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_bh_wq_enabled);
  50
  51 struct dm_verity_prefetch_work {
  52         struct work_struct work;
  53         struct dm_verity *v;
  54         unsigned short ioprio;
  55         sector_t block;
  56         unsigned int n_blocks;
  57 };
  58
  59 /*
  60  * Auxiliary structure appended to each dm-bufio buffer. If the value
  61  * hash_verified is nonzero, hash of the block has been verified.
  62  *
  63  * The variable hash_verified is set to 0 when allocating the buffer, then
  64  * it can be changed to 1 and it is never reset to 0 again.
  65  *
  66  * There is no lock around this value, a race condition can at worst cause
  67  * that multiple processes verify the hash of the same buffer simultaneously
  68  * and write 1 to hash_verified simultaneously.
  69  * This condition is harmless, so we don't need locking.
  70  */
  71 struct buffer_aux {
  72         int hash_verified;
  73 };
  74
  75 /*
  76  * Initialize struct buffer_aux for a freshly created buffer.
  77  */
  78 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  79 {
  80         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  81
  82         aux->hash_verified = 0;
  83 }
  84
  85 /*
  86  * Translate input sector number to the sector number on the target device.
  87  */
  88 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  89 {
  90         return v->data_start + dm_target_offset(v->ti, bi_sector);
  91 }
  92
  93 /*
  94  * Return hash position of a specified block at a specified tree level
  95  * (0 is the lowest level).
  96  * The lowest "hash_per_block_bits"-bits of the result denote hash position
  97  * inside a hash block. The remaining bits denote location of the hash block.
  98  */
  99 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
 100                                          int level)
 101 {
 102         return block >> (level * v->hash_per_block_bits);
 103 }
 104
 105 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
 106                                 const u8 *data, size_t len,
 107                                 struct crypto_wait *wait)
 108 {
 109         struct scatterlist sg;
 110
 111         if (likely(!is_vmalloc_addr(data))) {
 112                 sg_init_one(&sg, data, len);
 113                 ahash_request_set_crypt(req, &sg, NULL, len);
 114                 return crypto_wait_req(crypto_ahash_update(req), wait);
 115         }
 116
 117         do {
 118                 int r;
 119                 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 120
 121                 flush_kernel_vmap_range((void *)data, this_step);
 122                 sg_init_table(&sg, 1);
 123                 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 124                 ahash_request_set_crypt(req, &sg, NULL, this_step);
 125                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 126                 if (unlikely(r))
 127                         return r;
 128                 data += this_step;
 129                 len -= this_step;
 130         } while (len);
 131
 132         return 0;
 133 }
 134
 135 /*
 136  * Wrapper for crypto_ahash_init, which handles verity salting.
 137  */
 138 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
 139                                 struct crypto_wait *wait, bool may_sleep)
 140 {
 141         int r;
 142
 143         ahash_request_set_tfm(req, v->tfm);
 144         ahash_request_set_callback(req,
 145                 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
 146                 crypto_req_done, (void *)wait);
 147         crypto_init_wait(wait);
 148
 149         r = crypto_wait_req(crypto_ahash_init(req), wait);
 150
 151         if (unlikely(r < 0)) {
 152                 if (r != -ENOMEM)
 153                         DMERR("crypto_ahash_init failed: %d", r);
 154                 return r;
 155         }
 156
 157         if (likely(v->salt_size && (v->version >= 1)))
 158                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 159
 160         return r;
 161 }
 162
 163 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
 164                              u8 *digest, struct crypto_wait *wait)
 165 {
 166         int r;
 167
 168         if (unlikely(v->salt_size && (!v->version))) {
 169                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 170
 171                 if (r < 0) {
 172                         DMERR("%s failed updating salt: %d", __func__, r);
 173                         goto out;
 174                 }
 175         }
 176
 177         ahash_request_set_crypt(req, NULL, digest, 0);
 178         r = crypto_wait_req(crypto_ahash_final(req), wait);
 179 out:
 180         return r;
 181 }
 182
 183 int verity_hash(struct dm_verity *v, struct ahash_request *req,
 184                 const u8 *data, size_t len, u8 *digest, bool may_sleep)
 185 {
 186         int r;
 187         struct crypto_wait wait;
 188
 189         r = verity_hash_init(v, req, &wait, may_sleep);
 190         if (unlikely(r < 0))
 191                 goto out;
 192
 193         r = verity_hash_update(v, req, data, len, &wait);
 194         if (unlikely(r < 0))
 195                 goto out;
 196
 197         r = verity_hash_final(v, req, digest, &wait);
 198
 199 out:
 200         return r;
 201 }
 202
 203 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 204                                  sector_t *hash_block, unsigned int *offset)
 205 {
 206         sector_t position = verity_position_at_level(v, block, level);
 207         unsigned int idx;
 208
 209         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 210
 211         if (!offset)
 212                 return;
 213
 214         idx = position & ((1 << v->hash_per_block_bits) - 1);
 215         if (!v->version)
 216                 *offset = idx * v->digest_size;
 217         else
 218                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 219 }
 220
 221 /*
 222  * Handle verification errors.
