Pileus Git - ~andy/linux/blob - 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
 334                 todo = 1 << v->data_dev_block_bits;
 335                 while (io->iter.bi_size) {
 336                         u8 *page;
 337                         struct bio_vec bv = bio_iter_iovec(bio, io->iter);
 338
 339                         page = kmap_atomic(bv.bv_page);
 340                         r = crypto_shash_update(desc, page + bv.bv_offset,
 341                                                 bv.bv_len);
 342                         kunmap_atomic(page);
 343
 344                         if (r < 0) {
 345                                 DMERR("crypto_shash_update failed: %d", r);
 346                                 return r;
 347                         }
 348
 349                         bio_advance_iter(bio, &io->iter, bv.bv_len);
 350                 }
 351
 352                 if (!v->version) {
 353                         r = crypto_shash_update(desc, v->salt, v->salt_size);
 354                         if (r < 0) {
 355                                 DMERR("crypto_shash_update failed: %d", r);
 356                                 return r;
 357                         }
 358                 }
 359
 360                 result = io_real_digest(v, io);
 361                 r = crypto_shash_final(desc, result);
 362                 if (r < 0) {
 363                         DMERR("crypto_shash_final failed: %d", r);
 364                         return r;
 365                 }
 366                 if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
 367                         DMERR_LIMIT("data block %llu is corrupted",
 368                                 (unsigned long long)(io->block + b));
 369                         v->hash_failed = 1;
 370                         return -EIO;
 371                 }
 372         }
 373
 374         return 0;
 375 }
 376
 377 /*
 378  * End one "io" structure with a given error.
 379  */
 380 static void verity_finish_io(struct dm_verity_io *io, int error)
 381 {
 382         struct dm_verity *v = io->v;
 383         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
 384
 385         bio->bi_end_io = io->orig_bi_end_io;
 386         bio->bi_private = io->orig_bi_private;
 387
 388         bio_endio_nodec(bio, error);
 389 }
 390
 391 static void verity_work(struct work_struct *w)
 392 {
 393         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 394
 395         verity_finish_io(io, verity_verify_io(io));
 396 }
 397
 398 static void verity_end_io(struct bio *bio, int error)
 399 {
 400         struct dm_verity_io *io = bio->bi_private;
 401
 402         if (error) {
 403                 verity_finish_io(io, error);
 404                 return;
 405         }
 406
 407         INIT_WORK(&io->work, verity_work);
 408         queue_work(io->v->verify_wq, &io->work);
 409 }
 410
 411 /*
 412  * Prefetch buffers for the specified io.
 413  * The root buffer is not prefetched, it is assumed that it will be cached
 414  * all the time.
 415  */
 416 static void verity_prefetch_io(struct work_struct *work)
 417 {
 418         struct dm_verity_prefetch_work *pw =
 419                 container_of(work, struct dm_verity_prefetch_work, work);
 420         struct dm_verity *v = pw->v;
 421         int i;
 422
 423         for (i = v->levels - 2; i >= 0; i--) {
 424                 sector_t hash_block_start;
 425                 sector_t hash_block_end;
 426                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 427                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 428                 if (!i) {
 429                         unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
 430
 431                         cluster >>= v->data_dev_block_bits;
 432                         if (unlikely(!cluster))
 433                                 goto no_prefetch_cluster;
 434
 435                         if (unlikely(cluster & (cluster - 1)))
 436                                 cluster = 1 << __fls(cluster);
 437
 438                         hash_block_start &= ~(sector_t)(cluster - 1);
 439                         hash_block_end |= cluster - 1;
 440                         if (unlikely(hash_block_end >= v->hash_blocks))
 441                                 hash_block_end = v->hash_blocks - 1;
 442                 }
 443 no_prefetch_cluster:
 444                 dm_bufio_prefetch(v->bufio, hash_block_start,
 445                                   hash_block_end - hash_block_start + 1);
 446         }
 447
 448         kfree(pw);
 449 }
 450
 451 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 452 {
 453         struct dm_verity_prefetch_work *pw;
 454
 455         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 456                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 457
 458         if (!pw)
 459                 return;
 460
 461         INIT_WORK(&pw->work, verity_prefetch_io);
 462         pw->v = v;
 463         pw->block = io->block;
 464         pw->n_blocks = io->n_blocks;
 465         queue_work(v->verify_wq, &pw->work);
 466 }
 467
 468 /*
 469  * Bio map function. It allocates dm_verity_io structure and bio vector and
 470  * fills them. Then it issues prefetches and the I/O.
