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 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 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 && 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 */ 552 static 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 */ 561 static 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 } 573 574 static 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 } 580 581 static 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) || verity_is_system_shutting_down())) { 587 verity_finish_io(io, bio->bi_status); 588 return; 589 } 590 591 INIT_WORK(&io->work, verity_work); 592 queue_work(io->v->verify_wq, &io->work); 593 } 594 595 /* 596 * Prefetch buffers for the specified io. 597 * The root buffer is not prefetched, it is assumed that it will be cached 598 * all the time. 599 */ 600 static void verity_prefetch_io(struct work_struct *work) 601 { 602 struct dm_verity_prefetch_work *pw = 603 container_of(work, struct dm_verity_prefetch_work, work); 604 struct dm_verity *v = pw->v; 605 int i; 606 607 for (i = v->levels - 2; i >= 0; i--) { 608 sector_t hash_block_start; 609 sector_t hash_block_end; 610 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 611 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 612 if (!i) { 613 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster); 614 615 cluster >>= v->data_dev_block_bits; 616 if (unlikely(!cluster)) 617 goto no_prefetch_cluster; 618 619 if (unlikely(cluster & (cluster - 1))) 620 cluster = 1 << __fls(cluster); 621 622 hash_block_start &= ~(sector_t)(cluster - 1); 623 hash_block_end |= cluster - 1; 624 if (unlikely(hash_block_end >= v->hash_blocks)) 625 hash_block_end = v->hash_blocks - 1; 626 } 627 no_prefetch_cluster: 628 dm_bufio_prefetch(v->bufio, hash_block_start, 629 hash_block_end - hash_block_start + 1); 630 } 631 632 kfree(pw); 633 } 634 635 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 636 { 637 sector_t block = io->block; 638 unsigned int n_blocks = io->n_blocks; 639 struct dm_verity_prefetch_work *pw; 640 641 if (v->validated_blocks) { 642 while (n_blocks && test_bit(block, v->validated_blocks)) { 643 block++; 644 n_blocks--; 645 } 646 while (n_blocks && test_bit(block + n_blocks - 1, 647 v->validated_blocks)) 648 n_blocks--; 649 if (!n_blocks) 650 return; 651 } 652 653 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 654 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 655 656 if (!pw) 657 return; 658 659 INIT_WORK(&pw->work, verity_prefetch_io); 660 pw->v = v; 661 pw->block = block; 662 pw->n_blocks = n_blocks; 663 queue_work(v->verify_wq, &pw->work); 664 } 665 666 /* 667 * Bio map function. It allocates dm_verity_io structure and bio vector and 668 * fills them. Then it issues prefetches and the I/O. 669 */ 670 static int verity_map(struct dm_target *ti, struct bio *bio) 671 { 672 struct dm_verity *v = ti->private; 673 struct dm_verity_io *io; 674 675 bio_set_dev(bio, v->data_dev->bdev); 676 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 677 678 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) & 679 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 680 DMERR_LIMIT("unaligned io"); 681 return DM_MAPIO_KILL; 682 } 683 684 if (bio_end_sector(bio) >> 685 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 686 DMERR_LIMIT("io out of range"); 687 return DM_MAPIO_KILL; 688 } 689 690 if (bio_data_dir(bio) == WRITE) 691 return DM_MAPIO_KILL; 692 693 io = dm_per_bio_data(bio, ti->per_io_data_size); 694 io->v = v; 695 io->orig_bi_end_io = bio->bi_end_io; 696 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 697 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 698 699 bio->bi_end_io = verity_end_io; 700 bio->bi_private = io; 701 io->iter = bio->bi_iter; 702 703 verity_fec_init_io(io); 704 705 verity_submit_prefetch(v, io); 706 707 submit_bio_noacct(bio); 708 709 return DM_MAPIO_SUBMITTED; 710 } 711 712 /* 713 * Status: V (valid) or C (corruption found) 714 */ 715 static void verity_status(struct dm_target *ti, status_type_t type, 716 unsigned status_flags, char *result, unsigned