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_bh_wq_enabled); 50 51struct dm_verity_prefetch_work { 52 struct work_struct work; 53 struct dm_verity *v; 54 unsigned short ioprio; 55 sector_t block; 56 unsigned int n_blocks; 57}; 58 59/* 60 * Auxiliary structure appended to each dm-bufio buffer. If the value 61 * hash_verified is nonzero, hash of the block has been verified. 62 * 63 * The variable hash_verified is set to 0 when allocating the buffer, then 64 * it can be changed to 1 and it is never reset to 0 again. 65 * 66 * There is no lock around this value, a race condition can at worst cause 67 * that multiple processes verify the hash of the same buffer simultaneously 68 * and write 1 to hash_verified simultaneously. 69 * This condition is harmless, so we don't need locking. 70 */ 71struct buffer_aux { 72 int hash_verified; 73}; 74 75/* 76 * Initialize struct buffer_aux for a freshly created buffer. 77 */ 78static void dm_bufio_alloc_callback(struct dm_buffer *buf) 79{ 80 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 81 82 aux->hash_verified = 0; 83} 84 85/* 86 * Translate input sector number to the sector number on the target device. 87 */ 88static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 89{ 90 return v->data_start + dm_target_offset(v->ti, bi_sector); 91} 92 93/* 94 * Return hash position of a specified block at a specified tree level 95 * (0 is the lowest level). 96 * The lowest "hash_per_block_bits"-bits of the result denote hash position 97 * inside a hash block. The remaining bits denote location of the hash block. 98 */ 99static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 100 int level) 101{ 102 return block >> (level * v->hash_per_block_bits); 103} 104 105static int verity_hash_update(struct dm_verity *v, struct ahash_request *req, 106 const u8 *data, size_t len, 107 struct crypto_wait *wait) 108{ 109 struct scatterlist sg; 110 111 if (likely(!is_vmalloc_addr(data))) { 112 sg_init_one(&sg, data, len); 113 ahash_request_set_crypt(req, &sg, NULL, len); 114 return crypto_wait_req(crypto_ahash_update(req), wait); 115 } 116 117 do { 118 int r; 119 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 120 121 flush_kernel_vmap_range((void *)data, this_step); 122 sg_init_table(&sg, 1); 123 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 124 ahash_request_set_crypt(req, &sg, NULL, this_step); 125 r = crypto_wait_req(crypto_ahash_update(req), wait); 126 if (unlikely(r)) 127 return r; 128 data += this_step; 129 len -= this_step; 130 } while (len); 131 132 return 0; 133} 134 135/* 136 * Wrapper for crypto_ahash_init, which handles verity salting. 137 */ 138static int verity_hash_init(struct dm_verity *v, struct ahash_request *req, 139 struct crypto_wait *wait, bool may_sleep) 140{ 141 int r; 142 143 ahash_request_set_tfm(req, v->tfm); 144 ahash_request_set_callback(req, 145 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0, 146 crypto_req_done, (void *)wait); 147 crypto_init_wait(wait); 148 149 r = crypto_wait_req(crypto_ahash_init(req), wait); 150 151 if (unlikely(r < 0)) { 152 if (r != -ENOMEM) 153 DMERR("crypto_ahash_init failed: %d", r); 154 return r; 155 } 156 157 if (likely(v->salt_size && (v->version >= 1))) 158 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 159 160 return r; 161} 162 163static int verity_hash_final(struct dm_verity *v, struct ahash_request *req, 164 u8 *digest, struct crypto_wait *wait) 165{ 166 int r; 167 168 if (unlikely(v->salt_size && (!v->version))) { 169 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 170 171 if (r < 0) { 172 DMERR("%s failed updating salt: %d", __func__, r); 173 goto out; 174 } 175 } 176 177 ahash_request_set_crypt(req, NULL, digest, 0); 178 r = crypto_wait_req(crypto_ahash_final(req), wait); 179out: 180 return r; 181} 182 183int verity_hash(struct dm_verity *v, struct ahash_request *req, 184 const u8 *data, size_t len, u8 *digest, bool may_sleep) 185{ 186 int r; 187 struct crypto_wait wait; 188 189 r = verity_hash_init(v, req, &wait, may_sleep); 190 if (unlikely(r < 0)) 191 goto out; 192 193 r = verity_hash_update(v, req, data, len, &wait); 194 if (unlikely(r < 0)) 195 goto out; 196 197 r = verity_hash_final(v, req, digest, &wait); 198 199out: 200 return r; 201} 202 203static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 204 sector_t *hash_block, unsigned int *offset) 205{ 206 sector_t position = verity_position_at_level(v, block, level); 207 unsigned int idx; 208 209 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 210 211 if (!offset) 212 return; 213 214 idx = position & ((1 << v->hash_per_block_bits) - 1); 215 if (!v->version) 216 *offset = idx * v->digest_size; 217 else 218 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 219} 220 221/* 222 * Handle verification errors. 