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 CREATE_TRACE_POINTS
35 #include <trace/events/avc.h>
37 #define AVC_CACHE_SLOTS 512
38 #define AVC_DEF_CACHE_THRESHOLD 512
39 #define AVC_CACHE_RECLAIM 16
41 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
42 #define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
44 #define avc_cache_stats_incr(field) do {} while (0)
51 struct av_decision avd;
52 struct avc_xperms_node *xp_node;
57 struct hlist_node list; /* anchored in avc_cache->slots[i] */
58 struct rcu_head rhead;
61 struct avc_xperms_decision_node {
62 struct extended_perms_decision xpd;
63 struct list_head xpd_list; /* list of extended_perms_decision */
66 struct avc_xperms_node {
67 struct extended_perms xp;
68 struct list_head xpd_head; /* list head of extended_perms_decision */
72 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
73 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
74 atomic_t lru_hint; /* LRU hint for reclaim scan */
75 atomic_t active_nodes;
76 u32 latest_notif; /* latest revocation notification */
79 struct avc_callback_node {
80 int (*callback) (u32 event);
82 struct avc_callback_node *next;
85 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
86 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
90 unsigned int avc_cache_threshold;
91 struct avc_cache avc_cache;
94 static struct selinux_avc selinux_avc;
96 void selinux_avc_init(struct selinux_avc **avc)
100 selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
101 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
102 INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
103 spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
105 atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
106 atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
110 unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
112 return avc->avc_cache_threshold;
115 void avc_set_cache_threshold(struct selinux_avc *avc,
116 unsigned int cache_threshold)
118 avc->avc_cache_threshold = cache_threshold;
121 static struct avc_callback_node *avc_callbacks __ro_after_init;
122 static struct kmem_cache *avc_node_cachep __ro_after_init;
123 static struct kmem_cache *avc_xperms_data_cachep __ro_after_init;
124 static struct kmem_cache *avc_xperms_decision_cachep __ro_after_init;
125 static struct kmem_cache *avc_xperms_cachep __ro_after_init;
127 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
129 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
133 * avc_init - Initialize the AVC.
135 * Initialize the access vector cache.
137 void __init avc_init(void)
139 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
140 0, SLAB_PANIC, NULL);
141 avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
142 sizeof(struct avc_xperms_node),
143 0, SLAB_PANIC, NULL);
144 avc_xperms_decision_cachep = kmem_cache_create(
145 "avc_xperms_decision_node",
146 sizeof(struct avc_xperms_decision_node),
147 0, SLAB_PANIC, NULL);
148 avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
149 sizeof(struct extended_perms_data),
150 0, SLAB_PANIC, NULL);
153 int avc_get_hash_stats(struct selinux_avc *avc, char *page)
155 int i, chain_len, max_chain_len, slots_used;
156 struct avc_node *node;
157 struct hlist_head *head;
163 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
164 head = &avc->avc_cache.slots[i];
165 if (!hlist_empty(head)) {
168 hlist_for_each_entry_rcu(node, head, list)
170 if (chain_len > max_chain_len)
171 max_chain_len = chain_len;
177 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
178 "longest chain: %d\n",
179 atomic_read(&avc->avc_cache.active_nodes),
180 slots_used, AVC_CACHE_SLOTS, max_chain_len);
184 * using a linked list for extended_perms_decision lookup because the list is
185 * always small. i.e. less than 5, typically 1
187 static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
188 struct avc_xperms_node *xp_node)
190 struct avc_xperms_decision_node *xpd_node;
192 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
193 if (xpd_node->xpd.driver == driver)
