drivers/md/dm-verity.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-bufio.h"
  18
  19 #include <linux/module.h>
  20 #include <linux/device-mapper.h>
  21 #include <crypto/hash.h>
  22
  23 #define DM_MSG_PREFIX                   "verity"
  24
  25 #define DM_VERITY_IO_VEC_INLINE         16
  26 #define DM_VERITY_MEMPOOL_SIZE          4
  27 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
  28
  29 #define DM_VERITY_MAX_LEVELS            63
  30
  31 static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  32
  33 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
  34
  35 struct dm_verity {
  36         struct dm_dev *data_dev;
  37         struct dm_dev *hash_dev;
  38         struct dm_target *ti;
  39         struct dm_bufio_client *bufio;
  40         char *alg_name;
  41         struct crypto_shash *tfm;
  42         u8 *root_digest;        /* digest of the root block */
  43         u8 *salt;               /* salt: its size is salt_size */
  44         unsigned salt_size;
  45         sector_t data_start;    /* data offset in 512-byte sectors */
  46         sector_t hash_start;    /* hash start in blocks */
  47         sector_t data_blocks;   /* the number of data blocks */
  48         sector_t hash_blocks;   /* the number of hash blocks */
  49         unsigned char data_dev_block_bits;      /* log2(data blocksize) */
  50         unsigned char hash_dev_block_bits;      /* log2(hash blocksize) */
  51         unsigned char hash_per_block_bits;      /* log2(hashes in hash block) */
  52         unsigned char levels;   /* the number of tree levels */
  53         unsigned char version;
  54         unsigned digest_size;   /* digest size for the current hash algorithm */
  55         unsigned shash_descsize;/* the size of temporary space for crypto */
  56         int hash_failed;        /* set to 1 if hash of any block failed */
  57
  58         mempool_t *vec_mempool; /* mempool of bio vector */
  59
  60         struct workqueue_struct *verify_wq;
  61
  62         /* starting blocks for each tree level. 0 is the lowest level. */
  63         sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
  64 };
  65
  66 struct dm_verity_io {
  67         struct dm_verity *v;
  68
  69         /* original values of bio->bi_end_io and bio->bi_private */
  70         bio_end_io_t *orig_bi_end_io;
  71         void *orig_bi_private;
  72
  73         sector_t block;
  74         unsigned n_blocks;
  75
  76         struct bvec_iter iter;
  77
  78         struct work_struct work;
  79
  80         /*
  81          * Three variably-size fields follow this struct:
  82          *
  83          * u8 hash_desc[v->shash_descsize];
  84          * u8 real_digest[v->digest_size];
  85          * u8 want_digest[v->digest_size];
  86          *
  87          * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
  88          */
  89 };
  90
  91 struct dm_verity_prefetch_work {
  92         struct work_struct work;
  93         struct dm_verity *v;
  94         sector_t block;
  95         unsigned n_blocks;
  96 };
  97
  98 static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
  99 {
 100         return (struct shash_desc *)(io + 1);
 101 }
 102
 103 static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
 104 {
 105         return (u8 *)(io + 1) + v->shash_descsize;
 106 }
 107
 108 static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
 109 {
 110         return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
 111 }
 112
 113 /*
 114  * Auxiliary structure appended to each dm-bufio buffer. If the value
 115  * hash_verified is nonzero, hash of the block has been verified.
 116  *
 117  * The variable hash_verified is set to 0 when allocating the buffer, then
 118  * it can be changed to 1 and it is never reset to 0 again.
 119  *
 120  * There is no lock around this value, a race condition can at worst cause
 121  * that multiple processes verify the hash of the same buffer simultaneously
 122  * and write 1 to hash_verified simultaneously.
 123  * This condition is harmless, so we don't need locking.
 124  */
 125 struct buffer_aux {
 126         int hash_verified;
 127 };
 128
 129 /*
 130  * Initialize struct buffer_aux for a freshly created buffer.
