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1/*
2 * Implementation of the kernel access vector cache (AVC).
3 *
4 * Authors: Stephen Smalley, <sds@tycho.nsa.gov>
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 <linux/list.h>
26#include <net/sock.h>
27#include <linux/un.h>
28#include <net/af_unix.h>
29#include <linux/ip.h>
30#include <linux/audit.h>
31#include <linux/ipv6.h>
32#include <net/ipv6.h>
33#include "avc.h"
34#include "avc_ss.h"
35#include "classmap.h"
36
37#define AVC_CACHE_SLOTS 512
38#define AVC_DEF_CACHE_THRESHOLD 512
39#define AVC_CACHE_RECLAIM 16
40
41#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
42#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
43#else
44#define avc_cache_stats_incr(field) do {} while (0)
45#endif
46
47struct avc_entry {
48 u32 ssid;
49 u32 tsid;
50 u16 tclass;
51 struct av_decision avd;
52 struct avc_xperms_node *xp_node;
53};
54
55struct avc_node {
56 struct avc_entry ae;
57 struct hlist_node list; /* anchored in avc_cache->slots[i] */
58 struct rcu_head rhead;
59};
60
61struct avc_xperms_decision_node {
62 struct extended_perms_decision xpd;
63 struct list_head xpd_list; /* list of extended_perms_decision */
64};
65
66struct avc_xperms_node {
67 struct extended_perms xp;
68 struct list_head xpd_head; /* list head of extended_perms_decision */
69};
70
71struct avc_cache {
72 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
73 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
74 atomic_t lru_hint; /* LRU hint for reclaim scan */
75 atomic_t active_nodes;
76 u32 latest_notif; /* latest revocation notification */
77};
78
79struct avc_callback_node {
80 int (*callback) (u32 event);
81 u32 events;
82 struct avc_callback_node *next;
83};
84
85#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
86DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
87#endif
88
89struct selinux_avc {
90 unsigned int avc_cache_threshold;
91 struct avc_cache avc_cache;
92};
93
94static struct selinux_avc selinux_avc;
95
96void selinux_avc_init(struct selinux_avc **avc)
97{
98 int i;
99
100 selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
101 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
102 INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
103 spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
104 }
105 atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
106 atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
107 *avc = &selinux_avc;
108}
109
110unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
111{
112 return avc->avc_cache_threshold;
113}
114
115void avc_set_cache_threshold(struct selinux_avc *avc,
116 unsigned int cache_threshold)
117{
118 avc->avc_cache_threshold = cache_threshold;
119}
120
121static struct avc_callback_node *avc_callbacks;
122static struct kmem_cache *avc_node_cachep;
123static struct kmem_cache *avc_xperms_data_cachep;
124static struct kmem_cache *avc_xperms_decision_cachep;
125static struct kmem_cache *avc_xperms_cachep;
126
127static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
128{
129 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
130}
131
132/**
133 * avc_dump_av - Display an access vector in human-readable form.
134 * @tclass: target security class
135 * @av: access vector
136 */
137static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
138{
139 const char **perms;
140 int i, perm;
141
142 if (av == 0) {
143 audit_log_format(ab, " null");
144 return;
145 }
146
147 BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
148 perms = secclass_map[tclass-1].perms;
149
150 audit_log_format(ab, " {");
151 i = 0;
152 perm = 1;
153 while (i < (sizeof(av) * 8)) {
154 if ((perm & av) && perms[i]) {
155 audit_log_format(ab, " %s", perms[i]);
156 av &= ~perm;
157 }
158 i++;
159 perm <<= 1;
160 }
161
162 if (av)
163 audit_log_format(ab, " 0x%x", av);
164
165 audit_log_format(ab, " }");
166}
167
168/**
169 * avc_dump_query - Display a SID pair and a class in human-readable form.
170 * @ssid: source security identifier
171 * @tsid: target security identifier
172 * @tclass: target security class
173 */
174static void avc_dump_query(struct audit_buffer *ab, struct selinux_state *state,
175 u32 ssid, u32 tsid, u16 tclass)
176{
177 int rc;
178 char *scontext;
179 u32 scontext_len;
180
181 rc = security_sid_to_context(state, ssid, &scontext, &scontext_len);
182 if (rc)
183 audit_log_format(ab, "ssid=%d", ssid);
184 else {
185 audit_log_format(ab, "scontext=%s", scontext);
186 kfree(scontext);
187 }
188
189 rc = security_sid_to_context(state, tsid, &scontext, &scontext_len);
190 if (rc)
191 audit_log_format(ab, " tsid=%d", tsid);
192 else {
193 audit_log_format(ab, " tcontext=%s", scontext);
194 kfree(scontext);
195 }
196
197 BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
198 audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
199}
200
201/**
202 * avc_init - Initialize the AVC.
203 *
204 * Initialize the access vector cache.
205 */
206void __init avc_init(void)
207{
208 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
209 0, SLAB_PANIC, NULL);
210 avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
211 sizeof(struct avc_xperms_node),
212 0, SLAB_PANIC, NULL);
213 avc_xperms_decision_cachep = kmem_cache_create(
214 "avc_xperms_decision_node",
215 sizeof(struct avc_xperms_decision_node),
216 0, SLAB_PANIC, NULL);
217 avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
218 sizeof(struct extended_perms_data),
219 0, SLAB_PANIC, NULL);
220}
221
222int avc_get_hash_stats(struct selinux_avc *avc, char *page)
223{
224 int i, chain_len, max_chain_len, slots_used;
225 struct avc_node *node;
226 struct hlist_head *head;
227
228 rcu_read_lock();
229
230 slots_used = 0;
231 max_chain_len = 0;
232 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
233 head = &avc->avc_cache.slots[i];
234 if (!hlist_empty(head)) {
235 slots_used++;
236 chain_len = 0;
237 hlist_for_each_entry_rcu(node, head, list)
238 chain_len++;
239 if (chain_len > max_chain_len)
240 max_chain_len = chain_len;
241 }
242 }
243
244 rcu_read_unlock();
245
246 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
247 "longest chain: %d\n",
248 atomic_read(&avc->avc_cache.active_nodes),
249 slots_used, AVC_CACHE_SLOTS, max_chain_len);
250}
251
252/*
253 * using a linked list for extended_perms_decision lookup because the list is
254 * always small. i.e. less than 5, typically 1
255 */
256static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
257 struct avc_xperms_node *xp_node)
258{
259 struct avc_xperms_decision_node *xpd_node;
260
261 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
262 if (xpd_node->xpd.driver == driver)
263 return &xpd_node->xpd;
264 }
265 return NULL;
266}
267
268static inline unsigned int
269avc_xperms_has_perm(struct extended_perms_decision *xpd,
270 u8 perm, u8 which)
271{
272 unsigned int rc = 0;
273
274 if ((which == XPERMS_ALLOWED) &&
275 (xpd->used & XPERMS_ALLOWED))
276 rc = security_xperm_test(xpd->allowed->p, perm);
277 else if ((which == XPERMS_AUDITALLOW) &&
278 (xpd->used & XPERMS_AUDITALLOW))
279 rc = security_xperm_test(xpd->auditallow->p, perm);
280 else if ((which == XPERMS_DONTAUDIT) &&
281 (xpd->used & XPERMS_DONTAUDIT))
282 rc = security_xperm_test(xpd->dontaudit->p, perm);
283 return rc;
284}
285
286static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
287 u8 driver, u8 perm)
288{
289 struct extended_perms_decision *xpd;
290 security_xperm_set(xp_node->xp.drivers.p, driver);
291 xpd = avc_xperms_decision_lookup(driver, xp_node);
292 if (xpd && xpd->allowed)
293 security_xperm_set(xpd->allowed->p, perm);
294}
295
296static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
297{
298 struct extended_perms_decision *xpd;
299
300 xpd = &xpd_node->xpd;
301 if (xpd->allowed)
302 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
303 if (xpd->auditallow)
304 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
305 if (xpd->dontaudit)
306 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
307 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
308}
309
310static void avc_xperms_free(struct avc_xperms_node *xp_node)
311{
312 struct avc_xperms_decision_node *xpd_node, *tmp;
313
314 if (!xp_node)
315 return;
316
317 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
318 list_del(&xpd_node->xpd_list);
319 avc_xperms_decision_free(xpd_node);
320 }
321 kmem_cache_free(avc_xperms_cachep, xp_node);
322}
323
324static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
325 struct extended_perms_decision *src)
326{
327 dest->driver = src->driver;
328 dest->used = src->used;
329 if (dest->used & XPERMS_ALLOWED)
330 memcpy(dest->allowed->p, src->allowed->p,
331 sizeof(src->allowed->p));
332 if (dest->used & XPERMS_AUDITALLOW)
333 memcpy(dest->auditallow->p, src->auditallow->p,
334 sizeof(src->auditallow->p));
335 if (dest->used & XPERMS_DONTAUDIT)
