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 "dm-audit.h" 20 #include <linux/module.h> 21 #include <linux/reboot.h> 22 #include <linux/scatterlist.h> 23 #include <linux/string.h> 24 #include <linux/jump_label.h> 25 26 #define DM_MSG_PREFIX "verity" 27 28 #define DM_VERITY_ENV_LENGTH 42 29 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 30 31 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 32 33 #define DM_VERITY_MAX_CORRUPTED_ERRS 100 34 35 #define DM_VERITY_OPT_LOGGING "ignore_corruption" 36 #define DM_VERITY_OPT_RESTART "restart_on_corruption" 37 #define DM_VERITY_OPT_PANIC "panic_on_corruption" 38 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 39 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 40 #define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet" 41 42 #define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \ 43 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 44 45 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 46 47 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644); 48 49 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled); 50 51 /* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */ 52 static DEFINE_STATIC_KEY_FALSE(ahash_enabled); 53 54 struct dm_verity_prefetch_work { 55 struct work_struct work; 56 struct dm_verity *v; 57 unsigned short ioprio; 58 sector_t block; 59 unsigned int n_blocks; 60 }; 61 62 /* 63 * Auxiliary structure appended to each dm-bufio buffer. If the value 64 * hash_verified is nonzero, hash of the block has been verified. 65 * 66 * The variable hash_verified is set to 0 when allocating the buffer, then 67 * it can be changed to 1 and it is never reset to 0 again. 68 * 69 * There is no lock around this value, a race condition can at worst cause 70 * that multiple processes verify the hash of the same buffer simultaneously 71 * and write 1 to hash_verified simultaneously. 72 * This condition is harmless, so we don't need locking. 73 */ 74 struct buffer_aux { 75 int hash_verified; 76 }; 77 78 /* 79 * Initialize struct buffer_aux for a freshly created buffer. 80 */ 81 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 82 { 83 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 84 85 aux->hash_verified = 0; 86 } 87 88 /* 89 * Translate input sector number to the sector number on the target device. 90 */ 91 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 92 { 93 return v->data_start + dm_target_offset(v->ti, bi_sector); 94 } 95 96 /* 97 * Return hash position of a specified block at a specified tree level 98 * (0 is the lowest level). 99 * The lowest "hash_per_block_bits"-bits of the result denote hash position 100 * inside a hash block. The remaining bits denote location of the hash block. 101 */ 102 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 103 int level) 104 { 105 return block >> (level * v->hash_per_block_bits); 106 } 107 108 static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req, 109 const u8 *data, size_t len, 110 struct crypto_wait *wait) 111 { 112 struct scatterlist sg; 113 114 if (likely(!is_vmalloc_addr(data))) { 115 sg_init_one(&sg, data, len); 116 ahash_request_set_crypt(req, &sg, NULL, len); 117 return crypto_wait_req(crypto_ahash_update(req), wait); 118 } 119 120 do { 121 int r; 122 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 123 124 flush_kernel_vmap_range((void *)data, this_step); 125 sg_init_table(&sg, 1); 126 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 127 ahash_request_set_crypt(req, &sg, NULL, this_step); 128 r = crypto_wait_req(crypto_ahash_update(req), wait); 129 if (unlikely(r)) 130 return r; 131 data += this_step; 132 len -= this_step; 133 } while (len); 134 135 return 0; 136 } 137 138 /* 139 * Wrapper for crypto_ahash_init, which handles verity salting. 140 */ 141 static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req, 142 struct crypto_wait *wait, bool may_sleep) 143 { 144 int r; 145 146 ahash_request_set_tfm(req, v->ahash_tfm); 147 ahash_request_set_callback(req, 148 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0, 149 crypto_req_done, (void *)wait); 150 crypto_init_wait(wait); 151 152 r = crypto_wait_req(crypto_ahash_init(req), wait); 153 154 if (unlikely(r < 0)) { 155 if (r != -ENOMEM) 156 DMERR("crypto_ahash_init failed: %d", r); 157 return r; 158 } 159 160 if (likely(v->salt_size && (v->version >= 1))) 161 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait); 162 163 return r; 164 } 165 166 static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req, 167 u8 *digest, struct crypto_wait *wait) 168 { 169 int r; 170 171 if (unlikely(v->salt_size && (!v->version))) { 172 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait); 173 174 if (r < 0) { 175 DMERR("%s failed updating salt: %d", __func__, r); 176 goto out; 177 } 178 } 179 180 ahash_request_set_crypt(req, NULL, digest, 0); 181 r = crypto_wait_req(crypto_ahash_final(req), wait); 182 out: 183 return r; 184 } 185 186 int verity_hash(struct dm_verity *v, struct dm_verity_io *io, 187 const u8 *data, size_t len, u8 *digest, bool may_sleep) 188 { 189 int r; 190 191 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) { 192 struct ahash_request *req = verity_io_hash_req(v, io); 193 struct crypto_wait wait; 194 195 r = verity_ahash_init(v, req, &wait, may_sleep) ?: 196 verity_ahash_update(v, req, data, len, &wait) ?: 197 verity_ahash_final(v, req, digest, &wait); 