1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2012 Red Hat, Inc. 4 * 5 * Author: Mikulas Patocka <mpatocka@redhat.com> 6 * 7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors 8 * 9 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set 10 * default prefetch value. Data are read in "prefetch_cluster" chunks from the 11 * hash device. Setting this greatly improves performance when data and hash 12 * are on the same disk on different partitions on devices with poor random 13 * access behavior. 14 */ 15 16 #include "dm-verity.h" 17 #include "dm-verity-fec.h" 18 #include "dm-verity-verify-sig.h" 19 #include "dm-audit.h" 20 #include <linux/module.h> 21 #include <linux/reboot.h> 22 #include <linux/scatterlist.h> 23 #include <linux/string.h> 24 #include <linux/jump_label.h> 25 26 #define DM_MSG_PREFIX "verity" 27 28 #define DM_VERITY_ENV_LENGTH 42 29 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 30 31 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 32 33 #define DM_VERITY_MAX_CORRUPTED_ERRS 100 34 35 #define DM_VERITY_OPT_LOGGING "ignore_corruption" 36 #define DM_VERITY_OPT_RESTART "restart_on_corruption" 37 #define DM_VERITY_OPT_PANIC "panic_on_corruption" 38 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 39 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 40 #define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet" 41 42 #define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \ 43 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 44 45 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 46 47 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644); 48 49 static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled); 50 51 struct dm_verity_prefetch_work { 52 struct work_struct work; 53 struct dm_verity *v; 54 sector_t block; 55 unsigned int n_blocks; 56 }; 57 58 /* 59 * Auxiliary structure appended to each dm-bufio buffer. If the value 60 * hash_verified is nonzero, hash of the block has been verified. 61 * 62 * The variable hash_verified is set to 0 when allocating the buffer, then 63 * it can be changed to 1 and it is never reset to 0 again. 64 * 65 * There is no lock around this value, a race condition can at worst cause 66 * that multiple processes verify the hash of the same buffer simultaneously 67 * and write 1 to hash_verified simultaneously. 68 * This condition is harmless, so we don't need locking. 69 */ 70 struct buffer_aux { 71 int hash_verified; 72 }; 73 74 /* 75 * Initialize struct buffer_aux for a freshly created buffer. 76 */ 77 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 78 { 79 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 80 81 aux->hash_verified = 0; 82 } 83 84 /* 85 * Translate input sector number to the sector number on the target device. 86 */ 87 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 88 { 89 return v->data_start + dm_target_offset(v->ti, bi_sector); 90 } 91 92 /* 93 * Return hash position of a specified block at a specified tree level 94 * (0 is the lowest level). 95 * The lowest "hash_per_block_bits"-bits of the result denote hash position 96 * inside a hash block. The remaining bits denote location of the hash block. 97 */ 98 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 99 int level) 100 { 101 return block >> (level * v->hash_per_block_bits); 102 } 103 104 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req, 105 const u8 *data, size_t len, 106 struct crypto_wait *wait) 107 { 108 struct scatterlist sg; 109 110 if (likely(!is_vmalloc_addr(data))) { 111 sg_init_one(&sg, data, len); 112 ahash_request_set_crypt(req, &sg, NULL, len); 113 return crypto_wait_req(crypto_ahash_update(req), wait); 114 } 115 116 do { 117 int r; 118 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 119 120 flush_kernel_vmap_range((void *)data, this_step); 121 sg_init_table(&sg, 1); 122 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 123 ahash_request_set_crypt(req, &sg, NULL, this_step); 124 r = crypto_wait_req(crypto_ahash_update(req), wait); 125 if (unlikely(r)) 126 return r; 127 data += this_step; 128 len -= this_step; 129 } while (len); 130 131 return 0; 132 } 133 134 /* 135 * Wrapper for crypto_ahash_init, which handles verity salting. 136 */ 137 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req, 138 struct crypto_wait *wait, bool may_sleep) 139 { 140 int r; 141 142 ahash_request_set_tfm(req, v->tfm); 143 ahash_request_set_callback(req, 144 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0, 145 crypto_req_done, (void *)wait); 146 crypto_init_wait(wait); 147 148 r = crypto_wait_req(crypto_ahash_init(req), wait); 149 150 if (unlikely(r < 0)) { 151 if (r != -ENOMEM) 152 DMERR("crypto_ahash_init failed: %d", r); 153 return r; 154 } 155 156 if (likely(v->salt_size && (v->version >= 1))) 157 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 158 159 return r; 160 } 161 162 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req, 163 u8 *digest, struct crypto_wait *wait) 164 { 165 int r; 166 167 if (unlikely(v->salt_size && (!v->version))) { 168 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 169 