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, bool may_sleep)
 139 {
 140         int r;
 141
 142         ahash_request_set_tfm(req, v->tfm);
 143         ahash_request_set_callback(req,
 144                 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
 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                 if (r != -ENOMEM)
 152                         DMERR("crypto_ahash_init failed: %d", r);
 153                 return r;
 154         }
 155
 156         if (likely(v->salt_size && (v->version >= 1)))
 157                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 158
 159         return r;
 160 }
 161
 162 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
 163                              u8 *digest, struct crypto_wait *wait)
 164 {
 165         int r;
 166
 167         if (unlikely(v->salt_size && (!v->version))) {
 168                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 169
 170                 if (r < 0) {
 171                         DMERR("%s failed updating salt: %d", __func__, r);
 172                         goto out;
 173                 }
 174         }
 175
 176         ahash_request_set_crypt(req, NULL, digest, 0);
 177         r = crypto_wait_req(crypto_ahash_final(req), wait);
 178 out:
 179         return r;
 180 }
 181
 182 int verity_hash(struct dm_verity *v, struct ahash_request *req,
 183                 const u8 *data, size_t len, u8 *digest, bool may_sleep)
 184 {
 185         int r;
 186         struct crypto_wait wait;
 187
 188         r = verity_hash_init(v, req, &wait, may_sleep);
 189         if (unlikely(r < 0))
 190                 goto out;
 191
 192         r = verity_hash_update(v, req, data, len, &wait);
 193         if (unlikely(r < 0))
 194                 goto out;
 195
 196         r = verity_hash_final(v, req, digest, &wait);
 197
 198 out:
 199         return r;
 200 }
 201
 202 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 203                                  sector_t *hash_block, unsigned int *offset)
 204 {
 205         sector_t position = verity_position_at_level(v, block, level);
 206         unsigned int idx;
 207
 208         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 209
 210         if (!offset)
 211                 return;
 212
 213         idx = position & ((1 << v->hash_per_block_bits) - 1);
 214         if (!v->version)
 215                 *offset = idx * v->digest_size;
 216         else
 217                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 218 }
 219
 220 /*
 221  * Handle verification errors.
 222  */
 223 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 224                              unsigned long long block)
 225 {
 226         char verity_env[DM_VERITY_ENV_LENGTH];
 227         char *envp[] = { verity_env, NULL };
 228         const char *type_str = "";
 229         struct mapped_device *md = dm_table_get_md(v->ti->table);
 230
 231         /* Corruption should be visible in device status in all modes */
 232         v->hash_failed = true;
 233
 234         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 235                 goto out;
 236
 237         v->corrupted_errs++;
 238
 239         switch (type) {
 240         case DM_VERITY_BLOCK_TYPE_DATA:
 241                 type_str = "data";
 242                 break;
 243         case DM_VERITY_BLOCK_TYPE_METADATA:
 244                 type_str = "metadata";
 245                 break;
 246         default:
 247                 BUG();
 248         }
 249
 250         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 251                     type_str, block);
 252
 253         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
 254                 DMERR("%s: reached maximum errors", v->data_dev->name);
 255                 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
 256         }
 257
 258         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 259                 DM_VERITY_ENV_VAR_NAME, type, block);
 260
 261         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 262
 263 out:
 264         if (v->mode == DM_VERITY_MODE_LOGGING)
 265                 return 0;
 266
 267         if (v->mode == DM_VERITY_MODE_RESTART)
 268                 kernel_restart("dm-verity device corrupted");
 269
 270         if (v->mode == DM_VERITY_MODE_PANIC)
 271                 panic("dm-verity device corrupted");
 272
 273         return 1;
 274 }
 275
 276 /*
 277  * Verify hash of a metadata block pertaining to the specified data block
 278  * ("block" argument) at a specified level ("level" argument).
 279  *
 280  * On successful return, verity_io_want_digest(v, io) contains the hash value
 281  * for a lower tree level or for the data block (if we're at the lowest level).
 282  *
 283  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 284  * If "skip_unverified" is false, unverified buffer is hashed and verified
 285  * against current value of verity_io_want_digest(v, io).
 286  */
 287 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 288                                sector_t block, int level, bool skip_unverified,
 289                                u8 *want_digest)
 290 {
 291         struct dm_buffer *buf;
 292         struct buffer_aux *aux;
 293         u8 *data;
 294         int r;
 295         sector_t hash_block;
 296         unsigned int offset;
 297
 298         verity_hash_at_level(v, block, level, &hash_block, &offset);
 299
 300         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 301                 data = dm_bufio_get(v->bufio, hash_block, &buf);
 302                 if (data == NULL) {
 303                         /*
 304                          * In tasklet and the hash was not in the bufio cache.
 305                          * Return early and resume execution from a work-queue
 306                          * to read the hash from disk.
