1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * Copyright (C) 2012 Red Hat, Inc. 4 * 5 * Author: Mikulas Patocka <mpatocka@redhat.com> 6 * 7 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors 8 * 9 * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set 10 * default prefetch value. Data are read in "prefetch_cluster" chunks from the 11 * hash device. Setting this greatly improves performance when data and hash 12 * are on the same disk on different partitions on devices with poor random 13 * access behavior. 14 */ 15 16#include "dm-verity.h" 17#include "dm-verity-fec.h" 18#include "dm-verity-verify-sig.h" 19#include "dm-audit.h" 20#include <linux/module.h> 21#include <linux/reboot.h> 22#include <linux/scatterlist.h> 23#include <linux/string.h> 24#include <linux/jump_label.h> 25 26#define DM_MSG_PREFIX "verity" 27 28#define DM_VERITY_ENV_LENGTH 42 29#define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 30 31#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 32 33#define DM_VERITY_MAX_CORRUPTED_ERRS 100 34 35#define DM_VERITY_OPT_LOGGING "ignore_corruption" 36#define DM_VERITY_OPT_RESTART "restart_on_corruption" 37#define DM_VERITY_OPT_PANIC "panic_on_corruption" 38#define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 39#define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 40#define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet" 41 42#define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \ 43 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 44 45static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 46 47module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644); 48 49static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled); 50 51struct dm_verity_prefetch_work { 52 struct work_struct work; 53 struct dm_verity *v; 54 sector_t block; 55 unsigned int n_blocks; 56}; 57 58/* 59 * Auxiliary structure appended to each dm-bufio buffer. If the value 60 * hash_verified is nonzero, hash of the block has been verified. 61 * 62 * The variable hash_verified is set to 0 when allocating the buffer, then 63 * it can be changed to 1 and it is never reset to 0 again. 64 * 65 * There is no lock around this value, a race condition can at worst cause 66 * that multiple processes verify the hash of the same buffer simultaneously 67 * and write 1 to hash_verified simultaneously. 68 * This condition is harmless, so we don't need locking. 69 */ 70struct buffer_aux { 71 int hash_verified; 72}; 73 74/* 75 * Initialize struct buffer_aux for a freshly created buffer. 76 */ 77static void dm_bufio_alloc_callback(struct dm_buffer *buf) 78{ 79 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 80 81 aux->hash_verified = 0; 82} 83 84/* 85 * Translate input sector number to the sector number on the target device. 86 */ 87static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 88{ 89 return v->data_start + dm_target_offset(v->ti, bi_sector); 90} 91 92/* 93 * Return hash position of a specified block at a specified tree level 94 * (0 is the lowest level). 95 * The lowest "hash_per_block_bits"-bits of the result denote hash position 96 * inside a hash block. The remaining bits denote location of the hash block. 97 */ 98static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 99 int level) 100{ 101 return block >> (level * v->hash_per_block_bits); 102} 103 104static int verity_hash_update(struct dm_verity *v, struct ahash_request *req, 105 const u8 *data, size_t len, 106 struct crypto_wait *wait) 107{ 108 struct scatterlist sg; 109 110 if (likely(!is_vmalloc_addr(data))) { 111 sg_init_one(&sg, data, len); 112 ahash_request_set_crypt(req, &sg, NULL, len); 113 return crypto_wait_req(crypto_ahash_update(req), wait); 114 } 115 116 do { 117 int r; 118 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 119 120 flush_kernel_vmap_range((void *)data, this_step); 121 sg_init_table(&sg, 1); 122 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 123 ahash_request_set_crypt(req, &sg, NULL, this_step); 124 r = crypto_wait_req(crypto_ahash_update(req), wait); 125 if (unlikely(r)) 126 return r; 127 data += this_step; 128 len -= this_step; 129 } while (len); 130 131 return 0; 132} 133 134/* 135 * Wrapper for crypto_ahash_init, which handles verity salting. 136 */ 137static int verity_hash_init(struct dm_verity *v, struct ahash_request *req, 138 struct crypto_wait *wait, bool may_sleep) 139{ 140 int r; 141 142 ahash_request_set_tfm(req, v->tfm); 143 ahash_request_set_callback(req, 144 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0, 145 crypto_req_done, (void *)wait); 146 crypto_init_wait(wait); 147 148 r = crypto_wait_req(crypto_ahash_init(req), wait); 149 150 if (unlikely(r < 0)) { 151 if (r != -ENOMEM) 152 DMERR("crypto_ahash_init failed: %d", r); 153 return r; 154 } 155 156 if (likely(v->salt_size && (v->version >= 1))) 157 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 158 159 return r; 160} 161 162static int verity_hash_final(struct dm_verity *v, struct ahash_request *req, 163 u8 *digest, struct crypto_wait *wait) 164{ 165 int r; 166 167 if (unlikely(v->salt_size && (!v->version))) { 168 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 169 170 if (r < 0) { 171 DMERR("%s failed updating salt: %d", __func__, r); 172 goto out; 173 } 174 } 175 176 