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 #include <linux/scatterlist.h> 22 23 #define DM_MSG_PREFIX "verity" 24 25 #define DM_VERITY_ENV_LENGTH 42 26 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 27 28 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 29 30 #define DM_VERITY_MAX_CORRUPTED_ERRS 100 31 32 #define DM_VERITY_OPT_LOGGING "ignore_corruption" 33 #define DM_VERITY_OPT_RESTART "restart_on_corruption" 34 #define DM_VERITY_OPT_PANIC "panic_on_corruption" 35 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 36 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 37 38 #define DM_VERITY_OPTS_MAX (3 + DM_VERITY_OPTS_FEC + \ 39 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 40 41 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 42 43 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR); 44 45 struct dm_verity_prefetch_work { 46 struct work_struct work; 47 struct dm_verity *v; 48 sector_t block; 49 unsigned n_blocks; 50 }; 51 52 /* 53 * Auxiliary structure appended to each dm-bufio buffer. If the value 54 * hash_verified is nonzero, hash of the block has been verified. 55 * 56 * The variable hash_verified is set to 0 when allocating the buffer, then 57 * it can be changed to 1 and it is never reset to 0 again. 58 * 59 * There is no lock around this value, a race condition can at worst cause 60 * that multiple processes verify the hash of the same buffer simultaneously 61 * and write 1 to hash_verified simultaneously. 62 * This condition is harmless, so we don't need locking. 63 */ 64 struct buffer_aux { 65 int hash_verified; 66 }; 67 68 /* 69 * Initialize struct buffer_aux for a freshly created buffer. 70 */ 71 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 72 { 73 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 74 75 aux->hash_verified = 0; 76 } 77 78 /* 79 * Translate input sector number to the sector number on the target device. 80 */ 81 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 82 { 83 return v->data_start + dm_target_offset(v->ti, bi_sector); 84 } 85 86 /* 87 * Return hash position of a specified block at a specified tree level 88 * (0 is the lowest level). 89 * The lowest "hash_per_block_bits"-bits of the result denote hash position 90 * inside a hash block. The remaining bits denote location of the hash block. 91 */ 92 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 93 int level) 94 { 95 return block >> (level * v->hash_per_block_bits); 96 } 97 98 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req, 99 const u8 *data, size_t len, 100 struct crypto_wait *wait) 101 { 102 struct scatterlist sg; 103 104 if (likely(!is_vmalloc_addr(data))) { 105 sg_init_one(&sg, data, len); 106 ahash_request_set_crypt(req, &sg, NULL, len); 107 return crypto_wait_req(crypto_ahash_update(req), wait); 108 } else { 109 do { 110 int r; 111 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 112 flush_kernel_vmap_range((void *)data, this_step); 113 sg_init_table(&sg, 1); 114 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 115 ahash_request_set_crypt(req, &sg, NULL, this_step); 116 r = crypto_wait_req(crypto_ahash_update(req), wait); 117 if (unlikely(r)) 118 return r; 119 data += this_step; 120 len -= this_step; 121 } while (len); 122 return 0; 123 } 124 } 125 126 /* 127 * Wrapper for crypto_ahash_init, which handles verity salting. 128 */ 129 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req, 130 struct crypto_wait *wait) 131 { 132 int r; 133 134 ahash_request_set_tfm(req, v->tfm); 135 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | 136 CRYPTO_TFM_REQ_MAY_BACKLOG, 137 crypto_req_done, (void *)wait); 138 crypto_init_wait(wait); 139 140 r = crypto_wait_req(crypto_ahash_init(req), wait); 141 142 if (unlikely(r < 0)) { 143 DMERR("crypto_ahash_init failed: %d", r); 144 return r; 145 } 146 147 if (likely(v->salt_size && (v->version >= 1))) 148 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 149 150 return r; 151 } 152 153 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req, 154 u8 *digest, struct crypto_wait *wait) 155 { 156 int r; 157 158 if (unlikely(v->salt_size && (!v->version))) { 159 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 160 161 if (r < 0) { 162 DMERR("verity_hash_final failed updating salt: %d", r); 163 goto out; 164 } 165 } 166 167 ahash_request_set_crypt(req, NULL, digest, 