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 #include <linux/string.h> 23 24 #define DM_MSG_PREFIX "verity" 25 26 #define DM_VERITY_ENV_LENGTH 42 27 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 28 29 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 30 31 #define DM_VERITY_MAX_CORRUPTED_ERRS 100 32 33 #define DM_VERITY_OPT_LOGGING "ignore_corruption" 34 #define DM_VERITY_OPT_RESTART "restart_on_corruption" 35 #define DM_VERITY_OPT_PANIC "panic_on_corruption" 36 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 37 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 38 39 #define DM_VERITY_OPTS_MAX (3 + DM_VERITY_OPTS_FEC + \ 40 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 41 42 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 43 44 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR); 45 46 struct dm_verity_prefetch_work { 47 struct work_struct work; 48 struct dm_verity *v; 49 sector_t block; 50 unsigned n_blocks; 51 }; 52 53 /* 54 * Auxiliary structure appended to each dm-bufio buffer. If the value 55 * hash_verified is nonzero, hash of the block has been verified. 56 * 57 * The variable hash_verified is set to 0 when allocating the buffer, then 58 * it can be changed to 1 and it is never reset to 0 again. 59 * 60 * There is no lock around this value, a race condition can at worst cause 61 * that multiple processes verify the hash of the same buffer simultaneously 62 * and write 1 to hash_verified simultaneously. 63 * This condition is harmless, so we don't need locking. 64 */ 65 struct buffer_aux { 66 int hash_verified; 67 }; 68 69 /* 70 * Initialize struct buffer_aux for a freshly created buffer. 71 */ 72 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 73 { 74 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 75 76 aux->hash_verified = 0; 77 } 78 79 /* 80 * Translate input sector number to the sector number on the target device. 81 */ 82 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 83 { 84 return v->data_start + dm_target_offset(v->ti, bi_sector); 85 } 86 87 /* 88 * Return hash position of a specified block at a specified tree level 89 * (0 is the lowest level). 90 * The lowest "hash_per_block_bits"-bits of the result denote hash position 91 * inside a hash block. The remaining bits denote location of the hash block. 92 */ 93 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 94 int level) 95 { 96 return block >> (level * v->hash_per_block_bits); 97 } 98 99 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req, 100 const u8 *data, size_t len, 101 struct crypto_wait *wait) 102 { 103 struct scatterlist sg; 104 105 if (likely(!is_vmalloc_addr(data))) { 106 sg_init_one(&sg, data, len); 107 ahash_request_set_crypt(req, &sg, NULL, len); 108 return crypto_wait_req(crypto_ahash_update(req), wait); 109 } else { 110 do { 111 int r; 112 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 113 flush_kernel_vmap_range((void *)data, this_step); 114 sg_init_table(&sg, 1); 115 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 116 ahash_request_set_crypt(req, &sg, NULL, this_step); 117 r = crypto_wait_req(crypto_ahash_update(req), wait); 118 if (unlikely(r)) 119 return r; 120 data += this_step; 121 len -= this_step; 122 } while (len); 123 return 0; 124 } 125 } 126 127 /* 128 * Wrapper for crypto_ahash_init, which handles verity salting. 