maxlen) 717 { 718 struct dm_verity *v = ti->private; 719 unsigned args = 0; 720 unsigned sz = 0; 721 unsigned x; 722 723 switch (type) { 724 case STATUSTYPE_INFO: 725 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 726 break; 727 case STATUSTYPE_TABLE: 728 DMEMIT("%u %s %s %u %u %llu %llu %s ", 729 v->version, 730 v->data_dev->name, 731 v->hash_dev->name, 732 1 << v->data_dev_block_bits, 733 1 << v->hash_dev_block_bits, 734 (unsigned long long)v->data_blocks, 735 (unsigned long long)v->hash_start, 736 v->alg_name 737 ); 738 for (x = 0; x < v->digest_size; x++) 739 DMEMIT("%02x", v->root_digest[x]); 740 DMEMIT(" "); 741 if (!v->salt_size) 742 DMEMIT("-"); 743 else 744 for (x = 0; x < v->salt_size; x++) 745 DMEMIT("%02x", v->salt[x]); 746 if (v->mode != DM_VERITY_MODE_EIO) 747 args++; 748 if (verity_fec_is_enabled(v)) 749 args += DM_VERITY_OPTS_FEC; 750 if (v->zero_digest) 751 args++; 752 if (v->validated_blocks) 753 args++; 754 if (v->signature_key_desc) 755 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 756 if (!args) 757 return; 758 DMEMIT(" %u", args); 759 if (v->mode != DM_VERITY_MODE_EIO) { 760 DMEMIT(" "); 761 switch (v->mode) { 762 case DM_VERITY_MODE_LOGGING: 763 DMEMIT(DM_VERITY_OPT_LOGGING); 764 break; 765 case DM_VERITY_MODE_RESTART: 766 DMEMIT(DM_VERITY_OPT_RESTART); 767 break; 768 case DM_VERITY_MODE_PANIC: 769 DMEMIT(DM_VERITY_OPT_PANIC); 770 break; 771 default: 772 BUG(); 773 } 774 } 775 if (v->zero_digest) 776 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 777 if (v->validated_blocks) 778 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 779 sz = verity_fec_status_table(v, sz, result, maxlen); 780 if (v->signature_key_desc) 781 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 782 " %s", v->signature_key_desc); 783 break; 784 785 case STATUSTYPE_IMA: 786 DMEMIT_TARGET_NAME_VERSION(ti->type); 787 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 788 DMEMIT(",verity_version=%u", v->version); 789 DMEMIT(",data_device_name=%s", v->data_dev->name); 790 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 791 DMEMIT(",verity_algorithm=%s", v->alg_name); 792 793 DMEMIT(",root_digest="); 794 for (x = 0; x < v->digest_size; x++) 795 DMEMIT("%02x", v->root_digest[x]); 796 797 DMEMIT(",salt="); 798 if (!v->salt_size) 799 DMEMIT("-"); 800 else 801 for (x = 0; x < v->salt_size; x++) 802 DMEMIT("%02x", v->salt[x]); 803 804 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 805 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 806 if (v->signature_key_desc) 807 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 808 809 if (v->mode != DM_VERITY_MODE_EIO) { 810 DMEMIT(",verity_mode="); 811 switch (v->mode) { 812 case DM_VERITY_MODE_LOGGING: 813 DMEMIT(DM_VERITY_OPT_LOGGING); 814 break; 815 case DM_VERITY_MODE_RESTART: 816 DMEMIT(DM_VERITY_OPT_RESTART); 817 break; 818 case DM_VERITY_MODE_PANIC: 819 DMEMIT(DM_VERITY_OPT_PANIC); 820 break; 821 default: 822 DMEMIT("invalid"); 823 } 824 } 825 DMEMIT(";"); 826 break; 827 } 828 } 829 830 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 831 { 832 struct dm_verity *v = ti->private; 833 834 *bdev = v->data_dev->bdev; 835 836 if (v->data_start || 837 ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) 838 return 1; 839 return 0; 840 } 841 842 static int verity_iterate_devices(struct dm_target *ti, 843 iterate_devices_callout_fn fn, void *data) 844 { 845 struct dm_verity *v = ti->private; 846 847 return fn(ti, v->data_dev, v->data_start, ti->len, data); 848 } 849 850 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 851 { 852 struct dm_verity *v = ti->private; 853 854 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 855 limits->logical_block_size = 1 << v->data_dev_block_bits; 856 857 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 858 limits->physical_block_size = 1 << v->data_dev_block_bits; 859 860 blk_limits_io_min(limits, limits->logical_block_size); 861 } 862 863 static void verity_dtr(struct dm_target *ti) 864 { 865 struct dm_verity *v = ti->private; 866 867 if (v->verify_wq) 868 destroy_workqueue(v->verify_wq); 869 870 if (v->bufio) 871 dm_bufio_client_destroy(v->bufio); 872 873 kvfree(v->validated_blocks); 874 kfree(v->salt); 875 kfree(v->root_digest); 876 kfree(v->zero_digest); 877 878 if (v->tfm) 879 crypto_free_ahash(v->tfm); 880 881 kfree(v->alg_name); 882 883 if (v->hash_dev) 884 dm_put_device(ti, v->hash_dev); 885 886 if (v->data_dev) 887 dm_put_device(ti, v->data_dev); 888 889 verity_fec_dtr(v); 890 891 kfree(v->signature_key_desc); 892 893 kfree(v); 894 } 895 896 static int verity_alloc_most_once(struct dm_verity *v) 897 { 898 struct dm_target *ti = v->ti; 899 900 /* the bitset can only handle INT_MAX blocks */ 901 if (v->data_blocks > INT_MAX) { 902 ti->error = "device too large to use check_at_most_once"; 903 return -E2BIG; 904 } 905 906 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 907 sizeof(unsigned long), 908 GFP_KERNEL); 909 if (!v->validated_blocks) { 910 ti->error = "failed to allocate bitset for check_at_most_once"; 911 return -ENOMEM; 912 } 913 914 return 0; 915 } 916 917 static int verity_alloc_zero_digest(struct dm_verity *v) 918 { 919 int r = -ENOMEM; 920 struct ahash_request *req; 921 u8 *zero_data; 922 923 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 924 925 if (!v->zero_digest) 926 return r; 927 928 req = kmalloc(v->ahash_reqsize, GFP_KERNEL); 929 930 if (!req) 931 return r; /* verity_dtr will free zero_digest */ 932 933 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 934 935 if (!zero_data) 936 goto out; 937 938 r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits, 939 v->zero_digest); 940 941 out: 942 kfree(req); 943 kfree(zero_data); 944 945 return r; 946 } 947 948 static inline bool verity_is_verity_mode(const char *arg_name) 949 { 950 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 951 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 952 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 953 } 954 955 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 956 { 957 if (v->mode) 958 return -EINVAL; 959 960 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 961 v->mode = DM_VERITY_MODE_LOGGING; 962 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 963 v->mode = DM_VERITY_MODE_RESTART; 964 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 965 v->mode = DM_VERITY_MODE_PANIC; 966 967 return 0; 968 } 969 970 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 971 struct dm_verity_sig_opts *verify_args) 972 { 973 int r; 974 unsigned argc; 975 struct dm_target *ti = v->ti; 976 const char *arg_name; 977 978 static const struct dm_arg _args[] = { 979 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 980 }; 981 982 r = dm_read_arg_group(_args, as, &argc, &ti->error); 983 if (r) 984 return -EINVAL; 985 986 if (!argc) 987 return 0; 988 989 do { 990 arg_name = dm_shift_arg(as); 991 argc--; 992 993 if (verity_is_verity_mode(arg_name)) { 994 r = verity_parse_verity_mode(v, arg_name); 995 if (r) { 996 ti->error = "Conflicting error handling parameters"; 997 return r; 998 } 999 continue; 1000 1001 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1002 r = verity_alloc_zero_digest(v); 1003 if (r) { 1004 ti->error = "Cannot allocate zero digest"; 1005 return r; 1006 } 1007 continue; 1008 1009 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1010 r = verity_alloc_most_once(v); 1011 if (r) 1012 return r; 1013 continue; 1014 1015 } else if (verity_is_fec_opt_arg(arg_name)) { 1016 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1017 if (r) 1018 return r; 1019 continue; 1020 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1021 r = verity_verify_sig_parse_opt_args(as, v, 1022 verify_args, 1023 &argc, arg_name); 1024 if (r) 1025 return r; 1026 continue; 1027 1028 } 1029 1030 ti->error = "Unrecognized verity feature request"; 1031 return -EINVAL; 1032 } while (argc && !r); 1033 1034 return r; 1035 } 1036 1037 /* 1038 * Target parameters: 1039 * <version> The current format is version 1. 1040 * Vsn 0 is compatible with original Chromium OS releases. 