 223  */
 224 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 225                              unsigned long long block)
 226 {
 227         char verity_env[DM_VERITY_ENV_LENGTH];
 228         char *envp[] = { verity_env, NULL };
 229         const char *type_str = "";
 230         struct mapped_device *md = dm_table_get_md(v->ti->table);
 231
 232         /* Corruption should be visible in device status in all modes */
 233         v->hash_failed = true;
 234
 235         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 236                 goto out;
 237
 238         v->corrupted_errs++;
 239
 240         switch (type) {
 241         case DM_VERITY_BLOCK_TYPE_DATA:
 242                 type_str = "data";
 243                 break;
 244         case DM_VERITY_BLOCK_TYPE_METADATA:
 245                 type_str = "metadata";
 246                 break;
 247         default:
 248                 BUG();
 249         }
 250
 251         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 252                     type_str, block);
 253
 254         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
 255                 DMERR("%s: reached maximum errors", v->data_dev->name);
 256                 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
 257         }
 258
 259         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 260                 DM_VERITY_ENV_VAR_NAME, type, block);
 261
 262         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 263
 264 out:
 265         if (v->mode == DM_VERITY_MODE_LOGGING)
 266                 return 0;
 267
 268         if (v->mode == DM_VERITY_MODE_RESTART)
 269                 kernel_restart("dm-verity device corrupted");
 270
 271         if (v->mode == DM_VERITY_MODE_PANIC)
 272                 panic("dm-verity device corrupted");
 273
 274         return 1;
 275 }
 276
 277 /*
 278  * Verify hash of a metadata block pertaining to the specified data block
 279  * ("block" argument) at a specified level ("level" argument).
 280  *
 281  * On successful return, verity_io_want_digest(v, io) contains the hash value
 282  * for a lower tree level or for the data block (if we're at the lowest level).
 283  *
 284  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 285  * If "skip_unverified" is false, unverified buffer is hashed and verified
 286  * against current value of verity_io_want_digest(v, io).
 287  */
 288 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 289                                sector_t block, int level, bool skip_unverified,
 290                                u8 *want_digest)
 291 {
 292         struct dm_buffer *buf;
 293         struct buffer_aux *aux;
 294         u8 *data;
 295         int r;
 296         sector_t hash_block;
 297         unsigned int offset;
 298         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 299
 300         verity_hash_at_level(v, block, level, &hash_block, &offset);
 301
 302         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 303                 data = dm_bufio_get(v->bufio, hash_block, &buf);
 304                 if (data == NULL) {
 305                         /*
 306                          * In tasklet and the hash was not in the bufio cache.
 307                          * Return early and resume execution from a work-queue
 308                          * to read the hash from disk.
 309                          */
 310                         return -EAGAIN;
 311                 }
 312         } else {
 313                 data = dm_bufio_read_with_ioprio(v->bufio, hash_block,
 314                                                 &buf, bio_prio(bio));
 315         }
 316
 317         if (IS_ERR(data))
 318                 return PTR_ERR(data);
 319
 320         aux = dm_bufio_get_aux_data(buf);
 321
 322         if (!aux->hash_verified) {
 323                 if (skip_unverified) {
 324                         r = 1;
 325                         goto release_ret_r;
 326                 }
 327
 328                 r = verity_hash(v, verity_io_hash_req(v, io),
 329                                 data, 1 << v->hash_dev_block_bits,
 330                                 verity_io_real_digest(v, io), !io->in_bh);
 331                 if (unlikely(r < 0))
 332                         goto release_ret_r;
 333
 334                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 335                                   v->digest_size) == 0))
 336                         aux->hash_verified = 1;
 337                 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 338                         /*
 339                          * Error handling code (FEC included) cannot be run in a
 340                          * tasklet since it may sleep, so fallback to work-queue.
 341                          */
 342                         r = -EAGAIN;
 343                         goto release_ret_r;
 344                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 345                                              hash_block, data, NULL) == 0)
 346                         aux->hash_verified = 1;
 347                 else if (verity_handle_err(v,
 348                                            DM_VERITY_BLOCK_TYPE_METADATA,
 349                                            hash_block)) {
 350                         struct bio *bio =
 351                                 dm_bio_from_per_bio_data(io,
 352                                                          v->ti->per_io_data_size);
 353                         dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
 354                                          block, 0);
 355                         r = -EIO;
 356                         goto release_ret_r;
 357                 }
 358         }
 359
 360         data += offset;
 361         memcpy(want_digest, data, v->digest_size);
 362         r = 0;
 363
 364 release_ret_r:
 365         dm_bufio_release(buf);
 366         return r;
 367 }
 368
 369 /*
 370  * Find a hash for a given block, write it to digest and verify the integrity
 371  * of the hash tree if necessary.
 372  */
 373 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 374                           sector_t block, u8 *digest, bool *is_zero)
 375 {
 376         int r = 0, i;
 377
 378         if (likely(v->levels)) {
 379                 /*
 380                  * First, we try to get the requested hash for
 381                  * the current block. If the hash block itself is
 382                  * verified, zero is returned. If it isn't, this
 383                  * function returns 1 and we fall back to whole
 384                  * chain verification.
 385                  */
 386                 r = verity_verify_level(v, io, block, 0, true, digest);
 387                 if (likely(r <= 0))
 388                         goto out;
 389         }
 390
 391         memcpy(digest, v->root_digest, v->digest_size);
 392
 393         for (i = v->levels - 1; i >= 0; i--) {
 394                 r = verity_verify_level(v, io, block, i, false, digest);
 395                 if (unlikely(r))
 396                         goto out;
 397         }
 398 out:
 399         if (!r && v->zero_digest)
 400                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 401         else
 402                 *is_zero = false;
 403
 404         return r;
 405 }
 406
 407 /*
 408  * Calculates the digest for the given bio
 409  */
 410 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
 411                                struct bvec_iter *iter, struct crypto_wait *wait)
 412 {
 413         unsigned int todo = 1 << v->data_dev_block_bits;
 414         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 415         struct scatterlist sg;
 416         struct ahash_request *req = verity_io_hash_req(v, io);
 417
 418         do {
 419                 int r;
 420                 unsigned int len;
 421                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 422
 423                 sg_init_table(&sg, 1);
 424
 425                 len = bv.bv_len;
 426
 427                 if (likely(len >= todo))
 428                         len = todo;
 429                 /*
 430                  * Operating on a single page at a time looks suboptimal
 431                  * until you consider the typical block size is 4,096B.
