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_recheck_copy(struct dm_verity *v, struct dm_verity_io *io,
 486                                u8 *data, size_t len)
 487 {
 488         memcpy(data, io->recheck_buffer, len);
 489         io->recheck_buffer += len;
 490
 491         return 0;
 492 }
 493
 494 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
 495                                    struct bvec_iter start, sector_t cur_block)
 496 {
 497         struct page *page;
 498         void *buffer;
 499         int r;
 500         struct dm_io_request io_req;
 501         struct dm_io_region io_loc;
 502
 503         page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
 504         buffer = page_to_virt(page);
 505
 506         io_req.bi_opf = REQ_OP_READ;
 507         io_req.mem.type = DM_IO_KMEM;
 508         io_req.mem.ptr.addr = buffer;
 509         io_req.notify.fn = NULL;
 510         io_req.client = v->io;
 511         io_loc.bdev = v->data_dev->bdev;
 512         io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
 513         io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
 514         r = dm_io(&io_req, 1, &io_loc, NULL);
 515         if (unlikely(r))
 516                 goto free_ret;
 517
 518         r = verity_hash(v, verity_io_hash_req(v, io), buffer,
 519                         1 << v->data_dev_block_bits,
 520                         verity_io_real_digest(v, io), true);
 521         if (unlikely(r))
 522                 goto free_ret;
 523
 524         if (memcmp(verity_io_real_digest(v, io),
 525                    verity_io_want_digest(v, io), v->digest_size)) {
 526                 r = -EIO;
 527                 goto free_ret;
 528         }
 529
 530         io->recheck_buffer = buffer;
 531         r = verity_for_bv_block(v, io, &start, verity_recheck_copy);
 532         if (unlikely(r))
 533                 goto free_ret;
 534
 535         r = 0;
 536 free_ret:
 537         mempool_free(page, &v->recheck_pool);
 538
 539         return r;
 540 }
 541
 542 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 543                           u8 *data, size_t len)
 544 {
 545         memset(data, 0, len);
 546         return 0;
 547 }
 548
 549 /*
 550  * Moves the bio iter one data block forward.
 551  */
 552 static inline void verity_bv_skip_block(struct dm_verity *v,
 553                                         struct dm_verity_io *io,
 554                                         struct bvec_iter *iter)
 555 {
 556         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 557
 558         bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
 559 }
 560
 561 /*
 562  * Verify one "dm_verity_io" structure.
 563  */
 564 static int verity_verify_io(struct dm_verity_io *io)
 565 {
 566         bool is_zero;
 567         struct dm_verity *v = io->v;
 568         struct bvec_iter start;
 569         struct bvec_iter iter_copy;
 570         struct bvec_iter *iter;
 571         struct crypto_wait wait;
 572         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 573         unsigned int b;
 574
 575         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 576                 /*
 577                  * Copy the iterator in case we need to restart
 578                  * verification in a work-queue.
 579                  */
 580                 iter_copy = io->iter;
 581                 iter = &iter_copy;
 582         } else
 583                 iter = &io->iter;
 584
 585         for (b = 0; b < io->n_blocks; b++) {
 586                 int r;
 587                 sector_t cur_block = io->block + b;
 588                 struct ahash_request *req = verity_io_hash_req(v, io);
 589
 590                 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 591                     likely(test_bit(cur_block, v->validated_blocks))) {
 592                         verity_bv_skip_block(v, io, iter);
 593                         continue;
 594                 }
 595
 596                 r = verity_hash_for_block(v, io, cur_block,
 597                                           verity_io_want_digest(v, io),
 598                                           &is_zero);
 599                 if (unlikely(r < 0))
 600                         return r;
 601
 602                 if (is_zero) {
 603                         /*
 604                          * If we expect a zero block, don't validate, just
 605                          * return zeros.
