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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 ",
Eric Paris3f0882c2012-04-03 09:38:00 -0700439 ad->selinux_audit_data->slad->denied ? "denied" : "granted");
440 avc_dump_av(ab, ad->selinux_audit_data->slad->tclass,
441 ad->selinux_audit_data->slad->audited);
Thomas Liu2bf49692009-07-14 12:14:09 -0400442 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, " ");
Eric Paris3f0882c2012-04-03 09:38:00 -0700455 avc_dump_query(ab, ad->selinux_audit_data->slad->ssid,
456 ad->selinux_audit_data->slad->tsid,
457 ad->selinux_audit_data->slad->tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700458}
459
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700460/* This is the slow part of avc audit with big stack footprint */
461static noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
462 u32 requested, u32 audited, u32 denied,
Eric Parisf8294f12012-04-02 13:15:55 -0400463 struct common_audit_data *a,
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700464 unsigned flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700465{
Thomas Liu2bf49692009-07-14 12:14:09 -0400466 struct common_audit_data stack_data;
Eric Paris3b3b0e42012-04-03 09:37:02 -0700467 struct selinux_audit_data sad = {0,};
Eric Paris3f0882c2012-04-03 09:38:00 -0700468 struct selinux_late_audit_data slad;
Eric Paris9ade0cf2011-04-25 16:26:29 -0400469
Thomas Liu2bf49692009-07-14 12:14:09 -0400470 if (!a) {
471 a = &stack_data;
Eric Pariscb84aa92010-04-27 17:20:38 -0400472 COMMON_AUDIT_DATA_INIT(a, NONE);
Eric Paris3b3b0e42012-04-03 09:37:02 -0700473 a->selinux_audit_data = &sad;
James Morrisbe940d62009-07-13 10:39:36 +1000474 }
Eric Paris9ade0cf2011-04-25 16:26:29 -0400475
476 /*
477 * When in a RCU walk do the audit on the RCU retry. This is because
478 * the collection of the dname in an inode audit message is not RCU
479 * safe. Note this may drop some audits when the situation changes
480 * during retry. However this is logically just as if the operation
481 * happened a little later.
482 */
Eric Parisf48b7392011-04-25 12:54:27 -0400483 if ((a->type == LSM_AUDIT_DATA_INODE) &&
Al Virocf1dd1d2011-06-20 19:44:08 -0400484 (flags & MAY_NOT_BLOCK))
Eric Paris9ade0cf2011-04-25 16:26:29 -0400485 return -ECHILD;
486
Eric Paris3f0882c2012-04-03 09:38:00 -0700487 slad.tclass = tclass;
488 slad.requested = requested;
489 slad.ssid = ssid;
490 slad.tsid = tsid;
491 slad.audited = audited;
492 slad.denied = denied;
493
494 a->selinux_audit_data->slad = &slad;
Linus Torvaldsb61c37f2012-04-02 15:48:12 -0700495 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
Eric Paris9ade0cf2011-04-25 16:26:29 -0400496 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700497}
498
499/**
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700500 * avc_audit - Audit the granting or denial of permissions.
501 * @ssid: source security identifier
502 * @tsid: target security identifier
503 * @tclass: target security class
504 * @requested: requested permissions
505 * @avd: access vector decisions
506 * @result: result from avc_has_perm_noaudit
507 * @a: auxiliary audit data
508 * @flags: VFS walk flags
509 *
510 * Audit the granting or denial of permissions in accordance
511 * with the policy. This function is typically called by
512 * avc_has_perm() after a permission check, but can also be
513 * called directly by callers who use avc_has_perm_noaudit()
514 * in order to separate the permission check from the auditing.
515 * For example, this separation is useful when the permission check must
516 * be performed under a lock, to allow the lock to be released
517 * before calling the auditing code.
518 */
Linus Torvaldscdb0f9a2012-03-31 11:12:57 -0700519inline int avc_audit(u32 ssid, u32 tsid,
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700520 u16 tclass, u32 requested,
521 struct av_decision *avd, int result, struct common_audit_data *a,
522 unsigned flags)
523{
524 u32 denied, audited;
525 denied = requested & ~avd->allowed;
526 if (unlikely(denied)) {
527 audited = denied & avd->auditdeny;
528 /*
Eric Paris3b3b0e42012-04-03 09:37:02 -0700529 * a->selinux_audit_data->auditdeny is TRICKY! Setting a bit in
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700530 * this field means that ANY denials should NOT be audited if
531 * the policy contains an explicit dontaudit rule for that
532 * permission. Take notice that this is unrelated to the
533 * actual permissions that were denied. As an example lets
534 * assume:
535 *
536 * denied == READ
537 * avd.auditdeny & ACCESS == 0 (not set means explicit rule)
Eric Paris3b3b0e42012-04-03 09:37:02 -0700538 * selinux_audit_data->auditdeny & ACCESS == 1
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700539 *
540 * We will NOT audit the denial even though the denied
541 * permission was READ and the auditdeny checks were for
542 * ACCESS
543 */
544 if (a &&
Eric Paris3b3b0e42012-04-03 09:37:02 -0700545 a->selinux_audit_data->auditdeny &&
546 !(a->selinux_audit_data->auditdeny & avd->auditdeny))
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700547 audited = 0;
548 } else if (result)
549 audited = denied = requested;
550 else
551 audited = requested & avd->auditallow;
552 if (likely(!audited))
553 return 0;
554
555 return slow_avc_audit(ssid, tsid, tclass,
556 requested, audited, denied,
Eric Parisf8294f12012-04-02 13:15:55 -0400557 a, flags);
Linus Torvalds48aab2f2012-03-22 17:01:41 -0700558}
559
560/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700561 * avc_add_callback - Register a callback for security events.
