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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);
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 spinlock_t *lock;
621 struct hlist_head *head;
622
623 if (avc_latest_notif_update(avc, avd->seqno, 1))
624 return NULL;
625
626 node = avc_alloc_node(avc);
627 if (!node)
628 return NULL;
629
630 avc_node_populate(node, ssid, tsid, tclass, avd);
631 if (avc_xperms_populate(node, xp_node)) {
632 avc_node_kill(avc, node);
633 return NULL;
634 }
635
636 hvalue = avc_hash(ssid, tsid, tclass);
637 head = &avc->avc_cache.slots[hvalue];
638 lock = &avc->avc_cache.slots_lock[hvalue];
639 spin_lock_irqsave(lock, flag);
640 hlist_for_each_entry(pos, head, list) {
641 if (pos->ae.ssid == ssid &&
642 pos->ae.tsid == tsid &&
643 pos->ae.tclass == tclass) {
644 avc_node_replace(avc, node, pos);
645 goto found;
646 }
647 }
648 hlist_add_head_rcu(&node->list, head);
649found:
650 spin_unlock_irqrestore(lock, flag);
651 return node;
652}
653
654/**
655 * avc_audit_pre_callback - SELinux specific information
656 * will be called by generic audit code
657 * @ab: the audit buffer
658 * @a: audit_data
659 */
660static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
661{
662 struct common_audit_data *ad = a;
663 struct selinux_audit_data *sad = ad->selinux_audit_data;
664 u32 av = sad->audited;
665 const char **perms;
666 int i, perm;
667
668 audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
669
670 if (av == 0) {
671 audit_log_format(ab, " null");
672 return;
673 }
674
675 perms = secclass_map[sad->tclass-1].perms;
676
677 audit_log_format(ab, " {");
678 i = 0;
679 perm = 1;
680 while (i < (sizeof(av) * 8)) {
681 if ((perm & av) && perms[i]) {
682 audit_log_format(ab, " %s", perms[i]);
683 av &= ~perm;
684 }
685 i++;
686 perm <<= 1;
687 }
688
689 if (av)
690 audit_log_format(ab, " 0x%x", av);
691
692 audit_log_format(ab, " } for ");
693}
694
695/**
696 * avc_audit_post_callback - SELinux specific information
697 * will be called by generic audit code
698 * @ab: the audit buffer
699 * @a: audit_data
700 */
701static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
702{
703 struct common_audit_data *ad = a;
704 struct selinux_audit_data *sad = ad->selinux_audit_data;
705 char *scontext;
706 u32 scontext_len;
707 int rc;
708
709 rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
710 &scontext_len);
711 if (rc)
712 audit_log_format(ab, " ssid=%d", sad->ssid);
713 else {
714 audit_log_format(ab, " scontext=%s", scontext);
715 kfree(scontext);
716 }
717
718 rc = security_sid_to_context(sad->state, sad->tsid, &scontext,
719 &scontext_len);
720 if (rc)
721 audit_log_format(ab, " tsid=%d", sad->tsid);
722 else {
723 audit_log_format(ab, " tcontext=%s", scontext);
724 kfree(scontext);
725 }
726
727 audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name);
728
729 if (sad->denied)
730 audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
731
732 /* in case of invalid context report also the actual context string */
733 rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
734 &scontext_len);
735 if (!rc && scontext) {
736 if (scontext_len && scontext[scontext_len - 1] == '\0')
737 scontext_len--;
738 audit_log_format(ab, " srawcon=");
739 audit_log_n_untrustedstring(ab, scontext, scontext_len);
740 kfree(scontext);
741 }
742
743 rc = security_sid_to_context_inval(sad->state, sad->tsid, &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, " trawcon=");
749 audit_log_n_untrustedstring(ab, scontext, scontext_len);
750 kfree(scontext);
751 }
752}
753
754/* This is the slow part of avc audit with big stack footprint */
755noinline int slow_avc_audit(struct selinux_state *state,
756 u32 ssid, u32 tsid, u16 tclass,
757 u32 requested, u32 audited, u32 denied, int result,
758 struct common_audit_data *a)
759{
760 struct common_audit_data stack_data;
761 struct selinux_audit_data sad;
762
763 if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
764 return -EINVAL;
765
766 if (!a) {
767 a = &stack_data;
768 a->type = LSM_AUDIT_DATA_NONE;
769 }
770
771 sad.tclass = tclass;
772 sad.requested = requested;
773 sad.ssid = ssid;
774 sad.tsid = tsid;
775 sad.audited = audited;
776 sad.denied = denied;
777 sad.result = result;
778 sad.state = state;
779
780 a->selinux_audit_data = &sad;
781
782 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
783 return 0;
784}
785
786/**
787 * avc_add_callback - Register a callback for security events.
788 * @callback: callback function
789 * @events: security events
790 *
791 * Register a callback function for events in the set @events.
792 * Returns %0 on success or -%ENOMEM if insufficient memory
793 * exists to add the callback.
