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1/*
2 * Implementation of the kernel access vector cache (AVC).
3 *
4 * Authors: Stephen Smalley, <sds@epoch.ncsc.mil>
5 * James Morris <jmorris@redhat.com>
6 *
7 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
8 * Replaced the avc_lock spinlock by RCU.
9 *
10 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
11 *
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2,
14 * as published by the Free Software Foundation.
15 */
16#include <linux/types.h>
17#include <linux/stddef.h>
18#include <linux/kernel.h>
19#include <linux/slab.h>
20#include <linux/fs.h>
21#include <linux/dcache.h>
22#include <linux/init.h>
23#include <linux/skbuff.h>
24#include <linux/percpu.h>
25#include <net/sock.h>
26#include <linux/un.h>
27#include <net/af_unix.h>
28#include <linux/ip.h>
29#include <linux/audit.h>
30#include <linux/ipv6.h>
31#include <net/ipv6.h>
32#include "avc.h"
33#include "avc_ss.h"
34#include "classmap.h"
35
36#define AVC_CACHE_SLOTS 512
37#define AVC_DEF_CACHE_THRESHOLD 512
38#define AVC_CACHE_RECLAIM 16
39
40#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
41#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
42#else
43#define avc_cache_stats_incr(field) do {} while (0)
44#endif
45
46struct avc_entry {
47 u32 ssid;
48 u32 tsid;
49 u16 tclass;
50 struct av_decision avd;
51};
52
53struct avc_node {
54 struct avc_entry ae;
55 struct hlist_node list; /* anchored in avc_cache->slots[i] */
56 struct rcu_head rhead;
57};
58
59struct avc_cache {
60 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
61 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
62 atomic_t lru_hint; /* LRU hint for reclaim scan */
63 atomic_t active_nodes;
64 u32 latest_notif; /* latest revocation notification */
65};
66
67struct avc_callback_node {
68 int (*callback) (u32 event);
69 u32 events;
70 struct avc_callback_node *next;
71};
72
73/* Exported via selinufs */
74unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
75
76#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
77DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
78#endif
79
80static struct avc_cache avc_cache;
81static struct avc_callback_node *avc_callbacks;
82static struct kmem_cache *avc_node_cachep;
83
84static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
85{
86 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
87}
88
89/**
90 * avc_dump_av - Display an access vector in human-readable form.
91 * @tclass: target security class
92 * @av: access vector
93 */
94static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
95{
96 const char **perms;
97 int i, perm;
98
99 if (av == 0) {
100 audit_log_format(ab, " null");
101 return;
102 }
103
104 perms = secclass_map[tclass-1].perms;
105
106 audit_log_format(ab, " {");
107 i = 0;
108 perm = 1;
109 while (i < (sizeof(av) * 8)) {
110 if ((perm & av) && perms[i]) {
111 audit_log_format(ab, " %s", perms[i]);
112 av &= ~perm;
113 }
114 i++;
115 perm <<= 1;
116 }
117
118 if (av)
119 audit_log_format(ab, " 0x%x", av);
120
121 audit_log_format(ab, " }");
122}
123
124/**
125 * avc_dump_query - Display a SID pair and a class in human-readable form.
126 * @ssid: source security identifier
127 * @tsid: target security identifier
128 * @tclass: target security class
129 */
130static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
131{
132 int rc;
133 char *scontext;
134 u32 scontext_len;
135
136 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
137 if (rc)
138 audit_log_format(ab, "ssid=%d", ssid);
139 else {
140 audit_log_format(ab, "scontext=%s", scontext);
141 kfree(scontext);
142 }
143
144 rc = security_sid_to_context(tsid, &scontext, &scontext_len);
145 if (rc)
146 audit_log_format(ab, " tsid=%d", tsid);
147 else {
148 audit_log_format(ab, " tcontext=%s", scontext);
149 kfree(scontext);
150 }
151
152 BUG_ON(tclass >= ARRAY_SIZE(secclass_map));
153 audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
154}
155
156/**
157 * avc_init - Initialize the AVC.
