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_ERROR_RESTART "restart_on_error" 40 #define DM_VERITY_OPT_ERROR_PANIC "panic_on_error" 41 #define DM_VERITY_OPT_IGN_ZEROES "ignore_zero_blocks" 42 #define DM_VERITY_OPT_AT_MOST_ONCE "check_at_most_once" 43 #define DM_VERITY_OPT_TASKLET_VERIFY "try_verify_in_tasklet" 44 45 #define DM_VERITY_OPTS_MAX (5 + DM_VERITY_OPTS_FEC + \ 46 DM_VERITY_ROOT_HASH_VERIFICATION_OPTS) 47 48 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 49 50 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644); 51 52 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled); 53 54 /* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */ 55 static DEFINE_STATIC_KEY_FALSE(ahash_enabled); 56 57 struct dm_verity_prefetch_work { 58 struct work_struct work; 59 struct dm_verity *v; 60 unsigned short ioprio; 61 sector_t block; 62 unsigned int n_blocks; 63 }; 64 65 /* 66 * Auxiliary structure appended to each dm-bufio buffer. If the value 67 * hash_verified is nonzero, hash of the block has been verified. 68 * 69 * The variable hash_verified is set to 0 when allocating the buffer, then 70 * it can be changed to 1 and it is never reset to 0 again. 71 * 72 * There is no lock around this value, a race condition can at worst cause 73 * that multiple processes verify the hash of the same buffer simultaneously 74 * and write 1 to hash_verified simultaneously. 75 * This condition is harmless, so we don't need locking. 76 */ 77 struct buffer_aux { 78 int hash_verified; 79 }; 80 81 /* 82 * Initialize struct buffer_aux for a freshly created buffer. 83 */ 84 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 85 { 86 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 87 88 aux->hash_verified = 0; 89 } 90 91 /* 92 * Translate input sector number to the sector number on the target device. 93 */ 94 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 95 { 96 return v->data_start + dm_target_offset(v->ti, bi_sector); 97 } 98 99 /* 100 * Return hash position of a specified block at a specified tree level 101 * (0 is the lowest level). 102 * The lowest "hash_per_block_bits"-bits of the result denote hash position 103 * inside a hash block. The remaining bits denote location of the hash block. 104 */ 105 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 106 int level) 107 { 108 return block >> (level * v->hash_per_block_bits); 109 } 110 111 static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req, 112 const u8 *data, size_t len, 113 struct crypto_wait *wait) 114 { 115 struct scatterlist sg; 116 117 if (likely(!is_vmalloc_addr(data))) { 118 sg_init_one(&sg, data, len); 119 ahash_request_set_crypt(req, &sg, NULL, len); 120 return crypto_wait_req(crypto_ahash_update(req), wait); 121 } 122 123 do { 124 int r; 125 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data)); 126 127 flush_kernel_vmap_range((void *)data, this_step); 128 sg_init_table(&sg, 1); 129 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data)); 130 ahash_request_set_crypt(req, &sg, NULL, this_step); 131 r = crypto_wait_req(crypto_ahash_update(req), wait); 132 if (unlikely(r)) 133 return r; 134 data += this_step; 135 len -= this_step; 136 } while (len); 137 138 return 0; 139 } 140 141 /* 142 * Wrapper for crypto_ahash_init, which handles verity salting. 143 */ 144 static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req, 145 struct crypto_wait *wait, bool may_sleep) 146 { 147 int r; 148 149 ahash_request_set_tfm(req, v->ahash_tfm); 150 ahash_request_set_callback(req, 151 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0, 152 crypto_req_done, (void *)wait); 153 crypto_init_wait(wait); 154 155 r = crypto_wait_req(crypto_ahash_init(req), wait); 156 157 if (unlikely(r < 0)) { 158 if (r != -ENOMEM) 159 DMERR("crypto_ahash_init failed: %d", r); 160 return r; 161 } 162 163 if (likely(v->salt_size && (v->version >= 1))) 164 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait); 165 166 return r; 167 } 168 169 static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req, 170 u8 *digest, struct crypto_wait *wait) 171 { 172 int r; 173 174 if (unlikely(v->salt_size && (!v->version))) { 175 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait); 176 177 if (r < 0) { 178 DMERR("%s failed updating salt: %d", __func__, r); 179 goto out; 180 } 181 } 182 183 ahash_request_set_crypt(req, NULL, digest, 0); 184 r = crypto_wait_req(crypto_ahash_final(req), wait); 185 out: 186 return r; 187 } 188 189 int verity_hash(struct dm_verity *v, struct dm_verity_io *io, 190 const u8 *data, size_t len, u8 *digest, bool may_sleep) 191 { 192 int r; 193 194 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) { 195 struct ahash_request *req = verity_io_hash_req(v, io); 196 struct crypto_wait wait; 197 198 r = verity_ahash_init(v, req, &wait, may_sleep) ?: 199 verity_ahash_update(v, req, data, len, &wait) ?: 200 verity_ahash_final(v, req, digest, &wait); 201 } else { 202 struct shash_desc *desc = verity_io_hash_req(v, io); 203 204 desc->tfm = v->shash_tfm; 205 r = crypto_shash_import(desc, v->initial_hashstate) ?: 206 crypto_shash_finup(desc, data, len, digest); 207 } 208 if (unlikely(r)) 209 DMERR("Error hashing block: %d", r); 210 return r; 211 } 212 213 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 214 sector_t *hash_block, unsigned int *offset) 215 { 216 sector_t position = verity_position_at_level(v, block, level); 217 unsigned int idx; 218 219 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 220 221 if (!offset) 222 return; 223 224 idx = position & ((1 << v->hash_per_block_bits) - 1); 225 if (!v->version) 226 *offset = idx * v->digest_size; 227 else 228 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 229 } 230 231 /* 232 * Handle verification errors. 