 307                          */
 308                         return -EAGAIN;
 309                 }
 310         } else
 311                 data = dm_bufio_read(v->bufio, hash_block, &buf);
 312
 313         if (IS_ERR(data))
 314                 return PTR_ERR(data);
 315
 316         aux = dm_bufio_get_aux_data(buf);
 317
 318         if (!aux->hash_verified) {
 319                 if (skip_unverified) {
 320                         r = 1;
 321                         goto release_ret_r;
 322                 }
 323
 324                 r = verity_hash(v, verity_io_hash_req(v, io),
 325                                 data, 1 << v->hash_dev_block_bits,
 326                                 verity_io_real_digest(v, io), !io->in_tasklet);
 327                 if (unlikely(r < 0))
 328                         goto release_ret_r;
 329
 330                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 331                                   v->digest_size) == 0))
 332                         aux->hash_verified = 1;
 333                 else if (static_branch_unlikely(&use_tasklet_enabled) &&
 334                          io->in_tasklet) {
 335                         /*
 336                          * Error handling code (FEC included) cannot be run in a
 337                          * tasklet since it may sleep, so fallback to work-queue.
 338                          */
 339                         r = -EAGAIN;
 340                         goto release_ret_r;
 341                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 342                                              hash_block, data, NULL) == 0)
 343                         aux->hash_verified = 1;
 344                 else if (verity_handle_err(v,
 345                                            DM_VERITY_BLOCK_TYPE_METADATA,
 346                                            hash_block)) {
 347                         struct bio *bio =
 348                                 dm_bio_from_per_bio_data(io,
 349                                                          v->ti->per_io_data_size);
 350                         dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
 351                                          block, 0);
 352                         r = -EIO;
 353                         goto release_ret_r;
 354                 }
 355         }
 356
 357         data += offset;
 358         memcpy(want_digest, data, v->digest_size);
 359         r = 0;
 360
 361 release_ret_r:
 362         dm_bufio_release(buf);
 363         return r;
 364 }
 365
 366 /*
 367  * Find a hash for a given block, write it to digest and verify the integrity
 368  * of the hash tree if necessary.
 369  */
 370 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 371                           sector_t block, u8 *digest, bool *is_zero)
 372 {
 373         int r = 0, i;
 374
 375         if (likely(v->levels)) {
 376                 /*
 377                  * First, we try to get the requested hash for
 378                  * the current block. If the hash block itself is
 379                  * verified, zero is returned. If it isn't, this
 380                  * function returns 1 and we fall back to whole
 381                  * chain verification.
 382                  */
 383                 r = verity_verify_level(v, io, block, 0, true, digest);
 384                 if (likely(r <= 0))
 385                         goto out;
 386         }
 387
 388         memcpy(digest, v->root_digest, v->digest_size);
 389
 390         for (i = v->levels - 1; i >= 0; i--) {
 391                 r = verity_verify_level(v, io, block, i, false, digest);
 392                 if (unlikely(r))
 393                         goto out;
 394         }
 395 out:
 396         if (!r && v->zero_digest)
 397                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 398         else
 399                 *is_zero = false;
 400
 401         return r;
 402 }
 403
 404 /*
 405  * Calculates the digest for the given bio
 406  */
 407 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
 408                                struct bvec_iter *iter, struct crypto_wait *wait)
 409 {
 410         unsigned int todo = 1 << v->data_dev_block_bits;
 411         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 412         struct scatterlist sg;
 413         struct ahash_request *req = verity_io_hash_req(v, io);
 414
 415         do {
 416                 int r;
 417                 unsigned int len;
 418                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 419
 420                 sg_init_table(&sg, 1);
 421
 422                 len = bv.bv_len;
 423
 424                 if (likely(len >= todo))
 425                         len = todo;
 426                 /*
 427                  * Operating on a single page at a time looks suboptimal
 428                  * until you consider the typical block size is 4,096B.
 429                  * Going through this loops twice should be very rare.
 430                  */
 431                 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
 432                 ahash_request_set_crypt(req, &sg, NULL, len);
 433                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 434
 435                 if (unlikely(r < 0)) {
 436                         DMERR("%s crypto op failed: %d", __func__, r);
 437                         return r;
 438                 }
 439
 440                 bio_advance_iter(bio, iter, len);
 441                 todo -= len;
 442         } while (todo);
 443
 444         return 0;
 445 }
 446
 447 /*
 448  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
 449  * starting from iter.
 450  */
 451 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 452                         struct bvec_iter *iter,
 453                         int (*process)(struct dm_verity *v,
 454                                        struct dm_verity_io *io, u8 *data,
 455                                        size_t len))
 456 {
 457         unsigned int todo = 1 << v->data_dev_block_bits;
 458         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 459
 460         do {
 461                 int r;
 462                 u8 *page;
 463                 unsigned int len;
 464                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 465
 466                 page = bvec_kmap_local(&bv);
 467                 len = bv.bv_len;
 468
 469                 if (likely(len >= todo))
 470                         len = todo;
 471
 472                 r = process(v, io, page, len);
 473                 kunmap_local(page);
 474
 475                 if (r < 0)
 476                         return r;
 477
 478                 bio_advance_iter(bio, iter, len);
 479                 todo -= len;
 480         } while (todo);
 481
 482         return 0;
 483 }
 484
 485 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 486                           u8 *data, size_t len)
 487 {
 488         memset(data, 0, len);
 489         return 0;
 490 }
 491
 492 /*
 493  * Moves the bio iter one data block forward.