ahash_request_set_crypt(req, NULL, digest, 0); 177 r = crypto_wait_req(crypto_ahash_final(req), wait); 178out: 179 return r; 180} 181 182int verity_hash(struct dm_verity *v, struct ahash_request *req, 183 const u8 *data, size_t len, u8 *digest, bool may_sleep) 184{ 185 int r; 186 struct crypto_wait wait; 187 188 r = verity_hash_init(v, req, &wait, may_sleep); 189 if (unlikely(r < 0)) 190 goto out; 191 192 r = verity_hash_update(v, req, data, len, &wait); 193 if (unlikely(r < 0)) 194 goto out; 195 196 r = verity_hash_final(v, req, digest, &wait); 197 198out: 199 return r; 200} 201 202static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 203 sector_t *hash_block, unsigned int *offset) 204{ 205 sector_t position = verity_position_at_level(v, block, level); 206 unsigned int idx; 207 208 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 209 210 if (!offset) 211 return; 212 213 idx = position & ((1 << v->hash_per_block_bits) - 1); 214 if (!v->version) 215 *offset = idx * v->digest_size; 216 else 217 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 218} 219 220/* 221 * Handle verification errors. 222 */ 223static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 224 unsigned long long block) 225{ 226 char verity_env[DM_VERITY_ENV_LENGTH]; 227 char *envp[] = { verity_env, NULL }; 228 const char *type_str = ""; 229 struct mapped_device *md = dm_table_get_md(v->ti->table); 230 231 /* Corruption should be visible in device status in all modes */ 232 v->hash_failed = true; 233 234 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 235 goto out; 236 237 v->corrupted_errs++; 238 239 switch (type) { 240 case DM_VERITY_BLOCK_TYPE_DATA: 241 type_str = "data"; 242 break; 243 case DM_VERITY_BLOCK_TYPE_METADATA: 244 type_str = "metadata"; 245 break; 246 default: 247 BUG(); 248 } 249 250 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 251 type_str, block); 252 253 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { 254 DMERR("%s: reached maximum errors", v->data_dev->name); 255 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); 256 } 257 258 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 259 DM_VERITY_ENV_VAR_NAME, type, block); 260 261 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 262 263out: 264 if (v->mode == DM_VERITY_MODE_LOGGING) 265 return 0; 266 267 if (v->mode == DM_VERITY_MODE_RESTART) 268 kernel_restart("dm-verity device corrupted"); 269 270 if (v->mode == DM_VERITY_MODE_PANIC) 271 panic("dm-verity device corrupted"); 272 273 return 1; 274} 275 276/* 277 * Verify hash of a metadata block pertaining to the specified data block 278 * ("block" argument) at a specified level ("level" argument). 279 * 280 * On successful return, verity_io_want_digest(v, io) contains the hash value 281 * for a lower tree level or for the data block (if we're at the lowest level). 282 * 283 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 284 * If "skip_unverified" is false, unverified buffer is hashed and verified 285 * against current value of verity_io_want_digest(v, io). 286 */ 287static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 288 sector_t block, int level, bool skip_unverified, 289 u8 *want_digest) 290{ 291 struct dm_buffer *buf; 292 struct buffer_aux *aux; 293 u8 *data; 294 int r; 295 sector_t hash_block; 296 unsigned int offset; 297 298 verity_hash_at_level(v, block, level, &hash_block, &offset); 299 300 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) { 301 data = dm_bufio_get(v->bufio, hash_block, &buf); 302 if (data == NULL) { 303 /* 304 * In tasklet and the hash was not in the bufio cache. 305 * Return early and resume execution from a work-queue 306 * to read the hash from disk. 307 */ 308 return -EAGAIN; 309 } 310 } else 311 data = dm_bufio_read(v->bufio, hash_block, &buf); 312 313 if (IS_ERR(data)) 314 return PTR_ERR(data); 315 316 aux = dm_bufio_get_aux_data(buf); 317 318 if (!aux->hash_verified) { 319 if (skip_unverified) { 320 r = 1; 321 goto release_ret_r; 322 } 323 324 r = verity_hash(v, verity_io_hash_req(v, io), 325 data, 1 << v->hash_dev_block_bits, 326 verity_io_real_digest(v, io), !io->in_tasklet); 327 if (unlikely(r < 0)) 328 goto release_ret_r; 329 330 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 331 v->digest_size) == 0)) 332 aux->hash_verified = 1; 333 else if (static_branch_unlikely(&use_tasklet_enabled) && 334 io->in_tasklet) { 335 /* 336 * Error handling code (FEC included) cannot be run in a 337 * tasklet since it may sleep, so fallback to work-queue. 338 */ 339 r = -EAGAIN; 340 goto release_ret_r; 341 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 342 hash_block, data, NULL) == 0) 343 aux->hash_verified = 1; 344 else if (verity_handle_err(v, 345 DM_VERITY_BLOCK_TYPE_METADATA, 346 hash_block)) { 347 struct bio *bio = 348 dm_bio_from_per_bio_data(io, 349 v->ti->per_io_data_size); 350 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, 351 block, 0); 352 r = -EIO; 353 goto release_ret_r; 354 } 355 } 356 357 data += offset; 358 memcpy(want_digest, data, v->digest_size); 359 r = 0; 360 361release_ret_r: 362 dm_bufio_release(buf); 363 return r; 364} 365 366/* 367 * Find a hash for a given block, write it to digest and verify the integrity 368 * of the hash tree if necessary. 