 606                          */
 607                         r = verity_for_bv_block(v, io, iter,
 608                                                 verity_bv_zero);
 609                         if (unlikely(r < 0))
 610                                 return r;
 611
 612                         continue;
 613                 }
 614
 615                 r = verity_hash_init(v, req, &wait, !io->in_tasklet);
 616                 if (unlikely(r < 0))
 617                         return r;
 618
 619                 start = *iter;
 620                 r = verity_for_io_block(v, io, iter, &wait);
 621                 if (unlikely(r < 0))
 622                         return r;
 623
 624                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 625                                         &wait);
 626                 if (unlikely(r < 0))
 627                         return r;
 628
 629                 if (likely(memcmp(verity_io_real_digest(v, io),
 630                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 631                         if (v->validated_blocks)
 632                                 set_bit(cur_block, v->validated_blocks);
 633                         continue;
 634                 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
 635                            io->in_tasklet) {
 636                         /*
 637                          * Error handling code (FEC included) cannot be run in a
 638                          * tasklet since it may sleep, so fallback to work-queue.
 639                          */
 640                         return -EAGAIN;
 641                 } else if (verity_recheck(v, io, start, cur_block) == 0) {
 642                         if (v->validated_blocks)
 643                                 set_bit(cur_block, v->validated_blocks);
 644                         continue;
 645 #if defined(CONFIG_DM_VERITY_FEC)
 646                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 647                                              cur_block, NULL, &start) == 0) {
 648                         continue;
 649 #endif
 650                 } else {
 651                         if (bio->bi_status) {
 652                                 /*
 653                                  * Error correction failed; Just return error
 654                                  */
 655                                 return -EIO;
 656                         }
 657                         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 658                                               cur_block)) {
 659                                 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data",
 660                                                  bio, cur_block, 0);
 661                                 return -EIO;
 662                         }
 663                 }
 664         }
 665
 666         return 0;
 667 }
 668
 669 /*
 670  * Skip verity work in response to I/O error when system is shutting down.
 671  */
 672 static inline bool verity_is_system_shutting_down(void)
 673 {
 674         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 675                 || system_state == SYSTEM_RESTART;
 676 }
 677
 678 /*
 679  * End one "io" structure with a given error.
 680  */
 681 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 682 {
 683         struct dm_verity *v = io->v;
 684         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 685
 686         bio->bi_end_io = io->orig_bi_end_io;
 687         bio->bi_status = status;
 688
 689         if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
 690                 verity_fec_finish_io(io);
 691
 692         bio_endio(bio);
 693 }
 694
 695 static void verity_work(struct work_struct *w)
 696 {
 697         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 698
 699         io->in_tasklet = false;
 700
 701         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 702 }
 703
 704 static void verity_end_io(struct bio *bio)
 705 {
 706         struct dm_verity_io *io = bio->bi_private;
 707
 708         if (bio->bi_status &&
 709             (!verity_fec_is_enabled(io->v) ||
 710              verity_is_system_shutting_down() ||
 711              (bio->bi_opf & REQ_RAHEAD))) {
 712                 verity_finish_io(io, bio->bi_status);
 713                 return;
 714         }
 715
 716         INIT_WORK(&io->work, verity_work);
 717         queue_work(io->v->verify_wq, &io->work);
 718 }
 719
 720 /*
 721  * Prefetch buffers for the specified io.
 722  * The root buffer is not prefetched, it is assumed that it will be cached
 723  * all the time.
