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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Implementation of the kernel access vector cache (AVC).
3 *
4 * Authors: Stephen Smalley, <sds@epoch.ncsc.mil>
Eric Paris95fff332008-04-17 14:42:10 -04005 * James Morris <jmorris@redhat.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 *
7 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
Eric Paris95fff332008-04-17 14:42:10 -04008 * Replaced the avc_lock spinlock by RCU.
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 *
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,
Eric Paris95fff332008-04-17 14:42:10 -040014 * as published by the Free Software Foundation.
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 */
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
Chad Sellers5c458992006-11-06 12:38:16 -050035static const struct av_perm_to_string av_perm_to_string[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070036#define S_(c, v, s) { c, v, s },
37#include "av_perm_to_string.h"
38#undef S_
39};
40
Linus Torvalds1da177e2005-04-16 15:20:36 -070041static const char *class_to_string[] = {
42#define S_(s) s,
43#include "class_to_string.h"
44#undef S_
45};
Linus Torvalds1da177e2005-04-16 15:20:36 -070046
Eric Paris95fff332008-04-17 14:42:10 -040047#define TB_(s) static const char *s[] = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070048#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
Chad Sellers5c458992006-11-06 12:38:16 -050055static const struct av_inherit av_inherit[] = {
Eric Paris76f7ba32009-01-02 17:40:06 -050056#define S_(c, i, b) { .tclass = c,\
57 .common_pts = common_##i##_perm_to_string,\
58 .common_base = b },
Linus Torvalds1da177e2005-04-16 15:20:36 -070059#include "av_inherit.h"
60#undef S_
61};
62
Chad Sellers5c458992006-11-06 12:38:16 -050063const struct selinux_class_perm selinux_class_perm = {
Eric Paris76f7ba32009-01-02 17:40:06 -050064 .av_perm_to_string = av_perm_to_string,
65 .av_pts_len = ARRAY_SIZE(av_perm_to_string),
66 .class_to_string = class_to_string,
67 .cts_len = ARRAY_SIZE(class_to_string),
68 .av_inherit = av_inherit,
69 .av_inherit_len = ARRAY_SIZE(av_inherit)
Chad Sellers5c458992006-11-06 12:38:16 -050070};
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072#define AVC_CACHE_SLOTS 512
73#define AVC_DEF_CACHE_THRESHOLD 512
74#define AVC_CACHE_RECLAIM 16
75
76#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
Eric Paris95fff332008-04-17 14:42:10 -040077#define avc_cache_stats_incr(field) \
Linus Torvalds1da177e2005-04-16 15:20:36 -070078do { \
79 per_cpu(avc_cache_stats, get_cpu()).field++; \
80 put_cpu(); \
81} while (0)
82#else
83#define avc_cache_stats_incr(field) do {} while (0)
84#endif
85
86struct avc_entry {
87 u32 ssid;
88 u32 tsid;
89 u16 tclass;
90 struct av_decision avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070091};
92
93struct avc_node {
94 struct avc_entry ae;
Eric Paris26036652009-02-12 14:51:04 -050095 struct hlist_node list; /* anchored in avc_cache->slots[i] */
Eric Paris95fff332008-04-17 14:42:10 -040096 struct rcu_head rhead;
Linus Torvalds1da177e2005-04-16 15:20:36 -070097};
98
99struct avc_cache {
Eric Paris26036652009-02-12 14:51:04 -0500100 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 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
107struct avc_callback_node {
108 int (*callback) (u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400109 u16 tclass, u32 perms,
110 u32 *out_retained);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 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 */
120unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
121
122#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
123DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
124#endif
125
126static struct avc_cache avc_cache;
127static struct avc_callback_node *avc_callbacks;
Christoph Lametere18b8902006-12-06 20:33:20 -0800128static struct kmem_cache *avc_node_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
130static 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 */
KaiGai Kohei44c2d9b2009-06-18 17:26:13 +0900140static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141{
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 */
200static 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
Eric Paris95fff332008-04-17 14:42:10 -0400206 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207 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 }
Stephen Smalleya764ae42007-03-26 13:36:26 -0400221
222 BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
224}
225
226/**
227 * avc_init - Initialize the AVC.
