drivers/md/dm-verity-target.c

   1 /*
   2  * Copyright (C) 2012 Red Hat, Inc.
   3  *
   4  * Author: Mikulas Patocka <mpatocka@redhat.com>
   5  *
   6  * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
  11  * default prefetch value. Data are read in "prefetch_cluster" chunks from the
  12  * hash device. Setting this greatly improves performance when data and hash
  13  * are on the same disk on different partitions on devices with poor random
  14  * access behavior.
  15  */
  16
  17 #include "dm-verity.h"
  18 #include "dm-verity-fec.h"
  19
  20 #include <linux/module.h>
  21 #include <linux/reboot.h>
  22
  23 #define DM_MSG_PREFIX                   "verity"
  24
  25 #define DM_VERITY_ENV_LENGTH            42
  26 #define DM_VERITY_ENV_VAR_NAME          "DM_VERITY_ERR_BLOCK_NR"
  27
  28 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
  29
  30 #define DM_VERITY_MAX_CORRUPTED_ERRS    100
  31
  32 #define DM_VERITY_OPT_LOGGING           "ignore_corruption"
  33 #define DM_VERITY_OPT_RESTART           "restart_on_corruption"
  34 #define DM_VERITY_OPT_IGN_ZEROES        "ignore_zero_blocks"
  35
  36 #define DM_VERITY_OPTS_MAX              (2 + DM_VERITY_OPTS_FEC)
  37
  38 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  39
  40 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
  41
  42 struct dm_verity_prefetch_work {
  43         struct work_struct work;
  44         struct dm_verity *v;
  45         sector_t block;
  46         unsigned n_blocks;
  47 };
  48
  49 /*
  50  * Auxiliary structure appended to each dm-bufio buffer. If the value
  51  * hash_verified is nonzero, hash of the block has been verified.
  52  *
  53  * The variable hash_verified is set to 0 when allocating the buffer, then
  54  * it can be changed to 1 and it is never reset to 0 again.
  55  *
  56  * There is no lock around this value, a race condition can at worst cause
  57  * that multiple processes verify the hash of the same buffer simultaneously
  58  * and write 1 to hash_verified simultaneously.
  59  * This condition is harmless, so we don't need locking.
  60  */
  61 struct buffer_aux {
  62         int hash_verified;
  63 };
  64
  65 /*
  66  * Initialize struct buffer_aux for a freshly created buffer.
  67  */
  68 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  69 {
  70         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  71
  72         aux->hash_verified = 0;
  73 }
  74
  75 /*
  76  * Translate input sector number to the sector number on the target device.
  77  */
  78 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  79 {
  80         return v->data_start + dm_target_offset(v->ti, bi_sector);
  81 }
  82
  83 /*
  84  * Return hash position of a specified block at a specified tree level
  85  * (0 is the lowest level).
  86  * The lowest "hash_per_block_bits"-bits of the result denote hash position
  87  * inside a hash block. The remaining bits denote location of the hash block.
  88  */
  89 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
  90                                          int level)
  91 {
  92         return block >> (level * v->hash_per_block_bits);
  93 }
  94
  95 /*
  96  * Wrapper for crypto_shash_init, which handles verity salting.
