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 <linux/module.h>
  20 #include <linux/reboot.h>
  21 #include <linux/scatterlist.h>
  22 #include <linux/string.h>
  23 #include <linux/jump_label.h>
  24
  25 #define DM_MSG_PREFIX                   "verity"
  26
  27 #define DM_VERITY_ENV_LENGTH            42
  28 #define DM_VERITY_ENV_VAR_NAME          "DM_VERITY_ERR_BLOCK_NR"
  29
  30 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
  31
  32 #define DM_VERITY_MAX_CORRUPTED_ERRS    100
  33
  34 #define DM_VERITY_OPT_LOGGING           "ignore_corruption"
  35 #define DM_VERITY_OPT_RESTART           "restart_on_corruption"
  36 #define DM_VERITY_OPT_PANIC             "panic_on_corruption"
  37 #define DM_VERITY_OPT_IGN_ZEROES        "ignore_zero_blocks"
  38 #define DM_VERITY_OPT_AT_MOST_ONCE      "check_at_most_once"
  39 #define DM_VERITY_OPT_TASKLET_VERIFY    "try_verify_in_tasklet"
  40
  41 #define DM_VERITY_OPTS_MAX              (4 + DM_VERITY_OPTS_FEC + \
  42                                          DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
  43
  44 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  45
  46 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
  47
  48 static DEFINE_STATIC_KEY_FALSE(use_tasklet_enabled);
  49
  50 struct dm_verity_prefetch_work {
  51         struct work_struct work;
  52         struct dm_verity *v;
  53         sector_t block;
  54         unsigned int n_blocks;
  55 };
  56
  57 /*
  58  * Auxiliary structure appended to each dm-bufio buffer. If the value
  59  * hash_verified is nonzero, hash of the block has been verified.
  60  *
  61  * The variable hash_verified is set to 0 when allocating the buffer, then
  62  * it can be changed to 1 and it is never reset to 0 again.
  63  *
  64  * There is no lock around this value, a race condition can at worst cause
  65  * that multiple processes verify the hash of the same buffer simultaneously
  66  * and write 1 to hash_verified simultaneously.
  67  * This condition is harmless, so we don't need locking.
  68  */
  69 struct buffer_aux {
  70         int hash_verified;
  71 };
  72
  73 /*
  74  * Initialize struct buffer_aux for a freshly created buffer.
  75  */
  76 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  77 {
  78         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  79
  80         aux->hash_verified = 0;
  81 }
  82
  83 /*
  84  * Translate input sector number to the sector number on the target device.
  85  */
  86 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  87 {
  88         return v->data_start + dm_target_offset(v->ti, bi_sector);
  89 }
  90
  91 /*
  92  * Return hash position of a specified block at a specified tree level
  93  * (0 is the lowest level).
  94  * The lowest "hash_per_block_bits"-bits of the result denote hash position
  95  * inside a hash block. The remaining bits denote location of the hash block.
  96  */
  97 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
  98                                          int level)
  99 {
 100         return block >> (level * v->hash_per_block_bits);
 101 }
 102
 103 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
 104                                 const u8 *data, size_t len,
 105                                 struct crypto_wait *wait)
 106 {
 107         struct scatterlist sg;
 108
 109         if (likely(!is_vmalloc_addr(data))) {
 110                 sg_init_one(&sg, data, len);
 111                 ahash_request_set_crypt(req, &sg, NULL, len);
 112                 return crypto_wait_req(crypto_ahash_update(req), wait);
 113         } else {
 114                 do {
 115                         int r;
 116                         size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 117
 118                         flush_kernel_vmap_range((void *)data, this_step);
 119                         sg_init_table(&sg, 1);
 120                         sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 121                         ahash_request_set_crypt(req, &sg, NULL, this_step);
 122                         r = crypto_wait_req(crypto_ahash_update(req), wait);
 123                         if (unlikely(r))
 124                                 return r;
 125                         data += this_step;
 126                         len -= this_step;
 127                 } while (len);
 128                 return 0;
 129         }
 130 }
 131
 132 /*
 133  * Wrapper for crypto_ahash_init, which handles verity salting.
 134  */
 135 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
 136                                 struct crypto_wait *wait)
 137 {
 138         int r;
 139
 140         ahash_request_set_tfm(req, v->tfm);
 141         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
 142                                         CRYPTO_TFM_REQ_MAY_BACKLOG,
 143                                         crypto_req_done, (void *)wait);
 144         crypto_init_wait(wait);
 145
 146         r = crypto_wait_req(crypto_ahash_init(req), wait);
 147
 148         if (unlikely(r < 0)) {
 149                 DMERR("crypto_ahash_init failed: %d", r);
 150                 return r;
 151         }
 152
 153         if (likely(v->salt_size && (v->version >= 1)))
 154                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 155
 156         return r;
 157 }
 158
 159 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
 160                              u8 *digest, struct crypto_wait *wait)
 161 {
 162         int r;
 163
 164         if (unlikely(v->salt_size && (!v->version))) {
 165                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 166
 167                 if (r < 0) {
 168                         DMERR("%s failed updating salt: %d", __func__, r);
 169                         goto out;
 170                 }
 171         }
 172
 173         ahash_request_set_crypt(req, NULL, digest, 0);
 174         r = crypto_wait_req(crypto_ahash_final(req), wait);
 175 out:
 176         return r;
 177 }
 178
 179 int verity_hash(struct dm_verity *v, struct ahash_request *req,
 180                 const u8 *data, size_t len, u8 *digest)
 181 {
 182         int r;
 183         struct crypto_wait wait;
 184
 185         r = verity_hash_init(v, req, &wait);
 186         if (unlikely(r < 0))
 187                 goto out;
 188
 189         r = verity_hash_update(v, req, data, len, &wait);
 190         if (unlikely(r < 0))
 191                 goto out;
 192
 193         r = verity_hash_final(v, req, digest, &wait);
 194
 195 out:
 196         return r;
 197 }
 198
 199 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 200                                  sector_t *hash_block, unsigned int *offset)
 201 {
 202         sector_t position = verity_position_at_level(v, block, level);
 203         unsigned int idx;
 204
 205         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 206
 207         if (!offset)
 208                 return;
 209
 210         idx = position & ((1 << v->hash_per_block_bits) - 1);
 211         if (!v->version)
 212                 *offset = idx * v->digest_size;
 213         else
 214                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 215 }
 216
 217 /*
 218  * Handle verification errors.