 724  */
 725 static void verity_prefetch_io(struct work_struct *work)
 726 {
 727         struct dm_verity_prefetch_work *pw =
 728                 container_of(work, struct dm_verity_prefetch_work, work);
 729         struct dm_verity *v = pw->v;
 730         int i;
 731
 732         for (i = v->levels - 2; i >= 0; i--) {
 733                 sector_t hash_block_start;
 734                 sector_t hash_block_end;
 735
 736                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 737                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 738
 739                 if (!i) {
 740                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 741
 742                         cluster >>= v->data_dev_block_bits;
 743                         if (unlikely(!cluster))
 744                                 goto no_prefetch_cluster;
 745
 746                         if (unlikely(cluster & (cluster - 1)))
 747                                 cluster = 1 << __fls(cluster);
 748
 749                         hash_block_start &= ~(sector_t)(cluster - 1);
 750                         hash_block_end |= cluster - 1;
 751                         if (unlikely(hash_block_end >= v->hash_blocks))
 752                                 hash_block_end = v->hash_blocks - 1;
 753                 }
 754 no_prefetch_cluster:
 755                 dm_bufio_prefetch(v->bufio, hash_block_start,
 756                                   hash_block_end - hash_block_start + 1);
 757         }
 758
 759         kfree(pw);
 760 }
 761
 762 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 763 {
 764         sector_t block = io->block;
 765         unsigned int n_blocks = io->n_blocks;
 766         struct dm_verity_prefetch_work *pw;
 767
 768         if (v->validated_blocks) {
 769                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 770                         block++;
 771                         n_blocks--;
 772                 }
 773                 while (n_blocks && test_bit(block + n_blocks - 1,
 774                                             v->validated_blocks))
 775                         n_blocks--;
 776                 if (!n_blocks)
 777                         return;
 778         }
 779
 780         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 781                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 782
 783         if (!pw)
 784                 return;
 785
 786         INIT_WORK(&pw->work, verity_prefetch_io);
 787         pw->v = v;
 788         pw->block = block;
 789         pw->n_blocks = n_blocks;
 790         queue_work(v->verify_wq, &pw->work);
 791 }
 792
 793 /*
 794  * Bio map function. It allocates dm_verity_io structure and bio vector and
 795  * fills them. Then it issues prefetches and the I/O.
 796  */
 797 static int verity_map(struct dm_target *ti, struct bio *bio)
 798 {
 799         struct dm_verity *v = ti->private;
 800         struct dm_verity_io *io;
 801
 802         bio_set_dev(bio, v->data_dev->bdev);
 803         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 804
 805         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 806             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 807                 DMERR_LIMIT("unaligned io");
 808                 return DM_MAPIO_KILL;
 809         }
 810
 811         if (bio_end_sector(bio) >>
 812             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 813                 DMERR_LIMIT("io out of range");
 814                 return DM_MAPIO_KILL;
 815         }
 816
 817         if (bio_data_dir(bio) == WRITE)
 818                 return DM_MAPIO_KILL;
 819
 820         io = dm_per_bio_data(bio, ti->per_io_data_size);
 821         io->v = v;
 822         io->orig_bi_end_io = bio->bi_end_io;
 823         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 824         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 825
 826         bio->bi_end_io = verity_end_io;
 827         bio->bi_private = io;
 828         io->iter = bio->bi_iter;
 829
 830         verity_fec_init_io(io);
 831
 832         verity_submit_prefetch(v, io);
 833
 834         submit_bio_noacct(bio);
 835
 836         return DM_MAPIO_SUBMITTED;
 837 }
 838
 839 /*
 840  * Status: V (valid) or C (corruption found)
 841  */
 842 static void verity_status(struct dm_target *ti, status_type_t type,
 843                           unsigned int status_flags, char *result, unsigned int maxlen)
 844 {
 845         struct dm_verity *v = ti->private;
 846         unsigned int args = 0;
 847         unsigned int sz = 0;
 848         unsigned int x;
 849
 850         switch (type) {
 851         case STATUSTYPE_INFO:
 852                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 853                 break;
 854         case STATUSTYPE_TABLE:
 855                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 856                         v->version,
 857                         v->data_dev->name,
 858                         v->hash_dev->name,
 859                         1 << v->data_dev_block_bits,
 860                         1 << v->hash_dev_block_bits,
 861                         (unsigned long long)v->data_blocks,
 862                         (unsigned long long)v->hash_start,
 863                         v->alg_name
 864                         );
 865                 for (x = 0; x < v->digest_size; x++)
 866                         DMEMIT("%02x", v->root_digest[x]);
 867                 DMEMIT(" ");
 868                 if (!v->salt_size)
 869                         DMEMIT("-");
 870                 else
 871                         for (x = 0; x < v->salt_size; x++)
 872                                 DMEMIT("%02x", v->salt[x]);
 873                 if (v->mode != DM_VERITY_MODE_EIO)
 874                         args++;
 875                 if (verity_fec_is_enabled(v))
 876                         args += DM_VERITY_OPTS_FEC;
 877                 if (v->zero_digest)
 878                         args++;
