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