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 (3 + DM_VERITY_OPTS_FEC + \ 42 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 43 44 static unsigned 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 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 *offset) 200 { 201 sector_t position = verity_position_at_level(v, block, level); 202 unsigned 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 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 } 336 else if (verity_fec_decode(v, io, 337 DM_VERITY_BLOCK_TYPE_METADATA, 338 hash_block, data, NULL) == 0) 339 aux->hash_verified = 1; 340 else if (verity_handle_err(v, 341 DM_VERITY_BLOCK_TYPE_METADATA, 342 hash_block)) { 343 r = -EIO; 344 goto release_ret_r; 345 } 346 } 347 348 data += offset; 349 memcpy(want_digest, data, v->digest_size); 350 r = 0; 351 352 release_ret_r: 353 dm_bufio_release(buf); 354 return r; 355 } 356 357 /* 358 * Find a hash for a given block, write it to digest and verify the integrity 359 * of the hash tree if necessary. 360 */ 361 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 362 sector_t block, u8 *digest, bool *is_zero) 363 { 364 int r = 0, i; 365 366 if (likely(v->levels)) { 367 /* 368 * First, we try to get the requested hash for 369 * the current block. If the hash block itself is 370 * verified, zero is returned. If it isn't, this 371 * function returns 1 and we fall back to whole 372 * chain verification. 373 */ 374 r = verity_verify_level(v, io, block, 0, true, digest); 375 if (likely(r <= 0)) 376 goto out; 377 } 378 379 memcpy(digest, v->root_digest, v->digest_size); 380 381 for (i = v->levels - 1; i >= 0; i--) { 382 r = verity_verify_level(v, io, block, i, false, digest); 383 if (unlikely(r)) 384 goto out; 385 } 386 out: 387 if (!r && v->zero_digest) 388 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 389 else 390 *is_zero = false; 391 392 return r; 393 } 394 395 /* 396 * Calculates the digest for the given bio 397 */ 398 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, 399 struct bvec_iter *iter, struct crypto_wait *wait) 400 { 401 unsigned int todo = 1 << v->data_dev_block_bits; 402 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 403 struct scatterlist sg; 404 struct ahash_request *req = verity_io_hash_req(v, io); 405 406 do { 407 int r; 408 unsigned int len; 409 struct bio_vec bv = bio_iter_iovec(bio, *iter); 410 411 sg_init_table(&sg, 1); 412 413 len = bv.bv_len; 414 415 if (likely(len >= todo)) 416 len = todo; 417 /* 418 * Operating on a single page at a time looks suboptimal 419 * until you consider the typical block size is 4,096B. 420 * Going through this loops twice should be very rare. 421 */ 422 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset); 423 ahash_request_set_crypt(req, &sg, NULL, len); 424 r = crypto_wait_req(crypto_ahash_update(req), wait); 425 426 if (unlikely(r < 0)) { 427 DMERR("verity_for_io_block crypto op failed: %d", r); 428 return r; 429 } 430 431 bio_advance_iter(bio, iter, len); 432 todo -= len; 433 } while (todo); 434 435 return 0; 436 } 437 438 /* 439 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 440 * starting from iter. 441 */ 442 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 443 struct bvec_iter *iter, 444 int (*process)(struct dm_verity *v, 445 struct dm_verity_io *io, u8 *data, 446 size_t len)) 447 { 448 unsigned todo = 1 << v->data_dev_block_bits; 449 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 450 451 do { 452 int r; 453 u8 *page; 454 unsigned len; 455 struct bio_vec bv = bio_iter_iovec(bio, *iter); 456 457 page = bvec_kmap_local(&bv); 458 len = bv.bv_len; 459 460 if (likely(len >= todo)) 461 len = todo; 462 463 r = process(v, io, page, len); 464 kunmap_local(page); 465 466 if (r < 0) 467 return r; 468 469 bio_advance_iter(bio, iter, len); 470 todo -= len; 471 } while (todo); 472 473 return 0; 474 } 475 476 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 477 u8 *data, size_t len) 478 { 479 memset(data, 0, len); 480 return 0; 481 } 482 483 /* 484 * Moves the bio iter one data block forward. 