198 } else { 199 struct shash_desc *desc = verity_io_hash_req(v, io); 200 201 desc->tfm = v->shash_tfm; 202 r = crypto_shash_import(desc, v->initial_hashstate) ?: 203 crypto_shash_finup(desc, data, len, digest); 204 } 205 if (unlikely(r)) 206 DMERR("Error hashing block: %d", r); 207 return r; 208 } 209 210 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 211 sector_t *hash_block, unsigned int *offset) 212 { 213 sector_t position = verity_position_at_level(v, block, level); 214 unsigned int idx; 215 216 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 217 218 if (!offset) 219 return; 220 221 idx = position & ((1 << v->hash_per_block_bits) - 1); 222 if (!v->version) 223 *offset = idx * v->digest_size; 224 else 225 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 226 } 227 228 /* 229 * Handle verification errors. 230 */ 231 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 232 unsigned long long block) 233 { 234 char verity_env[DM_VERITY_ENV_LENGTH]; 235 char *envp[] = { verity_env, NULL }; 236 const char *type_str = ""; 237 struct mapped_device *md = dm_table_get_md(v->ti->table); 238 239 /* Corruption should be visible in device status in all modes */ 240 v->hash_failed = true; 241 242 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 243 goto out; 244 245 v->corrupted_errs++; 246 247 switch (type) { 248 case DM_VERITY_BLOCK_TYPE_DATA: 249 type_str = "data"; 250 break; 251 case DM_VERITY_BLOCK_TYPE_METADATA: 252 type_str = "metadata"; 253 break; 254 default: 255 BUG(); 256 } 257 258 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 259 type_str, block); 260 261 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { 262 DMERR("%s: reached maximum errors", v->data_dev->name); 263 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); 264 } 265 266 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 267 DM_VERITY_ENV_VAR_NAME, type, block); 268 269 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 270 271 out: 272 if (v->mode == DM_VERITY_MODE_LOGGING) 273 return 0; 274 275 if (v->mode == DM_VERITY_MODE_RESTART) 276 kernel_restart("dm-verity device corrupted"); 277 278 if (v->mode == DM_VERITY_MODE_PANIC) 279 panic("dm-verity device corrupted"); 280 281 return 1; 282 } 283 284 /* 285 * Verify hash of a metadata block pertaining to the specified data block 286 * ("block" argument) at a specified level ("level" argument). 287 * 288 * On successful return, verity_io_want_digest(v, io) contains the hash value 289 * for a lower tree level or for the data block (if we're at the lowest level). 290 * 291 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 292 * If "skip_unverified" is false, unverified buffer is hashed and verified 293 * against current value of verity_io_want_digest(v, io). 294 */ 295 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 296 sector_t block, int level, bool skip_unverified, 297 u8 *want_digest) 298 { 299 struct dm_buffer *buf; 300 struct buffer_aux *aux; 301 u8 *data; 302 int r; 303 sector_t hash_block; 304 unsigned int offset; 305 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 306 307 verity_hash_at_level(v, block, level, &hash_block, &offset); 308 309 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 310 data = dm_bufio_get(v->bufio, hash_block, &buf); 311 if (data == NULL) { 312 /* 313 * In tasklet and the hash was not in the bufio cache. 314 * Return early and resume execution from a work-queue 315 * to read the hash from disk. 316 */ 317 return -EAGAIN; 318 } 319 } else { 320 data = dm_bufio_read_with_ioprio(v->bufio, hash_block, 321 &buf, bio_prio(bio)); 322 } 323 324 if (IS_ERR(data)) 325 return PTR_ERR(data); 326 327 aux = dm_bufio_get_aux_data(buf); 328 329 if (!aux->hash_verified) { 330 if (skip_unverified) { 331 r = 1; 332 goto release_ret_r; 333 } 334 335 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits, 336 verity_io_real_digest(v, io), !io->in_bh); 337 if (unlikely(r < 0)) 338 goto release_ret_r; 339 340 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 341 v->digest_size) == 0)) 342 aux->hash_verified = 1; 343 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 344 /* 345 * Error handling code (FEC included) cannot be run in a 346 * tasklet since it may sleep, so fallback to work-queue. 347 */ 348 r = -EAGAIN; 349 goto release_ret_r; 350 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 351 hash_block, data) == 0) 352 aux->hash_verified = 1; 353 else if (verity_handle_err(v, 354 DM_VERITY_BLOCK_TYPE_METADATA, 355 hash_block)) { 356 struct bio *bio = 357 dm_bio_from_per_bio_data(io, 358 v->ti->per_io_data_size); 359 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, 360 block, 0); 361 r = -EIO; 362 goto release_ret_r; 363 } 364 } 365 366 data += offset; 367 memcpy(want_digest, data, v->digest_size); 368 r = 0; 369 370 release_ret_r: 371 dm_bufio_release(buf); 372 return r; 373 } 374 375 /* 376 * Find a hash for a given block, write it to digest and verify the integrity 377 * of the hash tree if necessary. 378 */ 379 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 380 sector_t block, u8 *digest, bool *is_zero) 381 { 382 int r = 0, i; 383 384 if (likely(v->levels)) { 385 /* 386 * First, we try to get the requested hash for 387 * the current block. If the hash block itself is 388 * verified, zero is returned. If it isn't, this 389 * function returns 1 and we fall back to whole 390 * chain verification. 