  97  */
  98 static int verity_hash_init(struct dm_verity *v, struct shash_desc *desc)
  99 {
 100         int r;
 101
 102         desc->tfm = v->tfm;
 103         desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 104
 105         r = crypto_shash_init(desc);
 106
 107         if (unlikely(r < 0)) {
 108                 DMERR("crypto_shash_init failed: %d", r);
 109                 return r;
 110         }
 111
 112         if (likely(v->version >= 1)) {
 113                 r = crypto_shash_update(desc, v->salt, v->salt_size);
 114
 115                 if (unlikely(r < 0)) {
 116                         DMERR("crypto_shash_update failed: %d", r);
 117                         return r;
 118                 }
 119         }
 120
 121         return 0;
 122 }
 123
 124 static int verity_hash_update(struct dm_verity *v, struct shash_desc *desc,
 125                               const u8 *data, size_t len)
 126 {
 127         int r = crypto_shash_update(desc, data, len);
 128
 129         if (unlikely(r < 0))
 130                 DMERR("crypto_shash_update failed: %d", r);
 131
 132         return r;
 133 }
 134
 135 static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc,
 136                              u8 *digest)
 137 {
 138         int r;
 139
 140         if (unlikely(!v->version)) {
 141                 r = crypto_shash_update(desc, v->salt, v->salt_size);
 142
 143                 if (r < 0) {
 144                         DMERR("crypto_shash_update failed: %d", r);
 145                         return r;
 146                 }
 147         }
 148
 149         r = crypto_shash_final(desc, digest);
 150
 151         if (unlikely(r < 0))
 152                 DMERR("crypto_shash_final failed: %d", r);
 153
 154         return r;
 155 }
 156
 157 int verity_hash(struct dm_verity *v, struct shash_desc *desc,
 158                 const u8 *data, size_t len, u8 *digest)
 159 {
 160         int r;
 161
 162         r = verity_hash_init(v, desc);
 163         if (unlikely(r < 0))
 164                 return r;
 165
 166         r = verity_hash_update(v, desc, data, len);
 167         if (unlikely(r < 0))
 168                 return r;
 169
 170         return verity_hash_final(v, desc, digest);
 171 }
 172
 173 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 174                                  sector_t *hash_block, unsigned *offset)
 175 {
 176         sector_t position = verity_position_at_level(v, block, level);
 177         unsigned idx;
 178
 179         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 180
 181         if (!offset)
 182                 return;
 183
 184         idx = position & ((1 << v->hash_per_block_bits) - 1);
 185         if (!v->version)
 186                 *offset = idx * v->digest_size;
 187         else
 188                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 189 }
 190
 191 /*
 192  * Handle verification errors.
 193  */
 194 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 195                              unsigned long long block)
 196 {
 197         char verity_env[DM_VERITY_ENV_LENGTH];
 198         char *envp[] = { verity_env, NULL };
 199         const char *type_str = "";
 200         struct mapped_device *md = dm_table_get_md(v->ti->table);
 201
 202         /* Corruption should be visible in device status in all modes */
 203         v->hash_failed = 1;
 204
 205         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 206                 goto out;
 207
 208         v->corrupted_errs++;
 209
 210         switch (type) {
 211         case DM_VERITY_BLOCK_TYPE_DATA:
 212                 type_str = "data";
 213                 break;
 214         case DM_VERITY_BLOCK_TYPE_METADATA:
 215                 type_str = "metadata";
 216                 break;
 217         default:
 218                 BUG();
 219         }
 220
 221         DMERR("%s: %s block %llu is corrupted", v->data_dev->name, type_str,
 222                 block);
 223
 224         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
 225                 DMERR("%s: reached maximum errors", v->data_dev->name);
 226
 227         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 228                 DM_VERITY_ENV_VAR_NAME, type, block);
 229
 230         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 231
 232 out:
 233         if (v->mode == DM_VERITY_MODE_LOGGING)
 234                 return 0;
 235
 236         if (v->mode == DM_VERITY_MODE_RESTART)
 237                 kernel_restart("dm-verity device corrupted");
 238
 239         return 1;
 240 }
 241
 242 /*
 243  * Verify hash of a metadata block pertaining to the specified data block
 244  * ("block" argument) at a specified level ("level" argument).
 245  *
 246  * On successful return, verity_io_want_digest(v, io) contains the hash value
 247  * for a lower tree level or for the data block (if we're at the lowest level).
 248  *
 249  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 250  * If "skip_unverified" is false, unverified buffer is hashed and verified
 251  * against current value of verity_io_want_digest(v, io).
