summaryrefslogtreecommitdiffstats
path: root/security/selinux/avc.c
blob: 95a8ef4a5073fbcde9f2fcec8a5301cf7db27eb2 (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
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
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
/*
 * Implementation of the kernel access vector cache (AVC).
 *
 * Authors:  Stephen Smalley, <sds@epoch.ncsc.mil>
 *	     James Morris <jmorris@redhat.com>
 *
 * Update:   KaiGai, Kohei <kaigai@ak.jp.nec.com>
 *	Replaced the avc_lock spinlock by RCU.
 *
 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
 *
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License version 2,
 *	as published by the Free Software Foundation.
 */
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/dcache.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/percpu.h>
#include <net/sock.h>
#include <linux/un.h>
#include <net/af_unix.h>
#include <linux/ip.h>
#include <linux/audit.h>
#include <linux/ipv6.h>
#include <net/ipv6.h>
#include "avc.h"
#include "avc_ss.h"

static const struct av_perm_to_string av_perm_to_string[] = {
#define S_(c, v, s) { c, v, s },
#include "av_perm_to_string.h"
#undef S_
};

static const char *class_to_string[] = {
#define S_(s) s,
#include "class_to_string.h"
#undef S_
};

#define TB_(s) static const char *s[] = {
#define TE_(s) };
#define S_(s) s,
#include "common_perm_to_string.h"
#undef TB_
#undef TE_
#undef S_

static const struct av_inherit av_inherit[] = {
#define S_(c, i, b) { c, common_##i##_perm_to_string, b },
#include "av_inherit.h"
#undef S_
};

const struct selinux_class_perm selinux_class_perm = {
	av_perm_to_string,
	ARRAY_SIZE(av_perm_to_string),
	class_to_string,
	ARRAY_SIZE(class_to_string),
	av_inherit,
	ARRAY_SIZE(av_inherit)
};

#define AVC_CACHE_SLOTS			512
#define AVC_DEF_CACHE_THRESHOLD		512
#define AVC_CACHE_RECLAIM		16

#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
#define avc_cache_stats_incr(field)				\
do {								\
	per_cpu(avc_cache_stats, get_cpu()).field++;		\
	put_cpu();						\
} while (0)
#else
#define avc_cache_stats_incr(field)	do {} while (0)
#endif

struct avc_entry {
	u32			ssid;
	u32			tsid;
	u16			tclass;
	struct av_decision	avd;
	atomic_t		used;	/* used recently */
};

struct avc_node {
	struct avc_entry	ae;
	struct list_head	list;
	struct rcu_head		rhead;
};

struct avc_cache {
	struct list_head	slots[AVC_CACHE_SLOTS];
	spinlock_t		slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
	atomic_t		lru_hint;	/* LRU hint for reclaim scan */
	atomic_t		active_nodes;
	u32			latest_notif;	/* latest revocation notification */
};

struct avc_callback_node {
	int (*callback) (u32 event, u32 ssid, u32 tsid,
			 u16 tclass, u32 perms,
			 u32 *out_retained);
	u32 events;
	u32 ssid;
	u32 tsid;
	u16 tclass;
	u32 perms;
	struct avc_callback_node *next;
};

/* Exported via selinufs */
unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;

#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
#endif

static struct avc_cache avc_cache;
static struct avc_callback_node *avc_callbacks;
static struct kmem_cache *avc_node_cachep;

static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
{
	return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
}

/**
 * avc_dump_av - Display an access vector in human-readable form.
 * @tclass: target security class
 * @av: access vector
 */
static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
{
	const char **common_pts = NULL;
	u32 common_base = 0;
	int i, i2, perm;

	if (av == 0) {
		audit_log_format(ab, " null");
		return;
	}

	for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
		if (av_inherit[i].tclass == tclass) {
			common_pts = av_inherit[i].common_pts;
			common_base = av_inherit[i].common_base;
			break;
		}
	}

	audit_log_format(ab, " {");
	i = 0;
	perm = 1;
	while (perm < common_base) {
		if (perm & av) {
			audit_log_format(ab, " %s", common_pts[i]);
			av &= ~perm;
		}
		i++;
		perm <<= 1;
	}