 471  */
 472 static int verity_map(struct dm_target *ti, struct bio *bio)
 473 {
 474         struct dm_verity *v = ti->private;
 475         struct dm_verity_io *io;
 476
 477         bio->bi_bdev = v->data_dev->bdev;
 478         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 479
 480         if (((unsigned)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 481             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 482                 DMERR_LIMIT("unaligned io");
 483                 return -EIO;
 484         }
 485
 486         if (bio_end_sector(bio) >>
 487             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 488                 DMERR_LIMIT("io out of range");
 489                 return -EIO;
 490         }
 491
 492         if (bio_data_dir(bio) == WRITE)
 493                 return -EIO;
 494
 495         io = dm_per_bio_data(bio, ti->per_bio_data_size);
 496         io->v = v;
 497         io->orig_bi_end_io = bio->bi_end_io;
 498         io->orig_bi_private = bio->bi_private;
 499         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 500         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 501
 502         bio->bi_end_io = verity_end_io;
 503         bio->bi_private = io;
 504         io->iter = bio->bi_iter;
 505
 506         verity_submit_prefetch(v, io);
 507
 508         generic_make_request(bio);
 509
 510         return DM_MAPIO_SUBMITTED;
 511 }
 512
 513 /*
 514  * Status: V (valid) or C (corruption found)
 515  */
 516 static void verity_status(struct dm_target *ti, status_type_t type,
 517                           unsigned status_flags, char *result, unsigned maxlen)
 518 {
 519         struct dm_verity *v = ti->private;
 520         unsigned sz = 0;
 521         unsigned x;
 522
 523         switch (type) {
 524         case STATUSTYPE_INFO:
 525                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 526                 break;
 527         case STATUSTYPE_TABLE:
 528                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 529                         v->version,
 530                         v->data_dev->name,
 531                         v->hash_dev->name,
 532                         1 << v->data_dev_block_bits,
 533                         1 << v->hash_dev_block_bits,
 534                         (unsigned long long)v->data_blocks,
 535                         (unsigned long long)v->hash_start,
 536                         v->alg_name
 537                         );
 538                 for (x = 0; x < v->digest_size; x++)
 539                         DMEMIT("%02x", v->root_digest[x]);
 540                 DMEMIT(" ");
 541                 if (!v->salt_size)
 542                         DMEMIT("-");
 543                 else
 544                         for (x = 0; x < v->salt_size; x++)
 545                                 DMEMIT("%02x", v->salt[x]);
 546                 break;
 547         }
 548 }
 549
 550 static int verity_ioctl(struct dm_target *ti, unsigned cmd,
 551                         unsigned long arg)
 552 {
 553         struct dm_verity *v = ti->private;
 554         int r = 0;
 555
 556         if (v->data_start ||
 557             ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
 558                 r = scsi_verify_blk_ioctl(NULL, cmd);
 559
 560         return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
 561                                      cmd, arg);
 562 }
 563
 564 static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 565                         struct bio_vec *biovec, int max_size)
 566 {
 567         struct dm_verity *v = ti->private;
 568         struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
 569
 570         if (!q->merge_bvec_fn)
 571                 return max_size;
 572
 573         bvm->bi_bdev = v->data_dev->bdev;
 574         bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
 575
 576         return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 577 }
 578
 579 static int verity_iterate_devices(struct dm_target *ti,
 580                                   iterate_devices_callout_fn fn, void *data)
 581 {
 582         struct dm_verity *v = ti->private;
 583
 584         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 585 }
 586
 587 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 588 {
 589         struct dm_verity *v = ti->private;
 590
 591         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 592                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 593
 594         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 595                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 596
 597         blk_limits_io_min(limits, limits->logical_block_size);
 598 }
 599
 600 static void verity_dtr(struct dm_target *ti)
 601 {
 602         struct dm_verity *v = ti->private;
 603
 604         if (v->verify_wq)
 605                 destroy_workqueue(v->verify_wq);
 606
 607         if (v->vec_mempool)
 608                 mempool_destroy(v->vec_mempool);
 609
 610         if (v->bufio)
 611                 dm_bufio_client_destroy(v->bufio);
 612
 613         kfree(v->salt);
 614         kfree(v->root_digest);
 615
 616         if (v->tfm)
 617                 crypto_free_shash(v->tfm);
 618
 619         kfree(v->alg_name);
 620
 621         if (v->hash_dev)
 622                 dm_put_device(ti, v->hash_dev);
 623
 624         if (v->data_dev)
 625                 dm_put_device(ti, v->data_dev);
 626
 627         kfree(v);
 628 }
 629
 630 /*
 631  * Target parameters:
 632  *      <version>       The current format is version 1.
