 r = verity_verify_level(v, io, block, i, false, digest); 334 if (unlikely(r)) 335 goto out; 336 } 337 out: 338 if (!r && v->zero_digest) 339 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 340 else 341 *is_zero = false; 342 343 return r; 344 } 345 346 /* 347 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 348 * starting from iter. 349 */ 350 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 351 struct bvec_iter *iter, 352 int (*process)(struct dm_verity *v, 353 struct dm_verity_io *io, u8 *data, 354 size_t len)) 355 { 356 unsigned todo = 1 << v->data_dev_block_bits; 357 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 358 359 do { 360 int r; 361 u8 *page; 362 unsigned len; 363 struct bio_vec bv = bio_iter_iovec(bio, *iter); 364 365 page = kmap_atomic(bv.bv_page); 366 len = bv.bv_len; 367 368 if (likely(len >= todo)) 369 len = todo; 370 371 r = process(v, io, page + bv.bv_offset, len); 372 kunmap_atomic(page); 373 374 if (r < 0) 375 return r; 376 377 bio_advance_iter(bio, iter, len); 378 todo -= len; 379 } while (todo); 380 381 return 0; 382 } 383 384 static int verity_bv_hash_update(struct dm_verity *v, struct dm_verity_io *io, 385 u8 *data, size_t len) 386 { 387 return verity_hash_update(v, verity_io_hash_desc(v, io), data, len); 388 } 389 390 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 391 u8 *data, size_t len) 392 { 393 memset(data, 0, len); 394 return 0; 395 } 396 397 /* 398 * Verify one "dm_verity_io" structure. 399 */ 400 static int verity_verify_io(struct dm_verity_io *io) 401 { 402 bool is_zero; 403 struct dm_verity *v = io->v; 404 struct bvec_iter start; 405 unsigned b; 406 407 for (b = 0; b < io->n_blocks; b++) { 408 int r; 409 struct shash_desc *desc = verity_io_hash_desc(v, io); 410 411 r = verity_hash_for_block(v, io, io->block + b, 412 verity_io_want_digest(v, io), 413 &is_zero); 414 if (unlikely(r < 0)) 415 return r; 416 417 if (is_zero) { 418 /* 419 * If we expect a zero block, don't validate, just 420 * return zeros. 421 */ 422 r = verity_for_bv_block(v, io, &io->iter, 423 verity_bv_zero); 424 if (unlikely(r < 0)) 425 return r; 426 427 continue; 428 } 429 430 r = verity_hash_init(v, desc); 431 if (unlikely(r < 0)) 432 return r; 433 434 start = io->iter; 435 r = verity_for_bv_block(v, io, &io->iter, verity_bv_hash_update); 436 if (unlikely(r < 0)) 437 return r; 438 439 r = verity_hash_final(v, desc, verity_io_real_digest(v, io)); 440 if (unlikely(r < 0)) 441 return r; 442 443 if (likely(memcmp(verity_io_real_digest(v, io), 444 verity_io_want_digest(v, io), v->digest_size) == 0)) 445 continue; 446 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 447 io->block + b, NULL, &start) == 0) 448 continue; 449 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 450 io->block + b)) 451 return -EIO; 452 } 453 454 return 0; 455 } 456 457 /* 458 * End one "io" structure with a given error. 459 */ 460 static void verity_finish_io(struct dm_verity_io *io, int error) 461 { 462 struct dm_verity *v = io->v; 463 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 464 465 bio->bi_end_io = io->orig_bi_end_io; 466 bio->bi_error = error; 467 468 verity_fec_finish_io(io); 469 470 bio_endio(bio); 471 } 472 473 static void verity_work(struct work_struct *w) 474 { 475 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 476 477 verity_finish_io(io, verity_verify_io(io)); 478 } 479 480 static void verity_end_io(struct bio *bio) 481 { 482 struct dm_verity_io *io = bio->bi_private; 483 484 if (bio->bi_error && !verity_fec_is_enabled(io->v)) { 485 verity_finish_io(io, bio->bi_error); 486 return; 487 } 488 489 INIT_WORK(&io->work, verity_work); 490 queue_work(io->v->verify_wq, &io->work); 491 } 492 493 /* 494 * Prefetch buffers for the specified io. 495 * The root buffer is not