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1da177e4
LT
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
5c458998 35static const struct av_perm_to_string av_perm_to_string[] = {
1da177e4
LT
36#define S_(c, v, s) { c, v, s },
37#include "av_perm_to_string.h"
38#undef S_
39};
40
1da177e4
LT
41static const char *class_to_string[] = {
42#define S_(s) s,
43#include "class_to_string.h"
44#undef S_
45};
1da177e4
LT
46
47#define TB_(s) static const char * s [] = {
48#define TE_(s) };
49#define S_(s) s,
50#include "common_perm_to_string.h"
51#undef TB_
52#undef TE_
53#undef S_
54
5c458998 55static const struct av_inherit av_inherit[] = {
1da177e4
LT
56#define S_(c, i, b) { c, common_##i##_perm_to_string, b },
57#include "av_inherit.h"
58#undef S_
59};
60
5c458998
CS
61const struct selinux_class_perm selinux_class_perm = {
62 av_perm_to_string,
63 ARRAY_SIZE(av_perm_to_string),
64 class_to_string,
65 ARRAY_SIZE(class_to_string),
66 av_inherit,
67 ARRAY_SIZE(av_inherit)
68};
69
1da177e4
LT
70#define AVC_CACHE_SLOTS 512
71#define AVC_DEF_CACHE_THRESHOLD 512
72#define AVC_CACHE_RECLAIM 16
73
74#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
75#define avc_cache_stats_incr(field) \
76do { \
77 per_cpu(avc_cache_stats, get_cpu()).field++; \
78 put_cpu(); \
79} while (0)
80#else
81#define avc_cache_stats_incr(field) do {} while (0)
82#endif
83
84struct avc_entry {
85 u32 ssid;
86 u32 tsid;
87 u16 tclass;
88 struct av_decision avd;
89 atomic_t used; /* used recently */
90};
91
92struct avc_node {
93 struct avc_entry ae;
94 struct list_head list;
95 struct rcu_head rhead;
96};
97
98struct avc_cache {
99 struct list_head slots[AVC_CACHE_SLOTS];
100 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
101 atomic_t lru_hint; /* LRU hint for reclaim scan */
102 atomic_t active_nodes;
103 u32 latest_notif; /* latest revocation notification */
104};
105
106struct avc_callback_node {
107 int (*callback) (u32 event, u32 ssid, u32 tsid,
108 u16 tclass, u32 perms,
109 u32 *out_retained);
110 u32 events;
111 u32 ssid;
112 u32 tsid;
113 u16 tclass;
114 u32 perms;
115 struct avc_callback_node *next;
116};
117
118/* Exported via selinufs */
119unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
120
121#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
122DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
123#endif
124
125static struct avc_cache avc_cache;
126static struct avc_callback_node *avc_callbacks;
e18b890b 127static struct kmem_cache *avc_node_cachep;
1da177e4
LT
128
129static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
130{
131 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
132}
133
134/**
135 * avc_dump_av - Display an access vector in human-readable form.
136 * @tclass: target security class
137 * @av: access vector
138 */
139static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
140{
141 const char **common_pts = NULL;
142 u32 common_base = 0;
143 int i, i2, perm;
144
145 if (av == 0) {
146 audit_log_format(ab, " null");
147 return;
148 }
149
150 for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
151 if (av_inherit[i].tclass == tclass) {
152 common_pts = av_inherit[i].common_pts;
153 common_base = av_inherit[i].common_base;
154 break;
155 }
156 }
157
158 audit_log_format(ab, " {");
159 i = 0;
160 perm = 1;
161 while (perm < common_base) {
162 if (perm & av) {
163 audit_log_format(ab, " %s", common_pts[i]);
164 av &= ~perm;
165 }
166 i++;
167 perm <<= 1;
168 }
169
170 while (i < sizeof(av) * 8) {
171 if (perm & av) {
172 for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
173 if ((av_perm_to_string[i2].tclass == tclass) &&
174 (av_perm_to_string[i2].value == perm))
175 break;
176 }
177 if (i2 < ARRAY_SIZE(av_perm_to_string)) {
178 audit_log_format(ab, " %s",
179 av_perm_to_string[i2].name);
180 av &= ~perm;
181 }
182 }
183 i++;
184 perm <<= 1;
185 }
186
187 if (av)
188 audit_log_format(ab, " 0x%x", av);
189
190 audit_log_format(ab, " }");
191}
192
193/**
194 * avc_dump_query - Display a SID pair and a class in human-readable form.
