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_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 || err == -ENOMEM) {
 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) ||
 671              verity_is_system_shutting_down() ||
 672              (bio->bi_opf & REQ_RAHEAD))) {
 673                 verity_finish_io(io, bio->bi_status);
 674                 return;
 675         }
 676
 677         if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
 678                 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
 679                 tasklet_schedule(&io->tasklet);
 680         } else {
 681                 INIT_WORK(&io->work, verity_work);
 682                 queue_work(io->v->verify_wq, &io->work);
 683         }
 684 }
 685
 686 /*
 687  * Prefetch buffers for the specified io.
 688  * The root buffer is not prefetched, it is assumed that it will be cached
 689  * all the time.
 690  */
 691 static void verity_prefetch_io(struct work_struct *work)
 692 {
 693         struct dm_verity_prefetch_work *pw =
 694                 container_of(work, struct dm_verity_prefetch_work, work);
 695         struct dm_verity *v = pw->v;
 696         int i;
 697
 698         for (i = v->levels - 2; i >= 0; i--) {
 699                 sector_t hash_block_start;
 700                 sector_t hash_block_end;
 701
 702                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 703                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 704
 705                 if (!i) {
 706                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 707
 708                         cluster >>= v->data_dev_block_bits;
 709                         if (unlikely(!cluster))
 710                                 goto no_prefetch_cluster;
 711
 712                         if (unlikely(cluster & (cluster - 1)))
 713                                 cluster = 1 << __fls(cluster);
 714
 715                         hash_block_start &= ~(sector_t)(cluster - 1);
 716                         hash_block_end |= cluster - 1;
 717                         if (unlikely(hash_block_end >= v->hash_blocks))
 718                                 hash_block_end = v->hash_blocks - 1;
 719                 }
 720 no_prefetch_cluster:
 721                 dm_bufio_prefetch(v->bufio, hash_block_start,
 722                                   hash_block_end - hash_block_start + 1);
 723         }
 724
 725         kfree(pw);
 726 }
 727
 728 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 729 {
 730         sector_t block = io->block;
 731         unsigned int n_blocks = io->n_blocks;
 732         struct dm_verity_prefetch_work *pw;
 733
 734         if (v->validated_blocks) {
 735                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 736                         block++;
 737                         n_blocks--;
 738                 }
 739                 while (n_blocks && test_bit(block + n_blocks - 1,
 740                                             v->validated_blocks))
 741                         n_blocks--;
 742                 if (!n_blocks)
 743                         return;
 744         }
 745
 746         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 747                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 748
 749         if (!pw)
 750                 return;
 751
 752         INIT_WORK(&pw->work, verity_prefetch_io);
 753         pw->v = v;
 754         pw->block = block;
 755         pw->n_blocks = n_blocks;
 756         queue_work(v->verify_wq, &pw->work);
 757 }
 758
 759 /*
 760  * Bio map function. It allocates dm_verity_io structure and bio vector and
 761  * fills them. Then it issues prefetches and the I/O.
