dm-ioctl.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
   4 * Copyright (C) 2004 - 2006 Red Hat, Inc. All rights reserved.
   5 *
   6 * This file is released under the GPL.
   7 */
   8
   9#include "dm-core.h"
  10#include "dm-ima.h"
  11#include <linux/module.h>
  12#include <linux/vmalloc.h>
  13#include <linux/miscdevice.h>
  14#include <linux/sched/mm.h>
  15#include <linux/init.h>
  16#include <linux/wait.h>
  17#include <linux/slab.h>
  18#include <linux/rbtree.h>
  19#include <linux/dm-ioctl.h>
  20#include <linux/hdreg.h>
  21#include <linux/compat.h>
  22#include <linux/nospec.h>
  23
  24#include <linux/uaccess.h>
  25#include <linux/ima.h>
  26
  27#define DM_MSG_PREFIX "ioctl"
  28#define DM_DRIVER_EMAIL "dm-devel@lists.linux.dev"
  29
  30struct dm_file {
  31	/*
  32	 * poll will wait until the global event number is greater than
  33	 * this value.
  34	 */
  35	volatile unsigned int global_event_nr;
  36};
  37
  38/*
  39 *---------------------------------------------------------------
  40 * The ioctl interface needs to be able to look up devices by
  41 * name or uuid.
  42 *---------------------------------------------------------------
  43 */
  44struct hash_cell {
  45	struct rb_node name_node;
  46	struct rb_node uuid_node;
  47	bool name_set;
  48	bool uuid_set;
  49
  50	char *name;
  51	char *uuid;
  52	struct mapped_device *md;
  53	struct dm_table *new_map;
  54};
  55
  56struct vers_iter {
  57	size_t param_size;
  58	struct dm_target_versions *vers, *old_vers;
  59	char *end;
  60	uint32_t flags;
  61};
  62
  63
  64static struct rb_root name_rb_tree = RB_ROOT;
  65static struct rb_root uuid_rb_tree = RB_ROOT;
  66
  67static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred);
  68
  69/*
  70 * Guards access to both hash tables.
  71 */
  72static DECLARE_RWSEM(_hash_lock);
  73
  74/*
  75 * Protects use of mdptr to obtain hash cell name and uuid from mapped device.
  76 */
  77static DEFINE_MUTEX(dm_hash_cells_mutex);
  78
  79static void dm_hash_exit(void)
  80{
  81	dm_hash_remove_all(false, false, false);
  82}
  83
  84/*
  85 *---------------------------------------------------------------
  86 * Code for looking up a device by name
  87 *---------------------------------------------------------------
  88 */
  89static struct hash_cell *__get_name_cell(const char *str)
  90{
  91	struct rb_node *n = name_rb_tree.rb_node;
  92
  93	while (n) {
  94		struct hash_cell *hc = container_of(n, struct hash_cell, name_node);
  95		int c;
  96
  97		c = strcmp(hc->name, str);
  98		if (!c) {
  99			dm_get(hc->md);
 100			return hc;
 101		}
 102		n = c >= 0 ? n->rb_left : n->rb_right;
 103	}
 104
 105	return NULL;
 106}
 107
 108static struct hash_cell *__get_uuid_cell(const char *str)
 109{
 110	struct rb_node *n = uuid_rb_tree.rb_node;
 111
 112	while (n) {
 113		struct hash_cell *hc = container_of(n, struct hash_cell, uuid_node);
 114		int c;
 115
 116		c = strcmp(hc->uuid, str);
 117		if (!c) {
 118			dm_get(hc->md);
 119			return hc;
 120		}
 121		n = c >= 0 ? n->rb_left : n->rb_right;
 122	}
 123
 124	return NULL;
 125}
 126
 127static void __unlink_name(struct hash_cell *hc)
 128{
 129	if (hc->name_set) {
 130		hc->name_set = false;
 131		rb_erase(&hc->name_node, &name_rb_tree);
 132	}
 133}
 134
 135static void __unlink_uuid(struct hash_cell *hc)
 136{
 137	if (hc->uuid_set) {
 138		hc->uuid_set = false;
 139		rb_erase(&hc->uuid_node, &uuid_rb_tree);
 140	}
 141}
 142
 143static void __link_name(struct hash_cell *new_hc)
 144{
 145	struct rb_node **n, *parent;
 146
 147	__unlink_name(new_hc);
 148
 149	new_hc->name_set = true;
 150
 151	n = &name_rb_tree.rb_node;
 152	parent = NULL;
 153
 154	while (*n) {
 155		struct hash_cell *hc = container_of(*n, struct hash_cell, name_node);
 156		int c;
 157
 158		c = strcmp(hc->name, new_hc->name);
 159		BUG_ON(!c);
 160		parent = *n;
 161		n = c >= 0 ? &hc->name_node.rb_left : &hc->name_node.rb_right;
 162	}
 163
 164	rb_link_node(&new_hc->name_node, parent, n);
 165	rb_insert_color(&new_hc->name_node, &name_rb_tree);
 166}
 167
 168static void __link_uuid(struct hash_cell *new_hc)
 169{
 170	struct rb_node **n, *parent;
 171
 172	__unlink_uuid(new_hc);
 173
 174	new_hc->uuid_set = true;
 175
 176	n = &uuid_rb_tree.rb_node;
 177	parent = NULL;
 178
 179	while (*n) {
 180		struct hash_cell *hc = container_of(*n, struct hash_cell, uuid_node);
 181		int c;
 182
 183		c = strcmp(hc->uuid, new_hc->uuid);
 184		BUG_ON(!c);
 185		parent = *n;
 186		n = c > 0 ? &hc->uuid_node.rb_left : &hc->uuid_node.rb_right;
 187	}
 188
 189	rb_link_node(&new_hc->uuid_node, parent, n);
 190	rb_insert_color(&new_hc->uuid_node, &uuid_rb_tree);
 191}
 192
 193static struct hash_cell *__get_dev_cell(uint64_t dev)
 194{
 195	struct mapped_device *md;
 196	struct hash_cell *hc;
 197
 198	md = dm_get_md(huge_decode_dev(dev));
 199	if (!md)
 200		return NULL;
 201
 202	hc = dm_get_mdptr(md);
 203	if (!hc) {
 204		dm_put(md);
 205		return NULL;
 206	}
 207
 208	return hc;
 209}
 210
 211/*
 212 *---------------------------------------------------------------
 213 * Inserting, removing and renaming a device.
 214 *---------------------------------------------------------------
 215 */
 216static struct hash_cell *alloc_cell(const char *name, const char *uuid,
 217				    struct mapped_device *md)
 218{
 219	struct hash_cell *hc;
 220
 221	hc = kmalloc(sizeof(*hc), GFP_KERNEL);
 222	if (!hc)
 223		return NULL;
 224
 225	hc->name = kstrdup(name, GFP_KERNEL);
 226	if (!hc->name) {
 227		kfree(hc);
 228		return NULL;
 229	}
 230
 231	if (!uuid)
 232		hc->uuid = NULL;
 233
 234	else {
 235		hc->uuid = kstrdup(uuid, GFP_KERNEL);
 236		if (!hc->uuid) {
 237			kfree(hc->name);
 238			kfree(hc);
 239			return NULL;
 240		}
 241	}
 242
 243	hc->name_set = hc->uuid_set = false;
 244	hc->md = md;
 245	hc->new_map = NULL;
 246	return hc;
 247}
 248
 249static void free_cell(struct hash_cell *hc)
 250{
 251	if (hc) {
 252		kfree(hc->name);
 253		kfree(hc->uuid);
 254		kfree(hc);
 255	}
 256}
 257
 258/*
 259 * The kdev_t and uuid of a device can never change once it is
 260 * initially inserted.
 261 */
 262static int dm_hash_insert(const char *name, const char *uuid, struct mapped_device *md)
 263{
 264	struct hash_cell *cell, *hc;
 265
 266	/*
 267	 * Allocate the new cells.
 268	 */
 269	cell = alloc_cell(name, uuid, md);
 270	if (!cell)
 271		return -ENOMEM;
 272
 273	/*
 274	 * Insert the cell into both hash tables.
 275	 */
 276	down_write(&_hash_lock);
 277	hc = __get_name_cell(name);
 278	if (hc) {
 279		dm_put(hc->md);
 280		goto bad;
 281	}
 282
 283	__link_name(cell);
 284
 285	if (uuid) {
 286		hc = __get_uuid_cell(uuid);
 287		if (hc) {
 288			__unlink_name(cell);
 289			dm_put(hc->md);
 290			goto bad;
 291		}
 292		__link_uuid(cell);
 293	}
 294	dm_get(md);
 295	mutex_lock(&dm_hash_cells_mutex);
 296	dm_set_mdptr(md, cell);
 297	mutex_unlock(&dm_hash_cells_mutex);
 298	up_write(&_hash_lock);
 299
 300	return 0;
 301
 302 bad:
 303	up_write(&_hash_lock);
 304	free_cell(cell);
 305	return -EBUSY;
 306}
 307
 308static struct dm_table *__hash_remove(struct hash_cell *hc)
 309{
 310	struct dm_table *table;
 311	int srcu_idx;
 312
 313	lockdep_assert_held(&_hash_lock);
 314
 315	/* remove from the dev trees */
 316	__unlink_name(hc);
 317	__unlink_uuid(hc);
 318	mutex_lock(&dm_hash_cells_mutex);
 319	dm_set_mdptr(hc->md, NULL);
 320	mutex_unlock(&dm_hash_cells_mutex);
 321
 322	table = dm_get_live_table(hc->md, &srcu_idx);
 323	if (table)
 324		dm_table_event(table);
 325	dm_put_live_table(hc->md, srcu_idx);
 326
 327	table = NULL;
 328	if (hc->new_map)
 329		table = hc->new_map;
 330	dm_put(hc->md);
 331	free_cell(hc);
 332
 333	return table;
 334}
 335
 336static void dm_hash_remove_all(bool keep_open_devices, bool mark_deferred, bool only_deferred)
 337{
 338	int dev_skipped;
 339	struct rb_node *n;
 340	struct hash_cell *hc;
 341	struct mapped_device *md;
 342	struct dm_table *t;
 343
 344retry:
 345	dev_skipped = 0;
 346
 347	down_write(&_hash_lock);
 348
 349	for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
 350		hc = container_of(n, struct hash_cell, name_node);
 351		md = hc->md;
 352		dm_get(md);
 353
 354		if (keep_open_devices &&
 355		    dm_lock_for_deletion(md, mark_deferred, only_deferred)) {
 356			dm_put(md);
 357			dev_skipped++;
 358			continue;
 359		}
 360
 361		t = __hash_remove(hc);
 362
 363		up_write(&_hash_lock);
 364
 365		if (t) {
 366			dm_sync_table(md);
 367			dm_table_destroy(t);
 368		}
 369		dm_ima_measure_on_device_remove(md, true);
 370		dm_put(md);
 371		if (likely(keep_open_devices))
 372			dm_destroy(md);
 373		else
 374			dm_destroy_immediate(md);
 375
 376		/*
 377		 * Some mapped devices may be using other mapped
 378		 * devices, so repeat until we make no further
 379		 * progress.  If a new mapped device is created
 380		 * here it will also get removed.
