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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
35 static const struct av_perm_to_string
36 {
37 u16 tclass;
38 u32 value;
39 const char *name;
40 } av_perm_to_string[] = {
41 #define S_(c, v, s) { c, v, s },
42 #include "av_perm_to_string.h"
43 #undef S_
44 };
45
46 static const char *class_to_string[] = {
47 #define S_(s) s,
48 #include "class_to_string.h"
49 #undef S_
50 };
51
52 #define TB_(s) static const char * s [] = {
53 #define TE_(s) };
54 #define S_(s) s,
55 #include "common_perm_to_string.h"
56 #undef TB_
57 #undef TE_
58 #undef S_
59
60 static const struct av_inherit
61 {
62 u16 tclass;
63 const char **common_pts;
64 u32 common_base;
65 } av_inherit[] = {
66 #define S_(c, i, b) { c, common_##i##_perm_to_string, b },
67 #include "av_inherit.h"
68 #undef S_
69 };
70
71 #define AVC_CACHE_SLOTS 512
72 #define AVC_DEF_CACHE_THRESHOLD 512
73 #define AVC_CACHE_RECLAIM 16
74
75 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
76 #define avc_cache_stats_incr(field) \
77 do { \
78 per_cpu(avc_cache_stats, get_cpu()).field++; \
79 put_cpu(); \
80 } while (0)
81 #else
82 #define avc_cache_stats_incr(field) do {} while (0)
83 #endif
84
85 struct avc_entry {
86 u32 ssid;
87 u32 tsid;
88 u16 tclass;
89 struct av_decision avd;
90 atomic_t used; /* used recently */
91 };
92
93 struct avc_node {
94 struct avc_entry ae;
95 struct list_head list;
96 struct rcu_head rhead;
97 };
98
99 struct avc_cache {
100 struct list_head slots[AVC_CACHE_SLOTS];
101 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
102 atomic_t lru_hint; /* LRU hint for reclaim scan */
103 atomic_t active_nodes;
104 u32 latest_notif; /* latest revocation notification */
105 };
106
107 struct avc_callback_node {
108 int (*callback) (u32 event, u32 ssid, u32 tsid,
109 u16 tclass, u32 perms,
110 u32 *out_retained);
111 u32 events;
112 u32 ssid;
113 u32 tsid;
114 u16 tclass;
115 u32 perms;
116 struct avc_callback_node *next;
117 };
118
119 /* Exported via selinufs */
120 unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
121
122 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
123 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
124 #endif
125
126 static struct avc_cache avc_cache;
127 static struct avc_callback_node *avc_callbacks;
128 static kmem_cache_t *avc_node_cachep;
129
130 static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
131 {
132 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
133 }
134
135 /**
136 * avc_dump_av - Display an access vector in human-readable form.
137 * @tclass: target security class
138 * @av: access vector
139 */
140 static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
141 {
142 const char **common_pts = NULL;
143 u32 common_base = 0;
144 int i, i2, perm;
145
146 if (av == 0) {
147 audit_log_format(ab, " null");
148 return;
149 }
150
151 for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
152 if (av_inherit[i].tclass == tclass) {
153 common_pts = av_inherit[i].common_pts;
154 common_base = av_inherit[i].common_base;
155 break;
156 }
157 }
158
159 audit_log_format(ab, " {");
160 i = 0;
161 perm = 1;
162 while (perm < common_base) {
163 if (perm & av) {
164 audit_log_format(ab, " %s", common_pts[i]);
165 av &= ~perm;
166 }
167 i++;
168 perm <<= 1;
169 }
170
171 while (i < sizeof(av) * 8) {
172 if (perm & av) {
173 for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
174 if ((av_perm_to_string[i2].tclass == tclass) &&
175 (av_perm_to_string[i2].value == perm))
176 break;
177 }
178 if (i2 < ARRAY_SIZE(av_perm_to_string)) {
179 audit_log_format(ab, " %s",
180 av_perm_to_string[i2].name);
181 av &= ~perm;
182 }
183 }
184 i++;
185 perm <<= 1;
186 }
187
188 if (av)
189 audit_log_format(ab, " 0x%x", av);
190
191 audit_log_format(ab, " }");
192 }
193
194 /**
195 * avc_dump_query - Display a SID pair and a class in human-readable form.
