drivers/md/dm-verity-target.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Red Hat, Inc.
   4  *
   5  * Author: Mikulas Patocka <[email protected]>
   6  *
   7  * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors
   8  *
   9  * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set
  10  * default prefetch value. Data are read in "prefetch_cluster" chunks from the
  11  * hash device. Setting this greatly improves performance when data and hash
  12  * are on the same disk on different partitions on devices with poor random
  13  * access behavior.
  14  */
  15
  16 #include "dm-verity.h"
  17 #include "dm-verity-fec.h"
  18 #include "dm-verity-verify-sig.h"
  19 #include "dm-audit.h"
  20 #include <linux/module.h>
  21 #include <linux/reboot.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/string.h>
  24 #include <linux/jump_label.h>
  25
  26 #define DM_MSG_PREFIX                   "verity"
  27
  28 #define DM_VERITY_ENV_LENGTH            42
  29 #define DM_VERITY_ENV_VAR_NAME          "DM_VERITY_ERR_BLOCK_NR"
  30
  31 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
  32
  33 #define DM_VERITY_MAX_CORRUPTED_ERRS    100
  34
  35 #define DM_VERITY_OPT_LOGGING           "ignore_corruption"
  36 #define DM_VERITY_OPT_RESTART           "restart_on_corruption"
  37 #define DM_VERITY_OPT_PANIC             "panic_on_corruption"
  38 #define DM_VERITY_OPT_IGN_ZEROES        "ignore_zero_blocks"
  39 #define DM_VERITY_OPT_AT_MOST_ONCE      "check_at_most_once"
  40 #define DM_VERITY_OPT_TASKLET_VERIFY    "try_verify_in_tasklet"
  41
  42 #define DM_VERITY_OPTS_MAX              (4 + DM_VERITY_OPTS_FEC + \
  43                                          DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
  44
  45 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  46
  47 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
  48
  49 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
  50
  51 /* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
  52 static DEFINE_STATIC_KEY_FALSE(ahash_enabled);
  53
  54 struct dm_verity_prefetch_work {
  55         struct work_struct work;
  56         struct dm_verity *v;
  57         unsigned short ioprio;
  58         sector_t block;
  59         unsigned int n_blocks;
  60 };
  61
  62 /*
  63  * Auxiliary structure appended to each dm-bufio buffer. If the value
  64  * hash_verified is nonzero, hash of the block has been verified.
  65  *
  66  * The variable hash_verified is set to 0 when allocating the buffer, then
  67  * it can be changed to 1 and it is never reset to 0 again.
  68  *
  69  * There is no lock around this value, a race condition can at worst cause
  70  * that multiple processes verify the hash of the same buffer simultaneously
  71  * and write 1 to hash_verified simultaneously.
  72  * This condition is harmless, so we don't need locking.
  73  */
  74 struct buffer_aux {
  75         int hash_verified;
  76 };
  77
  78 /*
  79  * Initialize struct buffer_aux for a freshly created buffer.
  80  */
  81 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  82 {
  83         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  84
  85         aux->hash_verified = 0;
  86 }
  87
  88 /*
  89  * Translate input sector number to the sector number on the target device.
  90  */
  91 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  92 {
  93         return v->data_start + dm_target_offset(v->ti, bi_sector);
  94 }
  95
  96 /*
  97  * Return hash position of a specified block at a specified tree level
  98  * (0 is the lowest level).
  99  * The lowest "hash_per_block_bits"-bits of the result denote hash position
 100  * inside a hash block. The remaining bits denote location of the hash block.
 101  */
 102 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
 103                                          int level)
 104 {
 105         return block >> (level * v->hash_per_block_bits);
 106 }
 107
 108 static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req,
 109                                 const u8 *data, size_t len,
 110                                 struct crypto_wait *wait)
 111 {
 112         struct scatterlist sg;
 113
 114         if (likely(!is_vmalloc_addr(data))) {
 115                 sg_init_one(&sg, data, len);
 116                 ahash_request_set_crypt(req, &sg, NULL, len);
 117                 return crypto_wait_req(crypto_ahash_update(req), wait);
 118         }
 119
 120         do {
 121                 int r;
 122                 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 123
 124                 flush_kernel_vmap_range((void *)data, this_step);
 125                 sg_init_table(&sg, 1);
 126                 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 127                 ahash_request_set_crypt(req, &sg, NULL, this_step);
 128                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 129                 if (unlikely(r))
 130                         return r;
 131                 data += this_step;
 132                 len -= this_step;
 133         } while (len);
 134
 135         return 0;
 136 }
 137
 138 /*
 139  * Wrapper for crypto_ahash_init, which handles verity salting.
 140  */
 141 static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req,
 142                                 struct crypto_wait *wait, bool may_sleep)
 143 {
 144         int r;
 145
 146         ahash_request_set_tfm(req, v->ahash_tfm);
 147         ahash_request_set_callback(req,
 148                 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
 149                 crypto_req_done, (void *)wait);
 150         crypto_init_wait(wait);
 151
 152         r = crypto_wait_req(crypto_ahash_init(req), wait);
 153
 154         if (unlikely(r < 0)) {
 155                 if (r != -ENOMEM)
 156                         DMERR("crypto_ahash_init failed: %d", r);
 157                 return r;
 158         }
 159
 160         if (likely(v->salt_size && (v->version >= 1)))
 161                 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
 162
 163         return r;
 164 }
 165
 166 static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req,
 167                               u8 *digest, struct crypto_wait *wait)
 168 {
 169         int r;
 170
 171         if (unlikely(v->salt_size && (!v->version))) {
 172                 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
 173
 174                 if (r < 0) {
 175                         DMERR("%s failed updating salt: %d", __func__, r);
 176                         goto out;
 177                 }
 178         }
 179
 180         ahash_request_set_crypt(req, NULL, digest, 0);
 181         r = crypto_wait_req(crypto_ahash_final(req), wait);
 182 out:
 183         return r;
 184 }
 185
 186 int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
 187                 const u8 *data, size_t len, u8 *digest, bool may_sleep)
 188 {
 189         int r;
 190
 191         if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) {
 192                 struct ahash_request *req = verity_io_hash_req(v, io);
 193                 struct crypto_wait wait;
 194
 195                 r = verity_ahash_init(v, req, &wait, may_sleep) ?:
 196                     verity_ahash_update(v, req, data, len, &wait) ?:
 197                     verity_ahash_final(v, req, digest, &wait);
 198         } else {
 199                 struct shash_desc *desc = verity_io_hash_req(v, io);
 200
 201                 desc->tfm = v->shash_tfm;
 202                 r = crypto_shash_import(desc, v->initial_hashstate) ?:
 203                     crypto_shash_finup(desc, data, len, digest);
 204         }
 205         if (unlikely(r))
 206                 DMERR("Error hashing block: %d", r);
 207         return r;
 208 }
 209
 210 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 211                                  sector_t *hash_block, unsigned int *offset)
 212 {
 213         sector_t position = verity_position_at_level(v, block, level);
 214         unsigned int idx;
 215
 216         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 217
 218         if (!offset)
 219                 return;
 220
 221         idx = position & ((1 << v->hash_per_block_bits) - 1);
 222         if (!v->version)
 223                 *offset = idx * v->digest_size;
 224         else
 225                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 226 }
 227
 228 /*
 229  * Handle verification errors.
