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 (2 + DM_VERITY_OPTS_FEC + \ 38 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 39 40 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 41 42 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR); 43 44 struct 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 */ 63 struct buffer_aux { 64 int hash_verified; 65 }; 66 67 /* 68 * Initialize struct buffer_aux for a freshly created buffer. 69 */ 70 static 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 */ 80 static 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 */ 91 static 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 97 static 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 */ 128 static 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 } 151 152 static 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); 168 out: 169 return r; 170 } 171 172 int 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); 187 188 out: 189 return r; 190 } 191 192 static 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 */ 213 static 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); 250 251 out: 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 */ 275 static 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; 324 325 release_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 */ 334 int 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 } 359 out: 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 */ 371 static 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 */ 415 int 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 } 448 449 static 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 */ 459 static 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 */ 471 static 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; 478 479 for (b = 0; b < io->n_blocks; b++) { 480 int r; 481 sector_t cur_block = io->block + b; 482 struct ahash_request *req = verity_io_hash_req(v, io); 483 484 if (v->validated_blocks && 485 likely(test_bit(cur_block, v->validated_blocks))) { 486 verity_bv_skip_block(v, io, &io->iter); 487 continue; 488 } 489 490 r = verity_hash_for_block(v, io, cur_block, 491 verity_io_want_digest(v, io), 492 &is_zero); 493 if (unlikely(r < 0)) 494 return r; 495 496 if (is_zero) { 497 /* 498 * If we expect a zero block, don't validate, just 499 * return zeros. 500 */ 501 r = verity_for_bv_block(v, io, &io->iter, 502 verity_bv_zero); 503 if (unlikely(r < 0)) 504 return r; 505 506 continue; 507 } 508 509 r = verity_hash_init(v, req, &wait); 510 if (unlikely(r < 0)) 511 return r; 512 513 start = io->iter; 514 r = verity_for_io_block(v, io, &io->iter, &wait); 515 if (unlikely(r < 0)) 516 return r; 517 518 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 519 &wait); 520 if (unlikely(r < 0)) 521 return r; 522 523 if (likely(memcmp(verity_io_real_digest(v, io), 524 verity_io_want_digest(v, io), v->digest_size) == 0)) { 525 if (v->validated_blocks) 526 set_bit(cur_block, v->validated_blocks); 527 continue; 528 } 529 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 530 cur_block, NULL, &start) == 0) 531 continue; 532 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 533 cur_block)) 534 return -EIO; 535 } 536 537 return 0; 538 } 539 540 /* 541 * End one "io" structure with a given error. 542 */ 543 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 544 { 545 struct dm_verity *v = io->v; 546 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 547 548 bio->bi_end_io = io->orig_bi_end_io; 549 bio->bi_status = status; 550 551 verity_fec_finish_io(io); 552 553 bio_endio(bio); 554 } 555 556 static void verity_work(struct work_struct *w) 557 { 558 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 559 560 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 561 } 562 563 static void verity_end_io(struct bio *bio) 564 { 565 struct dm_verity_io *io = bio->bi_private; 566 567 if (bio->bi_status && !verity_fec_is_enabled(io->v)) { 568 verity_finish_io(io, bio->bi_status); 569 return; 570 } 571 572 INIT_WORK(&io->work, verity_work); 573 queue_work(io->v->verify_wq, &io->work); 574 } 575 576 /* 577 * Prefetch buffers for the specified io. 578 * The root buffer is not prefetched, it is assumed that it will be cached 579 * all the time. 580 */ 581 static void verity_prefetch_io(struct work_struct *work) 582 { 583 struct dm_verity_prefetch_work *pw = 584 container_of(work, struct