336 memcpy(dest->dontaudit->p, src->dontaudit->p,
337 sizeof(src->dontaudit->p));
338}
339
340/*
341 * similar to avc_copy_xperms_decision, but only copy decision
342 * information relevant to this perm
343 */
344static inline void avc_quick_copy_xperms_decision(u8 perm,
345 struct extended_perms_decision *dest,
346 struct extended_perms_decision *src)
347{
348 /*
349 * compute index of the u32 of the 256 bits (8 u32s) that contain this
350 * command permission
351 */
352 u8 i = perm >> 5;
353
354 dest->used = src->used;
355 if (dest->used & XPERMS_ALLOWED)
356 dest->allowed->p[i] = src->allowed->p[i];
357 if (dest->used & XPERMS_AUDITALLOW)
358 dest->auditallow->p[i] = src->auditallow->p[i];
359 if (dest->used & XPERMS_DONTAUDIT)
360 dest->dontaudit->p[i] = src->dontaudit->p[i];
361}
362
363static struct avc_xperms_decision_node
364 *avc_xperms_decision_alloc(u8 which)
365{
366 struct avc_xperms_decision_node *xpd_node;
367 struct extended_perms_decision *xpd;
368
369 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep, GFP_NOWAIT);
370 if (!xpd_node)
371 return NULL;
372
373 xpd = &xpd_node->xpd;
374 if (which & XPERMS_ALLOWED) {
375 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
376 GFP_NOWAIT);
377 if (!xpd->allowed)
378 goto error;
379 }
380 if (which & XPERMS_AUDITALLOW) {
381 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
382 GFP_NOWAIT);
383 if (!xpd->auditallow)
384 goto error;
385 }
386 if (which & XPERMS_DONTAUDIT) {
387 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
388 GFP_NOWAIT);
389 if (!xpd->dontaudit)
390 goto error;
391 }
392 return xpd_node;
393error:
394 avc_xperms_decision_free(xpd_node);
395 return NULL;
396}
397
398static int avc_add_xperms_decision(struct avc_node *node,
399 struct extended_perms_decision *src)
400{
401 struct avc_xperms_decision_node *dest_xpd;
402
403 node->ae.xp_node->xp.len++;
404 dest_xpd = avc_xperms_decision_alloc(src->used);
405 if (!dest_xpd)
406 return -ENOMEM;
407 avc_copy_xperms_decision(&dest_xpd->xpd, src);
408 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
409 return 0;
410}
411
412static struct avc_xperms_node *avc_xperms_alloc(void)
413{
414 struct avc_xperms_node *xp_node;
415
416 xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT);
417 if (!xp_node)
418 return xp_node;
419 INIT_LIST_HEAD(&xp_node->xpd_head);
420 return xp_node;
421}
422
423static int avc_xperms_populate(struct avc_node *node,
424 struct avc_xperms_node *src)
425{
426 struct avc_xperms_node *dest;
427 struct avc_xperms_decision_node *dest_xpd;
428 struct avc_xperms_decision_node *src_xpd;
429
430 if (src->xp.len == 0)
431 return 0;
432 dest = avc_xperms_alloc();
433 if (!dest)
434 return -ENOMEM;
435
436 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
437 dest->xp.len = src->xp.len;
438
439 /* for each source xpd allocate a destination xpd and copy */
440 list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
441 dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
442 if (!dest_xpd)
443 goto error;
444 avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
445 list_add(&dest_xpd->xpd_list, &dest->xpd_head);
446 }
447 node->ae.xp_node = dest;
448 return 0;
449error:
450 avc_xperms_free(dest);
451 return -ENOMEM;
452
453}
454
455static inline u32 avc_xperms_audit_required(u32 requested,
456 struct av_decision *avd,
457 struct extended_perms_decision *xpd,
458 u8 perm,
459 int result,
460 u32 *deniedp)
461{
462 u32 denied, audited;
463
464 denied = requested & ~avd->allowed;
465 if (unlikely(denied)) {
466 audited = denied & avd->auditdeny;
467 if (audited && xpd) {
468 if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
469 audited &= ~requested;
470 }
471 } else if (result) {
472 audited = denied = requested;
473 } else {
474 audited = requested & avd->auditallow;
475 if (audited && xpd) {
476 if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
477 audited &= ~requested;
478 }
479 }
480
481 *deniedp = denied;
482 return audited;
483}
484
485static inline int avc_xperms_audit(struct selinux_state *state,
486 u32 ssid, u32 tsid, u16 tclass,
487 u32 requested, struct av_decision *avd,
488 struct extended_perms_decision *xpd,
489 u8 perm, int result,
490 struct common_audit_data *ad)
491{
492 u32 audited, denied;
493
494 audited = avc_xperms_audit_required(
495 requested, avd, xpd, perm, result, &denied);
496 if (likely(!audited))
497 return 0;
498 return slow_avc_audit(state, ssid, tsid, tclass, requested,
499 audited, denied, result, ad, 0);
500}
501
502static void avc_node_free(struct rcu_head *rhead)
503{
504 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
505 avc_xperms_free(node->ae.xp_node);
506 kmem_cache_free(avc_node_cachep, node);
507 avc_cache_stats_incr(frees);
508}
509
510static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
511{
512 hlist_del_rcu(&node->list);
513 call_rcu(&node->rhead, avc_node_free);
514 atomic_dec(&avc->avc_cache.active_nodes);
515}
516
517static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
518{
519 avc_xperms_free(node->ae.xp_node);
520 kmem_cache_free(avc_node_cachep, node);
521 avc_cache_stats_incr(frees);
522 atomic_dec(&avc->avc_cache.active_nodes);
523}
524
525static void avc_node_replace(struct selinux_avc *avc,
526 struct avc_node *new, struct avc_node *old)
527{
528 hlist_replace_rcu(&old->list, &new->list);
529 call_rcu(&old->rhead, avc_node_free);
530 atomic_dec(&avc->avc_cache.active_nodes);
531}
532
533static inline int avc_reclaim_node(struct selinux_avc *avc)
534{
535 struct avc_node *node;
536 int hvalue, try, ecx;
537 unsigned long flags;
538 struct hlist_head *head;
539 spinlock_t *lock;
540
541 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
542 hvalue = atomic_inc_return(&avc->avc_cache.lru_hint) &
543 (AVC_CACHE_SLOTS - 1);
544 head = &avc->avc_cache.slots[hvalue];
545 lock = &avc->avc_cache.slots_lock[hvalue];
546
547 if (!spin_trylock_irqsave(lock, flags))
548 continue;
549
550 rcu_read_lock();
551 hlist_for_each_entry(node, head, list) {
552 avc_node_delete(avc, node);
553 avc_cache_stats_incr(reclaims);
554 ecx++;
555 if (ecx >= AVC_CACHE_RECLAIM) {
556 rcu_read_unlock();
557 spin_unlock_irqrestore(lock, flags);
558 goto out;
559 }
560 }
561 rcu_read_unlock();
562 spin_unlock_irqrestore(lock, flags);
563 }
564out:
565 return ecx;
566}
567
568static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
569{
570 struct avc_node *node;
571
572 node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT);
573 if (!node)
574 goto out;
575
576 INIT_HLIST_NODE(&node->list);
577 avc_cache_stats_incr(allocations);
578
579 if (atomic_inc_return(&avc->avc_cache.active_nodes) >
580 avc->avc_cache_threshold)
581 avc_reclaim_node(avc);
582
583out:
584 return node;
585}
586
587static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
588{
589 node->ae.ssid = ssid;
590 node->ae.tsid = tsid;
591 node->ae.tclass = tclass;
592 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
593}
594
595static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
596 u32 ssid, u32 tsid, u16 tclass)
597{
598 struct avc_node *node, *ret = NULL;
599 int hvalue;
600 struct hlist_head *head;
601
602 hvalue = avc_hash(ssid, tsid, tclass);
603 head = &avc->avc_cache.slots[hvalue];
604 hlist_for_each_entry_rcu(node, head, list) {
605 if (ssid == node->ae.ssid &&
606 tclass == node->ae.tclass &&
607 tsid == node->ae.tsid) {
608 ret = node;
609 break;
610 }
611 }
612
613 return ret;
614}
615
616/**
617 * avc_lookup - Look up an AVC entry.
618 * @ssid: source security identifier
619 * @tsid: target security identifier
620 * @tclass: target security class
621 *
622 * Look up an AVC entry that is valid for the
623 * (@ssid, @tsid), interpreting the permissions
624 * based on @tclass. If a valid AVC entry exists,
625 * then this function returns the avc_node.
626 * Otherwise, this function returns NULL.
627 */
628static struct avc_node *avc_lookup(struct selinux_avc *avc,
629 u32 ssid, u32 tsid, u16 tclass)
630{
631 struct avc_node *node;
632
633 avc_cache_stats_incr(lookups);
634 node = avc_search_node(avc, ssid, tsid, tclass);
635
636 if (node)
637 return node;
638
639 avc_cache_stats_incr(misses);
640 return NULL;
641}
642
643static int avc_latest_notif_update(struct selinux_avc *avc,
644 int seqno, int is_insert)
645{
646 int ret = 0;
647 static DEFINE_SPINLOCK(notif_lock);
648 unsigned long flag;
649
650 spin_lock_irqsave(¬if_lock, flag);
651 if (is_insert) {
652 if (seqno < avc->avc_cache.latest_notif) {
653 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
654 seqno, avc->avc_cache.latest_notif);
655 ret = -EAGAIN;
656 }
657 } else {
658 if (seqno > avc->avc_cache.latest_notif)
659 avc->avc_cache.latest_notif = seqno;
660 }
661 spin_unlock_irqrestore(¬if_lock, flag);
662
663 return ret;
664}
665
666/**
667 * avc_insert - Insert an AVC entry.
