drivers/md/dm-verity-target.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Red Hat, Inc.
   4  *
   5  * Author: Mikulas Patocka <mpatocka@redhat.com>
   6  *
   7  * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   8  *
   9  * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
  10  * default prefetch value. Data are read in "prefetch_cluster" chunks from the
  11  * hash device. Setting this greatly improves performance when data and hash
  12  * are on the same disk on different partitions on devices with poor random
  13  * access behavior.
  14  */
  15
  16 #include "dm-verity.h"
  17 #include "dm-verity-fec.h"
  18 #include "dm-verity-verify-sig.h"
  19 #include "dm-audit.h"
  20 #include <linux/module.h>
  21 #include <linux/reboot.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/string.h>
  24 #include <linux/jump_label.h>
  25
  26 #define DM_MSG_PREFIX                   "verity"
  27
  28 #define DM_VERITY_ENV_LENGTH            42
  29 #define DM_VERITY_ENV_VAR_NAME          "DM_VERITY_ERR_BLOCK_NR"
  30
  31 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
  32
  33 #define DM_VERITY_MAX_CORRUPTED_ERRS    100
  34
  35 #define DM_VERITY_OPT_LOGGING           "ignore_corruption"
  36 #define DM_VERITY_OPT_RESTART           "restart_on_corruption"
  37 #define DM_VERITY_OPT_PANIC             "panic_on_corruption"
  38 #define DM_VERITY_OPT_IGN_ZEROES        "ignore_zero_blocks"
  39 #define DM_VERITY_OPT_AT_MOST_ONCE      "check_at_most_once"
  40 #define DM_VERITY_OPT_TASKLET_VERIFY    "try_verify_in_tasklet"
  41
  42 #define DM_VERITY_OPTS_MAX              (4 + DM_VERITY_OPTS_FEC + \
  43                                          DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
  44
  45 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  46
  47 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
  48
  49 static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
  50
  51 struct dm_verity_prefetch_work {
  52         struct work_struct work;
  53         struct dm_verity *v;
  54         sector_t block;
  55         unsigned int n_blocks;
  56 };
  57
  58 /*
  59  * Auxiliary structure appended to each dm-bufio buffer. If the value
  60  * hash_verified is nonzero, hash of the block has been verified.
  61  *
  62  * The variable hash_verified is set to 0 when allocating the buffer, then
  63  * it can be changed to 1 and it is never reset to 0 again.
  64  *
  65  * There is no lock around this value, a race condition can at worst cause
  66  * that multiple processes verify the hash of the same buffer simultaneously
  67  * and write 1 to hash_verified simultaneously.
  68  * This condition is harmless, so we don't need locking.
  69  */
  70 struct buffer_aux {
  71         int hash_verified;
  72 };
  73
  74 /*
  75  * Initialize struct buffer_aux for a freshly created buffer.
  76  */
  77 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  78 {
  79         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  80
  81         aux->hash_verified = 0;
  82 }
  83
  84 /*
  85  * Translate input sector number to the sector number on the target device.
  86  */
  87 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  88 {
  89         return v->data_start + dm_target_offset(v->ti, bi_sector);
  90 }
  91
  92 /*
  93  * Return hash position of a specified block at a specified tree level
  94  * (0 is the lowest level).
  95  * The lowest "hash_per_block_bits"-bits of the result denote hash position
  96  * inside a hash block. The remaining bits denote location of the hash block.
  97  */
  98 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
  99                                          int level)
 100 {
 101         return block >> (level * v->hash_per_block_bits);
 102 }
 103
 104 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
 105                                 const u8 *data, size_t len,
 106                                 struct crypto_wait *wait)
 107 {
 108         struct scatterlist sg;
 109
 110         if (likely(!is_vmalloc_addr(data))) {
 111                 sg_init_one(&sg, data, len);
 112                 ahash_request_set_crypt(req, &sg, NULL, len);
 113                 return crypto_wait_req(crypto_ahash_update(req), wait);
 114         }
 115
 116         do {
 117                 int r;
 118                 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 119
 120                 flush_kernel_vmap_range((void *)data, this_step);
 121                 sg_init_table(&sg, 1);
 122                 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 123                 ahash_request_set_crypt(req, &sg, NULL, this_step);
 124                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 125                 if (unlikely(r))
 126                         return r;
 127                 data += this_step;
 128                 len -= this_step;
 129         } while (len);
 130
 131         return 0;
 132 }
 133
 134 /*
 135  * Wrapper for crypto_ahash_init, which handles verity salting.
