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