2 * Implementation of the kernel access vector cache (AVC).
4 * Authors: Stephen Smalley, <sds@epoch.ncsc.mil>
5 * James Morris <jmorris@redhat.com>
7 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
8 * Replaced the avc_lock spinlock by RCU.
10 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2,
14 * as published by the Free Software Foundation.
16 #include <linux/types.h>
17 #include <linux/stddef.h>
18 #include <linux/kernel.h>
19 #include <linux/slab.h>
21 #include <linux/dcache.h>
22 #include <linux/init.h>
23 #include <linux/skbuff.h>
24 #include <linux/percpu.h>
25 #include <linux/list.h>
28 #include <net/af_unix.h>
30 #include <linux/audit.h>
31 #include <linux/ipv6.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 /* Exported via selinufs */
86 unsigned int avc_cache_threshold
= AVC_DEF_CACHE_THRESHOLD
;
88 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
89 DEFINE_PER_CPU(struct avc_cache_stats
, avc_cache_stats
) = { 0 };
92 static struct avc_cache avc_cache
;
93 static struct avc_callback_node
*avc_callbacks
;
94 static struct kmem_cache
*avc_node_cachep
;
95 static struct kmem_cache
*avc_xperms_data_cachep
;
96 static struct kmem_cache
*avc_xperms_decision_cachep
;
97 static struct kmem_cache
*avc_xperms_cachep
;
99 static inline int avc_hash(u32 ssid
, u32 tsid
, u16 tclass
)
101 return (ssid
^ (tsid
<<2) ^ (tclass
<<4)) & (AVC_CACHE_SLOTS
- 1);
105 * avc_dump_av - Display an access vector in human-readable form.
106 * @tclass: target security class
109 static void avc_dump_av(struct audit_buffer
*ab
, u16 tclass
, u32 av
)
115 audit_log_format(ab
, " null");
119 perms
= secclass_map
[tclass
-1].perms
;
121 audit_log_format(ab
, " {");
124 while (i
< (sizeof(av
) * 8)) {
125 if ((perm
& av
) && perms
[i
]) {
126 audit_log_format(ab
, " %s", perms
[i
]);
134 audit_log_format(ab
, " 0x%x", av
);
136 audit_log_format(ab
, " }");
140 * avc_dump_query - Display a SID pair and a class in human-readable form.
141 * @ssid: source security identifier
142 * @tsid: target security identifier
143 * @tclass: target security class
145 static void avc_dump_query(struct audit_buffer
*ab
, u32 ssid
, u32 tsid
, u16 tclass
)
151 rc
= security_sid_to_context(ssid
, &scontext
, &scontext_len
);
153 audit_log_format(ab
, "ssid=%d", ssid
);
155 audit_log_format(ab
, "scontext=%s", scontext
);
159 rc
= security_sid_to_context(tsid
, &scontext
, &scontext_len
);
161 audit_log_format(ab
, " tsid=%d", tsid
);
163 audit_log_format(ab
, " tcontext=%s", scontext
);
167 BUG_ON(tclass
>= ARRAY_SIZE(secclass_map
));
168 audit_log_format(ab
, " tclass=%s", secclass_map
[tclass
-1].name
);
172 * avc_init - Initialize the AVC.
174 * Initialize the access vector cache.
