drivers/md/dm-verity-target.c

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