1 // SPDX-License-Identifier: GPL-2.0-only
3 * Implementation of the kernel access vector cache (AVC).
5 * Authors: Stephen Smalley, <sds@tycho.nsa.gov>
6 * James Morris <jmorris@redhat.com>
8 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
9 * Replaced the avc_lock spinlock by RCU.
11 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
13 #include <linux/types.h>
14 #include <linux/stddef.h>
15 #include <linux/kernel.h>
16 #include <linux/slab.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>
25 #include <net/af_unix.h>
27 #include <linux/audit.h>
28 #include <linux/ipv6.h>
34 #define AVC_CACHE_SLOTS 512
35 #define AVC_DEF_CACHE_THRESHOLD 512
36 #define AVC_CACHE_RECLAIM 16
38 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
39 #define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
41 #define avc_cache_stats_incr(field) do {} while (0)
48 struct av_decision avd;
49 struct avc_xperms_node *xp_node;
54 struct hlist_node list; /* anchored in avc_cache->slots[i] */
55 struct rcu_head rhead;
58 struct avc_xperms_decision_node {
59 struct extended_perms_decision xpd;
60 struct list_head xpd_list; /* list of extended_perms_decision */
63 struct avc_xperms_node {
64 struct extended_perms xp;
65 struct list_head xpd_head; /* list head of extended_perms_decision */
69 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
70 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
71 atomic_t lru_hint; /* LRU hint for reclaim scan */
72 atomic_t active_nodes;
73 u32 latest_notif; /* latest revocation notification */
76 struct avc_callback_node {
77 int (*callback) (u32 event);
79 struct avc_callback_node *next;
82 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
83 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
87 unsigned int avc_cache_threshold;
88 struct avc_cache avc_cache;
91 static struct selinux_avc selinux_avc;
93 void selinux_avc_init(struct selinux_avc **avc)
97 selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
98 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
99 INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
100 spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
102 atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
103 atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
107 unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
109 return avc->avc_cache_threshold;
112 void avc_set_cache_threshold(struct selinux_avc *avc,
113 unsigned int cache_threshold)
115 avc->avc_cache_threshold = cache_threshold;
118 static struct avc_callback_node *avc_callbacks;
119 static struct kmem_cache *avc_node_cachep;
120 static struct kmem_cache *avc_xperms_data_cachep;
121 static struct kmem_cache *avc_xperms_decision_cachep;
122 static struct kmem_cache *avc_xperms_cachep;
124 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
126 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
130 * avc_init - Initialize the AVC.
132 * Initialize the access vector cache.
134 void __init avc_init(void)
136 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
137 0, SLAB_PANIC, NULL);
138 avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
139 sizeof(struct avc_xperms_node),
140 0, SLAB_PANIC, NULL);
141 avc_xperms_decision_cachep = kmem_cache_create(
142 "avc_xperms_decision_node",
143 sizeof(struct avc_xperms_decision_node),
144 0, SLAB_PANIC, NULL);
145 avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
146 sizeof(struct extended_perms_data),
147 0, SLAB_PANIC, NULL);
150 int avc_get_hash_stats(struct selinux_avc *avc, char *page)
152 int i, chain_len, max_chain_len, slots_used;
153 struct avc_node *node;
154 struct hlist_head *head;
160 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
161 head = &avc->avc_cache.slots[i];
162 if (!hlist_empty(head)) {
165 hlist_for_each_entry_rcu(node, head, list)
167 if (chain_len > max_chain_len)
168 max_chain_len = chain_len;
174 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
175 "longest chain: %d\n",
176 atomic_read(&avc->avc_cache.active_nodes),
177 slots_used, AVC_CACHE_SLOTS, max_chain_len);
181 * using a linked list for extended_perms_decision lookup because the list is
182 * always small. i.e. less than 5, typically 1