794 */
795int __init avc_add_callback(int (*callback)(u32 event), u32 events)
796{
797 struct avc_callback_node *c;
798 int rc = 0;
799
800 c = kmalloc(sizeof(*c), GFP_KERNEL);
801 if (!c) {
802 rc = -ENOMEM;
803 goto out;
804 }
805
806 c->callback = callback;
807 c->events = events;
808 c->next = avc_callbacks;
809 avc_callbacks = c;
810out:
811 return rc;
812}
813
814/**
815 * avc_update_node Update an AVC entry
816 * @event : Updating event
817 * @perms : Permission mask bits
818 * @ssid,@tsid,@tclass : identifier of an AVC entry
819 * @seqno : sequence number when decision was made
820 * @xpd: extended_perms_decision to be added to the node
821 * @flags: the AVC_* flags, e.g. AVC_NONBLOCKING, AVC_EXTENDED_PERMS, or 0.
822 *
823 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
824 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
825 * otherwise, this function updates the AVC entry. The original AVC-entry object
826 * will release later by RCU.
827 */
828static int avc_update_node(struct selinux_avc *avc,
829 u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
830 u32 tsid, u16 tclass, u32 seqno,
831 struct extended_perms_decision *xpd,
832 u32 flags)
833{
834 int hvalue, rc = 0;
835 unsigned long flag;
836 struct avc_node *pos, *node, *orig = NULL;
837 struct hlist_head *head;
838 spinlock_t *lock;
839
840 /*
841 * If we are in a non-blocking code path, e.g. VFS RCU walk,
842 * then we must not add permissions to a cache entry
843 * because we will not audit the denial. Otherwise,
844 * during the subsequent blocking retry (e.g. VFS ref walk), we
845 * will find the permissions already granted in the cache entry
846 * and won't audit anything at all, leading to silent denials in
847 * permissive mode that only appear when in enforcing mode.
848 *
849 * See the corresponding handling of MAY_NOT_BLOCK in avc_audit()
850 * and selinux_inode_permission().
851 */
852 if (flags & AVC_NONBLOCKING)
853 return 0;
854
855 node = avc_alloc_node(avc);
856 if (!node) {
857 rc = -ENOMEM;
858 goto out;
859 }
860
861 /* Lock the target slot */
862 hvalue = avc_hash(ssid, tsid, tclass);
863
864 head = &avc->avc_cache.slots[hvalue];
865 lock = &avc->avc_cache.slots_lock[hvalue];
866
867 spin_lock_irqsave(lock, flag);
868
869 hlist_for_each_entry(pos, head, list) {
870 if (ssid == pos->ae.ssid &&
871 tsid == pos->ae.tsid &&
872 tclass == pos->ae.tclass &&
873 seqno == pos->ae.avd.seqno){
874 orig = pos;
875 break;
876 }
877 }
878
879 if (!orig) {
880 rc = -ENOENT;
881 avc_node_kill(avc, node);
882 goto out_unlock;
883 }
884
885 /*
886 * Copy and replace original node.
887 */
888
889 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
890
891 if (orig->ae.xp_node) {
892 rc = avc_xperms_populate(node, orig->ae.xp_node);
893 if (rc) {
894 avc_node_kill(avc, node);
895 goto out_unlock;
896 }
897 }
898
899 switch (event) {
900 case AVC_CALLBACK_GRANT:
901 node->ae.avd.allowed |= perms;
902 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
903 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
904 break;
905 case AVC_CALLBACK_TRY_REVOKE:
906 case AVC_CALLBACK_REVOKE:
907 node->ae.avd.allowed &= ~perms;
908 break;
909 case AVC_CALLBACK_AUDITALLOW_ENABLE:
910 node->ae.avd.auditallow |= perms;
911 break;
912 case AVC_CALLBACK_AUDITALLOW_DISABLE:
913 node->ae.avd.auditallow &= ~perms;
914 break;
915 case AVC_CALLBACK_AUDITDENY_ENABLE:
916 node->ae.avd.auditdeny |= perms;
917 break;
918 case AVC_CALLBACK_AUDITDENY_DISABLE:
919 node->ae.avd.auditdeny &= ~perms;
920 break;
921 case AVC_CALLBACK_ADD_XPERMS:
922 avc_add_xperms_decision(node, xpd);
923 break;
924 }
925 avc_node_replace(avc, node, orig);
926out_unlock:
927 spin_unlock_irqrestore(lock, flag);
928out:
929 return rc;
930}
931
932/**
933 * avc_flush - Flush the cache
934 */
935static void avc_flush(struct selinux_avc *avc)
936{
937 struct hlist_head *head;
938 struct avc_node *node;
939 spinlock_t *lock;
940 unsigned long flag;
941 int i;
942
943 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
944 head = &avc->avc_cache.slots[i];
945 lock = &avc->avc_cache.slots_lock[i];
946
947 spin_lock_irqsave(lock, flag);
948 /*
949 * With preemptable RCU, the outer spinlock does not
950 * prevent RCU grace periods from ending.