369 */ 370int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 371 sector_t block, u8 *digest, bool *is_zero) 372{ 373 int r = 0, i; 374 375 if (likely(v->levels)) { 376 /* 377 * First, we try to get the requested hash for 378 * the current block. If the hash block itself is 379 * verified, zero is returned. If it isn't, this 380 * function returns 1 and we fall back to whole 381 * chain verification. 382 */ 383 r = verity_verify_level(v, io, block, 0, true, digest); 384 if (likely(r <= 0)) 385 goto out; 386 } 387 388 memcpy(digest, v->root_digest, v->digest_size); 389 390 for (i = v->levels - 1; i >= 0; i--) { 391 r = verity_verify_level(v, io, block, i, false, digest); 392 if (unlikely(r)) 393 goto out; 394 } 395out: 396 if (!r && v->zero_digest) 397 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 398 else 399 *is_zero = false; 400 401 return r; 402} 403 404/* 405 * Calculates the digest for the given bio 406 */ 407static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, 408 struct bvec_iter *iter, struct crypto_wait *wait) 409{ 410 unsigned int todo = 1 << v->data_dev_block_bits; 411 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 412 struct scatterlist sg; 413 struct ahash_request *req = verity_io_hash_req(v, io); 414 415 do { 416 int r; 417 unsigned int len; 418 struct bio_vec bv = bio_iter_iovec(bio, *iter); 419 420 sg_init_table(&sg, 1); 421 422 len = bv.bv_len; 423 424 if (likely(len >= todo)) 425 len = todo; 426 /* 427 * Operating on a single page at a time looks suboptimal 428 * until you consider the typical block size is 4,096B. 429 * Going through this loops twice should be very rare. 430 */ 431 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset); 432 ahash_request_set_crypt(req, &sg, NULL, len); 433 r = crypto_wait_req(crypto_ahash_update(req), wait); 434 435 if (unlikely(r < 0)) { 436 DMERR("%s crypto op failed: %d", __func__, r); 437 return r; 438 } 439 440 bio_advance_iter(bio, iter, len); 441 todo -= len; 442 } while (todo); 443 444 return 0; 445} 446 447/* 448 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 449 * starting from iter. 450 */ 451int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 452 struct bvec_iter *iter, 453 int (*process)(struct dm_verity *v, 454 struct dm_verity_io *io, u8 *data, 455 size_t len)) 456{ 457 unsigned int todo = 1 << v->data_dev_block_bits; 458 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 459 460 do { 461 int r; 462 u8 *page; 463 unsigned int len; 464 struct bio_vec bv = bio_iter_iovec(bio, *iter); 465 466 page = bvec_kmap_local(&bv); 467 len = bv.bv_len; 468 469 if (likely(len >= todo)) 470 len = todo; 471 472 r = process(v, io, page, len); 473 kunmap_local(page); 474 475 if (r < 0) 476 return r; 477 478 bio_advance_iter(bio, iter, len); 479 todo -= len; 480 } while (todo); 481 482 return 0; 483} 484 485static int verity_recheck_copy(struct dm_verity *v, struct dm_verity_io *io, 486 u8 *data, size_t len) 487{ 488 memcpy(data, io->recheck_buffer, len); 489 io->recheck_buffer += len; 490 491 return 0; 492} 493 494static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io, 495 struct bvec_iter start, sector_t cur_block) 496{ 497 struct page *page; 498 void *buffer; 499 int r; 500 struct dm_io_request io_req; 501 struct dm_io_region io_loc; 502 503 page = mempool_alloc(&v->recheck_pool, GFP_NOIO); 504 buffer = page_to_virt(page); 505 506 io_req.bi_opf = REQ_OP_READ; 507 io_req.mem.type = DM_IO_KMEM; 508 io_req.mem.ptr.addr = buffer; 509 io_req.notify.fn = NULL; 510 io_req.client = v->io; 511 io_loc.bdev = v->data_dev->bdev; 512 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT); 513 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT); 514 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT); 515 if (unlikely(r)) 516 goto free_ret; 517 518 r = verity_hash(v, verity_io_hash_req(v, io), buffer, 519 1 << v->data_dev_block_bits, 520 verity_io_real_digest(v, io), true); 521 if (unlikely(r)) 522 goto free_ret; 523 524 if (memcmp(verity_io_real_digest(v, io), 525 verity_io_want_digest(v, io), v->digest_size)) { 526 r = -EIO; 527 goto free_ret; 528 } 529 530 io->recheck_buffer = buffer; 531 r = verity_for_bv_block(v, io, &start, verity_recheck_copy); 532 if (unlikely(r)) 533 goto free_ret; 534 535 r = 0; 536free_ret: 537 mempool_free(page, &v->recheck_pool); 538 539 return r; 540} 541 542static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 543 u8 *data, size_t len) 544{ 545 memset(data, 0, len); 546 return 0; 547} 548 549/* 550 * Moves the bio iter one data block forward. 551 */ 552static inline void verity_bv_skip_block(struct dm_verity *v, 553 struct dm_verity_io *io, 554 struct bvec_iter *iter) 555{ 556 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 557 558 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits); 559} 560 561/* 562 * Verify one "dm_verity_io" structure. 563 */ 564static int verity_verify_io(struct dm_verity_io *io) 565{ 566 bool is_zero; 567 struct dm_verity *v = io->v; 568 struct bvec_iter start; 569 struct bvec_iter iter_copy; 570 struct bvec_iter *iter; 571 struct crypto_wait wait; 572 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 573 unsigned int b; 574 575 if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) { 576 /* 577 * Copy the iterator in case we need to restart 578 * verification in a work-queue. 