170 if (r < 0) { 171 DMERR("%s failed updating salt: %d", __func__, r); 172 goto out; 173 } 174 } 175 176 ahash_request_set_crypt(req, NULL, digest, 0); 177 r = crypto_wait_req(crypto_ahash_final(req), wait); 178 out: 179 return r; 180 } 181 182 int verity_hash(struct dm_verity *v, struct ahash_request *req, 183 const u8 *data, size_t len, u8 *digest, bool may_sleep) 184 { 185 int r; 186 struct crypto_wait wait; 187 188 r = verity_hash_init(v, req, &wait, may_sleep); 189 if (unlikely(r < 0)) 190 goto out; 191 192 r = verity_hash_update(v, req, data, len, &wait); 193 if (unlikely(r < 0)) 194 goto out; 195 196 r = verity_hash_final(v, req, digest, &wait); 197 198 out: 199 return r; 200 } 201 202 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 203 sector_t *hash_block, unsigned int *offset) 204 { 205 sector_t position = verity_position_at_level(v, block, level); 206 unsigned int idx; 207 208 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 209 210 if (!offset) 211 return; 212 213 idx = position & ((1 << v->hash_per_block_bits) - 1); 214 if (!v->version) 215 *offset = idx * v->digest_size; 216 else 217 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 218 } 219 220 /* 221 * Handle verification errors. 222 */ 223 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 224 unsigned long long block) 225 { 226 char verity_env[DM_VERITY_ENV_LENGTH]; 227 char *envp[] = { verity_env, NULL }; 228 const char *type_str = ""; 229 struct mapped_device *md = dm_table_get_md(v->ti->table); 230 231 /* Corruption should be visible in device status in all modes */ 232 v->hash_failed = true; 233 234 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 235 goto out; 236 237 v->corrupted_errs++; 238 239 switch (type) { 240 case DM_VERITY_BLOCK_TYPE_DATA: 241 type_str = "data"; 242 break; 243 case DM_VERITY_BLOCK_TYPE_METADATA: 244 type_str = "metadata"; 245 break; 246 default: 247 BUG(); 248 } 249 250 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 251 type_str, block); 252 253 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { 254 DMERR("%s: reached maximum errors", v->data_dev->name); 255 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); 256 } 257 258 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 259 DM_VERITY_ENV_VAR_NAME, type, block); 260 261 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 262 263 out: 264 if (v->mode == DM_VERITY_MODE_LOGGING) 265 return 0; 266 267 if (v->mode == DM_VERITY_MODE_RESTART) 268 kernel_restart("dm-verity device corrupted"); 269 270 if (v->mode == DM_VERITY_MODE_PANIC) 271 panic("dm-verity device corrupted"); 272 273 return 1; 274 } 275 276 /* 277 * Verify hash of a metadata block pertaining to the specified data block 278 * ("block" argument) at a specified level ("level" argument). 279 * 280 * On successful return, verity_io_want_digest(v, io) contains the hash value 281 * for a lower tree level or for the data block (if we're at the lowest level). 282 * 283 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 284 * If "skip_unverified" is false, unverified buffer is hashed and verified 285 * against current value of verity_io_want_digest(v, io). 286 */ 287 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 288 sector_t block, int level, bool skip_unverified, 289 u8 *want_digest) 290 { 291 struct dm_buffer *buf; 292 struct buffer_aux *aux; 293 u8 *data; 294 int r; 295 sector_t hash_block; 296 unsigned int offset; 297 298 verity_hash_at_level(v, block, level, &hash_block, &offset); 299 300 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) { 301 data = dm_bufio_get(v->bufio, hash_block, &buf); 302 if (data == NULL) { 303 /* 304 * In tasklet and the hash was not in the bufio cache. 305 * Return early and resume execution from a work-queue 306 * to read the hash from disk. 307 */ 308 return -EAGAIN; 309 } 310 } else 311 data = dm_bufio_read(v->bufio, hash_block, &buf); 312 313 if (IS_ERR(data)) 314 return PTR_ERR(data); 315 316 aux = dm_bufio_get_aux_data(buf); 317 318 if (!aux->hash_verified) { 319 if (skip_unverified) { 320 r = 1; 321 goto release_ret_r; 322 } 323 324 r = verity_hash(v, verity_io_hash_req(v, io), 325 data, 1 << v->hash_dev_block_bits, 326 verity_io_real_digest(v, io), !io->in_tasklet); 327 if (unlikely(r < 0)) 328 goto release_ret_r; 329 330 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 331 v->digest_size) == 0)) 332 aux->hash_verified = 1; 333 else if (static_branch_unlikely(&use_tasklet_enabled) && 334 io->in_tasklet) { 335 /* 336 * Error handling code (FEC included) cannot be run in a 337 * tasklet since it may sleep, so fallback to work-queue. 338 */ 339 r = -EAGAIN; 340 goto release_ret_r; 341 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 342 hash_block, data, NULL) == 0) 343 aux->hash_verified = 1; 344 else if (verity_handle_err(v, 345 DM_VERITY_BLOCK_TYPE_METADATA, 346 hash_block)) { 347 struct bio *bio = 348 dm_bio_from_per_bio_data(io, 349 v->ti->per_io_data_size); 350 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, 351 block, 0); 352 r = -EIO; 353 goto release_ret_r; 354 } 355 } 356 357 data += offset; 358 memcpy(want_digest, data, v->digest_size); 359 r = 0; 360 361 release_ret_r: 362 dm_bufio_release(buf); 363 return r; 364 } 365 366 /* 367 * Find a hash for a given block, write it to digest and verify the integrity 368 * of the hash tree if necessary. 