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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"
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -040034#include "classmap.h"
Chad Sellers5c458992006-11-06 12:38:16 -050035
Linus Torvalds1da177e2005-04-16 15:20:36 -070036#define AVC_CACHE_SLOTS 512
37#define AVC_DEF_CACHE_THRESHOLD 512
38#define AVC_CACHE_RECLAIM 16
39
40#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
Eric Paris95fff332008-04-17 14:42:10 -040041#define avc_cache_stats_incr(field) \
Linus Torvalds1da177e2005-04-16 15:20:36 -070042do { \
43 per_cpu(avc_cache_stats, get_cpu()).field++; \
44 put_cpu(); \
45} while (0)
46#else
47#define avc_cache_stats_incr(field) do {} while (0)
48#endif
49
50struct avc_entry {
51 u32 ssid;
52 u32 tsid;
53 u16 tclass;
54 struct av_decision avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070055};
56
57struct avc_node {
58 struct avc_entry ae;
Eric Paris26036652009-02-12 14:51:04 -050059 struct hlist_node list; /* anchored in avc_cache->slots[i] */
Eric Paris95fff332008-04-17 14:42:10 -040060 struct rcu_head rhead;
Linus Torvalds1da177e2005-04-16 15:20:36 -070061};
62
63struct avc_cache {
Eric Paris26036652009-02-12 14:51:04 -050064 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
Linus Torvalds1da177e2005-04-16 15:20:36 -070065 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
66 atomic_t lru_hint; /* LRU hint for reclaim scan */
67 atomic_t active_nodes;
68 u32 latest_notif; /* latest revocation notification */
69};
70
71struct avc_callback_node {
72 int (*callback) (u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -040073 u16 tclass, u32 perms,
74 u32 *out_retained);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 u32 events;
76 u32 ssid;
77 u32 tsid;
78 u16 tclass;
79 u32 perms;
80 struct avc_callback_node *next;
81};
82
83/* Exported via selinufs */
84unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
85
86#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
87DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
88#endif
89
90static struct avc_cache avc_cache;
91static struct avc_callback_node *avc_callbacks;
Christoph Lametere18b8902006-12-06 20:33:20 -080092static struct kmem_cache *avc_node_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070093
94static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
95{
96 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
97}
98
99/**
100 * avc_dump_av - Display an access vector in human-readable form.
101 * @tclass: target security class
102 * @av: access vector
103 */
KaiGai Kohei44c2d9b2009-06-18 17:26:13 +0900104static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105{
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400106 const char **perms;
107 int i, perm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
109 if (av == 0) {
110 audit_log_format(ab, " null");
111 return;
112 }
113
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400114 perms = secclass_map[tclass-1].perms;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115
116 audit_log_format(ab, " {");
117 i = 0;
118 perm = 1;
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400119 while (i < (sizeof(av) * 8)) {
Eric Paris0bce9522009-11-23 16:47:23 -0500120 if ((perm & av) && perms[i]) {
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400121 audit_log_format(ab, " %s", perms[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 av &= ~perm;
123 }
124 i++;
125 perm <<= 1;
126 }
127
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128 if (av)
129 audit_log_format(ab, " 0x%x", av);
130
131 audit_log_format(ab, " }");
132}
133
134/**
135 * avc_dump_query - Display a SID pair and a class in human-readable form.
136 * @ssid: source security identifier
137 * @tsid: target security identifier
138 * @tclass: target security class
139 */
140static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
141{
142 int rc;
143 char *scontext;
144 u32 scontext_len;
145
Eric Paris95fff332008-04-17 14:42:10 -0400146 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 if (rc)
148 audit_log_format(ab, "ssid=%d", ssid);
149 else {
150 audit_log_format(ab, "scontext=%s", scontext);
151 kfree(scontext);
152 }
153
154 rc = security_sid_to_context(tsid, &scontext, &scontext_len);
155 if (rc)
156 audit_log_format(ab, " tsid=%d", tsid);
157 else {
158 audit_log_format(ab, " tcontext=%s", scontext);
159 kfree(scontext);
160 }
Stephen Smalleya764ae42007-03-26 13:36:26 -0400161
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400162 BUG_ON(tclass >= ARRAY_SIZE(secclass_map));
163 audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164}
165
166/**
167 * avc_init - Initialize the AVC.