	while (i < sizeof(av) * 8) {
		if (perm & av) {
			for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
				if ((av_perm_to_string[i2].tclass == tclass) &&
				    (av_perm_to_string[i2].value == perm))
					break;
			}
			if (i2 < ARRAY_SIZE(av_perm_to_string)) {
				audit_log_format(ab, " %s",
						 av_perm_to_string[i2].name);
				av &= ~perm;
			}
		}
		i++;
		perm <<= 1;
	}

	if (av)
		audit_log_format(ab, " 0x%x", av);

	audit_log_format(ab, " }");
}

/**
 * avc_dump_query - Display a SID pair and a class in human-readable form.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 */
static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
{
	int rc;
	char *scontext;
	u32 scontext_len;

	rc = security_sid_to_context(ssid, &scontext, &scontext_len);
	if (rc)
		audit_log_format(ab, "ssid=%d", ssid);
	else {
		audit_log_format(ab, "scontext=%s", scontext);
		kfree(scontext);
	}

	rc = security_sid_to_context(tsid, &scontext, &scontext_len);
	if (rc)
		audit_log_format(ab, " tsid=%d", tsid);
	else {
		audit_log_format(ab, " tcontext=%s", scontext);
		kfree(scontext);
	}

	BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]);
	audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
}

/**
 * avc_init - Initialize the AVC.
 *
 * Initialize the access vector cache.
 */
void __init avc_init(void)
{
	int i;

	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
		INIT_LIST_HEAD(&avc_cache.slots[i]);
		spin_lock_init(&avc_cache.slots_lock[i]);
	}
	atomic_set(&avc_cache.active_nodes, 0);
	atomic_set(&avc_cache.lru_hint, 0);

	avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
					     0, SLAB_PANIC, NULL);

	audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
}

int avc_get_hash_stats(char *page)
{
	int i, chain_len, max_chain_len, slots_used;
	struct avc_node *node;

	rcu_read_lock();

	slots_used = 0;
	max_chain_len = 0;
	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
		if (!list_empty(&avc_cache.slots[i])) {
			slots_used++;
			chain_len = 0;
			list_for_each_entry_rcu(node, &avc_cache.slots[i], list)
				chain_len++;
			if (chain_len > max_chain_len)
				max_chain_len = chain_len;
		}
	}

	rcu_read_unlock();

	return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
			 "longest chain: %d\n",
			 atomic_read(&avc_cache.active_nodes),
			 slots_used, AVC_CACHE_SLOTS, max_chain_len);
}

static void avc_node_free(struct rcu_head *rhead)
{
	struct avc_node *node = container_of(rhead, struct avc_node, rhead);
	kmem_cache_free(avc_node_cachep, node);
	avc_cache_stats_incr(frees);
}

static void avc_node_delete(struct avc_node *node)
{
	list_del_rcu(&node->list);
	call_rcu(&node->rhead, avc_node_free);
	atomic_dec(&avc_cache.active_nodes);
}

static void avc_node_kill(struct avc_node *node)
{
	kmem_cache_free(avc_node_cachep, node);
	avc_cache_stats_incr(frees);
	atomic_dec(&avc_cache.active_nodes);
}

static void avc_node_replace(struct avc_node *new, struct avc_node *old)
{
	list_replace_rcu(&old->list, &new->list);
	call_rcu(&old->rhead, avc_node_free);
	atomic_dec(&avc_cache.active_nodes);
}

static inline int avc_reclaim_node(void)
{
	struct avc_node *node;
	int hvalue, try, ecx;
	unsigned long flags;

	for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
		hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);

		if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
			continue;

		rcu_read_lock();
		list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
			if (atomic_dec_and_test(&node->ae.used)) {
				/* Recently Unused */
				avc_node_delete(node);
				avc_cache_stats_incr(reclaims);
				ecx++;
				if (ecx >= AVC_CACHE_RECLAIM) {
					rcu_read_unlock();
					spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
					goto out;
				}
			}
		}
		rcu_read_unlock();
		spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
	}
out:
	return ecx;
}

static struct avc_node *avc_alloc_node(void)
{
	struct avc_node *node;

	node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
	if (!node)
		goto out;