 432                  * Going through this loops twice should be very rare.
 433                  */
 434                 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
 435                 ahash_request_set_crypt(req, &sg, NULL, len);
 436                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 437
 438                 if (unlikely(r < 0)) {
 439                         DMERR("%s crypto op failed: %d", __func__, r);
 440                         return r;
 441                 }
 442
 443                 bio_advance_iter(bio, iter, len);
 444                 todo -= len;
 445         } while (todo);
 446
 447         return 0;
 448 }
 449
 450 /*
 451  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
 452  * starting from iter.
 453  */
 454 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 455                         struct bvec_iter *iter,
 456                         int (*process)(struct dm_verity *v,
 457                                        struct dm_verity_io *io, u8 *data,
 458                                        size_t len))
 459 {
 460         unsigned int todo = 1 << v->data_dev_block_bits;
 461         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 462
 463         do {
 464                 int r;
 465                 u8 *page;
 466                 unsigned int len;
 467                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 468
 469                 page = bvec_kmap_local(&bv);
 470                 len = bv.bv_len;
 471
 472                 if (likely(len >= todo))
 473                         len = todo;
 474
 475                 r = process(v, io, page, len);
 476                 kunmap_local(page);
 477
 478                 if (r < 0)
 479                         return r;
 480
 481                 bio_advance_iter(bio, iter, len);
 482                 todo -= len;
 483         } while (todo);
 484
 485         return 0;
 486 }
 487
 488 static int verity_recheck_copy(struct dm_verity *v, struct dm_verity_io *io,
 489                                u8 *data, size_t len)
 490 {
 491         memcpy(data, io->recheck_buffer, len);
 492         io->recheck_buffer += len;
 493
 494         return 0;
 495 }
 496
 497 static int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
 498                           struct bvec_iter start, sector_t cur_block)
 499 {
 500         struct page *page;
 501         void *buffer;
 502         int r;
 503         struct dm_io_request io_req;
 504         struct dm_io_region io_loc;
 505
 506         page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
 507         buffer = page_to_virt(page);
 508
 509         io_req.bi_opf = REQ_OP_READ;
 510         io_req.mem.type = DM_IO_KMEM;
 511         io_req.mem.ptr.addr = buffer;
 512         io_req.notify.fn = NULL;
 513         io_req.client = v->io;
 514         io_loc.bdev = v->data_dev->bdev;
 515         io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
 516         io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
 517         r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
 518         if (unlikely(r))
 519                 goto free_ret;
 520
 521         r = verity_hash(v, verity_io_hash_req(v, io), buffer,
 522                         1 << v->data_dev_block_bits,
 523                         verity_io_real_digest(v, io), true);
 524         if (unlikely(r))
 525                 goto free_ret;
 526
 527         if (memcmp(verity_io_real_digest(v, io),
 528                    verity_io_want_digest(v, io), v->digest_size)) {
 529                 r = -EIO;
 530                 goto free_ret;
 531         }
 532
 533         io->recheck_buffer = buffer;
 534         r = verity_for_bv_block(v, io, &start, verity_recheck_copy);
 535         if (unlikely(r))
 536                 goto free_ret;
 537
 538         r = 0;
 539 free_ret:
 540         mempool_free(page, &v->recheck_pool);
 541
 542         return r;
 543 }
 544
 545 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 546                           u8 *data, size_t len)
 547 {
 548         memset(data, 0, len);
 549         return 0;
 550 }
 551
 552 /*
 553  * Moves the bio iter one data block forward.
 554  */
 555 static inline void verity_bv_skip_block(struct dm_verity *v,
 556                                         struct dm_verity_io *io,
 557                                         struct bvec_iter *iter)
 558 {
 559         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 560
 561         bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
 562 }
 563
 564 /*
 565  * Verify one "dm_verity_io" structure.
 566  */
 567 static int verity_verify_io(struct dm_verity_io *io)
 568 {
 569         bool is_zero;
 570         struct dm_verity *v = io->v;
 571         struct bvec_iter start;
 572         struct bvec_iter iter_copy;
 573         struct bvec_iter *iter;
 574         struct crypto_wait wait;
 575         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 576         unsigned int b;
 577
 578         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 579                 /*
 580                  * Copy the iterator in case we need to restart
 581                  * verification in a work-queue.
 582                  */
 583                 iter_copy = io->iter;
 584                 iter = &iter_copy;
 585         } else
 586                 iter = &io->iter;
 587
 588         for (b = 0; b < io->n_blocks; b++) {
 589                 int r;
 590                 sector_t cur_block = io->block + b;
 591                 struct ahash_request *req = verity_io_hash_req(v, io);
 592
 593                 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 594                     likely(test_bit(cur_block, v->validated_blocks))) {
 595                         verity_bv_skip_block(v, io, iter);
 596                         continue;
 597                 }
 598
 599                 r = verity_hash_for_block(v, io, cur_block,
 600                                           verity_io_want_digest(v, io),
 601                                           &is_zero);
 602                 if (unlikely(r < 0))
 603                         return r;
 604
 605                 if (is_zero) {
 606                         /*
 607                          * If we expect a zero block, don't validate, just
 608                          * return zeros.
 609                          */
 610                         r = verity_for_bv_block(v, io, iter,
 611                                                 verity_bv_zero);
 612                         if (unlikely(r < 0))
 613                                 return r;
 614
 615                         continue;
 616                 }
 617
 618                 r = verity_hash_init(v, req, &wait, !io->in_bh);
 619                 if (unlikely(r < 0))
 620                         return r;
 621
 622                 start = *iter;
 623                 r = verity_for_io_block(v, io, iter, &wait);
 624                 if (unlikely(r < 0))
 625                         return r;
 626
 627                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 628                                         &wait);
 629                 if (unlikely(r < 0))
 630                         return r;
 631
 632                 if (likely(memcmp(verity_io_real_digest(v, io),
 633                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 634                         if (v->validated_blocks)
 635                                 set_bit(cur_block, v->validated_blocks);
 636                         continue;
 637                 } else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 638                         /*
 639                          * Error handling code (FEC included) cannot be run in a
 640                          * tasklet since it may sleep, so fallback to work-queue.