168 *
169 * Initialize the access vector cache.
170 */
171void __init avc_init(void)
172{
173 int i;
174
175 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Paris26036652009-02-12 14:51:04 -0500176 INIT_HLIST_HEAD(&avc_cache.slots[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 spin_lock_init(&avc_cache.slots_lock[i]);
178 }
179 atomic_set(&avc_cache.active_nodes, 0);
180 atomic_set(&avc_cache.lru_hint, 0);
181
182 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
Paul Mundt20c2df82007-07-20 10:11:58 +0900183 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184
David Woodhouse9ad9ad32005-06-22 15:04:33 +0100185 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186}
187
188int avc_get_hash_stats(char *page)
189{
190 int i, chain_len, max_chain_len, slots_used;
191 struct avc_node *node;
Eric Paris26036652009-02-12 14:51:04 -0500192 struct hlist_head *head;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193
194 rcu_read_lock();
195
196 slots_used = 0;
197 max_chain_len = 0;
198 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500199 head = &avc_cache.slots[i];
Eric Paris26036652009-02-12 14:51:04 -0500200 if (!hlist_empty(head)) {
201 struct hlist_node *next;
202
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 slots_used++;
204 chain_len = 0;
Eric Paris26036652009-02-12 14:51:04 -0500205 hlist_for_each_entry_rcu(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 chain_len++;
207 if (chain_len > max_chain_len)
208 max_chain_len = chain_len;
209 }
210 }
211
212 rcu_read_unlock();
213
214 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
215 "longest chain: %d\n",
216 atomic_read(&avc_cache.active_nodes),
217 slots_used, AVC_CACHE_SLOTS, max_chain_len);
218}
219
220static void avc_node_free(struct rcu_head *rhead)
221{
222 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
223 kmem_cache_free(avc_node_cachep, node);
224 avc_cache_stats_incr(frees);
225}
226
227static void avc_node_delete(struct avc_node *node)
228{
Eric Paris26036652009-02-12 14:51:04 -0500229 hlist_del_rcu(&node->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 call_rcu(&node->rhead, avc_node_free);
231 atomic_dec(&avc_cache.active_nodes);
232}
233
234static void avc_node_kill(struct avc_node *node)
235{
236 kmem_cache_free(avc_node_cachep, node);
237 avc_cache_stats_incr(frees);
238 atomic_dec(&avc_cache.active_nodes);
239}
240
241static void avc_node_replace(struct avc_node *new, struct avc_node *old)
242{
Eric Paris26036652009-02-12 14:51:04 -0500243 hlist_replace_rcu(&old->list, &new->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 call_rcu(&old->rhead, avc_node_free);
245 atomic_dec(&avc_cache.active_nodes);
246}
247
248static inline int avc_reclaim_node(void)
249{
250 struct avc_node *node;
251 int hvalue, try, ecx;
252 unsigned long flags;
Eric Paris26036652009-02-12 14:51:04 -0500253 struct hlist_head *head;
254 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500255 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256
Eric Paris95fff332008-04-17 14:42:10 -0400257 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
Eric Parisedf3d1a2009-02-12 14:50:59 -0500259 head = &avc_cache.slots[hvalue];
260 lock = &avc_cache.slots_lock[hvalue];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700261
Eric Parisedf3d1a2009-02-12 14:50:59 -0500262 if (!spin_trylock_irqsave(lock, flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263 continue;
264
Paul E. McKenney61844252008-04-21 18:12:33 -0700265 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500266 hlist_for_each_entry(node, next, head, list) {
Eric Paris906d27d2009-02-12 14:50:43 -0500267 avc_node_delete(node);
268 avc_cache_stats_incr(reclaims);
269 ecx++;
270 if (ecx >= AVC_CACHE_RECLAIM) {
271 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500272 spin_unlock_irqrestore(lock, flags);
Eric Paris906d27d2009-02-12 14:50:43 -0500273 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 }
275 }
Paul E. McKenney61844252008-04-21 18:12:33 -0700276 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500277 spin_unlock_irqrestore(lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 }
279out:
280 return ecx;
281}
282
283static struct avc_node *avc_alloc_node(void)