1041 * <data device> 1042 * <hash device> 1043 * <data block size> 1044 * <hash block size> 1045 * <the number of data blocks> 1046 * <hash start block> 1047 * <algorithm> 1048 * <digest> 1049 * <salt> Hex string or "-" if no salt. 1050 */ 1051 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) 1052 { 1053 struct dm_verity *v; 1054 struct dm_verity_sig_opts verify_args = {0}; 1055 struct dm_arg_set as; 1056 unsigned int num; 1057 unsigned long long num_ll; 1058 int r; 1059 int i; 1060 sector_t hash_position; 1061 char dummy; 1062 char *root_hash_digest_to_validate; 1063 1064 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1065 if (!v) { 1066 ti->error = "Cannot allocate verity structure"; 1067 return -ENOMEM; 1068 } 1069 ti->private = v; 1070 v->ti = ti; 1071 1072 r = verity_fec_ctr_alloc(v); 1073 if (r) 1074 goto bad; 1075 1076 if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) { 1077 ti->error = "Device must be readonly"; 1078 r = -EINVAL; 1079 goto bad; 1080 } 1081 1082 if (argc < 10) { 1083 ti->error = "Not enough arguments"; 1084 r = -EINVAL; 1085 goto bad; 1086 } 1087 1088 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1089 num > 1) { 1090 ti->error = "Invalid version"; 1091 r = -EINVAL; 1092 goto bad; 1093 } 1094 v->version = num; 1095 1096 r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); 1097 if (r) { 1098 ti->error = "Data device lookup failed"; 1099 goto bad; 1100 } 1101 1102 r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); 1103 if (r) { 1104 ti->error = "Hash device lookup failed"; 1105 goto bad; 1106 } 1107 1108 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1109 !num || (num & (num - 1)) || 1110 num < bdev_logical_block_size(v->data_dev->bdev) || 1111 num > PAGE_SIZE) { 1112 ti->error = "Invalid data device block size"; 1113 r = -EINVAL; 1114 goto bad; 1115 } 1116 v->data_dev_block_bits = __ffs(num); 1117 1118 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1119 !num || (num & (num - 1)) || 1120 num < bdev_logical_block_size(v->hash_dev->bdev) || 1121 num > INT_MAX) { 1122 ti->error = "Invalid hash device block size"; 1123 r = -EINVAL; 1124 goto bad; 1125 } 1126 v->hash_dev_block_bits = __ffs(num); 1127 1128 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1129 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1130 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1131 ti->error = "Invalid data blocks"; 1132 r = -EINVAL; 1133 goto bad; 1134 } 1135 v->data_blocks = num_ll; 1136 1137 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1138 ti->error = "Data device is too small"; 1139 r = -EINVAL; 1140 goto bad; 1141 } 1142 1143 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1144 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1145 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1146 ti->error = "Invalid hash start"; 1147 r = -EINVAL; 1148 goto bad; 1149 } 1150 v->hash_start = num_ll; 1151 1152 v->alg_name = kstrdup(argv[7], GFP_KERNEL); 1153 if (!v->alg_name) { 1154 ti->error = "Cannot allocate algorithm name"; 1155 r = -ENOMEM; 1156 goto bad; 1157 } 1158 1159 v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0); 1160 if (IS_ERR(v->tfm)) { 1161 ti->error = "Cannot initialize hash function"; 1162 r = PTR_ERR(v->tfm); 1163 v->tfm = NULL; 1164 goto bad; 1165 } 1166 1167 /* 1168 * dm-verity performance can vary greatly depending on which hash 1169 * algorithm implementation is used. Help people debug performance 1170 * problems by logging the ->cra_driver_name. 1171 */ 1172 DMINFO("%s using implementation \"%s\"", v->alg_name, 1173 crypto_hash_alg_common(v->tfm)->base.cra_driver_name); 1174 1175 v->digest_size = crypto_ahash_digestsize(v->tfm); 1176 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1177 ti->error = "Digest size too big"; 1178 r = -EINVAL; 1179 goto bad; 1180 } 1181 v->ahash_reqsize = sizeof(struct ahash_request) + 1182 crypto_ahash_reqsize(v->tfm); 1183 1184 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1185 if (!v->root_digest) { 1186 ti->error = "Cannot allocate root digest"; 1187 r = -ENOMEM; 1188 goto bad; 1189 } 1190 if (strlen(argv[8]) != v->digest_size * 2 || 1191 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1192 ti->error = "Invalid root