233 */ 234 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 235 unsigned long long block) 236 { 237 char verity_env[DM_VERITY_ENV_LENGTH]; 238 char *envp[] = { verity_env, NULL }; 239 const char *type_str = ""; 240 struct mapped_device *md = dm_table_get_md(v->ti->table); 241 242 /* Corruption should be visible in device status in all modes */ 243 v->hash_failed = true; 244 245 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 246 goto out; 247 248 v->corrupted_errs++; 249 250 switch (type) { 251 case DM_VERITY_BLOCK_TYPE_DATA: 252 type_str = "data"; 253 break; 254 case DM_VERITY_BLOCK_TYPE_METADATA: 255 type_str = "metadata"; 256 break; 257 default: 258 BUG(); 259 } 260 261 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 262 type_str, block); 263 264 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { 265 DMERR("%s: reached maximum errors", v->data_dev->name); 266 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); 267 } 268 269 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 270 DM_VERITY_ENV_VAR_NAME, type, block); 271 272 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 273 274 out: 275 if (v->mode == DM_VERITY_MODE_LOGGING) 276 return 0; 277 278 if (v->mode == DM_VERITY_MODE_RESTART) 279 kernel_restart("dm-verity device corrupted"); 280 281 if (v->mode == DM_VERITY_MODE_PANIC) 282 panic("dm-verity device corrupted"); 283 284 return 1; 285 } 286 287 /* 288 * Verify hash of a metadata block pertaining to the specified data block 289 * ("block" argument) at a specified level ("level" argument). 290 * 291 * On successful return, verity_io_want_digest(v, io) contains the hash value 292 * for a lower tree level or for the data block (if we're at the lowest level). 293 * 294 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 295 * If "skip_unverified" is false, unverified buffer is hashed and verified 296 * against current value of verity_io_want_digest(v, io). 297 */ 298 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 299 sector_t block, int level, bool skip_unverified, 300 u8 *want_digest) 301 { 302 struct dm_buffer *buf; 303 struct buffer_aux *aux; 304 u8 *data; 305 int r; 306 sector_t hash_block; 307 unsigned int offset; 308 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 309 310 verity_hash_at_level(v, block, level, &hash_block, &offset); 311 312 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 313 data = dm_bufio_get(v->bufio, hash_block, &buf); 314 if (data == NULL) { 315 /* 316 * In tasklet and the hash was not in the bufio cache. 317 * Return early and resume execution from a work-queue 318 * to read the hash from disk. 319 */ 320 return -EAGAIN; 321 } 322 } else { 323 data = dm_bufio_read_with_ioprio(v->bufio, hash_block, 324 &buf, bio_prio(bio)); 325 } 326 327 if (IS_ERR(data)) 328 return PTR_ERR(data); 329 330 aux = dm_bufio_get_aux_data(buf); 331 332 if (!aux->hash_verified) { 333 if (skip_unverified) { 334 r = 1; 335 goto release_ret_r; 336 } 337 338 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits, 339 verity_io_real_digest(v, io), !io->in_bh); 340 if (unlikely(r < 0)) 341 goto release_ret_r; 342 343 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 344 v->digest_size) == 0)) 345 aux->hash_verified = 1; 346 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 347 /* 348 * Error handling code (FEC included) cannot be run in a 349 * tasklet since it may sleep, so fallback to work-queue. 350 */ 351 r = -EAGAIN; 352 goto release_ret_r; 353 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 354 hash_block, data) == 0) 355 aux->hash_verified = 1; 356 else if (verity_handle_err(v, 357 DM_VERITY_BLOCK_TYPE_METADATA, 358 hash_block)) { 359 struct bio *bio; 360 io->had_mismatch = true; 361 bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 362 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, 363 block, 0); 364 r = -EIO; 365 goto release_ret_r; 366 } 367 } 368 369 data += offset; 370 memcpy(want_digest, data, v->digest_size); 371 r = 0; 372 373 release_ret_r: 374 dm_bufio_release(buf); 375 return r; 376 } 377 378 /* 379 * Find a hash for a given block, write it to digest and verify the integrity 380 * of the hash tree if necessary. 381 */ 382 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 383 sector_t block, u8 *digest, bool *is_zero) 384 { 385 int r = 0, i; 386 387 if (likely(v->levels)) { 388 /* 389 * First, we try to get the requested hash for 390 * the current block. If the hash block itself is 391 * verified, zero is returned. If it isn't, this 392 * function returns 1 and we fall back to whole 393 * chain verification. 394 */ 395 r = verity_verify_level(v, io, block, 0, true, digest); 396 if (likely(r <= 0)) 397 goto out; 398 } 399 400 memcpy(digest, v->root_digest, v->digest_size); 401 402 for (i = v->levels - 1; i >= 0; i--) { 403 r = verity_verify_level(v, io, block, i, false, digest); 404 if (unlikely(r)) 405 goto out; 406 } 407 out: 408 if (!r && v->zero_digest) 409 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 410 else 411 *is_zero = false; 412 413 return r; 414 } 415 416 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io, 417 sector_t cur_block, u8 *dest) 418 { 419 struct page *page; 420 void *buffer; 421 int r; 422 struct dm_io_request io_req; 423 struct dm_io_region io_loc; 424 425 page = mempool_alloc(&v->recheck_pool, GFP_NOIO); 426 buffer = page_to_virt(page); 427 428 io_req.bi_opf = REQ_OP_READ; 429 io_req.mem.type = DM_IO_KMEM; 430 io_req.mem.ptr.addr = buffer; 431 io_req.notify.fn = NULL; 432 io_req.client = v->io; 433 io_loc.bdev = v->data_dev->bdev; 434 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT); 435 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT); 436 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT); 437 if (unlikely(r)) 438 goto free_ret; 439 440 r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits, 441 verity_io_real_digest(v, io), true); 442 if (unlikely(r)) 443 goto free_ret; 444 445 if (memcmp(verity_io_real_digest(v, io), 446 verity_io_want_digest(v, io), v->digest_size)) { 447 r = -EIO; 448 goto free_ret; 449 } 450 451 memcpy(dest, buffer, 1 << v->data_dev_block_bits); 452 r = 0; 453 free_ret: 454 mempool_free(page, &v->recheck_pool); 455 456 return r; 457 } 458 459 static int verity_handle_data_hash_mismatch(struct dm_verity *v, 460 struct dm_verity_io *io, 461 struct bio *bio, sector_t blkno, 462 u8 *data) 463 { 464 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 465 /* 466 * Error handling code (FEC included) cannot be run in the 467 * BH workqueue, so fallback to a standard workqueue. 