 381		 */
 382		goto retry;
 383	}
 384
 385	up_write(&_hash_lock);
 386
 387	if (dev_skipped)
 388		DMWARN("remove_all left %d open device(s)", dev_skipped);
 389}
 390
 391/*
 392 * Set the uuid of a hash_cell that isn't already set.
 393 */
 394static void __set_cell_uuid(struct hash_cell *hc, char *new_uuid)
 395{
 396	mutex_lock(&dm_hash_cells_mutex);
 397	hc->uuid = new_uuid;
 398	mutex_unlock(&dm_hash_cells_mutex);
 399
 400	__link_uuid(hc);
 401}
 402
 403/*
 404 * Changes the name of a hash_cell and returns the old name for
 405 * the caller to free.
 406 */
 407static char *__change_cell_name(struct hash_cell *hc, char *new_name)
 408{
 409	char *old_name;
 410
 411	/*
 412	 * Rename and move the name cell.
 413	 */
 414	__unlink_name(hc);
 415	old_name = hc->name;
 416
 417	mutex_lock(&dm_hash_cells_mutex);
 418	hc->name = new_name;
 419	mutex_unlock(&dm_hash_cells_mutex);
 420
 421	__link_name(hc);
 422
 423	return old_name;
 424}
 425
 426static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
 427					    const char *new)
 428{
 429	char *new_data, *old_name = NULL;
 430	struct hash_cell *hc;
 431	struct dm_table *table;
 432	struct mapped_device *md;
 433	unsigned int change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
 434	int srcu_idx;
 435
 436	/*
 437	 * duplicate new.
 438	 */
 439	new_data = kstrdup(new, GFP_KERNEL);
 440	if (!new_data)
 441		return ERR_PTR(-ENOMEM);
 442
 443	down_write(&_hash_lock);
 444
 445	/*
 446	 * Is new free ?
 447	 */
 448	if (change_uuid)
 449		hc = __get_uuid_cell(new);
 450	else
 451		hc = __get_name_cell(new);
 452
 453	if (hc) {
 454		DMERR("Unable to change %s on mapped device %s to one that already exists: %s",
 455		      change_uuid ? "uuid" : "name",
 456		      param->name, new);
 457		dm_put(hc->md);
 458		up_write(&_hash_lock);
 459		kfree(new_data);
 460		return ERR_PTR(-EBUSY);
 461	}
 462
 463	/*
 464	 * Is there such a device as 'old' ?
 465	 */
 466	hc = __get_name_cell(param->name);
 467	if (!hc) {
 468		DMERR("Unable to rename non-existent device, %s to %s%s",
 469		      param->name, change_uuid ? "uuid " : "", new);
 470		up_write(&_hash_lock);
 471		kfree(new_data);
 472		return ERR_PTR(-ENXIO);
 473	}
 474
 475	/*
 476	 * Does this device already have a uuid?
 477	 */
 478	if (change_uuid && hc->uuid) {
 479		DMERR("Unable to change uuid of mapped device %s to %s "
 480		      "because uuid is already set to %s",
 481		      param->name, new, hc->uuid);
 482		dm_put(hc->md);
 483		up_write(&_hash_lock);
 484		kfree(new_data);
 485		return ERR_PTR(-EINVAL);
 486	}
 487
 488	if (change_uuid)
 489		__set_cell_uuid(hc, new_data);
 490	else
 491		old_name = __change_cell_name(hc, new_data);
 492
 493	/*
 494	 * Wake up any dm event waiters.
 495	 */
 496	table = dm_get_live_table(hc->md, &srcu_idx);
 497	if (table)
 498		dm_table_event(table);
 499	dm_put_live_table(hc->md, srcu_idx);
 500
 501	if (!dm_kobject_uevent(hc->md, KOBJ_CHANGE, param->event_nr, false))
 502		param->flags |= DM_UEVENT_GENERATED_FLAG;
 503
 504	md = hc->md;
 505
 506	dm_ima_measure_on_device_rename(md);
 507
 508	up_write(&_hash_lock);
 509	kfree(old_name);
 510
 511	return md;
 512}
 513
 514void dm_deferred_remove(void)
 515{
 516	dm_hash_remove_all(true, false, true);
 517}
 518
 519/*
 520 *---------------------------------------------------------------
 521 * Implementation of the ioctl commands
 522 *---------------------------------------------------------------
 523 */
 524/*
 525 * All the ioctl commands get dispatched to functions with this
 526 * prototype.
 527 */
 528typedef int (*ioctl_fn)(struct file *filp, struct dm_ioctl *param, size_t param_size);
 529
 530static int remove_all(struct file *filp, struct dm_ioctl *param, size_t param_size)
 531{
 532	dm_hash_remove_all(true, !!(param->flags & DM_DEFERRED_REMOVE), false);
 533	param->data_size = 0;
 534	return 0;
 535}
 536
 537/*
 538 * Round up the ptr to an 8-byte boundary.
 539 */
 540#define ALIGN_MASK 7
 541static inline size_t align_val(size_t val)
 542{
 543	return (val + ALIGN_MASK) & ~ALIGN_MASK;
 544}
 545static inline void *align_ptr(void *ptr)
 546{
 547	return (void *)align_val((size_t)ptr);
 548}
 549
 550/*
 551 * Retrieves the data payload buffer from an already allocated
 552 * struct dm_ioctl.
 553 */
 554static void *get_result_buffer(struct dm_ioctl *param, size_t param_size,
 555			       size_t *len)
 556{
 557	param->data_start = align_ptr(param + 1) - (void *) param;
 558
 559	if (param->data_start < param_size)
 560		*len = param_size - param->data_start;
 561	else
 562		*len = 0;
 563
 564	return ((void *) param) + param->data_start;
 565}
 566
 567static bool filter_device(struct hash_cell *hc, const char *pfx_name, const char *pfx_uuid)
 568{
 569	const char *val;
 570	size_t val_len, pfx_len;
 571
 572	val = hc->name;
 573	val_len = strlen(val);
 574	pfx_len = strnlen(pfx_name, DM_NAME_LEN);
 575	if (pfx_len > val_len)
 576		return false;
 577	if (memcmp(val, pfx_name, pfx_len))
 578		return false;
 579
 580	val = hc->uuid ? hc->uuid : "";
 581	val_len = strlen(val);
 582	pfx_len = strnlen(pfx_uuid, DM_UUID_LEN);
 583	if (pfx_len > val_len)
 584		return false;
 585	if (memcmp(val, pfx_uuid, pfx_len))
 586		return false;
 587
 588	return true;
 589}
 590
 591static int list_devices(struct file *filp, struct dm_ioctl *param, size_t param_size)
 592{
 593	struct rb_node *n;
 594	struct hash_cell *hc;
 595	size_t len, needed = 0;
 596	struct gendisk *disk;
 597	struct dm_name_list *orig_nl, *nl, *old_nl = NULL;
 598	uint32_t *event_nr;
 599
 600	down_write(&_hash_lock);
 601
 602	/*
 603	 * Loop through all the devices working out how much
 604	 * space we need.
 605	 */
 606	for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
 607		hc = container_of(n, struct hash_cell, name_node);
 608		if (!filter_device(hc, param->name, param->uuid))
 609			continue;
 610		needed += align_val(offsetof(struct dm_name_list, name) + strlen(hc->name) + 1);
 611		needed += align_val(sizeof(uint32_t) * 2);
 612		if (param->flags & DM_UUID_FLAG && hc->uuid)
 613			needed += align_val(strlen(hc->uuid) + 1);
 614	}
 615
 616	/*
 617	 * Grab our output buffer.
 618	 */
 619	nl = orig_nl = get_result_buffer(param, param_size, &len);
 620	if (len < needed || len < sizeof(nl->dev)) {
 621		param->flags |= DM_BUFFER_FULL_FLAG;
 622		goto out;
 623	}
 624	param->data_size = param->data_start + needed;
 625
 626	nl->dev = 0;	/* Flags no data */
 627
 628	/*
 629	 * Now loop through filling out the names.
