Loading...
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Implementation of the kernel access vector cache (AVC).
4 *
5 * Authors: Stephen Smalley, <stephen.smalley.work@gmail.com>
6 * James Morris <jmorris@redhat.com>
7 *
8 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
9 * Replaced the avc_lock spinlock by RCU.
10 *
11 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
12 */
13#include <linux/types.h>
14#include <linux/stddef.h>
15#include <linux/kernel.h>
16#include <linux/slab.h>
17#include <linux/fs.h>
18#include <linux/dcache.h>
19#include <linux/init.h>
20#include <linux/skbuff.h>
21#include <linux/percpu.h>
22#include <linux/list.h>
23#include <net/sock.h>
24#include <linux/un.h>
25#include <net/af_unix.h>
26#include <linux/ip.h>
27#include <linux/audit.h>
28#include <linux/ipv6.h>
29#include <net/ipv6.h>
30#include "avc.h"
31#include "avc_ss.h"
32#include "classmap.h"
33
34#define CREATE_TRACE_POINTS
35#include <trace/events/avc.h>
36
37#define AVC_CACHE_SLOTS 512
38#define AVC_DEF_CACHE_THRESHOLD 512
39#define AVC_CACHE_RECLAIM 16
40
41#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
42#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
43#else
44#define avc_cache_stats_incr(field) do {} while (0)
45#endif
46
47struct avc_entry {
48 u32 ssid;
49 u32 tsid;
50 u16 tclass;
51 struct av_decision avd;
52 struct avc_xperms_node *xp_node;
53};
54
55struct avc_node {
56 struct avc_entry ae;
57 struct hlist_node list; /* anchored in avc_cache->slots[i] */
58 struct rcu_head rhead;
59};
60
61struct avc_xperms_decision_node {
62 struct extended_perms_decision xpd;
63 struct list_head xpd_list; /* list of extended_perms_decision */
64};
65
66struct avc_xperms_node {
67 struct extended_perms xp;
68 struct list_head xpd_head; /* list head of extended_perms_decision */
69};
70
71struct avc_cache {
72 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
73 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
74 atomic_t lru_hint; /* LRU hint for reclaim scan */
75 atomic_t active_nodes;
76 u32 latest_notif; /* latest revocation notification */
77};
78
79struct avc_callback_node {
80 int (*callback) (u32 event);
81 u32 events;
82 struct avc_callback_node *next;
83};
84
85#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
86DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
87#endif
88
89struct selinux_avc {
90 unsigned int avc_cache_threshold;
91 struct avc_cache avc_cache;
92};
93
94static struct selinux_avc selinux_avc;
95
96void selinux_avc_init(void)
97{
98 int i;
99
100 selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
101 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
102 INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
103 spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
104 }
105 atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
106 atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
107}
108
109unsigned int avc_get_cache_threshold(void)
110{
111 return selinux_avc.avc_cache_threshold;
112}
113
114void avc_set_cache_threshold(unsigned int cache_threshold)
115{
116 selinux_avc.avc_cache_threshold = cache_threshold;
117}
118
119static struct avc_callback_node *avc_callbacks __ro_after_init;
120static struct kmem_cache *avc_node_cachep __ro_after_init;
121static struct kmem_cache *avc_xperms_data_cachep __ro_after_init;
122static struct kmem_cache *avc_xperms_decision_cachep __ro_after_init;
123static struct kmem_cache *avc_xperms_cachep __ro_after_init;
124
125static inline u32 avc_hash(u32 ssid, u32 tsid, u16 tclass)
126{
127 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
128}
129
130/**
131 * avc_init - Initialize the AVC.
132 *
133 * Initialize the access vector cache.
