summaryrefslogtreecommitdiff
path: root/net/netlabel/netlabel_domainhash.c
blob: 0bfeaab88ef556852766c2c355f28233bff47bef (plain)
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
/*
 * 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.moore@hp.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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

#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 <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 */
/* XXX - updates should be so rare that having one spinlock for the entire
 * hash table should be okay */
static DEFINE_SPINLOCK(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 defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	struct netlbl_af6list *iter6;
	struct netlbl_af6list *tmp6;
#endif /* IPv6 */

	ptr = container_of(entry, struct netlbl_dom_map, rcu);
	if (ptr->type == NETLBL_NLTYPE_ADDRSELECT) {
		netlbl_af4list_foreach_safe(iter4, tmp4,
					    &ptr->type_def.addrsel->list4) {
			netlbl_af4list_remove_entry(iter4);
			kfree(netlbl_domhsh_addr4_entry(iter4));
		}
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
		netlbl_af6list_foreach_safe(iter6, tmp6,
					    &ptr->type_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 responsibile for
 * calling the rcu_read_[un]lock() functions.
 *
 */
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 & (rcu_dereference(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 responsibile for
 * the rcu hash table locks (i.e. the caller much call rcu_read_[un]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 = &rcu_dereference(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 responsibile for the rcu hash table locks
 * (i.e. the caller much call rcu_read_[un]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 = rcu_dereference(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 responsibile 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->type;
			cipsov4 = map4->type_def.cipsov4;
			netlbl_af4list_audit_addr(audit_buf, 0, NULL,
						  addr4->addr, addr4->mask);
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
		} else if (addr6 != NULL) {
			struct netlbl_domaddr6_map *map6;
			map6 = netlbl_domhsh_addr6_entry(addr6);
			type = map6->type;
			netlbl_af6list_audit_addr(audit_buf, 0, NULL,
						  &addr6->addr, &addr6->mask);
#endif /* IPv6 */
		} else {
			type = entry->type;
			cipsov4 = entry->type_def.cipsov4;
		}
		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);
	}
}

/*
 * 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 defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	struct netlbl_af6list *iter6;
	struct netlbl_af6list *tmp6;
#endif /* IPv6 */

	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->type == NETLBL_NLTYPE_ADDRSELECT) {
			netlbl_af4list_foreach_rcu(iter4,
					       &entry->type_def.addrsel->list4)
				netlbl_domhsh_audit_add(entry, iter4, NULL,
							ret_val, audit_info);
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
			netlbl_af6list_foreach_rcu(iter6,
					       &entry->type_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->type == NETLBL_NLTYPE_ADDRSELECT &&
		   entry->type == NETLBL_NLTYPE_ADDRSELECT) {
		struct list_head *old_list4;
		struct list_head *old_list6;

		old_list4 = &entry_old->type_def.addrsel->list4;
		old_list6 = &entry_old->type_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->type_def.addrsel->list4)
			if (netlbl_af4list_search_exact(iter4->addr,
							iter4->mask,
							old_list4)) {
				ret_val = -EEXIST;
				goto add_return;
			}
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
		netlbl_af6list_foreach_rcu(iter6,
					   &entry->type_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->type_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 defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
		netlbl_af6list_foreach_safe(iter6, tmp6,
					    &entry->type_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_assign_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->type) {
		case NETLBL_NLTYPE_ADDRSELECT:
			netlbl_af4list_foreach_rcu(iter4,
					     &entry->type_def.addrsel->list4) {
				map4 = netlbl_domhsh_addr4_entry(iter4);
				cipso_v4_doi_putdef(map4->type_def.cipsov4);
			}
			/* 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->type_def.cipsov4);
			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 defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	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->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->type_def.addrsel->list4);
	spin_unlock(&netlbl_domhsh_lock);

	if (entry_addr == NULL)
		goto remove_af4_failure;
	netlbl_af4list_foreach_rcu(iter4, &entry_map->type_def.addrsel->list4)
		goto remove_af4_single_addr;
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
	netlbl_af6list_foreach_rcu(iter6, &entry_map->type_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->type_def.cipsov4);
	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 responsibile
 * 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_domaddr4_map *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->type != NETLBL_NLTYPE_ADDRSELECT)
		return NULL;

	addr_iter = netlbl_af4list_search(addr,
					  &dom_iter->type_def.addrsel->list4);
	if (addr_iter == NULL)
		return NULL;

	return netlbl_domhsh_addr4_entry(addr_iter);
}

#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
/**
 * 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_domaddr6_map *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->type != NETLBL_NLTYPE_ADDRSELECT)
		return NULL;

	addr_iter = netlbl_af6list_search(addr,
					  &dom_iter->type_def.addrsel->list6);
	if (addr_iter == NULL)
		return NULL;

	return netlbl_domhsh_addr6_entry(addr_iter);
}
#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;
}