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 #define DM_VERITY_OPT_AT_MOST_ONCE      "check_at_most_once"
  36
  37 #define DM_VERITY_OPTS_MAX              (3 + DM_VERITY_OPTS_FEC)
  38
  39 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  40
  41 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
  42
  43 struct dm_verity_prefetch_work {
  44         struct work_struct work;
  45         struct dm_verity *v;
  46         sector_t block;
  47         unsigned n_blocks;
  48 };
  49
  50 /*
  51  * Auxiliary structure appended to each dm-bufio buffer. If the value
  52  * hash_verified is nonzero, hash of the block has been verified.
  53  *
  54  * The variable hash_verified is set to 0 when allocating the buffer, then
  55  * it can be changed to 1 and it is never reset to 0 again.
  56  *
  57  * There is no lock around this value, a race condition can at worst cause
  58  * that multiple processes verify the hash of the same buffer simultaneously
  59  * and write 1 to hash_verified simultaneously.
  60  * This condition is harmless, so we don't need locking.
  61  */
  62 struct buffer_aux {
  63         int hash_verified;
  64 };
  65
  66 /*
  67  * Initialize struct buffer_aux for a freshly created buffer.
  68  */
  69 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  70 {
  71         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  72
  73         aux->hash_verified = 0;
  74 }
  75
  76 /*
  77  * Translate input sector number to the sector number on the target device.
  78  */
  79 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  80 {
  81         return v->data_start + dm_target_offset(v->ti, bi_sector);
  82 }
  83
  84 /*
  85  * Return hash position of a specified block at a specified tree level
  86  * (0 is the lowest level).
  87  * The lowest "hash_per_block_bits"-bits of the result denote hash position
  88  * inside a hash block. The remaining bits denote location of the hash block.
  89  */
  90 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
  91                                          int level)
  92 {
  93         return block >> (level * v->hash_per_block_bits);
  94 }
  95
  96 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
  97                                 const u8 *data, size_t len,
  98                                 struct crypto_wait *wait)
  99 {
 100         struct scatterlist sg;
 101
 102         if (likely(!is_vmalloc_addr(data))) {
 103                 sg_init_one(&sg, data, len);
 104                 ahash_request_set_crypt(req, &sg, NULL, len);
 105                 return crypto_wait_req(crypto_ahash_update(req), wait);
 106         } else {
 107                 do {
 108                         int r;
 109                         size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 110                         flush_kernel_vmap_range((void *)data, this_step);
 111                         sg_init_table(&sg, 1);
 112                         sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 113                         ahash_request_set_crypt(req, &sg, NULL, this_step);
 114                         r = crypto_wait_req(crypto_ahash_update(req), wait);
 115                         if (unlikely(r))
 116                                 return r;
 117                         data += this_step;
 118                         len -= this_step;
 119                 } while (len);
 120                 return 0;
 121         }
 122 }
 123
 124 /*
 125  * Wrapper for crypto_ahash_init, which handles verity salting.
 126  */
 127 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
 128                                 struct crypto_wait *wait)
 129 {
 130         int r;
 131
 132         ahash_request_set_tfm(req, v->tfm);
 133         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
 134                                         CRYPTO_TFM_REQ_MAY_BACKLOG,
 135                                         crypto_req_done, (void *)wait);
 136         crypto_init_wait(wait);
 137
 138         r = crypto_wait_req(crypto_ahash_init(req), wait);
 139
 140         if (unlikely(r < 0)) {
 141                 DMERR("crypto_ahash_init failed: %d", r);
 142                 return r;
 143         }
 144
 145         if (likely(v->salt_size && (v->version >= 1)))
 146                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 147
 148         return r;
 149 }
 150
 151 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
 152                              u8 *digest, struct crypto_wait *wait)
 153 {
 154         int r;
 155
 156         if (unlikely(v->salt_size && (!v->version))) {
 157                 r = verity_hash_update(v, req, v->salt, v->salt_size, wait);
 158
 159                 if (r < 0) {
 160                         DMERR("verity_hash_final failed updating salt: %d", r);
 161                         goto out;
 162                 }
 163         }
 164
 165         ahash_request_set_crypt(req, NULL, digest, 0);
 166         r = crypto_wait_req(crypto_ahash_final(req), wait);
 167 out:
 168         return r;
 169 }
 170
 171 int verity_hash(struct dm_verity *v, struct ahash_request *req,
 172                 const u8 *data, size_t len, u8 *digest)
 173 {
 174         int r;
 175         struct crypto_wait wait;
 176
 177         r = verity_hash_init(v, req, &wait);
 178         if (unlikely(r < 0))
 179                 goto out;
 180
 181         r = verity_hash_update(v, req, data, len, &wait);
 182         if (unlikely(r < 0))
 183                 goto out;
 184
 185         r = verity_hash_final(v, req, digest, &wait);
 186
 187 out:
 188         return r;
 189 }
 190
 191 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 192                                  sector_t *hash_block, unsigned *offset)
 193 {
 194         sector_t position = verity_position_at_level(v, block, level);
 195         unsigned idx;
 196
 197         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 198
 199         if (!offset)
 200                 return;
 201
 202         idx = position & ((1 << v->hash_per_block_bits) - 1);
 203         if (!v->version)
 204                 *offset = idx * v->digest_size;
 205         else
 206                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 207 }
 208
 209 /*
 210  * Handle verification errors.
