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_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 646 } 647 648 static void verity_tasklet(unsigned long data) 649 { 650 struct dm_verity_io *io = (struct dm_verity_io *)data; 651 int err; 652 653 io->in_tasklet = true; 654 err = verity_verify_io(io); 655 if (err == -EAGAIN || err == -ENOMEM) { 656 /* fallback to retrying with work-queue */ 657 INIT_WORK(&io->work, verity_work); 658 queue_work(io->v->verify_wq, &io->work); 659 return; 660 } 661 662 verity_finish_io(io, errno_to_blk_status(err)); 663 } 664 665 static void verity_end_io(struct bio *bio) 666 { 667 struct dm_verity_io *io = bio->bi_private; 668 669 if (bio->bi_status && 670 (!verity_fec_is_enabled(io->v) || 671 verity_is_system_shutting_down() || 672 (bio->bi_opf & REQ_RAHEAD))) { 673 verity_finish_io(io, bio->bi_status); 674 return; 675 } 676 677 if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) { 678 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io); 679 tasklet_schedule(&io->tasklet); 680 } else { 681 INIT_WORK(&io->work, verity_work); 682 queue_work(io->v->verify_wq, &io->work); 683 } 684 } 685 686 /* 687 * Prefetch buffers for the specified io. 688 * The root buffer is not prefetched, it is assumed that it will be cached 689 * all the time. 690 */ 691 static void verity_prefetch_io(struct work_struct *work) 692 { 693 struct dm_verity_prefetch_work *pw = 694 container_of(work, struct dm_verity_prefetch_work, work); 695 struct dm_verity *v = pw->v; 696 int i; 697 698 for (i = v->levels - 2; i >= 0; i--) { 699 sector_t hash_block_start; 700 sector_t hash_block_end; 701 702 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 703 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 704 705 if (!i) { 706 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 707 708 cluster >>= v->data_dev_block_bits; 709 if (unlikely(!cluster)) 710 goto no_prefetch_cluster; 711 712 if (unlikely(cluster & (cluster - 1))) 713 cluster = 1 << __fls(cluster); 714 715 hash_block_start &= ~(sector_t)(cluster - 1); 716 hash_block_end |= cluster - 1; 717 if (unlikely(hash_block_end >= v->hash_blocks)) 718 hash_block_end = v->hash_blocks - 1; 719 } 720 no_prefetch_cluster: 721 dm_bufio_prefetch(v->bufio, hash_block_start, 722 hash_block_end - hash_block_start + 1); 723 } 724 725 kfree(pw); 726 } 727 728 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 729 { 730 sector_t block = io->block; 731 unsigned int n_blocks = io->n_blocks; 732 struct dm_verity_prefetch_work *pw; 733 734 if (v->validated_blocks) { 735 while (n_blocks && test_bit(block, v->validated_blocks)) { 736 block++; 737 n_blocks--; 738 } 739 while (n_blocks && test_bit(block + n_blocks - 1, 740 v->validated_blocks)) 741 n_blocks--; 742 if (!n_blocks) 743 return; 744 } 745 746 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 747 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 748 749 if (!pw) 750 return; 751 752 INIT_WORK(&pw->work, verity_prefetch_io); 753 pw->v = v; 754 pw->block = block; 755 pw->n_blocks = n_blocks; 756 queue_work(v->verify_wq, &pw->work); 757 } 758 759 /* 760 * Bio map function. It allocates dm_verity_io structure and bio vector and 761 * fills them. Then it issues prefetches and the I/O. 762 */ 763 static int verity_map(struct dm_target *ti, struct bio *bio) 764 { 765 struct dm_verity *v = ti->private; 766 struct dm_verity_io *io; 767 768 bio_set_dev(bio, v->data_dev->bdev); 769 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 770 771 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 772 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 773 DMERR_LIMIT("unaligned io"); 774 return DM_MAPIO_KILL; 775 } 776 777 if (bio_end_sector(bio) >> 778 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 779 DMERR_LIMIT("io out of range"); 780 return DM_MAPIO_KILL; 781 } 782 783 if (bio_data_dir(bio) == WRITE) 784 return DM_MAPIO_KILL; 785 786 io = dm_per_bio_data(bio, ti->per_io_data_size); 