196 * @ssid: source security identifier
197 * @tsid: target security identifier
198 * @tclass: target security class
199 */
200 static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
201 {
202 int rc;
203 char *scontext;
204 u32 scontext_len;
205
206 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
207 if (rc)
208 audit_log_format(ab, "ssid=%d", ssid);
209 else {
210 audit_log_format(ab, "scontext=%s", scontext);
211 kfree(scontext);
212 }
213
214 rc = security_sid_to_context(tsid, &scontext, &scontext_len);
215 if (rc)
216 audit_log_format(ab, " tsid=%d", tsid);
217 else {
218 audit_log_format(ab, " tcontext=%s", scontext);
219 kfree(scontext);
220 }
221 audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
222 }
223
224 /**
225 * avc_init - Initialize the AVC.
226 *
227 * Initialize the access vector cache.
228 */
229 void __init avc_init(void)
230 {
231 int i;
232
233 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
234 INIT_LIST_HEAD(&avc_cache.slots[i]);
235 spin_lock_init(&avc_cache.slots_lock[i]);
236 }
237 atomic_set(&avc_cache.active_nodes, 0);
238 atomic_set(&avc_cache.lru_hint, 0);
239
240 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
241 0, SLAB_PANIC, NULL, NULL);
242
243 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
244 }
245
246 int avc_get_hash_stats(char *page)
247 {
248 int i, chain_len, max_chain_len, slots_used;
249 struct avc_node *node;
250
251 rcu_read_lock();
252
253 slots_used = 0;
254 max_chain_len = 0;
255 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
256 if (!list_empty(&avc_cache.slots[i])) {
257 slots_used++;
258 chain_len = 0;
259 list_for_each_entry_rcu(node, &avc_cache.slots[i], list)
260 chain_len++;
261 if (chain_len > max_chain_len)
262 max_chain_len = chain_len;
263 }
264 }
265
266 rcu_read_unlock();
267
268 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
269 "longest chain: %d\n",
270 atomic_read(&avc_cache.active_nodes),
271 slots_used, AVC_CACHE_SLOTS, max_chain_len);
272 }
273
274 static void avc_node_free(struct rcu_head *rhead)
275 {
276 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
277 kmem_cache_free(avc_node_cachep, node);
278 avc_cache_stats_incr(frees);
279 }
280
281 static void avc_node_delete(struct avc_node *node)
282 {
283 list_del_rcu(&node->list);
284 call_rcu(&node->rhead, avc_node_free);
285 atomic_dec(&avc_cache.active_nodes);
286 }
287
288 static void avc_node_kill(struct avc_node *node)
289 {
290 kmem_cache_free(avc_node_cachep, node);
291 avc_cache_stats_incr(frees);
292 atomic_dec(&avc_cache.active_nodes);
293 }
294
295 static void avc_node_replace(struct avc_node *new, struct avc_node *old)
296 {
297 list_replace_rcu(&old->list, &new->list);
298 call_rcu(&old->rhead, avc_node_free);
299 atomic_dec(&avc_cache.active_nodes);
300 }
301
302 static inline int avc_reclaim_node(void)
303 {
304 struct avc_node *node;
305 int hvalue, try, ecx;
306 unsigned long flags;
307
308 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++ ) {
309 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
310
311 if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
312 continue;
313
314 list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
315 if (atomic_dec_and_test(&node->ae.used)) {
316 /* Recently Unused */
317 avc_node_delete(node);
318 avc_cache_stats_incr(reclaims);
319 ecx++;
320 if (ecx >= AVC_CACHE_RECLAIM) {
321 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
322 goto out;
323 }
324 }
325 }
326 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
327 }
328 out:
329 return ecx;
330 }
331
332 static struct avc_node *avc_alloc_node(void)
333 {
334 struct avc_node *node;
335
336 node = kmem_cache_alloc(avc_node_cachep, SLAB_ATOMIC);
337 if (!node)
338 goto out;
339
340 memset(node, 0, sizeof(*node));
341 INIT_RCU_HEAD(&node->rhead);
342 INIT_LIST_HEAD(&node->list);
343 atomic_set(&node->ae.used, 1);
344 avc_cache_stats_incr(allocations);
345
346 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
347 avc_reclaim_node();
348
349 out:
350 return node;
351 }
352
353 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
354 {
355 node->ae.ssid = ssid;
356 node->ae.tsid = tsid;
357 node->ae.tclass = tclass;
358 memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd));
359 }
360
361 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
362 {
363 struct avc_node *node, *ret = NULL;
364 int hvalue;
365
366 hvalue = avc_hash(ssid, tsid, tclass);
367 list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) {
368 if (ssid == node->ae.ssid &&
369 tclass == node->ae.tclass &&
370 tsid == node->ae.tsid) {
371 ret = node;
372 break;
373 }
374 }
375
376 if (ret == NULL) {
377 /* cache miss */
378 goto out;
379 }
380
381 /* cache hit */
382 if (atomic_read(&ret->ae.used) != 1)
383 atomic_set(&ret->ae.used, 1);
384 out:
385 return ret;
386 }
387
388 /**
389 * avc_lookup - Look up an AVC entry.
