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 <mpatocka@redhat.com>
   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/string.h>
  23#include <linux/jump_label.h>
  24#include <linux/security.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#define DM_VERITY_USE_BH_DEFAULT_BYTES	8192
  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
  48static unsigned int dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE;
  49
  50module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, 0644);
  51
  52static unsigned int dm_verity_use_bh_bytes[4] = {
  53	DM_VERITY_USE_BH_DEFAULT_BYTES,	// IOPRIO_CLASS_NONE
  54	DM_VERITY_USE_BH_DEFAULT_BYTES,	// IOPRIO_CLASS_RT
  55	DM_VERITY_USE_BH_DEFAULT_BYTES,	// IOPRIO_CLASS_BE
  56	0				// IOPRIO_CLASS_IDLE
  57};
  58
  59module_param_array_named(use_bh_bytes, dm_verity_use_bh_bytes, uint, NULL, 0644);
  60
  61static DEFINE_STATIC_KEY_FALSE(use_bh_wq_enabled);
  62
  63struct dm_verity_prefetch_work {
  64	struct work_struct work;
  65	struct dm_verity *v;
  66	unsigned short ioprio;
  67	sector_t block;
  68	unsigned int n_blocks;
  69};
  70
  71/*
  72 * Auxiliary structure appended to each dm-bufio buffer. If the value
  73 * hash_verified is nonzero, hash of the block has been verified.
  74 *
  75 * The variable hash_verified is set to 0 when allocating the buffer, then
  76 * it can be changed to 1 and it is never reset to 0 again.
  77 *
  78 * There is no lock around this value, a race condition can at worst cause
  79 * that multiple processes verify the hash of the same buffer simultaneously
  80 * and write 1 to hash_verified simultaneously.
  81 * This condition is harmless, so we don't need locking.
  82 */
  83struct buffer_aux {
  84	int hash_verified;
  85};
  86
  87/*
  88 * Initialize struct buffer_aux for a freshly created buffer.
  89 */
  90static void dm_bufio_alloc_callback(struct dm_buffer *buf)
  91{
  92	struct buffer_aux *aux = dm_bufio_get_aux_data(buf);
  93
  94	aux->hash_verified = 0;
  95}
  96
  97/*
  98 * Translate input sector number to the sector number on the target device.
  99 */
 100static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector)
 101{
 102	return dm_target_offset(v->ti, bi_sector);
 103}
 104
 105/*
 106 * Return hash position of a specified block at a specified tree level
 107 * (0 is the lowest level).
 108 * The lowest "hash_per_block_bits"-bits of the result denote hash position
 109 * inside a hash block. The remaining bits denote location of the hash block.
 110 */
 111static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
 112					 int level)
 113{
 114	return block >> (level * v->hash_per_block_bits);
 115}
 116
 117int verity_hash(struct dm_verity *v, struct dm_verity_io *io,
 118		const u8 *data, size_t len, u8 *digest)
 119{
 120	struct shash_desc *desc;
 121	int r;
 122
 123	if (likely(v->use_sha256_lib)) {
 124		struct sha256_ctx *ctx = &io->hash_ctx.sha256;
 125
 126		/*
 127		 * Fast path using SHA-256 library.  This is enabled only for
 128		 * verity version 1, where the salt is at the beginning.
 129		 */
 130		*ctx = *v->initial_hashstate.sha256;
 131		sha256_update(ctx, data, len);
 132		sha256_final(ctx, digest);
 133		return 0;
 134	}
 135
 136	desc = &io->hash_ctx.shash;
 137	desc->tfm = v->shash_tfm;
 138	if (unlikely(v->initial_hashstate.shash == NULL)) {
 139		/* Version 0: salt at end */
 140		r = crypto_shash_init(desc) ?:
 141		    crypto_shash_update(desc, data, len) ?:
 142		    crypto_shash_update(desc, v->salt, v->salt_size) ?:
 143		    crypto_shash_final(desc, digest);
 144	} else {
 145		/* Version 1: salt at beginning */
 146		r = crypto_shash_import(desc, v->initial_hashstate.shash) ?:
 147		    crypto_shash_finup(desc, data, len, digest);
 148	}
 149	if (unlikely(r))
 150		DMERR("Error hashing block: %d", r);
 151	return r;
 152}
 153
 154static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
 155				 sector_t *hash_block, unsigned int *offset)
 156{
 157	sector_t position = verity_position_at_level(v, block, level);
 158	unsigned int idx;
 159
 160	*hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits);
 161
 162	if (!offset)
 163		return;
 164
 165	idx = position & ((1 << v->hash_per_block_bits) - 1);
 166	if (!v->version)
 167		*offset = idx * v->digest_size;
 168	else
 169		*offset = idx << (v->hash_dev_block_bits - v->hash_per_block_bits);
 170}
 171
 172/*
 173 * Handle verification errors.
 174 */
 175static int verity_handle_err(struct dm_verity *v, enum verity_block_type type,
 176			     unsigned long long block)
 177{
 178	char verity_env[DM_VERITY_ENV_LENGTH];
 179	char *envp[] = { verity_env, NULL };
 180	const char *type_str = "";
 181	struct mapped_device *md = dm_table_get_md(v->ti->table);
 182
 183	/* Corruption should be visible in device status in all modes */
 184	v->hash_failed = true;
 185
 186	if (v->corrupted_errs >= DM_VERITY_MAX_CORRUPTED_ERRS)
 187		goto out;
 188
 189	v->corrupted_errs++;
 190
 191	switch (type) {
 192	case DM_VERITY_BLOCK_TYPE_DATA:
 193		type_str = "data";
 194		break;
 195	case DM_VERITY_BLOCK_TYPE_METADATA:
 196		type_str = "metadata";
 197		break;
 198	default:
 199		BUG();
 200	}
 201
 202	DMERR_LIMIT("%s: %s block %llu is corrupted", v->data_dev->name,
 203		    type_str, block);
 204
 205	if (v->corrupted_errs == DM_VERITY_MAX_CORRUPTED_ERRS) {
 206		DMERR("%s: reached maximum errors", v->data_dev->name);
 207		dm_audit_log_target(DM_MSG_PREFIX, "max-corrupted-errors", v->ti, 0);
 208	}
 209
 210	snprintf(verity_env, DM_VERITY_ENV_LENGTH, "%s=%d,%llu",
 211		DM_VERITY_ENV_VAR_NAME, type, block);
 212
 213	kobject_uevent_env(&disk_to_dev(dm_disk(md))->kobj, KOBJ_CHANGE, envp);
 214
 215out:
 216	if (v->mode == DM_VERITY_MODE_LOGGING)
 217		return 0;
 218
 219	if (v->mode == DM_VERITY_MODE_RESTART)
 220		kernel_restart("dm-verity device corrupted");
 221
 222	if (v->mode == DM_VERITY_MODE_PANIC)
 223		panic("dm-verity device corrupted");
 224
 225	return 1;
 226}
 227
 228/*
 229 * Verify hash of a metadata block pertaining to the specified data block
 230 * ("block" argument) at a specified level ("level" argument).
 231 *
 232 * On successful return, want_digest contains the hash value for a lower tree
 233 * level or for the data block (if we're at the lowest level).
 234 *
 235 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.
 236 * If "skip_unverified" is false, unverified buffer is hashed and verified
 237 * against current value of want_digest.
 238 */
 239static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
 240			       sector_t block, int level, bool skip_unverified,
 241			       u8 *want_digest)
 242{
 243	struct dm_buffer *buf;
 244	struct buffer_aux *aux;
 245	u8 *data;
 246	int r;
 247	sector_t hash_block;
 248	unsigned int offset;
 249	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 250
 251	verity_hash_at_level(v, block, level, &hash_block, &offset);
 252
 253	if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 254		data = dm_bufio_get(v->bufio, hash_block, &buf);
 255		if (IS_ERR_OR_NULL(data)) {
 256			/*
 257			 * In tasklet and the hash was not in the bufio cache.