134 */
135void __init avc_init(void)
136{
137 avc_node_cachep = KMEM_CACHE(avc_node, SLAB_PANIC);
138 avc_xperms_cachep = KMEM_CACHE(avc_xperms_node, SLAB_PANIC);
139 avc_xperms_decision_cachep = KMEM_CACHE(avc_xperms_decision_node, SLAB_PANIC);
140 avc_xperms_data_cachep = KMEM_CACHE(extended_perms_data, SLAB_PANIC);
141}
142
143int avc_get_hash_stats(char *page)
144{
145 int i, chain_len, max_chain_len, slots_used;
146 struct avc_node *node;
147 struct hlist_head *head;
148
149 rcu_read_lock();
150
151 slots_used = 0;
152 max_chain_len = 0;
153 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
154 head = &selinux_avc.avc_cache.slots[i];
155 if (!hlist_empty(head)) {
156 slots_used++;
157 chain_len = 0;
158 hlist_for_each_entry_rcu(node, head, list)
159 chain_len++;
160 if (chain_len > max_chain_len)
161 max_chain_len = chain_len;
162 }
163 }
164
165 rcu_read_unlock();
166
167 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
168 "longest chain: %d\n",
169 atomic_read(&selinux_avc.avc_cache.active_nodes),
170 slots_used, AVC_CACHE_SLOTS, max_chain_len);
171}
172
173/*
174 * using a linked list for extended_perms_decision lookup because the list is
175 * always small. i.e. less than 5, typically 1
176 */
177static struct extended_perms_decision *
178avc_xperms_decision_lookup(u8 driver, u8 base_perm,
179 struct avc_xperms_node *xp_node)
180{
181 struct avc_xperms_decision_node *xpd_node;
182
183 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
184 if (xpd_node->xpd.driver == driver &&
185 xpd_node->xpd.base_perm == base_perm)
186 return &xpd_node->xpd;
187 }
188 return NULL;
189}
190
191static inline unsigned int
192avc_xperms_has_perm(struct extended_perms_decision *xpd,
193 u8 perm, u8 which)
194{
195 unsigned int rc = 0;
196
197 if ((which == XPERMS_ALLOWED) &&
198 (xpd->used & XPERMS_ALLOWED))
199 rc = security_xperm_test(xpd->allowed->p, perm);
200 else if ((which == XPERMS_AUDITALLOW) &&
201 (xpd->used & XPERMS_AUDITALLOW))
202 rc = security_xperm_test(xpd->auditallow->p, perm);
203 else if ((which == XPERMS_DONTAUDIT) &&
204 (xpd->used & XPERMS_DONTAUDIT))
205 rc = security_xperm_test(xpd->dontaudit->p, perm);
206 return rc;
207}
208
209static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
210 u8 driver, u8 base_perm, u8 perm)
211{
212 struct extended_perms_decision *xpd;
213 security_xperm_set(xp_node->xp.drivers.p, driver);
214 xp_node->xp.base_perms |= base_perm;
215 xpd = avc_xperms_decision_lookup(driver, base_perm, xp_node);
216 if (xpd && xpd->allowed)
217 security_xperm_set(xpd->allowed->p, perm);
218}
219
220static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
221{
222 struct extended_perms_decision *xpd;
223
224 xpd = &xpd_node->xpd;
225 if (xpd->allowed)
226 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
227 if (xpd->auditallow)
228 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
229 if (xpd->dontaudit)
230 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
231 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
232}
233
234static void avc_xperms_free(struct avc_xperms_node *xp_node)
235{
236 struct avc_xperms_decision_node *xpd_node, *tmp;
237
238 if (!xp_node)
239 return;
240
241 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
242 list_del(&xpd_node->xpd_list);
243 avc_xperms_decision_free(xpd_node);
244 }
245 kmem_cache_free(avc_xperms_cachep, xp_node);
246}
247
248static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
249 struct extended_perms_decision *src)
250{
251 dest->base_perm = src->base_perm;
252 dest->driver = src->driver;
253 dest->used = src->used;
254 if (dest->used & XPERMS_ALLOWED)
255 memcpy(dest->allowed->p, src->allowed->p,
256 sizeof(src->allowed->p));
257 if (dest->used & XPERMS_AUDITALLOW)
258 memcpy(dest->auditallow->p, src->auditallow->p,
259 sizeof(src->auditallow->p));
260 if (dest->used & XPERMS_DONTAUDIT)
261 memcpy(dest->dontaudit->p, src->dontaudit->p,
262 sizeof(src->dontaudit->p));
263}
264
265/*
266 * similar to avc_copy_xperms_decision, but only copy decision
267 * information relevant to this perm
268 */