176 void __init
avc_init(void)
180 for (i
= 0; i
< AVC_CACHE_SLOTS
; i
++) {
181 INIT_HLIST_HEAD(&avc_cache
.slots
[i
]);
182 spin_lock_init(&avc_cache
.slots_lock
[i
]);
184 atomic_set(&avc_cache
.active_nodes
, 0);
185 atomic_set(&avc_cache
.lru_hint
, 0);
187 avc_node_cachep
= kmem_cache_create("avc_node", sizeof(struct avc_node
),
188 0, SLAB_PANIC
, NULL
);
189 avc_xperms_cachep
= kmem_cache_create("avc_xperms_node",
190 sizeof(struct avc_xperms_node
),
191 0, SLAB_PANIC
, NULL
);
192 avc_xperms_decision_cachep
= kmem_cache_create(
193 "avc_xperms_decision_node",
194 sizeof(struct avc_xperms_decision_node
),
195 0, SLAB_PANIC
, NULL
);
196 avc_xperms_data_cachep
= kmem_cache_create("avc_xperms_data",
197 sizeof(struct extended_perms_data
),
198 0, SLAB_PANIC
, NULL
);
200 audit_log(current
->audit_context
, GFP_KERNEL
, AUDIT_KERNEL
, "AVC INITIALIZED\n");
203 int avc_get_hash_stats(char *page
)
205 int i
, chain_len
, max_chain_len
, slots_used
;
206 struct avc_node
*node
;
207 struct hlist_head
*head
;
213 for (i
= 0; i
< AVC_CACHE_SLOTS
; i
++) {
214 head
= &avc_cache
.slots
[i
];
215 if (!hlist_empty(head
)) {
218 hlist_for_each_entry_rcu(node
, head
, list
)
220 if (chain_len
> max_chain_len
)
221 max_chain_len
= chain_len
;
227 return scnprintf(page
, PAGE_SIZE
, "entries: %d\nbuckets used: %d/%d\n"
228 "longest chain: %d\n",
229 atomic_read(&avc_cache
.active_nodes
),
230 slots_used
, AVC_CACHE_SLOTS
, max_chain_len
);
234 * using a linked list for extended_perms_decision lookup because the list is
235 * always small. i.e. less than 5, typically 1
237 static struct extended_perms_decision
*avc_xperms_decision_lookup(u8 driver
,
238 struct avc_xperms_node
*xp_node
)
240 struct avc_xperms_decision_node
*xpd_node
;
242 list_for_each_entry(xpd_node
, &xp_node
->xpd_head
, xpd_list
) {
243 if (xpd_node
->xpd
.driver
== driver
)
244 return &xpd_node
->xpd
;
249 static inline unsigned int
250 avc_xperms_has_perm(struct extended_perms_decision
*xpd
,
255 if ((which
== XPERMS_ALLOWED
) &&
256 (xpd
->used
& XPERMS_ALLOWED
))
257 rc
= security_xperm_test(xpd
->allowed
->p
, perm
);
258 else if ((which
== XPERMS_AUDITALLOW
) &&
259 (xpd
->used
& XPERMS_AUDITALLOW
))
260 rc
= security_xperm_test(xpd
->auditallow
->p
, perm
);
261 else if ((which
== XPERMS_DONTAUDIT
) &&
262 (xpd
->used
& XPERMS_DONTAUDIT
))
263 rc
= security_xperm_test(xpd
->dontaudit
->p
, perm
);
267 static void avc_xperms_allow_perm(struct avc_xperms_node
*xp_node
,
270 struct extended_perms_decision
*xpd
;
271 security_xperm_set(xp_node
->xp
.drivers
.p
, driver
);
272 xpd
= avc_xperms_decision_lookup(driver
, xp_node
);
273 if (xpd
&& xpd
->allowed
)
274 security_xperm_set(xpd
->allowed
->p
, perm
);
277 static void avc_xperms_decision_free(struct avc_xperms_decision_node
*xpd_node
)
279 struct extended_perms_decision
*xpd
;
281 xpd
= &xpd_node
->xpd
;
283 kmem_cache_free(avc_xperms_data_cachep
, xpd
->allowed
);
285 kmem_cache_free(avc_xperms_data_cachep
, xpd
->auditallow
);
287 kmem_cache_free(avc_xperms_data_cachep
, xpd
->dontaudit
);
288 kmem_cache_free(avc_xperms_decision_cachep
, xpd_node
);
291 static void avc_xperms_free(struct avc_xperms_node
*xp_node
)
293 struct avc_xperms_decision_node
*xpd_node
, *tmp
;
298 list_for_each_entry_safe(xpd_node
, tmp
, &xp_node
->xpd_head
, xpd_list
) {
299 list_del(&xpd_node
->xpd_list
);
300 avc_xperms_decision_free(xpd_node
);
302 kmem_cache_free(avc_xperms_cachep
, xp_node