 230  */
 231 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 232                              unsigned long long block)
 233 {
 234         char verity_env[DM_VERITY_ENV_LENGTH];
 235         char *envp[] = { verity_env, NULL };
 236         const char *type_str = "";
 237         struct mapped_device *md = dm_table_get_md(v->ti->table);
 238
 239         /* Corruption should be visible in device status in all modes */
 240         v->hash_failed = true;
 241
 242         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 243                 goto out;
 244
 245         v->corrupted_errs++;
 246
 247         switch (type) {
 248         case DM_VERITY_BLOCK_TYPE_DATA:
 249                 type_str = "data";
 250                 break;
 251         case DM_VERITY_BLOCK_TYPE_METADATA:
 252                 type_str = "metadata";
 253                 break;
 254         default:
 255                 BUG();
 256         }
 257
 258         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 259                     type_str, block);
 260
 261         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
 262                 DMERR("%s: reached maximum errors", v->data_dev->name);
 263                 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
 264         }
 265
 266         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 267                 DM_VERITY_ENV_VAR_NAME, type, block);
 268
 269         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 270
 271 out:
 272         if (v->mode == DM_VERITY_MODE_LOGGING)
 273                 return 0;
 274
 275         if (v->mode == DM_VERITY_MODE_RESTART)
 276                 kernel_restart("dm-verity device corrupted");
 277
 278         if (v->mode == DM_VERITY_MODE_PANIC)
 279                 panic("dm-verity device corrupted");
 280
 281         return 1;
 282 }
 283
 284 /*
 285  * Verify hash of a metadata block pertaining to the specified data block
 286  * ("block" argument) at a specified level ("level" argument).
 287  *
 288  * On successful return, verity_io_want_digest(v, io) contains the hash value
 289  * for a lower tree level or for the data block (if we're at the lowest level).
 290  *
 291  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 292  * If "skip_unverified" is false, unverified buffer is hashed and verified
 293  * against current value of verity_io_want_digest(v, io).
 294  */
 295 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 296                                sector_t block, int level, bool skip_unverified,
 297                                u8 *want_digest)
 298 {
 299         struct dm_buffer *buf;
 300         struct buffer_aux *aux;
 301         u8 *data;
 302         int r;
 303         sector_t hash_block;
 304         unsigned int offset;
 305         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 306
 307         verity_hash_at_level(v, block, level, &hash_block, &offset);
 308
 309         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 310                 data = dm_bufio_get(v->bufio, hash_block, &buf);
 311                 if (data == NULL) {
 312                         /*
 313                          * In tasklet and the hash was not in the bufio cache.
 314                          * Return early and resume execution from a work-queue
 315                          * to read the hash from disk.
 316                          */
 317                         return -EAGAIN;
 318                 }
 319         } else {
 320                 data = dm_bufio_read_with_ioprio(v->bufio, hash_block,
 321                                                 &buf, bio_prio(bio));
 322         }
 323
 324         if (IS_ERR(data))
 325                 return PTR_ERR(data);
 326
 327         aux = dm_bufio_get_aux_data(buf);
 328
 329         if (!aux->hash_verified) {
 330                 if (skip_unverified) {
 331                         r = 1;
 332                         goto release_ret_r;
 333                 }
 334
 335                 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits,
 336                                 verity_io_real_digest(v, io), !io->in_bh);
 337                 if (unlikely(r < 0))
 338                         goto release_ret_r;
 339
 340                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 341                                   v->digest_size) == 0))
 342                         aux->hash_verified = 1;
 343                 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 344                         /*
 345                          * Error handling code (FEC included) cannot be run in a
 346                          * tasklet since it may sleep, so fallback to work-queue.
 347                          */
 348                         r = -EAGAIN;
 349                         goto release_ret_r;
 350                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 351                                              hash_block, data) == 0)
 352                         aux->hash_verified = 1;
 353                 else if (verity_handle_err(v,
 354                                            DM_VERITY_BLOCK_TYPE_METADATA,
 355                                            hash_block)) {
 356                         struct bio *bio =
 357                                 dm_bio_from_per_bio_data(io,
 358                                                          v->ti->per_io_data_size);
 359                         dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
 360                                          block, 0);
 361                         r = -EIO;
 362                         goto release_ret_r;
 363                 }
 364         }
 365
 366         data += offset;
 367         memcpy(want_digest, data, v->digest_size);
 368         r = 0;
 369
 370 release_ret_r:
 371         dm_bufio_release(buf);
 372         return r;
 373 }
 374
 375 /*
 376  * Find a hash for a given block, write it to digest and verify the integrity
 377  * of the hash tree if necessary.
 378  */
 379 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 380                           sector_t block, u8 *digest, bool *is_zero)
 381 {
 382         int r = 0, i;
 383
 384         if (likely(v->levels)) {
 385                 /*
 386                  * First, we try to get the requested hash for
 387                  * the current block. If the hash block itself is
 388                  * verified, zero is returned. If it isn't, this
 389                  * function returns 1 and we fall back to whole
 390                  * chain verification.
