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 #include <linux/security.h>
  26
  27 #define DM_MSG_PREFIX                   "verity"
  28
  29 #define DM_VERITY_ENV_LENGTH            42
  30 #define DM_VERITY_ENV_VAR_NAME          "DM_VERITY_ERR_BLOCK_NR"
  31
  32 #define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144
  33
  34 #define DM_VERITY_MAX_CORRUPTED_ERRS    100
  35
  36 #define DM_VERITY_OPT_LOGGING           "ignore_corruption"
  37 #define DM_VERITY_OPT_RESTART           "restart_on_corruption"
  38 #define DM_VERITY_OPT_PANIC             "panic_on_corruption"
  39 #define DM_VERITY_OPT_ERROR_RESTART     "restart_on_error"
  40 #define DM_VERITY_OPT_ERROR_PANIC       "panic_on_error"
  41 #define DM_VERITY_OPT_IGN_ZEROES        "ignore_zero_blocks"
  42 #define DM_VERITY_OPT_AT_MOST_ONCE      "check_at_most_once"
  43 #define DM_VERITY_OPT_TASKLET_VERIFY    "try_verify_in_tasklet"
  44
  45 #define DM_VERITY_OPTS_MAX              (5 + DM_VERITY_OPTS_FEC + \
  46                                          DM_VERITY_ROOT_HASH_VERIFICATION_OPTS)
  47
  48 static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  49
  50 module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
  51
  52 static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
  53
  54 /* Is at least one dm-verity instance using ahash_tfm instead of shash_tfm? */
  55 static DEFINE_STATIC_KEY_FALSE(ahash_enabled);
  56
  57 struct dm_verity_prefetch_work {
  58         struct work_struct work;
  59         struct dm_verity *v;
  60         unsigned short ioprio;
  61         sector_t block;
  62         unsigned int n_blocks;
  63 };
  64
  65 /*
  66  * Auxiliary structure appended to each dm-bufio buffer. If the value
  67  * hash_verified is nonzero, hash of the block has been verified.
  68  *
  69  * The variable hash_verified is set to 0 when allocating the buffer, then
  70  * it can be changed to 1 and it is never reset to 0 again.
  71  *
  72  * There is no lock around this value, a race condition can at worst cause
  73  * that multiple processes verify the hash of the same buffer simultaneously
  74  * and write 1 to hash_verified simultaneously.
  75  * This condition is harmless, so we don't need locking.
  76  */
  77 struct buffer_aux {
  78         int hash_verified;
  79 };
  80
  81 /*
  82  * Initialize struct buffer_aux for a freshly created buffer.
  83  */
  84 static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  85 {
  86         struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  87
  88         aux->hash_verified = 0;
  89 }
  90
  91 /*
  92  * Translate input sector number to the sector number on the target device.
  93  */
  94 static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
  95 {
  96         return dm_target_offset(v->ti, bi_sector);
  97 }
  98
  99 /*
 100  * Return hash position of a specified block at a specified tree level
 101  * (0 is the lowest level).
 102  * The lowest "hash_per_block_bits"-bits of the result denote hash position
 103  * inside a hash block. The remaining bits denote location of the hash block.
 104  */
 105 static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
 106                                          int level)
 107 {
 108         return block >> (level * v->hash_per_block_bits);
 109 }
 110
 111 static int verity_ahash_update(struct dm_verity *v, struct ahash_request *req,
 112                                 const u8 *data, size_t len,
 113                                 struct crypto_wait *wait)
 114 {
 115         struct scatterlist sg;
 116
 117         if (likely(!is_vmalloc_addr(data))) {
 118                 sg_init_one(&sg, data, len);
 119                 ahash_request_set_crypt(req, &sg, NULL, len);
 120                 return crypto_wait_req(crypto_ahash_update(req), wait);
 121         }
 122
 123         do {
 124                 int r;
 125                 size_t this_step = min_t(size_t, len, PAGE_SIZE - offset_in_page(data));
 126
 127                 flush_kernel_vmap_range((void *)data, this_step);
 128                 sg_init_table(&sg, 1);
 129                 sg_set_page(&sg, vmalloc_to_page(data), this_step, offset_in_page(data));
 130                 ahash_request_set_crypt(req, &sg, NULL, this_step);
 131                 r = crypto_wait_req(crypto_ahash_update(req), wait);
 132                 if (unlikely(r))
 133                         return r;
 134                 data += this_step;
 135                 len -= this_step;
 136         } while (len);
 137
 138         return 0;
 139 }
 140
 141 /*
 142  * Wrapper for crypto_ahash_init, which handles verity salting.
 143  */
 144 static int verity_ahash_init(struct dm_verity *v, struct ahash_request *req,
 145                                 struct crypto_wait *wait, bool may_sleep)
 146 {
 147         int r;
 148
 149         ahash_request_set_tfm(req, v->ahash_tfm);
 150         ahash_request_set_callback(req,
 151                 may_sleep ? CRYPTO_TFM_REQ_MAY_SLEEP | CRYPTO_TFM_REQ_MAY_BACKLOG : 0,
 152                 crypto_req_done, (void *)wait);
 153         crypto_init_wait(wait);
 154
 155         r = crypto_wait_req(crypto_ahash_init(req), wait);
 156
 157         if (unlikely(r < 0)) {
 158                 if (r != -ENOMEM)
 159                         DMERR("crypto_ahash_init failed: %d", r);
 160                 return r;
 161         }
 162
 163         if (likely(v->salt_size && (v->version >= 1)))
 164                 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
 165
 166         return r;
 167 }
 168
 169 static int verity_ahash_final(struct dm_verity *v, struct ahash_request *req,
 170                               u8 *digest, struct crypto_wait *wait)
 171 {
 172         int r;
 173
 174         if (unlikely(v->salt_size && (!v->version))) {
 175                 r = verity_ahash_update(v, req, v->salt, v->salt_size, wait);
 176
 177                 if (r < 0) {
 178                         DMERR("%s failed updating salt: %d", __func__, r);
 179                         goto out;
 180                 }
 181         }
 182
 183         ahash_request_set_crypt(req, NULL, digest, 0);
 184         r = crypto_wait_req(crypto_ahash_final(req), wait);
 185 out:
 186         return r;
 187 }
 188
 189 int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
 190                 const u8 *data, size_t len, u8 *digest, bool may_sleep)
 191 {
 192         int r;
 193
 194         if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm) {
 195                 struct ahash_request *req = verity_io_hash_req(v, io);
 196                 struct crypto_wait wait;
 197
 198                 r = verity_ahash_init(v, req, &wait, may_sleep) ?:
 199                     verity_ahash_update(v, req, data, len, &wait) ?:
 200                     verity_ahash_final(v, req, digest, &wait);
 201         } else {
 202                 struct shash_desc *desc = verity_io_hash_req(v, io);
 203
 204                 desc->tfm = v->shash_tfm;
 205                 r = crypto_shash_import(desc, v->initial_hashstate) ?:
 206                     crypto_shash_finup(desc, data, len, digest);
 207         }
 208         if (unlikely(r))
 209                 DMERR("Error hashing block: %d", r);
 210         return r;
 211 }
 212
 213 static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 214                                  sector_t *hash_block, unsigned int *offset)
 215 {
 216         sector_t position = verity_position_at_level(v, block, level);
 217         unsigned int idx;
 218
 219         *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 220
 221         if (!offset)
 222                 return;
 223
 224         idx = position & ((1 << v->hash_per_block_bits) - 1);
 225         if (!v->version)
 226                 *offset = idx * v->digest_size;
 227         else
 228                 *offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 229 }
 230
 231 /*
 232  * Handle verification errors.