 131  */
 132 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
 133 {
 134         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
 135
 136         aux->hash_verified = 0;
 137 }
 138
 139 /*
 140  * Translate input sector number to the sector number on the target device.
 141  */
 142 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
 143 {
 144         return v->data_start + dm_target_offset(v->ti, bi_sector);
 145 }
 146
 147 /*
 148  * Return hash position of a specified block at a specified tree level
 149  * (0 is the lowest level).
 150  * The lowest "hash_per_block_bits"-bits of the result denote hash position
 151  * inside a hash block. The remaining bits denote location of the hash block.
 152  */
 153 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
 154                                          int level)
 155 {
 156         return block >> (level * v->hash_per_block_bits);
 157 }
 158
 159 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 160                                  sector_t *hash_block, unsigned *offset)
 161 {
 162         sector_t position = verity_position_at_level(v, block, level);
 163         unsigned idx;
 164
 165         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 166
 167         if (!offset)
 168                 return;
 169
 170         idx = position & ((1 << v->hash_per_block_bits) - 1);
 171         if (!v->version)
 172                 *offset = idx * v->digest_size;
 173         else
 174                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 175 }
 176
 177 /*
 178  * Verify hash of a metadata block pertaining to the specified data block
 179  * ("block" argument) at a specified level ("level" argument).
 180  *
 181  * On successful return, io_want_digest(v, io) contains the hash value for
 182  * a lower tree level or for the data block (if we're at the lowest leve).
 183  *
 184  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 185  * If "skip_unverified" is false, unverified buffer is hashed and verified
 186  * against current value of io_want_digest(v, io).
 187  */
 188 static int verity_verify_level(struct dm_verity_io *io, sector_t block,
 189                                int level, bool skip_unverified)
 190 {
 191         struct dm_verity *v = io->v;
 192         struct dm_buffer *buf;
 193         struct buffer_aux *aux;
 194         u8 *data;
 195         int r;
 196         sector_t hash_block;
 197         unsigned offset;
 198
 199         verity_hash_at_level(v, block, level, &hash_block, &offset);
 200
 201         data = dm_bufio_read(v->bufio, hash_block, &buf);
 202         if (unlikely(IS_ERR(data)))
 203                 return PTR_ERR(data);
 204
 205         aux = dm_bufio_get_aux_data(buf);
 206
 207         if (!aux->hash_verified) {
 208                 struct shash_desc *desc;
 209                 u8 *result;
 210
 211                 if (skip_unverified) {
 212                         r = 1;
 213                         goto release_ret_r;
 214                 }
 215
 216                 desc = io_hash_desc(v, io);
 217                 desc->tfm = v->tfm;
 218                 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 219                 r = crypto_shash_init(desc);
 220                 if (r < 0) {
 221                         DMERR("crypto_shash_init failed: %d", r);
 222                         goto release_ret_r;
 223                 }
 224
 225                 if (likely(v->version >= 1)) {
 226                         r = crypto_shash_update(desc, v->salt, v->salt_size);
 227                         if (r < 0) {
 228                                 DMERR("crypto_shash_update failed: %d", r);
 229                                 goto release_ret_r;
 230                         }
 231                 }
 232
 233                 r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
 234                 if (r < 0) {
 235                         DMERR("crypto_shash_update failed: %d", r);
 236                         goto release_ret_r;
 237                 }
 238
 239                 if (!v->version) {
 240                         r = crypto_shash_update(desc, v->salt, v->salt_size);
 241                         if (r < 0) {
 242                                 DMERR("crypto_shash_update failed: %d", r);
 243                                 goto release_ret_r;
 244                         }
 245                 }
 246
 247                 result = io_real_digest(v, io);
 248                 r = crypto_shash_final(desc, result);
 249                 if (r < 0) {
 250                         DMERR("crypto_shash_final failed: %d", r);
 251                         goto release_ret_r;
 252                 }
 253                 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
 254                         DMERR_LIMIT("metadata block %llu is corrupted",
 255                                 (unsigned long long)hash_block);
 256                         v->hash_failed = 1;
 257                         r = -EIO;
 258                         goto release_ret_r;
 259                 } else
 260                         aux->hash_verified = 1;
 261         }
 262
 263         data += offset;
 264
 265         memcpy(io_want_digest(v, io), data, v->digest_size);
 266
 267         dm_bufio_release(buf);
 268         return 0;
 269
 270 release_ret_r:
 271         dm_bufio_release(buf);
 272
 273         return r;
 274 }
 275
 276 /*
 277  * Verify one "dm_verity_io" structure.