951 */
952 rcu_read_lock();
953 hlist_for_each_entry(node, head, list)
954 avc_node_delete(avc, node);
955 rcu_read_unlock();
956 spin_unlock_irqrestore(lock, flag);
957 }
958}
959
960/**
961 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
962 * @seqno: policy sequence number
963 */
964int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
965{
966 struct avc_callback_node *c;
967 int rc = 0, tmprc;
968
969 avc_flush(avc);
970
971 for (c = avc_callbacks; c; c = c->next) {
972 if (c->events & AVC_CALLBACK_RESET) {
973 tmprc = c->callback(AVC_CALLBACK_RESET);
974 /* save the first error encountered for the return
975 value and continue processing the callbacks */
976 if (!rc)
977 rc = tmprc;
978 }
979 }
980
981 avc_latest_notif_update(avc, seqno, 0);
982 return rc;
983}
984
985/*
986 * Slow-path helper function for avc_has_perm_noaudit,
987 * when the avc_node lookup fails. We get called with
988 * the RCU read lock held, and need to return with it
989 * still held, but drop if for the security compute.
990 *
991 * Don't inline this, since it's the slow-path and just
992 * results in a bigger stack frame.
993 */
994static noinline
995struct avc_node *avc_compute_av(struct selinux_state *state,
996 u32 ssid, u32 tsid,
997 u16 tclass, struct av_decision *avd,
998 struct avc_xperms_node *xp_node)
999{
1000 rcu_read_unlock();
1001 INIT_LIST_HEAD(&xp_node->xpd_head);
1002 security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
1003 rcu_read_lock();
1004 return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
1005}
1006
1007static noinline int avc_denied(struct selinux_state *state,
1008 u32 ssid, u32 tsid,
1009 u16 tclass, u32 requested,
1010 u8 driver, u8 xperm, unsigned int flags,
1011 struct av_decision *avd)
1012{
1013 if (flags & AVC_STRICT)
1014 return -EACCES;
1015
1016 if (enforcing_enabled(state) &&
1017 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1018 return -EACCES;
1019
1020 avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
1021 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1022 return 0;
1023}
1024
1025/*
1026 * The avc extended permissions logic adds an additional 256 bits of
1027 * permissions to an avc node when extended permissions for that node are
1028 * specified in the avtab. If the additional 256 permissions is not adequate,
1029 * as-is the case with ioctls, then multiple may be chained together and the
1030 * driver field is used to specify which set contains the permission.
1031 */
1032int avc_has_extended_perms(struct selinux_state *state,
1033 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1034 u8 driver, u8 xperm, struct common_audit_data *ad)
1035{
1036 struct avc_node *node;
1037 struct av_decision avd;
1038 u32 denied;
1039 struct extended_perms_decision local_xpd;
1040 struct extended_perms_decision *xpd = NULL;
1041 struct extended_perms_data allowed;
1042 struct extended_perms_data auditallow;
1043 struct extended_perms_data dontaudit;
1044 struct avc_xperms_node local_xp_node;
1045 struct avc_xperms_node *xp_node;
1046 int rc = 0, rc2;
1047
1048 xp_node = &local_xp_node;
1049 if (WARN_ON(!requested))
1050 return -EACCES;
1051
1052 rcu_read_lock();
1053
1054 node = avc_lookup(state->avc, ssid, tsid, tclass);
1055 if (unlikely(!node)) {
1056 node = avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
1057 } else {
1058 memcpy(&avd, &node->ae.avd, sizeof(avd));
1059 xp_node = node->ae.xp_node;
1060 }
1061 /* if extended permissions are not defined, only consider av_decision */
1062 if (!xp_node || !xp_node->xp.len)
1063 goto decision;
1064
1065 local_xpd.allowed = &allowed;
1066 local_xpd.auditallow = &auditallow;
1067 local_xpd.dontaudit = &dontaudit;
1068
1069 xpd = avc_xperms_decision_lookup(driver, xp_node);
1070 if (unlikely(!xpd)) {
1071 /*
1072 * Compute the extended_perms_decision only if the driver
1073 * is flagged
1074 */
1075 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1076 avd.allowed &= ~requested;
1077 goto decision;
1078 }
1079 rcu_read_unlock();
1080 security_compute_xperms_decision(state, ssid, tsid, tclass,
1081 driver, &local_xpd);
1082 rcu_read_lock();
1083 avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
1084 driver, xperm, ssid, tsid, tclass, avd.seqno,
1085 &local_xpd, 0);
1086 } else {
1087 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1088 }
1089 xpd = &local_xpd;
1090
1091 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1092 avd.allowed &= ~requested;
1093
1094decision:
1095 denied = requested & ~(avd.allowed);
1096 if (unlikely(denied))
1097 rc = avc_denied(state, ssid, tsid, tclass, requested,
1098 driver, xperm, AVC_EXTENDED_PERMS, &avd);
1099
1100 rcu_read_unlock();
1101
1102 rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
1103 &avd, xpd, xperm, rc, ad);
1104 if (rc2)
1105 return rc2;
1106 return rc;
1107}
1108
1109/**
1110 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1111 * @ssid: source security identifier
1112 * @tsid: target security identifier
1113 * @tclass: target security class
1114 * @requested: requested permissions, interpreted based on @tclass
1115 * @flags: AVC_STRICT, AVC_NONBLOCKING, or 0
1116 * @avd: access vector decisions
1117 *
1118 * Check the AVC to determine whether the @requested permissions are granted
1119 * for the SID pair (@ssid, @tsid), interpreting the permissions
1120 * based on @tclass, and call the security server on a cache miss to obtain
1121 * a new decision and add it to the cache. Return a copy of the decisions
1122 * in @avd. Return %0 if all @requested permissions are granted,
1123 * -%EACCES if any permissions are denied, or another -errno upon
1124 * other errors. This function is typically called by avc_has_perm(),
1125 * but may also be called directly to separate permission checking from
1126 * auditing, e.g. in cases where a lock must be held for the check but
1127 * should be released for the auditing.