485 */ 486 static inline void verity_bv_skip_block(struct dm_verity *v, 487 struct dm_verity_io *io, 488 struct bvec_iter *iter) 489 { 490 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 491 492 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits); 493 } 494 495 /* 496 * Verify one "dm_verity_io" structure. 497 */ 498 static int verity_verify_io(struct dm_verity_io *io) 499 { 500 bool is_zero; 501 struct dm_verity *v = io->v; 502 #if defined(CONFIG_DM_VERITY_FEC) 503 struct bvec_iter start; 504 #endif 505 struct bvec_iter iter_copy; 506 struct bvec_iter *iter; 507 struct crypto_wait wait; 508 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 509 unsigned int b; 510 511 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) { 512 /* 513 * Copy the iterator in case we need to restart 514 * verification in a work-queue. 515 */ 516 iter_copy = io->iter; 517 iter = &iter_copy; 518 } else 519 iter = &io->iter; 520 521 for (b = 0; b < io->n_blocks; b++) { 522 int r; 523 sector_t cur_block = io->block + b; 524 struct ahash_request *req = verity_io_hash_req(v, io); 525 526 if (v->validated_blocks && 527 likely(test_bit(cur_block, v->validated_blocks))) { 528 verity_bv_skip_block(v, io, iter); 529 continue; 530 } 531 532 r = verity_hash_for_block(v, io, cur_block, 533 verity_io_want_digest(v, io), 534 &is_zero); 535 if (unlikely(r < 0)) 536 return r; 537 538 if (is_zero) { 539 /* 540 * If we expect a zero block, don't validate, just 541 * return zeros. 542 */ 543 r = verity_for_bv_block(v, io, iter, 544 verity_bv_zero); 545 if (unlikely(r < 0)) 546 return r; 547 548 continue; 549 } 550 551 r = verity_hash_init(v, req, &wait); 552 if (unlikely(r < 0)) 553 return r; 554 555 #if defined(CONFIG_DM_VERITY_FEC) 556 if (verity_fec_is_enabled(v)) 557 start = *iter; 558 #endif 559 r = verity_for_io_block(v, io, iter, &wait); 560 if (unlikely(r < 0)) 561 return r; 562 563 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 564 &wait); 565 if (unlikely(r < 0)) 566 return r; 567 568 if (likely(memcmp(verity_io_real_digest(v, io), 569 verity_io_want_digest(v, io), v->digest_size) == 0)) { 570 if (v->validated_blocks) 571 set_bit(cur_block, v->validated_blocks); 572 continue; 573 } else if (static_branch_unlikely(&use_tasklet_enabled) && 574 io->in_tasklet) { 575 /* 576 * Error handling code (FEC included) cannot be run in a 577 * tasklet since it may sleep, so fallback to work-queue. 578 */ 579 return -EAGAIN; 580 #if defined(CONFIG_DM_VERITY_FEC) 581 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 582 cur_block, NULL, &start) == 0) { 583 continue; 584 #endif 585 } else { 586 if (bio->bi_status) { 587 /* 588 * Error correction failed; Just return error 589 */ 590 return -EIO; 591 } 592 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 593 cur_block)) 594 return -EIO; 595 } 596 } 597 598 return 0; 599 } 600 601 /* 602 * Skip verity work in response to I/O error when system is shutting down. 603 */ 604 static inline bool verity_is_system_shutting_down(void) 605 { 606 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 607 || system_state == SYSTEM_RESTART; 608 } 609 610 /* 611 * End one "io" structure with a given error. 