562 * @callback: callback function
563 * @events: security events
564 * @ssid: source security identifier or %SECSID_WILD
565 * @tsid: target security identifier or %SECSID_WILD
566 * @tclass: target security class
567 * @perms: permissions
568 *
569 * Register a callback function for events in the set @events
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800570 * related to the SID pair (@ssid, @tsid)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 * and the permissions @perms, interpreting
572 * @perms based on @tclass. Returns %0 on success or
573 * -%ENOMEM if insufficient memory exists to add the callback.
574 */
575int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
Eric Paris95fff332008-04-17 14:42:10 -0400576 u16 tclass, u32 perms,
577 u32 *out_retained),
578 u32 events, u32 ssid, u32 tsid,
579 u16 tclass, u32 perms)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700580{
581 struct avc_callback_node *c;
582 int rc = 0;
583
584 c = kmalloc(sizeof(*c), GFP_ATOMIC);
585 if (!c) {
586 rc = -ENOMEM;
587 goto out;
588 }
589
590 c->callback = callback;
591 c->events = events;
592 c->ssid = ssid;
593 c->tsid = tsid;
594 c->perms = perms;
595 c->next = avc_callbacks;
596 avc_callbacks = c;
597out:
598 return rc;
599}
600
601static inline int avc_sidcmp(u32 x, u32 y)
602{
603 return (x == y || x == SECSID_WILD || y == SECSID_WILD);
604}
605
606/**
607 * avc_update_node Update an AVC entry
608 * @event : Updating event
609 * @perms : Permission mask bits
610 * @ssid,@tsid,@tclass : identifier of an AVC entry
Eric Parisa5dda6832009-02-12 14:50:11 -0500611 * @seqno : sequence number when decision was made
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612 *
613 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
614 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
Justin P. Mattock6382dc32010-01-14 23:03:18 -0800615 * otherwise, this function updates the AVC entry. The original AVC-entry object
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 * will release later by RCU.
617 */
Eric Parisa5dda6832009-02-12 14:50:11 -0500618static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass,
619 u32 seqno)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620{
621 int hvalue, rc = 0;
622 unsigned long flag;
623 struct avc_node *pos, *node, *orig = NULL;
Eric Paris26036652009-02-12 14:51:04 -0500624 struct hlist_head *head;
625 struct hlist_node *next;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500626 spinlock_t *lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627
628 node = avc_alloc_node();
629 if (!node) {
630 rc = -ENOMEM;
631 goto out;
632 }
633
634 /* Lock the target slot */
635 hvalue = avc_hash(ssid, tsid, tclass);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636
Eric Parisedf3d1a2009-02-12 14:50:59 -0500637 head = &avc_cache.slots[hvalue];
638 lock = &avc_cache.slots_lock[hvalue];
639
640 spin_lock_irqsave(lock, flag);
641
Eric Paris26036652009-02-12 14:51:04 -0500642 hlist_for_each_entry(pos, next, head, list) {
Eric Paris95fff332008-04-17 14:42:10 -0400643 if (ssid == pos->ae.ssid &&
644 tsid == pos->ae.tsid &&
Eric Parisa5dda6832009-02-12 14:50:11 -0500645 tclass == pos->ae.tclass &&
646 seqno == pos->ae.avd.seqno){
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 orig = pos;
648 break;
649 }
650 }
651
652 if (!orig) {
653 rc = -ENOENT;
654 avc_node_kill(node);
655 goto out_unlock;
656 }
657
658 /*
659 * Copy and replace original node.