228 *
229 * Initialize the access vector cache.
230 */
231void __init avc_init(void)
232{
233 int i;
234
235 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Paris26036652009-02-12 14:51:04 -0500236 INIT_HLIST_HEAD(&avc_cache.slots[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 spin_lock_init(&avc_cache.slots_lock[i]);
238 }
239 atomic_set(&avc_cache.active_nodes, 0);
240 atomic_set(&avc_cache.lru_hint, 0);
241
242 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
Paul Mundt20c2df82007-07-20 10:11:58 +0900243 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244
David Woodhouse9ad9ad32005-06-22 15:04:33 +0100245 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246}
247
248int avc_get_hash_stats(char *page)
249{
250 int i, chain_len, max_chain_len, slots_used;
251 struct avc_node *node;
Eric Paris26036652009-02-12 14:51:04 -0500252 struct hlist_head *head;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253
254 rcu_read_lock();
255
256 slots_used = 0;
257 max_chain_len = 0;
258 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500259 head = &avc_cache.slots[i];
Eric Paris26036652009-02-12 14:51:04 -0500260 if (!hlist_empty(head)) {
261 struct hlist_node *next;
262
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 slots_used++;
264 chain_len = 0;
Eric Paris26036652009-02-12 14:51:04 -0500265 hlist_for_each_entry_rcu(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 chain_len++;
267 if (chain_len > max_chain_len)
268 max_chain_len = chain_len;
269 }
270 }
271
272 rcu_read_unlock();
273
274 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
275 "longest chain: %d\n",
276 atomic_read(&avc_cache.active_nodes),
277 slots_used, AVC_CACHE_SLOTS, max_chain_len);
278}
279
280static void avc_node_free(struct rcu_head *rhead)
281{
282 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
283 kmem_cache_free(avc_node_cachep, node);
284 avc_cache_stats_incr(frees);
285}
286
287static void avc_node_delete(struct avc_node *node)
288{
Eric Paris26036652009-02-12 14:51:04 -0500289 hlist_del_rcu(&node->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 call_rcu(&node->rhead, avc_node_free);
291 atomic_dec(&avc_cache.active_nodes);
292}
293
294static void avc_node_kill(struct avc_node *node)
295{
296 kmem_cache_free(avc_node_cachep, node);
297 avc_cache_stats_incr(frees);
298 atomic_dec(&avc_cache.active_nodes);
299}
300
301static void avc_node_replace(struct avc_node *new, struct avc_node *old)
302{
Eric Paris26036652009-02-12 14:51:04 -0500303 hlist_replace_rcu(&old->list, &new->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304 call_rcu(&old->rhead, avc_node_free);
305 atomic_dec(&avc_cache.active_nodes);
306}
307
308static inline int avc_reclaim_node(void)
309{
310 struct avc_node *node;
311 int hvalue, try, ecx;
312 unsigned long flags;
Eric Paris26036652009-02-12 14:51:04 -0500313 struct hlist_head *head;
314 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500315 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
Eric Paris95fff332008-04-17 14:42:10 -0400317 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
Eric Parisedf3d1a2009-02-12 14:50:59 -0500319 head = &avc_cache.slots[hvalue];
320 lock = &avc_cache.slots_lock[hvalue];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700321
Eric Parisedf3d1a2009-02-12 14:50:59 -0500322 if (!spin_trylock_irqsave(lock, flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 continue;
324
Paul E. McKenney61844252008-04-21 18:12:33 -0700325 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500326 hlist_for_each_entry(node, next, head, list) {
Eric Paris906d27d2009-02-12 14:50:43 -0500327 avc_node_delete(node);
328 avc_cache_stats_incr(reclaims);
329 ecx++;
330 if (ecx >= AVC_CACHE_RECLAIM) {
331 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500332 spin_unlock_irqrestore(lock, flags);
Eric Paris906d27d2009-02-12 14:50:43 -0500333 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 }
335 }
Paul E. McKenney61844252008-04-21 18:12:33 -0700336 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500337 spin_unlock_irqrestore(lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 }