 219  */
 220 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 221                              unsigned long long block)
 222 {
 223         char verity_env[DM_VERITY_ENV_LENGTH];
 224         char *envp[] = { verity_env, NULL };
 225         const char *type_str = "";
 226         struct mapped_device *md = dm_table_get_md(v->ti->table);
 227
 228         /* Corruption should be visible in device status in all modes */
 229         v->hash_failed = true;
 230
 231         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 232                 goto out;
 233
 234         v->corrupted_errs++;
 235
 236         switch (type) {
 237         case DM_VERITY_BLOCK_TYPE_DATA:
 238                 type_str = "data";
 239                 break;
 240         case DM_VERITY_BLOCK_TYPE_METADATA:
 241                 type_str = "metadata";
 242                 break;
 243         default:
 244                 BUG();
 245         }
 246
 247         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 248                     type_str, block);
 249
 250         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
 251                 DMERR("%s: reached maximum errors", v->data_dev->name);
 252
 253         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 254                 DM_VERITY_ENV_VAR_NAME, type, block);
 255
 256         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 257
 258 out:
 259         if (v->mode == DM_VERITY_MODE_LOGGING)
 260                 return 0;
 261
 262         if (v->mode == DM_VERITY_MODE_RESTART)
 263                 kernel_restart("dm-verity device corrupted");
 264
 265         if (v->mode == DM_VERITY_MODE_PANIC)
 266                 panic("dm-verity device corrupted");
 267
 268         return 1;
 269 }
 270
 271 /*
 272  * Verify hash of a metadata block pertaining to the specified data block
 273  * ("block" argument) at a specified level ("level" argument).
 274  *
 275  * On successful return, verity_io_want_digest(v, io) contains the hash value
 276  * for a lower tree level or for the data block (if we're at the lowest level).
 277  *
 278  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 279  * If "skip_unverified" is false, unverified buffer is hashed and verified
 280  * against current value of verity_io_want_digest(v, io).
 281  */
 282 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 283                                sector_t block, int level, bool skip_unverified,
 284                                u8 *want_digest)
 285 {
 286         struct dm_buffer *buf;
 287         struct buffer_aux *aux;
 288         u8 *data;
 289         int r;
 290         sector_t hash_block;
 291         unsigned int offset;
 292
 293         verity_hash_at_level(v, block, level, &hash_block, &offset);
 294
 295         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 296                 data = dm_bufio_get(v->bufio, hash_block, &buf);
 297                 if (data == NULL) {
 298                         /*
 299                          * In tasklet and the hash was not in the bufio cache.
 300                          * Return early and resume execution from a work-queue
 301                          * to read the hash from disk.
 302                          */
 303                         return -EAGAIN;
 304                 }
 305         } else
 306                 data = dm_bufio_read(v->bufio, hash_block, &buf);
 307
 308         if (IS_ERR(data))
 309                 return PTR_ERR(data);
 310
 311         aux = dm_bufio_get_aux_data(buf);
 312
 313         if (!aux->hash_verified) {
 314                 if (skip_unverified) {
 315                         r = 1;
 316                         goto release_ret_r;
 317                 }
 318
 319                 r = verity_hash(v, verity_io_hash_req(v, io),
 320                                 data, 1 << v->hash_dev_block_bits,
 321                                 verity_io_real_digest(v, io));
 322                 if (unlikely(r < 0))
 323                         goto release_ret_r;
 324
 325                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 326                                   v->digest_size) == 0))
 327                         aux->hash_verified = 1;
 328                 else if (static_branch_unlikely(&use_tasklet_enabled) &&
 329                          io->in_tasklet) {
 330                         /*
 331                          * Error handling code (FEC included) cannot be run in a
 332                          * tasklet since it may sleep, so fallback to work-queue.
 333                          */
 334                         r = -EAGAIN;
 335                         goto release_ret_r;
 336                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 337                                              hash_block, data, NULL) == 0)
 338                         aux->hash_verified = 1;
 339                 else if (verity_handle_err(v,
 340                                            DM_VERITY_BLOCK_TYPE_METADATA,
 341                                            hash_block)) {
 342                         r = -EIO;
 343                         goto release_ret_r;
 344                 }
 345         }
 346
 347         data += offset;
 348         memcpy(want_digest, data, v->digest_size);
 349         r = 0;
 350
 351 release_ret_r:
 352         dm_bufio_release(buf);
 353         return r;
 354 }
 355
 356 /*
 357  * Find a hash for a given block, write it to digest and verify the integrity
 358  * of the hash tree if necessary.
 359  */
 360 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 361                           sector_t block, u8 *digest, bool *is_zero)
 362 {
 363         int r = 0, i;
 364
 365         if (likely(v->levels)) {
 366                 /*
 367                  * First, we try to get the requested hash for
 368                  * the current block. If the hash block itself is
 369                  * verified, zero is returned. If it isn't, this
 370                  * function returns 1 and we fall back to whole
 371                  * chain verification.
