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
  96struct dm_verity_prefetch_work {
  97        struct work_struct work;
  98        struct dm_verity *v;
  99        sector_t block;
 100        unsigned n_blocks;
 101};
 102
 103static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)
 104{
 105        return (struct shash_desc *)(io + 1);
 106}
 107
 108static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)
 109{
 110        return (u8 *)(io + 1) + v->shash_descsize;
 111}
 112
 113static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)
 114{
 115        return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;
 116}
 117
 118/*
 119 * Auxiliary structure appended to each dm-bufio buffer. If the value
 120 * hash_verified is nonzero, hash of the block has been verified.
 121 *
 122 * The variable hash_verified is set to 0 when allocating the buffer, then
 123 * it can be changed to 1 and it is never reset to 0 again.
 124 *
 125 * There is no lock around this value, a race condition can at worst cause
 126 * that multiple processes verify the hash of the same buffer simultaneously
 127 * and write 1 to hash_verified simultaneously.
 128 * This condition is harmless, so we don't need locking.
 129 */
 130struct buffer_aux {
 131        int hash_verified;
 132};
 133
 134/*
 135 * Initialize struct buffer_aux for a freshly created buffer.
 136 */
 137static void dm_bufio_alloc_callback(struct dm_buffer *buf)
 138{
 139        struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
 140
 141        aux->hash_verified = 0;
 142}
 143
 144/*
 145 * Translate input sector number to the sector number on the target device.
 146 */
 147static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
 148{
 149        return v->data_start + dm_target_offset(v->ti, bi_sector);
 150}
 151
 152/*
 153 * Return hash position of a specified block at a specified tree level
 154 * (0 is the lowest level).
 155 * The lowest "hash_per_block_bits"-bits of the result denote hash position
 156 * inside a hash block. The remaining bits denote location of the hash block.
 157 */
 158static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
 159                                         int level)
 160{
 161        return block >> (level * v->hash_per_block_bits);
 162}
 163
 164static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 165                                 sector_t *hash_block, unsigned *offset)
 166{
 167        sector_t position = verity_position_at_level(v, block, level);
 168        unsigned idx;
 169
 170        *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 171
 172        if (!offset)
 173                return;
 174
 175        idx = position & ((1 << v->hash_per_block_bits) - 1);
 176        if (!v->version)
 177                *offset = idx * v->digest_size;
 178        else
 179                *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 180}
 181
 182/*
 183 * Verify hash of a metadata block pertaining to the specified data block
 184 * ("block" argument) at a specified level ("level" argument).
 185 *
 186 * On successful return, io_want_digest(v, io) contains the hash value for
 187 * a lower tree level or for the data block (if we're at the lowest leve).
 188 *
 189 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 190 * If "skip_unverified" is false, unverified buffer is hashed and verified
 191 * against current value of io_want_digest(v, io).
 192 */
 193static int verity_verify_level(struct dm_verity_io *io, sector_t block,
 194                               int level, bool skip_unverified)
 195{
 196        struct dm_verity *v = io->v;
 197        struct dm_buffer *buf;
 198        struct buffer_aux *aux;
 199        u8 *data;
 200        int r;
 201        sector_t hash_block;
 202        unsigned offset;
 203
 204        verity_hash_at_level(v, block, level, &hash_block, &offset);
 205
 206        data = dm_bufio_read(v->bufio, hash_block, &buf);
 207        if (unlikely(IS_ERR(data)))
 208                return PTR_ERR(data);
 209
 210        aux = dm_bufio_get_aux_data(buf);
 211
 212        if (!aux->hash_verified) {
 213                struct shash_desc *desc;
 214                u8 *result;
 215
 216                if (skip_unverified) {
 217                        r = 1;
 218                        goto release_ret_r;
 219                }
 220
 221                desc = io_hash_desc(v, io);
 222                desc->tfm = v->tfm;
 223                desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 224                r = crypto_shash_init(desc);
 225                if (r < 0) {
 226                        DMERR("crypto_shash_init failed: %d", r);
 227                        goto release_ret_r;
 228                }
 229
 230                if (likely(v->version >= 1)) {
 231                        r = crypto_shash_update(desc, v->salt, v->salt_size);
 232                        if (r < 0) {
 233                                DMERR("crypto_shash_update failed: %d", r);
 234                                goto release_ret_r;
 235                        }
 236                }
 237
 238                r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
 239                if (r < 0) {
 240                        DMERR("crypto_shash_update failed: %d", r);
 241                        goto release_ret_r;
 242                }
 243
 244                if (!v->version) {
 245                        r = crypto_shash_update(desc, v->salt, v->salt_size);
 246                        if (r < 0) {
 247                                DMERR("crypto_shash_update failed: %d", r);
 248                                goto release_ret_r;
 249                        }
 250                }
 251
 252                result = io_real_digest(v, io);
 253                r = crypto_shash_final(desc, result);
 254                if (r < 0) {
 255                        DMERR("crypto_shash_final failed: %d", r);
 256                        goto release_ret_r;
 257                }
 258                if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
 259                        DMERR_LIMIT("metadata block %llu is corrupted",
 260                                (unsigned long long)hash_block);
 261                        v->hash_failed = 1;
 262                        r = -EIO;
 263                        goto release_ret_r;
 264                } else
 265                        aux->hash_verified = 1;
 266        }
 267
 268        data += offset;
 269
 270        memcpy(io_want_digest(v, io), data, v->digest_size);
 271
 272        dm_bufio_release(buf);
 273        return 0;
 274
 275release_ret_r:
 276        dm_bufio_release(buf);
 277
 278        return r;
 279}
 280
 281/*
 282 * Verify one "dm_verity_io" structure.
