netlabel_domainhash.c 22.1 KB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790
/*
 * NetLabel Domain Hash Table
 *
 * This file manages the domain hash table that NetLabel uses to determine
 * which network labeling protocol to use for a given domain.  The NetLabel
 * system manages static and dynamic label mappings for network protocols such
 * as CIPSO and RIPSO.
 *
 * Author: Paul Moore <paul@paul-moore.com>
 *
 */

/*
 * (c) Copyright Hewlett-Packard Development Company, L.P., 2006, 2008
 *
 * This program is free software;  you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY;  without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 * the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program;  if not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <linux/types.h>
#include <linux/rculist.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/audit.h>
#include <linux/slab.h>
#include <net/netlabel.h>
#include <net/cipso_ipv4.h>
#include <asm/bug.h>

#include "netlabel_mgmt.h"
#include "netlabel_addrlist.h"
#include "netlabel_domainhash.h"
#include "netlabel_user.h"

struct netlbl_domhsh_tbl {
	struct list_head *tbl;
	u32 size;
};

/* Domain hash table */
/* updates should be so rare that having one spinlock for the entire hash table
 * should be okay */
static DEFINE_SPINLOCK(netlbl_domhsh_lock);
#define netlbl_domhsh_rcu_deref(p) \
	rcu_dereference_check(p, lockdep_is_held(&netlbl_domhsh_lock))
static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL;
static struct netlbl_dom_map *netlbl_domhsh_def = NULL;

/*
 * Domain Hash Table Helper Functions
 */

/**
 * netlbl_domhsh_free_entry - Frees a domain hash table entry
 * @entry: the entry's RCU field
 *
 * Description:
 * This function is designed to be used as a callback to the call_rcu()
 * function so that the memory allocated to a hash table entry can be released
 * safely.
 *
 */
static void netlbl_domhsh_free_entry(struct rcu_head *entry)
{
	struct netlbl_dom_map *ptr;
	struct netlbl_af4list *iter4;
	struct netlbl_af4list *tmp4;
#if IS_ENABLED(CONFIG_IPV6)
	struct netlbl_af6list *iter6;
	struct netlbl_af6list *tmp6;
#endif /* IPv6 */

	ptr = container_of(entry, struct netlbl_dom_map, rcu);
	if (ptr->def.type == NETLBL_NLTYPE_ADDRSELECT) {
		netlbl_af4list_foreach_safe(iter4, tmp4,
					    &ptr->def.addrsel->list4) {
			netlbl_af4list_remove_entry(iter4);
			kfree(netlbl_domhsh_addr4_entry(iter4));
		}
#if IS_ENABLED(CONFIG_IPV6)
		netlbl_af6list_foreach_safe(iter6, tmp6,
					    &ptr->def.addrsel->list6) {
			netlbl_af6list_remove_entry(iter6);
			kfree(netlbl_domhsh_addr6_entry(iter6));
		}
#endif /* IPv6 */
	}
	kfree(ptr->domain);
	kfree(ptr);
}

/**
 * netlbl_domhsh_hash - Hashing function for the domain hash table
 * @domain: the domain name to hash
 *
 * Description:
 * This is the hashing function for the domain hash table, it returns the
 * correct bucket number for the domain.  The caller is responsible for
 * ensuring that the hash table is protected with either a RCU read lock or the
 * hash table lock.
 *
 */
static u32 netlbl_domhsh_hash(const char *key)
{
	u32 iter;
	u32 val;
	u32 len;

	/* This is taken (with slight modification) from
	 * security/selinux/ss/symtab.c:symhash() */

	for (iter = 0, val = 0, len = strlen(key); iter < len; iter++)
		val = (val << 4 | (val >> (8 * sizeof(u32) - 4))) ^ key[iter];
	return val & (netlbl_domhsh_rcu_deref(netlbl_domhsh)->size - 1);
}