prefetched, it is assumed that it will be cached 496 * all the time. 497 */ 498 static void verity_prefetch_io(struct work_struct *work) 499 { 500 struct dm_verity_prefetch_work *pw = 501 container_of(work, struct dm_verity_prefetch_work, work); 502 struct dm_verity *v = pw->v; 503 int i; 504 505 for (i = v->levels - 2; i >= 0; i--) { 506 sector_t hash_block_start; 507 sector_t hash_block_end; 508 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 509 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 510 if (!i) { 511 unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster); 512 513 cluster >>= v->data_dev_block_bits; 514 if (unlikely(!cluster)) 515 goto no_prefetch_cluster; 516 517 if (unlikely(cluster & (cluster - 1))) 518 cluster = 1 << __fls(cluster); 519 520 hash_block_start &= ~(sector_t)(cluster - 1); 521 hash_block_end |= cluster - 1; 522 if (unlikely(hash_block_end >= v->hash_blocks)) 523 hash_block_end = v->hash_blocks - 1; 524 } 525 no_prefetch_cluster: 526 dm_bufio_prefetch(v->bufio, hash_block_start, 527 hash_block_end - hash_block_start + 1); 528 } 529 530 kfree(pw); 531 } 532 533 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 534 { 535 struct dm_verity_prefetch_work *pw; 536 537 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 538 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 539 540 if (!pw) 541 return; 542 543 INIT_WORK(&pw->work, verity_prefetch_io); 544 pw->v = v; 545 pw->block = io->block; 546 pw->n_blocks = io->n_blocks; 547 queue_work(v->verify_wq, &pw->work); 548 } 549 550 /* 551 * Bio map function. It allocates dm_verity_io structure and bio vector and 552 * fills them. Then it issues prefetches and the I/O. 553 */ 554 static int verity_map(struct dm_target *ti, struct bio *bio) 555 { 556 struct dm_verity *v = ti->private; 557 struct dm_verity_io *io; 558 559 bio->bi_bdev = v->data_dev->bdev; 560 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 561 562 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) & 563 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 564 DMERR_LIMIT("unaligned io"); 565 return -EIO; 566 } 567 568 if (bio_end_sector(bio) >> 569 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 570 DMERR_LIMIT("io out of range"); 571 return -EIO; 572 } 573 574 if (bio_data_dir(bio) == WRITE) 575 return -EIO; 576 577 io = dm_per_bio_data(bio, ti->per_io_data_size); 578 io->v = v; 579 io->orig_bi_end_io = bio->bi_end_io; 580 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 581 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 582 583 bio->bi_end_io = verity_end_io; 584 bio->bi_private = io; 585 io->iter = bio->bi_iter; 586 587 verity_fec_init_io(io); 588 589 verity_submit_prefetch(v, io); 590 591 generic_make_request(bio); 592 593 return DM_MAPIO_SUBMITTED; 594 } 595 596 /* 597 * Status: V (valid) or C (corruption found) 598 */ 599 static void verity_status(struct dm_target *ti, status_type_t type, 600 unsigned status_flags, char *result, unsigned maxlen) 601 { 602 struct dm_verity *v = ti->private; 603 unsigned args = 0; 604 unsigned sz = 0; 605 unsigned x; 606 607 switch (type) { 608 case STATUSTYPE_INFO: 609 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 610 break; 611 case STATUSTYPE_TABLE: 612 DMEMIT("%u %s %s %u %u %llu %llu %s ", 613 v->version, 614 v->data_dev->name, 615 v->hash_dev->name, 616 1 << v->data_dev_block_bits, 617 1 << v->hash_dev_block_bits, 618 (unsigned long long)v->data_blocks, 619 (unsigned long long)v->hash_start, 620 v->alg_name 621 ); 622 for (x = 0; x < v->digest_size; x++) 623 DMEMIT("%02x", v->root_digest[x]); 624 DMEMIT(" "); 625 if (!v->salt_size) 626 DMEMIT("-"); 627 else 628 for (x = 0; x < v->salt_size; x++) 629 DMEMIT("%02x", v->salt[x]); 630 if (v->mode != DM_VERITY_MODE_EIO) 631 args++; 