	INIT_RCU_HEAD(&node->rhead);
	INIT_LIST_HEAD(&node->list);
	atomic_set(&node->ae.used, 1);
	avc_cache_stats_incr(allocations);

	if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
		avc_reclaim_node();

out:
	return node;
}

static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
{
	node->ae.ssid = ssid;
	node->ae.tsid = tsid;
	node->ae.tclass = tclass;
	memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd));
}

static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
{
	struct avc_node *node, *ret = NULL;
	int hvalue;

	hvalue = avc_hash(ssid, tsid, tclass);
	list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) {
		if (ssid == node->ae.ssid &&
		    tclass == node->ae.tclass &&
		    tsid == node->ae.tsid) {
			ret = node;
			break;
		}
	}

	if (ret == NULL) {
		/* cache miss */
		goto out;
	}

	/* cache hit */
	if (atomic_read(&ret->ae.used) != 1)
		atomic_set(&ret->ae.used, 1);
out:
	return ret;
}

/**
 * avc_lookup - Look up an AVC entry.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @requested: requested permissions, interpreted based on @tclass
 *
 * Look up an AVC entry that is valid for the
 * @requested permissions between the SID pair
 * (@ssid, @tsid), interpreting the permissions
 * based on @tclass.  If a valid AVC entry exists,
 * then this function return the avc_node.
 * Otherwise, this function returns NULL.
 */
static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested)
{
	struct avc_node *node;

	avc_cache_stats_incr(lookups);
	node = avc_search_node(ssid, tsid, tclass);

	if (node && ((node->ae.avd.decided & requested) == requested)) {
		avc_cache_stats_incr(hits);
		goto out;
	}

	node = NULL;
	avc_cache_stats_incr(misses);
out:
	return node;
}

static int avc_latest_notif_update(int seqno, int is_insert)
{
	int ret = 0;
	static DEFINE_SPINLOCK(notif_lock);
	unsigned long flag;

	spin_lock_irqsave(&notif_lock, flag);
	if (is_insert) {
		if (seqno < avc_cache.latest_notif) {
			printk(KERN_WARNING "SELinux: avc:  seqno %d < latest_notif %d\n",
			       seqno, avc_cache.latest_notif);
			ret = -EAGAIN;
		}
	} else {
		if (seqno > avc_cache.latest_notif)
			avc_cache.latest_notif = seqno;
	}
	spin_unlock_irqrestore(&notif_lock, flag);

	return ret;
}

/**
 * avc_insert - Insert an AVC entry.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @ae: AVC entry
 *
 * Insert an AVC entry for the SID pair
 * (@ssid, @tsid) and class @tclass.
 * The access vectors and the sequence number are
 * normally provided by the security server in
 * response to a security_compute_av() call.  If the
 * sequence number @ae->avd.seqno is not less than the latest
 * revocation notification, then the function copies
 * the access vectors into a cache entry, returns
 * avc_node inserted. Otherwise, this function returns NULL.
 */
static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
{
	struct avc_node *pos, *node = NULL;
	int hvalue;
	unsigned long flag;

	if (avc_latest_notif_update(ae->avd.seqno, 1))
		goto out;

	node = avc_alloc_node();
	if (node) {
		hvalue = avc_hash(ssid, tsid, tclass);
		avc_node_populate(node, ssid, tsid, tclass, ae);

		spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
		list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
			if (pos->ae.ssid == ssid &&
			    pos->ae.tsid == tsid &&
			    pos->ae.tclass == tclass) {
				avc_node_replace(node, pos);
				goto found;
			}
		}
		list_add_rcu(&node->list, &avc_cache.slots[hvalue]);
found:
		spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
	}
out:
	return node;
}

static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
				       struct in6_addr *addr, __be16 port,
				       char *name1, char *name2)
{
	if (!ipv6_addr_any(addr))
		audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr));
	if (port)
		audit_log_format(ab, " %s=%d", name2, ntohs(port));
}

static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
				       __be16 port, char *name1, char *name2)
{
	if (addr)
		audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr));
	if (port)
		audit_log_format(ab, " %s=%d", name2, ntohs(port));
}

