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