/**
 * netlbl_domhsh_search - Search for a domain entry
 * @domain: the domain
 *
 * Description:
 * Searches the domain hash table and returns a pointer to the hash table
 * entry if found, otherwise NULL is returned.  The caller is responsible for
 * ensuring that the hash table is protected with either a RCU read lock or the
 * hash table lock.
 *
 */
static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain)
{
	u32 bkt;
	struct list_head *bkt_list;
	struct netlbl_dom_map *iter;

	if (domain != NULL) {
		bkt = netlbl_domhsh_hash(domain);
		bkt_list = &netlbl_domhsh_rcu_deref(netlbl_domhsh)->tbl[bkt];
		list_for_each_entry_rcu(iter, bkt_list, list)
			if (iter->valid && strcmp(iter->domain, domain) == 0)
				return iter;
	}

	return NULL;
}

/**
 * netlbl_domhsh_search_def - Search for a domain entry
 * @domain: the domain
 * @def: return default if no match is found
 *
 * Description:
 * Searches the domain hash table and returns a pointer to the hash table
 * entry if an exact match is found, if an exact match is not present in the
 * hash table then the default entry is returned if valid otherwise NULL is
 * returned.  The caller is responsible ensuring that the hash table is
 * protected with either a RCU read lock or the hash table lock.
 *
 */
static struct netlbl_dom_map *netlbl_domhsh_search_def(const char *domain)
{
	struct netlbl_dom_map *entry;

	entry = netlbl_domhsh_search(domain);
	if (entry == NULL) {
		entry = netlbl_domhsh_rcu_deref(netlbl_domhsh_def);
		if (entry != NULL && !entry->valid)
			entry = NULL;
	}

	return entry;
}

/**
 * netlbl_domhsh_audit_add - Generate an audit entry for an add event
 * @entry: the entry being added
 * @addr4: the IPv4 address information
 * @addr6: the IPv6 address information
 * @result: the result code
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Generate an audit record for adding a new NetLabel/LSM mapping entry with
 * the given information.  Caller is responsible for holding the necessary
 * locks.
 *
 */
static void netlbl_domhsh_audit_add(struct netlbl_dom_map *entry,
				    struct netlbl_af4list *addr4,
				    struct netlbl_af6list *addr6,
				    int result,
				    struct netlbl_audit *audit_info)
{
	struct audit_buffer *audit_buf;
	struct cipso_v4_doi *cipsov4 = NULL;
	u32 type;

	audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_ADD, audit_info);
	if (audit_buf != NULL) {
		audit_log_format(audit_buf, " nlbl_domain=%s",
				 entry->domain ? entry->domain : "(default)");
		if (addr4 != NULL) {
			struct netlbl_domaddr4_map *map4;
			map4 = netlbl_domhsh_addr4_entry(addr4);
			type = map4->def.type;
			cipsov4 = map4->def.cipso;
			netlbl_af4list_audit_addr(audit_buf, 0, NULL,
						  addr4->addr, addr4->mask);
#if IS_ENABLED(CONFIG_IPV6)
		} else if (addr6 != NULL) {
			struct netlbl_domaddr6_map *map6;
			map6 = netlbl_domhsh_addr6_entry(addr6);
			type = map6->def.type;
			netlbl_af6list_audit_addr(audit_buf, 0, NULL,
						  &addr6->addr, &addr6->mask);
#endif /* IPv6 */
		} else {
			type = entry->def.type;
			cipsov4 = entry->def.cipso;
		}
		switch (type) {
		case NETLBL_NLTYPE_UNLABELED:
			audit_log_format(audit_buf, " nlbl_protocol=unlbl");
			break;
		case NETLBL_NLTYPE_CIPSOV4:
			BUG_ON(cipsov4 == NULL);
			audit_log_format(audit_buf,
					 " nlbl_protocol=cipsov4 cipso_doi=%u",
					 cipsov4->doi);
			break;
		}
		audit_log_format(audit_buf, " res=%u", result == 0 ? 1 : 0);
		audit_log_end(audit_buf);
	}
}

/**
 * netlbl_domhsh_validate - Validate a new domain mapping entry
 * @entry: the entry to validate
 *
 * This function validates the new domain mapping entry to ensure that it is
 * a valid entry.  Returns zero on success, negative values on failure.
 *
 */
static int netlbl_domhsh_validate(const struct netlbl_dom_map *entry)
{
	struct netlbl_af4list *iter4;
	struct netlbl_domaddr4_map *map4;
#if IS_ENABLED(CONFIG_IPV6)
	struct netlbl_af6list *iter6;
	struct netlbl_domaddr6_map *map6;
#endif /* IPv6 */

	if (entry == NULL)
		return -EINVAL;