269static inline void avc_quick_copy_xperms_decision(u8 perm,
270 struct extended_perms_decision *dest,
271 struct extended_perms_decision *src)
272{
273 /*
274 * compute index of the u32 of the 256 bits (8 u32s) that contain this
275 * command permission
276 */
277 u8 i = perm >> 5;
278
279 dest->base_perm = src->base_perm;
280 dest->used = src->used;
281 if (dest->used & XPERMS_ALLOWED)
282 dest->allowed->p[i] = src->allowed->p[i];
283 if (dest->used & XPERMS_AUDITALLOW)
284 dest->auditallow->p[i] = src->auditallow->p[i];
285 if (dest->used & XPERMS_DONTAUDIT)
286 dest->dontaudit->p[i] = src->dontaudit->p[i];
287}
288
289static struct avc_xperms_decision_node
290 *avc_xperms_decision_alloc(u8 which)
291{
292 struct avc_xperms_decision_node *xpd_node;
293 struct extended_perms_decision *xpd;
294
295 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
296 GFP_NOWAIT | __GFP_NOWARN);
297 if (!xpd_node)
298 return NULL;
299
300 xpd = &xpd_node->xpd;
301 if (which & XPERMS_ALLOWED) {
302 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
303 GFP_NOWAIT | __GFP_NOWARN);
304 if (!xpd->allowed)
305 goto error;
306 }
307 if (which & XPERMS_AUDITALLOW) {
308 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
309 GFP_NOWAIT | __GFP_NOWARN);
310 if (!xpd->auditallow)
311 goto error;
312 }
313 if (which & XPERMS_DONTAUDIT) {
314 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
315 GFP_NOWAIT | __GFP_NOWARN);
316 if (!xpd->dontaudit)
317 goto error;
318 }
319 return xpd_node;
320error:
321 avc_xperms_decision_free(xpd_node);
322 return NULL;
323}
324
325static int avc_add_xperms_decision(struct avc_node *node,
326 struct extended_perms_decision *src)
327{
328 struct avc_xperms_decision_node *dest_xpd;
329
330 dest_xpd = avc_xperms_decision_alloc(src->used);
331 if (!dest_xpd)
332 return -ENOMEM;
333 avc_copy_xperms_decision(&dest_xpd->xpd, src);
334 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
335 node->ae.xp_node->xp.len++;
336 return 0;
337}
338
339static struct avc_xperms_node *avc_xperms_alloc(void)
340{
341 struct avc_xperms_node *xp_node;
342
343 xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT | __GFP_NOWARN);
344 if (!xp_node)
345 return xp_node;
346 INIT_LIST_HEAD(&xp_node->xpd_head);
347 return xp_node;
348}
349
350static int avc_xperms_populate(struct avc_node *node,
351 struct avc_xperms_node *src)
352{
353 struct avc_xperms_node *dest;
354 struct avc_xperms_decision_node *dest_xpd;
355 struct avc_xperms_decision_node *src_xpd;
356
357 if (src->xp.len == 0)
358 return 0;
359 dest = avc_xperms_alloc();
360 if (!dest)
361 return -ENOMEM;
362
363 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
364 dest->xp.len = src->xp.len;
365 dest->xp.base_perms = src->xp.base_perms;
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 = 0;
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 = 0;
406 }
407 }
408
409 *deniedp = denied;
410 return audited;
411}
412
413static inline int avc_xperms_audit(u32 ssid, u32 tsid, u16 tclass,
414 u32 requested, struct av_decision *avd,
415 struct extended_perms_decision *xpd,
416 u8 perm, int result,
417 struct common_audit_data *ad)
418{
419 u32 audited, denied;
420
421 audited = avc_xperms_audit_required(
422 requested, avd, xpd, perm, result, &denied);
423 if (likely(!audited))
424 return 0;
425 return slow_avc_audit(ssid, tsid, tclass, requested,
426 audited, denied, result, ad);
427}
428
429static void avc_node_free(struct rcu_head *rhead)
430{
431 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
432 avc_xperms_free(node->ae.xp_node);
433 kmem_cache_free(avc_node_cachep, node);
434 avc_cache_stats_incr(frees);
435}
436
437static void avc_node_delete(struct avc_node *node)
438{
439 hlist_del_rcu(&node->list);
440 call_rcu(&node->rhead, avc_node_free);
441 atomic_dec(&selinux_avc.avc_cache.active_nodes);
442}
443
444static void avc_node_kill(struct avc_node *node)
445{
446 avc_xperms_free(node->ae.xp_node);
447 kmem_cache_free(avc_node_cachep, node);
448 avc_cache_stats_incr(frees);
449 atomic_dec(&selinux_avc.avc_cache.active_nodes);
450}
451
452static void avc_node_replace(struct avc_node *new, struct avc_node *old)