dm_verity_prefetch_work, work); 585 struct dm_verity *v = pw->v; 586 int i; 587 588 for (i = v->levels - 2; i >= 0; i--) { 589 sector_t hash_block_start; 590 sector_t hash_block_end; 591 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 592 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 593 if (!i) { 594 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster); 595 596 cluster >>= v->data_dev_block_bits; 597 if (unlikely(!cluster)) 598 goto no_prefetch_cluster; 599 600 if (unlikely(cluster & (cluster - 1))) 601 cluster = 1 << __fls(cluster); 602 603 hash_block_start &= ~(sector_t)(cluster - 1); 604 hash_block_end |= cluster - 1; 605 if (unlikely(hash_block_end >= v->hash_blocks)) 606 hash_block_end = v->hash_blocks - 1; 607 } 608 no_prefetch_cluster: 609 dm_bufio_prefetch(v->bufio, hash_block_start, 610 hash_block_end - hash_block_start + 1); 611 } 612 613 kfree(pw); 614 } 615 616 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 617 { 618 sector_t block = io->block; 619 unsigned int n_blocks = io->n_blocks; 620 struct dm_verity_prefetch_work *pw; 621 622 if (v->validated_blocks) { 623 while (n_blocks && test_bit(block, v->validated_blocks)) { 624 block++; 625 n_blocks--; 626 } 627 while (n_blocks && test_bit(block + n_blocks - 1, 628 v->validated_blocks)) 629 n_blocks--; 630 if (!n_blocks) 631 return; 632 } 633 634 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 635 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 636 637 if (!pw) 638 return; 639 640 INIT_WORK(&pw->work, verity_prefetch_io); 641 pw->v = v; 642 pw->block = block; 643 pw->n_blocks = n_blocks; 644 queue_work(v->verify_wq, &pw->work); 645 } 646 647 /* 648 * Bio map function. It allocates dm_verity_io structure and bio vector and 649 * fills them. Then it issues prefetches and the I/O. 650 */ 651 static int verity_map(struct dm_target *ti, struct bio *bio) 652 { 653 struct dm_verity *v = ti->private; 654 struct dm_verity_io *io; 655 656 bio_set_dev(bio, v->data_dev->bdev); 657 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 658 659 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) & 660 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 661 DMERR_LIMIT("unaligned io"); 662 return DM_MAPIO_KILL; 663 } 664 665 if (bio_end_sector(bio) >> 666 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 667 DMERR_LIMIT("io out of range"); 668 return DM_MAPIO_KILL; 669 } 670 671 if (bio_data_dir(bio) == WRITE) 672 return DM_MAPIO_KILL; 673 674 io = dm_per_bio_data(bio, ti->per_io_data_size); 675 io->v = v; 676 io->orig_bi_end_io = bio->bi_end_io; 677 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 678 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 679 680 bio->bi_end_io = verity_end_io; 681 bio->bi_private = io; 682 io->iter = bio->bi_iter; 683 684 verity_fec_init_io(io); 685 686 verity_submit_prefetch(v, io); 687 688 submit_bio_noacct(bio); 689 690 return DM_MAPIO_SUBMITTED; 691 } 692 693 /* 694 * Status: V (valid) or C (corruption found) 695 */ 696 static void verity_status(struct dm_target *ti, status_type_t type, 697 unsigned status_flags, char *result, unsigned maxlen) 698 { 699 struct dm_verity *v = ti->private; 700 unsigned args = 0; 701 unsigned sz = 0; 702 unsigned x; 703 704 switch (type) { 705 case STATUSTYPE_INFO: 706 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 707 break; 708 case STATUSTYPE_TABLE: 709 DMEMIT("%u %s %s %u %u %llu %llu %s ", 710 v->version, 711 v->data_dev->name, 712 v->hash_dev->name, 713 1 << v->data_dev_block_bits, 714 1 << v->hash_dev_block_bits, 715 (unsigned long long)v->data_blocks, 716 (unsigned long long)v->hash_start, 717 v->alg_name 718 ); 719 for (x = 0; x < v->digest_size; x++) 720 DMEMIT("%02x", v->root_digest[x]); 721 DMEMIT(" "); 722 if (!v->salt_size) 723 DMEMIT("-"); 724 else 725 for (x = 0; x < v->salt_size; x++) 726 DMEMIT("%02x", v->salt[x]); 727 if (v->mode != DM_VERITY_MODE_EIO) 728 args++; 729 if (verity_fec_is_enabled(v)) 730 args += DM_VERITY_OPTS_FEC; 731 if (v->zero_digest) 732 args++; 733 if (v->validated_blocks) 734 args++; 735 if (v->signature_key_desc) 736 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 737 if (!args) 738 return; 739 DMEMIT(" %u", args); 740 if (v->mode != DM_VERITY_MODE_EIO) { 741 DMEMIT(" "); 742 switch (v->mode) { 743 case DM_VERITY_MODE_LOGGING: 744 DMEMIT(DM_VERITY_OPT_LOGGING); 745 break; 746 case DM_VERITY_MODE_RESTART: 747 DMEMIT(DM_VERITY_OPT_RESTART); 748 break; 749 