787 io->v = v; 788 io->orig_bi_end_io = bio->bi_end_io; 789 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 790 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 791 792 bio->bi_end_io = verity_end_io; 793 bio->bi_private = io; 794 io->iter = bio->bi_iter; 795 796 verity_fec_init_io(io); 797 798 verity_submit_prefetch(v, io); 799 800 submit_bio_noacct(bio); 801 802 return DM_MAPIO_SUBMITTED; 803 } 804 805 /* 806 * Status: V (valid) or C (corruption found) 807 */ 808 static void verity_status(struct dm_target *ti, status_type_t type, 809 unsigned int status_flags, char *result, unsigned int maxlen) 810 { 811 struct dm_verity *v = ti->private; 812 unsigned int args = 0; 813 unsigned int sz = 0; 814 unsigned int x; 815 816 switch (type) { 817 case STATUSTYPE_INFO: 818 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 819 break; 820 case STATUSTYPE_TABLE: 821 DMEMIT("%u %s %s %u %u %llu %llu %s ", 822 v->version, 823 v->data_dev->name, 824 v->hash_dev->name, 825 1 << v->data_dev_block_bits, 826 1 << v->hash_dev_block_bits, 827 (unsigned long long)v->data_blocks, 828 (unsigned long long)v->hash_start, 829 v->alg_name 830 ); 831 for (x = 0; x < v->digest_size; x++) 832 DMEMIT("%02x", v->root_digest[x]); 833 DMEMIT(" "); 834 if (!v->salt_size) 835 DMEMIT("-"); 836 else 837 for (x = 0; x < v->salt_size; x++) 838 DMEMIT("%02x", v->salt[x]); 839 if (v->mode != DM_VERITY_MODE_EIO) 840 args++; 841 if (verity_fec_is_enabled(v)) 842 args += DM_VERITY_OPTS_FEC; 843 if (v->zero_digest) 844 args++; 845 if (v->validated_blocks) 846 args++; 847 if (v->use_tasklet) 848 args++; 849 if (v->signature_key_desc) 850 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 851 if (!args) 852 return; 853 DMEMIT(" %u", args); 854 if (v->mode != DM_VERITY_MODE_EIO) { 855 DMEMIT(" "); 856 switch (v->mode) { 857 case DM_VERITY_MODE_LOGGING: 858 DMEMIT(DM_VERITY_OPT_LOGGING); 859 break; 860 case DM_VERITY_MODE_RESTART: 861 DMEMIT(DM_VERITY_OPT_RESTART); 862 break; 863 case DM_VERITY_MODE_PANIC: 864 DMEMIT(DM_VERITY_OPT_PANIC); 865 break; 866 default: 867 BUG(); 868 } 869 } 870 if (v->zero_digest) 871 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 872 if (v->validated_blocks) 873 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 874 if (v->use_tasklet) 875 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 876 sz = verity_fec_status_table(v, sz, result, maxlen); 877 if (v->signature_key_desc) 878 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 879 " %s", v->signature_key_desc); 880 break; 881 882 case STATUSTYPE_IMA: 883 DMEMIT_TARGET_NAME_VERSION(ti->type); 884 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 885 DMEMIT(",verity_version=%u", v->version); 886 DMEMIT(",data_device_name=%s", v->data_dev->name); 887 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 888 DMEMIT(",verity_algorithm=%s", v->alg_name); 889 890 DMEMIT(",root_digest="); 891 for (x = 0; x < v->digest_size; x++) 892 DMEMIT("%02x", v->root_digest[x]); 893 894 DMEMIT(",salt="); 895 if (!v->salt_size) 896 DMEMIT("-"); 897 else 898 for (x = 0; x < v->salt_size; x++) 899 DMEMIT("%02x", v->salt[x]); 900 901 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 902 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 903 if (v->signature_key_desc) 904 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 905 906 if (v->mode != DM_VERITY_MODE_EIO) { 907 DMEMIT(",verity_mode="); 908 switch (v->mode) { 909 case DM_VERITY_MODE_LOGGING: 910 DMEMIT(DM_VERITY_OPT_LOGGING); 911 break; 912 case DM_VERITY_MODE_RESTART: 913 DMEMIT(DM_VERITY_OPT_RESTART); 914 break; 915 case DM_VERITY_MODE_PANIC: 916 DMEMIT(DM_VERITY_OPT_PANIC); 917 break; 918 default: 919 DMEMIT("invalid"); 920 } 921 } 922 DMEMIT(";"); 923 break; 924 } 925 } 926 927 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 928 { 929 struct dm_verity *v = ti->private; 930 931 *bdev = v->data_dev->bdev; 932 933 