 233  */
 234 static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 235                              unsigned long long block)
 236 {
 237         char verity_env[DM_VERITY_ENV_LENGTH];
 238         char *envp[] = { verity_env, NULL };
 239         const char *type_str = "";
 240         struct mapped_device *md = dm_table_get_md(v->ti->table);
 241
 242         /* Corruption should be visible in device status in all modes */
 243         v->hash_failed = true;
 244
 245         if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 246                 goto out;
 247
 248         v->corrupted_errs++;
 249
 250         switch (type) {
 251         case DM_VERITY_BLOCK_TYPE_DATA:
 252                 type_str = "data";
 253                 break;
 254         case DM_VERITY_BLOCK_TYPE_METADATA:
 255                 type_str = "metadata";
 256                 break;
 257         default:
 258                 BUG();
 259         }
 260
 261         DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 262                     type_str, block);
 263
 264         if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
 265                 DMERR("%s: reached maximum errors", v->data_dev->name);
 266                 dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
 267         }
 268
 269         snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 270                 DM_VERITY_ENV_VAR_NAME, type, block);
 271
 272         kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 273
 274 out:
 275         if (v->mode == DM_VERITY_MODE_LOGGING)
 276                 return 0;
 277
 278         if (v->mode == DM_VERITY_MODE_RESTART)
 279                 kernel_restart("dm-verity device corrupted");
 280
 281         if (v->mode == DM_VERITY_MODE_PANIC)
 282                 panic("dm-verity device corrupted");
 283
 284         return 1;
 285 }
 286
 287 /*
 288  * Verify hash of a metadata block pertaining to the specified data block
 289  * ("block" argument) at a specified level ("level" argument).
 290  *
 291  * On successful return, verity_io_want_digest(v, io) contains the hash value
 292  * for a lower tree level or for the data block (if we're at the lowest level).
 293  *
 294  * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 295  * If "skip_unverified" is false, unverified buffer is hashed and verified
 296  * against current value of verity_io_want_digest(v, io).
 297  */
 298 static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 299                                sector_t block, int level, bool skip_unverified,
 300                                u8 *want_digest)
 301 {
 302         struct dm_buffer *buf;
 303         struct buffer_aux *aux;
 304         u8 *data;
 305         int r;
 306         sector_t hash_block;
 307         unsigned int offset;
 308         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 309
 310         verity_hash_at_level(v, block, level, &hash_block, &offset);
 311
 312         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 313                 data = dm_bufio_get(v->bufio, hash_block, &buf);
 314                 if (data == NULL) {
 315                         /*
 316                          * In tasklet and the hash was not in the bufio cache.
 317                          * Return early and resume execution from a work-queue
 318                          * to read the hash from disk.
 319                          */
 320                         return -EAGAIN;
 321                 }
 322         } else {
 323                 data = dm_bufio_read_with_ioprio(v->bufio, hash_block,
 324                                                 &buf, bio_prio(bio));
 325         }
 326
 327         if (IS_ERR(data))
 328                 return PTR_ERR(data);
 329
 330         aux = dm_bufio_get_aux_data(buf);
 331
 332         if (!aux->hash_verified) {
 333                 if (skip_unverified) {
 334                         r = 1;
 335                         goto release_ret_r;
 336                 }
 337
 338                 r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits,
 339                                 verity_io_real_digest(v, io), !io->in_bh);
 340                 if (unlikely(r < 0))
 341                         goto release_ret_r;
 342
 343                 if (likely(memcmp(verity_io_real_digest(v, io), want_digest,
 344                                   v->digest_size) == 0))
 345                         aux->hash_verified = 1;
 346                 else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 347                         /*
 348                          * Error handling code (FEC included) cannot be run in a
 349                          * tasklet since it may sleep, so fallback to work-queue.
 350                          */
 351                         r = -EAGAIN;
 352                         goto release_ret_r;
 353                 } else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 354                                              hash_block, data) == 0)
 355                         aux->hash_verified = 1;
 356                 else if (verity_handle_err(v,
 357                                            DM_VERITY_BLOCK_TYPE_METADATA,
 358                                            hash_block)) {
 359                         struct bio *bio;
 360                         io->had_mismatch = true;
 361                         bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 362                         dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
 363                                          block, 0);
 364                         r = -EIO;
 365                         goto release_ret_r;
 366                 }
 367         }
 368
 369         data += offset;
 370         memcpy(want_digest, data, v->digest_size);
 371         r = 0;
 372
 373 release_ret_r:
 374         dm_bufio_release(buf);
 375         return r;
 376 }
 377
 378 /*
 379  * Find a hash for a given block, write it to digest and verify the integrity
 380  * of the hash tree if necessary.
 381  */
 382 int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 383                           sector_t block, u8 *digest, bool *is_zero)
 384 {
 385         int r = 0, i;
 386
 387         if (likely(v->levels)) {
 388                 /*
 389                  * First, we try to get the requested hash for
 390                  * the current block. If the hash block itself is
 391                  * verified, zero is returned. If it isn't, this
 392                  * function returns 1 and we fall back to whole
 393                  * chain verification.
 394                  */
 395                 r = verity_verify_level(v, io, block, 0, true, digest);
 396                 if (likely(r <= 0))
 397                         goto out;
 398         }
 399
 400         memcpy(digest, v->root_digest, v->digest_size);
 401
 402         for (i = v->levels - 1; i >= 0; i--) {
 403                 r = verity_verify_level(v, io, block, i, false, digest);
 404                 if (unlikely(r))
 405                         goto out;
 406         }
 407 out:
 408         if (!r && v->zero_digest)
 409                 *is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 410         else
 411                 *is_zero = false;
 412
 413         return r;
 414 }
 415
 416 static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
 417                                    sector_t cur_block, u8 *dest)
 418 {
 419         struct page *page;
 420         void *buffer;
 421         int r;
 422         struct dm_io_request io_req;
 423         struct dm_io_region io_loc;
 424
 425         page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
 426         buffer = page_to_virt(page);
 427
 428         io_req.bi_opf = REQ_OP_READ;
 429         io_req.mem.type = DM_IO_KMEM;
 430         io_req.mem.ptr.addr = buffer;
 431         io_req.notify.fn = NULL;
 432         io_req.client = v->io;
 433         io_loc.bdev = v->data_dev->bdev;
 434         io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
 435         io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
 436         r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
 437         if (unlikely(r))
 438                 goto free_ret;
 439
 440         r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
 441                         verity_io_real_digest(v, io), true);
 442         if (unlikely(r))
 443                 goto free_ret;
 444
 445         if (memcmp(verity_io_real_digest(v, io),
 446                    verity_io_want_digest(v, io), v->digest_size)) {
 447                 r = -EIO;
 448                 goto free_ret;
 449         }
 450
 451         memcpy(dest, buffer, 1 << v->data_dev_block_bits);
 452         r = 0;
 453 free_ret:
 454         mempool_free(page, &v->recheck_pool);
 455
 456         return r;
 457 }
 458
 459 static int verity_handle_data_hash_mismatch(struct dm_verity *v,
 460                                             struct dm_verity_io *io,
 461                                             struct bio *bio, sector_t blkno,
 462                                             u8 *data)
 463 {
 464         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 465                 /*
 466                  * Error handling code (FEC included) cannot be run in the
 467                  * BH workqueue, so fallback to a standard workqueue.
