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