case DM_VERITY_MODE_PANIC: 750 DMEMIT(DM_VERITY_OPT_PANIC); 751 break; 752 default: 753 BUG(); 754 } 755 } 756 if (v->zero_digest) 757 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 758 if (v->validated_blocks) 759 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 760 sz = verity_fec_status_table(v, sz, result, maxlen); 761 if (v->signature_key_desc) 762 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 763 " %s", v->signature_key_desc); 764 break; 765 } 766 } 767 768 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 769 { 770 struct dm_verity *v = ti->private; 771 772 *bdev = v->data_dev->bdev; 773 774 if (v->data_start || 775 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) 776 return 1; 777 return 0; 778 } 779 780 static int verity_iterate_devices(struct dm_target *ti, 781 iterate_devices_callout_fn fn, void *data) 782 { 783 struct dm_verity *v = ti->private; 784 785 return fn(ti, v->data_dev, v->data_start, ti->len, data); 786 } 787 788 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 789 { 790 struct dm_verity *v = ti->private; 791 792 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 793 limits->logical_block_size = 1 << v->data_dev_block_bits; 794 795 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 796 limits->physical_block_size = 1 << v->data_dev_block_bits; 797 798 blk_limits_io_min(limits, limits->logical_block_size); 799 } 800 801 static void verity_dtr(struct dm_target *ti) 802 { 803 struct dm_verity *v = ti->private; 804 805 if (v->verify_wq) 806 destroy_workqueue(v->verify_wq); 807 808 if (v->bufio) 809 dm_bufio_client_destroy(v->bufio); 810 811 kvfree(v->validated_blocks); 812 kfree(v->salt); 813 kfree(v->root_digest); 814 kfree(v->zero_digest); 815 816 if (v->tfm) 817 crypto_free_ahash(v->tfm); 818 819 kfree(v->alg_name); 820 821 if (v->hash_dev) 822 dm_put_device(ti, v->hash_dev); 823 824 if (v->data_dev) 825 dm_put_device(ti, v->data_dev); 826 827 verity_fec_dtr(v); 828 829 kfree(v->signature_key_desc); 830 831 kfree(v); 832 } 833 834 static int verity_alloc_most_once(struct dm_verity *v) 835 { 836 struct dm_target *ti = v->ti; 837 838 /* the bitset can only handle INT_MAX blocks */ 839 if (v->data_blocks > INT_MAX) { 840 ti->error = "device too large to use check_at_most_once"; 841 return -E2BIG; 842 } 843 844 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 845 sizeof(unsigned long), 846 GFP_KERNEL); 847 if (!v->validated_blocks) { 848 ti->error = "failed to allocate bitset for check_at_most_once"; 849 return -ENOMEM; 850 } 851 852 return 0; 853 } 854 855 static int verity_alloc_zero_digest(struct dm_verity *v) 856 { 857 int r = -ENOMEM; 858 struct ahash_request *req; 859 u8 *zero_data; 860 861 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 862 863 if (!v->zero_digest) 864 return r; 865 866 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 867 868 if (!req) 869 return r; /* verity_dtr will free zero_digest */ 870 871 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 872 873 if (!zero_data) 874 goto out; 875 876 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 877 v->zero_digest); 878 879 out: 880 kfree(req); 881 kfree(zero_data); 882 883 return r; 884 } 885 886 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 887 struct dm_verity_sig_opts *verify_args) 888 { 889 int r; 890 unsigned argc; 891 struct dm_target *ti = v->ti; 892 const char *arg_name; 893 894 static const struct dm_arg _args[] = { 895 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 896 }; 897 898 r = dm_read_arg_group(_args, as, &argc, &ti->error); 899 if (r) 900 return -EINVAL; 901 902 if (!argc) 903 return 0; 904 905 do { 906 arg_name = dm_shift_arg(as); 907 argc--; 908 909 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) { 910 v->mode = DM_VERITY_MODE_LOGGING; 911 continue; 912 913 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) { 914 v->mode = DM_VERITY_MODE_RESTART; 915 continue; 916 917 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) { 918 v->mode = DM_VERITY_MODE_PANIC; 919 continue; 920 921 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 922 r = verity_alloc_zero_digest(v); 923 if (r) { 924 ti->error = "Cannot allocate zero digest"; 925 return r; 926 } 927 continue; 928 929 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 930 r = verity_alloc_most_once(v); 931 if (r) 932 return r; 933 continue; 934 935 } else if (verity_is_fec_opt_arg(arg_name)) { 936 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 937 if (r) 938 return r; 939 continue; 940 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 941 r = verity_verify_sig_parse_opt_args(as, v, 942 verify_args, 943 &argc, arg_name); 944 if (r) 945 return r; 946 continue; 947 948 } 949 950 ti->error = "Unrecognized verity feature request"; 951 return -EINVAL; 952 } while (argc && !r); 953 954 return r; 955 } 956 957 /* 958 * Target parameters: 959 * <version> The current format is version 1. 