 630	 */
 631	for (n = rb_first(&name_rb_tree); n; n = rb_next(n)) {
 632		void *uuid_ptr;
 633
 634		hc = container_of(n, struct hash_cell, name_node);
 635		if (!filter_device(hc, param->name, param->uuid))
 636			continue;
 637		if (old_nl)
 638			old_nl->next = (uint32_t) ((void *) nl -
 639						   (void *) old_nl);
 640		disk = dm_disk(hc->md);
 641		nl->dev = huge_encode_dev(disk_devt(disk));
 642		nl->next = 0;
 643		strcpy(nl->name, hc->name);
 644
 645		old_nl = nl;
 646		event_nr = align_ptr(nl->name + strlen(hc->name) + 1);
 647		event_nr[0] = dm_get_event_nr(hc->md);
 648		event_nr[1] = 0;
 649		uuid_ptr = align_ptr(event_nr + 2);
 650		if (param->flags & DM_UUID_FLAG) {
 651			if (hc->uuid) {
 652				event_nr[1] |= DM_NAME_LIST_FLAG_HAS_UUID;
 653				strcpy(uuid_ptr, hc->uuid);
 654				uuid_ptr = align_ptr(uuid_ptr + strlen(hc->uuid) + 1);
 655			} else {
 656				event_nr[1] |= DM_NAME_LIST_FLAG_DOESNT_HAVE_UUID;
 657			}
 658		}
 659		nl = uuid_ptr;
 660	}
 661	/*
 662	 * If mismatch happens, security may be compromised due to buffer
 663	 * overflow, so it's better to crash.
 664	 */
 665	BUG_ON((char *)nl - (char *)orig_nl != needed);
 666
 667 out:
 668	up_write(&_hash_lock);
 669	return 0;
 670}
 671
 672static void list_version_get_needed(struct target_type *tt, void *needed_param)
 673{
 674	size_t *needed = needed_param;
 675
 676	*needed += sizeof(struct dm_target_versions);
 677	*needed += strlen(tt->name) + 1;
 678	*needed += ALIGN_MASK;
 679}
 680
 681static void list_version_get_info(struct target_type *tt, void *param)
 682{
 683	struct vers_iter *info = param;
 684
 685	/* Check space - it might have changed since the first iteration */
 686	if ((char *)info->vers + sizeof(tt->version) + strlen(tt->name) + 1 > info->end) {
 687		info->flags = DM_BUFFER_FULL_FLAG;
 688		return;
 689	}
 690
 691	if (info->old_vers)
 692		info->old_vers->next = (uint32_t) ((void *)info->vers - (void *)info->old_vers);
 693
 694	info->vers->version[0] = tt->version[0];
 695	info->vers->version[1] = tt->version[1];
 696	info->vers->version[2] = tt->version[2];
 697	info->vers->next = 0;
 698	strcpy(info->vers->name, tt->name);
 699
 700	info->old_vers = info->vers;
 701	info->vers = align_ptr((void *)(info->vers + 1) + strlen(tt->name) + 1);
 702}
 703
 704static int __list_versions(struct dm_ioctl *param, size_t param_size, const char *name)
 705{
 706	size_t len, needed = 0;
 707	struct dm_target_versions *vers;
 708	struct vers_iter iter_info;
 709	struct target_type *tt = NULL;
 710
 711	if (name) {
 712		tt = dm_get_target_type(name);
 713		if (!tt)
 714			return -EINVAL;
 715	}
 716
 717	/*
 718	 * Loop through all the devices working out how much
 719	 * space we need.
 720	 */
 721	if (!tt)
 722		dm_target_iterate(list_version_get_needed, &needed);
 723	else
 724		list_version_get_needed(tt, &needed);
 725
 726	/*
 727	 * Grab our output buffer.
 728	 */
 729	vers = get_result_buffer(param, param_size, &len);
 730	if (len < needed) {
 731		param->flags |= DM_BUFFER_FULL_FLAG;
 732		goto out;
 733	}
 734	param->data_size = param->data_start + needed;
 735
 736	iter_info.param_size = param_size;
 737	iter_info.old_vers = NULL;
 738	iter_info.vers = vers;
 739	iter_info.flags = 0;
 740	iter_info.end = (char *)vers + needed;
 741
 742	/*
 743	 * Now loop through filling out the names & versions.
 744	 */
 745	if (!tt)
 746		dm_target_iterate(list_version_get_info, &iter_info);
 747	else
 748		list_version_get_info(tt, &iter_info);
 749	param->flags |= iter_info.flags;
 750
 751 out:
 752	if (tt)
 753		dm_put_target_type(tt);
 754	return 0;
 755}
 756
 757static int list_versions(struct file *filp, struct dm_ioctl *param, size_t param_size)
 758{
 759	return __list_versions(param, param_size, NULL);
 760}
 761
 762static int get_target_version(struct file *filp, struct dm_ioctl *param, size_t param_size)
 763{
 764	return __list_versions(param, param_size, param->name);
 765}
 766
 767static int check_name(const char *name)
 768{
 769	if (strchr(name, '/')) {
 770		DMERR("device name cannot contain '/'");
 771		return -EINVAL;
 772	}
 773
 774	if (strcmp(name, DM_CONTROL_NODE) == 0 ||
 775	    strcmp(name, ".") == 0 ||
 776	    strcmp(name, "..") == 0) {
 777		DMERR("device name cannot be \"%s\", \".\", or \"..\"", DM_CONTROL_NODE);
 778		return -EINVAL;
 779	}
 780
 781	return 0;
 782}
 783
 784/*
 785 * On successful return, the caller must not attempt to acquire
 786 * _hash_lock without first calling dm_put_live_table, because dm_table_destroy
 787 * waits for this dm_put_live_table and could be called under this lock.
 788 */
 789static struct dm_table *dm_get_inactive_table(struct mapped_device *md, int *srcu_idx)
 790{
 791	struct hash_cell *hc;
 792	struct dm_table *table = NULL;
 793
 794	/* increment rcu count, we don't care about the table pointer */
 795	dm_get_live_table(md, srcu_idx);
 796
 797	down_read(&_hash_lock);
 798	hc = dm_get_mdptr(md);
 799	if (!hc) {
 800		DMERR("device has been removed from the dev hash table.");
 801		goto out;
 802	}
 803
 804	table = hc->new_map;
 805
 806out:
 807	up_read(&_hash_lock);
 808
 809	return table;
 810}
 811
 812static struct dm_table *dm_get_live_or_inactive_table(struct mapped_device *md,
 813						      struct dm_ioctl *param,
 814						      int *srcu_idx)
 815{
 816	return (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) ?
 817		dm_get_inactive_table(md, srcu_idx) : dm_get_live_table(md, srcu_idx);
 818}
 819
 820/*
 821 * Fills in a dm_ioctl structure, ready for sending back to
 822 * userland.
 823 */
 824static void __dev_status(struct mapped_device *md, struct dm_ioctl *param)
 825{
 826	struct gendisk *disk = dm_disk(md);
 827	struct dm_table *table;
 828	int srcu_idx;
 829
 830	param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
 831			  DM_ACTIVE_PRESENT_FLAG | DM_INTERNAL_SUSPEND_FLAG);
 832
 833	if (dm_suspended_md(md))
 834		param->flags |= DM_SUSPEND_FLAG;
 835
 836	if (dm_suspended_internally_md(md))
 837		param->flags |= DM_INTERNAL_SUSPEND_FLAG;
 838
 839	if (dm_test_deferred_remove_flag(md))
 840		param->flags |= DM_DEFERRED_REMOVE;
 841
 842	param->dev = huge_encode_dev(disk_devt(disk));
 843
 844	/*
 845	 * Yes, this will be out of date by the time it gets back
 846	 * to userland, but it is still very useful for
 847	 * debugging.
 848	 */
 849	param->open_count = dm_open_count(md);
 850
 851	param->event_nr = dm_get_event_nr(md);
 852	param->target_count = 0;
 853
 854	table = dm_get_live_table(md, &srcu_idx);
 855	if (table) {
 856		if (!(param->flags & DM_QUERY_INACTIVE_TABLE_FLAG)) {
 857			if (get_disk_ro(disk))
 858				param->flags |= DM_READONLY_FLAG;
 859			param->target_count = table->num_targets;
 860		}
 861
 862		param->flags |= DM_ACTIVE_PRESENT_FLAG;
 863	}
 864	dm_put_live_table(md, srcu_idx);
 865
 866	if (param->flags & DM_QUERY_INACTIVE_TABLE_FLAG) {
 867		int srcu_idx;
 868
 869		table = dm_get_inactive_table(md, &srcu_idx);
 870		if (table) {
 871			if (!(dm_table_get_mode(table) & BLK_OPEN_WRITE))
 872				param->flags |= DM_READONLY_FLAG;
 873			param->target_count = table->num_targets;
 874		}
 875		dm_put_live_table(md, srcu_idx);
 876	}
 877}
 878
 879static int dev_create(struct file *filp, struct dm_ioctl *param, size_t param_size)
 880{
 881	int r, m = DM_ANY_MINOR;
 882	struct mapped_device *md;
 883
 884	r = check_name(param->name);
 885	if (r)
 886		return r;
 887
 888	if (param->flags & DM_PERSISTENT_DEV_FLAG)
 889		m = MINOR(huge_decode_dev(param->dev));
 890
 891	r = dm_create(m, &md);
 892	if (r)
 893		return r;
 894
 895	r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
 896	if (r) {
 897		dm_put(md);
 898		dm_destroy(md);
 899		return r;
 900	}
 901
 902	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
 903
 904	__dev_status(md, param);
 905
 906	dm_put(md);
 907
 908	return 0;
 909}
 910
 911/*
 912 * Always use UUID for lookups if it's present, otherwise use name or dev.
