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1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Implementation of the kernel access vector cache (AVC).
4  *
5  * Authors:  Stephen Smalley, <sds@tycho.nsa.gov>
6  *	     James Morris <jmorris@redhat.com>
7  *
8  * Update:   KaiGai, Kohei <kaigai@ak.jp.nec.com>
9  *	Replaced the avc_lock spinlock by RCU.
10  *
11  * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
12  */
13 #include <linux/types.h>
14 #include <linux/stddef.h>
15 #include <linux/kernel.h>
16 #include <linux/slab.h>
17 #include <linux/fs.h>
18 #include <linux/dcache.h>
19 #include <linux/init.h>
20 #include <linux/skbuff.h>
21 #include <linux/percpu.h>
22 #include <linux/list.h>
23 #include <net/sock.h>
24 #include <linux/un.h>
25 #include <net/af_unix.h>
26 #include <linux/ip.h>
27 #include <linux/audit.h>
28 #include <linux/ipv6.h>
29 #include <net/ipv6.h>
30 #include "avc.h"
31 #include "avc_ss.h"
32 #include "classmap.h"
33 
34 #define CREATE_TRACE_POINTS
35 #include <trace/events/avc.h>
36 
37 #define AVC_CACHE_SLOTS			512
38 #define AVC_DEF_CACHE_THRESHOLD		512
39 #define AVC_CACHE_RECLAIM		16
40 
41 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
42 #define avc_cache_stats_incr(field)	this_cpu_inc(avc_cache_stats.field)
43 #else
44 #define avc_cache_stats_incr(field)	do {} while (0)
45 #endif
46 
47 #undef CREATE_TRACE_POINTS
48 #include <trace/hooks/avc.h>
49 
50 struct avc_entry {
51 	u32			ssid;
52 	u32			tsid;
53 	u16			tclass;
54 	struct av_decision	avd;
55 	struct avc_xperms_node	*xp_node;
56 };
57 
58 struct avc_node {
59 	struct avc_entry	ae;
60 	struct hlist_node	list; /* anchored in avc_cache->slots[i] */
61 	struct rcu_head		rhead;
62 };
63 
64 struct avc_xperms_decision_node {
65 	struct extended_perms_decision xpd;
66 	struct list_head xpd_list; /* list of extended_perms_decision */
67 };
68 
69 struct avc_xperms_node {
70 	struct extended_perms xp;
71 	struct list_head xpd_head; /* list head of extended_perms_decision */
72 };
73 
74 struct avc_cache {
75 	struct hlist_head	slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
76 	spinlock_t		slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
77 	atomic_t		lru_hint;	/* LRU hint for reclaim scan */
78 	atomic_t		active_nodes;
79 	u32			latest_notif;	/* latest revocation notification */
80 };
81 
82 struct avc_callback_node {
83 	int (*callback) (u32 event);
84 	u32 events;
85 	struct avc_callback_node *next;
86 };
87 
88 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
89 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
90 #endif
91 
92 struct selinux_avc {
93 	unsigned int avc_cache_threshold;
94 	struct avc_cache avc_cache;
95 };
96 
97 static struct selinux_avc selinux_avc;
98 
selinux_avc_init(struct selinux_avc ** avc)99 void selinux_avc_init(struct selinux_avc **avc)
100 {
101 	int i;
102 
103 	selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
104 	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
105 		INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
106 		spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
107 	}
108 	atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
109 	atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
110 	*avc = &selinux_avc;
111 }
112 
avc_get_cache_threshold(struct selinux_avc * avc)113 unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
114 {
115 	return avc->avc_cache_threshold;
116 }
117 
avc_set_cache_threshold(struct selinux_avc * avc,unsigned int cache_threshold)118 void avc_set_cache_threshold(struct selinux_avc *avc,
119 			     unsigned int cache_threshold)
120 {
121 	avc->avc_cache_threshold = cache_threshold;
122 }
123 
124 static struct avc_callback_node *avc_callbacks __ro_after_init;
125 static struct kmem_cache *avc_node_cachep __ro_after_init;
126 static struct kmem_cache *avc_xperms_data_cachep __ro_after_init;
127 static struct kmem_cache *avc_xperms_decision_cachep __ro_after_init;
128 static struct kmem_cache *avc_xperms_cachep __ro_after_init;
129 
avc_hash(u32 ssid,u32 tsid,u16 tclass)130 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
131 {
132 	return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
133 }
134 
135 /**
136  * avc_init - Initialize the AVC.
137  *
138  * Initialize the access vector cache.