);
305 static void avc_copy_xperms_decision(struct extended_perms_decision
*dest
,
306 struct extended_perms_decision
*src
)
308 dest
->driver
= src
->driver
;
309 dest
->used
= src
->used
;
310 if (dest
->used
& XPERMS_ALLOWED
)
311 memcpy(dest
->allowed
->p
, src
->allowed
->p
,
312 sizeof(src
->allowed
->p
));
313 if (dest
->used
& XPERMS_AUDITALLOW
)
314 memcpy(dest
->auditallow
->p
, src
->auditallow
->p
,
315 sizeof(src
->auditallow
->p
));
316 if (dest
->used
& XPERMS_DONTAUDIT
)
317 memcpy(dest
->dontaudit
->p
, src
->dontaudit
->p
,
318 sizeof(src
->dontaudit
->p
));
322 * similar to avc_copy_xperms_decision, but only copy decision
323 * information relevant to this perm
325 static inline void avc_quick_copy_xperms_decision(u8 perm
,
326 struct extended_perms_decision
*dest
,
327 struct extended_perms_decision
*src
)
330 * compute index of the u32 of the 256 bits (8 u32s) that contain this
335 dest
->used
= src
->used
;
336 if (dest
->used
& XPERMS_ALLOWED
)
337 dest
->allowed
->p
[i
] = src
->allowed
->p
[i
];
338 if (dest
->used
& XPERMS_AUDITALLOW
)
339 dest
->auditallow
->p
[i
] = src
->auditallow
->p
[i
];
340 if (dest
->used
& XPERMS_DONTAUDIT
)
341 dest
->dontaudit
->p
[i
] = src
->dontaudit
->p
[i
];
344 static struct avc_xperms_decision_node
345 *avc_xperms_decision_alloc(u8 which
)
347 struct avc_xperms_decision_node
*xpd_node
;
348 struct extended_perms_decision
*xpd
;
350 xpd_node
= kmem_cache_zalloc(avc_xperms_decision_cachep
,
351 GFP_ATOMIC
| __GFP_NOMEMALLOC
);
355 xpd
= &xpd_node
->xpd
;
356 if (which
& XPERMS_ALLOWED
) {
357 xpd
->allowed
= kmem_cache_zalloc(avc_xperms_data_cachep
,
358 GFP_ATOMIC
| __GFP_NOMEMALLOC
);
362 if (which
& XPERMS_AUDITALLOW
) {
363 xpd
->auditallow
= kmem_cache_zalloc(avc_xperms_data_cachep
,
364 GFP_ATOMIC
| __GFP_NOMEMALLOC
);
365 if (!xpd
->auditallow
)
368 if (which
& XPERMS_DONTAUDIT
) {
369 xpd
->dontaudit
= kmem_cache_zalloc(avc_xperms_data_cachep
,
370 GFP_ATOMIC
| __GFP_NOMEMALLOC
);
376 avc_xperms_decision_free(xpd_node
);
380 static int avc_add_xperms_decision(struct avc_node
*node
,
381 struct extended_perms_decision
*src
)
383 struct avc_xperms_decision_node
*dest_xpd
;
385 node
->ae
.xp_node
->xp
.len
++;
386 dest_xpd
= avc_xperms_decision_alloc(src
->used
);
389 avc_copy_xperms_decision(&dest_xpd
->xpd
, src
);
390 list_add(&dest_xpd
->xpd_list
, &node
->ae
.xp_node
->xpd_head
);
394 static struct avc_xperms_node
*avc_xperms_alloc(void)
396 struct avc_xperms_node
*xp_node
;
398 xp_node
= kmem_cache_zalloc(avc_xperms_cachep
,
399 GFP_ATOMIC
|__GFP_NOMEMALLOC
);
402 INIT_LIST_HEAD(&xp_node
->xpd_head
);
406 static int avc_xperms_populate(struct avc_node
*node
,
407 struct avc_xperms_node
*src
)
409 struct avc_xperms_node
*dest
;
410 struct avc_xperms_decision_node
*dest_xpd
;
411 struct avc_xperms_decision_node
*src_xpd
;
413 if (src
->xp
.len
== 0)
415 dest
= avc_xperms_alloc();
419 memcpy(dest
->xp
.drivers
.p
, src
->xp
.drivers
.p
, sizeof(dest
->xp
.drivers
.p
));
420 dest
->xp
.len
= src
->xp
.len
;
422 /* for each source xpd allocate a destination xpd and copy */
423 list_for_each_entry(src_xpd
, &src
->xpd_head
, xpd_list
) {
424 dest_xpd
= avc_xperms_decision_alloc(src_xpd
->xpd
.used
);
427 avc_copy_xperms_decision(&dest_xpd
->xpd
, &src_xpd
->xpd
);
428 list_add(&dest_xpd
->xpd_list
, &dest
->xpd_head
);
430 node
->ae
.xp_node
= dest
;
433 avc_xperms_free(dest
);
438 static inline u32
avc_xperms_audit_required(u32 requested