 283 */
 284static int verity_verify_io(struct dm_verity_io *io)
 285{
 286        struct dm_verity *v = io->v;
 287        unsigned b;
 288        int i;
 289        unsigned vector = 0, offset = 0;
 290
 291        for (b = 0; b < io->n_blocks; b++) {
 292                struct shash_desc *desc;
 293                u8 *result;
 294                int r;
 295                unsigned todo;
 296
 297                if (likely(v->levels)) {
 298                        /*
 299                         * First, we try to get the requested hash for
 300                         * the current block. If the hash block itself is
 301                         * verified, zero is returned. If it isn't, this
 302                         * function returns 0 and we fall back to whole
 303                         * chain verification.
 304                         */
 305                        int r = verity_verify_level(io, io->block + b, 0, true);
 306                        if (likely(!r))
 307                                goto test_block_hash;
 308                        if (r < 0)
 309                                return r;
 310                }
 311
 312                memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
 313
 314                for (i = v->levels - 1; i >= 0; i--) {
 315                        int r = verity_verify_level(io, io->block + b, i, false);
 316                        if (unlikely(r))
 317                                return r;
 318                }
 319
 320test_block_hash:
 321                desc = io_hash_desc(v, io);
 322                desc->tfm = v->tfm;
 323                desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
 324                r = crypto_shash_init(desc);
 325                if (r < 0) {
 326                        DMERR("crypto_shash_init failed: %d", r);
 327                        return r;
 328                }
 329
 330                if (likely(v->version >= 1)) {
 331                        r = crypto_shash_update(desc, v->salt, v->salt_size);
 332                        if (r < 0) {
 333                                DMERR("crypto_shash_update failed: %d", r);
 334                                return r;
 335                        }
 336                }
 337
 338                todo = 1 << v->data_dev_block_bits;
 339                do {
 340                        struct bio_vec *bv;
 341                        u8 *page;
 342                        unsigned len;
 343
 344                        BUG_ON(vector >= io->io_vec_size);
 345                        bv = &io->io_vec[vector];
 346                        page = kmap_atomic(bv->bv_page);
 347                        len = bv->bv_len - offset;
 348                        if (likely(len >= todo))
 349                                len = todo;
 350                        r = crypto_shash_update(desc,
 351                                        page + bv->bv_offset + offset, len);
 352                        kunmap_atomic(page);
 353                        if (r < 0) {
 354                                DMERR("crypto_shash_update failed: %d", r);
 355                                return r;
 356                        }
 357                        offset += len;
 358                        if (likely(offset == bv->bv_len)) {
 359                                offset = 0;
 360                                vector++;
 361                        }
 362                        todo -= len;
 363                } while (todo);
 364
 365                if (!v->version) {
 366                        r = crypto_shash_update(desc, v->salt, v->salt_size);
 367                        if (r < 0) {
 368                                DMERR("crypto_shash_update failed: %d", r);
 369                                return r;
 370                        }
 371                }
 372
 373                result = io_real_digest(v, io);
 374                r = crypto_shash_final(desc, result);
 375                if (r < 0) {
 376                        DMERR("crypto_shash_final failed: %d", r);
 377                        return r;
 378                }
 379                if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
 380                        DMERR_LIMIT("data block %llu is corrupted",
 381                                (unsigned long long)(io->block + b));
 382                        v->hash_failed = 1;
 383                        return -EIO;
 384                }
 385        }
 386        BUG_ON(vector != io->io_vec_size);
 387        BUG_ON(offset);
 388
 389        return 0;
 390}
 391
 392/*
 393 * End one "io" structure with a given error.
