drivers/md/dm-verity-target.c

   1 /*
   2  * Copyright (C) 2012 Red Hat, Inc.
   3  *
   4  * Author: Mikulas Patocka <mpatocka@redhat.com>
   5  *
   6  * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
  11  * default prefetch value. Data are read in "prefetch_cluster" chunks from the
  12  * hash device. Setting this greatly improves performance when data and hash
  13  * are on the same disk on different partitions on devices with poor random
  14  * access behavior.
  15  */
  16
  17 #include "dm-verity.h"
  18 #include "dm-verity-fec.h"
  19
  20 #include <linux/module.h>
  21 #include <linux/reboot.h>
  22
  23 #define DM_MSG_PREFIX                   "verity"
  24
  25 #define DM_VERITY_ENV_LENGTH            42
  26 #define DM_VERITY_ENV_VAR_NAME          "DM_VERITY_ERR_BLOCK_NR"
  27
  28 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
  29
  30 #define DM_VERITY_MAX_CORRUPTED_ERRS    100
  31
  32 #define DM_VERITY_OPT_LOGGING           "ignore_corruption"
  33 #define DM_VERITY_OPT_RESTART           "restart_on_corruption"
  34 #define DM_VERITY_OPT_IGN_ZEROES        "ignore_zero_blocks"
  35
  36 #define DM_VERITY_OPTS_MAX              (2 + DM_VERITY_OPTS_FEC)
  37
  38 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  39
  40 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
  41
  42 struct dm_verity_prefetch_work {
  43         struct work_struct work;
  44         struct dm_verity *v;
  45         sector_t block;
  46         unsigned n_blocks;
  47 };
  48
  49 /*
  50  * Auxiliary structure appended to each dm-bufio buffer. If the value
  51  * hash_verified is nonzero, hash of the block has been verified.
  52  *
  53  * The variable hash_verified is set to 0 when allocating the buffer, then
  54  * it can be changed to 1 and it is never reset to 0 again.
  55  *
  56  * There is no lock around this value, a race condition can at worst cause
  57  * that multiple processes verify the hash of the same buffer simultaneously
  58  * and write 1 to hash_verified simultaneously.
  59  * This condition is harmless, so we don't need locking.
  60  */
  61 struct buffer_aux {
  62         int hash_verified;
  63 };
  64
  65 /*
  66  * Initialize struct buffer_aux for a freshly created buffer.
  67  */
  68 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  69 {
  70         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  71
  72         aux->hash_verified = 0;
  73 }
  74
  75 /*
  76  * Translate input sector number to the sector number on the target device.
  77  */
  78 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  79 {
  80         return v->data_start + dm_target_offset(v->ti, bi_sector);
  81 }
  82
  83 /*
  84  * Return hash position of a specified block at a specified tree level
  85  * (0 is the lowest level).
  86  * The lowest "hash_per_block_bits"-bits of the result denote hash position
  87  * inside a hash block. The remaining bits denote location of the hash block.
  88  */
  89 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
  90                                          int level)
  91 {
  92         return block >> (level * v->hash_per_block_bits);
  93 }
  94
  95 /*
  96  * Callback function for asynchrnous crypto API completion notification
  97  */
  98 static void verity_op_done(struct crypto_async_request *base, int err)
  99 {
 100         struct verity_result *res = (struct verity_result *)base->data;
 101
 102         if (err == -EINPROGRESS)
 103                 return;
 104
 105         res->err = err;
 106         complete(&res->completion);
 107 }
 108
 109 /*
 110  * Wait for async crypto API callback
 111  */
 112 static inline int verity_complete_op(struct verity_result *res, int ret)
 113 {
 114         switch (ret) {
 115         case 0:
 116                 break;
 117
 118         case -EINPROGRESS:
 119         case -EBUSY:
 120                 ret = wait_for_completion_interruptible(&res->completion);
 121                 if (!ret)
 122                         ret = res->err;
 123                 reinit_completion(&res->completion);
 124                 break;
 125
 126         default:
 127                 DMERR("verity_wait_hash: crypto op submission failed: %d", ret);
 128         }
 129
 130         if (unlikely(ret < 0))
 131                 DMERR("verity_wait_hash: crypto op failed: %d", ret);
 132
 133         return ret;
 134 }
 135
 136 static int verity_hash_update(struct dm_verity *v, struct ahash_request *req,
 137                                 const u8 *data, size_t len,
 138                                 struct verity_result *res)
 139 {
 140         struct scatterlist sg;
 141
 142         if (likely(!is_vmalloc_addr(data))) {
 143                 sg_init_one(&sg, data, len);
 144                 ahash_request_set_crypt(req, &sg, NULL, len);
 145                 return verity_complete_op(res, crypto_ahash_update(req));
 146         } else {
 147                 do {
 148                         int r;
 149                         size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 150                         flush_kernel_vmap_range((void *)data, this_step);
 151                         sg_init_table(&sg, 1);
 152                         sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 153                         ahash_request_set_crypt(req, &sg, NULL, this_step);
 154                         r = verity_complete_op(res, crypto_ahash_update(req));
 155                         if (unlikely(r))
 156                                 return r;
 157                         data += this_step;
 158                         len -= this_step;
 159                 } while (len);
 160                 return 0;
 161         }
 162 }
 163
 164 /*
 165  * Wrapper for crypto_ahash_init, which handles verity salting.