 468                  */
 469                 return -EAGAIN;
 470         }
 471         if (verity_recheck(v, io, blkno, data) == 0) {
 472                 if (v->validated_blocks)
 473                         set_bit(blkno, v->validated_blocks);
 474                 return 0;
 475         }
 476 #if defined(CONFIG_DM_VERITY_FEC)
 477         if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, blkno,
 478                               data) == 0)
 479                 return 0;
 480 #endif
 481         if (bio->bi_status)
 482                 return -EIO; /* Error correction failed; Just return error */
 483
 484         if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
 485                 io->had_mismatch = true;
 486                 dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
 487                 return -EIO;
 488         }
 489         return 0;
 490 }
 491
 492 /*
 493  * Verify one "dm_verity_io" structure.
 494  */
 495 static int verity_verify_io(struct dm_verity_io *io)
 496 {
 497         struct dm_verity *v = io->v;
 498         const unsigned int block_size = 1 << v->data_dev_block_bits;
 499         struct bvec_iter iter_copy;
 500         struct bvec_iter *iter;
 501         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 502         unsigned int b;
 503
 504         if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 505                 /*
 506                  * Copy the iterator in case we need to restart
 507                  * verification in a work-queue.
 508                  */
 509                 iter_copy = io->iter;
 510                 iter = &iter_copy;
 511         } else
 512                 iter = &io->iter;
 513
 514         for (b = 0; b < io->n_blocks;
 515              b++, bio_advance_iter(bio, iter, block_size)) {
 516                 int r;
 517                 sector_t cur_block = io->block + b;
 518                 bool is_zero;
 519                 struct bio_vec bv;
 520                 void *data;
 521
 522                 if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 523                     likely(test_bit(cur_block, v->validated_blocks)))
 524                         continue;
 525
 526                 r = verity_hash_for_block(v, io, cur_block,
 527                                           verity_io_want_digest(v, io),
 528                                           &is_zero);
 529                 if (unlikely(r < 0))
 530                         return r;
 531
 532                 bv = bio_iter_iovec(bio, *iter);
 533                 if (unlikely(bv.bv_len < block_size)) {
 534                         /*
 535                          * Data block spans pages.  This should not happen,
 536                          * since dm-verity sets dma_alignment to the data block
 537                          * size minus 1, and dm-verity also doesn't allow the
 538                          * data block size to be greater than PAGE_SIZE.
 539                          */
 540                         DMERR_LIMIT("unaligned io (data block spans pages)");
 541                         return -EIO;
 542                 }
 543
 544                 data = bvec_kmap_local(&bv);
 545
 546                 if (is_zero) {
 547                         /*
 548                          * If we expect a zero block, don't validate, just
 549                          * return zeros.
 550                          */
 551                         memset(data, 0, block_size);
 552                         kunmap_local(data);
 553                         continue;
 554                 }
 555
 556                 r = verity_hash(v, io, data, block_size,
 557                                 verity_io_real_digest(v, io), !io->in_bh);
 558                 if (unlikely(r < 0)) {
 559                         kunmap_local(data);
 560                         return r;
 561                 }
 562
 563                 if (likely(memcmp(verity_io_real_digest(v, io),
 564                                   verity_io_want_digest(v, io), v->digest_size) == 0)) {
 565                         if (v->validated_blocks)
 566                                 set_bit(cur_block, v->validated_blocks);
 567                         kunmap_local(data);
 568                         continue;
 569                 }
 570                 r = verity_handle_data_hash_mismatch(v, io, bio, cur_block,
 571                                                      data);
 572                 kunmap_local(data);
 573                 if (unlikely(r))
 574                         return r;
 575         }
 576
 577         return 0;
 578 }
 579
 580 /*
 581  * Skip verity work in response to I/O error when system is shutting down.
 582  */
 583 static inline bool verity_is_system_shutting_down(void)
 584 {
 585         return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 586                 || system_state == SYSTEM_RESTART;
 587 }
 588
 589 static void restart_io_error(struct work_struct *w)
 590 {
 591         kernel_restart("dm-verity device has I/O error");
 592 }
 593
 594 /*
 595  * End one "io" structure with a given error.
 596  */
 597 static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 598 {
 599         struct dm_verity *v = io->v;
 600         struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 601
 602         bio->bi_end_io = io->orig_bi_end_io;
 603         bio->bi_status = status;
 604
 605         if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
 606                 verity_fec_finish_io(io);
 607
 608         if (unlikely(status != BLK_STS_OK) &&
 609             unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
 610             !io->had_mismatch &&
 611             !verity_is_system_shutting_down()) {
 612                 if (v->error_mode == DM_VERITY_MODE_PANIC) {
 613                         panic("dm-verity device has I/O error");
 614                 }
 615                 if (v->error_mode == DM_VERITY_MODE_RESTART) {
 616                         static DECLARE_WORK(restart_work, restart_io_error);
 617                         queue_work(v->verify_wq, &restart_work);
 618                         /*
 619                          * We deliberately don't call bio_endio here, because
 620                          * the machine will be restarted anyway.
 621                          */
 622                         return;
 623                 }
 624         }
 625
 626         bio_endio(bio);
 627 }
 628
 629 static void verity_work(struct work_struct *w)
 630 {
 631         struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 632
 633         io->in_bh = false;
 634
 635         verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 636 }
 637
 638 static void verity_bh_work(struct work_struct *w)
 639 {
 640         struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
 641         int err;
 642
 643         io->in_bh = true;
 644         err = verity_verify_io(io);
 645         if (err == -EAGAIN || err == -ENOMEM) {
 646                 /* fallback to retrying with work-queue */
 647                 INIT_WORK(&io->work, verity_work);
 648                 queue_work(io->v->verify_wq, &io->work);
 649                 return;
 650         }
 651
 652         verity_finish_io(io, errno_to_blk_status(err));
 653 }
 654
 655 static void verity_end_io(struct bio *bio)
 656 {
 657         struct dm_verity_io *io = bio->bi_private;
 658
 659         if (bio->bi_status &&
 660             (!verity_fec_is_enabled(io->v) ||
 661              verity_is_system_shutting_down() ||
 662              (bio->bi_opf & REQ_RAHEAD))) {
 663                 verity_finish_io(io, bio->bi_status);
 664                 return;
 665         }
 666
 667         if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq) {
 668                 INIT_WORK(&io->bh_work, verity_bh_work);
 669                 queue_work(system_bh_wq, &io->bh_work);
 670         } else {
 671                 INIT_WORK(&io->work, verity_work);
 672                 queue_work(io->v->verify_wq, &io->work);
 673         }
 674 }
 675
 676 /*
 677  * Prefetch buffers for the specified io.