 641                          */
 642                         return -EAGAIN;
 643                 } else if (verity_recheck(v, io, start, cur_block) == 0) {
 644                         if (v->validated_blocks)
 645                                 set_bit(cur_block, v->validated_blocks);
 646                         continue;
 647 #if defined(CONFIG_DM_VERITY_FEC)
 648                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 649                                              cur_block, NULL, &start) == 0) {
 650                         continue;
 651 #endif
 652                 } else {
 653                         if (bio->bi_status) {
 654                                 /*
 655                                  * Error correction failed; Just return error
 656                                  */
 657                                 return -EIO;
 658                         }
 659                         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 660                                               cur_block)) {
 661                                 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
 662                                                  bio, cur_block, 0);
 663                                 return -EIO;
 664                         }
 665                 }
 666         }
 667
 668         return 0;
 669 }
 670
 671 /*
 672  * Skip verity work in response to I/O error when system is shutting down.
 673  */
 674 static inline bool verity_is_system_shutting_down(void)
 675 {
 676         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 677                 || system_state == SYSTEM_RESTART;
 678 }
 679
 680 /*
 681  * End one "io" structure with a given error.
 682  */
 683 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 684 {
 685         struct dm_verity *v = io->v;
 686         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 687
 688         bio->bi_end_io = io->orig_bi_end_io;
 689         bio->bi_status = status;
 690
 691         if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
 692                 verity_fec_finish_io(io);
 693
 694         bio_endio(bio);
 695 }
 696
 697 static void verity_work(struct work_struct *w)
 698 {
 699         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 700
 701         io->in_bh = false;
 702
 703         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 704 }
 705
 706 static void verity_bh_work(struct work_struct *w)
 707 {
 708         struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
 709         int err;
 710
 711         io->in_bh = true;
 712         err = verity_verify_io(io);
 713         if (err == -EAGAIN || err == -ENOMEM) {
 714                 /* fallback to retrying with work-queue */
 715                 INIT_WORK(&io->work, verity_work);
 716                 queue_work(io->v->verify_wq, &io->work);
 717                 return;
 718         }
 719
 720         verity_finish_io(io, errno_to_blk_status(err));
 721 }
 722
 723 static void verity_end_io(struct bio *bio)
 724 {
 725         struct dm_verity_io *io = bio->bi_private;
 726
 727         if (bio->bi_status &&
 728             (!verity_fec_is_enabled(io->v) ||
 729              verity_is_system_shutting_down() ||
 730              (bio->bi_opf & REQ_RAHEAD))) {
 731                 verity_finish_io(io, bio->bi_status);
 732                 return;
 733         }
 734
 735         if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) {
 736                 INIT_WORK(&io->bh_work, verity_bh_work);
 737                 queue_work(system_bh_wq, &io->bh_work);
 738         } else {
 739                 INIT_WORK(&io->work, verity_work);
 740                 queue_work(io->v->verify_wq, &io->work);
 741         }
 742 }
 743
 744 /*
 745  * Prefetch buffers for the specified io.
 746  * The root buffer is not prefetched, it is assumed that it will be cached
 747  * all the time.
 748  */
 749 static void verity_prefetch_io(struct work_struct *work)
 750 {
 751         struct dm_verity_prefetch_work *pw =
 752                 container_of(work, struct dm_verity_prefetch_work, work);
 753         struct dm_verity *v = pw->v;
 754         int i;
 755
 756         for (i = v->levels - 2; i >= 0; i--) {
 757                 sector_t hash_block_start;
 758                 sector_t hash_block_end;
 759
 760                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 761                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 762
 763                 if (!i) {
 764                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 765
 766                         cluster >>= v->data_dev_block_bits;
 767                         if (unlikely(!cluster))
 768                                 goto no_prefetch_cluster;
 769
 770                         if (unlikely(cluster & (cluster - 1)))
 771                                 cluster = 1 << __fls(cluster);
 772
 773                         hash_block_start &= ~(sector_t)(cluster - 1);
 774                         hash_block_end |= cluster - 1;
 775                         if (unlikely(hash_block_end >= v->hash_blocks))
 776                                 hash_block_end = v->hash_blocks - 1;
 777                 }
 778 no_prefetch_cluster:
 779                 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start,
 780                                         hash_block_end - hash_block_start + 1,
 781                                         pw->ioprio);
 782         }
 783
 784         kfree(pw);
 785 }
 786
 787 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
 788                                    unsigned short ioprio)
 789 {
 790         sector_t block = io->block;
 791         unsigned int n_blocks = io->n_blocks;
 792         struct dm_verity_prefetch_work *pw;
 793
 794         if (v->validated_blocks) {
 795                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 796                         block++;
 797                         n_blocks--;
 798                 }
 799                 while (n_blocks && test_bit(block + n_blocks - 1,
 800                                             v->validated_blocks))
 801                         n_blocks--;
 802                 if (!n_blocks)
 803                         return;
 804         }
 805
 806         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 807                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 808
 809         if (!pw)
 810                 return;
 811
 812         INIT_WORK(&pw->work, verity_prefetch_io);
 813         pw->v = v;
 814         pw->block = block;
 815         pw->n_blocks = n_blocks;
 816         pw->ioprio = ioprio;
 817         queue_work(v->verify_wq, &pw->work);
 818 }
 819
 820 /*
 821  * Bio map function. It allocates dm_verity_io structure and bio vector and
 822  * fills them. Then it issues prefetches and the I/O.