 211  */
 212 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 213                              unsigned long long block)
 214 {
 215         char verity_env[DM_VERITY_ENV_LENGTH];
 216         char *envp[] = { verity_env, NULL };
 217         const char *type_str = "";
 218         struct mapped_device *md = dm_table_get_md(v->ti->table);
 219
 220         /* Corruption should be visible in device status in all modes */
 221         v->hash_failed = 1;
 222
 223         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 224                 goto out;
 225
 226         v->corrupted_errs++;
 227
 228         switch (type) {
 229         case DM_VERITY_BLOCK_TYPE_DATA:
 230                 type_str = "data";
 231                 break;
 232         case DM_VERITY_BLOCK_TYPE_METADATA:
 233                 type_str = "metadata";
 234                 break;
 235         default:
 236                 BUG();
 237         }
 238
 239         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 240                     type_str, block);
 241
 242         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
 243                 DMERR("%s: reached maximum errors", v->data_dev->name);
 244
 245         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 246                 DM_VERITY_ENV_VAR_NAME, type, block);
 247
 248         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 249
 250 out:
 251         if (v->mode == DM_VERITY_MODE_LOGGING)
 252                 return 0;
 253
 254         if (v->mode == DM_VERITY_MODE_RESTART)
 255                 kernel_restart("dm-verity device corrupted");
 256
 257         return 1;
 258 }
 259
 260 /*
 261  * Verify hash of a metadata block pertaining to the specified data block
 262  * ("block" argument) at a specified level ("level" argument).
 263  *
 264  * On successful return, verity_io_want_digest(v, io) contains the hash value
 265  * for a lower tree level or for the data block (if we're at the lowest level).
 266  *
 267  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 268  * If "skip_unverified" is false, unverified buffer is hashed and verified
 269  * against current value of verity_io_want_digest(v, io).
 270  */
 271 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 272                                sector_t block, int level, bool skip_unverified,
 273                                u8 *want_digest)
 274 {
 275         struct dm_buffer *buf;
 276         struct buffer_aux *aux;
 277         u8 *data;
 278         int r;
 279         sector_t hash_block;
 280         unsigned offset;
 281
 282         verity_hash_at_level(v, block, level, &hash_block, &offset);
 283
 284         data = dm_bufio_read(v->bufio, hash_block, &buf);
 285         if (IS_ERR(data))
 286                 return PTR_ERR(data);
 287
 288         aux = dm_bufio_get_aux_data(buf);
 289
 290         if (!aux->hash_verified) {
 291                 if (skip_unverified) {
 292                         r = 1;
 293                         goto release_ret_r;
 294                 }
 295
 296                 r = verity_hash(v, verity_io_hash_req(v, io),
 297                                 data, 1 << v->hash_dev_block_bits,
 298                                 verity_io_real_digest(v, io));
 299                 if (unlikely(r < 0))
 300                         goto release_ret_r;
 301
 302                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 303                                   v->digest_size) == 0))
 304                         aux->hash_verified = 1;
 305                 else if (verity_fec_decode(v, io,
 306                                            DM_VERITY_BLOCK_TYPE_METADATA,
 307                                            hash_block, data, NULL) == 0)
 308                         aux->hash_verified = 1;
 309                 else if (verity_handle_err(v,
 310                                            DM_VERITY_BLOCK_TYPE_METADATA,
 311                                            hash_block)) {
 312                         r = -EIO;
 313                         goto release_ret_r;
 314                 }
 315         }
 316
 317         data += offset;
 318         memcpy(want_digest, data, v->digest_size);
 319         r = 0;
 320
 321 release_ret_r:
 322         dm_bufio_release(buf);
 323         return r;
 324 }
 325
 326 /*
 327  * Find a hash for a given block, write it to digest and verify the integrity
 328  * of the hash tree if necessary.