 678  * The root buffer is not prefetched, it is assumed that it will be cached
 679  * all the time.
 680  */
 681 static void verity_prefetch_io(struct work_struct *work)
 682 {
 683         struct dm_verity_prefetch_work *pw =
 684                 container_of(work, struct dm_verity_prefetch_work, work);
 685         struct dm_verity *v = pw->v;
 686         int i;
 687
 688         for (i = v->levels - 2; i >= 0; i--) {
 689                 sector_t hash_block_start;
 690                 sector_t hash_block_end;
 691
 692                 verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 693                 verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 694
 695                 if (!i) {
 696                         unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 697
 698                         cluster >>= v->data_dev_block_bits;
 699                         if (unlikely(!cluster))
 700                                 goto no_prefetch_cluster;
 701
 702                         if (unlikely(cluster & (cluster - 1)))
 703                                 cluster = 1 << __fls(cluster);
 704
 705                         hash_block_start &= ~(sector_t)(cluster - 1);
 706                         hash_block_end |= cluster - 1;
 707                         if (unlikely(hash_block_end >= v->hash_blocks))
 708                                 hash_block_end = v->hash_blocks - 1;
 709                 }
 710 no_prefetch_cluster:
 711                 dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start,
 712                                         hash_block_end - hash_block_start + 1,
 713                                         pw->ioprio);
 714         }
 715
 716         kfree(pw);
 717 }
 718
 719 static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
 720                                    unsigned short ioprio)
 721 {
 722         sector_t block = io->block;
 723         unsigned int n_blocks = io->n_blocks;
 724         struct dm_verity_prefetch_work *pw;
 725
 726         if (v->validated_blocks) {
 727                 while (n_blocks && test_bit(block, v->validated_blocks)) {
 728                         block++;
 729                         n_blocks--;
 730                 }
 731                 while (n_blocks && test_bit(block + n_blocks - 1,
 732                                             v->validated_blocks))
 733                         n_blocks--;
 734                 if (!n_blocks)
 735                         return;
 736         }
 737
 738         pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 739                 GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 740
 741         if (!pw)
 742                 return;
 743
 744         INIT_WORK(&pw->work, verity_prefetch_io);
 745         pw->v = v;
 746         pw->block = block;
 747         pw->n_blocks = n_blocks;
 748         pw->ioprio = ioprio;
 749         queue_work(v->verify_wq, &pw->work);
 750 }
 751
 752 /*
 753  * Bio map function. It allocates dm_verity_io structure and bio vector and
 754  * fills them. Then it issues prefetches and the I/O.
 755  */
 756 static int verity_map(struct dm_target *ti, struct bio *bio)
 757 {
 758         struct dm_verity *v = ti->private;
 759         struct dm_verity_io *io;
 760
 761         bio_set_dev(bio, v->data_dev->bdev);
 762         bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 763
 764         if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 765             ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 766                 DMERR_LIMIT("unaligned io");
 767                 return DM_MAPIO_KILL;
 768         }
 769
 770         if (bio_end_sector(bio) >>
 771             (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 772                 DMERR_LIMIT("io out of range");
 773                 return DM_MAPIO_KILL;
 774         }
 775
 776         if (bio_data_dir(bio) == WRITE)
 777                 return DM_MAPIO_KILL;
 778
 779         io = dm_per_bio_data(bio, ti->per_io_data_size);
 780         io->v = v;
 781         io->orig_bi_end_io = bio->bi_end_io;
 782         io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 783         io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 784         io->had_mismatch = false;
 785
 786         bio->bi_end_io = verity_end_io;
 787         bio->bi_private = io;
 788         io->iter = bio->bi_iter;
 789
 790         verity_fec_init_io(io);
 791
 792         verity_submit_prefetch(v, io, bio_prio(bio));
 793
 794         submit_bio_noacct(bio);
 795
 796         return DM_MAPIO_SUBMITTED;
 797 }
 798
 799 /*
 800  * Status: V (valid) or C (corruption found)
 801  */
 802 static void verity_status(struct dm_target *ti, status_type_t type,
 803                           unsigned int status_flags, char *result, unsigned int maxlen)
 804 {
 805         struct dm_verity *v = ti->private;
 806         unsigned int args = 0;
 807         unsigned int sz = 0;
 808         unsigned int x;
 809
 810         switch (type) {
 811         case STATUSTYPE_INFO:
 812                 DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 813                 break;
 814         case STATUSTYPE_TABLE:
 815                 DMEMIT("%u %s %s %u %u %llu %llu %s ",
 816                         v->version,
 817                         v->data_dev->name,
 818                         v->hash_dev->name,
 819                         1 << v->data_dev_block_bits,
 820                         1 << v->hash_dev_block_bits,
 821                         (unsigned long long)v->data_blocks,
 822                         (unsigned long long)v->hash_start,
 823                         v->alg_name
 824                         );
 825                 for (x = 0; x < v->digest_size; x++)
 826                         DMEMIT("%02x", v->root_digest[x]);
 827                 DMEMIT(" ");
 828                 if (!v->salt_size)
 829                         DMEMIT("-");
 830                 else
 831                         for (x = 0; x < v->salt_size; x++)
 832                                 DMEMIT("%02x", v->salt[x]);
 833                 if (v->mode != DM_VERITY_MODE_EIO)
 834                         args++;
 835                 if (v->error_mode != DM_VERITY_MODE_EIO)
 836                         args++;
 837                 if (verity_fec_is_enabled(v))
 838                         args += DM_VERITY_OPTS_FEC;
 839                 if (v->zero_digest)
 840                         args++;
 841                 if (v->validated_blocks)
 842                         args++;
 843                 if (v->use_bh_wq)
 844                         args++;
 845                 if (v->signature_key_desc)
 846                         args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 847                 if (!args)
 848                         return;
 849                 DMEMIT(" %u", args);
 850                 if (v->mode != DM_VERITY_MODE_EIO) {
 851                         DMEMIT(" ");
 852                         switch (v->mode) {
 853                         case DM_VERITY_MODE_LOGGING:
 854                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 855                                 break;
 856                         case DM_VERITY_MODE_RESTART:
 857                                 DMEMIT(DM_VERITY_OPT_RESTART);
 858                                 break;
 859                         case DM_VERITY_MODE_PANIC:
 860                                 DMEMIT(DM_VERITY_OPT_PANIC);
 861                                 break;
 862                         default:
 863                                 BUG();
 864                         }
 865                 }
 866                 if (v->error_mode != DM_VERITY_MODE_EIO) {
 867                         DMEMIT(" ");
 868                         switch (v->error_mode) {
 869                         case DM_VERITY_MODE_RESTART:
 870                                 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
 871                                 break;
 872                         case DM_VERITY_MODE_PANIC:
 873                                 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
 874                                 break;
 875                         default:
 876                                 BUG();
 877                         }
 878                 }
 879                 if (v->zero_digest)
 880                         DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 881                 if (v->validated_blocks)
 882                         DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 883                 if (v->use_bh_wq)
 884                         DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 885                 sz = verity_fec_status_table(v, sz, result, maxlen);
 886                 if (v->signature_key_desc)
 887                         DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 888                                 " %s", v->signature_key_desc);
 889                 break;
 890
 891         case STATUSTYPE_IMA:
 892                 DMEMIT_TARGET_NAME_VERSION(ti->type);