468 */ 469 return -EAGAIN; 470 } 471 if (verity_recheck(v, io, blkno, data) == 0) { 472 if (v->validated_blocks) 473 set_bit(blkno, v->validated_blocks); 474 return 0; 475 } 476 #if defined(CONFIG_DM_VERITY_FEC) 477 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno, 478 data) == 0) 479 return 0; 480 #endif 481 if (bio->bi_status) 482 return -EIO; /* Error correction failed; Just return error */ 483 484 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) { 485 io->had_mismatch = true; 486 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0); 487 return -EIO; 488 } 489 return 0; 490 } 491 492 /* 493 * Verify one "dm_verity_io" structure. 494 */ 495 static int verity_verify_io(struct dm_verity_io *io) 496 { 497 struct dm_verity *v = io->v; 498 const unsigned int block_size = 1 << v->data_dev_block_bits; 499 struct bvec_iter iter_copy; 500 struct bvec_iter *iter; 501 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 502 unsigned int b; 503 504 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 505 /* 506 * Copy the iterator in case we need to restart 507 * verification in a work-queue. 508 */ 509 iter_copy = io->iter; 510 iter = &iter_copy; 511 } else 512 iter = &io->iter; 513 514 for (b = 0; b < io->n_blocks; 515 b++, bio_advance_iter(bio, iter, block_size)) { 516 int r; 517 sector_t cur_block = io->block + b; 518 bool is_zero; 519 struct bio_vec bv; 520 void *data; 521 522 if (v->validated_blocks && bio->bi_status == BLK_STS_OK && 523 likely(test_bit(cur_block, v->validated_blocks))) 524 continue; 525 526 r = verity_hash_for_block(v, io, cur_block, 527 verity_io_want_digest(v, io), 528 &is_zero); 529 if (unlikely(r < 0)) 530 return r; 531 532 bv = bio_iter_iovec(bio, *iter); 533 if (unlikely(bv.bv_len < block_size)) { 534 /* 535 * Data block spans pages. This should not happen, 536 * since dm-verity sets dma_alignment to the data block 537 * size minus 1, and dm-verity also doesn't allow the 538 * data block size to be greater than PAGE_SIZE. 539 */ 540 DMERR_LIMIT("unaligned io (data block spans pages)"); 541 return -EIO; 542 } 543 544 data = bvec_kmap_local(&bv); 545 546 if (is_zero) { 547 /* 548 * If we expect a zero block, don't validate, just 549 * return zeros. 550 */ 551 memset(data, 0, block_size); 552 kunmap_local(data); 553 continue; 554 } 555 556 r = verity_hash(v, io, data, block_size, 557 verity_io_real_digest(v, io), !io->in_bh); 558 if (unlikely(r < 0)) { 559 kunmap_local(data); 560 return r; 561 } 562 563 if (likely(memcmp(verity_io_real_digest(v, io), 564 verity_io_want_digest(v, io), v->digest_size) == 0)) { 565 if (v->validated_blocks) 566 set_bit(cur_block, v->validated_blocks); 567 kunmap_local(data); 568 continue; 569 } 570 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block, 571 data); 572 kunmap_local(data); 573 if (unlikely(r)) 574 return r; 575 } 576 577 return 0; 578 } 579 580 /* 581 * Skip verity work in response to I/O error when system is shutting down. 582 */ 583 static inline bool verity_is_system_shutting_down(void) 584 { 585 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 586 || system_state == SYSTEM_RESTART; 587 } 588 589 static void restart_io_error(struct work_struct *w) 590 { 591 kernel_restart("dm-verity device has I/O error"); 592 } 593 594 /* 595 * End one "io" structure with a given error. 596 */ 597 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 598 { 599 struct dm_verity *v = io->v; 600 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 601 602 bio->bi_end_io = io->orig_bi_end_io; 603 bio->bi_status = status; 604 605 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh) 606 verity_fec_finish_io(io); 607 608 if (unlikely(status != BLK_STS_OK) && 609 unlikely(!(bio->bi_opf & REQ_RAHEAD)) && 610 !io->had_mismatch && 611 !verity_is_system_shutting_down()) { 612 if (v->error_mode == DM_VERITY_MODE_PANIC) { 613 panic("dm-verity device has I/O error"); 614 } 615 if (v->error_mode == DM_VERITY_MODE_RESTART) { 616 static DECLARE_WORK(restart_work, restart_io_error); 617 queue_work(v->verify_wq, &restart_work); 618 /* 619 * We deliberately don't call bio_endio here, because 620 * the machine will be restarted anyway. 621 */ 622 return; 623 } 624 } 625 626 bio_endio(bio); 627 } 628 629 static void verity_work(struct work_struct *w) 630 { 631 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 632 633 io->in_bh = false; 634 635 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 636 } 637 638 static void verity_bh_work(struct work_struct *w) 639 { 640 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work); 641 int err; 642 643 io->in_bh = true; 644 err = verity_verify_io(io); 645 if (err == -EAGAIN || err == -ENOMEM) { 646 /* fallback to retrying with work-queue */ 647 INIT_WORK(&io->work, verity_work); 648 queue_work(io->v->verify_wq, &io->work); 649 return; 650 } 651 652 verity_finish_io(io, errno_to_blk_status(err)); 653 } 654 655 static void verity_end_io(struct bio *bio) 656 { 657 struct dm_verity_io *io = bio->bi_private; 658 659 if (bio->bi_status && 660 (!verity_fec_is_enabled(io->v) || 661 verity_is_system_shutting_down() || 662 (bio->bi_opf & REQ_RAHEAD))) { 663 verity_finish_io(io, bio->bi_status); 664 return; 665 } 666 667 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) { 668 INIT_WORK(&io->bh_work, verity_bh_work); 669 queue_work(system_bh_wq, &io->bh_work); 670 } else { 671 INIT_WORK(&io->work, verity_work); 672 queue_work(io->v->verify_wq, &io->work); 673 } 674 } 675 676 /* 677 * Prefetch buffers for the specified io. 678 * The root buffer is not prefetched, it is assumed that it will be cached 679 * all the time. 680 */ 681 static void verity_prefetch_io(struct work_struct *work) 682 { 683 struct dm_verity_prefetch_work *pw = 684 