579 */ 580 iter_copy = io->iter; 581 iter = &iter_copy; 582 } else 583 iter = &io->iter; 584 585 for (b = 0; b < io->n_blocks; b++) { 586 int r; 587 sector_t cur_block = io->block + b; 588 struct ahash_request *req = verity_io_hash_req(v, io); 589 590 if (v->validated_blocks && bio->bi_status == BLK_STS_OK && 591 likely(test_bit(cur_block, v->validated_blocks))) { 592 verity_bv_skip_block(v, io, iter); 593 continue; 594 } 595 596 r = verity_hash_for_block(v, io, cur_block, 597 verity_io_want_digest(v, io), 598 &is_zero); 599 if (unlikely(r < 0)) 600 return r; 601 602 if (is_zero) { 603 /* 604 * If we expect a zero block, don't validate, just 605 * return zeros. 606 */ 607 r = verity_for_bv_block(v, io, iter, 608 verity_bv_zero); 609 if (unlikely(r < 0)) 610 return r; 611 612 continue; 613 } 614 615 r = verity_hash_init(v, req, &wait, !io->in_tasklet); 616 if (unlikely(r < 0)) 617 return r; 618 619 start = *iter; 620 r = verity_for_io_block(v, io, iter, &wait); 621 if (unlikely(r < 0)) 622 return r; 623 624 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 625 &wait); 626 if (unlikely(r < 0)) 627 return r; 628 629 if (likely(memcmp(verity_io_real_digest(v, io), 630 verity_io_want_digest(v, io), v->digest_size) == 0)) { 631 if (v->validated_blocks) 632 set_bit(cur_block, v->validated_blocks); 633 continue; 634 } else if (static_branch_unlikely(&use_tasklet_enabled) && 635 io->in_tasklet) { 636 /* 637 * Error handling code (FEC included) cannot be run in a 638 * tasklet since it may sleep, so fallback to work-queue. 639 */ 640 return -EAGAIN; 641 } else if (verity_recheck(v, io, start, cur_block) == 0) { 642 if (v->validated_blocks) 643 set_bit(cur_block, v->validated_blocks); 644 continue; 645#if defined(CONFIG_DM_VERITY_FEC) 646 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 647 cur_block, NULL, &start) == 0) { 648 continue; 649#endif 650 } else { 651 if (bio->bi_status) { 652 /* 653 * Error correction failed; Just return error 654 */ 655 return -EIO; 656 } 657 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 658 cur_block)) { 659 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", 660 bio, cur_block, 0); 661 return -EIO; 662 } 663 } 664 } 665 666 return 0; 667} 668 669/* 670 * Skip verity work in response to I/O error when system is shutting down. 671 */ 672static inline bool verity_is_system_shutting_down(void) 673{ 674 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 675 || system_state == SYSTEM_RESTART; 676} 677 678/* 679 * End one "io" structure with a given error. 680 */ 681static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 682{ 683 struct dm_verity *v = io->v; 684 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 685 686 bio->bi_end_io = io->orig_bi_end_io; 687 bio->bi_status = status; 688 689 if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet) 690 verity_fec_finish_io(io); 691 692 bio_endio(bio); 693} 694 695static void verity_work(struct work_struct *w) 696{ 697 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 698 699 io->in_tasklet = false; 700 701 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 702} 703 704static void verity_end_io(struct bio *bio) 705{ 706 struct dm_verity_io *io = bio->bi_private; 707 708 if (bio->bi_status && 709 (!verity_fec_is_enabled(io->v) || 710 verity_is_system_shutting_down() || 711 (bio->bi_opf & REQ_RAHEAD))) { 712 verity_finish_io(io, bio->bi_status); 713 return; 714 } 715 716 INIT_WORK(&io->work, verity_work); 717 queue_work(io->v->verify_wq, &io->work); 718} 719 720/* 721 * Prefetch buffers for the specified io. 722 * The root buffer is not prefetched, it is assumed that it will be cached 723 * all the time. 724 */ 725static void verity_prefetch_io(struct work_struct *work) 726{ 727 struct dm_verity_prefetch_work *pw = 728 container_of(work, struct dm_verity_prefetch_work, work); 729 struct dm_verity *v = pw->v; 730 int i; 731 732 for (i = v->levels - 2; i >= 0; i--) { 733 sector_t hash_block_start; 734 sector_t hash_block_end; 735 736 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 737 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 738 739 if (!i) { 740 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 741 742 cluster >>= v->data_dev_block_bits; 743 if (unlikely(!cluster)) 744 goto no_prefetch_cluster; 745 746 if (unlikely(cluster & (cluster - 1))) 747 cluster = 1 << __fls(cluster); 748 749 hash_block_start &= ~(sector_t)(cluster - 1); 750 hash_block_end |= cluster - 1; 751 if (unlikely(hash_block_end >= v->hash_blocks)) 752 hash_block_end = v->hash_blocks - 1; 753 } 754no_prefetch_cluster: 755 dm_bufio_prefetch(v->bufio, hash_block_start, 756 hash_block_end - hash_block_start + 1); 757 } 758 759 kfree(pw); 760} 761 762static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 763{ 764 sector_t block = io->block; 765 unsigned int n_blocks = io->n_blocks; 766 struct dm_verity_prefetch_work *pw; 767 768 if (v->validated_blocks) { 769 while (n_blocks && test_bit(block, v->validated_blocks)) { 770 block++; 771 n_blocks--; 772 } 773 while (n_blocks && test_bit(block + n_blocks - 1, 774 v->validated_blocks)) 775 n_blocks--; 776 if (!n_blocks) 777 return; 778 } 779 780 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 781 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 