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 *io_mempool;  /* mempool of struct dm_verity_io */
  59         mempool_t *vec_mempool; /* mempool of bio vector */
  60
  61         struct workqueue_struct *verify_wq;
  62
  63         /* starting blocks for each tree level. 0 is the lowest level. */
  64         sector_t hash_level_block[DM_VERITY_MAX_LEVELS];
  65 };
  66
  67 struct dm_verity_io {
  68         struct dm_verity *v;
  69         struct bio *bio;
  70
  71         /* original values of bio->bi_end_io and bio->bi_private */
  72         bio_end_io_t *orig_bi_end_io;
  73         void *orig_bi_private;
  74
  75         sector_t block;
  76         unsigned n_blocks;
  77
  78         /* saved bio vector */
  79         struct bio_vec *io_vec;
  80         unsigned io_vec_size;
  81
  82         struct work_struct work;
  83
  84         /* A space for short vectors; longer vectors are allocated separately. */
  85         struct bio_vec io_vec_inline[DM_VERITY_IO_VEC_INLINE];
  86
  87         /*
  88          * Three variably-size fields follow this struct:
  89          *
  90          * u8 hash_desc[v->shash_descsize];
  91          * u8 real_digest[v->digest_size];
  92          * u8 want_digest[v->digest_size];
  93          *
  94          * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().
  95          */
  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         unsigned b;
 283         int i;
 284         unsigned vector = 0, offset = 0;
 285
 286         for (b = 0; b < io->n_blocks; b++) {
 287                 struct shash_desc *desc;
 288                 u8 *result;
 289                 int r;
 290                 unsigned todo;
 291
 292                 if (likely(v->levels)) {
 293                         /*
 294                          * First, we try to get the requested hash for
 295                          * the current block. If the hash block itself is
 296                          * verified, zero is returned. If it isn't, this
 297                          * function returns 0 and we fall back to whole
 298                          * chain verification.
 299                          */
 300                         int r = verity_verify_level(io, io->block + b, 0, true);
 301                         if (likely(!r))
 302                                 goto test_block_hash;
 303                         if (r < 0)
 304                                 return r;
 305                 }
 306
 307                 memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
 308
 309                 for (i = v->levels - 1; i >= 0; i--) {
 310                         int r = verity_verify_level(io, io->block + b, i, false);
 311                         if (unlikely(r))
 312                                 return r;
 313                 }
 314
 315 test_block_hash:
 316                 desc = io_hash_desc(v, io);
 317                 desc->tfm = v->tfm;
 318                 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 319                 r = crypto_shash_init(desc);
 320                 if (r < 0) {
 321                         DMERR("crypto_shash_init failed: %d", r);
 322                         return r;
 323                 }
 324
 325                 if (likely(v->version >= 1)) {
 326                         r = crypto_shash_update(desc, v->salt, v->salt_size);
 327                         if (r < 0) {
 328                                 DMERR("crypto_shash_update failed: %d", r);
 329                                 return r;
 330                         }
 331                 }
 332
 333                 todo = 1 << v->data_dev_block_bits;
 334                 do {
 335                         struct bio_vec *bv;
 336                         u8 *page;
 337                         unsigned len;
 338
 339                         BUG_ON(vector >= io->io_vec_size);
 340                         bv = &io->io_vec[vector];
 341                         page = kmap_atomic(bv->bv_page);
 342                         len = bv->bv_len - offset;
 343                         if (likely(len >= todo))
 344                                 len = todo;
 345                         r = crypto_shash_update(desc,
 346                                         page + bv->bv_offset + offset, len);
 347                         kunmap_atomic(page);
 348                         if (r < 0) {
 349                                 DMERR("crypto_shash_update failed: %d", r);
 350                                 return r;
 351                         }
 352                         offset += len;
 353                         if (likely(offset == bv->bv_len)) {
 354                                 offset = 0;
 355                                 vector++;
 356                         }
 357                         todo -= len;
 358                 } while (todo);
 359
 360                 if (!v->version) {
 361                         r = crypto_shash_update(desc, v->salt, v->salt_size);
 362                         if (r < 0) {
 363                                 DMERR("crypto_shash_update failed: %d", r);
 364                                 return r;
 365                         }
 366                 }
 367
 368                 result = io_real_digest(v, io);
 369                 r = crypto_shash_final(desc, result);
 370                 if (r < 0) {
 371                         DMERR("crypto_shash_final failed: %d", r);
 372                         return r;
 373                 }
 374                 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
 375                         DMERR_LIMIT("data block %llu is corrupted",
 376                                 (unsigned long long)(io->block + b));
 377                         v->hash_failed = 1;
 378                         return -EIO;
 379                 }
 380         }
 381         BUG_ON(vector != io->io_vec_size);
 382         BUG_ON(offset);
 383
 384         return 0;
 385 }
 386
 387 /*
 388  * End one "io" structure with a given error.
