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