 258			 * Return early and resume execution from a work-queue
 259			 * to read the hash from disk.
 260			 */
 261			return -EAGAIN;
 262		}
 263	} else {
 264		data = dm_bufio_read_with_ioprio(v->bufio, hash_block,
 265						&buf, bio->bi_ioprio);
 266	}
 267
 268	if (IS_ERR(data)) {
 269		if (skip_unverified)
 270			return 1;
 271		r = PTR_ERR(data);
 272		data = dm_bufio_new(v->bufio, hash_block, &buf);
 273		if (IS_ERR(data))
 274			return r;
 275		if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 276				      want_digest, hash_block, data) == 0) {
 277			aux = dm_bufio_get_aux_data(buf);
 278			aux->hash_verified = 1;
 279			goto release_ok;
 280		} else {
 281			dm_bufio_release(buf);
 282			dm_bufio_forget(v->bufio, hash_block);
 283			return r;
 284		}
 285	}
 286
 287	aux = dm_bufio_get_aux_data(buf);
 288
 289	if (!aux->hash_verified) {
 290		if (skip_unverified) {
 291			r = 1;
 292			goto release_ret_r;
 293		}
 294
 295		r = verity_hash(v, io, data, 1 << v->hash_dev_block_bits,
 296				io->tmp_digest);
 297		if (unlikely(r < 0))
 298			goto release_ret_r;
 299
 300		if (likely(memcmp(io->tmp_digest, want_digest,
 301				  v->digest_size) == 0))
 302			aux->hash_verified = 1;
 303		else if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 304			/*
 305			 * Error handling code (FEC included) cannot be run in a
 306			 * tasklet since it may sleep, so fallback to work-queue.
 307			 */
 308			r = -EAGAIN;
 309			goto release_ret_r;
 310		} else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
 311					     want_digest, hash_block, data) == 0)
 312			aux->hash_verified = 1;
 313		else if (verity_handle_err(v,
 314					   DM_VERITY_BLOCK_TYPE_METADATA,
 315					   hash_block)) {
 316			struct bio *bio;
 317			io->had_mismatch = true;
 318			bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 319			dm_audit_log_bio(DM_MSG_PREFIX, "verify-metadata", bio,
 320					 block, 0);
 321			r = -EIO;
 322			goto release_ret_r;
 323		}
 324	}
 325
 326release_ok:
 327	data += offset;
 328	memcpy(want_digest, data, v->digest_size);
 329	r = 0;
 330
 331release_ret_r:
 332	dm_bufio_release(buf);
 333	return r;
 334}
 335
 336/*
 337 * Find a hash for a given block, write it to digest and verify the integrity
 338 * of the hash tree if necessary.
 339 */
 340int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 341			  sector_t block, u8 *digest, bool *is_zero)
 342{
 343	int r = 0, i;
 344
 345	if (likely(v->levels)) {
 346		/*
 347		 * First, we try to get the requested hash for
 348		 * the current block. If the hash block itself is
 349		 * verified, zero is returned. If it isn't, this
 350		 * function returns 1 and we fall back to whole
 351		 * chain verification.
 352		 */
 353		r = verity_verify_level(v, io, block, 0, true, digest);
 354		if (likely(r <= 0))
 355			goto out;
 356	}
 357
 358	memcpy(digest, v->root_digest, v->digest_size);
 359
 360	for (i = v->levels - 1; i >= 0; i--) {
 361		r = verity_verify_level(v, io, block, i, false, digest);
 362		if (unlikely(r))
 363			goto out;
 364	}
 365out:
 366	if (!r && v->zero_digest)
 367		*is_zero = !memcmp(v->zero_digest, digest, v->digest_size);
 368	else
 369		*is_zero = false;
 370
 371	return r;
 372}
 373
 374static noinline int verity_recheck(struct dm_verity *v, struct dm_verity_io *io,
 375				   const u8 *want_digest, sector_t cur_block,
 376				   u8 *dest)
 377{
 378	struct page *page;
 379	void *buffer;
 380	int r;
 381	struct dm_io_request io_req;
 382	struct dm_io_region io_loc;
 383
 384	page = mempool_alloc(&v->recheck_pool, GFP_NOIO);
 385	buffer = page_to_virt(page);
 386
 387	io_req.bi_opf = REQ_OP_READ;
 388	io_req.mem.type = DM_IO_KMEM;
 389	io_req.mem.ptr.addr = buffer;
 390	io_req.notify.fn = NULL;
 391	io_req.client = v->io;
 392	io_loc.bdev = v->data_dev->bdev;
 393	io_loc.sector = cur_block << (v->data_dev_block_bits - SECTOR_SHIFT);
 394	io_loc.count = 1 << (v->data_dev_block_bits - SECTOR_SHIFT);
 395	r = dm_io(&io_req, 1, &io_loc, NULL, IOPRIO_DEFAULT);
 396	if (unlikely(r))
 397		goto free_ret;
 398
 399	r = verity_hash(v, io, buffer, 1 << v->data_dev_block_bits,
 400			io->tmp_digest);
 401	if (unlikely(r))
 402		goto free_ret;
 403
 404	if (memcmp(io->tmp_digest, want_digest, v->digest_size)) {
 405		r = -EIO;
 406		goto free_ret;
 407	}
 408
 409	memcpy(dest, buffer, 1 << v->data_dev_block_bits);
 410	r = 0;
 411free_ret:
 412	mempool_free(page, &v->recheck_pool);
 413
 414	return r;
 415}
 416
 417static int verity_handle_data_hash_mismatch(struct dm_verity *v,
 418					    struct dm_verity_io *io,
 419					    struct bio *bio,
 420					    struct pending_block *block)
 421{
 422	const u8 *want_digest = block->want_digest;
 423	sector_t blkno = block->blkno;
 424	u8 *data = block->data;
 425
 426	if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 427		/*
 428		 * Error handling code (FEC included) cannot be run in the
 429		 * BH workqueue, so fallback to a standard workqueue.
 430		 */
 431		return -EAGAIN;
 432	}
 433	if (verity_recheck(v, io, want_digest, blkno, data) == 0) {
 434		if (v->validated_blocks)
 435			set_bit(blkno, v->validated_blocks);
 436		return 0;
 437	}
 438#if defined(CONFIG_DM_VERITY_FEC)
 439	if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA, want_digest,
 440			      blkno, data) == 0)
 441		return 0;
 442#endif
 443	if (bio->bi_status)
 444		return -EIO; /* Error correction failed; Just return error */
 445
 446	if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA, blkno)) {
 447		io->had_mismatch = true;
 448		dm_audit_log_bio(DM_MSG_PREFIX, "verify-data", bio, blkno, 0);
 449		return -EIO;
 450	}
 451	return 0;
 452}
 453
 454static void verity_clear_pending_blocks(struct dm_verity_io *io)
 455{
 456	int i;
 457
 458	for (i = io->num_pending - 1; i >= 0; i--) {
 459		kunmap_local(io->pending_blocks[i].data);
 460		io->pending_blocks[i].data = NULL;
 461	}
 462	io->num_pending = 0;
 463}
 464
 465static int verity_verify_pending_blocks(struct dm_verity *v,
 466					struct dm_verity_io *io,
 467					struct bio *bio)
 468{
 469	const unsigned int block_size = 1 << v->data_dev_block_bits;
 470	int i, r;
 471
 472	if (io->num_pending == 2) {
 473		/* num_pending == 2 implies that the algorithm is SHA-256 */
 474		sha256_finup_2x(v->initial_hashstate.sha256,
 475				io->pending_blocks[0].data,
 476				io->pending_blocks[1].data, block_size,
 477				io->pending_blocks[0].real_digest,
 478				io->pending_blocks[1].real_digest);
 479	} else {
 480		for (i = 0; i < io->num_pending; i++) {
 481			r = verity_hash(v, io, io->pending_blocks[i].data,
 482					block_size,
 483					io->pending_blocks[i].real_digest);
 484			if (unlikely(r))
 485				return r;
 486		}
 487	}
 488
 489	for (i = 0; i < io->num_pending; i++) {
 490		struct pending_block *block = &io->pending_blocks[i];
 491
 492		if (likely(memcmp(block->real_digest, block->want_digest,
 493				  v->digest_size) == 0)) {
 494			if (v->validated_blocks)
 495				set_bit(block->blkno, v->validated_blocks);
 496		} else {
 497			r = verity_handle_data_hash_mismatch(v, io, bio, block);
 498			if (unlikely(r))
 499				return r;
 500		}
 501	}
 502	verity_clear_pending_blocks(io);
 503	return 0;
 504}
 505
 506/*
 507 * Verify one "dm_verity_io" structure.
