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