158 *
159 * Initialize the access vector cache.
160 */
161void __init avc_init(void)
162{
163 int i;
164
165 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
166 INIT_HLIST_HEAD(&avc_cache.slots[i]);
167 spin_lock_init(&avc_cache.slots_lock[i]);
168 }
169 atomic_set(&avc_cache.active_nodes, 0);
170 atomic_set(&avc_cache.lru_hint, 0);
171
172 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
173 0, SLAB_PANIC, NULL);
174
175 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
176}
177
178int avc_get_hash_stats(char *page)
179{
180 int i, chain_len, max_chain_len, slots_used;
181 struct avc_node *node;
182 struct hlist_head *head;
183
184 rcu_read_lock();
185
186 slots_used = 0;
187 max_chain_len = 0;
188 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
189 head = &avc_cache.slots[i];
190 if (!hlist_empty(head)) {
191 struct hlist_node *next;
192
193 slots_used++;
194 chain_len = 0;
195 hlist_for_each_entry_rcu(node, next, head, list)
196 chain_len++;
197 if (chain_len > max_chain_len)
198 max_chain_len = chain_len;
199 }
200 }
201
202 rcu_read_unlock();
203
204 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
205 "longest chain: %d\n",
206 atomic_read(&avc_cache.active_nodes),
207 slots_used, AVC_CACHE_SLOTS, max_chain_len);
208}
209
210static void avc_node_free(struct rcu_head *rhead)
211{
212 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
213 kmem_cache_free(avc_node_cachep, node);
214 avc_cache_stats_incr(frees);
215}
216
217static void avc_node_delete(struct avc_node *node)
218{
219 hlist_del_rcu(&node->list);
220 call_rcu(&node->rhead, avc_node_free);
221 atomic_dec(&avc_cache.active_nodes);
222}
223
224static void avc_node_kill(struct avc_node *node)
225{
226 kmem_cache_free(avc_node_cachep, node);
227 avc_cache_stats_incr(frees);
228 atomic_dec(&avc_cache.active_nodes);
229}
230
231static void avc_node_replace(struct avc_node *new, struct avc_node *old)
232{
233 hlist_replace_rcu(&old->list, &new->list);
234 call_rcu(&old->rhead, avc_node_free);
235 atomic_dec(&avc_cache.active_nodes);
236}
237
238static inline int avc_reclaim_node(void)
239{
240 struct avc_node *node;
241 int hvalue, try, ecx;
242 unsigned long flags;
243 struct hlist_head *head;
244 struct hlist_node *next;
245 spinlock_t *lock;
246
247 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
248 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
249 head = &avc_cache.slots[hvalue];
250 lock = &avc_cache.slots_lock[hvalue];
251
252 if (!spin_trylock_irqsave(lock, flags))
253 continue;
254
255 rcu_read_lock();
256 hlist_for_each_entry(node, next, head, list) {
257 avc_node_delete(node);
258 avc_cache_stats_incr(reclaims);
259 ecx++;
260 if (ecx >= AVC_CACHE_RECLAIM) {
261 rcu_read_unlock();
262 spin_unlock_irqrestore(lock, flags);
263 goto out;
264 }
265 }
266 rcu_read_unlock();
267 spin_unlock_irqrestore(lock, flags);
268 }
269out:
270 return ecx;
271}
272
273static struct avc_node *avc_alloc_node(void)
274{
275 struct avc_node *node;
276
277 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
278 if (!node)
279 goto out;
280
281 INIT_HLIST_NODE(&node->list);
282 avc_cache_stats_incr(allocations);
283
284 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
285 avc_reclaim_node();
286
287out:
288 return node;
289}
290
291static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
292{
293 node->ae.ssid = ssid;
294 node->ae.tsid = tsid;
295 node->ae.tclass = tclass;
296 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
297}
298
299static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
300{
301 struct avc_node *node, *ret = NULL;
302 int hvalue;
303 struct hlist_head *head;
304 struct hlist_node *next;
305
306 hvalue = avc_hash(ssid, tsid, tclass);
307 head = &avc_cache.slots[hvalue];
308 hlist_for_each_entry_rcu(node, next, head, list) {
309 if (ssid == node->ae.ssid &&
310 tclass == node->ae.tclass &&
311 tsid == node->ae.tsid) {
312 ret = node;
313 break;
314 }
315 }
316
317 return ret;
318}
319
320/**
321 * avc_lookup - Look up an AVC entry.