 166  */
 167 static int verity_hash_init(struct dm_verity *v, struct ahash_request *req,
 168                                 struct verity_result *res)
 169 {
 170         int r;
 171
 172         ahash_request_set_tfm(req, v->tfm);
 173         ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP |
 174                                         CRYPTO_TFM_REQ_MAY_BACKLOG,
 175                                         verity_op_done, (void *)res);
 176         init_completion(&res->completion);
 177
 178         r = verity_complete_op(res, crypto_ahash_init(req));
 179
 180         if (unlikely(r < 0)) {
 181                 DMERR("crypto_ahash_init failed: %d", r);
 182                 return r;
 183         }
 184
 185         if (likely(v->salt_size && (v->version >= 1)))
 186                 r = verity_hash_update(v, req, v->salt, v->salt_size, res);
 187
 188         return r;
 189 }
 190
 191 static int verity_hash_final(struct dm_verity *v, struct ahash_request *req,
 192                              u8 *digest, struct verity_result *res)
 193 {
 194         int r;
 195
 196         if (unlikely(v->salt_size && (!v->version))) {
 197                 r = verity_hash_update(v, req, v->salt, v->salt_size, res);
 198
 199                 if (r < 0) {
 200                         DMERR("verity_hash_final failed updating salt: %d", r);
 201                         goto out;
 202                 }
 203         }
 204
 205         ahash_request_set_crypt(req, NULL, digest, 0);
 206         r = verity_complete_op(res, crypto_ahash_final(req));
 207 out:
 208         return r;
 209 }
 210
 211 int verity_hash(struct dm_verity *v, struct ahash_request *req,
 212                 const u8 *data, size_t len, u8 *digest)
 213 {
 214         int r;
 215         struct verity_result res;
 216
 217         r = verity_hash_init(v, req, &res);
 218         if (unlikely(r < 0))
 219                 goto out;
 220
 221         r = verity_hash_update(v, req, data, len, &res);
 222         if (unlikely(r < 0))
 223                 goto out;
 224
 225         r = verity_hash_final(v, req, digest, &res);
 226
 227 out:
 228         return r;
 229 }
 230
 231 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 232                                  sector_t *hash_block, unsigned *offset)
 233 {
 234         sector_t position = verity_position_at_level(v, block, level);
 235         unsigned idx;
 236
 237         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 238
 239         if (!offset)
 240                 return;
 241
 242         idx = position & ((1 << v->hash_per_block_bits) - 1);
 243         if (!v->version)
 244                 *offset = idx * v->digest_size;
 245         else
 246                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 247 }
 248
 249 /*
 250  * Handle verification errors.
 251  */
 252 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 253                              unsigned long long block)
 254 {
 255         char verity_env[DM_VERITY_ENV_LENGTH];
 256         char *envp[] = { verity_env, NULL };
 257         const char *type_str = "";
 258         struct mapped_device *md = dm_table_get_md(v->ti->table);
 259
 260         /* Corruption should be visible in device status in all modes */
 261         v->hash_failed = 1;
 262
 263         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 264                 goto out;
 265
 266         v->corrupted_errs++;
 267
 268         switch (type) {
 269         case DM_VERITY_BLOCK_TYPE_DATA:
 270                 type_str = "data";
 271                 break;
 272         case DM_VERITY_BLOCK_TYPE_METADATA:
 273                 type_str = "metadata";
 274                 break;
 275         default:
 276                 BUG();
 277         }
 278
 279         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 280                     type_str, block);
 281
 282         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS)
 283                 DMERR("%s: reached maximum errors", v->data_dev->name);
 284
 285         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 286                 DM_VERITY_ENV_VAR_NAME, type, block);
 287
 288         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 289
 290 out:
 291         if (v->mode == DM_VERITY_MODE_LOGGING)
 292                 return 0;
 293
 294         if (v->mode == DM_VERITY_MODE_RESTART)
 295                 kernel_restart("dm-verity device corrupted");
 296
 297         return 1;
 298 }
 299
 300 /*
 301  * Verify hash of a metadata block pertaining to the specified data block
 302  * ("block" argument) at a specified level ("level" argument).
