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/string.h> 23 #include <linux/jump_label.h> 24 #include <linux/security.h> 25 26 #define DM_MSG_PREFIX "verity" 27 28 #define DM_VERITY_ENV_LENGTH 42 29 #define DM_VERITY_ENV_VAR_NAME "DM_VERITY_ERR_BLOCK_NR" 30 31 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 32 #define DM_VERITY_USE_BH_DEFAULT_BYTES 8192 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 unsigned int dm_verity_use_bh_bytes[4] = { 53 DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_NONE 54 DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_RT 55 DM_VERITY_USE_BH_DEFAULT_BYTES, // IOPRIO_CLASS_BE 56 0 // IOPRIO_CLASS_IDLE 57 }; 58 59 module_param_array_named(use_bh_bytes, dm_verity_use_bh_bytes, uint, NULL, 0644); 60 61 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled); 62 63 struct dm_verity_prefetch_work { 64 struct work_struct work; 65 struct dm_verity *v; 66 unsigned short ioprio; 67 sector_t block; 68 unsigned int n_blocks; 69 }; 70 71 /* 72 * Auxiliary structure appended to each dm-bufio buffer. If the value 73 * hash_verified is nonzero, hash of the block has been verified. 74 * 75 * The variable hash_verified is set to 0 when allocating the buffer, then 76 * it can be changed to 1 and it is never reset to 0 again. 77 * 78 * There is no lock around this value, a race condition can at worst cause 79 * that multiple processes verify the hash of the same buffer simultaneously 80 * and write 1 to hash_verified simultaneously. 81 * This condition is harmless, so we don't need locking. 82 */ 83 struct buffer_aux { 84 int hash_verified; 85 }; 86 87 /* 88 * Initialize struct buffer_aux for a freshly created buffer. 89 */ 90 static void dm_bufio_alloc_callback(struct dm_buffer *buf) 91 { 92 struct buffer_aux *aux = dm_bufio_get_aux_data(buf); 93 94 aux->hash_verified = 0; 95 } 96 97 /* 98 * Translate input sector number to the sector number on the target device. 99 */ 100 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) 101 { 102 return dm_target_offset(v->ti, bi_sector); 103 } 104 105 /* 106 * Return hash position of a specified block at a specified tree level 107 * (0 is the lowest level). 108 * The lowest "hash_per_block_bits"-bits of the result denote hash position 109 * inside a hash block. The remaining bits denote location of the hash block. 110 */ 111 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, 112 int level) 113 { 114 return block >> (level * v->hash_per_block_bits); 115 } 116 117 int verity_hash(struct dm_verity *v, struct dm_verity_io *io, 118 const u8 *data, size_t len, u8 *digest) 119 { 120 struct shash_desc *desc = &io->hash_desc; 121 int r; 122 123 desc->tfm = v->shash_tfm; 124 if (unlikely(v->initial_hashstate == NULL)) { 125 /* Version 0: salt at end */ 126 r = crypto_shash_init(desc) ?: 127 crypto_shash_update(desc, data, len) ?: 128 crypto_shash_update(desc, v->salt, v->salt_size) ?: 129 crypto_shash_final(desc, digest); 130 } else { 131 /* Version 1: salt at beginning */ 132 r = crypto_shash_import(desc, v->initial_hashstate) ?: 133 crypto_shash_finup(desc, data, len, digest); 134 } 135 if (unlikely(r)) 136 DMERR("Error hashing block: %d", r); 137 return r; 138 } 139 140 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, 141 sector_t *hash_block, unsigned int *offset) 142 { 143 sector_t position = verity_position_at_level(v, block, level); 144 unsigned int idx; 145 146 *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); 147 148 if (!offset) 149 return; 150 151 idx = position & ((1 << v->hash_per_block_bits) - 1); 152 if (!v->version) 153 *offset = idx * v->digest_size; 154 else 155 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits); 156 } 157 158 /* 159 * Handle verification errors. 160 */ 161 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 162 unsigned long long block) 163 { 164 char verity_env[DM_VERITY_ENV_LENGTH]; 165 char *envp[] = { verity_env, NULL }; 166 const char *type_str = ""; 167 struct mapped_device *md = dm_table_get_md(v->ti->table); 168 169 /* Corruption should be visible in device status in all modes */ 170 v->hash_failed = true; 171 172 if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS) 173 goto out; 174 175 v->corrupted_errs++; 176 177 switch (type) { 178 case DM_VERITY_BLOCK_TYPE_DATA: 179 type_str = "data"; 180 break; 181 case DM_VERITY_BLOCK_TYPE_METADATA: 182 type_str = "metadata"; 183 break; 184 default: 185 BUG(); 186 } 187 188 DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name, 189 type_str, block); 190 191 if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) { 192 DMERR("%s: reached maximum errors", v->data_dev->name); 193 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0); 194 } 195 196 snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu", 197 DM_VERITY_ENV_VAR_NAME, type, block); 198 199 kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp); 200 201 out: 202 if (v->mode == DM_VERITY_MODE_LOGGING) 203 return 0; 204 205 if (v->mode == DM_VERITY_MODE_RESTART) 206 kernel_restart("dm-verity device corrupted"); 207 208 if (v->mode == DM_VERITY_MODE_PANIC) 209 panic("dm-verity device corrupted"); 210 211 return 1; 212 } 213 214 /* 215 * Verify hash of a metadata block pertaining to the specified data block 216 * ("block" argument) at a specified level ("level" argument). 217 * 218 * On successful return, verity_io_want_digest(v, io) contains the hash value 219 * for a lower tree level or for the data block (if we're at the lowest level). 220 * 221 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned. 222 * If "skip_unverified" is false, unverified buffer is hashed and verified 223 * against current value of verity_io_want_digest(v, io). 