960 * Vsn 0 is compatible with original Chromium OS releases. 961 * <data device> 962 * <hash device> 963 * <data block size> 964 * <hash block size> 965 * <the number of data blocks> 966 * <hash start block> 967 * <algorithm> 968 * <digest> 969 * <salt> Hex string or "-" if no salt. 970 */ 971 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) 972 { 973 struct dm_verity *v; 974 struct dm_verity_sig_opts verify_args = {0}; 975 struct dm_arg_set as; 976 unsigned int num; 977 unsigned long long num_ll; 978 int r; 979 int i; 980 sector_t hash_position; 981 char dummy; 982 char *root_hash_digest_to_validate; 983 984 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 985 if (!v) { 986 ti->error = "Cannot allocate verity structure"; 987 return -ENOMEM; 988 } 989 ti->private = v; 990 v->ti = ti; 991 992 r = verity_fec_ctr_alloc(v); 993 if (r) 994 goto bad; 995 996 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { 997 ti->error = "Device must be readonly"; 998 r = -EINVAL; 999 goto bad; 1000 } 1001 1002 if (argc < 10) { 1003 ti->error = "Not enough arguments"; 1004 r = -EINVAL; 1005 goto bad; 1006 } 1007 1008 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1009 num > 1) { 1010 ti->error = "Invalid version"; 1011 r = -EINVAL; 1012 goto bad; 1013 } 1014 v->version = num; 1015 1016 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); 1017 if (r) { 1018 ti->error = "Data device lookup failed"; 1019 goto bad; 1020 } 1021 1022 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); 1023 if (r) { 1024 ti->error = "Hash device lookup failed"; 1025 goto bad; 1026 } 1027 1028 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1029 !num || (num & (num - 1)) || 1030 num < bdev_logical_block_size(v->data_dev->bdev) || 1031 num > PAGE_SIZE) { 1032 ti->error = "Invalid data device block size"; 1033 r = -EINVAL; 1034 goto bad; 1035 } 1036 v->data_dev_block_bits = __ffs(num); 1037 1038 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1039 !num || (num & (num - 1)) || 1040 num < bdev_logical_block_size(v->hash_dev->bdev) || 1041 num > INT_MAX) { 1042 ti->error = "Invalid hash device block size"; 1043 r = -EINVAL; 1044 goto bad; 1045 } 1046 v->hash_dev_block_bits = __ffs(num); 1047 1048 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1049 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1050 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1051 ti->error = "Invalid data blocks"; 1052 r = -EINVAL; 1053 goto bad; 1054 } 1055 v->data_blocks = num_ll; 1056 1057 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1058 ti->error = "Data device is too small"; 1059 r = -EINVAL; 1060 goto bad; 1061 } 1062 1063 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1064 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1065 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1066 ti->error = "Invalid hash start"; 1067 r = -EINVAL; 1068 goto bad; 1069 } 1070 v->hash_start = num_ll; 1071 1072 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1073 if (!v->alg_name) { 1074 ti->error = "Cannot allocate algorithm name"; 1075 r = -ENOMEM; 1076 goto bad; 1077 } 1078 1079 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0); 1080 if (IS_ERR(v->tfm)) { 1081 ti->error = "Cannot initialize hash function"; 1082 r = PTR_ERR(v->tfm); 1083 v->tfm = NULL; 1084 goto bad; 1085 } 1086 1087 /* 1088 * dm-verity performance can vary greatly depending on which hash 1089 * algorithm implementation is used. Help people debug performance 1090 * problems by logging the ->cra_driver_name. 1091 */ 1092 DMINFO("%s using implementation \"%s\"", v->alg_name, 1093 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1094 1095 v->digest_size = crypto_ahash_digestsize(v->tfm); 1096 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1097 ti->error = "Digest size too big"; 1098 r = -EINVAL; 1099 goto bad; 1100 } 1101 v->ahash_reqsize = sizeof(struct ahash_request) + 1102 crypto_ahash_reqsize(v->tfm); 