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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
Linus Torvalds044aea92011-05-19 18:59:47 -070041#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
Linus Torvalds1da177e2005-04-16 15:20:36 -070042#else
43#define avc_cache_stats_incr(field) do {} while (0)
44#endif
45
46struct avc_entry {
47 u32 ssid;
48 u32 tsid;
49 u16 tclass;
50 struct av_decision avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -070051};
52
53struct avc_node {
54 struct avc_entry ae;
Eric Paris26036652009-02-12 14:51:04 -050055 struct hlist_node list; /* anchored in avc_cache->slots[i] */
Eric Paris95fff332008-04-17 14:42:10 -040056 struct rcu_head rhead;
Linus Torvalds1da177e2005-04-16 15:20:36 -070057};
58
59struct avc_cache {
Eric Paris26036652009-02-12 14:51:04 -050060 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
62 atomic_t lru_hint; /* LRU hint for reclaim scan */
63 atomic_t active_nodes;
64 u32 latest_notif; /* latest revocation notification */
65};
66
67struct avc_callback_node {
68 int (*callback) (u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -040069 u16 tclass, u32 perms,
70 u32 *out_retained);
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 u32 events;
72 u32 ssid;
73 u32 tsid;
74 u16 tclass;
75 u32 perms;
76 struct avc_callback_node *next;
77};
78
79/* Exported via selinufs */
80unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
81
82#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
83DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
84#endif
85
86static struct avc_cache avc_cache;
87static struct avc_callback_node *avc_callbacks;
Christoph Lametere18b8902006-12-06 20:33:20 -080088static struct kmem_cache *avc_node_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070089
90static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
91{
92 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
93}
94
95/**
96 * avc_dump_av - Display an access vector in human-readable form.
97 * @tclass: target security class
98 * @av: access vector
99 */
KaiGai Kohei44c2d9b2009-06-18 17:26:13 +0900100static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101{
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400102 const char **perms;
103 int i, perm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700104
105 if (av == 0) {
106 audit_log_format(ab, " null");
107 return;
108 }
109
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400110 perms = secclass_map[tclass-1].perms;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111
112 audit_log_format(ab, " {");
113 i = 0;
114 perm = 1;
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400115 while (i < (sizeof(av) * 8)) {
Eric Paris0bce9522009-11-23 16:47:23 -0500116 if ((perm & av) && perms[i]) {
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400117 audit_log_format(ab, " %s", perms[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 av &= ~perm;
119 }
120 i++;
121 perm <<= 1;
122 }
123
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 if (av)
125 audit_log_format(ab, " 0x%x", av);
126
127 audit_log_format(ab, " }");
128}
129
130/**
131 * avc_dump_query - Display a SID pair and a class in human-readable form.
132 * @ssid: source security identifier
133 * @tsid: target security identifier
134 * @tclass: target security class
135 */
136static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
137{
138 int rc;
139 char *scontext;
140 u32 scontext_len;
141
Eric Paris95fff332008-04-17 14:42:10 -0400142 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 if (rc)
144 audit_log_format(ab, "ssid=%d", ssid);
145 else {
146 audit_log_format(ab, "scontext=%s", scontext);
147 kfree(scontext);
148 }
149
150 rc = security_sid_to_context(tsid, &scontext, &scontext_len);
151 if (rc)
152 audit_log_format(ab, " tsid=%d", tsid);
153 else {
154 audit_log_format(ab, " tcontext=%s", scontext);
155 kfree(scontext);
156 }
Stephen Smalleya764ae42007-03-26 13:36:26 -0400157
Stephen Smalleyc6d3aaa2009-09-30 13:37:50 -0400158 BUG_ON(tclass >= ARRAY_SIZE(secclass_map));
159 audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160}
161
162/**
163 * avc_init - Initialize the AVC.
164 *
165 * Initialize the access vector cache.