 136  */
 137 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
 138                                 struct crypto_wait *wait)
 139 {
 140         int r;
 141
 142         ahash_request_set_tfm(req, v->tfm);
 143         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
 144                                         CRYPTO_TFM_REQ_MAY_BACKLOG,
 145                                         crypto_req_done, (void *)wait);
 146         crypto_init_wait(wait);
 147
 148         r = crypto_wait_req(crypto_ahash_init(req), wait);
 149
 150         if (unlikely(r < 0)) {
 151                 DMERR("crypto_ahash_init failed: %d", r);
 152                 return r;
 153         }
 154
 155         if (likely(v->salt_size && (v->version >= 1)))
 156                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 157
 158         return r;
 159 }
 160
 161 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
 162                              u8 *digest, struct crypto_wait *wait)
 163 {
 164         int r;
 165
 166         if (unlikely(v->salt_size && (!v->version))) {
 167                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 168
 169                 if (r < 0) {
 170                         DMERR("%s failed updating salt: %d", __func__, r);
 171                         goto out;
 172                 }
 173         }
 174
 175         ahash_request_set_crypt(req, NULL, digest, 0);
 176         r = crypto_wait_req(crypto_ahash_final(req), wait);
 177 out:
 178         return r;
 179 }
 180
 181 int verity_hash(struct dm_verity *v, struct ahash_request *req,
 182                 const u8 *data, size_t len, u8 *digest)
 183 {
 184         int r;
 185         struct crypto_wait wait;
 186
 187         r = verity_hash_init(v, req, &wait);
 188         if (unlikely(r < 0))
 189                 goto out;
 190
 191         r = verity_hash_update(v, req, data, len, &wait);
 192         if (unlikely(r < 0))
 193                 goto out;
 194
 195         r = verity_hash_final(v, req, digest, &wait);
 196
 197 out:
 198         return r;
 199 }
 200
 201 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 202                                  sector_t *hash_block, unsigned int *offset)
 203 {
 204         sector_t position = verity_position_at_level(v, block, level);
 205         unsigned int idx;
 206
 207         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 208
 209         if (!offset)
 210                 return;
 211
 212         idx = position & ((1 << v->hash_per_block_bits) - 1);
 213         if (!v->version)
 214                 *offset = idx * v->digest_size;
 215         else
 216                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 217 }
 218
 219 /*
 220  * Handle verification errors.
 221  */
 222 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 223                              unsigned long long block)
 224 {
 225         char verity_env[DM_VERITY_ENV_LENGTH];
 226         char *envp[] = { verity_env, NULL };
 227         const char *type_str = "";
 228         struct mapped_device *md = dm_table_get_md(v->ti->table);
 229
 230         /* Corruption should be visible in device status in all modes */
 231         v->hash_failed = true;
 232
 233         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 234                 goto out;
 235
 236         v->corrupted_errs++;
 237
 238         switch (type) {
 239         case DM_VERITY_BLOCK_TYPE_DATA:
 240                 type_str = "data";
 241                 break;
 242         case DM_VERITY_BLOCK_TYPE_METADATA:
 243                 type_str = "metadata";
 244                 break;
 245         default:
 246                 BUG();
 247         }
 248
 249         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 250                     type_str, block);
 251
 252         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
 253                 DMERR("%s: reached maximum errors", v->data_dev->name);
 254                 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
 255         }
 256
 257         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 258                 DM_VERITY_ENV_VAR_NAME, type, block);
 259
 260         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 261
 262 out:
 263         if (v->mode == DM_VERITY_MODE_LOGGING)
 264                 return 0;
 265
 266         if (v->mode == DM_VERITY_MODE_RESTART)
 267                 kernel_restart("dm-verity device corrupted");
 268
 269         if (v->mode == DM_VERITY_MODE_PANIC)
 270                 panic("dm-verity device corrupted");
 271
 272         return 1;
 273 }
 274
 275 /*
 276  * Verify hash of a metadata block pertaining to the specified data block
 277  * ("block" argument) at a specified level ("level" argument).
 278  *
 279  * On successful return, verity_io_want_digest(v, io) contains the hash value
 280  * for a lower tree level or for the data block (if we're at the lowest level).
 281  *
 282  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 283  * If "skip_unverified" is false, unverified buffer is hashed and verified
 284  * against current value of verity_io_want_digest(v, io).
 285  */
 286 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 287                                sector_t block, int level, bool skip_unverified,
 288                                u8 *want_digest)
 289 {
 290         struct dm_buffer *buf;
 291         struct buffer_aux *aux;
 292         u8 *data;
 293         int r;
 294         sector_t hash_block;
 295         unsigned int offset;
 296
 297         verity_hash_at_level(v, block, level, &hash_block, &offset);
 298
 299         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 300                 data = dm_bufio_get(v->bufio, hash_block, &buf);
 301                 if (data == NULL) {
 302                         /*
 303                          * In tasklet and the hash was not in the bufio cache.
 304                          * Return early and resume execution from a work-queue
 305                          * to read the hash from disk.
 306                          */
 307                         return -EAGAIN;
 308                 }
 309         } else
 310                 data = dm_bufio_read(v->bufio, hash_block, &buf);
 311
 312         if (IS_ERR(data))
 313                 return PTR_ERR(data);
 314
 315         aux = dm_bufio_get_aux_data(buf);
 316
 317         if (!aux->hash_verified) {
 318                 if (skip_unverified) {
 319                         r = 1;
 320                         goto release_ret_r;
 321                 }
 322
 323                 r = verity_hash(v, verity_io_hash_req(v, io),
 324                                 data, 1 << v->hash_dev_block_bits,
 325                                 verity_io_real_digest(v, io));
 326                 if (unlikely(r < 0))
 327                         goto release_ret_r;
 328
 329                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 330                                   v->digest_size) == 0))
 331                         aux->hash_verified = 1;
 332                 else if (static_branch_unlikely(&use_tasklet_enabled) &&
 333                          io->in_tasklet) {
 334                         /*
 335                          * Error handling code (FEC included) cannot be run in a
 336                          * tasklet since it may sleep, so fallback to work-queue.