339out:
340 return ecx;
341}
342
343static struct avc_node *avc_alloc_node(void)
344{
345 struct avc_node *node;
346
Robert P. J. Dayc3762222007-02-10 01:45:03 -0800347 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 if (!node)
349 goto out;
350
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 INIT_RCU_HEAD(&node->rhead);
Eric Paris26036652009-02-12 14:51:04 -0500352 INIT_HLIST_NODE(&node->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353 avc_cache_stats_incr(allocations);
354
355 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
356 avc_reclaim_node();
357
358out:
359 return node;
360}
361
Eric Paris21193dc2009-02-12 14:50:49 -0500362static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363{
364 node->ae.ssid = ssid;
365 node->ae.tsid = tsid;
366 node->ae.tclass = tclass;
Eric Paris21193dc2009-02-12 14:50:49 -0500367 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368}
369
370static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
371{
372 struct avc_node *node, *ret = NULL;
373 int hvalue;
Eric Paris26036652009-02-12 14:51:04 -0500374 struct hlist_head *head;
375 struct hlist_node *next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
377 hvalue = avc_hash(ssid, tsid, tclass);
Eric Parisedf3d1a2009-02-12 14:50:59 -0500378 head = &avc_cache.slots[hvalue];
Eric Paris26036652009-02-12 14:51:04 -0500379 hlist_for_each_entry_rcu(node, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 if (ssid == node->ae.ssid &&
381 tclass == node->ae.tclass &&
382 tsid == node->ae.tsid) {
383 ret = node;
384 break;
385 }
386 }
387
Linus Torvalds1da177e2005-04-16 15:20:36 -0700388 return ret;
389}
390
391/**
392 * avc_lookup - Look up an AVC entry.
393 * @ssid: source security identifier
394 * @tsid: target security identifier
395 * @tclass: target security class
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 *
397 * Look up an AVC entry that is valid for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 * (@ssid, @tsid), interpreting the permissions
399 * based on @tclass. If a valid AVC entry exists,
400 * then this function return the avc_node.
401 * Otherwise, this function returns NULL.
402 */
Eric Parisf1c63812009-02-12 14:50:54 -0500403static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404{
405 struct avc_node *node;
406
407 avc_cache_stats_incr(lookups);
408 node = avc_search_node(ssid, tsid, tclass);
409
Eric Parisf1c63812009-02-12 14:50:54 -0500410 if (node)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 avc_cache_stats_incr(hits);
Eric Parisf1c63812009-02-12 14:50:54 -0500412 else
413 avc_cache_stats_incr(misses);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415 return node;
416}
417
418static int avc_latest_notif_update(int seqno, int is_insert)
419{
420 int ret = 0;
421 static DEFINE_SPINLOCK(notif_lock);
422 unsigned long flag;
423
424 spin_lock_irqsave(&notif_lock, flag);
425 if (is_insert) {
426 if (seqno < avc_cache.latest_notif) {
Eric Paris744ba352008-04-17 11:52:44 -0400427 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428 seqno, avc_cache.latest_notif);
429 ret = -EAGAIN;
430 }
431 } else {
432 if (seqno > avc_cache.latest_notif)
433 avc_cache.latest_notif = seqno;
434 }
435 spin_unlock_irqrestore(&notif_lock, flag);
436
437 return ret;
438}
439
440/**
441 * avc_insert - Insert an AVC entry.
442 * @ssid: source security identifier
443 * @tsid: target security identifier
444 * @tclass: target security class
Eric Paris21193dc2009-02-12 14:50:49 -0500445 * @avd: resulting av decision
Linus Torvalds1da177e2005-04-16 15:20:36 -0700446 *
447 * Insert an AVC entry for the SID pair
448 * (@ssid, @tsid) and class @tclass.
449 * The access vectors and the sequence number are
450 * normally provided by the security server in
451 * response to a security_compute_av() call. If the
Eric Paris21193dc2009-02-12 14:50:49 -0500452 * sequence number @avd->seqno is not less than the latest
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453 * revocation notification, then the function copies
454 * the access vectors into a cache entry, returns
455 * avc_node inserted. Otherwise, this function returns NULL.