 389  */
 390 static void verity_finish_io(struct dm_verity_io *io, int error)
 391 {
 392         struct bio *bio = io->bio;
 393         struct dm_verity *v = io->v;
 394
 395         bio->bi_end_io = io->orig_bi_end_io;
 396         bio->bi_private = io->orig_bi_private;
 397
 398         if (io->io_vec != io->io_vec_inline)
 399                 mempool_free(io->io_vec, v->vec_mempool);
 400
 401         mempool_free(io, v->io_mempool);
 402
 403         bio_endio(bio, error);
 404 }
 405
 406 static void verity_work(struct work_struct *w)
 407 {
 408         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 409
 410         verity_finish_io(io, verity_verify_io(io));
 411 }
 412
 413 static void verity_end_io(struct bio *bio, int error)
 414 {
 415         struct dm_verity_io *io = bio->bi_private;
 416
 417         if (error) {
 418                 verity_finish_io(io, error);
 419                 return;
 420         }
 421
 422         INIT_WORK(&io->work, verity_work);
 423         queue_work(io->v->verify_wq, &io->work);
 424 }
 425
 426 /*
 427  * Prefetch buffers for the specified io.
 428  * The root buffer is not prefetched, it is assumed that it will be cached
 429  * all the time.
 430  */
 431 static void verity_prefetch_io(struct dm_verity *v, struct dm_verity_io *io)
 432 {
 433         int i;
 434
 435         for (i = v->levels - 2; i >= 0; i--) {
 436                 sector_t hash_block_start;
 437                 sector_t hash_block_end;
 438                 verity_hash_at_level(v, io->block, i, &hash_block_start, NULL);
 439                 verity_hash_at_level(v, io->block + io->n_blocks - 1, i, &hash_block_end, NULL);
 440                 if (!i) {
 441                         unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
 442
 443                         cluster >>= v->data_dev_block_bits;
 444                         if (unlikely(!cluster))
 445                                 goto no_prefetch_cluster;
 446
 447                         if (unlikely(cluster & (cluster - 1)))
 448                                 cluster = 1 << (fls(cluster) - 1);
 449
 450                         hash_block_start &= ~(sector_t)(cluster - 1);
 451                         hash_block_end |= cluster - 1;
 452                         if (unlikely(hash_block_end >= v->hash_blocks))
 453                                 hash_block_end = v->hash_blocks - 1;
 454                 }
 455 no_prefetch_cluster:
 456                 dm_bufio_prefetch(v->bufio, hash_block_start,
 457                                   hash_block_end - hash_block_start + 1);
 458         }
 459 }
 460
 461 /*
 462  * Bio map function. It allocates dm_verity_io structure and bio vector and
 463  * fills them. Then it issues prefetches and the I/O.
