blob: 9da6420e2056541f330d85e41be66f4742691e2b [file] [log] [blame]
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
Eric Paris26036652009-02-12 14:51:04 -0500291 INIT_HLIST_NODE(&node->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 avc_cache_stats_incr(allocations);
293
294 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
295 avc_reclaim_node();
296
297out:
298 return node;
299}
300
Eric Paris21193dc2009-02-12 14:50:49 -0500301static 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 -0700302{
303 node->ae.ssid = ssid;
304 node->ae.tsid = tsid;
305 node->ae.tclass = tclass;
Eric Paris21193dc2009-02-12 14:50:49 -0500306 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307}
308
309static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
310{
311 struct avc_node *node, *ret = NULL;
312 int hvalue;
Eric Paris26036652009-02-12 14:51:04 -0500313 struct hlist_head *head;
314 struct hlist_node *next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315
316 hvalue = avc_hash(ssid, tsid, tclass);
Eric Parisedf3d1a2009-02-12 14:50:59 -0500317 head = &avc_cache.slots[hvalue];
Eric Paris26036652009-02-12 14:51:04 -0500318 hlist_for_each_entry_rcu(node, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700319 if (ssid == node->ae.ssid &&
320 tclass == node->ae.tclass &&
321 tsid == node->ae.tsid) {
322 ret = node;
323 break;
324 }
325 }
326
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 return ret;
328}
329
330/**
331 * avc_lookup - Look up an AVC entry.
332 * @ssid: source security identifier
333 * @tsid: target security identifier
334 * @tclass: target security class
Linus Torvalds1da177e2005-04-16 15:20:36 -0700335 *
336 * Look up an AVC entry that is valid for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337 * (@ssid, @tsid), interpreting the permissions
338 * based on @tclass. If a valid AVC entry exists,
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800339 * then this function returns the avc_node.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 * Otherwise, this function returns NULL.
341 */
Eric Parisf1c63812009-02-12 14:50:54 -0500342static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343{
344 struct avc_node *node;
345
346 avc_cache_stats_incr(lookups);
347 node = avc_search_node(ssid, tsid, tclass);
348
Eric Parisf1c63812009-02-12 14:50:54 -0500349 if (node)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350 avc_cache_stats_incr(hits);
Eric Parisf1c63812009-02-12 14:50:54 -0500351 else
352 avc_cache_stats_incr(misses);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700353
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 return node;
355}
356
357static int avc_latest_notif_update(int seqno, int is_insert)
358{
359 int ret = 0;
360 static DEFINE_SPINLOCK(notif_lock);
361 unsigned long flag;
362
363 spin_lock_irqsave(&notif_lock, flag);
364 if (is_insert) {
365 if (seqno < avc_cache.latest_notif) {
Eric Paris744ba352008-04-17 11:52:44 -0400366 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 seqno, avc_cache.latest_notif);
368 ret = -EAGAIN;
369 }
370 } else {
371 if (seqno > avc_cache.latest_notif)
372 avc_cache.latest_notif = seqno;
373 }
374 spin_unlock_irqrestore(&notif_lock, flag);
375
376 return ret;
377}
378
379/**
380 * avc_insert - Insert an AVC entry.
381 * @ssid: source security identifier
382 * @tsid: target security identifier
383 * @tclass: target security class
Eric Paris21193dc2009-02-12 14:50:49 -0500384 * @avd: resulting av decision
Linus Torvalds1da177e2005-04-16 15:20:36 -0700385 *
386 * Insert an AVC entry for the SID pair
387 * (@ssid, @tsid) and class @tclass.
388 * The access vectors and the sequence number are
389 * normally provided by the security server in
390 * response to a security_compute_av() call. If the
Eric Paris21193dc2009-02-12 14:50:49 -0500391 * sequence number @avd->seqno is not less than the latest
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392 * revocation notification, then the function copies
393 * the access vectors into a cache entry, returns
394 * avc_node inserted. Otherwise, this function returns NULL.