195 * @ssid: source security identifier
196 * @tsid: target security identifier
197 * @tclass: target security class
198 */
199static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
200{
201 int rc;
202 char *scontext;
203 u32 scontext_len;
204
205 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
206 if (rc)
207 audit_log_format(ab, "ssid=%d", ssid);
208 else {
209 audit_log_format(ab, "scontext=%s", scontext);
210 kfree(scontext);
211 }
212
213 rc = security_sid_to_context(tsid, &scontext, &scontext_len);
214 if (rc)
215 audit_log_format(ab, " tsid=%d", tsid);
216 else {
217 audit_log_format(ab, " tcontext=%s", scontext);
218 kfree(scontext);
219 }
a764ae4b
SS
220
221 BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]);
1da177e4
LT
222 audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
223}
224
225/**
226 * avc_init - Initialize the AVC.
227 *
228 * Initialize the access vector cache.
229 */
230void __init avc_init(void)
231{
232 int i;
233
234 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
235 INIT_LIST_HEAD(&avc_cache.slots[i]);
236 spin_lock_init(&avc_cache.slots_lock[i]);
237 }
238 atomic_set(&avc_cache.active_nodes, 0);
239 atomic_set(&avc_cache.lru_hint, 0);
240
241 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
20c2df83 242 0, SLAB_PANIC, NULL);
1da177e4 243
9ad9ad38 244 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
1da177e4
LT
245}
246
247int avc_get_hash_stats(char *page)
248{
249 int i, chain_len, max_chain_len, slots_used;
250 struct avc_node *node;
251
252 rcu_read_lock();
253
254 slots_used = 0;
255 max_chain_len = 0;
256 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
257 if (!list_empty(&avc_cache.slots[i])) {
258 slots_used++;
259 chain_len = 0;
260 list_for_each_entry_rcu(node, &avc_cache.slots[i], list)
261 chain_len++;
262 if (chain_len > max_chain_len)
263 max_chain_len = chain_len;
264 }
265 }
266
267 rcu_read_unlock();
268
269 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
270 "longest chain: %d\n",
271 atomic_read(&avc_cache.active_nodes),
272 slots_used, AVC_CACHE_SLOTS, max_chain_len);
273}
274
275static void avc_node_free(struct rcu_head *rhead)
276{
277 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
278 kmem_cache_free(avc_node_cachep, node);
279 avc_cache_stats_incr(frees);
280}
281
282static void avc_node_delete(struct avc_node *node)
283{
284 list_del_rcu(&node->list);
285 call_rcu(&node->rhead, avc_node_free);
286 atomic_dec(&avc_cache.active_nodes);
287}
288
289static void avc_node_kill(struct avc_node *node)
290{
291 kmem_cache_free(avc_node_cachep, node);
292 avc_cache_stats_incr(frees);
293 atomic_dec(&avc_cache.active_nodes);
294}
295
296static void avc_node_replace(struct avc_node *new, struct avc_node *old)
297{
298 list_replace_rcu(&old->list, &new->list);
299 call_rcu(&old->rhead, avc_node_free);
300 atomic_dec(&avc_cache.active_nodes);
301}
302
303static inline int avc_reclaim_node(void)
304{
305 struct avc_node *node;
306 int hvalue, try, ecx;
307 unsigned long flags;
308
309 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++ ) {
310 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
311
312 if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
313 continue;
314
315 list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
316 if (atomic_dec_and_test(&node->ae.used)) {
317 /* Recently Unused */
318 avc_node_delete(node);
319 avc_cache_stats_incr(reclaims);
320 ecx++;
321 if (ecx >= AVC_CACHE_RECLAIM) {
322 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
323 goto out;
324 }
325 }
326 }
327 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
328 }
329out:
330 return ecx;
331}
332
333static struct avc_node *avc_alloc_node(void)
334{
335 struct avc_node *node;
336
c3762229 337 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
1da177e4
LT
338 if (!node)
339 goto out;
340
1da177e4
LT
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
349out:
350 return node;
351}
352
353static 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
361static 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);
384out:
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 */
402static 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);
416out:
417 return node;
418}