456 */
Eric Paris21193dc2009-02-12 14:50:49 -0500457static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458{
459 struct avc_node *pos, *node = NULL;
460 int hvalue;
461 unsigned long flag;
462
Eric Paris21193dc2009-02-12 14:50:49 -0500463 if (avc_latest_notif_update(avd->seqno, 1))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 goto out;
465
466 node = avc_alloc_node();
467 if (node) {
Eric Paris26036652009-02-12 14:51:04 -0500468 struct hlist_head *head;
469 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500470 spinlock_t *lock;
471
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 hvalue = avc_hash(ssid, tsid, tclass);
Eric Paris21193dc2009-02-12 14:50:49 -0500473 avc_node_populate(node, ssid, tsid, tclass, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474
Eric Parisedf3d1a2009-02-12 14:50:59 -0500475 head = &avc_cache.slots[hvalue];
476 lock = &avc_cache.slots_lock[hvalue];
477
478 spin_lock_irqsave(lock, flag);
Eric Paris26036652009-02-12 14:51:04 -0500479 hlist_for_each_entry(pos, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480 if (pos->ae.ssid == ssid &&
481 pos->ae.tsid == tsid &&
482 pos->ae.tclass == tclass) {
Eric Paris95fff332008-04-17 14:42:10 -0400483 avc_node_replace(node, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484 goto found;
485 }
486 }
Eric Paris26036652009-02-12 14:51:04 -0500487 hlist_add_head_rcu(&node->list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488found:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500489 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 }
491out:
492 return node;
493}
494
Thomas Liu2bf49692009-07-14 12:14:09 -0400495/**
496 * avc_audit_pre_callback - SELinux specific information
497 * will be called by generic audit code
498 * @ab: the audit buffer
499 * @a: audit_data
500 */
501static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502{
Thomas Liu2bf49692009-07-14 12:14:09 -0400503 struct common_audit_data *ad = a;
504 audit_log_format(ab, "avc: %s ",
505 ad->selinux_audit_data.denied ? "denied" : "granted");
506 avc_dump_av(ab, ad->selinux_audit_data.tclass,
507 ad->selinux_audit_data.audited);
508 audit_log_format(ab, " for ");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700509}
510
Thomas Liu2bf49692009-07-14 12:14:09 -0400511/**
512 * avc_audit_post_callback - SELinux specific information
513 * will be called by generic audit code
514 * @ab: the audit buffer
515 * @a: audit_data
516 */
517static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518{
Thomas Liu2bf49692009-07-14 12:14:09 -0400519 struct common_audit_data *ad = a;
520 audit_log_format(ab, " ");
521 avc_dump_query(ab, ad->selinux_audit_data.ssid,
522 ad->selinux_audit_data.tsid,
523 ad->selinux_audit_data.tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524}
525
526/**
527 * avc_audit - Audit the granting or denial of permissions.
528 * @ssid: source security identifier
529 * @tsid: target security identifier
530 * @tclass: target security class
531 * @requested: requested permissions
532 * @avd: access vector decisions
533 * @result: result from avc_has_perm_noaudit
534 * @a: auxiliary audit data
535 *
536 * Audit the granting or denial of permissions in accordance
537 * with the policy. This function is typically called by
538 * avc_has_perm() after a permission check, but can also be
539 * called directly by callers who use avc_has_perm_noaudit()
540 * in order to separate the permission check from the auditing.
541 * For example, this separation is useful when the permission check must
542 * be performed under a lock, to allow the lock to be released
543 * before calling the auditing code.