391 */ 392 r = verity_verify_level(v, io, block, 0, true, digest); 393 if (likely(r <= 0)) 394 goto out; 395 } 396 397 memcpy(digest, v->root_digest, v->digest_size); 398 399 for (i = v->levels - 1; i >= 0; i--) { 400 r = verity_verify_level(v, io, block, i, false, digest); 401 if (unlikely(r)) 402 goto out; 403 } 404 out: 405 if (!r && v->zero_digest) 406 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 407 else 408 *is_zero = false; 409 410 return r; 411 } 412 413 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io, 414 sector_t cur_block, u8 *dest) 415 { 416 struct page *page; 417 void *buffer; 418 int r; 419 struct dm_io_request io_req; 420 struct dm_io_region io_loc; 421 422 page = mempool_alloc(&v->recheck_pool, GFP_NOIO); 423 buffer = page_to_virt(page); 424 425 io_req.bi_opf = REQ_OP_READ; 426 io_req.mem.type = DM_IO_KMEM; 427 io_req.mem.ptr.addr = buffer; 428 io_req.notify.fn = NULL; 429 io_req.client = v->io; 430 io_loc.bdev = v->data_dev->bdev; 431 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT); 432 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT); 433 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT); 434 if (unlikely(r)) 435 goto free_ret; 436 437 r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits, 438 verity_io_real_digest(v, io), true); 439 if (unlikely(r)) 440 goto free_ret; 441 442 if (memcmp(verity_io_real_digest(v, io), 443 verity_io_want_digest(v, io), v->digest_size)) { 444 r = -EIO; 445 goto free_ret; 446 } 447 448 memcpy(dest, buffer, 1 << v->data_dev_block_bits); 449 r = 0; 450 free_ret: 451 mempool_free(page, &v->recheck_pool); 452 453 return r; 454 } 455 456 static int verity_handle_data_hash_mismatch(struct dm_verity *v, 457 struct dm_verity_io *io, 458 struct bio *bio, sector_t blkno, 459 u8 *data) 460 { 461 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 462 /* 463 * Error handling code (FEC included) cannot be run in the 464 * BH workqueue, so fallback to a standard workqueue. 465 */ 466 return -EAGAIN; 467 } 468 if (verity_recheck(v, io, blkno, data) == 0) { 469 if (v->validated_blocks) 470 set_bit(blkno, v->validated_blocks); 471 return 0; 472 } 473 #if defined(CONFIG_DM_VERITY_FEC) 474 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno, 475 data) == 0) 476 return 0; 477 #endif 478 if (bio->bi_status) 479 return -EIO; /* Error correction failed; Just return error */ 480 481 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) { 482 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0); 483 return -EIO; 484 } 485 return 0; 486 } 487 488 /* 489 * Verify one "dm_verity_io" structure. 490 */ 491 static int verity_verify_io(struct dm_verity_io *io) 492 { 493 struct dm_verity *v = io->v; 494 const unsigned int block_size = 1 << v->data_dev_block_bits; 495 struct bvec_iter iter_copy; 496 struct bvec_iter *iter; 497 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 498 unsigned int b; 499 500 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 501 /* 502 * Copy the iterator in case we need to restart 503 * verification in a work-queue. 504 */ 505 iter_copy = io->iter; 506 iter = &iter_copy; 507 } else 508 iter = &io->iter; 509 510 for (b = 0; b < io->n_blocks; 511 b++, bio_advance_iter(bio, iter, block_size)) { 512 int r; 513 sector_t cur_block = io->block + b; 514 bool is_zero; 515 struct bio_vec bv; 516 void *data; 517 518 if (v->validated_blocks && bio->bi_status == BLK_STS_OK && 519 likely(test_bit(cur_block, v->validated_blocks))) 520 continue; 521 522 r = verity_hash_for_block(v, io, cur_block, 523 verity_io_want_digest(v, io), 524 &is_zero); 525 if (unlikely(r < 0)) 526 return r; 527 528 bv = bio_iter_iovec(bio, *iter); 529 if (unlikely(bv.bv_len < block_size)) { 530 /* 531 * Data block spans pages. This should not happen, 532 * since dm-verity sets dma_alignment to the data block 533 * size minus 1, and dm-verity also doesn't allow the 534 * data block size to be greater than PAGE_SIZE. 535 */ 536 DMERR_LIMIT("unaligned io (data block spans pages)"); 537 return -EIO; 538 } 539 540 data = bvec_kmap_local(&bv); 541 542 if (is_zero) { 543 /* 544 * If we expect a zero block, don't validate, just 545 * return zeros. 546 */ 547 memset(data, 0, block_size); 548 kunmap_local(data); 549 continue; 550 } 551 552 r = verity_hash(v, io, data, block_size, 553 verity_io_real_digest(v, io), !io->in_bh); 554 if (unlikely(r < 0)) { 555 kunmap_local(data); 556 return r; 557 } 558 559 if (likely(memcmp(verity_io_real_digest(v, io), 560 verity_io_want_digest(v, io), v->digest_size) == 0)) { 561 if (v->validated_blocks) 562 set_bit(cur_block, v->validated_blocks); 563 kunmap_local(data); 564 continue; 565 } 566 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block, 567 data); 568 kunmap_local(data); 569 if (unlikely(r)) 570 return r; 571 } 572 573 return 0; 574 } 575 576 /* 577 * Skip verity work in response to I/O error when system is shutting down. 578 */ 579 static inline bool verity_is_system_shutting_down(void) 580 { 581 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 582 || system_state == SYSTEM_RESTART; 583 } 584 585 /* 586 * End one "io" structure with a given error. 