 823  */
 824 static int verity_map(struct dm_target *ti, struct bio *bio)
 825 {
 826         struct dm_verity *v = ti->private;
 827         struct dm_verity_io *io;
 828
 829         bio_set_dev(bio, v->data_dev->bdev);
 830         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 831
 832         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 833             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 834                 DMERR_LIMIT("unaligned io");
 835                 return DM_MAPIO_KILL;
 836         }
 837
 838         if (bio_end_sector(bio) >>
 839             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 840                 DMERR_LIMIT("io out of range");
 841                 return DM_MAPIO_KILL;
 842         }
 843
 844         if (bio_data_dir(bio) == WRITE)
 845                 return DM_MAPIO_KILL;
 846
 847         io = dm_per_bio_data(bio, ti->per_io_data_size);
 848         io->v = v;
 849         io->orig_bi_end_io = bio->bi_end_io;
 850         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 851         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 852
 853         bio->bi_end_io = verity_end_io;
 854         bio->bi_private = io;
 855         io->iter = bio->bi_iter;
 856
 857         verity_fec_init_io(io);
 858
 859         verity_submit_prefetch(v, io, bio_prio(bio));
 860
 861         submit_bio_noacct(bio);
 862
 863         return DM_MAPIO_SUBMITTED;
 864 }
 865
 866 /*
 867  * Status: V (valid) or C (corruption found)
 868  */
 869 static void verity_status(struct dm_target *ti, status_type_t type,
 870                           unsigned int status_flags, char *result, unsigned int maxlen)
 871 {
 872         struct dm_verity *v = ti->private;
 873         unsigned int args = 0;
 874         unsigned int sz = 0;
 875         unsigned int x;
 876
 877         switch (type) {
 878         case STATUSTYPE_INFO:
 879                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 880                 break;
 881         case STATUSTYPE_TABLE:
 882                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 883                         v->version,
 884                         v->data_dev->name,
 885                         v->hash_dev->name,
 886                         1 << v->data_dev_block_bits,
 887                         1 << v->hash_dev_block_bits,
 888                         (unsigned long long)v->data_blocks,
 889                         (unsigned long long)v->hash_start,
 890                         v->alg_name
 891                         );
 892                 for (x = 0; x < v->digest_size; x++)
 893                         DMEMIT("%02x", v->root_digest[x]);
 894                 DMEMIT(" ");
 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                 if (v->mode != DM_VERITY_MODE_EIO)
 901                         args++;
 902                 if (verity_fec_is_enabled(v))
 903                         args += DM_VERITY_OPTS_FEC;
 904                 if (v->zero_digest)
 905                         args++;
 906                 if (v->validated_blocks)
 907                         args++;
 908                 if (v->use_bh_wq)
 909                         args++;
 910                 if (v->signature_key_desc)
 911                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 912                 if (!args)
 913                         return;
 914                 DMEMIT(" %u", args);
 915                 if (v->mode != DM_VERITY_MODE_EIO) {
 916                         DMEMIT(" ");
 917                         switch (v->mode) {
 918                         case DM_VERITY_MODE_LOGGING:
 919                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 920                                 break;
 921                         case DM_VERITY_MODE_RESTART:
 922                                 DMEMIT(DM_VERITY_OPT_RESTART);
 923                                 break;
 924                         case DM_VERITY_MODE_PANIC:
 925                                 DMEMIT(DM_VERITY_OPT_PANIC);
 926                                 break;
 927                         default:
 928                                 BUG();
 929                         }
 930                 }
 931                 if (v->zero_digest)
 932                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 933                 if (v->validated_blocks)
 934                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 935                 if (v->use_bh_wq)
 936                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 937                 sz = verity_fec_status_table(v, sz, result, maxlen);
 938                 if (v->signature_key_desc)
 939                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 940                                 " %s", v->signature_key_desc);
 941                 break;
 942
 943         case STATUSTYPE_IMA:
 944                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 945                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 946                 DMEMIT(",verity_version=%u", v->version);
 947                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 948                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 949                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 950
 951                 DMEMIT(",root_digest=");
 952                 for (x = 0; x < v->digest_size; x++)
 953                         DMEMIT("%02x", v->root_digest[x]);
 954
 955                 DMEMIT(",salt=");
 956                 if (!v->salt_size)
 957                         DMEMIT("-");
 958                 else
 959                         for (x = 0; x < v->salt_size; x++)
 960                                 DMEMIT("%02x", v->salt[x]);
 961
 962                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 963                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 964                 if (v->signature_key_desc)
 965                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 966
 967                 if (v->mode != DM_VERITY_MODE_EIO) {
 968                         DMEMIT(",verity_mode=");
 969                         switch (v->mode) {
 970                         case DM_VERITY_MODE_LOGGING:
 971                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 972                                 break;
 973                         case DM_VERITY_MODE_RESTART:
 974                                 DMEMIT(DM_VERITY_OPT_RESTART);
 975                                 break;
 976                         case DM_VERITY_MODE_PANIC:
 977                                 DMEMIT(DM_VERITY_OPT_PANIC);
 978                                 break;
 979                         default:
 980                                 DMEMIT("invalid");
 981                         }
 982                 }
 983                 DMEMIT(";");
 984                 break;
 985         }
 986 }
 987
 988 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 989 {
 990         struct dm_verity *v = ti->private;
 991
 992         *bdev = v->data_dev->bdev;
 993
 994         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 995                 return 1;
 996         return 0;
 997 }
 998
 999 static int verity_iterate_devices(struct dm_target *ti,
1000                                   iterate_devices_callout_fn fn, void *data)
1001 {
1002         struct dm_verity *v = ti->private;
1003
1004         return fn(ti, v->data_dev, v->data_start, ti->len, data);
1005 }
1006
