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
  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              (3 + 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         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 479
 480         for (b = 0; b < io->n_blocks; b++) {
 481                 int r;
 482                 sector_t cur_block = io->block + b;
 483                 struct ahash_request *req = verity_io_hash_req(v, io);
 484
 485                 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 486                     likely(test_bit(cur_block, v->validated_blocks))) {
 487                         verity_bv_skip_block(v, io, &io->iter);
 488                         continue;
 489                 }
 490
 491                 r = verity_hash_for_block(v, io, cur_block,
 492                                           verity_io_want_digest(v, io),
 493                                           &is_zero);
 494                 if (unlikely(r < 0))
 495                         return r;
 496
 497                 if (is_zero) {
 498                         /*
 499                          * If we expect a zero block, don't validate, just
 500                          * return zeros.
 501                          */
 502                         r = verity_for_bv_block(v, io, &io->iter,
 503                                                 verity_bv_zero);
 504                         if (unlikely(r < 0))
 505                                 return r;
 506
 507                         continue;
 508                 }
 509
 510                 r = verity_hash_init(v, req, &wait);
 511                 if (unlikely(r < 0))
 512                         return r;
 513
 514                 start = io->iter;
 515                 r = verity_for_io_block(v, io, &io->iter, &wait);
 516                 if (unlikely(r < 0))
 517                         return r;
 518
 519                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 520                                         &wait);
 521                 if (unlikely(r < 0))
 522                         return r;
 523
 524                 if (likely(memcmp(verity_io_real_digest(v, io),
 525                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 526                         if (v->validated_blocks)
 527                                 set_bit(cur_block, v->validated_blocks);
 528                         continue;
 529                 }
 530                 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 531                                            cur_block, NULL, &start) == 0)
 532                         continue;
 533                 else {
 534                         if (bio->bi_status) {
 535                                 /*
 536                                  * Error correction failed; Just return error
 537                                  */
 538                                 return -EIO;
 539                         }
 540                         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 541                                               cur_block))
 542                                 return -EIO;
 543                 }
 544         }
 545
 546         return 0;
 547 }
 548
 549 /*
 550  * Skip verity work in response to I/O error when system is shutting down.
 551  */
 552 static inline bool verity_is_system_shutting_down(void)
 553 {
 554         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 555                 || system_state == SYSTEM_RESTART;
 556 }
 557
 558 /*
 559  * End one "io" structure with a given error.
 560  */
 561 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 562 {
 563         struct dm_verity *v = io->v;
 564         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 565
 566         bio->bi_end_io = io->orig_bi_end_io;
 567         bio->bi_status = status;
 568
 569         verity_fec_finish_io(io);
 570
 571         bio_endio(bio);
 572 }
 573
 574 static void verity_work(struct work_struct *w)
 575 {
 576         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 577
 578         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 579 }
 580
 581 static void verity_end_io(struct bio *bio)
 582 {
 583         struct dm_verity_io *io = bio->bi_private;
 584
 585         if (bio->bi_status &&
 586             (!verity_fec_is_enabled(io->v) ||
 587              verity_is_system_shutting_down() ||
 588              (bio->bi_opf & REQ_RAHEAD))) {
 589                 verity_finish_io(io, bio->bi_status);
 590                 return;
 591         }
 592
 593         INIT_WORK(&io->work, verity_work);
 594         queue_work(io->v->verify_wq, &io->work);
 595 }
 596
 597 /*
 598  * Prefetch buffers for the specified io.
 599  * The root buffer is not prefetched, it is assumed that it will be cached
 600  * all the time.