 329  */
 330 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 331                           sector_t block, u8 *digest, bool *is_zero)
 332 {
 333         int r = 0, i;
 334
 335         if (likely(v->levels)) {
 336                 /*
 337                  * First, we try to get the requested hash for
 338                  * the current block. If the hash block itself is
 339                  * verified, zero is returned. If it isn't, this
 340                  * function returns 1 and we fall back to whole
 341                  * chain verification.
 342                  */
 343                 r = verity_verify_level(v, io, block, 0, true, digest);
 344                 if (likely(r <= 0))
 345                         goto out;
 346         }
 347
 348         memcpy(digest, v->root_digest, v->digest_size);
 349
 350         for (i = v->levels - 1; i >= 0; i--) {
 351                 r = verity_verify_level(v, io, block, i, false, digest);
 352                 if (unlikely(r))
 353                         goto out;
 354         }
 355 out:
 356         if (!r && v->zero_digest)
 357                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 358         else
 359                 *is_zero = false;
 360
 361         return r;
 362 }
 363
 364 /*
 365  * Calculates the digest for the given bio
 366  */
 367 static int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
 368                                struct bvec_iter *iter, struct crypto_wait *wait)
 369 {
 370         unsigned int todo = 1 << v->data_dev_block_bits;
 371         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 372         struct scatterlist sg;
 373         struct ahash_request *req = verity_io_hash_req(v, io);
 374
 375         do {
 376                 int r;
 377                 unsigned int len;
 378                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 379
 380                 sg_init_table(&sg, 1);
 381
 382                 len = bv.bv_len;
 383
 384                 if (likely(len >= todo))
 385                         len = todo;
 386                 /*
 387                  * Operating on a single page at a time looks suboptimal
 388                  * until you consider the typical block size is 4,096B.
 389                  * Going through this loops twice should be very rare.
 390                  */
 391                 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
 392                 ahash_request_set_crypt(req, &sg, NULL, len);
 393                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 394
 395                 if (unlikely(r < 0)) {
 396                         DMERR("verity_for_io_block crypto op failed: %d", r);
 397                         return r;
 398                 }
 399
 400                 bio_advance_iter(bio, iter, len);
 401                 todo -= len;
 402         } while (todo);
 403
 404         return 0;
 405 }
 406
 407 /*
 408  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
 409  * starting from iter.
 410  */
 411 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 412                         struct bvec_iter *iter,
 413                         int (*process)(struct dm_verity *v,
 414                                        struct dm_verity_io *io, u8 *data,
 415                                        size_t len))
 416 {
 417         unsigned todo = 1 << v->data_dev_block_bits;
 418         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 419
 420         do {
 421                 int r;
 422                 u8 *page;
 423                 unsigned len;
 424                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 425
 426                 page = kmap_atomic(bv.bv_page);
 427                 len = bv.bv_len;
 428
 429                 if (likely(len >= todo))
 430                         len = todo;
 431
 432                 r = process(v, io, page + bv.bv_offset, len);
 433                 kunmap_atomic(page);
 434
 435                 if (r < 0)
 436                         return r;
 437
 438                 bio_advance_iter(bio, iter, len);
 439                 todo -= len;
 440         } while (todo);
 441
 442         return 0;
 443 }
 444
 445 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 446                           u8 *data, size_t len)
 447 {
 448         memset(data, 0, len);
 449         return 0;
 450 }
 451
 452 /*
 453  * Moves the bio iter one data block forward.
 454  */
 455 static inline void verity_bv_skip_block(struct dm_verity *v,
 456                                         struct dm_verity_io *io,
 457                                         struct bvec_iter *iter)
 458 {
 459         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 460
 461         bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
 462 }
 463
 464 /*
 465  * Verify one "dm_verity_io" structure.