 252  */
 253 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 254                                sector_t block, int level, bool skip_unverified,
 255                                u8 *want_digest)
 256 {
 257         struct dm_buffer *buf;
 258         struct buffer_aux *aux;
 259         u8 *data;
 260         int r;
 261         sector_t hash_block;
 262         unsigned offset;
 263
 264         verity_hash_at_level(v, block, level, &hash_block, &offset);
 265
 266         data = dm_bufio_read(v->bufio, hash_block, &buf);
 267         if (IS_ERR(data))
 268                 return PTR_ERR(data);
 269
 270         aux = dm_bufio_get_aux_data(buf);
 271
 272         if (!aux->hash_verified) {
 273                 if (skip_unverified) {
 274                         r = 1;
 275                         goto release_ret_r;
 276                 }
 277
 278                 r = verity_hash(v, verity_io_hash_desc(v, io),
 279                                 data, 1 << v->hash_dev_block_bits,
 280                                 verity_io_real_digest(v, io));
 281                 if (unlikely(r < 0))
 282                         goto release_ret_r;
 283
 284                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 285                                   v->digest_size) == 0))
 286                         aux->hash_verified = 1;
 287                 else if (verity_fec_decode(v, io,
 288                                            DM_VERITY_BLOCK_TYPE_METADATA,
 289                                            hash_block, data, NULL) == 0)
 290                         aux->hash_verified = 1;
 291                 else if (verity_handle_err(v,
 292                                            DM_VERITY_BLOCK_TYPE_METADATA,
 293                                            hash_block)) {
 294                         r = -EIO;
 295                         goto release_ret_r;
 296                 }
 297         }
 298
 299         data += offset;
 300         memcpy(want_digest, data, v->digest_size);
 301         r = 0;
 302
 303 release_ret_r:
 304         dm_bufio_release(buf);
 305         return r;
 306 }
 307
 308 /*
 309  * Find a hash for a given block, write it to digest and verify the integrity
 310  * of the hash tree if necessary.
 311  */
 312 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 313                           sector_t block, u8 *digest, bool *is_zero)
 314 {
 315         int r = 0, i;
 316
 317         if (likely(v->levels)) {
 318                 /*
 319                  * First, we try to get the requested hash for
 320                  * the current block. If the hash block itself is
 321                  * verified, zero is returned. If it isn't, this
 322                  * function returns 1 and we fall back to whole
 323                  * chain verification.
 324                  */
 325                 r = verity_verify_level(v, io, block, 0, true, digest);
 326                 if (likely(r <= 0))
 327                         goto out;
 328         }
 329
 330         memcpy(digest, v->root_digest, v->digest_size);
 331
 332         for (i = v->levels - 1; i >= 0; i--) {
 333                 r = verity_verify_level(v, io, block, i, false, digest);
 334                 if (unlikely(r))
 335                         goto out;
 336         }
 337 out:
 338         if (!r && v->zero_digest)
 339                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 340         else
 341                 *is_zero = false;
 342
 343         return r;
 344 }
 345
 346 /*
 347  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
 348  * starting from iter.
 349  */
 350 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 351                         struct bvec_iter *iter,
 352                         int (*process)(struct dm_verity *v,
 353                                        struct dm_verity_io *io, u8 *data,
 354                                        size_t len))
 355 {
 356         unsigned todo = 1 << v->data_dev_block_bits;
 357         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
 358
 359         do {
 360                 int r;
 361                 u8 *page;
 362                 unsigned len;
 363                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 364
 365                 page = kmap_atomic(bv.bv_page);
 366                 len = bv.bv_len;
 367
 368                 if (likely(len >= todo))
 369                         len = todo;
 370
 371                 r = process(v, io, page + bv.bv_offset, len);
 372                 kunmap_atomic(page);
 373
 374                 if (r < 0)
 375                         return r;
 376
 377                 bio_advance_iter(bio, iter, len);
 378                 todo -= len;
 379         } while (todo);
 380
 381         return 0;
 382 }
 383
 384 static int verity_bv_hash_update(struct dm_verity *v, struct dm_verity_io *io,
 385                                  u8 *data, size_t len)
 386 {
 387         return verity_hash_update(v, verity_io_hash_desc(v, io), data, len);
 388 }
 389
 390 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 391                           u8 *data, size_t len)
 392 {
 393         memset(data, 0, len);
 394         return 0;
 395 }
 396
 397 /*
 398  * Verify one "dm_verity_io" structure.
 399  */
 400 static int verity_verify_io(struct dm_verity_io *io)
 401 {
 402         bool is_zero;
 403         struct dm_verity *v = io->v;
 404         struct bvec_iter start;
 405         unsigned b;
 406
 407         for (b = 0; b < io->n_blocks; b++) {
 408                 int r;
 409                 struct shash_desc *desc = verity_io_hash_desc(v, io);
 410
 411                 r = verity_hash_for_block(v, io, io->block + b,
 412                                           verity_io_want_digest(v, io),
 413                                           &is_zero);
 414                 if (unlikely(r < 0))
 415                         return r;
 416
 417                 if (is_zero) {
 418                         /*
 419                          * If we expect a zero block, don't validate, just
 420                          * return zeros.