container_of(work, struct dm_verity_prefetch_work, work); 685 struct dm_verity *v = pw->v; 686 int i; 687 688 for (i = v->levels - 2; i >= 0; i--) { 689 sector_t hash_block_start; 690 sector_t hash_block_end; 691 692 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 693 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 694 695 if (!i) { 696 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 697 698 cluster >>= v->data_dev_block_bits; 699 if (unlikely(!cluster)) 700 goto no_prefetch_cluster; 701 702 if (unlikely(cluster & (cluster - 1))) 703 cluster = 1 << __fls(cluster); 704 705 hash_block_start &= ~(sector_t)(cluster - 1); 706 hash_block_end |= cluster - 1; 707 if (unlikely(hash_block_end >= v->hash_blocks)) 708 hash_block_end = v->hash_blocks - 1; 709 } 710 no_prefetch_cluster: 711 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start, 712 hash_block_end - hash_block_start + 1, 713 pw->ioprio); 714 } 715 716 kfree(pw); 717 } 718 719 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io, 720 unsigned short ioprio) 721 { 722 sector_t block = io->block; 723 unsigned int n_blocks = io->n_blocks; 724 struct dm_verity_prefetch_work *pw; 725 726 if (v->validated_blocks) { 727 while (n_blocks && test_bit(block, v->validated_blocks)) { 728 block++; 729 n_blocks--; 730 } 731 while (n_blocks && test_bit(block + n_blocks - 1, 732 v->validated_blocks)) 733 n_blocks--; 734 if (!n_blocks) 735 return; 736 } 737 738 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 739 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 740 741 if (!pw) 742 return; 743 744 INIT_WORK(&pw->work, verity_prefetch_io); 745 pw->v = v; 746 pw->block = block; 747 pw->n_blocks = n_blocks; 748 pw->ioprio = ioprio; 749 queue_work(v->verify_wq, &pw->work); 750 } 751 752 /* 753 * Bio map function. It allocates dm_verity_io structure and bio vector and 754 * fills them. Then it issues prefetches and the I/O. 755 */ 756 static int verity_map(struct dm_target *ti, struct bio *bio) 757 { 758 struct dm_verity *v = ti->private; 759 struct dm_verity_io *io; 760 761 bio_set_dev(bio, v->data_dev->bdev); 762 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 763 764 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 765 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 766 DMERR_LIMIT("unaligned io"); 767 return DM_MAPIO_KILL; 768 } 769 770 if (bio_end_sector(bio) >> 771 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 772 DMERR_LIMIT("io out of range"); 773 return DM_MAPIO_KILL; 774 } 775 776 if (bio_data_dir(bio) == WRITE) 777 return DM_MAPIO_KILL; 778 779 io = dm_per_bio_data(bio, ti->per_io_data_size); 780 io->v = v; 781 io->orig_bi_end_io = bio->bi_end_io; 782 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 783 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 784 io->had_mismatch = false; 785 786 bio->bi_end_io = verity_end_io; 787 bio->bi_private = io; 788 io->iter = bio->bi_iter; 789 790 verity_fec_init_io(io); 791 792 verity_submit_prefetch(v, io, bio_prio(bio)); 793 794 submit_bio_noacct(bio); 795 796 return DM_MAPIO_SUBMITTED; 797 } 798 799 /* 800 * Status: V (valid) or C (corruption found) 801 */ 802 static void verity_status(struct dm_target *ti, status_type_t type, 803 unsigned int status_flags, char *result, unsigned int maxlen) 804 { 805 struct dm_verity *v = ti->private; 806 unsigned int args = 0; 807 unsigned int sz = 0; 808 unsigned int x; 809 810 switch (type) { 811 case STATUSTYPE_INFO: 812 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 813 break; 814 case STATUSTYPE_TABLE: 815 DMEMIT("%u %s %s %u %u %llu %llu %s ", 816 v->version, 817 v->data_dev->name, 818 v->hash_dev->name, 819 1 << v->data_dev_block_bits, 820 1 << v->hash_dev_block_bits, 821 (unsigned long long)v->data_blocks, 822 (unsigned long long)v->hash_start, 823 v->alg_name 824 ); 825 for (x = 0; x < v->digest_size; x++) 826 DMEMIT("%02x", v->root_digest[x]); 827 DMEMIT(" "); 828 if (!v->salt_size) 829 DMEMIT("-"); 830 else 831 for (x = 0; x < v->salt_size; x++) 832 DMEMIT("%02x", v->salt[x]); 833 if (v->mode != DM_VERITY_MODE_EIO) 834 args++; 835 if (v->error_mode != DM_VERITY_MODE_EIO) 836 args++; 837 if (verity_fec_is_enabled(v)) 838 args += DM_VERITY_OPTS_FEC; 839 if (v->zero_digest) 840 args++; 841 if (v->validated_blocks) 842 args++; 843 if (v->use_bh_wq) 844 args++; 845 if (v->signature_key_desc) 846 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 847 if (!args) 848 return; 849 DMEMIT(" %u", args); 850 if (v->mode != DM_VERITY_MODE_EIO) { 851 DMEMIT(" "); 852 switch (v->mode) { 853 case DM_VERITY_MODE_LOGGING: 854 DMEMIT(DM_VERITY_OPT_LOGGING); 855 break; 856 case DM_VERITY_MODE_RESTART: 857 DMEMIT(DM_VERITY_OPT_RESTART); 858 break; 859 case DM_VERITY_MODE_PANIC: 860 DMEMIT(DM_VERITY_OPT_PANIC); 861 break; 862 default: 863 BUG(); 864 } 865 } 866 if (v->error_mode != DM_VERITY_MODE_EIO) { 867 DMEMIT(" "); 868 switch (v->error_mode) { 869 case DM_VERITY_MODE_RESTART: 870 DMEMIT(DM_VERITY_OPT_ERROR_RESTART); 871 break; 872 case DM_VERITY_MODE_PANIC: 873 DMEMIT(DM_VERITY_OPT_ERROR_PANIC); 874 break; 875 default: 876 BUG(); 877 } 878 } 879 if (v->zero_digest) 880 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 881 if (v->validated_blocks) 882 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 883 if (v->use_bh_wq) 884 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 885 sz = verity_fec_status_table(v, sz, result, maxlen); 886 if (v->signature_key_desc) 887 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 888 " %s", v->signature_key_desc); 889 break; 890 891 case STATUSTYPE_IMA: 892 DMEMIT_TARGET_NAME_VERSION(ti->type); 893 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 894 DMEMIT(",verity_version=%u", v->version); 895 DMEMIT(",data_device_name=%s", v->data_dev->name); 896 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 897 DMEMIT(",verity_algorithm=%s", v->alg_name); 898 899 DMEMIT(",root_digest="); 900 for (x = 0; x < v->digest_size; x++) 901 DMEMIT("%02x", v->root_digest[x]); 902 903 DMEMIT(",salt="); 