139  */
avc_init(void)140 void __init avc_init(void)
141 {
142 	avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
143 					0, SLAB_PANIC, NULL);
144 	avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
145 					sizeof(struct avc_xperms_node),
146 					0, SLAB_PANIC, NULL);
147 	avc_xperms_decision_cachep = kmem_cache_create(
148 					"avc_xperms_decision_node",
149 					sizeof(struct avc_xperms_decision_node),
150 					0, SLAB_PANIC, NULL);
151 	avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
152 					sizeof(struct extended_perms_data),
153 					0, SLAB_PANIC, NULL);
154 }
155 
avc_get_hash_stats(struct selinux_avc * avc,char * page)156 int avc_get_hash_stats(struct selinux_avc *avc, char *page)
157 {
158 	int i, chain_len, max_chain_len, slots_used;
159 	struct avc_node *node;
160 	struct hlist_head *head;
161 
162 	rcu_read_lock();
163 
164 	slots_used = 0;
165 	max_chain_len = 0;
166 	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
167 		head = &avc->avc_cache.slots[i];
168 		if (!hlist_empty(head)) {
169 			slots_used++;
170 			chain_len = 0;
171 			hlist_for_each_entry_rcu(node, head, list)
172 				chain_len++;
173 			if (chain_len > max_chain_len)
174 				max_chain_len = chain_len;
175 		}
176 	}
177 
178 	rcu_read_unlock();
179 
180 	return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
181 			 "longest chain: %d\n",
182 			 atomic_read(&avc->avc_cache.active_nodes),
183 			 slots_used, AVC_CACHE_SLOTS, max_chain_len);
184 }
185 
186 /*
187  * using a linked list for extended_perms_decision lookup because the list is
188  * always small. i.e. less than 5, typically 1
189  */
avc_xperms_decision_lookup(u8 driver,struct avc_xperms_node * xp_node)190 static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
191 					struct avc_xperms_node *xp_node)
192 {
193 	struct avc_xperms_decision_node *xpd_node;
194 
195 	list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
196 		if (xpd_node->xpd.driver == driver)
197 			return &xpd_node->xpd;
198 	}
199 	return NULL;
200 }
201 
202 static inline unsigned int
avc_xperms_has_perm(struct extended_perms_decision * xpd,u8 perm,u8 which)203 avc_xperms_has_perm(struct extended_perms_decision *xpd,
204 					u8 perm, u8 which)
205 {
206 	unsigned int rc = 0;
207 
208 	if ((which == XPERMS_ALLOWED) &&
209 			(xpd->used & XPERMS_ALLOWED))
210 		rc = security_xperm_test(xpd->allowed->p, perm);
211 	else if ((which == XPERMS_AUDITALLOW) &&
212 			(xpd->used & XPERMS_AUDITALLOW))
213 		rc = security_xperm_test(xpd->auditallow->p, perm);
214 	else if ((which == XPERMS_DONTAUDIT) &&
215 			(xpd->used & XPERMS_DONTAUDIT))
216 		rc = security_xperm_test(xpd->dontaudit->p, perm);
217 	return rc;
218 }
219 
avc_xperms_allow_perm(struct avc_xperms_node * xp_node,u8 driver,u8 perm)220 static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
221 				u8 driver, u8 perm)
222 {
223 	struct extended_perms_decision *xpd;
224 	security_xperm_set(xp_node->xp.drivers.p, driver);
225 	xpd = avc_xperms_decision_lookup(driver, xp_node);
226 	if (xpd && xpd->allowed)
227 		security_xperm_set(xpd->allowed->p, perm);
228 }
229 
avc_xperms_decision_free(struct avc_xperms_decision_node * xpd_node)230 static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
231 {
232 	struct extended_perms_decision *xpd;
233 
234 	xpd = &xpd_node->xpd;
235 	if (xpd->allowed)
236 		kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
237 	if (xpd->auditallow)
238 		kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
239 	if (xpd->dontaudit)
240 		kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
241 	kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
242 }
243 
avc_xperms_free(struct avc_xperms_node * xp_node)244 static void avc_xperms_free(struct avc_xperms_node *xp_node)
245 {
246 	struct avc_xperms_decision_node *xpd_node, *tmp;
247 
248 	if (!xp_node)
249 		return;
250 
251 	list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
252 		list_del(&xpd_node->xpd_list);
253 		avc_xperms_decision_free(xpd_node);
254 	}
255 	kmem_cache_free(avc_xperms_cachep, xp_node);
256 }
257 
avc_copy_xperms_decision(struct extended_perms_decision * dest,struct extended_perms_decision * src)258 static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
259 					struct extended_perms_decision *src)
260 {
261 	dest->driver = src->driver;
262 	dest->used = src->used;
263 	if (dest->used & XPERMS_ALLOWED)
264 		memcpy(dest->allowed->p, src->allowed->p,
265 				sizeof(src->allowed->p));
266 	if (dest->used & XPERMS_AUDITALLOW)
267 		memcpy(dest->auditallow->p, src->auditallow->p,
268 				sizeof(src->auditallow->p));
269 	if (dest->used & XPERMS_DONTAUDIT)
270 		memcpy(dest->dontaudit->p, src->dontaudit->p,
271 				sizeof(src->dontaudit->p));
272 }
273 
274 /*
275  * similar to avc_copy_xperms_decision, but only copy decision
276  * information relevant to this perm
277  */
avc_quick_copy_xperms_decision(u8 perm,struct extended_perms_decision * dest,struct extended_perms_decision * src)278 static inline void avc_quick_copy_xperms_decision(u8 perm,
279 			struct extended_perms_decision *dest,
280 			struct extended_perms_decision *src)
281 {
282 	/*
283 	 * compute index of the u32 of the 256 bits (8 u32s) that contain this
284 	 * command permission
285 	 */
286 	u8 i = perm >> 5;
287 
288 	dest->used = src->used;
289 	if (dest->used & XPERMS_ALLOWED)
290 		dest->allowed->p[i] = src->allowed->p[i];
291 	if (dest->used & XPERMS_AUDITALLOW)