 391                  */
 392                 r = verity_verify_level(v, io, block, 0, true, digest);
 393                 if (likely(r <= 0))
 394                         goto out;
 395         }
 396
 397         memcpy(digest, v->root_digest, v->digest_size);
 398
 399         for (i = v->levels - 1; i >= 0; i--) {
 400                 r = verity_verify_level(v, io, block, i, false, digest);
 401                 if (unlikely(r))
 402                         goto out;
 403         }
 404 out:
 405         if (!r && v->zero_digest)
 406                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 407         else
 408                 *is_zero = false;
 409
 410         return r;
 411 }
 412
 413 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
 414                                    sector_t cur_block, u8 *dest)
 415 {
 416         struct page *page;
 417         void *buffer;
 418         int r;
 419         struct dm_io_request io_req;
 420         struct dm_io_region io_loc;
 421
 422         page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
 423         buffer = page_to_virt(page);
 424
 425         io_req.bi_opf = REQ_OP_READ;
 426         io_req.mem.type = DM_IO_KMEM;
 427         io_req.mem.ptr.addr = buffer;
 428         io_req.notify.fn = NULL;
 429         io_req.client = v->io;
 430         io_loc.bdev = v->data_dev->bdev;
 431         io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
 432         io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
 433         r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
 434         if (unlikely(r))
 435                 goto free_ret;
 436
 437         r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
 438                         verity_io_real_digest(v, io), true);
 439         if (unlikely(r))
 440                 goto free_ret;
 441
 442         if (memcmp(verity_io_real_digest(v, io),
 443                    verity_io_want_digest(v, io), v->digest_size)) {
 444                 r = -EIO;
 445                 goto free_ret;
 446         }
 447
 448         memcpy(dest, buffer, 1 << v->data_dev_block_bits);
 449         r = 0;
 450 free_ret:
 451         mempool_free(page, &v->recheck_pool);
 452
 453         return r;
 454 }
 455
 456 static int verity_handle_data_hash_mismatch(struct dm_verity *v,
 457                                             struct dm_verity_io *io,
 458                                             struct bio *bio, sector_t blkno,
 459                                             u8 *data)
 460 {
 461         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 462                 /*
 463                  * Error handling code (FEC included) cannot be run in the
 464                  * BH workqueue, so fallback to a standard workqueue.
 465                  */
 466                 return -EAGAIN;
 467         }
 468         if (verity_recheck(v, io, blkno, data) == 0) {
 469                 if (v->validated_blocks)
 470                         set_bit(blkno, v->validated_blocks);
 471                 return 0;
 472         }
 473 #if defined(CONFIG_DM_VERITY_FEC)
 474         if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno,
 475                               data) == 0)
 476                 return 0;
 477 #endif
 478         if (bio->bi_status)
 479                 return -EIO; /* Error correction failed; Just return error */
 480
 481         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
 482                 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
 483                 return -EIO;
 484         }
 485         return 0;
 486 }
 487
 488 /*
 489  * Verify one "dm_verity_io" structure.
 490  */
 491 static int verity_verify_io(struct dm_verity_io *io)
 492 {
 493         struct dm_verity *v = io->v;
 494         const unsigned int block_size = 1 << v->data_dev_block_bits;
 495         struct bvec_iter iter_copy;
 496         struct bvec_iter *iter;
 497         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 498         unsigned int b;
 499
 500         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 501                 /*
 502                  * Copy the iterator in case we need to restart
 503                  * verification in a work-queue.
 504                  */
 505                 iter_copy = io->iter;
 506                 iter = &iter_copy;
 507         } else
 508                 iter = &io->iter;
 509
 510         for (b = 0; b < io->n_blocks;
 511              b++, bio_advance_iter(bio, iter, block_size)) {
 512                 int r;
 513                 sector_t cur_block = io->block + b;
 514                 bool is_zero;
 515                 struct bio_vec bv;
 516                 void *data;
 517
 518                 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 519                     likely(test_bit(cur_block, v->validated_blocks)))
 520                         continue;
 521
 522                 r = verity_hash_for_block(v, io, cur_block,
 523                                           verity_io_want_digest(v, io),
 524                                           &is_zero);
 525                 if (unlikely(r < 0))
 526                         return r;
 527
 528                 bv = bio_iter_iovec(bio, *iter);
 529                 if (unlikely(bv.bv_len < block_size)) {
 530                         /*
 531                          * Data block spans pages.  This should not happen,
 532                          * since dm-verity sets dma_alignment to the data block
 533                          * size minus 1, and dm-verity also doesn't allow the
 534                          * data block size to be greater than PAGE_SIZE.
 535                          */
 536                         DMERR_LIMIT("unaligned io (data block spans pages)");
 537                         return -EIO;
 538                 }
 539
 540                 data = bvec_kmap_local(&bv);
 541
 542                 if (is_zero) {
 543                         /*
 544                          * If we expect a zero block, don't validate, just
 545                          * return zeros.
 546                          */
 547                         memset(data, 0, block_size);
 548                         kunmap_local(data);
 549                         continue;
 550                 }
 551
 552                 r = verity_hash(v, io, data, block_size,
 553                                 verity_io_real_digest(v, io), !io->in_bh);
 554                 if (unlikely(r < 0)) {
 555                         kunmap_local(data);
 556                         return r;
 557                 }
 558
 559                 if (likely(memcmp(verity_io_real_digest(v, io),
 560                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 561                         if (v->validated_blocks)
 562                                 set_bit(cur_block, v->validated_blocks);
 563                         kunmap_local(data);
 564                         continue;
 565                 }
 566                 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block,
 567                                                      data);
 568                 kunmap_local(data);
 569                 if (unlikely(r))
 570                         return r;
 571         }
 572
 573         return 0;
 574 }
 575
 576 /*
 577  * Skip verity work in response to I/O error when system is shutting down.
 578  */
 579 static inline bool verity_is_system_shutting_down(void)
 580 {
 581         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 582                 || system_state == SYSTEM_RESTART;
 583 }
 584
 585 /*
 586  * End one "io" structure with a given error.