904 if (!v->salt_size) 905 DMEMIT("-"); 906 else 907 for (x = 0; x < v->salt_size; x++) 908 DMEMIT("%02x", v->salt[x]); 909 910 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 911 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 912 if (v->signature_key_desc) 913 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 914 915 if (v->mode != DM_VERITY_MODE_EIO) { 916 DMEMIT(",verity_mode="); 917 switch (v->mode) { 918 case DM_VERITY_MODE_LOGGING: 919 DMEMIT(DM_VERITY_OPT_LOGGING); 920 break; 921 case DM_VERITY_MODE_RESTART: 922 DMEMIT(DM_VERITY_OPT_RESTART); 923 break; 924 case DM_VERITY_MODE_PANIC: 925 DMEMIT(DM_VERITY_OPT_PANIC); 926 break; 927 default: 928 DMEMIT("invalid"); 929 } 930 } 931 if (v->error_mode != DM_VERITY_MODE_EIO) { 932 DMEMIT(",verity_error_mode="); 933 switch (v->error_mode) { 934 case DM_VERITY_MODE_RESTART: 935 DMEMIT(DM_VERITY_OPT_ERROR_RESTART); 936 break; 937 case DM_VERITY_MODE_PANIC: 938 DMEMIT(DM_VERITY_OPT_ERROR_PANIC); 939 break; 940 default: 941 DMEMIT("invalid"); 942 } 943 } 944 DMEMIT(";"); 945 break; 946 } 947 } 948 949 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev) 950 { 951 struct dm_verity *v = ti->private; 952 953 *bdev = v->data_dev->bdev; 954 955 if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev)) 956 return 1; 957 return 0; 958 } 959 960 static int verity_iterate_devices(struct dm_target *ti, 961 iterate_devices_callout_fn fn, void *data) 962 { 963 struct dm_verity *v = ti->private; 964 965 return fn(ti, v->data_dev, v->data_start, ti->len, data); 966 } 967 968 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 969 { 970 struct dm_verity *v = ti->private; 971 972 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 973 limits->logical_block_size = 1 << v->data_dev_block_bits; 974 975 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 976 limits->physical_block_size = 1 << v->data_dev_block_bits; 977 978 limits->io_min = limits->logical_block_size; 979 980 /* 981 * Similar to what dm-crypt does, opt dm-verity out of support for 982 * direct I/O that is aligned to less than the traditional direct I/O 983 * alignment requirement of logical_block_size. This prevents dm-verity 984 * data blocks from crossing pages, eliminating various edge cases. 985 */ 986 limits->dma_alignment = limits->logical_block_size - 1; 987 } 988 989 #ifdef CONFIG_SECURITY 990 991 static int verity_init_sig(struct dm_verity *v, const void *sig, 992 size_t sig_size) 993 { 994 v->sig_size = sig_size; 995 996 if (sig) { 997 v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL); 998 if (!v->root_digest_sig) 999 return -ENOMEM; 1000 } 1001 1002 return 0; 1003 } 1004 1005 static void verity_free_sig(struct dm_verity *v) 1006 { 1007 kfree(v->root_digest_sig); 1008 } 1009 1010 #else 1011 1012 static inline int verity_init_sig(struct dm_verity *v, const void *sig, 1013 size_t sig_size) 1014 { 1015 return 0; 1016 } 1017 1018 static inline void verity_free_sig(struct dm_verity *v) 1019 { 1020 } 1021 1022 #endif /* CONFIG_SECURITY */ 1023 1024 static void verity_dtr(struct dm_target *ti) 1025 { 1026 struct dm_verity *v = ti->private; 1027 1028 if (v->verify_wq) 1029 destroy_workqueue(v->verify_wq); 1030 1031 mempool_exit(&v->recheck_pool); 1032 if (v->io) 1033 dm_io_client_destroy(v->io); 1034 1035 if (v->bufio) 1036 dm_bufio_client_destroy(v->bufio); 1037 1038 kvfree(v->validated_blocks); 1039 kfree(v->salt); 1040 kfree(v->initial_hashstate); 1041 kfree(v->root_digest); 1042 kfree(v->zero_digest); 1043 verity_free_sig(v); 1044 1045 if (v->ahash_tfm) { 1046 static_branch_dec(&ahash_enabled); 1047 crypto_free_ahash(v->ahash_tfm); 1048 } else { 1049 crypto_free_shash(v->shash_tfm); 1050 } 1051 1052 kfree(v->alg_name); 1053 1054 if (v->hash_dev) 1055 dm_put_device(ti, v->hash_dev); 1056 1057 if (v->data_dev) 1058 dm_put_device(ti, v->data_dev); 1059 1060 verity_fec_dtr(v); 1061 1062 kfree(v->signature_key_desc); 1063 1064 if (v->use_bh_wq) 1065 static_branch_dec(&use_bh_wq_enabled); 1066 1067 kfree(v); 1068 1069 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 1070 } 1071 1072 static int verity_alloc_most_once(struct dm_verity *v) 1073 { 1074 struct dm_target *ti = v->ti; 1075 1076 /* the bitset can only handle INT_MAX blocks */ 1077 if (v->data_blocks > INT_MAX) { 1078 ti->error = "device too large to use check_at_most_once"; 1079 return -E2BIG; 1080 } 1081 1082 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 1083 sizeof(unsigned long), 1084 GFP_KERNEL); 1085 if (!v->validated_blocks) { 1086 ti->error = "failed to allocate bitset for check_at_most_once"; 1087 return -ENOMEM; 1088 } 1089 1090 return 0; 1091 } 1092 1093 static int verity_alloc_zero_digest(struct dm_verity *v) 1094 { 1095 int r = -ENOMEM; 1096 struct dm_verity_io *io; 1097 u8 *zero_data; 1098 1099 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1100 1101 if (!v->zero_digest) 1102 return r; 1103 1104 io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL); 1105 1106 if (!io) 1107 return r; /* verity_dtr will free zero_digest */ 1108 1109 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1110 1111 if (!zero_data) 1112 goto out; 1113 1114 r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits, 1115 v->zero_digest, true); 1116 1117 out: 1118 kfree(io); 1119 kfree(zero_data); 1120 1121 return r; 1122 } 1123 1124 static inline bool verity_is_verity_mode(const char *arg_name) 1125 { 1126 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1127 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1128 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1129 } 1130 1131 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1132 { 1133 if (v->mode) 1134 return -EINVAL; 1135 1136 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1137 v->mode = DM_VERITY_MODE_LOGGING; 1138 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1139 v->mode = DM_VERITY_MODE_RESTART; 1140 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1141 v->mode = DM_VERITY_MODE_PANIC; 1142 1143 return 0; 1144 } 1145 1146 static