 762  */
 763 static int verity_map(struct dm_target *ti, struct bio *bio)
 764 {
 765         struct dm_verity *v = ti->private;
 766         struct dm_verity_io *io;
 767
 768         bio_set_dev(bio, v->data_dev->bdev);
 769         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 770
 771         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 772             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 773                 DMERR_LIMIT("unaligned io");
 774                 return DM_MAPIO_KILL;
 775         }
 776
 777         if (bio_end_sector(bio) >>
 778             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 779                 DMERR_LIMIT("io out of range");
 780                 return DM_MAPIO_KILL;
 781         }
 782
 783         if (bio_data_dir(bio) == WRITE)
 784                 return DM_MAPIO_KILL;
 785
 786         io = dm_per_bio_data(bio, ti->per_io_data_size);
 787         io->v = v;
 788         io->orig_bi_end_io = bio->bi_end_io;
 789         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 790         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 791
 792         bio->bi_end_io = verity_end_io;
 793         bio->bi_private = io;
 794         io->iter = bio->bi_iter;
 795
 796         verity_fec_init_io(io);
 797
 798         verity_submit_prefetch(v, io);
 799
 800         submit_bio_noacct(bio);
 801
 802         return DM_MAPIO_SUBMITTED;
 803 }
 804
 805 /*
 806  * Status: V (valid) or C (corruption found)
 807  */
 808 static void verity_status(struct dm_target *ti, status_type_t type,
 809                           unsigned int status_flags, char *result, unsigned int maxlen)
 810 {
 811         struct dm_verity *v = ti->private;
 812         unsigned int args = 0;
 813         unsigned int sz = 0;
 814         unsigned int x;
 815
 816         switch (type) {
 817         case STATUSTYPE_INFO:
 818                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 819                 break;
 820         case STATUSTYPE_TABLE:
 821                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 822                         v->version,
 823                         v->data_dev->name,
 824                         v->hash_dev->name,
 825                         1 << v->data_dev_block_bits,
 826                         1 << v->hash_dev_block_bits,
 827                         (unsigned long long)v->data_blocks,
 828                         (unsigned long long)v->hash_start,
 829                         v->alg_name
 830                         );
 831                 for (x = 0; x < v->digest_size; x++)
 832                         DMEMIT("%02x", v->root_digest[x]);
 833                 DMEMIT(" ");
 834                 if (!v->salt_size)
 835                         DMEMIT("-");
 836                 else
 837                         for (x = 0; x < v->salt_size; x++)
 838                                 DMEMIT("%02x", v->salt[x]);
 839                 if (v->mode != DM_VERITY_MODE_EIO)
 840                         args++;
 841                 if (verity_fec_is_enabled(v))
 842                         args += DM_VERITY_OPTS_FEC;
 843                 if (v->zero_digest)
 844                         args++;
 845                 if (v->validated_blocks)
 846                         args++;
 847                 if (v->use_tasklet)
 848                         args++;
 849                 if (v->signature_key_desc)
 850                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 851                 if (!args)
 852                         return;
 853                 DMEMIT(" %u", args);
 854                 if (v->mode != DM_VERITY_MODE_EIO) {
 855                         DMEMIT(" ");
 856                         switch (v->mode) {
 857                         case DM_VERITY_MODE_LOGGING:
 858                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 859                                 break;
 860                         case DM_VERITY_MODE_RESTART:
 861                                 DMEMIT(DM_VERITY_OPT_RESTART);
 862                                 break;
 863                         case DM_VERITY_MODE_PANIC:
 864                                 DMEMIT(DM_VERITY_OPT_PANIC);
 865                                 break;
 866                         default:
 867                                 BUG();
 868                         }
 869                 }
 870                 if (v->zero_digest)
 871                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 872                 if (v->validated_blocks)
 873                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 874                 if (v->use_tasklet)
 875                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 876                 sz = verity_fec_status_table(v, sz, result, maxlen);
 877                 if (v->signature_key_desc)
 878                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 879                                 " %s", v->signature_key_desc);
 880                 break;
 881
 882         case STATUSTYPE_IMA:
 883                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 884                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 885                 DMEMIT(",verity_version=%u", v->version);
 886                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 887                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 888                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 889
 890                 DMEMIT(",root_digest=");
 891                 for (x = 0; x < v->digest_size; x++)
 892                         DMEMIT("%02x", v->root_digest[x]);
 893
 894                 DMEMIT(",salt=");
 895                 if (!v->salt_size)
 896                         DMEMIT("-");
 897                 else