668 * @ssid: source security identifier
669 * @tsid: target security identifier
670 * @tclass: target security class
671 * @avd: resulting av decision
672 * @xp_node: resulting extended permissions
673 *
674 * Insert an AVC entry for the SID pair
675 * (@ssid, @tsid) and class @tclass.
676 * The access vectors and the sequence number are
677 * normally provided by the security server in
678 * response to a security_compute_av() call. If the
679 * sequence number @avd->seqno is not less than the latest
680 * revocation notification, then the function copies
681 * the access vectors into a cache entry, returns
682 * avc_node inserted. Otherwise, this function returns NULL.
683 */
684static struct avc_node *avc_insert(struct selinux_avc *avc,
685 u32 ssid, u32 tsid, u16 tclass,
686 struct av_decision *avd,
687 struct avc_xperms_node *xp_node)
688{
689 struct avc_node *pos, *node = NULL;
690 int hvalue;
691 unsigned long flag;
692
693 if (avc_latest_notif_update(avc, avd->seqno, 1))
694 goto out;
695
696 node = avc_alloc_node(avc);
697 if (node) {
698 struct hlist_head *head;
699 spinlock_t *lock;
700 int rc = 0;
701
702 hvalue = avc_hash(ssid, tsid, tclass);
703 avc_node_populate(node, ssid, tsid, tclass, avd);
704 rc = avc_xperms_populate(node, xp_node);
705 if (rc) {
706 kmem_cache_free(avc_node_cachep, node);
707 return NULL;
708 }
709 head = &avc->avc_cache.slots[hvalue];
710 lock = &avc->avc_cache.slots_lock[hvalue];
711
712 spin_lock_irqsave(lock, flag);
713 hlist_for_each_entry(pos, head, list) {
714 if (pos->ae.ssid == ssid &&
715 pos->ae.tsid == tsid &&
716 pos->ae.tclass == tclass) {
717 avc_node_replace(avc, node, pos);
718 goto found;
719 }
720 }
721 hlist_add_head_rcu(&node->list, head);
722found:
723 spin_unlock_irqrestore(lock, flag);
724 }
725out:
726 return node;
727}
728
729/**
730 * avc_audit_pre_callback - SELinux specific information
731 * will be called by generic audit code
732 * @ab: the audit buffer
733 * @a: audit_data
734 */
735static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
736{
737 struct common_audit_data *ad = a;
738 audit_log_format(ab, "avc: %s ",
739 ad->selinux_audit_data->denied ? "denied" : "granted");
740 avc_dump_av(ab, ad->selinux_audit_data->tclass,
741 ad->selinux_audit_data->audited);
742 audit_log_format(ab, " for ");
743}
744
745/**
746 * avc_audit_post_callback - SELinux specific information
747 * will be called by generic audit code
748 * @ab: the audit buffer
749 * @a: audit_data
750 */
751static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
752{
753 struct common_audit_data *ad = a;
754 audit_log_format(ab, " ");
755 avc_dump_query(ab, ad->selinux_audit_data->state,
756 ad->selinux_audit_data->ssid,
757 ad->selinux_audit_data->tsid,
758 ad->selinux_audit_data->tclass);
759 if (ad->selinux_audit_data->denied) {
760 audit_log_format(ab, " permissive=%u",
761 ad->selinux_audit_data->result ? 0 : 1);
762 }
763}
764
765/* This is the slow part of avc audit with big stack footprint */
766noinline int slow_avc_audit(struct selinux_state *state,
767 u32 ssid, u32 tsid, u16 tclass,
768 u32 requested, u32 audited, u32 denied, int result,
769 struct common_audit_data *a,
770 unsigned int flags)
771{
772 struct common_audit_data stack_data;
773 struct selinux_audit_data sad;
774
775 if (!a) {
776 a = &stack_data;
777 a->type = LSM_AUDIT_DATA_NONE;
778 }
779
780 /*
781 * When in a RCU walk do the audit on the RCU retry. This is because
782 * the collection of the dname in an inode audit message is not RCU
783 * safe. Note this may drop some audits when the situation changes
784 * during retry. However this is logically just as if the operation
785 * happened a little later.
786 */
787 if ((a->type == LSM_AUDIT_DATA_INODE) &&
788 (flags & MAY_NOT_BLOCK))
789 return -ECHILD;
790
791 sad.tclass = tclass;
792 sad.requested = requested;
793 sad.ssid = ssid;
794 sad.tsid = tsid;
795 sad.audited = audited;
796 sad.denied = denied;
797 sad.result = result;
798 sad.state = state;
799
800 a->selinux_audit_data = &sad;
801
802 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
803 return 0;
804}
805
806/**
807 * avc_add_callback - Register a callback for security events.
808 * @callback: callback function
809 * @events: security events
810 *
811 * Register a callback function for events in the set @events.
812 * Returns %0 on success or -%ENOMEM if insufficient memory
813 * exists to add the callback.
814 */
815int __init avc_add_callback(int (*callback)(u32 event), u32 events)
816{
817 struct avc_callback_node *c;
818 int rc = 0;
819
820 c = kmalloc(sizeof(*c), GFP_KERNEL);
821 if (!c) {
822 rc = -ENOMEM;
823 goto out;
824 }
825
826 c->callback = callback;
827 c->events = events;
828 c->next = avc_callbacks;
829 avc_callbacks = c;
830out:
831 return rc;
832}
833
834/**
835 * avc_update_node Update an AVC entry
836 * @event : Updating event
837 * @perms : Permission mask bits
838 * @ssid,@tsid,@tclass : identifier of an AVC entry
839 * @seqno : sequence number when decision was made
840 * @xpd: extended_perms_decision to be added to the node
841 *
842 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
843 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
844 * otherwise, this function updates the AVC entry. The original AVC-entry object
845 * will release later by RCU.
846 */
847static int avc_update_node(struct selinux_avc *avc,
848 u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
849 u32 tsid, u16 tclass, u32 seqno,
850 struct extended_perms_decision *xpd,
851 u32 flags)
852{
853 int hvalue, rc = 0;
854 unsigned long flag;
855 struct avc_node *pos, *node, *orig = NULL;
856 struct hlist_head *head;
857 spinlock_t *lock;
858
859 node = avc_alloc_node(avc);
860 if (!node) {
861 rc = -ENOMEM;
862 goto out;
863 }
864
865 /* Lock the target slot */
866 hvalue = avc_hash(ssid, tsid, tclass);
867
868 head = &avc->avc_cache.slots[hvalue];
869 lock = &avc->avc_cache.slots_lock[hvalue];
870
871 spin_lock_irqsave(lock, flag);
872
873 hlist_for_each_entry(pos, head, list) {
874 if (ssid == pos->ae.ssid &&
875 tsid == pos->ae.tsid &&
876 tclass == pos->ae.tclass &&
877 seqno == pos->ae.avd.seqno){
878 orig = pos;
879 break;
880 }
881 }
882
883 if (!orig) {
884 rc = -ENOENT;
885 avc_node_kill(avc, node);
886 goto out_unlock;
887 }
888
889 /*
890 * Copy and replace original node.
891 */
892
893 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
894
895 if (orig->ae.xp_node) {
896 rc = avc_xperms_populate(node, orig->ae.xp_node);
897 if (rc) {
898 kmem_cache_free(avc_node_cachep, node);
899 goto out_unlock;
900 }
901 }
902
903 switch (event) {
904 case AVC_CALLBACK_GRANT:
905 node->ae.avd.allowed |= perms;
906 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
907 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
908 break;
909 case AVC_CALLBACK_TRY_REVOKE:
910 case AVC_CALLBACK_REVOKE:
911 node->ae.avd.allowed &= ~perms;
912 break;
913 case AVC_CALLBACK_AUDITALLOW_ENABLE:
914 node->ae.avd.auditallow |= perms;
915 break;
916 case AVC_CALLBACK_AUDITALLOW_DISABLE:
917 node->ae.avd.auditallow &= ~perms;
918 break;
919 case AVC_CALLBACK_AUDITDENY_ENABLE:
920 node->ae.avd.auditdeny |= perms;
921 break;
922 case AVC_CALLBACK_AUDITDENY_DISABLE:
923 node->ae.avd.auditdeny &= ~perms;
924 break;
925 case AVC_CALLBACK_ADD_XPERMS:
926 avc_add_xperms_decision(node, xpd);
927 break;
928 }
929 avc_node_replace(avc, node, orig);
930out_unlock:
931 spin_unlock_irqrestore(lock, flag);
932out:
933 return rc;
934}
935
936/**
937 * avc_flush - Flush the cache
938 */
939static void avc_flush(struct selinux_avc *avc)
940{
941 struct hlist_head *head;
942 struct avc_node *node;
943 spinlock_t *lock;
944 unsigned long flag;
945 int i;
946
947 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
948 head = &avc->avc_cache.slots[i];
949 lock = &avc->avc_cache.slots_lock[i];
950
951 spin_lock_irqsave(lock, flag);
952 /*
953 * With preemptable RCU, the outer spinlock does not
954 * prevent RCU grace periods from ending.