1103 1104 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1105 if (!v->root_digest) { 1106 ti->error = "Cannot allocate root digest"; 1107 r = -ENOMEM; 1108 goto bad; 1109 } 1110 if (strlen(argv[8]) != v->digest_size * 2 || 1111 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1112 ti->error = "Invalid root digest"; 1113 r = -EINVAL; 1114 goto bad; 1115 } 1116 root_hash_digest_to_validate = argv[8]; 1117 1118 if (strcmp(argv[9], "-")) { 1119 v->salt_size = strlen(argv[9]) / 2; 1120 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1121 if (!v->salt) { 1122 ti->error = "Cannot allocate salt"; 1123 r = -ENOMEM; 1124 goto bad; 1125 } 1126 if (strlen(argv[9]) != v->salt_size * 2 || 1127 hex2bin(v->salt, argv[9], v->salt_size)) { 1128 ti->error = "Invalid salt"; 1129 r = -EINVAL; 1130 goto bad; 1131 } 1132 } 1133 1134 argv += 10; 1135 argc -= 10; 1136 1137 /* Optional parameters */ 1138 if (argc) { 1139 as.argc = argc; 1140 as.argv = argv; 1141 1142 r = verity_parse_opt_args(&as, v, &verify_args); 1143 if (r < 0) 1144 goto bad; 1145 } 1146 1147 /* Root hash signature is a optional parameter*/ 1148 r = verity_verify_root_hash(root_hash_digest_to_validate, 1149 strlen(root_hash_digest_to_validate), 1150 verify_args.sig, 1151 verify_args.sig_size); 1152 if (r < 0) { 1153 ti->error = "Root hash verification failed"; 1154 goto bad; 1155 } 1156 v->hash_per_block_bits = 1157 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1158 1159 v->levels = 0; 1160 if (v->data_blocks) 1161 while (v->hash_per_block_bits * v->levels < 64 && 1162 (unsigned long long)(v->data_blocks - 1) >> 1163 (v->hash_per_block_bits * v->levels)) 1164 v->levels++; 1165 1166 if (v->levels > DM_VERITY_MAX_LEVELS) { 1167 ti->error = "Too many tree levels"; 1168 r = -E2BIG; 1169 goto bad; 1170 } 1171 1172 hash_position = v->hash_start; 1173 for (i = v->levels - 1; i >= 0; i--) { 1174 sector_t s; 1175 v->hash_level_block[i] = hash_position; 1176 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1177 >> ((i + 1) * v->hash_per_block_bits); 1178 if (hash_position + s < hash_position) { 1179 ti->error = "Hash device offset overflow"; 1180 r = -E2BIG; 1181 goto bad; 1182 } 1183 hash_position += s; 1184 } 1185 v->hash_blocks = hash_position; 1186 1187 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1188 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1189 dm_bufio_alloc_callback, NULL); 1190 if (IS_ERR(v->bufio)) { 1191 ti->error = "Cannot initialize dm-bufio"; 1192 r = PTR_ERR(v->bufio); 1193 v->bufio = NULL; 1194 goto bad; 1195 } 1196 1197 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1198 ti->error = "Hash device is too small"; 1199 r = -E2BIG; 1200 goto bad; 1201 } 1202 1203 /* WQ_UNBOUND greatly improves performance when running on ramdisk */ 1204 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); 1205 if (!v->verify_wq) { 1206 ti->error = "Cannot allocate workqueue"; 1207 r = -ENOMEM; 1208 goto bad; 1209 } 1210 1211 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1212 v->ahash_reqsize + v->digest_size * 2; 1213 1214 r = verity_fec_ctr(v); 1215 if (r) 1216 goto bad; 1217 1218 ti->per_io_data_size = roundup(ti->per_io_data_size, 1219 __alignof__(struct dm_verity_io)); 1220 1221 verity_verify_sig_opts_cleanup(&verify_args); 1222 1223 return 0; 1224 1225 bad: 1226 1227 verity_verify_sig_opts_cleanup(&verify_args); 1228 verity_dtr(ti); 1229 1230 return r; 1231 } 1232 1233 static struct target_type verity_target = { 1234 .name = "verity", 1235 .version = {1, 7, 0}, 1236 .module = THIS_MODULE, 1237 .ctr = verity_ctr, 1238 .dtr = verity_dtr, 1239 .map = verity_map, 1240 .status = verity_status, 1241 .prepare_ioctl = verity_prepare_ioctl, 1242 .iterate_devices = verity_iterate_devices, 1243 .io_hints = verity_io_hints, 1244 }; 1245 1246 static int __init dm_verity_init(void) 1247 { 1248 int r; 1249 1250 r = dm_register_target(&verity_target); 1251 if (r < 0) 1252 DMERR("register failed %d", r); 1253 1254 return r; 1255 } 1256 1257 static void __exit dm_verity_exit(void) 1258 { 1259 dm_unregister_target(&verity_target); 1260 } 1261 1262 module_init(dm_verity_init); 1263 module_exit(dm_verity_exit); 1264 1265 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1266 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1267 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1268 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1269 MODULE_LICENSE("GPL"); 1270