390 * @ssid: source security identifier
391 * @tsid: target security identifier
392 * @tclass: target security class
393 * @requested: requested permissions, interpreted based on @tclass
394 *
395 * Look up an AVC entry that is valid for the
396 * @requested permissions between the SID pair
397 * (@ssid, @tsid), interpreting the permissions
398 * based on @tclass. If a valid AVC entry exists,
399 * then this function return the avc_node.
400 * Otherwise, this function returns NULL.
401 */
402 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested)
403 {
404 struct avc_node *node;
405
406 avc_cache_stats_incr(lookups);
407 node = avc_search_node(ssid, tsid, tclass);
408
409 if (node && ((node->ae.avd.decided & requested) == requested)) {
410 avc_cache_stats_incr(hits);
411 goto out;
412 }
413
414 node = NULL;
415 avc_cache_stats_incr(misses);
416 out:
417 return node;
418 }
419
420 static int avc_latest_notif_update(int seqno, int is_insert)
421 {
422 int ret = 0;
423 static DEFINE_SPINLOCK(notif_lock);
424 unsigned long flag;
425
426 spin_lock_irqsave(&notif_lock, flag);
427 if (is_insert) {
428 if (seqno < avc_cache.latest_notif) {
429 printk(KERN_WARNING "avc: seqno %d < latest_notif %d\n",
430 seqno, avc_cache.latest_notif);
431 ret = -EAGAIN;
432 }
433 } else {
434 if (seqno > avc_cache.latest_notif)
435 avc_cache.latest_notif = seqno;
436 }
437 spin_unlock_irqrestore(&notif_lock, flag);
438
439 return ret;
440 }
441
442 /**
443 * avc_insert - Insert an AVC entry.
444 * @ssid: source security identifier
445 * @tsid: target security identifier
446 * @tclass: target security class
447 * @ae: AVC entry
448 *
449 * Insert an AVC entry for the SID pair
450 * (@ssid, @tsid) and class @tclass.
451 * The access vectors and the sequence number are
452 * normally provided by the security server in
453 * response to a security_compute_av() call. If the
454 * sequence number @ae->avd.seqno is not less than the latest
455 * revocation notification, then the function copies
456 * the access vectors into a cache entry, returns
457 * avc_node inserted. Otherwise, this function returns NULL.
458 */
459 static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
460 {
461 struct avc_node *pos, *node = NULL;
462 int hvalue;
463 unsigned long flag;
464
465 if (avc_latest_notif_update(ae->avd.seqno, 1))
466 goto out;
467
468 node = avc_alloc_node();
469 if (node) {
470 hvalue = avc_hash(ssid, tsid, tclass);
471 avc_node_populate(node, ssid, tsid, tclass, ae);
472
473 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
474 list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
475 if (pos->ae.ssid == ssid &&
476 pos->ae.tsid == tsid &&
477 pos->ae.tclass == tclass) {
478 avc_node_replace(node, pos);
479 goto found;
480 }
481 }
482 list_add_rcu(&node->list, &avc_cache.slots[hvalue]);
483 found:
484 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
485 }
486 out:
487 return node;
488 }
489
490 static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
491 struct in6_addr *addr, __be16 port,
492 char *name1, char *name2)
493 {
494 if (!ipv6_addr_any(addr))
495 audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr));
496 if (port)
497 audit_log_format(ab, " %s=%d", name2, ntohs(port));
498 }
499
500 static inline void avc_print_ipv4_addr(struct audit_buffer *ab, u32 addr,
501 __be16 port, char *name1, char *name2)
502 {
503 if (addr)
504 audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr));
505 if (port)
506 audit_log_format(ab, " %s=%d", name2, ntohs(port));
507 }
508
509 /**
510 * avc_audit - Audit the granting or denial of permissions.