 494  */
 495 static inline void verity_bv_skip_block(struct dm_verity *v,
 496                                         struct dm_verity_io *io,
 497                                         struct bvec_iter *iter)
 498 {
 499         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 500
 501         bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
 502 }
 503
 504 /*
 505  * Verify one "dm_verity_io" structure.
 506  */
 507 static int verity_verify_io(struct dm_verity_io *io)
 508 {
 509         bool is_zero;
 510         struct dm_verity *v = io->v;
 511 #if defined(CONFIG_DM_VERITY_FEC)
 512         struct bvec_iter start;
 513 #endif
 514         struct bvec_iter iter_copy;
 515         struct bvec_iter *iter;
 516         struct crypto_wait wait;
 517         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 518         unsigned int b;
 519
 520         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 521                 /*
 522                  * Copy the iterator in case we need to restart
 523                  * verification in a work-queue.
 524                  */
 525                 iter_copy = io->iter;
 526                 iter = &iter_copy;
 527         } else
 528                 iter = &io->iter;
 529
 530         for (b = 0; b < io->n_blocks; b++) {
 531                 int r;
 532                 sector_t cur_block = io->block + b;
 533                 struct ahash_request *req = verity_io_hash_req(v, io);
 534
 535                 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 536                     likely(test_bit(cur_block, v->validated_blocks))) {
 537                         verity_bv_skip_block(v, io, iter);
 538                         continue;
 539                 }
 540
 541                 r = verity_hash_for_block(v, io, cur_block,
 542                                           verity_io_want_digest(v, io),
 543                                           &is_zero);
 544                 if (unlikely(r < 0))
 545                         return r;
 546
 547                 if (is_zero) {
 548                         /*
 549                          * If we expect a zero block, don't validate, just
 550                          * return zeros.
 551                          */
 552                         r = verity_for_bv_block(v, io, iter,
 553                                                 verity_bv_zero);
 554                         if (unlikely(r < 0))
 555                                 return r;
 556
 557                         continue;
 558                 }
 559
 560                 r = verity_hash_init(v, req, &wait, !io->in_tasklet);
 561                 if (unlikely(r < 0))
 562                         return r;
 563
 564 #if defined(CONFIG_DM_VERITY_FEC)
 565                 if (verity_fec_is_enabled(v))
 566                         start = *iter;
 567 #endif
 568                 r = verity_for_io_block(v, io, iter, &wait);
 569                 if (unlikely(r < 0))
 570                         return r;
 571
 572                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 573                                         &wait);
 574                 if (unlikely(r < 0))
 575                         return r;
 576
 577                 if (likely(memcmp(verity_io_real_digest(v, io),
 578                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 579                         if (v->validated_blocks)
 580                                 set_bit(cur_block, v->validated_blocks);
 581                         continue;
 582                 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
 583                            io->in_tasklet) {
 584                         /*
 585                          * Error handling code (FEC included) cannot be run in a
 586                          * tasklet since it may sleep, so fallback to work-queue.
 587                          */
 588                         return -EAGAIN;
 589 #if defined(CONFIG_DM_VERITY_FEC)
 590                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 591                                              cur_block, NULL, &start) == 0) {
 592                         continue;
 593 #endif
 594                 } else {
 595                         if (bio->bi_status) {
 596                                 /*
 597                                  * Error correction failed; Just return error
 598                                  */
 599                                 return -EIO;
 600                         }
 601                         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 602                                               cur_block)) {
 603                                 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
 604                                                  bio, cur_block, 0);
 605                                 return -EIO;
 606                         }
 607                 }
 608         }
 609
 610         return 0;
 611 }
 612
 613 /*
 614  * Skip verity work in response to I/O error when system is shutting down.
 615  */
 616 static inline bool verity_is_system_shutting_down(void)
 617 {
 618         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 619                 || system_state == SYSTEM_RESTART;
 620 }
 621
 622 /*
 623  * End one "io" structure with a given error.
 624  */
 625 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 626 {
 627         struct dm_verity *v = io->v;
 628         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 629
 630         bio->bi_end_io = io->orig_bi_end_io;
 631         bio->bi_status = status;
 632
 633         if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
 634                 verity_fec_finish_io(io);
 635
 636         bio_endio(bio);
 637 }
 638
 639 static void verity_work(struct work_struct *w)
 640 {
 641         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 642
 643         io->in_tasklet = false;
 644
 645         verity_fec_init_io(io);
 646         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 647 }
 648
 649 static void verity_tasklet(unsigned long data)
 650 {
 651         struct dm_verity_io *io = (struct dm_verity_io *)data;
 652         int err;
 653
 654         io->in_tasklet = true;
 655         err = verity_verify_io(io);
 656         if (err == -EAGAIN || err == -ENOMEM) {
 657                 /* fallback to retrying with work-queue */
 658                 INIT_WORK(&io->work, verity_work);
 659                 queue_work(io->v->verify_wq, &io->work);
 660                 return;
 661         }
 662
 663         verity_finish_io(io, errno_to_blk_status(err));
 664 }
 665
 666 static void verity_end_io(struct bio *bio)
 667 {
 668         struct dm_verity_io *io = bio->bi_private;
 669
 670         if (bio->bi_status &&
 671             (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
 672                 verity_finish_io(io, bio->bi_status);
 673                 return;
 674         }
 675
 676         if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
 677                 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
 678                 tasklet_schedule(&io->tasklet);
 679         } else {
 680                 INIT_WORK(&io->work, verity_work);
 681                 queue_work(io->v->verify_wq, &io->work);
 682         }
 683 }
 684
 685 /*
 686  * Prefetch buffers for the specified io.