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 934 return 1; 935 return 0; 936 } 937 938 static int verity_iterate_devices(struct dm_target *ti, 939 iterate_devices_callout_fn fn, void *data) 940 { 941 struct dm_verity *v = ti->private; 942 943 return fn(ti, v->data_dev, v->data_start, ti->len, data); 944 } 945 946 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 947 { 948 struct dm_verity *v = ti->private; 949 950 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 951 limits->logical_block_size = 1 << v->data_dev_block_bits; 952 953 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 954 limits->physical_block_size = 1 << v->data_dev_block_bits; 955 956 blk_limits_io_min(limits, limits->logical_block_size); 957 } 958 959 static void verity_dtr(struct dm_target *ti) 960 { 961 struct dm_verity *v = ti->private; 962 963 if (v->verify_wq) 964 destroy_workqueue(v->verify_wq); 965 966 if (v->bufio) 967 dm_bufio_client_destroy(v->bufio); 968 969 kvfree(v->validated_blocks); 970 kfree(v->salt); 971 kfree(v->root_digest); 972 kfree(v->zero_digest); 973 974 if (v->tfm) 975 crypto_free_ahash(v->tfm); 976 977 kfree(v->alg_name); 978 979 if (v->hash_dev) 980 dm_put_device(ti, v->hash_dev); 981 982 if (v->data_dev) 983 dm_put_device(ti, v->data_dev); 984 985 verity_fec_dtr(v); 986 987 kfree(v->signature_key_desc); 988 989 if (v->use_tasklet) 990 static_branch_dec(&use_tasklet_enabled); 991 992 kfree(v); 993 994 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 995 } 996 997 static int verity_alloc_most_once(struct dm_verity *v) 998 { 999 struct dm_target *ti = v->ti; 1000 1001 /* the bitset can only handle INT_MAX blocks */ 1002 if (v->data_blocks > INT_MAX) { 1003 ti->error = "device too large to use check_at_most_once"; 1004 return -E2BIG; 1005 } 1006 1007 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 1008 sizeof(unsigned long), 1009 GFP_KERNEL); 1010 if (!v->validated_blocks) { 1011 ti->error = "failed to allocate bitset for check_at_most_once"; 1012 return -ENOMEM; 1013 } 1014 1015 return 0; 1016 } 1017 1018 static int verity_alloc_zero_digest(struct dm_verity *v) 1019 { 1020 int r = -ENOMEM; 1021 struct ahash_request *req; 1022 u8 *zero_data; 1023 1024 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1025 1026 if (!v->zero_digest) 1027 return r; 1028 1029 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 1030 1031 if (!req) 1032 return r; /* verity_dtr will free zero_digest */ 1033 1034 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1035 1036 if (!zero_data) 1037 goto out; 1038 1039 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 1040 v->zero_digest, true); 1041 1042 out: 1043 kfree(req); 1044 kfree(zero_data); 1045 1046 return r; 1047 } 1048 1049 static inline bool verity_is_verity_mode(const char *arg_name) 1050 { 1051 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1052 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1053 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1054 } 1055 1056 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1057 { 1058 if (v->mode) 1059 return -EINVAL; 1060 1061 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1062 v->mode = DM_VERITY_MODE_LOGGING; 1063 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1064 v->mode = DM_VERITY_MODE_RESTART; 1065 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1066 v->mode = DM_VERITY_MODE_PANIC; 1067 1068 return 0; 1069 } 1070 1071 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1072 struct dm_verity_sig_opts *verify_args, 1073 bool only_modifier_opts) 1074 { 1075 int r = 0; 1076 unsigned int argc; 1077 struct dm_target *ti = v->ti; 1078 const char *arg_name; 1079 1080 static const struct dm_arg _args[] = { 1081 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1082 }; 1083 1084 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1085 if (r) 1086 return -EINVAL; 1087 1088 if (!argc) 1089 return 0; 1090 1091 do { 1092 arg_name = dm_shift_arg(as); 1093 argc--; 