166 */
167void __init avc_init(void)
168{
169 int i;
170
171 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Paris26036652009-02-12 14:51:04 -0500172 INIT_HLIST_HEAD(&avc_cache.slots[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 spin_lock_init(&avc_cache.slots_lock[i]);
174 }
175 atomic_set(&avc_cache.active_nodes, 0);
176 atomic_set(&avc_cache.lru_hint, 0);
177
178 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
Paul Mundt20c2df82007-07-20 10:11:58 +0900179 0, SLAB_PANIC, NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180
David Woodhouse9ad9ad32005-06-22 15:04:33 +0100181 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182}
183
184int avc_get_hash_stats(char *page)
185{
186 int i, chain_len, max_chain_len, slots_used;
187 struct avc_node *node;
Eric Paris26036652009-02-12 14:51:04 -0500188 struct hlist_head *head;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189
190 rcu_read_lock();
191
192 slots_used = 0;
193 max_chain_len = 0;
194 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500195 head = &avc_cache.slots[i];
Eric Paris26036652009-02-12 14:51:04 -0500196 if (!hlist_empty(head)) {
197 struct hlist_node *next;
198
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199 slots_used++;
200 chain_len = 0;
Eric Paris26036652009-02-12 14:51:04 -0500201 hlist_for_each_entry_rcu(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202 chain_len++;
203 if (chain_len > max_chain_len)
204 max_chain_len = chain_len;
205 }
206 }
207
208 rcu_read_unlock();
209
210 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
211 "longest chain: %d\n",
212 atomic_read(&avc_cache.active_nodes),
213 slots_used, AVC_CACHE_SLOTS, max_chain_len);
214}
215
216static void avc_node_free(struct rcu_head *rhead)
217{
218 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
219 kmem_cache_free(avc_node_cachep, node);
220 avc_cache_stats_incr(frees);
221}
222
223static void avc_node_delete(struct avc_node *node)
224{
Eric Paris26036652009-02-12 14:51:04 -0500225 hlist_del_rcu(&node->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 call_rcu(&node->rhead, avc_node_free);
227 atomic_dec(&avc_cache.active_nodes);
228}
229
230static void avc_node_kill(struct avc_node *node)
231{
232 kmem_cache_free(avc_node_cachep, node);
233 avc_cache_stats_incr(frees);
234 atomic_dec(&avc_cache.active_nodes);
235}
236
237static void avc_node_replace(struct avc_node *new, struct avc_node *old)
238{
Eric Paris26036652009-02-12 14:51:04 -0500239 hlist_replace_rcu(&old->list, &new->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 call_rcu(&old->rhead, avc_node_free);
241 atomic_dec(&avc_cache.active_nodes);
242}
243
244static inline int avc_reclaim_node(void)
245{
246 struct avc_node *node;
247 int hvalue, try, ecx;
248 unsigned long flags;
Eric Paris26036652009-02-12 14:51:04 -0500249 struct hlist_head *head;
250 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500251 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252
Eric Paris95fff332008-04-17 14:42:10 -0400253 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
Eric Parisedf3d1a2009-02-12 14:50:59 -0500255 head = &avc_cache.slots[hvalue];
256 lock = &avc_cache.slots_lock[hvalue];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257
Eric Parisedf3d1a2009-02-12 14:50:59 -0500258 if (!spin_trylock_irqsave(lock, flags))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259 continue;
260
Paul E. McKenney61844252008-04-21 18:12:33 -0700261 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500262 hlist_for_each_entry(node, next, head, list) {
Eric Paris906d27d2009-02-12 14:50:43 -0500263 avc_node_delete(node);
264 avc_cache_stats_incr(reclaims);
265 ecx++;
266 if (ecx >= AVC_CACHE_RECLAIM) {
267 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500268 spin_unlock_irqrestore(lock, flags);
Eric Paris906d27d2009-02-12 14:50:43 -0500269 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270 }
271 }
Paul E. McKenney61844252008-04-21 18:12:33 -0700272 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500273 spin_unlock_irqrestore(lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 }
275out:
276 return ecx;
277}
278