369 */ 370 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 371 sector_t block, u8 *digest, bool *is_zero) 372 { 373 int r = 0, i; 374 375 if (likely(v->levels)) { 376 /* 377 * First, we try to get the requested hash for 378 * the current block. If the hash block itself is 379 * verified, zero is returned. If it isn't, this 380 * function returns 1 and we fall back to whole 381 * chain verification. 382 */ 383 r = verity_verify_level(v, io, block, 0, true, digest); 384 if (likely(r <= 0)) 385 goto out; 386 } 387 388 memcpy(digest, v->root_digest, v->digest_size); 389 390 for (i = v->levels - 1; i >= 0; i--) { 391 r = verity_verify_level(v, io, block, i, false, digest); 392 if (unlikely(r)) 393 goto out; 394 } 395 out: 396 if (!r && v->zero_digest) 397 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 398 else 399 *is_zero = false; 400 401 return r; 402 } 403 404 /* 405 * Calculates the digest for the given bio 406 */ 407 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, 408 struct bvec_iter *iter, struct crypto_wait *wait) 409 { 410 unsigned int todo = 1 << v->data_dev_block_bits; 411 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 412 struct scatterlist sg; 413 struct ahash_request *req = verity_io_hash_req(v, io); 414 415 do { 416 int r; 417 unsigned int len; 418 struct bio_vec bv = bio_iter_iovec(bio, *iter); 419 420 sg_init_table(&sg, 1); 421 422 len = bv.bv_len; 423 424 if (likely(len >= todo)) 425 len = todo; 426 /* 427 * Operating on a single page at a time looks suboptimal 428 * until you consider the typical block size is 4,096B. 429 * Going through this loops twice should be very rare. 430 */ 431 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset); 432 ahash_request_set_crypt(req, &sg, NULL, len); 433 r = crypto_wait_req(crypto_ahash_update(req), wait); 434 435 if (unlikely(r < 0)) { 436 DMERR("%s crypto op failed: %d", __func__, r); 437 return r; 438 } 439 440 bio_advance_iter(bio, iter, len); 441 todo -= len; 442 } while (todo); 443 444 return 0; 445 } 446 447 /* 448 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 449 * starting from iter. 450 */ 451 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 452 struct bvec_iter *iter, 453 int (*process)(struct dm_verity *v, 454 struct dm_verity_io *io, u8 *data, 455 size_t len)) 456 { 457 unsigned int todo = 1 << v->data_dev_block_bits; 458 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 459 460 do { 461 int r; 462 u8 *page; 463 unsigned int len; 464 struct bio_vec bv = bio_iter_iovec(bio, *iter); 465 466 page = bvec_kmap_local(&bv); 467 len = bv.bv_len; 468 469 if (likely(len >= todo)) 470 len = todo; 471 472 r = process(v, io, page, len); 473 kunmap_local(page); 474 475 if (r < 0) 476 return r; 477 478 bio_advance_iter(bio, iter, len); 479 todo -= len; 480 } while (todo); 481 482 return 0; 483 } 484 485 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 486 u8 *data, size_t len) 487 { 488 memset(data, 0, len); 489 return 0; 490 } 491 492 /* 493 * Moves the bio iter one data block forward. 494 */ 495 static inline void verity_bv_skip_block(struct dm_verity *v, 496 struct dm_verity_io *io, 497 struct bvec_iter *iter) 498 { 499 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 500 501 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits); 502 } 503 504 /* 505 * Verify one "dm_verity_io" structure. 506 */ 507 static int verity_verify_io(struct dm_verity_io *io) 508 { 509 bool is_zero; 510 struct dm_verity *v = io->v; 511 #if defined(CONFIG_DM_VERITY_FEC) 512 struct bvec_iter start; 513 #endif 514 struct bvec_iter iter_copy; 515 struct bvec_iter *iter; 516 struct crypto_wait wait; 517 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 518 unsigned int b; 519 520 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) { 521 /* 522 * Copy the iterator in case we need to restart 523 * verification in a work-queue. 524 */ 525 iter_copy = io->iter; 526 iter = &iter_copy; 527 } else 528 iter = &io->iter; 529 530 for (b = 0; b < io->n_blocks; b++) { 531 int r; 532 sector_t cur_block = io->block + b; 533 struct ahash_request *req = verity_io_hash_req(v, io); 534 535 if (v->validated_blocks && bio->bi_status == BLK_STS_OK && 536 likely(test_bit(cur_block, v->validated_blocks))) { 537 verity_bv_skip_block(v, io, iter); 538 continue; 539 } 540 541 r = verity_hash_for_block(v, io, cur_block, 542 verity_io_want_digest(v, io), 543 &is_zero); 544 if (unlikely(r < 0)) 545 return r; 546 547 if (is_zero) { 548 /* 549 * If we expect a zero block, don't validate, just 550 * return zeros. 