587 */ 588 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 589 { 590 struct dm_verity *v = io->v; 591 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 592 593 bio->bi_end_io = io->orig_bi_end_io; 594 bio->bi_status = status; 595 596 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh) 597 verity_fec_finish_io(io); 598 599 bio_endio(bio); 600 } 601 602 static void verity_work(struct work_struct *w) 603 { 604 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 605 606 io->in_bh = false; 607 608 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 609 } 610 611 static void verity_bh_work(struct work_struct *w) 612 { 613 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work); 614 int err; 615 616 io->in_bh = true; 617 err = verity_verify_io(io); 618 if (err == -EAGAIN || err == -ENOMEM) { 619 /* fallback to retrying with work-queue */ 620 INIT_WORK(&io->work, verity_work); 621 queue_work(io->v->verify_wq, &io->work); 622 return; 623 } 624 625 verity_finish_io(io, errno_to_blk_status(err)); 626 } 627 628 static void verity_end_io(struct bio *bio) 629 { 630 struct dm_verity_io *io = bio->bi_private; 631 632 if (bio->bi_status && 633 (!verity_fec_is_enabled(io->v) || 634 verity_is_system_shutting_down() || 635 (bio->bi_opf & REQ_RAHEAD))) { 636 verity_finish_io(io, bio->bi_status); 637 return; 638 } 639 640 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) { 641 INIT_WORK(&io->bh_work, verity_bh_work); 642 queue_work(system_bh_wq, &io->bh_work); 643 } else { 644 INIT_WORK(&io->work, verity_work); 645 queue_work(io->v->verify_wq, &io->work); 646 } 647 } 648 649 /* 650 * Prefetch buffers for the specified io. 651 * The root buffer is not prefetched, it is assumed that it will be cached 652 * all the time. 653 */ 654 static void verity_prefetch_io(struct work_struct *work) 655 { 656 struct dm_verity_prefetch_work *pw = 657 container_of(work, struct dm_verity_prefetch_work, work); 658 struct dm_verity *v = pw->v; 659 int i; 660 661 for (i = v->levels - 2; i >= 0; i--) { 662 sector_t hash_block_start; 663 sector_t hash_block_end; 664 665 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 666 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 667 668 if (!i) { 669 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 670 671 cluster >>= v->data_dev_block_bits; 672 if (unlikely(!cluster)) 673 goto no_prefetch_cluster; 674 675 if (unlikely(cluster & (cluster - 1))) 676 cluster = 1 << __fls(cluster); 677 678 hash_block_start &= ~(sector_t)(cluster - 1); 679 hash_block_end |= cluster - 1; 680 if (unlikely(hash_block_end >= v->hash_blocks)) 681 hash_block_end = v->hash_blocks - 1; 682 } 683 no_prefetch_cluster: 684 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start, 685 hash_block_end - hash_block_start + 1, 686 pw->ioprio); 687 } 688 689 kfree(pw); 690 } 691 692 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io, 693 unsigned short ioprio) 694 { 695 sector_t block = io->block; 696 unsigned int n_blocks = io->n_blocks; 697 struct dm_verity_prefetch_work *pw; 698 699 if (v->validated_blocks) { 700 while (n_blocks && test_bit(block, v->validated_blocks)) { 701 block++; 702 n_blocks--; 703 } 704 while (n_blocks && test_bit(block + n_blocks - 1, 705 v->validated_blocks)) 706 n_blocks--; 707 if (!n_blocks) 708 return; 709 } 710 711 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 712 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 713 714 if (!pw) 715 return; 716 717 INIT_WORK(&pw->work, verity_prefetch_io); 718 pw->v = v; 719 pw->block = block; 720 pw->n_blocks = n_blocks; 721 pw->ioprio = ioprio; 722 queue_work(v->verify_wq, &pw->work); 723 } 724 725 /* 726 * Bio map function. It allocates dm_verity_io structure and bio vector and 727 * fills them. Then it issues prefetches and the I/O. 728 */ 729 static int verity_map(struct dm_target *ti, struct bio *bio) 730 { 731 struct dm_verity *v = ti->private; 732 struct dm_verity_io *io; 733 734 bio_set_dev(bio, v->data_dev->bdev); 735 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 736 737 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 738 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 739 DMERR_LIMIT("unaligned io"); 740 return DM_MAPIO_KILL; 741 } 742 743 if (bio_end_sector(bio) >> 744 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 745 DMERR_LIMIT("io out of range"); 746 return DM_MAPIO_KILL; 747 } 748 749 if (bio_data_dir(bio) == WRITE) 750 return DM_MAPIO_KILL; 751 752 io = dm_per_bio_data(bio, ti->per_io_data_size); 753 io->v = v; 754 io->orig_bi_end_io = bio->bi_end_io; 755 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 756 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 757 758 bio->bi_end_io = verity_end_io; 759 bio->bi_private = io; 760 io->iter = bio->bi_iter; 761 762 verity_fec_init_io(io); 763 764 verity_submit_prefetch(v, io, bio_prio(bio)); 765 766 submit_bio_noacct(bio); 767 768 return DM_MAPIO_SUBMITTED; 769 } 770 771 /* 772 * Status: V (valid) or C (corruption found) 773 */ 774 static void verity_status(struct dm_target *ti, status_type_t type, 775 unsigned int status_flags, char *result, unsigned int maxlen) 776 { 777 struct dm_verity *v = ti->private; 778 unsigned int args = 0; 779 unsigned int sz = 0; 780 unsigned int x; 781 782 switch (type) { 783 case STATUSTYPE_INFO: 784 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 785 break; 786 case STATUSTYPE_TABLE: 787 DMEMIT("%u %s %s %u %u %llu %llu %s ", 788 v->version, 789 v->data_dev->name, 790 v->hash_dev->name, 791 1 << v->data_dev_block_bits, 792 1 << v->hash_dev_block_bits, 793 (unsigned long long)v->data_blocks, 794 (unsigned long long)v->hash_start, 795 v->alg_name 796 ); 797 for (x = 