 278  */
 279 static int verity_verify_io(struct dm_verity_io *io)
 280 {
 281         struct dm_verity *v = io->v;
 282         struct bio *bio = dm_bio_from_per_bio_data(io,
 283                                                    v->ti->per_bio_data_size);
 284         unsigned b;
 285         int i;
 286
 287         for (b = 0; b < io->n_blocks; b++) {
 288                 struct shash_desc *desc;
 289                 u8 *result;
 290                 int r;
 291                 unsigned todo;
 292
 293                 if (likely(v->levels)) {
 294                         /*
 295                          * First, we try to get the requested hash for
 296                          * the current block. If the hash block itself is
 297                          * verified, zero is returned. If it isn't, this
 298                          * function returns 0 and we fall back to whole
 299                          * chain verification.
 300                          */
 301                         int r = verity_verify_level(io, io->block + b, 0, true);
 302                         if (likely(!r))
 303                                 goto test_block_hash;
 304                         if (r < 0)
 305                                 return r;
 306                 }
 307
 308                 memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
 309
 310                 for (i = v->levels - 1; i >= 0; i--) {
 311                         int r = verity_verify_level(io, io->block + b, i, false);
 312                         if (unlikely(r))
 313                                 return r;
 314                 }
 315
 316 test_block_hash:
 317                 desc = io_hash_desc(v, io);
 318                 desc->tfm = v->tfm;
 319                 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 320                 r = crypto_shash_init(desc);
 321                 if (r < 0) {
 322                         DMERR("crypto_shash_init failed: %d", r);
 323                         return r;
 324                 }
 325
 326                 if (likely(v->version >= 1)) {
 327                         r = crypto_shash_update(desc, v->salt, v->salt_size);
 328                         if (r < 0) {
 329                                 DMERR("crypto_shash_update failed: %d", r);
 330                                 return r;
 331                         }
 332                 }
 333                 todo = 1 << v->data_dev_block_bits;
 334                 do {
 335                         u8 *page;
 336                         unsigned len;
 337                         struct bio_vec bv = bio_iter_iovec(bio, io->iter);
 338
 339                         page = kmap_atomic(bv.bv_page);
 340                         len = bv.bv_len;
 341                         if (likely(len >= todo))
 342                                 len = todo;
 343                         r = crypto_shash_update(desc, page + bv.bv_offset, len);
 344                         kunmap_atomic(page);
 345
 346                         if (r < 0) {
 347                                 DMERR("crypto_shash_update failed: %d", r);
 348                                 return r;
 349                         }
 350
 351                         bio_advance_iter(bio, &io->iter, len);
 352                         todo -= len;
 353                 } while (todo);
 354
 355                 if (!v->version) {
 356                         r = crypto_shash_update(desc, v->salt, v->salt_size);
 357                         if (r < 0) {
 358                                 DMERR("crypto_shash_update failed: %d", r);
 359                                 return r;
 360                         }
 361                 }
 362
 363                 result = io_real_digest(v, io);
 364                 r = crypto_shash_final(desc, result);
 365                 if (r < 0) {
 366                         DMERR("crypto_shash_final failed: %d", r);
 367                         return r;
 368                 }
 369                 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
 370                         DMERR_LIMIT("data block %llu is corrupted",
 371                                 (unsigned long long)(io->block + b));
 372                         v->hash_failed = 1;
 373                         return -EIO;
 374                 }
 375         }
 376
 377         return 0;
 378 }
 379
 380 /*
 381  * End one "io" structure with a given error.