 372                  */
 373                 r = verity_verify_level(v, io, block, 0, true, digest);
 374                 if (likely(r <= 0))
 375                         goto out;
 376         }
 377
 378         memcpy(digest, v->root_digest, v->digest_size);
 379
 380         for (i = v->levels - 1; i >= 0; i--) {
 381                 r = verity_verify_level(v, io, block, i, false, digest);
 382                 if (unlikely(r))
 383                         goto out;
 384         }
 385 out:
 386         if (!r && v->zero_digest)
 387                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 388         else
 389                 *is_zero = false;
 390
 391         return r;
 392 }
 393
 394 /*
 395  * Calculates the digest for the given bio
 396  */
 397 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
 398                                struct bvec_iter *iter, struct crypto_wait *wait)
 399 {
 400         unsigned int todo = 1 << v->data_dev_block_bits;
 401         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 402         struct scatterlist sg;
 403         struct ahash_request *req = verity_io_hash_req(v, io);
 404
 405         do {
 406                 int r;
 407                 unsigned int len;
 408                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 409
 410                 sg_init_table(&sg, 1);
 411
 412                 len = bv.bv_len;
 413
 414                 if (likely(len >= todo))
 415                         len = todo;
 416                 /*
 417                  * Operating on a single page at a time looks suboptimal
 418                  * until you consider the typical block size is 4,096B.
 419                  * Going through this loops twice should be very rare.
 420                  */
 421                 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
 422                 ahash_request_set_crypt(req, &sg, NULL, len);
 423                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 424
 425                 if (unlikely(r < 0)) {
 426                         DMERR("%s crypto op failed: %d", __func__, r);
 427                         return r;
 428                 }
 429
 430                 bio_advance_iter(bio, iter, len);
 431                 todo -= len;
 432         } while (todo);
 433
 434         return 0;
 435 }
 436
 437 /*
 438  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
 439  * starting from iter.
 440  */
 441 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 442                         struct bvec_iter *iter,
 443                         int (*process)(struct dm_verity *v,
 444                                        struct dm_verity_io *io, u8 *data,
 445                                        size_t len))
 446 {
 447         unsigned int todo = 1 << v->data_dev_block_bits;
 448         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 449
 450         do {
 451                 int r;
 452                 u8 *page;
 453                 unsigned int len;
 454                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 455
 456                 page = bvec_kmap_local(&bv);
 457                 len = bv.bv_len;
 458
 459                 if (likely(len >= todo))
 460                         len = todo;
 461
 462                 r = process(v, io, page, len);
 463                 kunmap_local(page);
 464
 465                 if (r < 0)
 466                         return r;
 467
 468                 bio_advance_iter(bio, iter, len);
 469                 todo -= len;
 470         } while (todo);
 471
 472         return 0;
 473 }
 474
 475 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 476                           u8 *data, size_t len)
 477 {
 478         memset(data, 0, len);
 479         return 0;
 480 }
 481
 482 /*
 483  * Moves the bio iter one data block forward.
 484  */
 485 static inline void verity_bv_skip_block(struct dm_verity *v,
 486                                         struct dm_verity_io *io,
 487                                         struct bvec_iter *iter)
 488 {
 489         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 490
 491         bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
 492 }
 493
 494 /*
 495  * Verify one "dm_verity_io" structure.
 496  */
 497 static int verity_verify_io(struct dm_verity_io *io)
 498 {
 499         bool is_zero;
 500         struct dm_verity *v = io->v;
 501 #if defined(CONFIG_DM_VERITY_FEC)
 502         struct bvec_iter start;
 503 #endif
 504         struct bvec_iter iter_copy;
 505         struct bvec_iter *iter;
 506         struct crypto_wait wait;
 507         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 508         unsigned int b;
 509
 510         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 511                 /*
 512                  * Copy the iterator in case we need to restart
 513                  * verification in a work-queue.
 514                  */
 515                 iter_copy = io->iter;
 516                 iter = &iter_copy;
 517         } else
 518                 iter = &io->iter;
 519
 520         for (b = 0; b < io->n_blocks; b++) {
 521                 int r;
 522                 sector_t cur_block = io->block + b;
 523                 struct ahash_request *req = verity_io_hash_req(v, io);
 524
 525                 if (v->validated_blocks &&
 526                     likely(test_bit(cur_block, v->validated_blocks))) {
 527                         verity_bv_skip_block(v, io, iter);
 528                         continue;
 529                 }
 530
 531                 r = verity_hash_for_block(v, io, cur_block,
 532                                           verity_io_want_digest(v, io),
 533                                           &is_zero);
 534                 if (unlikely(r < 0))
 535                         return r;
 536
 537                 if (is_zero) {
 538                         /*
 539                          * If we expect a zero block, don't validate, just
 540                          * return zeros.
 541                          */
 542                         r = verity_for_bv_block(v, io, iter,
 543                                                 verity_bv_zero);
 544                         if (unlikely(r < 0))
 545                                 return r;
 546
 547                         continue;
 548                 }
 549
 550                 r = verity_hash_init(v, req, &wait);
 551                 if (unlikely(r < 0))
 552                         return r;
 553
 554 #if defined(CONFIG_DM_VERITY_FEC)
 555                 if (verity_fec_is_enabled(v))
 556                         start = *iter;
 557 #endif
 558                 r = verity_for_io_block(v, io, iter, &wait);
 559                 if (unlikely(r < 0))
 560                         return r;
 561
 562                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 563                                         &wait);
 564                 if (unlikely(r < 0))
 565                         return r;
 566
 567                 if (likely(memcmp(verity_io_real_digest(v, io),
 568                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 569                         if (v->validated_blocks)
 570                                 set_bit(cur_block, v->validated_blocks);
 571                         continue;
 572                 } else if (static_branch_unlikely(&use_tasklet_enabled) &&
 573                            io->in_tasklet) {
 574                         /*
 575                          * Error handling code (FEC included) cannot be run in a
 576                          * tasklet since it may sleep, so fallback to work-queue.