 893                 DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 894                 DMEMIT(",verity_version=%u", v->version);
 895                 DMEMIT(",data_device_name=%s", v->data_dev->name);
 896                 DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 897                 DMEMIT(",verity_algorithm=%s", v->alg_name);
 898
 899                 DMEMIT(",root_digest=");
 900                 for (x = 0; x < v->digest_size; x++)
 901                         DMEMIT("%02x", v->root_digest[x]);
 902
 903                 DMEMIT(",salt=");
 904                 if (!v->salt_size)
 905                         DMEMIT("-");
 906                 else
 907                         for (x = 0; x < v->salt_size; x++)
 908                                 DMEMIT("%02x", v->salt[x]);
 909
 910                 DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 911                 DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 912                 if (v->signature_key_desc)
 913                         DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 914
 915                 if (v->mode != DM_VERITY_MODE_EIO) {
 916                         DMEMIT(",verity_mode=");
 917                         switch (v->mode) {
 918                         case DM_VERITY_MODE_LOGGING:
 919                                 DMEMIT(DM_VERITY_OPT_LOGGING);
 920                                 break;
 921                         case DM_VERITY_MODE_RESTART:
 922                                 DMEMIT(DM_VERITY_OPT_RESTART);
 923                                 break;
 924                         case DM_VERITY_MODE_PANIC:
 925                                 DMEMIT(DM_VERITY_OPT_PANIC);
 926                                 break;
 927                         default:
 928                                 DMEMIT("invalid");
 929                         }
 930                 }
 931                 if (v->error_mode != DM_VERITY_MODE_EIO) {
 932                         DMEMIT(",verity_error_mode=");
 933                         switch (v->error_mode) {
 934                         case DM_VERITY_MODE_RESTART:
 935                                 DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
 936                                 break;
 937                         case DM_VERITY_MODE_PANIC:
 938                                 DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
 939                                 break;
 940                         default:
 941                                 DMEMIT("invalid");
 942                         }
 943                 }
 944                 DMEMIT(";");
 945                 break;
 946         }
 947 }
 948
 949 static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev)
 950 {
 951         struct dm_verity *v = ti->private;
 952
 953         *bdev = v->data_dev->bdev;
 954
 955         if (ti->len != bdev_nr_sectors(v->data_dev->bdev))
 956                 return 1;
 957         return 0;
 958 }
 959
 960 static int verity_iterate_devices(struct dm_target *ti,
 961                                   iterate_devices_callout_fn fn, void *data)
 962 {
 963         struct dm_verity *v = ti->private;
 964
 965         return fn(ti, v->data_dev, 0, ti->len, data);
 966 }
 967
 968 static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 969 {
 970         struct dm_verity *v = ti->private;
 971
 972         if (limits->logical_block_size < 1 << v->data_dev_block_bits)
 973                 limits->logical_block_size = 1 << v->data_dev_block_bits;
 974
 975         if (limits->physical_block_size < 1 << v->data_dev_block_bits)
 976                 limits->physical_block_size = 1 << v->data_dev_block_bits;
 977
 978         limits->io_min = limits->logical_block_size;
 979
 980         /*
 981          * Similar to what dm-crypt does, opt dm-verity out of support for
 982          * direct I/O that is aligned to less than the traditional direct I/O
 983          * alignment requirement of logical_block_size.  This prevents dm-verity
 984          * data blocks from crossing pages, eliminating various edge cases.
 985          */
 986         limits->dma_alignment = limits->logical_block_size - 1;
 987 }
 988
 989 #ifdef CONFIG_SECURITY
 990
 991 static int verity_init_sig(struct dm_verity *v, const void *sig,
 992                            size_t sig_size)
 993 {
 994         v->sig_size = sig_size;
 995
 996         if (sig) {
 997                 v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL);
 998                 if (!v->root_digest_sig)
 999                         return -ENOMEM;
1000         }
1001
1002         return 0;
1003 }
1004
1005 static void verity_free_sig(struct dm_verity *v)
1006 {
1007         kfree(v->root_digest_sig);
1008 }
1009
1010 #else
1011
1012 static inline int verity_init_sig(struct dm_verity *v, const void *sig,
1013                                   size_t sig_size)
1014 {
1015         return 0;
1016 }
1017
1018 static inline void verity_free_sig(struct dm_verity *v)
1019 {
1020 }
1021
1022 #endif /* CONFIG_SECURITY */
1023
1024 static void verity_dtr(struct dm_target *ti)
1025 {
1026         struct dm_verity *v = ti->private;
1027
1028         if (v->verify_wq)
1029                 destroy_workqueue(v->verify_wq);
1030
1031         mempool_exit(&v->recheck_pool);
1032         if (v->io)
1033                 dm_io_client_destroy(v->io);
1034
1035         if (v->bufio)
1036                 dm_bufio_client_destroy(v->bufio);
1037
1038         kvfree(v->validated_blocks);
1039         kfree(v->salt);
1040         kfree(v->initial_hashstate);
1041         kfree(v->root_digest);
1042         kfree(v->zero_digest);
1043         verity_free_sig(v);
1044
1045         if (v->ahash_tfm) {
1046                 static_branch_dec(&ahash_enabled);
1047                 crypto_free_ahash(v->ahash_tfm);
1048         } else {
1049                 crypto_free_shash(v->shash_tfm);
1050         }
1051
1052         kfree(v->alg_name);
1053
1054         if (v->hash_dev)
1055                 dm_put_device(ti, v->hash_dev);
1056
1057         if (v->data_dev)
1058                 dm_put_device(ti, v->data_dev);
1059
1060         verity_fec_dtr(v);
1061
1062         kfree(v->signature_key_desc);
1063
1064         if (v->use_bh_wq)
1065                 static_branch_dec(&use_bh_wq_enabled);
1066
1067         kfree(v);
1068
1069         dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1070 }
1071
1072 static int verity_alloc_most_once(struct dm_verity *v)
1073 {
1074         struct dm_target *ti = v->ti;
1075
1076         /* the bitset can only handle INT_MAX blocks */
1077         if (v->data_blocks > INT_MAX) {
1078                 ti->error = "device too large to use check_at_most_once";
1079                 return -E2BIG;
1080         }
1081
1082         v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1083                                        sizeof(unsigned long),
1084                                        GFP_KERNEL);
1085         if (!v->validated_blocks) {
1086                 ti->error = "failed to allocate bitset for check_at_most_once";
1087                 return -ENOMEM;
1088         }
1089
1090         return 0;
1091 }
1092
1093 static int verity_alloc_zero_digest(struct dm_verity *v)
1094 {
1095         int r = -ENOMEM;
1096         struct dm_verity_io *io;
1097         u8 *zero_data;
1098
1099         v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1100
1101         if (!v->zero_digest)
1102                 return r;
1103
1104         io = kmalloc(sizeof(*io) + v->hash_reqsize, GFP_KERNEL);
1105
1106         if (!io)
1107                 return r; /* verity_dtr will free zero_digest */
1108
1109         zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1110
1111         if (!zero_data)
1112                 goto out;
1113
1114         r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits,
1115                         v->zero_digest, true);
1116
1117 out:
1118         kfree(io);
1119         kfree(zero_data);
1120
1121         return r;
1122 }
1123
1124 static inline bool verity_is_verity_mode(const char *arg_name)
1125 {
1126         return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1127                 !strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1128                 !strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1129 }
1130
1131 static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1132 {
1133         if (v->mode)
1134                 return -EINVAL;
1135
1136         if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1137                 v->mode = DM_VERITY_MODE_LOGGING;
1138         else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1139                 v->mode = DM_VERITY_MODE_RESTART;
1140         else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1141                 v->mode = DM_VERITY_MODE_PANIC;
1142
1143         return 0;
1144 }
1145
1146 static inline bool verity_is_verity_error_mode(const char *arg_name)
1147 {
1148         return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) ||
1149                 !strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC));