224 */ 225 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 226 sector_t block, int level, bool skip_unverified, 227 u8 *want_digest) 228 { 229 struct dm_buffer *buf; 230 struct buffer_aux *aux; 231 u8 *data; 232 int r; 233 sector_t hash_block; 234 unsigned int offset; 235 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 236 237 verity_hash_at_level(v, block, level, &hash_block, &offset); 238 239 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 240 data = dm_bufio_get(v->bufio, hash_block, &buf); 241 if (IS_ERR_OR_NULL(data)) { 242 /* 243 * In tasklet and the hash was not in the bufio cache. 244 * Return early and resume execution from a work-queue 245 * to read the hash from disk. 246 */ 247 return -EAGAIN; 248 } 249 } else { 250 data = dm_bufio_read_with_ioprio(v->bufio, hash_block, 251 &buf, bio->bi_ioprio); 252 } 253 254 if (IS_ERR(data)) { 255 if (skip_unverified) 256 return 1; 257 r = PTR_ERR(data); 258 data = dm_bufio_new(v->bufio, hash_block, &buf); 259 if (IS_ERR(data)) 260 return r; 261 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 262 hash_block, data) == 0) { 263 aux = dm_bufio_get_aux_data(buf); 264 aux->hash_verified = 1; 265 goto release_ok; 266 } else { 267 dm_bufio_release(buf); 268 dm_bufio_forget(v->bufio, hash_block); 269 return r; 270 } 271 } 272 273 aux = dm_bufio_get_aux_data(buf); 274 275 if (!aux->hash_verified) { 276 if (skip_unverified) { 277 r = 1; 278 goto release_ret_r; 279 } 280 281 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits, 282 verity_io_real_digest(v, io)); 283 if (unlikely(r < 0)) 284 goto release_ret_r; 285 286 if (likely(memcmp(verity_io_real_digest(v, io), want_digest, 287 v->digest_size) == 0)) 288 aux->hash_verified = 1; 289 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 290 /* 291 * Error handling code (FEC included) cannot be run in a 292 * tasklet since it may sleep, so fallback to work-queue. 293 */ 294 r = -EAGAIN; 295 goto release_ret_r; 296 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA, 297 hash_block, data) == 0) 298 aux->hash_verified = 1; 299 else if (verity_handle_err(v, 300 DM_VERITY_BLOCK_TYPE_METADATA, 301 hash_block)) { 302 struct bio *bio; 303 io->had_mismatch = true; 304 bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 305 dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio, 306 block, 0); 307 r = -EIO; 308 goto release_ret_r; 309 } 310 } 311 312 release_ok: 313 data += offset; 314 memcpy(want_digest, data, v->digest_size); 315 r = 0; 316 317 release_ret_r: 318 dm_bufio_release(buf); 319 return r; 320 } 321 322 /* 323 * Find a hash for a given block, write it to digest and verify the integrity 324 * of the hash tree if necessary. 325 */ 326 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io, 327 sector_t block, u8 *digest, bool *is_zero) 328 { 329 int r = 0, i; 330 331 if (likely(v->levels)) { 332 /* 333 * First, we try to get the requested hash for 334 * the current block. If the hash block itself is 335 * verified, zero is returned. If it isn't, this 336 * function returns 1 and we fall back to whole 337 * chain verification. 338 */ 339 r = verity_verify_level(v, io, block, 0, true, digest); 340 if (likely(r <= 0)) 341 goto out; 342 } 343 344 memcpy(digest, v->root_digest, v->digest_size); 345 346 for (i = v->levels - 1; i >= 0; i--) { 347 r = verity_verify_level(v, io, block, i, false, digest); 348 if (unlikely(r)) 349 goto out; 350 } 351 out: 352 if (!r && v->zero_digest) 353 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size); 354 else 355 *is_zero = false; 356 357 return r; 358 } 359 360 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io, 361 sector_t cur_block, u8 *dest) 362 { 363 struct page *page; 364 void *buffer; 365 int r; 366 struct dm_io_request io_req; 367 struct dm_io_region io_loc; 368 369 page = mempool_alloc(&v->recheck_pool, GFP_NOIO); 370 buffer = page_to_virt(page); 371 372 io_req.bi_opf = REQ_OP_READ; 373 io_req.mem.type = DM_IO_KMEM; 374 io_req.mem.ptr.addr = buffer; 375 io_req.notify.fn = NULL; 376 io_req.client = v->io; 377 io_loc.bdev = v->data_dev->bdev; 378 io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT); 379 io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT); 380 r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT); 381 if (unlikely(r)) 382 goto free_ret; 383 384 r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits, 385 verity_io_real_digest(v, io)); 386 if (unlikely(r)) 387 goto free_ret; 388 389 if (memcmp(verity_io_real_digest(v, io), 390 verity_io_want_digest(v, io), v->digest_size)) { 391 r = -EIO; 392 goto free_ret; 393 } 394 395 memcpy(dest, buffer, 1 << v->data_dev_block_bits); 396 r = 0; 397 free_ret: 398 mempool_free(page, &v->recheck_pool); 399 400 return r; 401 } 402 403 static int verity_handle_data_hash_mismatch(struct dm_verity *v, 404 struct dm_verity_io *io, 405 struct bio *bio, sector_t blkno, 406 u8 *data) 407 { 408 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 409 /* 410 * Error handling code (FEC included) cannot be run in the 411 * BH workqueue, so fallback to a standard workqueue. 412 */ 413 return -EAGAIN; 414 } 415 if (verity_recheck(v, io, blkno, data) == 0) { 416 if (v->validated_blocks) 417 set_bit(blkno, v->validated_blocks); 418 return 0; 419 } 420 #if defined(CONFIG_DM_VERITY_FEC) 421 if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno, 422 data) == 0) 423 return 0; 424 #endif 425 if (bio->bi_status) 426 return -EIO; /* Error correction failed; Just return error */ 427 428 if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) { 429 io->had_mismatch = true; 430 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0); 431 return -EIO; 432 } 433 return 0; 434 } 435 436 /* 437 * Verify one "dm_verity_io" structure. 