 577                          */
 578                         return -EAGAIN;
 579 #if defined(CONFIG_DM_VERITY_FEC)
 580                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 581                                              cur_block, NULL, &start) == 0) {
 582                         continue;
 583 #endif
 584                 } else {
 585                         if (bio->bi_status) {
 586                                 /*
 587                                  * Error correction failed; Just return error
 588                                  */
 589                                 return -EIO;
 590                         }
 591                         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 592                                               cur_block))
 593                                 return -EIO;
 594                 }
 595         }
 596
 597         return 0;
 598 }
 599
 600 /*
 601  * Skip verity work in response to I/O error when system is shutting down.
 602  */
 603 static inline bool verity_is_system_shutting_down(void)
 604 {
 605         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 606                 || system_state == SYSTEM_RESTART;
 607 }
 608
 609 /*
 610  * End one "io" structure with a given error.
 611  */
 612 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 613 {
 614         struct dm_verity *v = io->v;
 615         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 616
 617         bio->bi_end_io = io->orig_bi_end_io;
 618         bio->bi_status = status;
 619
 620         if (!static_branch_unlikely(&use_tasklet_enabled) || !io->in_tasklet)
 621                 verity_fec_finish_io(io);
 622
 623         bio_endio(bio);
 624 }
 625
 626 static void verity_work(struct work_struct *w)
 627 {
 628         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 629
 630         io->in_tasklet = false;
 631
 632         verity_fec_init_io(io);
 633         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 634 }
 635
 636 static void verity_tasklet(unsigned long data)
 637 {
 638         struct dm_verity_io *io = (struct dm_verity_io *)data;
 639         int err;
 640
 641         io->in_tasklet = true;
 642         err = verity_verify_io(io);
 643         if (err == -EAGAIN) {
 644                 /* fallback to retrying with work-queue */
 645                 INIT_WORK(&io->work, verity_work);
 646                 queue_work(io->v->verify_wq, &io->work);
 647                 return;
 648         }
 649
 650         verity_finish_io(io, errno_to_blk_status(err));
 651 }
 652
 653 static void verity_end_io(struct bio *bio)
 654 {
 655         struct dm_verity_io *io = bio->bi_private;
 656
 657         if (bio->bi_status &&
 658             (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
 659                 verity_finish_io(io, bio->bi_status);
 660                 return;
 661         }
 662
 663         if (static_branch_unlikely(&use_tasklet_enabled) && io->v->use_tasklet) {
 664                 tasklet_init(&io->tasklet, verity_tasklet, (unsigned long)io);
 665                 tasklet_schedule(&io->tasklet);
 666         } else {
 667                 INIT_WORK(&io->work, verity_work);
 668                 queue_work(io->v->verify_wq, &io->work);
 669         }
 670 }
 671
 672 /*
 673  * Prefetch buffers for the specified io.
 674  * The root buffer is not prefetched, it is assumed that it will be cached
 675  * all the time.
 676  */
 677 static void verity_prefetch_io(struct work_struct *work)
 678 {
 679         struct dm_verity_prefetch_work *pw =
 680                 container_of(work, struct dm_verity_prefetch_work, work);
 681         struct dm_verity *v = pw->v;
 682         int i;
 683
 684         for (i = v->levels - 2; i >= 0; i--) {
 685                 sector_t hash_block_start;
 686                 sector_t hash_block_end;
 687
 688                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 689                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 690
 691                 if (!i) {
 692                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 693
 694                         cluster >>= v->data_dev_block_bits;
 695                         if (unlikely(!cluster))
 696                                 goto no_prefetch_cluster;
 697
 698                         if (unlikely(cluster & (cluster - 1)))
 699                                 cluster = 1 << __fls(cluster);
 700
 701                         hash_block_start &= ~(sector_t)(cluster - 1);
 702                         hash_block_end |= cluster - 1;
 703                         if (unlikely(hash_block_end >= v->hash_blocks))
 704                                 hash_block_end = v->hash_blocks - 1;
 705                 }
 706 no_prefetch_cluster:
 707                 dm_bufio_prefetch(v->bufio, hash_block_start,
 708                                   hash_block_end - hash_block_start + 1);
 709         }
 710
 711         kfree(pw);
 712 }
 713
 714 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 715 {
 716         sector_t block = io->block;
 717         unsigned int n_blocks = io->n_blocks;
 718         struct dm_verity_prefetch_work *pw;
 719
 720         if (v->validated_blocks) {
 721                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 722                         block++;
 723                         n_blocks--;
 724                 }
 725                 while (n_blocks && test_bit(block + n_blocks - 1,
 726                                             v->validated_blocks))
 727                         n_blocks--;
 728                 if (!n_blocks)
 729                         return;
 730         }
 731
 732         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 733                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 734
 735         if (!pw)
 736                 return;
 737
 738         INIT_WORK(&pw->work, verity_prefetch_io);
 739         pw->v = v;
 740         pw->block = block;
 741         pw->n_blocks = n_blocks;
 742         queue_work(v->verify_wq, &pw->work);
 743 }
 744
 745 /*
 746  * Bio map function. It allocates dm_verity_io structure and bio vector and
 747  * fills them. Then it issues prefetches and the I/O.