 303  *
 304  * On successful return, verity_io_want_digest(v, io) contains the hash value
 305  * for a lower tree level or for the data block (if we're at the lowest level).
 306  *
 307  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 308  * If "skip_unverified" is false, unverified buffer is hashed and verified
 309  * against current value of verity_io_want_digest(v, io).
 310  */
 311 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 312                                sector_t block, int level, bool skip_unverified,
 313                                u8 *want_digest)
 314 {
 315         struct dm_buffer *buf;
 316         struct buffer_aux *aux;
 317         u8 *data;
 318         int r;
 319         sector_t hash_block;
 320         unsigned offset;
 321
 322         verity_hash_at_level(v, block, level, &hash_block, &offset);
 323
 324         data = dm_bufio_read(v->bufio, hash_block, &buf);
 325         if (IS_ERR(data))
 326                 return PTR_ERR(data);
 327
 328         aux = dm_bufio_get_aux_data(buf);
 329
 330         if (!aux->hash_verified) {
 331                 if (skip_unverified) {
 332                         r = 1;
 333                         goto release_ret_r;
 334                 }
 335
 336                 r = verity_hash(v, verity_io_hash_req(v, io),
 337                                 data, 1 << v->hash_dev_block_bits,
 338                                 verity_io_real_digest(v, io));
 339                 if (unlikely(r < 0))
 340                         goto release_ret_r;
 341
 342                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 343                                   v->digest_size) == 0))
 344                         aux->hash_verified = 1;
 345                 else if (verity_fec_decode(v, io,
 346                                            DM_VERITY_BLOCK_TYPE_METADATA,
 347                                            hash_block, data, NULL) == 0)
 348                         aux->hash_verified = 1;
 349                 else if (verity_handle_err(v,
 350                                            DM_VERITY_BLOCK_TYPE_METADATA,
 351                                            hash_block)) {
 352                         r = -EIO;
 353                         goto release_ret_r;
 354                 }
 355         }
 356
 357         data += offset;
 358         memcpy(want_digest, data, v->digest_size);
 359         r = 0;
 360
 361 release_ret_r:
 362         dm_bufio_release(buf);
 363         return r;
 364 }
 365
 366 /*
 367  * Find a hash for a given block, write it to digest and verify the integrity
 368  * of the hash tree if necessary.
 369  */
 370 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 371                           sector_t block, u8 *digest, bool *is_zero)
 372 {
 373         int r = 0, i;
 374
 375         if (likely(v->levels)) {
 376                 /*
 377                  * First, we try to get the requested hash for
 378                  * the current block. If the hash block itself is
 379                  * verified, zero is returned. If it isn't, this
 380                  * function returns 1 and we fall back to whole
 381                  * chain verification.
 382                  */
 383                 r = verity_verify_level(v, io, block, 0, true, digest);
 384                 if (likely(r <= 0))
 385                         goto out;
 386         }
 387
 388         memcpy(digest, v->root_digest, v->digest_size);
 389
 390         for (i = v->levels - 1; i >= 0; i--) {
 391                 r = verity_verify_level(v, io, block, i, false, digest);
 392                 if (unlikely(r))
 393                         goto out;
 394         }
 395 out:
 396         if (!r && v->zero_digest)
 397                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 398         else
 399                 *is_zero = false;
 400
 401         return r;
 402 }
 403
 404 /*
 405  * Calculates the digest for the given bio
 406  */
 407 int verity_for_io_block(struct dm_verity *v, struct dm_verity_io *io,
 408                         struct bvec_iter *iter, struct verity_result *res)
 409 {
 410         unsigned int todo = 1 << v->data_dev_block_bits;
 411         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 412         struct scatterlist sg;
 413         struct ahash_request *req = verity_io_hash_req(v, io);
 414
 415         do {
 416                 int r;
 417                 unsigned int len;
 418                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 419
 420                 sg_init_table(&sg, 1);
 421
 422                 len = bv.bv_len;
 423
 424                 if (likely(len >= todo))
 425                         len = todo;
 426                 /*
 427                  * Operating on a single page at a time looks suboptimal
 428                  * until you consider the typical block size is 4,096B.
 429                  * Going through this loops twice should be very rare.