 466  */
 467 static int verity_verify_io(struct dm_verity_io *io)
 468 {
 469         bool is_zero;
 470         struct dm_verity *v = io->v;
 471         struct bvec_iter start;
 472         unsigned b;
 473         struct crypto_wait wait;
 474
 475         for (b = 0; b < io->n_blocks; b++) {
 476                 int r;
 477                 sector_t cur_block = io->block + b;
 478                 struct ahash_request *req = verity_io_hash_req(v, io);
 479
 480                 if (v->validated_blocks &&
 481                     likely(test_bit(cur_block, v->validated_blocks))) {
 482                         verity_bv_skip_block(v, io, &io->iter);
 483                         continue;
 484                 }
 485
 486                 r = verity_hash_for_block(v, io, cur_block,
 487                                           verity_io_want_digest(v, io),
 488                                           &is_zero);
 489                 if (unlikely(r < 0))
 490                         return r;
 491
 492                 if (is_zero) {
 493                         /*
 494                          * If we expect a zero block, don't validate, just
 495                          * return zeros.
 496                          */
 497                         r = verity_for_bv_block(v, io, &io->iter,
 498                                                 verity_bv_zero);
 499                         if (unlikely(r < 0))
 500                                 return r;
 501
 502                         continue;
 503                 }
 504
 505                 r = verity_hash_init(v, req, &wait);
 506                 if (unlikely(r < 0))
 507                         return r;
 508
 509                 start = io->iter;
 510                 r = verity_for_io_block(v, io, &io->iter, &wait);
 511                 if (unlikely(r < 0))
 512                         return r;
 513
 514                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 515                                         &wait);
 516                 if (unlikely(r < 0))
 517                         return r;
 518
 519                 if (likely(memcmp(verity_io_real_digest(v, io),
 520                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 521                         if (v->validated_blocks)
 522                                 set_bit(cur_block, v->validated_blocks);
 523                         continue;
 524                 }
 525                 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 526                                            cur_block, NULL, &start) == 0)
 527                         continue;
 528                 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 529                                            cur_block))
 530                         return -EIO;
 531         }
 532
 533         return 0;
 534 }
 535
 536 /*
 537  * Skip verity work in response to I/O error when system is shutting down.
 538  */
 539 static inline bool verity_is_system_shutting_down(void)
 540 {
 541         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 542                 || system_state == SYSTEM_RESTART;
 543 }
 544
 545 /*
 546  * End one "io" structure with a given error.
 547  */
 548 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 549 {
 550         struct dm_verity *v = io->v;
 551         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 552
 553         bio->bi_end_io = io->orig_bi_end_io;
 554         bio->bi_status = status;
 555
 556         verity_fec_finish_io(io);
 557
 558         bio_endio(bio);
 559 }
 560
 561 static void verity_work(struct work_struct *w)
 562 {
 563         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 564
 565         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 566 }
 567
 568 static void verity_end_io(struct bio *bio)
 569 {
 570         struct dm_verity_io *io = bio->bi_private;
 571
 572         if (bio->bi_status &&
 573             (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
 574                 verity_finish_io(io, bio->bi_status);
 575                 return;
 576         }
 577
 578         INIT_WORK(&io->work, verity_work);
 579         queue_work(io->v->verify_wq, &io->work);
 580 }
 581
 582 /*
 583  * Prefetch buffers for the specified io.
 584  * The root buffer is not prefetched, it is assumed that it will be cached
 585  * all the time.
 586  */
 587 static void verity_prefetch_io(struct work_struct *work)
 588 {
 589         struct dm_verity_prefetch_work *pw =
 590                 container_of(work, struct dm_verity_prefetch_work, work);
 591         struct dm_verity *v = pw->v;
 592         int i;
 593
 594         for (i = v->levels - 2; i >= 0; i--) {
 595                 sector_t hash_block_start;
 596                 sector_t hash_block_end;
 597                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 598                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 599                 if (!i) {
 600                         unsigned cluster = READ_ONCE(dm_verity_prefetch_cluster);
 601
 602                         cluster >>= v->data_dev_block_bits;
 603                         if (unlikely(!cluster))
 604                                 goto no_prefetch_cluster;
 605
 606                         if (unlikely(cluster & (cluster - 1)))
 607                                 cluster = 1 << __fls(cluster);
 608
 609                         hash_block_start &= ~(sector_t)(cluster - 1);
 610                         hash_block_end |= cluster - 1;
 611                         if (unlikely(hash_block_end >= v->hash_blocks))
 612                                 hash_block_end = v->hash_blocks - 1;
 613                 }
 614 no_prefetch_cluster:
 615                 dm_bufio_prefetch(v->bufio, hash_block_start,
 616                                   hash_block_end - hash_block_start + 1);
 617         }
 618
 619         kfree(pw);
 620 }
 621
 622 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 623 {
 624         struct dm_verity_prefetch_work *pw;
 625
 626         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 627                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 628
 629         if (!pw)
 630                 return;
 631
 632         INIT_WORK(&pw->work, verity_prefetch_io);
 633         pw->v = v;
 634         pw->block = io->block;
 635         pw->n_blocks = io->n_blocks;
 636         queue_work(v->verify_wq, &pw->work);
 637 }
 638
 639 /*
 640  * Bio map function. It allocates dm_verity_io structure and bio vector and
 641  * fills them. Then it issues prefetches and the I/O.