 748  */
 749 static int verity_map(struct dm_target *ti, struct bio *bio)
 750 {
 751         struct dm_verity *v = ti->private;
 752         struct dm_verity_io *io;
 753
 754         bio_set_dev(bio, v->data_dev->bdev);
 755         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 756
 757         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 758             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 759                 DMERR_LIMIT("unaligned io");
 760                 return DM_MAPIO_KILL;
 761         }
 762
 763         if (bio_end_sector(bio) >>
 764             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 765                 DMERR_LIMIT("io out of range");
 766                 return DM_MAPIO_KILL;
 767         }
 768
 769         if (bio_data_dir(bio) == WRITE)
 770                 return DM_MAPIO_KILL;
 771
 772         io = dm_per_bio_data(bio, ti->per_io_data_size);
 773         io->v = v;
 774         io->orig_bi_end_io = bio->bi_end_io;
 775         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 776         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 777
 778         bio->bi_end_io = verity_end_io;
 779         bio->bi_private = io;
 780         io->iter = bio->bi_iter;
 781
 782         verity_submit_prefetch(v, io);
 783
 784         submit_bio_noacct(bio);
 785
 786         return DM_MAPIO_SUBMITTED;
 787 }
 788
 789 /*
 790  * Status: V (valid) or C (corruption found)
 791  */
 792 static void verity_status(struct dm_target *ti, status_type_t type,
 793                           unsigned int status_flags, char *result, unsigned int maxlen)
 794 {
 795         struct dm_verity *v = ti->private;
 796         unsigned int args = 0;
 797         unsigned int sz = 0;
 798         unsigned int x;
 799
 800         switch (type) {
 801         case STATUSTYPE_INFO:
 802                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 803                 break;
 804         case STATUSTYPE_TABLE:
 805                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 806                         v->version,
 807                         v->data_dev->name,
 808                         v->hash_dev->name,
 809                         1 << v->data_dev_block_bits,
 810                         1 << v->hash_dev_block_bits,
 811                         (unsigned long long)v->data_blocks,
 812                         (unsigned long long)v->hash_start,
 813                         v->alg_name
 814                         );
 815                 for (x = 0; x < v->digest_size; x++)
 816                         DMEMIT("%02x", v->root_digest[x]);
 817                 DMEMIT(" ");
 818                 if (!v->salt_size)
 819                         DMEMIT("-");
 820                 else
 821                         for (x = 0; x < v->salt_size; x++)
 822                                 DMEMIT("%02x", v->salt[x]);
 823                 if (v->mode != DM_VERITY_MODE_EIO)
 824                         args++;
 825                 if (verity_fec_is_enabled(v))
 826                         args += DM_VERITY_OPTS_FEC;
 827                 if (v->zero_digest)
 828                         args++;
 829                 if (v->validated_blocks)
 830                         args++;
 831                 if (v->use_tasklet)
 832                         args++;
 833                 if (v->signature_key_desc)
 834                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 835                 if (!args)
 836                         return;
 837                 DMEMIT(" %u", args);
 838                 if (v->mode != DM_VERITY_MODE_EIO) {
 839                         DMEMIT(" ");
 840                         switch (v->mode) {
 841                         case DM_VERITY_MODE_LOGGING:
 842                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 843                                 break;
 844                         case DM_VERITY_MODE_RESTART:
 845                                 DMEMIT(DM_VERITY_OPT_RESTART);
 846                                 break;
 847                         case DM_VERITY_MODE_PANIC:
 848                                 DMEMIT(DM_VERITY_OPT_PANIC);
 849                                 break;
 850                         default:
 851                                 BUG();
 852                         }
 853                 }
 854                 if (v->zero_digest)
 855                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 856                 if (v->validated_blocks)
 857                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 858                 if (v->use_tasklet)
 859                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 860                 sz = verity_fec_status_table(v, sz, result, maxlen);
 861                 if (v->signature_key_desc)
 862                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 863                                 " %s", v->signature_key_desc);
 864                 break;
 865
 866         case STATUSTYPE_IMA:
 867                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 868                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 869                 DMEMIT(",verity_version=%u", v->version);
 870                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 871                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 872                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 873
 874                 DMEMIT(",root_digest=");
 875                 for (x = 0; x < v->digest_size; x++)
 876                         DMEMIT("%02x", v->root_digest[x]);
 877
 878                 DMEMIT(",salt=");
 879                 if (!v->salt_size)
 880                         DMEMIT("-");
 881                 else
 882                         for (x = 0; x < v->salt_size; x++)
 883                                 DMEMIT("%02x", v->salt[x]);
 884
 885                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 886                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 887                 if (v->signature_key_desc)
 888                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 889
 890                 if (v->mode != DM_VERITY_MODE_EIO) {
 891                         DMEMIT(",verity_mode=");
 892                         switch (v->mode) {
 893                         case DM_VERITY_MODE_LOGGING:
 894                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 895                                 break;
 896                         case DM_VERITY_MODE_RESTART:
 897                                 DMEMIT(DM_VERITY_OPT_RESTART);
 898                                 break;
 899                         case DM_VERITY_MODE_PANIC:
 900                                 DMEMIT(DM_VERITY_OPT_PANIC);
 901                                 break;
 902                         default:
 903                                 DMEMIT("invalid");
 904                         }
 905                 }
 906                 DMEMIT(";");
 907                 break;
 908         }
 909 }
 910
 911 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 912 {
 913         struct dm_verity *v = ti->private;
 914
 915         *bdev = v->data_dev->bdev;
 916
 917         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 918                 return 1;
 919         return 0;
 920 }
 921
 922 static int verity_iterate_devices(struct dm_target *ti,
 923                                   iterate_devices_callout_fn fn, void *data)
 924 {
 925         struct dm_verity *v = ti->private;