292 		dest->auditallow->p[i] = src->auditallow->p[i];
293 	if (dest->used & XPERMS_DONTAUDIT)
294 		dest->dontaudit->p[i] = src->dontaudit->p[i];
295 }
296 
297 static struct avc_xperms_decision_node
avc_xperms_decision_alloc(u8 which)298 		*avc_xperms_decision_alloc(u8 which)
299 {
300 	struct avc_xperms_decision_node *xpd_node;
301 	struct extended_perms_decision *xpd;
302 
303 	xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
304 				     GFP_NOWAIT | __GFP_NOWARN);
305 	if (!xpd_node)
306 		return NULL;
307 
308 	xpd = &xpd_node->xpd;
309 	if (which & XPERMS_ALLOWED) {
310 		xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
311 						GFP_NOWAIT | __GFP_NOWARN);
312 		if (!xpd->allowed)
313 			goto error;
314 	}
315 	if (which & XPERMS_AUDITALLOW) {
316 		xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
317 						GFP_NOWAIT | __GFP_NOWARN);
318 		if (!xpd->auditallow)
319 			goto error;
320 	}
321 	if (which & XPERMS_DONTAUDIT) {
322 		xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
323 						GFP_NOWAIT | __GFP_NOWARN);
324 		if (!xpd->dontaudit)
325 			goto error;
326 	}
327 	return xpd_node;
328 error:
329 	avc_xperms_decision_free(xpd_node);
330 	return NULL;
331 }
332 
avc_add_xperms_decision(struct avc_node * node,struct extended_perms_decision * src)333 static int avc_add_xperms_decision(struct avc_node *node,
334 			struct extended_perms_decision *src)
335 {
336 	struct avc_xperms_decision_node *dest_xpd;
337 
338 	node->ae.xp_node->xp.len++;
339 	dest_xpd = avc_xperms_decision_alloc(src->used);
340 	if (!dest_xpd)
341 		return -ENOMEM;
342 	avc_copy_xperms_decision(&dest_xpd->xpd, src);
343 	list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
344 	return 0;
345 }
346 
avc_xperms_alloc(void)347 static struct avc_xperms_node *avc_xperms_alloc(void)
348 {
349 	struct avc_xperms_node *xp_node;
350 
351 	xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT | __GFP_NOWARN);
352 	if (!xp_node)
353 		return xp_node;
354 	INIT_LIST_HEAD(&xp_node->xpd_head);
355 	return xp_node;
356 }
357 
avc_xperms_populate(struct avc_node * node,struct avc_xperms_node * src)358 static int avc_xperms_populate(struct avc_node *node,
359 				struct avc_xperms_node *src)
360 {
361 	struct avc_xperms_node *dest;
362 	struct avc_xperms_decision_node *dest_xpd;
363 	struct avc_xperms_decision_node *src_xpd;
364 
365 	if (src->xp.len == 0)
366 		return 0;
367 	dest = avc_xperms_alloc();
368 	if (!dest)
369 		return -ENOMEM;
370 
371 	memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
372 	dest->xp.len = src->xp.len;
373 
374 	/* for each source xpd allocate a destination xpd and copy */
375 	list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
376 		dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
377 		if (!dest_xpd)
378 			goto error;
379 		avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
380 		list_add(&dest_xpd->xpd_list, &dest->xpd_head);
381 	}
382 	node->ae.xp_node = dest;
383 	return 0;
384 error:
385 	avc_xperms_free(dest);
386 	return -ENOMEM;
387 
388 }
389 
avc_xperms_audit_required(u32 requested,struct av_decision * avd,struct extended_perms_decision * xpd,u8 perm,int result,u32 * deniedp)390 static inline u32 avc_xperms_audit_required(u32 requested,
391 					struct av_decision *avd,
392 					struct extended_perms_decision *xpd,
393 					u8 perm,
394 					int result,
395 					u32 *deniedp)
396 {
397 	u32 denied, audited;
398 
399 	denied = requested & ~avd->allowed;
400 	if (unlikely(denied)) {
401 		audited = denied & avd->auditdeny;
402 		if (audited && xpd) {
403 			if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
404 				audited &= ~requested;
405 		}
406 	} else if (result) {
407 		audited = denied = requested;
408 	} else {
409 		audited = requested & avd->auditallow;
410 		if (audited && xpd) {
411 			if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
412 				audited &= ~requested;
413 		}
414 	}
415 
416 	*deniedp = denied;
417 	return audited;
418 }
419 
avc_xperms_audit(struct selinux_state * state,u32 ssid,u32 tsid,u16 tclass,u32 requested,struct av_decision * avd,struct extended_perms_decision * xpd,u8 perm,int result,struct common_audit_data * ad)420 static inline int avc_xperms_audit(struct selinux_state *state,
421 				   u32 ssid, u32 tsid, u16 tclass,
422 				   u32 requested, struct av_decision *avd,
423 				   struct extended_perms_decision *xpd,
424 				   u8 perm, int result,
425 				   struct common_audit_data *ad)
426 {
427 	u32 audited, denied;
428 
429 	audited = avc_xperms_audit_required(
430 			requested, avd, xpd, perm, result, &denied);
431 	if (likely(!audited))
432 		return 0;
433 	return slow_avc_audit(state, ssid, tsid, tclass, requested,
434 			audited, denied, result, ad);
435 }
436 
avc_node_free(struct rcu_head * rhead)437 static void avc_node_free(struct rcu_head *rhead)
438 {
439 	struct avc_node *node = container_of(rhead, struct avc_node, rhead);
440 	avc_xperms_free(node->ae.xp_node);
441 	kmem_cache_free(avc_node_cachep, node);
442 	avc_cache_stats_incr(frees);
443 }
444 
avc_node_delete(struct selinux_avc * avc,struct avc_node * node)445 static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
446 {
447 	trace_android_rvh_selinux_avc_node_delete(node);
448 	hlist_del_rcu(&node->list);
449 	call_rcu(&node->rhead, avc_node_free);
450 	atomic_dec(&avc->avc_cache.active_nodes);
451 }
452 
avc_node_kill(struct selinux_avc * avc,struct avc_node * node)453 static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