1150 }
1151
1152 static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name)
1153 {
1154         if (v->error_mode)
1155                 return -EINVAL;
1156
1157         if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART))
1158                 v->error_mode = DM_VERITY_MODE_RESTART;
1159         else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC))
1160                 v->error_mode = DM_VERITY_MODE_PANIC;
1161
1162         return 0;
1163 }
1164
1165 static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1166                                  struct dm_verity_sig_opts *verify_args,
1167                                  bool only_modifier_opts)
1168 {
1169         int r = 0;
1170         unsigned int argc;
1171         struct dm_target *ti = v->ti;
1172         const char *arg_name;
1173
1174         static const struct dm_arg _args[] = {
1175                 {0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1176         };
1177
1178         r = dm_read_arg_group(_args, as, &argc, &ti->error);
1179         if (r)
1180                 return -EINVAL;
1181
1182         if (!argc)
1183                 return 0;
1184
1185         do {
1186                 arg_name = dm_shift_arg(as);
1187                 argc--;
1188
1189                 if (verity_is_verity_mode(arg_name)) {
1190                         if (only_modifier_opts)
1191                                 continue;
1192                         r = verity_parse_verity_mode(v, arg_name);
1193                         if (r) {
1194                                 ti->error = "Conflicting error handling parameters";
1195                                 return r;
1196                         }
1197                         continue;
1198
1199                 } else if (verity_is_verity_error_mode(arg_name)) {
1200                         if (only_modifier_opts)
1201                                 continue;
1202                         r = verity_parse_verity_error_mode(v, arg_name);
1203                         if (r) {
1204                                 ti->error = "Conflicting error handling parameters";
1205                                 return r;
1206                         }
1207                         continue;
1208
1209                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1210                         if (only_modifier_opts)
1211                                 continue;
1212                         r = verity_alloc_zero_digest(v);
1213                         if (r) {
1214                                 ti->error = "Cannot allocate zero digest";
1215                                 return r;
1216                         }
1217                         continue;
1218
1219                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1220                         if (only_modifier_opts)
1221                                 continue;
1222                         r = verity_alloc_most_once(v);
1223                         if (r)
1224                                 return r;
1225                         continue;
1226
1227                 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1228                         v->use_bh_wq = true;
1229                         static_branch_inc(&use_bh_wq_enabled);
1230                         continue;
1231
1232                 } else if (verity_is_fec_opt_arg(arg_name)) {
1233                         if (only_modifier_opts)
1234                                 continue;
1235                         r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1236                         if (r)
1237                                 return r;
1238                         continue;
1239
1240                 } else if (verity_verify_is_sig_opt_arg(arg_name)) {
1241                         if (only_modifier_opts)
1242                                 continue;
1243                         r = verity_verify_sig_parse_opt_args(as, v,
1244                                                              verify_args,
1245                                                              &argc, arg_name);
1246                         if (r)
1247                                 return r;
1248                         continue;
1249
1250                 } else if (only_modifier_opts) {
1251                         /*
1252                          * Ignore unrecognized opt, could easily be an extra
1253                          * argument to an option whose parsing was skipped.
1254                          * Normal parsing (@only_modifier_opts=false) will
1255                          * properly parse all options (and their extra args).
1256                          */
1257                         continue;
1258                 }
1259
1260                 DMERR("Unrecognized verity feature request: %s", arg_name);
1261                 ti->error = "Unrecognized verity feature request";
1262                 return -EINVAL;
1263         } while (argc && !r);
1264
1265         return r;
1266 }
1267
1268 static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name)
1269 {
1270         struct dm_target *ti = v->ti;
1271         struct crypto_ahash *ahash;
1272         struct crypto_shash *shash = NULL;
1273         const char *driver_name;
1274
1275         v->alg_name = kstrdup(alg_name, GFP_KERNEL);
1276         if (!v->alg_name) {
1277                 ti->error = "Cannot allocate algorithm name";
1278                 return -ENOMEM;
1279         }
1280
1281         /*
1282          * Allocate the hash transformation object that this dm-verity instance
1283          * will use.  The vast majority of dm-verity users use CPU-based
1284          * hashing, so when possible use the shash API to minimize the crypto
1285          * API overhead.  If the ahash API resolves to a different driver
1286          * (likely an off-CPU hardware offload), use ahash instead.  Also use
1287          * ahash if the obsolete dm-verity format with the appended salt is
1288          * being used, so that quirk only needs to be handled in one place.
1289          */
1290         ahash = crypto_alloc_ahash(alg_name, 0,
1291                                    v->use_bh_wq ? CRYPTO_ALG_ASYNC : 0);
1292         if (IS_ERR(ahash)) {
1293                 ti->error = "Cannot initialize hash function";
1294                 return PTR_ERR(ahash);
1295         }
1296         driver_name = crypto_ahash_driver_name(ahash);
1297         if (v->version >= 1 /* salt prepended, not appended? */) {
1298                 shash = crypto_alloc_shash(alg_name, 0, 0);
1299                 if (!IS_ERR(shash) &&
1300                     strcmp(crypto_shash_driver_name(shash), driver_name) != 0) {
1301                         /*
1302                          * ahash gave a different driver than shash, so probably
1303                          * this is a case of real hardware offload.  Use ahash.
1304                          */
1305                         crypto_free_shash(shash);
1306                         shash = NULL;
1307                 }
1308         }
1309         if (!IS_ERR_OR_NULL(shash)) {
1310                 crypto_free_ahash(ahash);
1311                 ahash = NULL;
1312                 v->shash_tfm = shash;
1313                 v->digest_size = crypto_shash_digestsize(shash);
1314                 v->hash_reqsize = sizeof(struct shash_desc) +
1315                                   crypto_shash_descsize(shash);
1316                 DMINFO("%s using shash \"%s\"", alg_name, driver_name);
1317         } else {
1318                 v->ahash_tfm = ahash;
1319                 static_branch_inc(&ahash_enabled);
1320                 v->digest_size = crypto_ahash_digestsize(ahash);
1321                 v->hash_reqsize = sizeof(struct ahash_request) +
1322                                   crypto_ahash_reqsize(ahash);
1323                 DMINFO("%s using ahash \"%s\"", alg_name, driver_name);
1324         }
1325         if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1326                 ti->error = "Digest size too big";
1327                 return -EINVAL;
1328         }
1329         return 0;
1330 }
1331
1332 static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg)
1333 {
1334         struct dm_target *ti = v->ti;
1335
1336         if (strcmp(arg, "-") != 0) {
1337                 v->salt_size = strlen(arg) / 2;
1338                 v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1339                 if (!v->salt) {
1340                         ti->error = "Cannot allocate salt";
1341                         return -ENOMEM;
1342                 }
1343                 if (strlen(arg) != v->salt_size * 2 ||
1344                     hex2bin(v->salt, arg, v->salt_size)) {
1345                         ti->error = "Invalid salt";
1346                         return -EINVAL;
1347                 }
1348         }
1349         if (v->shash_tfm) {
1350                 SHASH_DESC_ON_STACK(desc, v->shash_tfm);
1351                 int r;
1352
1353                 /*
1354                  * Compute the pre-salted hash state that can be passed to
1355                  * crypto_shash_import() for each block later.
