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, 0644);
  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         }
 114
 115         do {
 116                 int r;
 117                 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 118
 119                 flush_kernel_vmap_range((void *)data, this_step);
 120                 sg_init_table(&sg, 1);
 121                 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 122                 ahash_request_set_crypt(req, &sg, NULL, this_step);
 123                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 124                 if (unlikely(r))
 125                         return r;
 126                 data += this_step;
 127                 len -= this_step;
 128         } while (len);
 129
 130         return 0;
 131 }
 132
 133 /*
 134  * Wrapper for crypto_ahash_init, which handles verity salting.
 135  */
 136 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
 137                                 struct crypto_wait *wait)
 138 {
 139         int r;
 140
 141         ahash_request_set_tfm(req, v->tfm);
 142         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
 143                                         CRYPTO_TFM_REQ_MAY_BACKLOG,
 144                                         crypto_req_done, (void *)wait);
 145         crypto_init_wait(wait);
 146
 147         r = crypto_wait_req(crypto_ahash_init(req), wait);
 148
 149         if (unlikely(r < 0)) {
 150                 DMERR("crypto_ahash_init failed: %d", r);
 151                 return r;
 152         }
 153
 154         if (likely(v->salt_size && (v->version >= 1)))
 155                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 156
 157         return r;
 158 }
 159
 160 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
 161                              u8 *digest, struct crypto_wait *wait)
 162 {
 163         int r;
 164
 165         if (unlikely(v->salt_size && (!v->version))) {
 166                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 167
 168                 if (r < 0) {
 169                         DMERR("%s failed updating salt: %d", __func__, r);
 170                         goto out;
 171                 }
 172         }
 173
 174         ahash_request_set_crypt(req, NULL, digest, 0);
 175         r = crypto_wait_req(crypto_ahash_final(req), wait);
 176 out:
 177         return r;
 178 }
 179
 180 int verity_hash(struct dm_verity *v, struct ahash_request *req,
 181                 const u8 *data, size_t len, u8 *digest)
 182 {
 183         int r;
 184         struct crypto_wait wait;
 185
 186         r = verity_hash_init(v, req, &wait);
 187         if (unlikely(r < 0))
 188                 goto out;
 189
 190         r = verity_hash_update(v, req, data, len, &wait);
 191         if (unlikely(r < 0))
 192                 goto out;
 193
 194         r = verity_hash_final(v, req, digest, &wait);
 195
 196 out:
 197         return r;
 198 }
 199
 200 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 201                                  sector_t *hash_block, unsigned int *offset)
 202 {
 203         sector_t position = verity_position_at_level(v, block, level);
 204         unsigned int idx;
 205
 206         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 207
 208         if (!offset)
 209                 return;
 210
 211         idx = position & ((1 << v->hash_per_block_bits) - 1);
 212         if (!v->version)
 213                 *offset = idx * v->digest_size;
 214         else
 215                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 216 }
 217
 218 /*
 219  * Handle verification errors.
 220  */
 221 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 222                              unsigned long long block)
 223 {
 224         char verity_env[DM_VERITY_ENV_LENGTH];
 225         char *envp[] = { verity_env, NULL };
 226         const char *type_str = "";
 227         struct mapped_device *md = dm_table_get_md(v->ti->table);
 228
 229         /* Corruption should be visible in device status in all modes */
 230         v->hash_failed = true;
 231
 232         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 233                 goto out;
 234
 235         v->corrupted_errs++;
 236
 237         switch (type) {
 238         case DM_VERITY_BLOCK_TYPE_DATA:
 239                 type_str = "data";
 240                 break;
 241         case DM_VERITY_BLOCK_TYPE_METADATA:
 242                 type_str = "metadata";
 243                 break;
 244         default:
 245                 BUG();
 246         }
 247
 248         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 249                     type_str, block);
 250
 251         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
 252                 DMERR("%s: reached maximum errors", v->data_dev->name);
 253
 254         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 255                 DM_VERITY_ENV_VAR_NAME, type, block);
 256
 257         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 258
 259 out:
 260         if (v->mode == DM_VERITY_MODE_LOGGING)
 261                 return 0;
 262
 263         if (v->mode == DM_VERITY_MODE_RESTART)
 264                 kernel_restart("dm-verity device corrupted");
 265
 266         if (v->mode == DM_VERITY_MODE_PANIC)
 267                 panic("dm-verity device corrupted");
 268
 269         return 1;
 270 }
 271
 272 /*
 273  * Verify hash of a metadata block pertaining to the specified data block
 274  * ("block" argument) at a specified level ("level" argument).