279static struct avc_node *avc_alloc_node(void)
280{
281 struct avc_node *node;
282
Robert P. J. Dayc3762222007-02-10 01:45:03 -0800283 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 if (!node)
285 goto out;
286
Eric Paris26036652009-02-12 14:51:04 -0500287 INIT_HLIST_NODE(&node->list);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 avc_cache_stats_incr(allocations);
289
290 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
291 avc_reclaim_node();
292
293out:
294 return node;
295}
296
Eric Paris21193dc2009-02-12 14:50:49 -0500297static 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 -0700298{
299 node->ae.ssid = ssid;
300 node->ae.tsid = tsid;
301 node->ae.tclass = tclass;
Eric Paris21193dc2009-02-12 14:50:49 -0500302 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303}
304
305static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
306{
307 struct avc_node *node, *ret = NULL;
308 int hvalue;
Eric Paris26036652009-02-12 14:51:04 -0500309 struct hlist_head *head;
310 struct hlist_node *next;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311
312 hvalue = avc_hash(ssid, tsid, tclass);
Eric Parisedf3d1a2009-02-12 14:50:59 -0500313 head = &avc_cache.slots[hvalue];
Eric Paris26036652009-02-12 14:51:04 -0500314 hlist_for_each_entry_rcu(node, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 if (ssid == node->ae.ssid &&
316 tclass == node->ae.tclass &&
317 tsid == node->ae.tsid) {
318 ret = node;
319 break;
320 }
321 }
322
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 return ret;
324}
325
326/**
327 * avc_lookup - Look up an AVC entry.
328 * @ssid: source security identifier
329 * @tsid: target security identifier
330 * @tclass: target security class
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 *
332 * Look up an AVC entry that is valid for the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 * (@ssid, @tsid), interpreting the permissions
334 * based on @tclass. If a valid AVC entry exists,
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800335 * then this function returns the avc_node.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 * Otherwise, this function returns NULL.
337 */
Eric Parisf1c63812009-02-12 14:50:54 -0500338static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700339{
340 struct avc_node *node;
341
342 avc_cache_stats_incr(lookups);
343 node = avc_search_node(ssid, tsid, tclass);
344
Eric Parisf1c63812009-02-12 14:50:54 -0500345 if (node)
Linus Torvalds257313b2011-05-19 21:22:53 -0700346 return node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347
Linus Torvalds257313b2011-05-19 21:22:53 -0700348 avc_cache_stats_incr(misses);
349 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350}
351
352static int avc_latest_notif_update(int seqno, int is_insert)
353{
354 int ret = 0;
355 static DEFINE_SPINLOCK(notif_lock);
356 unsigned long flag;
357
358 spin_lock_irqsave(&notif_lock, flag);
359 if (is_insert) {
360 if (seqno < avc_cache.latest_notif) {
Eric Paris744ba352008-04-17 11:52:44 -0400361 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 seqno, avc_cache.latest_notif);
363 ret = -EAGAIN;
364 }
365 } else {
366 if (seqno > avc_cache.latest_notif)
367 avc_cache.latest_notif = seqno;
368 }
369 spin_unlock_irqrestore(&notif_lock, flag);
370
371 return ret;
372}
373
374/**
375 * avc_insert - Insert an AVC entry.
376 * @ssid: source security identifier
377 * @tsid: target security identifier
378 * @tclass: target security class
Eric Paris21193dc2009-02-12 14:50:49 -0500379 * @avd: resulting av decision
Linus Torvalds1da177e2005-04-16 15:20:36 -0700380 *
381 * Insert an AVC entry for the SID pair
382 * (@ssid, @tsid) and class @tclass.
383 * The access vectors and the sequence number are
384 * normally provided by the security server in
385 * response to a security_compute_av() call. If the
Eric Paris21193dc2009-02-12 14:50:49 -0500386 * sequence number @avd->seqno is not less than the latest
Linus Torvalds1da177e2005-04-16 15:20:36 -0700387 * revocation notification, then the function copies
388 * the access vectors into a cache entry, returns
389 * avc_node inserted. Otherwise, this function returns NULL.