 430                  */
 431                 sg_set_page(&sg, bv.bv_page, len, bv.bv_offset);
 432                 ahash_request_set_crypt(req, &sg, NULL, len);
 433                 r = verity_complete_op(res, crypto_ahash_update(req));
 434
 435                 if (unlikely(r < 0)) {
 436                         DMERR("verity_for_io_block crypto op failed: %d", r);
 437                         return r;
 438                 }
 439
 440                 bio_advance_iter(bio, iter, len);
 441                 todo -= len;
 442         } while (todo);
 443
 444         return 0;
 445 }
 446
 447 /*
 448  * Calls function process for 1 << v->data_dev_block_bits bytes in the bio_vec
 449  * starting from iter.
 450  */
 451 int verity_for_bv_block(struct dm_verity *v, struct dm_verity_io *io,
 452                         struct bvec_iter *iter,
 453                         int (*process)(struct dm_verity *v,
 454                                        struct dm_verity_io *io, u8 *data,
 455                                        size_t len))
 456 {
 457         unsigned todo = 1 << v->data_dev_block_bits;
 458         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 459
 460         do {
 461                 int r;
 462                 u8 *page;
 463                 unsigned len;
 464                 struct bio_vec bv = bio_iter_iovec(bio, *iter);
 465
 466                 page = kmap_atomic(bv.bv_page);
 467                 len = bv.bv_len;
 468
 469                 if (likely(len >= todo))
 470                         len = todo;
 471
 472                 r = process(v, io, page + bv.bv_offset, len);
 473                 kunmap_atomic(page);
 474
 475                 if (r < 0)
 476                         return r;
 477
 478                 bio_advance_iter(bio, iter, len);
 479                 todo -= len;
 480         } while (todo);
 481
 482         return 0;
 483 }
 484
 485 static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 486                           u8 *data, size_t len)
 487 {
 488         memset(data, 0, len);
 489         return 0;
 490 }
 491
 492 /*
 493  * Verify one "dm_verity_io" structure.
 494  */
 495 static int verity_verify_io(struct dm_verity_io *io)
 496 {
 497         bool is_zero;
 498         struct dm_verity *v = io->v;
 499         struct bvec_iter start;
 500         unsigned b;
 501         struct verity_result res;
 502
 503         for (b = 0; b < io->n_blocks; b++) {
 504                 int r;
 505                 struct ahash_request *req = verity_io_hash_req(v, io);
 506
 507                 r = verity_hash_for_block(v, io, io->block + b,
 508                                           verity_io_want_digest(v, io),
 509                                           &is_zero);
 510                 if (unlikely(r < 0))
 511                         return r;
 512
 513                 if (is_zero) {
 514                         /*
 515                          * If we expect a zero block, don't validate, just
 516                          * return zeros.
 517                          */
 518                         r = verity_for_bv_block(v, io, &io->iter,
 519                                                 verity_bv_zero);
 520                         if (unlikely(r < 0))
 521                                 return r;
 522
 523                         continue;
 524                 }
 525
 526                 r = verity_hash_init(v, req, &res);
 527                 if (unlikely(r < 0))
 528                         return r;
 529
 530                 start = io->iter;
 531                 r = verity_for_io_block(v, io, &io->iter, &res);
 532                 if (unlikely(r < 0))
 533                         return r;
 534
 535                 r = verity_hash_final(v, req, verity_io_real_digest(v, io),
 536                                         &res);
 537                 if (unlikely(r < 0))
 538                         return r;
 539
 540                 if (likely(memcmp(verity_io_real_digest(v, io),
 541                                   verity_io_want_digest(v, io), v->digest_size) == 0))
 542                         continue;
 543                 else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
 544                                            io->block + b, NULL, &start) == 0)
 545                         continue;
 546                 else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
 547                                            io->block + b))
 548                         return -EIO;
 549         }
 550
 551         return 0;
 552 }
 553
 554 /*
 555  * Skip verity work in response to I/O error when system is shutting down.
 556  */
 557 static inline bool verity_is_system_shutting_down(void)
 558 {
 559         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 560                 || system_state == SYSTEM_RESTART;
 561 }
 562
 563 /*
 564  * End one "io" structure with a given error.