1094 1095 if (verity_is_verity_mode(arg_name)) { 1096 if (only_modifier_opts) 1097 continue; 1098 r = verity_parse_verity_mode(v, arg_name); 1099 if (r) { 1100 ti->error = "Conflicting error handling parameters"; 1101 return r; 1102 } 1103 continue; 1104 1105 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1106 if (only_modifier_opts) 1107 continue; 1108 r = verity_alloc_zero_digest(v); 1109 if (r) { 1110 ti->error = "Cannot allocate zero digest"; 1111 return r; 1112 } 1113 continue; 1114 1115 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1116 if (only_modifier_opts) 1117 continue; 1118 r = verity_alloc_most_once(v); 1119 if (r) 1120 return r; 1121 continue; 1122 1123 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1124 v->use_tasklet = true; 1125 static_branch_inc(&use_tasklet_enabled); 1126 continue; 1127 1128 } else if (verity_is_fec_opt_arg(arg_name)) { 1129 if (only_modifier_opts) 1130 continue; 1131 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1132 if (r) 1133 return r; 1134 continue; 1135 1136 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1137 if (only_modifier_opts) 1138 continue; 1139 r = verity_verify_sig_parse_opt_args(as, v, 1140 verify_args, 1141 &argc, arg_name); 1142 if (r) 1143 return r; 1144 continue; 1145 1146 } else if (only_modifier_opts) { 1147 /* 1148 * Ignore unrecognized opt, could easily be an extra 1149 * argument to an option whose parsing was skipped. 1150 * Normal parsing (@only_modifier_opts=false) will 1151 * properly parse all options (and their extra args). 1152 */ 1153 continue; 1154 } 1155 1156 DMERR("Unrecognized verity feature request: %s", arg_name); 1157 ti->error = "Unrecognized verity feature request"; 1158 return -EINVAL; 1159 } while (argc && !r); 1160 1161 return r; 1162 } 1163 1164 /* 1165 * Target parameters: 1166 * <version> The current format is version 1. 1167 * Vsn 0 is compatible with original Chromium OS releases. 1168 * <data device> 1169 * <hash device> 1170 * <data block size> 1171 * <hash block size> 1172 * <the number of data blocks> 1173 * <hash start block> 1174 * <algorithm> 1175 * <digest> 1176 * <salt> Hex string or "-" if no salt. 1177 */ 1178 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1179 { 1180 struct dm_verity *v; 1181 struct dm_verity_sig_opts verify_args = {0}; 1182 struct dm_arg_set as; 1183 unsigned int num; 1184 unsigned long long num_ll; 1185 int r; 1186 int i; 1187 sector_t hash_position; 1188 char dummy; 1189 char *root_hash_digest_to_validate; 1190 1191 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1192 if (!v) { 1193 ti->error = "Cannot allocate verity structure"; 1194 return -ENOMEM; 1195 } 1196 ti->private = v; 1197 v->ti = ti; 1198 1199 r = verity_fec_ctr_alloc(v); 1200 if (r) 1201 goto bad; 1202 1203 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1204 ti->error = "Device must be readonly"; 1205 r = -EINVAL; 1206 goto bad; 1207 } 1208 1209 if (argc < 10) { 1210 ti->error = "Not enough arguments"; 1211 r = -EINVAL; 1212 goto bad; 1213 } 1214 1215 /* Parse optional parameters that modify primary args */ 1216 if (argc > 10) { 1217 as.argc = argc - 10; 1218 as.argv = argv + 10; 1219 r = verity_parse_opt_args(&as, v, &verify_args, true); 1220 if (r < 0) 1221 goto bad; 1222 } 1223 1224 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1225 num > 1) { 1226 ti->error = "Invalid version"; 1227 r = -EINVAL; 1228 goto bad; 1229 } 1230 v->version = num; 1231 1232 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1233 if (r) { 1234 ti->error = "Data device lookup failed"; 1235 goto bad; 1236 } 1237 1238 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1239 if (r) { 1240 ti->error = "Hash device lookup failed"; 1241 goto bad; 1242 } 1243 1244 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1245 !num || (num & (num - 1)) || 1246 num < bdev_logical_block_size(v->data_dev->bdev) || 1247 num > PAGE_SIZE) { 1248 ti->error = "Invalid data device