 382  */
 383 static void verity_finish_io(struct dm_verity_io *io, int error)
 384 {
 385         struct dm_verity *v = io->v;
 386         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
 387
 388         bio->bi_end_io = io->orig_bi_end_io;
 389         bio->bi_private = io->orig_bi_private;
 390
 391         bio_endio_nodec(bio, error);
 392 }
 393
 394 static void verity_work(struct work_struct *w)
 395 {
 396         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 397
 398         verity_finish_io(io, verity_verify_io(io));
 399 }
 400
 401 static void verity_end_io(struct bio *bio, int error)
 402 {
 403         struct dm_verity_io *io = bio->bi_private;
 404
 405         if (error) {
 406                 verity_finish_io(io, error);
 407                 return;
 408         }
 409
 410         INIT_WORK(&io->work, verity_work);
 411         queue_work(io->v->verify_wq, &io->work);
 412 }
 413
 414 /*
 415  * Prefetch buffers for the specified io.
 416  * The root buffer is not prefetched, it is assumed that it will be cached
 417  * all the time.
 418  */
 419 static void verity_prefetch_io(struct work_struct *work)
 420 {
 421         struct dm_verity_prefetch_work *pw =
 422                 container_of(work, struct dm_verity_prefetch_work, work);
 423         struct dm_verity *v = pw->v;
 424         int i;
 425
 426         for (i = v->levels - 2; i >= 0; i--) {
 427                 sector_t hash_block_start;
 428                 sector_t hash_block_end;
 429                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 430                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 431                 if (!i) {
 432                         unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
 433
 434                         cluster >>= v->data_dev_block_bits;
 435                         if (unlikely(!cluster))
 436                                 goto no_prefetch_cluster;
 437
 438                         if (unlikely(cluster & (cluster - 1)))
 439                                 cluster = 1 << __fls(cluster);
 440
 441                         hash_block_start &= ~(sector_t)(cluster - 1);
 442                         hash_block_end |= cluster - 1;
 443                         if (unlikely(hash_block_end >= v->hash_blocks))
 444                                 hash_block_end = v->hash_blocks - 1;
 445                 }
 446 no_prefetch_cluster:
 447                 dm_bufio_prefetch(v->bufio, hash_block_start,
 448                                   hash_block_end - hash_block_start + 1);
 449         }
 450
 451         kfree(pw);
 452 }
 453
 454 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 455 {
 456         struct dm_verity_prefetch_work *pw;
 457
 458         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 459                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 460
 461         if (!pw)
 462                 return;
 463
 464         INIT_WORK(&pw->work, verity_prefetch_io);
 465         pw->v = v;
 466         pw->block = io->block;
 467         pw->n_blocks = io->n_blocks;
 468         queue_work(v->verify_wq, &pw->work);
 469 }
 470
 471 /*
 472  * Bio map function. It allocates dm_verity_io structure and bio vector and
 473  * fills them. Then it issues prefetches and the I/O.