 508 */
 509static int verity_verify_io(struct dm_verity_io *io)
 510{
 511	struct dm_verity *v = io->v;
 512	const unsigned int block_size = 1 << v->data_dev_block_bits;
 513	const int max_pending = v->use_sha256_finup_2x ? 2 : 1;
 514	struct bvec_iter iter_copy;
 515	struct bvec_iter *iter;
 516	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 517	unsigned int b;
 518	int r;
 519
 520	io->num_pending = 0;
 521
 522	if (static_branch_unlikely(&use_bh_wq_enabled) && io->in_bh) {
 523		/*
 524		 * Copy the iterator in case we need to restart
 525		 * verification in a work-queue.
 526		 */
 527		iter_copy = io->iter;
 528		iter = &iter_copy;
 529	} else
 530		iter = &io->iter;
 531
 532	for (b = 0; b < io->n_blocks;
 533	     b++, bio_advance_iter(bio, iter, block_size)) {
 534		sector_t blkno = io->block + b;
 535		struct pending_block *block;
 536		bool is_zero;
 537		struct bio_vec bv;
 538		void *data;
 539
 540		if (v->validated_blocks && bio->bi_status == BLK_STS_OK &&
 541		    likely(test_bit(blkno, v->validated_blocks)))
 542			continue;
 543
 544		block = &io->pending_blocks[io->num_pending];
 545
 546		r = verity_hash_for_block(v, io, blkno, block->want_digest,
 547					  &is_zero);
 548		if (unlikely(r < 0))
 549			goto error;
 550
 551		bv = bio_iter_iovec(bio, *iter);
 552		if (unlikely(bv.bv_len < block_size)) {
 553			/*
 554			 * Data block spans pages.  This should not happen,
 555			 * since dm-verity sets dma_alignment to the data block
 556			 * size minus 1, and dm-verity also doesn't allow the
 557			 * data block size to be greater than PAGE_SIZE.
 558			 */
 559			DMERR_LIMIT("unaligned io (data block spans pages)");
 560			r = -EIO;
 561			goto error;
 562		}
 563
 564		data = bvec_kmap_local(&bv);
 565
 566		if (is_zero) {
 567			/*
 568			 * If we expect a zero block, don't validate, just
 569			 * return zeros.
 570			 */
 571			memset(data, 0, block_size);
 572			kunmap_local(data);
 573			continue;
 574		}
 575		block->data = data;
 576		block->blkno = blkno;
 577		if (++io->num_pending == max_pending) {
 578			r = verity_verify_pending_blocks(v, io, bio);
 579			if (unlikely(r))
 580				goto error;
 581		}
 582	}
 583
 584	if (io->num_pending) {
 585		r = verity_verify_pending_blocks(v, io, bio);
 586		if (unlikely(r))
 587			goto error;
 588	}
 589
 590	return 0;
 591
 592error:
 593	verity_clear_pending_blocks(io);
 594	return r;
 595}
 596
 597/*
 598 * Skip verity work in response to I/O error when system is shutting down.
 599 */
 600static inline bool verity_is_system_shutting_down(void)
 601{
 602	return system_state == SYSTEM_HALT || system_state == SYSTEM_POWER_OFF
 603		|| system_state == SYSTEM_RESTART;
 604}
 605
 606static void restart_io_error(struct work_struct *w)
 607{
 608	kernel_restart("dm-verity device has I/O error");
 609}
 610
 611/*
 612 * End one "io" structure with a given error.
 613 */
 614static void verity_finish_io(struct dm_verity_io *io, blk_status_t status)
 615{
 616	struct dm_verity *v = io->v;
 617	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
 618
 619	bio->bi_end_io = io->orig_bi_end_io;
 620	bio->bi_status = status;
 621
 622	if (!static_branch_unlikely(&use_bh_wq_enabled) || !io->in_bh)
 623		verity_fec_finish_io(io);
 624
 625	if (unlikely(status != BLK_STS_OK) &&
 626	    unlikely(!(bio->bi_opf & REQ_RAHEAD)) &&
 627	    !io->had_mismatch &&
 628	    !verity_is_system_shutting_down()) {
 629		if (v->error_mode == DM_VERITY_MODE_PANIC) {
 630			panic("dm-verity device has I/O error");
 631		}
 632		if (v->error_mode == DM_VERITY_MODE_RESTART) {
 633			static DECLARE_WORK(restart_work, restart_io_error);
 634			queue_work(v->verify_wq, &restart_work);
 635			/*
 636			 * We deliberately don't call bio_endio here, because
 637			 * the machine will be restarted anyway.
 638			 */
 639			return;
 640		}
 641	}
 642
 643	bio_endio(bio);
 644}
 645
 646static void verity_work(struct work_struct *w)
 647{
 648	struct dm_verity_io *io = container_of(w, struct dm_verity_io, work);
 649
 650	io->in_bh = false;
 651
 652	verity_finish_io(io, errno_to_blk_status(verity_verify_io(io)));
 653}
 654
 655static void verity_bh_work(struct work_struct *w)
 656{
 657	struct dm_verity_io *io = container_of(w, struct dm_verity_io, bh_work);
 658	int err;
 659
 660	io->in_bh = true;
 661	err = verity_verify_io(io);
 662	if (err == -EAGAIN || err == -ENOMEM) {
 663		/* fallback to retrying with work-queue */
 664		INIT_WORK(&io->work, verity_work);
 665		queue_work(io->v->verify_wq, &io->work);
 666		return;
 667	}
 668
 669	verity_finish_io(io, errno_to_blk_status(err));
 670}
 671
 672static inline bool verity_use_bh(unsigned int bytes, unsigned short ioprio)
 673{
 674	return ioprio <= IOPRIO_CLASS_IDLE &&
 675		bytes <= READ_ONCE(dm_verity_use_bh_bytes[ioprio]) &&
 676		!need_resched();
 677}
 678
 679static void verity_end_io(struct bio *bio)
 680{
 681	struct dm_verity_io *io = bio->bi_private;
 682	unsigned short ioprio = IOPRIO_PRIO_CLASS(bio->bi_ioprio);
 683	unsigned int bytes = io->n_blocks << io->v->data_dev_block_bits;
 684
 685	if (bio->bi_status &&
 686	    (!verity_fec_is_enabled(io->v) ||
 687	     verity_is_system_shutting_down() ||
 688	     (bio->bi_opf & REQ_RAHEAD))) {
 689		verity_finish_io(io, bio->bi_status);
 690		return;
 691	}
 692
 693	if (static_branch_unlikely(&use_bh_wq_enabled) && io->v->use_bh_wq &&
 694		verity_use_bh(bytes, ioprio)) {
 695		if (in_hardirq() || irqs_disabled()) {
 696			INIT_WORK(&io->bh_work, verity_bh_work);
 697			queue_work(system_bh_wq, &io->bh_work);
 698		} else {
 699			verity_bh_work(&io->bh_work);
 700		}
 701	} else {
 702		INIT_WORK(&io->work, verity_work);
 703		queue_work(io->v->verify_wq, &io->work);
 704	}
 705}
 706
 707/*
 708 * Prefetch buffers for the specified io.