 898                         for (x = 0; x < v->salt_size; x++)
 899                                 DMEMIT("%02x", v->salt[x]);
 900
 901                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 902                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 903                 if (v->signature_key_desc)
 904                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 905
 906                 if (v->mode != DM_VERITY_MODE_EIO) {
 907                         DMEMIT(",verity_mode=");
 908                         switch (v->mode) {
 909                         case DM_VERITY_MODE_LOGGING:
 910                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 911                                 break;
 912                         case DM_VERITY_MODE_RESTART:
 913                                 DMEMIT(DM_VERITY_OPT_RESTART);
 914                                 break;
 915                         case DM_VERITY_MODE_PANIC:
 916                                 DMEMIT(DM_VERITY_OPT_PANIC);
 917                                 break;
 918                         default:
 919                                 DMEMIT("invalid");
 920                         }
 921                 }
 922                 DMEMIT(";");
 923                 break;
 924         }
 925 }
 926
 927 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 928 {
 929         struct dm_verity *v = ti->private;
 930
 931         *bdev = v->data_dev->bdev;
 932
 933         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 934                 return 1;
 935         return 0;
 936 }
 937
 938 static int verity_iterate_devices(struct dm_target *ti,
 939                                   iterate_devices_callout_fn fn, void *data)
 940 {
 941         struct dm_verity *v = ti->private;
 942
 943         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 944 }
 945
 946 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 947 {
 948         struct dm_verity *v = ti->private;
 949
 950         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 951                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 952
 953         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 954                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 955
 956         blk_limits_io_min(limits, limits->logical_block_size);
 957 }
 958
 959 static void verity_dtr(struct dm_target *ti)
 960 {
 961         struct dm_verity *v = ti->private;
 962
 963         if (v->verify_wq)
 964                 destroy_workqueue(v->verify_wq);
 965
 966         if (v->bufio)
 967                 dm_bufio_client_destroy(v->bufio);
 968
 969         kvfree(v->validated_blocks);
 970         kfree(v->salt);
 971         kfree(v->root_digest);
 972         kfree(v->zero_digest);
 973
 974         if (v->tfm)
 975                 crypto_free_ahash(v->tfm);
 976
 977         kfree(v->alg_name);
 978
 979         if (v->hash_dev)
 980                 dm_put_device(ti, v->hash_dev);
 981
 982         if (v->data_dev)
 983                 dm_put_device(ti, v->data_dev);
 984
 985         verity_fec_dtr(v);
 986
 987         kfree(v->signature_key_desc);
 988
 989         if (v->use_tasklet)
 990                 static_branch_dec(&use_tasklet_enabled);
 991
 992         kfree(v);
 993
 994         dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
 995 }
 996
 997 static int verity_alloc_most_once(struct dm_verity *v)
 998 {
 999         struct dm_target *ti = v->ti;
1000
1001         /* the bitset can only handle INT_MAX blocks */
1002         if (v->data_blocks > INT_MAX) {
1003                 ti->error = "device too large to use check_at_most_once";
1004                 return -E2BIG;
1005         }
1006
1007         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1008                                        sizeof(unsigned long),
1009                                        GFP_KERNEL);
1010         if (!v->validated_blocks) {
1011                 ti->error = "failed to allocate bitset for check_at_most_once";
1012                 return -ENOMEM;
1013         }
1014
1015         return 0;
1016 }
1017
1018 static int verity_alloc_zero_digest(struct dm_verity *v)
1019 {
1020         int r = -ENOMEM;
1021         struct ahash_request *req;
1022         u8 *zero_data;
1023
1024         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1025
1026         if (!v->zero_digest)
1027                 return r;
1028
1029         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1030
1031         if (!req)
1032                 return r; /* verity_dtr will free zero_digest */
1033
1034         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1035
1036         if (!zero_data)
1037                 goto out;
1038
1039         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1040                         v->zero_digest, true);
1041
1042 out:
1043         kfree(req);
1044         kfree(zero_data);
1045
1046         return r;
1047 }
1048
1049 static inline bool verity_is_verity_mode(const char *arg_name)
1050 {
1051         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1052                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1053                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1054 }
1055
1056 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1057 {
1058         if (v->mode)
1059                 return -EINVAL;
1060
1061         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1062                 v->mode = DM_VERITY_MODE_LOGGING;
1063         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1064                 v->mode = DM_VERITY_MODE_RESTART;
1065         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1066                 v->mode = DM_VERITY_MODE_PANIC;
1067
1068         return 0;
1069 }
1070