 275  *
 276  * On successful return, verity_io_want_digest(v, io) contains the hash value
 277  * for a lower tree level or for the data block (if we're at the lowest level).
 278  *
 279  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 280  * If "skip_unverified" is false, unverified buffer is hashed and verified
 281  * against current value of verity_io_want_digest(v, io).
 282  */
 283 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 284                                sector_t block, int level, bool skip_unverified,
 285                                u8 *want_digest)
 286 {
 287         struct dm_buffer *buf;
 288         struct buffer_aux *aux;
 289         u8 *data;
 290         int r;
 291         sector_t hash_block;
 292         unsigned int offset;
 293
 294         verity_hash_at_level(v, block, level, &hash_block, &offset);
 295
 296         if (static_branch_unlikely(&use_tasklet_enabled) && io->in_tasklet) {
 297                 data = dm_bufio_get(v->bufio, hash_block, &buf);
 298                 if (data == NULL) {
 299                         /*
 300                          * In tasklet and the hash was not in the bufio cache.
 301                          * Return early and resume execution from a work-queue
 302                          * to read the hash from disk.
 303                          */
 304                         return -EAGAIN;
 305                 }
 306         } else
 307                 data = dm_bufio_read(v->bufio, hash_block, &buf);
 308
 309         if (IS_ERR(data))
 310                 return PTR_ERR(data);
 311
 312         aux = dm_bufio_get_aux_data(buf);
 313
 314         if (!aux->hash_verified) {
 315                 if (skip_unverified) {
 316                         r = 1;
 317                         goto release_ret_r;
 318                 }
 319
 320                 r = verity_hash(v, verity_io_hash_req(v, io),
 321                                 data, 1 << v->hash_dev_block_bits,
 322                                 verity_io_real_digest(v, io));
 323                 if (unlikely(r < 0))
 324                         goto release_ret_r;
 325
 326                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 327                                   v->digest_size) == 0))
 328                         aux->hash_verified = 1;
 329                 else if (static_branch_unlikely(&use_tasklet_enabled) &&
 330                          io->in_tasklet) {
 331                         /*
 332                          * Error handling code (FEC included) cannot be run in a
 333                          * tasklet since it may sleep, so fallback to work-queue.
 334                          */
 335                         r = -EAGAIN;
 336                         goto release_ret_r;
 337                 } else if (verity_fec_decode(v, io, 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("%s crypto op failed: %d", __func__, 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 int 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 int 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
 689                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 690                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 691
 692                 if (!i) {
 693                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 694
 695                         cluster >>= v->data_dev_block_bits;
 696                         if (unlikely(!cluster))
 697                                 goto no_prefetch_cluster;
 698
 699                         if (unlikely(cluster & (cluster - 1)))
 700                                 cluster = 1 << __fls(cluster);
 701
 702                         hash_block_start &= ~(sector_t)(cluster - 1);
 703                         hash_block_end |= cluster - 1;
 704                         if (unlikely(hash_block_end >= v->hash_blocks))
 705                                 hash_block_end = v->hash_blocks - 1;
 706                 }
 707 no_prefetch_cluster:
 708                 dm_bufio_prefetch(v->bufio, hash_block_start,
 709                                   hash_block_end - hash_block_start + 1);
 710         }
 711
 712         kfree(pw);
 713 }
 714
 715 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 716 {
 717         sector_t block = io->block;
 718         unsigned int n_blocks = io->n_blocks;
 719         struct dm_verity_prefetch_work *pw;
 720
 721         if (v->validated_blocks) {
 722                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 723                         block++;
 724                         n_blocks--;
 725                 }
 726                 while (n_blocks && test_bit(block + n_blocks - 1,
 727                                             v->validated_blocks))
 728                         n_blocks--;
 729                 if (!n_blocks)
 730                         return;
 731         }
 732
 733         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 734                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 735
 736         if (!pw)
 737                 return;
 738
 739         INIT_WORK(&pw->work, verity_prefetch_io);
 740         pw->v = v;
 741         pw->block = block;
 742         pw->n_blocks = n_blocks;
 743         queue_work(v->verify_wq, &pw->work);
 744 }
 745
 746 /*
 747  * Bio map function. It allocates dm_verity_io structure and bio vector and
 748  * fills them. Then it issues prefetches and the I/O.