 421                          */
 422                         r = verity_for_bv_block(v, io, &io->iter,
 423                                                 verity_bv_zero);
 424                         if (unlikely(r < 0))
 425                                 return r;
 426
 427                         continue;
 428                 }
 429
 430                 r = verity_hash_init(v, desc);
 431                 if (unlikely(r < 0))
 432                         return r;
 433
 434                 start = io->iter;
 435                 r = verity_for_bv_block(v, io, &io->iter, verity_bv_hash_update);
 436                 if (unlikely(r < 0))
 437                         return r;
 438
 439                 r = verity_hash_final(v, desc, verity_io_real_digest(v, io));
 440                 if (unlikely(r < 0))
 441                         return r;
 442
 443                 if (likely(memcmp(verity_io_real_digest(v, io),
 444                                   verity_io_want_digest(v, io), v->digest_size) == 0))
 445                         continue;
 446                 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 447                                            io->block + b, NULL, &start) == 0)
 448                         continue;
 449                 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 450                                            io->block + b))
 451                         return -EIO;
 452         }
 453
 454         return 0;
 455 }
 456
 457 /*
 458  * End one "io" structure with a given error.
 459  */
 460 static void verity_finish_io(struct dm_verity_io *io, int error)
 461 {
 462         struct dm_verity *v = io->v;
 463         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
 464
 465         bio->bi_end_io = io->orig_bi_end_io;
 466         bio->bi_error = error;
 467
 468         verity_fec_finish_io(io);
 469
 470         bio_endio(bio);
 471 }
 472
 473 static void verity_work(struct work_struct *w)
 474 {
 475         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 476
 477         verity_finish_io(io, verity_verify_io(io));
 478 }
 479
 480 static void verity_end_io(struct bio *bio)
 481 {
 482         struct dm_verity_io *io = bio->bi_private;
 483
 484         if (bio->bi_error && !verity_fec_is_enabled(io->v)) {
 485                 verity_finish_io(io, bio->bi_error);
 486                 return;
 487         }
 488
 489         INIT_WORK(&io->work, verity_work);
 490         queue_work(io->v->verify_wq, &io->work);
 491 }
 492
 493 /*
 494  * Prefetch buffers for the specified io.
 495  * The root buffer is not prefetched, it is assumed that it will be cached
 496  * all the time.
 497  */
 498 static void verity_prefetch_io(struct work_struct *work)
 499 {
 500         struct dm_verity_prefetch_work *pw =
 501                 container_of(work, struct dm_verity_prefetch_work, work);
 502         struct dm_verity *v = pw->v;
 503         int i;
 504         sector_t prefetch_size;
 505
 506         for (i = v->levels - 2; i >= 0; i--) {
 507                 sector_t hash_block_start;
 508                 sector_t hash_block_end;
 509                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 510                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 511                 if (!i) {
 512                         unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
 513
 514                         cluster >>= v->data_dev_block_bits;
 515                         if (unlikely(!cluster))
 516                                 goto no_prefetch_cluster;
 517
 518                         if (unlikely(cluster & (cluster - 1)))
 519                                 cluster = 1 << __fls(cluster);
 520
 521                         hash_block_start &= ~(sector_t)(cluster - 1);
 522                         hash_block_end |= cluster - 1;
 523                         if (unlikely(hash_block_end >= v->hash_blocks))
 524                                 hash_block_end = v->hash_blocks - 1;
 525                 }
 526 no_prefetch_cluster:
 527                 // for emmc, it is more efficient to send bigger read
 528                 prefetch_size = max((sector_t)CONFIG_DM_VERITY_HASH_PREFETCH_MIN_SIZE,
 529                         hash_block_end - hash_block_start + 1);
 530                 if ((hash_block_start + prefetch_size) >= (v->hash_start + v->hash_blocks)) {
 531                         prefetch_size = hash_block_end - hash_block_start + 1;
 532                 }
 533                 dm_bufio_prefetch(v->bufio, hash_block_start,
 534                                   prefetch_size);
 535         }
 536
 537         kfree(pw);
 538 }
 539
 540 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 541 {
 542         struct dm_verity_prefetch_work *pw;
 543
 544         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 545                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 546
 547         if (!pw)
 548                 return;
 549
 550         INIT_WORK(&pw->work, verity_prefetch_io);
 551         pw->v = v;
 552         pw->block = io->block;
 553         pw->n_blocks = io->n_blocks;
 554         queue_work(v->verify_wq, &pw->work);
 555 }
 556
 557 /*
 558  * Bio map function. It allocates dm_verity_io structure and bio vector and
 559  * fills them. Then it issues prefetches and the I/O.