544 */
545void avc_audit(u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400546 u16 tclass, u32 requested,
Thomas Liu2bf49692009-07-14 12:14:09 -0400547 struct av_decision *avd, int result, struct common_audit_data *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548{
Thomas Liu2bf49692009-07-14 12:14:09 -0400549 struct common_audit_data stack_data;
James Morrisbe940d62009-07-13 10:39:36 +1000550 u32 denied, audited;
James Morrisbe940d62009-07-13 10:39:36 +1000551 denied = requested & ~avd->allowed;
552 if (denied) {
553 audited = denied;
554 if (!(audited & avd->auditdeny))
555 return;
556 } else if (result) {
557 audited = denied = requested;
558 } else {
559 audited = requested;
560 if (!(audited & avd->auditallow))
561 return;
562 }
Thomas Liu2bf49692009-07-14 12:14:09 -0400563 if (!a) {
564 a = &stack_data;
565 memset(a, 0, sizeof(*a));
566 a->type = LSM_AUDIT_NO_AUDIT;
James Morrisbe940d62009-07-13 10:39:36 +1000567 }
Thomas Liu2bf49692009-07-14 12:14:09 -0400568 a->selinux_audit_data.tclass = tclass;
569 a->selinux_audit_data.requested = requested;
570 a->selinux_audit_data.ssid = ssid;
571 a->selinux_audit_data.tsid = tsid;
572 a->selinux_audit_data.audited = audited;
573 a->selinux_audit_data.denied = denied;
574 a->lsm_pre_audit = avc_audit_pre_callback;
575 a->lsm_post_audit = avc_audit_post_callback;
576 common_lsm_audit(a);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577}
578
579/**
580 * avc_add_callback - Register a callback for security events.
581 * @callback: callback function
582 * @events: security events
583 * @ssid: source security identifier or %SECSID_WILD
584 * @tsid: target security identifier or %SECSID_WILD
585 * @tclass: target security class
586 * @perms: permissions
587 *
588 * Register a callback function for events in the set @events
589 * related to the SID pair (@ssid, @tsid) and
590 * and the permissions @perms, interpreting
591 * @perms based on @tclass. Returns %0 on success or
592 * -%ENOMEM if insufficient memory exists to add the callback.
593 */
594int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400595 u16 tclass, u32 perms,
596 u32 *out_retained),
597 u32 events, u32 ssid, u32 tsid,
598 u16 tclass, u32 perms)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700599{
600 struct avc_callback_node *c;
601 int rc = 0;
602
603 c = kmalloc(sizeof(*c), GFP_ATOMIC);
604 if (!c) {
605 rc = -ENOMEM;
606 goto out;
607 }
608
609 c->callback = callback;
610 c->events = events;
611 c->ssid = ssid;
612 c->tsid = tsid;
613 c->perms = perms;
614 c->next = avc_callbacks;
615 avc_callbacks = c;
616out:
617 return rc;
618}
619
620static inline int avc_sidcmp(u32 x, u32 y)
621{
622 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
623}
624
625/**
626 * avc_update_node Update an AVC entry
627 * @event : Updating event
628 * @perms : Permission mask bits
629 * @ssid,@tsid,@tclass : identifier of an AVC entry
Eric Parisa5dda6832009-02-12 14:50:11 -0500630 * @seqno : sequence number when decision was made
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 *
632 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
633 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
634 * otherwise, this function update the AVC entry. The original AVC-entry object
635 * will release later by RCU.
636 */
Eric Parisa5dda6832009-02-12 14:50:11 -0500637static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
638 u32 seqno)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700639{
640 int hvalue, rc = 0;
641 unsigned long flag;
642 struct avc_node *pos, *node, *orig = NULL;
Eric Paris26036652009-02-12 14:51:04 -0500643 struct hlist_head *head;
644 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500645 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700646
647 node = avc_alloc_node();
648 if (!node) {
649 rc = -ENOMEM;
650 goto out;
651 }
652
653 /* Lock the target slot */
654 hvalue = avc_hash(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655
Eric Parisedf3d1a2009-02-12 14:50:59 -0500656 head = &avc_cache.slots[hvalue];
657 lock = &avc_cache.slots_lock[hvalue];
658
659 spin_lock_irqsave(lock, flag);
660
Eric Paris26036652009-02-12 14:51:04 -0500661 hlist_for_each_entry(pos, next, head, list) {
Eric Paris95fff332008-04-17 14:42:10 -0400662 if (ssid == pos->ae.ssid &&
663 tsid == pos->ae.tsid &&
Eric Parisa5dda6832009-02-12 14:50:11 -0500664 tclass == pos->ae.tclass &&
665 seqno == pos->ae.avd.seqno){
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 orig = pos;
667 break;
668 }
669 }
670
671 if (!orig) {
672 rc = -ENOENT;
673 avc_node_kill(node);
674 goto out_unlock;
675 }
676
677 /*
678 * Copy and replace original node.