184 static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
185 struct avc_xperms_node *xp_node)
187 struct avc_xperms_decision_node *xpd_node;
189 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
190 if (xpd_node->xpd.driver == driver)
191 return &xpd_node->xpd;
196 static inline unsigned int
197 avc_xperms_has_perm(struct extended_perms_decision *xpd,
202 if ((which == XPERMS_ALLOWED) &&
203 (xpd->used & XPERMS_ALLOWED))
204 rc = security_xperm_test(xpd->allowed->p, perm);
205 else if ((which == XPERMS_AUDITALLOW) &&
206 (xpd->used & XPERMS_AUDITALLOW))
207 rc = security_xperm_test(xpd->auditallow->p, perm);
208 else if ((which == XPERMS_DONTAUDIT) &&
209 (xpd->used & XPERMS_DONTAUDIT))
210 rc = security_xperm_test(xpd->dontaudit->p, perm);
214 static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
217 struct extended_perms_decision *xpd;
218 security_xperm_set(xp_node->xp.drivers.p, driver);
219 xpd = avc_xperms_decision_lookup(driver, xp_node);
220 if (xpd && xpd->allowed)
221 security_xperm_set(xpd->allowed->p, perm);
224 static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
226 struct extended_perms_decision *xpd;
228 xpd = &xpd_node->xpd;
230 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
232 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
234 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
235 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
238 static void avc_xperms_free(struct avc_xperms_node *xp_node)
240 struct avc_xperms_decision_node *xpd_node, *tmp;
245 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
246 list_del(&xpd_node->xpd_list);
247 avc_xperms_decision_free(xpd_node);
249 kmem_cache_free(avc_xperms_cachep, xp_node);
252 static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
253 struct extended_perms_decision *src)
255 dest->driver = src->driver;
256 dest->used = src->used;
257 if (dest->used & XPERMS_ALLOWED)
258 memcpy(dest->allowed->p, src->allowed->p,
259 sizeof(src->allowed->p));
260 if (dest->used & XPERMS_AUDITALLOW)
261 memcpy(dest->auditallow->p, src->auditallow->p,
262 sizeof(src->auditallow->p));
263 if (dest->used & XPERMS_DONTAUDIT)
264 memcpy(dest->dontaudit->p, src->dontaudit->p,
265 sizeof(src->dontaudit->p));
269 * similar to avc_copy_xperms_decision, but only copy decision
270 * information relevant to this perm
272 static inline void avc_quick_copy_xperms_decision(u8 perm,
273 struct extended_perms_decision *dest,
274 struct extended_perms_decision *src)
277 * compute index of the u32 of the 256 bits (8 u32s) that contain this
282 dest->used = src->used;
283 if (dest->used & XPERMS_ALLOWED)
284 dest->allowed->p[i] = src->allowed->p[i];
285 if (dest->used & XPERMS_AUDITALLOW)
286 dest->auditallow->p[i] = src->auditallow->p[i];
287 if (dest->used & XPERMS_DONTAUDIT)
288 dest->dontaudit->p[i] = src->dontaudit->p[i];
291 static struct avc_xperms_decision_node
292 *avc_xperms_decision_alloc(u8 which)
294 struct avc_xperms_decision_node *xpd_node;
295 struct extended_perms_decision *xpd;
297 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
298 GFP_NOWAIT | __GFP_NOWARN);
302 xpd = &xpd_node->xpd;
303 if (which & XPERMS_ALLOWED) {
304 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
305 GFP_NOWAIT | __GFP_NOWARN);
309 if (which & XPERMS_AUDITALLOW) {
310 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
311 GFP_NOWAIT | __GFP_NOWARN);
312 if (!xpd->auditallow)
315 if (which & XPERMS_DONTAUDIT) {
316 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
317 GFP_NOWAIT | __GFP_NOWARN);
323 avc_xperms_decision_free(xpd_node);
327 static int avc_add_xperms_decision(struct avc_node *node,
328 struct extended_perms_decision *src)
330 struct avc_xperms_decision_node *dest_xpd;
332 node->ae.xp_node->xp.len++;
333 dest_xpd = avc_xperms_decision_alloc(src->used);
336 avc_copy_xperms_decision(&dest_xpd->xpd, src);
337 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
341 static struct avc_xperms_node *avc_xperms_alloc(void)
343 struct avc_xperms_node *xp_node;
345 xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT | __GFP_NOWARN);
348 INIT_LIST_HEAD(&xp_node->xpd_head);