194 return &xpd_node->xpd;
199 static inline unsigned int
200 avc_xperms_has_perm(struct extended_perms_decision *xpd,
205 if ((which == XPERMS_ALLOWED) &&
206 (xpd->used & XPERMS_ALLOWED))
207 rc = security_xperm_test(xpd->allowed->p, perm);
208 else if ((which == XPERMS_AUDITALLOW) &&
209 (xpd->used & XPERMS_AUDITALLOW))
210 rc = security_xperm_test(xpd->auditallow->p, perm);
211 else if ((which == XPERMS_DONTAUDIT) &&
212 (xpd->used & XPERMS_DONTAUDIT))
213 rc = security_xperm_test(xpd->dontaudit->p, perm);
217 static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
220 struct extended_perms_decision *xpd;
221 security_xperm_set(xp_node->xp.drivers.p, driver);
222 xpd = avc_xperms_decision_lookup(driver, xp_node);
223 if (xpd && xpd->allowed)
224 security_xperm_set(xpd->allowed->p, perm);
227 static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
229 struct extended_perms_decision *xpd;
231 xpd = &xpd_node->xpd;
233 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
235 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
237 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
238 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
241 static void avc_xperms_free(struct avc_xperms_node *xp_node)
243 struct avc_xperms_decision_node *xpd_node, *tmp;
248 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
249 list_del(&xpd_node->xpd_list);
250 avc_xperms_decision_free(xpd_node);
252 kmem_cache_free(avc_xperms_cachep, xp_node);
255 static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
256 struct extended_perms_decision *src)
258 dest->driver = src->driver;
259 dest->used = src->used;
260 if (dest->used & XPERMS_ALLOWED)
261 memcpy(dest->allowed->p, src->allowed->p,
262 sizeof(src->allowed->p));
263 if (dest->used & XPERMS_AUDITALLOW)
264 memcpy(dest->auditallow->p, src->auditallow->p,
265 sizeof(src->auditallow->p));
266 if (dest->used & XPERMS_DONTAUDIT)
267 memcpy(dest->dontaudit->p, src->dontaudit->p,
268 sizeof(src->dontaudit->p));
272 * similar to avc_copy_xperms_decision, but only copy decision
273 * information relevant to this perm
275 static inline void avc_quick_copy_xperms_decision(u8 perm,
276 struct extended_perms_decision *dest,
277 struct extended_perms_decision *src)
280 * compute index of the u32 of the 256 bits (8 u32s) that contain this
285 dest->used = src->used;
286 if (dest->used & XPERMS_ALLOWED)
287 dest->allowed->p[i] = src->allowed->p[i];
288 if (dest->used & XPERMS_AUDITALLOW)
289 dest->auditallow->p[i] = src->auditallow->p[i];
290 if (dest->used & XPERMS_DONTAUDIT)
291 dest->dontaudit->p[i] = src->dontaudit->p[i];
294 static struct avc_xperms_decision_node
295 *avc_xperms_decision_alloc(u8 which)
297 struct avc_xperms_decision_node *xpd_node;
298 struct extended_perms_decision *xpd;
300 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
301 GFP_NOWAIT | __GFP_NOWARN);
305 xpd = &xpd_node->xpd;
306 if (which & XPERMS_ALLOWED) {
307 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
308 GFP_NOWAIT | __GFP_NOWARN);
312 if (which & XPERMS_AUDITALLOW) {
313 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
314 GFP_NOWAIT | __GFP_NOWARN);
315 if (!xpd->auditallow)
318 if (which & XPERMS_DONTAUDIT) {
319 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
320 GFP_NOWAIT | __GFP_NOWARN);
326 avc_xperms_decision_free(xpd_node);
330 static int avc_add_xperms_decision(struct avc_node *node,
331 struct extended_perms_decision *src)
333 struct avc_xperms_decision_node *dest_xpd;
335 node->ae.xp_node->xp.len++;
336 dest_xpd = avc_xperms_decision_alloc(src->used);
339 avc_copy_xperms_decision(&dest_xpd->xpd, src);
340 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
344 static struct avc_xperms_node *avc_xperms_alloc(void)
346 struct avc_xperms_node *xp_node;
348 xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT | __GFP_NOWARN);
351 INIT_LIST_HEAD(&xp_node->xpd_head);
355 static int avc_xperms_populate(struct avc_node *node,
356 struct avc_xperms_node *src)
358 struct avc_xperms_node *dest;
359 struct avc_xperms_decision_node *dest_xpd;