419
420static 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 */
459static 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]);
483found:
484 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
485 }
486out:
487 return node;
488}
489
490static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
b5bf6c55 491 struct in6_addr *addr, __be16 port,
1da177e4
LT
492 char *name1, char *name2)
493{
494 if (!ipv6_addr_any(addr))
46b86a2d 495 audit_log_format(ab, " %s=" NIP6_FMT, name1, NIP6(*addr));
1da177e4
LT
496 if (port)
497 audit_log_format(ab, " %s=%d", name2, ntohs(port));
498}
499
87fcd70d 500static inline void avc_print_ipv4_addr(struct audit_buffer *ab, __be32 addr,
b5bf6c55 501 __be16 port, char *name1, char *name2)
1da177e4
LT
502{
503 if (addr)
46b86a2d 504 audit_log_format(ab, " %s=" NIPQUAD_FMT, name1, NIPQUAD(addr));
1da177e4
LT
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 */
528void avc_audit(u32 ssid, u32 tsid,
529 u16 tclass, u32 requested,
530 struct av_decision *avd, int result, struct avc_audit_data *a)
531{
cd77b821 532 struct task_struct *tsk = current;
1da177e4
LT
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
9ad9ad38 550 ab = audit_log_start(current->audit_context, GFP_ATOMIC, AUDIT_AVC);
1da177e4
LT
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 ");
cd77b821
DW
556 if (a && a->tsk)
557 tsk = a->tsk;
7b5d781c 558 if (tsk && tsk->pid) {
cd77b821
DW
559 audit_log_format(ab, " pid=%d comm=", tsk->pid);
560 audit_log_untrustedstring(ab, tsk->comm);
561 }
1da177e4
LT
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;
4259fa01
AV
573 if (a->u.fs.mnt) {
574 audit_log_d_path(ab, "path=", dentry, a->u.fs.mnt);
575 } else {
576 audit_log_format(ab, " name=");
577 audit_log_untrustedstring(ab, dentry->d_name.name);
578 }
1da177e4
LT
579 inode = dentry->d_inode;
580 } else if (a->u.fs.inode) {
581 struct dentry *dentry;
582 inode = a->u.fs.inode;
583 dentry = d_find_alias(inode);
584 if (dentry) {
37ca5389
SS
585 audit_log_format(ab, " name=");
586 audit_log_untrustedstring(ab, dentry->d_name.name);
1da177e4
LT
587 dput(dentry);
588 }
589 }
590 if (inode)
13bddc2e 591 audit_log_format(ab, " dev=%s ino=%lu",
1da177e4
LT
592 inode->i_sb->s_id,
593 inode->i_ino);
594 break;
595 case AVC_AUDIT_DATA_NET:
596 if (a->u.net.sk) {
597 struct sock *sk = a->u.net.sk;
598 struct unix_sock *u;
599 int len = 0;
600 char *p = NULL;
601
602 switch (sk->sk_family) {
603 case AF_INET: {
604 struct inet_sock *inet = inet_sk(sk);
605
606 avc_print_ipv4_addr(ab, inet->rcv_saddr,
607 inet->sport,
608 "laddr", "lport");
609 avc_print_ipv4_addr(ab, inet->daddr,
610 inet->dport,
611 "faddr", "fport");
612 break;
613 }
614 case AF_INET6: {
615 struct inet_sock *inet = inet_sk(sk);
616 struct ipv6_pinfo *inet6 = inet6_sk(sk);
617
618 avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
619 inet->sport,
620 "laddr", "lport");
621 avc_print_ipv6_addr(ab, &inet6->daddr,
622 inet->dport,
623 "faddr", "fport");
624 break;
625 }
626 case AF_UNIX:
627 u = unix_sk(sk);
628 if (u->dentry) {
4259fa01
AV
629 audit_log_d_path(ab, "path=",
630 u->dentry, u->mnt);
1da177e4
LT
631 break;
632 }
633 if (!u->addr)
634 break;
635 len = u->addr->len-sizeof(short);
636 p = &u->addr->name->sun_path[0];
37ca5389 637 audit_log_format(ab, " path=");
1da177e4 638 if (*p)
37ca5389 639 audit_log_untrustedstring(ab, p);
1da177e4 640 else
37ca5389 641 audit_log_hex(ab, p, len);
1da177e4
LT
642 break;
643 }
644 }
645
646 switch (a->u.net.family) {
647 case AF_INET:
648 avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
649 a->u.net.sport,
650 "saddr", "src");
651 avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
652 a->u.net.dport,
653 "daddr", "dest");
654 break;
655 case AF_INET6:
656 avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
657 a->u.net.sport,
658 "saddr", "src");
659 avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
660 a->u.net.dport,
661 "daddr", "dest");
662 break;
663 }
664 if (a->u.net.netif)
665 audit_log_format(ab, " netif=%s",
666 a->u.net.netif);
667 break;
668 }
669 }
670 audit_log_format(ab, " ");
671 avc_dump_query(ab, ssid, tsid, tclass);
672 audit_log_end(ab);
673}
674
675/**
676 * avc_add_callback - Register a callback for security events.