1007 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
1008 {
1009         struct dm_verity *v = ti->private;
1010
1011         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
1012                 limits->logical_block_size = 1 << v->data_dev_block_bits;
1013
1014         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
1015                 limits->physical_block_size = 1 << v->data_dev_block_bits;
1016
1017         blk_limits_io_min(limits, limits->logical_block_size);
1018 }
1019
1020 static void verity_dtr(struct dm_target *ti)
1021 {
1022         struct dm_verity *v = ti->private;
1023
1024         if (v->verify_wq)
1025                 destroy_workqueue(v->verify_wq);
1026
1027         mempool_exit(&v->recheck_pool);
1028         if (v->io)
1029                 dm_io_client_destroy(v->io);
1030
1031         if (v->bufio)
1032                 dm_bufio_client_destroy(v->bufio);
1033
1034         kvfree(v->validated_blocks);
1035         kfree(v->salt);
1036         kfree(v->root_digest);
1037         kfree(v->zero_digest);
1038
1039         if (v->tfm)
1040                 crypto_free_ahash(v->tfm);
1041
1042         kfree(v->alg_name);
1043
1044         if (v->hash_dev)
1045                 dm_put_device(ti, v->hash_dev);
1046
1047         if (v->data_dev)
1048                 dm_put_device(ti, v->data_dev);
1049
1050         verity_fec_dtr(v);
1051
1052         kfree(v->signature_key_desc);
1053
1054         if (v->use_bh_wq)
1055                 static_branch_dec(&use_bh_wq_enabled);
1056
1057         kfree(v);
1058
1059         dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1060 }
1061
1062 static int verity_alloc_most_once(struct dm_verity *v)
1063 {
1064         struct dm_target *ti = v->ti;
1065
1066         /* the bitset can only handle INT_MAX blocks */
1067         if (v->data_blocks > INT_MAX) {
1068                 ti->error = "device too large to use check_at_most_once";
1069                 return -E2BIG;
1070         }
1071
1072         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1073                                        sizeof(unsigned long),
1074                                        GFP_KERNEL);
1075         if (!v->validated_blocks) {
1076                 ti->error = "failed to allocate bitset for check_at_most_once";
1077                 return -ENOMEM;
1078         }
1079
1080         return 0;
1081 }
1082
1083 static int verity_alloc_zero_digest(struct dm_verity *v)
1084 {
1085         int r = -ENOMEM;
1086         struct ahash_request *req;
1087         u8 *zero_data;
1088
1089         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1090
1091         if (!v->zero_digest)
1092                 return r;
1093
1094         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1095
1096         if (!req)
1097                 return r; /* verity_dtr will free zero_digest */
1098
1099         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1100
1101         if (!zero_data)
1102                 goto out;
1103
1104         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1105                         v->zero_digest, true);
1106
1107 out:
1108         kfree(req);
1109         kfree(zero_data);
1110
1111         return r;
1112 }
1113
1114 static inline bool verity_is_verity_mode(const char *arg_name)
1115 {
1116         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1117                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1118                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1119 }
1120
1121 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1122 {
1123         if (v->mode)
1124                 return -EINVAL;
1125
1126         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1127                 v->mode = DM_VERITY_MODE_LOGGING;
1128         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1129                 v->mode = DM_VERITY_MODE_RESTART;
1130         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1131                 v->mode = DM_VERITY_MODE_PANIC;
1132
1133         return 0;
1134 }
1135
1136 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1137                                  struct dm_verity_sig_opts *verify_args,
1138                                  bool only_modifier_opts)
1139 {
1140         int r = 0;
1141         unsigned int argc;
1142         struct dm_target *ti = v->ti;
1143         const char *arg_name;
1144
1145         static const struct dm_arg _args[] = {
1146                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1147         };
1148
1149         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1150         if (r)
1151                 return -EINVAL;
1152
1153         if (!argc)
1154                 return 0;
1155
1156         do {
1157                 arg_name = dm_shift_arg(as);
1158                 argc--;
1159
1160                 if (verity_is_verity_mode(arg_name)) {
1161                         if (only_modifier_opts)
1162                                 continue;
1163                         r = verity_parse_verity_mode(v, arg_name);
1164                         if (r) {
1165                                 ti->error = "Conflicting error handling parameters";
1166                                 return r;
1167                         }
1168                         continue;
1169
1170                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1171                         if (only_modifier_opts)
1172                                 continue;
1173                         r = verity_alloc_zero_digest(v);
1174                         if (r) {
1175                                 ti->error = "Cannot allocate zero digest";
1176                                 return r;
1177                         }
1178                         continue;
1179
1180                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1181                         if (only_modifier_opts)
1182                                 continue;
1183                         r = verity_alloc_most_once(v);
1184                         if (r)
1185                                 return r;
1186                         continue;
1187
1188                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1189                         v->use_bh_wq = true;
1190                         static_branch_inc(&use_bh_wq_enabled);
1191                         continue;
1192
1193                 } else if (verity_is_fec_opt_arg(arg_name)) {
1194                         if (only_modifier_opts)
1195                                 continue;
1196                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1197                         if (r)
1198                                 return r;
1199                         continue;
1200
1201                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1202                         if (only_modifier_opts)
1203                                 continue;
1204                         r = verity_verify_sig_parse_opt_args(as, v,
1205                                                              verify_args,
1206                                                              &argc, arg_name);
1207                         if (r)
1208                                 return r;
1209                         continue;
1210
1211                 } else if (only_modifier_opts) {
1212                         /*
1213                          * Ignore unrecognized opt, could easily be an extra
1214                          * argument to an option whose parsing was skipped.