 337                          */
 338                         r = -EAGAIN;
 339                         goto release_ret_r;
 340                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 341                                              hash_block, data, NULL) == 0)
 342                         aux->hash_verified = 1;
 343                 else if (verity_handle_err(v,
 344                                            DM_VERITY_BLOCK_TYPE_METADATA,
 345                                            hash_block)) {
 346                         struct bio *bio =
 347                                 dm_bio_from_per_bio_data(io,
 348                                                          v->ti->per_io_data_size);
 349                         dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
 350                                          block, 0);
 351                         r = -EIO;
 352                         goto release_ret_r;
 353                 }
 354         }
 355
 356         data += offset;
 357         memcpy(want_digest, data, v->digest_size);
 358         r = 0;
 359
 360 release_ret_r:
 361         dm_bufio_release(buf);
 362         return r;
 363 }
 364
 365 /*
 366  * Find a hash for a given block, write it to digest and verify the integrity
 367  * of the hash tree if necessary.
 368  */
 369 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 370                           sector_t block, u8 *digest, bool *is_zero)
 371 {
 372         int r = 0, i;
 373
 374         if (likely(v->levels)) {
 375                 /*
 376                  * First, we try to get the requested hash for
 377                  * the current block. If the hash block itself is
 378                  * verified, zero is returned. If it isn't, this
 379                  * function returns 1 and we fall back to whole
 380                  * chain verification.
 381                  */
 382                 r = verity_verify_level(v, io, block, 0, true, digest);
 383                 if (likely(r <= 0))
 384                         goto out;
 385         }
 386
 387         memcpy(digest, v->root_digest, v->digest_size);
 388
 389         for (i = v->levels - 1; i >= 0; i--) {
 390                 r = verity_verify_level(v, io, block, i, false, digest);
 391                 if (unlikely(r))
 392                         goto out;
 393         }
 394 out:
 395         if (!r && v->zero_digest)
 396                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 397         else
 398                 *is_zero = false;
 399
 400         return r;
 401 }
 402
 403 /*
 404  * Calculates the digest for the given bio
 405  */
 406 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
 407                                struct bvec_iter *iter, struct crypto_wait *wait)
 408 {
 409         unsigned int todo = 1 << v->data_dev_block_bits;
 410         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 411         struct scatterlist sg;
 412         struct ahash_request *req = verity_io_hash_req(v, io);
 413
 414         do {
 415                 int r;
 416                 unsigned int len;
 417                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 418
 419                 sg_init_table(&sg, 1);
 420
 421                 len = bv.bv_len;
 422
 423                 if (likely(len >= todo))
 424                         len = todo;
 425                 /*
 426                  * Operating on a single page at a time looks suboptimal
 427                  * until you consider the typical block size is 4,096B.
 428                  * Going through this loops twice should be very rare.
 429                  */
 430                 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
 431                 ahash_request_set_crypt(req, &sg, NULL, len);
 432                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 433
 434                 if (unlikely(r < 0)) {
 435                         DMERR("%s crypto op failed: %d", __func__, r);
 436                         return r;
 437                 }
 438
 439                 bio_advance_iter(bio, iter, len);
 440                 todo -= len;
 441         } while (todo);
 442
 443         return 0;
 444 }
 445
 446 /*
 447  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
 448  * starting from iter.
 449  */
 450 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 451                         struct bvec_iter *iter,
 452                         int (*process)(struct dm_verity *v,
 453                                        struct dm_verity_io *io, u8 *data,
 454                                        size_t len))
 455 {
 456         unsigned int todo = 1 << v->data_dev_block_bits;
 457         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 458
 459         do {
 460                 int r;
 461                 u8 *page;
 462                 unsigned int len;
 463                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 464
 465                 page = bvec_kmap_local(&bv);
 466                 len = bv.bv_len;
 467
 468                 if (likely(len >= todo))
 469                         len = todo;
 470
 471                 r = process(v, io, page, len);
 472                 kunmap_local(page);
 473
 474                 if (r < 0)
 475                         return r;
 476
 477                 bio_advance_iter(bio, iter, len);
 478                 todo -= len;
 479         } while (todo);
 480
 481         return 0;
 482 }
 483
 484 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 485                           u8 *data, size_t len)
 486 {
 487         memset(data, 0, len);
 488         return 0;
 489 }
 490
 491 /*
 492  * Moves the bio iter one data block forward.
 493  */
 494 static inline void verity_bv_skip_block(struct dm_verity *v,
 495                                         struct dm_verity_io *io,
 496                                         struct bvec_iter *iter)
 497 {
 498         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 499
 500         bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
 501 }
 502
 503 /*
 504  * Verify one "dm_verity_io" structure.
 505  */
 506 static int verity_verify_io(struct dm_verity_io *io)
 507 {
 508         bool is_zero;
 509         struct dm_verity *v = io->v;
 510 #if defined(CONFIG_DM_VERITY_FEC)
 511         struct bvec_iter start;
 512 #endif
 513         struct bvec_iter iter_copy;
 514         struct bvec_iter *iter;
 515         struct crypto_wait wait;
 516         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 517         unsigned int b;
 518
 519         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 520                 /*
 521                  * Copy the iterator in case we need to restart
 522                  * verification in a work-queue.
 523                  */
 524                 iter_copy = io->iter;
 525                 iter = &iter_copy;
 526         } else
 527                 iter = &io->iter;
 528
 529         for (b = 0; b < io->n_blocks; b++) {
 530                 int r;
 531                 sector_t cur_block = io->block + b;
 532                 struct ahash_request *req = verity_io_hash_req(v, io);
 533
 534                 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 535                     likely(test_bit(cur_block, v->validated_blocks))) {
 536                         verity_bv_skip_block(v, io, iter);
 537                         continue;
 538                 }
 539
 540                 r = verity_hash_for_block(v, io, cur_block,
 541                                           verity_io_want_digest(v, io),
 542                                           &is_zero);
 543                 if (unlikely(r < 0))
 544                         return r;
 545
 546                 if (is_zero) {
 547                         /*
 548                          * If we expect a zero block, don't validate, just
 549                          * return zeros.