660 */
661
Eric Paris21193dc2009-02-12 14:50:49 -0500662 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663
664 switch (event) {
665 case AVC_CALLBACK_GRANT:
666 node->ae.avd.allowed |= perms;
667 break;
668 case AVC_CALLBACK_TRY_REVOKE:
669 case AVC_CALLBACK_REVOKE:
670 node->ae.avd.allowed &= ~perms;
671 break;
672 case AVC_CALLBACK_AUDITALLOW_ENABLE:
673 node->ae.avd.auditallow |= perms;
674 break;
675 case AVC_CALLBACK_AUDITALLOW_DISABLE:
676 node->ae.avd.auditallow &= ~perms;
677 break;
678 case AVC_CALLBACK_AUDITDENY_ENABLE:
679 node->ae.avd.auditdeny |= perms;
680 break;
681 case AVC_CALLBACK_AUDITDENY_DISABLE:
682 node->ae.avd.auditdeny &= ~perms;
683 break;
684 }
685 avc_node_replace(node, orig);
686out_unlock:
Eric Parisedf3d1a2009-02-12 14:50:59 -0500687 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688out:
689 return rc;
690}
691
692/**
Eric Paris008574b2009-09-12 22:54:17 -0400693 * avc_flush - Flush the cache
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 */
Eric Paris008574b2009-09-12 22:54:17 -0400695static void avc_flush(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696{
Eric Paris26036652009-02-12 14:51:04 -0500697 struct hlist_head *head;
698 struct hlist_node *next;
Eric Paris008574b2009-09-12 22:54:17 -0400699 struct avc_node *node;
Eric Parisedf3d1a2009-02-12 14:50:59 -0500700 spinlock_t *lock;
Eric Paris008574b2009-09-12 22:54:17 -0400701 unsigned long flag;
702 int i;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703
704 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
Eric Parisedf3d1a2009-02-12 14:50:59 -0500705 head = &avc_cache.slots[i];
706 lock = &avc_cache.slots_lock[i];
707
708 spin_lock_irqsave(lock, flag);
Paul E. McKenney61844252008-04-21 18:12:33 -0700709 /*
710 * With preemptable RCU, the outer spinlock does not
711 * prevent RCU grace periods from ending.
712 */
713 rcu_read_lock();
Eric Paris26036652009-02-12 14:51:04 -0500714 hlist_for_each_entry(node, next, head, list)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 avc_node_delete(node);
Paul E. McKenney61844252008-04-21 18:12:33 -0700716 rcu_read_unlock();
Eric Parisedf3d1a2009-02-12 14:50:59 -0500717 spin_unlock_irqrestore(lock, flag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718 }
Eric Paris008574b2009-09-12 22:54:17 -0400719}
720
721/**
722 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
723 * @seqno: policy sequence number
724 */
725int avc_ss_reset(u32 seqno)
726{
727 struct avc_callback_node *c;
728 int rc = 0, tmprc;
729
730 avc_flush();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700731
732 for (c = avc_callbacks; c; c = c->next) {
733 if (c->events & AVC_CALLBACK_RESET) {
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600734 tmprc = c->callback(AVC_CALLBACK_RESET,
Eric Paris95fff332008-04-17 14:42:10 -0400735 0, 0, 0, 0, NULL);
Darrel Goeddel376bd9c2006-02-24 15:44:05 -0600736 /* save the first error encountered for the return
737 value and continue processing the callbacks */
738 if (!rc)
739 rc = tmprc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 }
741 }
742
743 avc_latest_notif_update(seqno, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744 return rc;
745}
746
Linus Torvaldsa554bea2012-03-31 10:58:08 -0700747/*
748 * Slow-path helper function for avc_has_perm_noaudit,
749 * when the avc_node lookup fails. We get called with
750 * the RCU read lock held, and need to return with it
751 * still held, but drop if for the security compute.
752 *
753 * Don't inline this, since it's the slow-path and just
754 * results in a bigger stack frame.
755 */
756static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid,
757 u16 tclass, struct av_decision *avd)
758{
759 rcu_read_unlock();
760 security_compute_av(ssid, tsid, tclass, avd);
761 rcu_read_lock();
762 return avc_insert(ssid, tsid, tclass, avd);
763}
764
765static noinline int avc_denied(u32 ssid, u32 tsid,
766 u16 tclass, u32 requested,
767 unsigned flags,
768 struct av_decision *avd)
769{
770 if (flags & AVC_STRICT)
771 return -EACCES;
772
773 if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE))
774 return -EACCES;
775
776 avc_update_node(AVC_CALLBACK_GRANT, requested, ssid,
777 tsid, tclass, avd->seqno);
778 return 0;
779}
780
781
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782/**
783 * avc_has_perm_noaudit - Check permissions but perform no auditing.