 687  * The root buffer is not prefetched, it is assumed that it will be cached
 688  * all the time.
 689  */
 690 static void verity_prefetch_io(struct work_struct *work)
 691 {
 692         struct dm_verity_prefetch_work *pw =
 693                 container_of(work, struct dm_verity_prefetch_work, work);
 694         struct dm_verity *v = pw->v;
 695         int i;
 696
 697         for (i = v->levels - 2; i >= 0; i--) {
 698                 sector_t hash_block_start;
 699                 sector_t hash_block_end;
 700
 701                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 702                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 703
 704                 if (!i) {
 705                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 706
 707                         cluster >>= v->data_dev_block_bits;
 708                         if (unlikely(!cluster))
 709                                 goto no_prefetch_cluster;
 710
 711                         if (unlikely(cluster & (cluster - 1)))
 712                                 cluster = 1 << __fls(cluster);
 713
 714                         hash_block_start &= ~(sector_t)(cluster - 1);
 715                         hash_block_end |= cluster - 1;
 716                         if (unlikely(hash_block_end >= v->hash_blocks))
 717                                 hash_block_end = v->hash_blocks - 1;
 718                 }
 719 no_prefetch_cluster:
 720                 dm_bufio_prefetch(v->bufio, hash_block_start,
 721                                   hash_block_end - hash_block_start + 1);
 722         }
 723
 724         kfree(pw);
 725 }
 726
 727 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 728 {
 729         sector_t block = io->block;
 730         unsigned int n_blocks = io->n_blocks;
 731         struct dm_verity_prefetch_work *pw;
 732
 733         if (v->validated_blocks) {
 734                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 735                         block++;
 736                         n_blocks--;
 737                 }
 738                 while (n_blocks && test_bit(block + n_blocks - 1,
 739                                             v->validated_blocks))
 740                         n_blocks--;
 741                 if (!n_blocks)
 742                         return;
 743         }
 744
 745         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 746                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 747
 748         if (!pw)
 749                 return;
 750
 751         INIT_WORK(&pw->work, verity_prefetch_io);
 752         pw->v = v;
 753         pw->block = block;
 754         pw->n_blocks = n_blocks;
 755         queue_work(v->verify_wq, &pw->work);
 756 }
 757
 758 /*
 759  * Bio map function. It allocates dm_verity_io structure and bio vector and
 760  * fills them. Then it issues prefetches and the I/O.
 761  */
 762 static int verity_map(struct dm_target *ti, struct bio *bio)
 763 {
 764         struct dm_verity *v = ti->private;
 765         struct dm_verity_io *io;
 766
 767         bio_set_dev(bio, v->data_dev->bdev);
 768         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 769
 770         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 771             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 772                 DMERR_LIMIT("unaligned io");
 773                 return DM_MAPIO_KILL;
 774         }
 775
 776         if (bio_end_sector(bio) >>
 777             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 778                 DMERR_LIMIT("io out of range");
 779                 return DM_MAPIO_KILL;
 780         }
 781
 782         if (bio_data_dir(bio) == WRITE)
 783                 return DM_MAPIO_KILL;
 784
 785         io = dm_per_bio_data(bio, ti->per_io_data_size);
 786         io->v = v;
 787         io->orig_bi_end_io = bio->bi_end_io;
 788         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 789         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 790
 791         bio->bi_end_io = verity_end_io;
 792         bio->bi_private = io;
 793         io->iter = bio->bi_iter;
 794
 795         verity_submit_prefetch(v, io);
 796
 797         submit_bio_noacct(bio);
 798
 799         return DM_MAPIO_SUBMITTED;
 800 }
 801
 802 /*
 803  * Status: V (valid) or C (corruption found)
 804  */
 805 static void verity_status(struct dm_target *ti, status_type_t type,
 806                           unsigned int status_flags, char *result, unsigned int maxlen)
 807 {
 808         struct dm_verity *v = ti->private;
 809         unsigned int args = 0;
 810         unsigned int sz = 0;
 811         unsigned int x;
 812
 813         switch (type) {
 814         case STATUSTYPE_INFO:
 815                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 816                 break;
 817         case STATUSTYPE_TABLE:
 818                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 819                         v->version,
 820                         v->data_dev->name,
 821                         v->hash_dev->name,
 822                         1 << v->data_dev_block_bits,
 823                         1 << v->hash_dev_block_bits,
 824                         (unsigned long long)v->data_blocks,
 825                         (unsigned long long)v->hash_start,
 826                         v->alg_name
 827                         );
 828                 for (x = 0; x < v->digest_size; x++)
 829                         DMEMIT("%02x", v->root_digest[x]);
 830                 DMEMIT(" ");
 831                 if (!v->salt_size)
 832                         DMEMIT("-");
 833                 else
 834                         for (x = 0; x < v->salt_size; x++)
 835                                 DMEMIT("%02x", v->salt[x]);
 836                 if (v->mode != DM_VERITY_MODE_EIO)
 837                         args++;
 838                 if (verity_fec_is_enabled(v))
 839                         args += DM_VERITY_OPTS_FEC;
 840                 if (v->zero_digest)
 841                         args++;
 842                 if (v->validated_blocks)
 843                         args++;
 844                 if (v->use_tasklet)
 845                         args++;
 846                 if (v->signature_key_desc)