 565  */
 566 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 567 {
 568         struct dm_verity *v = io->v;
 569         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 570
 571         bio->bi_end_io = io->orig_bi_end_io;
 572         bio->bi_status = status;
 573
 574         verity_fec_finish_io(io);
 575
 576         bio_endio(bio);
 577 }
 578
 579 static void verity_work(struct work_struct *w)
 580 {
 581         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 582
 583         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 584 }
 585
 586 static void verity_end_io(struct bio *bio)
 587 {
 588         struct dm_verity_io *io = bio->bi_private;
 589
 590         if (bio->bi_status &&
 591             (!verity_fec_is_enabled(io->v) || verity_is_system_shutting_down())) {
 592                 verity_finish_io(io, bio->bi_status);
 593                 return;
 594         }
 595
 596         INIT_WORK(&io->work, verity_work);
 597         queue_work(io->v->verify_wq, &io->work);
 598 }
 599
 600 /*
 601  * Prefetch buffers for the specified io.
 602  * The root buffer is not prefetched, it is assumed that it will be cached
 603  * all the time.
 604  */
 605 static void verity_prefetch_io(struct work_struct *work)
 606 {
 607         struct dm_verity_prefetch_work *pw =
 608                 container_of(work, struct dm_verity_prefetch_work, work);
 609         struct dm_verity *v = pw->v;
 610         int i;
 611
 612         for (i = v->levels - 2; i >= 0; i--) {
 613                 sector_t hash_block_start;
 614                 sector_t hash_block_end;
 615                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 616                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 617                 if (!i) {
 618                         unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
 619
 620                         cluster >>= v->data_dev_block_bits;
 621                         if (unlikely(!cluster))
 622                                 goto no_prefetch_cluster;
 623
 624                         if (unlikely(cluster & (cluster - 1)))
 625                                 cluster = 1 << __fls(cluster);
 626
 627                         hash_block_start &= ~(sector_t)(cluster - 1);
 628                         hash_block_end |= cluster - 1;
 629                         if (unlikely(hash_block_end >= v->hash_blocks))
 630                                 hash_block_end = v->hash_blocks - 1;
 631                 }
 632 no_prefetch_cluster:
 633                 dm_bufio_prefetch(v->bufio, hash_block_start,
 634                                   hash_block_end - hash_block_start + 1);
 635         }
 636
 637         kfree(pw);
 638 }
 639
 640 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 641 {
 642         struct dm_verity_prefetch_work *pw;
 643
 644         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 645                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 646
 647         if (!pw)
 648                 return;
 649
 650         INIT_WORK(&pw->work, verity_prefetch_io);
 651         pw->v = v;
 652         pw->block = io->block;
 653         pw->n_blocks = io->n_blocks;
 654         queue_work(v->verify_wq, &pw->work);
 655 }
 656
 657 /*
 658  * Bio map function. It allocates dm_verity_io structure and bio vector and
 659  * fills them. Then it issues prefetches and the I/O.
 660  */
 661 static int verity_map(struct dm_target *ti, struct bio *bio)
 662 {
 663         struct dm_verity *v = ti->private;
 664         struct dm_verity_io *io;
 665
 666         bio_set_dev(bio, v->data_dev->bdev);
 667         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 668
 669         if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 670             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 671                 DMERR_LIMIT("unaligned io");
 672                 return DM_MAPIO_KILL;
 673         }
 674
 675         if (bio_end_sector(bio) >>
 676             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 677                 DMERR_LIMIT("io out of range");
 678                 return DM_MAPIO_KILL;
 679         }
 680
 681         if (bio_data_dir(bio) == WRITE)
 682                 return DM_MAPIO_KILL;
 683
 684         io = dm_per_bio_data(bio, ti->per_io_data_size);
 685         io->v = v;
 686         io->orig_bi_end_io = bio->bi_end_io;
 687         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 688         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 689
 690         bio->bi_end_io = verity_end_io;
 691         bio->bi_private = io;
 692         io->iter = bio->bi_iter;
 693
 694         verity_fec_init_io(io);
 695
 696         verity_submit_prefetch(v, io);
 697
 698         generic_make_request(bio);
 699
 700         return DM_MAPIO_SUBMITTED;
 701 }
 702
 703 /*
 704  * Status: V (valid) or C (corruption found)
 705  */
 706 static void verity_status(struct dm_target *ti, status_type_t type,
 707                           unsigned status_flags, char *result, unsigned maxlen)
 708 {
 709         struct dm_verity *v = ti->private;
 710         unsigned args = 0;
 711         unsigned sz = 0;
 712         unsigned x;
 713
 714         switch (type) {
 715         case STATUSTYPE_INFO:
 716                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 717                 break;
 718         case STATUSTYPE_TABLE:
 719                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 720                         v->version,
 721                         v->data_dev->name,
 722                         v->hash_dev->name,
 723                         1 << v->data_dev_block_bits,
 724                         1 << v->hash_dev_block_bits,
 725                         (unsigned long long)v->data_blocks,
 726                         (unsigned long long)v->hash_start,
 727                         v->alg_name
 728                         );
 729                 for (x = 0; x < v->digest_size; x++)
 730                         DMEMIT("%02x", v->root_digest[x]);
 731                 DMEMIT(" ");
 732                 if (!v->salt_size)