,
439 struct av_decision
*avd
,
440 struct extended_perms_decision
*xpd
,
447 denied
= requested
& ~avd
->allowed
;
448 if (unlikely(denied
)) {
449 audited
= denied
& avd
->auditdeny
;
450 if (audited
&& xpd
) {
451 if (avc_xperms_has_perm(xpd
, perm
, XPERMS_DONTAUDIT
))
452 audited
&= ~requested
;
455 audited
= denied
= requested
;
457 audited
= requested
& avd
->auditallow
;
458 if (audited
&& xpd
) {
459 if (!avc_xperms_has_perm(xpd
, perm
, XPERMS_AUDITALLOW
))
460 audited
&= ~requested
;
468 static inline int avc_xperms_audit(u32 ssid
, u32 tsid
, u16 tclass
,
469 u32 requested
, struct av_decision
*avd
,
470 struct extended_perms_decision
*xpd
,
472 struct common_audit_data
*ad
)
476 audited
= avc_xperms_audit_required(
477 requested
, avd
, xpd
, perm
, result
, &denied
);
478 if (likely(!audited
))
480 return slow_avc_audit(ssid
, tsid
, tclass
, requested
,
481 audited
, denied
, result
, ad
, 0);
484 static void avc_node_free(struct rcu_head
*rhead
)
486 struct avc_node
*node
= container_of(rhead
, struct avc_node
, rhead
);
487 avc_xperms_free(node
->ae
.xp_node
);
488 kmem_cache_free(avc_node_cachep
, node
);
489 avc_cache_stats_incr(frees
);
492 static void avc_node_delete(struct avc_node
*node
)
494 hlist_del_rcu(&node
->list
);
495 call_rcu(&node
->rhead
, avc_node_free
);
496 atomic_dec(&avc_cache
.active_nodes
);
499 static void avc_node_kill(struct avc_node
*node
)
501 avc_xperms_free(node
->ae
.xp_node
);
502 kmem_cache_free(avc_node_cachep
, node
);
503 avc_cache_stats_incr(frees
);
504 atomic_dec(&avc_cache
.active_nodes
);
507 static void avc_node_replace(struct avc_node
*new, struct avc_node
*old
)
509 hlist_replace_rcu(&old
->list
, &new->list
);
510 call_rcu(&old
->rhead
, avc_node_free
);
511 atomic_dec(&avc_cache
.active_nodes
);
514 static inline int avc_reclaim_node(void)
516 struct avc_node
*node
;
517 int hvalue
, try, ecx
;
519 struct hlist_head
*head
;
522 for (try = 0, ecx
= 0; try < AVC_CACHE_SLOTS
; try++) {
523 hvalue
= atomic_inc_return(&avc_cache
.lru_hint
) & (AVC_CACHE_SLOTS
- 1);
524 head
= &avc_cache
.slots
[hvalue
];
525 lock
= &avc_cache
.slots_lock
[hvalue
];
527 if (!spin_trylock_irqsave(lock
, flags
))
531 hlist_for_each_entry(node
, head
, list
) {
532 avc_node_delete(node
);
533 avc_cache_stats_incr(reclaims
);
535 if (ecx
>= AVC_CACHE_RECLAIM
) {
537 spin_unlock_irqrestore(lock
, flags
);
542 spin_unlock_irqrestore(lock
, flags
);
548 static struct avc_node
*avc_alloc_node(void)
550 struct avc_node
*node
;
552 node
= kmem_cache_zalloc(avc_node_cachep
, GFP_ATOMIC
|__GFP_NOMEMALLOC
);
556 INIT_HLIST_NODE(&node
->list
);
557 avc_cache_stats_incr(allocations
);
559 if (atomic_inc_return(&avc_cache
.active_nodes
) > avc_cache_threshold
)
566 static void avc_node_populate(struct avc_node
*node
, u32 ssid
, u32 tsid
, u16 tclass
, struct av_decision
*avd
)
568 node
->ae
.ssid
= ssid
;
569 node
->ae
.tsid
= tsid
;
570 node
->ae
.tclass
= tclass
;
571 memcpy(&node
->ae
.avd
, avd
, sizeof(node
->ae
.avd
));
574 static inline struct avc_node
*avc_search_node(u32 ssid
, u32 tsid
, u16 tclass
)
576 struct avc_node
*node
, *ret
= NULL
;
578 struct hlist_head
*head
;
580 hvalue
= avc_hash(ssid
, tsid
, tclass
);
581 head
= &avc_cache
.slots
[hvalue
];
582 hlist_for_each_entry_rcu(node
, head
, list
) {
583 if (ssid
== node
->ae
.ssid
&&
584 tclass
== node
->ae
.tclass
&&
585 tsid
== node
->ae
.tsid
) {
595 * avc_lookup - Look up an AVC entry.