784 * @ssid: source security identifier
785 * @tsid: target security identifier
786 * @tclass: target security class
787 * @requested: requested permissions, interpreted based on @tclass
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400788 * @flags: AVC_STRICT or 0
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 * @avd: access vector decisions
790 *
791 * Check the AVC to determine whether the @requested permissions are granted
792 * for the SID pair (@ssid, @tsid), interpreting the permissions
793 * based on @tclass, and call the security server on a cache miss to obtain
794 * a new decision and add it to the cache. Return a copy of the decisions
795 * in @avd. Return %0 if all @requested permissions are granted,
796 * -%EACCES if any permissions are denied, or another -errno upon
797 * other errors. This function is typically called by avc_has_perm(),
798 * but may also be called directly to separate permission checking from
799 * auditing, e.g. in cases where a lock must be held for the check but
800 * should be released for the auditing.
801 */
Linus Torvaldscdb0f9a2012-03-31 11:12:57 -0700802inline int avc_has_perm_noaudit(u32 ssid, u32 tsid,
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400803 u16 tclass, u32 requested,
804 unsigned flags,
Linus Torvaldsf01e1af2011-05-24 13:48:51 -0700805 struct av_decision *avd)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806{
807 struct avc_node *node;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 int rc = 0;
809 u32 denied;
810
Eric Pariseda4f692008-03-11 14:19:34 -0400811 BUG_ON(!requested);
812
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813 rcu_read_lock();
814
Eric Parisf1c63812009-02-12 14:50:54 -0500815 node = avc_lookup(ssid, tsid, tclass);
Linus Torvalds257313b2011-05-19 21:22:53 -0700816 if (unlikely(!node)) {
Linus Torvaldsa554bea2012-03-31 10:58:08 -0700817 node = avc_compute_av(ssid, tsid, tclass, avd);
Eric Paris21193dc2009-02-12 14:50:49 -0500818 } else {
Linus Torvaldsf01e1af2011-05-24 13:48:51 -0700819 memcpy(avd, &node->ae.avd, sizeof(*avd));
Eric Paris21193dc2009-02-12 14:50:49 -0500820 avd = &node->ae.avd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 }
822
Eric Paris21193dc2009-02-12 14:50:49 -0500823 denied = requested & ~(avd->allowed);
Linus Torvaldsa554bea2012-03-31 10:58:08 -0700824 if (unlikely(denied))
825 rc = avc_denied(ssid, tsid, tclass, requested, flags, avd);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826
827 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700828 return rc;
829}
830
831/**
832 * avc_has_perm - Check permissions and perform any appropriate auditing.
833 * @ssid: source security identifier
834 * @tsid: target security identifier
835 * @tclass: target security class
836 * @requested: requested permissions, interpreted based on @tclass
837 * @auditdata: auxiliary audit data
Eric Paris9ade0cf2011-04-25 16:26:29 -0400838 * @flags: VFS walk flags
Linus Torvalds1da177e2005-04-16 15:20:36 -0700839 *
840 * Check the AVC to determine whether the @requested permissions are granted
841 * for the SID pair (@ssid, @tsid), interpreting the permissions
842 * based on @tclass, and call the security server on a cache miss to obtain
843 * a new decision and add it to the cache. Audit the granting or denial of
844 * permissions in accordance with the policy. Return %0 if all @requested
845 * permissions are granted, -%EACCES if any permissions are denied, or
846 * another -errno upon other errors.
847 */
Eric Paris9ade0cf2011-04-25 16:26:29 -0400848int avc_has_perm_flags(u32 ssid, u32 tsid, u16 tclass,
849 u32 requested, struct common_audit_data *auditdata,
850 unsigned flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700851{
852 struct av_decision avd;
Eric Paris9ade0cf2011-04-25 16:26:29 -0400853 int rc, rc2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854
Stephen Smalley2c3c05d2007-06-07 15:34:10 -0400855 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
Eric Paris9ade0cf2011-04-25 16:26:29 -0400856
857 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata,
858 flags);
859 if (rc2)
860 return rc2;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700861 return rc;
862}
Yuichi Nakamura788e7dd2007-09-14 09:27:07 +0900863
864u32 avc_policy_seqno(void)
865{
866 return avc_cache.latest_notif;
867}
Thomas Liu89c86572009-06-24 17:58:05 -0400868
869void avc_disable(void)
870{
Eric Paris5224ee02009-09-20 21:21:10 -0400871 /*
872 * If you are looking at this because you have realized that we are
873 * not destroying the avc_node_cachep it might be easy to fix, but
874 * I don't know the memory barrier semantics well enough to know. It's
875 * possible that some other task dereferenced security_ops when
876 * it still pointed to selinux operations. If that is the case it's
877 * possible that it is about to use the avc and is about to need the
878 * avc_node_cachep. I know I could wrap the security.c security_ops call
879 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
880 * the cache and get that memory back.
881 */
882 if (avc_node_cachep) {
883 avc_flush();
884 /* kmem_cache_destroy(avc_node_cachep); */
885 }
Thomas Liu89c86572009-06-24 17:58:05 -0400886}