 474  */
 475 static int verity_map(struct dm_target *ti, struct bio *bio)
 476 {
 477         struct dm_verity *v = ti->private;
 478         struct dm_verity_io *io;
 479
 480         bio->bi_bdev = v->data_dev->bdev;
 481         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 482
 483         if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 484             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 485                 DMERR_LIMIT("unaligned io");
 486                 return -EIO;
 487         }
 488
 489         if (bio_end_sector(bio) >>
 490             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 491                 DMERR_LIMIT("io out of range");
 492                 return -EIO;
 493         }
 494
 495         if (bio_data_dir(bio) == WRITE)
 496                 return -EIO;
 497
 498         io = dm_per_bio_data(bio, ti->per_bio_data_size);
 499         io->v = v;
 500         io->orig_bi_end_io = bio->bi_end_io;
 501         io->orig_bi_private = bio->bi_private;
 502         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 503         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 504
 505         bio->bi_end_io = verity_end_io;
 506         bio->bi_private = io;
 507         io->iter = bio->bi_iter;
 508
 509         verity_submit_prefetch(v, io);
 510
 511         generic_make_request(bio);
 512
 513         return DM_MAPIO_SUBMITTED;
 514 }
 515
 516 /*
 517  * Status: V (valid) or C (corruption found)
 518  */
 519 static void verity_status(struct dm_target *ti, status_type_t type,
 520                           unsigned status_flags, char *result, unsigned maxlen)
 521 {
 522         struct dm_verity *v = ti->private;
 523         unsigned sz = 0;
 524         unsigned x;
 525
 526         switch (type) {
 527         case STATUSTYPE_INFO:
 528                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 529                 break;
 530         case STATUSTYPE_TABLE:
 531                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 532                         v->version,
 533                         v->data_dev->name,
 534                         v->hash_dev->name,
 535                         1 << v->data_dev_block_bits,
 536                         1 << v->hash_dev_block_bits,
 537                         (unsigned long long)v->data_blocks,
 538                         (unsigned long long)v->hash_start,
 539                         v->alg_name
 540                         );
 541                 for (x = 0; x < v->digest_size; x++)
 542                         DMEMIT("%02x", v->root_digest[x]);
 543                 DMEMIT(" ");
 544                 if (!v->salt_size)
 545                         DMEMIT("-");
 546                 else
 547                         for (x = 0; x < v->salt_size; x++)
 548                                 DMEMIT("%02x", v->salt[x]);
 549                 break;
 550         }
 551 }
 552
 553 static int verity_ioctl(struct dm_target *ti, unsigned cmd,
 554                         unsigned long arg)
 555 {
 556         struct dm_verity *v = ti->private;
 557         int r = 0;
 558
 559         if (v->data_start ||
 560             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
 561                 r = scsi_verify_blk_ioctl(NULL, cmd);
 562
 563         return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
 564                                      cmd, arg);
 565 }
 566
 567 static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 568                         struct bio_vec *biovec, int max_size)
 569 {
 570         struct dm_verity *v = ti->private;
 571         struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
 572
 573         if (!q->merge_bvec_fn)
 574                 return max_size;
 575
 576         bvm->bi_bdev = v->data_dev->bdev;
 577         bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
 578
 579         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 580 }
 581
 582 static int verity_iterate_devices(struct dm_target *ti,
 583                                   iterate_devices_callout_fn fn, void *data)
 584 {
 585         struct dm_verity *v = ti->private;
 586
 587         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 588 }
 589
 590 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 591 {
 592         struct dm_verity *v = ti->private;
 593
 594         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 595                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 596
 597         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 598                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 599
 600         blk_limits_io_min(limits, limits->logical_block_size);
 601 }
 602
 603 static void verity_dtr(struct dm_target *ti)
 604 {
 605         struct dm_verity *v = ti->private;
 606
 607         if (v->verify_wq)
 608                 destroy_workqueue(v->verify_wq);
 609
 610         if (v->vec_mempool)
 611                 mempool_destroy(v->vec_mempool);
 612
 613         if (v->bufio)
 614                 dm_bufio_client_destroy(v->bufio);
 615
 616         kfree(v->salt);
 617         kfree(v->root_digest);
 618
 619         if (v->tfm)
 620                 crypto_free_shash(v->tfm);
 621
 622         kfree(v->alg_name);
 623
 624         if (v->hash_dev)
 625                 dm_put_device(ti, v->hash_dev);
 626
 627         if (v->data_dev)
 628                 dm_put_device(ti, v->data_dev);
 629
 630         kfree(v);
 631 }
 632
 633 /*
 634  * Target parameters:
 635  *      <version>       The current format is version 1.
 636  *                      Vsn 0 is compatible with original Chromium OS releases.