 709 * The root buffer is not prefetched, it is assumed that it will be cached
 710 * all the time.
 711 */
 712static void verity_prefetch_io(struct work_struct *work)
 713{
 714	struct dm_verity_prefetch_work *pw =
 715		container_of(work, struct dm_verity_prefetch_work, work);
 716	struct dm_verity *v = pw->v;
 717	int i;
 718
 719	for (i = v->levels - 2; i >= 0; i--) {
 720		sector_t hash_block_start;
 721		sector_t hash_block_end;
 722
 723		verity_hash_at_level(v, pw->block, i, &hash_block_start, NULL);
 724		verity_hash_at_level(v, pw->block + pw->n_blocks - 1, i, &hash_block_end, NULL);
 725
 726		if (!i) {
 727			unsigned int cluster = READ_ONCE(dm_verity_prefetch_cluster);
 728
 729			cluster >>= v->data_dev_block_bits;
 730			if (unlikely(!cluster))
 731				goto no_prefetch_cluster;
 732
 733			if (unlikely(cluster & (cluster - 1)))
 734				cluster = 1 << __fls(cluster);
 735
 736			hash_block_start &= ~(sector_t)(cluster - 1);
 737			hash_block_end |= cluster - 1;
 738			if (unlikely(hash_block_end >= v->hash_blocks))
 739				hash_block_end = v->hash_blocks - 1;
 740		}
 741no_prefetch_cluster:
 742		dm_bufio_prefetch_with_ioprio(v->bufio, hash_block_start,
 743					hash_block_end - hash_block_start + 1,
 744					pw->ioprio);
 745	}
 746
 747	kfree(pw);
 748}
 749
 750static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io,
 751				   unsigned short ioprio)
 752{
 753	sector_t block = io->block;
 754	unsigned int n_blocks = io->n_blocks;
 755	struct dm_verity_prefetch_work *pw;
 756
 757	if (v->validated_blocks) {
 758		while (n_blocks && test_bit(block, v->validated_blocks)) {
 759			block++;
 760			n_blocks--;
 761		}
 762		while (n_blocks && test_bit(block + n_blocks - 1,
 763					    v->validated_blocks))
 764			n_blocks--;
 765		if (!n_blocks)
 766			return;
 767	}
 768
 769	pw = kmalloc(sizeof(struct dm_verity_prefetch_work),
 770		GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
 771
 772	if (!pw)
 773		return;
 774
 775	INIT_WORK(&pw->work, verity_prefetch_io);
 776	pw->v = v;
 777	pw->block = block;
 778	pw->n_blocks = n_blocks;
 779	pw->ioprio = ioprio;
 780	queue_work(v->verify_wq, &pw->work);
 781}
 782
 783/*
 784 * Bio map function. It allocates dm_verity_io structure and bio vector and
 785 * fills them. Then it issues prefetches and the I/O.
 786 */
 787static int verity_map(struct dm_target *ti, struct bio *bio)
 788{
 789	struct dm_verity *v = ti->private;
 790	struct dm_verity_io *io;
 791
 792	bio_set_dev(bio, v->data_dev->bdev);
 793	bio->bi_iter.bi_sector = verity_map_sector(v, bio->bi_iter.bi_sector);
 794
 795	if (((unsigned int)bio->bi_iter.bi_sector | bio_sectors(bio)) &
 796	    ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) {
 797		DMERR_LIMIT("unaligned io");
 798		return DM_MAPIO_KILL;
 799	}
 800
 801	if (bio_end_sector(bio) >>
 802	    (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) {
 803		DMERR_LIMIT("io out of range");
 804		return DM_MAPIO_KILL;
 805	}
 806
 807	if (bio_data_dir(bio) == WRITE)
 808		return DM_MAPIO_KILL;
 809
 810	io = dm_per_bio_data(bio, ti->per_io_data_size);
 811	io->v = v;
 812	io->orig_bi_end_io = bio->bi_end_io;
 813	io->block = bio->bi_iter.bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT);
 814	io->n_blocks = bio->bi_iter.bi_size >> v->data_dev_block_bits;
 815	io->had_mismatch = false;
 816
 817	bio->bi_end_io = verity_end_io;
 818	bio->bi_private = io;
 819	io->iter = bio->bi_iter;
 820
 821	verity_fec_init_io(io);
 822
 823	verity_submit_prefetch(v, io, bio->bi_ioprio);
 824
 825	submit_bio_noacct(bio);
 826
 827	return DM_MAPIO_SUBMITTED;
 828}
 829
 830static void verity_postsuspend(struct dm_target *ti)
 831{
 832	struct dm_verity *v = ti->private;
 833	flush_workqueue(v->verify_wq);
 834	dm_bufio_client_reset(v->bufio);
 835}
 836
 837/*
 838 * Status: V (valid) or C (corruption found)
 839 */
 840static void verity_status(struct dm_target *ti, status_type_t type,
 841			  unsigned int status_flags, char *result, unsigned int maxlen)
 842{
 843	struct dm_verity *v = ti->private;
 844	unsigned int args = 0;
 845	unsigned int sz = 0;
 846	unsigned int x;
 847
 848	switch (type) {
 849	case STATUSTYPE_INFO:
 850		DMEMIT("%c", v->hash_failed ? 'C' : 'V');
 851		if (verity_fec_is_enabled(v))
 852			DMEMIT(" %lld", atomic64_read(&v->fec->corrected));
 853		else
 854			DMEMIT(" -");
 855		break;
 856	case STATUSTYPE_TABLE:
 857		DMEMIT("%u %s %s %u %u %llu %llu %s ",
 858			v->version,
 859			v->data_dev->name,
 860			v->hash_dev->name,
 861			1 << v->data_dev_block_bits,
 862			1 << v->hash_dev_block_bits,
 863			(unsigned long long)v->data_blocks,
 864			(unsigned long long)v->hash_start,
 865			v->alg_name
 866			);
 867		for (x = 0; x < v->digest_size; x++)
 868			DMEMIT("%02x", v->root_digest[x]);
 869		DMEMIT(" ");
 870		if (!v->salt_size)
 871			DMEMIT("-");
 872		else
 873			for (x = 0; x < v->salt_size; x++)
 874				DMEMIT("%02x", v->salt[x]);
 875		if (v->mode != DM_VERITY_MODE_EIO)
 876			args++;
 877		if (v->error_mode != DM_VERITY_MODE_EIO)
 878			args++;
 879		if (verity_fec_is_enabled(v))
 880			args += DM_VERITY_OPTS_FEC;
 881		if (v->zero_digest)
 882			args++;
 883		if (v->validated_blocks)
 884			args++;
 885		if (v->use_bh_wq)
 886			args++;
 887		if (v->signature_key_desc)
 888			args += DM_VERITY_ROOT_HASH_VERIFICATION_OPTS;
 889		if (!args)
 890			return;
 891		DMEMIT(" %u", args);
 892		if (v->mode != DM_VERITY_MODE_EIO) {
 893			DMEMIT(" ");
 894			switch (v->mode) {
 895			case DM_VERITY_MODE_LOGGING:
 896				DMEMIT(DM_VERITY_OPT_LOGGING);
 897				break;
 898			case DM_VERITY_MODE_RESTART:
 899				DMEMIT(DM_VERITY_OPT_RESTART);
 900				break;
 901			case DM_VERITY_MODE_PANIC:
 902				DMEMIT(DM_VERITY_OPT_PANIC);
 903				break;
 904			default:
 905				BUG();
 906			}
 907		}
 908		if (v->error_mode != DM_VERITY_MODE_EIO) {
 909			DMEMIT(" ");
 910			switch (v->error_mode) {
 911			case DM_VERITY_MODE_RESTART:
 912				DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
 913				break;
 914			case DM_VERITY_MODE_PANIC:
 915				DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
 916				break;
 917			default:
 918				BUG();
 919			}
 920		}
 921		if (v->zero_digest)
 922			DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
 923		if (v->validated_blocks)
 924			DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 925		if (v->use_bh_wq)
 926			DMEMIT(" " DM_VERITY_OPT_TASKLET_VERIFY);
 927		sz = verity_fec_status_table(v, sz, result, maxlen);