322 * @ssid: source security identifier
323 * @tsid: target security identifier
324 * @tclass: target security class
325 *
326 * Look up an AVC entry that is valid for the
327 * (@ssid, @tsid), interpreting the permissions
328 * based on @tclass. If a valid AVC entry exists,
329 * then this function returns the avc_node.
330 * Otherwise, this function returns NULL.
331 */
332static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
333{
334 struct avc_node *node;
335
336 avc_cache_stats_incr(lookups);
337 node = avc_search_node(ssid, tsid, tclass);
338
339 if (node)
340 return node;
341
342 avc_cache_stats_incr(misses);
343 return NULL;
344}
345
346static int avc_latest_notif_update(int seqno, int is_insert)
347{
348 int ret = 0;
349 static DEFINE_SPINLOCK(notif_lock);
350 unsigned long flag;
351
352 spin_lock_irqsave(¬if_lock, flag);
353 if (is_insert) {
354 if (seqno < avc_cache.latest_notif) {
355 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
356 seqno, avc_cache.latest_notif);
357 ret = -EAGAIN;
358 }
359 } else {
360 if (seqno > avc_cache.latest_notif)
361 avc_cache.latest_notif = seqno;
362 }
363 spin_unlock_irqrestore(¬if_lock, flag);
364
365 return ret;
366}
367
368/**
369 * avc_insert - Insert an AVC entry.
370 * @ssid: source security identifier
371 * @tsid: target security identifier
372 * @tclass: target security class
373 * @avd: resulting av decision
374 *
375 * Insert an AVC entry for the SID pair
376 * (@ssid, @tsid) and class @tclass.
377 * The access vectors and the sequence number are
378 * normally provided by the security server in
379 * response to a security_compute_av() call. If the
380 * sequence number @avd->seqno is not less than the latest
381 * revocation notification, then the function copies
382 * the access vectors into a cache entry, returns
383 * avc_node inserted. Otherwise, this function returns NULL.
384 */
385static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
386{
387 struct avc_node *pos, *node = NULL;
388 int hvalue;
389 unsigned long flag;
390
391 if (avc_latest_notif_update(avd->seqno, 1))
392 goto out;
393
394 node = avc_alloc_node();
395 if (node) {
396 struct hlist_head *head;
397 struct hlist_node *next;
398 spinlock_t *lock;
399
400 hvalue = avc_hash(ssid, tsid, tclass);
401 avc_node_populate(node, ssid, tsid, tclass, avd);
402
403 head = &avc_cache.slots[hvalue];
404 lock = &avc_cache.slots_lock[hvalue];
405
406 spin_lock_irqsave(lock, flag);
407 hlist_for_each_entry(pos, next, head, list) {
408 if (pos->ae.ssid == ssid &&
409 pos->ae.tsid == tsid &&
410 pos->ae.tclass == tclass) {
411 avc_node_replace(node, pos);
412 goto found;
413 }
414 }
415 hlist_add_head_rcu(&node->list, head);
416found:
417 spin_unlock_irqrestore(lock, flag);
418 }
419out:
420 return node;
421}
422
423/**
424 * avc_audit_pre_callback - SELinux specific information
425 * will be called by generic audit code
426 * @ab: the audit buffer
427 * @a: audit_data
428 */
429static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
430{
431 struct common_audit_data *ad = a;
432 audit_log_format(ab, "avc: %s ",
433 ad->selinux_audit_data->denied ? "denied" : "granted");
434 avc_dump_av(ab, ad->selinux_audit_data->tclass,
435 ad->selinux_audit_data->audited);
436 audit_log_format(ab, " for ");
437}
438
439/**
440 * avc_audit_post_callback - SELinux specific information
441 * will be called by generic audit code
442 * @ab: the audit buffer
443 * @a: audit_data
444 */
445static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