1215                          * Normal parsing (@only_modifier_opts=false) will
1216                          * properly parse all options (and their extra args).
1217                          */
1218                         continue;
1219                 }
1220
1221                 DMERR("Unrecognized verity feature request: %s", arg_name);
1222                 ti->error = "Unrecognized verity feature request";
1223                 return -EINVAL;
1224         } while (argc && !r);
1225
1226         return r;
1227 }
1228
1229 /*
1230  * Target parameters:
1231  *      <version>       The current format is version 1.
1232  *                      Vsn 0 is compatible with original Chromium OS releases.
1233  *      <data device>
1234  *      <hash device>
1235  *      <data block size>
1236  *      <hash block size>
1237  *      <the number of data blocks>
1238  *      <hash start block>
1239  *      <algorithm>
1240  *      <digest>
1241  *      <salt>          Hex string or "-" if no salt.
1242  */
1243 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1244 {
1245         struct dm_verity *v;
1246         struct dm_verity_sig_opts verify_args = {0};
1247         struct dm_arg_set as;
1248         unsigned int num;
1249         unsigned long long num_ll;
1250         int r;
1251         int i;
1252         sector_t hash_position;
1253         char dummy;
1254         char *root_hash_digest_to_validate;
1255
1256         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1257         if (!v) {
1258                 ti->error = "Cannot allocate verity structure";
1259                 return -ENOMEM;
1260         }
1261         ti->private = v;
1262         v->ti = ti;
1263
1264         r = verity_fec_ctr_alloc(v);
1265         if (r)
1266                 goto bad;
1267
1268         if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1269                 ti->error = "Device must be readonly";
1270                 r = -EINVAL;
1271                 goto bad;
1272         }
1273
1274         if (argc < 10) {
1275                 ti->error = "Not enough arguments";
1276                 r = -EINVAL;
1277                 goto bad;
1278         }
1279
1280         /* Parse optional parameters that modify primary args */
1281         if (argc > 10) {
1282                 as.argc = argc - 10;
1283                 as.argv = argv + 10;
1284                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1285                 if (r < 0)
1286                         goto bad;
1287         }
1288
1289         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1290             num > 1) {
1291                 ti->error = "Invalid version";
1292                 r = -EINVAL;
1293                 goto bad;
1294         }
1295         v->version = num;
1296
1297         r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1298         if (r) {
1299                 ti->error = "Data device lookup failed";
1300                 goto bad;
1301         }
1302
1303         r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1304         if (r) {
1305                 ti->error = "Hash device lookup failed";
1306                 goto bad;
1307         }
1308
1309         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1310             !num || (num & (num - 1)) ||
1311             num < bdev_logical_block_size(v->data_dev->bdev) ||
1312             num > PAGE_SIZE) {
1313                 ti->error = "Invalid data device block size";
1314                 r = -EINVAL;
1315                 goto bad;
1316         }
1317         v->data_dev_block_bits = __ffs(num);
1318
1319         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1320             !num || (num & (num - 1)) ||
1321             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1322             num > INT_MAX) {
1323                 ti->error = "Invalid hash device block size";
1324                 r = -EINVAL;
1325                 goto bad;
1326         }
1327         v->hash_dev_block_bits = __ffs(num);
1328
1329         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1330             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1331             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1332                 ti->error = "Invalid data blocks";
1333                 r = -EINVAL;
1334                 goto bad;
1335         }
1336         v->data_blocks = num_ll;
1337
1338         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1339                 ti->error = "Data device is too small";
1340                 r = -EINVAL;
1341                 goto bad;
1342         }
1343
1344         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1345             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1346             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1347                 ti->error = "Invalid hash start";
1348                 r = -EINVAL;
1349                 goto bad;
1350         }
1351         v->hash_start = num_ll;
1352
1353         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1354         if (!v->alg_name) {
1355                 ti->error = "Cannot allocate algorithm name";
1356                 r = -ENOMEM;
1357                 goto bad;
1358         }
1359
1360         v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1361                                     v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
1362         if (IS_ERR(v->tfm)) {
1363                 ti->error = "Cannot initialize hash function";
1364                 r = PTR_ERR(v->tfm);
1365                 v->tfm = NULL;
1366                 goto bad;
1367         }
1368
1369         /*
1370          * dm-verity performance can vary greatly depending on which hash
1371          * algorithm implementation is used.  Help people debug performance
1372          * problems by logging the ->cra_driver_name.
