Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * Implementation of the kernel access vector cache (AVC). | |
3 | * | |
4 | * Authors: Stephen Smalley, <sds@epoch.ncsc.mil> | |
95fff33b | 5 | * James Morris <jmorris@redhat.com> |
1da177e4 LT |
6 | * |
7 | * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com> | |
95fff33b | 8 | * Replaced the avc_lock spinlock by RCU. |
1da177e4 LT |
9 | * |
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, | |
95fff33b | 14 | * as published by the Free Software Foundation. |
1da177e4 LT |
15 | */ |
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" | |
c6d3aaa4 | 34 | #include "classmap.h" |
5c458998 | 35 | |
1da177e4 LT |
36 | #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 | |
95fff33b | 41 | #define avc_cache_stats_incr(field) \ |
1da177e4 LT |
42 | do { \ |
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 | ||
50 | struct avc_entry { | |
51 | u32 ssid; | |
52 | u32 tsid; | |
53 | u16 tclass; | |
54 | struct av_decision avd; | |
1da177e4 LT |
55 | }; |
56 | ||
57 | struct avc_node { | |
58 | struct avc_entry ae; | |
26036651 | 59 | struct hlist_node list; /* anchored in avc_cache->slots[i] */ |
95fff33b | 60 | struct rcu_head rhead; |
1da177e4 LT |
61 | }; |
62 | ||
63 | struct avc_cache { | |
26036651 | 64 | struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */ |
1da177e4 LT |
65 | 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 | ||
71 | struct avc_callback_node { | |
72 | int (*callback) (u32 event, u32 ssid, u32 tsid, | |
95fff33b EP |
73 | u16 tclass, u32 perms, |
74 | u32 *out_retained); | |
1da177e4 LT |
75 | 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 */ | |
84 | unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD; | |
85 | ||
86 | #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS | |
87 | DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 }; | |
88 | #endif | |
89 | ||
90 | static struct avc_cache avc_cache; | |
91 | static struct avc_callback_node *avc_callbacks; | |
e18b890b | 92 | static struct kmem_cache *avc_node_cachep; |
1da177e4 LT |
93 | |
94 | static 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 | */ | |
44c2d9bd | 104 | static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) |
1da177e4 | 105 | { |
c6d3aaa4 SS |
106 | const char **perms; |
107 | int i, perm; | |
1da177e4 LT |
108 | |
109 | if (av == 0) { | |
110 | audit_log_format(ab, " null"); | |
111 | return; | |
112 | } | |
113 | ||
c6d3aaa4 | 114 | perms = secclass_map[tclass-1].perms; |
1da177e4 LT |
115 | |
116 | audit_log_format(ab, " {"); | |
117 | i = 0; | |
118 | perm = 1; | |
c6d3aaa4 | 119 | while (i < (sizeof(av) * 8)) { |
0bce9527 | 120 | if ((perm & av) && perms[i]) { |
c6d3aaa4 | 121 | audit_log_format(ab, " %s", perms[i]); |
1da177e4 LT |
122 | av &= ~perm; |
123 | } | |
124 | i++; | |
125 | perm <<= 1; | |
126 | } | |
127 | ||
1da177e4 LT |
128 | 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 | */ | |
140 | static 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 | ||
95fff33b | 146 | rc = security_sid_to_context(ssid, &scontext, &scontext_len); |
1da177e4 LT |
147 | 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 | } | |
a764ae4b | 161 | |
c6d3aaa4 SS |
162 | BUG_ON(tclass >= ARRAY_SIZE(secclass_map)); |
163 | audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name); | |
1da177e4 LT |
164 | } |
165 | ||
166 | /** | |
167 | * avc_init - Initialize the AVC. | |
168 | * | |
169 | * Initialize the access vector cache. | |
170 | */ | |
171 | void __init avc_init(void) | |
172 | { | |
173 | int i; | |
174 | ||
175 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { | |
26036651 | 176 | INIT_HLIST_HEAD(&avc_cache.slots[i]); |
1da177e4 LT |
177 | 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), | |