 847                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 848                 if (!args)
 849                         return;
 850                 DMEMIT(" %u", args);
 851                 if (v->mode != DM_VERITY_MODE_EIO) {
 852                         DMEMIT(" ");
 853                         switch (v->mode) {
 854                         case DM_VERITY_MODE_LOGGING:
 855                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 856                                 break;
 857                         case DM_VERITY_MODE_RESTART:
 858                                 DMEMIT(DM_VERITY_OPT_RESTART);
 859                                 break;
 860                         case DM_VERITY_MODE_PANIC:
 861                                 DMEMIT(DM_VERITY_OPT_PANIC);
 862                                 break;
 863                         default:
 864                                 BUG();
 865                         }
 866                 }
 867                 if (v->zero_digest)
 868                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 869                 if (v->validated_blocks)
 870                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 871                 if (v->use_tasklet)
 872                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 873                 sz = verity_fec_status_table(v, sz, result, maxlen);
 874                 if (v->signature_key_desc)
 875                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 876                                 " %s", v->signature_key_desc);
 877                 break;
 878
 879         case STATUSTYPE_IMA:
 880                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 881                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 882                 DMEMIT(",verity_version=%u", v->version);
 883                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 884                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 885                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 886
 887                 DMEMIT(",root_digest=");
 888                 for (x = 0; x < v->digest_size; x++)
 889                         DMEMIT("%02x", v->root_digest[x]);
 890
 891                 DMEMIT(",salt=");
 892                 if (!v->salt_size)
 893                         DMEMIT("-");
 894                 else
 895                         for (x = 0; x < v->salt_size; x++)
 896                                 DMEMIT("%02x", v->salt[x]);
 897
 898                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 899                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 900                 if (v->signature_key_desc)
 901                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 902
 903                 if (v->mode != DM_VERITY_MODE_EIO) {
 904                         DMEMIT(",verity_mode=");
 905                         switch (v->mode) {
 906                         case DM_VERITY_MODE_LOGGING:
 907                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 908                                 break;
 909                         case DM_VERITY_MODE_RESTART:
 910                                 DMEMIT(DM_VERITY_OPT_RESTART);
 911                                 break;
 912                         case DM_VERITY_MODE_PANIC:
 913                                 DMEMIT(DM_VERITY_OPT_PANIC);
 914                                 break;
 915                         default:
 916                                 DMEMIT("invalid");
 917                         }
 918                 }
 919                 DMEMIT(";");
 920                 break;
 921         }
 922 }
 923
 924 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 925 {
 926         struct dm_verity *v = ti->private;
 927
 928         *bdev = v->data_dev->bdev;
 929
 930         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 931                 return 1;
 932         return 0;
 933 }
 934
 935 static int verity_iterate_devices(struct dm_target *ti,
 936                                   iterate_devices_callout_fn fn, void *data)
 937 {
 938         struct dm_verity *v = ti->private;
 939
 940         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 941 }
 942
 943 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 944 {
 945         struct dm_verity *v = ti->private;
 946
 947         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 948                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 949
 950         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 951                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 952
 953         blk_limits_io_min(limits, limits->logical_block_size);
 954 }
 955
 956 static void verity_dtr(struct dm_target *ti)
 957 {
 958         struct dm_verity *v = ti->private;
 959
 960         if (v->verify_wq)
 961                 destroy_workqueue(v->verify_wq);
 962
 963         if (v->bufio)
 964                 dm_bufio_client_destroy(v->bufio);
 965
 966         kvfree(v->validated_blocks);
 967         kfree(v->salt);
 968         kfree(v->root_digest);
 969         kfree(v->zero_digest);
 970
 971         if (v->tfm)
 972                 crypto_free_ahash(v->tfm);
 973
 974         kfree(v->alg_name);
 975
 976         if (v->hash_dev)
 977                 dm_put_device(ti, v->hash_dev);
 978
 979         if (v->data_dev)
 980                 dm_put_device(ti, v->data_dev);
 981
 982         verity_fec_dtr(v);
 983
 984         kfree(v->signature_key_desc);
 985
 986         if (v->use_tasklet)
 987                 static_branch_dec(&use_tasklet_enabled);
 988
 989         kfree(v);
 990
 991         dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
 992 }
 993
 994 static int verity_alloc_most_once(struct dm_verity *v)
 995 {
 996         struct dm_target *ti = v->ti;
 997
 998         /* the bitset can only handle INT_MAX blocks */
 999         if (v->data_blocks > INT_MAX) {
1000                 ti->error = "device too large to use check_at_most_once";
1001                 return -E2BIG;
1002         }
1003
1004         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1005                                        sizeof(unsigned long),
1006                                        GFP_KERNEL);
1007         if (!v->validated_blocks) {