	switch (entry->def.type) {
	case NETLBL_NLTYPE_UNLABELED:
		if (entry->def.cipso != NULL || entry->def.addrsel != NULL)
			return -EINVAL;
		break;
	case NETLBL_NLTYPE_CIPSOV4:
		if (entry->def.cipso == NULL)
			return -EINVAL;
		break;
	case NETLBL_NLTYPE_ADDRSELECT:
		netlbl_af4list_foreach(iter4, &entry->def.addrsel->list4) {
			map4 = netlbl_domhsh_addr4_entry(iter4);
			switch (map4->def.type) {
			case NETLBL_NLTYPE_UNLABELED:
				if (map4->def.cipso != NULL)
					return -EINVAL;
				break;
			case NETLBL_NLTYPE_CIPSOV4:
				if (map4->def.cipso == NULL)
					return -EINVAL;
				break;
			default:
				return -EINVAL;
			}
		}
#if IS_ENABLED(CONFIG_IPV6)
		netlbl_af6list_foreach(iter6, &entry->def.addrsel->list6) {
			map6 = netlbl_domhsh_addr6_entry(iter6);
			switch (map6->def.type) {
			case NETLBL_NLTYPE_UNLABELED:
				break;
			default:
				return -EINVAL;
			}
		}
#endif /* IPv6 */
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

/*
 * Domain Hash Table Functions
 */

/**
 * netlbl_domhsh_init - Init for the domain hash
 * @size: the number of bits to use for the hash buckets
 *
 * Description:
 * Initializes the domain hash table, should be called only by
 * netlbl_user_init() during initialization.  Returns zero on success, non-zero
 * values on error.
 *
 */
int __init netlbl_domhsh_init(u32 size)
{
	u32 iter;
	struct netlbl_domhsh_tbl *hsh_tbl;

	if (size == 0)
		return -EINVAL;

	hsh_tbl = kmalloc(sizeof(*hsh_tbl), GFP_KERNEL);
	if (hsh_tbl == NULL)
		return -ENOMEM;
	hsh_tbl->size = 1 << size;
	hsh_tbl->tbl = kcalloc(hsh_tbl->size,
			       sizeof(struct list_head),
			       GFP_KERNEL);
	if (hsh_tbl->tbl == NULL) {
		kfree(hsh_tbl);
		return -ENOMEM;
	}
	for (iter = 0; iter < hsh_tbl->size; iter++)
		INIT_LIST_HEAD(&hsh_tbl->tbl[iter]);

	spin_lock(&netlbl_domhsh_lock);
	rcu_assign_pointer(netlbl_domhsh, hsh_tbl);
	spin_unlock(&netlbl_domhsh_lock);

	return 0;
}

/**
 * netlbl_domhsh_add - Adds a entry to the domain hash table
 * @entry: the entry to add
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Adds a new entry to the domain hash table and handles any updates to the
 * lower level protocol handler (i.e. CIPSO).  Returns zero on success,
 * negative on failure.
 *
 */
int netlbl_domhsh_add(struct netlbl_dom_map *entry,
		      struct netlbl_audit *audit_info)
{
	int ret_val = 0;
	struct netlbl_dom_map *entry_old;
	struct netlbl_af4list *iter4;
	struct netlbl_af4list *tmp4;
#if IS_ENABLED(CONFIG_IPV6)
	struct netlbl_af6list *iter6;
	struct netlbl_af6list *tmp6;
#endif /* IPv6 */

	ret_val = netlbl_domhsh_validate(entry);
	if (ret_val != 0)
		return ret_val;

	/* XXX - we can remove this RCU read lock as the spinlock protects the
	 *       entire function, but before we do we need to fixup the
	 *       netlbl_af[4,6]list RCU functions to do "the right thing" with
	 *       respect to rcu_dereference() when only a spinlock is held. */
	rcu_read_lock();
	spin_lock(&netlbl_domhsh_lock);
	if (entry->domain != NULL)
		entry_old = netlbl_domhsh_search(entry->domain);
	else
		entry_old = netlbl_domhsh_search_def(entry->domain);
	if (entry_old == NULL) {
		entry->valid = 1;

		if (entry->domain != NULL) {
			u32 bkt = netlbl_domhsh_hash(entry->domain);
			list_add_tail_rcu(&entry->list,
				    &rcu_dereference(netlbl_domhsh)->tbl[bkt]);
		} else {
			INIT_LIST_HEAD(&entry->list);
			rcu_assign_pointer(netlbl_domhsh_def, entry);
		}