inline bool verity_is_verity_error_mode(const char *arg_name) 1147 { 1148 return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) || 1149 !strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC)); 1150 } 1151 1152 static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name) 1153 { 1154 if (v->error_mode) 1155 return -EINVAL; 1156 1157 if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART)) 1158 v->error_mode = DM_VERITY_MODE_RESTART; 1159 else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC)) 1160 v->error_mode = DM_VERITY_MODE_PANIC; 1161 1162 return 0; 1163 } 1164 1165 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1166 struct dm_verity_sig_opts *verify_args, 1167 bool only_modifier_opts) 1168 { 1169 int r = 0; 1170 unsigned int argc; 1171 struct dm_target *ti = v->ti; 1172 const char *arg_name; 1173 1174 static const struct dm_arg _args[] = { 1175 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1176 }; 1177 1178 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1179 if (r) 1180 return -EINVAL; 1181 1182 if (!argc) 1183 return 0; 1184 1185 do { 1186 arg_name = dm_shift_arg(as); 1187 argc--; 1188 1189 if (verity_is_verity_mode(arg_name)) { 1190 if (only_modifier_opts) 1191 continue; 1192 r = verity_parse_verity_mode(v, arg_name); 1193 if (r) { 1194 ti->error = "Conflicting error handling parameters"; 1195 return r; 1196 } 1197 continue; 1198 1199 } else if (verity_is_verity_error_mode(arg_name)) { 1200 if (only_modifier_opts) 1201 continue; 1202 r = verity_parse_verity_error_mode(v, arg_name); 1203 if (r) { 1204 ti->error = "Conflicting error handling parameters"; 1205 return r; 1206 } 1207 continue; 1208 1209 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1210 if (only_modifier_opts) 1211 continue; 1212 r = verity_alloc_zero_digest(v); 1213 if (r) { 1214 ti->error = "Cannot allocate zero digest"; 1215 return r; 1216 } 1217 continue; 1218 1219 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1220 if (only_modifier_opts) 1221 continue; 1222 r = verity_alloc_most_once(v); 1223 if (r) 1224 return r; 1225 continue; 1226 1227 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1228 v->use_bh_wq = true; 1229 static_branch_inc(&use_bh_wq_enabled); 1230 continue; 1231 1232 } else if (verity_is_fec_opt_arg(arg_name)) { 1233 if (only_modifier_opts) 1234 continue; 1235 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1236 if (r) 1237 return r; 1238 continue; 1239 1240 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1241 if (only_modifier_opts) 1242 continue; 1243 r = verity_verify_sig_parse_opt_args(as, v, 1244 verify_args, 1245 &argc, arg_name); 1246 if (r) 1247 return r; 1248 continue; 1249 1250 } else if (only_modifier_opts) { 1251 /* 1252 * Ignore unrecognized opt, could easily be an extra 1253 * argument to an option whose parsing was skipped. 1254 * Normal parsing (@only_modifier_opts=false) will 1255 * properly parse all options (and their extra args). 1256 */ 1257 continue; 1258 } 1259 1260 DMERR("Unrecognized verity feature request: %s", arg_name); 1261 ti->error = "Unrecognized verity feature request"; 1262 return -EINVAL; 1263 } while (argc && !r); 1264 1265 return r; 1266 } 1267 1268 static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name) 1269 { 1270 struct dm_target *ti = v->ti; 1271 struct crypto_ahash *ahash; 1272 struct crypto_shash *shash = NULL; 1273 const char *driver_name; 1274 1275 v->alg_name = kstrdup(alg_name, GFP_KERNEL); 1276 if (!v->alg_name) { 1277 ti->error = "Cannot allocate algorithm name"; 1278 return -ENOMEM; 1279 } 1280 1281 /* 1282 * Allocate the hash transformation object that this dm-verity instance 1283 * will use. The vast majority of dm-verity users use CPU-based 1284 * hashing, so when possible use the shash API to minimize the crypto 1285 * API overhead. If the ahash API resolves to a different driver 1286 * (likely an off-CPU hardware offload), use ahash instead. Also use 1287 * ahash if the obsolete dm-verity format with the appended salt is 1288 * being used, so that quirk only needs to be handled in one place. 1289 */ 1290 ahash = crypto_alloc_ahash(alg_name, 0, 1291 v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0); 1292 if (IS_ERR(ahash)) { 1293 ti->error = "Cannot initialize hash function"; 1294 return PTR_ERR(ahash); 1295 } 1296 driver_name = crypto_ahash_driver_name(ahash); 1297 if (v->version >= 1 /* salt prepended, not appended? */) { 1298 shash = crypto_alloc_shash(alg_name, 0, 0); 1299 if (!IS_ERR(shash) && 1300 strcmp(crypto_shash_driver_name(shash), driver_name) != 0) { 1301 /* 1302 * ahash gave a different driver than shash, so probably 1303 * this is a case of real hardware offload. Use ahash. 1304 */ 1305 crypto_free_shash(shash); 1306 shash = NULL; 1307 } 1308 } 1309 if (!IS_ERR_OR_NULL(shash)) { 1310 crypto_free_ahash(ahash); 1311 ahash = NULL; 1312 v->shash_tfm = shash; 1313 v->digest_size = crypto_shash_digestsize(shash); 1314 v->hash_reqsize = sizeof(struct shash_desc) + 1315 crypto_shash_descsize(shash); 1316 DMINFO("%s using shash \"%s\"", alg_name, driver_name); 1317 } else { 1318 v->ahash_tfm = ahash; 1319 static_branch_inc(&ahash_enabled); 1320 v->digest_size = crypto_ahash_digestsize(ahash); 1321 v->hash_reqsize = sizeof(struct ahash_request) + 1322 crypto_ahash_reqsize(ahash); 1323 DMINFO("%s using ahash \"%s\"", alg_name, driver_name); 1324 } 1325 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1326 ti->error = "Digest size too big"; 1327 return -EINVAL; 1328 } 1329 return 0; 1330 } 1331 1332 static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg) 1333 { 1334 struct dm_target *ti = v->ti; 1335 1336 if (strcmp(arg, "-") != 0) { 1337 v->salt_size = strlen(arg) / 2; 1338 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1339 if (!v->salt) { 1340 ti->error = "Cannot allocate salt"; 1341 return -ENOMEM; 1342 } 1343 if (strlen(arg) != v->salt_size * 2 || 1344 hex2bin(v->salt, arg, v->salt_size)) { 1345 ti->error = "Invalid salt"; 1346 return -EINVAL; 1347 } 1348 } 1349 if (v->shash_tfm) { 1350 SHASH_DESC_ON_STACK(desc, v->shash_tfm); 1351 int r; 1352 1353 /* 1354 * Compute the pre-salted hash state that can be passed to 1355 * crypto_shash_import() for each block later. 