284{
285 struct avc_node *node;
286
Robert P. J. Dayc3762222007-02-10 01:45:03 -0800287 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 if (!node)
289 goto out;
290
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291 INIT_RCU_HEAD(&node->rhead);
Eric Paris26036652009-02-12 14:51:04 -0500292 INIT_HLIST_NODE(&node->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293 avc_cache_stats_incr(allocations);
294
295 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
296 avc_reclaim_node();
297
298out:
299 return node;
300}
301
Eric Paris21193dc2009-02-12 14:50:49 -0500302static 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 -0700303{
304 node->ae.ssid = ssid;
305 node->ae.tsid = tsid;
306 node->ae.tclass = tclass;
Eric Paris21193dc2009-02-12 14:50:49 -0500307 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308}
309
310static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
311{
312 struct avc_node *node, *ret = NULL;
313 int hvalue;
Eric Paris26036652009-02-12 14:51:04 -0500314 struct hlist_head *head;
315 struct hlist_node *next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700316
317 hvalue = avc_hash(ssid, tsid, tclass);
Eric Parisedf3d1a2009-02-12 14:50:59 -0500318 head = &avc_cache.slots[hvalue];
Eric Paris26036652009-02-12 14:51:04 -0500319 hlist_for_each_entry_rcu(node, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320 if (ssid == node->ae.ssid &&
321 tclass == node->ae.tclass &&
322 tsid == node->ae.tsid) {
323 ret = node;
324 break;
325 }
326 }
327
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 return ret;
329}
330
331/**
332 * avc_lookup - Look up an AVC entry.
333 * @ssid: source security identifier
334 * @tsid: target security identifier
335 * @tclass: target security class
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 *
337 * Look up an AVC entry that is valid for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338 * (@ssid, @tsid), interpreting the permissions
339 * based on @tclass. If a valid AVC entry exists,
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800340 * then this function returns the avc_node.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700341 * Otherwise, this function returns NULL.
342 */
Eric Parisf1c63812009-02-12 14:50:54 -0500343static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344{
345 struct avc_node *node;
346
347 avc_cache_stats_incr(lookups);
348 node = avc_search_node(ssid, tsid, tclass);
349
Eric Parisf1c63812009-02-12 14:50:54 -0500350 if (node)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351 avc_cache_stats_incr(hits);
Eric Parisf1c63812009-02-12 14:50:54 -0500352 else
353 avc_cache_stats_incr(misses);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 return node;
356}
357
358static int avc_latest_notif_update(int seqno, int is_insert)
359{
360 int ret = 0;
361 static DEFINE_SPINLOCK(notif_lock);
362 unsigned long flag;
363
364 spin_lock_irqsave(&notif_lock, flag);
365 if (is_insert) {
366 if (seqno < avc_cache.latest_notif) {
Eric Paris744ba352008-04-17 11:52:44 -0400367 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 seqno, avc_cache.latest_notif);
369 ret = -EAGAIN;
370 }
371 } else {
372 if (seqno > avc_cache.latest_notif)
373 avc_cache.latest_notif = seqno;
374 }
375 spin_unlock_irqrestore(&notif_lock, flag);
376
377 return ret;
378}
379
380/**
381 * avc_insert - Insert an AVC entry.
382 * @ssid: source security identifier
383 * @tsid: target security identifier
384 * @tclass: target security class
Eric Paris21193dc2009-02-12 14:50:49 -0500385 * @avd: resulting av decision
Linus Torvalds1da177e2005-04-16 15:20:36 -0700386 *
387 * Insert an AVC entry for the SID pair
388 * (@ssid, @tsid) and class @tclass.
389 * The access vectors and the sequence number are
390 * normally provided by the security server in
391 * response to a security_compute_av() call. If the
Eric Paris21193dc2009-02-12 14:50:49 -0500392 * sequence number @avd->seqno is not less than the latest
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393 * revocation notification, then the function copies
394 * the access vectors into a cache entry, returns
395 * avc_node inserted. Otherwise, this function returns NULL.