360 struct avc_xperms_decision_node *src_xpd;
362 if (src->xp.len == 0)
364 dest = avc_xperms_alloc();
368 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
369 dest->xp.len = src->xp.len;
371 /* for each source xpd allocate a destination xpd and copy */
372 list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
373 dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
376 avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
377 list_add(&dest_xpd->xpd_list, &dest->xpd_head);
379 node->ae.xp_node = dest;
382 avc_xperms_free(dest);
387 static inline u32 avc_xperms_audit_required(u32 requested,
388 struct av_decision *avd,
389 struct extended_perms_decision *xpd,
396 denied = requested & ~avd->allowed;
397 if (unlikely(denied)) {
398 audited = denied & avd->auditdeny;
399 if (audited && xpd) {
400 if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
401 audited &= ~requested;
404 audited = denied = requested;
406 audited = requested & avd->auditallow;
407 if (audited && xpd) {
408 if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
409 audited &= ~requested;
417 static inline int avc_xperms_audit(struct selinux_state *state,
418 u32 ssid, u32 tsid, u16 tclass,
419 u32 requested, struct av_decision *avd,
420 struct extended_perms_decision *xpd,
422 struct common_audit_data *ad)
426 audited = avc_xperms_audit_required(
427 requested, avd, xpd, perm, result, &denied);
428 if (likely(!audited))
430 return slow_avc_audit(state, ssid, tsid, tclass, requested,
431 audited, denied, result, ad);
434 static void avc_node_free(struct rcu_head *rhead)
436 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
437 avc_xperms_free(node->ae.xp_node);
438 kmem_cache_free(avc_node_cachep, node);
439 avc_cache_stats_incr(frees);
442 static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
444 hlist_del_rcu(&node->list);
445 call_rcu(&node->rhead, avc_node_free);
446 atomic_dec(&avc->avc_cache.active_nodes);
449 static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
451 avc_xperms_free(node->ae.xp_node);
452 kmem_cache_free(avc_node_cachep, node);
453 avc_cache_stats_incr(frees);
454 atomic_dec(&avc->avc_cache.active_nodes);
457 static void avc_node_replace(struct selinux_avc *avc,
458 struct avc_node *new, struct avc_node *old)
460 hlist_replace_rcu(&old->list, &new->list);
461 call_rcu(&old->rhead, avc_node_free);
462 atomic_dec(&avc->avc_cache.active_nodes);
465 static inline int avc_reclaim_node(struct selinux_avc *avc)
467 struct avc_node *node;
468 int hvalue, try, ecx;
470 struct hlist_head *head;
473 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
474 hvalue = atomic_inc_return(&avc->avc_cache.lru_hint) &
475 (AVC_CACHE_SLOTS - 1);
476 head = &avc->avc_cache.slots[hvalue];
477 lock = &avc->avc_cache.slots_lock[hvalue];
479 if (!spin_trylock_irqsave(lock, flags))
483 hlist_for_each_entry(node, head, list) {
484 avc_node_delete(avc, node);
485 avc_cache_stats_incr(reclaims);
487 if (ecx >= AVC_CACHE_RECLAIM) {
489 spin_unlock_irqrestore(lock, flags);
494 spin_unlock_irqrestore(lock, flags);
500 static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
502 struct avc_node *node;
504 node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN);
508 INIT_HLIST_NODE(&node->list);
509 avc_cache_stats_incr(allocations);
511 if (atomic_inc_return(&avc->avc_cache.active_nodes) >
512 avc->avc_cache_threshold)
513 avc_reclaim_node(avc);
519 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
521 node->ae.ssid = ssid;
522 node->ae.tsid = tsid;
523 node->ae.tclass = tclass;
524 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
527 static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
528 u32 ssid, u32 tsid, u16 tclass)
530 struct avc_node *node, *ret = NULL;
532 struct hlist_head *head;
534 hvalue = avc_hash(ssid, tsid, tclass);
535 head = &avc->avc_cache.slots[hvalue];
536 hlist_for_each_entry_rcu(node, head, list) {
537 if (ssid == node->ae.ssid &&
538 tclass == node->ae.tclass &&
539 tsid == node->ae.tsid) {
549 * avc_lookup - Look up an AVC entry.