 642  */
 643 static int verity_map(struct dm_target *ti, struct bio *bio)
 644 {
 645         struct dm_verity *v = ti->private;
 646         struct dm_verity_io *io;
 647
 648         bio_set_dev(bio, v->data_dev->bdev);
 649         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 650
 651         if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 652             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 653                 DMERR_LIMIT("unaligned io");
 654                 return DM_MAPIO_KILL;
 655         }
 656
 657         if (bio_end_sector(bio) >>
 658             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 659                 DMERR_LIMIT("io out of range");
 660                 return DM_MAPIO_KILL;
 661         }
 662
 663         if (bio_data_dir(bio) == WRITE)
 664                 return DM_MAPIO_KILL;
 665
 666         io = dm_per_bio_data(bio, ti->per_io_data_size);
 667         io->v = v;
 668         io->orig_bi_end_io = bio->bi_end_io;
 669         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 670         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 671
 672         bio->bi_end_io = verity_end_io;
 673         bio->bi_private = io;
 674         io->iter = bio->bi_iter;
 675
 676         verity_fec_init_io(io);
 677
 678         verity_submit_prefetch(v, io);
 679
 680         generic_make_request(bio);
 681
 682         return DM_MAPIO_SUBMITTED;
 683 }
 684
 685 /*
 686  * Status: V (valid) or C (corruption found)
 687  */
 688 static void verity_status(struct dm_target *ti, status_type_t type,
 689                           unsigned status_flags, char *result, unsigned maxlen)
 690 {
 691         struct dm_verity *v = ti->private;
 692         unsigned args = 0;
 693         unsigned sz = 0;
 694         unsigned x;
 695
 696         switch (type) {
 697         case STATUSTYPE_INFO:
 698                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 699                 break;
 700         case STATUSTYPE_TABLE:
 701                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 702                         v->version,
 703                         v->data_dev->name,
 704                         v->hash_dev->name,
 705                         1 << v->data_dev_block_bits,
 706                         1 << v->hash_dev_block_bits,
 707                         (unsigned long long)v->data_blocks,
 708                         (unsigned long long)v->hash_start,
 709                         v->alg_name
 710                         );
 711                 for (x = 0; x < v->digest_size; x++)
 712                         DMEMIT("%02x", v->root_digest[x]);
 713                 DMEMIT(" ");
 714                 if (!v->salt_size)
 715                         DMEMIT("-");
 716                 else
 717                         for (x = 0; x < v->salt_size; x++)
 718                                 DMEMIT("%02x", v->salt[x]);
 719                 if (v->mode != DM_VERITY_MODE_EIO)
 720                         args++;
 721                 if (verity_fec_is_enabled(v))
 722                         args += DM_VERITY_OPTS_FEC;
 723                 if (v->zero_digest)
 724                         args++;
 725                 if (v->validated_blocks)
 726                         args++;
 727                 if (!args)
 728                         return;
 729                 DMEMIT(" %u", args);
 730                 if (v->mode != DM_VERITY_MODE_EIO) {
 731                         DMEMIT(" ");
 732                         switch (v->mode) {
 733                         case DM_VERITY_MODE_LOGGING:
 734                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 735                                 break;
 736                         case DM_VERITY_MODE_RESTART:
 737                                 DMEMIT(DM_VERITY_OPT_RESTART);
 738                                 break;
 739                         default:
 740                                 BUG();
 741                         }
 742                 }
 743                 if (v->zero_digest)
 744                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 745                 if (v->validated_blocks)
 746                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 747                 sz = verity_fec_status_table(v, sz, result, maxlen);
 748                 break;
 749         }
 750 }
 751
 752 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 753 {
 754         struct dm_verity *v = ti->private;
 755
 756         *bdev = v->data_dev->bdev;
 757
 758         if (v->data_start ||
 759             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
 760                 return 1;
 761         return 0;
 762 }
 763
 764 static int verity_iterate_devices(struct dm_target *ti,
 765                                   iterate_devices_callout_fn fn, void *data)
 766 {
 767         struct dm_verity *v = ti->private;
 768
 769         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 770 }
 771
 772 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 773 {
