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