551 */ 552 r = verity_for_bv_block(v, io, iter, 553 verity_bv_zero); 554 if (unlikely(r < 0)) 555 return r; 556 557 continue; 558 } 559 560 r = verity_hash_init(v, req, &wait, !io->in_tasklet); 561 if (unlikely(r < 0)) 562 return r; 563 564 #if defined(CONFIG_DM_VERITY_FEC) 565 if (verity_fec_is_enabled(v)) 566 start = *iter; 567 #endif 568 r = verity_for_io_block(v, io, iter, &wait); 569 if (unlikely(r < 0)) 570 return r; 571 572 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 573 &wait); 574 if (unlikely(r < 0)) 575 return r; 576 577 if (likely(memcmp(verity_io_real_digest(v, io), 578 verity_io_want_digest(v, io), v->digest_size) == 0)) { 579 if (v->validated_blocks) 580 set_bit(cur_block, v->validated_blocks); 581 continue; 582 } else if (static_branch_unlikely(&use_tasklet_enabled) && 583 io->in_tasklet) { 584 /* 585 * Error handling code (FEC included) cannot be run in a 586 * tasklet since it may sleep, so fallback to work-queue. 587 */ 588 return -EAGAIN; 589 #if defined(CONFIG_DM_VERITY_FEC) 590 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 591 cur_block, NULL, &start) == 0) { 592 continue; 593 #endif 594 } else { 595 if (bio->bi_status) { 596 /* 597 * Error correction failed; Just return error 598 */ 599 return -EIO; 600 } 601 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 602 cur_block)) { 603 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", 604 bio, cur_block, 0); 605 return -EIO; 606 } 607 } 608 } 609 610 return 0; 611 } 612 613 /* 614 * Skip verity work in response to I/O error when system is shutting down. 615 */ 616 static inline bool verity_is_system_shutting_down(void) 617 { 618 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 619 || system_state == SYSTEM_RESTART; 620 } 621 622 /* 623 * End one "io" structure with a given error. 624 */ 625 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 626 { 627 struct dm_verity *v = io->v; 628 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 629 630 bio->bi_end_io = io->orig_bi_end_io; 631 bio->bi_status = status; 632 633 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet) 634 verity_fec_finish_io(io); 635 636 bio_endio(bio); 637 } 638 639 static void verity_work(struct work_struct *w) 640 { 641 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 642 643 io->in_tasklet = false; 644 645 verity_fec_init_io(io); 646 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 647 } 648 649 static void verity_tasklet(unsigned long data) 650 { 651 struct dm_verity_io *io = (struct dm_verity_io *)data; 652 int err; 653 654 io->in_tasklet = true; 655 err = verity_verify_io(io); 656 if (err == -EAGAIN || err == -ENOMEM) { 657 /* fallback to retrying with work-queue */ 658 INIT_WORK(&io->work, verity_work); 659 queue_work(io->v->verify_wq, &io->work); 660 return; 661 } 662 663 verity_finish_io(io, errno_to_blk_status(err)); 664 } 665 666 static void verity_end_io(struct bio *bio) 667 { 668 struct dm_verity_io *io = bio->bi_private; 669 670 if (bio->bi_status && 671 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) { 672 verity_finish_io(io, bio->bi_status); 673 return; 674 } 675 676 if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) { 677 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io); 678 tasklet_schedule(&io->tasklet); 679 } else { 680 INIT_WORK(&io->work, verity_work); 681 queue_work(io->v->verify_wq, &io->work); 682 } 683 } 684 685 /* 686 * Prefetch buffers for the specified io. 687 * The root buffer is not prefetched, it is assumed that it will be cached 688 * all the time. 689 */ 690 static void verity_prefetch_io(struct work_struct *work) 691 { 692 struct dm_verity_prefetch_work *pw = 693 container_of(work, struct dm_verity_prefetch_work, work); 694 struct dm_verity *v = pw->v; 695 int i; 696 697 for (i = v->levels - 2; i >= 0; i--) { 698 sector_t hash_block_start; 699 sector_t hash_block_end; 700 701 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 702 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 703 704 if (!i) { 705 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 706 707 cluster >>= v->data_dev_block_bits; 708 if (unlikely(!cluster)) 709 goto no_prefetch_cluster; 710 711 if (unlikely(cluster & (cluster - 1))) 712 cluster = 1 << __fls(cluster); 713 714 hash_block_start &= ~(sector_t)(cluster - 1); 715 hash_block_end |= cluster - 1; 716 if (unlikely(hash_block_end >= v->hash_blocks)) 717 hash_block_end = v->hash_blocks - 1; 718 } 719 no_prefetch_cluster: 720 dm_bufio_prefetch(v->bufio, hash_block_start, 721 hash_block_end - hash_block_start + 1); 722 } 723 724 kfree(pw); 725 } 726 727 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 728 { 729 sector_t block = io->block; 730 unsigned int n_blocks = io->n_blocks; 731 struct dm_verity_prefetch_work *pw; 732 733 if (v->validated_blocks) { 734 while (n_blocks && test_bit(block, v->validated_blocks)) { 735 block++; 736 n_blocks--; 737 } 738 while (n_blocks && test_bit(block + n_blocks - 1, 739 v->validated_blocks)) 740 n_blocks--; 741 if (!n_blocks) 742 return; 743 } 744 745 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 746 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 747 748 if (!pw) 749 return; 750 751 INIT_WORK(&pw->work, verity_prefetch_io); 752 pw->v = v; 753 pw->block = block; 754 pw->n_blocks = n_blocks; 755 queue_work(v->verify_wq, &pw->work); 756 } 757 758 /* 759 * Bio map function. It allocates dm_verity_io structure and bio