/**
 * avc_audit - Audit the granting or denial of permissions.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @requested: requested permissions
 * @avd: access vector decisions
 * @result: result from avc_has_perm_noaudit
 * @a:  auxiliary audit data
 *
 * Audit the granting or denial of permissions in accordance
 * with the policy.  This function is typically called by
 * avc_has_perm() after a permission check, but can also be
 * called directly by callers who use avc_has_perm_noaudit()
 * in order to separate the permission check from the auditing.
 * For example, this separation is useful when the permission check must
 * be performed under a lock, to allow the lock to be released
 * before calling the auditing code.
 */
void avc_audit(u32 ssid, u32 tsid,
	       u16 tclass, u32 requested,
	       struct av_decision *avd, int result, struct avc_audit_data *a)
{
	struct task_struct *tsk = current;
	struct inode *inode = NULL;
	u32 denied, audited;
	struct audit_buffer *ab;

	denied = requested & ~avd->allowed;
	if (denied) {
		audited = denied;
		if (!(audited & avd->auditdeny))
			return;
	} else if (result) {
		audited = denied = requested;
	} else {
		audited = requested;
		if (!(audited & avd->auditallow))
			return;
	}

	ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
	if (!ab)
		return;		/* audit_panic has been called */
	audit_log_format(ab, "avc:  %s ", denied ? "denied" : "granted");
	avc_dump_av(ab, tclass, audited);
	audit_log_format(ab, " for ");
	if (a && a->tsk)
		tsk = a->tsk;
	if (tsk && tsk->pid) {
		audit_log_format(ab, " pid=%d comm=", tsk->pid);
		audit_log_untrustedstring(ab, tsk->comm);
	}
	if (a) {
		switch (a->type) {
		case AVC_AUDIT_DATA_IPC:
			audit_log_format(ab, " key=%d", a->u.ipc_id);
			break;
		case AVC_AUDIT_DATA_CAP:
			audit_log_format(ab, " capability=%d", a->u.cap);
			break;
		case AVC_AUDIT_DATA_FS:
			if (a->u.fs.path.dentry) {
				struct dentry *dentry = a->u.fs.path.dentry;
				if (a->u.fs.path.mnt) {
					audit_log_d_path(ab, "path=",
							 &a->u.fs.path);
				} else {
					audit_log_format(ab, " name=");
					audit_log_untrustedstring(ab, dentry->d_name.name);
				}
				inode = dentry->d_inode;
			} else if (a->u.fs.inode) {
				struct dentry *dentry;
				inode = a->u.fs.inode;
				dentry = d_find_alias(inode);
				if (dentry) {
					audit_log_format(ab, " name=");
					audit_log_untrustedstring(ab, dentry->d_name.name);
					dput(dentry);
				}
			}
			if (inode)
				audit_log_format(ab, " dev=%s ino=%lu",
						 inode->i_sb->s_id,
						 inode->i_ino);
			break;
		case AVC_AUDIT_DATA_NET:
			if (a->u.net.sk) {
				struct sock *sk = a->u.net.sk;
				struct unix_sock *u;
				int len = 0;
				char *p = NULL;

				switch (sk->sk_family) {
				case AF_INET: {
					struct inet_sock *inet = inet_sk(sk);

					avc_print_ipv4_addr(ab, inet->rcv_saddr,
							    inet->sport,
							    "laddr", "lport");
					avc_print_ipv4_addr(ab, inet->daddr,
							    inet->dport,
							    "faddr", "fport");
					break;
				}
				case AF_INET6: {
					struct inet_sock *inet = inet_sk(sk);
					struct ipv6_pinfo *inet6 = inet6_sk(sk);

					avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
							    inet->sport,
							    "laddr", "lport");
					avc_print_ipv6_addr(ab, &inet6->daddr,
							    inet->dport,
							    "faddr", "fport");
					break;
				}
				case AF_UNIX:
					u = unix_sk(sk);
					if (u->dentry) {
						struct path path = {
							.dentry = u->dentry,
							.mnt = u->mnt
						};
						audit_log_d_path(ab, "path=",
								 &path);
						break;
					}
					if (!u->addr)
						break;
					len = u->addr->len-sizeof(short);
					p = &u->addr->name->sun_path[0];
					audit_log_format(ab, " path=");
					if (*p)
						audit_log_untrustedstring(ab, p);
					else
						audit_log_hex(ab, p, len);
					break;
				}
			}