396 */
Eric Paris21193dc2009-02-12 14:50:49 -0500397static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398{
399 struct avc_node *pos, *node = NULL;
400 int hvalue;
401 unsigned long flag;
402
Eric Paris21193dc2009-02-12 14:50:49 -0500403 if (avc_latest_notif_update(avd->seqno, 1))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404 goto out;
405
406 node = avc_alloc_node();
407 if (node) {
Eric Paris26036652009-02-12 14:51:04 -0500408 struct hlist_head *head;
409 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500410 spinlock_t *lock;
411
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 hvalue = avc_hash(ssid, tsid, tclass);
Eric Paris21193dc2009-02-12 14:50:49 -0500413 avc_node_populate(node, ssid, tsid, tclass, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414
Eric Parisedf3d1a2009-02-12 14:50:59 -0500415 head = &avc_cache.slots[hvalue];
416 lock = &avc_cache.slots_lock[hvalue];
417
418 spin_lock_irqsave(lock, flag);
Eric Paris26036652009-02-12 14:51:04 -0500419 hlist_for_each_entry(pos, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420 if (pos->ae.ssid == ssid &&
421 pos->ae.tsid == tsid &&
422 pos->ae.tclass == tclass) {
Eric Paris95fff332008-04-17 14:42:10 -0400423 avc_node_replace(node, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 goto found;
425 }
426 }
Eric Paris26036652009-02-12 14:51:04 -0500427 hlist_add_head_rcu(&node->list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700428found:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500429 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430 }
431out:
432 return node;
433}
434
Thomas Liu2bf49692009-07-14 12:14:09 -0400435/**
436 * avc_audit_pre_callback - SELinux specific information
437 * will be called by generic audit code
438 * @ab: the audit buffer
439 * @a: audit_data
440 */
441static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442{
Thomas Liu2bf49692009-07-14 12:14:09 -0400443 struct common_audit_data *ad = a;
444 audit_log_format(ab, "avc: %s ",
445 ad->selinux_audit_data.denied ? "denied" : "granted");
446 avc_dump_av(ab, ad->selinux_audit_data.tclass,
447 ad->selinux_audit_data.audited);
448 audit_log_format(ab, " for ");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700449}
450
Thomas Liu2bf49692009-07-14 12:14:09 -0400451/**
452 * avc_audit_post_callback - SELinux specific information
453 * will be called by generic audit code
454 * @ab: the audit buffer
455 * @a: audit_data
456 */
457static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458{
Thomas Liu2bf49692009-07-14 12:14:09 -0400459 struct common_audit_data *ad = a;
460 audit_log_format(ab, " ");
461 avc_dump_query(ab, ad->selinux_audit_data.ssid,
462 ad->selinux_audit_data.tsid,
463 ad->selinux_audit_data.tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464}
465
466/**
467 * avc_audit - Audit the granting or denial of permissions.
468 * @ssid: source security identifier
469 * @tsid: target security identifier
470 * @tclass: target security class
471 * @requested: requested permissions
472 * @avd: access vector decisions
473 * @result: result from avc_has_perm_noaudit
474 * @a: auxiliary audit data
475 *
476 * Audit the granting or denial of permissions in accordance
477 * with the policy. This function is typically called by
478 * avc_has_perm() after a permission check, but can also be
479 * called directly by callers who use avc_has_perm_noaudit()
480 * in order to separate the permission check from the auditing.
481 * For example, this separation is useful when the permission check must
482 * be performed under a lock, to allow the lock to be released
483 * before calling the auditing code.