 879                 if (v->validated_blocks)
 880                         args++;
 881                 if (v->use_tasklet)
 882                         args++;
 883                 if (v->signature_key_desc)
 884                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 885                 if (!args)
 886                         return;
 887                 DMEMIT(" %u", args);
 888                 if (v->mode != DM_VERITY_MODE_EIO) {
 889                         DMEMIT(" ");
 890                         switch (v->mode) {
 891                         case DM_VERITY_MODE_LOGGING:
 892                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 893                                 break;
 894                         case DM_VERITY_MODE_RESTART:
 895                                 DMEMIT(DM_VERITY_OPT_RESTART);
 896                                 break;
 897                         case DM_VERITY_MODE_PANIC:
 898                                 DMEMIT(DM_VERITY_OPT_PANIC);
 899                                 break;
 900                         default:
 901                                 BUG();
 902                         }
 903                 }
 904                 if (v->zero_digest)
 905                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 906                 if (v->validated_blocks)
 907                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 908                 if (v->use_tasklet)
 909                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 910                 sz = verity_fec_status_table(v, sz, result, maxlen);
 911                 if (v->signature_key_desc)
 912                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 913                                 " %s", v->signature_key_desc);
 914                 break;
 915
 916         case STATUSTYPE_IMA:
 917                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 918                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 919                 DMEMIT(",verity_version=%u", v->version);
 920                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 921                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 922                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 923
 924                 DMEMIT(",root_digest=");
 925                 for (x = 0; x < v->digest_size; x++)
 926                         DMEMIT("%02x", v->root_digest[x]);
 927
 928                 DMEMIT(",salt=");
 929                 if (!v->salt_size)
 930                         DMEMIT("-");
 931                 else
 932                         for (x = 0; x < v->salt_size; x++)
 933                                 DMEMIT("%02x", v->salt[x]);
 934
 935                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 936                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 937                 if (v->signature_key_desc)
 938                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 939
 940                 if (v->mode != DM_VERITY_MODE_EIO) {
 941                         DMEMIT(",verity_mode=");
 942                         switch (v->mode) {
 943                         case DM_VERITY_MODE_LOGGING:
 944                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 945                                 break;
 946                         case DM_VERITY_MODE_RESTART:
 947                                 DMEMIT(DM_VERITY_OPT_RESTART);
 948                                 break;
 949                         case DM_VERITY_MODE_PANIC:
 950                                 DMEMIT(DM_VERITY_OPT_PANIC);
 951                                 break;
 952                         default:
 953                                 DMEMIT("invalid");
 954                         }
 955                 }
 956                 DMEMIT(";");
 957                 break;
 958         }
 959 }
 960
 961 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 962 {
 963         struct dm_verity *v = ti->private;
 964
 965         *bdev = v->data_dev->bdev;
 966
 967         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 968                 return 1;
 969         return 0;
 970 }
 971
 972 static int verity_iterate_devices(struct dm_target *ti,
 973                                   iterate_devices_callout_fn fn, void *data)
 974 {
 975         struct dm_verity *v = ti->private;
 976
 977         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 978 }
 979
 980 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 981 {
 982         struct dm_verity *v = ti->private;
 983
 984         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 985                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 986
 987         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 988                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 989
 990         blk_limits_io_min(limits, limits->logical_block_size);
 991 }
 992
 993 static void verity_dtr(struct dm_target *ti)
 994 {
 995         struct dm_verity *v = ti->private;
 996
 997         if (v->verify_wq)
 998                 destroy_workqueue(v->verify_wq);
 999
1000         mempool_exit(&v->recheck_pool);
1001         if (v->io)
1002                 dm_io_client_destroy(v->io);
1003
1004         if (v->bufio)
1005                 dm_bufio_client_destroy(v->bufio);
1006
1007         kvfree(v->validated_blocks);
1008         kfree(v->salt);
1009         kfree(v->root_digest);
1010         kfree(v->zero_digest);
1011
1012         if (v->tfm)
1013                 crypto_free_ahash(v->tfm);
1014
1015         kfree(v->alg_name);
1016
1017         if (v->hash_dev)
1018                 dm_put_device(ti, v->hash_dev);
1019
1020         if (v->data_dev)
1021                 dm_put_device(ti, v->data_dev);
1022
1023         verity_fec_dtr(v);
1024
1025         kfree(v->signature_key_desc);
1026
1027         if (v->use_tasklet)
1028                 static_branch_dec(&use_tasklet_enabled);
1029