 550                          */
 551                         r = verity_for_bv_block(v, io, iter,
 552                                                 verity_bv_zero);
 553                         if (unlikely(r < 0))
 554                                 return r;
 555
 556                         continue;
 557                 }
 558
 559                 r = verity_hash_init(v, req, &wait);
 560                 if (unlikely(r < 0))
 561                         return r;
 562
 563 #if defined(CONFIG_DM_VERITY_FEC)
 564                 if (verity_fec_is_enabled(v))
 565                         start = *iter;
 566 #endif
 567                 r = verity_for_io_block(v, io, iter, &wait);
 568                 if (unlikely(r < 0))
 569                         return r;
 570
 571                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 572                                         &wait);
 573                 if (unlikely(r < 0))
 574                         return r;
 575
 576                 if (likely(memcmp(verity_io_real_digest(v, io),
 577                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 578                         if (v->validated_blocks)
 579                                 set_bit(cur_block, v->validated_blocks);
 580                         continue;
 581                 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
 582                            io->in_tasklet) {
 583                         /*
 584                          * Error handling code (FEC included) cannot be run in a
 585                          * tasklet since it may sleep, so fallback to work-queue.
 586                          */
 587                         return -EAGAIN;
 588 #if defined(CONFIG_DM_VERITY_FEC)
 589                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 590                                              cur_block, NULL, &start) == 0) {
 591                         continue;
 592 #endif
 593                 } else {
 594                         if (bio->bi_status) {
 595                                 /*
 596                                  * Error correction failed; Just return error
 597                                  */
 598                                 return -EIO;
 599                         }
 600                         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 601                                               cur_block)) {
 602                                 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
 603                                                  bio, cur_block, 0);
 604                                 return -EIO;
 605                         }
 606                 }
 607         }
 608
 609         return 0;
 610 }
 611
 612 /*
 613  * Skip verity work in response to I/O error when system is shutting down.
 614  */
 615 static inline bool verity_is_system_shutting_down(void)
 616 {
 617         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 618                 || system_state == SYSTEM_RESTART;
 619 }
 620
 621 /*
 622  * End one "io" structure with a given error.
 623  */
 624 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 625 {
 626         struct dm_verity *v = io->v;
 627         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 628
 629         bio->bi_end_io = io->orig_bi_end_io;
 630         bio->bi_status = status;
 631
 632         if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
 633                 verity_fec_finish_io(io);
 634
 635         bio_endio(bio);
 636 }
 637
 638 static void verity_work(struct work_struct *w)
 639 {
 640         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 641
 642         io->in_tasklet = false;
 643
 644         verity_fec_init_io(io);
 645         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 646 }
 647
 648 static void verity_tasklet(unsigned long data)
 649 {
 650         struct dm_verity_io *io = (struct dm_verity_io *)data;
 651         int err;
 652
 653         io->in_tasklet = true;
 654         err = verity_verify_io(io);
 655         if (err == -EAGAIN) {
 656                 /* fallback to retrying with work-queue */
 657                 INIT_WORK(&io->work, verity_work);
 658                 queue_work(io->v->verify_wq, &io->work);
 659                 return;
 660         }
 661
 662         verity_finish_io(io, errno_to_blk_status(err));
 663 }
 664
 665 static void verity_end_io(struct bio *bio)
 666 {
 667         struct dm_verity_io *io = bio->bi_private;
 668
 669         if (bio->bi_status &&
 670             (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
 671                 verity_finish_io(io, bio->bi_status);
 672                 return;
 673         }
 674
 675         if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
 676                 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
 677                 tasklet_schedule(&io->tasklet);
 678         } else {
 679                 INIT_WORK(&io->work, verity_work);
 680                 queue_work(io->v->verify_wq, &io->work);
 681         }
 682 }
 683
 684 /*
 685  * Prefetch buffers for the specified io.
 686  * The root buffer is not prefetched, it is assumed that it will be cached
 687  * all the time.
 688  */
 689 static void verity_prefetch_io(struct work_struct *work)
 690 {
 691         struct dm_verity_prefetch_work *pw =
 692                 container_of(work, struct dm_verity_prefetch_work, work);
 693         struct dm_verity *v = pw->v;
 694         int i;
 695
 696         for (i = v->levels - 2; i >= 0; i--) {
 697                 sector_t hash_block_start;
 698                 sector_t hash_block_end;
 699
 700                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 701                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 702
 703                 if (!i) {
 704                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 705
 706                         cluster >>= v->data_dev_block_bits;
 707                         if (unlikely(!cluster))
 708                                 goto no_prefetch_cluster;
 709
 710                         if (unlikely(cluster & (cluster - 1)))
 711                                 cluster = 1 << __fls(cluster);
 712
 713                         hash_block_start &= ~(sector_t)(cluster - 1);
 714                         hash_block_end |= cluster - 1;
 715                         if (unlikely(hash_block_end >= v->hash_blocks))
 716                                 hash_block_end = v->hash_blocks - 1;
 717                 }
 718 no_prefetch_cluster:
 719                 dm_bufio_prefetch(v->bufio, hash_block_start,
 720                                   hash_block_end - hash_block_start + 1);
 721         }
 722
 723         kfree(pw);
 724 }
 725
 726 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 727 {
 728         sector_t block = io->block;
 729         unsigned int n_blocks = io->n_blocks;
 730         struct dm_verity_prefetch_work *pw;
 731
 732         if (v->validated_blocks) {
 733                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 734                         block++;
 735                         n_blocks--;
 736                 }
 737                 while (n_blocks && test_bit(block + n_blocks - 1,
 738                                             v->validated_blocks))
 739                         n_blocks--;
 740                 if (!n_blocks)
 741                         return;
 742         }
 743
 744         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 745                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 746
 747         if (!pw)
 748                 return;
 749
 750         INIT_WORK(&pw->work, verity_prefetch_io);
 751         pw->v = v;
 752         pw->block = block;
 753         pw->n_blocks = n_blocks;
 754         queue_work(v->verify_wq, &pw->work);
 755 }
 756
 757 /*
 758  * Bio map function. It allocates dm_verity_io structure and bio vector and
 759  * fills them. Then it issues prefetches and the I/O.