677 * @callback: callback function
678 * @events: security events
679 * @ssid: source security identifier or %SECSID_WILD
680 * @tsid: target security identifier or %SECSID_WILD
681 * @tclass: target security class
682 * @perms: permissions
683 *
684 * Register a callback function for events in the set @events
685 * related to the SID pair (@ssid, @tsid) and
686 * and the permissions @perms, interpreting
687 * @perms based on @tclass. Returns %0 on success or
688 * -%ENOMEM if insufficient memory exists to add the callback.
689 */
690int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
691 u16 tclass, u32 perms,
692 u32 *out_retained),
693 u32 events, u32 ssid, u32 tsid,
694 u16 tclass, u32 perms)
695{
696 struct avc_callback_node *c;
697 int rc = 0;
698
699 c = kmalloc(sizeof(*c), GFP_ATOMIC);
700 if (!c) {
701 rc = -ENOMEM;
702 goto out;
703 }
704
705 c->callback = callback;
706 c->events = events;
707 c->ssid = ssid;
708 c->tsid = tsid;
709 c->perms = perms;
710 c->next = avc_callbacks;
711 avc_callbacks = c;
712out:
713 return rc;
714}
715
716static inline int avc_sidcmp(u32 x, u32 y)
717{
718 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
719}
720
721/**
722 * avc_update_node Update an AVC entry
723 * @event : Updating event
724 * @perms : Permission mask bits
725 * @ssid,@tsid,@tclass : identifier of an AVC entry
726 *
727 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
728 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
729 * otherwise, this function update the AVC entry. The original AVC-entry object
730 * will release later by RCU.
731 */
732static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
733{
734 int hvalue, rc = 0;
735 unsigned long flag;
736 struct avc_node *pos, *node, *orig = NULL;
737
738 node = avc_alloc_node();
739 if (!node) {
740 rc = -ENOMEM;
741 goto out;
742 }
743
744 /* Lock the target slot */
745 hvalue = avc_hash(ssid, tsid, tclass);
746 spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
747
748 list_for_each_entry(pos, &avc_cache.slots[hvalue], list){
749 if ( ssid==pos->ae.ssid &&
750 tsid==pos->ae.tsid &&
751 tclass==pos->ae.tclass ){
752 orig = pos;
753 break;
754 }
755 }
756
757 if (!orig) {
758 rc = -ENOENT;
759 avc_node_kill(node);
760 goto out_unlock;
761 }
762
763 /*
764 * Copy and replace original node.