1030         kfree(v);
1031
1032         dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1033 }
1034
1035 static int verity_alloc_most_once(struct dm_verity *v)
1036 {
1037         struct dm_target *ti = v->ti;
1038
1039         /* the bitset can only handle INT_MAX blocks */
1040         if (v->data_blocks > INT_MAX) {
1041                 ti->error = "device too large to use check_at_most_once";
1042                 return -E2BIG;
1043         }
1044
1045         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1046                                        sizeof(unsigned long),
1047                                        GFP_KERNEL);
1048         if (!v->validated_blocks) {
1049                 ti->error = "failed to allocate bitset for check_at_most_once";
1050                 return -ENOMEM;
1051         }
1052
1053         return 0;
1054 }
1055
1056 static int verity_alloc_zero_digest(struct dm_verity *v)
1057 {
1058         int r = -ENOMEM;
1059         struct ahash_request *req;
1060         u8 *zero_data;
1061
1062         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1063
1064         if (!v->zero_digest)
1065                 return r;
1066
1067         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1068
1069         if (!req)
1070                 return r; /* verity_dtr will free zero_digest */
1071
1072         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1073
1074         if (!zero_data)
1075                 goto out;
1076
1077         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1078                         v->zero_digest, true);
1079
1080 out:
1081         kfree(req);
1082         kfree(zero_data);
1083
1084         return r;
1085 }
1086
1087 static inline bool verity_is_verity_mode(const char *arg_name)
1088 {
1089         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1090                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1091                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1092 }
1093
1094 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1095 {
1096         if (v->mode)
1097                 return -EINVAL;
1098
1099         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1100                 v->mode = DM_VERITY_MODE_LOGGING;
1101         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1102                 v->mode = DM_VERITY_MODE_RESTART;
1103         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1104                 v->mode = DM_VERITY_MODE_PANIC;
1105
1106         return 0;
1107 }
1108
1109 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1110                                  struct dm_verity_sig_opts *verify_args,
1111                                  bool only_modifier_opts)
1112 {
1113         int r = 0;
1114         unsigned int argc;
1115         struct dm_target *ti = v->ti;
1116         const char *arg_name;
1117
1118         static const struct dm_arg _args[] = {
1119                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1120         };
1121
1122         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1123         if (r)
1124                 return -EINVAL;
1125
1126         if (!argc)
1127                 return 0;
1128
1129         do {
1130                 arg_name = dm_shift_arg(as);
1131                 argc--;
1132
1133                 if (verity_is_verity_mode(arg_name)) {
1134                         if (only_modifier_opts)
1135                                 continue;
1136                         r = verity_parse_verity_mode(v, arg_name);
1137                         if (r) {
1138                                 ti->error = "Conflicting error handling parameters";
1139                                 return r;
1140                         }
1141                         continue;
1142
1143                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1144                         if (only_modifier_opts)
1145                                 continue;
1146                         r = verity_alloc_zero_digest(v);
1147                         if (r) {
1148                                 ti->error = "Cannot allocate zero digest";
1149                                 return r;
1150                         }
1151                         continue;
1152
1153                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1154                         if (only_modifier_opts)
1155                                 continue;
1156                         r = verity_alloc_most_once(v);
1157                         if (r)
1158                                 return r;
1159                         continue;
1160
1161                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1162                         v->use_tasklet = true;
1163                         static_branch_inc(&use_tasklet_enabled);
1164                         continue;
1165
1166                 } else if (verity_is_fec_opt_arg(arg_name)) {
1167                         if (only_modifier_opts)
1168                                 continue;
1169                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1170                         if (r)
1171                                 return r;
1172                         continue;
1173
1174                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1175                         if (only_modifier_opts)
1176                                 continue;
1177                         r = verity_verify_sig_parse_opt_args(as, v,
1178                                                              verify_args,
1179                                                              &argc, arg_name);
1180                         if (r)
1181                                 return r;
1182                         continue;
1183
1184                 } else if (only_modifier_opts) {
1185                         /*
1186                          * Ignore unrecognized opt, could easily be an extra
1187                          * argument to an option whose parsing was skipped.