395 */
Eric Paris21193dc2009-02-12 14:50:49 -0500396static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397{
398 struct avc_node *pos, *node = NULL;
399 int hvalue;
400 unsigned long flag;
401
Eric Paris21193dc2009-02-12 14:50:49 -0500402 if (avc_latest_notif_update(avd->seqno, 1))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 goto out;
404
405 node = avc_alloc_node();
406 if (node) {
Eric Paris26036652009-02-12 14:51:04 -0500407 struct hlist_head *head;
408 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500409 spinlock_t *lock;
410
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 hvalue = avc_hash(ssid, tsid, tclass);
Eric Paris21193dc2009-02-12 14:50:49 -0500412 avc_node_populate(node, ssid, tsid, tclass, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413
Eric Parisedf3d1a2009-02-12 14:50:59 -0500414 head = &avc_cache.slots[hvalue];
415 lock = &avc_cache.slots_lock[hvalue];
416
417 spin_lock_irqsave(lock, flag);
Eric Paris26036652009-02-12 14:51:04 -0500418 hlist_for_each_entry(pos, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700419 if (pos->ae.ssid == ssid &&
420 pos->ae.tsid == tsid &&
421 pos->ae.tclass == tclass) {
Eric Paris95fff332008-04-17 14:42:10 -0400422 avc_node_replace(node, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 goto found;
424 }
425 }
Eric Paris26036652009-02-12 14:51:04 -0500426 hlist_add_head_rcu(&node->list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427found:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500428 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700429 }
430out:
431 return node;
432}
433
Thomas Liu2bf49692009-07-14 12:14:09 -0400434/**
435 * avc_audit_pre_callback - SELinux specific information
436 * will be called by generic audit code
437 * @ab: the audit buffer
438 * @a: audit_data
439 */
440static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700441{
Thomas Liu2bf49692009-07-14 12:14:09 -0400442 struct common_audit_data *ad = a;
443 audit_log_format(ab, "avc: %s ",
444 ad->selinux_audit_data.denied ? "denied" : "granted");
445 avc_dump_av(ab, ad->selinux_audit_data.tclass,
446 ad->selinux_audit_data.audited);
447 audit_log_format(ab, " for ");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448}
449
Thomas Liu2bf49692009-07-14 12:14:09 -0400450/**
451 * avc_audit_post_callback - SELinux specific information
452 * will be called by generic audit code
453 * @ab: the audit buffer
454 * @a: audit_data
455 */
456static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457{
Thomas Liu2bf49692009-07-14 12:14:09 -0400458 struct common_audit_data *ad = a;
459 audit_log_format(ab, " ");
460 avc_dump_query(ab, ad->selinux_audit_data.ssid,
461 ad->selinux_audit_data.tsid,
462 ad->selinux_audit_data.tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463}
464
465/**
466 * avc_audit - Audit the granting or denial of permissions.
467 * @ssid: source security identifier
468 * @tsid: target security identifier
469 * @tclass: target security class
470 * @requested: requested permissions
471 * @avd: access vector decisions
472 * @result: result from avc_has_perm_noaudit
473 * @a: auxiliary audit data
474 *
475 * Audit the granting or denial of permissions in accordance
476 * with the policy. This function is typically called by
477 * avc_has_perm() after a permission check, but can also be
478 * called directly by callers who use avc_has_perm_noaudit()
479 * in order to separate the permission check from the auditing.
480 * For example, this separation is useful when the permission check must
481 * be performed under a lock, to allow the lock to be released
482 * before calling the auditing code.