446{
447 struct common_audit_data *ad = a;
448 audit_log_format(ab, " ");
449 avc_dump_query(ab, ad->selinux_audit_data->ssid,
450 ad->selinux_audit_data->tsid,
451 ad->selinux_audit_data->tclass);
452}
453
454/* This is the slow part of avc audit with big stack footprint */
455noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
456 u32 requested, u32 audited, u32 denied,
457 struct common_audit_data *a,
458 unsigned flags)
459{
460 struct common_audit_data stack_data;
461 struct selinux_audit_data sad;
462
463 if (!a) {
464 a = &stack_data;
465 a->type = LSM_AUDIT_DATA_NONE;
466 }
467
468 /*
469 * When in a RCU walk do the audit on the RCU retry. This is because
470 * the collection of the dname in an inode audit message is not RCU
471 * safe. Note this may drop some audits when the situation changes
472 * during retry. However this is logically just as if the operation
473 * happened a little later.
474 */
475 if ((a->type == LSM_AUDIT_DATA_INODE) &&
476 (flags & MAY_NOT_BLOCK))
477 return -ECHILD;
478
479 sad.tclass = tclass;
480 sad.requested = requested;
481 sad.ssid = ssid;
482 sad.tsid = tsid;
483 sad.audited = audited;
484 sad.denied = denied;
485
486 a->selinux_audit_data = &sad;
487
488 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
489 return 0;
490}
491
492/**
493 * avc_add_callback - Register a callback for security events.
494 * @callback: callback function
495 * @events: security events
496 *
497 * Register a callback function for events in the set @events.
498 * Returns %0 on success or -%ENOMEM if insufficient memory
499 * exists to add the callback.
500 */
501int __init avc_add_callback(int (*callback)(u32 event), u32 events)
502{
503 struct avc_callback_node *c;
504 int rc = 0;
505
506 c = kmalloc(sizeof(*c), GFP_KERNEL);
507 if (!c) {
508 rc = -ENOMEM;
509 goto out;
510 }
511
512 c->callback = callback;
513 c->events = events;
514 c->next = avc_callbacks;
515 avc_callbacks = c;
516out:
517 return rc;
518}
519
520static inline int avc_sidcmp(u32 x, u32 y)
521{
522 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
523}
524
525/**
526 * avc_update_node Update an AVC entry
527 * @event : Updating event
528 * @perms : Permission mask bits
529 * @ssid,@tsid,@tclass : identifier of an AVC entry
530 * @seqno : sequence number when decision was made
531 *
532 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
533 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
534 * otherwise, this function updates the AVC entry. The original AVC-entry object
535 * will release later by RCU.
536 */
537static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
538 u32 seqno)
539{
540 int hvalue, rc = 0;
541 unsigned long flag;
542 struct avc_node *pos, *node, *orig = NULL;
543 struct hlist_head *head;
544 struct hlist_node *next;
545 spinlock_t *lock;
546
547 node = avc_alloc_node();
548 if (!node) {
549 rc = -ENOMEM;
550 goto out;
551 }
552
553 /* Lock the target slot */
554 hvalue = avc_hash(ssid, tsid, tclass);
555
556 head = &avc_cache.slots[hvalue];
557 lock = &avc_cache.slots_lock[hvalue];
558
559 spin_lock_irqsave(lock, flag);
560
561 hlist_for_each_entry(pos, next, head, list) {
562 if (ssid == pos->ae.ssid &&
563 tsid == pos->ae.tsid &&
564 tclass == pos->ae.tclass &&
565 seqno == pos->ae.avd.seqno){
566 orig = pos;
567 break;
568 }
569 }
570
571 if (!orig) {
572 rc = -ENOENT;
573 avc_node_kill(node);
574 goto out_unlock;
575 }
576
577 /*
578 * Copy and replace original node.
