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 | |
044aea9b | 41 | #define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field) |
1da177e4 LT |
42 | #else |
43 | #define avc_cache_stats_incr(field) do {} while (0) | |
44 | #endif | |
45 | ||
46 | struct avc_entry { | |
47 | u32 ssid; | |
48 | u32 tsid; | |
49 | u16 tclass; | |
50 | struct av_decision avd; | |
1da177e4 LT |
51 | }; |
52 | ||
53 | struct avc_node { | |
54 | struct avc_entry ae; | |
26036651 | 55 | struct hlist_node list; /* anchored in avc_cache->slots[i] */ |
95fff33b | 56 | struct rcu_head rhead; |
1da177e4 LT |
57 | }; |
58 | ||
59 | struct avc_cache { | |
26036651 | 60 | struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */ |
1da177e4 LT |
61 | 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 | ||
67 | struct avc_callback_node { | |
562c99f2 | 68 | int (*callback) (u32 event); |
1da177e4 | 69 | u32 events; |
1da177e4 LT |
70 | struct avc_callback_node *next; |
71 | }; | |
72 | ||
73 | /* Exported via selinufs */ | |
74 | unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD; | |
75 | ||
76 | #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS | |
77 | DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 }; | |
78 | #endif | |
79 | ||
80 | static struct avc_cache avc_cache; | |
81 | static struct avc_callback_node *avc_callbacks; | |
e18b890b | 82 | static struct kmem_cache *avc_node_cachep; |
1da177e4 LT |
83 | |
84 | static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass) | |
85 | { | |
86 | return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1); | |
87 | } | |
88 | ||
89 | /** | |
90 | * avc_dump_av - Display an access vector in human-readable form. | |
91 | * @tclass: target security class | |
92 | * @av: access vector | |
93 | */ | |
44c2d9bd | 94 | static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av) |
1da177e4 | 95 | { |
c6d3aaa4 SS |
96 | const char **perms; |
97 | int i, perm; | |
1da177e4 LT |
98 | |
99 | if (av == 0) { | |
100 | audit_log_format(ab, " null"); | |
101 | return; | |
102 | } | |
103 | ||
c6d3aaa4 | 104 | perms = secclass_map[tclass-1].perms; |
1da177e4 LT |
105 | |
106 | audit_log_format(ab, " {"); | |
107 | i = 0; | |
108 | perm = 1; | |
c6d3aaa4 | 109 | while (i < (sizeof(av) * 8)) { |
0bce9527 | 110 | if ((perm & av) && perms[i]) { |
c6d3aaa4 | 111 | audit_log_format(ab, " %s", perms[i]); |
1da177e4 LT |
112 | av &= ~perm; |
113 | } | |
114 | i++; | |
115 | perm <<= 1; | |
116 | } | |
117 | ||
1da177e4 LT |
118 | if (av) |
119 | audit_log_format(ab, " 0x%x", av); | |
120 | ||
121 | audit_log_format(ab, " }"); | |
122 | } | |
123 | ||
124 | /** | |
125 | * avc_dump_query - Display a SID pair and a class in human-readable form. | |
126 | * @ssid: source security identifier | |
127 | * @tsid: target security identifier | |
128 | * @tclass: target security class | |
129 | */ | |
130 | static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass) | |
131 | { | |
132 | int rc; | |
133 | char *scontext; | |
134 | u32 scontext_len; | |
135 | ||
95fff33b | 136 | rc = security_sid_to_context(ssid, &scontext, &scontext_len); |
1da177e4 LT |
137 | if (rc) |
138 | audit_log_format(ab, "ssid=%d", ssid); | |
139 | else { | |
140 | audit_log_format(ab, "scontext=%s", scontext); | |
141 | kfree(scontext); | |
142 | } | |
143 | ||
144 | rc = security_sid_to_context(tsid, &scontext, &scontext_len); | |
145 | if (rc) | |
146 | audit_log_format(ab, " tsid=%d", tsid); | |
147 | else { | |
148 | audit_log_format(ab, " tcontext=%s", scontext); | |
149 | kfree(scontext); | |
150 | } | |
a764ae4b | 151 | |
c6d3aaa4 SS |
152 | BUG_ON(tclass >= ARRAY_SIZE(secclass_map)); |
153 | audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name); | |
1da177e4 LT |
154 | } |
155 | ||
156 | /** | |
157 | * avc_init - Initialize the AVC. | |
158 | * | |
159 | * Initialize the access vector cache. | |
160 | */ | |
161 | void __init avc_init(void) | |
162 | { | |
163 | int i; | |
164 | ||
165 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { | |
26036651 | 166 | INIT_HLIST_HEAD(&avc_cache.slots[i]); |
1da177e4 LT |
167 | spin_lock_init(&avc_cache.slots_lock[i]); |
168 | } | |
169 | atomic_set(&avc_cache.active_nodes, 0); | |
170 | atomic_set(&avc_cache.lru_hint, 0); | |
171 | ||
172 | avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node), | |
20c2df83 | 173 | 0, SLAB_PANIC, NULL); |
1da177e4 | 174 | |
9ad9ad38 | 175 | audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n"); |