596 * @ssid: source security identifier
597 * @tsid: target security identifier
598 * @tclass: target security class
600 * Look up an AVC entry that is valid for the
601 * (@ssid, @tsid), interpreting the permissions
602 * based on @tclass. If a valid AVC entry exists,
603 * then this function returns the avc_node.
604 * Otherwise, this function returns NULL.
606 static struct avc_node
*avc_lookup(u32 ssid
, u32 tsid
, u16 tclass
)
608 struct avc_node
*node
;
610 avc_cache_stats_incr(lookups
);
611 node
= avc_search_node(ssid
, tsid
, tclass
);
616 avc_cache_stats_incr(misses
);
620 static int avc_latest_notif_update(int seqno
, int is_insert
)
623 static DEFINE_SPINLOCK(notif_lock
);
626 spin_lock_irqsave(¬if_lock
, flag
);
628 if (seqno
< avc_cache
.latest_notif
) {
629 printk(KERN_WARNING
"SELinux: avc: seqno %d < latest_notif %d\n",
630 seqno
, avc_cache
.latest_notif
);
634 if (seqno
> avc_cache
.latest_notif
)
635 avc_cache
.latest_notif
= seqno
;
637 spin_unlock_irqrestore(¬if_lock
, flag
);
643 * avc_insert - Insert an AVC entry.
644 * @ssid: source security identifier
645 * @tsid: target security identifier
646 * @tclass: target security class
647 * @avd: resulting av decision
648 * @xp_node: resulting extended permissions
650 * Insert an AVC entry for the SID pair
651 * (@ssid, @tsid) and class @tclass.
652 * The access vectors and the sequence number are
653 * normally provided by the security server in
654 * response to a security_compute_av() call. If the
655 * sequence number @avd->seqno is not less than the latest
656 * revocation notification, then the function copies
657 * the access vectors into a cache entry, returns
658 * avc_node inserted. Otherwise, this function returns NULL.
660 static struct avc_node
*avc_insert(u32 ssid
, u32 tsid
, u16 tclass
,
661 struct av_decision
*avd
,
662 struct avc_xperms_node
*xp_node
)
664 struct avc_node
*pos
, *node
= NULL
;
668 if (avc_latest_notif_update(avd
->seqno
, 1))
671 node
= avc_alloc_node();
673 struct hlist_head
*head
;
677 hvalue
= avc_hash(ssid
, tsid
, tclass
);
678 avc_node_populate(node
, ssid
, tsid
, tclass
, avd
);
679 rc
= avc_xperms_populate(node
, xp_node
);
681 kmem_cache_free(avc_node_cachep
, node
);
684 head
= &avc_cache
.slots
[hvalue
];
685 lock
= &avc_cache
.slots_lock
[hvalue
];
687 spin_lock_irqsave(lock
, flag
);
688 hlist_for_each_entry(pos
, head
, list
) {
689 if (pos
->ae
.ssid
== ssid
&&
690 pos
->ae
.tsid
== tsid
&&
691 pos
->ae
.tclass
== tclass
) {
692 avc_node_replace(node
, pos
);
696 hlist_add_head_rcu(&node
->list
, head
);
698 spin_unlock_irqrestore(lock
, flag
);
705 * avc_audit_pre_callback - SELinux specific information
706 * will be called by generic audit code
707 * @ab: the audit buffer
710 static void avc_audit_pre_callback(struct audit_buffer
*ab
, void *a
)
712 struct common_audit_data
*ad
= a
;
713 audit_log_format(ab
, "avc: %s ",
714 ad
->selinux_audit_data
->denied
? "denied" : "granted");
715 avc_dump_av(ab
, ad
->selinux_audit_data
->tclass
,
716 ad
->selinux_audit_data
->audited
);
717 audit_log_format(ab
, " for ");
721 * avc_audit_post_callback - SELinux specific information
722 * will be called by generic audit code
723 * @ab: the audit buffer
726 static void avc_audit_post_callback(struct audit_buffer
*ab
, void *a
)
728 struct common_audit_data
*ad
= a
;
729 audit_log_format(ab
, " ");
730 avc_dump_query(ab
, ad
->selinux_audit_data
->ssid
,
731 ad
->selinux_audit_data
->tsid
,
732 ad
->selinux_audit_data
->tclass
);
733 if (ad
->selinux_audit_data
->denied
) {
734 audit_log_format(ab
, " permissive=%u",
735 ad
->selinux_audit_data
->result
? 0 : 1);
739 /* This is the slow part of avc audit with big stack footprint */
740 noinline
int slow_avc_audit(u32 ssid
, u32 tsid
, u16 tclass
,
741 u32 requested
, u32 audited
, u32 denied
, int result
,
742 struct common_audit_data
*a
,
745 struct common_audit_data stack_data
;
746 struct selinux_audit_data sad
;
750 a
->type
= LSM_AUDIT_DATA_NONE
;
754 * When in a RCU walk do the audit on the RCU retry. This is because
755 * the collection of the dname in an inode audit message is not RCU
756 * safe. Note this may drop some audits when the situation changes
757 * during retry. However this is logically just as if the operation
758 * happened a little later.