20c2df83 | 183 | 0, SLAB_PANIC, NULL); |
1da177e4 | 184 | |
9ad9ad38 | 185 | audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); |
1da177e4 LT |
186 | } |
187 | ||
188 | int avc_get_hash_stats(char *page) | |
189 | { | |
190 | int i, chain_len, max_chain_len, slots_used; | |
191 | struct avc_node *node; | |
26036651 | 192 | struct hlist_head *head; |
1da177e4 LT |
193 | |
194 | rcu_read_lock(); | |
195 | ||
196 | slots_used = 0; | |
197 | max_chain_len = 0; | |
198 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { | |
edf3d1ae | 199 | head = &avc_cache.slots[i]; |
26036651 EP |
200 | if (!hlist_empty(head)) { |
201 | struct hlist_node *next; | |
202 | ||
1da177e4 LT |
203 | slots_used++; |
204 | chain_len = 0; | |
26036651 | 205 | hlist_for_each_entry_rcu(node, next, head, list) |
1da177e4 LT |
206 | 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 | ||
220 | static 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 | ||
227 | static void avc_node_delete(struct avc_node *node) | |
228 | { | |
26036651 | 229 | hlist_del_rcu(&node->list); |
1da177e4 LT |
230 | call_rcu(&node->rhead, avc_node_free); |
231 | atomic_dec(&avc_cache.active_nodes); | |
232 | } | |
233 | ||
234 | static 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 | ||
241 | static void avc_node_replace(struct avc_node *new, struct avc_node *old) | |
242 | { | |
26036651 | 243 | hlist_replace_rcu(&old->list, &new->list); |
1da177e4 LT |
244 | call_rcu(&old->rhead, avc_node_free); |
245 | atomic_dec(&avc_cache.active_nodes); | |
246 | } | |
247 | ||
248 | static inline int avc_reclaim_node(void) | |
249 | { | |
250 | struct avc_node *node; | |
251 | int hvalue, try, ecx; | |
252 | unsigned long flags; | |
26036651 EP |
253 | struct hlist_head *head; |
254 | struct hlist_node *next; | |
edf3d1ae | 255 | spinlock_t *lock; |
1da177e4 | 256 | |
95fff33b | 257 | for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) { |
1da177e4 | 258 | hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); |
edf3d1ae EP |
259 | head = &avc_cache.slots[hvalue]; |
260 | lock = &avc_cache.slots_lock[hvalue]; | |
1da177e4 | 261 | |
edf3d1ae | 262 | if (!spin_trylock_irqsave(lock, flags)) |
1da177e4 LT |
263 | continue; |
264 | ||
61844250 | 265 | rcu_read_lock(); |
26036651 | 266 | hlist_for_each_entry(node, next, head, list) { |
906d27d9 EP |
267 | avc_node_delete(node); |
268 | avc_cache_stats_incr(reclaims); | |
269 | ecx++; | |
270 | if (ecx >= AVC_CACHE_RECLAIM) { | |
271 | rcu_read_unlock(); | |
edf3d1ae | 272 | spin_unlock_irqrestore(lock, flags); |
906d27d9 | 273 | goto out; |
1da177e4 LT |
274 | } |
275 | } | |
61844250 | 276 | rcu_read_unlock(); |
edf3d1ae | 277 | spin_unlock_irqrestore(lock, flags); |
1da177e4 LT |
278 | } |
279 | out: | |
280 | return ecx; | |
281 | } | |
282 | ||
283 | static struct avc_node *avc_alloc_node(void) | |
284 | { | |
285 | struct avc_node *node; | |
286 | ||
c3762229 | 287 | node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC); |
1da177e4 LT |
288 | if (!node) |
289 | goto out; | |
290 | ||
26036651 | 291 | INIT_HLIST_NODE(&node->list); |
1da177e4 LT |
292 | avc_cache_stats_incr(allocations); |
293 | ||
294 | if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) | |
295 | avc_reclaim_node(); | |
296 | ||
297 | out: | |
298 | return node; | |
299 | } | |
300 | ||
21193dcd | 301 | static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) |
1da177e4 LT |
302 | { |
303 | node->ae.ssid = ssid; | |
304 | node->ae.tsid = tsid; | |
305 | node->ae.tclass = tclass; | |
21193dcd | 306 | memcpy(&node->ae.avd, avd, sizeof(node->ae.avd)); |
1da177e4 LT |
307 | } |
308 | ||
309 | static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) | |
310 | { | |
311 | struct avc_node *node, *ret = NULL; | |
312 | int hvalue; | |
26036651 EP |
313 | struct hlist_head *head; |
