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