0; x < v->digest_size; x++) 798 DMEMIT("%02x", v->root_digest[x]); 799 DMEMIT(" "); 800 if (!v->salt_size) 801 DMEMIT("-"); 802 else 803 for (x = 0; x < v->salt_size; x++) 804 DMEMIT("%02x", v->salt[x]); 805 if (v->mode != DM_VERITY_MODE_EIO) 806 args++; 807 if (verity_fec_is_enabled(v)) 808 args += DM_VERITY_OPTS_FEC; 809 if (v->zero_digest) 810 args++; 811 if (v->validated_blocks) 812 args++; 813 if (v->use_bh_wq) 814 args++; 815 if (v->signature_key_desc) 816 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 817 if (!args) 818 return; 819 DMEMIT(" %u", args); 820 if (v->mode != DM_VERITY_MODE_EIO) { 821 DMEMIT(" "); 822 switch (v->mode) { 823 case DM_VERITY_MODE_LOGGING: 824 DMEMIT(DM_VERITY_OPT_LOGGING); 825 break; 826 case DM_VERITY_MODE_RESTART: 827 DMEMIT(DM_VERITY_OPT_RESTART); 828 break; 829 case DM_VERITY_MODE_PANIC: 830 DMEMIT(DM_VERITY_OPT_PANIC); 831 break; 832 default: 833 BUG(); 834 } 835 } 836 if (v->zero_digest) 837 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 838 if (v->validated_blocks) 839 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 840 if (v->use_bh_wq) 841 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 842 sz = verity_fec_status_table(v, sz, result, maxlen); 843 if (v->signature_key_desc) 844 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 845 " %s", v->signature_key_desc); 846 break; 847 848 case STATUSTYPE_IMA: 849 DMEMIT_TARGET_NAME_VERSION(ti->type); 850 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 851 DMEMIT(",verity_version=%u", v->version); 852 DMEMIT(",data_device_name=%s", v->data_dev->name); 853 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 854 DMEMIT(",verity_algorithm=%s", v->alg_name); 855 856 DMEMIT(",root_digest="); 857 for (x = 0; x < v->digest_size; x++) 858 DMEMIT("%02x", v->root_digest[x]); 859 860 DMEMIT(",salt="); 861 if (!v->salt_size) 862 DMEMIT("-"); 863 else 864 for (x = 0; x < v->salt_size; x++) 865 DMEMIT("%02x", v->salt[x]); 866 867 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 868 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 869 if (v->signature_key_desc) 870 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 871 872 if (v->mode != DM_VERITY_MODE_EIO) { 873 DMEMIT(",verity_mode="); 874 switch (v->mode) { 875 case DM_VERITY_MODE_LOGGING: 876 DMEMIT(DM_VERITY_OPT_LOGGING); 877 break; 878 case DM_VERITY_MODE_RESTART: 879 DMEMIT(DM_VERITY_OPT_RESTART); 880 break; 881 case DM_VERITY_MODE_PANIC: 882 DMEMIT(DM_VERITY_OPT_PANIC); 883 break; 884 default: 885 DMEMIT("invalid"); 886 } 887 } 888 DMEMIT(";"); 889 break; 890 } 891 } 892 893 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 894 { 895 struct dm_verity *v = ti->private; 896 897 *bdev = v->data_dev->bdev; 898 899 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 900 return 1; 901 return 0; 902 } 903 904 static int verity_iterate_devices(struct dm_target *ti, 905 iterate_devices_callout_fn fn, void *data) 906 { 907 struct dm_verity *v = ti->private; 908 909 return fn(ti, v->data_dev, v->data_start, ti->len, data); 910 } 911 912 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 913 { 914 struct dm_verity *v = ti->private; 915 916 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 917 limits->logical_block_size = 1 << v->data_dev_block_bits; 918 919 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 920 limits->physical_block_size = 1 << v->data_dev_block_bits; 921 922 limits->io_min = limits->logical_block_size; 923 924 /* 925 * Similar to what dm-crypt does, opt dm-verity out of support for 926 * direct I/O that is aligned to less than the traditional direct I/O 927 * alignment requirement of logical_block_size. This prevents dm-verity 928 * data blocks from crossing pages, eliminating various edge cases. 929 */ 930 limits->dma_alignment = limits->logical_block_size - 1; 931 } 932 933 static void verity_dtr(struct dm_target *ti) 934 { 935 struct dm_verity *v = ti->private; 936 937 if (v->verify_wq) 938 destroy_workqueue(v->verify_wq); 939 940 mempool_exit(&v->recheck_pool); 941 if (v->io) 942 dm_io_client_destroy(v->io); 943 944 if (v->bufio) 945 dm_bufio_client_destroy(v->bufio); 946 947 kvfree(v->validated_blocks); 948 kfree(v->salt); 949 kfree(v->initial_hashstate); 950 kfree(v->root_digest); 951 kfree(v->zero_digest); 952 953 if (v->ahash_tfm) { 954 static_branch_dec(&ahash_enabled); 955 crypto_free_ahash(v->ahash_tfm); 956 } else { 957 crypto_free_shash(v->shash_tfm); 958 } 959 960 kfree(v->alg_name); 961 962 if (v->hash_dev) 963 dm_put_device(ti, v->hash_dev); 964 965 if (v->data_dev) 966 dm_put_device(ti, v->data_dev); 967 968 verity_fec_dtr(v); 969 970 kfree(v->signature_key_desc); 971 972 if (v->use_bh_wq) 973 static_branch_dec(&use_bh_wq_enabled); 974 975 kfree(v); 976 977 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 978 } 979 980 static int verity_alloc_most_once(struct dm_verity *v) 981 { 982 struct dm_target *ti = v->ti; 983 984 /* the bitset can only handle INT_MAX blocks */ 985 if (v->data_blocks > INT_MAX) { 986 ti->error = "device too large to use check_at_most_once"; 987 return -E2BIG; 988 } 989 990 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 991 sizeof(unsigned long), 992 GFP_KERNEL); 993 if (!v->validated_blocks) { 994 ti->error = "failed to allocate bitset for check_at_most_once"; 995 return -ENOMEM; 996 } 997 998 return 0; 999 } 1000 1001 static int verity_alloc_zero_digest(struct dm_verity *v) 1002 { 1003 int r = -ENOMEM; 1004 struct dm_verity_io *io; 1005 u8 *zero_data; 1006 1007 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1008 1009 if (!v->zero_digest) 1010 return r; 1011 1012 io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL); 1013 1014 if (!io) 1015 return r; /* verity_dtr will free zero_digest */ 1016 1017 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1018 1019 if (!zero_data) 1020 goto out; 1021 1022 r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits, 1023 v->zero_digest, true); 1024 1025 out: 1026 kfree(io); 1027 kfree(zero_data); 1028 1029 return r; 1030 } 1031 1032 static inline bool verity_is_verity_mode(const char *arg_name) 1033 { 1034 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1035 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1036 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1037 } 1038 1039 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1040 { 1041 if (v->mode) 1042 return -EINVAL; 1043 1044 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1045 v->mode = DM_VERITY_MODE_LOGGING; 1046 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1047 v->mode = DM_VERITY_MODE_RESTART; 1048 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1049 v->mode = DM_VERITY_MODE_PANIC; 1050 1051 return 0; 1052 } 1053 1054 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1055 struct dm_verity_sig_opts *verify_args, 1056 bool only_modifier_opts) 1057 { 1058 int r = 0; 1059 unsigned int argc; 1060 struct dm_target *ti = v->ti; 1061 const char *arg_name; 1062 1063 static const struct dm_arg _args[] = { 1064 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1065 }; 1066 1067 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1068 if (r) 1069 return -EINVAL; 1070 1071 if (!argc) 1072 return 0; 1073 1074 do { 1075 arg_name = dm_shift_arg(as); 1076 argc--; 1077 1078 if (verity_is_verity_mode(arg_name)) { 1079 if (only_modifier_opts) 1080 continue; 1081 r = verity_parse_verity_mode(v, arg_name); 1082 if (r) { 1083 ti->error = "Conflicting error handling parameters"; 1084 return r; 1085 } 1086 continue; 1087 1088 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1089 if (only_modifier_opts) 1090 continue; 1091 r = verity_alloc_zero_digest(v); 1092 if (r) { 1093 ti->error = "Cannot allocate zero digest"; 1094 return r; 1095 } 1096 continue; 1097 1098 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1099 if (only_modifier_opts) 1100 continue; 1101 r = verity_alloc_most_once(v); 1102 if (r) 1103 return r; 1104 continue; 1105 1106 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1107 v->use_bh_wq = true; 1108 static_branch_inc(&use_bh_wq_enabled); 1109 continue; 1110 1111 } else if (verity_is_fec_opt_arg(arg_name)) { 1112 if (only_modifier_opts) 1113 continue; 1114 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1115 if (r) 1116 return r; 1117 continue; 1118 1119 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1120 if (only_modifier_opts) 1121 continue; 1122 r = verity_verify_sig_parse_opt_args(as, v, 1123 verify_args, 1124 &argc, arg_name); 1125 if (r) 1126 return r; 1127 continue; 1128 1129 } else if (only_modifier_opts) { 1130 /* 1131 * Ignore unrecognized opt, could easily be an extra 1132 * argument to an option whose parsing was skipped. 1133 * Normal parsing (@only_modifier_opts=false) will 1134 * properly parse all options (and their extra args). 1135 */ 1136 continue; 1137 } 1138 1139 DMERR("Unrecognized verity feature request: %s", arg_name); 1140 ti->error = "Unrecognized verity feature request"; 1141 return -EINVAL; 1142 } while (argc && !r); 1143 1144 return r; 1145 } 1146 1147 static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name) 1148 { 1149 struct dm_target *ti = v->ti; 1150 struct crypto_ahash *ahash; 1151 struct crypto_shash *shash = NULL; 1152 const char *driver_name; 1153 1154 v->alg_name = kstrdup(alg_name, GFP_KERNEL); 1155 if (!v->alg_name) { 1156 ti->error = "Cannot allocate algorithm name"; 1157 return -ENOMEM; 1158 } 1159 1160 /* 1161 * Allocate the hash transformation object that this dm-verity instance 1162 * will use. The vast majority of dm-verity users use CPU-based 1163 * hashing, so when possible use the shash API to minimize the crypto 1164 * API overhead. If the ahash API resolves to a different driver 1165 * (likely an off-CPU hardware offload), use ahash instead. Also use 1166 * ahash if the obsolete dm-verity format with the appended salt is 1167 * being used, so that quirk only needs to be handled in one place. 1168 */ 1169 ahash = crypto_alloc_ahash(alg_name, 0, 1170 v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0); 1171 if (IS_ERR(ahash)) { 1172 ti->error = "Cannot initialize hash function"; 1173 return PTR_ERR(ahash); 1174 } 1175 driver_name = crypto_ahash_driver_name(ahash); 1176 if (v->version >= 1 /* salt prepended, not appended? */) { 1177 shash = crypto_alloc_shash(alg_name, 0, 0); 1178 if (!IS_ERR(shash) && 1179 strcmp(crypto_shash_driver_name(shash), driver_name) != 0) { 1180 /* 1181 * ahash gave a different driver than shash, so probably 1182 * this is a case of real hardware offload. Use ahash. 