1356                  */
1357                 v->initial_hashstate = kmalloc(
1358                         crypto_shash_statesize(v->shash_tfm), GFP_KERNEL);
1359                 if (!v->initial_hashstate) {
1360                         ti->error = "Cannot allocate initial hash state";
1361                         return -ENOMEM;
1362                 }
1363                 desc->tfm = v->shash_tfm;
1364                 r = crypto_shash_init(desc) ?:
1365                     crypto_shash_update(desc, v->salt, v->salt_size) ?:
1366                     crypto_shash_export(desc, v->initial_hashstate);
1367                 if (r) {
1368                         ti->error = "Cannot set up initial hash state";
1369                         return r;
1370                 }
1371         }
1372         return 0;
1373 }
1374
1375 /*
1376  * Target parameters:
1377  *      <version>       The current format is version 1.
1378  *                      Vsn 0 is compatible with original Chromium OS releases.
1379  *      <data device>
1380  *      <hash device>
1381  *      <data block size>
1382  *      <hash block size>
1383  *      <the number of data blocks>
1384  *      <hash start block>
1385  *      <algorithm>
1386  *      <digest>
1387  *      <salt>          Hex string or "-" if no salt.
1388  */
1389 static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1390 {
1391         struct dm_verity *v;
1392         struct dm_verity_sig_opts verify_args = {0};
1393         struct dm_arg_set as;
1394         unsigned int num;
1395         unsigned long long num_ll;
1396         int r;
1397         int i;
1398         sector_t hash_position;
1399         char dummy;
1400         char *root_hash_digest_to_validate;
1401
1402         v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1403         if (!v) {
1404                 ti->error = "Cannot allocate verity structure";
1405                 return -ENOMEM;
1406         }
1407         ti->private = v;
1408         v->ti = ti;
1409
1410         r = verity_fec_ctr_alloc(v);
1411         if (r)
1412                 goto bad;
1413
1414         if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1415                 ti->error = "Device must be readonly";
1416                 r = -EINVAL;
1417                 goto bad;
1418         }
1419
1420         if (argc < 10) {
1421                 ti->error = "Not enough arguments";
1422                 r = -EINVAL;
1423                 goto bad;
1424         }
1425
1426         /* Parse optional parameters that modify primary args */
1427         if (argc > 10) {
1428                 as.argc = argc - 10;
1429                 as.argv = argv + 10;
1430                 r = verity_parse_opt_args(&as, v, &verify_args, true);
1431                 if (r < 0)
1432                         goto bad;
1433         }
1434
1435         if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1436             num > 1) {
1437                 ti->error = "Invalid version";
1438                 r = -EINVAL;
1439                 goto bad;
1440         }
1441         v->version = num;
1442
1443         r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1444         if (r) {
1445                 ti->error = "Data device lookup failed";
1446                 goto bad;
1447         }
1448
1449         r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1450         if (r) {
1451                 ti->error = "Hash device lookup failed";
1452                 goto bad;
1453         }
1454
1455         if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1456             !num || (num & (num - 1)) ||
1457             num < bdev_logical_block_size(v->data_dev->bdev) ||
1458             num > PAGE_SIZE) {
1459                 ti->error = "Invalid data device block size";
1460                 r = -EINVAL;
1461                 goto bad;
1462         }
1463         v->data_dev_block_bits = __ffs(num);
1464
1465         if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1466             !num || (num & (num - 1)) ||
1467             num < bdev_logical_block_size(v->hash_dev->bdev) ||
1468             num > INT_MAX) {
1469                 ti->error = "Invalid hash device block size";
1470                 r = -EINVAL;
1471                 goto bad;
1472         }
1473         v->hash_dev_block_bits = __ffs(num);
1474
1475         if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1476             (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1477             >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1478                 ti->error = "Invalid data blocks";
1479                 r = -EINVAL;
1480                 goto bad;
1481         }
1482         v->data_blocks = num_ll;
1483
1484         if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1485                 ti->error = "Data device is too small";
1486                 r = -EINVAL;
1487                 goto bad;
1488         }
1489
1490         if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1491             (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1492             >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1493                 ti->error = "Invalid hash start";
1494                 r = -EINVAL;
1495                 goto bad;
1496         }
1497         v->hash_start = num_ll;
1498
1499         r = verity_setup_hash_alg(v, argv[7]);
1500         if (r)
1501                 goto bad;
1502
1503         v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1504         if (!v->root_digest) {
1505                 ti->error = "Cannot allocate root digest";
1506                 r = -ENOMEM;
1507                 goto bad;
1508         }
1509         if (strlen(argv[8]) != v->digest_size * 2 ||
1510             hex2bin(v->root_digest, argv[8], v->digest_size)) {
1511                 ti->error = "Invalid root digest";
1512                 r = -EINVAL;
1513                 goto bad;
1514         }
1515         root_hash_digest_to_validate = argv[8];
1516
1517         r = verity_setup_salt_and_hashstate(v, argv[9]);
1518         if (r)
1519                 goto bad;
1520
1521         argv += 10;
1522         argc -= 10;
1523
1524         /* Optional parameters */
1525         if (argc) {
1526                 as.argc = argc;
1527                 as.argv = argv;
1528                 r = verity_parse_opt_args(&as, v, &verify_args, false);
1529                 if (r < 0)
1530                         goto bad;
1531         }
1532
1533         /* Root hash signature is  a optional parameter*/
1534         r = verity_verify_root_hash(root_hash_digest_to_validate,
1535                                     strlen(root_hash_digest_to_validate),
1536                                     verify_args.sig,
1537                                     verify_args.sig_size);
1538         if (r < 0) {
1539                 ti->error = "Root hash verification failed";
1540                 goto bad;
1541         }
1542
1543         r = verity_init_sig(v, verify_args.sig, verify_args.sig_size);
1544         if (r < 0) {
1545                 ti->error = "Cannot allocate root digest signature";
1546                 goto bad;
1547         }
1548
1549         v->hash_per_block_bits =
1550                 __fls((1 << v->hash_dev_block_bits) / v->digest_size);
1551
1552         v->levels = 0;
1553         if (v->data_blocks)
1554                 while (v->hash_per_block_bits * v->levels < 64 &&
1555                        (unsigned long long)(v->data_blocks - 1) >>
1556                        (v->hash_per_block_bits * v->levels))
1557                         v->levels++;
1558
1559         if (v->levels > DM_VERITY_MAX_LEVELS) {
1560                 ti->error = "Too many tree levels";
1561                 r = -E2BIG;
1562                 goto bad;
1563         }
1564
1565         hash_position = v->hash_start;
1566         for (i = v->levels - 1; i >= 0; i--) {
1567                 sector_t s;
1568
1569                 v->hash_level_block[i] = hash_position;
1570                 s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1571                                         >> ((i + 1) * v->hash_per_block_bits);
1572                 if (hash_position + s < hash_position) {
1573                         ti->error = "Hash device offset overflow";
1574                         r = -E2BIG;
1575                         goto bad;
1576                 }
1577                 hash_position += s;
1578         }
1579         v->hash_blocks = hash_position;
1580
1581         r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1582         if (unlikely(r)) {
1583                 ti->error = "Cannot allocate mempool";
1584                 goto bad;
1585         }
1586
1587         v->io = dm_io_client_create();
1588         if (IS_ERR(v->io)) {
1589                 r = PTR_ERR(v->io);
1590                 v->io = NULL;
1591                 ti->error = "Cannot allocate dm io";
1592                 goto bad;
1593         }
1594
1595         v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1596                 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1597                 dm_bufio_alloc_callback, NULL,
1598                 v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1599         if (IS_ERR(v->bufio)) {
1600                 ti->error = "Cannot initialize dm-bufio";
1601                 r = PTR_ERR(v->bufio);
1602                 v->bufio = NULL;
1603                 goto bad;
1604         }
1605
1606         if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1607                 ti->error = "Hash device is too small";
1608                 r = -E2BIG;
1609                 goto bad;
1610         }
1611
1612         /*
1613          * Using WQ_HIGHPRI improves throughput and completion latency by
1614          * reducing wait times when reading from a dm-verity device.