1008                 ti->error = "failed to allocate bitset for check_at_most_once";
1009                 return -ENOMEM;
1010         }
1011
1012         return 0;
1013 }
1014
1015 static int verity_alloc_zero_digest(struct dm_verity *v)
1016 {
1017         int r = -ENOMEM;
1018         struct ahash_request *req;
1019         u8 *zero_data;
1020
1021         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1022
1023         if (!v->zero_digest)
1024                 return r;
1025
1026         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1027
1028         if (!req)
1029                 return r; /* verity_dtr will free zero_digest */
1030
1031         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1032
1033         if (!zero_data)
1034                 goto out;
1035
1036         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1037                         v->zero_digest, true);
1038
1039 out:
1040         kfree(req);
1041         kfree(zero_data);
1042
1043         return r;
1044 }
1045
1046 static inline bool verity_is_verity_mode(const char *arg_name)
1047 {
1048         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1049                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1050                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1051 }
1052
1053 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1054 {
1055         if (v->mode)
1056                 return -EINVAL;
1057
1058         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1059                 v->mode = DM_VERITY_MODE_LOGGING;
1060         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1061                 v->mode = DM_VERITY_MODE_RESTART;
1062         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1063                 v->mode = DM_VERITY_MODE_PANIC;
1064
1065         return 0;
1066 }
1067
1068 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1069                                  struct dm_verity_sig_opts *verify_args,
1070                                  bool only_modifier_opts)
1071 {
1072         int r = 0;
1073         unsigned int argc;
1074         struct dm_target *ti = v->ti;
1075         const char *arg_name;
1076
1077         static const struct dm_arg _args[] = {
1078                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1079         };
1080
1081         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1082         if (r)
1083                 return -EINVAL;
1084
1085         if (!argc)
1086                 return 0;
1087
1088         do {
1089                 arg_name = dm_shift_arg(as);
1090                 argc--;
1091
1092                 if (verity_is_verity_mode(arg_name)) {
1093                         if (only_modifier_opts)
1094                                 continue;
1095                         r = verity_parse_verity_mode(v, arg_name);
1096                         if (r) {
1097                                 ti->error = "Conflicting error handling parameters";
1098                                 return r;
1099                         }
1100                         continue;
1101
1102                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1103                         if (only_modifier_opts)
1104                                 continue;
1105                         r = verity_alloc_zero_digest(v);
1106                         if (r) {
1107                                 ti->error = "Cannot allocate zero digest";
1108                                 return r;
1109                         }
1110                         continue;
1111
1112                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1113                         if (only_modifier_opts)
1114                                 continue;
1115                         r = verity_alloc_most_once(v);
1116                         if (r)
1117                                 return r;
1118                         continue;
1119
1120                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1121                         v->use_tasklet = true;
1122                         static_branch_inc(&use_tasklet_enabled);
1123                         continue;
1124
1125                 } else if (verity_is_fec_opt_arg(arg_name)) {
1126                         if (only_modifier_opts)
1127                                 continue;
1128                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1129                         if (r)
1130                                 return r;
1131                         continue;
1132
1133                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1134                         if (only_modifier_opts)
1135                                 continue;
1136                         r = verity_verify_sig_parse_opt_args(as, v,
1137                                                              verify_args,
1138                                                              &argc, arg_name);
1139                         if (r)
1140                                 return r;
1141                         continue;
1142
1143                 } else if (only_modifier_opts) {
1144                         /*
1145                          * Ignore unrecognized opt, could easily be an extra
1146                          * argument to an option whose parsing was skipped.
1147                          * Normal parsing (@only_modifier_opts=false) will
1148                          * properly parse all options (and their extra args).
1149                          */
1150                         continue;
1151                 }
1152
1153                 DMERR("Unrecognized verity feature request: %s", arg_name);
1154                 ti->error = "Unrecognized verity feature request";
1155                 return -EINVAL;
1156         } while (argc && !r);
1157
1158         return r;
1159 }
1160
1161 /*
1162  * Target parameters:
1163  *      <version>       The current format is version 1.
1164  *                      Vsn 0 is compatible with original Chromium OS releases.
1165  *      <data device>
1166  *      <hash device>
1167  *      <data block size>
1168  *      <hash block size>
1169  *      <the number of data blocks>
1170  *      <hash start block>
1171  *      <algorithm>
1172  *      <digest>
1173  *      <salt>          Hex string or "-" if no salt.