223 */ 224static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 225 unsigned long long block) 226{ 227 char verity_env[DM_VERITY_ENV_LENGTH]; 228 char *envp[] = { verity_env, NULL }; 229 const char *type_str = ""; 230 struct mapped_device *md = dm_table_get_md(v->ti->table); 231 232 /* Corruption should be visible in device status in all modes */ 233 v->hash_failed = true; 234 235 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 236 goto out; 237 238 v->corrupted_errs++; 239 240 switch (type) { 241 case DM_VERITY_BLOCK_TYPE_DATA: 242 type_str = "data"; 243 break; 244 case DM_VERITY_BLOCK_TYPE_METADATA: 245 type_str = "metadata"; 246 break; 247 default: 248 BUG(); 249 } 250 251 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 252 type_str, block); 253 254 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { 255 DMERR("%s: reached maximum errors", v->data_dev->name); 256 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); 257 } 258 259 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 260 DM_VERITY_ENV_VAR_NAME, type, block); 261 262 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 263 264out: 265 if (v->mode == DM_VERITY_MODE_LOGGING) 266 return 0; 267 268 if (v->mode == DM_VERITY_MODE_RESTART) 269 kernel_restart("dm-verity device corrupted"); 270 271 if (v->mode == DM_VERITY_MODE_PANIC) 272 panic("dm-verity device corrupted"); 273 274 return 1; 275} 276 277/* 278 * Verify hash of a metadata block pertaining to the specified data block 279 * ("block" argument) at a specified level ("level" argument). 280 * 281 * On successful return, verity_io_want_digest(v, io) contains the hash value 282 * for a lower tree level or for the data block (if we're at the lowest level). 283 * 284 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 285 * If "skip_unverified" is false, unverified buffer is hashed and verified 286 * against current value of verity_io_want_digest(v, io). 287 */ 288static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 289 sector_t block, int level, bool skip_unverified, 290 u8 *want_digest) 291{ 292 struct dm_buffer *buf; 293 struct buffer_aux *aux; 294 u8 *data; 295 int r; 296 sector_t hash_block; 297 unsigned int offset; 298 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 299 300 verity_hash_at_level(v, block, level, &hash_block, &offset); 301 302 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 303 data = dm_bufio_get(v->bufio, hash_block, &buf); 304 if (data == NULL) { 305 /* 306 * In tasklet and the hash was not in the bufio cache. 307 * Return early and resume execution from a work-queue 308 * to read the hash from disk. 309 */ 310 return -EAGAIN; 311 } 312 } else { 313 data = dm_bufio_read_with_ioprio(v->bufio, hash_block, 314 &buf, bio_prio(bio)); 315 } 316 317 if (IS_ERR(data)) 318 return PTR_ERR(data); 319 320 aux = dm_bufio_get_aux_data(buf); 321 322 if (!aux->hash_verified) { 323 if (skip_unverified) { 324 r = 1; 325 goto release_ret_r; 326 } 327 328 r = verity_hash(v, verity_io_hash_req(v, io), 329 data, 1 << v->hash_dev_block_bits, 330 verity_io_real_digest(v, io), !io->in_bh); 331 if (unlikely(r < 0)) 332 goto release_ret_r; 333 334 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 335 v->digest_size) == 0)) 336 aux->hash_verified = 1; 337 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 338 /* 339 * Error handling code (FEC included) cannot be run in a 340 * tasklet since it may sleep, so fallback to work-queue. 341 */ 342 r = -EAGAIN; 343 goto release_ret_r; 344 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 345 hash_block, data, NULL) == 0) 346 aux->hash_verified = 1; 347 else if (verity_handle_err(v, 348 DM_VERITY_BLOCK_TYPE_METADATA, 349 hash_block)) { 350 struct bio *bio = 351 dm_bio_from_per_bio_data(io, 352 v->ti->per_io_data_size); 353 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, 354 block, 0); 355 r = -EIO; 356 goto release_ret_r; 357 } 358 } 359 360 data += offset; 361 memcpy(want_digest, data, v->digest_size); 362 r = 0; 363 364release_ret_r: 365 dm_bufio_release(buf); 366 return r; 367} 368 369/* 370 * Find a hash for a given block, write it to digest and verify the integrity 371 * of the hash tree if necessary. 372 */ 373int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 374 sector_t block, u8 *digest, bool *is_zero) 375{ 376 int r = 0, i; 377 378 if (likely(v->levels)) { 379 /* 380 * First, we try to get the requested hash for 381 * the current block. If the hash block itself is 382 * verified, zero is returned. If it isn't, this 383 * function returns 1 and we fall back to whole 384 * chain verification. 385 */ 386 r = verity_verify_level(v, io, block, 0, true, digest); 387 if (likely(r <= 0)) 388 goto out; 389 } 390 391 memcpy(digest, v->root_digest, v->digest_size); 392 393 for (i = v->levels - 1; i >= 0; i--) { 394 r = verity_verify_level(v, io, block, i, false, digest); 395 if (unlikely(r)) 396 goto out; 397 } 398out: 399 if (!r && v->zero_digest) 400 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 401 else 402 *is_zero = false; 403 404 return r; 405} 406 407/* 408 * Calculates the digest for the given bio 409 */ 410static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, 411 struct bvec_iter *iter, struct crypto_wait *wait) 412{ 413 unsigned int todo = 1 << v->data_dev_block_bits; 414 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 415 struct scatterlist sg; 416 struct ahash_request *req = verity_io_hash_req(v, io); 417 418 do { 419 int r; 420 unsigned int len; 421 struct bio_vec bv = bio_iter_iovec(bio, *iter); 422 423 sg_init_table(&sg, 1); 424 425 len = bv.bv_len; 426 427 if (likely(len >= todo)) 428 len = todo; 429 /* 430 * Operating on a single page at a time looks suboptimal 431 * until you consider the typical block size is 4,096B. 432 * Going through this loops twice should be very rare. 433 */ 434 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset); 435 ahash_request_set_crypt(req, &sg, NULL, len); 436 r = crypto_wait_req(crypto_ahash_update(req), wait); 437 438 if (unlikely(r < 0)) { 439 DMERR("%s crypto op failed: %d", __func__, r); 440 return r; 441 } 442 443 bio_advance_iter(bio, iter, len); 444 todo -= len; 445 } while (todo); 446 447 return 0; 448} 449 450/* 451 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 452 * starting from iter. 453 */ 454int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 455 struct bvec_iter *iter, 456 int (*process)(struct dm_verity *v, 457 struct dm_verity_io *io, u8 *data, 458 size_t len)) 459{ 460 unsigned int todo = 1 << v->data_dev_block_bits; 461 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 462 463 do { 464 int r; 465 u8 *page; 466 unsigned int len; 467 struct bio_vec bv = bio_iter_iovec(bio, *iter); 468 469 page = bvec_kmap_local(&bv); 470 len = bv.bv_len; 471 472 if (likely(len >= todo)) 473 len = todo; 474 475 r = process(v, io, page, len); 476 kunmap_local(page); 477 478 if (r < 0) 479 return r; 480 481 bio_advance_iter(bio, iter, len); 482 todo -= len; 483 } while (todo); 484 485 return 0; 486} 487 488static int verity_recheck_copy(struct dm_verity *v, struct dm_verity_io *io, 489 u8 *data, size_t len) 490{ 491 memcpy(data, io->recheck_buffer, len); 492 io->recheck_buffer += len; 493 494 return 0; 495} 496 497static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io, 498 struct bvec_iter start, sector_t cur_block) 499{ 500 struct page *page; 501 void *buffer; 502 int r; 503 struct dm_io_request io_req; 504 struct dm_io_region io_loc; 505 506 page = mempool_alloc(&v->recheck_pool, GFP_NOIO); 507 buffer = page_to_virt(page); 508 509 io_req.bi_opf = REQ_OP_READ; 510 io_req.mem.type = DM_IO_KMEM; 511 io_req.mem.ptr.addr = buffer; 512 io_req.notify.fn = NULL; 513 io_req.client = v->io; 514 io_loc.bdev = v->data_dev->bdev; 515 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT); 516 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT); 517 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT); 518 if (unlikely(r)) 519 goto free_ret; 520 521 r = verity_hash(v, verity_io_hash_req(v, io), buffer, 522 1 << v->data_dev_block_bits, 523 verity_io_real_digest(v, io), true); 524 if (unlikely(r)) 525 goto free_ret; 526 527 if (memcmp(verity_io_real_digest(v, io), 528 verity_io_want_digest(v, io), v->digest_size)) { 529 r = -EIO; 530 goto free_ret; 531 } 532 533 io->recheck_buffer = buffer; 534 r = verity_for_bv_block(v, io, &start, verity_recheck_copy); 535 if (unlikely(r)) 536 goto free_ret; 537 538 r = 0; 539free_ret: 540 mempool_free(page, &v->recheck_pool); 541 542 return r; 543} 544 545static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 546 u8 *data, size_t len) 547{ 548 memset(data, 0, len); 549 return 0; 550} 551 552/* 553 * Moves the bio iter one data block forward. 554 */ 555static inline void verity_bv_skip_block(struct dm_verity *v, 556 struct dm_verity_io *io, 557 struct bvec_iter *iter) 558{ 559 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 560 561 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits); 562} 563 564/* 565 * Verify one "dm_verity_io" structure. 566 */ 567static int verity_verify_io(struct dm_verity_io *io) 568{ 569 bool is_zero; 570 struct dm_verity *v = io->v; 571 struct bvec_iter start; 572 struct bvec_iter iter_copy; 573 struct bvec_iter *iter; 574 struct crypto_wait wait; 575 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 576 unsigned int b; 577 578 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 579 /* 580 * Copy the iterator in case we need to restart 581 * verification in a work-queue. 582 */ 583 iter_copy = io->iter; 584 iter = &iter_copy; 585 } else 586 iter = &io->iter; 587 588 for (b = 0; b < io->n_blocks; b++) { 589 int r; 590 sector_t cur_block = io->block + b; 591 struct ahash_request *req = verity_io_hash_req(v, io); 592 593 if (v->validated_blocks && bio->bi_status == BLK_STS_OK && 594 likely(test_bit(cur_block, v->validated_blocks))) { 595 verity_bv_skip_block(v, io, iter); 596 continue; 597 } 598 599 r = verity_hash_for_block(v, io, cur_block, 600 verity_io_want_digest(v, io), 601 &is_zero); 602 if (unlikely(r < 0)) 603 return r; 604 605 if (is_zero) { 606 /* 607 * If we expect a zero block, don't validate, just 608 * return zeros. 609 */ 610 r = verity_for_bv_block(v, io, iter, 611 verity_bv_zero); 612 if (unlikely(r < 0)) 613 return r; 614 615 continue; 616 } 617 618 r = verity_hash_init(v, req, &wait, !io->in_bh); 619 if (unlikely(r < 0)) 620 return r; 621 622 start = *iter; 623 r = verity_for_io_block(v, io, iter, &wait); 624 if (unlikely(r < 0)) 625 return r; 626 627 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 628 &wait); 629 if (unlikely(r < 0)) 630 return r; 631 632 if (likely(memcmp(verity_io_real_digest(v, io), 633 verity_io_want_digest(v, io), v->digest_size) == 0)) { 634 if (v->validated_blocks) 635 set_bit(cur_block, v->validated_blocks); 636 continue; 637 } else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 638 /* 639 * Error handling code (FEC included) cannot be run in a 640 * tasklet since it may sleep, so fallback to work-queue. 