 774         struct dm_verity *v = ti->private;
 775
 776         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 777                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 778
 779         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 780                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 781
 782         blk_limits_io_min(limits, limits->logical_block_size);
 783 }
 784
 785 static void verity_dtr(struct dm_target *ti)
 786 {
 787         struct dm_verity *v = ti->private;
 788
 789         if (v->verify_wq)
 790                 destroy_workqueue(v->verify_wq);
 791
 792         if (v->bufio)
 793                 dm_bufio_client_destroy(v->bufio);
 794
 795         kvfree(v->validated_blocks);
 796         kfree(v->salt);
 797         kfree(v->root_digest);
 798         kfree(v->zero_digest);
 799
 800         if (v->tfm)
 801                 crypto_free_ahash(v->tfm);
 802
 803         kfree(v->alg_name);
 804
 805         if (v->hash_dev)
 806                 dm_put_device(ti, v->hash_dev);
 807
 808         if (v->data_dev)
 809                 dm_put_device(ti, v->data_dev);
 810
 811         verity_fec_dtr(v);
 812
 813         kfree(v);
 814 }
 815
 816 static int verity_alloc_most_once(struct dm_verity *v)
 817 {
 818         struct dm_target *ti = v->ti;
 819
 820         /* the bitset can only handle INT_MAX blocks */
 821         if (v->data_blocks > INT_MAX) {
 822                 ti->error = "device too large to use check_at_most_once";
 823                 return -E2BIG;
 824         }
 825
 826         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
 827                                        sizeof(unsigned long),
 828                                        GFP_KERNEL);
 829         if (!v->validated_blocks) {
 830                 ti->error = "failed to allocate bitset for check_at_most_once";
 831                 return -ENOMEM;
 832         }
 833
 834         return 0;
 835 }
 836
 837 static int verity_alloc_zero_digest(struct dm_verity *v)
 838 {
 839         int r = -ENOMEM;
 840         struct ahash_request *req;
 841         u8 *zero_data;
 842
 843         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
 844
 845         if (!v->zero_digest)
 846                 return r;
 847
 848         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
 849
 850         if (!req)
 851                 return r; /* verity_dtr will free zero_digest */
 852
 853         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
 854
 855         if (!zero_data)
 856                 goto out;
 857
 858         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
 859                         v->zero_digest);
 860
 861 out:
 862         kfree(req);
 863         kfree(zero_data);
 864
 865         return r;
 866 }
 867
 868 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
 869 {
 870         int r;
 871         unsigned argc;
 872         struct dm_target *ti = v->ti;
 873         const char *arg_name;
 874
 875         static const struct dm_arg _args[] = {
 876                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
 877         };
 878
 879         r = dm_read_arg_group(_args, as, &argc, &ti->error);
 880         if (r)
 881                 return -EINVAL;
 882
 883         if (!argc)
 884                 return 0;
 885
 886         do {
 887                 arg_name = dm_shift_arg(as);
 888                 argc--;
 889
 890                 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
 891                         v->mode = DM_VERITY_MODE_LOGGING;
 892                         continue;
 893
 894                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
 895                         v->mode = DM_VERITY_MODE_RESTART;
 896                         continue;
 897
 898                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
 899                         r = verity_alloc_zero_digest(v);
 900                         if (r) {
 901                                 ti->error = "Cannot allocate zero digest";
 902                                 return r;
 903                         }
 904                         continue;
 905
 906                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
 907                         r = verity_alloc_most_once(v);
 908                         if (r)
 909                                 return r;
 910                         continue;
 911
 912                 } else if (verity_is_fec_opt_arg(arg_name)) {
 913                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
 914                         if (r)
 915                                 return r;
 916                         continue;
 917                 }
 918
 919                 ti->error = "Unrecognized verity feature request";
 920                 return -EINVAL;
 921         } while (argc && !r);
 922
 923         return r;
 924 }
 925
 926 /*
 927  * Target parameters:
 928  *      <version>       The current format is version 1.