block size"; 1249 r = -EINVAL; 1250 goto bad; 1251 } 1252 v->data_dev_block_bits = __ffs(num); 1253 1254 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1255 !num || (num & (num - 1)) || 1256 num < bdev_logical_block_size(v->hash_dev->bdev) || 1257 num > INT_MAX) { 1258 ti->error = "Invalid hash device block size"; 1259 r = -EINVAL; 1260 goto bad; 1261 } 1262 v->hash_dev_block_bits = __ffs(num); 1263 1264 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1265 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1266 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1267 ti->error = "Invalid data blocks"; 1268 r = -EINVAL; 1269 goto bad; 1270 } 1271 v->data_blocks = num_ll; 1272 1273 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1274 ti->error = "Data device is too small"; 1275 r = -EINVAL; 1276 goto bad; 1277 } 1278 1279 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1280 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1281 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1282 ti->error = "Invalid hash start"; 1283 r = -EINVAL; 1284 goto bad; 1285 } 1286 v->hash_start = num_ll; 1287 1288 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1289 if (!v->alg_name) { 1290 ti->error = "Cannot allocate algorithm name"; 1291 r = -ENOMEM; 1292 goto bad; 1293 } 1294 1295 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 1296 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0); 1297 if (IS_ERR(v->tfm)) { 1298 ti->error = "Cannot initialize hash function"; 1299 r = PTR_ERR(v->tfm); 1300 v->tfm = NULL; 1301 goto bad; 1302 } 1303 1304 /* 1305 * dm-verity performance can vary greatly depending on which hash 1306 * algorithm implementation is used. Help people debug performance 1307 * problems by logging the ->cra_driver_name. 1308 */ 1309 DMINFO("%s using implementation \"%s\"", v->alg_name, 1310 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1311 1312 v->digest_size = crypto_ahash_digestsize(v->tfm); 1313 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1314 ti->error = "Digest size too big"; 1315 r = -EINVAL; 1316 goto bad; 1317 } 1318 v->ahash_reqsize = sizeof(struct ahash_request) + 1319 crypto_ahash_reqsize(v->tfm); 1320 1321 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1322 if (!v->root_digest) { 1323 ti->error = "Cannot allocate root digest"; 1324 r = -ENOMEM; 1325 goto bad; 1326 } 1327 if (strlen(argv[8]) != v->digest_size * 2 || 1328 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1329 ti->error = "Invalid root digest"; 1330 r = -EINVAL; 1331 goto bad; 1332 } 1333 root_hash_digest_to_validate = argv[8]; 1334 1335 if (strcmp(argv[9], "-")) { 1336 v->salt_size = strlen(argv[9]) / 2; 1337 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1338 if (!v->salt) { 1339 ti->error = "Cannot allocate salt"; 1340 r = -ENOMEM; 1341 goto bad; 1342 } 1343 if (strlen(argv[9]) != v->salt_size * 2 || 1344 hex2bin(v->salt, argv[9], v->salt_size)) { 1345 ti->error = "Invalid salt"; 1346 r = -EINVAL; 1347 goto bad; 1348 } 1349 } 1350 1351 argv += 10; 1352 argc -= 10; 1353 1354 /* Optional parameters */ 1355 if (argc) { 1356 as.argc = argc; 1357 as.argv = argv; 1358 r = verity_parse_opt_args(&as, v, &verify_args, false); 1359 if (r < 0) 1360 goto bad; 1361 } 1362 1363 /* Root hash signature is a optional parameter*/ 1364 r = verity_verify_root_hash(root_hash_digest_to_validate, 1365 strlen(root_hash_digest_to_validate), 1366 verify_args.sig, 1367 verify_args.sig_size); 1368 if (r < 0) { 1369 ti->error = "Root hash verification failed"; 1370 goto bad; 1371 } 1372 v->hash_per_block_bits = 1373 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1374 1375 v->levels = 0; 1376 if (v->data_blocks) 1377 while (v->hash_per_block_bits * v->levels < 64 && 1378 (unsigned long long)(v->data_blocks - 1) >> 1379 (v->hash_per_block_bits * v->levels)) 1380 v->levels++; 1381 1382 if (v->levels > DM_VERITY_MAX_LEVELS) { 1383 ti->error = "Too many tree levels"; 