612 */ 613 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 614 { 615 struct dm_verity *v = io->v; 616 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 617 618 bio->bi_end_io = io->orig_bi_end_io; 619 bio->bi_status = status; 620 621 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet) 622 verity_fec_finish_io(io); 623 624 bio_endio(bio); 625 } 626 627 static void verity_work(struct work_struct *w) 628 { 629 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 630 631 io->in_tasklet = false; 632 633 verity_fec_init_io(io); 634 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 635 } 636 637 static void verity_tasklet(unsigned long data) 638 { 639 struct dm_verity_io *io = (struct dm_verity_io *)data; 640 int err; 641 642 io->in_tasklet = true; 643 err = verity_verify_io(io); 644 if (err == -EAGAIN) { 645 /* fallback to retrying with work-queue */ 646 INIT_WORK(&io->work, verity_work); 647 queue_work(io->v->verify_wq, &io->work); 648 return; 649 } 650 651 verity_finish_io(io, errno_to_blk_status(err)); 652 } 653 654 static void verity_end_io(struct bio *bio) 655 { 656 struct dm_verity_io *io = bio->bi_private; 657 658 if (bio->bi_status && 659 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) { 660 verity_finish_io(io, bio->bi_status); 661 return; 662 } 663 664 if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) { 665 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io); 666 tasklet_schedule(&io->tasklet); 667 } else { 668 INIT_WORK(&io->work, verity_work); 669 queue_work(io->v->verify_wq, &io->work); 670 } 671 } 672 673 /* 674 * Prefetch buffers for the specified io. 675 * The root buffer is not prefetched, it is assumed that it will be cached 676 * all the time. 677 */ 678 static void verity_prefetch_io(struct work_struct *work) 679 { 680 struct dm_verity_prefetch_work *pw = 681 container_of(work, struct dm_verity_prefetch_work, work); 682 struct dm_verity *v = pw->v; 683 int i; 684 685 for (i = v->levels - 2; i >= 0; i--) { 686 sector_t hash_block_start; 687 sector_t hash_block_end; 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 if (!i) { 691 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster); 692 693 cluster >>= v->data_dev_block_bits; 694 if (unlikely(!cluster)) 695 goto no_prefetch_cluster; 696 697 if (unlikely(cluster & (cluster - 1))) 698 cluster = 1 << __fls(cluster); 699 700 hash_block_start &= ~(sector_t)(cluster - 1); 701 hash_block_end |= cluster - 1; 702 if (unlikely(hash_block_end >= v->hash_blocks)) 703 hash_block_end = v->hash_blocks - 1; 704 } 705 no_prefetch_cluster: 706 dm_bufio_prefetch(v->bufio, hash_block_start, 707 hash_block_end - hash_block_start + 1); 708 } 709 710 kfree(pw); 711 } 712 713 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 714 { 715 sector_t block = io->block; 716 unsigned int n_blocks = io->n_blocks; 717 struct dm_verity_prefetch_work *pw; 718 719 if (v->validated_blocks) { 720 while (n_blocks && test_bit(block, v->validated_blocks)) { 721 block++; 722 n_blocks--; 723 } 724 while (n_blocks && test_bit(block + n_blocks - 1, 725 v->validated_blocks)) 726 n_blocks--; 727 if (!n_blocks) 728 return; 729 } 730 731 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 732 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 733 734 if (!pw) 735 return; 736 737 INIT_WORK(&pw->work, verity_prefetch_io); 738 pw->v = v; 739 pw->block = block; 740 pw->n_blocks = n_blocks; 741 queue_work(v->verify_wq, &pw->work); 742 } 743 744 /* 745 * Bio map function. It allocates dm_verity_io structure and bio vector and 746 * fills them. Then it issues prefetches and the I/O. 747 */ 748 static int verity_map(struct dm_target *ti, struct bio *bio) 749 { 750 struct dm_verity *v = ti->private; 751 struct dm_verity_io *io; 752 753 bio_set_dev(bio, v->data_dev->bdev); 754 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 755 756 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) & 757 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 758 DMERR_LIMIT("unaligned io"); 759 return DM_MAPIO_KILL; 760 } 761 762 if (bio_end_sector(bio) >> 763 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 764 DMERR_LIMIT("io out of range"); 765 return DM_MAPIO_KILL; 766 } 767 768 if (bio_data_dir(bio) == WRITE) 769 return