390 */
Eric Paris21193dc2009-02-12 14:50:49 -0500391static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700392{
393 struct avc_node *pos, *node = NULL;
394 int hvalue;
395 unsigned long flag;
396
Eric Paris21193dc2009-02-12 14:50:49 -0500397 if (avc_latest_notif_update(avd->seqno, 1))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700398 goto out;
399
400 node = avc_alloc_node();
401 if (node) {
Eric Paris26036652009-02-12 14:51:04 -0500402 struct hlist_head *head;
403 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500404 spinlock_t *lock;
405
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 hvalue = avc_hash(ssid, tsid, tclass);
Eric Paris21193dc2009-02-12 14:50:49 -0500407 avc_node_populate(node, ssid, tsid, tclass, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408
Eric Parisedf3d1a2009-02-12 14:50:59 -0500409 head = &avc_cache.slots[hvalue];
410 lock = &avc_cache.slots_lock[hvalue];
411
412 spin_lock_irqsave(lock, flag);
Eric Paris26036652009-02-12 14:51:04 -0500413 hlist_for_each_entry(pos, next, head, list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414 if (pos->ae.ssid == ssid &&
415 pos->ae.tsid == tsid &&
416 pos->ae.tclass == tclass) {
Eric Paris95fff332008-04-17 14:42:10 -0400417 avc_node_replace(node, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 goto found;
419 }
420 }
Eric Paris26036652009-02-12 14:51:04 -0500421 hlist_add_head_rcu(&node->list, head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700422found:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500423 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 }
425out:
426 return node;
427}
428
Thomas Liu2bf49692009-07-14 12:14:09 -0400429/**
430 * avc_audit_pre_callback - SELinux specific information
431 * will be called by generic audit code
432 * @ab: the audit buffer
433 * @a: audit_data
434 */
435static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436{
Thomas Liu2bf49692009-07-14 12:14:09 -0400437 struct common_audit_data *ad = a;
438 audit_log_format(ab, "avc: %s ",
439 ad->selinux_audit_data.denied ? "denied" : "granted");
440 avc_dump_av(ab, ad->selinux_audit_data.tclass,
441 ad->selinux_audit_data.audited);
442 audit_log_format(ab, " for ");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443}
444
Thomas Liu2bf49692009-07-14 12:14:09 -0400445/**
446 * avc_audit_post_callback - SELinux specific information
447 * will be called by generic audit code
448 * @ab: the audit buffer
449 * @a: audit_data
450 */
451static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452{
Thomas Liu2bf49692009-07-14 12:14:09 -0400453 struct common_audit_data *ad = a;
454 audit_log_format(ab, " ");
455 avc_dump_query(ab, ad->selinux_audit_data.ssid,
456 ad->selinux_audit_data.tsid,
457 ad->selinux_audit_data.tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458}
459
460/**
461 * avc_audit - Audit the granting or denial of permissions.
462 * @ssid: source security identifier
463 * @tsid: target security identifier
464 * @tclass: target security class
465 * @requested: requested permissions
466 * @avd: access vector decisions
467 * @result: result from avc_has_perm_noaudit
468 * @a: auxiliary audit data
Eric Paris9ade0cf2011-04-25 16:26:29 -0400469 * @flags: VFS walk flags
Linus Torvalds1da177e2005-04-16 15:20:36 -0700470 *
471 * Audit the granting or denial of permissions in accordance
472 * with the policy. This function is typically called by
473 * avc_has_perm() after a permission check, but can also be
474 * called directly by callers who use avc_has_perm_noaudit()
475 * in order to separate the permission check from the auditing.
476 * For example, this separation is useful when the permission check must
477 * be performed under a lock, to allow the lock to be released
478 * before calling the auditing code.