1071 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1072                                  struct dm_verity_sig_opts *verify_args,
1073                                  bool only_modifier_opts)
1074 {
1075         int r = 0;
1076         unsigned int argc;
1077         struct dm_target *ti = v->ti;
1078         const char *arg_name;
1079
1080         static const struct dm_arg _args[] = {
1081                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1082         };
1083
1084         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1085         if (r)
1086                 return -EINVAL;
1087
1088         if (!argc)
1089                 return 0;
1090
1091         do {
1092                 arg_name = dm_shift_arg(as);
1093                 argc--;
1094
1095                 if (verity_is_verity_mode(arg_name)) {
1096                         if (only_modifier_opts)
1097                                 continue;
1098                         r = verity_parse_verity_mode(v, arg_name);
1099                         if (r) {
1100                                 ti->error = "Conflicting error handling parameters";
1101                                 return r;
1102                         }
1103                         continue;
1104
1105                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1106                         if (only_modifier_opts)
1107                                 continue;
1108                         r = verity_alloc_zero_digest(v);
1109                         if (r) {
1110                                 ti->error = "Cannot allocate zero digest";
1111                                 return r;
1112                         }
1113                         continue;
1114
1115                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1116                         if (only_modifier_opts)
1117                                 continue;
1118                         r = verity_alloc_most_once(v);
1119                         if (r)
1120                                 return r;
1121                         continue;
1122
1123                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1124                         v->use_tasklet = true;
1125                         static_branch_inc(&use_tasklet_enabled);
1126                         continue;
1127
1128                 } else if (verity_is_fec_opt_arg(arg_name)) {
1129                         if (only_modifier_opts)
1130                                 continue;
1131                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1132                         if (r)
1133                                 return r;
1134                         continue;
1135
1136                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1137                         if (only_modifier_opts)
1138                                 continue;
1139                         r = verity_verify_sig_parse_opt_args(as, v,
1140                                                              verify_args,
1141                                                              &argc, arg_name);
1142                         if (r)
1143                                 return r;
1144                         continue;
1145
1146                 } else if (only_modifier_opts) {
1147                         /*
1148                          * Ignore unrecognized opt, could easily be an extra
1149                          * argument to an option whose parsing was skipped.
1150                          * Normal parsing (@only_modifier_opts=false) will
1151                          * properly parse all options (and their extra args).
1152                          */
1153                         continue;
1154                 }
1155
1156                 DMERR("Unrecognized verity feature request: %s", arg_name);
1157                 ti->error = "Unrecognized verity feature request";
1158                 return -EINVAL;
1159         } while (argc && !r);
1160
1161         return r;
1162 }
1163
1164 /*
1165  * Target parameters:
1166  *      <version>       The current format is version 1.
1167  *                      Vsn 0 is compatible with original Chromium OS releases.
1168  *      <data device>
1169  *      <hash device>
1170  *      <data block size>
1171  *      <hash block size>
1172  *      <the number of data blocks>
1173  *      <hash start block>
1174  *      <algorithm>
1175  *      <digest>
1176  *      <salt>          Hex string or "-" if no salt.
1177  */
1178 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1179 {
1180         struct dm_verity *v;
1181         struct dm_verity_sig_opts verify_args = {0};
1182         struct dm_arg_set as;
1183         unsigned int num;
1184         unsigned long long num_ll;
1185         int r;
1186         int i;
1187         sector_t hash_position;
1188         char dummy;
1189         char *root_hash_digest_to_validate;
1190
1191         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1192         if (!v) {
1193                 ti->error = "Cannot allocate verity structure";
1194                 return -ENOMEM;
1195         }
1196         ti->private = v;
1197         v->ti = ti;
1198
1199         r = verity_fec_ctr_alloc(v);
1200         if (r)
1201                 goto bad;
1202
1203         if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1204                 ti->error = "Device must be readonly";
1205                 r = -EINVAL;
1206                 goto bad;
1207         }
1208
1209         if (argc < 10) {
1210                 ti->error = "Not enough arguments";
1211                 r = -EINVAL;
1212                 goto bad;
1213         }
1214
1215         /* Parse optional parameters that modify primary args */
1216         if (argc > 10) {
1217                 as.argc = argc - 10;
1218                 as.argv = argv + 10;