 749  */
 750 static int verity_map(struct dm_target *ti, struct bio *bio)
 751 {
 752         struct dm_verity *v = ti->private;
 753         struct dm_verity_io *io;
 754
 755         bio_set_dev(bio, v->data_dev->bdev);
 756         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 757
 758         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 759             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 760                 DMERR_LIMIT("unaligned io");
 761                 return DM_MAPIO_KILL;
 762         }
 763
 764         if (bio_end_sector(bio) >>
 765             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 766                 DMERR_LIMIT("io out of range");
 767                 return DM_MAPIO_KILL;
 768         }
 769
 770         if (bio_data_dir(bio) == WRITE)
 771                 return DM_MAPIO_KILL;
 772
 773         io = dm_per_bio_data(bio, ti->per_io_data_size);
 774         io->v = v;
 775         io->orig_bi_end_io = bio->bi_end_io;
 776         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 777         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 778
 779         bio->bi_end_io = verity_end_io;
 780         bio->bi_private = io;
 781         io->iter = bio->bi_iter;
 782
 783         verity_submit_prefetch(v, io);
 784
 785         submit_bio_noacct(bio);
 786
 787         return DM_MAPIO_SUBMITTED;
 788 }
 789
 790 /*
 791  * Status: V (valid) or C (corruption found)
 792  */
 793 static void verity_status(struct dm_target *ti, status_type_t type,
 794                           unsigned int status_flags, char *result, unsigned int maxlen)
 795 {
 796         struct dm_verity *v = ti->private;
 797         unsigned int args = 0;
 798         unsigned int sz = 0;
 799         unsigned int x;
 800
 801         switch (type) {
 802         case STATUSTYPE_INFO:
 803                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 804                 break;
 805         case STATUSTYPE_TABLE:
 806                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 807                         v->version,
 808                         v->data_dev->name,
 809                         v->hash_dev->name,
 810                         1 << v->data_dev_block_bits,
 811                         1 << v->hash_dev_block_bits,
 812                         (unsigned long long)v->data_blocks,
 813                         (unsigned long long)v->hash_start,
 814                         v->alg_name
 815                         );
 816                 for (x = 0; x < v->digest_size; x++)
 817                         DMEMIT("%02x", v->root_digest[x]);
 818                 DMEMIT(" ");
 819                 if (!v->salt_size)
 820                         DMEMIT("-");
 821                 else
 822                         for (x = 0; x < v->salt_size; x++)
 823                                 DMEMIT("%02x", v->salt[x]);
 824                 if (v->mode != DM_VERITY_MODE_EIO)
 825                         args++;
 826                 if (verity_fec_is_enabled(v))
 827                         args += DM_VERITY_OPTS_FEC;
 828                 if (v->zero_digest)
 829                         args++;
 830                 if (v->validated_blocks)
 831                         args++;
 832                 if (v->use_tasklet)
 833                         args++;
 834                 if (v->signature_key_desc)
 835                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 836                 if (!args)
 837                         return;
 838                 DMEMIT(" %u", args);
 839                 if (v->mode != DM_VERITY_MODE_EIO) {
 840                         DMEMIT(" ");
 841                         switch (v->mode) {
 842                         case DM_VERITY_MODE_LOGGING:
 843                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 844                                 break;
 845                         case DM_VERITY_MODE_RESTART:
 846                                 DMEMIT(DM_VERITY_OPT_RESTART);
 847                                 break;
 848                         case DM_VERITY_MODE_PANIC:
 849                                 DMEMIT(DM_VERITY_OPT_PANIC);
 850                                 break;
 851                         default:
 852                                 BUG();
 853                         }
 854                 }
 855                 if (v->zero_digest)
 856                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 857                 if (v->validated_blocks)
 858                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 859                 if (v->use_tasklet)
 860                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 861                 sz = verity_fec_status_table(v, sz, result, maxlen);
 862                 if (v->signature_key_desc)
 863                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 864                                 " %s", v->signature_key_desc);
 865                 break;