 560  */
 561 int verity_map(struct dm_target *ti, struct bio *bio)
 562 {
 563         struct dm_verity *v = ti->private;
 564         struct dm_verity_io *io;
 565
 566         bio->bi_bdev = v->data_dev->bdev;
 567         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 568
 569         if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 570             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 571                 DMERR_LIMIT("unaligned io");
 572                 return -EIO;
 573         }
 574
 575         if (bio_end_sector(bio) >>
 576             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 577                 DMERR_LIMIT("io out of range");
 578                 return -EIO;
 579         }
 580
 581         if (bio_data_dir(bio) == WRITE)
 582                 return -EIO;
 583
 584         io = dm_per_bio_data(bio, ti->per_bio_data_size);
 585         io->v = v;
 586         io->orig_bi_end_io = bio->bi_end_io;
 587         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 588         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 589
 590         bio->bi_end_io = verity_end_io;
 591         bio->bi_private = io;
 592         io->iter = bio->bi_iter;
 593
 594         verity_fec_init_io(io);
 595
 596         verity_submit_prefetch(v, io);
 597
 598         generic_make_request(bio);
 599
 600         return DM_MAPIO_SUBMITTED;
 601 }
 602 EXPORT_SYMBOL_GPL(verity_map);
 603
 604 /*
 605  * Status: V (valid) or C (corruption found)
 606  */
 607 void verity_status(struct dm_target *ti, status_type_t type,
 608                           unsigned status_flags, char *result, unsigned maxlen)
 609 {
 610         struct dm_verity *v = ti->private;
 611         unsigned args = 0;
 612         unsigned sz = 0;
 613         unsigned x;
 614
 615         switch (type) {
 616         case STATUSTYPE_INFO:
 617                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 618                 break;
 619         case STATUSTYPE_TABLE:
 620                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 621                         v->version,
 622                         v->data_dev->name,
 623                         v->hash_dev->name,
 624                         1 << v->data_dev_block_bits,
 625                         1 << v->hash_dev_block_bits,
 626                         (unsigned long long)v->data_blocks,
 627                         (unsigned long long)v->hash_start,
 628                         v->alg_name
 629                         );
 630                 for (x = 0; x < v->digest_size; x++)
 631                         DMEMIT("%02x", v->root_digest[x]);
 632                 DMEMIT(" ");
 633                 if (!v->salt_size)
 634                         DMEMIT("-");
 635                 else
 636                         for (x = 0; x < v->salt_size; x++)
 637                                 DMEMIT("%02x", v->salt[x]);
 638                 if (v->mode != DM_VERITY_MODE_EIO)
 639                         args++;
 640                 if (verity_fec_is_enabled(v))
 641                         args += DM_VERITY_OPTS_FEC;
 642                 if (v->zero_digest)
 643                         args++;
 644                 if (!args)
 645                         return;
 646                 DMEMIT(" %u", args);
 647                 if (v->mode != DM_VERITY_MODE_EIO) {
 648                         DMEMIT(" ");
 649                         switch (v->mode) {
 650                         case DM_VERITY_MODE_LOGGING:
 651                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 652                                 break;
 653                         case DM_VERITY_MODE_RESTART:
 654                                 DMEMIT(DM_VERITY_OPT_RESTART);
 655                                 break;
 656                         default:
 657                                 BUG();
 658                         }
 659                 }
 660                 if (v->zero_digest)
 661                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 662                 sz = verity_fec_status_table(v, sz, result, maxlen);
 663                 break;
 664         }
 665 }
 666 EXPORT_SYMBOL_GPL(verity_status);
 667
 668 int verity_prepare_ioctl(struct dm_target *ti,
 669                 struct block_device **bdev, fmode_t *mode)
 670 {
 671         struct dm_verity *v = ti->private;
 672
 673         *bdev = v->data_dev->bdev;
 674
 675         if (v->data_start ||
 676             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
 677                 return 1;