 913 */
 914static struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param)
 915{
 916	struct hash_cell *hc = NULL;
 917
 918	if (*param->uuid) {
 919		if (*param->name || param->dev) {
 920			DMERR("Invalid ioctl structure: uuid %s, name %s, dev %llx",
 921			      param->uuid, param->name, (unsigned long long)param->dev);
 922			return NULL;
 923		}
 924
 925		hc = __get_uuid_cell(param->uuid);
 926		if (!hc)
 927			return NULL;
 928	} else if (*param->name) {
 929		if (param->dev) {
 930			DMERR("Invalid ioctl structure: name %s, dev %llx",
 931			      param->name, (unsigned long long)param->dev);
 932			return NULL;
 933		}
 934
 935		hc = __get_name_cell(param->name);
 936		if (!hc)
 937			return NULL;
 938	} else if (param->dev) {
 939		hc = __get_dev_cell(param->dev);
 940		if (!hc)
 941			return NULL;
 942	} else
 943		return NULL;
 944
 945	/*
 946	 * Sneakily write in both the name and the uuid
 947	 * while we have the cell.
 948	 */
 949	strscpy(param->name, hc->name, sizeof(param->name));
 950	if (hc->uuid)
 951		strscpy(param->uuid, hc->uuid, sizeof(param->uuid));
 952	else
 953		param->uuid[0] = '\0';
 954
 955	if (hc->new_map)
 956		param->flags |= DM_INACTIVE_PRESENT_FLAG;
 957	else
 958		param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
 959
 960	return hc;
 961}
 962
 963static struct mapped_device *find_device(struct dm_ioctl *param)
 964{
 965	struct hash_cell *hc;
 966	struct mapped_device *md = NULL;
 967
 968	down_read(&_hash_lock);
 969	hc = __find_device_hash_cell(param);
 970	if (hc)
 971		md = hc->md;
 972	up_read(&_hash_lock);
 973
 974	return md;
 975}
 976
 977static int dev_remove(struct file *filp, struct dm_ioctl *param, size_t param_size)
 978{
 979	struct hash_cell *hc;
 980	struct mapped_device *md;
 981	int r;
 982	struct dm_table *t;
 983
 984	down_write(&_hash_lock);
 985	hc = __find_device_hash_cell(param);
 986
 987	if (!hc) {
 988		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
 989		up_write(&_hash_lock);
 990		return -ENXIO;
 991	}
 992
 993	md = hc->md;
 994
 995	/*
 996	 * Ensure the device is not open and nothing further can open it.
 997	 */
 998	r = dm_lock_for_deletion(md, !!(param->flags & DM_DEFERRED_REMOVE), false);
 999	if (r) {
1000		if (r == -EBUSY && param->flags & DM_DEFERRED_REMOVE) {
1001			up_write(&_hash_lock);
1002			dm_put(md);
1003			return 0;
1004		}
1005		DMDEBUG_LIMIT("unable to remove open device %s", hc->name);
1006		up_write(&_hash_lock);
1007		dm_put(md);
1008		return r;
1009	}
1010
1011	t = __hash_remove(hc);
1012	up_write(&_hash_lock);
1013
1014	if (t) {
1015		dm_sync_table(md);
1016		dm_table_destroy(t);
1017	}
1018
1019	param->flags &= ~DM_DEFERRED_REMOVE;
1020
1021	dm_ima_measure_on_device_remove(md, false);
1022
1023	if (!dm_kobject_uevent(md, KOBJ_REMOVE, param->event_nr, false))
1024		param->flags |= DM_UEVENT_GENERATED_FLAG;
1025
1026	dm_put(md);
1027	dm_destroy(md);
1028	return 0;
1029}
1030
1031/*
1032 * Check a string doesn't overrun the chunk of
1033 * memory we copied from userland.
1034 */
1035static int invalid_str(char *str, void *end)
1036{
1037	while ((void *) str < end)
1038		if (!*str++)
1039			return 0;
1040
1041	return -EINVAL;
1042}
1043
1044static int dev_rename(struct file *filp, struct dm_ioctl *param, size_t param_size)
1045{
1046	int r;
1047	char *new_data = (char *) param + param->data_start;
1048	struct mapped_device *md;
1049	unsigned int change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
1050
1051	if (new_data < param->data ||
1052	    invalid_str(new_data, (void *) param + param_size) || !*new_data ||
1053	    strlen(new_data) > (change_uuid ? DM_UUID_LEN - 1 : DM_NAME_LEN - 1)) {
1054		DMERR("Invalid new mapped device name or uuid string supplied.");
1055		return -EINVAL;
1056	}
1057
1058	if (!change_uuid) {
1059		r = check_name(new_data);
1060		if (r)
1061			return r;
1062	}
1063
1064	md = dm_hash_rename(param, new_data);
1065	if (IS_ERR(md))
1066		return PTR_ERR(md);
1067
1068	__dev_status(md, param);
1069	dm_put(md);
1070
1071	return 0;
1072}
1073
1074static int dev_set_geometry(struct file *filp, struct dm_ioctl *param, size_t param_size)
1075{
1076	int r = -EINVAL, x;
1077	struct mapped_device *md;
1078	struct hd_geometry geometry;
1079	unsigned long indata[4];
1080	char *geostr = (char *) param + param->data_start;
1081	char dummy;
1082
1083	md = find_device(param);
1084	if (!md)
1085		return -ENXIO;
1086
1087	if (geostr < param->data ||
1088	    invalid_str(geostr, (void *) param + param_size)) {
1089		DMERR("Invalid geometry supplied.");
1090		goto out;
1091	}
1092
1093	x = sscanf(geostr, "%lu %lu %lu %lu%c", indata,
1094		   indata + 1, indata + 2, indata + 3, &dummy);
1095
1096	if (x != 4) {
1097		DMERR("Unable to interpret geometry settings.");
1098		goto out;
1099	}
1100
1101	if (indata[0] > 65535 || indata[1] > 255 || indata[2] > 255) {
1102		DMERR("Geometry exceeds range limits.");
1103		goto out;
1104	}
1105
1106	geometry.cylinders = indata[0];
1107	geometry.heads = indata[1];
1108	geometry.sectors = indata[2];
1109	geometry.start = indata[3];
1110
1111	r = dm_set_geometry(md, &geometry);
1112
1113	param->data_size = 0;
1114
1115out:
1116	dm_put(md);
1117	return r;
1118}
1119
1120static int do_suspend(struct dm_ioctl *param)
1121{
1122	int r = 0;
1123	unsigned int suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
1124	struct mapped_device *md;
1125
1126	md = find_device(param);
1127	if (!md)
1128		return -ENXIO;
1129
1130	if (param->flags & DM_SKIP_LOCKFS_FLAG)
1131		suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
1132	if (param->flags & DM_NOFLUSH_FLAG)
1133		suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
1134
1135	if (!dm_suspended_md(md)) {
1136		r = dm_suspend(md, suspend_flags);
1137		if (r)
1138			goto out;
1139	}
1140
1141	__dev_status(md, param);
1142
1143out:
1144	dm_put(md);
1145
1146	return r;
1147}
1148
1149static int do_resume(struct dm_ioctl *param)
1150{
1151	int r = 0;
1152	unsigned int suspend_flags = DM_SUSPEND_LOCKFS_FLAG;
1153	struct hash_cell *hc;
1154	struct mapped_device *md;
1155	struct dm_table *new_map, *old_map = NULL;
1156	bool need_resize_uevent = false;
1157
1158	down_write(&_hash_lock);
1159
1160	hc = __find_device_hash_cell(param);
1161	if (!hc) {
1162		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
1163		up_write(&_hash_lock);
1164		return -ENXIO;
1165	}
1166
1167	md = hc->md;
1168
1169	new_map = hc->new_map;
1170	hc->new_map = NULL;
1171	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
1172
1173	up_write(&_hash_lock);
1174
1175	/* Do we need to load a new map ? */
1176	if (new_map) {
1177		sector_t old_size, new_size;
1178
1179		/* Suspend if it isn't already suspended */
1180		if (param->flags & DM_SKIP_LOCKFS_FLAG)
1181			suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
1182		if (param->flags & DM_NOFLUSH_FLAG)
1183			suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
1184		if (!dm_suspended_md(md)) {
1185			r = dm_suspend(md, suspend_flags);
1186			if (r) {
1187				down_write(&_hash_lock);
1188				hc = dm_get_mdptr(md);
1189				if (hc && !hc->new_map) {
1190					hc->new_map = new_map;
1191					new_map = NULL;
1192				} else {
1193					r = -ENXIO;
1194				}
1195				up_write(&_hash_lock);
1196				if (new_map) {
1197					dm_sync_table(md);
1198					dm_table_destroy(new_map);
1199				}
1200				dm_put(md);
1201				return r;
1202			}
1203		}
1204
1205		old_size = dm_get_size(md);
1206		old_map = dm_swap_table(md, new_map);
1207		if (IS_ERR(old_map)) {
1208			dm_sync_table(md);
1209			dm_table_destroy(new_map);
1210			dm_put(md);
1211			return PTR_ERR(old_map);
1212		}
1213		new_size = dm_get_size(md);
1214		if (old_size && new_size && old_size != new_size)
1215			need_resize_uevent = true;
1216
1217		if (dm_table_get_mode(new_map) & BLK_OPEN_WRITE)
1218			set_disk_ro(dm_disk(md), 0);
1219		else
1220			set_disk_ro(dm_disk(md), 1);
1221	}
1222
1223	if (dm_suspended_md(md)) {
1224		r = dm_resume(md);
1225		if (!r) {
1226			dm_ima_measure_on_device_resume(md, new_map ? true : false);
1227
1228			if (!dm_kobject_uevent(md, KOBJ_CHANGE, param->event_nr, need_resize_uevent))
1229				param->flags |= DM_UEVENT_GENERATED_FLAG;
1230		}
1231	}
1232
1233	/*
1234	 * Since dm_swap_table synchronizes RCU, nobody should be in
1235	 * read-side critical section already.