479 */
Eric Paris9ade0cf2011-04-25 16:26:29 -0400480int avc_audit(u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400481 u16 tclass, u32 requested,
Eric Paris9ade0cf2011-04-25 16:26:29 -0400482 struct av_decision *avd, int result, struct common_audit_data *a,
483 unsigned flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484{
Thomas Liu2bf49692009-07-14 12:14:09 -0400485 struct common_audit_data stack_data;
James Morrisbe940d62009-07-13 10:39:36 +1000486 u32 denied, audited;
James Morrisbe940d62009-07-13 10:39:36 +1000487 denied = requested & ~avd->allowed;
Eric Parisb782e0a2010-07-23 11:44:03 -0400488 if (denied) {
Stephen Smalleyb6cac5a2010-02-02 11:31:51 -0500489 audited = denied & avd->auditdeny;
Eric Parisb782e0a2010-07-23 11:44:03 -0400490 /*
491 * a->selinux_audit_data.auditdeny is TRICKY! Setting a bit in
492 * this field means that ANY denials should NOT be audited if
493 * the policy contains an explicit dontaudit rule for that
494 * permission. Take notice that this is unrelated to the
495 * actual permissions that were denied. As an example lets
496 * assume:
497 *
498 * denied == READ
499 * avd.auditdeny & ACCESS == 0 (not set means explicit rule)
500 * selinux_audit_data.auditdeny & ACCESS == 1
501 *
502 * We will NOT audit the denial even though the denied
503 * permission was READ and the auditdeny checks were for
504 * ACCESS
505 */
506 if (a &&
507 a->selinux_audit_data.auditdeny &&
508 !(a->selinux_audit_data.auditdeny & avd->auditdeny))
509 audited = 0;
510 } else if (result)
James Morrisbe940d62009-07-13 10:39:36 +1000511 audited = denied = requested;
Stephen Smalleyb6cac5a2010-02-02 11:31:51 -0500512 else
513 audited = requested & avd->auditallow;
514 if (!audited)
Eric Paris9ade0cf2011-04-25 16:26:29 -0400515 return 0;
516
Thomas Liu2bf49692009-07-14 12:14:09 -0400517 if (!a) {
518 a = &stack_data;
Eric Pariscb84aa92010-04-27 17:20:38 -0400519 COMMON_AUDIT_DATA_INIT(a, NONE);
James Morrisbe940d62009-07-13 10:39:36 +1000520 }
Eric Paris9ade0cf2011-04-25 16:26:29 -0400521
522 /*
523 * When in a RCU walk do the audit on the RCU retry. This is because
524 * the collection of the dname in an inode audit message is not RCU
525 * safe. Note this may drop some audits when the situation changes
526 * during retry. However this is logically just as if the operation
527 * happened a little later.
528 */
Eric Parisf48b7392011-04-25 12:54:27 -0400529 if ((a->type == LSM_AUDIT_DATA_INODE) &&
Al Virocf1dd1d2011-06-20 19:44:08 -0400530 (flags & MAY_NOT_BLOCK))
Eric Paris9ade0cf2011-04-25 16:26:29 -0400531 return -ECHILD;
532
Thomas Liu2bf49692009-07-14 12:14:09 -0400533 a->selinux_audit_data.tclass = tclass;
534 a->selinux_audit_data.requested = requested;
535 a->selinux_audit_data.ssid = ssid;
536 a->selinux_audit_data.tsid = tsid;
537 a->selinux_audit_data.audited = audited;
538 a->selinux_audit_data.denied = denied;
539 a->lsm_pre_audit = avc_audit_pre_callback;
540 a->lsm_post_audit = avc_audit_post_callback;
541 common_lsm_audit(a);
Eric Paris9ade0cf2011-04-25 16:26:29 -0400542 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543}
544
545/**
546 * avc_add_callback - Register a callback for security events.