1219                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1220                 if (r < 0)
1221                         goto bad;
1222         }
1223
1224         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1225             num > 1) {
1226                 ti->error = "Invalid version";
1227                 r = -EINVAL;
1228                 goto bad;
1229         }
1230         v->version = num;
1231
1232         r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1233         if (r) {
1234                 ti->error = "Data device lookup failed";
1235                 goto bad;
1236         }
1237
1238         r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1239         if (r) {
1240                 ti->error = "Hash device lookup failed";
1241                 goto bad;
1242         }
1243
1244         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1245             !num || (num & (num - 1)) ||
1246             num < bdev_logical_block_size(v->data_dev->bdev) ||
1247             num > PAGE_SIZE) {
1248                 ti->error = "Invalid data device block size";
1249                 r = -EINVAL;
1250                 goto bad;
1251         }
1252         v->data_dev_block_bits = __ffs(num);
1253
1254         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1255             !num || (num & (num - 1)) ||
1256             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1257             num > INT_MAX) {
1258                 ti->error = "Invalid hash device block size";
1259                 r = -EINVAL;
1260                 goto bad;
1261         }
1262         v->hash_dev_block_bits = __ffs(num);
1263
1264         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1265             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1266             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1267                 ti->error = "Invalid data blocks";
1268                 r = -EINVAL;
1269                 goto bad;
1270         }
1271         v->data_blocks = num_ll;
1272
1273         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1274                 ti->error = "Data device is too small";
1275                 r = -EINVAL;
1276                 goto bad;
1277         }
1278
1279         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1280             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1281             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1282                 ti->error = "Invalid hash start";
1283                 r = -EINVAL;
1284                 goto bad;
1285         }
1286         v->hash_start = num_ll;
1287
1288         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1289         if (!v->alg_name) {
1290                 ti->error = "Cannot allocate algorithm name";
1291                 r = -ENOMEM;
1292                 goto bad;
1293         }
1294
1295         v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1296                                     v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1297         if (IS_ERR(v->tfm)) {
1298                 ti->error = "Cannot initialize hash function";
1299                 r = PTR_ERR(v->tfm);
1300                 v->tfm = NULL;
1301                 goto bad;
1302         }
1303
1304         /*
1305          * dm-verity performance can vary greatly depending on which hash
1306          * algorithm implementation is used.  Help people debug performance
1307          * problems by logging the ->cra_driver_name.
1308          */
1309         DMINFO("%s using implementation \"%s\"", v->alg_name,
1310                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1311
1312         v->digest_size = crypto_ahash_digestsize(v->tfm);
1313         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1314                 ti->error = "Digest size too big";
1315                 r = -EINVAL;
1316                 goto bad;
1317         }
1318         v->ahash_reqsize = sizeof(struct ahash_request) +
1319                 crypto_ahash_reqsize(v->tfm);
1320
1321         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1322         if (!v->root_digest) {
1323                 ti->error = "Cannot allocate root digest";
1324                 r = -ENOMEM;
1325                 goto bad;
1326         }
1327         if (strlen(argv[8]) != v->digest_size * 2 ||
1328             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1329                 ti->error = "Invalid root digest";
1330                 r = -EINVAL;
1331                 goto bad;
1332         }
1333         root_hash_digest_to_validate = argv[8];
1334
1335         if (strcmp(argv[9], "-")) {
1336                 v->salt_size = strlen(argv[9]) / 2;
1337                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1338                 if (!v->salt) {
1339                         ti->error = "Cannot allocate salt";
1340                         r = -ENOMEM;
1341                         goto bad;
1342                 }
1343                 if (strlen(argv[9]) != v->salt_size * 2 ||
1344                     hex2bin(v->salt, argv[9], v->salt_size)) {
1345                         ti->error = "Invalid salt";
1346                         r = -EINVAL;
1347                         goto bad;
1348                 }
1349         }
1350
1351         argv += 10;
1352         argc -= 10;
1353
1354         /* Optional parameters */
1355         if (argc) {
1356                 as.argc = argc;
1357                 as.argv = argv;
1358                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1359                 if (r < 0)
1360                         goto bad;
1361         }
1362
1363         /* Root hash signature is  a optional parameter*/
1364         r = verity_verify_root_hash(root_hash_digest_to_validate,
1365                                     strlen(root_hash_digest_to_validate),