 587  */
 588 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 589 {
 590         struct dm_verity *v = io->v;
 591         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 592
 593         bio->bi_end_io = io->orig_bi_end_io;
 594         bio->bi_status = status;
 595
 596         if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
 597                 verity_fec_finish_io(io);
 598
 599         bio_endio(bio);
 600 }
 601
 602 static void verity_work(struct work_struct *w)
 603 {
 604         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 605
 606         io->in_bh = false;
 607
 608         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 609 }
 610
 611 static void verity_bh_work(struct work_struct *w)
 612 {
 613         struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
 614         int err;
 615
 616         io->in_bh = true;
 617         err = verity_verify_io(io);
 618         if (err == -EAGAIN || err == -ENOMEM) {
 619                 /* fallback to retrying with work-queue */
 620                 INIT_WORK(&io->work, verity_work);
 621                 queue_work(io->v->verify_wq, &io->work);
 622                 return;
 623         }
 624
 625         verity_finish_io(io, errno_to_blk_status(err));
 626 }
 627
 628 static void verity_end_io(struct bio *bio)
 629 {
 630         struct dm_verity_io *io = bio->bi_private;
 631
 632         if (bio->bi_status &&
 633             (!verity_fec_is_enabled(io->v) ||
 634              verity_is_system_shutting_down() ||
 635              (bio->bi_opf & REQ_RAHEAD))) {
 636                 verity_finish_io(io, bio->bi_status);
 637                 return;
 638         }
 639
 640         if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) {
 641                 INIT_WORK(&io->bh_work, verity_bh_work);
 642                 queue_work(system_bh_wq, &io->bh_work);
 643         } else {
 644                 INIT_WORK(&io->work, verity_work);
 645                 queue_work(io->v->verify_wq, &io->work);
 646         }
 647 }
 648
 649 /*
 650  * Prefetch buffers for the specified io.
 651  * The root buffer is not prefetched, it is assumed that it will be cached
 652  * all the time.
 653  */
 654 static void verity_prefetch_io(struct work_struct *work)
 655 {
 656         struct dm_verity_prefetch_work *pw =
 657                 container_of(work, struct dm_verity_prefetch_work, work);
 658         struct dm_verity *v = pw->v;
 659         int i;
 660
 661         for (i = v->levels - 2; i >= 0; i--) {
 662                 sector_t hash_block_start;
 663                 sector_t hash_block_end;
 664
 665                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 666                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 667
 668                 if (!i) {
 669                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 670
 671                         cluster >>= v->data_dev_block_bits;
 672                         if (unlikely(!cluster))
 673                                 goto no_prefetch_cluster;
 674
 675                         if (unlikely(cluster & (cluster - 1)))
 676                                 cluster = 1 << __fls(cluster);
 677
 678                         hash_block_start &= ~(sector_t)(cluster - 1);
 679                         hash_block_end |= cluster - 1;
 680                         if (unlikely(hash_block_end >= v->hash_blocks))
 681                                 hash_block_end = v->hash_blocks - 1;
 682                 }
 683 no_prefetch_cluster:
 684                 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start,
 685                                         hash_block_end - hash_block_start + 1,
 686                                         pw->ioprio);
 687         }
 688
 689         kfree(pw);
 690 }
 691
 692 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
 693                                    unsigned short ioprio)
 694 {
 695         sector_t block = io->block;
 696         unsigned int n_blocks = io->n_blocks;
 697         struct dm_verity_prefetch_work *pw;
 698
 699         if (v->validated_blocks) {
 700                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 701                         block++;
 702                         n_blocks--;
 703                 }
 704                 while (n_blocks && test_bit(block + n_blocks - 1,
 705                                             v->validated_blocks))
 706                         n_blocks--;
 707                 if (!n_blocks)
 708                         return;
 709         }
 710
 711         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 712                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 713
 714         if (!pw)
 715                 return;
 716
 717         INIT_WORK(&pw->work, verity_prefetch_io);
 718         pw->v = v;
 719         pw->block = block;
 720         pw->n_blocks = n_blocks;
 721         pw->ioprio = ioprio;
 722         queue_work(v->verify_wq, &pw->work);
 723 }
 724
 725 /*
 726  * Bio map function. It allocates dm_verity_io structure and bio vector and
 727  * fills them. Then it issues prefetches and the I/O.
 728  */
 729 static int verity_map(struct dm_target *ti, struct bio *bio)
 730 {
 731         struct dm_verity *v = ti->private;
 732         struct dm_verity_io *io;
 733
 734         bio_set_dev(bio, v->data_dev->bdev);
 735         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 736
 737         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 738             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 739                 DMERR_LIMIT("unaligned io");
 740                 return DM_MAPIO_KILL;
 741         }
 742
 743         if (bio_end_sector(bio) >>
 744             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 745                 DMERR_LIMIT("io out of range");
 746                 return DM_MAPIO_KILL;
 747         }
 748
 749         if (bio_data_dir(bio) == WRITE)
 750                 return DM_MAPIO_KILL;
 751
 752         io = dm_per_bio_data(bio, ti->per_io_data_size);
 753         io->v = v;
 754         io->orig_bi_end_io = bio->bi_end_io;
 755         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 756         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 757
 758         bio->bi_end_io = verity_end_io;
 759         bio->bi_private = io;
 760         io->iter = bio->bi_iter;
 761
 762         verity_fec_init_io(io);
 763
 764         verity_submit_prefetch(v, io, bio_prio(bio));
 765
 766         submit_bio_noacct(bio);
 767
 768         return DM_MAPIO_SUBMITTED;
 769 }
 770
 771 /*
 772  * Status: V (valid) or C (corruption found)
 773  */
 774 static void verity_status(struct dm_target *ti, status_type_t type,
 775                           unsigned int status_flags, char *result, unsigned int maxlen)
 776 {