 678         return 0;
 679 }
 680 EXPORT_SYMBOL_GPL(verity_prepare_ioctl);
 681
 682 int verity_iterate_devices(struct dm_target *ti,
 683                                   iterate_devices_callout_fn fn, void *data)
 684 {
 685         struct dm_verity *v = ti->private;
 686
 687         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 688 }
 689 EXPORT_SYMBOL_GPL(verity_iterate_devices);
 690
 691 void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 692 {
 693         struct dm_verity *v = ti->private;
 694
 695         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 696                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 697
 698         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 699                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 700
 701         blk_limits_io_min(limits, limits->logical_block_size);
 702 }
 703 EXPORT_SYMBOL_GPL(verity_io_hints);
 704
 705 void verity_dtr(struct dm_target *ti)
 706 {
 707         struct dm_verity *v = ti->private;
 708
 709         if (v->verify_wq)
 710                 destroy_workqueue(v->verify_wq);
 711
 712         if (v->bufio)
 713                 dm_bufio_client_destroy(v->bufio);
 714
 715         kfree(v->salt);
 716         kfree(v->root_digest);
 717         kfree(v->zero_digest);
 718
 719         if (v->tfm)
 720                 crypto_free_shash(v->tfm);
 721
 722         kfree(v->alg_name);
 723
 724         if (v->hash_dev)
 725                 dm_put_device(ti, v->hash_dev);
 726
 727         if (v->data_dev)
 728                 dm_put_device(ti, v->data_dev);
 729
 730         verity_fec_dtr(v);
 731
 732         kfree(v);
 733 }
 734 EXPORT_SYMBOL_GPL(verity_dtr);
 735
 736 static int verity_alloc_zero_digest(struct dm_verity *v)
 737 {
 738         int r = -ENOMEM;
 739         struct shash_desc *desc;
 740         u8 *zero_data;
 741
 742         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
 743
 744         if (!v->zero_digest)
 745                 return r;
 746
 747         desc = kmalloc(v->shash_descsize, GFP_KERNEL);
 748
 749         if (!desc)
 750                 return r; /* verity_dtr will free zero_digest */
 751
 752         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
 753
 754         if (!zero_data)
 755                 goto out;
 756
 757         r = verity_hash(v, desc, zero_data, 1 << v->data_dev_block_bits,
 758                         v->zero_digest);
 759
 760 out:
 761         kfree(desc);
 762         kfree(zero_data);
 763
 764         return r;
 765 }
 766
 767 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
 768 {
 769         int r;
 770         unsigned argc;
 771         struct dm_target *ti = v->ti;
 772         const char *arg_name;
 773
 774         static struct dm_arg _args[] = {
 775                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
 776         };
 777
 778         r = dm_read_arg_group(_args, as, &argc, &ti->error);
 779         if (r)
 780                 return -EINVAL;
 781
 782         if (!argc)
 783                 return 0;
 784
 785         do {
 786                 arg_name = dm_shift_arg(as);
 787                 argc--;
 788
 789                 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
 790                         v->mode = DM_VERITY_MODE_LOGGING;
 791                         continue;
 792
 793                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
 794                         v->mode = DM_VERITY_MODE_RESTART;
 795                         continue;
 796
 797                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
 798                         r = verity_alloc_zero_digest(v);
 799                         if (r) {
 800                                 ti->error = "Cannot allocate zero digest";
 801                                 return r;
 802                         }
 803                         continue;
 804
 805                 } else if (verity_is_fec_opt_arg(arg_name)) {
 806                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
 807                         if (r)
 808                                 return r;
 809                         continue;
 810                 }
 811
 812                 ti->error = "Unrecognized verity feature request";
 813                 return -EINVAL;
 814         } while (argc && !r);
 815
 816         return r;
 817 }
 818
 819 /*
 820  * Target parameters:
 821  *      <version>       The current format is version 1.
 822  *                      Vsn 0 is compatible with original Chromium OS releases.