 926
 927         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 928 }
 929
 930 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 931 {
 932         struct dm_verity *v = ti->private;
 933
 934         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 935                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 936
 937         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 938                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 939
 940         blk_limits_io_min(limits, limits->logical_block_size);
 941 }
 942
 943 static void verity_dtr(struct dm_target *ti)
 944 {
 945         struct dm_verity *v = ti->private;
 946
 947         if (v->verify_wq)
 948                 destroy_workqueue(v->verify_wq);
 949
 950         if (v->bufio)
 951                 dm_bufio_client_destroy(v->bufio);
 952
 953         kvfree(v->validated_blocks);
 954         kfree(v->salt);
 955         kfree(v->root_digest);
 956         kfree(v->zero_digest);
 957
 958         if (v->tfm)
 959                 crypto_free_ahash(v->tfm);
 960
 961         kfree(v->alg_name);
 962
 963         if (v->hash_dev)
 964                 dm_put_device(ti, v->hash_dev);
 965
 966         if (v->data_dev)
 967                 dm_put_device(ti, v->data_dev);
 968
 969         verity_fec_dtr(v);
 970
 971         kfree(v->signature_key_desc);
 972
 973         if (v->use_tasklet)
 974                 static_branch_dec(&use_tasklet_enabled);
 975
 976         kfree(v);
 977 }
 978
 979 static int verity_alloc_most_once(struct dm_verity *v)
 980 {
 981         struct dm_target *ti = v->ti;
 982
 983         /* the bitset can only handle INT_MAX blocks */
 984         if (v->data_blocks > INT_MAX) {
 985                 ti->error = "device too large to use check_at_most_once";
 986                 return -E2BIG;
 987         }
 988
 989         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
 990                                        sizeof(unsigned long),
 991                                        GFP_KERNEL);
 992         if (!v->validated_blocks) {
 993                 ti->error = "failed to allocate bitset for check_at_most_once";
 994                 return -ENOMEM;
 995         }
 996
 997         return 0;
 998 }
 999
1000 static int verity_alloc_zero_digest(struct dm_verity *v)
1001 {
1002         int r = -ENOMEM;
1003         struct ahash_request *req;
1004         u8 *zero_data;
1005
1006         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1007
1008         if (!v->zero_digest)
1009                 return r;
1010
1011         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1012
1013         if (!req)
1014                 return r; /* verity_dtr will free zero_digest */
1015
1016         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1017
1018         if (!zero_data)
1019                 goto out;
1020
1021         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1022                         v->zero_digest);
1023
1024 out:
1025         kfree(req);
1026         kfree(zero_data);
1027
1028         return r;
1029 }
1030
1031 static inline bool verity_is_verity_mode(const char *arg_name)
1032 {
1033         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1034                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1035                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1036 }
1037
1038 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1039 {
1040         if (v->mode)
1041                 return -EINVAL;
1042
1043         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1044                 v->mode = DM_VERITY_MODE_LOGGING;
1045         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1046                 v->mode = DM_VERITY_MODE_RESTART;
1047         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1048                 v->mode = DM_VERITY_MODE_PANIC;
1049
1050         return 0;
1051 }
1052
1053 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1054                                  struct dm_verity_sig_opts *verify_args,
1055                                  bool only_modifier_opts)
1056 {
1057         int r = 0;
1058         unsigned int argc;
1059         struct dm_target *ti = v->ti;
1060         const char *arg_name;
1061
1062         static const struct dm_arg _args[] = {
1063                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1064         };
1065
1066         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1067         if (r)
1068                 return -EINVAL;
1069
1070         if (!argc)
1071                 return 0;
1072
1073         do {
1074                 arg_name = dm_shift_arg(as);
1075                 argc--;
1076
1077                 if (verity_is_verity_mode(arg_name)) {
1078                         if (only_modifier_opts)
1079                                 continue;
1080                         r = verity_parse_verity_mode(v, arg_name);
1081                         if (r) {
1082                                 ti->error = "Conflicting error handling parameters";
1083                                 return r;
1084                         }
1085                         continue;
1086
1087                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1088                         if (only_modifier_opts)
1089                                 continue;
1090                         r = verity_alloc_zero_digest(v);
1091                         if (r) {
1092                                 ti->error = "Cannot allocate zero digest";
1093                                 return r;
1094                         }
1095                         continue;
1096
1097                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1098                         if (only_modifier_opts)
1099                                 continue;
1100                         r = verity_alloc_most_once(v);
1101                         if (r)
1102                                 return r;
1103                         continue;
1104
1105                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1106                         v->use_tasklet = true;
1107                         static_branch_inc(&use_tasklet_enabled);
1108                         continue;
1109
1110                 } else if (verity_is_fec_opt_arg(arg_name)) {
1111                         if (only_modifier_opts)
1112                                 continue;
1113                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1114                         if (r)
1115                                 return r;
1116                         continue;
1117
1118                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1119                         if (only_modifier_opts)
1120                                 continue;
1121                         r = verity_verify_sig_parse_opt_args(as, v,
1122                                                              verify_args,
1123                                                              &argc, arg_name);
1124                         if (r)
1125                                 return r;
1126                         continue;
1127
1128                 } else if (only_modifier_opts) {
1129                         /*
1130                          * Ignore unrecognized opt, could easily be an extra
1131                          * argument to an option whose parsing was skipped.
1132                          * Normal parsing (@only_modifier_opts=false) will
1133                          * properly parse all options (and their extra args).