352 static int avc_xperms_populate(struct avc_node *node,
353 struct avc_xperms_node *src)
355 struct avc_xperms_node *dest;
356 struct avc_xperms_decision_node *dest_xpd;
357 struct avc_xperms_decision_node *src_xpd;
359 if (src->xp.len == 0)
361 dest = avc_xperms_alloc();
365 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
366 dest->xp.len = src->xp.len;
368 /* for each source xpd allocate a destination xpd and copy */
369 list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
370 dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
373 avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
374 list_add(&dest_xpd->xpd_list, &dest->xpd_head);
376 node->ae.xp_node = dest;
379 avc_xperms_free(dest);
384 static inline u32 avc_xperms_audit_required(u32 requested,
385 struct av_decision *avd,
386 struct extended_perms_decision *xpd,
393 denied = requested & ~avd->allowed;
394 if (unlikely(denied)) {
395 audited = denied & avd->auditdeny;
396 if (audited && xpd) {
397 if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
398 audited &= ~requested;
401 audited = denied = requested;
403 audited = requested & avd->auditallow;
404 if (audited && xpd) {
405 if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
406 audited &= ~requested;
414 static inline int avc_xperms_audit(struct selinux_state *state,
415 u32 ssid, u32 tsid, u16 tclass,
416 u32 requested, struct av_decision *avd,
417 struct extended_perms_decision *xpd,
419 struct common_audit_data *ad)
423 audited = avc_xperms_audit_required(
424 requested, avd, xpd, perm, result, &denied);
425 if (likely(!audited))
427 return slow_avc_audit(state, ssid, tsid, tclass, requested,
428 audited, denied, result, ad);
431 static void avc_node_free(struct rcu_head *rhead)
433 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
434 avc_xperms_free(node->ae.xp_node);
435 kmem_cache_free(avc_node_cachep, node);
436 avc_cache_stats_incr(frees);
439 static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
441 hlist_del_rcu(&node->list);
442 call_rcu(&node->rhead, avc_node_free);
443 atomic_dec(&avc->avc_cache.active_nodes);
446 static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
448 avc_xperms_free(node->ae.xp_node);
449 kmem_cache_free(avc_node_cachep, node);
450 avc_cache_stats_incr(frees);
451 atomic_dec(&avc->avc_cache.active_nodes);
454 static void avc_node_replace(struct selinux_avc *avc,
455 struct avc_node *new, struct avc_node *old)
457 hlist_replace_rcu(&old->list, &new->list);
458 call_rcu(&old->rhead, avc_node_free);
459 atomic_dec(&avc->avc_cache.active_nodes);
462 static inline int avc_reclaim_node(struct selinux_avc *avc)
464 struct avc_node *node;
465 int hvalue, try, ecx;
467 struct hlist_head *head;
470 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
471 hvalue = atomic_inc_return(&avc->avc_cache.lru_hint) &
472 (AVC_CACHE_SLOTS - 1);
473 head = &avc->avc_cache.slots[hvalue];
474 lock = &avc->avc_cache.slots_lock[hvalue];
476 if (!spin_trylock_irqsave(lock, flags))
480 hlist_for_each_entry(node, head, list) {
481 avc_node_delete(avc, node);
482 avc_cache_stats_incr(reclaims);
484 if (ecx >= AVC_CACHE_RECLAIM) {
486 spin_unlock_irqrestore(lock, flags);
491 spin_unlock_irqrestore(lock, flags);
497 static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
499 struct avc_node *node;
501 node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN);
505 INIT_HLIST_NODE(&node->list);
506 avc_cache_stats_incr(allocations);
508 if (atomic_inc_return(&avc->avc_cache.active_nodes) >
509 avc->avc_cache_threshold)
510 avc_reclaim_node(avc);
516 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
518 node->ae.ssid = ssid;
519 node->ae.tsid = tsid;
520 node->ae.tclass = tclass;
521 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
524 static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
525 u32 ssid, u32 tsid, u16 tclass)
527 struct avc_node *node, *ret = NULL;
529 struct hlist_head *head;
531 hvalue = avc_hash(ssid, tsid, tclass);
532 head = &avc->avc_cache.slots[hvalue];
533 hlist_for_each_entry_rcu(node, head, list) {
534 if (ssid == node->ae.ssid &&
535 tclass == node->ae.tclass &&
536 tsid == node->ae.tsid) {
546 * avc_lookup - Look up an AVC entry.