438 */ 439 static int verity_verify_io(struct dm_verity_io *io) 440 { 441 struct dm_verity *v = io->v; 442 const unsigned int block_size = 1 << v->data_dev_block_bits; 443 struct bvec_iter iter_copy; 444 struct bvec_iter *iter; 445 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 446 unsigned int b; 447 448 if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) { 449 /* 450 * Copy the iterator in case we need to restart 451 * verification in a work-queue. 452 */ 453 iter_copy = io->iter; 454 iter = &iter_copy; 455 } else 456 iter = &io->iter; 457 458 for (b = 0; b < io->n_blocks; 459 b++, bio_advance_iter(bio, iter, block_size)) { 460 int r; 461 sector_t cur_block = io->block + b; 462 bool is_zero; 463 struct bio_vec bv; 464 void *data; 465 466 if (v->validated_blocks && bio->bi_status == BLK_STS_OK && 467 likely(test_bit(cur_block, v->validated_blocks))) 468 continue; 469 470 r = verity_hash_for_block(v, io, cur_block, 471 verity_io_want_digest(v, io), 472 &is_zero); 473 if (unlikely(r < 0)) 474 return r; 475 476 bv = bio_iter_iovec(bio, *iter); 477 if (unlikely(bv.bv_len < block_size)) { 478 /* 479 * Data block spans pages. This should not happen, 480 * since dm-verity sets dma_alignment to the data block 481 * size minus 1, and dm-verity also doesn't allow the 482 * data block size to be greater than PAGE_SIZE. 483 */ 484 DMERR_LIMIT("unaligned io (data block spans pages)"); 485 return -EIO; 486 } 487 488 data = bvec_kmap_local(&bv); 489 490 if (is_zero) { 491 /* 492 * If we expect a zero block, don't validate, just 493 * return zeros. 494 */ 495 memset(data, 0, block_size); 496 kunmap_local(data); 497 continue; 498 } 499 500 r = verity_hash(v, io, data, block_size, 501 verity_io_real_digest(v, io)); 502 if (unlikely(r < 0)) { 503 kunmap_local(data); 504 return r; 505 } 506 507 if (likely(memcmp(verity_io_real_digest(v, io), 508 verity_io_want_digest(v, io), v->digest_size) == 0)) { 509 if (v->validated_blocks) 510 set_bit(cur_block, v->validated_blocks); 511 kunmap_local(data); 512 continue; 513 } 514 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block, 515 data); 516 kunmap_local(data); 517 if (unlikely(r)) 518 return r; 519 } 520 521 return 0; 522 } 523 524 /* 525 * Skip verity work in response to I/O error when system is shutting down. 526 */ 527 static inline bool verity_is_system_shutting_down(void) 528 { 529 return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF 530 || system_state == SYSTEM_RESTART; 531 } 532 533 static void restart_io_error(struct work_struct *w) 534 { 535 kernel_restart("dm-verity device has I/O error"); 536 } 537 538 /* 539 * End one "io" structure with a given error. 540 */ 541 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status) 542 { 543 struct dm_verity *v = io->v; 544 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size); 545 546 bio->bi_end_io = io->orig_bi_end_io; 547 bio->bi_status = status; 548 549 if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh) 550 verity_fec_finish_io(io); 551 552 if (unlikely(status != BLK_STS_OK) && 553 unlikely(!(bio->bi_opf & REQ_RAHEAD)) && 554 !io->had_mismatch && 555 !verity_is_system_shutting_down()) { 556 if (v->error_mode == DM_VERITY_MODE_PANIC) { 557 panic("dm-verity device has I/O error"); 558 } 559 if (v->error_mode == DM_VERITY_MODE_RESTART) { 560 static DECLARE_WORK(restart_work, restart_io_error); 561 queue_work(v->verify_wq, &restart_work); 562 /* 563 * We deliberately don't call bio_endio here, because 564 * the machine will be restarted anyway. 565 */ 566 return; 567 } 568 } 569 570 bio_endio(bio); 571 } 572 573 static void verity_work(struct work_struct *w) 574 { 575 struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); 576 577 io->in_bh = false; 578 579 verity_finish_io(io, errno_to_blk_status(verity_verify_io(io))); 580 } 581 582 static void verity_bh_work(struct work_struct *w) 583 { 584 struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work); 585 int err; 586 587 io->in_bh = true; 588 err = verity_verify_io(io); 589 if (err == -EAGAIN || err == -ENOMEM) { 590 /* fallback to retrying with work-queue */ 591 INIT_WORK(&io->work, verity_work); 592 queue_work(io->v->verify_wq, &io->work); 593 return; 594 } 595 596 verity_finish_io(io, errno_to_blk_status(err)); 597 } 598 599 static inline bool verity_use_bh(unsigned int bytes, unsigned short ioprio) 600 { 601 return ioprio <= IOPRIO_CLASS_IDLE && 602 bytes <= READ_ONCE(dm_verity_use_bh_bytes[ioprio]) && 603 !need_resched(); 604 } 605 606 static void verity_end_io(struct bio *bio) 607 { 608 struct dm_verity_io *io = bio->bi_private; 609 unsigned short ioprio = IOPRIO_PRIO_CLASS(bio->bi_ioprio); 610 unsigned int bytes = io->n_blocks << io->v->data_dev_block_bits; 611 612 if (bio->bi_status && 613 (!verity_fec_is_enabled(io->v) || 614 verity_is_system_shutting_down() || 615 (bio->bi_opf & REQ_RAHEAD))) { 616 verity_finish_io(io, bio->bi_status); 617 return; 618 } 619 620 if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq && 621 verity_use_bh(bytes, ioprio)) { 622 if (in_hardirq() || irqs_disabled()) { 623 INIT_WORK(&io->bh_work, verity_bh_work); 624 queue_work(system_bh_wq, &io->bh_work); 625 } else { 626 verity_bh_work(&io->bh_work); 627 } 628 } else { 629 INIT_WORK(&io->work, verity_work); 630 queue_work(io->v->verify_wq, &io->work); 631 } 632 } 633 634 /* 635 * Prefetch buffers for the specified io. 636 * The root buffer is not prefetched, it is assumed that it will be cached 637 * all the time. 638 */ 639 static void verity_prefetch_io(struct work_struct *work) 640 { 641 struct dm_verity_prefetch_work *pw = 642 container_of(work, struct dm_verity_prefetch_work, work); 643 struct dm_verity *v = pw->v; 644 int i; 645 646 for (i = v->levels - 2; i >= 0; i--) { 647 sector_t hash_block_start; 648 sector_t hash_block_end; 649 650 