vector and 760 * fills them. Then it issues prefetches and the I/O. 761 */ 762 static int verity_map(struct dm_target *ti, struct bio *bio) 763 { 764 struct dm_verity *v = ti->private; 765 struct dm_verity_io *io; 766 767 bio_set_dev(bio, v->data_dev->bdev); 768 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 769 770 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 771 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 772 DMERR_LIMIT("unaligned io"); 773 return DM_MAPIO_KILL; 774 } 775 776 if (bio_end_sector(bio) >> 777 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 778 DMERR_LIMIT("io out of range"); 779 return DM_MAPIO_KILL; 780 } 781 782 if (bio_data_dir(bio) == WRITE) 783 return DM_MAPIO_KILL; 784 785 io = dm_per_bio_data(bio, ti->per_io_data_size); 786 io->v = v; 787 io->orig_bi_end_io = bio->bi_end_io; 788 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 789 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 790 791 bio->bi_end_io = verity_end_io; 792 bio->bi_private = io; 793 io->iter = bio->bi_iter; 794 795 verity_submit_prefetch(v, io); 796 797 submit_bio_noacct(bio); 798 799 return DM_MAPIO_SUBMITTED; 800 } 801 802 /* 803 * Status: V (valid) or C (corruption found) 804 */ 805 static void verity_status(struct dm_target *ti, status_type_t type, 806 unsigned int status_flags, char *result, unsigned int maxlen) 807 { 808 struct dm_verity *v = ti->private; 809 unsigned int args = 0; 810 unsigned int sz = 0; 811 unsigned int x; 812 813 switch (type) { 814 case STATUSTYPE_INFO: 815 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 816 break; 817 case STATUSTYPE_TABLE: 818 DMEMIT("%u %s %s %u %u %llu %llu %s ", 819 v->version, 820 v->data_dev->name, 821 v->hash_dev->name, 822 1 << v->data_dev_block_bits, 823 1 << v->hash_dev_block_bits, 824 (unsigned long long)v->data_blocks, 825 (unsigned long long)v->hash_start, 826 v->alg_name 827 ); 828 for (x = 0; x < v->digest_size; x++) 829 DMEMIT("%02x", v->root_digest[x]); 830 DMEMIT(" "); 831 if (!v->salt_size) 832 DMEMIT("-"); 833 else 834 for (x = 0; x < v->salt_size; x++) 835 DMEMIT("%02x", v->salt[x]); 836 if (v->mode != DM_VERITY_MODE_EIO) 837 args++; 838 if (verity_fec_is_enabled(v)) 839 args += DM_VERITY_OPTS_FEC; 840 if (v->zero_digest) 841 args++; 842 if (v->validated_blocks) 843 args++; 844 if (v->use_tasklet) 845 args++; 846 if (v->signature_key_desc) 847 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 848 if (!args) 849 return; 850 DMEMIT(" %u", args); 851 if (v->mode != DM_VERITY_MODE_EIO) { 852 DMEMIT(" "); 853 switch (v->mode) { 854 case DM_VERITY_MODE_LOGGING: 855 DMEMIT(DM_VERITY_OPT_LOGGING); 856 break; 857 case DM_VERITY_MODE_RESTART: 858 DMEMIT(DM_VERITY_OPT_RESTART); 859 break; 860 case DM_VERITY_MODE_PANIC: 861 DMEMIT(DM_VERITY_OPT_PANIC); 862 break; 863 default: 864 BUG(); 865 } 866 } 867 if (v->zero_digest) 868 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 869 if (v->validated_blocks) 870 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 871 if (v->use_tasklet) 872 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 873 sz = verity_fec_status_table(v, sz, result, maxlen); 874 if (v->signature_key_desc) 875 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 876 " %s", v->signature_key_desc); 877 break; 878 879 case STATUSTYPE_IMA: 880 DMEMIT_TARGET_NAME_VERSION(ti->type); 881 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 882 DMEMIT(",verity_version=%u", v->version); 883 DMEMIT(",data_device_name=%s", v->data_dev->name); 884 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 885 DMEMIT(",verity_algorithm=%s", v->alg_name); 886 887 DMEMIT(",root_digest="); 888 for (x = 0; x < v->digest_size; x++) 889 DMEMIT("%02x", v->root_digest[x]); 890 891 DMEMIT(",salt="); 892 if (!v->salt_size) 893 DMEMIT("-"); 894 else 895 for (x = 0; x < v->salt_size; x++) 896 DMEMIT("%02x", v->salt[x]); 897 898 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 899 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 900 if (v->signature_key_desc) 901 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 902 903 if (v->mode != DM_VERITY_MODE_EIO) { 904 DMEMIT(",verity_mode="); 905 switch (v->mode) { 906 case DM_VERITY_MODE_LOGGING: 907 DMEMIT(DM_VERITY_OPT_LOGGING); 908 break; 909 case DM_VERITY_MODE_RESTART: 910 DMEMIT(DM_VERITY_OPT_RESTART); 911 break; 912 case DM_VERITY_MODE_PANIC: 913 DMEMIT(DM_VERITY_OPT_PANIC); 914 break; 915 default: 916 DMEMIT("invalid"); 917 } 918 } 919 DMEMIT(";"); 920 break; 921 } 922 } 923 924 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 925 { 926 struct dm_verity *v = ti->private; 927 928 *bdev = v->data_dev->bdev; 929 930 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 931 return 1; 932 return 0; 933 } 934 935 static int verity_iterate_devices(struct dm_target *ti, 936 iterate_devices_callout_fn fn, void *data) 937 { 938 struct dm_verity *v = ti->private; 939 940 return fn(ti, v->data_dev, v->data_start, ti->len, data); 941 } 942 943 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 944 { 945 struct dm_verity *v = ti->private; 946 947 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 