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 #include <linux/security.h> 26 27 #define DM_MSG_PREFIX "verity" 28 29 #define DM_VERITY_ENV_LENGTH 42 30 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 31 32 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 33 34 #define DM_VERITY_MAX_CORRUPTED_ERRS 100 35 36 #define DM_VERITY_OPT_LOGGING "ignore_corruption" 37 #define DM_VERITY_OPT_RESTART "restart_on_corruption" 38 #define DM_VERITY_OPT_PANIC "panic_on_corruption" 39 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 40 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 41 #define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet" 42 43 #define DM_VERITY_OPTS_MAX (4 + DM_VERITY_OPTS_FEC + \ 44 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 45 46 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 47 48 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644); 49 50 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled); 51 52 /* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */ 53 static DEFINE_STATIC_KEY_FALSE(ahash_enabled); 54 55 struct dm_verity_prefetch_work { 56 struct work_struct work; 57 struct dm_verity *v; 58 unsigned short ioprio; 59 sector_t block; 60 unsigned int n_blocks; 61 }; 62 63 /* 64 * Auxiliary structure appended to each dm-bufio buffer. If the value 65 * hash_verified is nonzero, hash of the block has been verified. 66 * 67 * The variable hash_verified is set to 0 when allocating the buffer, then 68 * it can be changed to 1 and it is never reset to 0 again. 69 * 70 * There is no lock around this value, a race condition can at worst cause 71 * that multiple processes verify the hash of the same buffer simultaneously 72 * and write 1 to hash_verified simultaneously. 73 * This condition is harmless, so we don't need locking. 74 */ 75 struct buffer_aux { 76 int hash_verified; 77 }; 78 79 /* 80 * Initialize struct buffer_aux for a freshly created buffer. 81 */ 82 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 83 { 84 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 85 86 aux->hash_verified = 0; 87 } 88 89 /* 90 * Translate input sector number to the sector number on the target device. 91 */ 92 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 93 { 94 return v->data_start + dm_target_offset(v->ti, bi_sector); 95 } 96 97 /* 98 * Return hash position of a specified block at a specified tree level 99 * (0 is the lowest level). 100 * The lowest "hash_per_block_bits"-bits of the result denote hash position 101 * inside a hash block. The remaining bits denote location of the hash block. 102 */ 103 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 104 int level) 105 { 106 return block >> (level * v->hash_per_block_bits); 107 } 108 109 static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req, 110 const u8 *data, size_t len, 111 struct crypto_wait *wait) 112 { 113 struct scatterlist sg; 114 115 if (likely(!is_vmalloc_addr(data))) { 116 sg_init_one(&sg, data, len); 117 ahash_request_set_crypt(req, &sg, NULL, len); 118 return crypto_wait_req(crypto_ahash_update(req), wait); 119 } 120 121 do { 122 int r; 123 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 124 125 flush_kernel_vmap_range((void *)data, this_step); 126 sg_init_table(&sg, 1); 127 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 128 ahash_request_set_crypt(req, &sg, NULL, this_step); 129 r = crypto_wait_req(crypto_ahash_update(req), wait); 130 if (unlikely(r)) 131 return r; 132 data += this_step; 133 len -= this_step; 134 } while (len); 135 136 return 0; 137 } 138 139 /* 140 * Wrapper for crypto_ahash_init, which handles verity salting. 141 */ 142 static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req, 143 struct crypto_wait *wait, bool may_sleep) 144 { 145 int r; 146 147 ahash_request_set_tfm(req, v->ahash_tfm); 148 ahash_request_set_callback(req, 149 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0, 150 crypto_req_done, (void *)wait); 151 crypto_init_wait(wait); 152 153 r = crypto_wait_req(crypto_ahash_init(req), wait); 154 155 if (unlikely(r < 0)) { 156 if (r != -ENOMEM) 157 DMERR("crypto_ahash_init failed: %d", r); 158 return r; 159 } 160 161 if (likely(v->salt_size && (v->version >= 1))) 162 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait); 163 164 return r; 165 } 166 167 static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req, 168 u8 *digest, struct crypto_wait *wait) 169 { 170 int r; 171 172 if (unlikely(v->salt_size && (!v->version))) { 173 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait); 174 175 if (r < 0) { 176 DMERR("%s failed updating salt: %d", __func__, r); 177 goto out; 178 } 179 } 180 181 ahash_request_set_crypt(req, NULL, digest, 0); 182 r = crypto_wait_req(crypto_ahash_final(req), wait); 183 out: 184 return r; 185 } 186 187 int verity_hash(struct dm_verity *v, struct dm_verity_io *io, 188 const u8 *data, size_t len, u8 *digest, bool may_sleep) 189 { 190 int r; 191 192 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) { 193 struct ahash_request *req = verity_io_hash_req(v, io); 194 struct crypto_wait wait; 195 196 r = verity_ahash_init(v, req, &wait, may_sleep) ?: 197 verity_ahash_update(v, req, data, len, &wait) ?: 198 verity_ahash_final(v, req, digest, &wait); 199 } else { 200 struct shash_desc *desc = verity_io_hash_req(v, io); 201 202 desc->tfm = v->shash_tfm; 203 r = crypto_shash_import(desc, v->initial_hashstate) ?: 204 crypto_shash_finup(desc, data, len, digest); 205 } 206 if (unlikely(r)) 207 DMERR("Error hashing block: %d", r); 208 return r; 209 } 210 211 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 212 sector_t *hash_block, unsigned int *offset) 213 { 214 sector_t position = verity_position_at_level(v, block, level); 215 unsigned int idx; 216 217 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 218 219 if (!offset) 220 return; 221 222 idx = position & ((1 << v->hash_per_block_bits) - 1); 223 if (!v->version) 224 *offset = idx * v->digest_size; 225 else 226 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 227 } 228 229 /* 230 * Handle verification errors. 