955 */
956 rcu_read_lock();
957 hlist_for_each_entry(node, head, list)
958 avc_node_delete(avc, node);
959 rcu_read_unlock();
960 spin_unlock_irqrestore(lock, flag);
961 }
962}
963
964/**
965 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
966 * @seqno: policy sequence number
967 */
968int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
969{
970 struct avc_callback_node *c;
971 int rc = 0, tmprc;
972
973 avc_flush(avc);
974
975 for (c = avc_callbacks; c; c = c->next) {
976 if (c->events & AVC_CALLBACK_RESET) {
977 tmprc = c->callback(AVC_CALLBACK_RESET);
978 /* save the first error encountered for the return
979 value and continue processing the callbacks */
980 if (!rc)
981 rc = tmprc;
982 }
983 }
984
985 avc_latest_notif_update(avc, seqno, 0);
986 return rc;
987}
988
989/*
990 * Slow-path helper function for avc_has_perm_noaudit,
991 * when the avc_node lookup fails. We get called with
992 * the RCU read lock held, and need to return with it
993 * still held, but drop if for the security compute.
994 *
995 * Don't inline this, since it's the slow-path and just
996 * results in a bigger stack frame.
997 */
998static noinline
999struct avc_node *avc_compute_av(struct selinux_state *state,
1000 u32 ssid, u32 tsid,
1001 u16 tclass, struct av_decision *avd,
1002 struct avc_xperms_node *xp_node)
1003{
1004 rcu_read_unlock();
1005 INIT_LIST_HEAD(&xp_node->xpd_head);
1006 security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
1007 rcu_read_lock();
1008 return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
1009}
1010
1011static noinline int avc_denied(struct selinux_state *state,
1012 u32 ssid, u32 tsid,
1013 u16 tclass, u32 requested,
1014 u8 driver, u8 xperm, unsigned int flags,
1015 struct av_decision *avd)
1016{
1017 if (flags & AVC_STRICT)
1018 return -EACCES;
1019
1020 if (enforcing_enabled(state) &&
1021 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1022 return -EACCES;
1023
1024 avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
1025 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1026 return 0;
1027}
1028
1029/*
1030 * The avc extended permissions logic adds an additional 256 bits of
1031 * permissions to an avc node when extended permissions for that node are
1032 * specified in the avtab. If the additional 256 permissions is not adequate,
1033 * as-is the case with ioctls, then multiple may be chained together and the
1034 * driver field is used to specify which set contains the permission.
1035 */
1036int avc_has_extended_perms(struct selinux_state *state,
1037 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1038 u8 driver, u8 xperm, struct common_audit_data *ad)
1039{
1040 struct avc_node *node;
1041 struct av_decision avd;
1042 u32 denied;
1043 struct extended_perms_decision local_xpd;
1044 struct extended_perms_decision *xpd = NULL;
1045 struct extended_perms_data allowed;
1046 struct extended_perms_data auditallow;
1047 struct extended_perms_data dontaudit;
1048 struct avc_xperms_node local_xp_node;
1049 struct avc_xperms_node *xp_node;
1050 int rc = 0, rc2;
1051
1052 xp_node = &local_xp_node;
1053 BUG_ON(!requested);
1054
1055 rcu_read_lock();
1056
1057 node = avc_lookup(state->avc, ssid, tsid, tclass);
1058 if (unlikely(!node)) {
1059 node = avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
1060 } else {
1061 memcpy(&avd, &node->ae.avd, sizeof(avd));
1062 xp_node = node->ae.xp_node;
1063 }
1064 /* if extended permissions are not defined, only consider av_decision */
1065 if (!xp_node || !xp_node->xp.len)
1066 goto decision;
1067
1068 local_xpd.allowed = &allowed;
1069 local_xpd.auditallow = &auditallow;
1070 local_xpd.dontaudit = &dontaudit;
1071
1072 xpd = avc_xperms_decision_lookup(driver, xp_node);
1073 if (unlikely(!xpd)) {
1074 /*
1075 * Compute the extended_perms_decision only if the driver
1076 * is flagged
1077 */
1078 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1079 avd.allowed &= ~requested;
1080 goto decision;
1081 }
1082 rcu_read_unlock();
1083 security_compute_xperms_decision(state, ssid, tsid, tclass,
1084 driver, &local_xpd);
1085 rcu_read_lock();
1086 avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
1087 driver, xperm, ssid, tsid, tclass, avd.seqno,
1088 &local_xpd, 0);
1089 } else {
1090 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1091 }
1092 xpd = &local_xpd;
1093
1094 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1095 avd.allowed &= ~requested;
1096
1097decision:
1098 denied = requested & ~(avd.allowed);
1099 if (unlikely(denied))
1100 rc = avc_denied(state, ssid, tsid, tclass, requested,
1101 driver, xperm, AVC_EXTENDED_PERMS, &avd);
1102
1103 rcu_read_unlock();
1104
1105 rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
1106 &avd, xpd, xperm, rc, ad);
1107 if (rc2)
1108 return rc2;
1109 return rc;
1110}
1111
1112/**
1113 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1114 * @ssid: source security identifier
1115 * @tsid: target security identifier
1116 * @tclass: target security class
1117 * @requested: requested permissions, interpreted based on @tclass
1118 * @flags: AVC_STRICT or 0
1119 * @avd: access vector decisions
1120 *
1121 * Check the AVC to determine whether the @requested permissions are granted
1122 * for the SID pair (@ssid, @tsid), interpreting the permissions
1123 * based on @tclass, and call the security server on a cache miss to obtain
1124 * a new decision and add it to the cache. Return a copy of the decisions
1125 * in @avd. Return %0 if all @requested permissions are granted,
1126 * -%EACCES if any permissions are denied, or another -errno upon
1127 * other errors. This function is typically called by avc_has_perm(),
1128 * but may also be called directly to separate permission checking from
1129 * auditing, e.g. in cases where a lock must be held for the check but
1130 * should be released for the auditing.
1131 */
1132inline int avc_has_perm_noaudit(struct selinux_state *state,
1133 u32 ssid, u32 tsid,
1134 u16 tclass, u32 requested,
1135 unsigned int flags,
1136 struct av_decision *avd)
1137{
1138 struct avc_node *node;
1139 struct avc_xperms_node xp_node;
1140 int rc = 0;
1141 u32 denied;
1142
1143 BUG_ON(!requested);
1144
1145 rcu_read_lock();
1146
1147 node = avc_lookup(state->avc, ssid, tsid, tclass);
1148 if (unlikely(!node))
1149 node = avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
1150 else
1151 memcpy(avd, &node->ae.avd, sizeof(*avd));
1152
1153 denied = requested & ~(avd->allowed);
1154 if (unlikely(denied))
1155 rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
1156 flags, avd);
1157
1158 rcu_read_unlock();
1159 return rc;
1160}
1161
1162/**
1163 * avc_has_perm - Check permissions and perform any appropriate auditing.
1164 * @ssid: source security identifier
1165 * @tsid: target security identifier
1166 * @tclass: target security class
1167 * @requested: requested permissions, interpreted based on @tclass
1168 * @auditdata: auxiliary audit data
1169 *
1170 * Check the AVC to determine whether the @requested permissions are granted
1171 * for the SID pair (@ssid, @tsid), interpreting the permissions
1172 * based on @tclass, and call the security server on a cache miss to obtain
1173 * a new decision and add it to the cache. Audit the granting or denial of
1174 * permissions in accordance with the policy. Return %0 if all @requested
1175 * permissions are granted, -%EACCES if any permissions are denied, or
1176 * another -errno upon other errors.
1177 */
1178int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
1179 u32 requested, struct common_audit_data *auditdata)
1180{
1181 struct av_decision avd;
1182 int rc, rc2;
1183
1184 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1185 &avd);
1186
1187 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1188 auditdata, 0);
1189 if (rc2)
1190 return rc2;
1191 return rc;
1192}
1193
1194int avc_has_perm_flags(struct selinux_state *state,
1195 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1196 struct common_audit_data *auditdata,
1197 int flags)
1198{
1199 struct av_decision avd;
1200 int rc, rc2;
1201
1202 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1203 &avd);
1204
1205 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1206 auditdata, flags);
1207 if (rc2)
1208 return rc2;
1209 return rc;
1210}
1211
1212u32 avc_policy_seqno(struct selinux_state *state)
1213{
1214 return state->avc->avc_cache.latest_notif;
1215}
1216
1217void avc_disable(void)
1218{
1219 /*
1220 * If you are looking at this because you have realized that we are
1221 * not destroying the avc_node_cachep it might be easy to fix, but
1222 * I don't know the memory barrier semantics well enough to know. It's
1223 * possible that some other task dereferenced security_ops when
1224 * it still pointed to selinux operations. If that is the case it's
1225 * possible that it is about to use the avc and is about to need the
1226 * avc_node_cachep. I know I could wrap the security.c security_ops call
1227 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1228 * the cache and get that memory back.
1229 */
1230 if (avc_node_cachep) {
1231 avc_flush(selinux_state.avc);
1232 /* kmem_cache_destroy(avc_node_cachep); */
1233 }
1234}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Implementation of the kernel access vector cache (AVC).
4 *
5 * Authors: Stephen Smalley, <sds@tycho.nsa.gov>
6 * James Morris <jmorris@redhat.com>
7 *
8 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
9 * Replaced the avc_lock spinlock by RCU.