453{
454 hlist_replace_rcu(&old->list, &new->list);
455 call_rcu(&old->rhead, avc_node_free);
456 atomic_dec(&selinux_avc.avc_cache.active_nodes);
457}
458
459static inline int avc_reclaim_node(void)
460{
461 struct avc_node *node;
462 int hvalue, try, ecx;
463 unsigned long flags;
464 struct hlist_head *head;
465 spinlock_t *lock;
466
467 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
468 hvalue = atomic_inc_return(&selinux_avc.avc_cache.lru_hint) &
469 (AVC_CACHE_SLOTS - 1);
470 head = &selinux_avc.avc_cache.slots[hvalue];
471 lock = &selinux_avc.avc_cache.slots_lock[hvalue];
472
473 if (!spin_trylock_irqsave(lock, flags))
474 continue;
475
476 rcu_read_lock();
477 hlist_for_each_entry(node, head, list) {
478 avc_node_delete(node);
479 avc_cache_stats_incr(reclaims);
480 ecx++;
481 if (ecx >= AVC_CACHE_RECLAIM) {
482 rcu_read_unlock();
483 spin_unlock_irqrestore(lock, flags);
484 goto out;
485 }
486 }
487 rcu_read_unlock();
488 spin_unlock_irqrestore(lock, flags);
489 }
490out:
491 return ecx;
492}
493
494static struct avc_node *avc_alloc_node(void)
495{
496 struct avc_node *node;
497
498 node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN);
499 if (!node)
500 goto out;
501
502 INIT_HLIST_NODE(&node->list);
503 avc_cache_stats_incr(allocations);
504
505 if (atomic_inc_return(&selinux_avc.avc_cache.active_nodes) >
506 selinux_avc.avc_cache_threshold)
507 avc_reclaim_node();
508
509out:
510 return node;
511}
512
513static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
514{
515 node->ae.ssid = ssid;
516 node->ae.tsid = tsid;
517 node->ae.tclass = tclass;
518 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
519}
520
521static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
522{
523 struct avc_node *node, *ret = NULL;
524 u32 hvalue;
525 struct hlist_head *head;
526
527 hvalue = avc_hash(ssid, tsid, tclass);
528 head = &selinux_avc.avc_cache.slots[hvalue];
529 hlist_for_each_entry_rcu(node, head, list) {
530 if (ssid == node->ae.ssid &&
531 tclass == node->ae.tclass &&
532 tsid == node->ae.tsid) {
533 ret = node;
534 break;
535 }
536 }
537
538 return ret;
539}
540
541/**
542 * avc_lookup - Look up an AVC entry.
543 * @ssid: source security identifier
544 * @tsid: target security identifier
545 * @tclass: target security class
546 *
547 * Look up an AVC entry that is valid for the
548 * (@ssid, @tsid), interpreting the permissions
549 * based on @tclass. If a valid AVC entry exists,
550 * then this function returns the avc_node.
551 * Otherwise, this function returns NULL.
552 */
553static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
554{
555 struct avc_node *node;
556
557 avc_cache_stats_incr(lookups);
558 node = avc_search_node(ssid, tsid, tclass);
559
560 if (node)
561 return node;
562
563 avc_cache_stats_incr(misses);
564 return NULL;
565}
566
567static int avc_latest_notif_update(u32 seqno, int is_insert)
568{
569 int ret = 0;
570 static DEFINE_SPINLOCK(notif_lock);
571 unsigned long flag;
572
573 spin_lock_irqsave(¬if_lock, flag);
574 if (is_insert) {
575 if (seqno < selinux_avc.avc_cache.latest_notif) {
576 pr_warn("SELinux: avc: seqno %d < latest_notif %d\n",
577 seqno, selinux_avc.avc_cache.latest_notif);
578 ret = -EAGAIN;
579 }
580 } else {
581 if (seqno > selinux_avc.avc_cache.latest_notif)
582 selinux_avc.avc_cache.latest_notif = seqno;
583 }
584 spin_unlock_irqrestore(¬if_lock, flag);
585
586 return ret;
587}
588
589/**
590 * avc_insert - Insert an AVC entry.
591 * @ssid: source security identifier
592 * @tsid: target security identifier
593 * @tclass: target security class
594 * @avd: resulting av decision
595 * @xp_node: resulting extended permissions
596 *
597 * Insert an AVC entry for the SID pair
598 * (@ssid, @tsid) and class @tclass.
599 * The access vectors and the sequence number are
600 * normally provided by the security server in
601 * response to a security_compute_av() call. If the
602 * sequence number @avd->seqno is not less than the latest
603 * revocation notification, then the function copies
604 * the access vectors into a cache entry.