231 */ 232 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 233 unsigned long long block) 234 { 235 char verity_env[DM_VERITY_ENV_LENGTH]; 236 char *envp[] = { verity_env, NULL }; 237 const char *type_str = ""; 238 struct mapped_device *md = dm_table_get_md(v->ti->table); 239 240 /* Corruption should be visible in device status in all modes */ 241 v->hash_failed = true; 242 243 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 244 goto out; 245 246 v->corrupted_errs++; 247 248 switch (type) { 249 case DM_VERITY_BLOCK_TYPE_DATA: 250 type_str = "data"; 251 break; 252 case DM_VERITY_BLOCK_TYPE_METADATA: 253 type_str = "metadata"; 254 break; 255 default: 256 BUG(); 257 } 258 259 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 260 type_str, block); 261 262 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { 263 DMERR("%s: reached maximum errors", v->data_dev->name); 264 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); 265 } 266 267 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 268 DM_VERITY_ENV_VAR_NAME, type, block); 269 270 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 271 272 out: 273 if (v->mode == DM_VERITY_MODE_LOGGING) 274 return 0; 275 276 if (v->mode == DM_VERITY_MODE_RESTART) 277 kernel_restart("dm-verity device corrupted"); 278 279 if (v->mode == DM_VERITY_MODE_PANIC) 280 panic("dm-verity device corrupted"); 281 282 return 1; 283 } 284 285 /* 286 * Verify hash of a metadata block pertaining to the specified data block 287 * ("block" argument) at a specified level ("level" argument). 288 * 289 * On successful return, verity_io_want_digest(v, io) contains the hash value 290 * for a lower tree level or for the data block (if we're at the lowest level). 291 * 292 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 293 * If "skip_unverified" is false, unverified buffer is hashed and verified 294 * against current value of verity_io_want_digest(v, io). 295 */ 296 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 297 sector_t block, int level, bool skip_unverified, 298 u8 *want_digest) 299 { 300 struct dm_buffer *buf; 301 struct buffer_aux *aux; 302 u8 *data; 303 int r; 304 sector_t hash_block; 305 unsigned int offset; 306 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 307 308 verity_hash_at_level(v, block, level, &hash_block, &offset); 309 310 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 311 data = dm_bufio_get(v->bufio, hash_block, &buf); 312 if (data == NULL) { 313 /* 314 * In tasklet and the hash was not in the bufio cache. 315 * Return early and resume execution from a work-queue 316 * to read the hash from disk. 317 */ 318 return -EAGAIN; 319 } 320 } else { 321 data = dm_bufio_read_with_ioprio(v->bufio, hash_block, 322 &buf, bio_prio(bio)); 323 } 324 325 if (IS_ERR(data)) 326 return PTR_ERR(data); 327 328 aux = dm_bufio_get_aux_data(buf); 329 330 if (!aux->hash_verified) { 331 if (skip_unverified) { 332 r = 1; 333 goto release_ret_r; 334 } 335 336 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits, 337 verity_io_real_digest(v, io), !io->in_bh); 338 if (unlikely(r < 0)) 339 goto release_ret_r; 340 341 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 342 v->digest_size) == 0)) 343 aux->hash_verified = 1; 344 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 345 /* 346 * Error handling code (FEC included) cannot be run in a 347 * tasklet since it may sleep, so fallback to work-queue. 348 */ 349 r = -EAGAIN; 350 goto release_ret_r; 351 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 352 hash_block, data) == 0) 353 aux->hash_verified = 1; 354 else if (verity_handle_err(v, 355 DM_VERITY_BLOCK_TYPE_METADATA, 356 hash_block)) { 357 struct bio *bio = 358 dm_bio_from_per_bio_data(io, 359 v->ti->per_io_data_size); 360 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, 361 block, 0); 362 r = -EIO; 363 goto release_ret_r; 364 } 365 } 366 367 data += offset; 368 memcpy(want_digest, data, v->digest_size); 369 r = 0; 370 371 release_ret_r: 372 dm_bufio_release(buf); 373 return r; 374 } 375 376 /* 377 * Find a hash for a given block, write it to digest and verify the integrity 378 * of the hash tree if necessary. 379 */ 380 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 381 sector_t block, u8 *digest, bool *is_zero) 382 { 383 int r = 0, i; 384 385 if (likely(v->levels)) { 386 /* 387 * First, we try to get the requested hash for 388 * the current block. If the hash block itself is 389 * verified, zero is returned. If it isn't, this 390 * function returns 1 and we fall back to whole 391 * chain verification. 392 */ 393 r = verity_verify_level(v, io, block, 0, true, digest); 394 if (likely(r <= 0)) 395 goto out; 396 } 397 398 memcpy(digest, v->root_digest, v->digest_size); 399 400 for (i = v->levels - 1; i >= 0; i--) { 401 r = verity_verify_level(v, io, block, i, false, digest); 402 if (unlikely(r)) 403 goto out; 404 } 405 out: 406 if (!r && v->zero_digest) 407 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 408 else 409 *is_zero = false; 410 411 return r; 412 } 413 414 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io, 415 sector_t cur_block, u8 *dest) 416 { 417 struct page *page; 418 void *buffer; 419 int r; 420 struct dm_io_request io_req; 421 struct dm_io_region io_loc; 422 423 page = mempool_alloc(&v->recheck_pool, GFP_NOIO); 424 buffer = page_to_virt(page); 425 426 io_req.bi_opf = REQ_OP_READ; 427 io_req.mem.type = DM_IO_KMEM; 428 io_req.mem.ptr.addr = buffer; 429 io_req.notify.fn = NULL; 430 io_req.client = v->io; 431 io_loc.bdev = v->data_dev->bdev; 432 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT); 433 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT); 434 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT); 435 if (unlikely(r)) 436 goto free_ret; 437 438 r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits, 439 verity_io_real_digest(v, io), true); 440 if (unlikely(r)) 441 goto free_ret; 442 443 if (memcmp(verity_io_real_digest(v, io), 444 verity_io_want_digest(v, io), v->digest_size)) { 445 r = -EIO; 446 goto free_ret; 447 } 448 449 memcpy(dest, buffer, 1 << v->data_dev_block_bits); 450 r = 0; 451 free_ret: 452 mempool_free(page, &v->recheck_pool); 453 454 return r; 455 } 456 457 static int verity_handle_data_hash_mismatch(struct dm_verity *v, 458 struct dm_verity_io *io, 459 struct bio *bio, sector_t blkno, 460 u8 *data) 461 { 462 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 463 /* 464 * Error handling code (FEC included) cannot be run in the 465 * BH workqueue, so fallback to a standard workqueue. 466 */ 467 return -EAGAIN; 468 } 469 if (verity_recheck(v, io, blkno, data) == 0) { 470 if (v->validated_blocks) 471 set_bit(blkno, v->validated_blocks); 472 return 0; 473 } 474 #if defined(CONFIG_DM_VERITY_FEC) 475 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno, 476 data) == 0) 477 return 0; 478 #endif 479 if (bio->bi_status) 480 return -EIO; /* Error correction failed; Just return error */ 481 482 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) { 483 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0); 484 return -EIO; 485 } 486 return 0; 487 } 488 489 /* 490 * Verify one "dm_verity_io" structure. 491 */ 492 static int verity_verify_io(struct dm_verity_io *io) 493 { 494 struct dm_verity *v = io->v; 495 const unsigned int block_size = 1 << v->data_dev_block_bits; 496 struct bvec_iter iter_copy; 497 struct bvec_iter *iter; 498 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 499 unsigned int b; 500 501 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 502 /* 503 * Copy the iterator in case we need to restart 504 * verification in a work-queue. 505 */ 506 iter_copy = io->iter; 507 iter = &iter_copy; 508 } else 509 iter = &io->iter; 510 511 for (b = 0; b < io->n_blocks; 512 b++, bio_advance_iter(bio, iter, block_size)) { 513 int r; 514 sector_t cur_block = io->block + b; 515 bool is_zero; 516 struct bio_vec bv; 517 void *data; 518 519 if (v->validated_blocks && bio->bi_status == BLK_STS_OK && 520 likely(test_bit(cur_block, v->validated_blocks))) 521 continue; 522 523 r = verity_hash_for_block(v, io, cur_block, 524 verity_io_want_digest(v, io), 525 &is_zero); 526 if (unlikely(r < 0)) 527 return r; 528 529 bv = bio_iter_iovec(bio, *iter); 530 if (unlikely(bv.bv_len < block_size)) { 531 /* 532 * Data block spans pages. This should not happen, 533 * since dm-verity sets dma_alignment to the data block 534 * size minus 1, and dm-verity also doesn't allow the 535 * data block size to be greater than PAGE_SIZE. 536 */ 537 DMERR_LIMIT("unaligned io (data block spans pages)"); 538 return -EIO; 539 } 540 541 data = bvec_kmap_local(&bv); 542 543 if (is_zero) { 544 /* 545 * If we expect a zero block, don't validate, just 546 * return zeros. 547 */ 548 memset(data, 0, block_size); 549 kunmap_local(data); 550 continue; 551 } 552 553 r = verity_hash(v, io, data, block_size, 554 verity_io_real_digest(v, io), !io->in_bh); 555 if (unlikely(r < 0)) { 556 kunmap_local(data); 557 return r; 558 } 559 560 if (likely(memcmp(verity_io_real_digest(v, io), 561 verity_io_want_digest(v, io), v->digest_size) == 0)) { 562 if (v->validated_blocks) 563 set_bit(cur_block, v->validated_blocks); 564 kunmap_local(data); 565 continue; 566 } 567 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block, 568 data); 569 kunmap_local(data); 570 if (unlikely(r)) 571 return r; 572 } 573 574 return 0; 575 } 576 577 /* 578 * Skip verity work in response to I/O error when system is shutting down. 579 */ 580 static inline bool verity_is_system_shutting_down(void) 581 { 582 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 583 || system_state == SYSTEM_RESTART; 584 } 585 586 /* 587 * End one "io" structure with a given error. 588 */ 589 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 590 { 591 struct dm_verity *v = io->v; 592 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 593 594 bio->bi_end_io = io->orig_bi_end_io; 595 bio->bi_status = status; 596 597 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh) 598 verity_fec_finish_io(io); 599 600 bio_endio(bio); 601 } 602 603 static void verity_work(struct work_struct *w) 604 { 605 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 606 607 io->in_bh = false; 608 609 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 610 } 611 612 static void verity_bh_work(struct work_struct *w) 613 { 614 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work); 615 int err; 616 617 io->in_bh = true; 618 err = verity_verify_io(io); 619 if (err == -EAGAIN || err == -ENOMEM) { 620 /* fallback to retrying with work-queue */ 621 INIT_WORK(&io->work, verity_work); 622 queue_work(io->v->verify_wq, &io->work); 623 return; 624 } 625 626 verity_finish_io(io, errno_to_blk_status(err)); 627 } 628 629 static void verity_end_io(struct bio *bio) 630 { 631 struct dm_verity_io *io = bio->bi_private; 632 633 if (bio->bi_status && 634 (!verity_fec_is_enabled(io->v) || 635 verity_is_system_shutting_down() || 636 (bio->bi_opf & REQ_RAHEAD))) { 637 verity_finish_io(io, bio->bi_status); 638 return; 639 } 640 641 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) { 642 INIT_WORK(&io->bh_work, verity_bh_work); 643 queue_work(system_bh_wq, &io->bh_work); 644 } else { 645 INIT_WORK(&io->work, verity_work); 646 queue_work(io->v->verify_wq, &io->work); 647 } 648 } 649 650 /* 651 * Prefetch buffers for the specified io. 652 * The root buffer is not prefetched, it is assumed that it will be cached 653 * all the time. 654 */ 655 static void verity_prefetch_io(struct work_struct *work) 656 { 657 struct dm_verity_prefetch_work *pw = 658 container_of(work, struct dm_verity_prefetch_work, work); 659 struct dm_verity *v = pw->v; 660 int i; 661 662 for (i = v->levels - 2; i >= 0; i--) { 663 sector_t hash_block_start; 664 sector_t hash_block_end; 665 666 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 667 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 668 669 if (!i) { 670 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 671 672 cluster >>= v->data_dev_block_bits; 673 if (unlikely(!cluster)) 674 goto no_prefetch_cluster; 675 676 if (unlikely(cluster & (cluster - 1))) 677 cluster = 1 << __fls(cluster); 678 679 hash_block_start &= ~(sector_t)(cluster - 1); 680 hash_block_end |= cluster - 1; 681 if (unlikely(hash_block_end >= v->hash_blocks)) 682 hash_block_end = v->hash_blocks - 1; 683 } 684 no_prefetch_cluster: 685 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start, 686 hash_block_end - hash_block_start + 1, 687 pw->ioprio); 688 } 689 690 kfree(pw); 691 } 692 693 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io, 694 unsigned short ioprio) 695 { 696 sector_t block = io->block; 697 unsigned int n_blocks = io->n_blocks; 698 struct dm_verity_prefetch_work *pw; 699 700 if (v->validated_blocks) { 701 while (n_blocks && test_bit(block, v->validated_blocks)) { 702 block++; 703 n_blocks--; 704 } 705 while (n_blocks && test_bit(block + n_blocks - 1, 706 v->validated_blocks)) 707 n_blocks--; 708 if (!n_blocks) 709 return; 710 } 711 712 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 713 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 714 715 if (!pw) 716 return; 717 718 INIT_WORK(&pw->work, verity_prefetch_io); 719 pw->v = v; 720 pw->block = block; 721 pw->n_blocks = n_blocks; 722 pw->ioprio = ioprio; 723 queue_work(v->verify_wq, &pw->work); 724 } 725 726 /* 727 * Bio map function. It allocates dm_verity_io structure and bio vector and 728 * fills them. Then it issues prefetches and the I/O. 729 */ 730 static int verity_map(struct dm_target *ti, struct bio *bio) 731 { 732 struct dm_verity *v = ti->private; 733 struct dm_verity_io *io; 734 735 bio_set_dev(bio, v->data_dev->bdev); 736 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 737 738 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 739 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 740 DMERR_LIMIT("unaligned io"); 741 return DM_MAPIO_KILL; 742 } 743 744 if (bio_end_sector(bio) >> 745 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 746 DMERR_LIMIT("io out of range"); 747 return DM_MAPIO_KILL; 748 } 749 750 if (bio_data_dir(bio) == WRITE) 751 return DM_MAPIO_KILL; 752 753 io = dm_per_bio_data(bio, ti->per_io_data_size); 754 io->v = v; 755 io->orig_bi_end_io = bio->bi_end_io; 756 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 757 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 758 759 bio->bi_end_io = verity_end_io; 760 bio->bi_private = io; 761 io->iter = bio->bi_iter; 762 763 verity_fec_init_io(io); 764 765 verity_submit_prefetch(v, io, bio_prio(bio)); 766 767 submit_bio_noacct(bio); 768 769 return DM_MAPIO_SUBMITTED; 770 } 771 772 /* 773 * Status: V (valid) or C (corruption found) 774 */ 775 static void verity_status(struct dm_target *ti, status_type_t type, 776 unsigned int status_flags, char *result, unsigned int maxlen) 777 { 778 struct dm_verity *v = ti->private; 779 unsigned int args = 0; 780 unsigned int sz = 0; 781 unsigned int x; 782 783 switch (type) { 784 case STATUSTYPE_INFO: 785 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 786 break; 787 case STATUSTYPE_TABLE: 788 DMEMIT("%u %s %s %u %u %llu %llu %s ", 789 v->version, 790 v->data_dev->name, 791 v->hash_dev->name, 792 1 << v->data_dev_block_bits, 793 1 << v->hash_dev_block_bits, 794 (unsigned long long)v->data_blocks, 795 (unsigned long long)v->hash_start, 796 v->alg_name 797 ); 798 for (x = 0; x < v->digest_size; x++) 799 DMEMIT("%02x", v->root_digest[x]); 800 DMEMIT(" "); 801 if (!v->salt_size) 802 DMEMIT("-"); 803 else 804 for (x = 0; x < v->salt_size; x++) 805 DMEMIT("%02x", v->salt[x]); 806 if (v->mode != DM_VERITY_MODE_EIO) 807 args++; 808 if (verity_fec_is_enabled(v)) 809 args += DM_VERITY_OPTS_FEC; 810 if (v->zero_digest) 811 args++; 812 if (v->validated_blocks) 813 args++; 814 if (v->use_bh_wq) 815 args++; 816 if (v->signature_key_desc) 817 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 818 if (!args) 819 return; 820 DMEMIT(" %u", args); 821 if (v->mode != DM_VERITY_MODE_EIO) { 822 DMEMIT(" "); 823 switch (v->mode) { 824 case DM_VERITY_MODE_LOGGING: 825 DMEMIT(DM_VERITY_OPT_LOGGING); 826 break; 827 case DM_VERITY_MODE_RESTART: 828 DMEMIT(DM_VERITY_OPT_RESTART); 829 break; 830 case DM_VERITY_MODE_PANIC: 831 DMEMIT(DM_VERITY_OPT_PANIC); 832 break; 833 default: 834 BUG(); 835 } 836 } 837 if (v->zero_digest) 838 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 839 if (v->validated_blocks) 840 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 841 if (v->use_bh_wq) 842 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 843 sz = verity_fec_status_table(v, sz, result, maxlen); 844 if (v->signature_key_desc) 845 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 846 " %s", v->signature_key_desc); 847 break; 848 849 case STATUSTYPE_IMA: 850 DMEMIT_TARGET_NAME_VERSION(ti->type); 851 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 852 DMEMIT(",verity_version=%u", v->version); 853 DMEMIT(",data_device_name=%s", v->data_dev->name); 