0); 168 r = crypto_wait_req(crypto_ahash_final(req), wait); 169 out: 170 return r; 171 } 172 173 int verity_hash(struct dm_verity *v, struct ahash_request *req, 174 const u8 *data, size_t len, u8 *digest) 175 { 176 int r; 177 struct crypto_wait wait; 178 179 r = verity_hash_init(v, req, &wait); 180 if (unlikely(r < 0)) 181 goto out; 182 183 r = verity_hash_update(v, req, data, len, &wait); 184 if (unlikely(r < 0)) 185 goto out; 186 187 r = verity_hash_final(v, req, digest, &wait); 188 189 out: 190 return r; 191 } 192 193 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 194 sector_t *hash_block, unsigned *offset) 195 { 196 sector_t position = verity_position_at_level(v, block, level); 197 unsigned idx; 198 199 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 200 201 if (!offset) 202 return; 203 204 idx = position & ((1 << v->hash_per_block_bits) - 1); 205 if (!v->version) 206 *offset = idx * v->digest_size; 207 else 208 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 209 } 210 211 /* 212 * Handle verification errors. 213 */ 214 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 215 unsigned long long block) 216 { 217 char verity_env[DM_VERITY_ENV_LENGTH]; 218 char *envp[] = { verity_env, NULL }; 219 const char *type_str = ""; 220 struct mapped_device *md = dm_table_get_md(v->ti->table); 221 222 /* Corruption should be visible in device status in all modes */ 223 v->hash_failed = 1; 224 225 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 226 goto out; 227 228 v->corrupted_errs++; 229 230 switch (type) { 231 case DM_VERITY_BLOCK_TYPE_DATA: 232 type_str = "data"; 233 break; 234 case DM_VERITY_BLOCK_TYPE_METADATA: 235 type_str = "metadata"; 236 break; 237 default: 238 BUG(); 239 } 240 241 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 242 type_str, block); 243 244 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) 245 DMERR("%s: reached maximum errors", v->data_dev->name); 246 247 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 248 DM_VERITY_ENV_VAR_NAME, type, block); 249 250 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 251 252 out: 253 if (v->mode == DM_VERITY_MODE_LOGGING) 254 return 0; 255 256 if (v->mode == DM_VERITY_MODE_RESTART) 257 kernel_restart("dm-verity device corrupted"); 258 259 if (v->mode == DM_VERITY_MODE_PANIC) 260 panic("dm-verity device corrupted"); 261 262 return 1; 263 } 264 265 /* 266 * Verify hash of a metadata block pertaining to the specified data block 267 * ("block" argument) at a specified level ("level" argument). 268 * 269 * On successful return, verity_io_want_digest(v, io) contains the hash value 270 * for a lower tree level or for the data block (if we're at the lowest level). 271 * 272 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 273 * If "skip_unverified" is false, unverified buffer is hashed and verified 274 * against current value of verity_io_want_digest(v, io). 275 */ 276 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 277 sector_t block, int level, bool skip_unverified, 278 u8 *want_digest) 279 { 280 struct dm_buffer *buf; 281 struct buffer_aux *aux; 282 u8 *data; 283 int r; 284 sector_t hash_block; 285 unsigned offset; 286 287 verity_hash_at_level(v, block, level, &hash_block, &offset); 288 289 data = dm_bufio_read(v->bufio, hash_block, &buf); 290 if (IS_ERR(data)) 291 return PTR_ERR(data); 292 293 aux = dm_bufio_get_aux_data(buf); 294 295 if (!aux->hash_verified) { 296 if (skip_unverified) { 297 r = 1; 298 goto release_ret_r; 299 } 300 301 r = verity_hash(v, verity_io_hash_req(v, io), 302 data, 1 << v->hash_dev_block_bits, 303 verity_io_real_digest(v, io)); 304 if (unlikely(r < 0)) 305 goto release_ret_r; 306 307 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 308 v->digest_size) == 0)) 309 aux->hash_verified = 1; 310 else if (verity_fec_decode(v, io, 311 DM_VERITY_BLOCK_TYPE_METADATA, 312 hash_block, data, NULL) == 0) 313 aux->hash_verified = 1; 314 else if (verity_handle_err(v, 315 DM_VERITY_BLOCK_TYPE_METADATA, 316 hash_block)) { 317 r = -EIO; 318 goto release_ret_r; 319 } 320 } 321 322 data += offset; 323 memcpy(want_digest, data, v->digest_size); 324 r = 0; 325 326 release_ret_r: 327 dm_bufio_release(buf); 328 return r; 329 } 330 331 /* 332 * Find a hash for a given block, write it to digest and verify the integrity 333 * of the hash tree if necessary. 