10 *
11 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
12 */
13#include <linux/types.h>
14#include <linux/stddef.h>
15#include <linux/kernel.h>
16#include <linux/slab.h>
17#include <linux/fs.h>
18#include <linux/dcache.h>
19#include <linux/init.h>
20#include <linux/skbuff.h>
21#include <linux/percpu.h>
22#include <linux/list.h>
23#include <net/sock.h>
24#include <linux/un.h>
25#include <net/af_unix.h>
26#include <linux/ip.h>
27#include <linux/audit.h>
28#include <linux/ipv6.h>
29#include <net/ipv6.h>
30#include "avc.h"
31#include "avc_ss.h"
32#include "classmap.h"
33
34#define AVC_CACHE_SLOTS 512
35#define AVC_DEF_CACHE_THRESHOLD 512
36#define AVC_CACHE_RECLAIM 16
37
38#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
39#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
40#else
41#define avc_cache_stats_incr(field) do {} while (0)
42#endif
43
44struct avc_entry {
45 u32 ssid;
46 u32 tsid;
47 u16 tclass;
48 struct av_decision avd;
49 struct avc_xperms_node *xp_node;
50};
51
52struct avc_node {
53 struct avc_entry ae;
54 struct hlist_node list; /* anchored in avc_cache->slots[i] */
55 struct rcu_head rhead;
56};
57
58struct avc_xperms_decision_node {
59 struct extended_perms_decision xpd;
60 struct list_head xpd_list; /* list of extended_perms_decision */
61};
62
63struct avc_xperms_node {
64 struct extended_perms xp;
65 struct list_head xpd_head; /* list head of extended_perms_decision */
66};
67
68struct avc_cache {
69 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
70 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
71 atomic_t lru_hint; /* LRU hint for reclaim scan */
72 atomic_t active_nodes;
73 u32 latest_notif; /* latest revocation notification */
74};
75
76struct avc_callback_node {
77 int (*callback) (u32 event);
78 u32 events;
79 struct avc_callback_node *next;
80};
81
82#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
83DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
84#endif
85
86struct selinux_avc {
87 unsigned int avc_cache_threshold;
88 struct avc_cache avc_cache;
89};
90
91static struct selinux_avc selinux_avc;
92
93void selinux_avc_init(struct selinux_avc **avc)
94{
95 int i;
96
97 selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
98 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
99 INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
100 spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
101 }
102 atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
103 atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
104 *avc = &selinux_avc;
105}
106
107unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
108{
109 return avc->avc_cache_threshold;
110}
111
112void avc_set_cache_threshold(struct selinux_avc *avc,
113 unsigned int cache_threshold)
114{
115 avc->avc_cache_threshold = cache_threshold;
116}
117
118static struct avc_callback_node *avc_callbacks;
119static struct kmem_cache *avc_node_cachep;
120static struct kmem_cache *avc_xperms_data_cachep;
121static struct kmem_cache *avc_xperms_decision_cachep;
122static struct kmem_cache *avc_xperms_cachep;
123
124static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
125{
126 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
127}
128
129/**
130 * avc_init - Initialize the AVC.
131 *
132 * Initialize the access vector cache.
133 */
134void __init avc_init(void)
135{
136 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
137 0, SLAB_PANIC, NULL);
138 avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
139 sizeof(struct avc_xperms_node),
140 0, SLAB_PANIC, NULL);
141 avc_xperms_decision_cachep = kmem_cache_create(
142 "avc_xperms_decision_node",
143 sizeof(struct avc_xperms_decision_node),
144 0, SLAB_PANIC, NULL);
145 avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
146 sizeof(struct extended_perms_data),
147 0, SLAB_PANIC, NULL);
148}
149
150int avc_get_hash_stats(struct selinux_avc *avc, char *page)
151{
152 int i, chain_len, max_chain_len, slots_used;
153 struct avc_node *node;
154 struct hlist_head *head;
155
156 rcu_read_lock();
157
158 slots_used = 0;
159 max_chain_len = 0;
160 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
161 head = &avc->avc_cache.slots[i];
162 if (!hlist_empty(head)) {
163 slots_used++;
164 chain_len = 0;
165 hlist_for_each_entry_rcu(node, head, list)
166 chain_len++;
167 if (chain_len > max_chain_len)
168 max_chain_len = chain_len;
169 }
170 }
171
172 rcu_read_unlock();
173
174 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
175 "longest chain: %d\n",
176 atomic_read(&avc->avc_cache.active_nodes),
177 slots_used, AVC_CACHE_SLOTS, max_chain_len);
178}
179
180/*
181 * using a linked list for extended_perms_decision lookup because the list is
182 * always small. i.e. less than 5, typically 1
183 */
184static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
185 struct avc_xperms_node *xp_node)
186{
187 struct avc_xperms_decision_node *xpd_node;
188
189 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
190 if (xpd_node->xpd.driver == driver)
191 return &xpd_node->xpd;
192 }
193 return NULL;
194}
195
196static inline unsigned int
197avc_xperms_has_perm(struct extended_perms_decision *xpd,
198 u8 perm, u8 which)
199{
200 unsigned int rc = 0;
201
202 if ((which == XPERMS_ALLOWED) &&
203 (xpd->used & XPERMS_ALLOWED))
204 rc = security_xperm_test(xpd->allowed->p, perm);
205 else if ((which == XPERMS_AUDITALLOW) &&
206 (xpd->used & XPERMS_AUDITALLOW))
207 rc = security_xperm_test(xpd->auditallow->p, perm);
208 else if ((which == XPERMS_DONTAUDIT) &&
209 (xpd->used & XPERMS_DONTAUDIT))
210 rc = security_xperm_test(xpd->dontaudit->p, perm);
211 return rc;
212}
213
214static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
215 u8 driver, u8 perm)
216{
217 struct extended_perms_decision *xpd;
218 security_xperm_set(xp_node->xp.drivers.p, driver);
219 xpd = avc_xperms_decision_lookup(driver, xp_node);
220 if (xpd && xpd->allowed)
221 security_xperm_set(xpd->allowed->p, perm);
222}
223
224static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
225{
226 struct extended_perms_decision *xpd;
227
228 xpd = &xpd_node->xpd;
229 if (xpd->allowed)
230 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
231 if (xpd->auditallow)
232 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
233 if (xpd->dontaudit)
234 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
235 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
236}
237
238static void avc_xperms_free(struct avc_xperms_node *xp_node)
239{
240 struct avc_xperms_decision_node *xpd_node, *tmp;
241
242 if (!xp_node)
243 return;
244
245 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
246 list_del(&xpd_node->xpd_list);
247 avc_xperms_decision_free(xpd_node);
248 }
249 kmem_cache_free(avc_xperms_cachep, xp_node);
250}
251
252static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
253 struct extended_perms_decision *src)
254{
255 dest->driver = src->driver;
256 dest->used = src->used;
257 if (dest->used & XPERMS_ALLOWED)
258 memcpy(dest->allowed->p, src->allowed->p,
259 sizeof(src->allowed->p));
260 if (dest->used & XPERMS_AUDITALLOW)
261 memcpy(dest->auditallow->p, src->auditallow->p,
262 sizeof(src->auditallow->p));
263 if (dest->used & XPERMS_DONTAUDIT)
264 memcpy(dest->dontaudit->p, src->dontaudit->p,
265 sizeof(src->dontaudit->p));
266}
267
268/*
269 * similar to avc_copy_xperms_decision, but only copy decision
270 * information relevant to this perm
271 */
272static inline void avc_quick_copy_xperms_decision(u8 perm,
273 struct extended_perms_decision *dest,
274 struct extended_perms_decision *src)
275{
276 /*
277 * compute index of the u32 of the 256 bits (8 u32s) that contain this
278 * command permission
279 */
280 u8 i = perm >> 5;
281
282 dest->used = src->used;
283 if (dest->used & XPERMS_ALLOWED)
284 dest->allowed->p[i] = src->allowed->p[i];
285 if (dest->used & XPERMS_AUDITALLOW)
286 dest->auditallow->p[i] = src->auditallow->p[i];
287 if (dest->used & XPERMS_DONTAUDIT)
288 dest->dontaudit->p[i] = src->dontaudit->p[i];
289}
290
291static struct avc_xperms_decision_node
292 *avc_xperms_decision_alloc(u8 which)
293{
294 struct avc_xperms_decision_node *xpd_node;
295 struct extended_perms_decision *xpd;
296
297 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep, GFP_NOWAIT);
298 if (!xpd_node)
299 return NULL;
300
301 xpd = &xpd_node->xpd;
302 if (which & XPERMS_ALLOWED) {