 733                         DMEMIT("-");
 734                 else
 735                         for (x = 0; x < v->salt_size; x++)
 736                                 DMEMIT("%02x", v->salt[x]);
 737                 if (v->mode != DM_VERITY_MODE_EIO)
 738                         args++;
 739                 if (verity_fec_is_enabled(v))
 740                         args += DM_VERITY_OPTS_FEC;
 741                 if (v->zero_digest)
 742                         args++;
 743                 if (!args)
 744                         return;
 745                 DMEMIT(" %u", args);
 746                 if (v->mode != DM_VERITY_MODE_EIO) {
 747                         DMEMIT(" ");
 748                         switch (v->mode) {
 749                         case DM_VERITY_MODE_LOGGING:
 750                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 751                                 break;
 752                         case DM_VERITY_MODE_RESTART:
 753                                 DMEMIT(DM_VERITY_OPT_RESTART);
 754                                 break;
 755                         default:
 756                                 BUG();
 757                         }
 758                 }
 759                 if (v->zero_digest)
 760                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 761                 sz = verity_fec_status_table(v, sz, result, maxlen);
 762                 break;
 763         }
 764 }
 765
 766 static int verity_prepare_ioctl(struct dm_target *ti,
 767                 struct block_device **bdev, fmode_t *mode)
 768 {
 769         struct dm_verity *v = ti->private;
 770
 771         *bdev = v->data_dev->bdev;
 772
 773         if (v->data_start ||
 774             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
 775                 return 1;
 776         return 0;
 777 }
 778
 779 static int verity_iterate_devices(struct dm_target *ti,
 780                                   iterate_devices_callout_fn fn, void *data)
 781 {
 782         struct dm_verity *v = ti->private;
 783
 784         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 785 }
 786
 787 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 788 {
 789         struct dm_verity *v = ti->private;
 790
 791         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 792                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 793
 794         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 795                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 796
 797         blk_limits_io_min(limits, limits->logical_block_size);
 798 }
 799
 800 static void verity_dtr(struct dm_target *ti)
 801 {
 802         struct dm_verity *v = ti->private;
 803
 804         if (v->verify_wq)
 805                 destroy_workqueue(v->verify_wq);
 806
 807         if (v->bufio)
 808                 dm_bufio_client_destroy(v->bufio);
 809
 810         kfree(v->salt);
 811         kfree(v->root_digest);
 812         kfree(v->zero_digest);
 813
 814         if (v->tfm)
 815                 crypto_free_ahash(v->tfm);
 816
 817         kfree(v->alg_name);
 818
 819         if (v->hash_dev)
 820                 dm_put_device(ti, v->hash_dev);
 821
 822         if (v->data_dev)
 823                 dm_put_device(ti, v->data_dev);
 824
 825         verity_fec_dtr(v);
 826
 827         kfree(v);
 828 }
 829
 830 static int verity_alloc_zero_digest(struct dm_verity *v)
 831 {
 832         int r = -ENOMEM;
 833         struct ahash_request *req;
 834         u8 *zero_data;
 835
 836         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
 837
 838         if (!v->zero_digest)
 839                 return r;
 840
 841         req = kmalloc(v->ahash_reqsize, GFP_KERNEL);
 842
 843         if (!req)
 844                 return r; /* verity_dtr will free zero_digest */
 845
 846         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
 847
 848         if (!zero_data)
 849                 goto out;
 850
 851         r = verity_hash(v, req, zero_data, 1 << v->data_dev_block_bits,
 852                         v->zero_digest);
 853
 854 out:
 855         kfree(req);
 856         kfree(zero_data);
 857
 858         return r;
 859 }
 860
 861 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
 862 {
 863         int r;
 864         unsigned argc;
 865         struct dm_target *ti = v->ti;
 866         const char *arg_name;
 867
 868         static const struct dm_arg _args[] = {
 869                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
 870         };
 871
 872         r = dm_read_arg_group(_args, as, &argc, &ti->error);
 873         if (r)
 874                 return -EINVAL;
 875
 876         if (!argc)
 877                 return 0;
 878
 879         do {
 880                 arg_name = dm_shift_arg(as);
 881                 argc--;
 882
 883                 if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING)) {
 884                         v->mode = DM_VERITY_MODE_LOGGING;
 885                         continue;
 886
 887                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART)) {
 888                         v->mode = DM_VERITY_MODE_RESTART;
 889                         continue;
 890
 891                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
 892                         r = verity_alloc_zero_digest(v);
 893                         if (r) {
 894                                 ti->error = "Cannot allocate zero digest";
 895                                 return r;
 896                         }
 897                         continue;
 898
 899                 } else if (verity_is_fec_opt_arg(arg_name)) {
 900                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
 901                         if (r)
 902                                 return r;
 903                         continue;
 904                 }
 905
 906                 ti->error = "Unrecognized verity feature request";
 907                 return -EINVAL;
 908         } while (argc && !r);
 909
 910         return r;
 911 }
 912
 913 /*
 914  * Target parameters:
 915  *      <version>       The current format is version 1.