605 */
606static void avc_insert(u32 ssid, u32 tsid, u16 tclass,
607 struct av_decision *avd, struct avc_xperms_node *xp_node)
608{
609 struct avc_node *pos, *node = NULL;
610 u32 hvalue;
611 unsigned long flag;
612 spinlock_t *lock;
613 struct hlist_head *head;
614
615 if (avc_latest_notif_update(avd->seqno, 1))
616 return;
617
618 node = avc_alloc_node();
619 if (!node)
620 return;
621
622 avc_node_populate(node, ssid, tsid, tclass, avd);
623 if (avc_xperms_populate(node, xp_node)) {
624 avc_node_kill(node);
625 return;
626 }
627
628 hvalue = avc_hash(ssid, tsid, tclass);
629 head = &selinux_avc.avc_cache.slots[hvalue];
630 lock = &selinux_avc.avc_cache.slots_lock[hvalue];
631 spin_lock_irqsave(lock, flag);
632 hlist_for_each_entry(pos, head, list) {
633 if (pos->ae.ssid == ssid &&
634 pos->ae.tsid == tsid &&
635 pos->ae.tclass == tclass) {
636 avc_node_replace(node, pos);
637 goto found;
638 }
639 }
640 hlist_add_head_rcu(&node->list, head);
641found:
642 spin_unlock_irqrestore(lock, flag);
643}
644
645/**
646 * avc_audit_pre_callback - SELinux specific information
647 * will be called by generic audit code
648 * @ab: the audit buffer
649 * @a: audit_data
650 */
651static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
652{
653 struct common_audit_data *ad = a;
654 struct selinux_audit_data *sad = ad->selinux_audit_data;
655 u32 av = sad->audited, perm;
656 const char *const *perms;
657 u32 i;
658
659 audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
660
661 if (av == 0) {
662 audit_log_format(ab, " null");
663 return;
664 }
665
666 perms = secclass_map[sad->tclass-1].perms;
667
668 audit_log_format(ab, " {");
669 i = 0;
670 perm = 1;
671 while (i < (sizeof(av) * 8)) {
672 if ((perm & av) && perms[i]) {
673 audit_log_format(ab, " %s", perms[i]);
674 av &= ~perm;
675 }
676 i++;
677 perm <<= 1;
678 }
679
680 if (av)
681 audit_log_format(ab, " 0x%x", av);
682
683 audit_log_format(ab, " } for ");
684}
685
686/**
687 * avc_audit_post_callback - SELinux specific information
688 * will be called by generic audit code
689 * @ab: the audit buffer
690 * @a: audit_data
691 */
692static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
693{
694 struct common_audit_data *ad = a;
695 struct selinux_audit_data *sad = ad->selinux_audit_data;
696 char *scontext = NULL;
697 char *tcontext = NULL;
698 const char *tclass = NULL;
699 u32 scontext_len;
700 u32 tcontext_len;
701 int rc;
702
703 rc = security_sid_to_context(sad->ssid, &scontext,
704 &scontext_len);
705 if (rc)
706 audit_log_format(ab, " ssid=%d", sad->ssid);
707 else
708 audit_log_format(ab, " scontext=%s", scontext);
709
710 rc = security_sid_to_context(sad->tsid, &tcontext,
711 &tcontext_len);
712 if (rc)
713 audit_log_format(ab, " tsid=%d", sad->tsid);
714 else
715 audit_log_format(ab, " tcontext=%s", tcontext);
716
717 tclass = secclass_map[sad->tclass-1].name;
718 audit_log_format(ab, " tclass=%s", tclass);
719
720 if (sad->denied)
721 audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
722
723 trace_selinux_audited(sad, scontext, tcontext, tclass);
724 kfree(tcontext);
725 kfree(scontext);
726
727 /* in case of invalid context report also the actual context string */
728 rc = security_sid_to_context_inval(sad->ssid, &scontext,
729 &scontext_len);
730 if (!rc && scontext) {
731 if (scontext_len && scontext[scontext_len - 1] == '\0')
732 scontext_len--;
733 audit_log_format(ab, " srawcon=");
734 audit_log_n_untrustedstring(ab, scontext, scontext_len);
735 kfree(scontext);
736 }
737
738 rc = security_sid_to_context_inval(sad->tsid, &scontext,
739 &scontext_len);
740 if (!rc && scontext) {
741 if (scontext_len && scontext[scontext_len - 1] == '\0')
742 scontext_len--;
743 audit_log_format(ab, " trawcon=");
744 audit_log_n_untrustedstring(ab, scontext, scontext_len);
745 kfree(scontext);
746 }
747}
748
749/*
750 * This is the slow part of avc audit with big stack footprint.
751 * Note that it is non-blocking and can be called from under
752 * rcu_read_lock().
753 */
754noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
755 u32 requested, u32 audited, u32 denied, int result,
756 struct common_audit_data *a)
757{
758 struct common_audit_data stack_data;
759 struct selinux_audit_data sad;
760
761 if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
762 return -EINVAL;
763
764 if (!a) {
765 a = &stack_data;
766 a->type = LSM_AUDIT_DATA_NONE;
767 }
768
769 sad.tclass = tclass;
770 sad.requested = requested;
771 sad.ssid = ssid;
772 sad.tsid = tsid;
773 sad.audited = audited;
774 sad.denied = denied;
775 sad.result = result;
776
777 a->selinux_audit_data = &sad;
778
779 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
780 return 0;
781}
782
783/**
784 * avc_add_callback - Register a callback for security events.