 777         struct dm_verity *v = ti->private;
 778         unsigned int args = 0;
 779         unsigned int sz = 0;
 780         unsigned int x;
 781
 782         switch (type) {
 783         case STATUSTYPE_INFO:
 784                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 785                 break;
 786         case STATUSTYPE_TABLE:
 787                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 788                         v->version,
 789                         v->data_dev->name,
 790                         v->hash_dev->name,
 791                         1 << v->data_dev_block_bits,
 792                         1 << v->hash_dev_block_bits,
 793                         (unsigned long long)v->data_blocks,
 794                         (unsigned long long)v->hash_start,
 795                         v->alg_name
 796                         );
 797                 for (x = 0; x < v->digest_size; x++)
 798                         DMEMIT("%02x", v->root_digest[x]);
 799                 DMEMIT(" ");
 800                 if (!v->salt_size)
 801                         DMEMIT("-");
 802                 else
 803                         for (x = 0; x < v->salt_size; x++)
 804                                 DMEMIT("%02x", v->salt[x]);
 805                 if (v->mode != DM_VERITY_MODE_EIO)
 806                         args++;
 807                 if (verity_fec_is_enabled(v))
 808                         args += DM_VERITY_OPTS_FEC;
 809                 if (v->zero_digest)
 810                         args++;
 811                 if (v->validated_blocks)
 812                         args++;
 813                 if (v->use_bh_wq)
 814                         args++;
 815                 if (v->signature_key_desc)
 816                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 817                 if (!args)
 818                         return;
 819                 DMEMIT(" %u", args);
 820                 if (v->mode != DM_VERITY_MODE_EIO) {
 821                         DMEMIT(" ");
 822                         switch (v->mode) {
 823                         case DM_VERITY_MODE_LOGGING:
 824                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 825                                 break;
 826                         case DM_VERITY_MODE_RESTART:
 827                                 DMEMIT(DM_VERITY_OPT_RESTART);
 828                                 break;
 829                         case DM_VERITY_MODE_PANIC:
 830                                 DMEMIT(DM_VERITY_OPT_PANIC);
 831                                 break;
 832                         default:
 833                                 BUG();
 834                         }
 835                 }
 836                 if (v->zero_digest)
 837                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 838                 if (v->validated_blocks)
 839                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 840                 if (v->use_bh_wq)
 841                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 842                 sz = verity_fec_status_table(v, sz, result, maxlen);
 843                 if (v->signature_key_desc)
 844                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 845                                 " %s", v->signature_key_desc);
 846                 break;
 847
 848         case STATUSTYPE_IMA:
 849                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 850                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 851                 DMEMIT(",verity_version=%u", v->version);
 852                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 853                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 854                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 855
 856                 DMEMIT(",root_digest=");
 857                 for (x = 0; x < v->digest_size; x++)
 858                         DMEMIT("%02x", v->root_digest[x]);
 859
 860                 DMEMIT(",salt=");
 861                 if (!v->salt_size)
 862                         DMEMIT("-");
 863                 else
 864                         for (x = 0; x < v->salt_size; x++)
 865                                 DMEMIT("%02x", v->salt[x]);
 866
 867                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 868                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 869                 if (v->signature_key_desc)
 870                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 871
 872                 if (v->mode != DM_VERITY_MODE_EIO) {
 873                         DMEMIT(",verity_mode=");
 874                         switch (v->mode) {
 875                         case DM_VERITY_MODE_LOGGING:
 876                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 877                                 break;
 878                         case DM_VERITY_MODE_RESTART:
 879                                 DMEMIT(DM_VERITY_OPT_RESTART);
 880                                 break;
 881                         case DM_VERITY_MODE_PANIC:
 882                                 DMEMIT(DM_VERITY_OPT_PANIC);
 883                                 break;
 884                         default:
 885                                 DMEMIT("invalid");
 886                         }
 887                 }
 888                 DMEMIT(";");
 889                 break;
 890         }
 891 }
 892
 893 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 894 {
 895         struct dm_verity *v = ti->private;
 896
 897         *bdev = v->data_dev->bdev;
 898
 899         if (v->data_start || ti->len != bdev_nr_sectors(v->data_dev->bdev))
 900                 return 1;
 901         return 0;
 902 }
 903
 904 static int verity_iterate_devices(struct dm_target *ti,
 905                                   iterate_devices_callout_fn fn, void *data)
 906 {
 907         struct dm_verity *v = ti->private;
 908
 909         return fn(ti, v->data_dev, v->data_start, ti->len, data);
 910 }
 911
 912 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 913 {
 914         struct dm_verity *v = ti->private;
 915
 916         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 917                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 918
 919         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 920                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 921
 922         limits->io_min = limits->logical_block_size;
 923
 924         /*
 925          * Similar to what dm-crypt does, opt dm-verity out of support for
 926          * direct I/O that is aligned to less than the traditional direct I/O
 927          * alignment requirement of logical_block_size.  This prevents dm-verity
 928          * data blocks from crossing pages, eliminating various edge cases.