129 */ 130 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req, 131 struct crypto_wait *wait) 132 { 133 int r; 134 135 ahash_request_set_tfm(req, v->tfm); 136 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | 137 CRYPTO_TFM_REQ_MAY_BACKLOG, 138 crypto_req_done, (void *)wait); 139 crypto_init_wait(wait); 140 141 r = crypto_wait_req(crypto_ahash_init(req), wait); 142 143 if (unlikely(r < 0)) { 144 DMERR("crypto_ahash_init failed: %d", r); 145 return r; 146 } 147 148 if (likely(v->salt_size && (v->version >= 1))) 149 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 150 151 return r; 152 } 153 154 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req, 155 u8 *digest, struct crypto_wait *wait) 156 { 157 int r; 158 159 if (unlikely(v->salt_size && (!v->version))) { 160 r = verity_hash_update(v, req, v->salt, v->salt_size, wait); 161 162 if (r < 0) { 163 DMERR("verity_hash_final failed updating salt: %d", r); 164 goto out; 165 } 166 } 167 168 ahash_request_set_crypt(req, NULL, digest, 0); 169 r = crypto_wait_req(crypto_ahash_final(req), wait); 170 out: 171 return r; 172 } 173 174 int verity_hash(struct dm_verity *v, struct ahash_request *req, 175 const u8 *data, size_t len, u8 *digest) 176 { 177 int r; 178 struct crypto_wait wait; 179 180 r = verity_hash_init(v, req, &wait); 181 if (unlikely(r < 0)) 182 goto out; 183 184 r = verity_hash_update(v, req, data, len, &wait); 185 if (unlikely(r < 0)) 186 goto out; 187 188 r = verity_hash_final(v, req, digest, &wait); 189 190 out: 191 return r; 192 } 193 194 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 195 sector_t *hash_block, unsigned *offset) 196 { 197 sector_t position = verity_position_at_level(v, block, level); 198 unsigned idx; 199 200 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 201 202 if (!offset) 203 return; 204 205 idx = position & ((1 << v->hash_per_block_bits) - 1); 206 if (!v->version) 207 *offset = idx * v->digest_size; 208 else 209 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 210 } 211 212 /* 213 * Handle verification errors. 214 */ 215 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 216 unsigned long long block) 217 { 218 char verity_env[DM_VERITY_ENV_LENGTH]; 219 char *envp[] = { verity_env, NULL }; 220 const char *type_str = ""; 221 struct mapped_device *md = dm_table_get_md(v->ti->table); 222 223 /* Corruption should be visible in device status in all modes */ 224 v->hash_failed = 1; 225 226 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 227 goto out; 228 229 v->corrupted_errs++; 230 231 switch (type) { 232 case DM_VERITY_BLOCK_TYPE_DATA: 233 type_str = "data"; 234 break; 235 case DM_VERITY_BLOCK_TYPE_METADATA: 236 type_str = "metadata"; 237 break; 238 default: 239 BUG(); 240 } 241 242 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 243 type_str, block); 244 245 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) 246 DMERR("%s: reached maximum errors", v->data_dev->name); 247 248 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 249 DM_VERITY_ENV_VAR_NAME, type, block); 250 251 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 252 253 out: 254 if (v->mode == DM_VERITY_MODE_LOGGING) 255 return 0; 256 257 if (v->mode == DM_VERITY_MODE_RESTART) 258 kernel_restart("dm-verity device corrupted"); 259 260 if (v->mode == DM_VERITY_MODE_PANIC) 261 panic("dm-verity device corrupted"); 262 263 return 1; 264 } 265 266 /* 267 * Verify hash of a metadata block pertaining to the specified data block 268 * ("block" argument) at a specified level ("level" argument). 269 * 270 * On successful return, verity_io_want_digest(v, io) contains the hash value 271 * for a lower tree level or for the data block (if we're at the lowest level). 272 * 273 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 274 * If "skip_unverified" is false, unverified buffer is hashed and verified 275 * against current value of verity_io_want_digest(v, io). 