454 {
455 	avc_xperms_free(node->ae.xp_node);
456 	kmem_cache_free(avc_node_cachep, node);
457 	avc_cache_stats_incr(frees);
458 	atomic_dec(&avc->avc_cache.active_nodes);
459 }
460 
avc_node_replace(struct selinux_avc * avc,struct avc_node * new,struct avc_node * old)461 static void avc_node_replace(struct selinux_avc *avc,
462 			     struct avc_node *new, struct avc_node *old)
463 {
464 	trace_android_rvh_selinux_avc_node_replace(old, new);
465 	hlist_replace_rcu(&old->list, &new->list);
466 	call_rcu(&old->rhead, avc_node_free);
467 	atomic_dec(&avc->avc_cache.active_nodes);
468 }
469 
avc_reclaim_node(struct selinux_avc * avc)470 static inline int avc_reclaim_node(struct selinux_avc *avc)
471 {
472 	struct avc_node *node;
473 	int hvalue, try, ecx;
474 	unsigned long flags;
475 	struct hlist_head *head;
476 	spinlock_t *lock;
477 
478 	for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
479 		hvalue = atomic_inc_return(&avc->avc_cache.lru_hint) &
480 			(AVC_CACHE_SLOTS - 1);
481 		head = &avc->avc_cache.slots[hvalue];
482 		lock = &avc->avc_cache.slots_lock[hvalue];
483 
484 		if (!spin_trylock_irqsave(lock, flags))
485 			continue;
486 
487 		rcu_read_lock();
488 		hlist_for_each_entry(node, head, list) {
489 			avc_node_delete(avc, node);
490 			avc_cache_stats_incr(reclaims);
491 			ecx++;
492 			if (ecx >= AVC_CACHE_RECLAIM) {
493 				rcu_read_unlock();
494 				spin_unlock_irqrestore(lock, flags);
495 				goto out;
496 			}
497 		}
498 		rcu_read_unlock();
499 		spin_unlock_irqrestore(lock, flags);
500 	}
501 out:
502 	return ecx;
503 }
504 
avc_alloc_node(struct selinux_avc * avc)505 static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
506 {
507 	struct avc_node *node;
508 
509 	node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN);
510 	if (!node)
511 		goto out;
512 
513 	INIT_HLIST_NODE(&node->list);
514 	avc_cache_stats_incr(allocations);
515 
516 	if (atomic_inc_return(&avc->avc_cache.active_nodes) >
517 	    avc->avc_cache_threshold)
518 		avc_reclaim_node(avc);
519 
520 out:
521 	return node;
522 }
523 
avc_node_populate(struct avc_node * node,u32 ssid,u32 tsid,u16 tclass,struct av_decision * avd)524 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
525 {
526 	node->ae.ssid = ssid;
527 	node->ae.tsid = tsid;
528 	node->ae.tclass = tclass;
529 	memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
530 }
531 
avc_search_node(struct selinux_avc * avc,u32 ssid,u32 tsid,u16 tclass)532 static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
533 					       u32 ssid, u32 tsid, u16 tclass)
534 {
535 	struct avc_node *node, *ret = NULL;
536 	int hvalue;
537 	struct hlist_head *head;
538 
539 	hvalue = avc_hash(ssid, tsid, tclass);
540 	head = &avc->avc_cache.slots[hvalue];
541 	hlist_for_each_entry_rcu(node, head, list) {
542 		if (ssid == node->ae.ssid &&
543 		    tclass == node->ae.tclass &&
544 		    tsid == node->ae.tsid) {
545 			ret = node;
546 			break;
547 		}
548 	}
549 
550 	return ret;
551 }
552 
553 /**
554  * avc_lookup - Look up an AVC entry.
555  * @avc: the access vector cache
556  * @ssid: source security identifier
557  * @tsid: target security identifier
558  * @tclass: target security class
559  *
560  * Look up an AVC entry that is valid for the
561  * (@ssid, @tsid), interpreting the permissions
562  * based on @tclass.  If a valid AVC entry exists,
563  * then this function returns the avc_node.
564  * Otherwise, this function returns NULL.
565  */
avc_lookup(struct selinux_avc * avc,u32 ssid,u32 tsid,u16 tclass)566 static struct avc_node *avc_lookup(struct selinux_avc *avc,
567 				   u32 ssid, u32 tsid, u16 tclass)
568 {
569 	struct avc_node *node;
570 
571 	avc_cache_stats_incr(lookups);
572 	node = avc_search_node(avc, ssid, tsid, tclass);
573 
574 	if (node) {
575 		trace_android_rvh_selinux_avc_lookup(node, ssid, tsid, tclass);
576 		return node;
577 	}
578 
579 	avc_cache_stats_incr(misses);
580 	return NULL;
581 }
582 
avc_latest_notif_update(struct selinux_avc * avc,int seqno,int is_insert)583 static int avc_latest_notif_update(struct selinux_avc *avc,
584 				   int seqno, int is_insert)
585 {
586 	int ret = 0;
587 	static DEFINE_SPINLOCK(notif_lock);
588 	unsigned long flag;
589 
590 	spin_lock_irqsave(&notif_lock, flag);
591 	if (is_insert) {
592 		if (seqno < avc->avc_cache.latest_notif) {
593 			pr_warn("SELinux: avc:  seqno %d < latest_notif %d\n",
594 			       seqno, avc->avc_cache.latest_notif);
595 			ret = -EAGAIN;
596 		}
597 	} else {
598 		if (seqno > avc->avc_cache.latest_notif)
599 			avc->avc_cache.latest_notif = seqno;
600 	}
601 	spin_unlock_irqrestore(&notif_lock, flag);
602 
603 	return ret;
604 }
605 
606 /**
607  * avc_insert - Insert an AVC entry.
608  * @avc: the access vector cache
609  * @ssid: source security identifier
610  * @tsid: target security identifier
611  * @tclass: target security class
612  * @avd: resulting av decision
613  * @xp_node: resulting extended permissions
614  *
615  * Insert an AVC entry for the SID pair
616  * (@ssid, @tsid) and class @tclass.
617  * The access vectors and the sequence number are
618  * normally provided by the security server in
619  * response to a security_compute_av() call.  If the
620  * sequence number @avd->seqno is not less than the latest
621  * revocation notification, then the function copies
622  * the access vectors into a cache entry, returns
623  * avc_node inserted. Otherwise, this function returns NULL.