 866
 867         case STATUSTYPE_IMA:
 868                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 869                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 870                 DMEMIT(",verity_version=%u", v->version);
 871                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 872                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 873                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 874
 875                 DMEMIT(",root_digest=");
 876                 for (x = 0; x < v->digest_size; x++)
 877                         DMEMIT("%02x", v->root_digest[x]);
 878
 879                 DMEMIT(",salt=");
 880                 if (!v->salt_size)
 881                         DMEMIT("-");
 882                 else
 883                         for (x = 0; x < v->salt_size; x++)
 884                                 DMEMIT("%02x", v->salt[x]);
 885
 886                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 887                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 888                 if (v->signature_key_desc)
 889                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 890
 891                 if (v->mode != DM_VERITY_MODE_EIO) {
 892                         DMEMIT(",verity_mode=");
 893                         switch (v->mode) {
 894                         case DM_VERITY_MODE_LOGGING:
 895                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 896                                 break;
 897                         case DM_VERITY_MODE_RESTART:
 898                                 DMEMIT(DM_VERITY_OPT_RESTART);
 899                                 break;
 900                         case DM_VERITY_MODE_PANIC:
 901                                 DMEMIT(DM_VERITY_OPT_PANIC);
 902                                 break;
 903                         default:
 904                                 DMEMIT("invalid");
 905                         }
 906                 }
 907                 DMEMIT(";");
 908                 break;
 909         }
 910 }
 911
 912 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 913 {
 914         struct dm_verity *v = ti->private;
 915
 916         *bdev = v->data_dev->bdev;
 917
 918         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 919                 return 1;
 920         return 0;
 921 }
 922
 923 static int verity_iterate_devices(struct dm_target *ti,
 924                                   iterate_devices_callout_fn fn, void *data)
 925 {
 926         struct dm_verity *v = ti->private;
 927
 928         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 929 }
 930
 931 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 932 {
 933         struct dm_verity *v = ti->private;
 934
 935         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 936                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 937
 938         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 939                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 940
 941         blk_limits_io_min(limits, limits->logical_block_size);
 942 }
 943
 944 static void verity_dtr(struct dm_target *ti)
 945 {
 946         struct dm_verity *v = ti->private;
 947
 948         if (v->verify_wq)
 949                 destroy_workqueue(v->verify_wq);
 950
 951         if (v->bufio)
 952                 dm_bufio_client_destroy(v->bufio);
 953
 954         kvfree(v->validated_blocks);
 955         kfree(v->salt);
 956         kfree(v->root_digest);
 957         kfree(v->zero_digest);
 958
 959         if (v->tfm)
 960                 crypto_free_ahash(v->tfm);
 961
 962         kfree(v->alg_name);
 963
 964         if (v->hash_dev)
 965                 dm_put_device(ti, v->hash_dev);
 966
 967         if (v->data_dev)
 968                 dm_put_device(ti, v->data_dev);
 969
 970         verity_fec_dtr(v);
 971
 972         kfree(v->signature_key_desc);
 973
 974         if (v->use_tasklet)
 975                 static_branch_dec(&use_tasklet_enabled);
 976
 977         kfree(v);
 978 }
 979
 980 static int verity_alloc_most_once(struct dm_verity *v)
 981 {
 982         struct dm_target *ti = v->ti;
 983
 984         /* the bitset can only handle INT_MAX blocks */
 985         if (v->data_blocks > INT_MAX) {
 986                 ti->error = "device too large to use check_at_most_once";
 987                 return -E2BIG;
 988         }
 989
 990         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
 991                                        sizeof(unsigned long),
 992                                        GFP_KERNEL);
 993         if (!v->validated_blocks) {
 994                 ti->error = "failed to allocate bitset for check_at_most_once";
 995                 return -ENOMEM;
 996         }
 997
 998         return 0;
 999 }
1000
1001 static int verity_alloc_zero_digest(struct dm_verity *v)
1002 {
1003         int r = -ENOMEM;
1004         struct ahash_request *req;