1188                          * Normal parsing (@only_modifier_opts=false) will
1189                          * properly parse all options (and their extra args).
1190                          */
1191                         continue;
1192                 }
1193
1194                 DMERR("Unrecognized verity feature request: %s", arg_name);
1195                 ti->error = "Unrecognized verity feature request";
1196                 return -EINVAL;
1197         } while (argc && !r);
1198
1199         return r;
1200 }
1201
1202 /*
1203  * Target parameters:
1204  *      <version>       The current format is version 1.
1205  *                      Vsn 0 is compatible with original Chromium OS releases.
1206  *      <data device>
1207  *      <hash device>
1208  *      <data block size>
1209  *      <hash block size>
1210  *      <the number of data blocks>
1211  *      <hash start block>
1212  *      <algorithm>
1213  *      <digest>
1214  *      <salt>          Hex string or "-" if no salt.
1215  */
1216 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1217 {
1218         struct dm_verity *v;
1219         struct dm_verity_sig_opts verify_args = {0};
1220         struct dm_arg_set as;
1221         unsigned int num;
1222         unsigned long long num_ll;
1223         int r;
1224         int i;
1225         sector_t hash_position;
1226         char dummy;
1227         char *root_hash_digest_to_validate;
1228
1229         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1230         if (!v) {
1231                 ti->error = "Cannot allocate verity structure";
1232                 return -ENOMEM;
1233         }
1234         ti->private = v;
1235         v->ti = ti;
1236
1237         r = verity_fec_ctr_alloc(v);
1238         if (r)
1239                 goto bad;
1240
1241         if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1242                 ti->error = "Device must be readonly";
1243                 r = -EINVAL;
1244                 goto bad;
1245         }
1246
1247         if (argc < 10) {
1248                 ti->error = "Not enough arguments";
1249                 r = -EINVAL;
1250                 goto bad;
1251         }
1252
1253         /* Parse optional parameters that modify primary args */
1254         if (argc > 10) {
1255                 as.argc = argc - 10;
1256                 as.argv = argv + 10;
1257                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1258                 if (r < 0)
1259                         goto bad;
1260         }
1261
1262         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1263             num > 1) {
1264                 ti->error = "Invalid version";
1265                 r = -EINVAL;
1266                 goto bad;
1267         }
1268         v->version = num;
1269
1270         r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1271         if (r) {
1272                 ti->error = "Data device lookup failed";
1273                 goto bad;
1274         }
1275
1276         r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1277         if (r) {
1278                 ti->error = "Hash device lookup failed";
1279                 goto bad;
1280         }
1281
1282         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1283             !num || (num & (num - 1)) ||
1284             num < bdev_logical_block_size(v->data_dev->bdev) ||
1285             num > PAGE_SIZE) {
1286                 ti->error = "Invalid data device block size";
1287                 r = -EINVAL;
1288                 goto bad;
1289         }
1290         v->data_dev_block_bits = __ffs(num);
1291
1292         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1293             !num || (num & (num - 1)) ||
1294             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1295             num > INT_MAX) {
1296                 ti->error = "Invalid hash device block size";
1297                 r = -EINVAL;
1298                 goto bad;
1299         }
1300         v->hash_dev_block_bits = __ffs(num);
1301
1302         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1303             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1304             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1305                 ti->error = "Invalid data blocks";
1306                 r = -EINVAL;
1307                 goto bad;
1308         }
1309         v->data_blocks = num_ll;
1310
1311         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1312                 ti->error = "Data device is too small";
1313                 r = -EINVAL;
1314                 goto bad;
1315         }
1316
1317         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1318             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1319             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1320                 ti->error = "Invalid hash start";
1321                 r = -EINVAL;
1322                 goto bad;
1323         }
1324         v->hash_start = num_ll;
1325
1326         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1327         if (!v->alg_name) {
1328                 ti->error = "Cannot allocate algorithm name";
1329                 r = -ENOMEM;
1330                 goto bad;
1331         }
1332
1333         v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1334                                     v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1335         if (IS_ERR(v->tfm)) {
1336                 ti->error = "Cannot initialize hash function";
1337                 r = PTR_ERR(v->tfm);
1338                 v->tfm = NULL;
1339                 goto bad;
1340         }
1341
1342         /*
1343          * dm-verity performance can vary greatly depending on which hash
1344          * algorithm implementation is used.  Help people debug performance
1345          * problems by logging the ->cra_driver_name.