			switch (a->u.net.family) {
			case AF_INET:
				avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
						    a->u.net.sport,
						    "saddr", "src");
				avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
						    a->u.net.dport,
						    "daddr", "dest");
				break;
			case AF_INET6:
				avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
						    a->u.net.sport,
						    "saddr", "src");
				avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
						    a->u.net.dport,
						    "daddr", "dest");
				break;
			}
			if (a->u.net.netif > 0) {
				struct net_device *dev;

				/* NOTE: we always use init's namespace */
				dev = dev_get_by_index(&init_net,
						       a->u.net.netif);
				if (dev) {
					audit_log_format(ab, " netif=%s",
							 dev->name);
					dev_put(dev);
				}
			}
			break;
		}
	}
	audit_log_format(ab, " ");
	avc_dump_query(ab, ssid, tsid, tclass);
	audit_log_end(ab);
}

/**
 * avc_add_callback - Register a callback for security events.
 * @callback: callback function
 * @events: security events
 * @ssid: source security identifier or %SECSID_WILD
 * @tsid: target security identifier or %SECSID_WILD
 * @tclass: target security class
 * @perms: permissions
 *
 * Register a callback function for events in the set @events
 * related to the SID pair (@ssid, @tsid) and
 * and the permissions @perms, interpreting
 * @perms based on @tclass.  Returns %0 on success or
 * -%ENOMEM if insufficient memory exists to add the callback.
 */
int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
				     u16 tclass, u32 perms,
				     u32 *out_retained),
		     u32 events, u32 ssid, u32 tsid,
		     u16 tclass, u32 perms)
{
	struct avc_callback_node *c;
	int rc = 0;

	c = kmalloc(sizeof(*c), GFP_ATOMIC);
	if (!c) {
		rc = -ENOMEM;
		goto out;
	}

	c->callback = callback;
	c->events = events;
	c->ssid = ssid;
	c->tsid = tsid;
	c->perms = perms;
	c->next = avc_callbacks;
	avc_callbacks = c;
out:
	return rc;
}

static inline int avc_sidcmp(u32 x, u32 y)
{
	return (x == y || x == SECSID_WILD || y == SECSID_WILD);
}

/**
 * avc_update_node Update an AVC entry
 * @event : Updating event
 * @perms : Permission mask bits
 * @ssid,@tsid,@tclass : identifier of an AVC entry
 *
 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
 * otherwise, this function update the AVC entry. The original AVC-entry object
 * will release later by RCU.
 */
static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
{
	int hvalue, rc = 0;
	unsigned long flag;
	struct avc_node *pos, *node, *orig = NULL;

	node = avc_alloc_node();
	if (!node) {
		rc = -ENOMEM;
		goto out;
	}

	/* Lock the target slot */
	hvalue = avc_hash(ssid, tsid, tclass);
	spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);

	list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
		if (ssid == pos->ae.ssid &&
		    tsid == pos->ae.tsid &&
		    tclass == pos->ae.tclass){
			orig = pos;
			break;
		}
	}

	if (!orig) {
		rc = -ENOENT;
		avc_node_kill(node);
		goto out_unlock;
	}

	/*
	 * Copy and replace original node.
	 */

	avc_node_populate(node, ssid, tsid, tclass, &orig->ae);

	switch (event) {
	case AVC_CALLBACK_GRANT:
		node->ae.avd.allowed |= perms;
		break;
	case AVC_CALLBACK_TRY_REVOKE:
	case AVC_CALLBACK_REVOKE:
		node->ae.avd.allowed &= ~perms;
		break;
	case AVC_CALLBACK_AUDITALLOW_ENABLE:
		node->ae.avd.auditallow |= perms;
		break;
	case AVC_CALLBACK_AUDITALLOW_DISABLE:
		node->ae.avd.auditallow &= ~perms;
		break;
	case AVC_CALLBACK_AUDITDENY_ENABLE:
		node->ae.avd.auditdeny |= perms;
		break;
	case AVC_CALLBACK_AUDITDENY_DISABLE:
		node->ae.avd.auditdeny &= ~perms;
		break;
	}
	avc_node_replace(node, orig);
out_unlock:
	spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
out:
	return rc;
}