547 * @ssid: source security identifier
548 * @tsid: target security identifier
549 * @tclass: target security class
551 * Look up an AVC entry that is valid for the
552 * (@ssid, @tsid), interpreting the permissions
553 * based on @tclass. If a valid AVC entry exists,
554 * then this function returns the avc_node.
555 * Otherwise, this function returns NULL.
557 static struct avc_node *avc_lookup(struct selinux_avc *avc,
558 u32 ssid, u32 tsid, u16 tclass)
560 struct avc_node *node;
562 avc_cache_stats_incr(lookups);
563 node = avc_search_node(avc, ssid, tsid, tclass);
568 avc_cache_stats_incr(misses);
572 static int avc_latest_notif_update(struct selinux_avc *avc,
573 int seqno, int is_insert)
576 static DEFINE_SPINLOCK(notif_lock);
579 spin_lock_irqsave(¬if_lock, flag);
581 if (seqno < avc->avc_cache.latest_notif) {
582 pr_warn("SELinux: avc: seqno %d < latest_notif %d\n",
583 seqno, avc->avc_cache.latest_notif);
587 if (seqno > avc->avc_cache.latest_notif)
588 avc->avc_cache.latest_notif = seqno;
590 spin_unlock_irqrestore(¬if_lock, flag);
596 * avc_insert - Insert an AVC entry.
597 * @ssid: source security identifier
598 * @tsid: target security identifier
599 * @tclass: target security class
600 * @avd: resulting av decision
601 * @xp_node: resulting extended permissions
603 * Insert an AVC entry for the SID pair
604 * (@ssid, @tsid) and class @tclass.
605 * The access vectors and the sequence number are
606 * normally provided by the security server in
607 * response to a security_compute_av() call. If the
608 * sequence number @avd->seqno is not less than the latest
609 * revocation notification, then the function copies
610 * the access vectors into a cache entry, returns
611 * avc_node inserted. Otherwise, this function returns NULL.
613 static struct avc_node *avc_insert(struct selinux_avc *avc,
614 u32 ssid, u32 tsid, u16 tclass,
615 struct av_decision *avd,
616 struct avc_xperms_node *xp_node)
618 struct avc_node *pos, *node = NULL;
622 struct hlist_head *head;
624 if (avc_latest_notif_update(avc, avd->seqno, 1))
627 node = avc_alloc_node(avc);
631 avc_node_populate(node, ssid, tsid, tclass, avd);
632 if (avc_xperms_populate(node, xp_node)) {
633 avc_node_kill(avc, node);
637 hvalue = avc_hash(ssid, tsid, tclass);
638 head = &avc->avc_cache.slots[hvalue];
639 lock = &avc->avc_cache.slots_lock[hvalue];
640 spin_lock_irqsave(lock, flag);
641 hlist_for_each_entry(pos, head, list) {
642 if (pos->ae.ssid == ssid &&
643 pos->ae.tsid == tsid &&
644 pos->ae.tclass == tclass) {
645 avc_node_replace(avc, node, pos);
649 hlist_add_head_rcu(&node->list, head);
651 spin_unlock_irqrestore(lock, flag);
656 * avc_audit_pre_callback - SELinux specific information
657 * will be called by generic audit code
658 * @ab: the audit buffer
661 static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
663 struct common_audit_data *ad = a;
664 struct selinux_audit_data *sad = ad->selinux_audit_data;
665 u32 av = sad->audited;
669 audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
672 audit_log_format(ab, " null");
676 perms = secclass_map[sad->tclass-1].perms;
678 audit_log_format(ab, " {");
681 while (i < (sizeof(av) * 8)) {
682 if ((perm & av) && perms[i]) {
683 audit_log_format(ab, " %s", perms[i]);
691 audit_log_format(ab, " 0x%x", av);
693 audit_log_format(ab, " } for ");
697 * avc_audit_post_callback - SELinux specific information
698 * will be called by generic audit code
699 * @ab: the audit buffer
702 static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
704 struct common_audit_data *ad = a;
705 struct selinux_audit_data *sad = ad->selinux_audit_data;
710 rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
713 audit_log_format(ab, " ssid=%d", sad->ssid);
715 audit_log_format(ab, " scontext=%s", scontext);