765 */
766
767 avc_node_populate(node, ssid, tsid, tclass, &orig->ae);
768
769 switch (event) {
770 case AVC_CALLBACK_GRANT:
771 node->ae.avd.allowed |= perms;
772 break;
773 case AVC_CALLBACK_TRY_REVOKE:
774 case AVC_CALLBACK_REVOKE:
775 node->ae.avd.allowed &= ~perms;
776 break;
777 case AVC_CALLBACK_AUDITALLOW_ENABLE:
778 node->ae.avd.auditallow |= perms;
779 break;
780 case AVC_CALLBACK_AUDITALLOW_DISABLE:
781 node->ae.avd.auditallow &= ~perms;
782 break;
783 case AVC_CALLBACK_AUDITDENY_ENABLE:
784 node->ae.avd.auditdeny |= perms;
785 break;
786 case AVC_CALLBACK_AUDITDENY_DISABLE:
787 node->ae.avd.auditdeny &= ~perms;
788 break;
789 }
790 avc_node_replace(node, orig);
791out_unlock:
792 spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
793out:
794 return rc;
795}
796
797/**
798 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
799 * @seqno: policy sequence number
800 */
801int avc_ss_reset(u32 seqno)
802{
803 struct avc_callback_node *c;
376bd9cb 804 int i, rc = 0, tmprc;
1da177e4
LT
805 unsigned long flag;
806 struct avc_node *node;
807
808 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
809 spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
810 list_for_each_entry(node, &avc_cache.slots[i], list)
811 avc_node_delete(node);
812 spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
813 }
814
815 for (c = avc_callbacks; c; c = c->next) {
816 if (c->events & AVC_CALLBACK_RESET) {
376bd9cb
DG
817 tmprc = c->callback(AVC_CALLBACK_RESET,
818 0, 0, 0, 0, NULL);
819 /* save the first error encountered for the return
820 value and continue processing the callbacks */
821 if (!rc)
822 rc = tmprc;
1da177e4
LT
823 }
824 }
825
826 avc_latest_notif_update(seqno, 0);
1da177e4
LT
827 return rc;
828}
829
830/**
831 * avc_has_perm_noaudit - Check permissions but perform no auditing.
832 * @ssid: source security identifier
833 * @tsid: target security identifier
834 * @tclass: target security class
835 * @requested: requested permissions, interpreted based on @tclass
2c3c05db 836 * @flags: AVC_STRICT or 0
1da177e4
LT
837 * @avd: access vector decisions
838 *
839 * Check the AVC to determine whether the @requested permissions are granted
840 * for the SID pair (@ssid, @tsid), interpreting the permissions
841 * based on @tclass, and call the security server on a cache miss to obtain
842 * a new decision and add it to the cache. Return a copy of the decisions
843 * in @avd. Return %0 if all @requested permissions are granted,
844 * -%EACCES if any permissions are denied, or another -errno upon
845 * other errors. This function is typically called by avc_has_perm(),
846 * but may also be called directly to separate permission checking from
847 * auditing, e.g. in cases where a lock must be held for the check but
848 * should be released for the auditing.
849 */
850int avc_has_perm_noaudit(u32 ssid, u32 tsid,
2c3c05db
SS
851 u16 tclass, u32 requested,
852 unsigned flags,
853 struct av_decision *avd)
1da177e4
LT
854{
855 struct avc_node *node;
856 struct avc_entry entry, *p_ae;
857 int rc = 0;
858 u32 denied;
859
860 rcu_read_lock();
861
862 node = avc_lookup(ssid, tsid, tclass, requested);
863 if (!node) {
864 rcu_read_unlock();
865 rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd);
866 if (rc)
867 goto out;
868 rcu_read_lock();
869 node = avc_insert(ssid,tsid,tclass,&entry);
870 }
871
872 p_ae = node ? &node->ae : &entry;
873
874 if (avd)
875 memcpy(avd, &p_ae->avd, sizeof(*avd));
876
877 denied = requested & ~(p_ae->avd.allowed);
878
879 if (!requested || denied) {
2c3c05db 880 if (selinux_enforcing || (flags & AVC_STRICT))
1da177e4
LT
881 rc = -EACCES;
882 else
883 if (node)
884 avc_update_node(AVC_CALLBACK_GRANT,requested,
885 ssid,tsid,tclass);
886 }
887
888 rcu_read_unlock();
889out:
890 return rc;
891}
892
893/**
894 * avc_has_perm - Check permissions and perform any appropriate auditing.
895 * @ssid: source security identifier
896 * @tsid: target security identifier
897 * @tclass: target security class
898 * @requested: requested permissions, interpreted based on @tclass
899 * @auditdata: auxiliary audit data
900 *
901 * Check the AVC to determine whether the @requested permissions are granted
902 * for the SID pair (@ssid, @tsid), interpreting the permissions
903 * based on @tclass, and call the security server on a cache miss to obtain
904 * a new decision and add it to the cache. Audit the granting or denial of
905 * permissions in accordance with the policy. Return %0 if all @requested
906 * permissions are granted, -%EACCES if any permissions are denied, or
907 * another -errno upon other errors.
908 */
909int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
910 u32 requested, struct avc_audit_data *auditdata)
911{
912 struct av_decision avd;
913 int rc;
914
2c3c05db 915 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
1da177e4
LT
916 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
917 return rc;
918}