579 */
580
581 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
582
583 switch (event) {
584 case AVC_CALLBACK_GRANT:
585 node->ae.avd.allowed |= perms;
586 break;
587 case AVC_CALLBACK_TRY_REVOKE:
588 case AVC_CALLBACK_REVOKE:
589 node->ae.avd.allowed &= ~perms;
590 break;
591 case AVC_CALLBACK_AUDITALLOW_ENABLE:
592 node->ae.avd.auditallow |= perms;
593 break;
594 case AVC_CALLBACK_AUDITALLOW_DISABLE:
595 node->ae.avd.auditallow &= ~perms;
596 break;
597 case AVC_CALLBACK_AUDITDENY_ENABLE:
598 node->ae.avd.auditdeny |= perms;
599 break;
600 case AVC_CALLBACK_AUDITDENY_DISABLE:
601 node->ae.avd.auditdeny &= ~perms;
602 break;
603 }
604 avc_node_replace(node, orig);
605out_unlock:
606 spin_unlock_irqrestore(lock, flag);
607out:
608 return rc;
609}
610
611/**
612 * avc_flush - Flush the cache
613 */
614static void avc_flush(void)
615{
616 struct hlist_head *head;
617 struct hlist_node *next;
618 struct avc_node *node;
619 spinlock_t *lock;
620 unsigned long flag;
621 int i;
622
623 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
624 head = &avc_cache.slots[i];
625 lock = &avc_cache.slots_lock[i];
626
627 spin_lock_irqsave(lock, flag);
628 /*
629 * With preemptable RCU, the outer spinlock does not
630 * prevent RCU grace periods from ending.
631 */
632 rcu_read_lock();
633 hlist_for_each_entry(node, next, head, list)
634 avc_node_delete(node);
635 rcu_read_unlock();
636 spin_unlock_irqrestore(lock, flag);
637 }
638}
639
640/**
641 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
642 * @seqno: policy sequence number
643 */
644int avc_ss_reset(u32 seqno)
645{
646 struct avc_callback_node *c;
647 int rc = 0, tmprc;
648
649 avc_flush();
650
651 for (c = avc_callbacks; c; c = c->next) {
652 if (c->events & AVC_CALLBACK_RESET) {
653 tmprc = c->callback(AVC_CALLBACK_RESET);
654 /* save the first error encountered for the return
655 value and continue processing the callbacks */
656 if (!rc)
657 rc = tmprc;
658 }
659 }
660
661 avc_latest_notif_update(seqno, 0);
662 return rc;
663}
664
665/*
666 * Slow-path helper function for avc_has_perm_noaudit,
667 * when the avc_node lookup fails. We get called with
668 * the RCU read lock held, and need to return with it
669 * still held, but drop if for the security compute.
670 *
671 * Don't inline this, since it's the slow-path and just
672 * results in a bigger stack frame.
673 */
674static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid,
675 u16 tclass, struct av_decision *avd)
676{
677 rcu_read_unlock();
678 security_compute_av(ssid, tsid, tclass, avd);
679 rcu_read_lock();
680 return avc_insert(ssid, tsid, tclass, avd);
681}
682
683static noinline int avc_denied(u32 ssid, u32 tsid,
684 u16 tclass, u32 requested,
685 unsigned flags,
686 struct av_decision *avd)
687{
688 if (flags & AVC_STRICT)
689 return -EACCES;
690
691 if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE))
692 return -EACCES;
693
694 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
695 tsid, tclass, avd->seqno);
696 return 0;
697}
698
699
700/**
701 * avc_has_perm_noaudit - Check permissions but perform no auditing.