334 */ 335 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 336 sector_t block, u8 *digest, bool *is_zero) 337 { 338 int r = 0, i; 339 340 if (likely(v->levels)) { 341 /* 342 * First, we try to get the requested hash for 343 * the current block. If the hash block itself is 344 * verified, zero is returned. If it isn't, this 345 * function returns 1 and we fall back to whole 346 * chain verification. 347 */ 348 r = verity_verify_level(v, io, block, 0, true, digest); 349 if (likely(r <= 0)) 350 goto out; 351 } 352 353 memcpy(digest, v->root_digest, v->digest_size); 354 355 for (i = v->levels - 1; i >= 0; i--) { 356 r = verity_verify_level(v, io, block, i, false, digest); 357 if (unlikely(r)) 358 goto out; 359 } 360 out: 361 if (!r && v->zero_digest) 362 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 363 else 364 *is_zero = false; 365 366 return r; 367 } 368 369 /* 370 * Calculates the digest for the given bio 371 */ 372 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, 373 struct bvec_iter *iter, struct crypto_wait *wait) 374 { 375 unsigned int todo = 1 << v->data_dev_block_bits; 376 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 377 struct scatterlist sg; 378 struct ahash_request *req = verity_io_hash_req(v, io); 379 380 do { 381 int r; 382 unsigned int len; 383 struct bio_vec bv = bio_iter_iovec(bio, *iter); 384 385 sg_init_table(&sg, 1); 386 387 len = bv.bv_len; 388 389 if (likely(len >= todo)) 390 len = todo; 391 /* 392 * Operating on a single page at a time looks suboptimal 393 * until you consider the typical block size is 4,096B. 394 * Going through this loops twice should be very rare. 395 */ 396 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset); 397 ahash_request_set_crypt(req, &sg, NULL, len); 398 r = crypto_wait_req(crypto_ahash_update(req), wait); 399 400 if (unlikely(r < 0)) { 401 DMERR("verity_for_io_block crypto op failed: %d", r); 402 return r; 403 } 404 405 bio_advance_iter(bio, iter, len); 406 todo -= len; 407 } while (todo); 408 409 return 0; 410 } 411 412 /* 413 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 414 * starting from iter. 415 */ 416 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 417 struct bvec_iter *iter, 418 int (*process)(struct dm_verity *v, 419 struct dm_verity_io *io, u8 *data, 420 size_t len)) 421 { 422 unsigned todo = 1 << v->data_dev_block_bits; 423 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 424 425 do { 426 int r; 427 u8 *page; 428 unsigned len; 429 struct bio_vec bv = bio_iter_iovec(bio, *iter); 430 431 page = bvec_kmap_local(&bv); 432 len = bv.bv_len; 433 434 if (likely(len >= todo)) 435 len = todo; 436 437 r = process(v, io, page, len); 438 kunmap_local(page); 439 440 if (r < 0) 441 return r; 442 443 bio_advance_iter(bio, iter, len); 444 todo -= len; 445 } while (todo); 446 447 return 0; 448 } 449 450 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 451 u8 *data, size_t len) 452 { 453 memset(data, 0, len); 454 return 0; 455 } 456 457 /* 458 * Moves the bio iter one data block forward. 459 */ 460 static inline void verity_bv_skip_block(struct dm_verity *v, 461 struct dm_verity_io *io, 462 struct bvec_iter *iter) 463 { 464 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 465 466 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits); 467 } 468 469 /* 470 * Verify one "dm_verity_io" structure. 471 */ 472 static int verity_verify_io(struct dm_verity_io *io) 473 { 474 bool is_zero; 475 struct dm_verity *v = io->v; 476 struct bvec_iter start; 477 unsigned b; 478 struct crypto_wait wait; 479 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 480 481 for (b = 0; b < io->n_blocks; b++) { 482 int r; 483 sector_t cur_block = io->block + b; 484 struct ahash_request *req = verity_io_hash_req(v, io); 485 486 if (v->validated_blocks && 487 likely(test_bit(cur_block, v->validated_blocks))) { 488 verity_bv_skip_block(v, io, &io->iter); 489 continue; 490 } 491 492 r = verity_hash_for_block(v, io, cur_block, 493 verity_io_want_digest(v, io), 494 &is_zero); 495 if (unlikely(r < 0)) 496 return r; 497 498 if (is_zero) { 499 /* 500 * If we expect a zero block, don't validate, just 501 * return zeros. 