 394 */
 395static void verity_finish_io(struct dm_verity_io *io, int error)
 396{
 397        struct dm_verity *v = io->v;
 398        struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_bio_data_size);
 399
 400        bio->bi_end_io = io->orig_bi_end_io;
 401        bio->bi_private = io->orig_bi_private;
 402
 403        if (io->io_vec != io->io_vec_inline)
 404                mempool_free(io->io_vec, v->vec_mempool);
 405
 406        bio_endio(bio, error);
 407}
 408
 409static void verity_work(struct work_struct *w)
 410{
 411        struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 412
 413        verity_finish_io(io, verity_verify_io(io));
 414}
 415
 416static void verity_end_io(struct bio *bio, int error)
 417{
 418        struct dm_verity_io *io = bio->bi_private;
 419
 420        if (error) {
 421                verity_finish_io(io, error);
 422                return;
 423        }
 424
 425        INIT_WORK(&io->work, verity_work);
 426        queue_work(io->v->verify_wq, &io->work);
 427}
 428
 429/*
 430 * Prefetch buffers for the specified io.
 431 * The root buffer is not prefetched, it is assumed that it will be cached
 432 * all the time.
 433 */
 434static void verity_prefetch_io(struct work_struct *work)
 435{
 436        struct dm_verity_prefetch_work *pw =
 437                container_of(work, struct dm_verity_prefetch_work, work);
 438        struct dm_verity *v = pw->v;
 439        int i;
 440
 441        for (i = v->levels - 2; i >= 0; i--) {
 442                sector_t hash_block_start;
 443                sector_t hash_block_end;
 444                verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 445                verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 446                if (!i) {
 447                        unsigned cluster = ACCESS_ONCE(dm_verity_prefetch_cluster);
 448
 449                        cluster >>= v->data_dev_block_bits;
 450                        if (unlikely(!cluster))
 451                                goto no_prefetch_cluster;
 452
 453                        if (unlikely(cluster & (cluster - 1)))
 454                                cluster = 1 << (fls(cluster) - 1);
 455
 456                        hash_block_start &= ~(sector_t)(cluster - 1);
 457                        hash_block_end |= cluster - 1;
 458                        if (unlikely(hash_block_end >= v->hash_blocks))
 459                                hash_block_end = v->hash_blocks - 1;
 460                }
 461no_prefetch_cluster:
 462                dm_bufio_prefetch(v->bufio, hash_block_start,
 463                                  hash_block_end - hash_block_start + 1);
 464        }
 465
 466        kfree(pw);
 467}
 468
 469static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
 470{
 471        struct dm_verity_prefetch_work *pw;
 472
 473        pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 474                GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 475
 476        if (!pw)
 477                return;
 478
 479        INIT_WORK(&pw->work, verity_prefetch_io);
 480        pw->v = v;
 481        pw->block = io->block;
 482        pw->n_blocks = io->n_blocks;
 483        queue_work(v->verify_wq, &pw->work);
 484}
 485
 486/*
 487 * Bio map function. It allocates dm_verity_io structure and bio vector and
 488 * fills them. Then it issues prefetches and the I/O.