1356 */ 1357 v->initial_hashstate = kmalloc( 1358 crypto_shash_statesize(v->shash_tfm), GFP_KERNEL); 1359 if (!v->initial_hashstate) { 1360 ti->error = "Cannot allocate initial hash state"; 1361 return -ENOMEM; 1362 } 1363 desc->tfm = v->shash_tfm; 1364 r = crypto_shash_init(desc) ?: 1365 crypto_shash_update(desc, v->salt, v->salt_size) ?: 1366 crypto_shash_export(desc, v->initial_hashstate); 1367 if (r) { 1368 ti->error = "Cannot set up initial hash state"; 1369 return r; 1370 } 1371 } 1372 return 0; 1373 } 1374 1375 /* 1376 * Target parameters: 1377 * <version> The current format is version 1. 1378 * Vsn 0 is compatible with original Chromium OS releases. 1379 * <data device> 1380 * <hash device> 1381 * <data block size> 1382 * <hash block size> 1383 * <the number of data blocks> 1384 * <hash start block> 1385 * <algorithm> 1386 * <digest> 1387 * <salt> Hex string or "-" if no salt. 1388 */ 1389 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1390 { 1391 struct dm_verity *v; 1392 struct dm_verity_sig_opts verify_args = {0}; 1393 struct dm_arg_set as; 1394 unsigned int num; 1395 unsigned long long num_ll; 1396 int r; 1397 int i; 1398 sector_t hash_position; 1399 char dummy; 1400 char *root_hash_digest_to_validate; 1401 1402 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1403 if (!v) { 1404 ti->error = "Cannot allocate verity structure"; 1405 return -ENOMEM; 1406 } 1407 ti->private = v; 1408 v->ti = ti; 1409 1410 r = verity_fec_ctr_alloc(v); 1411 if (r) 1412 goto bad; 1413 1414 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1415 ti->error = "Device must be readonly"; 1416 r = -EINVAL; 1417 goto bad; 1418 } 1419 1420 if (argc < 10) { 1421 ti->error = "Not enough arguments"; 1422 r = -EINVAL; 1423 goto bad; 1424 } 1425 1426 /* Parse optional parameters that modify primary args */ 1427 if (argc > 10) { 1428 as.argc = argc - 10; 1429 as.argv = argv + 10; 1430 r = verity_parse_opt_args(&as, v, &verify_args, true); 1431 if (r < 0) 1432 goto bad; 1433 } 1434 1435 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1436 num > 1) { 1437 ti->error = "Invalid version"; 1438 r = -EINVAL; 1439 goto bad; 1440 } 1441 v->version = num; 1442 1443 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1444 if (r) { 1445 ti->error = "Data device lookup failed"; 1446 goto bad; 1447 } 1448 1449 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1450 if (r) { 1451 ti->error = "Hash device lookup failed"; 1452 goto bad; 1453 } 1454 1455 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1456 !num || (num & (num - 1)) || 1457 num < bdev_logical_block_size(v->data_dev->bdev) || 1458 num > PAGE_SIZE) { 1459 ti->error = "Invalid data device block size"; 1460 r = -EINVAL; 1461 goto bad; 1462 } 1463 v->data_dev_block_bits = __ffs(num); 1464 1465 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1466 !num || (num & (num - 1)) || 1467 num < bdev_logical_block_size(v->hash_dev->bdev) || 1468 num > INT_MAX) { 1469 ti->error = "Invalid hash device block size"; 1470 r = -EINVAL; 1471 goto bad; 1472 } 1473 v->hash_dev_block_bits = __ffs(num); 1474 1475 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1476 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1477 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1478 ti->error = "Invalid data blocks"; 1479 r = -EINVAL; 1480 goto bad; 1481 } 1482 v->data_blocks = num_ll; 1483 1484 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1485 ti->error = "Data device is too small"; 1486 r = -EINVAL; 1487 goto bad; 1488 } 1489 1490 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1491 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1492 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1493 ti->error = "Invalid hash start"; 1494 r = -EINVAL; 1495 goto bad; 1496 } 1497 v->hash_start = num_ll; 1498 1499 r = verity_setup_hash_alg(v, argv[7]); 1500 if (r) 1501 goto bad; 1502 1503 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1504 if (!v->root_digest) { 1505 ti->error = "Cannot allocate root digest"; 1506 r = -ENOMEM; 1507 goto bad; 1508 } 1509 if (strlen(argv[8]) != v->digest_size * 2 || 1510 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1511 ti->error = "Invalid root digest"; 1512 r = -EINVAL; 1513 goto bad; 1514 } 1515 root_hash_digest_to_validate = argv[8]; 1516 1517 r = verity_setup_salt_and_hashstate(v, argv[9]); 1518 if (r) 1519 goto bad; 1520 1521 argv += 10; 1522 argc -= 10; 1523 1524 /* Optional parameters */ 1525 if (argc) { 1526 as.argc = argc; 1527 as.argv = argv; 1528 r = verity_parse_opt_args(&as, v, &verify_args, false); 1529 if (r < 0) 1530 goto bad; 1531 } 1532 1533 /* Root hash signature is a optional parameter*/ 1534 r = verity_verify_root_hash(root_hash_digest_to_validate, 1535 strlen(root_hash_digest_to_validate), 1536 verify_args.sig, 1537 verify_args.sig_size); 1538 if (r < 0) { 1539 ti->error = "Root hash verification failed"; 1540 goto bad; 1541 } 1542 1543 r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); 1544 if (r < 0) { 1545 ti->error = "Cannot allocate root digest signature"; 1546 goto bad; 1547 } 1548 1549 v->hash_per_block_bits = 1550 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1551 1552 v->levels = 0; 1553 if (v->data_blocks) 1554 while (v->hash_per_block_bits * v->levels < 64 && 1555 (unsigned long long)(v->data_blocks - 1) >> 1556 (v->hash_per_block_bits * v->levels)) 1557 v->levels++; 1558 1559 if (v->levels > DM_VERITY_MAX_LEVELS) { 1560 ti->error = "Too many tree levels"; 1561 r = -E2BIG; 1562 goto bad; 1563 } 1564 1565 hash_position = v->hash_start; 1566 for (i = v->levels - 1; i >= 0; i--) { 1567 sector_t s; 1568 1569 v->hash_level_block[i] = hash_position; 1570 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1571 >> ((i + 1) * v->hash_per_block_bits); 1572 if (hash_position + s < hash_position) { 1573 