550 * @ssid: source security identifier
551 * @tsid: target security identifier
552 * @tclass: target security class
554 * Look up an AVC entry that is valid for the
555 * (@ssid, @tsid), interpreting the permissions
556 * based on @tclass. If a valid AVC entry exists,
557 * then this function returns the avc_node.
558 * Otherwise, this function returns NULL.
560 static struct avc_node *avc_lookup(struct selinux_avc *avc,
561 u32 ssid, u32 tsid, u16 tclass)
563 struct avc_node *node;
565 avc_cache_stats_incr(lookups);
566 node = avc_search_node(avc, ssid, tsid, tclass);
571 avc_cache_stats_incr(misses);
575 static int avc_latest_notif_update(struct selinux_avc *avc,
576 int seqno, int is_insert)
579 static DEFINE_SPINLOCK(notif_lock);
582 spin_lock_irqsave(¬if_lock, flag);
584 if (seqno < avc->avc_cache.latest_notif) {
585 pr_warn("SELinux: avc: seqno %d < latest_notif %d\n",
586 seqno, avc->avc_cache.latest_notif);
590 if (seqno > avc->avc_cache.latest_notif)
591 avc->avc_cache.latest_notif = seqno;
593 spin_unlock_irqrestore(¬if_lock, flag);
599 * avc_insert - Insert an AVC entry.
600 * @ssid: source security identifier
601 * @tsid: target security identifier
602 * @tclass: target security class
603 * @avd: resulting av decision
604 * @xp_node: resulting extended permissions
606 * Insert an AVC entry for the SID pair
607 * (@ssid, @tsid) and class @tclass.
608 * The access vectors and the sequence number are
609 * normally provided by the security server in
610 * response to a security_compute_av() call. If the
611 * sequence number @avd->seqno is not less than the latest
612 * revocation notification, then the function copies
613 * the access vectors into a cache entry, returns
614 * avc_node inserted. Otherwise, this function returns NULL.
616 static struct avc_node *avc_insert(struct selinux_avc *avc,
617 u32 ssid, u32 tsid, u16 tclass,
618 struct av_decision *avd,
619 struct avc_xperms_node *xp_node)
621 struct avc_node *pos, *node = NULL;
625 struct hlist_head *head;
627 if (avc_latest_notif_update(avc, avd->seqno, 1))
630 node = avc_alloc_node(avc);
634 avc_node_populate(node, ssid, tsid, tclass, avd);
635 if (avc_xperms_populate(node, xp_node)) {
636 avc_node_kill(avc, node);
640 hvalue = avc_hash(ssid, tsid, tclass);
641 head = &avc->avc_cache.slots[hvalue];
642 lock = &avc->avc_cache.slots_lock[hvalue];
643 spin_lock_irqsave(lock, flag);
644 hlist_for_each_entry(pos, head, list) {
645 if (pos->ae.ssid == ssid &&
646 pos->ae.tsid == tsid &&
647 pos->ae.tclass == tclass) {
648 avc_node_replace(avc, node, pos);
652 hlist_add_head_rcu(&node->list, head);
654 spin_unlock_irqrestore(lock, flag);
659 * avc_audit_pre_callback - SELinux specific information
660 * will be called by generic audit code
661 * @ab: the audit buffer
664 static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
666 struct common_audit_data *ad = a;
667 struct selinux_audit_data *sad = ad->selinux_audit_data;
668 u32 av = sad->audited;
672 audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
675 audit_log_format(ab, " null");
679 perms = secclass_map[sad->tclass-1].perms;
681 audit_log_format(ab, " {");
684 while (i < (sizeof(av) * 8)) {
685 if ((perm & av) && perms[i]) {
686 audit_log_format(ab, " %s", perms[i]);
694 audit_log_format(ab, " 0x%x", av);
696 audit_log_format(ab, " } for ");
700 * avc_audit_post_callback - SELinux specific information
701 * will be called by generic audit code
702 * @ab: the audit buffer
705 static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
707 struct common_audit_data *ad = a;
708 struct selinux_audit_data *sad = ad->selinux_audit_data;