303 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
304 GFP_NOWAIT);
305 if (!xpd->allowed)
306 goto error;
307 }
308 if (which & XPERMS_AUDITALLOW) {
309 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
310 GFP_NOWAIT);
311 if (!xpd->auditallow)
312 goto error;
313 }
314 if (which & XPERMS_DONTAUDIT) {
315 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
316 GFP_NOWAIT);
317 if (!xpd->dontaudit)
318 goto error;
319 }
320 return xpd_node;
321error:
322 avc_xperms_decision_free(xpd_node);
323 return NULL;
324}
325
326static int avc_add_xperms_decision(struct avc_node *node,
327 struct extended_perms_decision *src)
328{
329 struct avc_xperms_decision_node *dest_xpd;
330
331 node->ae.xp_node->xp.len++;
332 dest_xpd = avc_xperms_decision_alloc(src->used);
333 if (!dest_xpd)
334 return -ENOMEM;
335 avc_copy_xperms_decision(&dest_xpd->xpd, src);
336 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
337 return 0;
338}
339
340static struct avc_xperms_node *avc_xperms_alloc(void)
341{
342 struct avc_xperms_node *xp_node;
343
344 xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT);
345 if (!xp_node)
346 return xp_node;
347 INIT_LIST_HEAD(&xp_node->xpd_head);
348 return xp_node;
349}
350
351static int avc_xperms_populate(struct avc_node *node,
352 struct avc_xperms_node *src)
353{
354 struct avc_xperms_node *dest;
355 struct avc_xperms_decision_node *dest_xpd;
356 struct avc_xperms_decision_node *src_xpd;
357
358 if (src->xp.len == 0)
359 return 0;
360 dest = avc_xperms_alloc();
361 if (!dest)
362 return -ENOMEM;
363
364 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
365 dest->xp.len = src->xp.len;
366
367 /* for each source xpd allocate a destination xpd and copy */
368 list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
369 dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
370 if (!dest_xpd)
371 goto error;
372 avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
373 list_add(&dest_xpd->xpd_list, &dest->xpd_head);
374 }
375 node->ae.xp_node = dest;
376 return 0;
377error:
378 avc_xperms_free(dest);
379 return -ENOMEM;
380
381}
382
383static inline u32 avc_xperms_audit_required(u32 requested,
384 struct av_decision *avd,
385 struct extended_perms_decision *xpd,
386 u8 perm,
387 int result,
388 u32 *deniedp)
389{
390 u32 denied, audited;
391
392 denied = requested & ~avd->allowed;
393 if (unlikely(denied)) {
394 audited = denied & avd->auditdeny;
395 if (audited && xpd) {
396 if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
397 audited &= ~requested;
398 }
399 } else if (result) {
400 audited = denied = requested;
401 } else {
402 audited = requested & avd->auditallow;
403 if (audited && xpd) {
404 if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
405 audited &= ~requested;
406 }
407 }
408
409 *deniedp = denied;
410 return audited;
411}
412
413static inline int avc_xperms_audit(struct selinux_state *state,
414 u32 ssid, u32 tsid, u16 tclass,
415 u32 requested, struct av_decision *avd,
416 struct extended_perms_decision *xpd,
417 u8 perm, int result,
418 struct common_audit_data *ad)
419{
420 u32 audited, denied;
421
422 audited = avc_xperms_audit_required(
423 requested, avd, xpd, perm, result, &denied);
424 if (likely(!audited))
425 return 0;
426 return slow_avc_audit(state, ssid, tsid, tclass, requested,
427 audited, denied, result, ad, 0);
428}
429
430static void avc_node_free(struct rcu_head *rhead)
431{
432 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
433 avc_xperms_free(node->ae.xp_node);
434 kmem_cache_free(avc_node_cachep, node);
435 avc_cache_stats_incr(frees);
436}
437
438static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
439{
440 hlist_del_rcu(&node->list);
441 call_rcu(&node->rhead, avc_node_free);
442 atomic_dec(&avc->avc_cache.active_nodes);
443}
444
445static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
446{
447 avc_xperms_free(node->ae.xp_node);
448 kmem_cache_free(avc_node_cachep, node);
449 avc_cache_stats_incr(frees);
450 atomic_dec(&avc->avc_cache.active_nodes);
451}
452
453static void avc_node_replace(struct selinux_avc *avc,
454 struct avc_node *new, struct avc_node *old)
455{
456 hlist_replace_rcu(&old->list, &new->list);
457 call_rcu(&old->rhead, avc_node_free);
458 atomic_dec(&avc->avc_cache.active_nodes);
459}
460
461static inline int avc_reclaim_node(struct selinux_avc *avc)
462{
463 struct avc_node *node;
464 int hvalue, try, ecx;
465 unsigned long flags;
466 struct hlist_head *head;
467 spinlock_t *lock;
468
469 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
470 hvalue = atomic_inc_return(&avc->avc_cache.lru_hint) &
471 (AVC_CACHE_SLOTS - 1);
472 head = &avc->avc_cache.slots[hvalue];
473 lock = &avc->avc_cache.slots_lock[hvalue];
474
475 if (!spin_trylock_irqsave(lock, flags))
476 continue;
477
478 rcu_read_lock();
479 hlist_for_each_entry(node, head, list) {
480 avc_node_delete(avc, node);
481 avc_cache_stats_incr(reclaims);
482 ecx++;
483 if (ecx >= AVC_CACHE_RECLAIM) {
484 rcu_read_unlock();
485 spin_unlock_irqrestore(lock, flags);
486 goto out;
487 }
488 }
489 rcu_read_unlock();
490 spin_unlock_irqrestore(lock, flags);
491 }
492out:
493 return ecx;
494}
495
496static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
497{
498 struct avc_node *node;
499
500 node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT);
501 if (!node)
502 goto out;
503
504 INIT_HLIST_NODE(&node->list);
505 avc_cache_stats_incr(allocations);
506
507 if (atomic_inc_return(&avc->avc_cache.active_nodes) >
508 avc->avc_cache_threshold)
509 avc_reclaim_node(avc);
510
511out:
512 return node;
513}
514
515static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
516{
517 node->ae.ssid = ssid;
518 node->ae.tsid = tsid;
519 node->ae.tclass = tclass;
520 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
521}
522
523static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
524 u32 ssid, u32 tsid, u16 tclass)
525{
526 struct avc_node *node, *ret = NULL;
527 int hvalue;
528 struct hlist_head *head;
529
530 hvalue = avc_hash(ssid, tsid, tclass);
531 head = &avc->avc_cache.slots[hvalue];
532 hlist_for_each_entry_rcu(node, head, list) {
533 if (ssid == node->ae.ssid &&
534 tclass == node->ae.tclass &&
535 tsid == node->ae.tsid) {
536 ret = node;
537 break;
538 }
539 }
540
541 return ret;
542}
543
544/**
545 * avc_lookup - Look up an AVC entry.
546 * @ssid: source security identifier
547 * @tsid: target security identifier
548 * @tclass: target security class
549 *
550 * Look up an AVC entry that is valid for the
551 * (@ssid, @tsid), interpreting the permissions
552 * based on @tclass. If a valid AVC entry exists,
553 * then this function returns the avc_node.
554 * Otherwise, this function returns NULL.
555 */
556static struct avc_node *avc_lookup(struct selinux_avc *avc,
557 u32 ssid, u32 tsid, u16 tclass)
558{
559 struct avc_node *node;
560
561 avc_cache_stats_incr(lookups);
562 node = avc_search_node(avc, ssid, tsid, tclass);
563
564 if (node)
565 return node;
566
567 avc_cache_stats_incr(misses);
568 return NULL;
569}
570
571static int avc_latest_notif_update(struct selinux_avc *avc,
572 int seqno, int is_insert)
573{
574 int ret = 0;
575 static DEFINE_SPINLOCK(notif_lock);
576 unsigned long flag;
577
578 spin_lock_irqsave(¬if_lock, flag);
579 if (is_insert) {
580 if (seqno < avc->avc_cache.latest_notif) {
581 pr_warn("SELinux: avc: seqno %d < latest_notif %d\n",
582 seqno, avc->avc_cache.latest_notif);
583 ret = -EAGAIN;
584 }
585 } else {
586 if (seqno > avc->avc_cache.latest_notif)
587 avc->avc_cache.latest_notif = seqno;
588 }
589 spin_unlock_irqrestore(¬if_lock, flag);
590
591 return ret;
592}
593
594/**
595 * avc_insert - Insert an AVC entry.
596 * @ssid: source security identifier
597 * @tsid: target security identifier
598 * @tclass: target security class
599 * @avd: resulting av decision
600 * @xp_node: resulting extended permissions
601 *
602 * Insert an AVC entry for the SID pair
603 * (@ssid, @tsid) and class @tclass.
604 * The access vectors and the sequence number are
605 * normally provided by the security server in
606 * response to a security_compute_av() call. If the
607 * sequence number @avd->seqno is not less than the latest
608 * revocation notification, then the function copies
609 * the access vectors into a cache entry, returns
610 * avc_node inserted. Otherwise, this function returns NULL.