511 * @ssid: source security identifier
512 * @tsid: target security identifier
513 * @tclass: target security class
514 * @requested: requested permissions
515 * @avd: access vector decisions
516 * @result: result from avc_has_perm_noaudit
517 * @a: auxiliary audit data
518 *
519 * Audit the granting or denial of permissions in accordance
520 * with the policy. This function is typically called by
521 * avc_has_perm() after a permission check, but can also be
522 * called directly by callers who use avc_has_perm_noaudit()
523 * in order to separate the permission check from the auditing.
524 * For example, this separation is useful when the permission check must
525 * be performed under a lock, to allow the lock to be released
526 * before calling the auditing code.
527 */
528 void avc_audit(u32 ssid, u32 tsid,
529 u16 tclass, u32 requested,
530 struct av_decision *avd, int result, struct avc_audit_data *a)
531 {
532 struct task_struct *tsk = current;
533 struct inode *inode = NULL;
534 u32 denied, audited;
535 struct audit_buffer *ab;
536
537 denied = requested & ~avd->allowed;
538 if (denied) {
539 audited = denied;
540 if (!(audited & avd->auditdeny))
541 return;
542 } else if (result) {
543 audited = denied = requested;
544 } else {
545 audited = requested;
546 if (!(audited & avd->auditallow))
547 return;
548 }
549
550 ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
551 if (!ab)
552 return; /* audit_panic has been called */
553 audit_log_format(ab, "avc: %s ", denied ? "denied" : "granted");
554 avc_dump_av(ab, tclass,audited);
555 audit_log_format(ab, " for ");
556 if (a && a->tsk)
557 tsk = a->tsk;
558 if (tsk && tsk->pid) {
559 audit_log_format(ab, " pid=%d comm=", tsk->pid);
560 audit_log_untrustedstring(ab, tsk->comm);
561 }
562 if (a) {
563 switch (a->type) {
564 case AVC_AUDIT_DATA_IPC:
565 audit_log_format(ab, " key=%d", a->u.ipc_id);
566 break;
567 case AVC_AUDIT_DATA_CAP:
568 audit_log_format(ab, " capability=%d", a->u.cap);
569 break;
570 case AVC_AUDIT_DATA_FS:
571 if (a->u.fs.dentry) {
572 struct dentry *dentry = a->u.fs.dentry;
573 if (a->u.fs.mnt)
574 audit_avc_path(dentry, a->u.fs.mnt);
575 audit_log_format(ab, " name=");
576 audit_log_untrustedstring(ab, dentry->d_name.name);
577 inode = dentry->d_inode;
578 } else if (a->u.fs.inode) {
579 struct dentry *dentry;
580 inode = a->u.fs.inode;
581 dentry = d_find_alias(inode);
582 if (dentry) {
583 audit_log_format(ab, " name=");
584 audit_log_untrustedstring(ab, dentry->d_name.name);
585 dput(dentry);
586 }
587 }
588 if (inode)
589 audit_log_format(ab, " dev=%s ino=%ld",
590 inode->i_sb->s_id,
591 inode->i_ino);
592 break;
593 case AVC_AUDIT_DATA_NET:
594 if (a->u.net.sk) {
595 struct sock *sk = a->u.net.sk;
596 struct unix_sock *u;
597 int len = 0;
598 char *p = NULL;
599
600 switch (sk->sk_family) {
601 case AF_INET: {
602 struct inet_sock *inet = inet_sk(sk);
603
604 avc_print_ipv4_addr(ab, inet->rcv_saddr,
605 inet->sport,
606 "laddr", "lport");
607 avc_print_ipv4_addr(ab, inet->daddr,
608 inet->dport,
609 "faddr", "fport");
610 break;
611 }
612 case AF_INET6: {
613 struct inet_sock *inet = inet_sk(sk);
614 struct ipv6_pinfo *inet6 = inet6_sk(sk);
615
616 avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
617 inet->sport,
618 "laddr", "lport");
619 avc_print_ipv6_addr(ab, &inet6->daddr,
620 inet->dport,
621 "faddr", "fport");
622 break;
623 }
624 case AF_UNIX:
625 u = unix_sk(sk);
626 if (u->dentry) {
627 audit_avc_path(u->dentry, u->mnt);
628 audit_log_format(ab, " name=");
629 audit_log_untrustedstring(ab, u->dentry->d_name.name);
630 break;
631 }
632 if (!u->addr)
633 break;
634 len = u->addr->len-sizeof(short);
635 p = &u->addr->name->sun_path[0];
636 audit_log_format(ab, " path=");
637 if (*p)
638 audit_log_untrustedstring(ab, p);
639 else
640 audit_log_hex(ab, p, len);
641 break;
642 }
643 }
644
645 switch (a->u.net.family) {
646 case AF_INET:
647 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
648 a->u.net.sport,
649 "saddr", "src");
650 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
651 a->u.net.dport,
652 "daddr", "dest");
653 break;
654 case AF_INET6:
655 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
656 a->u.net.sport,
657 "saddr", "src");
658 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
659 a->u.net.dport,
660 "daddr", "dest");
661 break;
662 }
663 if (a->u.net.netif)
664 audit_log_format(ab, " netif=%s",
665 a->u.net.netif);
666 break;
667 }
668 }
669 audit_log_format(ab, " ");
670 avc_dump_query(ab, ssid, tsid, tclass);
671 audit_log_end(ab);
672 }
673
674 /**
675 * avc_add_callback - Register a callback for security events.