 637  *      <data device>
 638  *      <hash device>
 639  *      <data block size>
 640  *      <hash block size>
 641  *      <the number of data blocks>
 642  *      <hash start block>
 643  *      <algorithm>
 644  *      <digest>
 645  *      <salt>          Hex string or "-" if no salt.
 646  */
 647 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 648 {
 649         struct dm_verity *v;
 650         unsigned num;
 651         unsigned long long num_ll;
 652         int r;
 653         int i;
 654         sector_t hash_position;
 655         char dummy;
 656
 657         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
 658         if (!v) {
 659                 ti->error = "Cannot allocate verity structure";
 660                 return -ENOMEM;
 661         }
 662         ti->private = v;
 663         v->ti = ti;
 664
 665         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
 666                 ti->error = "Device must be readonly";
 667                 r = -EINVAL;
 668                 goto bad;
 669         }
 670
 671         if (argc != 10) {
 672                 ti->error = "Invalid argument count: exactly 10 arguments required";
 673                 r = -EINVAL;
 674                 goto bad;
 675         }
 676
 677         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
 678             num > 1) {
 679                 ti->error = "Invalid version";
 680                 r = -EINVAL;
 681                 goto bad;
 682         }
 683         v->version = num;
 684
 685         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
 686         if (r) {
 687                 ti->error = "Data device lookup failed";
 688                 goto bad;
 689         }
 690
 691         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
 692         if (r) {
 693                 ti->error = "Data device lookup failed";
 694                 goto bad;
 695         }
 696
 697         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
 698             !num || (num & (num - 1)) ||
 699             num < bdev_logical_block_size(v->data_dev->bdev) ||
 700             num > PAGE_SIZE) {
 701                 ti->error = "Invalid data device block size";
 702                 r = -EINVAL;
 703                 goto bad;
 704         }
 705         v->data_dev_block_bits = __ffs(num);
 706
 707         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
 708             !num || (num & (num - 1)) ||
 709             num < bdev_logical_block_size(v->hash_dev->bdev) ||
 710             num > INT_MAX) {
 711                 ti->error = "Invalid hash device block size";
 712                 r = -EINVAL;
 713                 goto bad;
 714         }
 715         v->hash_dev_block_bits = __ffs(num);
 716
 717         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
 718             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
 719             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 720                 ti->error = "Invalid data blocks";
 721                 r = -EINVAL;
 722                 goto bad;
 723         }
 724         v->data_blocks = num_ll;
 725
 726         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
 727                 ti->error = "Data device is too small";
 728                 r = -EINVAL;
 729                 goto bad;
 730         }
 731
 732         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
 733             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
 734             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 735                 ti->error = "Invalid hash start";
 736                 r = -EINVAL;
 737                 goto bad;
 738         }
 739         v->hash_start = num_ll;
 740
 741         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
 742         if (!v->alg_name) {
 743                 ti->error = "Cannot allocate algorithm name";
 744                 r = -ENOMEM;
 745                 goto bad;
 746         }
 747
 748         v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
 749         if (IS_ERR(v->tfm)) {
 750                 ti->error = "Cannot initialize hash function";
 751                 r = PTR_ERR(v->tfm);
 752                 v->tfm = NULL;
 753                 goto bad;
 754         }
 755         v->digest_size = crypto_shash_digestsize(v->tfm);
 756         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
 757                 ti->error = "Digest size too big";
 758                 r = -EINVAL;
 759                 goto bad;
 760         }
 761         v->shash_descsize =
 762                 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
 763
 764         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
 765         if (!v->root_digest) {
 766                 ti->error = "Cannot allocate root digest";
 767                 r = -ENOMEM;
 768                 goto bad;
 769         }
 770         if (strlen(argv[8]) != v->digest_size * 2 ||