 633  *                      Vsn 0 is compatible with original Chromium OS releases.
 634  *      <data device>
 635  *      <hash device>
 636  *      <data block size>
 637  *      <hash block size>
 638  *      <the number of data blocks>
 639  *      <hash start block>
 640  *      <algorithm>
 641  *      <digest>
 642  *      <salt>          Hex string or "-" if no salt.
 643  */
 644 static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 645 {
 646         struct dm_verity *v;
 647         unsigned num;
 648         unsigned long long num_ll;
 649         int r;
 650         int i;
 651         sector_t hash_position;
 652         char dummy;
 653
 654         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
 655         if (!v) {
 656                 ti->error = "Cannot allocate verity structure";
 657                 return -ENOMEM;
 658         }
 659         ti->private = v;
 660         v->ti = ti;
 661
 662         if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
 663                 ti->error = "Device must be readonly";
 664                 r = -EINVAL;
 665                 goto bad;
 666         }
 667
 668         if (argc != 10) {
 669                 ti->error = "Invalid argument count: exactly 10 arguments required";
 670                 r = -EINVAL;
 671                 goto bad;
 672         }
 673
 674         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
 675             num > 1) {
 676                 ti->error = "Invalid version";
 677                 r = -EINVAL;
 678                 goto bad;
 679         }
 680         v->version = num;
 681
 682         r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
 683         if (r) {
 684                 ti->error = "Data device lookup failed";
 685                 goto bad;
 686         }
 687
 688         r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
 689         if (r) {
 690                 ti->error = "Data device lookup failed";
 691                 goto bad;
 692         }
 693
 694         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
 695             !num || (num & (num - 1)) ||
 696             num < bdev_logical_block_size(v->data_dev->bdev) ||
 697             num > PAGE_SIZE) {
 698                 ti->error = "Invalid data device block size";
 699                 r = -EINVAL;
 700                 goto bad;
 701         }
 702         v->data_dev_block_bits = __ffs(num);
 703
 704         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
 705             !num || (num & (num - 1)) ||
 706             num < bdev_logical_block_size(v->hash_dev->bdev) ||
 707             num > INT_MAX) {
 708                 ti->error = "Invalid hash device block size";
 709                 r = -EINVAL;
 710                 goto bad;
 711         }
 712         v->hash_dev_block_bits = __ffs(num);
 713
 714         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
 715             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
 716             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 717                 ti->error = "Invalid data blocks";
 718                 r = -EINVAL;
 719                 goto bad;
 720         }
 721         v->data_blocks = num_ll;
 722
 723         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
 724                 ti->error = "Data device is too small";
 725                 r = -EINVAL;
 726                 goto bad;
 727         }
 728
 729         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
 730             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
 731             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 732                 ti->error = "Invalid hash start";
 733                 r = -EINVAL;
 734                 goto bad;
 735         }
 736         v->hash_start = num_ll;
 737
 738         v->alg_name = kstrdup(argv[7], GFP_KERNEL);
 739         if (!v->alg_name) {
 740                 ti->error = "Cannot allocate algorithm name";
 741                 r = -ENOMEM;
 742                 goto bad;
 743         }
 744
 745         v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
 746         if (IS_ERR(v->tfm)) {
 747                 ti->error = "Cannot initialize hash function";
 748                 r = PTR_ERR(v->tfm);
 749                 v->tfm = NULL;
 750                 goto bad;
 751         }
 752         v->digest_size = crypto_shash_digestsize(v->tfm);
 753         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
 754                 ti->error = "Digest size too big";
 755                 r = -EINVAL;
 756                 goto bad;
 757         }
 758         v->shash_descsize =
 759                 sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
 760
 761         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
 762         if (!v->root_digest) {
 763                 ti->error = "Cannot allocate root digest";
 764                 r = -ENOMEM;
 765                 goto bad;
 766         }