632 if (verity_fec_is_enabled(v)) 633 args += DM_VERITY_OPTS_FEC; 634 if (v->zero_digest) 635 args++; 636 if (!args) 637 return; 638 DMEMIT(" %u", args); 639 if (v->mode != DM_VERITY_MODE_EIO) { 640 DMEMIT(" "); 641 switch (v->mode) { 642 case DM_VERITY_MODE_LOGGING: 643 DMEMIT(DM_VERITY_OPT_LOGGING); 644 break; 645 case DM_VERITY_MODE_RESTART: 646 DMEMIT(DM_VERITY_OPT_RESTART); 647 break; 648 default: 649 BUG(); 650 } 651 } 652 if (v->zero_digest) 653 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 654 sz = verity_fec_status_table(v, sz, result, maxlen); 655 break; 656 } 657 } 658 659 static int verity_prepare_ioctl(struct dm_target *ti, 660 struct block_device **bdev, fmode_t *mode) 661 { 662 struct dm_verity *v = ti->private; 663 664 *bdev = v->data_dev->bdev; 665 666 if (v->data_start || 667 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) 668 return 1; 669 return 0; 670 } 671 672 static int verity_iterate_devices(struct dm_target *ti, 673 iterate_devices_callout_fn fn, void *data) 674 { 675 struct dm_verity *v = ti->private; 676 677 return fn(ti, v->data_dev, v->data_start, ti->len, data); 678 } 679 680 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 681 { 682 struct dm_verity *v = ti->private; 683 684 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 685 limits->logical_block_size = 1 << v->data_dev_block_bits; 686 687 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 688 limits->physical_block_size = 1 << v->data_dev_block_bits; 689 690 blk_limits_io_min(limits, limits->logical_block_size); 691 } 692 693 static void verity_dtr(struct dm_target *ti) 694 { 695 struct dm_verity *v = ti->private; 696 697 if (v->verify_wq) 698 destroy_workqueue(v->verify_wq); 699 700 if (v->bufio) 701 dm_bufio_client_destroy(v->bufio); 702 703 kfree(v->salt); 704 kfree(v->root_digest); 705 kfree(v->zero_digest); 706 707 if (v->tfm) 708 crypto_free_shash(v->tfm); 709 710 kfree(v->alg_name); 711 712 if (v->hash_dev) 713 dm_put_device(ti, v->hash_dev); 714 715 if (v->data_dev) 716 dm_put_device(ti, v->data_dev); 717 718 verity_fec_dtr(v); 719 720 kfree(v); 721 } 722 723 static int verity_alloc_zero_digest(struct dm_verity *v) 724 { 725 int r = -ENOMEM; 726 struct shash_desc *desc; 727 u8 *zero_data; 728 729 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 730 731 if (!v->zero_digest) 732 return r; 733 734 desc = kmalloc(v->shash_descsize, GFP_KERNEL); 735 736 if (!desc) 737 return r; /* verity_dtr will free zero_digest */ 738 739 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 740 741 if (!zero_data) 742 goto out; 743 744 r = verity_hash(v, desc, zero_data, 1 << v->data_dev_block_bits, 745 v->zero_digest); 746 747 out: 748 kfree(desc); 749 kfree(zero_data); 750 751 return r; 752 } 753 754 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v) 755 { 756 int r; 757 unsigned argc; 758 struct dm_target *ti = v->ti; 759 const char *arg_name; 760 761 static struct dm_arg _args[] = { 762 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 763 }; 764 765 r = dm_read_arg_group(_args, as, &argc, &ti->error); 766 if (r) 767 return -EINVAL; 768 769 if (!argc) 770 return 0; 771 772 do { 773 arg_name = dm_shift_arg(as); 774 argc--; 775 776 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) { 777 v->mode = DM_VERITY_MODE_LOGGING; 778 continue; 779 780 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) { 781 v->mode = DM_VERITY_MODE_RESTART; 782 continue; 783 784 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 785 r = verity_alloc_zero_digest(v); 786 if (r) { 787 ti->error = "Cannot allocate zero digest"; 788 return r; 789 } 790 continue; 791 792 } else if (verity_is_fec_opt_arg(arg_name)) { 793 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 794 if (r) 795 return r; 796 continue; 797 } 798 799 ti->error = "Unrecognized verity feature request"; 800 return -EINVAL; 801 } while (argc && !r); 802 803 return r; 804 } 805 806 /* 807 * Target parameters: 808 * <version> The current format is version 1. 