785 * @callback: callback function
786 * @events: security events
787 *
788 * Register a callback function for events in the set @events.
789 * Returns %0 on success or -%ENOMEM if insufficient memory
790 * exists to add the callback.
791 */
792int __init avc_add_callback(int (*callback)(u32 event), u32 events)
793{
794 struct avc_callback_node *c;
795 int rc = 0;
796
797 c = kmalloc(sizeof(*c), GFP_KERNEL);
798 if (!c) {
799 rc = -ENOMEM;
800 goto out;
801 }
802
803 c->callback = callback;
804 c->events = events;
805 c->next = avc_callbacks;
806 avc_callbacks = c;
807out:
808 return rc;
809}
810
811/**
812 * avc_update_node - Update an AVC entry
813 * @event : Updating event
814 * @perms : Permission mask bits
815 * @driver: xperm driver information
816 * @base_perm: the base permission associated with the extended permission
817 * @xperm: xperm permissions
818 * @ssid: AVC entry source sid
819 * @tsid: AVC entry target sid
820 * @tclass : AVC entry target object class
821 * @seqno : sequence number when decision was made
822 * @xpd: extended_perms_decision to be added to the node
823 * @flags: the AVC_* flags, e.g. AVC_EXTENDED_PERMS, or 0.
824 *
825 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
826 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
827 * otherwise, this function updates the AVC entry. The original AVC-entry object
828 * will release later by RCU.
829 */
830static int avc_update_node(u32 event, u32 perms, u8 driver, u8 base_perm,
831 u8 xperm, u32 ssid, u32 tsid, u16 tclass, u32 seqno,
832 struct extended_perms_decision *xpd, u32 flags)
833{
834 u32 hvalue;
835 int rc = 0;
836 unsigned long flag;
837 struct avc_node *pos, *node, *orig = NULL;
838 struct hlist_head *head;
839 spinlock_t *lock;
840
841 node = avc_alloc_node();
842 if (!node) {
843 rc = -ENOMEM;
844 goto out;
845 }
846
847 /* Lock the target slot */
848 hvalue = avc_hash(ssid, tsid, tclass);
849
850 head = &selinux_avc.avc_cache.slots[hvalue];
851 lock = &selinux_avc.avc_cache.slots_lock[hvalue];
852
853 spin_lock_irqsave(lock, flag);
854
855 hlist_for_each_entry(pos, head, list) {
856 if (ssid == pos->ae.ssid &&
857 tsid == pos->ae.tsid &&
858 tclass == pos->ae.tclass &&
859 seqno == pos->ae.avd.seqno){
860 orig = pos;
861 break;
862 }
863 }
864
865 if (!orig) {
866 rc = -ENOENT;
867 avc_node_kill(node);
868 goto out_unlock;
869 }
870
871 /*
872 * Copy and replace original node.
873 */
874
875 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
876
877 if (orig->ae.xp_node) {
878 rc = avc_xperms_populate(node, orig->ae.xp_node);
879 if (rc) {
880 avc_node_kill(node);
881 goto out_unlock;
882 }
883 }
884
885 switch (event) {
886 case AVC_CALLBACK_GRANT:
887 node->ae.avd.allowed |= perms;
888 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
889 avc_xperms_allow_perm(node->ae.xp_node, driver, base_perm, xperm);
890 break;
891 case AVC_CALLBACK_TRY_REVOKE:
892 case AVC_CALLBACK_REVOKE:
893 node->ae.avd.allowed &= ~perms;
894 break;
895 case AVC_CALLBACK_AUDITALLOW_ENABLE:
896 node->ae.avd.auditallow |= perms;
897 break;
898 case AVC_CALLBACK_AUDITALLOW_DISABLE:
899 node->ae.avd.auditallow &= ~perms;
900 break;
901 case AVC_CALLBACK_AUDITDENY_ENABLE:
902 node->ae.avd.auditdeny |= perms;
903 break;
904 case AVC_CALLBACK_AUDITDENY_DISABLE:
905 node->ae.avd.auditdeny &= ~perms;
906 break;
907 case AVC_CALLBACK_ADD_XPERMS:
908 rc = avc_add_xperms_decision(node, xpd);
909 if (rc) {
910 avc_node_kill(node);
911 goto out_unlock;
912 }
913 break;
914 }
915 avc_node_replace(node, orig);
916out_unlock:
917 spin_unlock_irqrestore(lock, flag);
918out:
919 return rc;
920}
921
922/**
923 * avc_flush - Flush the cache
924 */
925static void avc_flush(void)
926{
927 struct hlist_head *head;
928 struct avc_node *node;
929 spinlock_t *lock;
930 unsigned long flag;
931 int i;
932
933 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
934 head = &selinux_avc.avc_cache.slots[i];
935 lock = &selinux_avc.avc_cache.slots_lock[i];
936
937 spin_lock_irqsave(lock, flag);
938 /*
939 * With preemptable RCU, the outer spinlock does not
940 * prevent RCU grace periods from ending.