1236	 */
1237	if (old_map)
1238		dm_table_destroy(old_map);
1239
1240	if (!r)
1241		__dev_status(md, param);
1242
1243	dm_put(md);
1244	return r;
1245}
1246
1247/*
1248 * Set or unset the suspension state of a device.
1249 * If the device already is in the requested state we just return its status.
1250 */
1251static int dev_suspend(struct file *filp, struct dm_ioctl *param, size_t param_size)
1252{
1253	if (param->flags & DM_SUSPEND_FLAG)
1254		return do_suspend(param);
1255
1256	return do_resume(param);
1257}
1258
1259/*
1260 * Copies device info back to user space, used by
1261 * the create and info ioctls.
1262 */
1263static int dev_status(struct file *filp, struct dm_ioctl *param, size_t param_size)
1264{
1265	struct mapped_device *md;
1266
1267	md = find_device(param);
1268	if (!md)
1269		return -ENXIO;
1270
1271	__dev_status(md, param);
1272	dm_put(md);
1273
1274	return 0;
1275}
1276
1277/*
1278 * Build up the status struct for each target
1279 */
1280static void retrieve_status(struct dm_table *table,
1281			    struct dm_ioctl *param, size_t param_size)
1282{
1283	unsigned int i, num_targets;
1284	struct dm_target_spec *spec;
1285	char *outbuf, *outptr;
1286	status_type_t type;
1287	size_t remaining, len, used = 0;
1288	unsigned int status_flags = 0;
1289
1290	outptr = outbuf = get_result_buffer(param, param_size, &len);
1291
1292	if (param->flags & DM_STATUS_TABLE_FLAG)
1293		type = STATUSTYPE_TABLE;
1294	else if (param->flags & DM_IMA_MEASUREMENT_FLAG)
1295		type = STATUSTYPE_IMA;
1296	else
1297		type = STATUSTYPE_INFO;
1298
1299	/* Get all the target info */
1300	num_targets = table->num_targets;
1301	for (i = 0; i < num_targets; i++) {
1302		struct dm_target *ti = dm_table_get_target(table, i);
1303		size_t l;
1304
1305		remaining = len - (outptr - outbuf);
1306		if (remaining <= sizeof(struct dm_target_spec)) {
1307			param->flags |= DM_BUFFER_FULL_FLAG;
1308			break;
1309		}
1310
1311		spec = (struct dm_target_spec *) outptr;
1312
1313		spec->status = 0;
1314		spec->sector_start = ti->begin;
1315		spec->length = ti->len;
1316		strscpy_pad(spec->target_type, ti->type->name,
1317			sizeof(spec->target_type));
1318
1319		outptr += sizeof(struct dm_target_spec);
1320		remaining = len - (outptr - outbuf);
1321		if (remaining <= 0) {
1322			param->flags |= DM_BUFFER_FULL_FLAG;
1323			break;
1324		}
1325
1326		/* Get the status/table string from the target driver */
1327		if (ti->type->status) {
1328			if (param->flags & DM_NOFLUSH_FLAG)
1329				status_flags |= DM_STATUS_NOFLUSH_FLAG;
1330			ti->type->status(ti, type, status_flags, outptr, remaining);
1331		} else
1332			outptr[0] = '\0';
1333
1334		l = strlen(outptr) + 1;
1335		if (l == remaining) {
1336			param->flags |= DM_BUFFER_FULL_FLAG;
1337			break;
1338		}
1339
1340		outptr += l;
1341		used = param->data_start + (outptr - outbuf);
1342
1343		outptr = align_ptr(outptr);
1344		spec->next = outptr - outbuf;
1345	}
1346
1347	if (used)
1348		param->data_size = used;
1349
1350	param->target_count = num_targets;
1351}
1352
1353/*
1354 * Wait for a device to report an event
1355 */
1356static int dev_wait(struct file *filp, struct dm_ioctl *param, size_t param_size)
1357{
1358	int r = 0;
1359	struct mapped_device *md;
1360	struct dm_table *table;
1361	int srcu_idx;
1362
1363	md = find_device(param);
1364	if (!md)
1365		return -ENXIO;
1366
1367	/*
1368	 * Wait for a notification event
1369	 */
1370	if (dm_wait_event(md, param->event_nr)) {
1371		r = -ERESTARTSYS;
1372		goto out;
1373	}
1374
1375	/*
1376	 * The userland program is going to want to know what
1377	 * changed to trigger the event, so we may as well tell
1378	 * him and save an ioctl.
1379	 */
1380	__dev_status(md, param);
1381
1382	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
1383	if (table)
1384		retrieve_status(table, param, param_size);
1385	dm_put_live_table(md, srcu_idx);
1386
1387out:
1388	dm_put(md);
1389
1390	return r;
1391}
1392
1393/*
1394 * Remember the global event number and make it possible to poll
1395 * for further events.
1396 */
1397static int dev_arm_poll(struct file *filp, struct dm_ioctl *param, size_t param_size)
1398{
1399	struct dm_file *priv = filp->private_data;
1400
1401	priv->global_event_nr = atomic_read(&dm_global_event_nr);
1402
1403	return 0;
1404}
1405
1406static inline blk_mode_t get_mode(struct dm_ioctl *param)
1407{
1408	blk_mode_t mode = BLK_OPEN_READ | BLK_OPEN_WRITE;
1409
1410	if (param->flags & DM_READONLY_FLAG)
1411		mode = BLK_OPEN_READ;
1412
1413	return mode;
1414}
1415
1416static int next_target(struct dm_target_spec *last, uint32_t next, const char *end,
1417		       struct dm_target_spec **spec, char **target_params)
1418{
1419	static_assert(__alignof__(struct dm_target_spec) <= 8,
1420		"struct dm_target_spec must not require more than 8-byte alignment");
1421
1422	/*
1423	 * Number of bytes remaining, starting with last. This is always
1424	 * sizeof(struct dm_target_spec) or more, as otherwise *last was
1425	 * out of bounds already.
1426	 */
1427	size_t remaining = end - (char *)last;
1428
1429	/*
1430	 * There must be room for both the next target spec and the
1431	 * NUL-terminator of the target itself.
1432	 */
1433	if (remaining - sizeof(struct dm_target_spec) <= next) {
1434		DMERR("Target spec extends beyond end of parameters");
1435		return -EINVAL;
1436	}
1437
1438	if (next % __alignof__(struct dm_target_spec)) {
1439		DMERR("Next dm_target_spec (offset %u) is not %zu-byte aligned",
1440		      next, __alignof__(struct dm_target_spec));
1441		return -EINVAL;
1442	}
1443
1444	*spec = (struct dm_target_spec *) ((unsigned char *) last + next);
1445	*target_params = (char *) (*spec + 1);
1446
1447	return 0;
1448}
1449
1450static int populate_table(struct dm_table *table,
1451			  struct dm_ioctl *param, size_t param_size)
1452{
1453	int r;
1454	unsigned int i = 0;
1455	struct dm_target_spec *spec = (struct dm_target_spec *) param;
1456	uint32_t next = param->data_start;
1457	const char *const end = (const char *) param + param_size;
1458	char *target_params;
1459	size_t min_size = sizeof(struct dm_ioctl);
1460
1461	if (!param->target_count) {
1462		DMERR("%s: no targets specified", __func__);
1463		return -EINVAL;
1464	}
1465
1466	for (i = 0; i < param->target_count; i++) {
1467		const char *nul_terminator;
1468
1469		if (next < min_size) {
1470			DMERR("%s: next target spec (offset %u) overlaps %s",
1471			      __func__, next, i ? "previous target" : "'struct dm_ioctl'");
1472			return -EINVAL;
1473		}
1474
1475		r = next_target(spec, next, end, &spec, &target_params);
1476		if (r) {
1477			DMERR("unable to find target");
1478			return r;
1479		}
1480
1481		nul_terminator = memchr(target_params, 0, (size_t)(end - target_params));
1482		if (nul_terminator == NULL) {
1483			DMERR("%s: target parameters not NUL-terminated", __func__);
1484			return -EINVAL;
1485		}
1486
1487		/* Add 1 for NUL terminator */
1488		min_size = (size_t)(nul_terminator - (const char *)spec) + 1;
1489
1490		r = dm_table_add_target(table, spec->target_type,
1491					(sector_t) spec->sector_start,
1492					(sector_t) spec->length,
1493					target_params);
1494		if (r) {
1495			DMERR("error adding target to table");
1496			return r;
1497		}
1498
1499		next = spec->next;
1500	}
1501
1502	return dm_table_complete(table);
1503}
1504
1505static bool is_valid_type(enum dm_queue_mode cur, enum dm_queue_mode new)
1506{
1507	if (cur == new ||
1508	    (cur == DM_TYPE_BIO_BASED && new == DM_TYPE_DAX_BIO_BASED))
1509		return true;
1510
1511	return false;
1512}
1513
1514static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_size)
1515{
1516	int r;
1517	struct hash_cell *hc;
1518	struct dm_table *t, *old_map = NULL;
1519	struct mapped_device *md;
1520	struct target_type *immutable_target_type;
1521
1522	md = find_device(param);
1523	if (!md)
1524		return -ENXIO;
1525
1526	r = dm_table_create(&t, get_mode(param), param->target_count, md);
1527	if (r)
1528		goto err;
1529
1530	/* Protect md->type and md->queue against concurrent table loads. */
1531	dm_lock_md_type(md);
1532	r = populate_table(t, param, param_size);
1533	if (r)
1534		goto err_unlock_md_type;