 760  */
 761 static int verity_map(struct dm_target *ti, struct bio *bio)
 762 {
 763         struct dm_verity *v = ti->private;
 764         struct dm_verity_io *io;
 765
 766         bio_set_dev(bio, v->data_dev->bdev);
 767         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 768
 769         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 770             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 771                 DMERR_LIMIT("unaligned io");
 772                 return DM_MAPIO_KILL;
 773         }
 774
 775         if (bio_end_sector(bio) >>
 776             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 777                 DMERR_LIMIT("io out of range");
 778                 return DM_MAPIO_KILL;
 779         }
 780
 781         if (bio_data_dir(bio) == WRITE)
 782                 return DM_MAPIO_KILL;
 783
 784         io = dm_per_bio_data(bio, ti->per_io_data_size);
 785         io->v = v;
 786         io->orig_bi_end_io = bio->bi_end_io;
 787         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 788         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 789
 790         bio->bi_end_io = verity_end_io;
 791         bio->bi_private = io;
 792         io->iter = bio->bi_iter;
 793
 794         verity_submit_prefetch(v, io);
 795
 796         submit_bio_noacct(bio);
 797
 798         return DM_MAPIO_SUBMITTED;
 799 }
 800
 801 /*
 802  * Status: V (valid) or C (corruption found)
 803  */
 804 static void verity_status(struct dm_target *ti, status_type_t type,
 805                           unsigned int status_flags, char *result, unsigned int maxlen)
 806 {
 807         struct dm_verity *v = ti->private;
 808         unsigned int args = 0;
 809         unsigned int sz = 0;
 810         unsigned int x;
 811
 812         switch (type) {
 813         case STATUSTYPE_INFO:
 814                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 815                 break;
 816         case STATUSTYPE_TABLE:
 817                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 818                         v->version,
 819                         v->data_dev->name,
 820                         v->hash_dev->name,
 821                         1 << v->data_dev_block_bits,
 822                         1 << v->hash_dev_block_bits,
 823                         (unsigned long long)v->data_blocks,
 824                         (unsigned long long)v->hash_start,
 825                         v->alg_name
 826                         );
 827                 for (x = 0; x < v->digest_size; x++)
 828                         DMEMIT("%02x", v->root_digest[x]);
 829                 DMEMIT(" ");
 830                 if (!v->salt_size)
 831                         DMEMIT("-");
 832                 else
 833                         for (x = 0; x < v->salt_size; x++)
 834                                 DMEMIT("%02x", v->salt[x]);
 835                 if (v->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_tasklet)
 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->zero_digest)
 867                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 868                 if (v->validated_blocks)
 869                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 870                 if (v->use_tasklet)
 871                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 872                 sz = verity_fec_status_table(v, sz, result, maxlen);
 873                 if (v->signature_key_desc)
 874                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 875                                 " %s", v->signature_key_desc);
 876                 break;
 877
 878         case STATUSTYPE_IMA:
 879                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 880                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 881                 DMEMIT(",verity_version=%u", v->version);
 882                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 883                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 884                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 885
 886                 DMEMIT(",root_digest=");
 887                 for (x = 0; x < v->digest_size; x++)
 888                         DMEMIT("%02x", v->root_digest[x]);
 889
 890                 DMEMIT(",salt=");
 891                 if (!v->salt_size)
 892                         DMEMIT("-");
 893                 else
 894                         for (x = 0; x < v->salt_size; x++)
 895                                 DMEMIT("%02x", v->salt[x]);
 896
 897                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 898                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 899                 if (v->signature_key_desc)
 900                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 901
 902                 if (v->mode != DM_VERITY_MODE_EIO) {
 903                         DMEMIT(",verity_mode=");
 904                         switch (v->mode) {
 905                         case DM_VERITY_MODE_LOGGING:
 906                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 907                                 break;
 908                         case DM_VERITY_MODE_RESTART:
 909                                 DMEMIT(DM_VERITY_OPT_RESTART);
 910                                 break;
 911                         case DM_VERITY_MODE_PANIC:
 912                                 DMEMIT(DM_VERITY_OPT_PANIC);
 913                                 break;
 914                         default:
 915                                 DMEMIT("invalid");
 916                         }
 917                 }
 918                 DMEMIT(";");
 919                 break;
 920         }
 921 }
 922
 923 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 924 {
 925         struct dm_verity *v = ti->private;
 926
 927         *bdev = v->data_dev->bdev;
 928
 929         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 930                 return 1;
 931         return 0;
 932 }
 933
 934 static int verity_iterate_devices(struct dm_target *ti,
 935                                   iterate_devices_callout_fn fn, void *data)
 936 {
 937         struct dm_verity *v = ti->private;
 938
 939         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 940 }
 941
 942 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 943 {
 944         struct dm_verity *v = ti->private;
 945
 946         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 947                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 948
 949         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 950                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 951
 952         blk_limits_io_min(limits, limits->logical_block_size);
 953 }
 954
 955 static void verity_dtr(struct dm_target *ti)
 956 {
 957         struct dm_verity *v = ti->private;
 958
 959         if (v->verify_wq)