702 * @ssid: source security identifier
703 * @tsid: target security identifier
704 * @tclass: target security class
705 * @requested: requested permissions, interpreted based on @tclass
706 * @flags: AVC_STRICT or 0
707 * @avd: access vector decisions
708 *
709 * Check the AVC to determine whether the @requested permissions are granted
710 * for the SID pair (@ssid, @tsid), interpreting the permissions
711 * based on @tclass, and call the security server on a cache miss to obtain
712 * a new decision and add it to the cache. Return a copy of the decisions
713 * in @avd. Return %0 if all @requested permissions are granted,
714 * -%EACCES if any permissions are denied, or another -errno upon
715 * other errors. This function is typically called by avc_has_perm(),
716 * but may also be called directly to separate permission checking from
717 * auditing, e.g. in cases where a lock must be held for the check but
718 * should be released for the auditing.
719 */
720inline int avc_has_perm_noaudit(u32 ssid, u32 tsid,
721 u16 tclass, u32 requested,
722 unsigned flags,
723 struct av_decision *avd)
724{
725 struct avc_node *node;
726 int rc = 0;
727 u32 denied;
728
729 BUG_ON(!requested);
730
731 rcu_read_lock();
732
733 node = avc_lookup(ssid, tsid, tclass);
734 if (unlikely(!node)) {
735 node = avc_compute_av(ssid, tsid, tclass, avd);
736 } else {
737 memcpy(avd, &node->ae.avd, sizeof(*avd));
738 avd = &node->ae.avd;
739 }
740
741 denied = requested & ~(avd->allowed);
742 if (unlikely(denied))
743 rc = avc_denied(ssid, tsid, tclass, requested, flags, avd);
744
745 rcu_read_unlock();
746 return rc;
747}
748
749/**
750 * avc_has_perm - Check permissions and perform any appropriate auditing.
751 * @ssid: source security identifier
752 * @tsid: target security identifier
753 * @tclass: target security class
754 * @requested: requested permissions, interpreted based on @tclass
755 * @auditdata: auxiliary audit data
756 * @flags: VFS walk flags
757 *
758 * Check the AVC to determine whether the @requested permissions are granted
759 * for the SID pair (@ssid, @tsid), interpreting the permissions
760 * based on @tclass, and call the security server on a cache miss to obtain
761 * a new decision and add it to the cache. Audit the granting or denial of
762 * permissions in accordance with the policy. Return %0 if all @requested
763 * permissions are granted, -%EACCES if any permissions are denied, or
764 * another -errno upon other errors.
765 */
766int avc_has_perm_flags(u32 ssid, u32 tsid, u16 tclass,
767 u32 requested, struct common_audit_data *auditdata,
768 unsigned flags)
769{
770 struct av_decision avd;
771 int rc, rc2;
772
773 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
774
775 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata,
776 flags);
777 if (rc2)
778 return rc2;
779 return rc;
780}
781
782u32 avc_policy_seqno(void)
783{
784 return avc_cache.latest_notif;
785}
786
787void avc_disable(void)
788{
789 /*
790 * If you are looking at this because you have realized that we are
791 * not destroying the avc_node_cachep it might be easy to fix, but
792 * I don't know the memory barrier semantics well enough to know. It's
793 * possible that some other task dereferenced security_ops when
794 * it still pointed to selinux operations. If that is the case it's
795 * possible that it is about to use the avc and is about to need the
796 * avc_node_cachep. I know I could wrap the security.c security_ops call
797 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
798 * the cache and get that memory back.
799 */
800 if (avc_node_cachep) {
801 avc_flush();
802 /* kmem_cache_destroy(avc_node_cachep); */
803 }
804}