 464  */
 465 static int verity_map(struct dm_target *ti, struct bio *bio,
 466                       union map_info *map_context)
 467 {
 468         struct dm_verity *v = ti->private;
 469         struct dm_verity_io *io;
 470
 471         bio->bi_bdev = v->data_dev->bdev;
 472         bio->bi_sector = verity_map_sector(v, bio->bi_sector);
 473
 474         if (((unsigned)bio->bi_sector | bio_sectors(bio)) &
 475             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 476                 DMERR_LIMIT("unaligned io");
 477                 return -EIO;
 478         }
 479
 480         if ((bio->bi_sector + bio_sectors(bio)) >>
 481             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 482                 DMERR_LIMIT("io out of range");
 483                 return -EIO;
 484         }
 485
 486         if (bio_data_dir(bio) == WRITE)
 487                 return -EIO;
 488
 489         io = mempool_alloc(v->io_mempool, GFP_NOIO);
 490         io->v = v;
 491         io->bio = bio;
 492         io->orig_bi_end_io = bio->bi_end_io;
 493         io->orig_bi_private = bio->bi_private;
 494         io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 495         io->n_blocks = bio->bi_size >> v->data_dev_block_bits;
 496
 497         bio->bi_end_io = verity_end_io;
 498         bio->bi_private = io;
 499         io->io_vec_size = bio->bi_vcnt - bio->bi_idx;
 500         if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE)
 501                 io->io_vec = io->io_vec_inline;
 502         else
 503                 io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO);
 504         memcpy(io->io_vec, bio_iovec(bio),
 505                io->io_vec_size * sizeof(struct bio_vec));
 506
 507         verity_prefetch_io(v, io);
 508
 509         generic_make_request(bio);
 510
 511         return DM_MAPIO_SUBMITTED;
 512 }
 513
 514 /*
 515  * Status: V (valid) or C (corruption found)
 516  */
 517 static int verity_status(struct dm_target *ti, status_type_t type,
 518                          unsigned status_flags, char *result, unsigned maxlen)
 519 {
 520         struct dm_verity *v = ti->private;
 521         unsigned sz = 0;
 522         unsigned x;
 523
 524         switch (type) {
 525         case STATUSTYPE_INFO:
 526                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 527                 break;
 528         case STATUSTYPE_TABLE:
 529                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 530                         v->version,
 531                         v->data_dev->name,
 532                         v->hash_dev->name,
 533                         1 << v->data_dev_block_bits,
 534                         1 << v->hash_dev_block_bits,
 535                         (unsigned long long)v->data_blocks,
 536                         (unsigned long long)v->hash_start,
 537                         v->alg_name
 538                         );
 539                 for (x = 0; x < v->digest_size; x++)
 540                         DMEMIT("%02x", v->root_digest[x]);
 541                 DMEMIT(" ");
 542                 if (!v->salt_size)
 543                         DMEMIT("-");
 544                 else
 545                         for (x = 0; x < v->salt_size; x++)
 546                                 DMEMIT("%02x", v->salt[x]);
 547                 break;
 548         }
 549
 550         return 0;
 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->io_mempool)
 614                 mempool_destroy(v->io_mempool);
 615
 616         if (v->bufio)
 617                 dm_bufio_client_destroy(v->bufio);
 618
 619         kfree(v->salt);
 620         kfree(v->root_digest);
 621
 622         if (v->tfm)
 623                 crypto_free_shash(v->tfm);
 624
 625         kfree(v->alg_name);
 626
 627         if (v->hash_dev)
 628                 dm_put_device(ti, v->hash_dev);
 629
 630         if (v->data_dev)
 631                 dm_put_device(ti, v->data_dev);
 632
 633         kfree(v);
 634 }
 635
 636 /*
 637  * Target parameters:
 638  *      <version>       The current format is version 1.
 639  *                      Vsn 0 is compatible with original Chromium OS releases.
 640  *      <data device>
 641  *      <hash device>
 642  *      <data block size>
 643  *      <hash block size>
 644  *      <the number of data blocks>
 645  *      <hash start block>
 646  *      <algorithm>
 647  *      <digest>
 648  *      <salt>          Hex string or "-" if no salt.