 823  *      <data device>
 824  *      <hash device>
 825  *      <data block size>
 826  *      <hash block size>
 827  *      <the number of data blocks>
 828  *      <hash start block>
 829  *      <algorithm>
 830  *      <digest>
 831  *      <salt>          Hex string or "-" if no salt.
 832  */
 833 int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 834 {
 835         struct dm_verity *v;
 836         struct dm_arg_set as;
 837         unsigned int num;
 838         unsigned long long num_ll;
 839         int r;
 840         int i;
 841         sector_t hash_position;
 842         char dummy;
 843
 844         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
 845         if (!v) {
 846                 ti->error = "Cannot allocate verity structure";
 847                 return -ENOMEM;
 848         }
 849         ti->private = v;
 850         v->ti = ti;
 851
 852         r = verity_fec_ctr_alloc(v);
 853         if (r)
 854                 goto bad;
 855
 856         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
 857                 ti->error = "Device must be readonly";
 858                 r = -EINVAL;
 859                 goto bad;
 860         }
 861
 862         if (argc < 10) {
 863                 ti->error = "Not enough arguments";
 864                 r = -EINVAL;
 865                 goto bad;
 866         }
 867
 868         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
 869             num > 1) {
 870                 ti->error = "Invalid version";
 871                 r = -EINVAL;
 872                 goto bad;
 873         }
 874         v->version = num;
 875
 876         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
 877         if (r) {
 878                 ti->error = "Data device lookup failed";
 879                 goto bad;
 880         }
 881
 882         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
 883         if (r) {
 884                 ti->error = "Data device lookup failed";
 885                 goto bad;
 886         }
 887
 888         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
 889             !num || (num & (num - 1)) ||
 890             num < bdev_logical_block_size(v->data_dev->bdev) ||
 891             num > PAGE_SIZE) {
 892                 ti->error = "Invalid data device block size";
 893                 r = -EINVAL;
 894                 goto bad;
 895         }
 896         v->data_dev_block_bits = __ffs(num);
 897
 898         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
 899             !num || (num & (num - 1)) ||
 900             num < bdev_logical_block_size(v->hash_dev->bdev) ||
 901             num > INT_MAX) {
 902                 ti->error = "Invalid hash device block size";
 903                 r = -EINVAL;
 904                 goto bad;
 905         }
 906         v->hash_dev_block_bits = __ffs(num);
 907
 908         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
 909             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
 910             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 911                 ti->error = "Invalid data blocks";
 912                 r = -EINVAL;
 913                 goto bad;
 914         }
 915         v->data_blocks = num_ll;
 916
 917         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
 918                 ti->error = "Data device is too small";
 919                 r = -EINVAL;
 920                 goto bad;
 921         }
 922
 923         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
 924             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
 925             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 926                 ti->error = "Invalid hash start";
 927                 r = -EINVAL;
 928                 goto bad;
 929         }
 930         v->hash_start = num_ll;
 931
 932         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
 933         if (!v->alg_name) {
 934                 ti->error = "Cannot allocate algorithm name";
 935                 r = -ENOMEM;
 936                 goto bad;
 937         }
 938
 939         v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
 940         if (IS_ERR(v->tfm)) {
 941                 ti->error = "Cannot initialize hash function";
 942                 r = PTR_ERR(v->tfm);
 943                 v->tfm = NULL;
 944                 goto bad;
 945         }
 946         v->digest_size = crypto_shash_digestsize(v->tfm);
 947         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
 948                 ti->error = "Digest size too big";
 949                 r = -EINVAL;
 950                 goto bad;
 951         }
 952         v->shash_descsize =
 953                 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
 954
 955         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
 956         if (!v->root_digest) {
 957                 ti->error = "Cannot allocate root digest";
 958                 r = -ENOMEM;
 959                 goto bad;
 960         }
 961         if (strlen(argv[8]) != v->digest_size * 2 ||
 962             hex2bin(v->root_digest, argv[8], v->digest_size)) {