 771             hex2bin(v->root_digest, argv[8], v->digest_size)) {
 772                 ti->error = "Invalid root digest";
 773                 r = -EINVAL;
 774                 goto bad;
 775         }
 776
 777         if (strcmp(argv[9], "-")) {
 778                 v->salt_size = strlen(argv[9]) / 2;
 779                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
 780                 if (!v->salt) {
 781                         ti->error = "Cannot allocate salt";
 782                         r = -ENOMEM;
 783                         goto bad;
 784                 }
 785                 if (strlen(argv[9]) != v->salt_size * 2 ||
 786                     hex2bin(v->salt, argv[9], v->salt_size)) {
 787                         ti->error = "Invalid salt";
 788                         r = -EINVAL;
 789                         goto bad;
 790                 }
 791         }
 792
 793         v->hash_per_block_bits =
 794                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
 795
 796         v->levels = 0;
 797         if (v->data_blocks)
 798                 while (v->hash_per_block_bits * v->levels < 64 &&
 799                        (unsigned long long)(v->data_blocks - 1) >>
 800                        (v->hash_per_block_bits * v->levels))
 801                         v->levels++;
 802
 803         if (v->levels > DM_VERITY_MAX_LEVELS) {
 804                 ti->error = "Too many tree levels";
 805                 r = -E2BIG;
 806                 goto bad;
 807         }
 808
 809         hash_position = v->hash_start;
 810         for (i = v->levels - 1; i >= 0; i--) {
 811                 sector_t s;
 812                 v->hash_level_block[i] = hash_position;
 813                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
 814                                         >> ((i + 1) * v->hash_per_block_bits);
 815                 if (hash_position + s < hash_position) {
 816                         ti->error = "Hash device offset overflow";
 817                         r = -E2BIG;
 818                         goto bad;
 819                 }
 820                 hash_position += s;
 821         }
 822         v->hash_blocks = hash_position;
 823
 824         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
 825                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
 826                 dm_bufio_alloc_callback, NULL);
 827         if (IS_ERR(v->bufio)) {
 828                 ti->error = "Cannot initialize dm-bufio";
 829                 r = PTR_ERR(v->bufio);
 830                 v->bufio = NULL;
 831                 goto bad;
 832         }
 833
 834         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
 835                 ti->error = "Hash device is too small";
 836                 r = -E2BIG;
 837                 goto bad;
 838         }
 839
 840         ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
 841
 842         v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
 843                                         BIO_MAX_PAGES * sizeof(struct bio_vec));
 844         if (!v->vec_mempool) {
 845                 ti->error = "Cannot allocate vector mempool";
 846                 r = -ENOMEM;
 847                 goto bad;
 848         }
 849
 850         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
 851         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
 852         if (!v->verify_wq) {
 853                 ti->error = "Cannot allocate workqueue";
 854                 r = -ENOMEM;
 855                 goto bad;
 856         }
 857
 858         return 0;
 859
 860 bad:
 861         verity_dtr(ti);
 862
 863         return r;
 864 }
 865
 866 static struct target_type verity_target = {
 867         .name           = "verity",
 868         .version        = {1, 2, 0},
 869         .module         = THIS_MODULE,
 870         .ctr            = verity_ctr,
 871         .dtr            = verity_dtr,
 872         .map            = verity_map,
 873         .status         = verity_status,
 874         .ioctl          = verity_ioctl,
 875         .merge          = verity_merge,
 876         .iterate_devices = verity_iterate_devices,
 877         .io_hints       = verity_io_hints,
 878 };
 879
 880 static int __init dm_verity_init(void)
 881 {
 882         int r;
 883
 884         r = dm_register_target(&verity_target);
 885         if (r < 0)
 886                 DMERR("register failed %d", r);
 887
 888         return r;
 889 }
 890
 891 static void __exit dm_verity_exit(void)
 892 {
 893         dm_unregister_target(&verity_target);
 894 }
 895
 896 module_init(dm_verity_init);
 897 module_exit(dm_verity_exit);
 898
 899 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
 900 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
 901 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
 902 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
 903 MODULE_LICENSE("GPL");