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