 601  */
 602 static void verity_prefetch_io(struct work_struct *work)
 603 {
 604         struct dm_verity_prefetch_work *pw =
 605                 container_of(work, struct dm_verity_prefetch_work, work);
 606         struct dm_verity *v = pw->v;
 607         int i;
 608
 609         for (i = v->levels - 2; i >= 0; i--) {
 610                 sector_t hash_block_start;
 611                 sector_t hash_block_end;
 612                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 613                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 614                 if (!i) {
 615                         unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
 616
 617                         cluster >>= v->data_dev_block_bits;
 618                         if (unlikely(!cluster))
 619                                 goto no_prefetch_cluster;
 620
 621                         if (unlikely(cluster & (cluster - 1)))
 622                                 cluster = 1 << __fls(cluster);
 623
 624                         hash_block_start &= ~(sector_t)(cluster - 1);
 625                         hash_block_end |= cluster - 1;
 626                         if (unlikely(hash_block_end >= v->hash_blocks))
 627                                 hash_block_end = v->hash_blocks - 1;
 628                 }
 629 no_prefetch_cluster:
 630                 dm_bufio_prefetch(v->bufio, hash_block_start,
 631                                   hash_block_end - hash_block_start + 1);
 632         }
 633
 634         kfree(pw);
 635 }
 636
 637 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 638 {
 639         sector_t block = io->block;
 640         unsigned int n_blocks = io->n_blocks;
 641         struct dm_verity_prefetch_work *pw;
 642
 643         if (v->validated_blocks) {
 644                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 645                         block++;
 646                         n_blocks--;
 647                 }
 648                 while (n_blocks && test_bit(block + n_blocks - 1,
 649                                             v->validated_blocks))
 650                         n_blocks--;
 651                 if (!n_blocks)
 652                         return;
 653         }
 654
 655         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 656                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 657
 658         if (!pw)
 659                 return;
 660
 661         INIT_WORK(&pw->work, verity_prefetch_io);
 662         pw->v = v;
 663         pw->block = block;
 664         pw->n_blocks = n_blocks;
 665         queue_work(v->verify_wq, &pw->work);
 666 }
 667
 668 /*
 669  * Bio map function. It allocates dm_verity_io structure and bio vector and
 670  * fills them. Then it issues prefetches and the I/O.
 671  */
 672 static int verity_map(struct dm_target *ti, struct bio *bio)
 673 {
 674         struct dm_verity *v = ti->private;
 675         struct dm_verity_io *io;
 676
 677         bio_set_dev(bio, v->data_dev->bdev);
 678         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 679
 680         if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 681             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 682                 DMERR_LIMIT("unaligned io");
 683                 return DM_MAPIO_KILL;
 684         }
 685
 686         if (bio_end_sector(bio) >>
 687             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 688                 DMERR_LIMIT("io out of range");
 689                 return DM_MAPIO_KILL;
 690         }
 691
 692         if (bio_data_dir(bio) == WRITE)
 693                 return DM_MAPIO_KILL;
 694
 695         io = dm_per_bio_data(bio, ti->per_io_data_size);
 696         io->v = v;
 697         io->orig_bi_end_io = bio->bi_end_io;
 698         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 699         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 700
 701         bio->bi_end_io = verity_end_io;
 702         bio->bi_private = io;
 703         io->iter = bio->bi_iter;
 704
 705         verity_fec_init_io(io);
 706
 707         verity_submit_prefetch(v, io);
 708
 709         submit_bio_noacct(bio);
 710
 711         return DM_MAPIO_SUBMITTED;
 712 }
 713
 714 /*
 715  * Status: V (valid) or C (corruption found)
 716  */
 717 static void verity_status(struct dm_target *ti, status_type_t type,
 718                           unsigned status_flags, char *result, unsigned maxlen)
 719 {
 720         struct dm_verity *v = ti->private;
 721         unsigned args = 0;
 722         unsigned sz = 0;
 723         unsigned x;
 724
 725         switch (type) {
 726         case STATUSTYPE_INFO:
 727                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 728                 break;
 729         case STATUSTYPE_TABLE:
 730                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 731                         v->version,
 732                         v->data_dev->name,
 733                         v->hash_dev->name,
 734                         1 << v->data_dev_block_bits,
 735                         1 << v->hash_dev_block_bits,
 736                         (unsigned long long)v->data_blocks,
 737                         (unsigned long long)v->hash_start,
 738                         v->alg_name
 739                         );
 740                 for (x = 0; x < v->digest_size; x++)
 741                         DMEMIT("%02x", v->root_digest[x]);
 742                 DMEMIT(" ");
 743                 if (!v->salt_size)
 744                         DMEMIT("-");
 745                 else
 746                         for (x = 0; x < v->salt_size; x++)
 747                                 DMEMIT("%02x", v->salt[x]);
 748                 if (v->mode != DM_VERITY_MODE_EIO)
 749                         args++;
 750                 if (verity_fec_is_enabled(v))
 751                         args += DM_VERITY_OPTS_FEC;
 752                 if (v->zero_digest)
 753                         args++;
 754                 if (v->validated_blocks)
 755                         args++;
 756                 if (v->signature_key_desc)
 757                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 758                 if (!args)
 759                         return;
 760                 DMEMIT(" %u", args);
 761                 if (v->mode != DM_VERITY_MODE_EIO) {
 762                         DMEMIT(" ");
 763                         switch (v->mode) {
 764                         case DM_VERITY_MODE_LOGGING:
 765                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 766                                 break;
 767                         case DM_VERITY_MODE_RESTART:
 768                                 DMEMIT(DM_VERITY_OPT_RESTART);
 769                                 break;
 770                         case DM_VERITY_MODE_PANIC:
 771                                 DMEMIT(DM_VERITY_OPT_PANIC);
 772                                 break;
 773                         default:
 774                                 BUG();
 775                         }
 776                 }
 777                 if (v->zero_digest)
 778                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 779                 if (v->validated_blocks)
 780                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 781                 sz = verity_fec_status_table(v, sz, result, maxlen);
 782                 if (v->signature_key_desc)
 783                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 784                                 " %s", v->signature_key_desc);
 785                 break;
 786         }
 787 }
 788
 789 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 790 {
 791         struct dm_verity *v = ti->private;
 792
 793         *bdev = v->data_dev->bdev;
 794
 795         if (v->data_start ||
 796             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
 797                 return 1;
 798         return 0;
 799 }
 800
 801 static int verity_iterate_devices(struct dm_target *ti,
 802                                   iterate_devices_callout_fn fn, void *data)
 803 {
 804         struct dm_verity *v = ti->private;
 805
 806         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 807 }
 808
 809 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 810 {
 811         struct dm_verity *v = ti->private;
 812
 813         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 814                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 815
 816         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 817                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 818
 819         blk_limits_io_min(limits, limits->logical_block_size);
 820 }
 821
 822 static void verity_dtr(struct dm_target *ti)
 823 {
 824         struct dm_verity *v = ti->private;
 825
 826         if (v->verify_wq)
 827                 destroy_workqueue(v->verify_wq);
 828
 829         if (v->bufio)
 830                 dm_bufio_client_destroy(v->bufio);
 831
 832         kvfree(v->validated_blocks);
 833         kfree(v->salt);
 834         kfree(v->root_digest);
 835         kfree(v->zero_digest);
 836
 837         if (v->tfm)
 838                 crypto_free_ahash(v->tfm);
 839
 840         kfree(v->alg_name);
 841
 842         if (v->hash_dev)
 843                 dm_put_device(ti, v->hash_dev);
 844
 845         if (v->data_dev)
 846                 dm_put_device(ti, v->data_dev);
 847
 848         verity_fec_dtr(v);
 849
 850         kfree(v->signature_key_desc);
 851
 852         kfree(v);
 853 }
 854
 855 static int verity_alloc_most_once(struct dm_verity *v)
