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