linux/drivers/md/dm-verity.c
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   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
  31static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  32
  33module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);
  34
  35struct 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
  67struct 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
  98static 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
 103static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
 104{
 105        return (u8 *)(io + 1) + v->shash_descsize;
 106}
 107
 108static 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 */
 125struct buffer_aux {
 126        int hash_verified;
 127};
 128
 129/*
 130 * Initialize struct buffer_aux for a freshly created buffer.
 131 */
 132static 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 */
 142static 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 */
 153static 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
 159static 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 */
 188static 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
 270release_ret_r:
 271        dm_bufio_release(buf);
 272
 273        return r;
 274}
 275
 276/*
 277 * Verify one "dm_verity_io" structure.
 278 */
 279static 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
 315test_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 */
 390static 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
 406static 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
 413static 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 */
 431static 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 = *(volatile unsigned *)&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                }
 455no_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 */
 465static 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 */
 517static 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
 553static 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
 567static 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
 582static 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
 590static 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
 603static 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 */
 650static 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
 870bad:
 871        verity_dtr(ti);
 872
 873        return r;
 874}
 875
 876static 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
 890static 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
 901static void __exit dm_verity_exit(void)
 902{
 903        dm_unregister_target(&verity_target);
 904}
 905
 906module_init(dm_verity_init);
 907module_exit(dm_verity_exit);
 908
 909MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
 910MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
 911MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
 912MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
 913MODULE_LICENSE("GPL");
 914
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