1615          *
1616          * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1617          * allows verify_wq to preempt softirq since verification in BH workqueue
1618          * will fall-back to using it for error handling (or if the bufio cache
1619          * doesn't have required hashes).
1620          */
1621         v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1622         if (!v->verify_wq) {
1623                 ti->error = "Cannot allocate workqueue";
1624                 r = -ENOMEM;
1625                 goto bad;
1626         }
1627
1628         ti->per_io_data_size = sizeof(struct dm_verity_io) + v->hash_reqsize;
1629
1630         r = verity_fec_ctr(v);
1631         if (r)
1632                 goto bad;
1633
1634         ti->per_io_data_size = roundup(ti->per_io_data_size,
1635                                        __alignof__(struct dm_verity_io));
1636
1637         verity_verify_sig_opts_cleanup(&verify_args);
1638
1639         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1640
1641         return 0;
1642
1643 bad:
1644
1645         verity_verify_sig_opts_cleanup(&verify_args);
1646         dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1647         verity_dtr(ti);
1648
1649         return r;
1650 }
1651
1652 /*
1653  * Get the verity mode (error behavior) of a verity target.
1654  *
1655  * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1656  * target.
1657  */
1658 int dm_verity_get_mode(struct dm_target *ti)
1659 {
1660         struct dm_verity *v = ti->private;
1661
1662         if (!dm_is_verity_target(ti))
1663                 return -EINVAL;
1664
1665         return v->mode;
1666 }
1667
1668 /*
1669  * Get the root digest of a verity target.
1670  *
1671  * Returns a copy of the root digest, the caller is responsible for
1672  * freeing the memory of the digest.
1673  */
1674 int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1675 {
1676         struct dm_verity *v = ti->private;
1677
1678         if (!dm_is_verity_target(ti))
1679                 return -EINVAL;
1680
1681         *root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1682         if (*root_digest == NULL)
1683                 return -ENOMEM;
1684
1685         *digest_size = v->digest_size;
1686
1687         return 0;
1688 }
1689
1690 #ifdef CONFIG_SECURITY
1691
1692 #ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG
1693
1694 static int verity_security_set_signature(struct block_device *bdev,
1695                                          struct dm_verity *v)
1696 {
1697         /*
1698          * if the dm-verity target is unsigned, v->root_digest_sig will
1699          * be NULL, and the hook call is still required to let LSMs mark
1700          * the device as unsigned. This information is crucial for LSMs to
1701          * block operations such as execution on unsigned files
1702          */
1703         return security_bdev_setintegrity(bdev,
1704                                           LSM_INT_DMVERITY_SIG_VALID,
1705                                           v->root_digest_sig,
1706                                           v->sig_size);
1707 }
1708
1709 #else
1710
1711 static inline int verity_security_set_signature(struct block_device *bdev,
1712                                                 struct dm_verity *v)
1713 {
1714         return 0;
1715 }
1716
1717 #endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */
1718
1719 /*
1720  * Expose verity target's root hash and signature data to LSMs before resume.
1721  *
1722  * Returns 0 on success, or -ENOMEM if the system is out of memory.
1723  */
1724 static int verity_preresume(struct dm_target *ti)
1725 {
1726         struct block_device *bdev;
1727         struct dm_verity_digest root_digest;
1728         struct dm_verity *v;
1729         int r;
1730
1731         v = ti->private;
1732         bdev = dm_disk(dm_table_get_md(ti->table))->part0;
1733         root_digest.digest = v->root_digest;
1734         root_digest.digest_len = v->digest_size;
1735         if (static_branch_unlikely(&ahash_enabled) && !v->shash_tfm)
1736                 root_digest.alg = crypto_ahash_alg_name(v->ahash_tfm);
1737         else
1738                 root_digest.alg = crypto_shash_alg_name(v->shash_tfm);
1739
1740         r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest,
1741                                        sizeof(root_digest));
1742         if (r)
1743                 return r;
1744
1745         r =  verity_security_set_signature(bdev, v);
1746         if (r)
1747                 goto bad;
1748
1749         return 0;
1750
1751 bad:
1752
1753         security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0);
1754
1755         return r;
1756 }
1757
1758 #endif /* CONFIG_SECURITY */
1759
1760 static struct target_type verity_target = {
1761         .name           = "verity",
1762 /* Note: the LSMs depend on the singleton and immutable features */
1763         .features       = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1764         .version        = {1, 10, 0},
1765         .module         = THIS_MODULE,
1766         .ctr            = verity_ctr,
1767         .dtr            = verity_dtr,
1768         .map            = verity_map,
1769         .status         = verity_status,
1770         .prepare_ioctl  = verity_prepare_ioctl,
1771         .iterate_devices = verity_iterate_devices,
1772         .io_hints       = verity_io_hints,
1773 #ifdef CONFIG_SECURITY
1774         .preresume      = verity_preresume,
1775 #endif /* CONFIG_SECURITY */
1776 };
1777 module_dm(verity);
1778
1779 /*
1780  * Check whether a DM target is a verity target.
1781  */
1782 bool dm_is_verity_target(struct dm_target *ti)
1783 {
1784         return ti->type == &verity_target;
1785 }
1786
1787 MODULE_AUTHOR("Mikulas Patocka <[email protected]>");
1788 MODULE_AUTHOR("Mandeep Baines <[email protected]>");
1789 MODULE_AUTHOR("Will Drewry <[email protected]>");
1790 MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1791 MODULE_LICENSE("GPL");