719 rc = security_sid_to_context(sad->state, sad->tsid, &scontext,
722 audit_log_format(ab, " tsid=%d", sad->tsid);
724 audit_log_format(ab, " tcontext=%s", scontext);
728 audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name);
731 audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
733 /* in case of invalid context report also the actual context string */
734 rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
736 if (!rc && scontext) {
737 if (scontext_len && scontext[scontext_len - 1] == '\0')
739 audit_log_format(ab, " srawcon=");
740 audit_log_n_untrustedstring(ab, scontext, scontext_len);
744 rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
746 if (!rc && scontext) {
747 if (scontext_len && scontext[scontext_len - 1] == '\0')
749 audit_log_format(ab, " trawcon=");
750 audit_log_n_untrustedstring(ab, scontext, scontext_len);
755 /* This is the slow part of avc audit with big stack footprint */
756 noinline int slow_avc_audit(struct selinux_state *state,
757 u32 ssid, u32 tsid, u16 tclass,
758 u32 requested, u32 audited, u32 denied, int result,
759 struct common_audit_data *a)
761 struct common_audit_data stack_data;
762 struct selinux_audit_data sad;
764 if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
769 a->type = LSM_AUDIT_DATA_NONE;
773 sad.requested = requested;
776 sad.audited = audited;
781 a->selinux_audit_data = &sad;
783 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
788 * avc_add_callback - Register a callback for security events.
789 * @callback: callback function
790 * @events: security events
792 * Register a callback function for events in the set @events.
793 * Returns %0 on success or -%ENOMEM if insufficient memory
794 * exists to add the callback.
796 int __init avc_add_callback(int (*callback)(u32 event), u32 events)
798 struct avc_callback_node *c;
801 c = kmalloc(sizeof(*c), GFP_KERNEL);
807 c->callback = callback;
809 c->next = avc_callbacks;
816 * avc_update_node Update an AVC entry
817 * @event : Updating event
818 * @perms : Permission mask bits
819 * @ssid,@tsid,@tclass : identifier of an AVC entry
820 * @seqno : sequence number when decision was made
821 * @xpd: extended_perms_decision to be added to the node
822 * @flags: the AVC_* flags, e.g. AVC_NONBLOCKING, AVC_EXTENDED_PERMS, or 0.
824 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
825 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
826 * otherwise, this function updates the AVC entry. The original AVC-entry object
827 * will release later by RCU.
829 static int avc_update_node(struct selinux_avc *avc,
830 u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
831 u32 tsid, u16 tclass, u32 seqno,
832 struct extended_perms_decision *xpd,
837 struct avc_node *pos, *node, *orig = NULL;
838 struct hlist_head *head;
842 * If we are in a non-blocking code path, e.g. VFS RCU walk,
843 * then we must not add permissions to a cache entry
844 * because we will not audit the denial. Otherwise,
845 * during the subsequent blocking retry (e.g. VFS ref walk), we
846 * will find the permissions already granted in the cache entry
847 * and won't audit anything at all, leading to silent denials in
848 * permissive mode that only appear when in enforcing mode.
850 * See the corresponding handling of MAY_NOT_BLOCK in avc_audit()
851 * and selinux_inode_permission().
853 if (flags & AVC_NONBLOCKING)
856 node = avc_alloc_node(avc);
862 /* Lock the target slot */
863 hvalue = avc_hash(ssid, tsid, tclass);
865 head = &avc->avc_cache.slots[hvalue];
866 lock = &avc->avc_cache.slots_lock[hvalue];
868 spin_lock_irqsave(lock, flag);
870 hlist_for_each_entry(pos, head, list) {
871 if (ssid == pos->ae.ssid &&
872 tsid == pos->ae.tsid &&
873 tclass == pos->ae.tclass &&
874 seqno == pos->ae.avd.seqno){
882 avc_node_kill(avc, node);
887 * Copy and replace original node.