 928		if (v->signature_key_desc)
 929			DMEMIT(" " DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY
 930				" %s", v->signature_key_desc);
 931		break;
 932
 933	case STATUSTYPE_IMA:
 934		DMEMIT_TARGET_NAME_VERSION(ti->type);
 935		DMEMIT(",hash_failed=%c", v->hash_failed ? 'C' : 'V');
 936		DMEMIT(",verity_version=%u", v->version);
 937		DMEMIT(",data_device_name=%s", v->data_dev->name);
 938		DMEMIT(",hash_device_name=%s", v->hash_dev->name);
 939		DMEMIT(",verity_algorithm=%s", v->alg_name);
 940
 941		DMEMIT(",root_digest=");
 942		for (x = 0; x < v->digest_size; x++)
 943			DMEMIT("%02x", v->root_digest[x]);
 944
 945		DMEMIT(",salt=");
 946		if (!v->salt_size)
 947			DMEMIT("-");
 948		else
 949			for (x = 0; x < v->salt_size; x++)
 950				DMEMIT("%02x", v->salt[x]);
 951
 952		DMEMIT(",ignore_zero_blocks=%c", v->zero_digest ? 'y' : 'n');
 953		DMEMIT(",check_at_most_once=%c", v->validated_blocks ? 'y' : 'n');
 954		if (v->signature_key_desc)
 955			DMEMIT(",root_hash_sig_key_desc=%s", v->signature_key_desc);
 956
 957		if (v->mode != DM_VERITY_MODE_EIO) {
 958			DMEMIT(",verity_mode=");
 959			switch (v->mode) {
 960			case DM_VERITY_MODE_LOGGING:
 961				DMEMIT(DM_VERITY_OPT_LOGGING);
 962				break;
 963			case DM_VERITY_MODE_RESTART:
 964				DMEMIT(DM_VERITY_OPT_RESTART);
 965				break;
 966			case DM_VERITY_MODE_PANIC:
 967				DMEMIT(DM_VERITY_OPT_PANIC);
 968				break;
 969			default:
 970				DMEMIT("invalid");
 971			}
 972		}
 973		if (v->error_mode != DM_VERITY_MODE_EIO) {
 974			DMEMIT(",verity_error_mode=");
 975			switch (v->error_mode) {
 976			case DM_VERITY_MODE_RESTART:
 977				DMEMIT(DM_VERITY_OPT_ERROR_RESTART);
 978				break;
 979			case DM_VERITY_MODE_PANIC:
 980				DMEMIT(DM_VERITY_OPT_ERROR_PANIC);
 981				break;
 982			default:
 983				DMEMIT("invalid");
 984			}
 985		}
 986		DMEMIT(";");
 987		break;
 988	}
 989}
 990
 991static int verity_prepare_ioctl(struct dm_target *ti, struct block_device **bdev,
 992				unsigned int cmd, unsigned long arg,
 993				bool *forward)
 994{
 995	struct dm_verity *v = ti->private;
 996
 997	*bdev = v->data_dev->bdev;
 998
 999	if (ti->len != bdev_nr_sectors(v->data_dev->bdev))
1000		return 1;
1001	return 0;
1002}
1003
1004static int verity_iterate_devices(struct dm_target *ti,
1005				  iterate_devices_callout_fn fn, void *data)
1006{
1007	struct dm_verity *v = ti->private;
1008
1009	return fn(ti, v->data_dev, 0, ti->len, data);
1010}
1011
1012static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
1013{
1014	struct dm_verity *v = ti->private;
1015
1016	if (limits->logical_block_size < 1 << v->data_dev_block_bits)
1017		limits->logical_block_size = 1 << v->data_dev_block_bits;
1018
1019	if (limits->physical_block_size < 1 << v->data_dev_block_bits)
1020		limits->physical_block_size = 1 << v->data_dev_block_bits;
1021
1022	limits->io_min = limits->logical_block_size;
1023
1024	/*
1025	 * Similar to what dm-crypt does, opt dm-verity out of support for
1026	 * direct I/O that is aligned to less than the traditional direct I/O
1027	 * alignment requirement of logical_block_size.  This prevents dm-verity
1028	 * data blocks from crossing pages, eliminating various edge cases.
1029	 */
1030	limits->dma_alignment = limits->logical_block_size - 1;
1031}
1032
1033#ifdef CONFIG_SECURITY
1034
1035static int verity_init_sig(struct dm_verity *v, const void *sig,
1036			   size_t sig_size)
1037{
1038	v->sig_size = sig_size;
1039
1040	if (sig) {
1041		v->root_digest_sig = kmemdup(sig, v->sig_size, GFP_KERNEL);
1042		if (!v->root_digest_sig)
1043			return -ENOMEM;
1044	}
1045
1046	return 0;
1047}
1048
1049static void verity_free_sig(struct dm_verity *v)
1050{
1051	kfree(v->root_digest_sig);
1052}
1053
1054#else
1055
1056static inline int verity_init_sig(struct dm_verity *v, const void *sig,
1057				  size_t sig_size)
1058{
1059	return 0;
1060}
1061
1062static inline void verity_free_sig(struct dm_verity *v)
1063{
1064}
1065
1066#endif /* CONFIG_SECURITY */
1067
1068static void verity_dtr(struct dm_target *ti)
1069{
1070	struct dm_verity *v = ti->private;
1071
1072	if (v->verify_wq)
1073		destroy_workqueue(v->verify_wq);
1074
1075	mempool_exit(&v->recheck_pool);
1076	if (v->io)
1077		dm_io_client_destroy(v->io);
1078
1079	if (v->bufio)
1080		dm_bufio_client_destroy(v->bufio);
1081
1082	kvfree(v->validated_blocks);
1083	kfree(v->salt);
1084	kfree(v->initial_hashstate.shash);
1085	kfree(v->root_digest);
1086	kfree(v->zero_digest);
1087	verity_free_sig(v);
1088
1089	crypto_free_shash(v->shash_tfm);
1090
1091	kfree(v->alg_name);
1092
1093	if (v->hash_dev)
1094		dm_put_device(ti, v->hash_dev);
1095
1096	if (v->data_dev)
1097		dm_put_device(ti, v->data_dev);
1098
1099	verity_fec_dtr(v);
1100
1101	kfree(v->signature_key_desc);
1102
1103	if (v->use_bh_wq)
1104		static_branch_dec(&use_bh_wq_enabled);
1105
1106	kfree(v);
1107
1108	dm_audit_log_dtr(DM_MSG_PREFIX, ti, 1);
1109}
1110
1111static int verity_alloc_most_once(struct dm_verity *v)
1112{
1113	struct dm_target *ti = v->ti;
1114
1115	if (v->validated_blocks)
1116		return 0;
1117
1118	/* the bitset can only handle INT_MAX blocks */
1119	if (v->data_blocks > INT_MAX) {
1120		ti->error = "device too large to use check_at_most_once";
1121		return -E2BIG;
1122	}
1123
1124	v->validated_blocks = kvcalloc(BITS_TO_LONGS(v->data_blocks),
1125				       sizeof(unsigned long),
1126				       GFP_KERNEL);
1127	if (!v->validated_blocks) {
1128		ti->error = "failed to allocate bitset for check_at_most_once";
1129		return -ENOMEM;
1130	}
1131
1132	return 0;
1133}
1134
1135static int verity_alloc_zero_digest(struct dm_verity *v)
1136{
1137	int r = -ENOMEM;
1138	struct dm_verity_io *io;
1139	u8 *zero_data;
1140
1141	if (v->zero_digest)
1142		return 0;
1143
1144	v->zero_digest = kmalloc(v->digest_size, GFP_KERNEL);
1145
1146	if (!v->zero_digest)
1147		return r;
1148
1149	io = kmalloc(v->ti->per_io_data_size, GFP_KERNEL);
1150
1151	if (!io)
1152		return r; /* verity_dtr will free zero_digest */
1153
1154	zero_data = kzalloc(1 << v->data_dev_block_bits, GFP_KERNEL);
1155
1156	if (!zero_data)
1157		goto out;
1158
1159	r = verity_hash(v, io, zero_data, 1 << v->data_dev_block_bits,
1160			v->zero_digest);
1161
1162out:
1163	kfree(io);
1164	kfree(zero_data);
1165
1166	return r;
1167}
1168
1169static inline bool verity_is_verity_mode(const char *arg_name)
1170{
1171	return (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING) ||
1172		!strcasecmp(arg_name, DM_VERITY_OPT_RESTART) ||