624  */
avc_insert(struct selinux_avc * avc,u32 ssid,u32 tsid,u16 tclass,struct av_decision * avd,struct avc_xperms_node * xp_node)625 static struct avc_node *avc_insert(struct selinux_avc *avc,
626 				   u32 ssid, u32 tsid, u16 tclass,
627 				   struct av_decision *avd,
628 				   struct avc_xperms_node *xp_node)
629 {
630 	struct avc_node *pos, *node = NULL;
631 	int hvalue;
632 	unsigned long flag;
633 	spinlock_t *lock;
634 	struct hlist_head *head;
635 
636 	if (avc_latest_notif_update(avc, avd->seqno, 1))
637 		return NULL;
638 
639 	node = avc_alloc_node(avc);
640 	if (!node)
641 		return NULL;
642 
643 	avc_node_populate(node, ssid, tsid, tclass, avd);
644 	if (avc_xperms_populate(node, xp_node)) {
645 		avc_node_kill(avc, node);
646 		return NULL;
647 	}
648 
649 	hvalue = avc_hash(ssid, tsid, tclass);
650 	head = &avc->avc_cache.slots[hvalue];
651 	lock = &avc->avc_cache.slots_lock[hvalue];
652 	spin_lock_irqsave(lock, flag);
653 	hlist_for_each_entry(pos, head, list) {
654 		if (pos->ae.ssid == ssid &&
655 			pos->ae.tsid == tsid &&
656 			pos->ae.tclass == tclass) {
657 			avc_node_replace(avc, node, pos);
658 			goto found;
659 		}
660 	}
661 	hlist_add_head_rcu(&node->list, head);
662 	trace_android_rvh_selinux_avc_insert(node);
663 found:
664 	spin_unlock_irqrestore(lock, flag);
665 	return node;
666 }
667 
668 /**
669  * avc_audit_pre_callback - SELinux specific information
670  * will be called by generic audit code
671  * @ab: the audit buffer
672  * @a: audit_data
673  */
avc_audit_pre_callback(struct audit_buffer * ab,void * a)674 static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
675 {
676 	struct common_audit_data *ad = a;
677 	struct selinux_audit_data *sad = ad->selinux_audit_data;
678 	u32 av = sad->audited;
679 	const char *const *perms;
680 	int i, perm;
681 
682 	audit_log_format(ab, "avc:  %s ", sad->denied ? "denied" : "granted");
683 
684 	if (av == 0) {
685 		audit_log_format(ab, " null");
686 		return;
687 	}
688 
689 	perms = secclass_map[sad->tclass-1].perms;
690 
691 	audit_log_format(ab, " {");
692 	i = 0;
693 	perm = 1;
694 	while (i < (sizeof(av) * 8)) {
695 		if ((perm & av) && perms[i]) {
696 			audit_log_format(ab, " %s", perms[i]);
697 			av &= ~perm;
698 		}
699 		i++;
700 		perm <<= 1;
701 	}
702 
703 	if (av)
704 		audit_log_format(ab, " 0x%x", av);
705 
706 	audit_log_format(ab, " } for ");
707 }
708 
709 /**
710  * avc_audit_post_callback - SELinux specific information
711  * will be called by generic audit code
712  * @ab: the audit buffer
713  * @a: audit_data
714  */
avc_audit_post_callback(struct audit_buffer * ab,void * a)715 static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
716 {
717 	struct common_audit_data *ad = a;
718 	struct selinux_audit_data *sad = ad->selinux_audit_data;
719 	char *scontext = NULL;
720 	char *tcontext = NULL;
721 	const char *tclass = NULL;
722 	u32 scontext_len;
723 	u32 tcontext_len;
724 	int rc;
725 
726 	rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
727 				     &scontext_len);
728 	if (rc)
729 		audit_log_format(ab, " ssid=%d", sad->ssid);
730 	else
731 		audit_log_format(ab, " scontext=%s", scontext);
732 
733 	rc = security_sid_to_context(sad->state, sad->tsid, &tcontext,
734 				     &tcontext_len);
735 	if (rc)
736 		audit_log_format(ab, " tsid=%d", sad->tsid);
737 	else
738 		audit_log_format(ab, " tcontext=%s", tcontext);
739 
740 	tclass = secclass_map[sad->tclass-1].name;
741 	audit_log_format(ab, " tclass=%s", tclass);
742 
743 	if (sad->denied)
744 		audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
745 
746 	trace_selinux_audited(sad, scontext, tcontext, tclass);
747 	kfree(tcontext);
748 	kfree(scontext);
749 
750 	/* in case of invalid context report also the actual context string */
751 	rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
752 					   &scontext_len);
753 	if (!rc && scontext) {
754 		if (scontext_len && scontext[scontext_len - 1] == '\0')
755 			scontext_len--;
756 		audit_log_format(ab, " srawcon=");
757 		audit_log_n_untrustedstring(ab, scontext, scontext_len);
758 		kfree(scontext);
759 	}
760 
761 	rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
762 					   &scontext_len);
763 	if (!rc && scontext) {
764 		if (scontext_len && scontext[scontext_len - 1] == '\0')
765 			scontext_len--;
766 		audit_log_format(ab, " trawcon=");
767 		audit_log_n_untrustedstring(ab, scontext, scontext_len);
768 		kfree(scontext);
769 	}
770 }
771 
772 /*
773  * This is the slow part of avc audit with big stack footprint.
774  * Note that it is non-blocking and can be called from under
775  * rcu_read_lock().