502 */ 503 r = verity_for_bv_block(v, io, &io->iter, 504 verity_bv_zero); 505 if (unlikely(r < 0)) 506 return r; 507 508 continue; 509 } 510 511 r = verity_hash_init(v, req, &wait); 512 if (unlikely(r < 0)) 513 return r; 514 515 start = io->iter; 516 r = verity_for_io_block(v, io, &io->iter, &wait); 517 if (unlikely(r < 0)) 518 return r; 519 520 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 521 &wait); 522 if (unlikely(r < 0)) 523 return r; 524 525 if (likely(memcmp(verity_io_real_digest(v, io), 526 verity_io_want_digest(v, io), v->digest_size) == 0)) { 527 if (v->validated_blocks) 528 set_bit(cur_block, v->validated_blocks); 529 continue; 530 } 531 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, 532 cur_block, NULL, &start) == 0) 533 continue; 534 else { 535 if (bio->bi_status) { 536 /* 537 * Error correction failed; Just return error 538 */ 539 return -EIO; 540 } 541 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, 542 cur_block)) 543 return -EIO; 544 } 545 } 546 547 return 0; 548 } 549 550 /* 551 * Skip verity work in response to I/O error when system is shutting down. 552 */ 553 static inline bool verity_is_system_shutting_down(void) 554 { 555 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 556 || system_state == SYSTEM_RESTART; 557 } 558 559 /* 560 * End one "io" structure with a given error. 561 */ 562 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 563 { 564 struct dm_verity *v = io->v; 565 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 566 567 bio->bi_end_io = io->orig_bi_end_io; 568 bio->bi_status = status; 569 570 verity_fec_finish_io(io); 571 572 bio_endio(bio); 573 } 574 575 static void verity_work(struct work_struct *w) 576 { 577 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 578 579 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 580 } 581 582 static void verity_end_io(struct bio *bio) 583 { 584 struct dm_verity_io *io = bio->bi_private; 585 586 if (bio->bi_status && 587 (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) { 588 verity_finish_io(io, bio->bi_status); 589 return; 590 } 591 592 INIT_WORK(&io->work, verity_work); 593 queue_work(io->v->verify_wq, &io->work); 594 } 595 596 /* 597 * Prefetch buffers for the specified io. 598 * The root buffer is not prefetched, it is assumed that it will be cached 599 * all the time. 600 */ 601 static void verity_prefetch_io(struct work_struct *work) 602 { 603 struct dm_verity_prefetch_work *pw = 604 container_of(work, struct dm_verity_prefetch_work, work); 605 struct dm_verity *v = pw->v; 606 int i; 607 608 for (i = v->levels - 2; i >= 0; i--) { 609 sector_t hash_block_start; 610 sector_t hash_block_end; 611 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 612 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 613 if (!i) { 614 unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster); 615 616 cluster >>= v->data_dev_block_bits; 617 if (unlikely(!cluster)) 618 goto no_prefetch_cluster; 619 620 if (unlikely(cluster & (cluster - 1))) 621 cluster = 1 << __fls(cluster); 622 623 hash_block_start &= ~(sector_t)(cluster - 1); 624 hash_block_end |= cluster - 1; 625 if (unlikely(hash_block_end >= v->hash_blocks)) 626 hash_block_end = v->hash_blocks - 1; 627 } 628 no_prefetch_cluster: 629 dm_bufio_prefetch(v->bufio, hash_block_start, 630 hash_block_end - hash_block_start + 1); 631 } 632 633 kfree(pw); 634 } 635 636 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io) 637 { 638 sector_t block = io->block; 639 unsigned int n_blocks = io->n_blocks; 640 struct dm_verity_prefetch_work *pw; 641 642 if (v->validated_blocks) { 643 while (n_blocks && test_bit(block, v->validated_blocks)) { 644 block++; 645 n_blocks--; 646 } 647 while (n_blocks && test_bit(block + n_blocks - 1, 648 v->validated_blocks)) 649 n_blocks--; 650 if (!n_blocks) 651 return; 652 } 653 654 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 655 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 656 657 if (!pw) 658 return; 659 660 INIT_WORK(&pw->work, verity_prefetch_io); 661 pw->v = v; 662 pw->block = block; 663 pw->n_blocks = n_blocks; 664 queue_work(v->verify_wq, &pw->work); 665 } 666 667 /* 668 * Bio map function. It allocates dm_verity_io structure and bio vector and 669 * fills them. Then it issues prefetches and the I/O. 670 */ 671 static int verity_map(struct dm_target *ti, struct bio *bio) 672 { 673 struct dm_verity *v = ti->private; 674 struct dm_verity_io *io; 675 676 bio_set_dev(bio, v->data_dev->bdev); 677 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 