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL); 651 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL); 652 653 if (!i) { 654 unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster); 655 656 cluster >>= v->data_dev_block_bits; 657 if (unlikely(!cluster)) 658 goto no_prefetch_cluster; 659 660 if (unlikely(cluster & (cluster - 1))) 661 cluster = 1 << __fls(cluster); 662 663 hash_block_start &= ~(sector_t)(cluster - 1); 664 hash_block_end |= cluster - 1; 665 if (unlikely(hash_block_end >= v->hash_blocks)) 666 hash_block_end = v->hash_blocks - 1; 667 } 668 no_prefetch_cluster: 669 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start, 670 hash_block_end - hash_block_start + 1, 671 pw->ioprio); 672 } 673 674 kfree(pw); 675 } 676 677 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io, 678 unsigned short ioprio) 679 { 680 sector_t block = io->block; 681 unsigned int n_blocks = io->n_blocks; 682 struct dm_verity_prefetch_work *pw; 683 684 if (v->validated_blocks) { 685 while (n_blocks && test_bit(block, v->validated_blocks)) { 686 block++; 687 n_blocks--; 688 } 689 while (n_blocks && test_bit(block + n_blocks - 1, 690 v->validated_blocks)) 691 n_blocks--; 692 if (!n_blocks) 693 return; 694 } 695 696 pw = kmalloc(sizeof(struct dm_verity_prefetch_work), 697 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); 698 699 if (!pw) 700 return; 701 702 INIT_WORK(&pw->work, verity_prefetch_io); 703 pw->v = v; 704 pw->block = block; 705 pw->n_blocks = n_blocks; 706 pw->ioprio = ioprio; 707 queue_work(v->verify_wq, &pw->work); 708 } 709 710 /* 711 * Bio map function. It allocates dm_verity_io structure and bio vector and 712 * fills them. Then it issues prefetches and the I/O. 713 */ 714 static int verity_map(struct dm_target *ti, struct bio *bio) 715 { 716 struct dm_verity *v = ti->private; 717 struct dm_verity_io *io; 718 719 bio_set_dev(bio, v->data_dev->bdev); 720 bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector); 721 722 if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) & 723 ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { 724 DMERR_LIMIT("unaligned io"); 725 return DM_MAPIO_KILL; 726 } 727 728 if (bio_end_sector(bio) >> 729 (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { 730 DMERR_LIMIT("io out of range"); 731 return DM_MAPIO_KILL; 732 } 733 734 if (bio_data_dir(bio) == WRITE) 735 return DM_MAPIO_KILL; 736 737 io = dm_per_bio_data(bio, ti->per_io_data_size); 738 io->v = v; 739 io->orig_bi_end_io = bio->bi_end_io; 740 io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); 741 io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits; 742 io->had_mismatch = false; 743 744 bio->bi_end_io = verity_end_io; 745 bio->bi_private = io; 746 io->iter = bio->bi_iter; 747 748 verity_fec_init_io(io); 749 750 verity_submit_prefetch(v, io, bio->bi_ioprio); 751 752 submit_bio_noacct(bio); 753 754 return DM_MAPIO_SUBMITTED; 755 } 756 757 static void verity_postsuspend(struct dm_target *ti) 758 { 759 struct dm_verity *v = ti->private; 760 flush_workqueue(v->verify_wq); 761 dm_bufio_client_reset(v->bufio); 762 } 763 764 /* 765 * Status: V (valid) or C (corruption found) 766 */ 767 static void verity_status(struct dm_target *ti, status_type_t type, 768 unsigned int status_flags, char *result, unsigned int maxlen) 769 { 770 struct dm_verity *v = ti->private; 771 unsigned int args = 0; 772 unsigned int sz = 0; 773 unsigned int x; 774 775 switch (type) { 776 case STATUSTYPE_INFO: 777 DMEMIT("%c", v->hash_failed ? 'C' : 'V'); 778 break; 779 case STATUSTYPE_TABLE: 780 DMEMIT("%u %s %s %u %u %llu %llu %s ", 781 v->version, 782 v->data_dev->name, 783 v->hash_dev->name, 784 1 << v->data_dev_block_bits, 785 1 << v->hash_dev_block_bits, 786 (unsigned long long)v->data_blocks, 787 (unsigned long long)v->hash_start, 788 v->alg_name 789 ); 790 for (x = 0; x < v->digest_size; x++) 791 DMEMIT("%02x", v->root_digest[x]); 792 DMEMIT(" "); 793 if (!v->salt_size) 794 DMEMIT("-"); 795 else 796 for (x = 0; x < v->salt_size; x++) 797 DMEMIT("%02x", v->salt[x]); 798 if (v->mode != DM_VERITY_MODE_EIO) 799 args++; 800 if (v->error_mode != DM_VERITY_MODE_EIO) 801 args++; 802 if (verity_fec_is_enabled(v)) 803 args += DM_VERITY_OPTS_FEC; 804 if (v->zero_digest) 805 args++; 806 if (v->validated_blocks) 807 args++; 808 if (v->use_bh_wq) 809 args++; 810 if (v->signature_key_desc) 811 args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS; 812 if (!args) 813 return; 814 DMEMIT(" %u", args); 815 if (v->mode != DM_VERITY_MODE_EIO) { 816 DMEMIT(" "); 817 switch (v->mode) { 818 case DM_VERITY_MODE_LOGGING: 819 DMEMIT(DM_VERITY_OPT_LOGGING); 820 break; 821 case DM_VERITY_MODE_RESTART: 822 DMEMIT(DM_VERITY_OPT_RESTART); 823 break; 824 case DM_VERITY_MODE_PANIC: 825 DMEMIT(DM_VERITY_OPT_PANIC); 826 break; 827 default: 828 BUG(); 829 } 830 } 831 if (v->error_mode != DM_VERITY_MODE_EIO) { 832 DMEMIT(" "); 833 switch (v->error_mode) { 834 case DM_VERITY_MODE_RESTART: 835 DMEMIT(DM_VERITY_OPT_ERROR_RESTART); 836 break; 837 case DM_VERITY_MODE_PANIC: 838 DMEMIT(DM_VERITY_OPT_ERROR_PANIC); 839 break; 840 default: 841 BUG(); 842 } 843 } 844 if (v->zero_digest) 845 DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES); 846 if (v->validated_blocks) 847 DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE); 848 if (v->use_bh_wq) 849 DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY); 850 sz = verity_fec_status_table(v, sz, result, maxlen); 851 if (v->signature_key_desc) 852 DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY 853 " %s", v->signature_key_desc); 854 break; 855 856 case STATUSTYPE_IMA: 857 DMEMIT_TARGET_NAME_VERSION(ti->type); 858 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V'); 859 DMEMIT(",verity_version=%u", v->version); 860 