		if (entry->def.type == NETLBL_NLTYPE_ADDRSELECT) {
			netlbl_af4list_foreach_rcu(iter4,
						   &entry->def.addrsel->list4)
				netlbl_domhsh_audit_add(entry, iter4, NULL,
							ret_val, audit_info);
#if IS_ENABLED(CONFIG_IPV6)
			netlbl_af6list_foreach_rcu(iter6,
						   &entry->def.addrsel->list6)
				netlbl_domhsh_audit_add(entry, NULL, iter6,
							ret_val, audit_info);
#endif /* IPv6 */
		} else
			netlbl_domhsh_audit_add(entry, NULL, NULL,
						ret_val, audit_info);
	} else if (entry_old->def.type == NETLBL_NLTYPE_ADDRSELECT &&
		   entry->def.type == NETLBL_NLTYPE_ADDRSELECT) {
		struct list_head *old_list4;
		struct list_head *old_list6;

		old_list4 = &entry_old->def.addrsel->list4;
		old_list6 = &entry_old->def.addrsel->list6;

		/* we only allow the addition of address selectors if all of
		 * the selectors do not exist in the existing domain map */
		netlbl_af4list_foreach_rcu(iter4, &entry->def.addrsel->list4)
			if (netlbl_af4list_search_exact(iter4->addr,
							iter4->mask,
							old_list4)) {
				ret_val = -EEXIST;
				goto add_return;
			}
#if IS_ENABLED(CONFIG_IPV6)
		netlbl_af6list_foreach_rcu(iter6, &entry->def.addrsel->list6)
			if (netlbl_af6list_search_exact(&iter6->addr,
							&iter6->mask,
							old_list6)) {
				ret_val = -EEXIST;
				goto add_return;
			}
#endif /* IPv6 */

		netlbl_af4list_foreach_safe(iter4, tmp4,
					    &entry->def.addrsel->list4) {
			netlbl_af4list_remove_entry(iter4);
			iter4->valid = 1;
			ret_val = netlbl_af4list_add(iter4, old_list4);
			netlbl_domhsh_audit_add(entry_old, iter4, NULL,
						ret_val, audit_info);
			if (ret_val != 0)
				goto add_return;
		}
#if IS_ENABLED(CONFIG_IPV6)
		netlbl_af6list_foreach_safe(iter6, tmp6,
					    &entry->def.addrsel->list6) {
			netlbl_af6list_remove_entry(iter6);
			iter6->valid = 1;
			ret_val = netlbl_af6list_add(iter6, old_list6);
			netlbl_domhsh_audit_add(entry_old, NULL, iter6,
						ret_val, audit_info);
			if (ret_val != 0)
				goto add_return;
		}
#endif /* IPv6 */
	} else
		ret_val = -EINVAL;

add_return:
	spin_unlock(&netlbl_domhsh_lock);
	rcu_read_unlock();
	return ret_val;
}

/**
 * netlbl_domhsh_add_default - Adds the default entry to the domain hash table
 * @entry: the entry to add
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Adds a new default entry to the domain hash table and handles any updates
 * to the lower level protocol handler (i.e. CIPSO).  Returns zero on success,
 * negative on failure.
 *
 */
int netlbl_domhsh_add_default(struct netlbl_dom_map *entry,
			      struct netlbl_audit *audit_info)
{
	return netlbl_domhsh_add(entry, audit_info);
}

/**
 * netlbl_domhsh_remove_entry - Removes a given entry from the domain table
 * @entry: the entry to remove
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Removes an entry from the domain hash table and handles any updates to the
 * lower level protocol handler (i.e. CIPSO).  Caller is responsible for
 * ensuring that the RCU read lock is held.  Returns zero on success, negative
 * on failure.
 *
 */
int netlbl_domhsh_remove_entry(struct netlbl_dom_map *entry,
			       struct netlbl_audit *audit_info)
{
	int ret_val = 0;
	struct audit_buffer *audit_buf;

	if (entry == NULL)
		return -ENOENT;

	spin_lock(&netlbl_domhsh_lock);
	if (entry->valid) {
		entry->valid = 0;
		if (entry != rcu_dereference(netlbl_domhsh_def))
			list_del_rcu(&entry->list);
		else
			RCU_INIT_POINTER(netlbl_domhsh_def, NULL);
	} else
		ret_val = -ENOENT;
	spin_unlock(&netlbl_domhsh_lock);

	audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL, audit_info);
	if (audit_buf != NULL) {
		audit_log_format(audit_buf,
				 " nlbl_domain=%s res=%u",
				 entry->domain ? entry->domain : "(default)",
				 ret_val == 0 ? 1 : 0);
		audit_log_end(audit_buf);
	}

	if (ret_val == 0) {
		struct netlbl_af4list *iter4;
		struct netlbl_domaddr4_map *map4;