854 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 855 DMEMIT(",verity_algorithm=%s", v->alg_name); 856 857 DMEMIT(",root_digest="); 858 for (x = 0; x < v->digest_size; x++) 859 DMEMIT("%02x", v->root_digest[x]); 860 861 DMEMIT(",salt="); 862 if (!v->salt_size) 863 DMEMIT("-"); 864 else 865 for (x = 0; x < v->salt_size; x++) 866 DMEMIT("%02x", v->salt[x]); 867 868 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 869 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 870 if (v->signature_key_desc) 871 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 872 873 if (v->mode != DM_VERITY_MODE_EIO) { 874 DMEMIT(",verity_mode="); 875 switch (v->mode) { 876 case DM_VERITY_MODE_LOGGING: 877 DMEMIT(DM_VERITY_OPT_LOGGING); 878 break; 879 case DM_VERITY_MODE_RESTART: 880 DMEMIT(DM_VERITY_OPT_RESTART); 881 break; 882 case DM_VERITY_MODE_PANIC: 883 DMEMIT(DM_VERITY_OPT_PANIC); 884 break; 885 default: 886 DMEMIT("invalid"); 887 } 888 } 889 DMEMIT(";"); 890 break; 891 } 892 } 893 894 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 895 { 896 struct dm_verity *v = ti->private; 897 898 *bdev = v->data_dev->bdev; 899 900 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 901 return 1; 902 return 0; 903 } 904 905 static int verity_iterate_devices(struct dm_target *ti, 906 iterate_devices_callout_fn fn, void *data) 907 { 908 struct dm_verity *v = ti->private; 909 910 return fn(ti, v->data_dev, v->data_start, ti->len, data); 911 } 912 913 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 914 { 915 struct dm_verity *v = ti->private; 916 917 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 918 limits->logical_block_size = 1 << v->data_dev_block_bits; 919 920 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 921 limits->physical_block_size = 1 << v->data_dev_block_bits; 922 923 limits->io_min = limits->logical_block_size; 924 925 /* 926 * Similar to what dm-crypt does, opt dm-verity out of support for 927 * direct I/O that is aligned to less than the traditional direct I/O 928 * alignment requirement of logical_block_size. This prevents dm-verity 929 * data blocks from crossing pages, eliminating various edge cases. 930 */ 931 limits->dma_alignment = limits->logical_block_size - 1; 932 } 933 934 #ifdef CONFIG_SECURITY 935 936 static int verity_init_sig(struct dm_verity *v, const void *sig, 937 size_t sig_size) 938 { 939 v->sig_size = sig_size; 940 941 if (sig) { 942 v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL); 943 if (!v->root_digest_sig) 944 return -ENOMEM; 945 } 946 947 return 0; 948 } 949 950 static void verity_free_sig(struct dm_verity *v) 951 { 952 kfree(v->root_digest_sig); 953 } 954 955 #else 956 957 static inline int verity_init_sig(struct dm_verity *v, const void *sig, 958 size_t sig_size) 959 { 960 return 0; 961 } 962 963 static inline void verity_free_sig(struct dm_verity *v) 964 { 965 } 966 967 #endif /* CONFIG_SECURITY */ 968 969 static void verity_dtr(struct dm_target *ti) 970 { 971 struct dm_verity *v = ti->private; 972 973 if (v->verify_wq) 974 destroy_workqueue(v->verify_wq); 975 976 mempool_exit(&v->recheck_pool); 977 if (v->io) 978 dm_io_client_destroy(v->io); 979 980 if (v->bufio) 981 dm_bufio_client_destroy(v->bufio); 982 983 kvfree(v->validated_blocks); 984 kfree(v->salt); 985 kfree(v->initial_hashstate); 986 kfree(v->root_digest); 987 kfree(v->zero_digest); 988 verity_free_sig(v); 989 990 if (v->ahash_tfm) { 991 static_branch_dec(&ahash_enabled); 992 crypto_free_ahash(v->ahash_tfm); 993 } else { 994 crypto_free_shash(v->shash_tfm); 995 } 996 997 kfree(v->alg_name); 998 999 if (v->hash_dev) 1000 dm_put_device(ti, v->hash_dev); 1001 1002 if (v->data_dev) 1003 dm_put_device(ti, v->data_dev); 1004 1005 verity_fec_dtr(v); 1006 1007 kfree(v->signature_key_desc); 1008 1009 if (v->use_bh_wq) 1010 static_branch_dec(&use_bh_wq_enabled); 1011 1012 kfree(v); 1013 1014 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 1015 } 1016 1017 static int verity_alloc_most_once(struct dm_verity *v) 1018 { 1019 struct dm_target *ti = v->ti; 1020 1021 /* the bitset can only handle INT_MAX blocks */ 1022 if (v->data_blocks > INT_MAX) { 1023 ti->error = "device too large to use check_at_most_once"; 1024 return -E2BIG; 1025 } 1026 1027 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 1028 sizeof(unsigned long), 1029 GFP_KERNEL); 1030 if (!v->validated_blocks) { 1031 ti->error = "failed to allocate bitset for check_at_most_once"; 1032 return -ENOMEM; 1033 } 1034 1035 return 0; 1036 } 1037 1038 static int verity_alloc_zero_digest(struct dm_verity *v) 1039 { 1040 int r = -ENOMEM; 1041 struct dm_verity_io *io; 1042 u8 *zero_data; 1043 1044 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1045 1046 if (!v->zero_digest) 1047 return r; 1048 1049 io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL); 1050 1051 if (!io) 1052 return r; /* verity_dtr will free zero_digest */ 1053 1054 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1055 1056 if (!zero_data) 1057 goto out; 1058 1059 r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits, 1060 v->zero_digest, true); 1061 1062 out: 1063 kfree(io); 1064 kfree(zero_data); 1065 1066 return r; 1067 } 1068 1069 static inline bool verity_is_verity_mode(const char *arg_name) 1070 { 1071 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1072 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1073 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1074 } 1075 1076 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1077 { 1078 if (v->mode) 1079 return -EINVAL; 1080 1081 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1082 v->mode = DM_VERITY_MODE_LOGGING; 1083 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1084 v->mode = DM_VERITY_MODE_RESTART; 1085 