484 */
485void avc_audit(u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400486 u16 tclass, u32 requested,
Thomas Liu2bf49692009-07-14 12:14:09 -0400487 struct av_decision *avd, int result, struct common_audit_data *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488{
Thomas Liu2bf49692009-07-14 12:14:09 -0400489 struct common_audit_data stack_data;
James Morrisbe940d62009-07-13 10:39:36 +1000490 u32 denied, audited;
James Morrisbe940d62009-07-13 10:39:36 +1000491 denied = requested & ~avd->allowed;
Stephen Smalleyb6cac5a2010-02-02 11:31:51 -0500492 if (denied)
493 audited = denied & avd->auditdeny;
494 else if (result)
James Morrisbe940d62009-07-13 10:39:36 +1000495 audited = denied = requested;
Stephen Smalleyb6cac5a2010-02-02 11:31:51 -0500496 else
497 audited = requested & avd->auditallow;
498 if (!audited)
499 return;
Thomas Liu2bf49692009-07-14 12:14:09 -0400500 if (!a) {
501 a = &stack_data;
502 memset(a, 0, sizeof(*a));
503 a->type = LSM_AUDIT_NO_AUDIT;
James Morrisbe940d62009-07-13 10:39:36 +1000504 }
Thomas Liu2bf49692009-07-14 12:14:09 -0400505 a->selinux_audit_data.tclass = tclass;
506 a->selinux_audit_data.requested = requested;
507 a->selinux_audit_data.ssid = ssid;
508 a->selinux_audit_data.tsid = tsid;
509 a->selinux_audit_data.audited = audited;
510 a->selinux_audit_data.denied = denied;
511 a->lsm_pre_audit = avc_audit_pre_callback;
512 a->lsm_post_audit = avc_audit_post_callback;
513 common_lsm_audit(a);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514}
515
516/**
517 * avc_add_callback - Register a callback for security events.
518 * @callback: callback function
519 * @events: security events
520 * @ssid: source security identifier or %SECSID_WILD
521 * @tsid: target security identifier or %SECSID_WILD
522 * @tclass: target security class
523 * @perms: permissions
524 *
525 * Register a callback function for events in the set @events
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800526 * related to the SID pair (@ssid, @tsid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700527 * and the permissions @perms, interpreting
528 * @perms based on @tclass. Returns %0 on success or
529 * -%ENOMEM if insufficient memory exists to add the callback.
530 */
531int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400532 u16 tclass, u32 perms,
533 u32 *out_retained),
534 u32 events, u32 ssid, u32 tsid,
535 u16 tclass, u32 perms)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536{
537 struct avc_callback_node *c;
538 int rc = 0;
539
540 c = kmalloc(sizeof(*c), GFP_ATOMIC);
541 if (!c) {
542 rc = -ENOMEM;
543 goto out;
544 }
545
546 c->callback = callback;
547 c->events = events;
548 c->ssid = ssid;
549 c->tsid = tsid;
550 c->perms = perms;
551 c->next = avc_callbacks;
552 avc_callbacks = c;
553out:
554 return rc;
555}
556
557static inline int avc_sidcmp(u32 x, u32 y)
558{
559 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
560}
561
562/**
563 * avc_update_node Update an AVC entry
564 * @event : Updating event
565 * @perms : Permission mask bits
566 * @ssid,@tsid,@tclass : identifier of an AVC entry
Eric Parisa5dda6832009-02-12 14:50:11 -0500567 * @seqno : sequence number when decision was made
Linus Torvalds1da177e2005-04-16 15:20:36 -0700568 *
569 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
570 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800571 * otherwise, this function updates the AVC entry. The original AVC-entry object
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 * will release later by RCU.
573 */
Eric Parisa5dda6832009-02-12 14:50:11 -0500574static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
575 u32 seqno)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700576{
577 int hvalue, rc = 0;
578 unsigned long flag;
579 struct avc_node *pos, *node, *orig = NULL;
Eric Paris26036652009-02-12 14:51:04 -0500580 struct hlist_head *head;
581 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500582 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583
584 node = avc_alloc_node();
585 if (!node) {
586 rc = -ENOMEM;
587 goto out;
588 }
589
590 /* Lock the target slot */
591 hvalue = avc_hash(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592
Eric Parisedf3d1a2009-02-12 14:50:59 -0500593 head = &avc_cache.slots[hvalue];
594 lock = &avc_cache.slots_lock[hvalue];
595
596 spin_lock_irqsave(lock, flag);
597
Eric Paris26036652009-02-12 14:51:04 -0500598 hlist_for_each_entry(pos, next, head, list) {
Eric Paris95fff332008-04-17 14:42:10 -0400599 if (ssid == pos->ae.ssid &&
600 tsid == pos->ae.tsid &&
Eric Parisa5dda6832009-02-12 14:50:11 -0500601 tclass == pos->ae.tclass &&
602 seqno == pos->ae.avd.seqno){
Linus Torvalds1da177e2005-04-16 15:20:36 -0700603 orig = pos;
604 break;
605 }
606 }
607
608 if (!orig) {
609 rc = -ENOENT;
610 avc_node_kill(node);
611 goto out_unlock;
612 }
613
614 /*
615 * Copy and replace original node.