676 * @callback: callback function
677 * @events: security events
678 * @ssid: source security identifier or %SECSID_WILD
679 * @tsid: target security identifier or %SECSID_WILD
680 * @tclass: target security class
681 * @perms: permissions
682 *
683 * Register a callback function for events in the set @events
684 * related to the SID pair (@ssid, @tsid) and
685 * and the permissions @perms, interpreting
686 * @perms based on @tclass. Returns %0 on success or
687 * -%ENOMEM if insufficient memory exists to add the callback.
688 */
689 int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
690 u16 tclass, u32 perms,
691 u32 *out_retained),
692 u32 events, u32 ssid, u32 tsid,
693 u16 tclass, u32 perms)
694 {
695 struct avc_callback_node *c;
696 int rc = 0;
697
698 c = kmalloc(sizeof(*c), GFP_ATOMIC);
699 if (!c) {
700 rc = -ENOMEM;
701 goto out;
702 }
703
704 c->callback = callback;
705 c->events = events;
706 c->ssid = ssid;
707 c->tsid = tsid;
708 c->perms = perms;
709 c->next = avc_callbacks;
710 avc_callbacks = c;
711 out:
712 return rc;
713 }
714
715 static inline int avc_sidcmp(u32 x, u32 y)
716 {
717 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
718 }
719
720 /**
721 * avc_update_node Update an AVC entry
722 * @event : Updating event
723 * @perms : Permission mask bits
724 * @ssid,@tsid,@tclass : identifier of an AVC entry
725 *
726 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
727 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
728 * otherwise, this function update the AVC entry. The original AVC-entry object
729 * will release later by RCU.
730 */
731 static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
732 {
733 int hvalue, rc = 0;
734 unsigned long flag;
735 struct avc_node *pos, *node, *orig = NULL;
736
737 node = avc_alloc_node();
738 if (!node) {
739 rc = -ENOMEM;
740 goto out;
741 }
742
743 /* Lock the target slot */
744 hvalue = avc_hash(ssid, tsid, tclass);
745 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
746
747 list_for_each_entry(pos, &avc_cache.slots[hvalue], list){
748 if ( ssid==pos->ae.ssid &&
749 tsid==pos->ae.tsid &&
750 tclass==pos->ae.tclass ){
751 orig = pos;
752 break;
753 }
754 }
755
756 if (!orig) {
757 rc = -ENOENT;
758 avc_node_kill(node);
759 goto out_unlock;
760 }
761
762 /*
763 * Copy and replace original node.