1346          */
1347         DMINFO("%s using implementation \"%s\"", v->alg_name,
1348                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1349
1350         v->digest_size = crypto_ahash_digestsize(v->tfm);
1351         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1352                 ti->error = "Digest size too big";
1353                 r = -EINVAL;
1354                 goto bad;
1355         }
1356         v->ahash_reqsize = sizeof(struct ahash_request) +
1357                 crypto_ahash_reqsize(v->tfm);
1358
1359         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1360         if (!v->root_digest) {
1361                 ti->error = "Cannot allocate root digest";
1362                 r = -ENOMEM;
1363                 goto bad;
1364         }
1365         if (strlen(argv[8]) != v->digest_size * 2 ||
1366             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1367                 ti->error = "Invalid root digest";
1368                 r = -EINVAL;
1369                 goto bad;
1370         }
1371         root_hash_digest_to_validate = argv[8];
1372
1373         if (strcmp(argv[9], "-")) {
1374                 v->salt_size = strlen(argv[9]) / 2;
1375                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1376                 if (!v->salt) {
1377                         ti->error = "Cannot allocate salt";
1378                         r = -ENOMEM;
1379                         goto bad;
1380                 }
1381                 if (strlen(argv[9]) != v->salt_size * 2 ||
1382                     hex2bin(v->salt, argv[9], v->salt_size)) {
1383                         ti->error = "Invalid salt";
1384                         r = -EINVAL;
1385                         goto bad;
1386                 }
1387         }
1388
1389         argv += 10;
1390         argc -= 10;
1391
1392         /* Optional parameters */
1393         if (argc) {
1394                 as.argc = argc;
1395                 as.argv = argv;
1396                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1397                 if (r < 0)
1398                         goto bad;
1399         }
1400
1401         /* Root hash signature is  a optional parameter*/
1402         r = verity_verify_root_hash(root_hash_digest_to_validate,
1403                                     strlen(root_hash_digest_to_validate),
1404                                     verify_args.sig,
1405                                     verify_args.sig_size);
1406         if (r < 0) {
1407                 ti->error = "Root hash verification failed";
1408                 goto bad;
1409         }
1410         v->hash_per_block_bits =
1411                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1412
1413         v->levels = 0;
1414         if (v->data_blocks)
1415                 while (v->hash_per_block_bits * v->levels < 64 &&
1416                        (unsigned long long)(v->data_blocks - 1) >>
1417                        (v->hash_per_block_bits * v->levels))
1418                         v->levels++;
1419
1420         if (v->levels > DM_VERITY_MAX_LEVELS) {
1421                 ti->error = "Too many tree levels";
1422                 r = -E2BIG;
1423                 goto bad;
1424         }
1425
1426         hash_position = v->hash_start;
1427         for (i = v->levels - 1; i >= 0; i--) {
1428                 sector_t s;
1429
1430                 v->hash_level_block[i] = hash_position;
1431                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1432                                         >> ((i + 1) * v->hash_per_block_bits);
1433                 if (hash_position + s < hash_position) {
1434                         ti->error = "Hash device offset overflow";
1435                         r = -E2BIG;
1436                         goto bad;
1437                 }
1438                 hash_position += s;
1439         }
1440         v->hash_blocks = hash_position;
1441
1442         r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1443         if (unlikely(r)) {
1444                 ti->error = "Cannot allocate mempool";
1445                 goto bad;
1446         }
1447
1448         v->io = dm_io_client_create();
1449         if (IS_ERR(v->io)) {
1450                 r = PTR_ERR(v->io);
1451                 v->io = NULL;
1452                 ti->error = "Cannot allocate dm io";
1453                 goto bad;
1454         }
1455
1456         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1457                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1458                 dm_bufio_alloc_callback, NULL,
1459                 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1460         if (IS_ERR(v->bufio)) {
1461                 ti->error = "Cannot initialize dm-bufio";
1462                 r = PTR_ERR(v->bufio);
1463                 v->bufio = NULL;
1464                 goto bad;
1465         }
1466
1467         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1468                 ti->error = "Hash device is too small";
1469                 r = -E2BIG;
1470                 goto bad;
1471         }
1472
1473         /*
1474          * Using WQ_HIGHPRI improves throughput and completion latency by
1475          * reducing wait times when reading from a dm-verity device.