 960                 destroy_workqueue(v->verify_wq);
 961
 962         if (v->bufio)
 963                 dm_bufio_client_destroy(v->bufio);
 964
 965         kvfree(v->validated_blocks);
 966         kfree(v->salt);
 967         kfree(v->root_digest);
 968         kfree(v->zero_digest);
 969
 970         if (v->tfm)
 971                 crypto_free_ahash(v->tfm);
 972
 973         kfree(v->alg_name);
 974
 975         if (v->hash_dev)
 976                 dm_put_device(ti, v->hash_dev);
 977
 978         if (v->data_dev)
 979                 dm_put_device(ti, v->data_dev);
 980
 981         verity_fec_dtr(v);
 982
 983         kfree(v->signature_key_desc);
 984
 985         if (v->use_tasklet)
 986                 static_branch_dec(&use_tasklet_enabled);
 987
 988         kfree(v);
 989
 990         dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
 991 }
 992
 993 static int verity_alloc_most_once(struct dm_verity *v)
 994 {
 995         struct dm_target *ti = v->ti;
 996
 997         /* the bitset can only handle INT_MAX blocks */
 998         if (v->data_blocks > INT_MAX) {
 999                 ti->error = "device too large to use check_at_most_once";
1000                 return -E2BIG;
1001         }
1002
1003         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1004                                        sizeof(unsigned long),
1005                                        GFP_KERNEL);
1006         if (!v->validated_blocks) {
1007                 ti->error = "failed to allocate bitset for check_at_most_once";
1008                 return -ENOMEM;
1009         }
1010
1011         return 0;
1012 }
1013
1014 static int verity_alloc_zero_digest(struct dm_verity *v)
1015 {
1016         int r = -ENOMEM;
1017         struct ahash_request *req;
1018         u8 *zero_data;
1019
1020         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1021
1022         if (!v->zero_digest)
1023                 return r;
1024
1025         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1026
1027         if (!req)
1028                 return r; /* verity_dtr will free zero_digest */
1029
1030         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1031
1032         if (!zero_data)
1033                 goto out;
1034
1035         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1036                         v->zero_digest);
1037
1038 out:
1039         kfree(req);
1040         kfree(zero_data);
1041
1042         return r;
1043 }
1044
1045 static inline bool verity_is_verity_mode(const char *arg_name)
1046 {
1047         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1048                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1049                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1050 }
1051
1052 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1053 {
1054         if (v->mode)
1055                 return -EINVAL;
1056
1057         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1058                 v->mode = DM_VERITY_MODE_LOGGING;
1059         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1060                 v->mode = DM_VERITY_MODE_RESTART;
1061         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1062                 v->mode = DM_VERITY_MODE_PANIC;
1063
1064         return 0;
1065 }
1066
1067 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1068                                  struct dm_verity_sig_opts *verify_args,
1069                                  bool only_modifier_opts)
1070 {
1071         int r = 0;
1072         unsigned int argc;
1073         struct dm_target *ti = v->ti;
1074         const char *arg_name;
1075
1076         static const struct dm_arg _args[] = {
1077                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1078         };
1079
1080         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1081         if (r)
1082                 return -EINVAL;
1083
1084         if (!argc)
1085                 return 0;
1086
1087         do {
1088                 arg_name = dm_shift_arg(as);
1089                 argc--;
1090
1091                 if (verity_is_verity_mode(arg_name)) {
1092                         if (only_modifier_opts)
1093                                 continue;
1094                         r = verity_parse_verity_mode(v, arg_name);
1095                         if (r) {
1096                                 ti->error = "Conflicting error handling parameters";
1097                                 return r;
1098                         }
1099                         continue;
1100
1101                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1102                         if (only_modifier_opts)
1103                                 continue;
1104                         r = verity_alloc_zero_digest(v);
1105                         if (r) {
1106                                 ti->error = "Cannot allocate zero digest";
1107                                 return r;
1108                         }
1109                         continue;
1110
1111                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1112                         if (only_modifier_opts)
1113                                 continue;
1114                         r = verity_alloc_most_once(v);
1115                         if (r)
1116                                 return r;
1117                         continue;
1118
1119                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1120                         v->use_tasklet = true;
1121                         static_branch_inc(&use_tasklet_enabled);
1122                         continue;
1123
1124                 } else if (verity_is_fec_opt_arg(arg_name)) {
1125                         if (only_modifier_opts)
1126                                 continue;
1127                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1128                         if (r)
1129                                 return r;
1130                         continue;
1131
1132                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1133                         if (only_modifier_opts)
1134                                 continue;
1135                         r = verity_verify_sig_parse_opt_args(as, v,
1136                                                              verify_args,
1137                                                              &argc, arg_name);
1138                         if (r)
1139                                 return r;
1140                         continue;
1141
1142                 } else if (only_modifier_opts) {
1143                         /*
1144                          * Ignore unrecognized opt, could easily be an extra
1145                          * argument to an option whose parsing was skipped.
1146                          * Normal parsing (@only_modifier_opts=false) will
1147                          * properly parse all options (and their extra args).