DMEMIT(",data_device_name=%s", v->data_dev->name); 861 DMEMIT(",hash_device_name=%s", v->hash_dev->name); 862 DMEMIT(",verity_algorithm=%s", v->alg_name); 863 864 DMEMIT(",root_digest="); 865 for (x = 0; x < v->digest_size; x++) 866 DMEMIT("%02x", v->root_digest[x]); 867 868 DMEMIT(",salt="); 869 if (!v->salt_size) 870 DMEMIT("-"); 871 else 872 for (x = 0; x < v->salt_size; x++) 873 DMEMIT("%02x", v->salt[x]); 874 875 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n'); 876 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n'); 877 if (v->signature_key_desc) 878 DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc); 879 880 if (v->mode != DM_VERITY_MODE_EIO) { 881 DMEMIT(",verity_mode="); 882 switch (v->mode) { 883 case DM_VERITY_MODE_LOGGING: 884 DMEMIT(DM_VERITY_OPT_LOGGING); 885 break; 886 case DM_VERITY_MODE_RESTART: 887 DMEMIT(DM_VERITY_OPT_RESTART); 888 break; 889 case DM_VERITY_MODE_PANIC: 890 DMEMIT(DM_VERITY_OPT_PANIC); 891 break; 892 default: 893 DMEMIT("invalid"); 894 } 895 } 896 if (v->error_mode != DM_VERITY_MODE_EIO) { 897 DMEMIT(",verity_error_mode="); 898 switch (v->error_mode) { 899 case DM_VERITY_MODE_RESTART: 900 DMEMIT(DM_VERITY_OPT_ERROR_RESTART); 901 break; 902 case DM_VERITY_MODE_PANIC: 903 DMEMIT(DM_VERITY_OPT_ERROR_PANIC); 904 break; 905 default: 906 DMEMIT("invalid"); 907 } 908 } 909 DMEMIT(";"); 910 break; 911 } 912 } 913 914 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev, 915 unsigned int cmd, unsigned long arg, 916 bool *forward) 917 { 918 struct dm_verity *v = ti->private; 919 920 *bdev = v->data_dev->bdev; 921 922 if (ti->len != bdev_nr_sectors(v->data_dev->bdev)) 923 return 1; 924 return 0; 925 } 926 927 static int verity_iterate_devices(struct dm_target *ti, 928 iterate_devices_callout_fn fn, void *data) 929 { 930 struct dm_verity *v = ti->private; 931 932 return fn(ti, v->data_dev, 0, ti->len, data); 933 } 934 935 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits) 936 { 937 struct dm_verity *v = ti->private; 938 939 if (limits->logical_block_size < 1 << v->data_dev_block_bits) 940 limits->logical_block_size = 1 << v->data_dev_block_bits; 941 942 if (limits->physical_block_size < 1 << v->data_dev_block_bits) 943 limits->physical_block_size = 1 << v->data_dev_block_bits; 944 945 limits->io_min = limits->logical_block_size; 946 947 /* 948 * Similar to what dm-crypt does, opt dm-verity out of support for 949 * direct I/O that is aligned to less than the traditional direct I/O 950 * alignment requirement of logical_block_size. This prevents dm-verity 951 * data blocks from crossing pages, eliminating various edge cases. 952 */ 953 limits->dma_alignment = limits->logical_block_size - 1; 954 } 955 956 #ifdef CONFIG_SECURITY 957 958 static int verity_init_sig(struct dm_verity *v, const void *sig, 959 size_t sig_size) 960 { 961 v->sig_size = sig_size; 962 963 if (sig) { 964 v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL); 965 if (!v->root_digest_sig) 966 return -ENOMEM; 967 } 968 969 return 0; 970 } 971 972 static void verity_free_sig(struct dm_verity *v) 973 { 974 kfree(v->root_digest_sig); 975 } 976 977 #else 978 979 static inline int verity_init_sig(struct dm_verity *v, const void *sig, 980 size_t sig_size) 981 { 982 return 0; 983 } 984 985 static inline void verity_free_sig(struct dm_verity *v) 986 { 987 } 988 989 #endif /* CONFIG_SECURITY */ 990 991 static void verity_dtr(struct dm_target *ti) 992 { 993 struct dm_verity *v = ti->private; 994 995 if (v->verify_wq) 996 destroy_workqueue(v->verify_wq); 997 998 mempool_exit(&v->recheck_pool); 999 if (v->io) 1000 dm_io_client_destroy(v->io); 1001 1002 if (v->bufio) 1003 dm_bufio_client_destroy(v->bufio); 1004 1005 kvfree(v->validated_blocks); 1006 kfree(v->salt); 1007 kfree(v->initial_hashstate); 1008 kfree(v->root_digest); 1009 kfree(v->zero_digest); 1010 verity_free_sig(v); 1011 1012 crypto_free_shash(v->shash_tfm); 1013 1014 kfree(v->alg_name); 1015 1016 if (v->hash_dev) 1017 dm_put_device(ti, v->hash_dev); 1018 1019 if (v->data_dev) 1020 dm_put_device(ti, v->data_dev); 1021 1022 verity_fec_dtr(v); 1023 1024 kfree(v->signature_key_desc); 1025 1026 if (v->use_bh_wq) 1027 static_branch_dec(&use_bh_wq_enabled); 1028 1029 kfree(v); 1030 1031 dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1); 1032 } 1033 1034 static int verity_alloc_most_once(struct dm_verity *v) 1035 { 1036 struct dm_target *ti = v->ti; 1037 1038 if (v->validated_blocks) 1039 return 0; 1040 1041 /* the bitset can only handle INT_MAX blocks */ 1042 if (v->data_blocks > INT_MAX) { 1043 ti->error = "device too large to use check_at_most_once"; 1044 return -E2BIG; 1045 } 1046 1047 v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks), 1048 sizeof(unsigned long), 1049 GFP_KERNEL); 1050 if (!v->validated_blocks) { 1051 ti->error = "failed to allocate bitset for check_at_most_once"; 1052 return -ENOMEM; 1053 } 1054 1055 return 0; 1056 } 1057 1058 static int verity_alloc_zero_digest(struct dm_verity *v) 1059 { 1060 int r = -ENOMEM; 1061 struct dm_verity_io *io; 1062 u8 *zero_data; 1063 1064 if (v->zero_digest) 1065 return 0; 1066 1067 v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL); 1068 1069 if (!v->zero_digest) 1070 return r; 1071 1072 io = kmalloc(sizeof(*io) + crypto_shash_descsize(v->shash_tfm), 1073 GFP_KERNEL); 1074 1075 if (!io) 1076 return r; /* verity_dtr will free zero_digest */ 1077 1078 zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL); 1079 1080 if (!zero_data) 1081 goto out; 1082 1083 r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits, 1084 v->zero_digest); 1085 1086 out: 1087 kfree(io); 1088 kfree(zero_data); 1089 1090 return r; 1091 } 1092 1093 static inline bool verity_is_verity_mode(const char *arg_name) 1094 { 1095 return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) || 