/**
 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
 * @seqno: policy sequence number
 */
int avc_ss_reset(u32 seqno)
{
	struct avc_callback_node *c;
	int i, rc = 0, tmprc;
	unsigned long flag;
	struct avc_node *node;

	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
		spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
		/*
		 * With preemptable RCU, the outer spinlock does not
		 * prevent RCU grace periods from ending.
		 */
		rcu_read_lock();
		list_for_each_entry(node, &avc_cache.slots[i], list)
			avc_node_delete(node);
		rcu_read_unlock();
		spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
	}

	for (c = avc_callbacks; c; c = c->next) {
		if (c->events & AVC_CALLBACK_RESET) {
			tmprc = c->callback(AVC_CALLBACK_RESET,
					    0, 0, 0, 0, NULL);
			/* save the first error encountered for the return
			   value and continue processing the callbacks */
			if (!rc)
				rc = tmprc;
		}
	}

	avc_latest_notif_update(seqno, 0);
	return rc;
}

/**
 * avc_has_perm_noaudit - Check permissions but perform no auditing.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @requested: requested permissions, interpreted based on @tclass
 * @flags:  AVC_STRICT or 0
 * @avd: access vector decisions
 *
 * Check the AVC to determine whether the @requested permissions are granted
 * for the SID pair (@ssid, @tsid), interpreting the permissions
 * based on @tclass, and call the security server on a cache miss to obtain
 * a new decision and add it to the cache.  Return a copy of the decisions
 * in @avd.  Return %0 if all @requested permissions are granted,
 * -%EACCES if any permissions are denied, or another -errno upon
 * other errors.  This function is typically called by avc_has_perm(),
 * but may also be called directly to separate permission checking from
 * auditing, e.g. in cases where a lock must be held for the check but
 * should be released for the auditing.
 */
int avc_has_perm_noaudit(u32 ssid, u32 tsid,
			 u16 tclass, u32 requested,
			 unsigned flags,
			 struct av_decision *avd)
{
	struct avc_node *node;
	struct avc_entry entry, *p_ae;
	int rc = 0;
	u32 denied;

	BUG_ON(!requested);

	rcu_read_lock();

	node = avc_lookup(ssid, tsid, tclass, requested);
	if (!node) {
		rcu_read_unlock();
		rc = security_compute_av(ssid, tsid, tclass, requested, &entry.avd);
		if (rc)
			goto out;
		rcu_read_lock();
		node = avc_insert(ssid, tsid, tclass, &entry);
	}

	p_ae = node ? &node->ae : &entry;

	if (avd)
		memcpy(avd, &p_ae->avd, sizeof(*avd));

	denied = requested & ~(p_ae->avd.allowed);

	if (denied) {
		if (flags & AVC_STRICT)
			rc = -EACCES;
		else if (!selinux_enforcing || security_permissive_sid(ssid))
			avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
					tsid, tclass);
		else
			rc = -EACCES;
	}

	rcu_read_unlock();
out:
	return rc;
}

/**
 * avc_has_perm - Check permissions and perform any appropriate auditing.
 * @ssid: source security identifier
 * @tsid: target security identifier
 * @tclass: target security class
 * @requested: requested permissions, interpreted based on @tclass
 * @auditdata: auxiliary audit data
 *
 * Check the AVC to determine whether the @requested permissions are granted
 * for the SID pair (@ssid, @tsid), interpreting the permissions
 * based on @tclass, and call the security server on a cache miss to obtain
 * a new decision and add it to the cache.  Audit the granting or denial of
 * permissions in accordance with the policy.  Return %0 if all @requested
 * permissions are granted, -%EACCES if any permissions are denied, or
 * another -errno upon other errors.
 */
int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
		 u32 requested, struct avc_audit_data *auditdata)
{
	struct av_decision avd;
	int rc;

	rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
	avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
	return rc;
}

u32 avc_policy_seqno(void)
{
	return avc_cache.latest_notif;
}
OpenPOWER on IntegriCloud