276 */ 277 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 278 sector_t block, int level, bool skip_unverified, 279 u8 *want_digest) 280 { 281 struct dm_buffer *buf; 282 struct buffer_aux *aux; 283 u8 *data; 284 int r; 285 sector_t hash_block; 286 unsigned offset; 287 288 verity_hash_at_level(v, block, level, &hash_block, &offset); 289 290 data = dm_bufio_read(v->bufio, hash_block, &buf); 291 if (IS_ERR(data)) 292 return PTR_ERR(data); 293 294 aux = dm_bufio_get_aux_data(buf); 295 296 if (!aux->hash_verified) { 297 if (skip_unverified) { 298 r = 1; 299 goto release_ret_r; 300 } 301 302 r = verity_hash(v, verity_io_hash_req(v, io), 303 data, 1 << v->hash_dev_block_bits, 304 verity_io_real_digest(v, io)); 305 if (unlikely(r < 0)) 306 goto release_ret_r; 307 308 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 309 v->digest_size) == 0)) 310 aux->hash_verified = 1; 311 else if (verity_fec_decode(v, io, 312 DM_VERITY_BLOCK_TYPE_METADATA, 313 hash_block, data, NULL) == 0) 314 aux->hash_verified = 1; 315 else if (verity_handle_err(v, 316 DM_VERITY_BLOCK_TYPE_METADATA, 317 hash_block)) { 318 r = -EIO; 319 goto release_ret_r; 320 } 321 } 322 323 data += offset; 324 memcpy(want_digest, data, v->digest_size); 325 r = 0; 326 327 release_ret_r: 328 dm_bufio_release(buf); 329 return r; 330 } 331 332 /* 333 * Find a hash for a given block, write it to digest and verify the integrity 334 * of the hash tree if necessary. 335 */ 336 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 337 sector_t block, u8 *digest, bool *is_zero) 338 { 339 int r = 0, i; 340 341 if (likely(v->levels)) { 342 /* 343 * First, we try to get the requested hash for 344 * the current block. If the hash block itself is 345 * verified, zero is returned. If it isn't, this 346 * function returns 1 and we fall back to whole 347 * chain verification. 348 */ 349 r = verity_verify_level(v, io, block, 0, true, digest); 350 if (likely(r <= 0)) 351 goto out; 352 } 353 354 memcpy(digest, v->root_digest, v->digest_size); 355 356 for (i = v->levels - 1; i >= 0; i--) { 357 r = verity_verify_level(v, io, block, i, false, digest); 358 if (unlikely(r)) 359 goto out; 360 } 361 out: 362 if (!r && v->zero_digest) 363 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 364 else 365 *is_zero = false; 366 367 return r; 368 } 369 370 /* 371 * Calculates the digest for the given bio 372 */ 373 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io, 374 struct bvec_iter *iter, struct crypto_wait *wait) 375 { 376 unsigned int todo = 1 << v->data_dev_block_bits; 377 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 378 struct scatterlist sg; 379 struct ahash_request *req = verity_io_hash_req(v, io); 380 381 do { 382 int r; 383 unsigned int len; 384 struct bio_vec bv = bio_iter_iovec(bio, *iter); 385 386 sg_init_table(&sg, 1); 387 388 len = bv.bv_len; 389 390 if (likely(len >= todo)) 391 len = todo; 392 /* 393 * Operating on a single page at a time looks suboptimal 394 * until you consider the typical block size is 4,096B. 395 * Going through this loops twice should be very rare. 396 */ 397 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset); 398 ahash_request_set_crypt(req, &sg, NULL, len); 399 r = crypto_wait_req(crypto_ahash_update(req), wait); 400 401 if (unlikely(r < 0)) { 402 DMERR("verity_for_io_block crypto op failed: %d", r); 403 return r; 404 } 405 406 bio_advance_iter(bio, iter, len); 407 todo -= len; 408 } while (todo); 409 410 return 0; 411 } 412 413 /* 414 * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec 415 * starting from iter. 416 */ 417 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io, 418 struct bvec_iter *iter, 419 int (*process)(struct dm_verity *v, 420 struct dm_verity_io *io, u8 *data, 421 size_t len)) 422 { 423 unsigned todo = 1 << v->data_dev_block_bits; 424 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 425 426 do { 427 int r; 428 u8 *page; 429 unsigned len; 430 struct bio_vec bv = bio_iter_iovec(bio, *iter); 431 432 page = bvec_kmap_local(&bv); 433 len = bv.bv_len; 434 435 if (likely(len >= todo)) 436 len = todo; 437 438 r = process(v, io, page, len); 439 kunmap_local(page); 440 441 if (r < 0) 442 return r; 443 444 bio_advance_iter(bio, iter, len); 445 todo -= len; 446 } while (todo); 447 448 return 0; 449 } 450 451 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io, 452 u8 *data, size_t len) 453 { 454 memset(data, 0, len); 455 return 0; 456 } 457 458 /* 459 * Moves the bio iter one data block forward. 