641 */ 642 return -EAGAIN; 643 } else if (verity_recheck(v, io, start, cur_block) == 0) { 644 if (v->validated_blocks) 645 set_bit(cur_block, v->validated_blocks); 646 continue; 647#if defined(CONFIG_DM_VERITY_FEC) 648 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 649 cur_block, NULL, &start) == 0) { 650 continue; 651#endif 652 } else { 653 if (bio->bi_status) { 654 /* 655 * Error correction failed; Just return error 656 */ 657 return -EIO; 658 } 659 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 660 cur_block)) { 661 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", 662 bio, cur_block, 0); 663 return -EIO; 664 } 665 } 666 } 667 668 return 0; 669} 670 671/* 672 * Skip verity work in response to I/O error when system is shutting down. 673 */ 674static inline bool verity_is_system_shutting_down(void) 675{ 676 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 677 || system_state == SYSTEM_RESTART; 678} 679 680/* 681 * End one "io" structure with a given error. 682 */ 683static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 684{ 685 struct dm_verity *v = io->v; 686 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 687 688 bio->bi_end_io = io->orig_bi_end_io; 689 bio->bi_status = status; 690 691 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh) 692 verity_fec_finish_io(io); 693 694 bio_endio(bio); 695} 696 697static void verity_work(struct work_struct *w) 698{ 699 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 700 701 io->in_bh = false; 702 703 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 704} 705 706static void verity_bh_work(struct work_struct *w) 707{ 708 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work); 709 int err; 710 711 io->in_bh = true; 712 err = verity_verify_io(io); 713 if (err == -EAGAIN || err == -ENOMEM) { 714 /* fallback to retrying with work-queue */ 715 INIT_WORK(&io->work, verity_work); 716 queue_work(io->v->verify_wq, &io->work); 717 return; 718 } 719 720 verity_finish_io(io, errno_to_blk_status(err)); 721} 722 723static void verity_end_io(struct bio *bio) 724{ 725 struct dm_verity_io *io = bio->bi_private; 726 727 if (bio->bi_status && 728 (!verity_fec_is_enabled(io->v) || 729 verity_is_system_shutting_down() || 730 (bio->bi_opf & REQ_RAHEAD))) { 731 verity_finish_io(io, bio->bi_status); 732 return; 733 } 734 735 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) { 736 INIT_WORK(&io->bh_work, verity_bh_work); 737 queue_work(system_bh_wq, &io->bh_work); 738 } else { 739 INIT_WORK(&io->work, verity_work); 740 queue_work(io->v->verify_wq, &io->work); 741 } 742} 743 744/* 745 * Prefetch buffers for the specified io. 746 * The root buffer is not prefetched, it is assumed that it will be cached 747 * all the time. 748 */ 749static void verity_prefetch_io(struct work_struct *work) 750{ 751 struct dm_verity_prefetch_work *pw = 752 container_of(work, struct dm_verity_prefetch_work, work); 753 struct dm_verity *v = pw->v; 754 int i; 755 756 for (i = v->levels - 2; i >= 0; i--) { 757 sector_t hash_block_start; 758 sector_t hash_block_end; 759 760 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 761 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 762 763 if (!i) { 764 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 765 766 cluster >>= v->data_dev_block_bits; 767 if (unlikely(!cluster)) 768 goto no_prefetch_cluster; 769 770 if (unlikely(cluster & (cluster - 1))) 771 cluster = 1 << __fls(cluster); 772 773 hash_block_start &= ~(sector_t)(cluster - 1); 774 hash_block_end |= cluster - 1; 775 if (unlikely(hash_block_end >= v->hash_blocks)) 776 hash_block_end = v->hash_blocks - 1; 777 } 778no_prefetch_cluster: 779 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start, 780 hash_block_end - hash_block_start + 1, 781 pw->ioprio); 782 } 783 784 kfree(pw); 785} 786 787static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io, 788 unsigned short ioprio) 789{ 790 sector_t block = io->block; 791 unsigned int n_blocks = io->n_blocks; 792 struct dm_verity_prefetch_work *pw; 793 794 if (v->validated_blocks) { 795 while (n_blocks && test_bit(block, v->validated_blocks)) { 796 block++; 797 n_blocks--; 798 } 799 while (n_blocks && test_bit(block + n_blocks - 1, 800 v->validated_blocks)) 801 n_blocks--; 802 if (!n_blocks) 803 return; 804 } 805 806 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 807 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 808 809 if (!pw) 810 return; 811 812 INIT_WORK(&pw->work, verity_prefetch_io); 813 pw->v = v; 814 pw->block = block; 815 pw->n_blocks = n_blocks; 816 pw->ioprio = ioprio; 817 queue_work(v->verify_wq, &pw->work); 818} 819 820/* 821 * Bio map function. It allocates dm_verity_io structure and bio vector and 822 * fills them. Then it issues prefetches and the I/O. 823 */ 824static int verity_map(struct dm_target *ti, struct bio *bio) 825{ 826 struct dm_verity *v = ti->private; 827 struct dm_verity_io *io; 828 