 767         if (strlen(argv[8]) != v->digest_size * 2 ||
 768             hex2bin(v->root_digest, argv[8], v->digest_size)) {
 769                 ti->error = "Invalid root digest";
 770                 r = -EINVAL;
 771                 goto bad;
 772         }
 773
 774         if (strcmp(argv[9], "-")) {
 775                 v->salt_size = strlen(argv[9]) / 2;
 776                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
 777                 if (!v->salt) {
 778                         ti->error = "Cannot allocate salt";
 779                         r = -ENOMEM;
 780                         goto bad;
 781                 }
 782                 if (strlen(argv[9]) != v->salt_size * 2 ||
 783                     hex2bin(v->salt, argv[9], v->salt_size)) {
 784                         ti->error = "Invalid salt";
 785                         r = -EINVAL;
 786                         goto bad;
 787                 }
 788         }
 789
 790         v->hash_per_block_bits =
 791                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
 792
 793         v->levels = 0;
 794         if (v->data_blocks)
 795                 while (v->hash_per_block_bits * v->levels < 64 &&
 796                        (unsigned long long)(v->data_blocks - 1) >>
 797                        (v->hash_per_block_bits * v->levels))
 798                         v->levels++;
 799
 800         if (v->levels > DM_VERITY_MAX_LEVELS) {
 801                 ti->error = "Too many tree levels";
 802                 r = -E2BIG;
 803                 goto bad;
 804         }
 805
 806         hash_position = v->hash_start;
 807         for (i = v->levels - 1; i >= 0; i--) {
 808                 sector_t s;
 809                 v->hash_level_block[i] = hash_position;
 810                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
 811                                         >> ((i + 1) * v->hash_per_block_bits);
 812                 if (hash_position + s < hash_position) {
 813                         ti->error = "Hash device offset overflow";
 814                         r = -E2BIG;
 815                         goto bad;
 816                 }
 817                 hash_position += s;
 818         }
 819         v->hash_blocks = hash_position;
 820
 821         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
 822                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
 823                 dm_bufio_alloc_callback, NULL);
 824         if (IS_ERR(v->bufio)) {
 825                 ti->error = "Cannot initialize dm-bufio";
 826                 r = PTR_ERR(v->bufio);
 827                 v->bufio = NULL;
 828                 goto bad;
 829         }
 830
 831         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
 832                 ti->error = "Hash device is too small";
 833                 r = -E2BIG;
 834                 goto bad;
 835         }
 836
 837         ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
 838
 839         v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
 840                                         BIO_MAX_PAGES * sizeof(struct bio_vec));
 841         if (!v->vec_mempool) {
 842                 ti->error = "Cannot allocate vector mempool";
 843                 r = -ENOMEM;
 844                 goto bad;
 845         }
 846
 847         /* WQ_UNBOUND greatly improves performance when running on ramdisk */
 848         v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
 849         if (!v->verify_wq) {
 850                 ti->error = "Cannot allocate workqueue";
 851                 r = -ENOMEM;
 852                 goto bad;
 853         }
 854
 855         return 0;
 856
 857 bad:
 858         verity_dtr(ti);
 859
 860         return r;
 861 }
 862
 863 static struct target_type verity_target = {
 864         .name           = "verity",
 865         .version        = {1, 2, 0},
 866         .module         = THIS_MODULE,
 867         .ctr            = verity_ctr,
 868         .dtr            = verity_dtr,
 869         .map            = verity_map,
 870         .status         = verity_status,
 871         .ioctl          = verity_ioctl,
 872         .merge          = verity_merge,
 873         .iterate_devices = verity_iterate_devices,
 874         .io_hints       = verity_io_hints,
 875 };
 876
 877 static int __init dm_verity_init(void)
 878 {
 879         int r;
 880
 881         r = dm_register_target(&verity_target);
 882         if (r < 0)
 883                 DMERR("register failed %d", r);
 884
 885         return r;
 886 }
 887
 888 static void __exit dm_verity_exit(void)
 889 {
 890         dm_unregister_target(&verity_target);
 891 }
 892
 893 module_init(dm_verity_init);
 894 module_exit(dm_verity_exit);
 895
 896 MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
 897 MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
 898 MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
 899 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
 900 MODULE_LICENSE("GPL");