760 if ((a
->type
== LSM_AUDIT_DATA_INODE
) &&
761 (flags
& MAY_NOT_BLOCK
))
765 sad
.requested
= requested
;
768 sad
.audited
= audited
;
772 a
->selinux_audit_data
= &sad
;
774 common_lsm_audit(a
, avc_audit_pre_callback
, avc_audit_post_callback
);
779 * avc_add_callback - Register a callback for security events.
780 * @callback: callback function
781 * @events: security events
783 * Register a callback function for events in the set @events.
784 * Returns %0 on success or -%ENOMEM if insufficient memory
785 * exists to add the callback.
787 int __init
avc_add_callback(int (*callback
)(u32 event
), u32 events
)
789 struct avc_callback_node
*c
;
792 c
= kmalloc(sizeof(*c
), GFP_KERNEL
);
798 c
->callback
= callback
;
800 c
->next
= avc_callbacks
;
807 * avc_update_node Update an AVC entry
808 * @event : Updating event
809 * @perms : Permission mask bits
810 * @ssid,@tsid,@tclass : identifier of an AVC entry
811 * @seqno : sequence number when decision was made
812 * @xpd: extended_perms_decision to be added to the node
814 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
815 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
816 * otherwise, this function updates the AVC entry. The original AVC-entry object
817 * will release later by RCU.
819 static int avc_update_node(u32 event
, u32 perms
, u8 driver
, u8 xperm
, u32 ssid
,
820 u32 tsid
, u16 tclass
, u32 seqno
,
821 struct extended_perms_decision
*xpd
,
826 struct avc_node
*pos
, *node
, *orig
= NULL
;
827 struct hlist_head
*head
;
830 node
= avc_alloc_node();
836 /* Lock the target slot */
837 hvalue
= avc_hash(ssid
, tsid
, tclass
);
839 head
= &avc_cache
.slots
[hvalue
];
840 lock
= &avc_cache
.slots_lock
[hvalue
];
842 spin_lock_irqsave(lock
, flag
);
844 hlist_for_each_entry(pos
, head
, list
) {
845 if (ssid
== pos
->ae
.ssid
&&
846 tsid
== pos
->ae
.tsid
&&
847 tclass
== pos
->ae
.tclass
&&
848 seqno
== pos
->ae
.avd
.seqno
){
861 * Copy and replace original node.
864 avc_node_populate(node
, ssid
, tsid
, tclass
, &orig
->ae
.avd
);
866 if (orig
->ae
.xp_node
) {
867 rc
= avc_xperms_populate(node
, orig
->ae
.xp_node
);
869 kmem_cache_free(avc_node_cachep
, node
);
875 case AVC_CALLBACK_GRANT
:
876 node
->ae
.avd
.allowed
|= perms
;
877 if (node
->ae
.xp_node
&& (flags
& AVC_EXTENDED_PERMS
))
878 avc_xperms_allow_perm(node
->ae
.xp_node
, driver
, xperm
);
880 case AVC_CALLBACK_TRY_REVOKE
:
881 case AVC_CALLBACK_REVOKE
:
882 node
->ae
.avd
.allowed
&= ~perms
;
884 case AVC_CALLBACK_AUDITALLOW_ENABLE
:
885 node
->ae
.avd
.auditallow
|= perms
;
887 case AVC_CALLBACK_AUDITALLOW_DISABLE
:
888 node
->ae
.avd
.auditallow
&= ~perms
;
890 case AVC_CALLBACK_AUDITDENY_ENABLE
:
891 node
->ae
.avd
.auditdeny
|= perms
;
893 case AVC_CALLBACK_AUDITDENY_DISABLE
:
894 node
->ae
.avd
.auditdeny
&= ~perms
;
896 case AVC_CALLBACK_ADD_XPERMS
:
897 avc_add_xperms_decision(node
, xpd
);
900 avc_node_replace(node
, orig
);
902 spin_unlock_irqrestore(lock
, flag
);
908 * avc_flush - Flush the cache
910 static void avc_flush(void)
912 struct hlist_head
*head
;
913 struct avc_node
*node
;
918 for (i
= 0; i
< AVC_CACHE_SLOTS
; i
++) {
919 head
= &avc_cache
.slots
[i
];
920 lock
= &avc_cache
.slots_lock
[i
];
922 spin_lock_irqsave(lock
, flag
);
924 * With preemptable RCU, the outer spinlock does not
925 * prevent RCU grace periods from ending.