1005         u8 *zero_data;
1006
1007         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1008
1009         if (!v->zero_digest)
1010                 return r;
1011
1012         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
1013
1014         if (!req)
1015                 return r; /* verity_dtr will free zero_digest */
1016
1017         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1018
1019         if (!zero_data)
1020                 goto out;
1021
1022         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
1023                         v->zero_digest);
1024
1025 out:
1026         kfree(req);
1027         kfree(zero_data);
1028
1029         return r;
1030 }
1031
1032 static inline bool verity_is_verity_mode(const char *arg_name)
1033 {
1034         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1035                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1036                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1037 }
1038
1039 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1040 {
1041         if (v->mode)
1042                 return -EINVAL;
1043
1044         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1045                 v->mode = DM_VERITY_MODE_LOGGING;
1046         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1047                 v->mode = DM_VERITY_MODE_RESTART;
1048         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1049                 v->mode = DM_VERITY_MODE_PANIC;
1050
1051         return 0;
1052 }
1053
1054 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1055                                  struct dm_verity_sig_opts *verify_args,
1056                                  bool only_modifier_opts)
1057 {
1058         int r = 0;
1059         unsigned int argc;
1060         struct dm_target *ti = v->ti;
1061         const char *arg_name;
1062
1063         static const struct dm_arg _args[] = {
1064                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1065         };
1066
1067         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1068         if (r)
1069                 return -EINVAL;
1070
1071         if (!argc)
1072                 return 0;
1073
1074         do {
1075                 arg_name = dm_shift_arg(as);
1076                 argc--;
1077
1078                 if (verity_is_verity_mode(arg_name)) {
1079                         if (only_modifier_opts)
1080                                 continue;
1081                         r = verity_parse_verity_mode(v, arg_name);
1082                         if (r) {
1083                                 ti->error = "Conflicting error handling parameters";
1084                                 return r;
1085                         }
1086                         continue;
1087
1088                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1089                         if (only_modifier_opts)
1090                                 continue;
1091                         r = verity_alloc_zero_digest(v);
1092                         if (r) {
1093                                 ti->error = "Cannot allocate zero digest";
1094                                 return r;
1095                         }
1096                         continue;
1097
1098                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1099                         if (only_modifier_opts)
1100                                 continue;
1101                         r = verity_alloc_most_once(v);
1102                         if (r)
1103                                 return r;
1104                         continue;
1105
1106                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1107                         v->use_tasklet = true;
1108                         static_branch_inc(&use_tasklet_enabled);
1109                         continue;
1110
1111                 } else if (verity_is_fec_opt_arg(arg_name)) {
1112                         if (only_modifier_opts)
1113                                 continue;
1114                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1115                         if (r)
1116                                 return r;
1117                         continue;
1118
1119                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1120                         if (only_modifier_opts)
1121                                 continue;
1122                         r = verity_verify_sig_parse_opt_args(as, v,
1123                                                              verify_args,
1124                                                              &argc, arg_name);
1125                         if (r)
1126                                 return r;
1127                         continue;
1128
1129                 } else if (only_modifier_opts) {
1130                         /*
1131                          * Ignore unrecognized opt, could easily be an extra
1132                          * argument to an option whose parsing was skipped.