1096 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) || 1097 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC)); 1098 } 1099 1100 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name) 1101 { 1102 if (v->mode) 1103 return -EINVAL; 1104 1105 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) 1106 v->mode = DM_VERITY_MODE_LOGGING; 1107 else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) 1108 v->mode = DM_VERITY_MODE_RESTART; 1109 else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) 1110 v->mode = DM_VERITY_MODE_PANIC; 1111 1112 return 0; 1113 } 1114 1115 static inline bool verity_is_verity_error_mode(const char *arg_name) 1116 { 1117 return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) || 1118 !strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC)); 1119 } 1120 1121 static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name) 1122 { 1123 if (v->error_mode) 1124 return -EINVAL; 1125 1126 if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART)) 1127 v->error_mode = DM_VERITY_MODE_RESTART; 1128 else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC)) 1129 v->error_mode = DM_VERITY_MODE_PANIC; 1130 1131 return 0; 1132 } 1133 1134 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v, 1135 struct dm_verity_sig_opts *verify_args, 1136 bool only_modifier_opts) 1137 { 1138 int r = 0; 1139 unsigned int argc; 1140 struct dm_target *ti = v->ti; 1141 const char *arg_name; 1142 1143 static const struct dm_arg _args[] = { 1144 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"}, 1145 }; 1146 1147 r = dm_read_arg_group(_args, as, &argc, &ti->error); 1148 if (r) 1149 return -EINVAL; 1150 1151 if (!argc) 1152 return 0; 1153 1154 do { 1155 arg_name = dm_shift_arg(as); 1156 argc--; 1157 1158 if (verity_is_verity_mode(arg_name)) { 1159 if (only_modifier_opts) 1160 continue; 1161 r = verity_parse_verity_mode(v, arg_name); 1162 if (r) { 1163 ti->error = "Conflicting error handling parameters"; 1164 return r; 1165 } 1166 continue; 1167 1168 } else if (verity_is_verity_error_mode(arg_name)) { 1169 if (only_modifier_opts) 1170 continue; 1171 r = verity_parse_verity_error_mode(v, arg_name); 1172 if (r) { 1173 ti->error = "Conflicting error handling parameters"; 1174 return r; 1175 } 1176 continue; 1177 1178 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) { 1179 if (only_modifier_opts) 1180 continue; 1181 r = verity_alloc_zero_digest(v); 1182 if (r) { 1183 ti->error = "Cannot allocate zero digest"; 1184 return r; 1185 } 1186 continue; 1187 1188 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) { 1189 if (only_modifier_opts) 1190 continue; 1191 r = verity_alloc_most_once(v); 1192 if (r) 1193 return r; 1194 continue; 1195 1196 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) { 1197 v->use_bh_wq = true; 1198 static_branch_inc(&use_bh_wq_enabled); 1199 continue; 1200 1201 } else if (verity_is_fec_opt_arg(arg_name)) { 1202 if (only_modifier_opts) 1203 continue; 1204 r = verity_fec_parse_opt_args(as, v, &argc, arg_name); 1205 if (r) 1206 return r; 1207 continue; 1208 1209 } else if (verity_verify_is_sig_opt_arg(arg_name)) { 1210 if (only_modifier_opts) 1211 continue; 1212 r = verity_verify_sig_parse_opt_args(as, v, 1213 verify_args, 1214 &argc, arg_name); 1215 if (r) 1216 return r; 1217 continue; 1218 1219 } else if (only_modifier_opts) { 1220 /* 1221 * Ignore unrecognized opt, could easily be an extra 1222 * argument to an option whose parsing was skipped. 1223 * Normal parsing (@only_modifier_opts=false) will 1224 * properly parse all options (and their extra args). 1225 */ 1226 continue; 1227 } 1228 1229 DMERR("Unrecognized verity feature request: %s", arg_name); 1230 ti->error = "Unrecognized verity feature request"; 1231 return -EINVAL; 1232 } while (argc && !r); 1233 1234 return r; 1235 } 1236 1237 static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name) 1238 { 1239 struct dm_target *ti = v->ti; 1240 struct crypto_shash *shash; 1241 1242 v->alg_name = kstrdup(alg_name, GFP_KERNEL); 1243 if (!v->alg_name) { 1244 ti->error = "Cannot allocate algorithm name"; 1245 return -ENOMEM; 1246 } 1247 1248 shash = crypto_alloc_shash(alg_name, 0, 0); 1249 if (IS_ERR(shash)) { 1250 ti->error = "Cannot initialize hash function"; 1251 return PTR_ERR(shash); 1252 } 1253 v->shash_tfm = shash; 1254 v->digest_size = crypto_shash_digestsize(shash); 1255 DMINFO("%s using \"%s\"", alg_name, crypto_shash_driver_name(shash)); 1256 if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { 1257 ti->error = "Digest size too big"; 1258 return -EINVAL; 1259 } 1260 return 0; 1261 } 1262 1263 static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg) 1264 { 1265 struct dm_target *ti = v->ti; 1266 1267 if (strcmp(arg, "-") != 0) { 1268 v->salt_size = strlen(arg) / 2; 1269 v->salt = kmalloc(v->salt_size, GFP_KERNEL); 1270 if (!v->salt) { 1271 ti->error = "Cannot allocate salt"; 1272 return -ENOMEM; 1273 } 1274 if (strlen(arg) != v->salt_size * 2 || 1275 hex2bin(v->salt, arg, v->salt_size)) { 1276 ti->error = "Invalid salt"; 1277 return -EINVAL; 1278 } 1279 } 1280 if (v->version) { /* Version 1: salt at beginning */ 1281 SHASH_DESC_ON_STACK(desc, v->shash_tfm); 1282 int r; 1283 1284 /* 1285 * Compute the pre-salted hash state that can be passed to 1286 * crypto_shash_import() for each block later. 1287 */ 1288 v->initial_hashstate = kmalloc( 1289 crypto_shash_statesize(v->shash_tfm), GFP_KERNEL); 1290 if (!v->initial_hashstate) { 1291 ti->error = "Cannot allocate initial hash state"; 1292 return -ENOMEM; 1293 } 1294 desc->tfm = v->shash_tfm; 1295 r = crypto_shash_init(desc) ?: 1296 crypto_shash_update(desc, v->salt, v->salt_size) ?: 1297 crypto_shash_export(desc, v->initial_hashstate); 1298 if (r) { 1299 ti->error = "Cannot set up initial hash state"; 1300 return r; 1301 } 1302 } 1303 return 0; 1304 } 1305 1306 /* 1307 * Target parameters: 1308 * <version> The current format is version 1. 