948 limits->logical_block_size = 1 << v->data_dev_block_bits; 949 950 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 951 limits->physical_block_size = 1 << v->data_dev_block_bits; 952 953 blk_limits_io_min(limits, limits->logical_block_size); 954 } 955 956 static void verity_dtr(struct dm_target *ti) 957 { 958 struct dm_verity *v = ti->private; 959 960 if (v->verify_wq) 961 destroy_workqueue(v->verify_wq); 962 963 if (v->bufio) 964 dm_bufio_client_destroy(v->bufio); 965 966 kvfree(v->validated_blocks); 967 kfree(v->salt); 968 kfree(v->root_digest); 969 kfree(v->zero_digest); 970 971 if (v->tfm) 972 crypto_free_ahash(v->tfm); 973 974 kfree(v->alg_name); 975 976 if (v->hash_dev) 977 dm_put_device(ti, v->hash_dev); 978 979 if (v->data_dev) 980 dm_put_device(ti, v->data_dev); 981 982 verity_fec_dtr(v); 983 984 kfree(v->signature_key_desc); 985 986 if (v->use_tasklet) 987 static_branch_dec(&use_tasklet_enabled); 988 989 kfree(v); 990 991 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 992 } 993 994 static int verity_alloc_most_once(struct dm_verity *v) 995 { 996 struct dm_target *ti = v->ti; 997 998 /* the bitset can only handle INT_MAX blocks */ 999 if (v->data_blocks > INT_MAX) { 1000 ti->error = "device too large to use check_at_most_once"; 1001 return -E2BIG; 1002 } 1003 1004 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 1005 sizeof(unsigned long), 1006 GFP_KERNEL); 1007 if (!v->validated_blocks) { 1008 ti->error = "failed to allocate bitset for check_at_most_once"; 1009 return -ENOMEM; 1010 } 1011 1012 return 0; 1013 } 1014 1015 static int verity_alloc_zero_digest(struct dm_verity *v) 1016 { 1017 int r = -ENOMEM; 1018 struct ahash_request *req; 1019 u8 *zero_data; 1020 1021 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1022 1023 if (!v->zero_digest) 1024 return r; 1025 1026 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 1027 1028 if (!req) 1029 return r; /* verity_dtr will free zero_digest */ 1030 1031 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1032 1033 if (!zero_data) 1034 goto out; 1035 1036 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 1037 v->zero_digest, true); 1038 1039 out: 1040 kfree(req); 1041 kfree(zero_data); 1042 1043 return r; 1044 } 1045 1046 static inline bool verity_is_verity_mode(const char *arg_name) 1047 { 1048 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1049 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1050 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1051 } 1052 1053 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1054 { 1055 if (v->mode) 1056 return -EINVAL; 1057 1058 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1059 v->mode = DM_VERITY_MODE_LOGGING; 1060 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1061 v->mode = DM_VERITY_MODE_RESTART; 1062 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1063 v->mode = DM_VERITY_MODE_PANIC; 1064 1065 return 0; 1066 } 1067 1068 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1069 struct dm_verity_sig_opts *verify_args, 1070 bool only_modifier_opts) 1071 { 1072 int r = 0; 1073 unsigned int argc; 1074 struct dm_target *ti = v->ti; 1075 const char *arg_name; 1076 1077 static const struct dm_arg _args[] = { 1078 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1079 }; 1080 1081 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1082 if (r) 1083 return -EINVAL; 1084 1085 if (!argc) 1086 return 0; 1087 1088 do { 1089 arg_name = dm_shift_arg(as); 1090 argc--; 1091 1092 if (verity_is_verity_mode(arg_name)) { 1093 if (only_modifier_opts) 1094 continue; 1095 r = verity_parse_verity_mode(v, arg_name); 1096 if (r) { 1097 ti->error = "Conflicting error handling parameters"; 1098 return r; 1099 } 1100 continue; 1101 1102 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1103 if (only_modifier_opts) 1104 continue; 1105 r = verity_alloc_zero_digest(v); 1106 if (r) { 1107 ti->error = "Cannot allocate zero digest"; 1108 return r; 1109 } 1110 continue; 1111 1112 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1113 if (only_modifier_opts) 1114 continue; 1115 r = verity_alloc_most_once(v); 1116 if (r) 1117 return r; 1118 continue; 1119 1120 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1121 v->use_tasklet = true; 1122 static_branch_inc(&use_tasklet_enabled); 1123 continue; 1124 1125 } else if (verity_is_fec_opt_arg(arg_name)) { 1126 if (only_modifier_opts) 1127 continue; 1128 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1129 if (r) 1130 return r; 1131 continue; 1132 1133 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1134 if (only_modifier_opts) 1135 continue; 1136 r = verity_verify_sig_parse_opt_args(as, v, 1137 verify_args, 1138 &argc, arg_name); 1139 if (r) 1140 return r; 1141 continue; 1142 1143 } else if (only_modifier_opts) { 1144 /* 1145 * Ignore unrecognized opt, could easily be an extra 1146 * argument to an option whose parsing was skipped. 1147 * Normal parsing (@only_modifier_opts=false) will 1148 * properly parse all options (and their extra args). 