890 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
892 if (orig->ae.xp_node) {
893 rc = avc_xperms_populate(node, orig->ae.xp_node);
895 avc_node_kill(avc, node);
901 case AVC_CALLBACK_GRANT:
902 node->ae.avd.allowed |= perms;
903 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
904 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
906 case AVC_CALLBACK_TRY_REVOKE:
907 case AVC_CALLBACK_REVOKE:
908 node->ae.avd.allowed &= ~perms;
910 case AVC_CALLBACK_AUDITALLOW_ENABLE:
911 node->ae.avd.auditallow |= perms;
913 case AVC_CALLBACK_AUDITALLOW_DISABLE:
914 node->ae.avd.auditallow &= ~perms;
916 case AVC_CALLBACK_AUDITDENY_ENABLE:
917 node->ae.avd.auditdeny |= perms;
919 case AVC_CALLBACK_AUDITDENY_DISABLE:
920 node->ae.avd.auditdeny &= ~perms;
922 case AVC_CALLBACK_ADD_XPERMS:
923 avc_add_xperms_decision(node, xpd);
926 avc_node_replace(avc, node, orig);
928 spin_unlock_irqrestore(lock, flag);
934 * avc_flush - Flush the cache
936 static void avc_flush(struct selinux_avc *avc)
938 struct hlist_head *head;
939 struct avc_node *node;
944 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
945 head = &avc->avc_cache.slots[i];
946 lock = &avc->avc_cache.slots_lock[i];
948 spin_lock_irqsave(lock, flag);
950 * With preemptable RCU, the outer spinlock does not
951 * prevent RCU grace periods from ending.
954 hlist_for_each_entry(node, head, list)
955 avc_node_delete(avc, node);
957 spin_unlock_irqrestore(lock, flag);
962 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
963 * @seqno: policy sequence number
965 int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
967 struct avc_callback_node *c;
972 for (c = avc_callbacks; c; c = c->next) {
973 if (c->events & AVC_CALLBACK_RESET) {
974 tmprc = c->callback(AVC_CALLBACK_RESET);
975 /* save the first error encountered for the return
976 value and continue processing the callbacks */
982 avc_latest_notif_update(avc, seqno, 0);
987 * Slow-path helper function for avc_has_perm_noaudit,
988 * when the avc_node lookup fails. We get called with
989 * the RCU read lock held, and need to return with it
990 * still held, but drop if for the security compute.
992 * Don't inline this, since it's the slow-path and just
993 * results in a bigger stack frame.
996 struct avc_node *avc_compute_av(struct selinux_state *state,
998 u16 tclass, struct av_decision *avd,
999 struct avc_xperms_node *xp_node)
1002 INIT_LIST_HEAD(&xp_node->xpd_head);
1003 security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
1005 return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
1008 static noinline int avc_denied(struct selinux_state *state,
1010 u16 tclass, u32 requested,
1011 u8 driver, u8 xperm, unsigned int flags,
1012 struct av_decision *avd)
1014 if (flags & AVC_STRICT)
1017 if (enforcing_enabled(state) &&
1018 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1021 avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
1022 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1027 * The avc extended permissions logic adds an additional 256 bits of
1028 * permissions to an avc node when extended permissions for that node are
1029 * specified in the avtab. If the additional 256 permissions is not adequate,
1030 * as-is the case with ioctls, then multiple may be chained together and the
1031 * driver field is used to specify which set contains the permission.