547 * @callback: callback function
548 * @events: security events
549 * @ssid: source security identifier or %SECSID_WILD
550 * @tsid: target security identifier or %SECSID_WILD
551 * @tclass: target security class
552 * @perms: permissions
553 *
554 * Register a callback function for events in the set @events
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800555 * related to the SID pair (@ssid, @tsid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 * and the permissions @perms, interpreting
557 * @perms based on @tclass. Returns %0 on success or
558 * -%ENOMEM if insufficient memory exists to add the callback.
559 */
560int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400561 u16 tclass, u32 perms,
562 u32 *out_retained),
563 u32 events, u32 ssid, u32 tsid,
564 u16 tclass, u32 perms)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565{
566 struct avc_callback_node *c;
567 int rc = 0;
568
569 c = kmalloc(sizeof(*c), GFP_ATOMIC);
570 if (!c) {
571 rc = -ENOMEM;
572 goto out;
573 }
574
575 c->callback = callback;
576 c->events = events;
577 c->ssid = ssid;
578 c->tsid = tsid;
579 c->perms = perms;
580 c->next = avc_callbacks;
581 avc_callbacks = c;
582out:
583 return rc;
584}
585
586static inline int avc_sidcmp(u32 x, u32 y)
587{
588 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
589}
590
591/**
592 * avc_update_node Update an AVC entry
593 * @event : Updating event
594 * @perms : Permission mask bits
595 * @ssid,@tsid,@tclass : identifier of an AVC entry
Eric Parisa5dda682009-02-12 14:50:11 -0500596 * @seqno : sequence number when decision was made
Linus Torvalds1da177e2005-04-16 15:20:36 -0700597 *
598 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
599 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800600 * otherwise, this function updates the AVC entry. The original AVC-entry object
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601 * will release later by RCU.
602 */
Eric Parisa5dda682009-02-12 14:50:11 -0500603static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
604 u32 seqno)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605{
606 int hvalue, rc = 0;
607 unsigned long flag;
608 struct avc_node *pos, *node, *orig = NULL;
Eric Paris26036652009-02-12 14:51:04 -0500609 struct hlist_head *head;
610 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500611 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612
613 node = avc_alloc_node();
614 if (!node) {
615 rc = -ENOMEM;
616 goto out;
617 }
618
619 /* Lock the target slot */
620 hvalue = avc_hash(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700621
Eric Parisedf3d1a2009-02-12 14:50:59 -0500622 head = &avc_cache.slots[hvalue];
623 lock = &avc_cache.slots_lock[hvalue];
624
625 spin_lock_irqsave(lock, flag);
626
Eric Paris26036652009-02-12 14:51:04 -0500627 hlist_for_each_entry(pos, next, head, list) {
Eric Paris95fff332008-04-17 14:42:10 -0400628 if (ssid == pos->ae.ssid &&
629 tsid == pos->ae.tsid &&
Eric Parisa5dda682009-02-12 14:50:11 -0500630 tclass == pos->ae.tclass &&
631 seqno == pos->ae.avd.seqno){
Linus Torvalds1da177e2005-04-16 15:20:36 -0700632 orig = pos;
633 break;
634 }
635 }
636
637 if (!orig) {
638 rc = -ENOENT;
639 avc_node_kill(node);
640 goto out_unlock;
641 }
642
643 /*
644 * Copy and replace original node.