483 */
484void avc_audit(u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400485 u16 tclass, u32 requested,
Thomas Liu2bf49692009-07-14 12:14:09 -0400486 struct av_decision *avd, int result, struct common_audit_data *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487{
Thomas Liu2bf49692009-07-14 12:14:09 -0400488 struct common_audit_data stack_data;
James Morrisbe940d62009-07-13 10:39:36 +1000489 u32 denied, audited;
James Morrisbe940d62009-07-13 10:39:36 +1000490 denied = requested & ~avd->allowed;
Eric Parisb782e0a2010-07-23 11:44:03 -0400491 if (denied) {
Stephen Smalleyb6cac5a2010-02-02 11:31:51 -0500492 audited = denied & avd->auditdeny;
Eric Parisb782e0a2010-07-23 11:44:03 -0400493 /*
494 * a->selinux_audit_data.auditdeny is TRICKY! Setting a bit in
495 * this field means that ANY denials should NOT be audited if
496 * the policy contains an explicit dontaudit rule for that
497 * permission. Take notice that this is unrelated to the
498 * actual permissions that were denied. As an example lets
499 * assume:
500 *
501 * denied == READ
502 * avd.auditdeny & ACCESS == 0 (not set means explicit rule)
503 * selinux_audit_data.auditdeny & ACCESS == 1
504 *
505 * We will NOT audit the denial even though the denied
506 * permission was READ and the auditdeny checks were for
507 * ACCESS
508 */
509 if (a &&
510 a->selinux_audit_data.auditdeny &&
511 !(a->selinux_audit_data.auditdeny & avd->auditdeny))
512 audited = 0;
513 } else if (result)
James Morrisbe940d62009-07-13 10:39:36 +1000514 audited = denied = requested;
Stephen Smalleyb6cac5a2010-02-02 11:31:51 -0500515 else
516 audited = requested & avd->auditallow;
517 if (!audited)
518 return;
Thomas Liu2bf49692009-07-14 12:14:09 -0400519 if (!a) {
520 a = &stack_data;
Eric Pariscb84aa92010-04-27 17:20:38 -0400521 COMMON_AUDIT_DATA_INIT(a, NONE);
James Morrisbe940d62009-07-13 10:39:36 +1000522 }
Thomas Liu2bf49692009-07-14 12:14:09 -0400523 a->selinux_audit_data.tclass = tclass;
524 a->selinux_audit_data.requested = requested;
525 a->selinux_audit_data.ssid = ssid;
526 a->selinux_audit_data.tsid = tsid;
527 a->selinux_audit_data.audited = audited;
528 a->selinux_audit_data.denied = denied;
529 a->lsm_pre_audit = avc_audit_pre_callback;
530 a->lsm_post_audit = avc_audit_post_callback;
531 common_lsm_audit(a);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532}
533
534/**
535 * avc_add_callback - Register a callback for security events.
536 * @callback: callback function
537 * @events: security events
538 * @ssid: source security identifier or %SECSID_WILD
539 * @tsid: target security identifier or %SECSID_WILD
540 * @tclass: target security class
541 * @perms: permissions
542 *
543 * Register a callback function for events in the set @events
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800544 * related to the SID pair (@ssid, @tsid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545 * and the permissions @perms, interpreting
546 * @perms based on @tclass. Returns %0 on success or
547 * -%ENOMEM if insufficient memory exists to add the callback.
548 */
549int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400550 u16 tclass, u32 perms,
551 u32 *out_retained),
552 u32 events, u32 ssid, u32 tsid,
553 u16 tclass, u32 perms)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554{
555 struct avc_callback_node *c;
556 int rc = 0;
557
558 c = kmalloc(sizeof(*c), GFP_ATOMIC);
559 if (!c) {
560 rc = -ENOMEM;
561 goto out;
562 }
563
564 c->callback = callback;
565 c->events = events;
566 c->ssid = ssid;
567 c->tsid = tsid;
568 c->perms = perms;
569 c->next = avc_callbacks;
570 avc_callbacks = c;
571out:
572 return rc;
573}
574
575static inline int avc_sidcmp(u32 x, u32 y)
576{
577 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
578}
579
580/**
581 * avc_update_node Update an AVC entry
582 * @event : Updating event
583 * @perms : Permission mask bits
584 * @ssid,@tsid,@tclass : identifier of an AVC entry
Eric Parisa5dda682009-02-12 14:50:11 -0500585 * @seqno : sequence number when decision was made
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586 *
587 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
588 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800589 * otherwise, this function updates the AVC entry. The original AVC-entry object
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 * will release later by RCU.
591 */
Eric Parisa5dda682009-02-12 14:50:11 -0500592static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
593 u32 seqno)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594{
595 int hvalue, rc = 0;
596 unsigned long flag;
597 struct avc_node *pos, *node, *orig = NULL;
Eric Paris26036652009-02-12 14:51:04 -0500598 struct hlist_head *head;
599 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500600 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601
602 node = avc_alloc_node();
603 if (!node) {
604 rc = -ENOMEM;
605 goto out;
606 }
607
608 /* Lock the target slot */
609 hvalue = avc_hash(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610
Eric Parisedf3d1a2009-02-12 14:50:59 -0500611 head = &avc_cache.slots[hvalue];
612 lock = &avc_cache.slots_lock[hvalue];
613
614 spin_lock_irqsave(lock, flag);
615
Eric Paris26036652009-02-12 14:51:04 -0500616 hlist_for_each_entry(pos, next, head, list) {
Eric Paris95fff332008-04-17 14:42:10 -0400617 if (ssid == pos->ae.ssid &&
618 tsid == pos->ae.tsid &&
Eric Parisa5dda682009-02-12 14:50:11 -0500619 tclass == pos->ae.tclass &&
620 seqno == pos->ae.avd.seqno){
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621 orig = pos;
622 break;
623 }
624 }
625
626 if (!orig) {
627 rc = -ENOENT;
628 avc_node_kill(node);
629 goto out_unlock;
630 }
631
632 /*
633 * Copy and replace original node.