928 hlist_for_each_entry(node
, head
, list
)
929 avc_node_delete(node
);
931 spin_unlock_irqrestore(lock
, flag
);
936 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
937 * @seqno: policy sequence number
939 int avc_ss_reset(u32 seqno
)
941 struct avc_callback_node
*c
;
946 for (c
= avc_callbacks
; c
; c
= c
->next
) {
947 if (c
->events
& AVC_CALLBACK_RESET
) {
948 tmprc
= c
->callback(AVC_CALLBACK_RESET
);
949 /* save the first error encountered for the return
950 value and continue processing the callbacks */
956 avc_latest_notif_update(seqno
, 0);
961 * Slow-path helper function for avc_has_perm_noaudit,
962 * when the avc_node lookup fails. We get called with
963 * the RCU read lock held, and need to return with it
964 * still held, but drop if for the security compute.
966 * Don't inline this, since it's the slow-path and just
967 * results in a bigger stack frame.
969 static noinline
struct avc_node
*avc_compute_av(u32 ssid
, u32 tsid
,
970 u16 tclass
, struct av_decision
*avd
,
971 struct avc_xperms_node
*xp_node
)
974 INIT_LIST_HEAD(&xp_node
->xpd_head
);
975 security_compute_av(ssid
, tsid
, tclass
, avd
, &xp_node
->xp
);
977 return avc_insert(ssid
, tsid
, tclass
, avd
, xp_node
);
980 static noinline
int avc_denied(u32 ssid
, u32 tsid
,
981 u16 tclass
, u32 requested
,
982 u8 driver
, u8 xperm
, unsigned flags
,
983 struct av_decision
*avd
)
985 if (flags
& AVC_STRICT
)
988 if (selinux_enforcing
&& !(avd
->flags
& AVD_FLAGS_PERMISSIVE
))
991 avc_update_node(AVC_CALLBACK_GRANT
, requested
, driver
, xperm
, ssid
,
992 tsid
, tclass
, avd
->seqno
, NULL
, flags
);
997 * The avc extended permissions logic adds an additional 256 bits of
998 * permissions to an avc node when extended permissions for that node are
999 * specified in the avtab. If the additional 256 permissions is not adequate,
1000 * as-is the case with ioctls, then multiple may be chained together and the
1001 * driver field is used to specify which set contains the permission.
1003 int avc_has_extended_perms(u32 ssid
, u32 tsid
, u16 tclass
, u32 requested
,
1004 u8 driver
, u8 xperm
, struct common_audit_data
*ad
)
1006 struct avc_node
*node
;
1007 struct av_decision avd
;
1009 struct extended_perms_decision local_xpd
;
1010 struct extended_perms_decision
*xpd
= NULL
;
1011 struct extended_perms_data allowed
;
1012 struct extended_perms_data auditallow
;
1013 struct extended_perms_data dontaudit
;
1014 struct avc_xperms_node local_xp_node
;
1015 struct avc_xperms_node
*xp_node
;
1018 xp_node
= &local_xp_node
;
1023 node
= avc_lookup(ssid
, tsid
, tclass
);
1024 if (unlikely(!node
)) {
1025 node
= avc_compute_av(ssid
, tsid
, tclass
, &avd
, xp_node
);
1027 memcpy(&avd
, &node
->ae
.avd
, sizeof(avd
));
1028 xp_node
= node
->ae
.xp_node
;
1030 /* if extended permissions are not defined, only consider av_decision */
1031 if (!xp_node
|| !xp_node
->xp
.len
)
1034 local_xpd
.allowed
= &allowed
;
1035 local_xpd
.auditallow
= &auditallow
;
1036 local_xpd
.dontaudit
= &dontaudit
;
1038 xpd
= avc_xperms_decision_lookup(driver
, xp_node
);
1039 if (unlikely(!xpd
)) {
1041 * Compute the extended_perms_decision only if the driver
1044 if (!security_xperm_test(xp_node
->xp
.drivers
.p
, driver
)) {
1045 avd
.allowed
&= ~requested
;
1049 security_compute_xperms_decision(ssid
, tsid
, tclass
, driver
,
1052 avc_update_node(AVC_CALLBACK_ADD_XPERMS
, requested
, driver
, xperm
,
1053 ssid
, tsid
, tclass
, avd
.seqno
, &local_xpd
, 0);
1055 avc_quick_copy_xperms_decision(xperm
, &local_xpd
, xpd
);
1059 if (!avc_xperms_has_perm(xpd
, xperm