 489 */
 490static int verity_map(struct dm_target *ti, struct bio *bio)
 491{
 492        struct dm_verity *v = ti->private;
 493        struct dm_verity_io *io;
 494
 495        bio->bi_bdev = v->data_dev->bdev;
 496        bio->bi_sector = verity_map_sector(v, bio->bi_sector);
 497
 498        if (((unsigned)bio->bi_sector | bio_sectors(bio)) &
 499            ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 500                DMERR_LIMIT("unaligned io");
 501                return -EIO;
 502        }
 503
 504        if ((bio->bi_sector + bio_sectors(bio)) >>
 505            (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 506                DMERR_LIMIT("io out of range");
 507                return -EIO;
 508        }
 509
 510        if (bio_data_dir(bio) == WRITE)
 511                return -EIO;
 512
 513        io = dm_per_bio_data(bio, ti->per_bio_data_size);
 514        io->v = v;
 515        io->orig_bi_end_io = bio->bi_end_io;
 516        io->orig_bi_private = bio->bi_private;
 517        io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 518        io->n_blocks = bio->bi_size >> v->data_dev_block_bits;
 519
 520        bio->bi_end_io = verity_end_io;
 521        bio->bi_private = io;
 522        io->io_vec_size = bio->bi_vcnt - bio->bi_idx;
 523        if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE)
 524                io->io_vec = io->io_vec_inline;
 525        else
 526                io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO);
 527        memcpy(io->io_vec, bio_iovec(bio),
 528               io->io_vec_size * sizeof(struct bio_vec));
 529
 530        verity_submit_prefetch(v, io);
 531
 532        generic_make_request(bio);
 533
 534        return DM_MAPIO_SUBMITTED;
 535}
 536
 537/*
 538 * Status: V (valid) or C (corruption found)
 539 */
 540static void verity_status(struct dm_target *ti, status_type_t type,
 541                          unsigned status_flags, char *result, unsigned maxlen)
 542{
 543        struct dm_verity *v = ti->private;
 544        unsigned sz = 0;
 545        unsigned x;
 546
 547        switch (type) {
 548        case STATUSTYPE_INFO:
 549                DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 550                break;
 551        case STATUSTYPE_TABLE:
 552                DMEMIT("%u %s %s %u %u %llu %llu %s ",
 553                        v->version,
 554                        v->data_dev->name,
 555                        v->hash_dev->name,
 556                        1 << v->data_dev_block_bits,
 557                        1 << v->hash_dev_block_bits,
 558                        (unsigned long long)v->data_blocks,
 559                        (unsigned long long)v->hash_start,
 560                        v->alg_name
 561                        );
 562                for (x = 0; x < v->digest_size; x++)
 563                        DMEMIT("%02x", v->root_digest[x]);
 564                DMEMIT(" ");
 565                if (!v->salt_size)
 566                        DMEMIT("-");
 567                else
 568                        for (x = 0; x < v->salt_size; x++)
 569                                DMEMIT("%02x", v->salt[x]);
 570                break;
 571        }
 572}
 573
 574static int verity_ioctl(struct dm_target *ti, unsigned cmd,
 575                        unsigned long arg)
 576{
 577        struct dm_verity *v = ti->private;
 578        int r = 0;
 579
 580        if (v->data_start ||
 581            ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT)
 582                r = scsi_verify_blk_ioctl(NULL, cmd);
 583
 584        return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode,
 585                                     cmd, arg);
 586}
 587
 588static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
 589                        struct bio_vec *biovec, int max_size)
 590{
 591        struct dm_verity *v = ti->private;
 592        struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
 593
 594        if (!q->merge_bvec_fn)
 595                return max_size;
 596
 597        bvm->bi_bdev = v->data_dev->bdev;
 598        bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
 599
 600        return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
 601}
 602
 603static int verity_iterate_devices(struct dm_target *ti,
 604                                  iterate_devices_callout_fn fn, void *data)
 605{
 606        struct dm_verity *v = ti->private;
 607
 608        return fn(ti, v->data_dev, v->data_start, ti->len, data);
 609}
 610
 611static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 612{
 613        struct dm_verity *v = ti->private;
 614
 615        if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 616                limits->logical_block_size = 1 << v->data_dev_block_bits;
 617
 618        if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 619                limits->physical_block_size = 1 << v->data_dev_block_bits;
 620
 621        blk_limits_io_min(limits, limits->logical_block_size);
 622}
 623
 624static void verity_dtr(struct dm_target *ti)
 625{
 626        struct dm_verity *v = ti->private;
 627
 628        if (v->verify_wq)
 629                destroy_workqueue(v->verify_wq);
 630
 631        if (v->vec_mempool)
 632                mempool_destroy(v->vec_mempool);
 633
 634        if (v->bufio)
 635                dm_bufio_client_destroy(v->bufio);
 636
 637        kfree(v->salt);
 638        kfree(v->root_digest);
 639
 640        if (v->tfm)
 641                crypto_free_shash(v->tfm);
 642
 643        kfree(v->alg_name);
 644
 645        if (v->hash_dev)
 646                dm_put_device(ti, v->hash_dev);
 647
 648        if (v->data_dev)
 649                dm_put_device(ti, v->data_dev);
 650
 651        kfree(v);
 652}
 653
 654/*
 655 * Target parameters:
 656 *      <version>       The current format is version 1.