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1086 v->mode = DM_VERITY_MODE_PANIC; 1087 1088 return 0; 1089 } 1090 1091 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1092 struct dm_verity_sig_opts *verify_args, 1093 bool only_modifier_opts) 1094 { 1095 int r = 0; 1096 unsigned int argc; 1097 struct dm_target *ti = v->ti; 1098 const char *arg_name; 1099 1100 static const struct dm_arg _args[] = { 1101 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1102 }; 1103 1104 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1105 if (r) 1106 return -EINVAL; 1107 1108 if (!argc) 1109 return 0; 1110 1111 do { 1112 arg_name = dm_shift_arg(as); 1113 argc--; 1114 1115 if (verity_is_verity_mode(arg_name)) { 1116 if (only_modifier_opts) 1117 continue; 1118 r = verity_parse_verity_mode(v, arg_name); 1119 if (r) { 1120 ti->error = "Conflicting error handling parameters"; 1121 return r; 1122 } 1123 continue; 1124 1125 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1126 if (only_modifier_opts) 1127 continue; 1128 r = verity_alloc_zero_digest(v); 1129 if (r) { 1130 ti->error = "Cannot allocate zero digest"; 1131 return r; 1132 } 1133 continue; 1134 1135 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1136 if (only_modifier_opts) 1137 continue; 1138 r = verity_alloc_most_once(v); 1139 if (r) 1140 return r; 1141 continue; 1142 1143 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1144 v->use_bh_wq = true; 1145 static_branch_inc(&use_bh_wq_enabled); 1146 continue; 1147 1148 } else if (verity_is_fec_opt_arg(arg_name)) { 1149 if (only_modifier_opts) 1150 continue; 1151 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1152 if (r) 1153 return r; 1154 continue; 1155 1156 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1157 if (only_modifier_opts) 1158 continue; 1159 r = verity_verify_sig_parse_opt_args(as, v, 1160 verify_args, 1161 &argc, arg_name); 1162 if (r) 1163 return r; 1164 continue; 1165 1166 } else if (only_modifier_opts) { 1167 /* 1168 * Ignore unrecognized opt, could easily be an extra 1169 * argument to an option whose parsing was skipped. 1170 * Normal parsing (@only_modifier_opts=false) will 1171 * properly parse all options (and their extra args). 1172 */ 1173 continue; 1174 } 1175 1176 DMERR("Unrecognized verity feature request: %s", arg_name); 1177 ti->error = "Unrecognized verity feature request"; 1178 return -EINVAL; 1179 } while (argc && !r); 1180 1181 return r; 1182 } 1183 1184 static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name) 1185 { 1186 struct dm_target *ti = v->ti; 1187 struct crypto_ahash *ahash; 1188 struct crypto_shash *shash = NULL; 1189 const char *driver_name; 1190 1191 v->alg_name = kstrdup(alg_name, GFP_KERNEL); 1192 if (!v->alg_name) { 1193 ti->error = "Cannot allocate algorithm name"; 1194 return -ENOMEM; 1195 } 1196 1197 /* 1198 * Allocate the hash transformation object that this dm-verity instance 1199 * will use. The vast majority of dm-verity users use CPU-based 1200 * hashing, so when possible use the shash API to minimize the crypto 1201 * API overhead. If the ahash API resolves to a different driver 1202 * (likely an off-CPU hardware offload), use ahash instead. Also use 1203 * ahash if the obsolete dm-verity format with the appended salt is 1204 * being used, so that quirk only needs to be handled in one place. 1205 */ 1206 ahash = crypto_alloc_ahash(alg_name, 0, 1207 v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0); 1208 if (IS_ERR(ahash)) { 1209 ti->error = "Cannot initialize hash function"; 1210 return PTR_ERR(ahash); 1211 } 1212 driver_name = crypto_ahash_driver_name(ahash); 1213 if (v->version >= 1 /* salt prepended, not appended? */) { 1214 shash = crypto_alloc_shash(alg_name, 0, 0); 1215 if (!IS_ERR(shash) && 1216 strcmp(crypto_shash_driver_name(shash), driver_name) != 0) { 1217 /* 1218 * ahash gave a different driver than shash, so probably 1219 * this is a case of real hardware offload. Use ahash. 1220 */ 1221 crypto_free_shash(shash); 1222 shash = NULL; 1223 } 1224 } 1225 if (!IS_ERR_OR_NULL(shash)) { 1226 crypto_free_ahash(ahash); 1227 ahash = NULL; 1228 v->shash_tfm = shash; 1229 v->digest_size = crypto_shash_digestsize(shash); 1230 v->hash_reqsize = sizeof(struct shash_desc) + 1231 crypto_shash_descsize(shash); 1232 DMINFO("%s using shash \"%s\"", alg_name, driver_name); 1233 } else { 1234 v->ahash_tfm = ahash; 1235 static_branch_inc(&ahash_enabled); 1236 v->digest_size = crypto_ahash_digestsize(ahash); 1237 v->hash_reqsize = sizeof(struct ahash_request) + 1238 crypto_ahash_reqsize(ahash); 1239 DMINFO("%s using ahash \"%s\"", alg_name, driver_name); 1240 } 1241 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1242 ti->error = "Digest size too big"; 1243 return -EINVAL; 1244 } 1245 return 0; 1246 } 1247 1248 static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg) 1249 { 1250 struct dm_target *ti = v->ti; 1251 1252 if (strcmp(arg, "-") != 0) { 1253 v->salt_size = strlen(arg) / 2; 1254 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1255 if (!v->salt) { 1256 ti->error = "Cannot allocate salt"; 1257 return -ENOMEM; 1258 } 1259 if (strlen(arg) != v->salt_size * 2 || 1260 hex2bin(v->salt, arg, v->salt_size)) { 1261 ti->error = "Invalid salt"; 1262 return -EINVAL; 1263 } 1264 } 1265 if (v->shash_tfm) { 1266 SHASH_DESC_ON_STACK(desc, v->shash_tfm); 1267 int r; 1268 1269 /* 1270 * Compute the pre-salted hash state that can be passed to 1271 * crypto_shash_import() for each block later. 1272 */ 1273 v->initial_hashstate = kmalloc( 1274 crypto_shash_statesize(v->shash_tfm), GFP_KERNEL); 1275 if (!v->initial_hashstate) { 1276 ti->error = "Cannot allocate initial hash state"; 1277 return -ENOMEM; 1278 } 1279 desc->tfm = v->shash_tfm; 1280 r = crypto_shash_init(desc) ?: 1281 crypto_shash_update(desc, v->salt, v->salt_size) ?: 1282 crypto_shash_export(desc, v->initial_hashstate); 1283 if (r) { 1284 ti->error = "Cannot set up initial hash state"; 1285 return r; 1286 } 1287 } 1288 return 0; 1289 } 1290 1291 /* 1292 * Target parameters: 1293 * <version> The current format is version 1. 