314 | struct hlist_node *next; | |
1da177e4 LT |
315 | |
316 | hvalue = avc_hash(ssid, tsid, tclass); | |
edf3d1ae | 317 | head = &avc_cache.slots[hvalue]; |
26036651 | 318 | hlist_for_each_entry_rcu(node, next, head, list) { |
1da177e4 LT |
319 | if (ssid == node->ae.ssid && |
320 | tclass == node->ae.tclass && | |
321 | tsid == node->ae.tsid) { | |
322 | ret = node; | |
323 | break; | |
324 | } | |
325 | } | |
326 | ||
1da177e4 LT |
327 | 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 | |
1da177e4 LT |
335 | * |
336 | * Look up an AVC entry that is valid for the | |
1da177e4 LT |
337 | * (@ssid, @tsid), interpreting the permissions |
338 | * based on @tclass. If a valid AVC entry exists, | |
6382dc33 | 339 | * then this function returns the avc_node. |
1da177e4 LT |
340 | * Otherwise, this function returns NULL. |
341 | */ | |
f1c6381a | 342 | static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass) |
1da177e4 LT |
343 | { |
344 | struct avc_node *node; | |
345 | ||
346 | avc_cache_stats_incr(lookups); | |
347 | node = avc_search_node(ssid, tsid, tclass); | |
348 | ||
f1c6381a | 349 | if (node) |
1da177e4 | 350 | avc_cache_stats_incr(hits); |
f1c6381a EP |
351 | else |
352 | avc_cache_stats_incr(misses); | |
1da177e4 | 353 | |
1da177e4 LT |
354 | return node; |
355 | } | |
356 | ||
357 | static 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(¬if_lock, flag); | |
364 | if (is_insert) { | |
365 | if (seqno < avc_cache.latest_notif) { | |
744ba35e | 366 | printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n", |
1da177e4 LT |
367 | 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(¬if_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 | |
21193dcd | 384 | * @avd: resulting av decision |
1da177e4 LT |
385 | * |
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 | |
21193dcd | 391 | * sequence number @avd->seqno is not less than the latest |
1da177e4 LT |
392 | * 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 | */ | |
21193dcd | 396 | static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) |
1da177e4 LT |
397 | { |
398 | struct avc_node *pos, *node = NULL; | |
399 | int hvalue; | |
400 | unsigned long flag; | |
401 | ||
21193dcd | 402 | if (avc_latest_notif_update(avd->seqno, 1)) |
1da177e4 LT |
403 | goto out; |
404 | ||
405 | node = avc_alloc_node(); | |
406 | if (node) { | |
26036651 EP |
407 | struct hlist_head *head; |
408 | struct hlist_node *next; | |
edf3d1ae EP |
409 | spinlock_t *lock; |
410 | ||
1da177e4 | 411 | hvalue = avc_hash(ssid, tsid, tclass); |
21193dcd | 412 | avc_node_populate(node, ssid, tsid, tclass, avd); |
1da177e4 | 413 | |
edf3d1ae EP |
414 | head = &avc_cache.slots[hvalue]; |
415 | lock = &avc_cache.slots_lock[hvalue]; | |
416 | ||
417 | spin_lock_irqsave(lock, flag); | |
26036651 | 418 | hlist_for_each_entry(pos, next, head, list) { |
1da177e4 LT |
419 | if (pos->ae.ssid == ssid && |
420 | pos->ae.tsid == tsid && | |
421 | pos->ae.tclass == tclass) { | |
95fff33b | 422 | avc_node_replace(node, pos); |
1da177e4 LT |
423 | goto found; |
424 | } | |
425 | } | |
26036651 | 426 | hlist_add_head_rcu(&node->list, head); |
1da177e4 | 427 | found: |
edf3d1ae | 428 | spin_unlock_irqrestore(lock, flag); |
1da177e4 LT |
429 | } |
430 | out: | |
431 | return node; | |
432 | } | |
433 | ||
2bf49690 TL |
434 | /** |
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 | */ | |
440 | static void avc_audit_pre_callback(struct audit_buffer *ab, void *a) | |
1da177e4 | 441 | { |
2bf49690 TL |
442 | 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 "); | |
1da177e4 LT |
448 | } |
449 | ||
2bf49690 TL |
450 | /** |
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 | */ | |
456 | static void avc_audit_post_callback(struct audit_buffer *ab, void *a) | |
1da177e4 | 457 | { |