611 */
612static struct avc_node *avc_insert(struct selinux_avc *avc,
613 u32 ssid, u32 tsid, u16 tclass,
614 struct av_decision *avd,
615 struct avc_xperms_node *xp_node)
616{
617 struct avc_node *pos, *node = NULL;
618 int hvalue;
619 unsigned long flag;
620
621 if (avc_latest_notif_update(avc, avd->seqno, 1))
622 goto out;
623
624 node = avc_alloc_node(avc);
625 if (node) {
626 struct hlist_head *head;
627 spinlock_t *lock;
628 int rc = 0;
629
630 hvalue = avc_hash(ssid, tsid, tclass);
631 avc_node_populate(node, ssid, tsid, tclass, avd);
632 rc = avc_xperms_populate(node, xp_node);
633 if (rc) {
634 kmem_cache_free(avc_node_cachep, node);
635 return NULL;
636 }
637 head = &avc->avc_cache.slots[hvalue];
638 lock = &avc->avc_cache.slots_lock[hvalue];
639
640 spin_lock_irqsave(lock, flag);
641 hlist_for_each_entry(pos, head, list) {
642 if (pos->ae.ssid == ssid &&
643 pos->ae.tsid == tsid &&
644 pos->ae.tclass == tclass) {
645 avc_node_replace(avc, node, pos);
646 goto found;
647 }
648 }
649 hlist_add_head_rcu(&node->list, head);
650found:
651 spin_unlock_irqrestore(lock, flag);
652 }
653out:
654 return node;
655}
656
657/**
658 * avc_audit_pre_callback - SELinux specific information
659 * will be called by generic audit code
660 * @ab: the audit buffer
661 * @a: audit_data
662 */
663static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
664{
665 struct common_audit_data *ad = a;
666 struct selinux_audit_data *sad = ad->selinux_audit_data;
667 u32 av = sad->audited;
668 const char **perms;
669 int i, perm;
670
671 audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
672
673 if (av == 0) {
674 audit_log_format(ab, " null");
675 return;
676 }
677
678 perms = secclass_map[sad->tclass-1].perms;
679
680 audit_log_format(ab, " {");
681 i = 0;
682 perm = 1;
683 while (i < (sizeof(av) * 8)) {
684 if ((perm & av) && perms[i]) {
685 audit_log_format(ab, " %s", perms[i]);
686 av &= ~perm;
687 }
688 i++;
689 perm <<= 1;
690 }
691
692 if (av)
693 audit_log_format(ab, " 0x%x", av);
694
695 audit_log_format(ab, " } for ");
696}
697
698/**
699 * avc_audit_post_callback - SELinux specific information
700 * will be called by generic audit code
701 * @ab: the audit buffer
702 * @a: audit_data
703 */
704static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
705{
706 struct common_audit_data *ad = a;
707 struct selinux_audit_data *sad = ad->selinux_audit_data;
708 char *scontext;
709 u32 scontext_len;
710 int rc;
711
712 rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
713 &scontext_len);
714 if (rc)
715 audit_log_format(ab, " ssid=%d", sad->ssid);
716 else {
717 audit_log_format(ab, " scontext=%s", scontext);
718 kfree(scontext);
719 }
720
721 rc = security_sid_to_context(sad->state, sad->tsid, &scontext,
722 &scontext_len);
723 if (rc)
724 audit_log_format(ab, " tsid=%d", sad->tsid);
725 else {
726 audit_log_format(ab, " tcontext=%s", scontext);
727 kfree(scontext);
728 }
729
730 audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name);
731
732 if (sad->denied)
733 audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
734
735 /* in case of invalid context report also the actual context string */
736 rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
737 &scontext_len);
738 if (!rc && scontext) {
739 if (scontext_len && scontext[scontext_len - 1] == '\0')
740 scontext_len--;
741 audit_log_format(ab, " srawcon=");
742 audit_log_n_untrustedstring(ab, scontext, scontext_len);
743 kfree(scontext);
744 }
745
746 rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
747 &scontext_len);
748 if (!rc && scontext) {
749 if (scontext_len && scontext[scontext_len - 1] == '\0')
750 scontext_len--;
751 audit_log_format(ab, " trawcon=");
752 audit_log_n_untrustedstring(ab, scontext, scontext_len);
753 kfree(scontext);
754 }
755}
756
757/* This is the slow part of avc audit with big stack footprint */
758noinline int slow_avc_audit(struct selinux_state *state,
759 u32 ssid, u32 tsid, u16 tclass,
760 u32 requested, u32 audited, u32 denied, int result,
761 struct common_audit_data *a,
762 unsigned int flags)
763{
764 struct common_audit_data stack_data;
765 struct selinux_audit_data sad;
766
767 if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
768 return -EINVAL;
769
770 if (!a) {
771 a = &stack_data;
772 a->type = LSM_AUDIT_DATA_NONE;
773 }
774
775 /*
776 * When in a RCU walk do the audit on the RCU retry. This is because
777 * the collection of the dname in an inode audit message is not RCU
778 * safe. Note this may drop some audits when the situation changes
779 * during retry. However this is logically just as if the operation
780 * happened a little later.
781 */
782 if ((a->type == LSM_AUDIT_DATA_INODE) &&
783 (flags & MAY_NOT_BLOCK))
784 return -ECHILD;
785
786 sad.tclass = tclass;
787 sad.requested = requested;
788 sad.ssid = ssid;
789 sad.tsid = tsid;
790 sad.audited = audited;
791 sad.denied = denied;
792 sad.result = result;
793 sad.state = state;
794
795 a->selinux_audit_data = &sad;
796
797 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
798 return 0;
799}
800
801/**
802 * avc_add_callback - Register a callback for security events.
803 * @callback: callback function
804 * @events: security events
805 *
806 * Register a callback function for events in the set @events.
807 * Returns %0 on success or -%ENOMEM if insufficient memory
808 * exists to add the callback.
809 */
810int __init avc_add_callback(int (*callback)(u32 event), u32 events)
811{
812 struct avc_callback_node *c;
813 int rc = 0;
814
815 c = kmalloc(sizeof(*c), GFP_KERNEL);
816 if (!c) {
817 rc = -ENOMEM;
818 goto out;
819 }
820
821 c->callback = callback;
822 c->events = events;
823 c->next = avc_callbacks;
824 avc_callbacks = c;
825out:
826 return rc;
827}
828
829/**
830 * avc_update_node Update an AVC entry
831 * @event : Updating event
832 * @perms : Permission mask bits
833 * @ssid,@tsid,@tclass : identifier of an AVC entry
834 * @seqno : sequence number when decision was made
835 * @xpd: extended_perms_decision to be added to the node
836 * @flags: the AVC_* flags, e.g. AVC_NONBLOCKING, AVC_EXTENDED_PERMS, or 0.
837 *
838 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
839 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
840 * otherwise, this function updates the AVC entry. The original AVC-entry object
841 * will release later by RCU.
842 */
843static int avc_update_node(struct selinux_avc *avc,
844 u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
845 u32 tsid, u16 tclass, u32 seqno,
846 struct extended_perms_decision *xpd,
847 u32 flags)
848{
849 int hvalue, rc = 0;
850 unsigned long flag;
851 struct avc_node *pos, *node, *orig = NULL;
852 struct hlist_head *head;
853 spinlock_t *lock;
854
855 /*
856 * If we are in a non-blocking code path, e.g. VFS RCU walk,
857 * then we must not add permissions to a cache entry
858 * because we cannot safely audit the denial. Otherwise,
859 * during the subsequent blocking retry (e.g. VFS ref walk), we
860 * will find the permissions already granted in the cache entry
861 * and won't audit anything at all, leading to silent denials in
862 * permissive mode that only appear when in enforcing mode.
863 *
864 * See the corresponding handling in slow_avc_audit(), and the
865 * logic in selinux_inode_permission for the MAY_NOT_BLOCK flag,
866 * which is transliterated into AVC_NONBLOCKING.
867 */
868 if (flags & AVC_NONBLOCKING)
869 return 0;
870
871 node = avc_alloc_node(avc);
872 if (!node) {
873 rc = -ENOMEM;
874 goto out;
875 }
876
877 /* Lock the target slot */
878 hvalue = avc_hash(ssid, tsid, tclass);
879
880 head = &avc->avc_cache.slots[hvalue];
881 lock = &avc->avc_cache.slots_lock[hvalue];
882
883 spin_lock_irqsave(lock, flag);
884
885 hlist_for_each_entry(pos, head, list) {
886 if (ssid == pos->ae.ssid &&
887 tsid == pos->ae.tsid &&
888 tclass == pos->ae.tclass &&
889 seqno == pos->ae.avd.seqno){
890 orig = pos;
891 break;
892 }
893 }
894
895 if (!orig) {
896 rc = -ENOENT;
897 avc_node_kill(avc, node);
898 goto out_unlock;
899 }
900
901 /*
902 * Copy and replace original node.
903 */
904
905 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
906
907 if (orig->ae.xp_node) {
908 rc = avc_xperms_populate(node, orig->ae.xp_node);
909 if (rc) {
910 kmem_cache_free(avc_node_cachep, node);
911 goto out_unlock;
912 }
913 }
914
915 switch (event) {
916 case AVC_CALLBACK_GRANT:
917 node->ae.avd.allowed |= perms;
918 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
919 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
920 break;
921 case AVC_CALLBACK_TRY_REVOKE:
922 case AVC_CALLBACK_REVOKE:
923 node->ae.avd.allowed &= ~perms;
924 break;
925 case AVC_CALLBACK_AUDITALLOW_ENABLE:
926 node->ae.avd.auditallow |= perms;
927 break;
928 case AVC_CALLBACK_AUDITALLOW_DISABLE:
929 node->ae.avd.auditallow &= ~perms;
930 break;
931 case AVC_CALLBACK_AUDITDENY_ENABLE:
932 node->ae.avd.auditdeny |= perms;
933 break;
934 case AVC_CALLBACK_AUDITDENY_DISABLE:
935 node->ae.avd.auditdeny &= ~perms;
936 break;
937 case AVC_CALLBACK_ADD_XPERMS:
938 avc_add_xperms_decision(node, xpd);
939 break;
940 }
941 avc_node_replace(avc, node, orig);
942out_unlock:
943 spin_unlock_irqrestore(lock, flag);
944out:
945 return rc;
946}
947
948/**
949 * avc_flush - Flush the cache
950 */
951static void avc_flush(struct selinux_avc *avc)
952{
953 struct hlist_head *head;
954 struct avc_node *node;
955 spinlock_t *lock;
956 unsigned long flag;
957 int i;
958
959 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
960 head = &avc->avc_cache.slots[i];
961 lock = &avc->avc_cache.slots_lock[i];
962
963 spin_lock_irqsave(lock, flag);
964 /*
965 * With preemptable RCU, the outer spinlock does not
966 * prevent RCU grace periods from ending.