 649  */
 650 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 651 {
 652         struct dm_verity *v;
 653         unsigned num;
 654         unsigned long long num_ll;
 655         int r;
 656         int i;
 657         sector_t hash_position;
 658         char dummy;
 659
 660         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
 661         if (!v) {
 662                 ti->error = "Cannot allocate verity structure";
 663                 return -ENOMEM;
 664         }
 665         ti->private = v;
 666         v->ti = ti;
 667
 668         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
 669                 ti->error = "Device must be readonly";
 670                 r = -EINVAL;
 671                 goto bad;
 672         }
 673
 674         if (argc != 10) {
 675                 ti->error = "Invalid argument count: exactly 10 arguments required";
 676                 r = -EINVAL;
 677                 goto bad;
 678         }
 679
 680         if (sscanf(argv[0], "%d%c", &num, &dummy) != 1 ||
 681             num < 0 || num > 1) {
 682                 ti->error = "Invalid version";
 683                 r = -EINVAL;
 684                 goto bad;
 685         }
 686         v->version = num;
 687
 688         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
 689         if (r) {
 690                 ti->error = "Data device lookup failed";
 691                 goto bad;
 692         }
 693
 694         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
 695         if (r) {
 696                 ti->error = "Data device lookup failed";
 697                 goto bad;
 698         }
 699
 700         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
 701             !num || (num & (num - 1)) ||
 702             num < bdev_logical_block_size(v->data_dev->bdev) ||
 703             num > PAGE_SIZE) {
 704                 ti->error = "Invalid data device block size";
 705                 r = -EINVAL;
 706                 goto bad;
 707         }
 708         v->data_dev_block_bits = ffs(num) - 1;
 709
 710         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
 711             !num || (num & (num - 1)) ||
 712             num < bdev_logical_block_size(v->hash_dev->bdev) ||
 713             num > INT_MAX) {
 714                 ti->error = "Invalid hash device block size";
 715                 r = -EINVAL;
 716                 goto bad;
 717         }
 718         v->hash_dev_block_bits = ffs(num) - 1;
 719
 720         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
 721             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
 722             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 723                 ti->error = "Invalid data blocks";
 724                 r = -EINVAL;
 725                 goto bad;
 726         }
 727         v->data_blocks = num_ll;
 728
 729         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
 730                 ti->error = "Data device is too small";
 731                 r = -EINVAL;
 732                 goto bad;
 733         }
 734
 735         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
 736             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
 737             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 738                 ti->error = "Invalid hash start";
 739                 r = -EINVAL;
 740                 goto bad;
 741         }
 742         v->hash_start = num_ll;
 743
 744         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
 745         if (!v->alg_name) {
 746                 ti->error = "Cannot allocate algorithm name";
 747                 r = -ENOMEM;
 748                 goto bad;
 749         }
 750
 751         v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
 752         if (IS_ERR(v->tfm)) {
 753                 ti->error = "Cannot initialize hash function";
 754                 r = PTR_ERR(v->tfm);
 755                 v->tfm = NULL;
 756                 goto bad;
 757         }
 758         v->digest_size = crypto_shash_digestsize(v->tfm);
 759         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
 760                 ti->error = "Digest size too big";
 761                 r = -EINVAL;
 762                 goto bad;
 763         }
 764         v->shash_descsize =
 765                 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
 766
 767         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
 768         if (!v->root_digest) {
 769                 ti->error = "Cannot allocate root digest";
 770                 r = -ENOMEM;
 771                 goto bad;
 772         }
 773         if (strlen(argv[8]) != v->digest_size * 2 ||
 774             hex2bin(v->root_digest, argv[8], v->digest_size)) {
 775                 ti->error = "Invalid root digest";
 776                 r = -EINVAL;
 777                 goto bad;
 778         }
 779
 780         if (strcmp(argv[9], "-")) {