DM_MAPIO_KILL; 770 771 io = dm_per_bio_data(bio, ti->per_io_data_size); 772 io->v = v; 773 io->orig_bi_end_io = bio->bi_end_io; 774 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 775 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 776 777 bio->bi_end_io = verity_end_io; 778 bio->bi_private = io; 779 io->iter = bio->bi_iter; 780 781 verity_submit_prefetch(v, io); 782 783 submit_bio_noacct(bio); 784 785 return DM_MAPIO_SUBMITTED; 786 } 787 788 /* 789 * Status: V (valid) or C (corruption found) 790 */ 791 static void verity_status(struct dm_target *ti, status_type_t type, 792 unsigned status_flags, char *result, unsigned maxlen) 793 { 794 struct dm_verity *v = ti->private; 795 unsigned args = 0; 796 unsigned sz = 0; 797 unsigned x; 798 799 switch (type) { 800 case STATUSTYPE_INFO: 801 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 802 break; 803 case STATUSTYPE_TABLE: 804 DMEMIT("%u %s %s %u %u %llu %llu %s ", 805 v->version, 806 v->data_dev->name, 807 v->hash_dev->name, 808 1 << v->data_dev_block_bits, 809 1 << v->hash_dev_block_bits, 810 (unsigned long long)v->data_blocks, 811 (unsigned long long)v->hash_start, 812 v->alg_name 813 ); 814 for (x = 0; x < v->digest_size; x++) 815 DMEMIT("%02x", v->root_digest[x]); 816 DMEMIT(" "); 817 if (!v->salt_size) 818 DMEMIT("-"); 819 else 820 for (x = 0; x < v->salt_size; x++) 821 DMEMIT("%02x", v->salt[x]); 822 if (v->mode != DM_VERITY_MODE_EIO) 823 args++; 824 if (verity_fec_is_enabled(v)) 825 args += DM_VERITY_OPTS_FEC; 826 if (v->zero_digest) 827 args++; 828 if (v->validated_blocks) 829 args++; 830 if (v->use_tasklet) 831 args++; 832 if (v->signature_key_desc) 833 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 834 if (!args) 835 return; 836 DMEMIT(" %u", args); 837 if (v->mode != DM_VERITY_MODE_EIO) { 838 DMEMIT(" "); 839 switch (v->mode) { 840 case DM_VERITY_MODE_LOGGING: 841 DMEMIT(DM_VERITY_OPT_LOGGING); 842 break; 843 case DM_VERITY_MODE_RESTART: 844 DMEMIT(DM_VERITY_OPT_RESTART); 845 break; 846 case DM_VERITY_MODE_PANIC: 847 DMEMIT(DM_VERITY_OPT_PANIC); 848 break; 849 default: 850 BUG(); 851 } 852 } 853 if (v->zero_digest) 854 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 855 if (v->validated_blocks) 856 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 857 if (v->use_tasklet) 858 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 859 sz = verity_fec_status_table(v, sz, result, maxlen); 860 if (v->signature_key_desc) 861 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 862 " %s", v->signature_key_desc); 863 break; 864 865 case STATUSTYPE_IMA: 866 DMEMIT_TARGET_NAME_VERSION(ti->type); 867 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 868 DMEMIT(",verity_version=%u", v->version); 869 DMEMIT(",data_device_name=%s", v->data_dev->name); 870 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 871 DMEMIT(",verity_algorithm=%s", v->alg_name); 872 873 DMEMIT(",root_digest="); 874 for (x = 0; x < v->digest_size; x++) 875 DMEMIT("%02x", v->root_digest[x]); 876 877 DMEMIT(",salt="); 878 if (!v->salt_size) 879 DMEMIT("-"); 880 else 881 for (x = 0; x < v->salt_size; x++) 882 DMEMIT("%02x", v->salt[x]); 883 884 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 885 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 886 if (v->signature_key_desc) 887 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 888 889 if (v->mode != DM_VERITY_MODE_EIO) { 890 DMEMIT(",verity_mode="); 891 switch (v->mode) { 892 case DM_VERITY_MODE_LOGGING: 893 DMEMIT(DM_VERITY_OPT_LOGGING); 894 break; 895 case DM_VERITY_MODE_RESTART: 896 DMEMIT(DM_VERITY_OPT_RESTART); 897 break; 898 case DM_VERITY_MODE_PANIC: 899 DMEMIT(DM_VERITY_OPT_PANIC); 900 break; 901 default: 902 DMEMIT("invalid"); 903 } 904 } 905 DMEMIT(";"); 906 break; 907 } 908 } 909 910 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 911 { 