1183 */ 1184 crypto_free_shash(shash); 1185 shash = NULL; 1186 } 1187 } 1188 if (!IS_ERR_OR_NULL(shash)) { 1189 crypto_free_ahash(ahash); 1190 ahash = NULL; 1191 v->shash_tfm = shash; 1192 v->digest_size = crypto_shash_digestsize(shash); 1193 v->hash_reqsize = sizeof(struct shash_desc) + 1194 crypto_shash_descsize(shash); 1195 DMINFO("%s using shash \"%s\"", alg_name, driver_name); 1196 } else { 1197 v->ahash_tfm = ahash; 1198 static_branch_inc(&ahash_enabled); 1199 v->digest_size = crypto_ahash_digestsize(ahash); 1200 v->hash_reqsize = sizeof(struct ahash_request) + 1201 crypto_ahash_reqsize(ahash); 1202 DMINFO("%s using ahash \"%s\"", alg_name, driver_name); 1203 } 1204 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1205 ti->error = "Digest size too big"; 1206 return -EINVAL; 1207 } 1208 return 0; 1209 } 1210 1211 static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg) 1212 { 1213 struct dm_target *ti = v->ti; 1214 1215 if (strcmp(arg, "-") != 0) { 1216 v->salt_size = strlen(arg) / 2; 1217 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1218 if (!v->salt) { 1219 ti->error = "Cannot allocate salt"; 1220 return -ENOMEM; 1221 } 1222 if (strlen(arg) != v->salt_size * 2 || 1223 hex2bin(v->salt, arg, v->salt_size)) { 1224 ti->error = "Invalid salt"; 1225 return -EINVAL; 1226 } 1227 } 1228 if (v->shash_tfm) { 1229 SHASH_DESC_ON_STACK(desc, v->shash_tfm); 1230 int r; 1231 1232 /* 1233 * Compute the pre-salted hash state that can be passed to 1234 * crypto_shash_import() for each block later. 1235 */ 1236 v->initial_hashstate = kmalloc( 1237 crypto_shash_statesize(v->shash_tfm), GFP_KERNEL); 1238 if (!v->initial_hashstate) { 1239 ti->error = "Cannot allocate initial hash state"; 1240 return -ENOMEM; 1241 } 1242 desc->tfm = v->shash_tfm; 1243 r = crypto_shash_init(desc) ?: 1244 crypto_shash_update(desc, v->salt, v->salt_size) ?: 1245 crypto_shash_export(desc, v->initial_hashstate); 1246 if (r) { 1247 ti->error = "Cannot set up initial hash state"; 1248 return r; 1249 } 1250 } 1251 return 0; 1252 } 1253 1254 /* 1255 * Target parameters: 1256 * <version> The current format is version 1. 1257 * Vsn 0 is compatible with original Chromium OS releases. 1258 * <data device> 1259 * <hash device> 1260 * <data block size> 1261 * <hash block size> 1262 * <the number of data blocks> 1263 * <hash start block> 1264 * <algorithm> 1265 * <digest> 1266 * <salt> Hex string or "-" if no salt. 1267 */ 1268 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1269 { 1270 struct dm_verity *v; 1271 struct dm_verity_sig_opts verify_args = {0}; 1272 struct dm_arg_set as; 1273 unsigned int num; 1274 unsigned long long num_ll; 1275 int r; 1276 int i; 1277 sector_t hash_position; 1278 char dummy; 1279 char *root_hash_digest_to_validate; 1280 1281 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1282 if (!v) { 1283 ti->error = "Cannot allocate verity structure"; 1284 return -ENOMEM; 1285 } 1286 ti->private = v; 1287 v->ti = ti; 1288 1289 r = verity_fec_ctr_alloc(v); 1290 if (r) 1291 goto bad; 1292 1293 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1294 ti->error = "Device must be readonly"; 1295 r = -EINVAL; 1296 goto bad; 1297 } 1298 1299 if (argc < 10) { 1300 ti->error = "Not enough arguments"; 1301 r = -EINVAL; 1302 goto bad; 1303 } 1304 1305 /* Parse optional parameters that modify primary args */ 1306 if (argc > 10) { 1307 as.argc = argc - 10; 1308 as.argv = argv + 10; 1309 r = verity_parse_opt_args(&as, v, &verify_args, true); 1310 if (r < 0) 1311 goto bad; 1312 } 1313 1314 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1315 num > 1) { 1316 ti->error = "Invalid version"; 1317 r = -EINVAL; 1318 goto bad; 1319 } 1320 v->version = num; 1321 1322 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1323 if (r) { 1324 ti->error = "Data device lookup failed"; 1325 goto bad; 1326 } 1327 1328 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1329 if (r) { 1330 ti->error = "Hash device lookup failed"; 1331 goto bad; 1332 } 1333 1334 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1335 !num || (num & (num - 1)) || 1336 num < bdev_logical_block_size(v->data_dev->bdev) || 1337 num > PAGE_SIZE) { 1338 ti->error = "Invalid data device block size"; 1339 r = -EINVAL; 1340 goto bad; 1341 } 1342 v->data_dev_block_bits = __ffs(num); 1343 1344 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1345 !num || (num & (num - 1)) || 1346 num < bdev_logical_block_size(v->hash_dev->bdev) || 1347 num > INT_MAX) { 1348 ti->error = "Invalid hash device block size"; 1349 r = -EINVAL; 1350 goto bad; 1351 } 1352 v->hash_dev_block_bits = __ffs(num); 1353 1354 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1355 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1356 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1357 ti->error = "Invalid data blocks"; 1358 r = -EINVAL; 1359 goto bad; 1360 } 1361 v->data_blocks = num_ll; 1362 1363 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1364 ti->error = "Data device is too small"; 1365 r = -EINVAL; 1366 goto bad; 1367 } 1368 1369 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1370 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1371 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1372 ti->error = "Invalid hash start"; 1373 r = -EINVAL; 1374 goto bad; 1375 } 1376 v->hash_start = num_ll; 1377 1378 r = verity_setup_hash_alg(v, argv[7]); 1379 if (r) 1380 goto bad; 1381 1382 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1383 if (!v->root_digest) { 1384 ti->error = "Cannot allocate root digest"; 1385 r = -ENOMEM; 1386 goto bad; 1387 } 1388 if (strlen(argv[8]) != v->digest_size * 2 || 1389 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1390 