1173		!strcasecmp(arg_name, DM_VERITY_OPT_PANIC));
1174}
1175
1176static int verity_parse_verity_mode(struct dm_verity *v, const char *arg_name)
1177{
1178	if (v->mode)
1179		return -EINVAL;
1180
1181	if (!strcasecmp(arg_name, DM_VERITY_OPT_LOGGING))
1182		v->mode = DM_VERITY_MODE_LOGGING;
1183	else if (!strcasecmp(arg_name, DM_VERITY_OPT_RESTART))
1184		v->mode = DM_VERITY_MODE_RESTART;
1185	else if (!strcasecmp(arg_name, DM_VERITY_OPT_PANIC))
1186		v->mode = DM_VERITY_MODE_PANIC;
1187
1188	return 0;
1189}
1190
1191static inline bool verity_is_verity_error_mode(const char *arg_name)
1192{
1193	return (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART) ||
1194		!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC));
1195}
1196
1197static int verity_parse_verity_error_mode(struct dm_verity *v, const char *arg_name)
1198{
1199	if (v->error_mode)
1200		return -EINVAL;
1201
1202	if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_RESTART))
1203		v->error_mode = DM_VERITY_MODE_RESTART;
1204	else if (!strcasecmp(arg_name, DM_VERITY_OPT_ERROR_PANIC))
1205		v->error_mode = DM_VERITY_MODE_PANIC;
1206
1207	return 0;
1208}
1209
1210static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
1211				 struct dm_verity_sig_opts *verify_args,
1212				 bool only_modifier_opts)
1213{
1214	int r = 0;
1215	unsigned int argc;
1216	struct dm_target *ti = v->ti;
1217	const char *arg_name;
1218
1219	static const struct dm_arg _args[] = {
1220		{0, DM_VERITY_OPTS_MAX, "Invalid number of feature args"},
1221	};
1222
1223	r = dm_read_arg_group(_args, as, &argc, &ti->error);
1224	if (r)
1225		return -EINVAL;
1226
1227	if (!argc)
1228		return 0;
1229
1230	do {
1231		arg_name = dm_shift_arg(as);
1232		argc--;
1233
1234		if (verity_is_verity_mode(arg_name)) {
1235			if (only_modifier_opts)
1236				continue;
1237			r = verity_parse_verity_mode(v, arg_name);
1238			if (r) {
1239				ti->error = "Conflicting error handling parameters";
1240				return r;
1241			}
1242			continue;
1243
1244		} else if (verity_is_verity_error_mode(arg_name)) {
1245			if (only_modifier_opts)
1246				continue;
1247			r = verity_parse_verity_error_mode(v, arg_name);
1248			if (r) {
1249				ti->error = "Conflicting error handling parameters";
1250				return r;
1251			}
1252			continue;
1253
1254		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_IGN_ZEROES)) {
1255			if (only_modifier_opts)
1256				continue;
1257			r = verity_alloc_zero_digest(v);
1258			if (r) {
1259				ti->error = "Cannot allocate zero digest";
1260				return r;
1261			}
1262			continue;
1263
1264		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
1265			if (only_modifier_opts)
1266				continue;
1267			r = verity_alloc_most_once(v);
1268			if (r)
1269				return r;
1270			continue;
1271
1272		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_TASKLET_VERIFY)) {
1273			v->use_bh_wq = true;
1274			static_branch_inc(&use_bh_wq_enabled);
1275			continue;
1276
1277		} else if (verity_is_fec_opt_arg(arg_name)) {
1278			if (only_modifier_opts)
1279				continue;
1280			r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
1281			if (r)
1282				return r;
1283			continue;
1284
1285		} else if (verity_verify_is_sig_opt_arg(arg_name)) {
1286			if (only_modifier_opts)
1287				continue;
1288			r = verity_verify_sig_parse_opt_args(as, v,
1289							     verify_args,
1290							     &argc, arg_name);
1291			if (r)
1292				return r;
1293			continue;
1294
1295		} else if (only_modifier_opts) {
1296			/*
1297			 * Ignore unrecognized opt, could easily be an extra
1298			 * argument to an option whose parsing was skipped.
1299			 * Normal parsing (@only_modifier_opts=false) will
1300			 * properly parse all options (and their extra args).
1301			 */
1302			continue;
1303		}
1304
1305		DMERR("Unrecognized verity feature request: %s", arg_name);
1306		ti->error = "Unrecognized verity feature request";
1307		return -EINVAL;
1308	} while (argc && !r);
1309
1310	return r;
1311}
1312
1313static int verity_setup_hash_alg(struct dm_verity *v, const char *alg_name)
1314{
1315	struct dm_target *ti = v->ti;
1316	struct crypto_shash *shash;
1317
1318	v->alg_name = kstrdup(alg_name, GFP_KERNEL);
1319	if (!v->alg_name) {
1320		ti->error = "Cannot allocate algorithm name";
1321		return -ENOMEM;
1322	}
1323
1324	shash = crypto_alloc_shash(alg_name, 0, 0);
1325	if (IS_ERR(shash)) {
1326		ti->error = "Cannot initialize hash function";
1327		return PTR_ERR(shash);
1328	}
1329	v->shash_tfm = shash;
1330	v->digest_size = crypto_shash_digestsize(shash);
1331	if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
1332		ti->error = "Digest size too big";
1333		return -EINVAL;
1334	}
1335	if (likely(v->version && strcmp(alg_name, "sha256") == 0)) {
1336		/*
1337		 * Fast path: use the library API for reduced overhead and
1338		 * interleaved hashing support.
1339		 */
1340		v->use_sha256_lib = true;
1341		if (sha256_finup_2x_is_optimized())
1342			v->use_sha256_finup_2x = true;
1343		ti->per_io_data_size =
1344			offsetofend(struct dm_verity_io, hash_ctx.sha256);
1345	} else {
1346		/* Fallback case: use the generic crypto API. */
1347		ti->per_io_data_size =
1348			offsetofend(struct dm_verity_io, hash_ctx.shash) +
1349			crypto_shash_descsize(shash);
1350	}
1351	return 0;
1352}
1353
1354static int verity_setup_salt_and_hashstate(struct dm_verity *v, const char *arg)
1355{
1356	struct dm_target *ti = v->ti;
1357
1358	if (strcmp(arg, "-") != 0) {
1359		v->salt_size = strlen(arg) / 2;
1360		v->salt = kmalloc(v->salt_size, GFP_KERNEL);
1361		if (!v->salt) {
1362			ti->error = "Cannot allocate salt";
1363			return -ENOMEM;
1364		}
1365		if (strlen(arg) != v->salt_size * 2 ||
1366		    hex2bin(v->salt, arg, v->salt_size)) {
1367			ti->error = "Invalid salt";
1368			return -EINVAL;
1369		}
1370	}
1371	if (likely(v->use_sha256_lib)) {
1372		/* Implies version 1: salt at beginning */
1373		v->initial_hashstate.sha256 =
1374			kmalloc(sizeof(struct sha256_ctx), GFP_KERNEL);
1375		if (!v->initial_hashstate.sha256) {
1376			ti->error = "Cannot allocate initial hash state";
1377			return -ENOMEM;
1378		}
1379		sha256_init(v->initial_hashstate.sha256);
1380		sha256_update(v->initial_hashstate.sha256,
1381			      v->salt, v->salt_size);
1382	} else if (v->version) { /* Version 1: salt at beginning */
1383		SHASH_DESC_ON_STACK(desc, v->shash_tfm);
1384		int r;
1385
1386		/*
1387		 * Compute the pre-salted hash state that can be passed to
1388		 * crypto_shash_import() for each block later.
