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