679 */
680
Eric Paris21193dc2009-02-12 14:50:49 -0500681 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
683 switch (event) {
684 case AVC_CALLBACK_GRANT:
685 node->ae.avd.allowed |= perms;
686 break;
687 case AVC_CALLBACK_TRY_REVOKE:
688 case AVC_CALLBACK_REVOKE:
689 node->ae.avd.allowed &= ~perms;
690 break;
691 case AVC_CALLBACK_AUDITALLOW_ENABLE:
692 node->ae.avd.auditallow |= perms;
693 break;
694 case AVC_CALLBACK_AUDITALLOW_DISABLE:
695 node->ae.avd.auditallow &= ~perms;
696 break;
697 case AVC_CALLBACK_AUDITDENY_ENABLE:
698 node->ae.avd.auditdeny |= perms;
699 break;
700 case AVC_CALLBACK_AUDITDENY_DISABLE:
701 node->ae.avd.auditdeny &= ~perms;
702 break;
703 }
704 avc_node_replace(node, orig);
705out_unlock:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500706 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700707out:
708 return rc;
709}
710
711/**
Eric Paris008574b2009-09-12 22:54:17 -0400712 * avc_flush - Flush the cache
Linus Torvalds1da177e2005-04-16 15:20:36 -0700713 */
Eric Paris008574b2009-09-12 22:54:17 -0400714static void avc_flush(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715{
Eric Paris26036652009-02-12 14:51:04 -0500716 struct hlist_head *head;
717 struct hlist_node *next;
Eric Paris008574b2009-09-12 22:54:17 -0400718 struct avc_node *node;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500719 spinlock_t *lock;
Eric Paris008574b2009-09-12 22:54:17 -0400720 unsigned long flag;
721 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722
723 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500724 head = &avc_cache.slots[i];
725 lock = &avc_cache.slots_lock[i];
726
727 spin_lock_irqsave(lock, flag);
Paul E. McKenney61844252008-04-21 18:12:33 -0700728 /*
729 * With preemptable RCU, the outer spinlock does not
730 * prevent RCU grace periods from ending.
731 */
732 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500733 hlist_for_each_entry(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 avc_node_delete(node);
Paul E. McKenney61844252008-04-21 18:12:33 -0700735 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500736 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 }
Eric Paris008574b2009-09-12 22:54:17 -0400738}
739
740/**
741 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
742 * @seqno: policy sequence number
743 */
744int avc_ss_reset(u32 seqno)
745{
746 struct avc_callback_node *c;
747 int rc = 0, tmprc;
748
749 avc_flush();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700750
751 for (c = avc_callbacks; c; c = c->next) {
752 if (c->events & AVC_CALLBACK_RESET) {
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600753 tmprc = c->callback(AVC_CALLBACK_RESET,
Eric Paris95fff332008-04-17 14:42:10 -0400754 0, 0, 0, 0, NULL);
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600755 /* save the first error encountered for the return
756 value and continue processing the callbacks */
757 if (!rc)
758 rc = tmprc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 }
760 }
761
762 avc_latest_notif_update(seqno, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 return rc;
764}
765
766/**
767 * avc_has_perm_noaudit - Check permissions but perform no auditing.
768 * @ssid: source security identifier
769 * @tsid: target security identifier
770 * @tclass: target security class
771 * @requested: requested permissions, interpreted based on @tclass
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400772 * @flags: AVC_STRICT or 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 * @avd: access vector decisions
774 *
775 * Check the AVC to determine whether the @requested permissions are granted
776 * for the SID pair (@ssid, @tsid), interpreting the permissions
777 * based on @tclass, and call the security server on a cache miss to obtain
778 * a new decision and add it to the cache. Return a copy of the decisions
779 * in @avd. Return %0 if all @requested permissions are granted,
780 * -%EACCES if any permissions are denied, or another -errno upon
781 * other errors. This function is typically called by avc_has_perm(),
782 * but may also be called directly to separate permission checking from
783 * auditing, e.g. in cases where a lock must be held for the check but
784 * should be released for the auditing.