941 */
942 rcu_read_lock();
943 hlist_for_each_entry(node, head, list)
944 avc_node_delete(node);
945 rcu_read_unlock();
946 spin_unlock_irqrestore(lock, flag);
947 }
948}
949
950/**
951 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
952 * @seqno: policy sequence number
953 */
954int avc_ss_reset(u32 seqno)
955{
956 struct avc_callback_node *c;
957 int rc = 0, tmprc;
958
959 avc_flush();
960
961 for (c = avc_callbacks; c; c = c->next) {
962 if (c->events & AVC_CALLBACK_RESET) {
963 tmprc = c->callback(AVC_CALLBACK_RESET);
964 /* save the first error encountered for the return
965 value and continue processing the callbacks */
966 if (!rc)
967 rc = tmprc;
968 }
969 }
970
971 avc_latest_notif_update(seqno, 0);
972 return rc;
973}
974
975/**
976 * avc_compute_av - Add an entry to the AVC based on the security policy
977 * @ssid: subject
978 * @tsid: object/target
979 * @tclass: object class
980 * @avd: access vector decision
981 * @xp_node: AVC extended permissions node
982 *
983 * Slow-path helper function for avc_has_perm_noaudit, when the avc_node lookup
984 * fails. Don't inline this, since it's the slow-path and just results in a
985 * bigger stack frame.
986 */
987static noinline void avc_compute_av(u32 ssid, u32 tsid, u16 tclass,
988 struct av_decision *avd,
989 struct avc_xperms_node *xp_node)
990{
991 INIT_LIST_HEAD(&xp_node->xpd_head);
992 security_compute_av(ssid, tsid, tclass, avd, &xp_node->xp);
993 avc_insert(ssid, tsid, tclass, avd, xp_node);
994}
995
996static noinline int avc_denied(u32 ssid, u32 tsid, u16 tclass, u32 requested,
997 u8 driver, u8 base_perm, u8 xperm,
998 unsigned int flags, struct av_decision *avd)
999{
1000 if (flags & AVC_STRICT)
1001 return -EACCES;
1002
1003 if (enforcing_enabled() &&
1004 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1005 return -EACCES;
1006
1007 avc_update_node(AVC_CALLBACK_GRANT, requested, driver, base_perm,
1008 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1009 return 0;
1010}
1011
1012/*
1013 * The avc extended permissions logic adds an additional 256 bits of
1014 * permissions to an avc node when extended permissions for that node are
1015 * specified in the avtab. If the additional 256 permissions is not adequate,
1016 * as-is the case with ioctls, then multiple may be chained together and the
1017 * driver field is used to specify which set contains the permission.
1018 */
1019int avc_has_extended_perms(u32 ssid, u32 tsid, u16 tclass, u32 requested,
1020 u8 driver, u8 base_perm, u8 xperm,
1021 struct common_audit_data *ad)
1022{
1023 struct avc_node *node;
1024 struct av_decision avd;
1025 u32 denied;
1026 struct extended_perms_decision local_xpd;
1027 struct extended_perms_decision *xpd = NULL;
1028 struct extended_perms_data allowed;
1029 struct extended_perms_data auditallow;
1030 struct extended_perms_data dontaudit;
1031 struct avc_xperms_node local_xp_node;
1032 struct avc_xperms_node *xp_node;
1033 int rc = 0, rc2;
1034
1035 xp_node = &local_xp_node;
1036 if (WARN_ON(!requested))
1037 return -EACCES;
1038
1039 rcu_read_lock();
1040
1041 node = avc_lookup(ssid, tsid, tclass);
1042 if (unlikely(!node)) {
1043 avc_compute_av(ssid, tsid, tclass, &avd, xp_node);
1044 } else {
1045 memcpy(&avd, &node->ae.avd, sizeof(avd));
1046 xp_node = node->ae.xp_node;
1047 }
1048 /* if extended permissions are not defined, only consider av_decision */
1049 if (!xp_node || !xp_node->xp.len)
1050 goto decision;
1051
1052 local_xpd.allowed = &allowed;
1053 local_xpd.auditallow = &auditallow;
1054 local_xpd.dontaudit = &dontaudit;
1055
1056 xpd = avc_xperms_decision_lookup(driver, base_perm, xp_node);
1057 if (unlikely(!xpd)) {
1058 /*
1059 * Compute the extended_perms_decision only if the driver
1060 * is flagged and the base permission is known.