		switch (entry->def.type) {
		case NETLBL_NLTYPE_ADDRSELECT:
			netlbl_af4list_foreach_rcu(iter4,
					     &entry->def.addrsel->list4) {
				map4 = netlbl_domhsh_addr4_entry(iter4);
				cipso_v4_doi_putdef(map4->def.cipso);
			}
			/* no need to check the IPv6 list since we currently
			 * support only unlabeled protocols for IPv6 */
			break;
		case NETLBL_NLTYPE_CIPSOV4:
			cipso_v4_doi_putdef(entry->def.cipso);
			break;
		}
		call_rcu(&entry->rcu, netlbl_domhsh_free_entry);
	}

	return ret_val;
}

/**
 * netlbl_domhsh_remove_af4 - Removes an address selector entry
 * @domain: the domain
 * @addr: IPv4 address
 * @mask: IPv4 address mask
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Removes an individual address selector from a domain mapping and potentially
 * the entire mapping if it is empty.  Returns zero on success, negative values
 * on failure.
 *
 */
int netlbl_domhsh_remove_af4(const char *domain,
			     const struct in_addr *addr,
			     const struct in_addr *mask,
			     struct netlbl_audit *audit_info)
{
	struct netlbl_dom_map *entry_map;
	struct netlbl_af4list *entry_addr;
	struct netlbl_af4list *iter4;
#if IS_ENABLED(CONFIG_IPV6)
	struct netlbl_af6list *iter6;
#endif /* IPv6 */
	struct netlbl_domaddr4_map *entry;

	rcu_read_lock();

	if (domain)
		entry_map = netlbl_domhsh_search(domain);
	else
		entry_map = netlbl_domhsh_search_def(domain);
	if (entry_map == NULL ||
	    entry_map->def.type != NETLBL_NLTYPE_ADDRSELECT)
		goto remove_af4_failure;

	spin_lock(&netlbl_domhsh_lock);
	entry_addr = netlbl_af4list_remove(addr->s_addr, mask->s_addr,
					   &entry_map->def.addrsel->list4);
	spin_unlock(&netlbl_domhsh_lock);

	if (entry_addr == NULL)
		goto remove_af4_failure;
	netlbl_af4list_foreach_rcu(iter4, &entry_map->def.addrsel->list4)
		goto remove_af4_single_addr;
#if IS_ENABLED(CONFIG_IPV6)
	netlbl_af6list_foreach_rcu(iter6, &entry_map->def.addrsel->list6)
		goto remove_af4_single_addr;
#endif /* IPv6 */
	/* the domain mapping is empty so remove it from the mapping table */
	netlbl_domhsh_remove_entry(entry_map, audit_info);

remove_af4_single_addr:
	rcu_read_unlock();
	/* yick, we can't use call_rcu here because we don't have a rcu head
	 * pointer but hopefully this should be a rare case so the pause
	 * shouldn't be a problem */
	synchronize_rcu();
	entry = netlbl_domhsh_addr4_entry(entry_addr);
	cipso_v4_doi_putdef(entry->def.cipso);
	kfree(entry);
	return 0;

remove_af4_failure:
	rcu_read_unlock();
	return -ENOENT;
}

/**
 * netlbl_domhsh_remove - Removes an entry from the domain hash table
 * @domain: the domain to remove
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Removes an entry from the domain hash table and handles any updates to the
 * lower level protocol handler (i.e. CIPSO).  Returns zero on success,
 * negative on failure.
 *
 */
int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info)
{
	int ret_val;
	struct netlbl_dom_map *entry;

	rcu_read_lock();
	if (domain)
		entry = netlbl_domhsh_search(domain);
	else
		entry = netlbl_domhsh_search_def(domain);
	ret_val = netlbl_domhsh_remove_entry(entry, audit_info);
	rcu_read_unlock();

	return ret_val;
}

/**
 * netlbl_domhsh_remove_default - Removes the default entry from the table
 * @audit_info: NetLabel audit information
 *
 * Description:
 * Removes/resets the default entry for the domain hash table and handles any
 * updates to the lower level protocol handler (i.e. CIPSO).  Returns zero on
 * success, non-zero on failure.
 *
 */
int netlbl_domhsh_remove_default(struct netlbl_audit *audit_info)
{
	return netlbl_domhsh_remove(NULL, audit_info);
}