634 */
635
Eric Paris21193dc2009-02-12 14:50:49 -0500636 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
638 switch (event) {
639 case AVC_CALLBACK_GRANT:
640 node->ae.avd.allowed |= perms;
641 break;
642 case AVC_CALLBACK_TRY_REVOKE:
643 case AVC_CALLBACK_REVOKE:
644 node->ae.avd.allowed &= ~perms;
645 break;
646 case AVC_CALLBACK_AUDITALLOW_ENABLE:
647 node->ae.avd.auditallow |= perms;
648 break;
649 case AVC_CALLBACK_AUDITALLOW_DISABLE:
650 node->ae.avd.auditallow &= ~perms;
651 break;
652 case AVC_CALLBACK_AUDITDENY_ENABLE:
653 node->ae.avd.auditdeny |= perms;
654 break;
655 case AVC_CALLBACK_AUDITDENY_DISABLE:
656 node->ae.avd.auditdeny &= ~perms;
657 break;
658 }
659 avc_node_replace(node, orig);
660out_unlock:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500661 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700662out:
663 return rc;
664}
665
666/**
Eric Paris008574b2009-09-12 22:54:17 -0400667 * avc_flush - Flush the cache
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 */
Eric Paris008574b2009-09-12 22:54:17 -0400669static void avc_flush(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670{
Eric Paris26036652009-02-12 14:51:04 -0500671 struct hlist_head *head;
672 struct hlist_node *next;
Eric Paris008574b2009-09-12 22:54:17 -0400673 struct avc_node *node;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500674 spinlock_t *lock;
Eric Paris008574b2009-09-12 22:54:17 -0400675 unsigned long flag;
676 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700677
678 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500679 head = &avc_cache.slots[i];
680 lock = &avc_cache.slots_lock[i];
681
682 spin_lock_irqsave(lock, flag);
Paul E. McKenney61844252008-04-21 18:12:33 -0700683 /*
684 * With preemptable RCU, the outer spinlock does not
685 * prevent RCU grace periods from ending.
686 */
687 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500688 hlist_for_each_entry(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 avc_node_delete(node);
Paul E. McKenney61844252008-04-21 18:12:33 -0700690 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500691 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 }
Eric Paris008574b2009-09-12 22:54:17 -0400693}
694
695/**
696 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
697 * @seqno: policy sequence number
698 */
699int avc_ss_reset(u32 seqno)
700{
701 struct avc_callback_node *c;
702 int rc = 0, tmprc;
703
704 avc_flush();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705
706 for (c = avc_callbacks; c; c = c->next) {
707 if (c->events & AVC_CALLBACK_RESET) {
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600708 tmprc = c->callback(AVC_CALLBACK_RESET,
Eric Paris95fff332008-04-17 14:42:10 -0400709 0, 0, 0, 0, NULL);
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600710 /* save the first error encountered for the return
711 value and continue processing the callbacks */
712 if (!rc)
713 rc = tmprc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700714 }
715 }
716
717 avc_latest_notif_update(seqno, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 return rc;
719}
720
721/**
722 * avc_has_perm_noaudit - Check permissions but perform no auditing.
723 * @ssid: source security identifier
724 * @tsid: target security identifier
725 * @tclass: target security class
726 * @requested: requested permissions, interpreted based on @tclass
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400727 * @flags: AVC_STRICT or 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728 * @avd: access vector decisions
729 *
730 * Check the AVC to determine whether the @requested permissions are granted
731 * for the SID pair (@ssid, @tsid), interpreting the permissions
732 * based on @tclass, and call the security server on a cache miss to obtain
733 * a new decision and add it to the cache. Return a copy of the decisions
734 * in @avd. Return %0 if all @requested permissions are granted,
735 * -%EACCES if any permissions are denied, or another -errno upon
736 * other errors. This function is typically called by avc_has_perm(),
737 * but may also be called directly to separate permission checking from
738 * auditing, e.g. in cases where a lock must be held for the check but
739 * should be released for the auditing.