1133                          * Normal parsing (@only_modifier_opts=false) will
1134                          * properly parse all options (and their extra args).
1135                          */
1136                         continue;
1137                 }
1138
1139                 DMERR("Unrecognized verity feature request: %s", arg_name);
1140                 ti->error = "Unrecognized verity feature request";
1141                 return -EINVAL;
1142         } while (argc && !r);
1143
1144         return r;
1145 }
1146
1147 /*
1148  * Target parameters:
1149  *      <version>       The current format is version 1.
1150  *                      Vsn 0 is compatible with original Chromium OS releases.
1151  *      <data device>
1152  *      <hash device>
1153  *      <data block size>
1154  *      <hash block size>
1155  *      <the number of data blocks>
1156  *      <hash start block>
1157  *      <algorithm>
1158  *      <digest>
1159  *      <salt>          Hex string or "-" if no salt.
1160  */
1161 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1162 {
1163         struct dm_verity *v;
1164         struct dm_verity_sig_opts verify_args = {0};
1165         struct dm_arg_set as;
1166         unsigned int num;
1167         unsigned long long num_ll;
1168         int r;
1169         int i;
1170         sector_t hash_position;
1171         char dummy;
1172         char *root_hash_digest_to_validate;
1173
1174         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1175         if (!v) {
1176                 ti->error = "Cannot allocate verity structure";
1177                 return -ENOMEM;
1178         }
1179         ti->private = v;
1180         v->ti = ti;
1181
1182         r = verity_fec_ctr_alloc(v);
1183         if (r)
1184                 goto bad;
1185
1186         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
1187                 ti->error = "Device must be readonly";
1188                 r = -EINVAL;
1189                 goto bad;
1190         }
1191
1192         if (argc < 10) {
1193                 ti->error = "Not enough arguments";
1194                 r = -EINVAL;
1195                 goto bad;
1196         }
1197
1198         /* Parse optional parameters that modify primary args */
1199         if (argc > 10) {
1200                 as.argc = argc - 10;
1201                 as.argv = argv + 10;
1202                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1203                 if (r < 0)
1204                         goto bad;
1205         }
1206
1207         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1208             num > 1) {
1209                 ti->error = "Invalid version";
1210                 r = -EINVAL;
1211                 goto bad;
1212         }
1213         v->version = num;
1214
1215         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1216         if (r) {
1217                 ti->error = "Data device lookup failed";
1218                 goto bad;
1219         }
1220
1221         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1222         if (r) {
1223                 ti->error = "Hash device lookup failed";
1224                 goto bad;
1225         }
1226
1227         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1228             !num || (num & (num - 1)) ||
1229             num < bdev_logical_block_size(v->data_dev->bdev) ||
1230             num > PAGE_SIZE) {
1231                 ti->error = "Invalid data device block size";
1232                 r = -EINVAL;
1233                 goto bad;
1234         }
1235         v->data_dev_block_bits = __ffs(num);
1236
1237         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1238             !num || (num & (num - 1)) ||
1239             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1240             num > INT_MAX) {
1241                 ti->error = "Invalid hash device block size";
1242                 r = -EINVAL;
1243                 goto bad;
1244         }
1245         v->hash_dev_block_bits = __ffs(num);
1246
1247         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1248             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1249             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1250                 ti->error = "Invalid data blocks";
1251                 r = -EINVAL;
1252                 goto bad;
1253         }
1254         v->data_blocks = num_ll;
1255
1256         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1257                 ti->error = "Data device is too small";
1258                 r = -EINVAL;
1259                 goto bad;
1260         }
1261
1262         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1263             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1264             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1265                 ti->error = "Invalid hash start";
1266                 r = -EINVAL;
1267                 goto bad;
1268         }
1269         v->hash_start = num_ll;
1270
1271         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1272         if (!v->alg_name) {
1273                 ti->error = "Cannot allocate algorithm name";
1274                 r = -ENOMEM;
1275                 goto bad;
1276         }
1277
1278         v->tfm = crypto_alloc_ahash(v->alg_name, 0,
1279                                     v->use_tasklet ? CRYPTO_ALG_ASYNC : 0);
1280         if (IS_ERR(v->tfm)) {
1281                 ti->error = "Cannot initialize hash function";
1282                 r = PTR_ERR(v->tfm);
1283                 v->tfm = NULL;
1284                 goto bad;
1285         }
1286
1287         /*
1288          * dm-verity performance can vary greatly depending on which hash
1289          * algorithm implementation is used.  Help people debug performance
1290          * problems by logging the ->cra_driver_name.