912 struct dm_verity *v = ti->private; 913 914 *bdev = v->data_dev->bdev; 915 916 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 917 return 1; 918 return 0; 919 } 920 921 static int verity_iterate_devices(struct dm_target *ti, 922 iterate_devices_callout_fn fn, void *data) 923 { 924 struct dm_verity *v = ti->private; 925 926 return fn(ti, v->data_dev, v->data_start, ti->len, data); 927 } 928 929 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 930 { 931 struct dm_verity *v = ti->private; 932 933 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 934 limits->logical_block_size = 1 << v->data_dev_block_bits; 935 936 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 937 limits->physical_block_size = 1 << v->data_dev_block_bits; 938 939 blk_limits_io_min(limits, limits->logical_block_size); 940 } 941 942 static void verity_dtr(struct dm_target *ti) 943 { 944 struct dm_verity *v = ti->private; 945 946 if (v->verify_wq) 947 destroy_workqueue(v->verify_wq); 948 949 if (v->bufio) 950 dm_bufio_client_destroy(v->bufio); 951 952 kvfree(v->validated_blocks); 953 kfree(v->salt); 954 kfree(v->root_digest); 955 kfree(v->zero_digest); 956 957 if (v->tfm) 958 crypto_free_ahash(v->tfm); 959 960 kfree(v->alg_name); 961 962 if (v->hash_dev) 963 dm_put_device(ti, v->hash_dev); 964 965 if (v->data_dev) 966 dm_put_device(ti, v->data_dev); 967 968 verity_fec_dtr(v); 969 970 kfree(v->signature_key_desc); 971 972 if (v->use_tasklet) 973 static_branch_dec(&use_tasklet_enabled); 974 975 kfree(v); 976 } 977 978 static int verity_alloc_most_once(struct dm_verity *v) 979 { 980 struct dm_target *ti = v->ti; 981 982 /* the bitset can only handle INT_MAX blocks */ 983 if (v->data_blocks > INT_MAX) { 984 ti->error = "device too large to use check_at_most_once"; 985 return -E2BIG; 986 } 987 988 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 989 sizeof(unsigned long), 990 GFP_KERNEL); 991 if (!v->validated_blocks) { 992 ti->error = "failed to allocate bitset for check_at_most_once"; 993 return -ENOMEM; 994 } 995 996 return 0; 997 } 998 999 static int verity_alloc_zero_digest(struct dm_verity *v) 1000 { 1001 int r = -ENOMEM; 1002 struct ahash_request *req; 1003 u8 *zero_data; 1004 1005 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1006 1007 if (!v->zero_digest) 1008 return r; 1009 1010 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 1011 1012 if (!req) 1013 return r; /* verity_dtr will free zero_digest */ 1014 1015 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1016 1017 if (!zero_data) 1018 goto out; 1019 1020 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 1021 v->zero_digest); 1022 1023 out: 1024 kfree(req); 1025 kfree(zero_data); 1026 1027 return r; 1028 } 1029 1030 static inline bool verity_is_verity_mode(const char *arg_name) 1031 { 1032 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1033 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1034 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1035 } 1036 1037 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1038 { 1039 if (v->mode) 1040 return -EINVAL; 1041 1042 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1043 v->mode = DM_VERITY_MODE_LOGGING; 1044 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1045 v->mode = DM_VERITY_MODE_RESTART; 1046 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1047 v->mode = DM_VERITY_MODE_PANIC; 1048 1049 return 0; 1050 } 1051 1052 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1053 struct dm_verity_sig_opts *verify_args, 1054 bool only_modifier_opts) 1055 { 1056 int r; 1057 unsigned argc; 1058 struct dm_target *ti = v->ti; 1059 const char *arg_name; 1060 1061 static const struct dm_arg _args[] = { 1062 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1063 }; 1064 1065 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1066 if (r) 1067 return -EINVAL; 1068 1069 if (!argc) 1070 return 0; 1071 1072 do { 1073 arg_name = dm_shift_arg(as); 1074 argc--; 1075 1076 if (verity_is_verity_mode(arg_name)) { 1077 if (only_modifier_opts) 1078 continue; 1079 r = verity_parse_verity_mode(v, arg_name); 1080 if (r) { 1081 ti->error = "Conflicting error handling parameters"; 1082 return r; 1083 } 1084 continue; 1085 1086 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1087 if (only_modifier_opts) 1088 continue; 1089 r = verity_alloc_zero_digest(v); 1090 if (r) { 1091 ti->error = "Cannot allocate zero digest"; 1092 return r; 1093 } 1094 continue; 1095 1096 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1097 if (only_modifier_opts) 1098 continue; 1099 r = verity_alloc_most_once(v); 1100 if (r) 1101 return r; 1102 continue; 1103 1104 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1105 v->use_tasklet = true; 1106 static_branch_inc(&use_tasklet_enabled); 1107 continue; 1108 1109 } else if (verity_is_fec_opt_arg(arg_name)) { 1110 if (only_modifier_opts) 1111 continue; 1112 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1113 if (r) 1114 return r; 1115 continue; 1116 1117 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1118 if (only_modifier_opts) 1119 continue; 1120 r = verity_verify_sig_parse_opt_args(as, v, 1121 verify_args, 1122 &argc, arg_name); 1123 if (r) 1124 return r; 1125 continue; 1126 } 1127 1128 ti->error = "Unrecognized verity feature request"; 1129 return -EINVAL; 1130 } while (argc && !r); 1131 1132 return r; 1133 } 1134 1135 /* 1136 * Target parameters: 1137 * <version> The current format is version 1. 1138 * Vsn 0 is compatible with original Chromium OS releases. 1139 * <data device> 1140 * <hash device> 1141 * <data block size> 1142 * <hash block size> 1143 * <the number of data blocks> 1144 * <hash start block> 1145 * <algorithm> 1146 * <digest> 1147 * <salt> Hex string or "-" if no salt. 1148 */ 1149 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) 1150 { 1151 struct dm_verity *v; 1152 struct dm_verity_sig_opts verify_args = {0}; 1153 struct dm_arg_set as; 1154 unsigned int num; 1155 unsigned int wq_flags; 1156 unsigned long long num_ll; 1157 int r; 1158 int i; 1159 sector_t hash_position; 1160 char dummy; 1161 char *root_hash_digest_to_validate; 1162 1163 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1164 if (!v) { 1165 ti->error = "Cannot allocate verity structure"; 1166 return -ENOMEM; 1167 } 1168 ti->private = v; 1169 v->ti = ti; 1170 1171 r = verity_fec_ctr_alloc(v); 1172 if (r) 1173 goto bad; 1174 1175 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { 1176 ti->error = "Device must be readonly"; 1177 r = -EINVAL; 1178 goto bad; 1179 } 1180 1181 if (argc < 10) { 1182 ti->error = "Not enough arguments"; 1183 r = -EINVAL; 1184 goto bad; 1185 } 1186 1187 /* Parse optional parameters that modify primary args */ 1188 if (argc > 10) { 1189 as.argc = argc - 10; 1190 as.argv = argv + 10; 1191 r = verity_parse_opt_args(&as, v, &verify_args, true); 1192 if (r < 0) 1193 goto bad; 1194 } 1195 1196 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1197 num > 1) { 1198 ti->error = "Invalid version"; 1199 r = -EINVAL; 1200 goto bad; 1201 } 1202 v->version = num; 1203 1204 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); 1205 if (r) { 1206 ti->error = "Data device lookup failed"; 1207 goto bad; 1208 } 1209 1210 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); 1211 if (r) { 1212 ti->error = "Hash device lookup failed"; 1213 goto bad; 1214 } 1215 1216 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1217 !num || (num & (num - 1)) || 1218 num < bdev_logical_block_size(v->data_dev->bdev) || 1219 num > PAGE_SIZE) { 1220 ti->error = "Invalid data device block size"; 1221 r = -EINVAL; 1222 goto bad; 1223 } 1224 v->data_dev_block_bits = __ffs(num); 1225 