782 783 if (!pw) 784 return; 785 786 INIT_WORK(&pw->work, verity_prefetch_io); 787 pw->v = v; 788 pw->block = block; 789 pw->n_blocks = n_blocks; 790 queue_work(v->verify_wq, &pw->work); 791} 792 793/* 794 * Bio map function. It allocates dm_verity_io structure and bio vector and 795 * fills them. Then it issues prefetches and the I/O. 796 */ 797static int verity_map(struct dm_target *ti, struct bio *bio) 798{ 799 struct dm_verity *v = ti->private; 800 struct dm_verity_io *io; 801 802 bio_set_dev(bio, v->data_dev->bdev); 803 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 804 805 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 806 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 807 DMERR_LIMIT("unaligned io"); 808 return DM_MAPIO_KILL; 809 } 810 811 if (bio_end_sector(bio) >> 812 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 813 DMERR_LIMIT("io out of range"); 814 return DM_MAPIO_KILL; 815 } 816 817 if (bio_data_dir(bio) == WRITE) 818 return DM_MAPIO_KILL; 819 820 io = dm_per_bio_data(bio, ti->per_io_data_size); 821 io->v = v; 822 io->orig_bi_end_io = bio->bi_end_io; 823 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 824 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 825 826 bio->bi_end_io = verity_end_io; 827 bio->bi_private = io; 828 io->iter = bio->bi_iter; 829 830 verity_fec_init_io(io); 831 832 verity_submit_prefetch(v, io); 833 834 submit_bio_noacct(bio); 835 836 return DM_MAPIO_SUBMITTED; 837} 838 839/* 840 * Status: V (valid) or C (corruption found) 841 */ 842static void verity_status(struct dm_target *ti, status_type_t type, 843 unsigned int status_flags, char *result, unsigned int maxlen) 844{ 845 struct dm_verity *v = ti->private; 846 unsigned int args = 0; 847 unsigned int sz = 0; 848 unsigned int x; 849 850 switch (type) { 851 case STATUSTYPE_INFO: 852 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 853 break; 854 case STATUSTYPE_TABLE: 855 DMEMIT("%u %s %s %u %u %llu %llu %s ", 856 v->version, 857 v->data_dev->name, 858 v->hash_dev->name, 859 1 << v->data_dev_block_bits, 860 1 << v->hash_dev_block_bits, 861 (unsigned long long)v->data_blocks, 862 (unsigned long long)v->hash_start, 863 v->alg_name 864 ); 865 for (x = 0; x < v->digest_size; x++) 866 DMEMIT("%02x", v->root_digest[x]); 867 DMEMIT(" "); 868 if (!v->salt_size) 869 DMEMIT("-"); 870 else 871 for (x = 0; x < v->salt_size; x++) 872 DMEMIT("%02x", v->salt[x]); 873 if (v->mode != DM_VERITY_MODE_EIO) 874 args++; 875 if (verity_fec_is_enabled(v)) 876 args += DM_VERITY_OPTS_FEC; 877 if (v->zero_digest) 878 args++; 879 if (v->validated_blocks) 880 args++; 881 if (v->use_tasklet) 882 args++; 883 if (v->signature_key_desc) 884 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 885 if (!args) 886 return; 887 DMEMIT(" %u", args); 888 if (v->mode != DM_VERITY_MODE_EIO) { 889 DMEMIT(" "); 890 switch (v->mode) { 891 case DM_VERITY_MODE_LOGGING: 892 DMEMIT(DM_VERITY_OPT_LOGGING); 893 break; 894 case DM_VERITY_MODE_RESTART: 895 DMEMIT(DM_VERITY_OPT_RESTART); 896 break; 897 case DM_VERITY_MODE_PANIC: 898 DMEMIT(DM_VERITY_OPT_PANIC); 899 break; 900 default: 901 BUG(); 902 } 903 } 904 if (v->zero_digest) 905 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 906 if (v->validated_blocks) 907 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 908 if (v->use_tasklet) 909 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 910 sz = verity_fec_status_table(v, sz, result, maxlen); 911 if (v->signature_key_desc) 912 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 913 " %s", v->signature_key_desc); 914 break; 915 916 case STATUSTYPE_IMA: 917 DMEMIT_TARGET_NAME_VERSION(ti->type); 918 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 919 DMEMIT(",verity_version=%u", v->version); 920 DMEMIT(",data_device_name=%s", v->data_dev->name); 921 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 922 DMEMIT(",verity_algorithm=%s", v->alg_name); 923 924 DMEMIT(",root_digest="); 925 for (x = 0; x < v->digest_size; x++) 926 DMEMIT("%02x", v->root_digest[x]); 927 928 DMEMIT(",salt="); 929 if (!v->salt_size) 930 DMEMIT("-"); 931 else 932 for (x = 0; x < v->salt_size; x++) 933 DMEMIT("%02x", v->salt[x]); 934 935 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 936 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 937 if (v->signature_key_desc) 938 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 939 940 if (v->mode != DM_VERITY_MODE_EIO) { 941 DMEMIT(",verity_mode="); 942 switch (v->mode) { 943 case DM_VERITY_MODE_LOGGING: 944 DMEMIT(DM_VERITY_OPT_LOGGING); 945 break; 946 case DM_VERITY_MODE_RESTART: 947 DMEMIT(DM_VERITY_OPT_RESTART); 948 break; 949 case DM_VERITY_MODE_PANIC: 950 DMEMIT(DM_VERITY_OPT_PANIC); 951 break; 952 default: 953 DMEMIT("invalid"); 954 } 955 } 956 DMEMIT(";"); 957 break; 958 } 959} 960 961static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 962{ 963 struct dm_verity *v = ti->private; 964 965 *bdev = v->data_dev->bdev; 966 967 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 968 return 1; 969 return 0; 970} 971 972static int verity_iterate_devices(struct dm_target *ti, 973 iterate_devices_callout_fn fn, void *data) 974{ 975 struct dm_verity *v = ti->private; 976 977 return fn(ti, v->data_dev, v->data_start, ti->len, data); 978} 979 