digest"; 1193 r = -EINVAL; 1194 goto bad; 1195 } 1196 root_hash_digest_to_validate = argv[8]; 1197 1198 if (strcmp(argv[9], "-")) { 1199 v->salt_size = strlen(argv[9]) / 2; 1200 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1201 if (!v->salt) { 1202 ti->error = "Cannot allocate salt"; 1203 r = -ENOMEM; 1204 goto bad; 1205 } 1206 if (strlen(argv[9]) != v->salt_size * 2 || 1207 hex2bin(v->salt, argv[9], v->salt_size)) { 1208 ti->error = "Invalid salt"; 1209 r = -EINVAL; 1210 goto bad; 1211 } 1212 } 1213 1214 argv += 10; 1215 argc -= 10; 1216 1217 /* Optional parameters */ 1218 if (argc) { 1219 as.argc = argc; 1220 as.argv = argv; 1221 1222 r = verity_parse_opt_args(&as, v, &verify_args); 1223 if (r < 0) 1224 goto bad; 1225 } 1226 1227 /* Root hash signature is a optional parameter*/ 1228 r = verity_verify_root_hash(root_hash_digest_to_validate, 1229 strlen(root_hash_digest_to_validate), 1230 verify_args.sig, 1231 verify_args.sig_size); 1232 if (r < 0) { 1233 ti->error = "Root hash verification failed"; 1234 goto bad; 1235 } 1236 v->hash_per_block_bits = 1237 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1238 1239 v->levels = 0; 1240 if (v->data_blocks) 1241 while (v->hash_per_block_bits * v->levels < 64 && 1242 (unsigned long long)(v->data_blocks - 1) >> 1243 (v->hash_per_block_bits * v->levels)) 1244 v->levels++; 1245 1246 if (v->levels > DM_VERITY_MAX_LEVELS) { 1247 ti->error = "Too many tree levels"; 1248 r = -E2BIG; 1249 goto bad; 1250 } 1251 1252 hash_position = v->hash_start; 1253 for (i = v->levels - 1; i >= 0; i--) { 1254 sector_t s; 1255 v->hash_level_block[i] = hash_position; 1256 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1257 >> ((i + 1) * v->hash_per_block_bits); 1258 if (hash_position + s < hash_position) { 1259 ti->error = "Hash device offset overflow"; 1260 r = -E2BIG; 1261 goto bad; 1262 } 1263 hash_position += s; 1264 } 1265 v->hash_blocks = hash_position; 1266 1267 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1268 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1269 dm_bufio_alloc_callback, NULL); 1270 if (IS_ERR(v->bufio)) { 1271 ti->error = "Cannot initialize dm-bufio"; 1272 r = PTR_ERR(v->bufio); 1273 v->bufio = NULL; 1274 goto bad; 1275 } 1276 1277 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1278 ti->error = "Hash device is too small"; 1279 r = -E2BIG; 1280 goto bad; 1281 } 1282 1283 /* WQ_UNBOUND greatly improves performance when running on ramdisk */ 1284 v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); 1285 if (!v->verify_wq) { 1286 ti->error = "Cannot allocate workqueue"; 1287 r = -ENOMEM; 1288 goto bad; 1289 } 1290 1291 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1292 v->ahash_reqsize + v->digest_size * 2; 1293 1294 r = verity_fec_ctr(v); 1295 if (r) 1296 goto bad; 1297 1298 ti->per_io_data_size = roundup(ti->per_io_data_size, 1299 __alignof__(struct dm_verity_io)); 1300 1301 verity_verify_sig_opts_cleanup(&verify_args); 1302 1303 return 0; 1304 1305 bad: 1306 1307 verity_verify_sig_opts_cleanup(&verify_args); 1308 verity_dtr(ti); 1309 1310 return r; 1311 } 1312 1313 static struct target_type verity_target = { 1314 .name = "verity", 1315 .version = {1, 8, 0}, 1316 .module = THIS_MODULE, 1317 .ctr = verity_ctr, 1318 .dtr = verity_dtr, 1319 .map = verity_map, 1320 .status = verity_status, 1321 .prepare_ioctl = verity_prepare_ioctl, 1322 .iterate_devices = verity_iterate_devices, 1323 .io_hints = verity_io_hints, 1324 }; 1325 1326 static int __init dm_verity_init(void) 1327 { 1328 int r; 1329 1330 r = dm_register_target(&verity_target); 1331 if (r < 0) 1332 DMERR("register failed %d", r); 1333 1334 return r; 1335 } 1336 1337 static void __exit dm_verity_exit(void) 1338 { 1339 dm_unregister_target(&verity_target); 1340 } 1341 1342 module_init(dm_verity_init); 1343 module_exit(dm_verity_exit); 1344 1345 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1346 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1347 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1348 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1349 MODULE_LICENSE("GPL"); 1350