967 */
968 rcu_read_lock();
969 hlist_for_each_entry(node, head, list)
970 avc_node_delete(avc, node);
971 rcu_read_unlock();
972 spin_unlock_irqrestore(lock, flag);
973 }
974}
975
976/**
977 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
978 * @seqno: policy sequence number
979 */
980int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
981{
982 struct avc_callback_node *c;
983 int rc = 0, tmprc;
984
985 avc_flush(avc);
986
987 for (c = avc_callbacks; c; c = c->next) {
988 if (c->events & AVC_CALLBACK_RESET) {
989 tmprc = c->callback(AVC_CALLBACK_RESET);
990 /* save the first error encountered for the return
991 value and continue processing the callbacks */
992 if (!rc)
993 rc = tmprc;
994 }
995 }
996
997 avc_latest_notif_update(avc, seqno, 0);
998 return rc;
999}
1000
1001/*
1002 * Slow-path helper function for avc_has_perm_noaudit,
1003 * when the avc_node lookup fails. We get called with
1004 * the RCU read lock held, and need to return with it
1005 * still held, but drop if for the security compute.
1006 *
1007 * Don't inline this, since it's the slow-path and just
1008 * results in a bigger stack frame.
1009 */
1010static noinline
1011struct avc_node *avc_compute_av(struct selinux_state *state,
1012 u32 ssid, u32 tsid,
1013 u16 tclass, struct av_decision *avd,
1014 struct avc_xperms_node *xp_node)
1015{
1016 rcu_read_unlock();
1017 INIT_LIST_HEAD(&xp_node->xpd_head);
1018 security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
1019 rcu_read_lock();
1020 return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
1021}
1022
1023static noinline int avc_denied(struct selinux_state *state,
1024 u32 ssid, u32 tsid,
1025 u16 tclass, u32 requested,
1026 u8 driver, u8 xperm, unsigned int flags,
1027 struct av_decision *avd)
1028{
1029 if (flags & AVC_STRICT)
1030 return -EACCES;
1031
1032 if (enforcing_enabled(state) &&
1033 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1034 return -EACCES;
1035
1036 avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
1037 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1038 return 0;
1039}
1040
1041/*
1042 * The avc extended permissions logic adds an additional 256 bits of
1043 * permissions to an avc node when extended permissions for that node are
1044 * specified in the avtab. If the additional 256 permissions is not adequate,
1045 * as-is the case with ioctls, then multiple may be chained together and the
1046 * driver field is used to specify which set contains the permission.
1047 */
1048int avc_has_extended_perms(struct selinux_state *state,
1049 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1050 u8 driver, u8 xperm, struct common_audit_data *ad)
1051{
1052 struct avc_node *node;
1053 struct av_decision avd;
1054 u32 denied;
1055 struct extended_perms_decision local_xpd;
1056 struct extended_perms_decision *xpd = NULL;
1057 struct extended_perms_data allowed;
1058 struct extended_perms_data auditallow;
1059 struct extended_perms_data dontaudit;
1060 struct avc_xperms_node local_xp_node;
1061 struct avc_xperms_node *xp_node;
1062 int rc = 0, rc2;
1063
1064 xp_node = &local_xp_node;
1065 if (WARN_ON(!requested))
1066 return -EACCES;
1067
1068 rcu_read_lock();
1069
1070 node = avc_lookup(state->avc, ssid, tsid, tclass);
1071 if (unlikely(!node)) {
1072 node = avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
1073 } else {
1074 memcpy(&avd, &node->ae.avd, sizeof(avd));
1075 xp_node = node->ae.xp_node;
1076 }
1077 /* if extended permissions are not defined, only consider av_decision */
1078 if (!xp_node || !xp_node->xp.len)
1079 goto decision;
1080
1081 local_xpd.allowed = &allowed;
1082 local_xpd.auditallow = &auditallow;
1083 local_xpd.dontaudit = &dontaudit;
1084
1085 xpd = avc_xperms_decision_lookup(driver, xp_node);
1086 if (unlikely(!xpd)) {
1087 /*
1088 * Compute the extended_perms_decision only if the driver
1089 * is flagged
1090 */
1091 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1092 avd.allowed &= ~requested;
1093 goto decision;
1094 }
1095 rcu_read_unlock();
1096 security_compute_xperms_decision(state, ssid, tsid, tclass,
1097 driver, &local_xpd);
1098 rcu_read_lock();
1099 avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
1100 driver, xperm, ssid, tsid, tclass, avd.seqno,
1101 &local_xpd, 0);
1102 } else {
1103 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1104 }
1105 xpd = &local_xpd;
1106
1107 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1108 avd.allowed &= ~requested;
1109
1110decision:
1111 denied = requested & ~(avd.allowed);
1112 if (unlikely(denied))
1113 rc = avc_denied(state, ssid, tsid, tclass, requested,
1114 driver, xperm, AVC_EXTENDED_PERMS, &avd);
1115
1116 rcu_read_unlock();
1117
1118 rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
1119 &avd, xpd, xperm, rc, ad);
1120 if (rc2)
1121 return rc2;
1122 return rc;
1123}
1124
1125/**
1126 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1127 * @ssid: source security identifier
1128 * @tsid: target security identifier
1129 * @tclass: target security class
1130 * @requested: requested permissions, interpreted based on @tclass
1131 * @flags: AVC_STRICT, AVC_NONBLOCKING, or 0
1132 * @avd: access vector decisions
1133 *
1134 * Check the AVC to determine whether the @requested permissions are granted
1135 * for the SID pair (@ssid, @tsid), interpreting the permissions
1136 * based on @tclass, and call the security server on a cache miss to obtain
1137 * a new decision and add it to the cache. Return a copy of the decisions
1138 * in @avd. Return %0 if all @requested permissions are granted,
1139 * -%EACCES if any permissions are denied, or another -errno upon
1140 * other errors. This function is typically called by avc_has_perm(),
1141 * but may also be called directly to separate permission checking from
1142 * auditing, e.g. in cases where a lock must be held for the check but
1143 * should be released for the auditing.
1144 */
1145inline int avc_has_perm_noaudit(struct selinux_state *state,
1146 u32 ssid, u32 tsid,
1147 u16 tclass, u32 requested,
1148 unsigned int flags,
1149 struct av_decision *avd)
1150{
1151 struct avc_node *node;
1152 struct avc_xperms_node xp_node;
1153 int rc = 0;
1154 u32 denied;
1155
1156 if (WARN_ON(!requested))
1157 return -EACCES;
1158
1159 rcu_read_lock();
1160
1161 node = avc_lookup(state->avc, ssid, tsid, tclass);
1162 if (unlikely(!node))
1163 node = avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
1164 else
1165 memcpy(avd, &node->ae.avd, sizeof(*avd));
1166
1167 denied = requested & ~(avd->allowed);
1168 if (unlikely(denied))
1169 rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
1170 flags, avd);
1171
1172 rcu_read_unlock();
1173 return rc;
1174}
1175
1176/**
1177 * avc_has_perm - Check permissions and perform any appropriate auditing.
1178 * @ssid: source security identifier
1179 * @tsid: target security identifier
1180 * @tclass: target security class
1181 * @requested: requested permissions, interpreted based on @tclass
1182 * @auditdata: auxiliary audit data
1183 *
1184 * Check the AVC to determine whether the @requested permissions are granted
1185 * for the SID pair (@ssid, @tsid), interpreting the permissions
1186 * based on @tclass, and call the security server on a cache miss to obtain
1187 * a new decision and add it to the cache. Audit the granting or denial of
1188 * permissions in accordance with the policy. Return %0 if all @requested
1189 * permissions are granted, -%EACCES if any permissions are denied, or
1190 * another -errno upon other errors.
1191 */
1192int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
1193 u32 requested, struct common_audit_data *auditdata)
1194{
1195 struct av_decision avd;
1196 int rc, rc2;
1197
1198 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1199 &avd);
1200
1201 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1202 auditdata, 0);
1203 if (rc2)
1204 return rc2;
1205 return rc;
1206}
1207
1208u32 avc_policy_seqno(struct selinux_state *state)
1209{
1210 return state->avc->avc_cache.latest_notif;
1211}
1212
1213void avc_disable(void)
1214{
1215 /*
1216 * If you are looking at this because you have realized that we are
1217 * not destroying the avc_node_cachep it might be easy to fix, but
1218 * I don't know the memory barrier semantics well enough to know. It's
1219 * possible that some other task dereferenced security_ops when
1220 * it still pointed to selinux operations. If that is the case it's
1221 * possible that it is about to use the avc and is about to need the
1222 * avc_node_cachep. I know I could wrap the security.c security_ops call
1223 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1224 * the cache and get that memory back.
1225 */
1226 if (avc_node_cachep) {
1227 avc_flush(selinux_state.avc);
1228 /* kmem_cache_destroy(avc_node_cachep); */
1229 }
1230}