1174  */
1175 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1176 {
1177         struct dm_verity *v;
1178         struct dm_verity_sig_opts verify_args = {0};
1179         struct dm_arg_set as;
1180         unsigned int num;
1181         unsigned long long num_ll;
1182         int r;
1183         int i;
1184         sector_t hash_position;
1185         char dummy;
1186         char *root_hash_digest_to_validate;
1187
1188         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1189         if (!v) {
1190                 ti->error = "Cannot allocate verity structure";
1191                 return -ENOMEM;
1192         }
1193         ti->private = v;
1194         v->ti = ti;
1195
1196         r = verity_fec_ctr_alloc(v);
1197         if (r)
1198                 goto bad;
1199
1200         if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1201                 ti->error = "Device must be readonly";
1202                 r = -EINVAL;
1203                 goto bad;
1204         }
1205
1206         if (argc < 10) {
1207                 ti->error = "Not enough arguments";
1208                 r = -EINVAL;
1209                 goto bad;
1210         }
1211
1212         /* Parse optional parameters that modify primary args */
1213         if (argc > 10) {
1214                 as.argc = argc - 10;
1215                 as.argv = argv + 10;
1216                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1217                 if (r < 0)
1218                         goto bad;
1219         }
1220
1221         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1222             num > 1) {
1223                 ti->error = "Invalid version";
1224                 r = -EINVAL;
1225                 goto bad;
1226         }
1227         v->version = num;
1228
1229         r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1230         if (r) {
1231                 ti->error = "Data device lookup failed";
1232                 goto bad;
1233         }
1234
1235         r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1236         if (r) {
1237                 ti->error = "Hash device lookup failed";
1238                 goto bad;
1239         }
1240
1241         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1242             !num || (num & (num - 1)) ||
1243             num < bdev_logical_block_size(v->data_dev->bdev) ||
1244             num > PAGE_SIZE) {
1245                 ti->error = "Invalid data device block size";
1246                 r = -EINVAL;
1247                 goto bad;
1248         }
1249         v->data_dev_block_bits = __ffs(num);
1250
1251         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1252             !num || (num & (num - 1)) ||
1253             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1254             num > INT_MAX) {
1255                 ti->error = "Invalid hash device block size";
1256                 r = -EINVAL;
1257                 goto bad;
1258         }
1259         v->hash_dev_block_bits = __ffs(num);
1260
1261         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1262             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1263             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1264                 ti->error = "Invalid data blocks";
1265                 r = -EINVAL;
1266                 goto bad;
1267         }
1268         v->data_blocks = num_ll;
1269
1270         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1271                 ti->error = "Data device is too small";
1272                 r = -EINVAL;
1273                 goto bad;
1274         }
1275
1276         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1277             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1278             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1279                 ti->error = "Invalid hash start";
1280                 r = -EINVAL;
1281                 goto bad;
1282         }
1283         v->hash_start = num_ll;
1284
1285         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1286         if (!v->alg_name) {
1287                 ti->error = "Cannot allocate algorithm name";
1288                 r = -ENOMEM;
1289                 goto bad;
1290         }
1291
1292         v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1293                                     v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1294         if (IS_ERR(v->tfm)) {
1295                 ti->error = "Cannot initialize hash function";
1296                 r = PTR_ERR(v->tfm);
1297                 v->tfm = NULL;
1298                 goto bad;
1299         }
1300
1301         /*
1302          * dm-verity performance can vary greatly depending on which hash
1303          * algorithm implementation is used.  Help people debug performance
1304          * problems by logging the ->cra_driver_name.
1305          */
1306         DMINFO("%s using implementation \"%s\"", v->alg_name,
1307                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1308
1309         v->digest_size = crypto_ahash_digestsize(v->tfm);
1310         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1311                 ti->error = "Digest size too big";
1312                 r = -EINVAL;
1313                 goto bad;
1314         }
1315         v->ahash_reqsize = sizeof(struct ahash_request) +
1316                 crypto_ahash_reqsize(v->tfm);
1317
1318         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1319         if (!v->root_digest) {
1320                 ti->error = "Cannot allocate root digest";
1321                 r = -ENOMEM;
1322                 goto bad;
1323         }
1324         if (strlen(argv[8]) != v->digest_size * 2 ||
1325             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1326                 ti->error = "Invalid root digest";
1327                 r = -EINVAL;
1328                 goto bad;
1329         }
1330         root_hash_digest_to_validate = argv[8];
1331
1332         if (strcmp(argv[9], "-")) {
1333                 v->salt_size = strlen(argv[9]) / 2;
1334                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1335                 if (!v->salt) {
1336                         ti->error = "Cannot allocate salt";
1337                         r = -ENOMEM;
1338                         goto bad;
1339                 }
1340                 if (strlen(argv[9]) != v->salt_size * 2 ||
1341                     hex2bin(v->salt, argv[9], v->salt_size)) {
1342                         ti->error = "Invalid salt";