1134                          */
1135                         continue;
1136                 }
1137
1138                 DMERR("Unrecognized verity feature request: %s", arg_name);
1139                 ti->error = "Unrecognized verity feature request";
1140                 return -EINVAL;
1141         } while (argc && !r);
1142
1143         return r;
1144 }
1145
1146 /*
1147  * Target parameters:
1148  *      <version>       The current format is version 1.
1149  *                      Vsn 0 is compatible with original Chromium OS releases.
1150  *      <data device>
1151  *      <hash device>
1152  *      <data block size>
1153  *      <hash block size>
1154  *      <the number of data blocks>
1155  *      <hash start block>
1156  *      <algorithm>
1157  *      <digest>
1158  *      <salt>          Hex string or "-" if no salt.
1159  */
1160 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1161 {
1162         struct dm_verity *v;
1163         struct dm_verity_sig_opts verify_args = {0};
1164         struct dm_arg_set as;
1165         unsigned int num;
1166         unsigned long long num_ll;
1167         int r;
1168         int i;
1169         sector_t hash_position;
1170         char dummy;
1171         char *root_hash_digest_to_validate;
1172
1173         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1174         if (!v) {
1175                 ti->error = "Cannot allocate verity structure";
1176                 return -ENOMEM;
1177         }
1178         ti->private = v;
1179         v->ti = ti;
1180
1181         r = verity_fec_ctr_alloc(v);
1182         if (r)
1183                 goto bad;
1184
1185         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
1186                 ti->error = "Device must be readonly";
1187                 r = -EINVAL;
1188                 goto bad;
1189         }
1190
1191         if (argc < 10) {
1192                 ti->error = "Not enough arguments";
1193                 r = -EINVAL;
1194                 goto bad;
1195         }
1196
1197         /* Parse optional parameters that modify primary args */
1198         if (argc > 10) {
1199                 as.argc = argc - 10;
1200                 as.argv = argv + 10;
1201                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1202                 if (r < 0)
1203                         goto bad;
1204         }
1205
1206         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1207             num > 1) {
1208                 ti->error = "Invalid version";
1209                 r = -EINVAL;
1210                 goto bad;
1211         }
1212         v->version = num;
1213
1214         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1215         if (r) {
1216                 ti->error = "Data device lookup failed";
1217                 goto bad;
1218         }
1219
1220         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1221         if (r) {
1222                 ti->error = "Hash device lookup failed";
1223                 goto bad;
1224         }
1225
1226         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1227             !num || (num & (num - 1)) ||
1228             num < bdev_logical_block_size(v->data_dev->bdev) ||
1229             num > PAGE_SIZE) {
1230                 ti->error = "Invalid data device block size";
1231                 r = -EINVAL;
1232                 goto bad;
1233         }
1234         v->data_dev_block_bits = __ffs(num);
1235
1236         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1237             !num || (num & (num - 1)) ||
1238             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1239             num > INT_MAX) {
1240                 ti->error = "Invalid hash device block size";
1241                 r = -EINVAL;
1242                 goto bad;
1243         }
1244         v->hash_dev_block_bits = __ffs(num);
1245
1246         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1247             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1248             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1249                 ti->error = "Invalid data blocks";
1250                 r = -EINVAL;
1251                 goto bad;
1252         }
1253         v->data_blocks = num_ll;
1254
1255         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1256                 ti->error = "Data device is too small";
1257                 r = -EINVAL;
1258                 goto bad;
1259         }
1260
1261         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1262             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1263             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1264                 ti->error = "Invalid hash start";
1265                 r = -EINVAL;
1266                 goto bad;
1267         }
1268         v->hash_start = num_ll;
1269
1270         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1271         if (!v->alg_name) {
1272                 ti->error = "Cannot allocate algorithm name";
1273                 r = -ENOMEM;
1274                 goto bad;
1275         }
1276
1277         v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1278                                     v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1279         if (IS_ERR(v->tfm)) {
1280                 ti->error = "Cannot initialize hash function";
1281                 r = PTR_ERR(v->tfm);
1282                 v->tfm = NULL;
1283                 goto bad;
1284         }
1285
1286         /*
1287          * dm-verity performance can vary greatly depending on which hash
1288          * algorithm implementation is used.  Help people debug performance
1289          * problems by logging the ->cra_driver_name.