 929          */
 930         limits->dma_alignment = limits->logical_block_size - 1;
 931 }
 932
 933 static void verity_dtr(struct dm_target *ti)
 934 {
 935         struct dm_verity *v = ti->private;
 936
 937         if (v->verify_wq)
 938                 destroy_workqueue(v->verify_wq);
 939
 940         mempool_exit(&v->recheck_pool);
 941         if (v->io)
 942                 dm_io_client_destroy(v->io);
 943
 944         if (v->bufio)
 945                 dm_bufio_client_destroy(v->bufio);
 946
 947         kvfree(v->validated_blocks);
 948         kfree(v->salt);
 949         kfree(v->initial_hashstate);
 950         kfree(v->root_digest);
 951         kfree(v->zero_digest);
 952
 953         if (v->ahash_tfm) {
 954                 static_branch_dec(&ahash_enabled);
 955                 crypto_free_ahash(v->ahash_tfm);
 956         } else {
 957                 crypto_free_shash(v->shash_tfm);
 958         }
 959
 960         kfree(v->alg_name);
 961
 962         if (v->hash_dev)
 963                 dm_put_device(ti, v->hash_dev);
 964
 965         if (v->data_dev)
 966                 dm_put_device(ti, v->data_dev);
 967
 968         verity_fec_dtr(v);
 969
 970         kfree(v->signature_key_desc);
 971
 972         if (v->use_bh_wq)
 973                 static_branch_dec(&use_bh_wq_enabled);
 974
 975         kfree(v);
 976
 977         dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
 978 }
 979
 980 static int verity_alloc_most_once(struct dm_verity *v)
 981 {
 982         struct dm_target *ti = v->ti;
 983
 984         /* the bitset can only handle INT_MAX blocks */
 985         if (v->data_blocks > INT_MAX) {
 986                 ti->error = "device too large to use check_at_most_once";
 987                 return -E2BIG;
 988         }
 989
 990         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
 991                                        sizeof(unsigned long),
 992                                        GFP_KERNEL);
 993         if (!v->validated_blocks) {
 994                 ti->error = "failed to allocate bitset for check_at_most_once";
 995                 return -ENOMEM;
 996         }
 997
 998         return 0;
 999 }
1000
1001 static int verity_alloc_zero_digest(struct dm_verity *v)
1002 {
1003         int r = -ENOMEM;
1004         struct dm_verity_io *io;
1005         u8 *zero_data;
1006
1007         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1008
1009         if (!v->zero_digest)
1010                 return r;
1011
1012         io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL);
1013
1014         if (!io)
1015                 return r; /* verity_dtr will free zero_digest */
1016
1017         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1018
1019         if (!zero_data)
1020                 goto out;
1021
1022         r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits,
1023                         v->zero_digest, true);
1024
1025 out:
1026         kfree(io);
1027         kfree(zero_data);
1028
1029         return r;
1030 }
1031
1032 static inline bool verity_is_verity_mode(const char *arg_name)
1033 {
1034         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1035                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1036                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1037 }
1038
1039 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1040 {
1041         if (v->mode)
1042                 return -EINVAL;
1043
1044         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1045                 v->mode = DM_VERITY_MODE_LOGGING;
1046         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1047                 v->mode = DM_VERITY_MODE_RESTART;
1048         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1049                 v->mode = DM_VERITY_MODE_PANIC;
1050
1051         return 0;
1052 }
1053
1054 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1055                                  struct dm_verity_sig_opts *verify_args,
1056                                  bool only_modifier_opts)
1057 {
1058         int r = 0;
1059         unsigned int argc;
1060         struct dm_target *ti = v->ti;
1061         const char *arg_name;
1062
1063         static const struct dm_arg _args[] = {
1064                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1065         };
1066
1067         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1068         if (r)
1069                 return -EINVAL;
1070
1071         if (!argc)
1072                 return 0;
1073
1074         do {
1075                 arg_name = dm_shift_arg(as);
1076                 argc--;
1077
1078                 if (verity_is_verity_mode(arg_name)) {
1079                         if (only_modifier_opts)
1080                                 continue;
1081                         r = verity_parse_verity_mode(v, arg_name);
1082                         if (r) {
1083                                 ti->error = "Conflicting error handling parameters";
1084                                 return r;
1085                         }
1086                         continue;
1087
1088                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1089                         if (only_modifier_opts)
1090                                 continue;
1091                         r = verity_alloc_zero_digest(v);
1092                         if (r) {
1093                                 ti->error = "Cannot allocate zero digest";
1094                                 return r;
1095                         }
1096                         continue;
1097
1098                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1099                         if (only_modifier_opts)
1100                                 continue;
1101                         r = verity_alloc_most_once(v);
1102                         if (r)
1103                                 return r;
1104                         continue;
1105
1106                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1107                         v->use_bh_wq = true;
1108                         static_branch_inc(&use_bh_wq_enabled);
1109                         continue;
1110
1111                 } else if (verity_is_fec_opt_arg(arg_name)) {
1112                         if (only_modifier_opts)
1113                                 continue;
1114                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1115                         if (r)
1116                                 return r;
1117                         continue;
1118
1119                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1120                         if (only_modifier_opts)
1121                                 continue;
1122                         r = verity_verify_sig_parse_opt_args(as, v,
1123                                                              verify_args,
1124                                                              &argc, arg_name);
1125                         if (r)
1126                                 return r;
1127                         continue;
1128
1129                 } else if (only_modifier_opts) {
1130                         /*
1131                          * Ignore unrecognized opt, could easily be an extra
1132                          * argument to an option whose parsing was skipped.
1133                          * Normal parsing (@only_modifier_opts=false) will
1134                          * properly parse all options (and their extra args).
1135                          */
1136                         continue;
1137                 }
1138
1139                 DMERR("Unrecognized verity feature request: %s", arg_name);
1140                 ti->error = "Unrecognized verity feature request";
1141                 return -EINVAL;
1142         } while (argc && !r);
1143
1144         return r;
1145 }
1146
1147 static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name)
1148 {
1149         struct dm_target *ti = v->ti;
1150         struct crypto_ahash *ahash;
1151         struct crypto_shash *shash = NULL;
1152         const char *driver_name;
1153
1154         v->alg_name = kstrdup(alg_name, GFP_KERNEL);
1155         if (!v->alg_name) {
1156                 ti->error = "Cannot allocate algorithm name";
1157                 return -ENOMEM;
1158         }
1159
1160         /*
1161          * Allocate the hash transformation object that this dm-verity instance
1162          * will use.  The vast majority of dm-verity users use CPU-based
1163          * hashing, so when possible use the shash API to minimize the crypto
1164          * API overhead.  If the ahash API resolves to a different driver
1165          * (likely an off-CPU hardware offload), use ahash instead.  Also use
1166          * ahash if the obsolete dm-verity format with the appended salt is
1167          * being used, so that quirk only needs to be handled in one place.
1168          */
1169         ahash = crypto_alloc_ahash(alg_name, 0,
1170                                    v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
1171         if (IS_ERR(ahash)) {
1172                 ti->error = "Cannot initialize hash function";
1173                 return PTR_ERR(ahash);
1174         }
1175         driver_name = crypto_ahash_driver_name(ahash);
1176         if (v->version >= 1 /* salt prepended, not appended? */) {
1177                 shash = crypto_alloc_shash(alg_name, 0, 0);
1178                 if (!IS_ERR(shash) &&
1179                     strcmp(crypto_shash_driver_name(shash), driver_name) != 0) {
1180                         /*
1181                          * ahash gave a different driver than shash, so probably
1182                          * this is a case of real hardware offload.  Use ahash.