1294 * Vsn 0 is compatible with original Chromium OS releases. 1295 * <data device> 1296 * <hash device> 1297 * <data block size> 1298 * <hash block size> 1299 * <the number of data blocks> 1300 * <hash start block> 1301 * <algorithm> 1302 * <digest> 1303 * <salt> Hex string or "-" if no salt. 1304 */ 1305 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1306 { 1307 struct dm_verity *v; 1308 struct dm_verity_sig_opts verify_args = {0}; 1309 struct dm_arg_set as; 1310 unsigned int num; 1311 unsigned long long num_ll; 1312 int r; 1313 int i; 1314 sector_t hash_position; 1315 char dummy; 1316 char *root_hash_digest_to_validate; 1317 1318 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1319 if (!v) { 1320 ti->error = "Cannot allocate verity structure"; 1321 return -ENOMEM; 1322 } 1323 ti->private = v; 1324 v->ti = ti; 1325 1326 r = verity_fec_ctr_alloc(v); 1327 if (r) 1328 goto bad; 1329 1330 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1331 ti->error = "Device must be readonly"; 1332 r = -EINVAL; 1333 goto bad; 1334 } 1335 1336 if (argc < 10) { 1337 ti->error = "Not enough arguments"; 1338 r = -EINVAL; 1339 goto bad; 1340 } 1341 1342 /* Parse optional parameters that modify primary args */ 1343 if (argc > 10) { 1344 as.argc = argc - 10; 1345 as.argv = argv + 10; 1346 r = verity_parse_opt_args(&as, v, &verify_args, true); 1347 if (r < 0) 1348 goto bad; 1349 } 1350 1351 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1352 num > 1) { 1353 ti->error = "Invalid version"; 1354 r = -EINVAL; 1355 goto bad; 1356 } 1357 v->version = num; 1358 1359 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1360 if (r) { 1361 ti->error = "Data device lookup failed"; 1362 goto bad; 1363 } 1364 1365 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1366 if (r) { 1367 ti->error = "Hash device lookup failed"; 1368 goto bad; 1369 } 1370 1371 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1372 !num || (num & (num - 1)) || 1373 num < bdev_logical_block_size(v->data_dev->bdev) || 1374 num > PAGE_SIZE) { 1375 ti->error = "Invalid data device block size"; 1376 r = -EINVAL; 1377 goto bad; 1378 } 1379 v->data_dev_block_bits = __ffs(num); 1380 1381 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1382 !num || (num & (num - 1)) || 1383 num < bdev_logical_block_size(v->hash_dev->bdev) || 1384 num > INT_MAX) { 1385 ti->error = "Invalid hash device block size"; 1386 r = -EINVAL; 1387 goto bad; 1388 } 1389 v->hash_dev_block_bits = __ffs(num); 1390 1391 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1392 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1393 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1394 ti->error = "Invalid data blocks"; 1395 r = -EINVAL; 1396 goto bad; 1397 } 1398 v->data_blocks = num_ll; 1399 1400 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1401 ti->error = "Data device is too small"; 1402 r = -EINVAL; 1403 goto bad; 1404 } 1405 1406 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1407 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1408 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1409 ti->error = "Invalid hash start"; 1410 r = -EINVAL; 1411 goto bad; 1412 } 1413 v->hash_start = num_ll; 1414 1415 r = verity_setup_hash_alg(v, argv[7]); 1416 if (r) 1417 goto bad; 1418 1419 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1420 if (!v->root_digest) { 1421 ti->error = "Cannot allocate root digest"; 1422 r = -ENOMEM; 1423 goto bad; 1424 } 1425 if (strlen(argv[8]) != v->digest_size * 2 || 1426 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1427 ti->error = "Invalid root digest"; 1428 r = -EINVAL; 1429 goto bad; 1430 } 1431 root_hash_digest_to_validate = argv[8]; 1432 1433 r = verity_setup_salt_and_hashstate(v, argv[9]); 1434 if (r) 1435 goto bad; 1436 1437 argv += 10; 1438 argc -= 10; 1439 1440 /* Optional parameters */ 1441 if (argc) { 1442 as.argc = argc; 1443 as.argv = argv; 1444 r = verity_parse_opt_args(&as, v, &verify_args, false); 1445 if (r < 0) 1446 goto bad; 1447 } 1448 1449 /* Root hash signature is a optional parameter*/ 1450 r = verity_verify_root_hash(root_hash_digest_to_validate, 1451 strlen(root_hash_digest_to_validate), 1452 verify_args.sig, 1453 verify_args.sig_size); 1454 if (r < 0) { 1455 ti->error = "Root hash verification failed"; 1456 goto bad; 1457 } 1458 1459 r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); 1460 if (r < 0) { 1461 ti->error = "Cannot allocate root digest signature"; 1462 goto bad; 1463 } 1464 1465 v->hash_per_block_bits = 1466 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1467 1468 v->levels = 0; 1469 if (v->data_blocks) 1470 while (v->hash_per_block_bits * v->levels < 64 && 1471 (unsigned long long)(v->data_blocks - 1) >> 1472 (v->hash_per_block_bits * v->levels)) 1473 v->levels++; 1474 1475 if (v->levels > DM_VERITY_MAX_LEVELS) { 1476 ti->error = "Too many tree levels"; 1477 r = -E2BIG; 1478 goto bad; 1479 } 1480 1481 hash_position = v->hash_start; 1482 for (i = v->levels - 1; i >= 0; i--) { 1483 sector_t s; 1484 1485 v->hash_level_block[i] = hash_position; 1486 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1487 >> ((i + 1) * v->hash_per_block_bits); 1488 if (hash_position + s < hash_position) { 1489 ti->error = "Hash device offset overflow"; 1490 r = -E2BIG; 1491 goto bad; 1492 } 1493 hash_position += s; 1494 } 1495 v->hash_blocks = hash_position; 1496 1497 r = mempool_init_page_pool(&v->recheck_pool, 1, 0); 1498 if (unlikely(r)) { 1499 ti->error = "Cannot allocate mempool"; 1500 goto bad; 1501 } 1502 1503 v->io = dm_io_client_create(); 1504 if (IS_ERR(v->io)) { 1505 r = PTR_ERR(v->io); 1506 v->io = NULL; 1507 ti->error = "Cannot allocate dm io"; 1508 goto bad; 1509 } 1510 1511 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1512 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1513 dm_bufio_alloc_callback, NULL, 1514 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1515 if (IS_ERR(v->bufio)) { 1516 ti->error = "Cannot initialize dm-bufio"; 1517 r = PTR_ERR(v->bufio); 1518 v->bufio = NULL; 1519 goto bad; 1520 } 1521 1522 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1523 ti->error = "Hash device is too small"; 1524 r = -E2BIG; 1525 goto bad; 1526 } 1527 1528 /* 1529 * Using WQ_HIGHPRI improves throughput and completion latency by 1530 * reducing wait times when reading from a dm-verity device. 1531 * 1532 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1533 * allows verify_wq to preempt softirq since verification in BH workqueue 1534 * will fall-back to using it for error handling (or if the bufio cache 1535 * doesn't have required hashes). 1536 */ 1537 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1538 if (!v->verify_wq) { 1539 ti->error = "Cannot allocate workqueue"; 1540 r = -ENOMEM; 1541 goto bad; 1542 } 1543 1544 ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize; 1545 1546 r = verity_fec_ctr(v); 1547 if (r) 1548 goto bad; 1549 1550 ti->per_io_data_size = roundup(ti->per_io_data_size, 1551 __alignof__(struct dm_verity_io)); 1552 1553 verity_verify_sig_opts_cleanup(&verify_args); 1554 1555 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1556 1557 return 0; 1558 1559 bad: 1560 1561 verity_verify_sig_opts_cleanup(&verify_args); 1562 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1563 verity_dtr(ti); 1564 1565 return r; 1566 } 1567 1568 /* 1569 * Get the verity mode (error behavior) of a verity target. 1570 * 1571 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1572 * target. 1573 */ 1574 int dm_verity_get_mode(struct dm_target *ti) 1575 { 1576 struct dm_verity *v = ti->private; 1577 1578 if (!dm_is_verity_target(ti)) 1579 return -EINVAL; 1580 1581 return v->mode; 1582 } 1583 1584 /* 1585 * Get the root digest of a verity target. 1586 * 1587 * Returns a copy of the root digest, the caller is responsible for 1588 * freeing the memory of the digest. 1589 */ 1590 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1591 { 1592 struct dm_verity *v = ti->private; 1593 1594 if (!dm_is_verity_target(ti)) 1595 return -EINVAL; 1596 1597 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1598 if (*root_digest == NULL) 1599 return -ENOMEM; 1600 1601 *digest_size = v->digest_size; 1602 1603 return 0; 1604 } 1605 1606 #ifdef CONFIG_SECURITY 1607 1608 #ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG 1609 1610 static int verity_security_set_signature(struct block_device *bdev, 1611 struct dm_verity *v) 1612 { 1613 /* 1614 * if the dm-verity target is unsigned, v->root_digest_sig will 1615 * be NULL, and the hook call is still required to let LSMs mark 1616 * the device as unsigned. This information is crucial for LSMs to 1617 * block operations such as execution on unsigned files 1618 */ 1619 return security_bdev_setintegrity(bdev, 1620 LSM_INT_DMVERITY_SIG_VALID, 1621 v->root_digest_sig, 1622 v->sig_size); 1623 } 1624 1625 #else 1626 1627 static inline int verity_security_set_signature(struct block_device *bdev, 1628 struct dm_verity *v) 1629 { 1630 return 0; 1631 } 1632 1633 #endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */ 1634 1635 /* 1636 * Expose verity target's root hash and signature data to LSMs before resume. 1637 * 1638 * Returns 0 on success, or -ENOMEM if the system is out of memory. 1639 */ 1640 static int verity_preresume(struct dm_target *ti) 1641 { 1642 struct block_device *bdev; 1643 struct dm_verity_digest root_digest; 1644 struct dm_verity *v; 1645 int r; 1646 1647 v = ti->private; 1648 bdev = dm_disk(dm_table_get_md(ti->table))->part0; 1649 root_digest.digest = v->root_digest; 1650 root_digest.digest_len = v->digest_size; 1651 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) 1652 root_digest.alg = crypto_ahash_alg_name(v->ahash_tfm); 1653 else 1654 root_digest.alg = crypto_shash_alg_name(v->shash_tfm); 1655 1656 r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest, 1657 sizeof(root_digest)); 1658 if (r) 1659 return r; 1660 1661 r = verity_security_set_signature(bdev, v); 1662 if (r) 1663 goto bad; 1664 1665 return 0; 1666 1667 bad: 1668 1669 security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0); 1670 1671 return r; 1672 } 1673 1674 #endif /* CONFIG_SECURITY */ 1675 1676 static struct target_type verity_target = { 1677 .name = "verity", 1678 /* Note: the LSMs depend on the singleton and immutable features */ 1679 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, 1680 .version = {1, 10, 0}, 1681 .module = THIS_MODULE, 1682 .ctr = verity_ctr, 1683 .dtr = verity_dtr, 1684 .map = verity_map, 1685 .status = verity_status, 1686 .prepare_ioctl = verity_prepare_ioctl, 1687 .iterate_devices = verity_iterate_devices, 1688 .io_hints = verity_io_hints, 1689 #ifdef CONFIG_SECURITY 1690 .preresume = verity_preresume, 1691 #endif /* CONFIG_SECURITY */ 1692 }; 1693 module_dm(verity); 1694 1695 /* 1696 * Check whether a DM target is a verity target. 1697 */ 1698 bool dm_is_verity_target(struct dm_target *ti) 1699 { 1700 return ti->type == &verity_target; 1701 } 1702 1703 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1704 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1705 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1706 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1707 MODULE_LICENSE("GPL"); 1708