678 679 if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) & 680 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 681 DMERR_LIMIT("unaligned io"); 682 return DM_MAPIO_KILL; 683 } 684 685 if (bio_end_sector(bio) >> 686 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 687 DMERR_LIMIT("io out of range"); 688 return DM_MAPIO_KILL; 689 } 690 691 if (bio_data_dir(bio) == WRITE) 692 return DM_MAPIO_KILL; 693 694 io = dm_per_bio_data(bio, ti->per_io_data_size); 695 io->v = v; 696 io->orig_bi_end_io = bio->bi_end_io; 697 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 698 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 699 700 bio->bi_end_io = verity_end_io; 701 bio->bi_private = io; 702 io->iter = bio->bi_iter; 703 704 verity_fec_init_io(io); 705 706 verity_submit_prefetch(v, io); 707 708 submit_bio_noacct(bio); 709 710 return DM_MAPIO_SUBMITTED; 711 } 712 713 /* 714 * Status: V (valid) or C (corruption found) 715 */ 716 static void verity_status(struct dm_target *ti, status_type_t type, 717 unsigned status_flags, char *result, unsigned maxlen) 718 { 719 struct dm_verity *v = ti->private; 720 unsigned args = 0; 721 unsigned sz = 0; 722 unsigned x; 723 724 switch (type) { 725 case STATUSTYPE_INFO: 726 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 727 break; 728 case STATUSTYPE_TABLE: 729 DMEMIT("%u %s %s %u %u %llu %llu %s ", 730 v->version, 731 v->data_dev->name, 732 v->hash_dev->name, 733 1 << v->data_dev_block_bits, 734 1 << v->hash_dev_block_bits, 735 (unsigned long long)v->data_blocks, 736 (unsigned long long)v->hash_start, 737 v->alg_name 738 ); 739 for (x = 0; x < v->digest_size; x++) 740 DMEMIT("%02x", v->root_digest[x]); 741 DMEMIT(" "); 742 if (!v->salt_size) 743 DMEMIT("-"); 744 else 745 for (x = 0; x < v->salt_size; x++) 746 DMEMIT("%02x", v->salt[x]); 747 if (v->mode != DM_VERITY_MODE_EIO) 748 args++; 749 if (verity_fec_is_enabled(v)) 750 args += DM_VERITY_OPTS_FEC; 751 if (v->zero_digest) 752 args++; 753 if (v->validated_blocks) 754 args++; 755 if (v->signature_key_desc) 756 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 757 if (!args) 758 return; 759 DMEMIT(" %u", args); 760 if (v->mode != DM_VERITY_MODE_EIO) { 761 DMEMIT(" "); 762 switch (v->mode) { 763 case DM_VERITY_MODE_LOGGING: 764 DMEMIT(DM_VERITY_OPT_LOGGING); 765 break; 766 case DM_VERITY_MODE_RESTART: 767 DMEMIT(DM_VERITY_OPT_RESTART); 768 break; 769 case DM_VERITY_MODE_PANIC: 770 DMEMIT(DM_VERITY_OPT_PANIC); 771 break; 772 default: 773 BUG(); 774 } 775 } 776 if (v->zero_digest) 777 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 778 if (v->validated_blocks) 779 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 780 sz = verity_fec_status_table(v, sz, result, maxlen); 781 if (v->signature_key_desc) 782 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 783 " %s", v->signature_key_desc); 784 break; 785 786 case STATUSTYPE_IMA: 787 DMEMIT_TARGET_NAME_VERSION(ti->type); 788 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 789 DMEMIT(",verity_version=%u", v->version); 790 DMEMIT(",data_device_name=%s", v->data_dev->name); 791 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 792 DMEMIT(",verity_algorithm=%s", v->alg_name); 793 794 DMEMIT(",root_digest="); 795 for (x = 0; x < v->digest_size; x++) 796 DMEMIT("%02x", v->root_digest[x]); 797 798 DMEMIT(",salt="); 799 if (!v->salt_size) 800 DMEMIT("-"); 801 else 802 for (x = 0; x < v->salt_size; x++) 803 DMEMIT("%02x", v->salt[x]); 804 805 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 806 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 807 if (v->signature_key_desc) 808 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 809 810 if (v->mode != DM_VERITY_MODE_EIO) { 811 DMEMIT(",verity_mode="); 812 switch (v->mode) { 813 case DM_VERITY_MODE_LOGGING: 814 DMEMIT(DM_VERITY_OPT_LOGGING); 815 break; 816 case DM_VERITY_MODE_RESTART: 817 DMEMIT(DM_VERITY_OPT_RESTART); 818 break; 819 case DM_VERITY_MODE_PANIC: 820 DMEMIT(DM_VERITY_OPT_PANIC); 821 break; 822 default: 823 DMEMIT("invalid"); 824 } 825 } 826 DMEMIT(";"); 827 break; 828 } 829 } 830 831 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 832 { 833 struct dm_verity *v = ti->private; 834 835 *bdev = v->data_dev->bdev; 836 837 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 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