980static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 981{ 982 struct dm_verity *v = ti->private; 983 984 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 985 limits->logical_block_size = 1 << v->data_dev_block_bits; 986 987 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 988 limits->physical_block_size = 1 << v->data_dev_block_bits; 989 990 blk_limits_io_min(limits, limits->logical_block_size); 991} 992 993static void verity_dtr(struct dm_target *ti) 994{ 995 struct dm_verity *v = ti->private; 996 997 if (v->verify_wq) 998 destroy_workqueue(v->verify_wq); 999 1000 mempool_exit(&v->recheck_pool); 1001 if (v->io) 1002 dm_io_client_destroy(v->io); 1003 1004 if (v->bufio) 1005 dm_bufio_client_destroy(v->bufio); 1006 1007 kvfree(v->validated_blocks); 1008 kfree(v->salt); 1009 kfree(v->root_digest); 1010 kfree(v->zero_digest); 1011 1012 if (v->tfm) 1013 crypto_free_ahash(v->tfm); 1014 1015 kfree(v->alg_name); 1016 1017 if (v->hash_dev) 1018 dm_put_device(ti, v->hash_dev); 1019 1020 if (v->data_dev) 1021 dm_put_device(ti, v->data_dev); 1022 1023 verity_fec_dtr(v); 1024 1025 kfree(v->signature_key_desc); 1026 1027 if (v->use_tasklet) 1028 static_branch_dec(&use_tasklet_enabled); 1029 1030 kfree(v); 1031 1032 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 1033} 1034 1035static int verity_alloc_most_once(struct dm_verity *v) 1036{ 1037 struct dm_target *ti = v->ti; 1038 1039 /* the bitset can only handle INT_MAX blocks */ 1040 if (v->data_blocks > INT_MAX) { 1041 ti->error = "device too large to use check_at_most_once"; 1042 return -E2BIG; 1043 } 1044 1045 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 1046 sizeof(unsigned long), 1047 GFP_KERNEL); 1048 if (!v->validated_blocks) { 1049 ti->error = "failed to allocate bitset for check_at_most_once"; 1050 return -ENOMEM; 1051 } 1052 1053 return 0; 1054} 1055 1056static int verity_alloc_zero_digest(struct dm_verity *v) 1057{ 1058 int r = -ENOMEM; 1059 struct ahash_request *req; 1060 u8 *zero_data; 1061 1062 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1063 1064 if (!v->zero_digest) 1065 return r; 1066 1067 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 1068 1069 if (!req) 1070 return r; /* verity_dtr will free zero_digest */ 1071 1072 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1073 1074 if (!zero_data) 1075 goto out; 1076 1077 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 1078 v->zero_digest, true); 1079 1080out: 1081 kfree(req); 1082 kfree(zero_data); 1083 1084 return r; 1085} 1086 1087static inline bool verity_is_verity_mode(const char *arg_name) 1088{ 1089 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1090 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1091 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1092} 1093 1094static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1095{ 1096 if (v->mode) 1097 return -EINVAL; 1098 1099 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1100 v->mode = DM_VERITY_MODE_LOGGING; 1101 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1102 v->mode = DM_VERITY_MODE_RESTART; 1103 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1104 v->mode = DM_VERITY_MODE_PANIC; 1105 1106 return 0; 1107} 1108 1109static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1110 struct dm_verity_sig_opts *verify_args, 1111 bool only_modifier_opts) 1112{ 1113 int r = 0; 1114 unsigned int argc; 1115 struct dm_target *ti = v->ti; 1116 const char *arg_name; 1117 1118 static const struct dm_arg _args[] = { 1119 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1120 }; 1121 1122 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1123 if (r) 1124 return -EINVAL; 1125 1126 if (!argc) 1127 return 0; 1128 1129 do { 1130 arg_name = dm_shift_arg(as); 1131 argc--; 1132 1133 if (verity_is_verity_mode(arg_name)) { 1134 if (only_modifier_opts) 1135 continue; 1136 r = verity_parse_verity_mode(v, arg_name); 1137 if (r) { 1138 ti->error = "Conflicting error handling parameters"; 1139 return r; 1140 } 1141 continue; 1142 1143 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1144 if (only_modifier_opts) 1145 continue; 1146 r = verity_alloc_zero_digest(v); 1147 if (r) { 1148 ti->error = "Cannot allocate zero digest"; 1149 return r; 1150 } 1151 continue; 1152 1153 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1154 if (only_modifier_opts) 1155 continue; 1156 r = verity_alloc_most_once(v); 1157 if (r) 1158 return r; 1159 continue; 1160 1161 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1162 v->use_tasklet = true; 1163 static_branch_inc(&use_tasklet_enabled); 1164 continue; 1165 1166 } else if (verity_is_fec_opt_arg(arg_name)) { 1167 if (only_modifier_opts) 1168 continue; 1169 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1170 if (r) 1171 return r; 1172 continue; 1173 1174 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1175 if (only_modifier_opts) 1176 continue; 1177 r = verity_verify_sig_parse_opt_args(as, v, 1178 verify_args, 1179 &argc, arg_name); 1180 if (r) 1181 return r; 1182 continue; 1183 1184 } else if (only_modifier_opts) { 1185 /* 1186 * Ignore unrecognized opt, could easily be an extra 1187 * argument to an option whose parsing was skipped. 1188 * Normal parsing (@only_modifier_opts=false) will 1189 * properly parse all options (and their extra args). 