1148                          */
1149                         continue;
1150                 }
1151
1152                 DMERR("Unrecognized verity feature request: %s", arg_name);
1153                 ti->error = "Unrecognized verity feature request";
1154                 return -EINVAL;
1155         } while (argc && !r);
1156
1157         return r;
1158 }
1159
1160 /*
1161  * Target parameters:
1162  *      <version>       The current format is version 1.
1163  *                      Vsn 0 is compatible with original Chromium OS releases.
1164  *      <data device>
1165  *      <hash device>
1166  *      <data block size>
1167  *      <hash block size>
1168  *      <the number of data blocks>
1169  *      <hash start block>
1170  *      <algorithm>
1171  *      <digest>
1172  *      <salt>          Hex string or "-" if no salt.
1173  */
1174 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1175 {
1176         struct dm_verity *v;
1177         struct dm_verity_sig_opts verify_args = {0};
1178         struct dm_arg_set as;
1179         unsigned int num;
1180         unsigned long long num_ll;
1181         int r;
1182         int i;
1183         sector_t hash_position;
1184         char dummy;
1185         char *root_hash_digest_to_validate;
1186
1187         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1188         if (!v) {
1189                 ti->error = "Cannot allocate verity structure";
1190                 return -ENOMEM;
1191         }
1192         ti->private = v;
1193         v->ti = ti;
1194
1195         r = verity_fec_ctr_alloc(v);
1196         if (r)
1197                 goto bad;
1198
1199         if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1200                 ti->error = "Device must be readonly";
1201                 r = -EINVAL;
1202                 goto bad;
1203         }
1204
1205         if (argc < 10) {
1206                 ti->error = "Not enough arguments";
1207                 r = -EINVAL;
1208                 goto bad;
1209         }
1210
1211         /* Parse optional parameters that modify primary args */
1212         if (argc > 10) {
1213                 as.argc = argc - 10;
1214                 as.argv = argv + 10;
1215                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1216                 if (r < 0)
1217                         goto bad;
1218         }
1219
1220         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1221             num > 1) {
1222                 ti->error = "Invalid version";
1223                 r = -EINVAL;
1224                 goto bad;
1225         }
1226         v->version = num;
1227
1228         r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1229         if (r) {
1230                 ti->error = "Data device lookup failed";
1231                 goto bad;
1232         }
1233
1234         r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1235         if (r) {
1236                 ti->error = "Hash device lookup failed";
1237                 goto bad;
1238         }
1239
1240         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1241             !num || (num & (num - 1)) ||
1242             num < bdev_logical_block_size(v->data_dev->bdev) ||
1243             num > PAGE_SIZE) {
1244                 ti->error = "Invalid data device block size";
1245                 r = -EINVAL;
1246                 goto bad;
1247         }
1248         v->data_dev_block_bits = __ffs(num);
1249
1250         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1251             !num || (num & (num - 1)) ||
1252             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1253             num > INT_MAX) {
1254                 ti->error = "Invalid hash device block size";
1255                 r = -EINVAL;
1256                 goto bad;
1257         }
1258         v->hash_dev_block_bits = __ffs(num);
1259
1260         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1261             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1262             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1263                 ti->error = "Invalid data blocks";
1264                 r = -EINVAL;
1265                 goto bad;
1266         }
1267         v->data_blocks = num_ll;
1268
1269         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1270                 ti->error = "Data device is too small";
1271                 r = -EINVAL;
1272                 goto bad;
1273         }
1274
1275         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1276             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1277             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1278                 ti->error = "Invalid hash start";
1279                 r = -EINVAL;
1280                 goto bad;
1281         }
1282         v->hash_start = num_ll;
1283
1284         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1285         if (!v->alg_name) {
1286                 ti->error = "Cannot allocate algorithm name";
1287                 r = -ENOMEM;
1288                 goto bad;
1289         }
1290
1291         v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1292                                     v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1293         if (IS_ERR(v->tfm)) {
1294                 ti->error = "Cannot initialize hash function";
1295                 r = PTR_ERR(v->tfm);
1296                 v->tfm = NULL;
1297                 goto bad;
1298         }
1299
1300         /*
1301          * dm-verity performance can vary greatly depending on which hash
1302          * algorithm implementation is used.  Help people debug performance
1303          * problems by logging the ->cra_driver_name.