1343                         r = -EINVAL;
1344                         goto bad;
1345                 }
1346         }
1347
1348         argv += 10;
1349         argc -= 10;
1350
1351         /* Optional parameters */
1352         if (argc) {
1353                 as.argc = argc;
1354                 as.argv = argv;
1355                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1356                 if (r < 0)
1357                         goto bad;
1358         }
1359
1360         /* Root hash signature is  a optional parameter*/
1361         r = verity_verify_root_hash(root_hash_digest_to_validate,
1362                                     strlen(root_hash_digest_to_validate),
1363                                     verify_args.sig,
1364                                     verify_args.sig_size);
1365         if (r < 0) {
1366                 ti->error = "Root hash verification failed";
1367                 goto bad;
1368         }
1369         v->hash_per_block_bits =
1370                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1371
1372         v->levels = 0;
1373         if (v->data_blocks)
1374                 while (v->hash_per_block_bits * v->levels < 64 &&
1375                        (unsigned long long)(v->data_blocks - 1) >>
1376                        (v->hash_per_block_bits * v->levels))
1377                         v->levels++;
1378
1379         if (v->levels > DM_VERITY_MAX_LEVELS) {
1380                 ti->error = "Too many tree levels";
1381                 r = -E2BIG;
1382                 goto bad;
1383         }
1384
1385         hash_position = v->hash_start;
1386         for (i = v->levels - 1; i >= 0; i--) {
1387                 sector_t s;
1388
1389                 v->hash_level_block[i] = hash_position;
1390                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1391                                         >> ((i + 1) * v->hash_per_block_bits);
1392                 if (hash_position + s < hash_position) {
1393                         ti->error = "Hash device offset overflow";
1394                         r = -E2BIG;
1395                         goto bad;
1396                 }
1397                 hash_position += s;
1398         }
1399         v->hash_blocks = hash_position;
1400
1401         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1402                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1403                 dm_bufio_alloc_callback, NULL,
1404                 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1405         if (IS_ERR(v->bufio)) {
1406                 ti->error = "Cannot initialize dm-bufio";
1407                 r = PTR_ERR(v->bufio);
1408                 v->bufio = NULL;
1409                 goto bad;
1410         }
1411
1412         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1413                 ti->error = "Hash device is too small";
1414                 r = -E2BIG;
1415                 goto bad;
1416         }
1417
1418         /*
1419          * Using WQ_HIGHPRI improves throughput and completion latency by
1420          * reducing wait times when reading from a dm-verity device.
1421          *
1422          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1423          * allows verify_wq to preempt softirq since verification in tasklet
1424          * will fall-back to using it for error handling (or if the bufio cache
1425          * doesn't have required hashes).
1426          */
1427         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1428         if (!v->verify_wq) {
1429                 ti->error = "Cannot allocate workqueue";
1430                 r = -ENOMEM;
1431                 goto bad;
1432         }
1433
1434         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1435                                 v->ahash_reqsize + v->digest_size * 2;
1436
1437         r = verity_fec_ctr(v);
1438         if (r)
1439                 goto bad;
1440
1441         ti->per_io_data_size = roundup(ti->per_io_data_size,
1442                                        __alignof__(struct dm_verity_io));
1443
1444         verity_verify_sig_opts_cleanup(&verify_args);
1445
1446         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1447
1448         return 0;
1449
1450 bad:
1451
1452         verity_verify_sig_opts_cleanup(&verify_args);
1453         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1454         verity_dtr(ti);
1455
1456         return r;
1457 }
1458
1459 /*
1460  * Check whether a DM target is a verity target.
1461  */
1462 bool dm_is_verity_target(struct dm_target *ti)
1463 {
1464         return ti->type->module == THIS_MODULE;
1465 }
1466
1467 /*
1468  * Get the verity mode (error behavior) of a verity target.
1469  *
1470  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1471  * target.
1472  */
1473 int dm_verity_get_mode(struct dm_target *ti)
1474 {
1475         struct dm_verity *v = ti->private;
1476
1477         if (!dm_is_verity_target(ti))
1478                 return -EINVAL;
1479
1480         return v->mode;
1481 }
1482
1483 /*
1484  * Get the root digest of a verity target.
1485  *
1486  * Returns a copy of the root digest, the caller is responsible for
1487  * freeing the memory of the digest.
1488  */
1489 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1490 {
1491         struct dm_verity *v = ti->private;
1492
1493         if (!dm_is_verity_target(ti))
1494                 return -EINVAL;
1495
1496         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1497         if (*root_digest == NULL)
1498                 return -ENOMEM;
1499
1500         *digest_size = v->digest_size;
1501
1502         return 0;
1503 }
1504
1505 static struct target_type verity_target = {
1506         .name           = "verity",
1507         .features       = DM_TARGET_IMMUTABLE,
1508         .version        = {1, 9, 0},
1509         .module         = THIS_MODULE,
1510         .ctr            = verity_ctr,
1511         .dtr            = verity_dtr,
1512         .map            = verity_map,
1513         .status         = verity_status,
1514         .prepare_ioctl  = verity_prepare_ioctl,
1515         .iterate_devices = verity_iterate_devices,
1516         .io_hints       = verity_io_hints,
1517 };
1518 module_dm(verity);
1519
1520 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1521 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1522 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1523 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1524 MODULE_LICENSE("GPL");