809 * Vsn 0 is compatible with original Chromium OS releases. 810 * <data device> 811 * <hash device> 812 * <data block size> 813 * <hash block size> 814 * <the number of data blocks> 815 * <hash start block> 816 * <algorithm> 817 * <digest> 818 * <salt> Hex string or "-" if no salt. 819 */ 820 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) 821 { 822 struct dm_verity *v; 823 struct dm_arg_set as; 824 unsigned int num; 825 unsigned long long num_ll; 826 int r; 827 int i; 828 sector_t hash_position; 829 char dummy; 830 831 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 832 if (!v) { 833 ti->error = "Cannot allocate verity structure"; 834 return -ENOMEM; 835 } 836 ti->private = v; 837 v->ti = ti; 838 839 r = verity_fec_ctr_alloc(v); 840 if (r) 841 goto bad; 842 843 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { 844 ti->error = "Device must be readonly"; 845 r = -EINVAL; 846 goto bad; 847 } 848 849 if (argc < 10) { 850 ti->error = "Not enough arguments"; 851 r = -EINVAL; 852 goto bad; 853 } 854 855 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 856 num > 1) { 857 ti->error = "Invalid version"; 858 r = -EINVAL; 859 goto bad; 860 } 861 v->version = num; 862 863 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); 864 if (r) { 865 ti->error = "Data device lookup failed"; 866 goto bad; 867 } 868 869 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); 870 if (r) { 871 ti->error = "Hash device lookup failed"; 872 goto bad; 873 } 874 875 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 876 !num || (num & (num - 1)) || 877 num < bdev_logical_block_size(v->data_dev->bdev) || 878 num > PAGE_SIZE) { 879 ti->error = "Invalid data device block size"; 880 r = -EINVAL; 881 goto bad; 882 } 883 v->data_dev_block_bits = __ffs(num); 884 885 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 886 !num || (num & (num - 1)) || 887 num < bdev_logical_block_size(v->hash_dev->bdev) || 888 num > INT_MAX) { 889 ti->error = "Invalid hash device block size"; 890 r = -EINVAL; 891 goto bad; 892 } 893 v->hash_dev_block_bits = __ffs(num); 894 895 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 896 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 897 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 898 ti->error = "Invalid data blocks"; 899 r = -EINVAL; 900 goto bad; 901 } 902 v->data_blocks = num_ll; 903 904 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 905 ti->error = "Data device is too small"; 906 r = -EINVAL; 907 goto bad; 908 } 909 910 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 911 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 912 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 913 ti->error = "Invalid hash start"; 914 r = -EINVAL; 915 goto bad; 916 } 917 v->hash_start = num_ll; 918 919 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 920 if (!v->alg_name) { 921 ti->error = "Cannot allocate algorithm name"; 922 r = -ENOMEM; 923 goto bad; 924 } 925 926 v->tfm = crypto_alloc_shash(v->alg_name, 0, 0); 927 if (IS_ERR(v->tfm)) { 928 ti->error = "Cannot initialize hash function"; 929 r = PTR_ERR(v->tfm); 930 v->tfm = NULL; 931 goto bad; 932 } 933 v->digest_size = crypto_shash_digestsize(v->tfm); 934 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 935 ti->error = "Digest size too big"; 936 r = -EINVAL; 937 goto bad; 938 } 939 v->shash_descsize = 940 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm); 941 942 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 943 if (!v->root_digest) { 944 ti->error = "Cannot allocate root