616 */
617
Eric Paris21193dc2009-02-12 14:50:49 -0500618 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619
620 switch (event) {
621 case AVC_CALLBACK_GRANT:
622 node->ae.avd.allowed |= perms;
623 break;
624 case AVC_CALLBACK_TRY_REVOKE:
625 case AVC_CALLBACK_REVOKE:
626 node->ae.avd.allowed &= ~perms;
627 break;
628 case AVC_CALLBACK_AUDITALLOW_ENABLE:
629 node->ae.avd.auditallow |= perms;
630 break;
631 case AVC_CALLBACK_AUDITALLOW_DISABLE:
632 node->ae.avd.auditallow &= ~perms;
633 break;
634 case AVC_CALLBACK_AUDITDENY_ENABLE:
635 node->ae.avd.auditdeny |= perms;
636 break;
637 case AVC_CALLBACK_AUDITDENY_DISABLE:
638 node->ae.avd.auditdeny &= ~perms;
639 break;
640 }
641 avc_node_replace(node, orig);
642out_unlock:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500643 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644out:
645 return rc;
646}
647
648/**
Eric Paris008574b2009-09-12 22:54:17 -0400649 * avc_flush - Flush the cache
Linus Torvalds1da177e2005-04-16 15:20:36 -0700650 */
Eric Paris008574b2009-09-12 22:54:17 -0400651static void avc_flush(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700652{
Eric Paris26036652009-02-12 14:51:04 -0500653 struct hlist_head *head;
654 struct hlist_node *next;
Eric Paris008574b2009-09-12 22:54:17 -0400655 struct avc_node *node;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500656 spinlock_t *lock;
Eric Paris008574b2009-09-12 22:54:17 -0400657 unsigned long flag;
658 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659
660 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500661 head = &avc_cache.slots[i];
662 lock = &avc_cache.slots_lock[i];
663
664 spin_lock_irqsave(lock, flag);
Paul E. McKenney61844252008-04-21 18:12:33 -0700665 /*
666 * With preemptable RCU, the outer spinlock does not
667 * prevent RCU grace periods from ending.
668 */
669 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500670 hlist_for_each_entry(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700671 avc_node_delete(node);
Paul E. McKenney61844252008-04-21 18:12:33 -0700672 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500673 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700674 }
Eric Paris008574b2009-09-12 22:54:17 -0400675}
676
677/**
678 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
679 * @seqno: policy sequence number
680 */
681int avc_ss_reset(u32 seqno)
682{
683 struct avc_callback_node *c;
684 int rc = 0, tmprc;
685
686 avc_flush();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687
688 for (c = avc_callbacks; c; c = c->next) {
689 if (c->events & AVC_CALLBACK_RESET) {
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600690 tmprc = c->callback(AVC_CALLBACK_RESET,
Eric Paris95fff332008-04-17 14:42:10 -0400691 0, 0, 0, 0, NULL);
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600692 /* save the first error encountered for the return
693 value and continue processing the callbacks */
694 if (!rc)
695 rc = tmprc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 }
697 }
698
699 avc_latest_notif_update(seqno, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 return rc;
701}
702
703/**
704 * avc_has_perm_noaudit - Check permissions but perform no auditing.
705 * @ssid: source security identifier
706 * @tsid: target security identifier
707 * @tclass: target security class
708 * @requested: requested permissions, interpreted based on @tclass
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400709 * @flags: AVC_STRICT or 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700710 * @avd: access vector decisions
711 *
712 * Check the AVC to determine whether the @requested permissions are granted
713 * for the SID pair (@ssid, @tsid), interpreting the permissions
714 * based on @tclass, and call the security server on a cache miss to obtain
715 * a new decision and add it to the cache. Return a copy of the decisions
716 * in @avd. Return %0 if all @requested permissions are granted,
717 * -%EACCES if any permissions are denied, or another -errno upon
718 * other errors. This function is typically called by avc_has_perm(),
719 * but may also be called directly to separate permission checking from
720 * auditing, e.g. in cases where a lock must be held for the check but
721 * should be released for the auditing.