1535
1536	dm_ima_measure_on_table_load(t, STATUSTYPE_IMA);
1537
1538	immutable_target_type = dm_get_immutable_target_type(md);
1539	if (immutable_target_type &&
1540	    (immutable_target_type != dm_table_get_immutable_target_type(t)) &&
1541	    !dm_table_get_wildcard_target(t)) {
1542		DMERR("can't replace immutable target type %s",
1543		      immutable_target_type->name);
1544		r = -EINVAL;
1545		goto err_unlock_md_type;
1546	}
1547
1548	if (dm_get_md_type(md) == DM_TYPE_NONE) {
1549		/* setup md->queue to reflect md's type (may block) */
1550		r = dm_setup_md_queue(md, t);
1551		if (r) {
1552			DMERR("unable to set up device queue for new table.");
1553			goto err_unlock_md_type;
1554		}
1555	} else if (!is_valid_type(dm_get_md_type(md), dm_table_get_type(t))) {
1556		DMERR("can't change device type (old=%u vs new=%u) after initial table load.",
1557		      dm_get_md_type(md), dm_table_get_type(t));
1558		r = -EINVAL;
1559		goto err_unlock_md_type;
1560	}
1561
1562	dm_unlock_md_type(md);
1563
1564	/* stage inactive table */
1565	down_write(&_hash_lock);
1566	hc = dm_get_mdptr(md);
1567	if (!hc) {
1568		DMERR("device has been removed from the dev hash table.");
1569		up_write(&_hash_lock);
1570		r = -ENXIO;
1571		goto err_destroy_table;
1572	}
1573
1574	if (hc->new_map)
1575		old_map = hc->new_map;
1576	hc->new_map = t;
1577	up_write(&_hash_lock);
1578
1579	param->flags |= DM_INACTIVE_PRESENT_FLAG;
1580	__dev_status(md, param);
1581
1582	if (old_map) {
1583		dm_sync_table(md);
1584		dm_table_destroy(old_map);
1585	}
1586
1587	dm_put(md);
1588
1589	return 0;
1590
1591err_unlock_md_type:
1592	dm_unlock_md_type(md);
1593err_destroy_table:
1594	dm_table_destroy(t);
1595err:
1596	dm_put(md);
1597
1598	return r;
1599}
1600
1601static int table_clear(struct file *filp, struct dm_ioctl *param, size_t param_size)
1602{
1603	struct hash_cell *hc;
1604	struct mapped_device *md;
1605	struct dm_table *old_map = NULL;
1606	bool has_new_map = false;
1607
1608	down_write(&_hash_lock);
1609
1610	hc = __find_device_hash_cell(param);
1611	if (!hc) {
1612		DMDEBUG_LIMIT("device doesn't appear to be in the dev hash table.");
1613		up_write(&_hash_lock);
1614		return -ENXIO;
1615	}
1616
1617	if (hc->new_map) {
1618		old_map = hc->new_map;
1619		hc->new_map = NULL;
1620		has_new_map = true;
1621	}
1622
1623	md = hc->md;
1624	up_write(&_hash_lock);
1625
1626	param->flags &= ~DM_INACTIVE_PRESENT_FLAG;
1627	__dev_status(md, param);
1628
1629	if (old_map) {
1630		dm_sync_table(md);
1631		dm_table_destroy(old_map);
1632	}
1633	dm_ima_measure_on_table_clear(md, has_new_map);
1634	dm_put(md);
1635
1636	return 0;
1637}
1638
1639/*
1640 * Retrieves a list of devices used by a particular dm device.
1641 */
1642static void retrieve_deps(struct dm_table *table,
1643			  struct dm_ioctl *param, size_t param_size)
1644{
1645	unsigned int count = 0;
1646	struct list_head *tmp;
1647	size_t len, needed;
1648	struct dm_dev_internal *dd;
1649	struct dm_target_deps *deps;
1650
1651	down_read(&table->devices_lock);
1652
1653	deps = get_result_buffer(param, param_size, &len);
1654
1655	/*
1656	 * Count the devices.
1657	 */
1658	list_for_each(tmp, dm_table_get_devices(table))
1659		count++;
1660
1661	/*
1662	 * Check we have enough space.
1663	 */
1664	needed = struct_size(deps, dev, count);
1665	if (len < needed) {
1666		param->flags |= DM_BUFFER_FULL_FLAG;
1667		goto out;
1668	}
1669
1670	/*
1671	 * Fill in the devices.
1672	 */
1673	deps->count = count;
1674	count = 0;
1675	list_for_each_entry(dd, dm_table_get_devices(table), list)
1676		deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev);
1677
1678	param->data_size = param->data_start + needed;
1679
1680out:
1681	up_read(&table->devices_lock);
1682}
1683
1684static int table_deps(struct file *filp, struct dm_ioctl *param, size_t param_size)
1685{
1686	struct mapped_device *md;
1687	struct dm_table *table;
1688	int srcu_idx;
1689
1690	md = find_device(param);
1691	if (!md)
1692		return -ENXIO;
1693
1694	__dev_status(md, param);
1695
1696	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
1697	if (table)
1698		retrieve_deps(table, param, param_size);
1699	dm_put_live_table(md, srcu_idx);
1700
1701	dm_put(md);
1702
1703	return 0;
1704}
1705
1706/*
1707 * Return the status of a device as a text string for each
1708 * target.
1709 */
1710static int table_status(struct file *filp, struct dm_ioctl *param, size_t param_size)
1711{
1712	struct mapped_device *md;
1713	struct dm_table *table;
1714	int srcu_idx;
1715
1716	md = find_device(param);
1717	if (!md)
1718		return -ENXIO;
1719
1720	__dev_status(md, param);
1721
1722	table = dm_get_live_or_inactive_table(md, param, &srcu_idx);
1723	if (table)
1724		retrieve_status(table, param, param_size);
1725	dm_put_live_table(md, srcu_idx);
1726
1727	dm_put(md);
1728
1729	return 0;
1730}
1731
1732/*
1733 * Process device-mapper dependent messages.  Messages prefixed with '@'
1734 * are processed by the DM core.  All others are delivered to the target.
1735 * Returns a number <= 1 if message was processed by device mapper.
1736 * Returns 2 if message should be delivered to the target.
1737 */
1738static int message_for_md(struct mapped_device *md, unsigned int argc, char **argv,
1739			  char *result, unsigned int maxlen)
1740{
1741	int r;
1742
1743	if (**argv != '@')
1744		return 2; /* no '@' prefix, deliver to target */
1745
1746	if (!strcasecmp(argv[0], "@cancel_deferred_remove")) {
1747		if (argc != 1) {
1748			DMERR("Invalid arguments for @cancel_deferred_remove");
1749			return -EINVAL;
1750		}
1751		return dm_cancel_deferred_remove(md);
1752	}
1753
1754	r = dm_stats_message(md, argc, argv, result, maxlen);
1755	if (r < 2)
1756		return r;
1757
1758	DMERR("Unsupported message sent to DM core: %s", argv[0]);
1759	return -EINVAL;
1760}
1761
1762/*
1763 * Pass a message to the target that's at the supplied device offset.
1764 */
1765static int target_message(struct file *filp, struct dm_ioctl *param, size_t param_size)
1766{
1767	int r, argc;
1768	char **argv;
1769	struct mapped_device *md;
1770	struct dm_table *table;
1771	struct dm_target *ti;
1772	struct dm_target_msg *tmsg = (void *) param + param->data_start;
1773	size_t maxlen;
1774	char *result = get_result_buffer(param, param_size, &maxlen);
1775	int srcu_idx;
1776
1777	md = find_device(param);
1778	if (!md)
1779		return -ENXIO;
1780
1781	if (tmsg < (struct dm_target_msg *) param->data ||
1782	    invalid_str(tmsg->message, (void *) param + param_size)) {
1783		DMERR("Invalid target message parameters.");
1784		r = -EINVAL;
1785		goto out;
1786	}
1787
1788	r = dm_split_args(&argc, &argv, tmsg->message);
1789	if (r) {
1790		DMERR("Failed to split target message parameters");
1791		goto out;
1792	}
1793
1794	if (!argc) {
1795		DMERR("Empty message received.");
1796		r = -EINVAL;
1797		goto out_argv;
1798	}
1799
1800	r = message_for_md(md, argc, argv, result, maxlen);
1801	if (r <= 1)
1802		goto out_argv;
1803
1804	table = dm_get_live_table(md, &srcu_idx);
1805	if (!table)
1806		goto out_table;
1807
1808	if (dm_deleting_md(md)) {
1809		r = -ENXIO;
1810		goto out_table;
1811	}
1812
1813	ti = dm_table_find_target(table, tmsg->sector);
1814	if (!ti) {
1815		DMERR("Target message sector outside device.");
1816		r = -EINVAL;
1817	} else if (ti->type->message)
1818		r = ti->type->message(ti, argc, argv, result, maxlen);
1819	else {
1820		DMERR("Target type does not support messages");
1821		r = -EINVAL;
1822	}
1823
1824 out_table:
1825	dm_put_live_table(md, srcu_idx);
1826 out_argv:
1827	kfree(argv);
1828 out:
1829	if (r >= 0)
1830		__dev_status(md, param);
1831
1832	if (r == 1) {
1833		param->flags |= DM_DATA_OUT_FLAG;
1834		if (dm_message_test_buffer_overflow(result, maxlen))
1835			param->flags |= DM_BUFFER_FULL_FLAG;
1836		else
1837			param->data_size = param->data_start + strlen(result) + 1;
1838		r = 0;
1839	}
1840
1841	dm_put(md);
1842	return r;
1843}
1844
1845/*
1846 * The ioctl parameter block consists of two parts, a dm_ioctl struct
1847 * followed by a data buffer.  This flag is set if the second part,
1848 * which has a variable size, is not used by the function processing
1849 * the ioctl.