/**
 * netlbl_domhsh_getentry - Get an entry from the domain hash table
 * @domain: the domain name to search for
 *
 * Description:
 * Look through the domain hash table searching for an entry to match @domain,
 * return a pointer to a copy of the entry or NULL.  The caller is responsible
 * for ensuring that rcu_read_[un]lock() is called.
 *
 */
struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain)
{
	return netlbl_domhsh_search_def(domain);
}

/**
 * netlbl_domhsh_getentry_af4 - Get an entry from the domain hash table
 * @domain: the domain name to search for
 * @addr: the IP address to search for
 *
 * Description:
 * Look through the domain hash table searching for an entry to match @domain
 * and @addr, return a pointer to a copy of the entry or NULL.  The caller is
 * responsible for ensuring that rcu_read_[un]lock() is called.
 *
 */
struct netlbl_dommap_def *netlbl_domhsh_getentry_af4(const char *domain,
						     __be32 addr)
{
	struct netlbl_dom_map *dom_iter;
	struct netlbl_af4list *addr_iter;

	dom_iter = netlbl_domhsh_search_def(domain);
	if (dom_iter == NULL)
		return NULL;

	if (dom_iter->def.type != NETLBL_NLTYPE_ADDRSELECT)
		return &dom_iter->def;
	addr_iter = netlbl_af4list_search(addr, &dom_iter->def.addrsel->list4);
	if (addr_iter == NULL)
		return NULL;
	return &(netlbl_domhsh_addr4_entry(addr_iter)->def);
}

#if IS_ENABLED(CONFIG_IPV6)
/**
 * netlbl_domhsh_getentry_af6 - Get an entry from the domain hash table
 * @domain: the domain name to search for
 * @addr: the IP address to search for
 *
 * Description:
 * Look through the domain hash table searching for an entry to match @domain
 * and @addr, return a pointer to a copy of the entry or NULL.  The caller is
 * responsible for ensuring that rcu_read_[un]lock() is called.
 *
 */
struct netlbl_dommap_def *netlbl_domhsh_getentry_af6(const char *domain,
						   const struct in6_addr *addr)
{
	struct netlbl_dom_map *dom_iter;
	struct netlbl_af6list *addr_iter;

	dom_iter = netlbl_domhsh_search_def(domain);
	if (dom_iter == NULL)
		return NULL;

	if (dom_iter->def.type != NETLBL_NLTYPE_ADDRSELECT)
		return &dom_iter->def;
	addr_iter = netlbl_af6list_search(addr, &dom_iter->def.addrsel->list6);
	if (addr_iter == NULL)
		return NULL;
	return &(netlbl_domhsh_addr6_entry(addr_iter)->def);
}
#endif /* IPv6 */

/**
 * netlbl_domhsh_walk - Iterate through the domain mapping hash table
 * @skip_bkt: the number of buckets to skip at the start
 * @skip_chain: the number of entries to skip in the first iterated bucket
 * @callback: callback for each entry
 * @cb_arg: argument for the callback function
 *
 * Description:
 * Interate over the domain mapping hash table, skipping the first @skip_bkt
 * buckets and @skip_chain entries.  For each entry in the table call
 * @callback, if @callback returns a negative value stop 'walking' through the
 * table and return.  Updates the values in @skip_bkt and @skip_chain on
 * return.  Returns zero on success, negative values on failure.
 *
 */
int netlbl_domhsh_walk(u32 *skip_bkt,
		     u32 *skip_chain,
		     int (*callback) (struct netlbl_dom_map *entry, void *arg),
		     void *cb_arg)
{
	int ret_val = -ENOENT;
	u32 iter_bkt;
	struct list_head *iter_list;
	struct netlbl_dom_map *iter_entry;
	u32 chain_cnt = 0;

	rcu_read_lock();
	for (iter_bkt = *skip_bkt;
	     iter_bkt < rcu_dereference(netlbl_domhsh)->size;
	     iter_bkt++, chain_cnt = 0) {
		iter_list = &rcu_dereference(netlbl_domhsh)->tbl[iter_bkt];
		list_for_each_entry_rcu(iter_entry, iter_list, list)
			if (iter_entry->valid) {
				if (chain_cnt++ < *skip_chain)
					continue;
				ret_val = callback(iter_entry, cb_arg);
				if (ret_val < 0) {
					chain_cnt--;
					goto walk_return;
				}
			}
	}

walk_return:
	rcu_read_unlock();
	*skip_bkt = iter_bkt;
	*skip_chain = chain_cnt;
	return ret_val;
}