776  */
slow_avc_audit(struct selinux_state * state,u32 ssid,u32 tsid,u16 tclass,u32 requested,u32 audited,u32 denied,int result,struct common_audit_data * a)777 noinline int slow_avc_audit(struct selinux_state *state,
778 			    u32 ssid, u32 tsid, u16 tclass,
779 			    u32 requested, u32 audited, u32 denied, int result,
780 			    struct common_audit_data *a)
781 {
782 	struct common_audit_data stack_data;
783 	struct selinux_audit_data sad;
784 
785 	if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
786 		return -EINVAL;
787 
788 	if (!a) {
789 		a = &stack_data;
790 		a->type = LSM_AUDIT_DATA_NONE;
791 	}
792 
793 	sad.tclass = tclass;
794 	sad.requested = requested;
795 	sad.ssid = ssid;
796 	sad.tsid = tsid;
797 	sad.audited = audited;
798 	sad.denied = denied;
799 	sad.result = result;
800 	sad.state = state;
801 
802 	a->selinux_audit_data = &sad;
803 
804 	common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
805 	return 0;
806 }
807 
808 /**
809  * avc_add_callback - Register a callback for security events.
810  * @callback: callback function
811  * @events: security events
812  *
813  * Register a callback function for events in the set @events.
814  * Returns %0 on success or -%ENOMEM if insufficient memory
815  * exists to add the callback.
816  */
avc_add_callback(int (* callback)(u32 event),u32 events)817 int __init avc_add_callback(int (*callback)(u32 event), u32 events)
818 {
819 	struct avc_callback_node *c;
820 	int rc = 0;
821 
822 	c = kmalloc(sizeof(*c), GFP_KERNEL);
823 	if (!c) {
824 		rc = -ENOMEM;
825 		goto out;
826 	}
827 
828 	c->callback = callback;
829 	c->events = events;
830 	c->next = avc_callbacks;
831 	avc_callbacks = c;
832 out:
833 	return rc;
834 }
835 
836 /**
837  * avc_update_node - Update an AVC entry
838  * @avc: the access vector cache
839  * @event : Updating event
840  * @perms : Permission mask bits
841  * @driver: xperm driver information
842  * @xperm: xperm permissions
843  * @ssid: AVC entry source sid
844  * @tsid: AVC entry target sid
845  * @tclass : AVC entry target object class
846  * @seqno : sequence number when decision was made
847  * @xpd: extended_perms_decision to be added to the node
848  * @flags: the AVC_* flags, e.g. AVC_EXTENDED_PERMS, or 0.
849  *
850  * if a valid AVC entry doesn't exist,this function returns -ENOENT.
851  * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
852  * otherwise, this function updates the AVC entry. The original AVC-entry object
853  * will release later by RCU.
854  */
avc_update_node(struct selinux_avc * avc,u32 event,u32 perms,u8 driver,u8 xperm,u32 ssid,u32 tsid,u16 tclass,u32 seqno,struct extended_perms_decision * xpd,u32 flags)855 static int avc_update_node(struct selinux_avc *avc,
856 			   u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
857 			   u32 tsid, u16 tclass, u32 seqno,
858 			   struct extended_perms_decision *xpd,
859 			   u32 flags)
860 {
861 	int hvalue, rc = 0;
862 	unsigned long flag;
863 	struct avc_node *pos, *node, *orig = NULL;
864 	struct hlist_head *head;
865 	spinlock_t *lock;
866 
867 	node = avc_alloc_node(avc);
868 	if (!node) {
869 		rc = -ENOMEM;
870 		goto out;
871 	}
872 
873 	/* Lock the target slot */
874 	hvalue = avc_hash(ssid, tsid, tclass);
875 
876 	head = &avc->avc_cache.slots[hvalue];
877 	lock = &avc->avc_cache.slots_lock[hvalue];
878 
879 	spin_lock_irqsave(lock, flag);
880 
881 	hlist_for_each_entry(pos, head, list) {
882 		if (ssid == pos->ae.ssid &&
883 		    tsid == pos->ae.tsid &&
884 		    tclass == pos->ae.tclass &&
885 		    seqno == pos->ae.avd.seqno){
886 			orig = pos;
887 			break;
888 		}
889 	}
890 
891 	if (!orig) {
892 		rc = -ENOENT;
893 		avc_node_kill(avc, node);
894 		goto out_unlock;
895 	}
896 
897 	/*
898 	 * Copy and replace original node.
899 	 */
900 
901 	avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
902 
903 	if (orig->ae.xp_node) {
904 		rc = avc_xperms_populate(node, orig->ae.xp_node);
905 		if (rc) {
906 			avc_node_kill(avc, node);
907 			goto out_unlock;
908 		}
909 	}
910 
911 	switch (event) {
912 	case AVC_CALLBACK_GRANT:
913 		node->ae.avd.allowed |= perms;
914 		if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
915 			avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
916 		break;
917 	case AVC_CALLBACK_TRY_REVOKE:
918 	case AVC_CALLBACK_REVOKE:
919 		node->ae.avd.allowed &= ~perms;
920 		break;
921 	case AVC_CALLBACK_AUDITALLOW_ENABLE:
922 		node->ae.avd.auditallow |= perms;
923 		break;
924 	case AVC_CALLBACK_AUDITALLOW_DISABLE:
925 		node->ae.avd.auditallow &= ~perms;
926 		break;
927 	case AVC_CALLBACK_AUDITDENY_ENABLE:
928 		node->ae.avd.auditdeny |= perms;
929 		break;
930 	case AVC_CALLBACK_AUDITDENY_DISABLE:
931 		node->ae.avd.auditdeny &= ~perms;
932 		break;
933 	case AVC_CALLBACK_ADD_XPERMS:
934 		avc_add_xperms_decision(node, xpd);
935 		break;
936 	}
937 	avc_node_replace(avc, node, orig);
938 out_unlock:
939 	spin_unlock_irqrestore(lock, flag);
940 out:
941 	return rc;
942 }
943 
944 /**
945  * avc_flush - Flush the cache
946  * @avc: the access vector cache
947  */
avc_flush(struct selinux_avc * avc)948 static void avc_flush(struct selinux_avc *avc)
949 {
950 	struct hlist_head *head;
951 	struct avc_node *node;
952 	spinlock_t *lock;
953 	unsigned long flag;
954 	int i;
955 
956 	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
957 		head = &avc->avc_cache.slots[i];
958 		lock = &avc->avc_cache.slots_lock[i];
959 
960 		spin_lock_irqsave(lock, flag);
961 		/*
962 		 * With preemptable RCU, the outer spinlock does not
963 		 * prevent RCU grace periods from ending.