1850 */
1851#define IOCTL_FLAGS_NO_PARAMS		1
1852#define IOCTL_FLAGS_ISSUE_GLOBAL_EVENT	2
1853
1854/*
1855 *---------------------------------------------------------------
1856 * Implementation of open/close/ioctl on the special char device.
1857 *---------------------------------------------------------------
1858 */
1859static ioctl_fn lookup_ioctl(unsigned int cmd, int *ioctl_flags)
1860{
1861	static const struct {
1862		int cmd;
1863		int flags;
1864		ioctl_fn fn;
1865	} _ioctls[] = {
1866		{DM_VERSION_CMD, 0, NULL}, /* version is dealt with elsewhere */
1867		{DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, remove_all},
1868		{DM_LIST_DEVICES_CMD, 0, list_devices},
1869
1870		{DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_create},
1871		{DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_remove},
1872		{DM_DEV_RENAME_CMD, IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_rename},
1873		{DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend},
1874		{DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status},
1875		{DM_DEV_WAIT_CMD, 0, dev_wait},
1876
1877		{DM_TABLE_LOAD_CMD, 0, table_load},
1878		{DM_TABLE_CLEAR_CMD, IOCTL_FLAGS_NO_PARAMS, table_clear},
1879		{DM_TABLE_DEPS_CMD, 0, table_deps},
1880		{DM_TABLE_STATUS_CMD, 0, table_status},
1881
1882		{DM_LIST_VERSIONS_CMD, 0, list_versions},
1883
1884		{DM_TARGET_MSG_CMD, 0, target_message},
1885		{DM_DEV_SET_GEOMETRY_CMD, 0, dev_set_geometry},
1886		{DM_DEV_ARM_POLL_CMD, IOCTL_FLAGS_NO_PARAMS, dev_arm_poll},
1887		{DM_GET_TARGET_VERSION_CMD, 0, get_target_version},
1888		{DM_MPATH_PROBE_PATHS_CMD, 0, NULL}, /* block device ioctl */
1889	};
1890
1891	if (unlikely(cmd >= ARRAY_SIZE(_ioctls)))
1892		return NULL;
1893
1894	cmd = array_index_nospec(cmd, ARRAY_SIZE(_ioctls));
1895	*ioctl_flags = _ioctls[cmd].flags;
1896	return _ioctls[cmd].fn;
1897}
1898
1899/*
1900 * As well as checking the version compatibility this always
1901 * copies the kernel interface version out.
1902 */
1903static int check_version(unsigned int cmd, struct dm_ioctl __user *user,
1904			 struct dm_ioctl *kernel_params)
1905{
1906	int r = 0;
1907
1908	/* Make certain version is first member of dm_ioctl struct */
1909	BUILD_BUG_ON(offsetof(struct dm_ioctl, version) != 0);
1910
1911	if (copy_from_user(kernel_params->version, user->version, sizeof(kernel_params->version)))
1912		return -EFAULT;
1913
1914	if ((kernel_params->version[0] != DM_VERSION_MAJOR) ||
1915	    (kernel_params->version[1] > DM_VERSION_MINOR)) {
1916		DMERR_LIMIT("ioctl interface mismatch: kernel(%u.%u.%u), user(%u.%u.%u), cmd(%d)",
1917		      DM_VERSION_MAJOR, DM_VERSION_MINOR,
1918		      DM_VERSION_PATCHLEVEL,
1919		      kernel_params->version[0],
1920		      kernel_params->version[1],
1921		      kernel_params->version[2],
1922		      cmd);
1923		r = -EINVAL;
1924	}
1925
1926	/*
1927	 * Fill in the kernel version.
1928	 */
1929	kernel_params->version[0] = DM_VERSION_MAJOR;
1930	kernel_params->version[1] = DM_VERSION_MINOR;
1931	kernel_params->version[2] = DM_VERSION_PATCHLEVEL;
1932	if (copy_to_user(user->version, kernel_params->version, sizeof(kernel_params->version)))
1933		return -EFAULT;
1934
1935	return r;
1936}
1937
1938#define DM_PARAMS_MALLOC	0x0001	/* Params allocated with kvmalloc() */
1939#define DM_WIPE_BUFFER		0x0010	/* Wipe input buffer before returning from ioctl */
1940
1941static void free_params(struct dm_ioctl *param, size_t param_size, int param_flags)
1942{
1943	if (param_flags & DM_WIPE_BUFFER)
1944		memset(param, 0, param_size);
1945
1946	if (param_flags & DM_PARAMS_MALLOC)
1947		kvfree(param);
1948}
1949
1950static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
1951		       int ioctl_flags, struct dm_ioctl **param, int *param_flags)
1952{
1953	struct dm_ioctl *dmi;
1954	int secure_data;
1955	const size_t minimum_data_size = offsetof(struct dm_ioctl, data);
1956
1957	/* check_version() already copied version from userspace, avoid TOCTOU */
1958	if (copy_from_user((char *)param_kernel + sizeof(param_kernel->version),
1959			   (char __user *)user + sizeof(param_kernel->version),
1960			   minimum_data_size - sizeof(param_kernel->version)))
1961		return -EFAULT;
1962
1963	if (unlikely(param_kernel->data_size < minimum_data_size) ||
1964	    unlikely(param_kernel->data_size > DM_MAX_TARGETS * DM_MAX_TARGET_PARAMS)) {
1965		DMERR_LIMIT("Invalid data size in the ioctl structure: %u",
1966		      param_kernel->data_size);
1967		return -EINVAL;
1968	}
1969
1970	secure_data = param_kernel->flags & DM_SECURE_DATA_FLAG;
1971
1972	*param_flags = secure_data ? DM_WIPE_BUFFER : 0;
1973
1974	if (ioctl_flags & IOCTL_FLAGS_NO_PARAMS) {
1975		dmi = param_kernel;
1976		dmi->data_size = minimum_data_size;
1977		goto data_copied;
1978	}
1979
1980	/*
1981	 * Use __GFP_HIGH to avoid low memory issues when a device is
1982	 * suspended and the ioctl is needed to resume it.
1983	 * Use kmalloc() rather than vmalloc() when we can.
1984	 */
1985	dmi = NULL;
1986	dmi = kvmalloc(param_kernel->data_size, GFP_NOIO | __GFP_HIGH);
1987
1988	if (!dmi) {
1989		if (secure_data && clear_user(user, param_kernel->data_size))
1990			return -EFAULT;
1991		return -ENOMEM;
1992	}
1993
1994	*param_flags |= DM_PARAMS_MALLOC;
1995
1996	/* Copy from param_kernel (which was already copied from user) */
1997	memcpy(dmi, param_kernel, minimum_data_size);
1998
1999	if (copy_from_user(&dmi->data, (char __user *)user + minimum_data_size,
2000			   param_kernel->data_size - minimum_data_size))
2001		goto bad;
2002data_copied:
2003	/* Wipe the user buffer so we do not return it to userspace */
2004	if (secure_data && clear_user(user, param_kernel->data_size))
2005		goto bad;
2006
2007	*param = dmi;
2008	return 0;
2009
2010bad:
2011	free_params(dmi, param_kernel->data_size, *param_flags);
2012
2013	return -EFAULT;
2014}
2015
2016static int validate_params(uint cmd, struct dm_ioctl *param)
2017{
2018	/* Always clear this flag */
2019	param->flags &= ~DM_BUFFER_FULL_FLAG;
2020	param->flags &= ~DM_UEVENT_GENERATED_FLAG;
2021	param->flags &= ~DM_SECURE_DATA_FLAG;
2022	param->flags &= ~DM_DATA_OUT_FLAG;
2023
2024	/* Ignores parameters */
2025	if (cmd == DM_REMOVE_ALL_CMD ||
2026	    cmd == DM_LIST_DEVICES_CMD ||
2027	    cmd == DM_LIST_VERSIONS_CMD)
2028		return 0;
2029
2030	if (cmd == DM_DEV_CREATE_CMD) {
2031		if (!*param->name) {
2032			DMERR("name not supplied when creating device");
2033			return -EINVAL;
2034		}
2035	} else if (*param->uuid && *param->name) {
2036		DMERR("only supply one of name or uuid, cmd(%u)", cmd);
2037		return -EINVAL;
2038	}
2039
2040	/* Ensure strings are terminated */
2041	param->name[DM_NAME_LEN - 1] = '\0';
2042	param->uuid[DM_UUID_LEN - 1] = '\0';
2043
2044	return 0;
2045}
2046
2047static int ctl_ioctl(struct file *file, uint command, struct dm_ioctl __user *user)
2048{
2049	int r = 0;
2050	int ioctl_flags;
2051	int param_flags;
2052	unsigned int cmd;
2053	struct dm_ioctl *param;
2054	ioctl_fn fn = NULL;
2055	size_t input_param_size;
2056	struct dm_ioctl param_kernel;
2057
2058	/* only root can play with this */
2059	if (!capable(CAP_SYS_ADMIN))
2060		return -EACCES;
2061
2062	if (_IOC_TYPE(command) != DM_IOCTL)
2063		return -ENOTTY;
2064
2065	cmd = _IOC_NR(command);
2066
2067	/*
2068	 * Check the interface version passed in.  This also
2069	 * writes out the kernel's interface version.
2070	 */
2071	r = check_version(cmd, user, &param_kernel);
2072	if (r)
2073		return r;
2074
2075	/*
2076	 * Nothing more to do for the version command.