2bf49690 TL |
458 | 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); | |
1da177e4 LT |
463 | } |
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 | */ | |
484 | void avc_audit(u32 ssid, u32 tsid, | |
95fff33b | 485 | u16 tclass, u32 requested, |
2bf49690 | 486 | struct av_decision *avd, int result, struct common_audit_data *a) |
1da177e4 | 487 | { |
2bf49690 | 488 | struct common_audit_data stack_data; |
be940d62 | 489 | u32 denied, audited; |
be940d62 | 490 | denied = requested & ~avd->allowed; |
b782e0a6 | 491 | if (denied) { |
b6cac5a3 | 492 | audited = denied & avd->auditdeny; |
b782e0a6 EP |
493 | /* |
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) | |
be940d62 | 514 | audited = denied = requested; |
b6cac5a3 SS |
515 | else |
516 | audited = requested & avd->auditallow; | |
517 | if (!audited) | |
518 | return; | |
2bf49690 TL |
519 | if (!a) { |
520 | a = &stack_data; | |
cb84aa9b | 521 | COMMON_AUDIT_DATA_INIT(a, NONE); |
be940d62 | 522 | } |
2bf49690 TL |
523 | 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); | |
1da177e4 LT |
532 | } |
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 | |
6382dc33 | 544 | * related to the SID pair (@ssid, @tsid) |
1da177e4 LT |
545 | * 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 | */ | |
549 | int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid, | |
95fff33b EP |
550 | u16 tclass, u32 perms, |
551 | u32 *out_retained), | |
552 | u32 events, u32 ssid, u32 tsid, | |
553 | u16 tclass, u32 perms) | |
1da177e4 LT |
554 | { |
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; | |
571 | out: | |
572 | return rc; | |
573 | } | |
574 | ||
575 | static 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 | |
a5dda683 | 585 | * @seqno : sequence number when decision was made |
1da177e4 LT |
586 | * |
587 | * if a valid AVC entry doesn't exist,this function returns -ENOENT. | |
588 | * if kmalloc() called internal returns NULL, this function returns -ENOMEM. | |
6382dc33 | 589 | * otherwise, this function updates the AVC entry. The original AVC-entry object |
1da177e4 LT |
590 | * will release later by RCU. |
591 | */ | |
a5dda683 EP |
592 | static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass, |
593 | u32 seqno) | |
1da177e4 LT |
594 | { |
595 | int hvalue, rc = 0; | |
596 | unsigned long flag; | |
597 | struct avc_node *pos, *node, *orig = NULL; | |
26036651 EP |
598 | struct hlist_head *head; |
599 | struct hlist_node *next; | |
edf3d1ae | 600 | spinlock_t *lock; |
1da177e4 LT |
601 | |
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); | |
1da177e4 | 610 | |
edf3d1ae EP |
611 | head = &avc_cache.slots[hvalue]; |
612 | lock = &avc_cache.slots_lock[hvalue]; | |
613 | ||
614 | spin_lock_irqsave(lock, flag); | |
615 | ||
26036651 | 616 | hlist_for_each_entry(pos, next, head, list) { |
95fff33b EP |
617 | if (ssid == pos->ae.ssid && |
618 | tsid == pos->ae.tsid && | |
a5dda683 EP |
619 | tclass == pos->ae.tclass && |
620 | seqno == pos->ae.avd.seqno){ | |
1da177e4 LT |
621 | 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 | ||
21193dcd | 636 | avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd); |
1da177e4 LT |
637 | |
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); | |
660 | out_unlock: | |
edf3d1ae | 661 | spin_unlock_irqrestore(lock, flag); |
1da177e4 LT |
662 | out: |
663 | return rc; | |
664 | } | |
665 | ||
666 | /** | |
008574b1 | 667 | * avc_flush - Flush the cache |
1da177e4 | 668 | */ |
008574b1 | 669 | static void avc_flush(void) |
1da177e4 | 670 | { |
26036651 EP |
671 | struct hlist_head *head; |
672 | struct hlist_node *next; | |
008574b1 | 673 | struct avc_node *node; |
edf3d1ae | 674 | spinlock_t *lock; |
008574b1 EP |
675 | unsigned long flag; |
676 | int i; | |
1da177e4 LT |
677 | |
