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