740 */
741int avc_has_perm_noaudit(u32 ssid, u32 tsid,
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400742 u16 tclass, u32 requested,
743 unsigned flags,
Eric Paris21193dc2009-02-12 14:50:49 -0500744 struct av_decision *in_avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745{
746 struct avc_node *node;
Eric Paris21193dc2009-02-12 14:50:49 -0500747 struct av_decision avd_entry, *avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 int rc = 0;
749 u32 denied;
750
Eric Pariseda4f692008-03-11 14:19:34 -0400751 BUG_ON(!requested);
752
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 rcu_read_lock();
754
Eric Parisf1c63812009-02-12 14:50:54 -0500755 node = avc_lookup(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756 if (!node) {
757 rcu_read_unlock();
Eric Paris21193dc2009-02-12 14:50:49 -0500758
759 if (in_avd)
760 avd = in_avd;
761 else
762 avd = &avd_entry;
763
Stephen Smalley19439d02010-01-14 17:28:10 -0500764 security_compute_av(ssid, tsid, tclass, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 rcu_read_lock();
Eric Paris21193dc2009-02-12 14:50:49 -0500766 node = avc_insert(ssid, tsid, tclass, avd);
767 } else {
768 if (in_avd)
769 memcpy(in_avd, &node->ae.avd, sizeof(*in_avd));
770 avd = &node->ae.avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700771 }
772
Eric Paris21193dc2009-02-12 14:50:49 -0500773 denied = requested & ~(avd->allowed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774
Eric Pariseda4f692008-03-11 14:19:34 -0400775 if (denied) {
Eric Paris64dbf072008-03-31 12:17:33 +1100776 if (flags & AVC_STRICT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777 rc = -EACCES;
KaiGai Kohei8a6f83a2009-04-01 10:07:57 +0900778 else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE))
Eric Paris64dbf072008-03-31 12:17:33 +1100779 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
Eric Paris21193dc2009-02-12 14:50:49 -0500780 tsid, tclass, avd->seqno);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700781 else
Eric Paris64dbf072008-03-31 12:17:33 +1100782 rc = -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783 }
784
785 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 return rc;
787}
788
789/**
790 * avc_has_perm - Check permissions and perform any appropriate auditing.
791 * @ssid: source security identifier
792 * @tsid: target security identifier
793 * @tclass: target security class
794 * @requested: requested permissions, interpreted based on @tclass
795 * @auditdata: auxiliary audit data
796 *
797 * Check the AVC to determine whether the @requested permissions are granted
798 * for the SID pair (@ssid, @tsid), interpreting the permissions
799 * based on @tclass, and call the security server on a cache miss to obtain
800 * a new decision and add it to the cache. Audit the granting or denial of
801 * permissions in accordance with the policy. Return %0 if all @requested
802 * permissions are granted, -%EACCES if any permissions are denied, or
803 * another -errno upon other errors.
804 */
805int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
Thomas Liu2bf49692009-07-14 12:14:09 -0400806 u32 requested, struct common_audit_data *auditdata)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807{
808 struct av_decision avd;
809 int rc;
810
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400811 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
813 return rc;
814}
Yuichi Nakamura788e7dd2007-09-14 09:27:07 +0900815
816u32 avc_policy_seqno(void)
817{
818 return avc_cache.latest_notif;
819}
Thomas Liu89c86572009-06-24 17:58:05 -0400820
821void avc_disable(void)
822{
Eric Paris5224ee02009-09-20 21:21:10 -0400823 /*
824 * If you are looking at this because you have realized that we are
825 * not destroying the avc_node_cachep it might be easy to fix, but
826 * I don't know the memory barrier semantics well enough to know. It's
827 * possible that some other task dereferenced security_ops when
828 * it still pointed to selinux operations. If that is the case it's
829 * possible that it is about to use the avc and is about to need the
830 * avc_node_cachep. I know I could wrap the security.c security_ops call
831 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
832 * the cache and get that memory back.
833 */
834 if (avc_node_cachep) {
835 avc_flush();
836 /* kmem_cache_destroy(avc_node_cachep); */
837 }
Thomas Liu89c86572009-06-24 17:58:05 -0400838}