829 bio_set_dev(bio, v->data_dev->bdev); 830 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 831 832 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 833 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 834 DMERR_LIMIT("unaligned io"); 835 return DM_MAPIO_KILL; 836 } 837 838 if (bio_end_sector(bio) >> 839 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 840 DMERR_LIMIT("io out of range"); 841 return DM_MAPIO_KILL; 842 } 843 844 if (bio_data_dir(bio) == WRITE) 845 return DM_MAPIO_KILL; 846 847 io = dm_per_bio_data(bio, ti->per_io_data_size); 848 io->v = v; 849 io->orig_bi_end_io = bio->bi_end_io; 850 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 851 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 852 853 bio->bi_end_io = verity_end_io; 854 bio->bi_private = io; 855 io->iter = bio->bi_iter; 856 857 verity_fec_init_io(io); 858 859 verity_submit_prefetch(v, io, bio_prio(bio)); 860 861 submit_bio_noacct(bio); 862 863 return DM_MAPIO_SUBMITTED; 864} 865 866/* 867 * Status: V (valid) or C (corruption found) 868 */ 869static void verity_status(struct dm_target *ti, status_type_t type, 870 unsigned int status_flags, char *result, unsigned int maxlen) 871{ 872 struct dm_verity *v = ti->private; 873 unsigned int args = 0; 874 unsigned int sz = 0; 875 unsigned int x; 876 877 switch (type) { 878 case STATUSTYPE_INFO: 879 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 880 break; 881 case STATUSTYPE_TABLE: 882 DMEMIT("%u %s %s %u %u %llu %llu %s ", 883 v->version, 884 v->data_dev->name, 885 v->hash_dev->name, 886 1 << v->data_dev_block_bits, 887 1 << v->hash_dev_block_bits, 888 (unsigned long long)v->data_blocks, 889 (unsigned long long)v->hash_start, 890 v->alg_name 891 ); 892 for (x = 0; x < v->digest_size; x++) 893 DMEMIT("%02x", v->root_digest[x]); 894 DMEMIT(" "); 895 if (!v->salt_size) 896 DMEMIT("-"); 897 else 898 for (x = 0; x < v->salt_size; x++) 899 DMEMIT("%02x", v->salt[x]); 900 if (v->mode != DM_VERITY_MODE_EIO) 901 args++; 902 if (verity_fec_is_enabled(v)) 903 args += DM_VERITY_OPTS_FEC; 904 if (v->zero_digest) 905 args++; 906 if (v->validated_blocks) 907 args++; 908 if (v->use_bh_wq) 909 args++; 910 if (v->signature_key_desc) 911 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 912 if (!args) 913 return; 914 DMEMIT(" %u", args); 915 if (v->mode != DM_VERITY_MODE_EIO) { 916 DMEMIT(" "); 917 switch (v->mode) { 918 case DM_VERITY_MODE_LOGGING: 919 DMEMIT(DM_VERITY_OPT_LOGGING); 920 break; 921 case DM_VERITY_MODE_RESTART: 922 DMEMIT(DM_VERITY_OPT_RESTART); 923 break; 924 case DM_VERITY_MODE_PANIC: 925 DMEMIT(DM_VERITY_OPT_PANIC); 926 break; 927 default: 928 BUG(); 929 } 930 } 931 if (v->zero_digest) 932 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 933 if (v->validated_blocks) 934 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 935 if (v->use_bh_wq) 936 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 937 sz = verity_fec_status_table(v, sz, result, maxlen); 938 if (v->signature_key_desc) 939 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 940 " %s", v->signature_key_desc); 941 break; 942 943 case STATUSTYPE_IMA: 944 DMEMIT_TARGET_NAME_VERSION(ti->type); 945 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 946 DMEMIT(",verity_version=%u", v->version); 947 DMEMIT(",data_device_name=%s", v->data_dev->name); 948 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 949 DMEMIT(",verity_algorithm=%s", v->alg_name); 950 951 DMEMIT(",root_digest="); 952 for (x = 0; x < v->digest_size; x++) 953 DMEMIT("%02x", v->root_digest[x]); 954 955 DMEMIT(",salt="); 956 if (!v->salt_size) 957 DMEMIT("-"); 958 else 959 for (x = 0; x < v->salt_size; x++) 960 DMEMIT("%02x", v->salt[x]); 961 962 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 963 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 964 if (v->signature_key_desc) 965 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 966 967 if (v->mode != DM_VERITY_MODE_EIO) { 968 DMEMIT(",verity_mode="); 969 switch (v->mode) { 970 case DM_VERITY_MODE_LOGGING: 971 DMEMIT(DM_VERITY_OPT_LOGGING); 972 break; 973 case DM_VERITY_MODE_RESTART: 974 DMEMIT(DM_VERITY_OPT_RESTART); 975 break; 976 case DM_VERITY_MODE_PANIC: 977 DMEMIT(DM_VERITY_OPT_PANIC); 978 break; 979 default: 980 DMEMIT("invalid"); 981 } 982 } 983 DMEMIT(";"); 984 break; 985 } 986} 987 988static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 989{ 990 struct dm_verity *v = ti->private; 991 992 *bdev = v->data_dev->bdev; 993 994 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 995 return 1; 996 return 0; 997} 998 999static int verity_iterate_devices(struct dm_target *ti, 1000 iterate_devices_callout_fn fn, void *data) 1001{ 1002 struct dm_verity *v = ti->private; 1003 1004 return fn(ti, v->data_dev, v->data_start, ti->len, data); 1005} 1006 1007static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 1008{ 1009 struct dm_verity *v = ti->private; 1010 1011 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 1012 limits->logical_block_size = 1 << v->data_dev_block_bits; 1013 1014 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 1015 limits->physical_block_size = 1 << v->data_dev_block_bits; 1016 1017 