709 char *scontext = NULL;
710 char *tcontext = NULL;
711 const char *tclass = NULL;
716 rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
719 audit_log_format(ab, " ssid=%d", sad->ssid);
721 audit_log_format(ab, " scontext=%s", scontext);
723 rc = security_sid_to_context(sad->state, sad->tsid, &tcontext,
726 audit_log_format(ab, " tsid=%d", sad->tsid);
728 audit_log_format(ab, " tcontext=%s", tcontext);
730 tclass = secclass_map[sad->tclass-1].name;
731 audit_log_format(ab, " tclass=%s", tclass);
734 audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
736 trace_selinux_audited(sad, scontext, tcontext, tclass);
740 /* in case of invalid context report also the actual context string */
741 rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
743 if (!rc && scontext) {
744 if (scontext_len && scontext[scontext_len - 1] == '\0')
746 audit_log_format(ab, " srawcon=");
747 audit_log_n_untrustedstring(ab, scontext, scontext_len);
751 rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
753 if (!rc && scontext) {
754 if (scontext_len && scontext[scontext_len - 1] == '\0')
756 audit_log_format(ab, " trawcon=");
757 audit_log_n_untrustedstring(ab, scontext, scontext_len);
763 * This is the slow part of avc audit with big stack footprint.
764 * Note that it is non-blocking and can be called from under
767 noinline int slow_avc_audit(struct selinux_state *state,
768 u32 ssid, u32 tsid, u16 tclass,
769 u32 requested, u32 audited, u32 denied, int result,
770 struct common_audit_data *a)
772 struct common_audit_data stack_data;
773 struct selinux_audit_data sad;
775 if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
780 a->type = LSM_AUDIT_DATA_NONE;
784 sad.requested = requested;
787 sad.audited = audited;
792 a->selinux_audit_data = &sad;
794 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
799 * avc_add_callback - Register a callback for security events.
800 * @callback: callback function
801 * @events: security events
803 * Register a callback function for events in the set @events.
804 * Returns %0 on success or -%ENOMEM if insufficient memory
805 * exists to add the callback.
807 int __init avc_add_callback(int (*callback)(u32 event), u32 events)
809 struct avc_callback_node *c;
812 c = kmalloc(sizeof(*c), GFP_KERNEL);
818 c->callback = callback;
820 c->next = avc_callbacks;
827 * avc_update_node - Update an AVC entry
828 * @event : Updating event
829 * @perms : Permission mask bits
830 * @ssid,@tsid,@tclass : identifier of an AVC entry
831 * @seqno : sequence number when decision was made
832 * @xpd: extended_perms_decision to be added to the node
833 * @flags: the AVC_* flags, e.g. AVC_EXTENDED_PERMS, or 0.
835 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
836 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
837 * otherwise, this function updates the AVC entry. The original AVC-entry object
838 * will release later by RCU.
840 static int avc_update_node(struct selinux_avc *avc,
841 u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
842 u32 tsid, u16 tclass, u32 seqno,
843 struct extended_perms_decision *xpd,
848 struct avc_node *pos, *node, *orig = NULL;
849 struct hlist_head *head;
852 node = avc_alloc_node(avc);
858 /* Lock the target slot */
859 hvalue = avc_hash(ssid, tsid, tclass);
861 head = &avc->avc_cache.slots[hvalue];
862 lock = &avc->avc_cache.slots_lock[hvalue];
864 spin_lock_irqsave(lock, flag);
866 hlist_for_each_entry(pos, head, list) {
867 if (ssid == pos->ae.ssid &&
868 tsid == pos->ae.tsid &&
869 tclass == pos->ae.tclass &&
870 seqno == pos->ae.avd.seqno){
878 avc_node_kill(avc, node);
883 * Copy and replace original node.