722 */
723int avc_has_perm_noaudit(u32 ssid, u32 tsid,
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400724 u16 tclass, u32 requested,
725 unsigned flags,
Eric Paris21193dc2009-02-12 14:50:49 -0500726 struct av_decision *in_avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700727{
728 struct avc_node *node;
Eric Paris21193dc2009-02-12 14:50:49 -0500729 struct av_decision avd_entry, *avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730 int rc = 0;
731 u32 denied;
732
Eric Pariseda4f692008-03-11 14:19:34 -0400733 BUG_ON(!requested);
734
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735 rcu_read_lock();
736
Eric Parisf1c63812009-02-12 14:50:54 -0500737 node = avc_lookup(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700738 if (!node) {
739 rcu_read_unlock();
Eric Paris21193dc2009-02-12 14:50:49 -0500740
741 if (in_avd)
742 avd = in_avd;
743 else
744 avd = &avd_entry;
745
Stephen Smalley19439d02010-01-14 17:28:10 -0500746 security_compute_av(ssid, tsid, tclass, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700747 rcu_read_lock();
Eric Paris21193dc2009-02-12 14:50:49 -0500748 node = avc_insert(ssid, tsid, tclass, avd);
749 } else {
750 if (in_avd)
751 memcpy(in_avd, &node->ae.avd, sizeof(*in_avd));
752 avd = &node->ae.avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 }
754
Eric Paris21193dc2009-02-12 14:50:49 -0500755 denied = requested & ~(avd->allowed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756
Eric Pariseda4f692008-03-11 14:19:34 -0400757 if (denied) {
Eric Paris64dbf072008-03-31 12:17:33 +1100758 if (flags & AVC_STRICT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700759 rc = -EACCES;
KaiGai Kohei8a6f83a2009-04-01 10:07:57 +0900760 else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE))
Eric Paris64dbf072008-03-31 12:17:33 +1100761 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
Eric Paris21193dc2009-02-12 14:50:49 -0500762 tsid, tclass, avd->seqno);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 else
Eric Paris64dbf072008-03-31 12:17:33 +1100764 rc = -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 }
766
767 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 return rc;
769}
770
771/**
772 * avc_has_perm - Check permissions and perform any appropriate auditing.
773 * @ssid: source security identifier
774 * @tsid: target security identifier
775 * @tclass: target security class
776 * @requested: requested permissions, interpreted based on @tclass
777 * @auditdata: auxiliary audit data
778 *
779 * Check the AVC to determine whether the @requested permissions are granted
780 * for the SID pair (@ssid, @tsid), interpreting the permissions
781 * based on @tclass, and call the security server on a cache miss to obtain
782 * a new decision and add it to the cache. Audit the granting or denial of
783 * permissions in accordance with the policy. Return %0 if all @requested
784 * permissions are granted, -%EACCES if any permissions are denied, or
785 * another -errno upon other errors.
786 */
787int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
Thomas Liu2bf49692009-07-14 12:14:09 -0400788 u32 requested, struct common_audit_data *auditdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789{
790 struct av_decision avd;
791 int rc;
792
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400793 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
795 return rc;
796}
Yuichi Nakamura788e7dd2007-09-14 09:27:07 +0900797
798u32 avc_policy_seqno(void)
799{
800 return avc_cache.latest_notif;
801}
Thomas Liu89c86572009-06-24 17:58:05 -0400802
803void avc_disable(void)
804{
Eric Paris5224ee02009-09-20 21:21:10 -0400805 /*
806 * If you are looking at this because you have realized that we are
807 * not destroying the avc_node_cachep it might be easy to fix, but
808 * I don't know the memory barrier semantics well enough to know. It's
809 * possible that some other task dereferenced security_ops when
810 * it still pointed to selinux operations. If that is the case it's
811 * possible that it is about to use the avc and is about to need the
812 * avc_node_cachep. I know I could wrap the security.c security_ops call
813 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
814 * the cache and get that memory back.
815 */
816 if (avc_node_cachep) {
817 avc_flush();
818 /* kmem_cache_destroy(avc_node_cachep); */
819 }
Thomas Liu89c86572009-06-24 17:58:05 -0400820}