1366                                     verify_args.sig,
1367                                     verify_args.sig_size);
1368         if (r < 0) {
1369                 ti->error = "Root hash verification failed";
1370                 goto bad;
1371         }
1372         v->hash_per_block_bits =
1373                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1374
1375         v->levels = 0;
1376         if (v->data_blocks)
1377                 while (v->hash_per_block_bits * v->levels < 64 &&
1378                        (unsigned long long)(v->data_blocks - 1) >>
1379                        (v->hash_per_block_bits * v->levels))
1380                         v->levels++;
1381
1382         if (v->levels > DM_VERITY_MAX_LEVELS) {
1383                 ti->error = "Too many tree levels";
1384                 r = -E2BIG;
1385                 goto bad;
1386         }
1387
1388         hash_position = v->hash_start;
1389         for (i = v->levels - 1; i >= 0; i--) {
1390                 sector_t s;
1391
1392                 v->hash_level_block[i] = hash_position;
1393                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1394                                         >> ((i + 1) * v->hash_per_block_bits);
1395                 if (hash_position + s < hash_position) {
1396                         ti->error = "Hash device offset overflow";
1397                         r = -E2BIG;
1398                         goto bad;
1399                 }
1400                 hash_position += s;
1401         }
1402         v->hash_blocks = hash_position;
1403
1404         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1405                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1406                 dm_bufio_alloc_callback, NULL,
1407                 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1408         if (IS_ERR(v->bufio)) {
1409                 ti->error = "Cannot initialize dm-bufio";
1410                 r = PTR_ERR(v->bufio);
1411                 v->bufio = NULL;
1412                 goto bad;
1413         }
1414
1415         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1416                 ti->error = "Hash device is too small";
1417                 r = -E2BIG;
1418                 goto bad;
1419         }
1420
1421         /*
1422          * Using WQ_HIGHPRI improves throughput and completion latency by
1423          * reducing wait times when reading from a dm-verity device.
1424          *
1425          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1426          * allows verify_wq to preempt softirq since verification in tasklet
1427          * will fall-back to using it for error handling (or if the bufio cache
1428          * doesn't have required hashes).
1429          */
1430         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1431         if (!v->verify_wq) {
1432                 ti->error = "Cannot allocate workqueue";
1433                 r = -ENOMEM;
1434                 goto bad;
1435         }
1436
1437         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1438                                 v->ahash_reqsize + v->digest_size * 2;
1439
1440         r = verity_fec_ctr(v);
1441         if (r)
1442                 goto bad;
1443
1444         ti->per_io_data_size = roundup(ti->per_io_data_size,
1445                                        __alignof__(struct dm_verity_io));
1446
1447         verity_verify_sig_opts_cleanup(&verify_args);
1448
1449         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1450
1451         return 0;
1452
1453 bad:
1454
1455         verity_verify_sig_opts_cleanup(&verify_args);
1456         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1457         verity_dtr(ti);
1458
1459         return r;
1460 }
1461
1462 /*
1463  * Check whether a DM target is a verity target.
1464  */
1465 bool dm_is_verity_target(struct dm_target *ti)
1466 {
1467         return ti->type->module == THIS_MODULE;
1468 }
1469
1470 /*
1471  * Get the verity mode (error behavior) of a verity target.
1472  *
1473  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1474  * target.
1475  */
1476 int dm_verity_get_mode(struct dm_target *ti)
1477 {
1478         struct dm_verity *v = ti->private;
1479
1480         if (!dm_is_verity_target(ti))
1481                 return -EINVAL;
1482
1483         return v->mode;
1484 }
1485
1486 /*
1487  * Get the root digest of a verity target.
1488  *
1489  * Returns a copy of the root digest, the caller is responsible for
1490  * freeing the memory of the digest.
1491  */
1492 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1493 {
1494         struct dm_verity *v = ti->private;
1495
1496         if (!dm_is_verity_target(ti))
1497                 return -EINVAL;
1498
1499         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1500         if (*root_digest == NULL)
1501                 return -ENOMEM;
1502
1503         *digest_size = v->digest_size;
1504
1505         return 0;
1506 }
1507
1508 static struct target_type verity_target = {
1509         .name           = "verity",
1510         .features       = DM_TARGET_IMMUTABLE,
1511         .version        = {1, 9, 0},
1512         .module         = THIS_MODULE,
1513         .ctr            = verity_ctr,
1514         .dtr            = verity_dtr,
1515         .map            = verity_map,
1516         .status         = verity_status,
1517         .prepare_ioctl  = verity_prepare_ioctl,
1518         .iterate_devices = verity_iterate_devices,
1519         .io_hints       = verity_io_hints,
1520 };
1521 module_dm(verity);
1522
1523 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1524 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1525 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1526 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1527 MODULE_LICENSE("GPL");