1190 */ 1191 continue; 1192 } 1193 1194 DMERR("Unrecognized verity feature request: %s", arg_name); 1195 ti->error = "Unrecognized verity feature request"; 1196 return -EINVAL; 1197 } while (argc && !r); 1198 1199 return r; 1200} 1201 1202/* 1203 * Target parameters: 1204 * <version> The current format is version 1. 1205 * Vsn 0 is compatible with original Chromium OS releases. 1206 * <data device> 1207 * <hash device> 1208 * <data block size> 1209 * <hash block size> 1210 * <the number of data blocks> 1211 * <hash start block> 1212 * <algorithm> 1213 * <digest> 1214 * <salt> Hex string or "-" if no salt. 1215 */ 1216static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1217{ 1218 struct dm_verity *v; 1219 struct dm_verity_sig_opts verify_args = {0}; 1220 struct dm_arg_set as; 1221 unsigned int num; 1222 unsigned long long num_ll; 1223 int r; 1224 int i; 1225 sector_t hash_position; 1226 char dummy; 1227 char *root_hash_digest_to_validate; 1228 1229 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1230 if (!v) { 1231 ti->error = "Cannot allocate verity structure"; 1232 return -ENOMEM; 1233 } 1234 ti->private = v; 1235 v->ti = ti; 1236 1237 r = verity_fec_ctr_alloc(v); 1238 if (r) 1239 goto bad; 1240 1241 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1242 ti->error = "Device must be readonly"; 1243 r = -EINVAL; 1244 goto bad; 1245 } 1246 1247 if (argc < 10) { 1248 ti->error = "Not enough arguments"; 1249 r = -EINVAL; 1250 goto bad; 1251 } 1252 1253 /* Parse optional parameters that modify primary args */ 1254 if (argc > 10) { 1255 as.argc = argc - 10; 1256 as.argv = argv + 10; 1257 r = verity_parse_opt_args(&as, v, &verify_args, true); 1258 if (r < 0) 1259 goto bad; 1260 } 1261 1262 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1263 num > 1) { 1264 ti->error = "Invalid version"; 1265 r = -EINVAL; 1266 goto bad; 1267 } 1268 v->version = num; 1269 1270 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1271 if (r) { 1272 ti->error = "Data device lookup failed"; 1273 goto bad; 1274 } 1275 1276 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1277 if (r) { 1278 ti->error = "Hash device lookup failed"; 1279 goto bad; 1280 } 1281 1282 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1283 !num || (num & (num - 1)) || 1284 num < bdev_logical_block_size(v->data_dev->bdev) || 1285 num > PAGE_SIZE) { 1286 ti->error = "Invalid data device block size"; 1287 r = -EINVAL; 1288 goto bad; 1289 } 1290 v->data_dev_block_bits = __ffs(num); 1291 1292 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1293 !num || (num & (num - 1)) || 1294 num < bdev_logical_block_size(v->hash_dev->bdev) || 1295 num > INT_MAX) { 1296 ti->error = "Invalid hash device block size"; 1297 r = -EINVAL; 1298 goto bad; 1299 } 1300 v->hash_dev_block_bits = __ffs(num); 1301 1302 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1303 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1304 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1305 ti->error = "Invalid data blocks"; 1306 r = -EINVAL; 1307 goto bad; 1308 } 1309 v->data_blocks = num_ll; 1310 1311 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1312 ti->error = "Data device is too small"; 1313 r = -EINVAL; 1314 goto bad; 1315 } 1316 1317 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1318 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1319 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1320 ti->error = "Invalid hash start"; 1321 r = -EINVAL; 1322 goto bad; 1323 } 1324 v->hash_start = num_ll; 1325 1326 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1327 if (!v->alg_name) { 1328 ti->error = "Cannot allocate algorithm name"; 1329 r = -ENOMEM; 1330 goto bad; 1331 } 1332 1333 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 1334 v->use_tasklet ? CRYPTO_ALG_ASYNC : 0); 1335 if (IS_ERR(v->tfm)) { 1336 ti->error = "Cannot initialize hash function"; 1337 r = PTR_ERR(v->tfm); 1338 v->tfm = NULL; 1339 goto bad; 1340 } 1341 1342 /* 1343 * dm-verity performance can vary greatly depending on which hash 1344 * algorithm implementation is used. Help people debug performance 1345 * problems by logging the ->cra_driver_name. 1346 */ 1347 DMINFO("%s using implementation \"%s\"", v->alg_name, 1348 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1349 1350 v->digest_size = crypto_ahash_digestsize(v->tfm); 1351 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1352 ti->error = "Digest size too big"; 1353 r = -EINVAL; 1354 goto bad; 1355 } 1356 v->ahash_reqsize = sizeof(struct ahash_request) + 1357 crypto_ahash_reqsize(v->tfm); 1358 1359 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1360 if (!v->root_digest) { 1361 ti->error = "Cannot allocate root digest"; 1362 r = -ENOMEM; 1363 goto bad; 1364 } 1365 if (strlen(argv[8]) != v->digest_size * 2 || 1366 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1367 ti->error = "Invalid root digest"; 1368 r = -EINVAL; 1369 goto bad; 1370 } 1371 root_hash_digest_to_validate = argv[8]; 1372 1373 if (strcmp(argv[9], "-")) { 1374 v->salt_size = strlen(argv[9]) / 2; 1375 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1376 if (!v->salt) { 1377 ti->error = "Cannot allocate salt"; 1378 r = -ENOMEM; 1379 goto bad; 1380 } 1381 if (strlen(argv[9]) != v->salt_size * 2 || 1382 