1389		 */
1390		v->initial_hashstate.shash = kmalloc(
1391			crypto_shash_statesize(v->shash_tfm), GFP_KERNEL);
1392		if (!v->initial_hashstate.shash) {
1393			ti->error = "Cannot allocate initial hash state";
1394			return -ENOMEM;
1395		}
1396		desc->tfm = v->shash_tfm;
1397		r = crypto_shash_init(desc) ?:
1398		    crypto_shash_update(desc, v->salt, v->salt_size) ?:
1399		    crypto_shash_export(desc, v->initial_hashstate.shash);
1400		if (r) {
1401			ti->error = "Cannot set up initial hash state";
1402			return r;
1403		}
1404	}
1405	return 0;
1406}
1407
1408/*
1409 * Target parameters:
1410 *	<version>	The current format is version 1.
1411 *			Vsn 0 is compatible with original Chromium OS releases.
1412 *	<data device>
1413 *	<hash device>
1414 *	<data block size>
1415 *	<hash block size>
1416 *	<the number of data blocks>
1417 *	<hash start block>
1418 *	<algorithm>
1419 *	<digest>
1420 *	<salt>		Hex string or "-" if no salt.
1421 */
1422static int verity_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1423{
1424	struct dm_verity *v;
1425	struct dm_verity_sig_opts verify_args = {0};
1426	struct dm_arg_set as;
1427	unsigned int num;
1428	unsigned long long num_ll;
1429	int r;
1430	int i;
1431	sector_t hash_position;
1432	char dummy;
1433	char *root_hash_digest_to_validate;
1434
1435	v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL);
1436	if (!v) {
1437		ti->error = "Cannot allocate verity structure";
1438		return -ENOMEM;
1439	}
1440	ti->private = v;
1441	v->ti = ti;
1442
1443	r = verity_fec_ctr_alloc(v);
1444	if (r)
1445		goto bad;
1446
1447	if ((dm_table_get_mode(ti->table) & ~BLK_OPEN_READ)) {
1448		ti->error = "Device must be readonly";
1449		r = -EINVAL;
1450		goto bad;
1451	}
1452
1453	if (argc < 10) {
1454		ti->error = "Not enough arguments";
1455		r = -EINVAL;
1456		goto bad;
1457	}
1458
1459	/* Parse optional parameters that modify primary args */
1460	if (argc > 10) {
1461		as.argc = argc - 10;
1462		as.argv = argv + 10;
1463		r = verity_parse_opt_args(&as, v, &verify_args, true);
1464		if (r < 0)
1465			goto bad;
1466	}
1467
1468	if (sscanf(argv[0], "%u%c", &num, &dummy) != 1 ||
1469	    num > 1) {
1470		ti->error = "Invalid version";
1471		r = -EINVAL;
1472		goto bad;
1473	}
1474	v->version = num;
1475
1476	r = dm_get_device(ti, argv[1], BLK_OPEN_READ, &v->data_dev);
1477	if (r) {
1478		ti->error = "Data device lookup failed";
1479		goto bad;
1480	}
1481
1482	r = dm_get_device(ti, argv[2], BLK_OPEN_READ, &v->hash_dev);
1483	if (r) {
1484		ti->error = "Hash device lookup failed";
1485		goto bad;
1486	}
1487
1488	if (sscanf(argv[3], "%u%c", &num, &dummy) != 1 ||
1489	    !num || (num & (num - 1)) ||
1490	    num < bdev_logical_block_size(v->data_dev->bdev) ||
1491	    num > PAGE_SIZE) {
1492		ti->error = "Invalid data device block size";
1493		r = -EINVAL;
1494		goto bad;
1495	}
1496	v->data_dev_block_bits = __ffs(num);
1497
1498	if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 ||
1499	    !num || (num & (num - 1)) ||
1500	    num < bdev_logical_block_size(v->hash_dev->bdev) ||
1501	    num > INT_MAX) {
1502		ti->error = "Invalid hash device block size";
1503		r = -EINVAL;
1504		goto bad;
1505	}
1506	v->hash_dev_block_bits = __ffs(num);
1507
1508	if (sscanf(argv[5], "%llu%c", &num_ll, &dummy) != 1 ||
1509	    (sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
1510	    >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1511		ti->error = "Invalid data blocks";
1512		r = -EINVAL;
1513		goto bad;
1514	}
1515	v->data_blocks = num_ll;
1516
1517	if (ti->len > (v->data_blocks << (v->data_dev_block_bits - SECTOR_SHIFT))) {
1518		ti->error = "Data device is too small";
1519		r = -EINVAL;
1520		goto bad;
1521	}
1522
1523	if (sscanf(argv[6], "%llu%c", &num_ll, &dummy) != 1 ||
1524	    (sector_t)(num_ll << (v->hash_dev_block_bits - SECTOR_SHIFT))
1525	    >> (v->hash_dev_block_bits - SECTOR_SHIFT) != num_ll) {
1526		ti->error = "Invalid hash start";
1527		r = -EINVAL;
1528		goto bad;
1529	}
1530	v->hash_start = num_ll;
1531
1532	r = verity_setup_hash_alg(v, argv[7]);
1533	if (r)
1534		goto bad;
1535
1536	v->root_digest = kmalloc(v->digest_size, GFP_KERNEL);
1537	if (!v->root_digest) {
1538		ti->error = "Cannot allocate root digest";
1539		r = -ENOMEM;
1540		goto bad;
1541	}
1542	if (strlen(argv[8]) != v->digest_size * 2 ||
1543	    hex2bin(v->root_digest, argv[8], v->digest_size)) {
1544		ti->error = "Invalid root digest";
1545		r = -EINVAL;
1546		goto bad;
1547	}
1548	root_hash_digest_to_validate = argv[8];
1549
1550	r = verity_setup_salt_and_hashstate(v, argv[9]);
1551	if (r)
1552		goto bad;
1553
1554	argv += 10;
1555	argc -= 10;
1556
1557	/* Optional parameters */
1558	if (argc) {
1559		as.argc = argc;
1560		as.argv = argv;
1561		r = verity_parse_opt_args(&as, v, &verify_args, false);
1562		if (r < 0)
1563			goto bad;
1564	}
1565
1566	/* Root hash signature is an optional parameter */
1567	r = verity_verify_root_hash(root_hash_digest_to_validate,
1568				    strlen(root_hash_digest_to_validate),
1569				    verify_args.sig,
1570				    verify_args.sig_size);
1571	if (r < 0) {
1572		ti->error = "Root hash verification failed";
1573		goto bad;
1574	}
1575
1576	r = verity_init_sig(v, verify_args.sig, verify_args.sig_size);
1577	if (r < 0) {
1578		ti->error = "Cannot allocate root digest signature";
1579		goto bad;
1580	}
1581
1582	v->hash_per_block_bits =
1583		__fls((1 << v->hash_dev_block_bits) / v->digest_size);
1584
1585	v->levels = 0;
1586	if (v->data_blocks)
1587		while (v->hash_per_block_bits * v->levels < 64 &&
1588		       (unsigned long long)(v->data_blocks - 1) >>
1589		       (v->hash_per_block_bits * v->levels))
1590			v->levels++;
1591
1592	if (v->levels > DM_VERITY_MAX_LEVELS) {
1593		ti->error = "Too many tree levels";
1594		r = -E2BIG;
1595		goto bad;
1596	}
1597
1598	hash_position = v->hash_start;
1599	for (i = v->levels - 1; i >= 0; i--) {
1600		sector_t s;
1601
1602		v->hash_level_block[i] = hash_position;
1603		s = (v->data_blocks + ((sector_t)1 << ((i + 1) * v->hash_per_block_bits)) - 1)
1604					>> ((i + 1) * v->hash_per_block_bits);
1605		if (hash_position + s < hash_position) {
1606			ti->error = "Hash device offset overflow";
1607			r = -E2BIG;
1608			goto bad;
1609		}
1610		hash_position += s;
1611	}
1612	v->hash_blocks = hash_position;
1613
1614	r = mempool_init_page_pool(&v->recheck_pool, 1, 0);
1615	if (unlikely(r)) {
1616		ti->error = "Cannot allocate mempool";
1617		goto bad;
1618	}
1619
1620	v->io = dm_io_client_create();
1621	if (IS_ERR(v->io)) {
1622		r = PTR_ERR(v->io);
1623		v->io = NULL;
1624		ti->error = "Cannot allocate dm io";
1625		goto bad;
1626	}
1627
1628	v->bufio = dm_bufio_client_create(v->hash_dev->bdev,
1629		1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux),
1630		dm_bufio_alloc_callback, NULL,
1631		v->use_bh_wq ? DM_BUFIO_CLIENT_NO_SLEEP : 0);
1632	if (IS_ERR(v->bufio)) {
1633		ti->error = "Cannot initialize dm-bufio";
1634		r = PTR_ERR(v->bufio);
1635		v->bufio = NULL;
1636		goto bad;
1637	}
1638
1639	if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) {
1640		ti->error = "Hash device is too small";
1641		r = -E2BIG;
1642		goto bad;
1643	}
1644
1645	/*
1646	 * Using WQ_HIGHPRI improves throughput and completion latency by
1647	 * reducing wait times when reading from a dm-verity device.