1291          */
1292         DMINFO("%s using implementation \"%s\"", v->alg_name,
1293                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1294
1295         v->digest_size = crypto_ahash_digestsize(v->tfm);
1296         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1297                 ti->error = "Digest size too big";
1298                 r = -EINVAL;
1299                 goto bad;
1300         }
1301         v->ahash_reqsize = sizeof(struct ahash_request) +
1302                 crypto_ahash_reqsize(v->tfm);
1303
1304         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1305         if (!v->root_digest) {
1306                 ti->error = "Cannot allocate root digest";
1307                 r = -ENOMEM;
1308                 goto bad;
1309         }
1310         if (strlen(argv[8]) != v->digest_size * 2 ||
1311             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1312                 ti->error = "Invalid root digest";
1313                 r = -EINVAL;
1314                 goto bad;
1315         }
1316         root_hash_digest_to_validate = argv[8];
1317
1318         if (strcmp(argv[9], "-")) {
1319                 v->salt_size = strlen(argv[9]) / 2;
1320                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1321                 if (!v->salt) {
1322                         ti->error = "Cannot allocate salt";
1323                         r = -ENOMEM;
1324                         goto bad;
1325                 }
1326                 if (strlen(argv[9]) != v->salt_size * 2 ||
1327                     hex2bin(v->salt, argv[9], v->salt_size)) {
1328                         ti->error = "Invalid salt";
1329                         r = -EINVAL;
1330                         goto bad;
1331                 }
1332         }
1333
1334         argv += 10;
1335         argc -= 10;
1336
1337         /* Optional parameters */
1338         if (argc) {
1339                 as.argc = argc;
1340                 as.argv = argv;
1341                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1342                 if (r < 0)
1343                         goto bad;
1344         }
1345
1346         /* Root hash signature is  a optional parameter*/
1347         r = verity_verify_root_hash(root_hash_digest_to_validate,
1348                                     strlen(root_hash_digest_to_validate),
1349                                     verify_args.sig,
1350                                     verify_args.sig_size);
1351         if (r < 0) {
1352                 ti->error = "Root hash verification failed";
1353                 goto bad;
1354         }
1355         v->hash_per_block_bits =
1356                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1357
1358         v->levels = 0;
1359         if (v->data_blocks)
1360                 while (v->hash_per_block_bits * v->levels < 64 &&
1361                        (unsigned long long)(v->data_blocks - 1) >>
1362                        (v->hash_per_block_bits * v->levels))
1363                         v->levels++;
1364
1365         if (v->levels > DM_VERITY_MAX_LEVELS) {
1366                 ti->error = "Too many tree levels";
1367                 r = -E2BIG;
1368                 goto bad;
1369         }
1370
1371         hash_position = v->hash_start;
1372         for (i = v->levels - 1; i >= 0; i--) {
1373                 sector_t s;
1374
1375                 v->hash_level_block[i] = hash_position;
1376                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1377                                         >> ((i + 1) * v->hash_per_block_bits);
1378                 if (hash_position + s < hash_position) {
1379                         ti->error = "Hash device offset overflow";
1380                         r = -E2BIG;
1381                         goto bad;
1382                 }
1383                 hash_position += s;
1384         }
1385         v->hash_blocks = hash_position;
1386
1387         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1388                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1389                 dm_bufio_alloc_callback, NULL,
1390                 v->use_tasklet ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1391         if (IS_ERR(v->bufio)) {
1392                 ti->error = "Cannot initialize dm-bufio";
1393                 r = PTR_ERR(v->bufio);
1394                 v->bufio = NULL;
1395                 goto bad;
1396         }
1397
1398         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1399                 ti->error = "Hash device is too small";
1400                 r = -E2BIG;
1401                 goto bad;
1402         }
1403
1404         /*
1405          * Using WQ_HIGHPRI improves throughput and completion latency by
1406          * reducing wait times when reading from a dm-verity device.