1183                          */
1184                         crypto_free_shash(shash);
1185                         shash = NULL;
1186                 }
1187         }
1188         if (!IS_ERR_OR_NULL(shash)) {
1189                 crypto_free_ahash(ahash);
1190                 ahash = NULL;
1191                 v->shash_tfm = shash;
1192                 v->digest_size = crypto_shash_digestsize(shash);
1193                 v->hash_reqsize = sizeof(struct shash_desc) +
1194                                   crypto_shash_descsize(shash);
1195                 DMINFO("%s using shash \"%s\"", alg_name, driver_name);
1196         } else {
1197                 v->ahash_tfm = ahash;
1198                 static_branch_inc(&ahash_enabled);
1199                 v->digest_size = crypto_ahash_digestsize(ahash);
1200                 v->hash_reqsize = sizeof(struct ahash_request) +
1201                                   crypto_ahash_reqsize(ahash);
1202                 DMINFO("%s using ahash \"%s\"", alg_name, driver_name);
1203         }
1204         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1205                 ti->error = "Digest size too big";
1206                 return -EINVAL;
1207         }
1208         return 0;
1209 }
1210
1211 static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg)
1212 {
1213         struct dm_target *ti = v->ti;
1214
1215         if (strcmp(arg, "-") != 0) {
1216                 v->salt_size = strlen(arg) / 2;
1217                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1218                 if (!v->salt) {
1219                         ti->error = "Cannot allocate salt";
1220                         return -ENOMEM;
1221                 }
1222                 if (strlen(arg) != v->salt_size * 2 ||
1223                     hex2bin(v->salt, arg, v->salt_size)) {
1224                         ti->error = "Invalid salt";
1225                         return -EINVAL;
1226                 }
1227         }
1228         if (v->shash_tfm) {
1229                 SHASH_DESC_ON_STACK(desc, v->shash_tfm);
1230                 int r;
1231
1232                 /*
1233                  * Compute the pre-salted hash state that can be passed to
1234                  * crypto_shash_import() for each block later.
1235                  */
1236                 v->initial_hashstate = kmalloc(
1237                         crypto_shash_statesize(v->shash_tfm), GFP_KERNEL);
1238                 if (!v->initial_hashstate) {
1239                         ti->error = "Cannot allocate initial hash state";
1240                         return -ENOMEM;
1241                 }
1242                 desc->tfm = v->shash_tfm;
1243                 r = crypto_shash_init(desc) ?:
1244                     crypto_shash_update(desc, v->salt, v->salt_size) ?:
1245                     crypto_shash_export(desc, v->initial_hashstate);
1246                 if (r) {
1247                         ti->error = "Cannot set up initial hash state";
1248                         return r;
1249                 }
1250         }
1251         return 0;
1252 }
1253
1254 /*
1255  * Target parameters:
1256  *      <version>       The current format is version 1.
1257  *                      Vsn 0 is compatible with original Chromium OS releases.
1258  *      <data device>
1259  *      <hash device>
1260  *      <data block size>
1261  *      <hash block size>
1262  *      <the number of data blocks>
1263  *      <hash start block>
1264  *      <algorithm>
1265  *      <digest>
1266  *      <salt>          Hex string or "-" if no salt.
1267  */
1268 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1269 {
1270         struct dm_verity *v;
1271         struct dm_verity_sig_opts verify_args = {0};
1272         struct dm_arg_set as;
1273         unsigned int num;
1274         unsigned long long num_ll;
1275         int r;
1276         int i;
1277         sector_t hash_position;
1278         char dummy;
1279         char *root_hash_digest_to_validate;
1280
1281         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1282         if (!v) {
1283                 ti->error = "Cannot allocate verity structure";
1284                 return -ENOMEM;
1285         }
1286         ti->private = v;
1287         v->ti = ti;
1288
1289         r = verity_fec_ctr_alloc(v);
1290         if (r)
1291                 goto bad;
1292
1293         if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1294                 ti->error = "Device must be readonly";
1295                 r = -EINVAL;
1296                 goto bad;
1297         }
1298
1299         if (argc < 10) {
1300                 ti->error = "Not enough arguments";
1301                 r = -EINVAL;
1302                 goto bad;
1303         }
1304
1305         /* Parse optional parameters that modify primary args */
1306         if (argc > 10) {
1307                 as.argc = argc - 10;
1308                 as.argv = argv + 10;
1309                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1310                 if (r < 0)
1311                         goto bad;
1312         }
1313
1314         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1315             num > 1) {
1316                 ti->error = "Invalid version";
1317                 r = -EINVAL;
1318                 goto bad;
1319         }
1320         v->version = num;
1321
1322         r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1323         if (r) {
1324                 ti->error = "Data device lookup failed";
1325                 goto bad;
1326         }
1327
1328         r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1329         if (r) {
1330                 ti->error = "Hash device lookup failed";
1331                 goto bad;
1332         }
1333
1334         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1335             !num || (num & (num - 1)) ||
1336             num < bdev_logical_block_size(v->data_dev->bdev) ||
1337             num > PAGE_SIZE) {
1338                 ti->error = "Invalid data device block size";
1339                 r = -EINVAL;
1340                 goto bad;
1341         }
1342         v->data_dev_block_bits = __ffs(num);
1343
1344         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1345             !num || (num & (num - 1)) ||
1346             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1347             num > INT_MAX) {
1348                 ti->error = "Invalid hash device block size";
1349                 r = -EINVAL;
1350                 goto bad;
1351         }
1352         v->hash_dev_block_bits = __ffs(num);
1353
1354         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1355             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1356             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1357                 ti->error = "Invalid data blocks";
1358                 r = -EINVAL;
1359                 goto bad;
1360         }
1361         v->data_blocks = num_ll;
1362
1363         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1364                 ti->error = "Data device is too small";
1365                 r = -EINVAL;
1366                 goto bad;
1367         }
1368
1369         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1370             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1371             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1372                 ti->error = "Invalid hash start";
1373                 r = -EINVAL;
1374                 goto bad;
1375         }
1376         v->hash_start = num_ll;
1377
1378         r = verity_setup_hash_alg(v, argv[7]);