 856 {
 857         struct dm_target *ti = v->ti;
 858
 859         /* the bitset can only handle INT_MAX blocks */
 860         if (v->data_blocks > INT_MAX) {
 861                 ti->error = "device too large to use check_at_most_once";
 862                 return -E2BIG;
 863         }
 864
 865         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
 866                                        sizeof(unsigned long),
 867                                        GFP_KERNEL);
 868         if (!v->validated_blocks) {
 869                 ti->error = "failed to allocate bitset for check_at_most_once";
 870                 return -ENOMEM;
 871         }
 872
 873         return 0;
 874 }
 875
 876 static int verity_alloc_zero_digest(struct dm_verity *v)
 877 {
 878         int r = -ENOMEM;
 879         struct ahash_request *req;
 880         u8 *zero_data;
 881
 882         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
 883
 884         if (!v->zero_digest)
 885                 return r;
 886
 887         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
 888
 889         if (!req)
 890                 return r; /* verity_dtr will free zero_digest */
 891
 892         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
 893
 894         if (!zero_data)
 895                 goto out;
 896
 897         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
 898                         v->zero_digest);
 899
 900 out:
 901         kfree(req);
 902         kfree(zero_data);
 903
 904         return r;
 905 }
 906
 907 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
 908                                  struct dm_verity_sig_opts *verify_args)
 909 {
 910         int r;
 911         unsigned argc;
 912         struct dm_target *ti = v->ti;
 913         const char *arg_name;
 914
 915         static const struct dm_arg _args[] = {
 916                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
 917         };
 918
 919         r = dm_read_arg_group(_args, as, &argc, &ti->error);
 920         if (r)
 921                 return -EINVAL;
 922
 923         if (!argc)
 924                 return 0;
 925
 926         do {
 927                 arg_name = dm_shift_arg(as);
 928                 argc--;
 929
 930                 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
 931                         v->mode = DM_VERITY_MODE_LOGGING;
 932                         continue;
 933
 934                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
 935                         v->mode = DM_VERITY_MODE_RESTART;
 936                         continue;
 937
 938                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC)) {
 939                         v->mode = DM_VERITY_MODE_PANIC;
 940                         continue;
 941
 942                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
 943                         r = verity_alloc_zero_digest(v);
 944                         if (r) {
 945                                 ti->error = "Cannot allocate zero digest";
 946                                 return r;
 947                         }
 948                         continue;
 949
 950                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
 951                         r = verity_alloc_most_once(v);
 952                         if (r)
 953                                 return r;
 954                         continue;
 955
 956                 } else if (verity_is_fec_opt_arg(arg_name)) {
 957                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
 958                         if (r)
 959                                 return r;
 960                         continue;
 961                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
 962                         r = verity_verify_sig_parse_opt_args(as, v,
 963                                                              verify_args,
 964                                                              &argc, arg_name);
 965                         if (r)
 966                                 return r;
 967                         continue;
 968
 969                 }
 970
 971                 ti->error = "Unrecognized verity feature request";
 972                 return -EINVAL;
 973         } while (argc && !r);
 974
 975         return r;
 976 }
 977
 978 /*
 979  * Target parameters:
 980  *      <version>       The current format is version 1.
 981  *                      Vsn 0 is compatible with original Chromium OS releases.
 982  *      <data device>
 983  *      <hash device>
 984  *      <data block size>
 985  *      <hash block size>
 986  *      <the number of data blocks>
 987  *      <hash start block>
 988  *      <algorithm>
 989  *      <digest>
 990  *      <salt>          Hex string or "-" if no salt.