1476          *
1477          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1478          * allows verify_wq to preempt softirq since verification in tasklet
1479          * will fall-back to using it for error handling (or if the bufio cache
1480          * doesn't have required hashes).
1481          */
1482         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1483         if (!v->verify_wq) {
1484                 ti->error = "Cannot allocate workqueue";
1485                 r = -ENOMEM;
1486                 goto bad;
1487         }
1488
1489         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1490                                 v->ahash_reqsize + v->digest_size * 2;
1491
1492         r = verity_fec_ctr(v);
1493         if (r)
1494                 goto bad;
1495
1496         ti->per_io_data_size = roundup(ti->per_io_data_size,
1497                                        __alignof__(struct dm_verity_io));
1498
1499         verity_verify_sig_opts_cleanup(&verify_args);
1500
1501         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1502
1503         return 0;
1504
1505 bad:
1506
1507         verity_verify_sig_opts_cleanup(&verify_args);
1508         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1509         verity_dtr(ti);
1510
1511         return r;
1512 }
1513
1514 /*
1515  * Check whether a DM target is a verity target.
1516  */
1517 bool dm_is_verity_target(struct dm_target *ti)
1518 {
1519         return ti->type->module == THIS_MODULE;
1520 }
1521
1522 /*
1523  * Get the verity mode (error behavior) of a verity target.
1524  *
1525  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1526  * target.
1527  */
1528 int dm_verity_get_mode(struct dm_target *ti)
1529 {
1530         struct dm_verity *v = ti->private;
1531
1532         if (!dm_is_verity_target(ti))
1533                 return -EINVAL;
1534
1535         return v->mode;
1536 }
1537
1538 /*
1539  * Get the root digest of a verity target.
1540  *
1541  * Returns a copy of the root digest, the caller is responsible for
1542  * freeing the memory of the digest.
1543  */
1544 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1545 {
1546         struct dm_verity *v = ti->private;
1547
1548         if (!dm_is_verity_target(ti))
1549                 return -EINVAL;
1550
1551         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1552         if (*root_digest == NULL)
1553                 return -ENOMEM;
1554
1555         *digest_size = v->digest_size;
1556
1557         return 0;
1558 }
1559
1560 static struct target_type verity_target = {
1561         .name           = "verity",
1562         .features       = DM_TARGET_IMMUTABLE,
1563         .version        = {1, 10, 0},
1564         .module         = THIS_MODULE,
1565         .ctr            = verity_ctr,
1566         .dtr            = verity_dtr,
1567         .map            = verity_map,
1568         .status         = verity_status,
1569         .prepare_ioctl  = verity_prepare_ioctl,
1570         .iterate_devices = verity_iterate_devices,
1571         .io_hints       = verity_io_hints,
1572 };
1573 module_dm(verity);
1574
1575 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1576 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1577 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1578 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1579 MODULE_LICENSE("GPL");