1033 int avc_has_extended_perms(struct selinux_state *state,
1034 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1035 u8 driver, u8 xperm, struct common_audit_data *ad)
1037 struct avc_node *node;
1038 struct av_decision avd;
1040 struct extended_perms_decision local_xpd;
1041 struct extended_perms_decision *xpd = NULL;
1042 struct extended_perms_data allowed;
1043 struct extended_perms_data auditallow;
1044 struct extended_perms_data dontaudit;
1045 struct avc_xperms_node local_xp_node;
1046 struct avc_xperms_node *xp_node;
1049 xp_node = &local_xp_node;
1050 if (WARN_ON(!requested))
1055 node = avc_lookup(state->avc, ssid, tsid, tclass);
1056 if (unlikely(!node)) {
1057 node = avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
1059 memcpy(&avd, &node->ae.avd, sizeof(avd));
1060 xp_node = node->ae.xp_node;
1062 /* if extended permissions are not defined, only consider av_decision */
1063 if (!xp_node || !xp_node->xp.len)
1066 local_xpd.allowed = &allowed;
1067 local_xpd.auditallow = &auditallow;
1068 local_xpd.dontaudit = &dontaudit;
1070 xpd = avc_xperms_decision_lookup(driver, xp_node);
1071 if (unlikely(!xpd)) {
1073 * Compute the extended_perms_decision only if the driver
1076 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1077 avd.allowed &= ~requested;
1081 security_compute_xperms_decision(state, ssid, tsid, tclass,
1082 driver, &local_xpd);
1084 avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
1085 driver, xperm, ssid, tsid, tclass, avd.seqno,
1088 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1092 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1093 avd.allowed &= ~requested;
1096 denied = requested & ~(avd.allowed);
1097 if (unlikely(denied))
1098 rc = avc_denied(state, ssid, tsid, tclass, requested,
1099 driver, xperm, AVC_EXTENDED_PERMS, &avd);
1103 rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
1104 &avd, xpd, xperm, rc, ad);
1111 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1112 * @ssid: source security identifier
1113 * @tsid: target security identifier
1114 * @tclass: target security class
1115 * @requested: requested permissions, interpreted based on @tclass
1116 * @flags: AVC_STRICT, AVC_NONBLOCKING, or 0
1117 * @avd: access vector decisions
1119 * Check the AVC to determine whether the @requested permissions are granted
1120 * for the SID pair (@ssid, @tsid), interpreting the permissions
1121 * based on @tclass, and call the security server on a cache miss to obtain
1122 * a new decision and add it to the cache. Return a copy of the decisions
1123 * in @avd. Return %0 if all @requested permissions are granted,
1124 * -%EACCES if any permissions are denied, or another -errno upon
1125 * other errors. This function is typically called by avc_has_perm(),
1126 * but may also be called directly to separate permission checking from
1127 * auditing, e.g. in cases where a lock must be held for the check but
1128 * should be released for the auditing.
1130 inline int avc_has_perm_noaudit(struct selinux_state *state,
1132 u16 tclass, u32 requested,
1134 struct av_decision *avd)
1136 struct avc_node *node;
1137 struct avc_xperms_node xp_node;
1141 if (WARN_ON(!requested))
1146 node = avc_lookup(state->avc, ssid, tsid, tclass);
1147 if (unlikely(!node))
1148 node = avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
1150 memcpy(avd, &node->ae.avd, sizeof(*avd));
1152 denied = requested & ~(avd->allowed);
1153 if (unlikely(denied))
1154 rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
1162 * avc_has_perm - Check permissions and perform any appropriate auditing.
1163 * @ssid: source security identifier
1164 * @tsid: target security identifier
1165 * @tclass: target security class
1166 * @requested: requested permissions, interpreted based on @tclass
1167 * @auditdata: auxiliary audit data
1169 * Check the AVC to determine whether the @requested permissions are granted
1170 * for the SID pair (@ssid, @tsid), interpreting the permissions
1171 * based on @tclass, and call the security server on a cache miss to obtain
1172 * a new decision and add it to the cache. Audit the granting or denial of
1173 * permissions in accordance with the policy. Return %0 if all @requested
1174 * permissions are granted, -%EACCES if any permissions are denied, or
1175 * another -errno upon other errors.
1177 int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
1178 u32 requested, struct common_audit_data *auditdata)
1180 struct av_decision avd;
1183 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1186 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1193 int avc_has_perm_flags(struct selinux_state *state,
1194 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1195 struct common_audit_data *auditdata,
1198 struct av_decision avd;
1201 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested,
1202 (flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 0,
1205 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1212 u32 avc_policy_seqno(struct selinux_state *state)
1214 return state->avc->avc_cache.latest_notif;
1217 void avc_disable(void)
1220 * If you are looking at this because you have realized that we are
1221 * not destroying the avc_node_cachep it might be easy to fix, but
1222 * I don't know the memory barrier semantics well enough to know. It's
1223 * possible that some other task dereferenced security_ops when
1224 * it still pointed to selinux operations. If that is the case it's
1225 * possible that it is about to use the avc and is about to need the
1226 * avc_node_cachep. I know I could wrap the security.c security_ops call
1227 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1228 * the cache and get that memory back.
1230 if (avc_node_cachep) {
1231 avc_flush(selinux_state.avc);
1232 /* kmem_cache_destroy(avc_node_cachep); */