1384 r = -E2BIG; 1385 goto bad; 1386 } 1387 1388 hash_position = v->hash_start; 1389 for (i = v->levels - 1; i >= 0; i--) { 1390 sector_t s; 1391 1392 v->hash_level_block[i] = hash_position; 1393 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1394 >> ((i + 1) * v->hash_per_block_bits); 1395 if (hash_position + s < hash_position) { 1396 ti->error = "Hash device offset overflow"; 1397 r = -E2BIG; 1398 goto bad; 1399 } 1400 hash_position += s; 1401 } 1402 v->hash_blocks = hash_position; 1403 1404 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1405 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1406 dm_bufio_alloc_callback, NULL, 1407 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1408 if (IS_ERR(v->bufio)) { 1409 ti->error = "Cannot initialize dm-bufio"; 1410 r = PTR_ERR(v->bufio); 1411 v->bufio = NULL; 1412 goto bad; 1413 } 1414 1415 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1416 ti->error = "Hash device is too small"; 1417 r = -E2BIG; 1418 goto bad; 1419 } 1420 1421 /* 1422 * Using WQ_HIGHPRI improves throughput and completion latency by 1423 * reducing wait times when reading from a dm-verity device. 1424 * 1425 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1426 * allows verify_wq to preempt softirq since verification in tasklet 1427 * will fall-back to using it for error handling (or if the bufio cache 1428 * doesn't have required hashes). 1429 */ 1430 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1431 if (!v->verify_wq) { 1432 ti->error = "Cannot allocate workqueue"; 1433 r = -ENOMEM; 1434 goto bad; 1435 } 1436 1437 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1438 v->ahash_reqsize + v->digest_size * 2; 1439 1440 r = verity_fec_ctr(v); 1441 if (r) 1442 goto bad; 1443 1444 ti->per_io_data_size = roundup(ti->per_io_data_size, 1445 __alignof__(struct dm_verity_io)); 1446 1447 verity_verify_sig_opts_cleanup(&verify_args); 1448 1449 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1450 1451 return 0; 1452 1453 bad: 1454 1455 verity_verify_sig_opts_cleanup(&verify_args); 1456 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1457 verity_dtr(ti); 1458 1459 return r; 1460 } 1461 1462 /* 1463 * Check whether a DM target is a verity target. 1464 */ 1465 bool dm_is_verity_target(struct dm_target *ti) 1466 { 1467 return ti->type->module == THIS_MODULE; 1468 } 1469 1470 /* 1471 * Get the verity mode (error behavior) of a verity target. 1472 * 1473 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1474 * target. 1475 */ 1476 int dm_verity_get_mode(struct dm_target *ti) 1477 { 1478 struct dm_verity *v = ti->private; 1479 1480 if (!dm_is_verity_target(ti)) 1481 return -EINVAL; 1482 1483 return v->mode; 1484 } 1485 1486 /* 1487 * Get the root digest of a verity target. 1488 * 1489 * Returns a copy of the root digest, the caller is responsible for 1490 * freeing the memory of the digest. 1491 */ 1492 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1493 { 1494 struct dm_verity *v = ti->private; 1495 1496 if (!dm_is_verity_target(ti)) 1497 return -EINVAL; 1498 1499 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1500 if (*root_digest == NULL) 1501 return -ENOMEM; 1502 1503 *digest_size = v->digest_size; 1504 1505 return 0; 1506 } 1507 1508 static struct target_type verity_target = { 1509 .name = "verity", 1510 .features = DM_TARGET_IMMUTABLE, 1511 .version = {1, 9, 0}, 1512 .module = THIS_MODULE, 1513 .ctr = verity_ctr, 1514 .dtr = verity_dtr, 1515 .map = verity_map, 1516 .status = verity_status, 1517 .prepare_ioctl = verity_prepare_ioctl, 1518 .iterate_devices = verity_iterate_devices, 1519 .io_hints = verity_io_hints, 1520 }; 1521 module_dm(verity); 1522 1523 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1524 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1525 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1526 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1527 MODULE_LICENSE("GPL"); 1528