1128 */
1129inline int avc_has_perm_noaudit(struct selinux_state *state,
1130 u32 ssid, u32 tsid,
1131 u16 tclass, u32 requested,
1132 unsigned int flags,
1133 struct av_decision *avd)
1134{
1135 struct avc_node *node;
1136 struct avc_xperms_node xp_node;
1137 int rc = 0;
1138 u32 denied;
1139
1140 if (WARN_ON(!requested))
1141 return -EACCES;
1142
1143 rcu_read_lock();
1144
1145 node = avc_lookup(state->avc, ssid, tsid, tclass);
1146 if (unlikely(!node))
1147 node = avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
1148 else
1149 memcpy(avd, &node->ae.avd, sizeof(*avd));
1150
1151 denied = requested & ~(avd->allowed);
1152 if (unlikely(denied))
1153 rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
1154 flags, avd);
1155
1156 rcu_read_unlock();
1157 return rc;
1158}
1159
1160/**
1161 * avc_has_perm - Check permissions and perform any appropriate auditing.
1162 * @ssid: source security identifier
1163 * @tsid: target security identifier
1164 * @tclass: target security class
1165 * @requested: requested permissions, interpreted based on @tclass
1166 * @auditdata: auxiliary audit data
1167 *
1168 * Check the AVC to determine whether the @requested permissions are granted
1169 * for the SID pair (@ssid, @tsid), interpreting the permissions
1170 * based on @tclass, and call the security server on a cache miss to obtain
1171 * a new decision and add it to the cache. Audit the granting or denial of
1172 * permissions in accordance with the policy. Return %0 if all @requested
1173 * permissions are granted, -%EACCES if any permissions are denied, or
1174 * another -errno upon other errors.
1175 */
1176int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
1177 u32 requested, struct common_audit_data *auditdata)
1178{
1179 struct av_decision avd;
1180 int rc, rc2;
1181
1182 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1183 &avd);
1184
1185 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1186 auditdata, 0);
1187 if (rc2)
1188 return rc2;
1189 return rc;
1190}
1191
1192int avc_has_perm_flags(struct selinux_state *state,
1193 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1194 struct common_audit_data *auditdata,
1195 int flags)
1196{
1197 struct av_decision avd;
1198 int rc, rc2;
1199
1200 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested,
1201 (flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 0,
1202 &avd);
1203
1204 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1205 auditdata, flags);
1206 if (rc2)
1207 return rc2;
1208 return rc;
1209}
1210
1211u32 avc_policy_seqno(struct selinux_state *state)
1212{
1213 return state->avc->avc_cache.latest_notif;
1214}
1215
1216void avc_disable(void)
1217{
1218 /*
1219 * If you are looking at this because you have realized that we are
1220 * not destroying the avc_node_cachep it might be easy to fix, but
1221 * I don't know the memory barrier semantics well enough to know. It's
1222 * possible that some other task dereferenced security_ops when
1223 * it still pointed to selinux operations. If that is the case it's
1224 * possible that it is about to use the avc and is about to need the
1225 * avc_node_cachep. I know I could wrap the security.c security_ops call
1226 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1227 * the cache and get that memory back.
1228 */
1229 if (avc_node_cachep) {
1230 avc_flush(selinux_state.avc);
1231 /* kmem_cache_destroy(avc_node_cachep); */
1232 }
1233}
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);
69 u32 events;
70 struct avc_callback_node *next;
71};
72
73/* Exported via selinufs */
74unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
75
76#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
77DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
78#endif
79
80static struct avc_cache avc_cache;
81static struct avc_callback_node *avc_callbacks;
82static struct kmem_cache *avc_node_cachep;
83
84static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
85{
86 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
87}
88
89/**
90 * avc_dump_av - Display an access vector in human-readable form.
91 * @tclass: target security class
92 * @av: access vector
93 */
94static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
95{
96 const char **perms;
97 int i, perm;
98
99 if (av == 0) {
100 audit_log_format(ab, " null");
101 return;
102 }
103
104 perms = secclass_map[tclass-1].perms;
105
106 audit_log_format(ab, " {");
107 i = 0;
108 perm = 1;
109 while (i < (sizeof(av) * 8)) {
110 if ((perm & av) && perms[i]) {
111 audit_log_format(ab, " %s", perms[i]);
112 av &= ~perm;
113 }
114 i++;
115 perm <<= 1;
116 }
117
118 if (av)
119 audit_log_format(ab, " 0x%x", av);
120
121 audit_log_format(ab, " }");
122}
123
124/**
125 * avc_dump_query - Display a SID pair and a class in human-readable form.