964 		 */
965 		rcu_read_lock();
966 		hlist_for_each_entry(node, head, list)
967 			avc_node_delete(avc, node);
968 		rcu_read_unlock();
969 		spin_unlock_irqrestore(lock, flag);
970 	}
971 }
972 
973 /**
974  * avc_ss_reset - Flush the cache and revalidate migrated permissions.
975  * @avc: the access vector cache
976  * @seqno: policy sequence number
977  */
avc_ss_reset(struct selinux_avc * avc,u32 seqno)978 int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
979 {
980 	struct avc_callback_node *c;
981 	int rc = 0, tmprc;
982 
983 	avc_flush(avc);
984 
985 	for (c = avc_callbacks; c; c = c->next) {
986 		if (c->events & AVC_CALLBACK_RESET) {
987 			tmprc = c->callback(AVC_CALLBACK_RESET);
988 			/* save the first error encountered for the return
989 			   value and continue processing the callbacks */
990 			if (!rc)
991 				rc = tmprc;
992 		}
993 	}
994 
995 	avc_latest_notif_update(avc, seqno, 0);
996 	return rc;
997 }
998 
999 /*
1000  * Slow-path helper function for avc_has_perm_noaudit,
1001  * when the avc_node lookup fails. We get called with
1002  * the RCU read lock held, and need to return with it
1003  * still held, but drop if for the security compute.
1004  *
1005  * Don't inline this, since it's the slow-path and just
1006  * results in a bigger stack frame.
1007  */
1008 static noinline
avc_compute_av(struct selinux_state * state,u32 ssid,u32 tsid,u16 tclass,struct av_decision * avd,struct avc_xperms_node * xp_node)1009 struct avc_node *avc_compute_av(struct selinux_state *state,
1010 				u32 ssid, u32 tsid,
1011 				u16 tclass, struct av_decision *avd,
1012 				struct avc_xperms_node *xp_node)
1013 {
1014 	rcu_read_unlock();
1015 	INIT_LIST_HEAD(&xp_node->xpd_head);
1016 	security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
1017 	rcu_read_lock();
1018 	return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
1019 }
1020 
avc_denied(struct selinux_state * state,u32 ssid,u32 tsid,u16 tclass,u32 requested,u8 driver,u8 xperm,unsigned int flags,struct av_decision * avd)1021 static noinline int avc_denied(struct selinux_state *state,
1022 			       u32 ssid, u32 tsid,
1023 			       u16 tclass, u32 requested,
1024 			       u8 driver, u8 xperm, unsigned int flags,
1025 			       struct av_decision *avd)
1026 {
1027 	if (flags & AVC_STRICT)
1028 		return -EACCES;
1029 
1030 	if (enforcing_enabled(state) &&
1031 	    !(avd->flags & AVD_FLAGS_PERMISSIVE))
1032 		return -EACCES;
1033 
1034 	avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
1035 			xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1036 	return 0;
1037 }
1038 
1039 /*
1040  * The avc extended permissions logic adds an additional 256 bits of
1041  * permissions to an avc node when extended permissions for that node are
1042  * specified in the avtab. If the additional 256 permissions is not adequate,
1043  * as-is the case with ioctls, then multiple may be chained together and the
1044  * driver field is used to specify which set contains the permission.
1045  */
avc_has_extended_perms(struct selinux_state * state,u32 ssid,u32 tsid,u16 tclass,u32 requested,u8 driver,u8 xperm,struct common_audit_data * ad)1046 int avc_has_extended_perms(struct selinux_state *state,
1047 			   u32 ssid, u32 tsid, u16 tclass, u32 requested,
1048 			   u8 driver, u8 xperm, struct common_audit_data *ad)
1049 {
1050 	struct avc_node *node;
1051 	struct av_decision avd;
1052 	u32 denied;
1053 	struct extended_perms_decision local_xpd;
1054 	struct extended_perms_decision *xpd = NULL;
1055 	struct extended_perms_data allowed;
1056 	struct extended_perms_data auditallow;
1057 	struct extended_perms_data dontaudit;
1058 	struct avc_xperms_node local_xp_node;
1059 	struct avc_xperms_node *xp_node;
1060 	int rc = 0, rc2;
1061 
1062 	xp_node = &local_xp_node;
1063 	if (WARN_ON(!requested))
1064 		return -EACCES;
1065 
1066 	rcu_read_lock();
1067 
1068 	node = avc_lookup(state->avc, ssid, tsid, tclass);
1069 	if (unlikely(!node)) {
1070 		avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
1071 	} else {
1072 		memcpy(&avd, &node->ae.avd, sizeof(avd));
1073 		xp_node = node->ae.xp_node;
1074 	}
1075 	/* if extended permissions are not defined, only consider av_decision */
1076 	if (!xp_node || !xp_node->xp.len)
1077 		goto decision;
1078 
1079 	local_xpd.allowed = &allowed;
1080 	local_xpd.auditallow = &auditallow;
1081 	local_xpd.dontaudit = &dontaudit;
1082 
1083 	xpd = avc_xperms_decision_lookup(driver, xp_node);
1084 	if (unlikely(!xpd)) {
1085 		/*
1086 		 * Compute the extended_perms_decision only if the driver
1087 		 * is flagged
1088 		 */
1089 		if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1090 			avd.allowed &= ~requested;
1091 			goto decision;
1092 		}
1093 		rcu_read_unlock();
1094 		security_compute_xperms_decision(state, ssid, tsid, tclass,
1095 						 driver, &local_xpd);
1096 		rcu_read_lock();
1097 		avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
1098 				driver, xperm, ssid, tsid, tclass, avd.seqno,
1099 				&local_xpd, 0);
1100 	} else {
1101 		avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1102 	}
1103 	xpd = &local_xpd;
1104 
1105 	if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1106 		avd.allowed &= ~requested;
1107 
1108 decision:
1109 	denied = requested & ~(avd.allowed);
1110 	if (unlikely(denied))
1111 		rc = avc_denied(state, ssid, tsid, tclass, requested,
1112 				driver, xperm, AVC_EXTENDED_PERMS, &avd);
1113 
1114 	rcu_read_unlock();
1115 
1116 	rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
1117 			&avd, xpd, xperm, rc, ad);
1118 	if (rc2)
1119 		return rc2;
1120 	return rc;
1121 }
1122 
1123 /**
1124  * avc_has_perm_noaudit - Check permissions but perform no auditing.