460 */ 461 static inline void verity_bv_skip_block(struct dm_verity *v, 462 struct dm_verity_io *io, 463 struct bvec_iter *iter) 464 { 465 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 466 467 bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits); 468 } 469 470 /* 471 * Verify one "dm_verity_io" structure. 472 */ 473 static int verity_verify_io(struct dm_verity_io *io) 474 { 475 bool is_zero; 476 struct dm_verity *v = io->v; 477 struct bvec_iter start; 478 unsigned b; 479 struct crypto_wait wait; 480 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 481 482 for (b = 0; b < io->n_blocks; b++) { 483 int r; 484 sector_t cur_block = io->block + b; 485 struct ahash_request *req = verity_io_hash_req(v, io); 486 487 if (v->validated_blocks && 488 likely(test_bit(cur_block, v->validated_blocks))) { 489 verity_bv_skip_block(v, io, &io->iter); 490 continue; 491 } 492 493 r = verity_hash_for_block(v, io, cur_block, 494 verity_io_want_digest(v, io), 495 &is_zero); 496 if (unlikely(r < 0)) 497 return r; 498 499 if (is_zero) { 500 /* 501 * If we expect a zero block, don't validate, just 502 * return zeros. 503 */ 504 r = verity_for_bv_block(v, io, &io->iter, 505 verity_bv_zero); 506 if (unlikely(r < 0)) 507 return r; 508 509 continue; 510 } 511 512 r = verity_hash_init(v, req, &wait); 513 if (unlikely(r < 0)) 514 return r; 515 516 start = io->iter; 517 r = verity_for_io_block(v, io, &io->iter, &wait); 518 if (unlikely(r < 0)) 519 return r; 520 521 r = verity_hash_final(v, req, verity_io_real_digest(v, io), 522 &wait); 523 if (unlikely(r < 0)) 524 return r; 525 526 if (likely(memcmp(verity_io_real_digest(v, io), 527 verity_io_want_digest(v, io), v->digest_size) == 0)) { 528 if (v->validated_blocks) 529 set_bit(cur_block, v->validated_blocks); 530 continue; 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 /* 1314 * Check whether a DM target is a verity target. 1315 */ 1316 bool dm_is_verity_target(struct dm_target *ti) 1317 { 1318 return ti->type->module == THIS_MODULE; 1319 } 1320 1321 /* 1322 * Get the root digest of a verity target. 1323 * 1324 * Returns a copy of the root digest, the caller is responsible for 1325 * freeing the memory of the digest. 1326 */ 1327 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1328 { 1329 struct dm_verity *v = ti->private; 1330 1331 if (!dm_is_verity_target(ti)) 1332 return -EINVAL; 1333 1334 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1335 if (*root_digest == NULL) 1336 return -ENOMEM; 1337 1338 *digest_size = v->digest_size; 1339 1340 return 0; 1341 } 1342 1343 static struct target_type verity_target = { 1344 .name = "verity", 1345 .features = DM_TARGET_IMMUTABLE, 1346 .version = {1, 8, 1}, 1347 .module = THIS_MODULE, 1348 .ctr = verity_ctr, 1349 .dtr = verity_dtr, 1350 .map = verity_map, 1351 .status = verity_status, 1352 .prepare_ioctl = verity_prepare_ioctl, 1353 .iterate_devices = verity_iterate_devices, 1354 .io_hints = verity_io_hints, 1355 }; 1356 1357 static int __init dm_verity_init(void) 1358 { 1359 int r; 1360 1361 r = dm_register_target(&verity_target); 1362 if (r < 0) 1363 DMERR("register failed %d", r); 1364 1365 return r; 1366 } 1367 1368 static void __exit dm_verity_exit(void) 1369 { 1370 dm_unregister_target(&verity_target); 1371 } 1372 1373 module_init(dm_verity_init); 1374 module_exit(dm_verity_exit); 1375 1376 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1377 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1378 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1379 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1380 MODULE_LICENSE("GPL"); 1381