126 * @ssid: source security identifier
127 * @tsid: target security identifier
128 * @tclass: target security class
129 */
130static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
131{
132 int rc;
133 char *scontext;
134 u32 scontext_len;
135
136 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
137 if (rc)
138 audit_log_format(ab, "ssid=%d", ssid);
139 else {
140 audit_log_format(ab, "scontext=%s", scontext);
141 kfree(scontext);
142 }
143
144 rc = security_sid_to_context(tsid, &scontext, &scontext_len);
145 if (rc)
146 audit_log_format(ab, " tsid=%d", tsid);
147 else {
148 audit_log_format(ab, " tcontext=%s", scontext);
149 kfree(scontext);
150 }
151
152 BUG_ON(tclass >= ARRAY_SIZE(secclass_map));
153 audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
154}
155
156/**
157 * avc_init - Initialize the AVC.
158 *
159 * Initialize the access vector cache.
160 */
161void __init avc_init(void)
162{
163 int i;
164
165 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
166 INIT_HLIST_HEAD(&avc_cache.slots[i]);
167 spin_lock_init(&avc_cache.slots_lock[i]);
168 }
169 atomic_set(&avc_cache.active_nodes, 0);
170 atomic_set(&avc_cache.lru_hint, 0);
171
172 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
173 0, SLAB_PANIC, NULL);
174
175 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
176}
177
178int avc_get_hash_stats(char *page)
179{
180 int i, chain_len, max_chain_len, slots_used;
181 struct avc_node *node;
182 struct hlist_head *head;
183
184 rcu_read_lock();
185
186 slots_used = 0;
187 max_chain_len = 0;
188 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
189 head = &avc_cache.slots[i];
190 if (!hlist_empty(head)) {
191 struct hlist_node *next;
192
193 slots_used++;
194 chain_len = 0;
195 hlist_for_each_entry_rcu(node, next, head, list)
196 chain_len++;
197 if (chain_len > max_chain_len)
198 max_chain_len = chain_len;
199 }
200 }
201
202 rcu_read_unlock();
203
204 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
205 "longest chain: %d\n",
206 atomic_read(&avc_cache.active_nodes),
207 slots_used, AVC_CACHE_SLOTS, max_chain_len);
208}
209
210static void avc_node_free(struct rcu_head *rhead)
211{
212 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
213 kmem_cache_free(avc_node_cachep, node);
214 avc_cache_stats_incr(frees);
215}
216
217static void avc_node_delete(struct avc_node *node)
218{
219 hlist_del_rcu(&node->list);
220 call_rcu(&node->rhead, avc_node_free);
221 atomic_dec(&avc_cache.active_nodes);
222}
223
224static void avc_node_kill(struct avc_node *node)
225{
226 kmem_cache_free(avc_node_cachep, node);
227 avc_cache_stats_incr(frees);
228 atomic_dec(&avc_cache.active_nodes);
229}
230
231static void avc_node_replace(struct avc_node *new, struct avc_node *old)
232{
233 hlist_replace_rcu(&old->list, &new->list);
234 call_rcu(&old->rhead, avc_node_free);
235 atomic_dec(&avc_cache.active_nodes);
236}
237
238static inline int avc_reclaim_node(void)
239{
240 struct avc_node *node;
241 int hvalue, try, ecx;
242 unsigned long flags;
243 struct hlist_head *head;
244 struct hlist_node *next;
245 spinlock_t *lock;
246
247 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
248 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
249 head = &avc_cache.slots[hvalue];
250 lock = &avc_cache.slots_lock[hvalue];
251
252 if (!spin_trylock_irqsave(lock, flags))
253 continue;
254
255 rcu_read_lock();
256 hlist_for_each_entry(node, next, head, list) {
257 avc_node_delete(node);
258 avc_cache_stats_incr(reclaims);
259 ecx++;
260 if (ecx >= AVC_CACHE_RECLAIM) {
261 rcu_read_unlock();
262 spin_unlock_irqrestore(lock, flags);
263 goto out;
264 }
265 }
266 rcu_read_unlock();
267 spin_unlock_irqrestore(lock, flags);
268 }
269out:
270 return ecx;
271}
272
273static struct avc_node *avc_alloc_node(void)
274{
275 struct avc_node *node;
276
277 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
278 if (!node)
279 goto out;
280
281 INIT_HLIST_NODE(&node->list);
282 avc_cache_stats_incr(allocations);
283
284 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
285 avc_reclaim_node();
286
287out:
288 return node;
289}
290
291static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
292{
293 node->ae.ssid = ssid;
294 node->ae.tsid = tsid;
295 node->ae.tclass = tclass;
296 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
297}
298
299static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
300{
301 struct avc_node *node, *ret = NULL;
302 int hvalue;
303 struct hlist_head *head;
304 struct hlist_node *next;
305
306 hvalue = avc_hash(ssid, tsid, tclass);
307 head = &avc_cache.slots[hvalue];
308 hlist_for_each_entry_rcu(node, next, head, list) {
309 if (ssid == node->ae.ssid &&
310 tclass == node->ae.tclass &&
311 tsid == node->ae.tsid) {
312 ret = node;
313 break;
314 }
315 }
316
317 return ret;
318}
319
320/**
321 * avc_lookup - Look up an AVC entry.