1226 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1227 !num || (num & (num - 1)) || 1228 num < bdev_logical_block_size(v->hash_dev->bdev) || 1229 num > INT_MAX) { 1230 ti->error = "Invalid hash device block size"; 1231 r = -EINVAL; 1232 goto bad; 1233 } 1234 v->hash_dev_block_bits = __ffs(num); 1235 1236 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1237 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1238 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1239 ti->error = "Invalid data blocks"; 1240 r = -EINVAL; 1241 goto bad; 1242 } 1243 v->data_blocks = num_ll; 1244 1245 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1246 ti->error = "Data device is too small"; 1247 r = -EINVAL; 1248 goto bad; 1249 } 1250 1251 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1252 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1253 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1254 ti->error = "Invalid hash start"; 1255 r = -EINVAL; 1256 goto bad; 1257 } 1258 v->hash_start = num_ll; 1259 1260 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1261 if (!v->alg_name) { 1262 ti->error = "Cannot allocate algorithm name"; 1263 r = -ENOMEM; 1264 goto bad; 1265 } 1266 1267 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 1268 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0); 1269 if (IS_ERR(v->tfm)) { 1270 ti->error = "Cannot initialize hash function"; 1271 r = PTR_ERR(v->tfm); 1272 v->tfm = NULL; 1273 goto bad; 1274 } 1275 1276 /* 1277 * dm-verity performance can vary greatly depending on which hash 1278 * algorithm implementation is used. Help people debug performance 1279 * problems by logging the ->cra_driver_name. 1280 */ 1281 DMINFO("%s using implementation \"%s\"", v->alg_name, 1282 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1283 1284 v->digest_size = crypto_ahash_digestsize(v->tfm); 1285 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1286 ti->error = "Digest size too big"; 1287 r = -EINVAL; 1288 goto bad; 1289 } 1290 v->ahash_reqsize = sizeof(struct ahash_request) + 1291 crypto_ahash_reqsize(v->tfm); 1292 1293 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1294 if (!v->root_digest) { 1295 ti->error = "Cannot allocate root digest"; 1296 r = -ENOMEM; 1297 goto bad; 1298 } 1299 if (strlen(argv[8]) != v->digest_size * 2 || 1300 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1301 ti->error = "Invalid root digest"; 1302 r = -EINVAL; 1303 goto bad; 1304 } 1305 root_hash_digest_to_validate = argv[8]; 1306 1307 if (strcmp(argv[9], "-")) { 1308 v->salt_size = strlen(argv[9]) / 2; 1309 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1310 if (!v->salt) { 1311 ti->error = "Cannot allocate salt"; 1312 r = -ENOMEM; 1313 goto bad; 1314 } 1315 if (strlen(argv[9]) != v->salt_size * 2 || 1316 hex2bin(v->salt, argv[9], v->salt_size)) { 1317 ti->error = "Invalid salt"; 1318 r = -EINVAL; 1319 goto bad; 1320 } 1321 } 1322 1323 argv += 10; 1324 argc -= 10; 1325 1326 /* Optional parameters */ 1327 if (argc) { 1328 as.argc = argc; 1329 as.argv = argv; 1330 r = verity_parse_opt_args(&as, v, &verify_args, false); 1331 if (r < 0) 1332 goto bad; 1333 } 1334 1335 /* Root hash signature is a optional parameter*/ 1336 r = verity_verify_root_hash(root_hash_digest_to_validate, 1337 strlen(root_hash_digest_to_validate), 1338 verify_args.sig, 1339 verify_args.sig_size); 1340 if (r < 0) { 1341 ti->error = "Root hash verification failed"; 1342 goto bad; 1343 } 1344 v->hash_per_block_bits = 1345 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1346 1347 v->levels = 0; 1348 if (v->data_blocks) 1349 while (v->hash_per_block_bits * v->levels < 64 && 1350 (unsigned long long)(v->data_blocks - 1) >> 1351 (v->hash_per_block_bits * v->levels)) 1352 v->levels++; 1353 1354 if (v->levels > DM_VERITY_MAX_LEVELS) { 1355 ti->error = "Too