 963                 ti->error = "Invalid root digest";
 964                 r = -EINVAL;
 965                 goto bad;
 966         }
 967
 968         if (strcmp(argv[9], "-")) {
 969                 v->salt_size = strlen(argv[9]) / 2;
 970                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
 971                 if (!v->salt) {
 972                         ti->error = "Cannot allocate salt";
 973                         r = -ENOMEM;
 974                         goto bad;
 975                 }
 976                 if (strlen(argv[9]) != v->salt_size * 2 ||
 977                     hex2bin(v->salt, argv[9], v->salt_size)) {
 978                         ti->error = "Invalid salt";
 979                         r = -EINVAL;
 980                         goto bad;
 981                 }
 982         }
 983
 984         argv += 10;
 985         argc -= 10;
 986
 987         /* Optional parameters */
 988         if (argc) {
 989                 as.argc = argc;
 990                 as.argv = argv;
 991
 992                 r = verity_parse_opt_args(&as, v);
 993                 if (r < 0)
 994                         goto bad;
 995         }
 996
 997         v->hash_per_block_bits =
 998                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
 999
1000         v->levels = 0;
1001         if (v->data_blocks)
1002                 while (v->hash_per_block_bits * v->levels < 64 &&
1003                        (unsigned long long)(v->data_blocks - 1) >>
1004                        (v->hash_per_block_bits * v->levels))
1005                         v->levels++;
1006
1007         if (v->levels > DM_VERITY_MAX_LEVELS) {
1008                 ti->error = "Too many tree levels";
1009                 r = -E2BIG;
1010                 goto bad;
1011         }
1012
1013         hash_position = v->hash_start;
1014         for (i = v->levels - 1; i >= 0; i--) {
1015                 sector_t s;
1016                 v->hash_level_block[i] = hash_position;
1017                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1018                                         >> ((i + 1) * v->hash_per_block_bits);
1019                 if (hash_position + s < hash_position) {
1020                         ti->error = "Hash device offset overflow";
1021                         r = -E2BIG;
1022                         goto bad;
1023                 }
1024                 hash_position += s;
1025         }
1026         v->hash_blocks = hash_position;
1027
1028         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1029                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1030                 dm_bufio_alloc_callback, NULL);
1031         if (IS_ERR(v->bufio)) {
1032                 ti->error = "Cannot initialize dm-bufio";
1033                 r = PTR_ERR(v->bufio);
1034                 v->bufio = NULL;
1035                 goto bad;
1036         }
1037
1038         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1039                 ti->error = "Hash device is too small";
1040                 r = -E2BIG;
1041                 goto bad;
1042         }
1043
1044         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1045         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1046         if (!v->verify_wq) {
1047                 ti->error = "Cannot allocate workqueue";
1048                 r = -ENOMEM;
1049                 goto bad;
1050         }
1051
1052         ti->per_bio_data_size = sizeof(struct dm_verity_io) +
1053                                 v->shash_descsize + v->digest_size * 2;
1054
1055         r = verity_fec_ctr(v);
1056         if (r)
1057                 goto bad;
1058
1059         ti->per_bio_data_size = roundup(ti->per_bio_data_size,
1060                                         __alignof__(struct dm_verity_io));
1061
1062         return 0;
1063
1064 bad:
1065         verity_dtr(ti);
1066
1067         return r;
1068 }
1069 EXPORT_SYMBOL_GPL(verity_ctr);
1070
1071 static struct target_type verity_target = {
1072         .name           = "verity",
1073         .version        = {1, 3, 0},
1074         .module         = THIS_MODULE,
1075         .ctr            = verity_ctr,
1076         .dtr            = verity_dtr,
1077         .map            = verity_map,
1078         .status         = verity_status,
1079         .prepare_ioctl  = verity_prepare_ioctl,
1080         .iterate_devices = verity_iterate_devices,
1081         .io_hints       = verity_io_hints,
1082 };
1083
1084 static int __init dm_verity_init(void)
1085 {
1086         int r;
1087
1088         r = dm_register_target(&verity_target);
1089         if (r < 0)
1090                 DMERR("register failed %d", r);
1091
1092         return r;
1093 }
1094
1095 static void __exit dm_verity_exit(void)
1096 {
1097         dm_unregister_target(&verity_target);
1098 }
1099
1100 module_init(dm_verity_init);
1101 module_exit(dm_verity_exit);
1102
1103 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1104 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1105 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1106 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1107 MODULE_LICENSE("GPL");