886 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
888 if (orig->ae.xp_node) {
889 rc = avc_xperms_populate(node, orig->ae.xp_node);
891 avc_node_kill(avc, node);
897 case AVC_CALLBACK_GRANT:
898 node->ae.avd.allowed |= perms;
899 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
900 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
902 case AVC_CALLBACK_TRY_REVOKE:
903 case AVC_CALLBACK_REVOKE:
904 node->ae.avd.allowed &= ~perms;
906 case AVC_CALLBACK_AUDITALLOW_ENABLE:
907 node->ae.avd.auditallow |= perms;
909 case AVC_CALLBACK_AUDITALLOW_DISABLE:
910 node->ae.avd.auditallow &= ~perms;
912 case AVC_CALLBACK_AUDITDENY_ENABLE:
913 node->ae.avd.auditdeny |= perms;
915 case AVC_CALLBACK_AUDITDENY_DISABLE:
916 node->ae.avd.auditdeny &= ~perms;
918 case AVC_CALLBACK_ADD_XPERMS:
919 avc_add_xperms_decision(node, xpd);
922 avc_node_replace(avc, node, orig);
924 spin_unlock_irqrestore(lock, flag);
930 * avc_flush - Flush the cache
932 static void avc_flush(struct selinux_avc *avc)
934 struct hlist_head *head;
935 struct avc_node *node;
940 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
941 head = &avc->avc_cache.slots[i];
942 lock = &avc->avc_cache.slots_lock[i];
944 spin_lock_irqsave(lock, flag);
946 * With preemptable RCU, the outer spinlock does not
947 * prevent RCU grace periods from ending.
950 hlist_for_each_entry(node, head, list)
951 avc_node_delete(avc, node);
953 spin_unlock_irqrestore(lock, flag);
958 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
959 * @seqno: policy sequence number
961 int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
963 struct avc_callback_node *c;
968 for (c = avc_callbacks; c; c = c->next) {
969 if (c->events & AVC_CALLBACK_RESET) {
970 tmprc = c->callback(AVC_CALLBACK_RESET);
971 /* save the first error encountered for the return
972 value and continue processing the callbacks */
978 avc_latest_notif_update(avc, seqno, 0);
983 * Slow-path helper function for avc_has_perm_noaudit,
984 * when the avc_node lookup fails. We get called with
985 * the RCU read lock held, and need to return with it
986 * still held, but drop if for the security compute.
988 * Don't inline this, since it's the slow-path and just
989 * results in a bigger stack frame.
992 struct avc_node *avc_compute_av(struct selinux_state *state,
994 u16 tclass, struct av_decision *avd,
995 struct avc_xperms_node *xp_node)
998 INIT_LIST_HEAD(&xp_node->xpd_head);
999 security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
1001 return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
1004 static noinline int avc_denied(struct selinux_state *state,
1006 u16 tclass, u32 requested,
1007 u8 driver, u8 xperm, unsigned int flags,
1008 struct av_decision *avd)
1010 if (flags & AVC_STRICT)
1013 if (enforcing_enabled(state) &&
1014 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1017 avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
1018 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1023 * The avc extended permissions logic adds an additional 256 bits of
1024 * permissions to an avc node when extended permissions for that node are
1025 * specified in the avtab. If the additional 256 permissions is not adequate,
1026 * as-is the case with ioctls, then multiple may be chained together and the
1027 * driver field is used to specify which set contains the permission.