 781                 v->salt_size = strlen(argv[9]) / 2;
 782                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
 783                 if (!v->salt) {
 784                         ti->error = "Cannot allocate salt";
 785                         r = -ENOMEM;
 786                         goto bad;
 787                 }
 788                 if (strlen(argv[9]) != v->salt_size * 2 ||
 789                     hex2bin(v->salt, argv[9], v->salt_size)) {
 790                         ti->error = "Invalid salt";
 791                         r = -EINVAL;
 792                         goto bad;
 793                 }
 794         }
 795
 796         v->hash_per_block_bits =
 797                 fls((1 << v->hash_dev_block_bits) / v->digest_size) - 1;
 798
 799         v->levels = 0;
 800         if (v->data_blocks)
 801                 while (v->hash_per_block_bits * v->levels < 64 &&
 802                        (unsigned long long)(v->data_blocks - 1) >>
 803                        (v->hash_per_block_bits * v->levels))
 804                         v->levels++;
 805
 806         if (v->levels > DM_VERITY_MAX_LEVELS) {
 807                 ti->error = "Too many tree levels";
 808                 r = -E2BIG;
 809                 goto bad;
 810         }
 811
 812         hash_position = v->hash_start;
 813         for (i = v->levels - 1; i >= 0; i--) {
 814                 sector_t s;
 815                 v->hash_level_block[i] = hash_position;
 816                 s = verity_position_at_level(v, v->data_blocks, i);
 817                 s = (s >> v->hash_per_block_bits) +
 818                     !!(s & ((1 << v->hash_per_block_bits) - 1));
 819                 if (hash_position + s < hash_position) {
 820                         ti->error = "Hash device offset overflow";
 821                         r = -E2BIG;
 822                         goto bad;
 823                 }
 824                 hash_position += s;
 825         }
 826         v->hash_blocks = hash_position;
 827
 828         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
 829                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
 830                 dm_bufio_alloc_callback, NULL);
 831         if (IS_ERR(v->bufio)) {
 832                 ti->error = "Cannot initialize dm-bufio";
 833                 r = PTR_ERR(v->bufio);
 834                 v->bufio = NULL;
 835                 goto bad;
 836         }
 837
 838         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
 839                 ti->error = "Hash device is too small";
 840                 r = -E2BIG;
 841                 goto bad;
 842         }
 843
 844         v->io_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
 845           sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2);
 846         if (!v->io_mempool) {
 847                 ti->error = "Cannot allocate io mempool";
 848                 r = -ENOMEM;
 849                 goto bad;
 850         }
 851
 852         v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
 853                                         BIO_MAX_PAGES * sizeof(struct bio_vec));
 854         if (!v->vec_mempool) {
 855                 ti->error = "Cannot allocate vector mempool";
 856                 r = -ENOMEM;
 857                 goto bad;
 858         }
 859
 860         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
 861         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
 862         if (!v->verify_wq) {
 863                 ti->error = "Cannot allocate workqueue";
 864                 r = -ENOMEM;
 865                 goto bad;
 866         }
 867
 868         return 0;
 869
 870 bad:
 871         verity_dtr(ti);
 872
 873         return r;
 874 }
 875
 876 static struct target_type verity_target = {
 877         .name           = "verity",
 878         .version        = {1, 0, 0},
 879         .module         = THIS_MODULE,
 880         .ctr            = verity_ctr,
 881         .dtr            = verity_dtr,
 882         .map            = verity_map,
 883         .status         = verity_status,
 884         .ioctl          = verity_ioctl,
 885         .merge          = verity_merge,
 886         .iterate_devices = verity_iterate_devices,
 887         .io_hints       = verity_io_hints,
 888 };
 889
 890 static int __init dm_verity_init(void)
 891 {
 892         int r;
 893
 894         r = dm_register_target(&verity_target);
 895         if (r < 0)
 896                 DMERR("register failed %d", r);
 897
 898         return r;
 899 }
 900
 901 static void __exit dm_verity_exit(void)
 902 {
 903         dm_unregister_target(&verity_target);
 904 }
 905
 906 module_init(dm_verity_init);
 907 module_exit(dm_verity_exit);
 908
 909 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
 910 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
 911 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
 912 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
 913 MODULE_LICENSE("GPL");