785 */
786int avc_has_perm_noaudit(u32 ssid, u32 tsid,
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400787 u16 tclass, u32 requested,
788 unsigned flags,
Eric Paris21193dc2009-02-12 14:50:49 -0500789 struct av_decision *in_avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790{
791 struct avc_node *node;
Eric Paris21193dc2009-02-12 14:50:49 -0500792 struct av_decision avd_entry, *avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700793 int rc = 0;
794 u32 denied;
795
Eric Pariseda4f692008-03-11 14:19:34 -0400796 BUG_ON(!requested);
797
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 rcu_read_lock();
799
Eric Parisf1c63812009-02-12 14:50:54 -0500800 node = avc_lookup(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 if (!node) {
802 rcu_read_unlock();
Eric Paris21193dc2009-02-12 14:50:49 -0500803
804 if (in_avd)
805 avd = in_avd;
806 else
807 avd = &avd_entry;
808
809 rc = security_compute_av(ssid, tsid, tclass, requested, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700810 if (rc)
811 goto out;
812 rcu_read_lock();
Eric Paris21193dc2009-02-12 14:50:49 -0500813 node = avc_insert(ssid, tsid, tclass, avd);
814 } else {
815 if (in_avd)
816 memcpy(in_avd, &node->ae.avd, sizeof(*in_avd));
817 avd = &node->ae.avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 }
819
Eric Paris21193dc2009-02-12 14:50:49 -0500820 denied = requested & ~(avd->allowed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821
Eric Pariseda4f692008-03-11 14:19:34 -0400822 if (denied) {
Eric Paris64dbf072008-03-31 12:17:33 +1100823 if (flags & AVC_STRICT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824 rc = -EACCES;
KaiGai Kohei8a6f83a2009-04-01 10:07:57 +0900825 else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE))
Eric Paris64dbf072008-03-31 12:17:33 +1100826 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
Eric Paris21193dc2009-02-12 14:50:49 -0500827 tsid, tclass, avd->seqno);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 else
Eric Paris64dbf072008-03-31 12:17:33 +1100829 rc = -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 }
831
832 rcu_read_unlock();
833out:
834 return rc;
835}
836
837/**
838 * avc_has_perm - Check permissions and perform any appropriate auditing.
839 * @ssid: source security identifier
840 * @tsid: target security identifier
841 * @tclass: target security class
842 * @requested: requested permissions, interpreted based on @tclass
843 * @auditdata: auxiliary audit data
844 *
845 * Check the AVC to determine whether the @requested permissions are granted
846 * for the SID pair (@ssid, @tsid), interpreting the permissions
847 * based on @tclass, and call the security server on a cache miss to obtain
848 * a new decision and add it to the cache. Audit the granting or denial of
849 * permissions in accordance with the policy. Return %0 if all @requested
850 * permissions are granted, -%EACCES if any permissions are denied, or
851 * another -errno upon other errors.
852 */
853int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
Thomas Liu2bf49692009-07-14 12:14:09 -0400854 u32 requested, struct common_audit_data *auditdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855{
856 struct av_decision avd;
857 int rc;
858
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400859 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
861 return rc;
862}
Yuichi Nakamura788e7dd2007-09-14 09:27:07 +0900863
864u32 avc_policy_seqno(void)
865{
866 return avc_cache.latest_notif;
867}
Thomas Liu89c86572009-06-24 17:58:05 -0400868
869void avc_disable(void)
870{
Eric Paris5224ee02009-09-20 21:21:10 -0400871 /*
872 * If you are looking at this because you have realized that we are
873 * not destroying the avc_node_cachep it might be easy to fix, but
874 * I don't know the memory barrier semantics well enough to know. It's
875 * possible that some other task dereferenced security_ops when
876 * it still pointed to selinux operations. If that is the case it's
877 * possible that it is about to use the avc and is about to need the
878 * avc_node_cachep. I know I could wrap the security.c security_ops call
879 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
880 * the cache and get that memory back.
881 */
882 if (avc_node_cachep) {
883 avc_flush();
884 /* kmem_cache_destroy(avc_node_cachep); */
885 }
Thomas Liu89c86572009-06-24 17:58:05 -0400886}