 991  */
 992 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 993 {
 994         struct dm_verity *v;
 995         struct dm_verity_sig_opts verify_args = {0};
 996         struct dm_arg_set as;
 997         unsigned int num;
 998         unsigned long long num_ll;
 999         int r;
1000         int i;
1001         sector_t hash_position;
1002         char dummy;
1003         char *root_hash_digest_to_validate;
1004
1005         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1006         if (!v) {
1007                 ti->error = "Cannot allocate verity structure";
1008                 return -ENOMEM;
1009         }
1010         ti->private = v;
1011         v->ti = ti;
1012
1013         r = verity_fec_ctr_alloc(v);
1014         if (r)
1015                 goto bad;
1016
1017         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
1018                 ti->error = "Device must be readonly";
1019                 r = -EINVAL;
1020                 goto bad;
1021         }
1022
1023         if (argc < 10) {
1024                 ti->error = "Not enough arguments";
1025                 r = -EINVAL;
1026                 goto bad;
1027         }
1028
1029         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1030             num > 1) {
1031                 ti->error = "Invalid version";
1032                 r = -EINVAL;
1033                 goto bad;
1034         }
1035         v->version = num;
1036
1037         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
1038         if (r) {
1039                 ti->error = "Data device lookup failed";
1040                 goto bad;
1041         }
1042
1043         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
1044         if (r) {
1045                 ti->error = "Hash device lookup failed";
1046                 goto bad;
1047         }
1048
1049         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1050             !num || (num & (num - 1)) ||
1051             num < bdev_logical_block_size(v->data_dev->bdev) ||
1052             num > PAGE_SIZE) {
1053                 ti->error = "Invalid data device block size";
1054                 r = -EINVAL;
1055                 goto bad;
1056         }
1057         v->data_dev_block_bits = __ffs(num);
1058
1059         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1060             !num || (num & (num - 1)) ||
1061             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1062             num > INT_MAX) {
1063                 ti->error = "Invalid hash device block size";
1064                 r = -EINVAL;
1065                 goto bad;
1066         }
1067         v->hash_dev_block_bits = __ffs(num);
1068
1069         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1070             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1071             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1072                 ti->error = "Invalid data blocks";
1073                 r = -EINVAL;
1074                 goto bad;
1075         }
1076         v->data_blocks = num_ll;
1077
1078         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1079                 ti->error = "Data device is too small";
1080                 r = -EINVAL;
1081                 goto bad;
1082         }
1083
1084         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1085             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1086             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1087                 ti->error = "Invalid hash start";
1088                 r = -EINVAL;
1089                 goto bad;
1090         }
1091         v->hash_start = num_ll;
1092
1093         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1094         if (!v->alg_name) {
1095                 ti->error = "Cannot allocate algorithm name";
1096                 r = -ENOMEM;
1097                 goto bad;
1098         }
1099
1100         v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1101         if (IS_ERR(v->tfm)) {
1102                 ti->error = "Cannot initialize hash function";
1103                 r = PTR_ERR(v->tfm);
1104                 v->tfm = NULL;
1105                 goto bad;
1106         }
1107
1108         /*
1109          * dm-verity performance can vary greatly depending on which hash
1110          * algorithm implementation is used.  Help people debug performance
1111          * problems by logging the ->cra_driver_name.
1112          */
1113         DMINFO("%s using implementation \"%s\"", v->alg_name,
1114                crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
1115
1116         v->digest_size = crypto_ahash_digestsize(v->tfm);
1117         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1118                 ti->error = "Digest size too big";
1119                 r = -EINVAL;
1120                 goto bad;
1121         }
1122         v->ahash_reqsize = sizeof(struct ahash_request) +
1123                 crypto_ahash_reqsize(v->tfm);
1124
1125         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1126         if (!v->root_digest) {
1127                 ti->error = "Cannot allocate root digest";
1128                 r = -ENOMEM;
1129                 goto bad;
1130         }
1131         if (strlen(argv[8]) != v->digest_size * 2 ||
1132             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1133                 ti->error = "Invalid root digest";
1134                 r = -EINVAL;
1135                 goto bad;
1136         }
1137         root_hash_digest_to_validate = argv[8];
1138
1139         if (strcmp(argv[9], "-")) {