764 */
765
766 avc_node_populate(node, ssid, tsid, tclass, &orig->ae);
767
768 switch (event) {
769 case AVC_CALLBACK_GRANT:
770 node->ae.avd.allowed |= perms;
771 break;
772 case AVC_CALLBACK_TRY_REVOKE:
773 case AVC_CALLBACK_REVOKE:
774 node->ae.avd.allowed &= ~perms;
775 break;
776 case AVC_CALLBACK_AUDITALLOW_ENABLE:
777 node->ae.avd.auditallow |= perms;
778 break;
779 case AVC_CALLBACK_AUDITALLOW_DISABLE:
780 node->ae.avd.auditallow &= ~perms;
781 break;
782 case AVC_CALLBACK_AUDITDENY_ENABLE:
783 node->ae.avd.auditdeny |= perms;
784 break;
785 case AVC_CALLBACK_AUDITDENY_DISABLE:
786 node->ae.avd.auditdeny &= ~perms;
787 break;
788 }
789 avc_node_replace(node, orig);
790 out_unlock:
791 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
792 out:
793 return rc;
794 }
795
796 /**
797 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
798 * @seqno: policy sequence number
799 */
800 int avc_ss_reset(u32 seqno)
801 {
802 struct avc_callback_node *c;
803 int i, rc = 0, tmprc;
804 unsigned long flag;
805 struct avc_node *node;
806
807 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
808 spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
809 list_for_each_entry(node, &avc_cache.slots[i], list)
810 avc_node_delete(node);
811 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
812 }
813
814 for (c = avc_callbacks; c; c = c->next) {
815 if (c->events & AVC_CALLBACK_RESET) {
816 tmprc = c->callback(AVC_CALLBACK_RESET,
817 0, 0, 0, 0, NULL);
818 /* save the first error encountered for the return
819 value and continue processing the callbacks */
820 if (!rc)
821 rc = tmprc;
822 }
823 }
824
825 avc_latest_notif_update(seqno, 0);
826 return rc;
827 }
828
829 /**
830 * avc_has_perm_noaudit - Check permissions but perform no auditing.
831 * @ssid: source security identifier
832 * @tsid: target security identifier
833 * @tclass: target security class
834 * @requested: requested permissions, interpreted based on @tclass
835 * @avd: access vector decisions
836 *
837 * Check the AVC to determine whether the @requested permissions are granted
838 * for the SID pair (@ssid, @tsid), interpreting the permissions
839 * based on @tclass, and call the security server on a cache miss to obtain
840 * a new decision and add it to the cache. Return a copy of the decisions
841 * in @avd. Return %0 if all @requested permissions are granted,
842 * -%EACCES if any permissions are denied, or another -errno upon
843 * other errors. This function is typically called by avc_has_perm(),
844 * but may also be called directly to separate permission checking from
845 * auditing, e.g. in cases where a lock must be held for the check but
846 * should be released for the auditing.
847 */
848 int avc_has_perm_noaudit(u32 ssid, u32 tsid,
849 u16 tclass, u32 requested,
850 struct av_decision *avd)
851 {
852 struct avc_node *node;
853 struct avc_entry entry, *p_ae;
854 int rc = 0;
855 u32 denied;
856
857 rcu_read_lock();
858
859 node = avc_lookup(ssid, tsid, tclass, requested);
860 if (!node) {
861 rcu_read_unlock();
862 rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd);
863 if (rc)
864 goto out;
865 rcu_read_lock();
866 node = avc_insert(ssid,tsid,tclass,&entry);
867 }
868
869 p_ae = node ? &node->ae : &entry;
870
871 if (avd)
872 memcpy(avd, &p_ae->avd, sizeof(*avd));
873
874 denied = requested & ~(p_ae->avd.allowed);
875
876 if (!requested || denied) {
877 if (selinux_enforcing)
878 rc = -EACCES;
879 else
880 if (node)
881 avc_update_node(AVC_CALLBACK_GRANT,requested,
882 ssid,tsid,tclass);
883 }
884
885 rcu_read_unlock();
886 out:
887 return rc;
888 }
889
890 /**
891 * avc_has_perm - Check permissions and perform any appropriate auditing.
892 * @ssid: source security identifier
893 * @tsid: target security identifier
894 * @tclass: target security class
895 * @requested: requested permissions, interpreted based on @tclass
896 * @auditdata: auxiliary audit data
897 *
898 * Check the AVC to determine whether the @requested permissions are granted
899 * for the SID pair (@ssid, @tsid), interpreting the permissions
900 * based on @tclass, and call the security server on a cache miss to obtain
901 * a new decision and add it to the cache. Audit the granting or denial of
902 * permissions in accordance with the policy. Return %0 if all @requested
903 * permissions are granted, -%EACCES if any permissions are denied, or
904 * another -errno upon other errors.
905 */
906 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
907 u32 requested, struct avc_audit_data *auditdata)
908 {
909 struct av_decision avd;
910 int rc;
911
912 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, &avd);
913 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
914 return rc;
915 }