1309 * Vsn 0 is compatible with original Chromium OS releases. 1310 * <data device> 1311 * <hash device> 1312 * <data block size> 1313 * <hash block size> 1314 * <the number of data blocks> 1315 * <hash start block> 1316 * <algorithm> 1317 * <digest> 1318 * <salt> Hex string or "-" if no salt. 1319 */ 1320 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv) 1321 { 1322 struct dm_verity *v; 1323 struct dm_verity_sig_opts verify_args = {0}; 1324 struct dm_arg_set as; 1325 unsigned int num; 1326 unsigned long long num_ll; 1327 int r; 1328 int i; 1329 sector_t hash_position; 1330 char dummy; 1331 char *root_hash_digest_to_validate; 1332 1333 v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); 1334 if (!v) { 1335 ti->error = "Cannot allocate verity structure"; 1336 return -ENOMEM; 1337 } 1338 ti->private = v; 1339 v->ti = ti; 1340 1341 r = verity_fec_ctr_alloc(v); 1342 if (r) 1343 goto bad; 1344 1345 if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) { 1346 ti->error = "Device must be readonly"; 1347 r = -EINVAL; 1348 goto bad; 1349 } 1350 1351 if (argc < 10) { 1352 ti->error = "Not enough arguments"; 1353 r = -EINVAL; 1354 goto bad; 1355 } 1356 1357 /* Parse optional parameters that modify primary args */ 1358 if (argc > 10) { 1359 as.argc = argc - 10; 1360 as.argv = argv + 10; 1361 r = verity_parse_opt_args(&as, v, &verify_args, true); 1362 if (r < 0) 1363 goto bad; 1364 } 1365 1366 if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 || 1367 num > 1) { 1368 ti->error = "Invalid version"; 1369 r = -EINVAL; 1370 goto bad; 1371 } 1372 v->version = num; 1373 1374 r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev); 1375 if (r) { 1376 ti->error = "Data device lookup failed"; 1377 goto bad; 1378 } 1379 1380 r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev); 1381 if (r) { 1382 ti->error = "Hash device lookup failed"; 1383 goto bad; 1384 } 1385 1386 if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 || 1387 !num || (num & (num - 1)) || 1388 num < bdev_logical_block_size(v->data_dev->bdev) || 1389 num > PAGE_SIZE) { 1390 ti->error = "Invalid data device block size"; 1391 r = -EINVAL; 1392 goto bad; 1393 } 1394 v->data_dev_block_bits = __ffs(num); 1395 1396 if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || 1397 !num || (num & (num - 1)) || 1398 num < bdev_logical_block_size(v->hash_dev->bdev) || 1399 num > INT_MAX) { 1400 ti->error = "Invalid hash device block size"; 1401 r = -EINVAL; 1402 goto bad; 1403 } 1404 v->hash_dev_block_bits = __ffs(num); 1405 1406 if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 || 1407 (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) 1408 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1409 ti->error = "Invalid data blocks"; 1410 r = -EINVAL; 1411 goto bad; 1412 } 1413 v->data_blocks = num_ll; 1414 1415 if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) { 1416 ti->error = "Data device is too small"; 1417 r = -EINVAL; 1418 goto bad; 1419 } 1420 1421 if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 || 1422 (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT)) 1423 >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) { 1424 ti->error = "Invalid hash start"; 1425 r = -EINVAL; 1426 goto bad; 1427 } 1428 v->hash_start = num_ll; 1429 1430 r = verity_setup_hash_alg(v, argv[7]); 1431 if (r) 1432 goto bad; 1433 1434 v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); 1435 if (!v->root_digest) { 1436 ti->error = "Cannot allocate root digest"; 1437 r = -ENOMEM; 1438 goto bad; 1439 } 1440 if (strlen(argv[8]) != v->digest_size * 2 || 1441 hex2bin(v->root_digest, argv[8], v->digest_size)) { 1442 ti->error = "Invalid root digest"; 1443 r = -EINVAL; 1444 goto bad; 1445 } 1446 root_hash_digest_to_validate = argv[8]; 1447 1448 r = verity_setup_salt_and_hashstate(v, argv[9]); 1449 if (r) 1450 goto bad; 1451 1452 argv += 10; 1453 argc -= 10; 1454 1455 /* Optional parameters */ 1456 if (argc) { 1457 as.argc = argc; 1458 as.argv = argv; 1459 r = verity_parse_opt_args(&as, v, &verify_args, false); 1460 if (r < 0) 1461 goto bad; 1462 } 1463 1464 /* Root hash signature is an optional parameter */ 1465 r = verity_verify_root_hash(root_hash_digest_to_validate, 1466 strlen(root_hash_digest_to_validate), 1467 verify_args.sig, 1468 verify_args.sig_size); 1469 if (r < 0) { 1470 ti->error = "Root hash verification failed"; 1471 goto bad; 1472 } 1473 1474 r = verity_init_sig(v, verify_args.sig, verify_args.sig_size); 1475 if (r < 0) { 1476 ti->error = "Cannot allocate root digest signature"; 1477 goto bad; 1478 } 1479 1480 v->hash_per_block_bits = 1481 __fls((1 << v->hash_dev_block_bits) / v->digest_size); 1482 1483 v->levels = 0; 1484 if (v->data_blocks) 1485 while (v->hash_per_block_bits * v->levels < 64 && 1486 (unsigned long long)(v->data_blocks - 1) >> 1487 (v->hash_per_block_bits * v->levels)) 1488 v->levels++; 1489 1490 if (v->levels > DM_VERITY_MAX_LEVELS) { 1491 ti->error = "Too many tree levels"; 1492 r = -E2BIG; 1493 goto bad; 1494 } 1495 1496 hash_position = v->hash_start; 1497 for (i = v->levels - 1; i >= 0; i--) { 1498 sector_t s; 1499 1500 v->hash_level_block[i] = hash_position; 1501 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1) 1502 >> ((i + 1) * v->hash_per_block_bits); 1503 if (hash_position + s < hash_position) { 1504 ti->error = "Hash device offset overflow"; 1505 r = -E2BIG; 1506 goto bad; 1507 } 1508 hash_position += s; 1509 } 1510 v->hash_blocks = hash_position; 1511 1512 r = mempool_init_page_pool(&v->recheck_pool, 1, 0); 1513 if (unlikely(r)) { 1514 ti->error = "Cannot