1140                 v->salt_size = strlen(argv[9]) / 2;
1141                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1142                 if (!v->salt) {
1143                         ti->error = "Cannot allocate salt";
1144                         r = -ENOMEM;
1145                         goto bad;
1146                 }
1147                 if (strlen(argv[9]) != v->salt_size * 2 ||
1148                     hex2bin(v->salt, argv[9], v->salt_size)) {
1149                         ti->error = "Invalid salt";
1150                         r = -EINVAL;
1151                         goto bad;
1152                 }
1153         }
1154
1155         argv += 10;
1156         argc -= 10;
1157
1158         /* Optional parameters */
1159         if (argc) {
1160                 as.argc = argc;
1161                 as.argv = argv;
1162
1163                 r = verity_parse_opt_args(&as, v, &verify_args);
1164                 if (r < 0)
1165                         goto bad;
1166         }
1167
1168         /* Root hash signature is  a optional parameter*/
1169         r = verity_verify_root_hash(root_hash_digest_to_validate,
1170                                     strlen(root_hash_digest_to_validate),
1171                                     verify_args.sig,
1172                                     verify_args.sig_size);
1173         if (r < 0) {
1174                 ti->error = "Root hash verification failed";
1175                 goto bad;
1176         }
1177         v->hash_per_block_bits =
1178                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1179
1180         v->levels = 0;
1181         if (v->data_blocks)
1182                 while (v->hash_per_block_bits * v->levels < 64 &&
1183                        (unsigned long long)(v->data_blocks - 1) >>
1184                        (v->hash_per_block_bits * v->levels))
1185                         v->levels++;
1186
1187         if (v->levels > DM_VERITY_MAX_LEVELS) {
1188                 ti->error = "Too many tree levels";
1189                 r = -E2BIG;
1190                 goto bad;
1191         }
1192
1193         hash_position = v->hash_start;
1194         for (i = v->levels - 1; i >= 0; i--) {
1195                 sector_t s;
1196                 v->hash_level_block[i] = hash_position;
1197                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1198                                         >> ((i + 1) * v->hash_per_block_bits);
1199                 if (hash_position + s < hash_position) {
1200                         ti->error = "Hash device offset overflow";
1201                         r = -E2BIG;
1202                         goto bad;
1203                 }
1204                 hash_position += s;
1205         }
1206         v->hash_blocks = hash_position;
1207
1208         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1209                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1210                 dm_bufio_alloc_callback, NULL);
1211         if (IS_ERR(v->bufio)) {
1212                 ti->error = "Cannot initialize dm-bufio";
1213                 r = PTR_ERR(v->bufio);
1214                 v->bufio = NULL;
1215                 goto bad;
1216         }
1217
1218         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1219                 ti->error = "Hash device is too small";
1220                 r = -E2BIG;
1221                 goto bad;
1222         }
1223
1224         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1225         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1226         if (!v->verify_wq) {
1227                 ti->error = "Cannot allocate workqueue";
1228                 r = -ENOMEM;
1229                 goto bad;
1230         }
1231
1232         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1233                                 v->ahash_reqsize + v->digest_size * 2;
1234
1235         r = verity_fec_ctr(v);
1236         if (r)
1237                 goto bad;
1238
1239         ti->per_io_data_size = roundup(ti->per_io_data_size,
1240                                        __alignof__(struct dm_verity_io));
1241
1242         verity_verify_sig_opts_cleanup(&verify_args);
1243
1244         return 0;
1245
1246 bad:
1247
1248         verity_verify_sig_opts_cleanup(&verify_args);
1249         verity_dtr(ti);
1250
1251         return r;
1252 }
1253
1254 static struct target_type verity_target = {
1255         .name           = "verity",
1256         .features       = DM_TARGET_IMMUTABLE,
1257         .version        = {1, 7, 0},
1258         .module         = THIS_MODULE,
1259         .ctr            = verity_ctr,
1260         .dtr            = verity_dtr,
1261         .map            = verity_map,
1262         .status         = verity_status,
1263         .prepare_ioctl  = verity_prepare_ioctl,
1264         .iterate_devices = verity_iterate_devices,
1265         .io_hints       = verity_io_hints,
1266 };
1267
1268 static int __init dm_verity_init(void)
1269 {
1270         int r;
1271
1272         r = dm_register_target(&verity_target);
1273         if (r < 0)
1274                 DMERR("register failed %d", r);
1275
1276         return r;
1277 }
1278
1279 static void __exit dm_verity_exit(void)
1280 {
1281         dm_unregister_target(&verity_target);
1282 }
1283
1284 module_init(dm_verity_init);
1285 module_exit(dm_verity_exit);
1286
1287 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1288 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1289 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1290 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1291 MODULE_LICENSE("GPL");