hex2bin(v->salt, argv[9], v->salt_size)) { 1383 ti->error = "Invalid salt"; 1384 r = -EINVAL; 1385 goto bad; 1386 } 1387 } 1388 1389 argv += 10; 1390 argc -= 10; 1391 1392 /* Optional parameters */ 1393 if (argc) { 1394 as.argc = argc; 1395 as.argv = argv; 1396 r = verity_parse_opt_args(&as, v, &verify_args, false); 1397 if (r < 0) 1398 goto bad; 1399 } 1400 1401 /* Root hash signature is a optional parameter*/ 1402 r = verity_verify_root_hash(root_hash_digest_to_validate, 1403 strlen(root_hash_digest_to_validate), 1404 verify_args.sig, 1405 verify_args.sig_size); 1406 if (r < 0) { 1407 ti->error = "Root hash verification failed"; 1408 goto bad; 1409 } 1410 v->hash_per_block_bits = 1411 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1412 1413 v->levels = 0; 1414 if (v->data_blocks) 1415 while (v->hash_per_block_bits * v->levels < 64 && 1416 (unsigned long long)(v->data_blocks - 1) >> 1417 (v->hash_per_block_bits * v->levels)) 1418 v->levels++; 1419 1420 if (v->levels > DM_VERITY_MAX_LEVELS) { 1421 ti->error = "Too many tree levels"; 1422 r = -E2BIG; 1423 goto bad; 1424 } 1425 1426 hash_position = v->hash_start; 1427 for (i = v->levels - 1; i >= 0; i--) { 1428 sector_t s; 1429 1430 v->hash_level_block[i] = hash_position; 1431 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1432 >> ((i + 1) * v->hash_per_block_bits); 1433 if (hash_position + s < hash_position) { 1434 ti->error = "Hash device offset overflow"; 1435 r = -E2BIG; 1436 goto bad; 1437 } 1438 hash_position += s; 1439 } 1440 v->hash_blocks = hash_position; 1441 1442 r = mempool_init_page_pool(&v->recheck_pool, 1, 0); 1443 if (unlikely(r)) { 1444 ti->error = "Cannot allocate mempool"; 1445 goto bad; 1446 } 1447 1448 v->io = dm_io_client_create(); 1449 if (IS_ERR(v->io)) { 1450 r = PTR_ERR(v->io); 1451 v->io = NULL; 1452 ti->error = "Cannot allocate dm io"; 1453 goto bad; 1454 } 1455 1456 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1457 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1458 dm_bufio_alloc_callback, NULL, 1459 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1460 if (IS_ERR(v->bufio)) { 1461 ti->error = "Cannot initialize dm-bufio"; 1462 r = PTR_ERR(v->bufio); 1463 v->bufio = NULL; 1464 goto bad; 1465 } 1466 1467 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1468 ti->error = "Hash device is too small"; 1469 r = -E2BIG; 1470 goto bad; 1471 } 1472 1473 /* 1474 * Using WQ_HIGHPRI improves throughput and completion latency by 1475 * reducing wait times when reading from a dm-verity device. 1476 * 1477 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1478 * allows verify_wq to preempt softirq since verification in tasklet 1479 * will fall-back to using it for error handling (or if the bufio cache 1480 * doesn't have required hashes). 1481 */ 1482 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1483 if (!v->verify_wq) { 1484 ti->error = "Cannot allocate workqueue"; 1485 r = -ENOMEM; 1486 goto bad; 1487 } 1488 1489 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1490 v->ahash_reqsize + v->digest_size * 2; 1491 1492 r = verity_fec_ctr(v); 1493 if (r) 1494 goto bad; 1495 1496 ti->per_io_data_size = roundup(ti->per_io_data_size, 1497 __alignof__(struct dm_verity_io)); 1498 1499 verity_verify_sig_opts_cleanup(&verify_args); 1500 1501 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1502 1503 return 0; 1504 1505bad: 1506 1507 verity_verify_sig_opts_cleanup(&verify_args); 1508 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1509 verity_dtr(ti); 1510 1511 return r; 1512} 1513 1514/* 1515 * Check whether a DM target is a verity target. 1516 */ 1517bool dm_is_verity_target(struct dm_target *ti) 1518{ 1519 return ti->type->module == THIS_MODULE; 1520} 1521 1522/* 1523 * Get the verity mode (error behavior) of a verity target. 1524 * 1525 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1526 * target. 1527 */ 1528int dm_verity_get_mode(struct dm_target *ti) 1529{ 1530 struct dm_verity *v = ti->private; 1531 1532 if (!dm_is_verity_target(ti)) 1533 return -EINVAL; 1534 1535 return v->mode; 1536} 1537 1538/* 1539 * Get the root digest of a verity target. 1540 * 1541 * Returns a copy of the root digest, the caller is responsible for 1542 * freeing the memory of the digest. 1543 */ 1544int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1545{ 1546 struct dm_verity *v = ti->private; 1547 1548 if (!dm_is_verity_target(ti)) 1549 return -EINVAL; 1550 1551 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1552 if (*root_digest == NULL) 1553 return -ENOMEM; 1554 1555 *digest_size = v->digest_size; 1556 1557 return 0; 1558} 1559 1560static struct target_type verity_target = { 1561 .name = "verity", 1562 .features = DM_TARGET_IMMUTABLE, 1563 .version = {1, 9, 0}, 1564 .module = THIS_MODULE, 1565 .ctr = verity_ctr, 1566 .dtr = verity_dtr, 1567 .map = verity_map, 1568 .status = verity_status, 1569 .prepare_ioctl = verity_prepare_ioctl, 1570 .iterate_devices = verity_iterate_devices, 1571 .io_hints = verity_io_hints, 1572}; 1573module_dm(verity); 1574 1575MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1576MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1577MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1578MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1579MODULE_LICENSE("GPL"); 1580