322 * @ssid: source security identifier
323 * @tsid: target security identifier
324 * @tclass: target security class
325 *
326 * Look up an AVC entry that is valid for the
327 * (@ssid, @tsid), interpreting the permissions
328 * based on @tclass. If a valid AVC entry exists,
329 * then this function returns the avc_node.
330 * Otherwise, this function returns NULL.
331 */
332static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
333{
334 struct avc_node *node;
335
336 avc_cache_stats_incr(lookups);
337 node = avc_search_node(ssid, tsid, tclass);
338
339 if (node)
340 return node;
341
342 avc_cache_stats_incr(misses);
343 return NULL;
344}
345
346static int avc_latest_notif_update(int seqno, int is_insert)
347{
348 int ret = 0;
349 static DEFINE_SPINLOCK(notif_lock);
350 unsigned long flag;
351
352 spin_lock_irqsave(¬if_lock, flag);
353 if (is_insert) {
354 if (seqno < avc_cache.latest_notif) {
355 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
356 seqno, avc_cache.latest_notif);
357 ret = -EAGAIN;
358 }
359 } else {
360 if (seqno > avc_cache.latest_notif)
361 avc_cache.latest_notif = seqno;
362 }
363 spin_unlock_irqrestore(¬if_lock, flag);
364
365 return ret;
366}
367
368/**
369 * avc_insert - Insert an AVC entry.
370 * @ssid: source security identifier
371 * @tsid: target security identifier
372 * @tclass: target security class
373 * @avd: resulting av decision
374 *
375 * Insert an AVC entry for the SID pair
376 * (@ssid, @tsid) and class @tclass.
377 * The access vectors and the sequence number are
378 * normally provided by the security server in
379 * response to a security_compute_av() call. If the
380 * sequence number @avd->seqno is not less than the latest
381 * revocation notification, then the function copies
382 * the access vectors into a cache entry, returns
383 * avc_node inserted. Otherwise, this function returns NULL.
384 */
385static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
386{
387 struct avc_node *pos, *node = NULL;
388 int hvalue;
389 unsigned long flag;
390
391 if (avc_latest_notif_update(avd->seqno, 1))
392 goto out;
393
394 node = avc_alloc_node();
395 if (node) {
396 struct hlist_head *head;
397 struct hlist_node *next;
398 spinlock_t *lock;
399
400 hvalue = avc_hash(ssid, tsid, tclass);
401 avc_node_populate(node, ssid, tsid, tclass, avd);
402
403 head = &avc_cache.slots[hvalue];
404 lock = &avc_cache.slots_lock[hvalue];
405
406 spin_lock_irqsave(lock, flag);
407 hlist_for_each_entry(pos, next, head, list) {
408 if (pos->ae.ssid == ssid &&
409 pos->ae.tsid == tsid &&
410 pos->ae.tclass == tclass) {
411 avc_node_replace(node, pos);
412 goto found;
413 }
414 }
415 hlist_add_head_rcu(&node->list, head);
416found:
417 spin_unlock_irqrestore(lock, flag);
418 }
419out:
420 return node;
421}
422
423/**
424 * avc_audit_pre_callback - SELinux specific information
425 * will be called by generic audit code
426 * @ab: the audit buffer
427 * @a: audit_data
428 */
429static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
430{
431 struct common_audit_data *ad = a;
432 audit_log_format(ab, "avc: %s ",
433 ad->selinux_audit_data->denied ? "denied" : "granted");
434 avc_dump_av(ab, ad->selinux_audit_data->tclass,
435 ad->selinux_audit_data->audited);
436 audit_log_format(ab, " for ");
437}
438
439/**
440 * avc_audit_post_callback - SELinux specific information
441 * will be called by generic audit code
442 * @ab: the audit buffer
443 * @a: audit_data
444 */
445static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
446{
447 struct common_audit_data *ad = a;
448 audit_log_format(ab, " ");
449 avc_dump_query(ab, ad->selinux_audit_data->ssid,
450 ad->selinux_audit_data->tsid,
451 ad->selinux_audit_data->tclass);
452}
453
454/* This is the slow part of avc audit with big stack footprint */
455noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
456 u32 requested, u32 audited, u32 denied,
457 struct common_audit_data *a,
458 unsigned flags)
459{
460 struct common_audit_data stack_data;
461 struct selinux_audit_data sad;
462
463 if (!a) {
464 a = &stack_data;
465 a->type = LSM_AUDIT_DATA_NONE;
466 }
467
468 /*
469 * When in a RCU walk do the audit on the RCU retry. This is because
470 * the collection of the dname in an inode audit message is not RCU
471 * safe. Note this may drop some audits when the situation changes
472 * during retry. However this is logically just as if the operation
473 * happened a little later.