blk_limits_io_min(limits, limits->logical_block_size); 1018} 1019 1020static void verity_dtr(struct dm_target *ti) 1021{ 1022 struct dm_verity *v = ti->private; 1023 1024 if (v->verify_wq) 1025 destroy_workqueue(v->verify_wq); 1026 1027 mempool_exit(&v->recheck_pool); 1028 if (v->io) 1029 dm_io_client_destroy(v->io); 1030 1031 if (v->bufio) 1032 dm_bufio_client_destroy(v->bufio); 1033 1034 kvfree(v->validated_blocks); 1035 kfree(v->salt); 1036 kfree(v->root_digest); 1037 kfree(v->zero_digest); 1038 1039 if (v->tfm) 1040 crypto_free_ahash(v->tfm); 1041 1042 kfree(v->alg_name); 1043 1044 if (v->hash_dev) 1045 dm_put_device(ti, v->hash_dev); 1046 1047 if (v->data_dev) 1048 dm_put_device(ti, v->data_dev); 1049 1050 verity_fec_dtr(v); 1051 1052 kfree(v->signature_key_desc); 1053 1054 if (v->use_bh_wq) 1055 static_branch_dec(&use_bh_wq_enabled); 1056 1057 kfree(v); 1058 1059 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 1060} 1061 1062static int verity_alloc_most_once(struct dm_verity *v) 1063{ 1064 struct dm_target *ti = v->ti; 1065 1066 /* the bitset can only handle INT_MAX blocks */ 1067 if (v->data_blocks > INT_MAX) { 1068 ti->error = "device too large to use check_at_most_once"; 1069 return -E2BIG; 1070 } 1071 1072 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 1073 sizeof(unsigned long), 1074 GFP_KERNEL); 1075 if (!v->validated_blocks) { 1076 ti->error = "failed to allocate bitset for check_at_most_once"; 1077 return -ENOMEM; 1078 } 1079 1080 return 0; 1081} 1082 1083static int verity_alloc_zero_digest(struct dm_verity *v) 1084{ 1085 int r = -ENOMEM; 1086 struct ahash_request *req; 1087 u8 *zero_data; 1088 1089 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1090 1091 if (!v->zero_digest) 1092 return r; 1093 1094 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 1095 1096 if (!req) 1097 return r; /* verity_dtr will free zero_digest */ 1098 1099 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1100 1101 if (!zero_data) 1102 goto out; 1103 1104 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 1105 v->zero_digest, true); 1106 1107out: 1108 kfree(req); 1109 kfree(zero_data); 1110 1111 return r; 1112} 1113 1114static inline bool verity_is_verity_mode(const char *arg_name) 1115{ 1116 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1117 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1118 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1119} 1120 1121static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1122{ 1123 if (v->mode) 1124 return -EINVAL; 1125 1126 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1127 v->mode = DM_VERITY_MODE_LOGGING; 1128 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1129 v->mode = DM_VERITY_MODE_RESTART; 1130 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1131 v->mode = DM_VERITY_MODE_PANIC; 1132 1133 return 0; 1134} 1135 1136static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1137 struct dm_verity_sig_opts *verify_args, 1138 bool only_modifier_opts) 1139{ 1140 int r = 0; 1141 unsigned int argc; 1142 struct dm_target *ti = v->ti; 1143 const char *arg_name; 1144 1145 static const struct dm_arg _args[] = { 1146 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1147 }; 1148 1149 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1150 if (r) 1151 return -EINVAL; 1152 1153 if (!argc) 1154 return 0; 1155 1156 do { 1157 arg_name = dm_shift_arg(as); 1158 argc--; 1159 1160 if (verity_is_verity_mode(arg_name)) { 1161 if (only_modifier_opts) 1162 continue; 1163 r = verity_parse_verity_mode(v, arg_name); 1164 if (r) { 1165 ti->error = "Conflicting error handling parameters"; 1166 return r; 1167 } 1168 continue; 1169 1170 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1171 if (only_modifier_opts) 1172 continue; 1173 r = verity_alloc_zero_digest(v); 1174 if (r) { 1175 ti->error = "Cannot allocate zero digest"; 1176 return r; 1177 } 1178 continue; 1179 1180 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1181 if (only_modifier_opts) 1182 continue; 1183 r = verity_alloc_most_once(v); 1184 if (r) 1185 return r; 1186 continue; 1187 1188 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1189 v->use_bh_wq = true; 1190 static_branch_inc(&use_bh_wq_enabled); 1191 continue; 1192 1193 } else if (verity_is_fec_opt_arg(arg_name)) { 1194 if (only_modifier_opts) 1195 continue; 1196 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1197 if (r) 1198 return r; 1199 continue; 1200 1201 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1202 if (only_modifier_opts) 1203 continue; 1204 r = verity_verify_sig_parse_opt_args(as, v, 1205 verify_args, 1206 &argc, arg_name); 1207 if (r) 1208 return r; 1209 continue; 1210 1211 } else if (only_modifier_opts) { 1212 /* 1213 * Ignore unrecognized opt, could easily be an extra 1214 * argument to an option whose parsing was skipped. 1215 * Normal parsing (@only_modifier_opts=false) will 1216 * properly parse all options (and their extra args). 1217 */ 1218 continue; 1219 } 1220 1221 DMERR("Unrecognized verity feature request: %s", arg_name); 1222 ti->error = "Unrecognized verity feature request"; 1223 return -EINVAL; 1224 } while (argc && !r); 1225 1226 return r; 1227} 1228 1229/* 1230 * Target parameters: 1231 * <version> The current format is version 1. 