1061 */
1062 if (!security_xperm_test(xp_node->xp.drivers.p, driver) ||
1063 !(xp_node->xp.base_perms & base_perm)) {
1064 avd.allowed &= ~requested;
1065 goto decision;
1066 }
1067 rcu_read_unlock();
1068 security_compute_xperms_decision(ssid, tsid, tclass, driver,
1069 base_perm, &local_xpd);
1070 rcu_read_lock();
1071 avc_update_node(AVC_CALLBACK_ADD_XPERMS, requested, driver,
1072 base_perm, xperm, ssid, tsid, tclass, avd.seqno,
1073 &local_xpd, 0);
1074 } else {
1075 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1076 }
1077 xpd = &local_xpd;
1078
1079 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1080 avd.allowed &= ~requested;
1081
1082decision:
1083 denied = requested & ~(avd.allowed);
1084 if (unlikely(denied))
1085 rc = avc_denied(ssid, tsid, tclass, requested, driver,
1086 base_perm, xperm, AVC_EXTENDED_PERMS, &avd);
1087
1088 rcu_read_unlock();
1089
1090 rc2 = avc_xperms_audit(ssid, tsid, tclass, requested,
1091 &avd, xpd, xperm, rc, ad);
1092 if (rc2)
1093 return rc2;
1094 return rc;
1095}
1096
1097/**
1098 * avc_perm_nonode - Add an entry to the AVC
1099 * @ssid: subject
1100 * @tsid: object/target
1101 * @tclass: object class
1102 * @requested: requested permissions
1103 * @flags: AVC flags
1104 * @avd: access vector decision
1105 *
1106 * This is the "we have no node" part of avc_has_perm_noaudit(), which is
1107 * unlikely and needs extra stack space for the new node that we generate, so
1108 * don't inline it.
1109 */
1110static noinline int avc_perm_nonode(u32 ssid, u32 tsid, u16 tclass,
1111 u32 requested, unsigned int flags,
1112 struct av_decision *avd)
1113{
1114 u32 denied;
1115 struct avc_xperms_node xp_node;
1116
1117 avc_compute_av(ssid, tsid, tclass, avd, &xp_node);
1118 denied = requested & ~(avd->allowed);
1119 if (unlikely(denied))
1120 return avc_denied(ssid, tsid, tclass, requested, 0, 0, 0,
1121 flags, avd);
1122 return 0;
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 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(u32 ssid, u32 tsid,
1146 u16 tclass, u32 requested,
1147 unsigned int flags,
1148 struct av_decision *avd)
1149{
1150 u32 denied;
1151 struct avc_node *node;
1152
1153 if (WARN_ON(!requested))
1154 return -EACCES;
1155
1156 rcu_read_lock();
1157 node = avc_lookup(ssid, tsid, tclass);
1158 if (unlikely(!node)) {
1159 rcu_read_unlock();
1160 return avc_perm_nonode(ssid, tsid, tclass, requested,
1161 flags, avd);
1162 }
1163 denied = requested & ~node->ae.avd.allowed;
1164 memcpy(avd, &node->ae.avd, sizeof(*avd));
1165 rcu_read_unlock();
1166
1167 if (unlikely(denied))
1168 return avc_denied(ssid, tsid, tclass, requested, 0, 0, 0,
1169 flags, avd);
1170 return 0;
1171}
1172
1173/**
1174 * avc_has_perm - Check permissions and perform any appropriate auditing.
1175 * @ssid: source security identifier
1176 * @tsid: target security identifier
1177 * @tclass: target security class
1178 * @requested: requested permissions, interpreted based on @tclass
1179 * @auditdata: auxiliary audit data
1180 *
1181 * Check the AVC to determine whether the @requested permissions are granted
1182 * for the SID pair (@ssid, @tsid), interpreting the permissions
1183 * based on @tclass, and call the security server on a cache miss to obtain
1184 * a new decision and add it to the cache. Audit the granting or denial of
1185 * permissions in accordance with the policy. Return %0 if all @requested
1186 * permissions are granted, -%EACCES if any permissions are denied, or
1187 * another -errno upon other errors.
1188 */
1189int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
1190 u32 requested, struct common_audit_data *auditdata)
1191{
1192 struct av_decision avd;
1193 int rc, rc2;
1194
1195 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0,
1196 &avd);
1197
1198 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc,
1199 auditdata);
1200 if (rc2)
1201 return rc2;
1202 return rc;
1203}
1204
1205u32 avc_policy_seqno(void)
1206{
1207 return selinux_avc.avc_cache.latest_notif;
1208}
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}