474 */
475 if ((a->type == LSM_AUDIT_DATA_INODE) &&
476 (flags & MAY_NOT_BLOCK))
477 return -ECHILD;
478
479 sad.tclass = tclass;
480 sad.requested = requested;
481 sad.ssid = ssid;
482 sad.tsid = tsid;
483 sad.audited = audited;
484 sad.denied = denied;
485
486 a->selinux_audit_data = &sad;
487
488 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
489 return 0;
490}
491
492/**
493 * avc_add_callback - Register a callback for security events.
494 * @callback: callback function
495 * @events: security events
496 *
497 * Register a callback function for events in the set @events.
498 * Returns %0 on success or -%ENOMEM if insufficient memory
499 * exists to add the callback.
500 */
501int __init avc_add_callback(int (*callback)(u32 event), u32 events)
502{
503 struct avc_callback_node *c;
504 int rc = 0;
505
506 c = kmalloc(sizeof(*c), GFP_KERNEL);
507 if (!c) {
508 rc = -ENOMEM;
509 goto out;
510 }
511
512 c->callback = callback;
513 c->events = events;
514 c->next = avc_callbacks;
515 avc_callbacks = c;
516out:
517 return rc;
518}
519
520static inline int avc_sidcmp(u32 x, u32 y)
521{
522 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
523}
524
525/**
526 * avc_update_node Update an AVC entry
527 * @event : Updating event
528 * @perms : Permission mask bits
529 * @ssid,@tsid,@tclass : identifier of an AVC entry
530 * @seqno : sequence number when decision was made
531 *
532 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
533 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
534 * otherwise, this function updates the AVC entry. The original AVC-entry object
535 * will release later by RCU.
536 */
537static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
538 u32 seqno)
539{
540 int hvalue, rc = 0;
541 unsigned long flag;
542 struct avc_node *pos, *node, *orig = NULL;
543 struct hlist_head *head;
544 struct hlist_node *next;
545 spinlock_t *lock;
546
547 node = avc_alloc_node();
548 if (!node) {
549 rc = -ENOMEM;
550 goto out;
551 }
552
553 /* Lock the target slot */
554 hvalue = avc_hash(ssid, tsid, tclass);
555
556 head = &avc_cache.slots[hvalue];
557 lock = &avc_cache.slots_lock[hvalue];
558
559 spin_lock_irqsave(lock, flag);
560
561 hlist_for_each_entry(pos, next, head, list) {
562 if (ssid == pos->ae.ssid &&
563 tsid == pos->ae.tsid &&
564 tclass == pos->ae.tclass &&
565 seqno == pos->ae.avd.seqno){
566 orig = pos;
567 break;
568 }
569 }
570
571 if (!orig) {
572 rc = -ENOENT;
573 avc_node_kill(node);
574 goto out_unlock;
575 }
576
577 /*
578 * Copy and replace original node.
579 */
580
581 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
582
583 switch (event) {
584 case AVC_CALLBACK_GRANT:
585 node->ae.avd.allowed |= perms;
586 break;
587 case AVC_CALLBACK_TRY_REVOKE:
588 case AVC_CALLBACK_REVOKE:
589 node->ae.avd.allowed &= ~perms;
590 break;
591 case AVC_CALLBACK_AUDITALLOW_ENABLE:
592 node->ae.avd.auditallow |= perms;
593 break;
594 case AVC_CALLBACK_AUDITALLOW_DISABLE:
595 node->ae.avd.auditallow &= ~perms;
596 break;
597 case AVC_CALLBACK_AUDITDENY_ENABLE:
598 node->ae.avd.auditdeny |= perms;
599 break;
600 case AVC_CALLBACK_AUDITDENY_DISABLE:
601 node->ae.avd.auditdeny &= ~perms;
602 break;
603 }
604 avc_node_replace(node, orig);
605out_unlock:
606 spin_unlock_irqrestore(lock, flag);
607out:
608 return rc;
609}
610
611/**
612 * avc_flush - Flush the cache
613 */
614static void avc_flush(void)
615{
616 struct hlist_head *head;
617 struct hlist_node *next;
618 struct avc_node *node;
619 spinlock_t *lock;
620 unsigned long flag;
621 int i;
622
623 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
624 head = &avc_cache.slots[i];
625 lock = &avc_cache.slots_lock[i];
626
627 spin_lock_irqsave(lock, flag);
628 /*
629 * With preemptable RCU, the outer spinlock does not
630 * prevent RCU grace periods from ending.