1149 */ 1150 continue; 1151 } 1152 1153 DMERR("Unrecognized verity feature request: %s", arg_name); 1154 ti->error = "Unrecognized verity feature request"; 1155 return -EINVAL; 1156 } while (argc && !r); 1157 1158 return r; 1159 } 1160 1161 /* 1162 * Target parameters: 1163 * <version> The current format is version 1. 1164 * Vsn 0 is compatible with original Chromium OS releases. 1165 * <data device> 1166 * <hash device> 1167 * <data block size> 1168 * <hash block size> 1169 * <the number of data blocks> 1170 * <hash start block> 1171 * <algorithm> 1172 * <digest> 1173 * <salt> Hex string or "-" if no salt. 1174 */ 1175 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1176 { 1177 struct dm_verity *v; 1178 struct dm_verity_sig_opts verify_args = {0}; 1179 struct dm_arg_set as; 1180 unsigned int num; 1181 unsigned long long num_ll; 1182 int r; 1183 int i; 1184 sector_t hash_position; 1185 char dummy; 1186 char *root_hash_digest_to_validate; 1187 1188 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1189 if (!v) { 1190 ti->error = "Cannot allocate verity structure"; 1191 return -ENOMEM; 1192 } 1193 ti->private = v; 1194 v->ti = ti; 1195 1196 r = verity_fec_ctr_alloc(v); 1197 if (r) 1198 goto bad; 1199 1200 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1201 ti->error = "Device must be readonly"; 1202 r = -EINVAL; 1203 goto bad; 1204 } 1205 1206 if (argc < 10) { 1207 ti->error = "Not enough arguments"; 1208 r = -EINVAL; 1209 goto bad; 1210 } 1211 1212 /* Parse optional parameters that modify primary args */ 1213 if (argc > 10) { 1214 as.argc = argc - 10; 1215 as.argv = argv + 10; 1216 r = verity_parse_opt_args(&as, v, &verify_args, true); 1217 if (r < 0) 1218 goto bad; 1219 } 1220 1221 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1222 num > 1) { 1223 ti->error = "Invalid version"; 1224 r = -EINVAL; 1225 goto bad; 1226 } 1227 v->version = num; 1228 1229 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1230 if (r) { 1231 ti->error = "Data device lookup failed"; 1232 goto bad; 1233 } 1234 1235 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1236 if (r) { 1237 ti->error = "Hash device lookup failed"; 1238 goto bad; 1239 } 1240 1241 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1242 !num || (num & (num - 1)) || 1243 num < bdev_logical_block_size(v->data_dev->bdev) || 1244 num > PAGE_SIZE) { 1245 ti->error = "Invalid data device block size"; 1246 r = -EINVAL; 1247 goto bad; 1248 } 1249 v->data_dev_block_bits = __ffs(num); 1250 1251 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1252 !num || (num & (num - 1)) || 1253 num < bdev_logical_block_size(v->hash_dev->bdev) || 1254 num > INT_MAX) { 1255 ti->error = "Invalid hash device block size"; 1256 r = -EINVAL; 1257 goto bad; 1258 } 1259 v->hash_dev_block_bits = __ffs(num); 1260 1261 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1262 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1263 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1264 ti->error = "Invalid data blocks"; 1265 r = -EINVAL; 1266 goto bad; 1267 } 1268 v->data_blocks = num_ll; 1269 1270 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1271 ti->error = "Data device is too small"; 1272 r = -EINVAL; 1273 goto bad; 1274 } 1275 1276 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1277 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1278 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1279 ti->error = "Invalid hash start"; 1280 r = -EINVAL; 1281 goto bad; 1282 } 1283 v->hash_start = num_ll; 1284 1285 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1286 if (!v->alg_name) { 1287 ti->error = "Cannot allocate algorithm name"; 1288 r = -ENOMEM; 1289 goto bad; 1290 } 1291 1292 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 1293 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0); 1294 if (IS_ERR(v->tfm)) { 1295 ti->error = "Cannot initialize hash function"; 1296 r = PTR_ERR(v->tfm); 1297 v->tfm = NULL; 1298 goto bad; 1299 } 1300 1301 /* 1302 * dm-verity performance can vary greatly depending on which hash 1303 * algorithm implementation is used. Help people debug performance 1304 * problems by logging the ->cra_driver_name. 1305 */ 1306 DMINFO("%s using implementation \"%s\"", v->alg_name, 1307 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1308 1309 v->digest_size = crypto_ahash_digestsize(v->tfm); 1310 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1311 ti->error = "Digest size too big"; 1312 r = -EINVAL; 1313 goto bad; 1314 } 1315 v->ahash_reqsize = sizeof(struct ahash_request) + 1316 crypto_ahash_reqsize(v->tfm); 1317 1318 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1319 if (!v->root_digest) { 1320 ti->error = "Cannot allocate root digest"; 1321 r = -ENOMEM; 1322 goto bad; 1323 } 1324 if (strlen(argv[8]) != v->digest_size * 2 || 1325 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1326 ti->error = "Invalid root digest"; 1327 r = -EINVAL; 1328 goto bad; 1329 } 1330 root_hash_digest_to_validate = argv[8]; 1331 1332 if (strcmp(argv[9], "-")) { 1333 v->salt_size = strlen(argv[9]) / 2; 1334 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1335 if (!v->salt) { 1336 ti->error = "Cannot allocate salt"; 1337 r = -ENOMEM; 1338 goto bad; 1339 } 1340 if (strlen(argv[9]) != v->salt_size * 2 || 1341 hex2bin(v->salt, argv[9], v->salt_size)) { 1342 ti->error = "Invalid salt"; 1343 r = -EINVAL; 1344 goto bad; 1345 } 1346 } 1347 1348 argv += 10; 1349 argc -= 10; 1350 1351 /* Optional parameters */ 1352 if (argc) { 1353 as.argc = argc; 1354 as.argv = argv; 1355 r = verity_parse_opt_args(&as, v, &verify_args, false); 1356 if (r < 0) 1357 goto bad; 1358 } 1359 1360 /* Root hash signature is a optional parameter*/ 1361 r = verity_verify_root_hash(root_hash_digest_to_validate, 1362 strlen(root_hash_digest_to_validate), 1363 verify_args.sig, 1364 verify_args.sig_size); 1365 if (r < 0) { 1366 ti->error = "Root hash verification failed"; 1367 goto bad; 1368 } 1369 v->hash_per_block_bits = 1370 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1371 1372 v->levels = 0; 1373 if (v->data_blocks) 1374 while (v->hash_per_block_bits * v->levels < 64 && 1375 (unsigned long long)(v->data_blocks - 1) >> 1376 (v->hash_per_block_bits * v->levels)) 1377 v->levels++; 1378 1379 if (v->levels > DM_VERITY_MAX_LEVELS) { 1380 ti->error = "Too many tree levels"; 1381 r = -E2BIG; 1382 goto bad; 1383 } 1384 1385 hash_position = v->hash_start; 1386 for (i = v->levels - 1; i >= 0; i--) { 1387 sector_t s; 1388 1389 v->hash_level_block[i] = hash_position; 1390 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1391 >> ((i + 1) * v->hash_per_block_bits); 1392 if (hash_position + s < hash_position) { 1393 ti->error = "Hash device offset overflow"; 1394 r = -E2BIG; 1395 goto bad; 1396 } 1397 hash_position += s; 1398 } 1399 v->hash_blocks = hash_position; 1400 1401 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1402 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1403 dm_bufio_alloc_callback, NULL, 1404 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1405 if (IS_ERR(v->bufio)) { 1406 ti->error = "Cannot initialize dm-bufio"; 1407 r = PTR_ERR(v->bufio); 1408 v->bufio = NULL; 1409 goto bad; 1410 } 1411 1412 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1413 ti->error = "Hash device is too small"; 1414 r = -E2BIG; 1415 goto bad; 1416 } 1417 1418 /* 1419 * Using WQ_HIGHPRI improves throughput and completion latency by 1420 * reducing wait times when reading from a dm-verity device. 1421 * 1422 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1423 * allows verify_wq to preempt softirq since verification in tasklet 1424 * will fall-back to using it for error handling (or if the bufio cache 1425 * doesn't have required hashes). 1426 */ 1427 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1428 if (!v->verify_wq) { 1429 ti->error = "Cannot allocate workqueue"; 1430 r = -ENOMEM; 1431 goto bad; 1432 } 1433 1434 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1435 v->ahash_reqsize + v->digest_size * 2; 1436 1437 r = verity_fec_ctr(v); 1438 if (r) 1439 goto bad; 1440 1441 ti->per_io_data_size = roundup(ti->per_io_data_size, 1442 __alignof__(struct dm_verity_io)); 1443 1444 verity_verify_sig_opts_cleanup(&verify_args); 1445 1446 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1447 1448 return 0; 1449 1450 bad: 1451 1452 verity_verify_sig_opts_cleanup(&verify_args); 1453 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1454 verity_dtr(ti); 1455 1456 return r; 1457 } 1458 1459 /* 1460 * Check whether a DM target is a verity target. 1461 */ 1462 bool dm_is_verity_target(struct dm_target *ti) 1463 { 1464 return ti->type->module == THIS_MODULE; 1465 } 1466 1467 /* 1468 * Get the verity mode (error behavior) of a verity target. 1469 * 1470 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1471 * target. 1472 */ 1473 int dm_verity_get_mode(struct dm_target *ti) 1474 { 1475 struct dm_verity *v = ti->private; 1476 1477 if (!dm_is_verity_target(ti)) 1478 return -EINVAL; 1479 1480 return v->mode; 1481 } 1482 1483 /* 1484 * Get the root digest of a verity target. 1485 * 1486 * Returns a copy of the root digest, the caller is responsible for 1487 * freeing the memory of the digest. 1488 */ 1489 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1490 { 1491 struct dm_verity *v = ti->private; 1492 1493 if (!dm_is_verity_target(ti)) 1494 return -EINVAL; 1495 1496 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1497 if (*root_digest == NULL) 1498 return -ENOMEM; 1499 1500 *digest_size = v->digest_size; 1501 1502 return 0; 1503 } 1504 1505 static struct target_type verity_target = { 1506 .name = "verity", 1507 .features = DM_TARGET_IMMUTABLE, 1508 .version = {1, 9, 0}, 1509 .module = THIS_MODULE, 1510 .ctr = verity_ctr, 1511 .dtr = verity_dtr, 1512 .map = verity_map, 1513 .status = verity_status, 1514 .prepare_ioctl = verity_prepare_ioctl, 1515 .iterate_devices = verity_iterate_devices, 1516 .io_hints = verity_io_hints, 1517 }; 1518 module_dm(verity); 1519 1520 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1521 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1522 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1523 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1524 MODULE_LICENSE("GPL"); 1525