ti->error = "Hash device offset overflow"; 1574 r = -E2BIG; 1575 goto bad; 1576 } 1577 hash_position += s; 1578 } 1579 v->hash_blocks = hash_position; 1580 1581 r = mempool_init_page_pool(&v->recheck_pool, 1, 0); 1582 if (unlikely(r)) { 1583 ti->error = "Cannot allocate mempool"; 1584 goto bad; 1585 } 1586 1587 v->io = dm_io_client_create(); 1588 if (IS_ERR(v->io)) { 1589 r = PTR_ERR(v->io); 1590 v->io = NULL; 1591 ti->error = "Cannot allocate dm io"; 1592 goto bad; 1593 } 1594 1595 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1596 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1597 dm_bufio_alloc_callback, NULL, 1598 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1599 if (IS_ERR(v->bufio)) { 1600 ti->error = "Cannot initialize dm-bufio"; 1601 r = PTR_ERR(v->bufio); 1602 v->bufio = NULL; 1603 goto bad; 1604 } 1605 1606 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1607 ti->error = "Hash device is too small"; 1608 r = -E2BIG; 1609 goto bad; 1610 } 1611 1612 /* 1613 * Using WQ_HIGHPRI improves throughput and completion latency by 1614 * reducing wait times when reading from a dm-verity device. 1615 * 1616 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1617 * allows verify_wq to preempt softirq since verification in BH workqueue 1618 * will fall-back to using it for error handling (or if the bufio cache 1619 * doesn't have required hashes). 1620 */ 1621 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1622 if (!v->verify_wq) { 1623 ti->error = "Cannot allocate workqueue"; 1624 r = -ENOMEM; 1625 goto bad; 1626 } 1627 1628 ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize; 1629 1630 r = verity_fec_ctr(v); 1631 if (r) 1632 goto bad; 1633 1634 ti->per_io_data_size = roundup(ti->per_io_data_size, 1635 __alignof__(struct dm_verity_io)); 1636 1637 verity_verify_sig_opts_cleanup(&verify_args); 1638 1639 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1640 1641 return 0; 1642 1643 bad: 1644 1645 verity_verify_sig_opts_cleanup(&verify_args); 1646 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1647 verity_dtr(ti); 1648 1649 return r; 1650 } 1651 1652 /* 1653 * Get the verity mode (error behavior) of a verity target. 1654 * 1655 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1656 * target. 1657 */ 1658 int dm_verity_get_mode(struct dm_target *ti) 1659 { 1660 struct dm_verity *v = ti->private; 1661 1662 if (!dm_is_verity_target(ti)) 1663 return -EINVAL; 1664 1665 return v->mode; 1666 } 1667 1668 /* 1669 * Get the root digest of a verity target. 1670 * 1671 * Returns a copy of the root digest, the caller is responsible for 1672 * freeing the memory of the digest. 1673 */ 1674 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1675 { 1676 struct dm_verity *v = ti->private; 1677 1678 if (!dm_is_verity_target(ti)) 1679 return -EINVAL; 1680 1681 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1682 if (*root_digest == NULL) 1683 return -ENOMEM; 1684 1685 *digest_size = v->digest_size; 1686 1687 return 0; 1688 } 1689 1690 #ifdef CONFIG_SECURITY 1691 1692 #ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG 1693 1694 static int verity_security_set_signature(struct block_device *bdev, 1695 struct dm_verity *v) 1696 { 1697 /* 1698 * if the dm-verity target is unsigned, v->root_digest_sig will 1699 * be NULL, and the hook call is still required to let LSMs mark 1700 * the device as unsigned. This information is crucial for LSMs to 1701 * block operations such as execution on unsigned files 1702 */ 1703 return security_bdev_setintegrity(bdev, 1704 LSM_INT_DMVERITY_SIG_VALID, 1705 v->root_digest_sig, 1706 v->sig_size); 1707 } 1708 1709 #else 1710 1711 static inline int verity_security_set_signature(struct block_device *bdev, 1712 struct dm_verity *v) 1713 { 1714 return 0; 1715 } 1716 1717 #endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */ 1718 1719 /* 1720 * Expose verity target's root hash and signature data to LSMs before resume. 1721 * 1722 * Returns 0 on success, or -ENOMEM if the system is out of memory. 1723 */ 1724 static int verity_preresume(struct dm_target *ti) 1725 { 1726 struct block_device *bdev; 1727 struct dm_verity_digest root_digest; 1728 struct dm_verity *v; 1729 int r; 1730 1731 v = ti->private; 1732 bdev = dm_disk(dm_table_get_md(ti->table))->part0; 1733 root_digest.digest = v->root_digest; 1734 root_digest.digest_len = v->digest_size; 1735 if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) 1736 root_digest.alg = crypto_ahash_alg_name(v->ahash_tfm); 1737 else 1738 root_digest.alg = crypto_shash_alg_name(v->shash_tfm); 1739 1740 r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest, 1741 sizeof(root_digest)); 1742 if (r) 1743 return r; 1744 1745 r = verity_security_set_signature(bdev, v); 1746 if (r) 1747 goto bad; 1748 1749 return 0; 1750 1751 bad: 1752 1753 security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0); 1754 1755 return r; 1756 } 1757 1758 #endif /* CONFIG_SECURITY */ 1759 1760 static struct target_type verity_target = { 1761 .name = "verity", 1762 /* Note: the LSMs depend on the singleton and immutable features */ 1763 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, 1764 .version = {1, 10, 0}, 1765 .module = THIS_MODULE, 1766 .ctr = verity_ctr, 1767 .dtr = verity_dtr, 1768 .map = verity_map, 1769 .status = verity_status, 1770 .prepare_ioctl = verity_prepare_ioctl, 1771 .iterate_devices = verity_iterate_devices, 1772 .io_hints = verity_io_hints, 1773 #ifdef CONFIG_SECURITY 1774 .preresume = verity_preresume, 1775 #endif /* CONFIG_SECURITY */ 1776 }; 1777 module_dm(verity); 1778 1779 /* 1780 * Check whether a DM target is a verity target. 1781 */ 1782 bool dm_is_verity_target(struct dm_target *ti) 1783 { 1784 return ti->type == &verity_target; 1785 } 1786 1787 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1788 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1789 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1790 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1791 MODULE_LICENSE("GPL"); 1792