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