1029 int avc_has_extended_perms(struct selinux_state *state,
1030 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1031 u8 driver, u8 xperm, struct common_audit_data *ad)
1033 struct avc_node *node;
1034 struct av_decision avd;
1036 struct extended_perms_decision local_xpd;
1037 struct extended_perms_decision *xpd = NULL;
1038 struct extended_perms_data allowed;
1039 struct extended_perms_data auditallow;
1040 struct extended_perms_data dontaudit;
1041 struct avc_xperms_node local_xp_node;
1042 struct avc_xperms_node *xp_node;
1045 xp_node = &local_xp_node;
1046 if (WARN_ON(!requested))
1051 node = avc_lookup(state->avc, ssid, tsid, tclass);
1052 if (unlikely(!node)) {
1053 node = avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
1055 memcpy(&avd, &node->ae.avd, sizeof(avd));
1056 xp_node = node->ae.xp_node;
1058 /* if extended permissions are not defined, only consider av_decision */
1059 if (!xp_node || !xp_node->xp.len)
1062 local_xpd.allowed = &allowed;
1063 local_xpd.auditallow = &auditallow;
1064 local_xpd.dontaudit = &dontaudit;
1066 xpd = avc_xperms_decision_lookup(driver, xp_node);
1067 if (unlikely(!xpd)) {
1069 * Compute the extended_perms_decision only if the driver
1072 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1073 avd.allowed &= ~requested;
1077 security_compute_xperms_decision(state, ssid, tsid, tclass,
1078 driver, &local_xpd);
1080 avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
1081 driver, xperm, ssid, tsid, tclass, avd.seqno,
1084 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1088 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1089 avd.allowed &= ~requested;
1092 denied = requested & ~(avd.allowed);
1093 if (unlikely(denied))
1094 rc = avc_denied(state, ssid, tsid, tclass, requested,
1095 driver, xperm, AVC_EXTENDED_PERMS, &avd);
1099 rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
1100 &avd, xpd, xperm, rc, ad);
1107 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1108 * @ssid: source security identifier
1109 * @tsid: target security identifier
1110 * @tclass: target security class
1111 * @requested: requested permissions, interpreted based on @tclass
1112 * @flags: AVC_STRICT or 0
1113 * @avd: access vector decisions
1115 * Check the AVC to determine whether the @requested permissions are granted
1116 * for the SID pair (@ssid, @tsid), interpreting the permissions
1117 * based on @tclass, and call the security server on a cache miss to obtain
1118 * a new decision and add it to the cache. Return a copy of the decisions
1119 * in @avd. Return %0 if all @requested permissions are granted,
1120 * -%EACCES if any permissions are denied, or another -errno upon
1121 * other errors. This function is typically called by avc_has_perm(),
1122 * but may also be called directly to separate permission checking from
1123 * auditing, e.g. in cases where a lock must be held for the check but
1124 * should be released for the auditing.
1126 inline int avc_has_perm_noaudit(struct selinux_state *state,
1128 u16 tclass, u32 requested,
1130 struct av_decision *avd)
1132 struct avc_node *node;
1133 struct avc_xperms_node xp_node;
1137 if (WARN_ON(!requested))
1142 node = avc_lookup(state->avc, ssid, tsid, tclass);
1143 if (unlikely(!node))
1144 node = avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
1146 memcpy(avd, &node->ae.avd, sizeof(*avd));
1148 denied = requested & ~(avd->allowed);
1149 if (unlikely(denied))
1150 rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
1158 * avc_has_perm - Check permissions and perform any appropriate auditing.
1159 * @ssid: source security identifier
1160 * @tsid: target security identifier
1161 * @tclass: target security class
1162 * @requested: requested permissions, interpreted based on @tclass
1163 * @auditdata: auxiliary audit data
1165 * Check the AVC to determine whether the @requested permissions are granted
1166 * for the SID pair (@ssid, @tsid), interpreting the permissions
1167 * based on @tclass, and call the security server on a cache miss to obtain
1168 * a new decision and add it to the cache. Audit the granting or denial of
1169 * permissions in accordance with the policy. Return %0 if all @requested
1170 * permissions are granted, -%EACCES if any permissions are denied, or
1171 * another -errno upon other errors.
1173 int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
1174 u32 requested, struct common_audit_data *auditdata)
1176 struct av_decision avd;
1179 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1182 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1189 u32 avc_policy_seqno(struct selinux_state *state)
1191 return state->avc->avc_cache.latest_notif;
1194 void avc_disable(void)
1197 * If you are looking at this because you have realized that we are
1198 * not destroying the avc_node_cachep it might be easy to fix, but
1199 * I don't know the memory barrier semantics well enough to know. It's
1200 * possible that some other task dereferenced security_ops when
1201 * it still pointed to selinux operations. If that is the case it's
1202 * possible that it is about to use the avc and is about to need the
1203 * avc_node_cachep. I know I could wrap the security.c security_ops call
1204 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1205 * the cache and get that memory back.
1207 if (avc_node_cachep) {
1208 avc_flush(selinux_state.avc);
1209 /* kmem_cache_destroy(avc_node_cachep); */