digest"; 945 r = -ENOMEM; 946 goto bad; 947 } 948 if (strlen(argv[8]) != v->digest_size * 2 || 949 hex2bin(v->root_digest, argv[8], v->digest_size)) { 950 ti->error = "Invalid root digest"; 951 r = -EINVAL; 952 goto bad; 953 } 954 955 if (strcmp(argv[9], "-")) { 956 v->salt_size = strlen(argv[9]) / 2; 957 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 958 if (!v->salt) { 959 ti->error = "Cannot allocate salt"; 960 r = -ENOMEM; 961 goto bad; 962 } 963 if (strlen(argv[9]) != v->salt_size * 2 || 964 hex2bin(v->salt, argv[9], v->salt_size)) { 965 ti->error = "Invalid salt"; 966 r = -EINVAL; 967 goto bad; 968 } 969 } 970 971 argv += 10; 972 argc -= 10; 973 974 /* Optional parameters */ 975 if (argc) { 976 as.argc = argc; 977 as.argv = argv; 978 979 r = verity_parse_opt_args(&as, v); 980 if (r < 0) 981 goto bad; 982 } 983 984 v->hash_per_block_bits = 985 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 986 987 v->levels = 0; 988 if (v->data_blocks) 989 while (v->hash_per_block_bits * v->levels < 64 && 990 (unsigned long long)(v->data_blocks - 1) >> 991 (v->hash_per_block_bits * v->levels)) 992 v->levels++; 993 994 if (v->levels > DM_VERITY_MAX_LEVELS) { 995 ti->error = "Too many tree levels"; 996 r = -E2BIG; 997 goto bad; 998 } 999 1000 hash_position = v->hash_start; 1001 for (i = v->levels - 1; i >= 0; i--) { 1002 sector_t s; 1003 v->hash_level_block[i] = hash_position; 1004 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1005 >> ((i + 1) * v->hash_per_block_bits); 1006 if (hash_position + s < hash_position) { 1007 ti->error = "Hash device offset overflow"; 1008 r = -E2BIG; 1009 goto bad; 1010 } 1011 hash_position += s; 1012 } 1013 v->hash_blocks = hash_position; 1014 1015 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1016 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1017 dm_bufio_alloc_callback, NULL); 1018 if (IS_ERR(v->bufio)) { 1019 ti->error = "Cannot initialize dm-bufio"; 1020 r = PTR_ERR(v->bufio); 1021 v->bufio = NULL; 1022 goto bad; 1023 } 1024 1025 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1026 ti->error = "Hash device is too small"; 1027 r = -E2BIG; 1028 goto bad; 1029 } 1030 1031 /* WQ_UNBOUND greatly improves performance when running on ramdisk */ 1032 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); 1033 if (!v->verify_wq) { 1034 ti->error = "Cannot allocate workqueue"; 1035 r = -ENOMEM; 1036 goto bad; 1037 } 1038 1039 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1040 v->shash_descsize + v->digest_size * 2; 1041 1042 r = verity_fec_ctr(v); 1043 if (r) 1044 goto bad; 1045 1046 ti->per_io_data_size = roundup(ti->per_io_data_size, 1047 __alignof__(struct dm_verity_io)); 1048 1049 return 0; 1050 1051 bad: 1052 verity_dtr(ti); 1053 1054 return r; 1055 } 1056 1057 static struct target_type verity_target = { 1058 .name = "verity", 1059 .version = {1, 3, 0}, 1060 .module = THIS_MODULE, 1061 .ctr = verity_ctr, 1062 .dtr = verity_dtr, 1063 .map = verity_map, 1064 .status = verity_status, 1065 .prepare_ioctl = verity_prepare_ioctl, 1066 .iterate_devices = verity_iterate_devices, 1067 .io_hints = verity_io_hints, 1068 }; 1069 1070 static int __init dm_verity_init(void) 1071 { 1072 int r; 1073 1074 r = dm_register_target(&verity_target); 1075 if (r < 0) 1076 DMERR("register failed %d", r); 1077 1078 return r; 1079 } 1080 1081 static void __exit dm_verity_exit(void) 1082 { 1083 dm_unregister_target(&verity_target); 1084 } 1085 1086 module_init(dm_verity_init); 1087 module_exit(dm_verity_exit); 1088 1089 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1090 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1091 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1092 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1093 MODULE_LICENSE("GPL"); 1094