645 */
646
Eric Paris21193dc2009-02-12 14:50:49 -0500647 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648
649 switch (event) {
650 case AVC_CALLBACK_GRANT:
651 node->ae.avd.allowed |= perms;
652 break;
653 case AVC_CALLBACK_TRY_REVOKE:
654 case AVC_CALLBACK_REVOKE:
655 node->ae.avd.allowed &= ~perms;
656 break;
657 case AVC_CALLBACK_AUDITALLOW_ENABLE:
658 node->ae.avd.auditallow |= perms;
659 break;
660 case AVC_CALLBACK_AUDITALLOW_DISABLE:
661 node->ae.avd.auditallow &= ~perms;
662 break;
663 case AVC_CALLBACK_AUDITDENY_ENABLE:
664 node->ae.avd.auditdeny |= perms;
665 break;
666 case AVC_CALLBACK_AUDITDENY_DISABLE:
667 node->ae.avd.auditdeny &= ~perms;
668 break;
669 }
670 avc_node_replace(node, orig);
671out_unlock:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500672 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673out:
674 return rc;
675}
676
677/**
Eric Paris008574b2009-09-12 22:54:17 -0400678 * avc_flush - Flush the cache
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 */
Eric Paris008574b2009-09-12 22:54:17 -0400680static void avc_flush(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681{
Eric Paris26036652009-02-12 14:51:04 -0500682 struct hlist_head *head;
683 struct hlist_node *next;
Eric Paris008574b2009-09-12 22:54:17 -0400684 struct avc_node *node;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500685 spinlock_t *lock;
Eric Paris008574b2009-09-12 22:54:17 -0400686 unsigned long flag;
687 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688
689 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500690 head = &avc_cache.slots[i];
691 lock = &avc_cache.slots_lock[i];
692
693 spin_lock_irqsave(lock, flag);
Paul E. McKenney61844252008-04-21 18:12:33 -0700694 /*
695 * With preemptable RCU, the outer spinlock does not
696 * prevent RCU grace periods from ending.
697 */
698 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500699 hlist_for_each_entry(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700700 avc_node_delete(node);
Paul E. McKenney61844252008-04-21 18:12:33 -0700701 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500702 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 }
Eric Paris008574b2009-09-12 22:54:17 -0400704}
705
706/**
707 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
708 * @seqno: policy sequence number
709 */
710int avc_ss_reset(u32 seqno)
711{
712 struct avc_callback_node *c;
713 int rc = 0, tmprc;
714
715 avc_flush();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716
717 for (c = avc_callbacks; c; c = c->next) {
718 if (c->events & AVC_CALLBACK_RESET) {
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600719 tmprc = c->callback(AVC_CALLBACK_RESET,
Eric Paris95fff332008-04-17 14:42:10 -0400720 0, 0, 0, 0, NULL);
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600721 /* save the first error encountered for the return
722 value and continue processing the callbacks */
723 if (!rc)
724 rc = tmprc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700725 }
726 }
727
728 avc_latest_notif_update(seqno, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 return rc;
730}
731
732/**
733 * avc_has_perm_noaudit - Check permissions but perform no auditing.
734 * @ssid: source security identifier
735 * @tsid: target security identifier
736 * @tclass: target security class
737 * @requested: requested permissions, interpreted based on @tclass
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400738 * @flags: AVC_STRICT or 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700739 * @avd: access vector decisions
740 *
741 * Check the AVC to determine whether the @requested permissions are granted
742 * for the SID pair (@ssid, @tsid), interpreting the permissions
743 * based on @tclass, and call the security server on a cache miss to obtain
744 * a new decision and add it to the cache. Return a copy of the decisions
745 * in @avd. Return %0 if all @requested permissions are granted,
746 * -%EACCES if any permissions are denied, or another -errno upon
747 * other errors. This function is typically called by avc_has_perm(),
748 * but may also be called directly to separate permission checking from
749 * auditing, e.g. in cases where a lock must be held for the check but
750 * should be released for the auditing.