many tree levels"; 1356 r = -E2BIG; 1357 goto bad; 1358 } 1359 1360 hash_position = v->hash_start; 1361 for (i = v->levels - 1; i >= 0; i--) { 1362 sector_t s; 1363 v->hash_level_block[i] = hash_position; 1364 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1365 >> ((i + 1) * v->hash_per_block_bits); 1366 if (hash_position + s < hash_position) { 1367 ti->error = "Hash device offset overflow"; 1368 r = -E2BIG; 1369 goto bad; 1370 } 1371 hash_position += s; 1372 } 1373 v->hash_blocks = hash_position; 1374 1375 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1376 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1377 dm_bufio_alloc_callback, NULL, 1378 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1379 if (IS_ERR(v->bufio)) { 1380 ti->error = "Cannot initialize dm-bufio"; 1381 r = PTR_ERR(v->bufio); 1382 v->bufio = NULL; 1383 goto bad; 1384 } 1385 1386 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1387 ti->error = "Hash device is too small"; 1388 r = -E2BIG; 1389 goto bad; 1390 } 1391 1392 /* WQ_UNBOUND greatly improves performance when running on ramdisk */ 1393 wq_flags = WQ_MEM_RECLAIM | WQ_UNBOUND; 1394 if (v->use_tasklet) { 1395 /* 1396 * Allow verify_wq to preempt softirq since verification in 1397 * tasklet will fall-back to using it for error handling 1398 * (or if the bufio cache doesn't have required hashes). 1399 */ 1400 wq_flags |= WQ_HIGHPRI; 1401 } 1402 v->verify_wq = alloc_workqueue("kverityd", wq_flags, num_online_cpus()); 1403 if (!v->verify_wq) { 1404 ti->error = "Cannot allocate workqueue"; 1405 r = -ENOMEM; 1406 goto bad; 1407 } 1408 1409 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1410 v->ahash_reqsize + v->digest_size * 2; 1411 1412 r = verity_fec_ctr(v); 1413 if (r) 1414 goto bad; 1415 1416 ti->per_io_data_size = roundup(ti->per_io_data_size, 1417 __alignof__(struct dm_verity_io)); 1418 1419 verity_verify_sig_opts_cleanup(&verify_args); 1420 1421 return 0; 1422 1423 bad: 1424 1425 verity_verify_sig_opts_cleanup(&verify_args); 1426 verity_dtr(ti); 1427 1428 return r; 1429 } 1430 1431 /* 1432 * Check whether a DM target is a verity target. 1433 */ 1434 bool dm_is_verity_target(struct dm_target *ti) 1435 { 1436 return ti->type->module == THIS_MODULE; 1437 } 1438 1439 /* 1440 * Get the root digest of a verity target. 1441 * 1442 * Returns a copy of the root digest, the caller is responsible for 1443 * freeing the memory of the digest. 1444 */ 1445 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1446 { 1447 struct dm_verity *v = ti->private; 1448 1449 if (!dm_is_verity_target(ti)) 1450 return -EINVAL; 1451 1452 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1453 if (*root_digest == NULL) 1454 return -ENOMEM; 1455 1456 *digest_size = v->digest_size; 1457 1458 return 0; 1459 } 1460 1461 static struct target_type verity_target = { 1462 .name = "verity", 1463 .features = DM_TARGET_IMMUTABLE, 1464 .version = {1, 9, 0}, 1465 .module = THIS_MODULE, 1466 .ctr = verity_ctr, 1467 .dtr = verity_dtr, 1468 .map = verity_map, 1469 .status = verity_status, 1470 .prepare_ioctl = verity_prepare_ioctl, 1471 .iterate_devices = verity_iterate_devices, 1472 .io_hints = verity_io_hints, 1473 }; 1474 1475 static int __init dm_verity_init(void) 1476 { 1477 int r; 1478 1479 r = dm_register_target(&verity_target); 1480 if (r < 0) 1481 DMERR("register failed %d", r); 1482 1483 return r; 1484 } 1485 1486 static void __exit dm_verity_exit(void) 1487 { 1488 dm_unregister_target(&verity_target); 1489 } 1490 1491 module_init(dm_verity_init); 1492 module_exit(dm_verity_exit); 1493 1494 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1495 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1496 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1497 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1498 MODULE_LICENSE("GPL"); 1499