 916  *                      Vsn 0 is compatible with original Chromium OS releases.
 917  *      <data device>
 918  *      <hash device>
 919  *      <data block size>
 920  *      <hash block size>
 921  *      <the number of data blocks>
 922  *      <hash start block>
 923  *      <algorithm>
 924  *      <digest>
 925  *      <salt>          Hex string or "-" if no salt.
 926  */
 927 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 928 {
 929         struct dm_verity *v;
 930         struct dm_arg_set as;
 931         unsigned int num;
 932         unsigned long long num_ll;
 933         int r;
 934         int i;
 935         sector_t hash_position;
 936         char dummy;
 937
 938         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
 939         if (!v) {
 940                 ti->error = "Cannot allocate verity structure";
 941                 return -ENOMEM;
 942         }
 943         ti->private = v;
 944         v->ti = ti;
 945
 946         r = verity_fec_ctr_alloc(v);
 947         if (r)
 948                 goto bad;
 949
 950         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
 951                 ti->error = "Device must be readonly";
 952                 r = -EINVAL;
 953                 goto bad;
 954         }
 955
 956         if (argc < 10) {
 957                 ti->error = "Not enough arguments";
 958                 r = -EINVAL;
 959                 goto bad;
 960         }
 961
 962         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
 963             num > 1) {
 964                 ti->error = "Invalid version";
 965                 r = -EINVAL;
 966                 goto bad;
 967         }
 968         v->version = num;
 969
 970         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
 971         if (r) {
 972                 ti->error = "Data device lookup failed";
 973                 goto bad;
 974         }
 975
 976         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
 977         if (r) {
 978                 ti->error = "Hash device lookup failed";
 979                 goto bad;
 980         }
 981
 982         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
 983             !num || (num & (num - 1)) ||
 984             num < bdev_logical_block_size(v->data_dev->bdev) ||
 985             num > PAGE_SIZE) {
 986                 ti->error = "Invalid data device block size";
 987                 r = -EINVAL;
 988                 goto bad;
 989         }
 990         v->data_dev_block_bits = __ffs(num);
 991
 992         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
 993             !num || (num & (num - 1)) ||
 994             num < bdev_logical_block_size(v->hash_dev->bdev) ||
 995             num > INT_MAX) {
 996                 ti->error = "Invalid hash device block size";
 997                 r = -EINVAL;
 998                 goto bad;
 999         }
1000         v->hash_dev_block_bits = __ffs(num);
1001
1002         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1003             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1004             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1005                 ti->error = "Invalid data blocks";
1006                 r = -EINVAL;
1007                 goto bad;
1008         }
1009         v->data_blocks = num_ll;
1010
1011         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1012                 ti->error = "Data device is too small";
1013                 r = -EINVAL;
1014                 goto bad;
1015         }
1016
1017         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1018             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1019             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1020                 ti->error = "Invalid hash start";
1021                 r = -EINVAL;
1022                 goto bad;
1023         }
1024         v->hash_start = num_ll;
1025
1026         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
1027         if (!v->alg_name) {
1028                 ti->error = "Cannot allocate algorithm name";
1029                 r = -ENOMEM;
1030                 goto bad;
1031         }
1032
1033         v->tfm = crypto_alloc_ahash(v->alg_name, 0, 0);
1034         if (IS_ERR(v->tfm)) {
1035                 ti->error = "Cannot initialize hash function";
1036                 r = PTR_ERR(v->tfm);
1037                 v->tfm = NULL;
1038                 goto bad;
1039         }
1040         v->digest_size = crypto_ahash_digestsize(v->tfm);
1041         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1042                 ti->error = "Digest size too big";
1043                 r = -EINVAL;
1044                 goto bad;
1045         }
1046         v->ahash_reqsize = sizeof(struct ahash_request) +
1047                 crypto_ahash_reqsize(v->tfm);
1048
1049         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1050         if (!v->root_digest) {
1051                 ti->error = "Cannot allocate root digest";
1052                 r = -ENOMEM;
1053                 goto bad;
1054         }
1055         if (strlen(argv[8]) != v->digest_size * 2 ||