751 */
752int avc_has_perm_noaudit(u32 ssid, u32 tsid,
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400753 u16 tclass, u32 requested,
754 unsigned flags,
Linus Torvaldsf01e1af2011-05-24 13:48:51 -0700755 struct av_decision *avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756{
757 struct avc_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 int rc = 0;
759 u32 denied;
760
Eric Pariseda4f692008-03-11 14:19:34 -0400761 BUG_ON(!requested);
762
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 rcu_read_lock();
764
Eric Parisf1c63812009-02-12 14:50:54 -0500765 node = avc_lookup(ssid, tsid, tclass);
Linus Torvalds257313b2011-05-19 21:22:53 -0700766 if (unlikely(!node)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 rcu_read_unlock();
Stephen Smalley19439d02010-01-14 17:28:10 -0500768 security_compute_av(ssid, tsid, tclass, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769 rcu_read_lock();
Eric Paris21193dc2009-02-12 14:50:49 -0500770 node = avc_insert(ssid, tsid, tclass, avd);
771 } else {
Linus Torvaldsf01e1af2011-05-24 13:48:51 -0700772 memcpy(avd, &node->ae.avd, sizeof(*avd));
Eric Paris21193dc2009-02-12 14:50:49 -0500773 avd = &node->ae.avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 }
775
Eric Paris21193dc2009-02-12 14:50:49 -0500776 denied = requested & ~(avd->allowed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777
Eric Pariseda4f692008-03-11 14:19:34 -0400778 if (denied) {
Eric Paris64dbf072008-03-31 12:17:33 +1100779 if (flags & AVC_STRICT)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 rc = -EACCES;
KaiGai Kohei8a6f83a2009-04-01 10:07:57 +0900781 else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE))
Eric Paris64dbf072008-03-31 12:17:33 +1100782 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
Eric Paris21193dc2009-02-12 14:50:49 -0500783 tsid, tclass, avd->seqno);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 else
Eric Paris64dbf072008-03-31 12:17:33 +1100785 rc = -EACCES;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 }
787
788 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 return rc;
790}
791
792/**
793 * avc_has_perm - Check permissions and perform any appropriate auditing.
794 * @ssid: source security identifier
795 * @tsid: target security identifier
796 * @tclass: target security class
797 * @requested: requested permissions, interpreted based on @tclass
798 * @auditdata: auxiliary audit data
Eric Paris9ade0cf2011-04-25 16:26:29 -0400799 * @flags: VFS walk flags
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 *
801 * Check the AVC to determine whether the @requested permissions are granted
802 * for the SID pair (@ssid, @tsid), interpreting the permissions
803 * based on @tclass, and call the security server on a cache miss to obtain
804 * a new decision and add it to the cache. Audit the granting or denial of
805 * permissions in accordance with the policy. Return %0 if all @requested
806 * permissions are granted, -%EACCES if any permissions are denied, or
807 * another -errno upon other errors.
808 */
Eric Paris9ade0cf2011-04-25 16:26:29 -0400809int avc_has_perm_flags(u32 ssid, u32 tsid, u16 tclass,
810 u32 requested, struct common_audit_data *auditdata,
811 unsigned flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812{
813 struct av_decision avd;
Eric Paris9ade0cf2011-04-25 16:26:29 -0400814 int rc, rc2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400816 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
Eric Paris9ade0cf2011-04-25 16:26:29 -0400817
818 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata,
819 flags);
820 if (rc2)
821 return rc2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822 return rc;
823}
Yuichi Nakamura788e7dd2007-09-14 09:27:07 +0900824
825u32 avc_policy_seqno(void)
826{
827 return avc_cache.latest_notif;
828}
Thomas Liu89c86572009-06-24 17:58:05 -0400829
830void avc_disable(void)
831{
Eric Paris5224ee02009-09-20 21:21:10 -0400832 /*
833 * If you are looking at this because you have realized that we are
834 * not destroying the avc_node_cachep it might be easy to fix, but
835 * I don't know the memory barrier semantics well enough to know. It's
836 * possible that some other task dereferenced security_ops when
837 * it still pointed to selinux operations. If that is the case it's
838 * possible that it is about to use the avc and is about to need the
839 * avc_node_cachep. I know I could wrap the security.c security_ops call
840 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
841 * the cache and get that memory back.
842 */
843 if (avc_node_cachep) {
844 avc_flush();
845 /* kmem_cache_destroy(avc_node_cachep); */
846 }
Thomas Liu89c86572009-06-24 17:58:05 -0400847}