678 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { | |
edf3d1ae EP |
679 | head = &avc_cache.slots[i]; |
680 | lock = &avc_cache.slots_lock[i]; | |
681 | ||
682 | spin_lock_irqsave(lock, flag); | |
61844250 PM |
683 | /* |
684 | * With preemptable RCU, the outer spinlock does not | |
685 | * prevent RCU grace periods from ending. | |
686 | */ | |
687 | rcu_read_lock(); | |
26036651 | 688 | hlist_for_each_entry(node, next, head, list) |
1da177e4 | 689 | avc_node_delete(node); |
61844250 | 690 | rcu_read_unlock(); |
edf3d1ae | 691 | spin_unlock_irqrestore(lock, flag); |
1da177e4 | 692 | } |
008574b1 EP |
693 | } |
694 | ||
695 | /** | |
696 | * avc_ss_reset - Flush the cache and revalidate migrated permissions. | |
697 | * @seqno: policy sequence number | |
698 | */ | |
699 | int avc_ss_reset(u32 seqno) | |
700 | { | |
701 | struct avc_callback_node *c; | |
702 | int rc = 0, tmprc; | |
703 | ||
704 | avc_flush(); | |
1da177e4 LT |
705 | |
706 | for (c = avc_callbacks; c; c = c->next) { | |
707 | if (c->events & AVC_CALLBACK_RESET) { | |
376bd9cb | 708 | tmprc = c->callback(AVC_CALLBACK_RESET, |
95fff33b | 709 | 0, 0, 0, 0, NULL); |
376bd9cb DG |
710 | /* save the first error encountered for the return |
711 | value and continue processing the callbacks */ | |
712 | if (!rc) | |
713 | rc = tmprc; | |
1da177e4 LT |
714 | } |
715 | } | |
716 | ||
717 | avc_latest_notif_update(seqno, 0); | |
1da177e4 LT |
718 | 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 | |
2c3c05db | 727 | * @flags: AVC_STRICT or 0 |
1da177e4 LT |
728 | * @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 | */ | |
741 | int avc_has_perm_noaudit(u32 ssid, u32 tsid, | |
2c3c05db SS |
742 | u16 tclass, u32 requested, |
743 | unsigned flags, | |
21193dcd | 744 | struct av_decision *in_avd) |
1da177e4 LT |
745 | { |
746 | struct avc_node *node; | |
21193dcd | 747 | struct av_decision avd_entry, *avd; |
1da177e4 LT |
748 | int rc = 0; |
749 | u32 denied; | |
750 | ||
eda4f69c EP |
751 | BUG_ON(!requested); |
752 | ||
1da177e4 LT |
753 | rcu_read_lock(); |
754 | ||
f1c6381a | 755 | node = avc_lookup(ssid, tsid, tclass); |
1da177e4 LT |
756 | if (!node) { |
757 | rcu_read_unlock(); | |
21193dcd EP |
758 | |
759 | if (in_avd) | |
760 | avd = in_avd; | |
761 | else | |
762 | avd = &avd_entry; | |
763 | ||
19439d05 | 764 | security_compute_av(ssid, tsid, tclass, avd); |
1da177e4 | 765 | rcu_read_lock(); |
21193dcd EP |
766 | 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; | |
1da177e4 LT |
771 | } |
772 | ||
21193dcd | 773 | denied = requested & ~(avd->allowed); |
1da177e4 | 774 | |
eda4f69c | 775 | if (denied) { |
64dbf074 | 776 | if (flags & AVC_STRICT) |
1da177e4 | 777 | rc = -EACCES; |
8a6f83af | 778 | else if (!selinux_enforcing || (avd->flags & AVD_FLAGS_PERMISSIVE)) |
64dbf074 | 779 | avc_update_node(AVC_CALLBACK_GRANT, requested, ssid, |
21193dcd | 780 | tsid, tclass, avd->seqno); |
1da177e4 | 781 | else |
64dbf074 | 782 | rc = -EACCES; |
1da177e4 LT |
783 | } |
784 | ||
785 | rcu_read_unlock(); | |
1da177e4 LT |
786 | 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 | */ | |
805 | int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, | |
2bf49690 | 806 | u32 requested, struct common_audit_data *auditdata) |
1da177e4 LT |
807 | { |
808 | struct av_decision avd; | |
809 | int rc; | |
810 | ||
2c3c05db | 811 | rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); |
1da177e4 LT |
812 | avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); |
813 | return rc; | |
814 | } | |
788e7dd4 YN |
815 | |
816 | u32 avc_policy_seqno(void) | |
817 | { | |
818 | return avc_cache.latest_notif; | |
819 | } | |
89c86576 TL |
820 | |
821 | void avc_disable(void) | |
822 | { | |
5224ee08 EP |
823 | /* |
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 | } | |
89c86576 | 838 | } |