1056             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1057                 ti->error = "Invalid root digest";
1058                 r = -EINVAL;
1059                 goto bad;
1060         }
1061
1062         if (strcmp(argv[9], "-")) {
1063                 v->salt_size = strlen(argv[9]) / 2;
1064                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1065                 if (!v->salt) {
1066                         ti->error = "Cannot allocate salt";
1067                         r = -ENOMEM;
1068                         goto bad;
1069                 }
1070                 if (strlen(argv[9]) != v->salt_size * 2 ||
1071                     hex2bin(v->salt, argv[9], v->salt_size)) {
1072                         ti->error = "Invalid salt";
1073                         r = -EINVAL;
1074                         goto bad;
1075                 }
1076         }
1077
1078         argv += 10;
1079         argc -= 10;
1080
1081         /* Optional parameters */
1082         if (argc) {
1083                 as.argc = argc;
1084                 as.argv = argv;
1085
1086                 r = verity_parse_opt_args(&as, v);
1087                 if (r < 0)
1088                         goto bad;
1089         }
1090
1091         v->hash_per_block_bits =
1092                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1093
1094         v->levels = 0;
1095         if (v->data_blocks)
1096                 while (v->hash_per_block_bits * v->levels < 64 &&
1097                        (unsigned long long)(v->data_blocks - 1) >>
1098                        (v->hash_per_block_bits * v->levels))
1099                         v->levels++;
1100
1101         if (v->levels > DM_VERITY_MAX_LEVELS) {
1102                 ti->error = "Too many tree levels";
1103                 r = -E2BIG;
1104                 goto bad;
1105         }
1106
1107         hash_position = v->hash_start;
1108         for (i = v->levels - 1; i >= 0; i--) {
1109                 sector_t s;
1110                 v->hash_level_block[i] = hash_position;
1111                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1112                                         >> ((i + 1) * v->hash_per_block_bits);
1113                 if (hash_position + s < hash_position) {
1114                         ti->error = "Hash device offset overflow";
1115                         r = -E2BIG;
1116                         goto bad;
1117                 }
1118                 hash_position += s;
1119         }
1120         v->hash_blocks = hash_position;
1121
1122         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1123                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1124                 dm_bufio_alloc_callback, NULL);
1125         if (IS_ERR(v->bufio)) {
1126                 ti->error = "Cannot initialize dm-bufio";
1127                 r = PTR_ERR(v->bufio);
1128                 v->bufio = NULL;
1129                 goto bad;
1130         }
1131
1132         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1133                 ti->error = "Hash device is too small";
1134                 r = -E2BIG;
1135                 goto bad;
1136         }
1137
1138         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
1139         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
1140         if (!v->verify_wq) {
1141                 ti->error = "Cannot allocate workqueue";
1142                 r = -ENOMEM;
1143                 goto bad;
1144         }
1145
1146         ti->per_io_data_size = sizeof(struct dm_verity_io) +
1147                                 v->ahash_reqsize + v->digest_size * 2;
1148
1149         r = verity_fec_ctr(v);
1150         if (r)
1151                 goto bad;
1152
1153         ti->per_io_data_size = roundup(ti->per_io_data_size,
1154                                        __alignof__(struct dm_verity_io));
1155
1156         return 0;
1157
1158 bad:
1159         verity_dtr(ti);
1160
1161         return r;
1162 }
1163
1164 static struct target_type verity_target = {
1165         .name           = "verity",
1166         .version        = {1, 3, 0},
1167         .module         = THIS_MODULE,
1168         .ctr            = verity_ctr,
1169         .dtr            = verity_dtr,
1170         .map            = verity_map,
1171         .status         = verity_status,
1172         .prepare_ioctl  = verity_prepare_ioctl,
1173         .iterate_devices = verity_iterate_devices,
1174         .io_hints       = verity_io_hints,
1175 };
1176
1177 static int __init dm_verity_init(void)
1178 {
1179         int r;
1180
1181         r = dm_register_target(&verity_target);
1182         if (r < 0)
1183                 DMERR("register failed %d", r);
1184
1185         return r;
1186 }
1187
1188 static void __exit dm_verity_exit(void)
1189 {
1190         dm_unregister_target(&verity_target);
1191 }
1192
1193 module_init(dm_verity_init);
1194 module_exit(dm_verity_exit);
1195
1196 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1197 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1198 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1199 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1200 MODULE_LICENSE("GPL");