 657 *                      Vsn 0 is compatible with original Chromium OS releases.
 658 *      <data device>
 659 *      <hash device>
 660 *      <data block size>
 661 *      <hash block size>
 662 *      <the number of data blocks>
 663 *      <hash start block>
 664 *      <algorithm>
 665 *      <digest>
 666 *      <salt>          Hex string or "-" if no salt.
 667 */
 668static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 669{
 670        struct dm_verity *v;
 671        unsigned num;
 672        unsigned long long num_ll;
 673        int r;
 674        int i;
 675        sector_t hash_position;
 676        char dummy;
 677
 678        v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
 679        if (!v) {
 680                ti->error = "Cannot allocate verity structure";
 681                return -ENOMEM;
 682        }
 683        ti->private = v;
 684        v->ti = ti;
 685
 686        if ((dm_table_get_mode(ti->table) & ~FMODE_READ)) {
 687                ti->error = "Device must be readonly";
 688                r = -EINVAL;
 689                goto bad;
 690        }
 691
 692        if (argc != 10) {
 693                ti->error = "Invalid argument count: exactly 10 arguments required";
 694                r = -EINVAL;
 695                goto bad;
 696        }
 697
 698        if (sscanf(argv[0], "%d%c", &num, &dummy) != 1 ||
 699            num < 0 || num > 1) {
 700                ti->error = "Invalid version";
 701                r = -EINVAL;
 702                goto bad;
 703        }
 704        v->version = num;
 705
 706        r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev);
 707        if (r) {
 708                ti->error = "Data device lookup failed";
 709                goto bad;
 710        }
 711
 712        r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev);
 713        if (r) {
 714                ti->error = "Data device lookup failed";
 715                goto bad;
 716        }
 717
 718        if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
 719            !num || (num & (num - 1)) ||
 720            num < bdev_logical_block_size(v->data_dev->bdev) ||
 721            num > PAGE_SIZE) {
 722                ti->error = "Invalid data device block size";
 723                r = -EINVAL;
 724                goto bad;
 725        }
 726        v->data_dev_block_bits = ffs(num) - 1;
 727
 728        if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
 729            !num || (num & (num - 1)) ||
 730            num < bdev_logical_block_size(v->hash_dev->bdev) ||
 731            num > INT_MAX) {
 732                ti->error = "Invalid hash device block size";
 733                r = -EINVAL;
 734                goto bad;
 735        }
 736        v->hash_dev_block_bits = ffs(num) - 1;
 737
 738        if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
 739            (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
 740            >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 741                ti->error = "Invalid data blocks";
 742                r = -EINVAL;
 743                goto bad;
 744        }
 745        v->data_blocks = num_ll;
 746
 747        if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
 748                ti->error = "Data device is too small";
 749                r = -EINVAL;
 750                goto bad;
 751        }
 752
 753        if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
 754            (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
 755            >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
 756                ti->error = "Invalid hash start";
 757                r = -EINVAL;
 758                goto bad;
 759        }
 760        v->hash_start = num_ll;
 761
 762        v->alg_name = kstrdup(argv[7], GFP_KERNEL);
 763        if (!v->alg_name) {
 764                ti->error = "Cannot allocate algorithm name";
 765                r = -ENOMEM;
 766                goto bad;
 767        }
 768
 769        v->tfm = crypto_alloc_shash(v->alg_name, 0, 0);
 770        if (IS_ERR(v->tfm)) {
 771                ti->error = "Cannot initialize hash function";
 772                r = PTR_ERR(v->tfm);
 773                v->tfm = NULL;
 774                goto bad;
 775        }
 776        v->digest_size = crypto_shash_digestsize(v->tfm);
 777        if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
 778                ti->error = "Digest size too big";
 779                r = -EINVAL;
 780                goto bad;
 781        }
 782        v->shash_descsize =
 783                sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm);
 784
 785        v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
 786        if (!v->root_digest) {
 787                ti->error = "Cannot allocate root digest";
 788                r = -ENOMEM;
 789                goto bad;
 790        }
 791        if (strlen(argv[8]) != v->digest_size * 2 ||
 792            hex2bin(v->root_digest, argv[8], v->digest_size)) {