1232 * Vsn 0 is compatible with original Chromium OS releases. 1233 * <data device> 1234 * <hash device> 1235 * <data block size> 1236 * <hash block size> 1237 * <the number of data blocks> 1238 * <hash start block> 1239 * <algorithm> 1240 * <digest> 1241 * <salt> Hex string or "-" if no salt. 1242 */ 1243static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1244{ 1245 struct dm_verity *v; 1246 struct dm_verity_sig_opts verify_args = {0}; 1247 struct dm_arg_set as; 1248 unsigned int num; 1249 unsigned long long num_ll; 1250 int r; 1251 int i; 1252 sector_t hash_position; 1253 char dummy; 1254 char *root_hash_digest_to_validate; 1255 1256 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1257 if (!v) { 1258 ti->error = "Cannot allocate verity structure"; 1259 return -ENOMEM; 1260 } 1261 ti->private = v; 1262 v->ti = ti; 1263 1264 r = verity_fec_ctr_alloc(v); 1265 if (r) 1266 goto bad; 1267 1268 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1269 ti->error = "Device must be readonly"; 1270 r = -EINVAL; 1271 goto bad; 1272 } 1273 1274 if (argc < 10) { 1275 ti->error = "Not enough arguments"; 1276 r = -EINVAL; 1277 goto bad; 1278 } 1279 1280 /* Parse optional parameters that modify primary args */ 1281 if (argc > 10) { 1282 as.argc = argc - 10; 1283 as.argv = argv + 10; 1284 r = verity_parse_opt_args(&as, v, &verify_args, true); 1285 if (r < 0) 1286 goto bad; 1287 } 1288 1289 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1290 num > 1) { 1291 ti->error = "Invalid version"; 1292 r = -EINVAL; 1293 goto bad; 1294 } 1295 v->version = num; 1296 1297 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1298 if (r) { 1299 ti->error = "Data device lookup failed"; 1300 goto bad; 1301 } 1302 1303 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1304 if (r) { 1305 ti->error = "Hash device lookup failed"; 1306 goto bad; 1307 } 1308 1309 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1310 !num || (num & (num - 1)) || 1311 num < bdev_logical_block_size(v->data_dev->bdev) || 1312 num > PAGE_SIZE) { 1313 ti->error = "Invalid data device block size"; 1314 r = -EINVAL; 1315 goto bad; 1316 } 1317 v->data_dev_block_bits = __ffs(num); 1318 1319 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1320 !num || (num & (num - 1)) || 1321 num < bdev_logical_block_size(v->hash_dev->bdev) || 1322 num > INT_MAX) { 1323 ti->error = "Invalid hash device block size"; 1324 r = -EINVAL; 1325 goto bad; 1326 } 1327 v->hash_dev_block_bits = __ffs(num); 1328 1329 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1330 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1331 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1332 ti->error = "Invalid data blocks"; 1333 r = -EINVAL; 1334 goto bad; 1335 } 1336 v->data_blocks = num_ll; 1337 1338 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1339 ti->error = "Data device is too small"; 1340 r = -EINVAL; 1341 goto bad; 1342 } 1343 1344 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1345 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1346 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1347 ti->error = "Invalid hash start"; 1348 r = -EINVAL; 1349 goto bad; 1350 } 1351 v->hash_start = num_ll; 1352 1353 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1354 if (!v->alg_name) { 1355 ti->error = "Cannot allocate algorithm name"; 1356 r = -ENOMEM; 1357 goto bad; 1358 } 1359 1360 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 1361 v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0); 1362 if (IS_ERR(v->tfm)) { 1363 ti->error = "Cannot initialize hash function"; 1364 r = PTR_ERR(v->tfm); 1365 v->tfm = NULL; 1366 goto bad; 1367 } 1368 1369 /* 1370 * dm-verity performance can vary greatly depending on which hash 1371 * algorithm implementation is used. Help people debug performance 1372 * problems by logging the ->cra_driver_name. 1373 */ 1374 DMINFO("%s using implementation \"%s\"", v->alg_name, 1375 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1376 1377 v->digest_size = crypto_ahash_digestsize(v->tfm); 1378 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1379 ti->error = "Digest size too big"; 1380 r = -EINVAL; 1381 goto bad; 1382 } 1383 v->ahash_reqsize = sizeof(struct ahash_request) + 1384 crypto_ahash_reqsize(v->tfm); 1385 1386 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1387 if (!v->root_digest) { 1388 ti->error = "Cannot allocate root digest"; 1389 r = -ENOMEM; 1390 goto bad; 1391 } 1392 if (strlen(argv[8]) != v->digest_size * 2 || 1393 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1394 ti->error = "Invalid root digest"; 1395 r = -EINVAL; 1396 goto bad; 1397 } 1398 root_hash_digest_to_validate = argv[8]; 1399 1400 if (strcmp(argv[9], "-")) { 1401 v->salt_size = strlen(argv[9]) / 2; 1402 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1403 if (!v->salt) { 1404 ti->error = "Cannot allocate salt"; 1405 r = -ENOMEM; 1406 goto bad; 1407 } 1408 if (strlen(argv[9]) != v->salt_size * 2 || 1409 hex2bin(v->salt, argv[9], v->salt_size)) { 1410 ti->error = "Invalid salt"; 1411 r = -EINVAL; 1412 goto bad; 1413 } 1414 } 1415 1416 argv += 10; 