1125  * @state: SELinux state
1126  * @ssid: source security identifier
1127  * @tsid: target security identifier
1128  * @tclass: target security class
1129  * @requested: requested permissions, interpreted based on @tclass
1130  * @flags:  AVC_STRICT or 0
1131  * @avd: access vector decisions
1132  *
1133  * Check the AVC to determine whether the @requested permissions are granted
1134  * for the SID pair (@ssid, @tsid), interpreting the permissions
1135  * based on @tclass, and call the security server on a cache miss to obtain
1136  * a new decision and add it to the cache.  Return a copy of the decisions
1137  * in @avd.  Return %0 if all @requested permissions are granted,
1138  * -%EACCES if any permissions are denied, or another -errno upon
1139  * other errors.  This function is typically called by avc_has_perm(),
1140  * but may also be called directly to separate permission checking from
1141  * auditing, e.g. in cases where a lock must be held for the check but
1142  * should be released for the auditing.
1143  */
avc_has_perm_noaudit(struct selinux_state * state,u32 ssid,u32 tsid,u16 tclass,u32 requested,unsigned int flags,struct av_decision * avd)1144 inline int avc_has_perm_noaudit(struct selinux_state *state,
1145 				u32 ssid, u32 tsid,
1146 				u16 tclass, u32 requested,
1147 				unsigned int flags,
1148 				struct av_decision *avd)
1149 {
1150 	struct avc_node *node;
1151 	struct avc_xperms_node xp_node;
1152 	int rc = 0;
1153 	u32 denied;
1154 
1155 	if (WARN_ON(!requested))
1156 		return -EACCES;
1157 
1158 	rcu_read_lock();
1159 
1160 	node = avc_lookup(state->avc, ssid, tsid, tclass);
1161 	if (unlikely(!node))
1162 		avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
1163 	else
1164 		memcpy(avd, &node->ae.avd, sizeof(*avd));
1165 
1166 	denied = requested & ~(avd->allowed);
1167 	if (unlikely(denied))
1168 		rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
1169 				flags, avd);
1170 
1171 	rcu_read_unlock();
1172 	return rc;
1173 }
1174 
1175 /**
1176  * avc_has_perm - Check permissions and perform any appropriate auditing.
1177  * @state: SELinux state
1178  * @ssid: source security identifier
1179  * @tsid: target security identifier
1180  * @tclass: target security class
1181  * @requested: requested permissions, interpreted based on @tclass
1182  * @auditdata: auxiliary audit data
1183  *
1184  * Check the AVC to determine whether the @requested permissions are granted
1185  * for the SID pair (@ssid, @tsid), interpreting the permissions
1186  * based on @tclass, and call the security server on a cache miss to obtain
1187  * a new decision and add it to the cache.  Audit the granting or denial of
1188  * permissions in accordance with the policy.  Return %0 if all @requested
1189  * permissions are granted, -%EACCES if any permissions are denied, or
1190  * another -errno upon other errors.
1191  */
avc_has_perm(struct selinux_state * state,u32 ssid,u32 tsid,u16 tclass,u32 requested,struct common_audit_data * auditdata)1192 int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
1193 		 u32 requested, struct common_audit_data *auditdata)
1194 {
1195 	struct av_decision avd;
1196 	int rc, rc2;
1197 
1198 	rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1199 				  &avd);
1200 
1201 	rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1202 			auditdata);
1203 	if (rc2)
1204 		return rc2;
1205 	return rc;
1206 }
1207 
avc_policy_seqno(struct selinux_state * state)1208 u32 avc_policy_seqno(struct selinux_state *state)
1209 {
1210 	return state->avc->avc_cache.latest_notif;
1211 }
1212 
avc_disable(void)1213 void avc_disable(void)
1214 {
1215 	/*
1216 	 * If you are looking at this because you have realized that we are
1217 	 * not destroying the avc_node_cachep it might be easy to fix, but
1218 	 * I don't know the memory barrier semantics well enough to know.  It's
1219 	 * possible that some other task dereferenced security_ops when
1220 	 * it still pointed to selinux operations.  If that is the case it's
1221 	 * possible that it is about to use the avc and is about to need the
1222 	 * avc_node_cachep.  I know I could wrap the security.c security_ops call
1223 	 * in an rcu_lock, but seriously, it's not worth it.  Instead I just flush
1224 	 * the cache and get that memory back.
1225 	 */
1226 	if (avc_node_cachep) {
1227 		avc_flush(selinux_state.avc);
1228 		/* kmem_cache_destroy(avc_node_cachep); */
1229 	}
1230 }
1231