 793                ti->error = "Invalid root digest";
 794                r = -EINVAL;
 795                goto bad;
 796        }
 797
 798        if (strcmp(argv[9], "-")) {
 799                v->salt_size = strlen(argv[9]) / 2;
 800                v->salt = kmalloc(v->salt_size, GFP_KERNEL);
 801                if (!v->salt) {
 802                        ti->error = "Cannot allocate salt";
 803                        r = -ENOMEM;
 804                        goto bad;
 805                }
 806                if (strlen(argv[9]) != v->salt_size * 2 ||
 807                    hex2bin(v->salt, argv[9], v->salt_size)) {
 808                        ti->error = "Invalid salt";
 809                        r = -EINVAL;
 810                        goto bad;
 811                }
 812        }
 813
 814        v->hash_per_block_bits =
 815                fls((1 << v->hash_dev_block_bits) / v->digest_size) - 1;
 816
 817        v->levels = 0;
 818        if (v->data_blocks)
 819                while (v->hash_per_block_bits * v->levels < 64 &&
 820                       (unsigned long long)(v->data_blocks - 1) >>
 821                       (v->hash_per_block_bits * v->levels))
 822                        v->levels++;
 823
 824        if (v->levels > DM_VERITY_MAX_LEVELS) {
 825                ti->error = "Too many tree levels";
 826                r = -E2BIG;
 827                goto bad;
 828        }
 829
 830        hash_position = v->hash_start;
 831        for (i = v->levels - 1; i >= 0; i--) {
 832                sector_t s;
 833                v->hash_level_block[i] = hash_position;
 834                s = verity_position_at_level(v, v->data_blocks, i);
 835                s = (s >> v->hash_per_block_bits) +
 836                    !!(s & ((1 << v->hash_per_block_bits) - 1));
 837                if (hash_position + s < hash_position) {
 838                        ti->error = "Hash device offset overflow";
 839                        r = -E2BIG;
 840                        goto bad;
 841                }
 842                hash_position += s;
 843        }
 844        v->hash_blocks = hash_position;
 845
 846        v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
 847                1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
 848                dm_bufio_alloc_callback, NULL);
 849        if (IS_ERR(v->bufio)) {
 850                ti->error = "Cannot initialize dm-bufio";
 851                r = PTR_ERR(v->bufio);
 852                v->bufio = NULL;
 853                goto bad;
 854        }
 855
 856        if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
 857                ti->error = "Hash device is too small";
 858                r = -E2BIG;
 859                goto bad;
 860        }
 861
 862        ti->per_bio_data_size = roundup(sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2, __alignof__(struct dm_verity_io));
 863
 864        v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE,
 865                                        BIO_MAX_PAGES * sizeof(struct bio_vec));
 866        if (!v->vec_mempool) {
 867                ti->error = "Cannot allocate vector mempool";
 868                r = -ENOMEM;
 869                goto bad;
 870        }
 871
 872        /* WQ_UNBOUND greatly improves performance when running on ramdisk */
 873        v->verify_wq = alloc_workqueue("kverityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus());
 874        if (!v->verify_wq) {
 875                ti->error = "Cannot allocate workqueue";
 876                r = -ENOMEM;
 877                goto bad;
 878        }
 879
 880        return 0;
 881
 882bad:
 883        verity_dtr(ti);
 884
 885        return r;
 886}
 887
 888static struct target_type verity_target = {
 889        .name           = "verity",
 890        .version        = {1, 2, 0},
 891        .module         = THIS_MODULE,
 892        .ctr            = verity_ctr,
 893        .dtr            = verity_dtr,
 894        .map            = verity_map,
 895        .status         = verity_status,
 896        .ioctl          = verity_ioctl,
 897        .merge          = verity_merge,
 898        .iterate_devices = verity_iterate_devices,
 899        .io_hints       = verity_io_hints,
 900};
 901
 902static int __init dm_verity_init(void)
 903{
 904        int r;
 905
 906        r = dm_register_target(&verity_target);
 907        if (r < 0)
 908                DMERR("register failed %d", r);
 909
 910        return r;
 911}
 912
 913static void __exit dm_verity_exit(void)
 914{
 915        dm_unregister_target(&verity_target);
 916}
 917
 918module_init(dm_verity_init);
 919module_exit(dm_verity_exit);
 920
 921MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
 922MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
 923MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
 924MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
 925MODULE_LICENSE("GPL");
 926
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