2077	 */
2078	if (cmd == DM_VERSION_CMD)
2079		return 0;
2080
2081	fn = lookup_ioctl(cmd, &ioctl_flags);
2082	if (!fn) {
2083		DMERR("dm_ctl_ioctl: unknown command 0x%x", command);
2084		return -ENOTTY;
2085	}
2086
2087	/*
2088	 * Copy the parameters into kernel space.
2089	 */
2090	r = copy_params(user, &param_kernel, ioctl_flags, &param, &param_flags);
2091
2092	if (r)
2093		return r;
2094
2095	input_param_size = param->data_size;
2096	r = validate_params(cmd, param);
2097	if (r)
2098		goto out;
2099
2100	param->data_size = offsetof(struct dm_ioctl, data);
2101	r = fn(file, param, input_param_size);
2102
2103	if (unlikely(param->flags & DM_BUFFER_FULL_FLAG) &&
2104	    unlikely(ioctl_flags & IOCTL_FLAGS_NO_PARAMS))
2105		DMERR("ioctl %d tried to output some data but has IOCTL_FLAGS_NO_PARAMS set", cmd);
2106
2107	if (!r && ioctl_flags & IOCTL_FLAGS_ISSUE_GLOBAL_EVENT)
2108		dm_issue_global_event();
2109
2110	/*
2111	 * Copy the results back to userland.
2112	 */
2113	if (!r && copy_to_user(user, param, param->data_size))
2114		r = -EFAULT;
2115
2116out:
2117	free_params(param, input_param_size, param_flags);
2118	return r;
2119}
2120
2121static long dm_ctl_ioctl(struct file *file, uint command, ulong u)
2122{
2123	return (long)ctl_ioctl(file, command, (struct dm_ioctl __user *)u);
2124}
2125
2126#ifdef CONFIG_COMPAT
2127static long dm_compat_ctl_ioctl(struct file *file, uint command, ulong u)
2128{
2129	return (long)dm_ctl_ioctl(file, command, (ulong) compat_ptr(u));
2130}
2131#else
2132#define dm_compat_ctl_ioctl NULL
2133#endif
2134
2135static int dm_open(struct inode *inode, struct file *filp)
2136{
2137	int r;
2138	struct dm_file *priv;
2139
2140	r = nonseekable_open(inode, filp);
2141	if (unlikely(r))
2142		return r;
2143
2144	priv = filp->private_data = kmalloc(sizeof(struct dm_file), GFP_KERNEL);
2145	if (!priv)
2146		return -ENOMEM;
2147
2148	priv->global_event_nr = atomic_read(&dm_global_event_nr);
2149
2150	return 0;
2151}
2152
2153static int dm_release(struct inode *inode, struct file *filp)
2154{
2155	kfree(filp->private_data);
2156	return 0;
2157}
2158
2159static __poll_t dm_poll(struct file *filp, poll_table *wait)
2160{
2161	struct dm_file *priv = filp->private_data;
2162	__poll_t mask = 0;
2163
2164	poll_wait(filp, &dm_global_eventq, wait);
2165
2166	if ((int)(atomic_read(&dm_global_event_nr) - priv->global_event_nr) > 0)
2167		mask |= EPOLLIN;
2168
2169	return mask;
2170}
2171
2172static const struct file_operations _ctl_fops = {
2173	.open    = dm_open,
2174	.release = dm_release,
2175	.poll    = dm_poll,
2176	.unlocked_ioctl	 = dm_ctl_ioctl,
2177	.compat_ioctl = dm_compat_ctl_ioctl,
2178	.owner	 = THIS_MODULE,
2179	.llseek  = noop_llseek,
2180};
2181
2182static struct miscdevice _dm_misc = {
2183	.minor		= MAPPER_CTRL_MINOR,
2184	.name		= DM_NAME,
2185	.nodename	= DM_DIR "/" DM_CONTROL_NODE,
2186	.fops		= &_ctl_fops
2187};
2188
2189MODULE_ALIAS_MISCDEV(MAPPER_CTRL_MINOR);
2190MODULE_ALIAS("devname:" DM_DIR "/" DM_CONTROL_NODE);
2191
2192/*
2193 * Create misc character device and link to DM_DIR/control.
2194 */
2195int __init dm_interface_init(void)
2196{
2197	int r;
2198
2199	r = misc_register(&_dm_misc);
2200	if (r) {
2201		DMERR("misc_register failed for control device");
2202		return r;
2203	}
2204
2205	DMINFO("%d.%d.%d%s initialised: %s", DM_VERSION_MAJOR,
2206	       DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL, DM_VERSION_EXTRA,
2207	       DM_DRIVER_EMAIL);
2208	return 0;
2209}
2210
2211void dm_interface_exit(void)
2212{
2213	misc_deregister(&_dm_misc);
2214	dm_hash_exit();
2215}
2216
2217/**
2218 * dm_copy_name_and_uuid - Copy mapped device name & uuid into supplied buffers
2219 * @md: Pointer to mapped_device
2220 * @name: Buffer (size DM_NAME_LEN) for name
2221 * @uuid: Buffer (size DM_UUID_LEN) for uuid or empty string if uuid not defined
2222 */
2223int dm_copy_name_and_uuid(struct mapped_device *md, char *name, char *uuid)
2224{
2225	int r = 0;
2226	struct hash_cell *hc;
2227
2228	if (!md)
2229		return -ENXIO;
2230
2231	mutex_lock(&dm_hash_cells_mutex);
2232	hc = dm_get_mdptr(md);
2233	if (!hc) {
2234		r = -ENXIO;
2235		goto out;
2236	}
2237
2238	if (name)
2239		strcpy(name, hc->name);
2240	if (uuid)
2241		strcpy(uuid, hc->uuid ? : "");
2242
2243out:
2244	mutex_unlock(&dm_hash_cells_mutex);
2245
2246	return r;
2247}
2248EXPORT_SYMBOL_GPL(dm_copy_name_and_uuid);
2249
2250/**
2251 * dm_early_create - create a mapped device in early boot.
2252 *
2253 * @dmi: Contains main information of the device mapping to be created.
2254 * @spec_array: array of pointers to struct dm_target_spec. Describes the
2255 * mapping table of the device.
2256 * @target_params_array: array of strings with the parameters to a specific
2257 * target.
2258 *
2259 * Instead of having the struct dm_target_spec and the parameters for every
2260 * target embedded at the end of struct dm_ioctl (as performed in a normal
2261 * ioctl), pass them as arguments, so the caller doesn't need to serialize them.
2262 * The size of the spec_array and target_params_array is given by
2263 * @dmi->target_count.
2264 * This function is supposed to be called in early boot, so locking mechanisms
2265 * to protect against concurrent loads are not required.
2266 */
2267int __init dm_early_create(struct dm_ioctl *dmi,
2268			   struct dm_target_spec **spec_array,
2269			   char **target_params_array)
2270{
2271	int r, m = DM_ANY_MINOR;
2272	struct dm_table *t, *old_map;
2273	struct mapped_device *md;
2274	unsigned int i;
2275
2276	if (!dmi->target_count)
2277		return -EINVAL;
2278
2279	r = check_name(dmi->name);
2280	if (r)
2281		return r;
2282
2283	if (dmi->flags & DM_PERSISTENT_DEV_FLAG)
2284		m = MINOR(huge_decode_dev(dmi->dev));
2285
2286	/* alloc dm device */
2287	r = dm_create(m, &md);
2288	if (r)
2289		return r;
2290
2291	/* hash insert */
2292	r = dm_hash_insert(dmi->name, *dmi->uuid ? dmi->uuid : NULL, md);
2293	if (r)
2294		goto err_destroy_dm;
2295
2296	/* alloc table */
2297	r = dm_table_create(&t, get_mode(dmi), dmi->target_count, md);
2298	if (r)
2299		goto err_hash_remove;
2300
2301	/* add targets */
2302	for (i = 0; i < dmi->target_count; i++) {
2303		r = dm_table_add_target(t, spec_array[i]->target_type,
2304					(sector_t) spec_array[i]->sector_start,
2305					(sector_t) spec_array[i]->length,
2306					target_params_array[i]);
2307		if (r) {
2308			DMERR("error adding target to table");
2309			goto err_destroy_table;
2310		}
2311	}
2312
2313	/* finish table */
2314	r = dm_table_complete(t);
2315	if (r)
2316		goto err_destroy_table;
2317
2318	/* setup md->queue to reflect md's type (may block) */
2319	r = dm_setup_md_queue(md, t);
2320	if (r) {
2321		DMERR("unable to set up device queue for new table.");
2322		goto err_destroy_table;
2323	}
2324
2325	/* Set new map */
2326	dm_suspend(md, 0);
2327	old_map = dm_swap_table(md, t);
2328	if (IS_ERR(old_map)) {
2329		r = PTR_ERR(old_map);
2330		goto err_destroy_table;
2331	}
2332	set_disk_ro(dm_disk(md), !!(dmi->flags & DM_READONLY_FLAG));
2333
2334	/* resume device */
2335	r = dm_resume(md);
2336	if (r)
2337		goto err_destroy_table;
2338
2339	DMINFO("%s (%s) is ready", md->disk->disk_name, dmi->name);
2340	dm_put(md);
2341	return 0;
2342
2343err_destroy_table:
2344	dm_table_destroy(t);
2345err_hash_remove:
2346	down_write(&_hash_lock);
2347	(void) __hash_remove(__get_name_cell(dmi->name));
2348	up_write(&_hash_lock);
2349	/* release reference from __get_name_cell */
2350	dm_put(md);
2351err_destroy_dm:
2352	dm_put(md);
2353	dm_destroy(md);
2354	return r;
2355}