1379         if (r)
1380                 goto bad;
1381
1382         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1383         if (!v->root_digest) {
1384                 ti->error = "Cannot allocate root digest";
1385                 r = -ENOMEM;
1386                 goto bad;
1387         }
1388         if (strlen(argv[8]) != v->digest_size * 2 ||
1389             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1390                 ti->error = "Invalid root digest";
1391                 r = -EINVAL;
1392                 goto bad;
1393         }
1394         root_hash_digest_to_validate = argv[8];
1395
1396         r = verity_setup_salt_and_hashstate(v, argv[9]);
1397         if (r)
1398                 goto bad;
1399
1400         argv += 10;
1401         argc -= 10;
1402
1403         /* Optional parameters */
1404         if (argc) {
1405                 as.argc = argc;
1406                 as.argv = argv;
1407                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1408                 if (r < 0)
1409                         goto bad;
1410         }
1411
1412         /* Root hash signature is  a optional parameter*/
1413         r = verity_verify_root_hash(root_hash_digest_to_validate,
1414                                     strlen(root_hash_digest_to_validate),
1415                                     verify_args.sig,
1416                                     verify_args.sig_size);
1417         if (r < 0) {
1418                 ti->error = "Root hash verification failed";
1419                 goto bad;
1420         }
1421         v->hash_per_block_bits =
1422                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1423
1424         v->levels = 0;
1425         if (v->data_blocks)
1426                 while (v->hash_per_block_bits * v->levels < 64 &&
1427                        (unsigned long long)(v->data_blocks - 1) >>
1428                        (v->hash_per_block_bits * v->levels))
1429                         v->levels++;
1430
1431         if (v->levels > DM_VERITY_MAX_LEVELS) {
1432                 ti->error = "Too many tree levels";
1433                 r = -E2BIG;
1434                 goto bad;
1435         }
1436
1437         hash_position = v->hash_start;
1438         for (i = v->levels - 1; i >= 0; i--) {
1439                 sector_t s;
1440
1441                 v->hash_level_block[i] = hash_position;
1442                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1443                                         >> ((i + 1) * v->hash_per_block_bits);
1444                 if (hash_position + s < hash_position) {
1445                         ti->error = "Hash device offset overflow";
1446                         r = -E2BIG;
1447                         goto bad;
1448                 }
1449                 hash_position += s;
1450         }
1451         v->hash_blocks = hash_position;
1452
1453         r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1454         if (unlikely(r)) {
1455                 ti->error = "Cannot allocate mempool";
1456                 goto bad;
1457         }
1458
1459         v->io = dm_io_client_create();
1460         if (IS_ERR(v->io)) {
1461                 r = PTR_ERR(v->io);
1462                 v->io = NULL;
1463                 ti->error = "Cannot allocate dm io";
1464                 goto bad;
1465         }
1466
1467         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1468                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1469                 dm_bufio_alloc_callback, NULL,
1470                 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1471         if (IS_ERR(v->bufio)) {
1472                 ti->error = "Cannot initialize dm-bufio";
1473                 r = PTR_ERR(v->bufio);
1474                 v->bufio = NULL;
1475                 goto bad;
1476         }
1477
1478         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1479                 ti->error = "Hash device is too small";
1480                 r = -E2BIG;
1481                 goto bad;
1482         }
1483
1484         /*
1485          * Using WQ_HIGHPRI improves throughput and completion latency by
1486          * reducing wait times when reading from a dm-verity device.
1487          *
1488          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1489          * allows verify_wq to preempt softirq since verification in BH workqueue
1490          * will fall-back to using it for error handling (or if the bufio cache
1491          * doesn't have required hashes).
1492          */
1493         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1494         if (!v->verify_wq) {
1495                 ti->error = "Cannot allocate workqueue";
1496                 r = -ENOMEM;
1497                 goto bad;
1498         }
1499
1500         ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize;
1501
1502         r = verity_fec_ctr(v);
1503         if (r)
1504                 goto bad;
1505
1506         ti->per_io_data_size = roundup(ti->per_io_data_size,
1507                                        __alignof__(struct dm_verity_io));
1508
1509         verity_verify_sig_opts_cleanup(&verify_args);
1510
1511         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1512
1513         return 0;
1514
1515 bad:
1516
1517         verity_verify_sig_opts_cleanup(&verify_args);
1518         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1519         verity_dtr(ti);
1520
1521         return r;
1522 }
1523
1524 /*
1525  * Get the verity mode (error behavior) of a verity target.
1526  *
1527  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1528  * target.
1529  */
1530 int dm_verity_get_mode(struct dm_target *ti)
1531 {
1532         struct dm_verity *v = ti->private;
1533
1534         if (!dm_is_verity_target(ti))
1535                 return -EINVAL;
1536
1537         return v->mode;
1538 }
1539
1540 /*
1541  * Get the root digest of a verity target.
1542  *
1543  * Returns a copy of the root digest, the caller is responsible for
1544  * freeing the memory of the digest.
1545  */
1546 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1547 {
1548         struct dm_verity *v = ti->private;
1549
1550         if (!dm_is_verity_target(ti))
1551                 return -EINVAL;
1552
1553         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1554         if (*root_digest == NULL)
1555                 return -ENOMEM;
1556
1557         *digest_size = v->digest_size;
1558
1559         return 0;
1560 }
1561
1562 static struct target_type verity_target = {
1563         .name           = "verity",
1564         .features       = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1565         .version        = {1, 10, 0},
1566         .module         = THIS_MODULE,
1567         .ctr            = verity_ctr,
1568         .dtr            = verity_dtr,
1569         .map            = verity_map,
1570         .status         = verity_status,
1571         .prepare_ioctl  = verity_prepare_ioctl,
1572         .iterate_devices = verity_iterate_devices,
1573         .io_hints       = verity_io_hints,
1574 };
1575 module_dm(verity);
1576
1577 /*
1578  * Check whether a DM target is a verity target.
1579  */
1580 bool dm_is_verity_target(struct dm_target *ti)
1581 {
1582         return ti->type == &verity_target;
1583 }
1584
1585 MODULE_AUTHOR("Mikulas Patocka <[email protected]>");
1586 MODULE_AUTHOR("Mandeep Baines <[email protected]>");
1587 MODULE_AUTHOR("Will Drewry <[email protected]>");
1588 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1589 MODULE_LICENSE("GPL");