, XPERMS_ALLOWED
))
1060 avd
.allowed
&= ~requested
;
1063 denied
= requested
& ~(avd
.allowed
);
1064 if (unlikely(denied
))
1065 rc
= avc_denied(ssid
, tsid
, tclass
, requested
, driver
, xperm
,
1066 AVC_EXTENDED_PERMS
, &avd
);
1070 rc2
= avc_xperms_audit(ssid
, tsid
, tclass
, requested
,
1071 &avd
, xpd
, xperm
, rc
, ad
);
1078 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1079 * @ssid: source security identifier
1080 * @tsid: target security identifier
1081 * @tclass: target security class
1082 * @requested: requested permissions, interpreted based on @tclass
1083 * @flags: AVC_STRICT or 0
1084 * @avd: access vector decisions
1086 * Check the AVC to determine whether the @requested permissions are granted
1087 * for the SID pair (@ssid, @tsid), interpreting the permissions
1088 * based on @tclass, and call the security server on a cache miss to obtain
1089 * a new decision and add it to the cache. Return a copy of the decisions
1090 * in @avd. Return %0 if all @requested permissions are granted,
1091 * -%EACCES if any permissions are denied, or another -errno upon
1092 * other errors. This function is typically called by avc_has_perm(),
1093 * but may also be called directly to separate permission checking from
1094 * auditing, e.g. in cases where a lock must be held for the check but
1095 * should be released for the auditing.
1097 inline int avc_has_perm_noaudit(u32 ssid
, u32 tsid
,
1098 u16 tclass
, u32 requested
,
1100 struct av_decision
*avd
)
1102 struct avc_node
*node
;
1103 struct avc_xperms_node xp_node
;
1111 node
= avc_lookup(ssid
, tsid
, tclass
);
1112 if (unlikely(!node
))
1113 node
= avc_compute_av(ssid
, tsid
, tclass
, avd
, &xp_node
);
1115 memcpy(avd
, &node
->ae
.avd
, sizeof(*avd
));
1117 denied
= requested
& ~(avd
->allowed
);
1118 if (unlikely(denied
))
1119 rc
= avc_denied(ssid
, tsid
, tclass
, requested
, 0, 0, flags
, avd
);
1126 * avc_has_perm - Check permissions and perform any appropriate auditing.
1127 * @ssid: source security identifier
1128 * @tsid: target security identifier
1129 * @tclass: target security class
1130 * @requested: requested permissions, interpreted based on @tclass
1131 * @auditdata: auxiliary audit data
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. Audit the granting or denial of
1137 * permissions in accordance with the policy. Return %0 if all @requested
1138 * permissions are granted, -%EACCES if any permissions are denied, or
1139 * another -errno upon other errors.
1141 int avc_has_perm(u32 ssid
, u32 tsid
, u16 tclass
,
1142 u32 requested
, struct common_audit_data
*auditdata
)
1144 struct av_decision avd
;
1147 rc
= avc_has_perm_noaudit(ssid
, tsid
, tclass
, requested
, 0, &avd
);
1149 rc2
= avc_audit(ssid
, tsid
, tclass
, requested
, &avd
, rc
, auditdata
);
1155 u32
avc_policy_seqno(void)
1157 return avc_cache
.latest_notif
;
1160 void avc_disable(void)
1163 * If you are looking at this because you have realized that we are
1164 * not destroying the avc_node_cachep it might be easy to fix, but
1165 * I don't know the memory barrier semantics well enough to know. It's
1166 * possible that some other task dereferenced security_ops when
1167 * it still pointed to selinux operations. If that is the case it's
1168 * possible that it is about to use the avc and is about to need the
1169 * avc_node_cachep. I know I could wrap the security.c security_ops call
1170 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1171 * the cache and get that memory back.
1173 if (avc_node_cachep
) {
1175 /* kmem_cache_destroy(avc_node_cachep); */