1417 argc -= 10; 1418 1419 /* Optional parameters */ 1420 if (argc) { 1421 as.argc = argc; 1422 as.argv = argv; 1423 r = verity_parse_opt_args(&as, v, &verify_args, false); 1424 if (r < 0) 1425 goto bad; 1426 } 1427 1428 /* Root hash signature is a optional parameter*/ 1429 r = verity_verify_root_hash(root_hash_digest_to_validate, 1430 strlen(root_hash_digest_to_validate), 1431 verify_args.sig, 1432 verify_args.sig_size); 1433 if (r < 0) { 1434 ti->error = "Root hash verification failed"; 1435 goto bad; 1436 } 1437 v->hash_per_block_bits = 1438 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1439 1440 v->levels = 0; 1441 if (v->data_blocks) 1442 while (v->hash_per_block_bits * v->levels < 64 && 1443 (unsigned long long)(v->data_blocks - 1) >> 1444 (v->hash_per_block_bits * v->levels)) 1445 v->levels++; 1446 1447 if (v->levels > DM_VERITY_MAX_LEVELS) { 1448 ti->error = "Too many tree levels"; 1449 r = -E2BIG; 1450 goto bad; 1451 } 1452 1453 hash_position = v->hash_start; 1454 for (i = v->levels - 1; i >= 0; i--) { 1455 sector_t s; 1456 1457 v->hash_level_block[i] = hash_position; 1458 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1459 >> ((i + 1) * v->hash_per_block_bits); 1460 if (hash_position + s < hash_position) { 1461 ti->error = "Hash device offset overflow"; 1462 r = -E2BIG; 1463 goto bad; 1464 } 1465 hash_position += s; 1466 } 1467 v->hash_blocks = hash_position; 1468 1469 r = mempool_init_page_pool(&v->recheck_pool, 1, 0); 1470 if (unlikely(r)) { 1471 ti->error = "Cannot allocate mempool"; 1472 goto bad; 1473 } 1474 1475 v->io = dm_io_client_create(); 1476 if (IS_ERR(v->io)) { 1477 r = PTR_ERR(v->io); 1478 v->io = NULL; 1479 ti->error = "Cannot allocate dm io"; 1480 goto bad; 1481 } 1482 1483 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1484 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1485 dm_bufio_alloc_callback, NULL, 1486 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1487 if (IS_ERR(v->bufio)) { 1488 ti->error = "Cannot initialize dm-bufio"; 1489 r = PTR_ERR(v->bufio); 1490 v->bufio = NULL; 1491 goto bad; 1492 } 1493 1494 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1495 ti->error = "Hash device is too small"; 1496 r = -E2BIG; 1497 goto bad; 1498 } 1499 1500 /* 1501 * Using WQ_HIGHPRI improves throughput and completion latency by 1502 * reducing wait times when reading from a dm-verity device. 1503 * 1504 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1505 * allows verify_wq to preempt softirq since verification in BH workqueue 1506 * will fall-back to using it for error handling (or if the bufio cache 1507 * doesn't have required hashes). 1508 */ 1509 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1510 if (!v->verify_wq) { 1511 ti->error = "Cannot allocate workqueue"; 1512 r = -ENOMEM; 1513 goto bad; 1514 } 1515 1516 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1517 v->ahash_reqsize + v->digest_size * 2; 1518 1519 r = verity_fec_ctr(v); 1520 if (r) 1521 goto bad; 1522 1523 ti->per_io_data_size = roundup(ti->per_io_data_size, 1524 __alignof__(struct dm_verity_io)); 1525 1526 verity_verify_sig_opts_cleanup(&verify_args); 1527 1528 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1529 1530 return 0; 1531 1532bad: 1533 1534 verity_verify_sig_opts_cleanup(&verify_args); 1535 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1536 verity_dtr(ti); 1537 1538 return r; 1539} 1540 1541/* 1542 * Check whether a DM target is a verity target. 1543 */ 1544bool dm_is_verity_target(struct dm_target *ti) 1545{ 1546 return ti->type->module == THIS_MODULE; 1547} 1548 1549/* 1550 * Get the verity mode (error behavior) of a verity target. 1551 * 1552 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1553 * target. 1554 */ 1555int dm_verity_get_mode(struct dm_target *ti) 1556{ 1557 struct dm_verity *v = ti->private; 1558 1559 if (!dm_is_verity_target(ti)) 1560 return -EINVAL; 1561 1562 return v->mode; 1563} 1564 1565/* 1566 * Get the root digest of a verity target. 1567 * 1568 * Returns a copy of the root digest, the caller is responsible for 1569 * freeing the memory of the digest. 1570 */ 1571int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1572{ 1573 struct dm_verity *v = ti->private; 1574 1575 if (!dm_is_verity_target(ti)) 1576 return -EINVAL; 1577 1578 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1579 if (*root_digest == NULL) 1580 return -ENOMEM; 1581 1582 *digest_size = v->digest_size; 1583 1584 return 0; 1585} 1586 1587static struct target_type verity_target = { 1588 .name = "verity", 1589 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, 1590 .version = {1, 10, 0}, 1591 .module = THIS_MODULE, 1592 .ctr = verity_ctr, 1593 .dtr = verity_dtr, 1594 .map = verity_map, 1595 .status = verity_status, 1596 .prepare_ioctl = verity_prepare_ioctl, 1597 .iterate_devices = verity_iterate_devices, 1598 .io_hints = verity_io_hints, 1599}; 1600module_dm(verity); 1601 1602MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1603MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1604MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1605MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1606MODULE_LICENSE("GPL"); 1607