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