allocate mempool"; 1515 goto bad; 1516 } 1517 1518 v->io = dm_io_client_create(); 1519 if (IS_ERR(v->io)) { 1520 r = PTR_ERR(v->io); 1521 v->io = NULL; 1522 ti->error = "Cannot allocate dm io"; 1523 goto bad; 1524 } 1525 1526 v->bufio = dm_bufio_client_create(v->hash_dev->bdev, 1527 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), 1528 dm_bufio_alloc_callback, NULL, 1529 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0); 1530 if (IS_ERR(v->bufio)) { 1531 ti->error = "Cannot initialize dm-bufio"; 1532 r = PTR_ERR(v->bufio); 1533 v->bufio = NULL; 1534 goto bad; 1535 } 1536 1537 if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { 1538 ti->error = "Hash device is too small"; 1539 r = -E2BIG; 1540 goto bad; 1541 } 1542 1543 /* 1544 * Using WQ_HIGHPRI improves throughput and completion latency by 1545 * reducing wait times when reading from a dm-verity device. 1546 * 1547 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI 1548 * allows verify_wq to preempt softirq since verification in BH workqueue 1549 * will fall-back to using it for error handling (or if the bufio cache 1550 * doesn't have required hashes). 1551 */ 1552 v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1553 if (!v->verify_wq) { 1554 ti->error = "Cannot allocate workqueue"; 1555 r = -ENOMEM; 1556 goto bad; 1557 } 1558 1559 ti->per_io_data_size = sizeof(struct dm_verity_io) + 1560 crypto_shash_descsize(v->shash_tfm); 1561 1562 r = verity_fec_ctr(v); 1563 if (r) 1564 goto bad; 1565 1566 ti->per_io_data_size = roundup(ti->per_io_data_size, 1567 __alignof__(struct dm_verity_io)); 1568 1569 verity_verify_sig_opts_cleanup(&verify_args); 1570 1571 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1); 1572 1573 return 0; 1574 1575 bad: 1576 1577 verity_verify_sig_opts_cleanup(&verify_args); 1578 dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0); 1579 verity_dtr(ti); 1580 1581 return r; 1582 } 1583 1584 /* 1585 * Get the verity mode (error behavior) of a verity target. 1586 * 1587 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity 1588 * target. 1589 */ 1590 int dm_verity_get_mode(struct dm_target *ti) 1591 { 1592 struct dm_verity *v = ti->private; 1593 1594 if (!dm_is_verity_target(ti)) 1595 return -EINVAL; 1596 1597 return v->mode; 1598 } 1599 1600 /* 1601 * Get the root digest of a verity target. 1602 * 1603 * Returns a copy of the root digest, the caller is responsible for 1604 * freeing the memory of the digest. 1605 */ 1606 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size) 1607 { 1608 struct dm_verity *v = ti->private; 1609 1610 if (!dm_is_verity_target(ti)) 1611 return -EINVAL; 1612 1613 *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL); 1614 if (*root_digest == NULL) 1615 return -ENOMEM; 1616 1617 *digest_size = v->digest_size; 1618 1619 return 0; 1620 } 1621 1622 #ifdef CONFIG_SECURITY 1623 1624 #ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG 1625 1626 static int verity_security_set_signature(struct block_device *bdev, 1627 struct dm_verity *v) 1628 { 1629 /* 1630 * if the dm-verity target is unsigned, v->root_digest_sig will 1631 * be NULL, and the hook call is still required to let LSMs mark 1632 * the device as unsigned. This information is crucial for LSMs to 1633 * block operations such as execution on unsigned files 1634 */ 1635 return security_bdev_setintegrity(bdev, 1636 LSM_INT_DMVERITY_SIG_VALID, 1637 v->root_digest_sig, 1638 v->sig_size); 1639 } 1640 1641 #else 1642 1643 static inline int verity_security_set_signature(struct block_device *bdev, 1644 struct dm_verity *v) 1645 { 1646 return 0; 1647 } 1648 1649 #endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */ 1650 1651 /* 1652 * Expose verity target's root hash and signature data to LSMs before resume. 1653 * 1654 * Returns 0 on success, or -ENOMEM if the system is out of memory. 1655 */ 1656 static int verity_preresume(struct dm_target *ti) 1657 { 1658 struct block_device *bdev; 1659 struct dm_verity_digest root_digest; 1660 struct dm_verity *v; 1661 int r; 1662 1663 v = ti->private; 1664 bdev = dm_disk(dm_table_get_md(ti->table))->part0; 1665 root_digest.digest = v->root_digest; 1666 root_digest.digest_len = v->digest_size; 1667 root_digest.alg = crypto_shash_alg_name(v->shash_tfm); 1668 1669 r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest, 1670 sizeof(root_digest)); 1671 if (r) 1672 return r; 1673 1674 r = verity_security_set_signature(bdev, v); 1675 if (r) 1676 goto bad; 1677 1678 return 0; 1679 1680 bad: 1681 1682 security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0); 1683 1684 return r; 1685 } 1686 1687 #endif /* CONFIG_SECURITY */ 1688 1689 static struct target_type verity_target = { 1690 .name = "verity", 1691 /* Note: the LSMs depend on the singleton and immutable features */ 1692 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE, 1693 .version = {1, 12, 0}, 1694 .module = THIS_MODULE, 1695 .ctr = verity_ctr, 1696 .dtr = verity_dtr, 1697 .map = verity_map, 1698 .postsuspend = verity_postsuspend, 1699 .status = verity_status, 1700 .prepare_ioctl = verity_prepare_ioctl, 1701 .iterate_devices = verity_iterate_devices, 1702 .io_hints = verity_io_hints, 1703 #ifdef CONFIG_SECURITY 1704 .preresume = verity_preresume, 1705 #endif /* CONFIG_SECURITY */ 1706 }; 1707 module_dm(verity); 1708 1709 /* 1710 * Check whether a DM target is a verity target. 1711 */ 1712 bool dm_is_verity_target(struct dm_target *ti) 1713 { 1714 return ti->type == &verity_target; 1715 } 1716 1717 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>"); 1718 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>"); 1719 MODULE_AUTHOR("Will Drewry <wad@chromium.org>"); 1720 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); 1721 MODULE_LICENSE("GPL"); 1722