1648	 *
1649	 * Also as required for the "try_verify_in_tasklet" feature: WQ_HIGHPRI
1650	 * allows verify_wq to preempt softirq since verification in BH workqueue
1651	 * will fall-back to using it for error handling (or if the bufio cache
1652	 * doesn't have required hashes).
1653	 */
1654	v->verify_wq = alloc_workqueue("kverityd", WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1655	if (!v->verify_wq) {
1656		ti->error = "Cannot allocate workqueue";
1657		r = -ENOMEM;
1658		goto bad;
1659	}
1660
1661	r = verity_fec_ctr(v);
1662	if (r)
1663		goto bad;
1664
1665	ti->per_io_data_size = roundup(ti->per_io_data_size,
1666				       __alignof__(struct dm_verity_io));
1667
1668	verity_verify_sig_opts_cleanup(&verify_args);
1669
1670	dm_audit_log_ctr(DM_MSG_PREFIX, ti, 1);
1671
1672	return 0;
1673
1674bad:
1675
1676	verity_verify_sig_opts_cleanup(&verify_args);
1677	dm_audit_log_ctr(DM_MSG_PREFIX, ti, 0);
1678	verity_dtr(ti);
1679
1680	return r;
1681}
1682
1683/*
1684 * Get the verity mode (error behavior) of a verity target.
1685 *
1686 * Returns the verity mode of the target, or -EINVAL if 'ti' is not a verity
1687 * target.
1688 */
1689int dm_verity_get_mode(struct dm_target *ti)
1690{
1691	struct dm_verity *v = ti->private;
1692
1693	if (!dm_is_verity_target(ti))
1694		return -EINVAL;
1695
1696	return v->mode;
1697}
1698
1699/*
1700 * Get the root digest of a verity target.
1701 *
1702 * Returns a copy of the root digest, the caller is responsible for
1703 * freeing the memory of the digest.
1704 */
1705int dm_verity_get_root_digest(struct dm_target *ti, u8 **root_digest, unsigned int *digest_size)
1706{
1707	struct dm_verity *v = ti->private;
1708
1709	if (!dm_is_verity_target(ti))
1710		return -EINVAL;
1711
1712	*root_digest = kmemdup(v->root_digest, v->digest_size, GFP_KERNEL);
1713	if (*root_digest == NULL)
1714		return -ENOMEM;
1715
1716	*digest_size = v->digest_size;
1717
1718	return 0;
1719}
1720
1721#ifdef CONFIG_SECURITY
1722
1723#ifdef CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG
1724
1725static int verity_security_set_signature(struct block_device *bdev,
1726					 struct dm_verity *v)
1727{
1728	/*
1729	 * if the dm-verity target is unsigned, v->root_digest_sig will
1730	 * be NULL, and the hook call is still required to let LSMs mark
1731	 * the device as unsigned. This information is crucial for LSMs to
1732	 * block operations such as execution on unsigned files
1733	 */
1734	return security_bdev_setintegrity(bdev,
1735					  LSM_INT_DMVERITY_SIG_VALID,
1736					  v->root_digest_sig,
1737					  v->sig_size);
1738}
1739
1740#else
1741
1742static inline int verity_security_set_signature(struct block_device *bdev,
1743						struct dm_verity *v)
1744{
1745	return 0;
1746}
1747
1748#endif /* CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG */
1749
1750/*
1751 * Expose verity target's root hash and signature data to LSMs before resume.
1752 *
1753 * Returns 0 on success, or -ENOMEM if the system is out of memory.
1754 */
1755static int verity_preresume(struct dm_target *ti)
1756{
1757	struct block_device *bdev;
1758	struct dm_verity_digest root_digest;
1759	struct dm_verity *v;
1760	int r;
1761
1762	v = ti->private;
1763	bdev = dm_disk(dm_table_get_md(ti->table))->part0;
1764	root_digest.digest = v->root_digest;
1765	root_digest.digest_len = v->digest_size;
1766	root_digest.alg = crypto_shash_alg_name(v->shash_tfm);
1767
1768	r = security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, &root_digest,
1769				       sizeof(root_digest));
1770	if (r)
1771		return r;
1772
1773	r =  verity_security_set_signature(bdev, v);
1774	if (r)
1775		goto bad;
1776
1777	return 0;
1778
1779bad:
1780
1781	security_bdev_setintegrity(bdev, LSM_INT_DMVERITY_ROOTHASH, NULL, 0);
1782
1783	return r;
1784}
1785
1786#endif /* CONFIG_SECURITY */
1787
1788static struct target_type verity_target = {
1789	.name		= "verity",
1790/* Note: the LSMs depend on the singleton and immutable features */
1791	.features	= DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1792	.version	= {1, 13, 0},
1793	.module		= THIS_MODULE,
1794	.ctr		= verity_ctr,
1795	.dtr		= verity_dtr,
1796	.map		= verity_map,
1797	.postsuspend	= verity_postsuspend,
1798	.status		= verity_status,
1799	.prepare_ioctl	= verity_prepare_ioctl,
1800	.iterate_devices = verity_iterate_devices,
1801	.io_hints	= verity_io_hints,
1802#ifdef CONFIG_SECURITY
1803	.preresume	= verity_preresume,
1804#endif /* CONFIG_SECURITY */
1805};
1806module_dm(verity);
1807
1808/*
1809 * Check whether a DM target is a verity target.
1810 */
1811bool dm_is_verity_target(struct dm_target *ti)
1812{
1813	return ti->type == &verity_target;
1814}
1815
1816MODULE_AUTHOR("Mikulas Patocka <mpatocka@redhat.com>");
1817MODULE_AUTHOR("Mandeep Baines <msb@chromium.org>");
1818MODULE_AUTHOR("Will Drewry <wad@chromium.org>");
1819MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking");
1820MODULE_LICENSE("GPL");