1304          */
1305         DMINFO("%s using implementation \"%s\"", v->alg_name,
1306                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1307
1308         v->digest_size = crypto_ahash_digestsize(v->tfm);
1309         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1310                 ti->error = "Digest size too big";
1311                 r = -EINVAL;
1312                 goto bad;
1313         }
1314         v->ahash_reqsize = sizeof(struct ahash_request) +
1315                 crypto_ahash_reqsize(v->tfm);
1316
1317         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1318         if (!v->root_digest) {
1319                 ti->error = "Cannot allocate root digest";
1320                 r = -ENOMEM;
1321                 goto bad;
1322         }
1323         if (strlen(argv[8]) != v->digest_size * 2 ||
1324             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1325                 ti->error = "Invalid root digest";
1326                 r = -EINVAL;
1327                 goto bad;
1328         }
1329         root_hash_digest_to_validate = argv[8];
1330
1331         if (strcmp(argv[9], "-")) {
1332                 v->salt_size = strlen(argv[9]) / 2;
1333                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1334                 if (!v->salt) {
1335                         ti->error = "Cannot allocate salt";
1336                         r = -ENOMEM;
1337                         goto bad;
1338                 }
1339                 if (strlen(argv[9]) != v->salt_size * 2 ||
1340                     hex2bin(v->salt, argv[9], v->salt_size)) {
1341                         ti->error = "Invalid salt";
1342                         r = -EINVAL;
1343                         goto bad;
1344                 }
1345         }
1346
1347         argv += 10;
1348         argc -= 10;
1349
1350         /* Optional parameters */
1351         if (argc) {
1352                 as.argc = argc;
1353                 as.argv = argv;
1354                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1355                 if (r < 0)
1356                         goto bad;
1357         }
1358
1359         /* Root hash signature is  a optional parameter*/
1360         r = verity_verify_root_hash(root_hash_digest_to_validate,
1361                                     strlen(root_hash_digest_to_validate),
1362                                     verify_args.sig,
1363                                     verify_args.sig_size);
1364         if (r < 0) {
1365                 ti->error = "Root hash verification failed";
1366                 goto bad;
1367         }
1368         v->hash_per_block_bits =
1369                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1370
1371         v->levels = 0;
1372         if (v->data_blocks)
1373                 while (v->hash_per_block_bits * v->levels < 64 &&
1374                        (unsigned long long)(v->data_blocks - 1) >>
1375                        (v->hash_per_block_bits * v->levels))
1376                         v->levels++;
1377
1378         if (v->levels > DM_VERITY_MAX_LEVELS) {
1379                 ti->error = "Too many tree levels";
1380                 r = -E2BIG;
1381                 goto bad;
1382         }
1383
1384         hash_position = v->hash_start;
1385         for (i = v->levels - 1; i >= 0; i--) {
1386                 sector_t s;
1387
1388                 v->hash_level_block[i] = hash_position;
1389                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1390                                         >> ((i + 1) * v->hash_per_block_bits);
1391                 if (hash_position + s < hash_position) {
1392                         ti->error = "Hash device offset overflow";
1393                         r = -E2BIG;
1394                         goto bad;
1395                 }
1396                 hash_position += s;
1397         }
1398         v->hash_blocks = hash_position;
1399
1400         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1401                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1402                 dm_bufio_alloc_callback, NULL,
1403                 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1404         if (IS_ERR(v->bufio)) {
1405                 ti->error = "Cannot initialize dm-bufio";
1406                 r = PTR_ERR(v->bufio);
1407                 v->bufio = NULL;
1408                 goto bad;
1409         }
1410
1411         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1412                 ti->error = "Hash device is too small";
1413                 r = -E2BIG;
1414                 goto bad;
1415         }
1416
1417         /*
1418          * Using WQ_HIGHPRI improves throughput and completion latency by
1419          * reducing wait times when reading from a dm-verity device.
1420          *
1421          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1422          * allows verify_wq to preempt softirq since verification in tasklet
1423          * will fall-back to using it for error handling (or if the bufio cache
1424          * doesn't have required hashes).
1425          */
1426         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1427         if (!v->verify_wq) {
1428                 ti->error = "Cannot allocate workqueue";
1429                 r = -ENOMEM;
1430                 goto bad;
1431         }
1432
1433         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1434                                 v->ahash_reqsize + v->digest_size * 2;
1435
1436         r = verity_fec_ctr(v);
1437         if (r)
1438                 goto bad;
1439
1440         ti->per_io_data_size = roundup(ti->per_io_data_size,
1441                                        __alignof__(struct dm_verity_io));
1442
1443         verity_verify_sig_opts_cleanup(&verify_args);
1444
1445         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1446
1447         return 0;
1448
1449 bad:
1450
1451         verity_verify_sig_opts_cleanup(&verify_args);
1452         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1453         verity_dtr(ti);
1454
1455         return r;
1456 }
1457
1458 /*
1459  * Check whether a DM target is a verity target.
1460  */
1461 bool dm_is_verity_target(struct dm_target *ti)
1462 {
1463         return ti->type->module == THIS_MODULE;
1464 }
1465
1466 /*
1467  * Get the verity mode (error behavior) of a verity target.
1468  *
1469  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1470  * target.
1471  */
1472 int dm_verity_get_mode(struct dm_target *ti)
1473 {
1474         struct dm_verity *v = ti->private;
1475
1476         if (!dm_is_verity_target(ti))
1477                 return -EINVAL;
1478
1479         return v->mode;
1480 }
1481
1482 /*
1483  * Get the root digest of a verity target.
1484  *
1485  * Returns a copy of the root digest, the caller is responsible for
1486  * freeing the memory of the digest.
1487  */
1488 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1489 {
1490         struct dm_verity *v = ti->private;
1491
1492         if (!dm_is_verity_target(ti))
1493                 return -EINVAL;
1494
1495         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1496         if (*root_digest == NULL)
1497                 return -ENOMEM;
1498
1499         *digest_size = v->digest_size;
1500
1501         return 0;
1502 }
1503
1504 static struct target_type verity_target = {
1505         .name           = "verity",
1506         .features       = DM_TARGET_IMMUTABLE,
1507         .version        = {1, 9, 0},
1508         .module         = THIS_MODULE,
1509         .ctr            = verity_ctr,
1510         .dtr            = verity_dtr,
1511         .map            = verity_map,
1512         .status         = verity_status,
1513         .prepare_ioctl  = verity_prepare_ioctl,
1514         .iterate_devices = verity_iterate_devices,
1515         .io_hints       = verity_io_hints,
1516 };
1517 module_dm(verity);
1518
1519 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1520 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1521 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1522 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1523 MODULE_LICENSE("GPL");