631 */
632 rcu_read_lock();
633 hlist_for_each_entry(node, next, head, list)
634 avc_node_delete(node);
635 rcu_read_unlock();
636 spin_unlock_irqrestore(lock, flag);
637 }
638}
639
640/**
641 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
642 * @seqno: policy sequence number
643 */
644int avc_ss_reset(u32 seqno)
645{
646 struct avc_callback_node *c;
647 int rc = 0, tmprc;
648
649 avc_flush();
650
651 for (c = avc_callbacks; c; c = c->next) {
652 if (c->events & AVC_CALLBACK_RESET) {
653 tmprc = c->callback(AVC_CALLBACK_RESET);
654 /* save the first error encountered for the return
655 value and continue processing the callbacks */
656 if (!rc)
657 rc = tmprc;
658 }
659 }
660
661 avc_latest_notif_update(seqno, 0);
662 return rc;
663}
664
665/*
666 * Slow-path helper function for avc_has_perm_noaudit,
667 * when the avc_node lookup fails. We get called with
668 * the RCU read lock held, and need to return with it
669 * still held, but drop if for the security compute.
670 *
671 * Don't inline this, since it's the slow-path and just
672 * results in a bigger stack frame.
673 */
674static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid,
675 u16 tclass, struct av_decision *avd)
676{
677 rcu_read_unlock();
678 security_compute_av(ssid, tsid, tclass, avd);
679 rcu_read_lock();
680 return avc_insert(ssid, tsid, tclass, avd);
681}
682
683static noinline int avc_denied(u32 ssid, u32 tsid,
684 u16 tclass, u32 requested,
685 unsigned flags,
686 struct av_decision *avd)
687{
688 if (flags & AVC_STRICT)
689 return -EACCES;
690
691 if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE))
692 return -EACCES;
693
694 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
695 tsid, tclass, avd->seqno);
696 return 0;
697}
698
699
700/**
701 * avc_has_perm_noaudit - Check permissions but perform no auditing.
702 * @ssid: source security identifier
703 * @tsid: target security identifier
704 * @tclass: target security class
705 * @requested: requested permissions, interpreted based on @tclass
706 * @flags: AVC_STRICT or 0
707 * @avd: access vector decisions
708 *
709 * Check the AVC to determine whether the @requested permissions are granted
710 * for the SID pair (@ssid, @tsid), interpreting the permissions
711 * based on @tclass, and call the security server on a cache miss to obtain
712 * a new decision and add it to the cache. Return a copy of the decisions
713 * in @avd. Return %0 if all @requested permissions are granted,
714 * -%EACCES if any permissions are denied, or another -errno upon
715 * other errors. This function is typically called by avc_has_perm(),
716 * but may also be called directly to separate permission checking from
717 * auditing, e.g. in cases where a lock must be held for the check but
718 * should be released for the auditing.
719 */
720inline int avc_has_perm_noaudit(u32 ssid, u32 tsid,
721 u16 tclass, u32 requested,
722 unsigned flags,
723 struct av_decision *avd)
724{
725 struct avc_node *node;
726 int rc = 0;
727 u32 denied;
728
729 BUG_ON(!requested);
730
731 rcu_read_lock();
732
733 node = avc_lookup(ssid, tsid, tclass);
734 if (unlikely(!node)) {
735 node = avc_compute_av(ssid, tsid, tclass, avd);
736 } else {
737 memcpy(avd, &node->ae.avd, sizeof(*avd));
738 avd = &node->ae.avd;
739 }
740
741 denied = requested & ~(avd->allowed);
742 if (unlikely(denied))
743 rc = avc_denied(ssid, tsid, tclass, requested, flags, avd);
744
745 rcu_read_unlock();
746 return rc;
747}
748
749/**
750 * avc_has_perm - Check permissions and perform any appropriate auditing.
751 * @ssid: source security identifier
752 * @tsid: target security identifier
753 * @tclass: target security class
754 * @requested: requested permissions, interpreted based on @tclass
755 * @auditdata: auxiliary audit data
756 * @flags: VFS walk flags
757 *
758 * Check the AVC to determine whether the @requested permissions are granted
759 * for the SID pair (@ssid, @tsid), interpreting the permissions
760 * based on @tclass, and call the security server on a cache miss to obtain
761 * a new decision and add it to the cache. Audit the granting or denial of
762 * permissions in accordance with the policy. Return %0 if all @requested
763 * permissions are granted, -%EACCES if any permissions are denied, or
764 * another -errno upon other errors.
765 */
766int avc_has_perm_flags(u32 ssid, u32 tsid, u16 tclass,
767 u32 requested, struct common_audit_data *auditdata,
768 unsigned flags)
769{
770 struct av_decision avd;
771 int rc, rc2;
772
773 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
774
775 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata,
776 flags);
777 if (rc2)
778 return rc2;
779 return rc;
780}
781
782u32 avc_policy_seqno(void)
783{
784 return avc_cache.latest_notif;
785}
786
787void avc_disable(void)
788{
789 /*
790 * If you are looking at this because you have realized that we are
791 * not destroying the avc_node_cachep it might be easy to fix, but
792 * I don't know the memory barrier semantics well enough to know. It's
793 * possible that some other task dereferenced security_ops when
794 * it still pointed to selinux operations. If that is the case it's
795 * possible that it is about to use the avc and is about to need the
796 * avc_node_cachep. I know I could wrap the security.c security_ops call
797 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
798 * the cache and get that memory back.
799 */
800 if (avc_node_cachep) {
801 avc_flush();
802 /* kmem_cache_destroy(avc_node_cachep); */
803 }
804}