ti->error = "Invalid root digest"; 1391 r = -EINVAL; 1392 goto bad; 1393 } 1394 root_hash_digest_to_validate = argv[8]; 1395 1396 r = verity_setup_salt_and_hashstate(v, argv[9]); 1397 if (r) 1398 goto bad; 1399 1400 argv += 10; 1401 argc -= 10; 1402 1403 /* Optional parameters */ 1404 if (argc) { 1405 as.argc = argc; 1406 as.argv = argv; 1407 r = verity_parse_opt_args(&as, v, &verify_args, false); 1408 if (r < 0) 1409 goto bad; 1410 } 1411 1412 /* Root hash signature is a optional parameter*/ 1413 r = verity_verify_root_hash(root_hash_digest_to_validate, 1414 strlen(root_hash_digest_to_validate), 1415 verify_args.sig, 1416 verify_args.sig_size); 1417 if (r < 0) { 1418 ti->error = "Root hash verification failed"; 1419 goto bad; 1420 } 1421 v->hash_per_block_bits = 1422 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1423 1424 v->levels = 0; 1425 if (v->data_blocks) 1426 while (v->hash_per_block_bits * v->levels < 64 && 1427 (unsigned long long)(v->data_blocks - 1) >> 1428 (v->hash_per_block_bits * v->levels)) 1429 v->levels++; 1430 1431 if (v->levels > DM_VERITY_MAX_LEVELS) { 1432 ti->error = "Too many tree levels"; 1433 r = -E2BIG; 1434 goto bad; 1435 } 1436 1437 hash_position = v->hash_start; 1438 for (i = v->levels - 1; i >= 0; i--) { 1439 sector_t s; 1440 1441 v->hash_level_block[i] = hash_position; 1442 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1443 >> ((i + 1) * v->hash_per_block_bits); 1444 if (hash_position + s < hash_position) { 1445 ti->error = "Hash device offset overflow"; 1446 r = -E2BIG; 1447 goto bad; 1448 } 1449 hash_position += s; 1450 } 1451 v->hash_blocks = hash_position; 1452 1453 r = mempool_init_page_pool(&v->recheck_pool, 1, 0); 1454 if (unlikely(r)) { 1455 ti->error = "Cannot allocate mempool"; 1456 goto bad; 1457 } 1458 1459 v->io = dm_io_client_create(); 1460 if (IS_ERR(v->io)) { 1461 r = PTR_ERR(v->io); 1462 v->io = NULL; 1463 ti->error = "Cannot allocate dm io"; 1464 goto bad; 1465 } 1466 1467 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1468 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1469 dm_bufio_alloc_callback, NULL, 1470 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1471 if (IS_ERR(v->bufio)) { 1472 ti->error = "Cannot initialize dm-bufio"; 1473 r = PTR_ERR(v->bufio); 1474 v->bufio = NULL; 1475 goto bad; 1476 } 1477 1478 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1479 ti->error = "Hash device is too small"; 1480 r = -E2BIG; 1481 goto bad; 1482 } 1483 1484 /* 1485 * Using WQ_HIGHPRI improves throughput and completion latency by 1486 * reducing wait times when reading from a dm-verity device. 1487 * 1488 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1489 * allows verify_wq to preempt softirq since verification in BH workqueue 1490 * will fall-back to using it for error handling (or if the bufio cache 1491 * doesn't have required hashes). 1492 */ 1493 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1494 if (!v->verify_wq) { 1495 ti->error = "Cannot allocate workqueue"; 1496 r = -ENOMEM; 1497 goto bad; 1498 } 1499 1500 ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize; 1501 1502 r = verity_fec_ctr(v); 1503 if (r) 1504 goto bad; 1505 1506 ti->per_io_data_size = roundup(ti->per_io_data_size, 1507 __alignof__(struct dm_verity_io)); 1508 1509 verity_verify_sig_opts_cleanup(&verify_args); 1510 1511 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1512 1513 return 0; 1514 1515 bad: 1516 1517 verity_verify_sig_opts_cleanup(&verify_args); 1518 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1519 verity_dtr(ti); 1520 1521 return r; 1522 } 1523 1524 /* 1525 * Get the verity mode (error behavior) of a verity target. 1526 * 1527 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1528 * target. 1529 */ 1530 int dm_verity_get_mode(struct dm_target *ti) 1531 { 1532 struct dm_verity *v = ti->private; 1533 1534 if (!dm_is_verity_target(ti)) 1535 return -EINVAL; 1536 1537 return v->mode; 1538 } 1539 1540 /* 1541 * Get the root digest of a verity target. 1542 * 1543 * Returns a copy of the root digest, the caller is responsible for 1544 * freeing the memory of the digest. 1545 */ 1546 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1547 { 1548 struct dm_verity *v = ti->private; 1549 1550 if (!dm_is_verity_target(ti)) 1551 return -EINVAL; 1552 1553 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1554 if (*root_digest == NULL) 1555 return -ENOMEM; 1556 1557 *digest_size = v->digest_size; 1558 1559 return 0; 1560 } 1561 1562 static struct target_type verity_target = { 1563 .name = "verity", 1564 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, 1565 .version = {1, 10, 0}, 1566 .module = THIS_MODULE, 1567 .ctr = verity_ctr, 1568 .dtr = verity_dtr, 1569 .map = verity_map, 1570 .status = verity_status, 1571 .prepare_ioctl = verity_prepare_ioctl, 1572 .iterate_devices = verity_iterate_devices, 1573 .io_hints = verity_io_hints, 1574 }; 1575 module_dm(verity); 1576 1577 /* 1578 * Check whether a DM target is a verity target. 1579 */ 1580 bool dm_is_verity_target(struct dm_target *ti) 1581 { 1582 return ti->type == &verity_target; 1583 } 1584 1585 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1586 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1587 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1588 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1589 MODULE_LICENSE("GPL"); 1590