1290          */
1291         DMINFO("%s using implementation \"%s\"", v->alg_name,
1292                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1293
1294         v->digest_size = crypto_ahash_digestsize(v->tfm);
1295         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1296                 ti->error = "Digest size too big";
1297                 r = -EINVAL;
1298                 goto bad;
1299         }
1300         v->ahash_reqsize = sizeof(struct ahash_request) +
1301                 crypto_ahash_reqsize(v->tfm);
1302
1303         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1304         if (!v->root_digest) {
1305                 ti->error = "Cannot allocate root digest";
1306                 r = -ENOMEM;
1307                 goto bad;
1308         }
1309         if (strlen(argv[8]) != v->digest_size * 2 ||
1310             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1311                 ti->error = "Invalid root digest";
1312                 r = -EINVAL;
1313                 goto bad;
1314         }
1315         root_hash_digest_to_validate = argv[8];
1316
1317         if (strcmp(argv[9], "-")) {
1318                 v->salt_size = strlen(argv[9]) / 2;
1319                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1320                 if (!v->salt) {
1321                         ti->error = "Cannot allocate salt";
1322                         r = -ENOMEM;
1323                         goto bad;
1324                 }
1325                 if (strlen(argv[9]) != v->salt_size * 2 ||
1326                     hex2bin(v->salt, argv[9], v->salt_size)) {
1327                         ti->error = "Invalid salt";
1328                         r = -EINVAL;
1329                         goto bad;
1330                 }
1331         }
1332
1333         argv += 10;
1334         argc -= 10;
1335
1336         /* Optional parameters */
1337         if (argc) {
1338                 as.argc = argc;
1339                 as.argv = argv;
1340                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1341                 if (r < 0)
1342                         goto bad;
1343         }
1344
1345         /* Root hash signature is  a optional parameter*/
1346         r = verity_verify_root_hash(root_hash_digest_to_validate,
1347                                     strlen(root_hash_digest_to_validate),
1348                                     verify_args.sig,
1349                                     verify_args.sig_size);
1350         if (r < 0) {
1351                 ti->error = "Root hash verification failed";
1352                 goto bad;
1353         }
1354         v->hash_per_block_bits =
1355                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1356
1357         v->levels = 0;
1358         if (v->data_blocks)
1359                 while (v->hash_per_block_bits * v->levels < 64 &&
1360                        (unsigned long long)(v->data_blocks - 1) >>
1361                        (v->hash_per_block_bits * v->levels))
1362                         v->levels++;
1363
1364         if (v->levels > DM_VERITY_MAX_LEVELS) {
1365                 ti->error = "Too many tree levels";
1366                 r = -E2BIG;
1367                 goto bad;
1368         }
1369
1370         hash_position = v->hash_start;
1371         for (i = v->levels - 1; i >= 0; i--) {
1372                 sector_t s;
1373
1374                 v->hash_level_block[i] = hash_position;
1375                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1376                                         >> ((i + 1) * v->hash_per_block_bits);
1377                 if (hash_position + s < hash_position) {
1378                         ti->error = "Hash device offset overflow";
1379                         r = -E2BIG;
1380                         goto bad;
1381                 }
1382                 hash_position += s;
1383         }
1384         v->hash_blocks = hash_position;
1385
1386         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1387                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1388                 dm_bufio_alloc_callback, NULL,
1389                 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1390         if (IS_ERR(v->bufio)) {
1391                 ti->error = "Cannot initialize dm-bufio";
1392                 r = PTR_ERR(v->bufio);
1393                 v->bufio = NULL;
1394                 goto bad;
1395         }
1396
1397         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1398                 ti->error = "Hash device is too small";
1399                 r = -E2BIG;
1400                 goto bad;
1401         }
1402
1403         /*
1404          * Using WQ_HIGHPRI improves throughput and completion latency by
1405          * reducing wait times when reading from a dm-verity device.
1406          *
1407          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1408          * allows verify_wq to preempt softirq since verification in tasklet
1409          * will fall-back to using it for error handling (or if the bufio cache
1410          * doesn't have required hashes).
1411          */
1412         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1413         if (!v->verify_wq) {
1414                 ti->error = "Cannot allocate workqueue";
1415                 r = -ENOMEM;
1416                 goto bad;
1417         }
1418
1419         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1420                                 v->ahash_reqsize + v->digest_size * 2;
1421
1422         r = verity_fec_ctr(v);
1423         if (r)
1424                 goto bad;
1425
1426         ti->per_io_data_size = roundup(ti->per_io_data_size,
1427                                        __alignof__(struct dm_verity_io));
1428
1429         verity_verify_sig_opts_cleanup(&verify_args);
1430
1431         return 0;
1432
1433 bad:
1434
1435         verity_verify_sig_opts_cleanup(&verify_args);
1436         verity_dtr(ti);
1437
1438         return r;
1439 }
1440
1441 /*
1442  * Check whether a DM target is a verity target.
1443  */
1444 bool dm_is_verity_target(struct dm_target *ti)
1445 {
1446         return ti->type->module == THIS_MODULE;
1447 }
1448
1449 /*
1450  * Get the verity mode (error behavior) of a verity target.
1451  *
1452  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1453  * target.
1454  */
1455 int dm_verity_get_mode(struct dm_target *ti)
1456 {
1457         struct dm_verity *v = ti->private;
1458
1459         if (!dm_is_verity_target(ti))
1460                 return -EINVAL;
1461
1462         return v->mode;
1463 }
1464
1465 /*
1466  * Get the root digest of a verity target.
1467  *
1468  * Returns a copy of the root digest, the caller is responsible for
1469  * freeing the memory of the digest.
1470  */
1471 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1472 {
1473         struct dm_verity *v = ti->private;
1474
1475         if (!dm_is_verity_target(ti))
1476                 return -EINVAL;
1477
1478         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1479         if (*root_digest == NULL)
1480                 return -ENOMEM;
1481
1482         *digest_size = v->digest_size;
1483
1484         return 0;
1485 }
1486
1487 static struct target_type verity_target = {
1488         .name           = "verity",
1489         .features       = DM_TARGET_IMMUTABLE,
1490         .version        = {1, 9, 0},
1491         .module         = THIS_MODULE,
1492         .ctr            = verity_ctr,
1493         .dtr            = verity_dtr,
1494         .map            = verity_map,
1495         .status         = verity_status,
1496         .prepare_ioctl  = verity_prepare_ioctl,
1497         .iterate_devices = verity_iterate_devices,
1498         .io_hints       = verity_io_hints,
1499 };
1500
1501 static int __init dm_verity_init(void)
1502 {
1503         int r;
1504
1505         r = dm_register_target(&verity_target);
1506         if (r < 0)
1507                 DMERR("register failed %d", r);
1508
1509         return r;
1510 }
1511
1512 static void __exit dm_verity_exit(void)
1513 {
1514         dm_unregister_target(&verity_target);
1515 }
1516
1517 module_init(dm_verity_init);
1518 module_exit(dm_verity_exit);
1519
1520 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1521 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1522 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1523 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1524 MODULE_LICENSE("GPL");