1407          *
1408          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1409          * allows verify_wq to preempt softirq since verification in tasklet
1410          * will fall-back to using it for error handling (or if the bufio cache
1411          * doesn't have required hashes).
1412          */
1413         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1414         if (!v->verify_wq) {
1415                 ti->error = "Cannot allocate workqueue";
1416                 r = -ENOMEM;
1417                 goto bad;
1418         }
1419
1420         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1421                                 v->ahash_reqsize + v->digest_size * 2;
1422
1423         r = verity_fec_ctr(v);
1424         if (r)
1425                 goto bad;
1426
1427         ti->per_io_data_size = roundup(ti->per_io_data_size,
1428                                        __alignof__(struct dm_verity_io));
1429
1430         verity_verify_sig_opts_cleanup(&verify_args);
1431
1432         return 0;
1433
1434 bad:
1435
1436         verity_verify_sig_opts_cleanup(&verify_args);
1437         verity_dtr(ti);
1438
1439         return r;
1440 }
1441
1442 /*
1443  * Check whether a DM target is a verity target.
1444  */
1445 bool dm_is_verity_target(struct dm_target *ti)
1446 {
1447         return ti->type->module == THIS_MODULE;
1448 }
1449
1450 /*
1451  * Get the verity mode (error behavior) of a verity target.
1452  *
1453  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1454  * target.
1455  */
1456 int dm_verity_get_mode(struct dm_target *ti)
1457 {
1458         struct dm_verity *v = ti->private;
1459
1460         if (!dm_is_verity_target(ti))
1461                 return -EINVAL;
1462
1463         return v->mode;
1464 }
1465
1466 /*
1467  * Get the root digest of a verity target.
1468  *
1469  * Returns a copy of the root digest, the caller is responsible for
1470  * freeing the memory of the digest.
1471  */
1472 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1473 {
1474         struct dm_verity *v = ti->private;
1475
1476         if (!dm_is_verity_target(ti))
1477                 return -EINVAL;
1478
1479         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1480         if (*root_digest == NULL)
1481                 return -ENOMEM;
1482
1483         *digest_size = v->digest_size;
1484
1485         return 0;
1486 }
1487
1488 static struct target_type verity_target = {
1489         .name           = "verity",
1490         .features       = DM_TARGET_IMMUTABLE,
1491         .version        = {1, 9, 0},
1492         .module         = THIS_MODULE,
1493         .ctr            = verity_ctr,
1494         .dtr            = verity_dtr,
1495         .map            = verity_map,
1496         .status         = verity_status,
1497         .prepare_ioctl  = verity_prepare_ioctl,
1498         .iterate_devices = verity_iterate_devices,
1499         .io_hints       = verity_io_hints,
1500 };
1501
1502 static int __init dm_verity_init(void)
1503 {
1504         int r;
1505
1506         r = dm_register_target(&verity_target);
1507         if (r < 0)
1508                 DMERR("register failed %d", r);
1509
1510         return r;
1511 }
1512
1513 static void __exit dm_verity_exit(void)
1514 {
1515         dm_unregister_target(&verity_target);
1516 }
1517
1518 module_init(dm_verity_init);
1519 module_exit(dm_verity_exit);
1520
1521 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1522 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1523 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1524 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1525 MODULE_LICENSE("GPL");