 929  *                      Vsn 0 is compatible with original Chromium OS releases.
 930  *      <data device>
 931  *      <hash device>
 932  *      <data block size>
 933  *      <hash block size>
 934  *      <the number of data blocks>
 935  *      <hash start block>
 936  *      <algorithm>
 937  *      <digest>
 938  *      <salt>          Hex string or "-" if no salt.
 939  */
 940 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 941 {
 942         struct dm_verity *v;
 943         struct dm_arg_set as;
 944         unsigned int num;
 945         unsigned long long num_ll;
 946         int r;
 947         int i;
 948         sector_t hash_position;
 949         char dummy;
 950
 951         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
 952         if (!v) {
 953                 ti->error = "Cannot allocate verity structure";
 954                 return -ENOMEM;
 955         }
 956         ti->private = v;
 957         v->ti = ti;
 958
 959         r = verity_fec_ctr_alloc(v);
 960         if (r)
 961                 goto bad;
 962
 963         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
 964                 ti->error = "Device must be readonly";
 965                 r = -EINVAL;
 966                 goto bad;
 967         }
 968
 969         if (argc < 10) {
 970                 ti->error = "Not enough arguments";
 971                 r = -EINVAL;
 972                 goto bad;
 973         }
 974
 975         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
 976             num > 1) {
 977                 ti->error = "Invalid version";
 978                 r = -EINVAL;
 979                 goto bad;
 980         }
 981         v->version = num;
 982
 983         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
 984         if (r) {
 985                 ti->error = "Data device lookup failed";
 986                 goto bad;
 987         }
 988
 989         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
 990         if (r) {
 991                 ti->error = "Hash device lookup failed";
 992                 goto bad;
 993         }
 994
 995         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
 996             !num || (num & (num - 1)) ||
 997             num < bdev_logical_block_size(v->data_dev->bdev) ||
 998             num > PAGE_SIZE) {
 999                 ti->error = "Invalid data device block size";
1000                 r = -EINVAL;
1001                 goto bad;
1002         }
1003         v->data_dev_block_bits = __ffs(num);
1004
1005         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1006             !num || (num & (num - 1)) ||
1007             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1008             num > INT_MAX) {
1009                 ti->error = "Invalid hash device block size";
1010                 r = -EINVAL;
1011                 goto bad;
1012         }
1013         v->hash_dev_block_bits = __ffs(num);
1014
1015         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1016             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1017             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1018                 ti->error = "Invalid data blocks";
1019                 r = -EINVAL;
1020                 goto bad;
1021         }
1022         v->data_blocks = num_ll;
1023
1024         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1025                 ti->error = "Data device is too small";
1026                 r = -EINVAL;
1027                 goto bad;
1028         }
1029
1030         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1031             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1032             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1033                 ti->error = "Invalid hash start";
1034                 r = -EINVAL;
1035                 goto bad;
1036         }
1037         v->hash_start = num_ll;
1038
1039         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1040         if (!v->alg_name) {
1041                 ti->error = "Cannot allocate algorithm name";
1042                 r = -ENOMEM;
1043                 goto bad;
1044         }
1045
1046         v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1047         if (IS_ERR(v->tfm)) {
1048                 ti->error = "Cannot initialize hash function";
1049                 r = PTR_ERR(v->tfm);
1050                 v->tfm = NULL;
1051                 goto bad;
1052         }
1053         v->digest_size = crypto_ahash_digestsize(v->tfm);
1054         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1055                 ti->error = "Digest size too big";
1056                 r = -EINVAL;
1057                 goto bad;
1058         }
1059         v->ahash_reqsize = sizeof(struct ahash_request) +
1060                 crypto_ahash_reqsize(v->tfm);
1061
1062         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1063         if (!v->root_digest) {
1064                 ti->error = "Cannot allocate root digest";
1065                 r = -ENOMEM;
1066                 goto bad;
1067         }
1068         if (strlen(argv[8]) != v->digest_size * 2 ||