1373          */
1374         DMINFO("%s using implementation \"%s\"", v->alg_name,
1375                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1376
1377         v->digest_size = crypto_ahash_digestsize(v->tfm);
1378         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1379                 ti->error = "Digest size too big";
1380                 r = -EINVAL;
1381                 goto bad;
1382         }
1383         v->ahash_reqsize = sizeof(struct ahash_request) +
1384                 crypto_ahash_reqsize(v->tfm);
1385
1386         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1387         if (!v->root_digest) {
1388                 ti->error = "Cannot allocate root digest";
1389                 r = -ENOMEM;
1390                 goto bad;
1391         }
1392         if (strlen(argv[8]) != v->digest_size * 2 ||
1393             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1394                 ti->error = "Invalid root digest";
1395                 r = -EINVAL;
1396                 goto bad;
1397         }
1398         root_hash_digest_to_validate = argv[8];
1399
1400         if (strcmp(argv[9], "-")) {
1401                 v->salt_size = strlen(argv[9]) / 2;
1402                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1403                 if (!v->salt) {
1404                         ti->error = "Cannot allocate salt";
1405                         r = -ENOMEM;
1406                         goto bad;
1407                 }
1408                 if (strlen(argv[9]) != v->salt_size * 2 ||
1409                     hex2bin(v->salt, argv[9], v->salt_size)) {
1410                         ti->error = "Invalid salt";
1411                         r = -EINVAL;
1412                         goto bad;
1413                 }
1414         }
1415
1416         argv += 10;
1417         argc -= 10;
1418
1419         /* Optional parameters */
1420         if (argc) {
1421                 as.argc = argc;
1422                 as.argv = argv;
1423                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1424                 if (r < 0)
1425                         goto bad;
1426         }
1427
1428         /* Root hash signature is  a optional parameter*/
1429         r = verity_verify_root_hash(root_hash_digest_to_validate,
1430                                     strlen(root_hash_digest_to_validate),
1431                                     verify_args.sig,
1432                                     verify_args.sig_size);
1433         if (r < 0) {
1434                 ti->error = "Root hash verification failed";
1435                 goto bad;
1436         }
1437         v->hash_per_block_bits =
1438                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1439
1440         v->levels = 0;
1441         if (v->data_blocks)
1442                 while (v->hash_per_block_bits * v->levels < 64 &&
1443                        (unsigned long long)(v->data_blocks - 1) >>
1444                        (v->hash_per_block_bits * v->levels))
1445                         v->levels++;
1446
1447         if (v->levels > DM_VERITY_MAX_LEVELS) {
1448                 ti->error = "Too many tree levels";
1449                 r = -E2BIG;
1450                 goto bad;
1451         }
1452
1453         hash_position = v->hash_start;
1454         for (i = v->levels - 1; i >= 0; i--) {
1455                 sector_t s;
1456
1457                 v->hash_level_block[i] = hash_position;
1458                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1459                                         >> ((i + 1) * v->hash_per_block_bits);
1460                 if (hash_position + s < hash_position) {
1461                         ti->error = "Hash device offset overflow";
1462                         r = -E2BIG;
1463                         goto bad;
1464                 }
1465                 hash_position += s;
1466         }
1467         v->hash_blocks = hash_position;
1468
1469         r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1470         if (unlikely(r)) {
1471                 ti->error = "Cannot allocate mempool";
1472                 goto bad;
1473         }
1474
1475         v->io = dm_io_client_create();
1476         if (IS_ERR(v->io)) {
1477                 r = PTR_ERR(v->io);
1478                 v->io = NULL;
1479                 ti->error = "Cannot allocate dm io";
1480                 goto bad;
1481         }
1482
1483         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1484                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1485                 dm_bufio_alloc_callback, NULL,
1486                 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1487         if (IS_ERR(v->bufio)) {
1488                 ti->error = "Cannot initialize dm-bufio";
1489                 r = PTR_ERR(v->bufio);
1490                 v->bufio = NULL;
1491                 goto bad;
1492         }
1493
1494         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1495                 ti->error = "Hash device is too small";
1496                 r = -E2BIG;
1497                 goto bad;
1498         }
1499
1500         /*
1501          * Using WQ_HIGHPRI improves throughput and completion latency by
1502          * reducing wait times when reading from a dm-verity device.
1503          *
1504          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1505          * allows verify_wq to preempt softirq since verification in BH workqueue
1506          * will fall-back to using it for error handling (or if the bufio cache
1507          * doesn't have required hashes).
1508          */
1509         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1510         if (!v->verify_wq) {
1511                 ti->error = "Cannot allocate workqueue";
1512                 r = -ENOMEM;
1513                 goto bad;
1514         }
1515
1516         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1517                                 v->ahash_reqsize + v->digest_size * 2;
1518
1519         r = verity_fec_ctr(v);
1520         if (r)
1521                 goto bad;
1522
1523         ti->per_io_data_size = roundup(ti->per_io_data_size,
1524                                        __alignof__(struct dm_verity_io));
1525
1526         verity_verify_sig_opts_cleanup(&verify_args);
1527
1528         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1529
1530         return 0;
1531
1532 bad:
1533
1534         verity_verify_sig_opts_cleanup(&verify_args);
1535         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1536         verity_dtr(ti);
1537
1538         return r;
1539 }
1540
1541 /*
1542  * Check whether a DM target is a verity target.
1543  */
1544 bool dm_is_verity_target(struct dm_target *ti)
1545 {
1546         return ti->type->module == THIS_MODULE;
1547 }
1548
1549 /*
1550  * Get the verity mode (error behavior) of a verity target.
1551  *
1552  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1553  * target.
1554  */
1555 int dm_verity_get_mode(struct dm_target *ti)
1556 {
1557         struct dm_verity *v = ti->private;
1558
1559         if (!dm_is_verity_target(ti))
1560                 return -EINVAL;
1561
1562         return v->mode;
1563 }
1564
1565 /*
1566  * Get the root digest of a verity target.
1567  *
1568  * Returns a copy of the root digest, the caller is responsible for
1569  * freeing the memory of the digest.
1570  */
1571 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1572 {
1573         struct dm_verity *v = ti->private;
1574
1575         if (!dm_is_verity_target(ti))
1576                 return -EINVAL;
1577
1578         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1579         if (*root_digest == NULL)
1580                 return -ENOMEM;
1581
1582         *digest_size = v->digest_size;
1583
1584         return 0;
1585 }
1586
1587 static struct target_type verity_target = {
1588         .name           = "verity",
1589         .features       = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1590         .version        = {1, 10, 0},
1591         .module         = THIS_MODULE,
1592         .ctr            = verity_ctr,
1593         .dtr            = verity_dtr,
1594         .map            = verity_map,
1595         .status         = verity_status,
1596         .prepare_ioctl  = verity_prepare_ioctl,
1597         .iterate_devices = verity_iterate_devices,
1598         .io_hints       = verity_io_hints,
1599 };
1600 module_dm(verity);
1601
1602 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1603 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1604 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1605 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1606 MODULE_LICENSE("GPL");