1069             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1070                 ti->error = "Invalid root digest";
1071                 r = -EINVAL;
1072                 goto bad;
1073         }
1074
1075         if (strcmp(argv[9], "-")) {
1076                 v->salt_size = strlen(argv[9]) / 2;
1077                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1078                 if (!v->salt) {
1079                         ti->error = "Cannot allocate salt";
1080                         r = -ENOMEM;
1081                         goto bad;
1082                 }
1083                 if (strlen(argv[9]) != v->salt_size * 2 ||
1084                     hex2bin(v->salt, argv[9], v->salt_size)) {
1085                         ti->error = "Invalid salt";
1086                         r = -EINVAL;
1087                         goto bad;
1088                 }
1089         }
1090
1091         argv += 10;
1092         argc -= 10;
1093
1094         /* Optional parameters */
1095         if (argc) {
1096                 as.argc = argc;
1097                 as.argv = argv;
1098
1099                 r = verity_parse_opt_args(&as, v);
1100                 if (r < 0)
1101                         goto bad;
1102         }
1103
1104         v->hash_per_block_bits =
1105                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1106
1107         v->levels = 0;
1108         if (v->data_blocks)
1109                 while (v->hash_per_block_bits * v->levels < 64 &&
1110                        (unsigned long long)(v->data_blocks - 1) >>
1111                        (v->hash_per_block_bits * v->levels))
1112                         v->levels++;
1113
1114         if (v->levels > DM_VERITY_MAX_LEVELS) {
1115                 ti->error = "Too many tree levels";
1116                 r = -E2BIG;
1117                 goto bad;
1118         }
1119
1120         hash_position = v->hash_start;
1121         for (i = v->levels - 1; i >= 0; i--) {
1122                 sector_t s;
1123                 v->hash_level_block[i] = hash_position;
1124                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1125                                         >> ((i + 1) * v->hash_per_block_bits);
1126                 if (hash_position + s < hash_position) {
1127                         ti->error = "Hash device offset overflow";
1128                         r = -E2BIG;
1129                         goto bad;
1130                 }
1131                 hash_position += s;
1132         }
1133         v->hash_blocks = hash_position;
1134
1135         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1136                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1137                 dm_bufio_alloc_callback, NULL);
1138         if (IS_ERR(v->bufio)) {
1139                 ti->error = "Cannot initialize dm-bufio";
1140                 r = PTR_ERR(v->bufio);
1141                 v->bufio = NULL;
1142                 goto bad;
1143         }
1144
1145         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1146                 ti->error = "Hash device is too small";
1147                 r = -E2BIG;
1148                 goto bad;
1149         }
1150
1151         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1152         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1153         if (!v->verify_wq) {
1154                 ti->error = "Cannot allocate workqueue";
1155                 r = -ENOMEM;
1156                 goto bad;
1157         }
1158
1159         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1160                                 v->ahash_reqsize + v->digest_size * 2;
1161
1162         r = verity_fec_ctr(v);
1163         if (r)
1164                 goto bad;
1165
1166         ti->per_io_data_size = roundup(ti->per_io_data_size,
1167                                        __alignof__(struct dm_verity_io));
1168
1169         return 0;
1170
1171 bad:
1172         verity_dtr(ti);
1173
1174         return r;
1175 }
1176
1177 static struct target_type verity_target = {
1178         .name           = "verity",
1179         .features       = DM_TARGET_IMMUTABLE,
1180         .version        = {1, 4, 0},
1181         .module         = THIS_MODULE,
1182         .ctr            = verity_ctr,
1183         .dtr            = verity_dtr,
1184         .map            = verity_map,
1185         .status         = verity_status,
1186         .prepare_ioctl  = verity_prepare_ioctl,
1187         .iterate_devices = verity_iterate_devices,
1188         .io_hints       = verity_io_hints,
1189 };
1190
1191 static int __init dm_verity_init(void)
1192 {
1193         int r;
1194
1195         r = dm_register_target(&verity_target);
1196         if (r < 0)
1197                 DMERR("register failed %d", r);
1198
1199         return r;
1200 }
1201
1202 static void __exit dm_verity_exit(void)
1203 {
1204         dm_unregister_target(&verity_target);
1205 }
1206
1207 module_init(dm_verity_init);
1208 module_exit(dm_verity_exit);
1209
1210 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1211 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1212 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1213 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1214 MODULE_LICENSE("GPL");