1da177e4 LT |
176 | } |
177 | ||
178 | int avc_get_hash_stats(char *page) | |
179 | { | |
180 | int i, chain_len, max_chain_len, slots_used; | |
181 | struct avc_node *node; | |
26036651 | 182 | struct hlist_head *head; |
1da177e4 LT |
183 | |
184 | rcu_read_lock(); | |
185 | ||
186 | slots_used = 0; | |
187 | max_chain_len = 0; | |
188 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { | |
edf3d1ae | 189 | head = &avc_cache.slots[i]; |
26036651 | 190 | if (!hlist_empty(head)) { |
1da177e4 LT |
191 | slots_used++; |
192 | chain_len = 0; | |
b67bfe0d | 193 | hlist_for_each_entry_rcu(node, head, list) |
1da177e4 LT |
194 | chain_len++; |
195 | if (chain_len > max_chain_len) | |
196 | max_chain_len = chain_len; | |
197 | } | |
198 | } | |
199 | ||
200 | rcu_read_unlock(); | |
201 | ||
202 | return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n" | |
203 | "longest chain: %d\n", | |
204 | atomic_read(&avc_cache.active_nodes), | |
205 | slots_used, AVC_CACHE_SLOTS, max_chain_len); | |
206 | } | |
207 | ||
208 | static void avc_node_free(struct rcu_head *rhead) | |
209 | { | |
210 | struct avc_node *node = container_of(rhead, struct avc_node, rhead); | |
211 | kmem_cache_free(avc_node_cachep, node); | |
212 | avc_cache_stats_incr(frees); | |
213 | } | |
214 | ||
215 | static void avc_node_delete(struct avc_node *node) | |
216 | { | |
26036651 | 217 | hlist_del_rcu(&node->list); |
1da177e4 LT |
218 | call_rcu(&node->rhead, avc_node_free); |
219 | atomic_dec(&avc_cache.active_nodes); | |
220 | } | |
221 | ||
222 | static void avc_node_kill(struct avc_node *node) | |
223 | { | |
224 | kmem_cache_free(avc_node_cachep, node); | |
225 | avc_cache_stats_incr(frees); | |
226 | atomic_dec(&avc_cache.active_nodes); | |
227 | } | |
228 | ||
229 | static void avc_node_replace(struct avc_node *new, struct avc_node *old) | |
230 | { | |
26036651 | 231 | hlist_replace_rcu(&old->list, &new->list); |
1da177e4 LT |
232 | call_rcu(&old->rhead, avc_node_free); |
233 | atomic_dec(&avc_cache.active_nodes); | |
234 | } | |
235 | ||
236 | static inline int avc_reclaim_node(void) | |
237 | { | |
238 | struct avc_node *node; | |
239 | int hvalue, try, ecx; | |
240 | unsigned long flags; | |
26036651 | 241 | struct hlist_head *head; |
edf3d1ae | 242 | spinlock_t *lock; |
1da177e4 | 243 | |
95fff33b | 244 | for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) { |
1da177e4 | 245 | hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1); |
edf3d1ae EP |
246 | head = &avc_cache.slots[hvalue]; |
247 | lock = &avc_cache.slots_lock[hvalue]; | |
1da177e4 | 248 | |
edf3d1ae | 249 | if (!spin_trylock_irqsave(lock, flags)) |
1da177e4 LT |
250 | continue; |
251 | ||
61844250 | 252 | rcu_read_lock(); |
b67bfe0d | 253 | hlist_for_each_entry(node, head, list) { |
906d27d9 EP |
254 | avc_node_delete(node); |
255 | avc_cache_stats_incr(reclaims); | |
256 | ecx++; | |
257 | if (ecx >= AVC_CACHE_RECLAIM) { | |
258 | rcu_read_unlock(); | |
edf3d1ae | 259 | spin_unlock_irqrestore(lock, flags); |
906d27d9 | 260 | goto out; |
1da177e4 LT |
261 | } |
262 | } | |
61844250 | 263 | rcu_read_unlock(); |
edf3d1ae | 264 | spin_unlock_irqrestore(lock, flags); |
1da177e4 LT |
265 | } |
266 | out: | |
267 | return ecx; | |
268 | } | |
269 | ||
270 | static struct avc_node *avc_alloc_node(void) | |
271 | { | |
272 | struct avc_node *node; | |
273 | ||
6290c2c4 | 274 | node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC|__GFP_NOMEMALLOC); |
1da177e4 LT |
275 | if (!node) |
276 | goto out; | |
277 | ||
26036651 | 278 | INIT_HLIST_NODE(&node->list); |
1da177e4 LT |
279 | avc_cache_stats_incr(allocations); |
280 | ||
281 | if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold) | |
282 | avc_reclaim_node(); | |
283 | ||
284 | out: | |
285 | return node; | |
286 | } | |
287 | ||
21193dcd | 288 | static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) |
1da177e4 LT |
289 | { |
290 | node->ae.ssid = ssid; | |
291 | node->ae.tsid = tsid; | |
292 | node->ae.tclass = tclass; | |
21193dcd | 293 | memcpy(&node->ae.avd, avd, sizeof(node->ae.avd)); |
1da177e4 LT |
294 | } |
295 | ||
296 | static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass) | |
297 | { | |
298 | struct avc_node *node, *ret = NULL; | |
299 | int hvalue; | |
26036651 | 300 | struct hlist_head *head; |
1da177e4 LT |
301 | |
302 | hvalue = avc_hash(ssid, tsid, tclass); | |
edf3d1ae | 303 | head = &avc_cache.slots[hvalue]; |
b67bfe0d | 304 | hlist_for_each_entry_rcu(node, head, list) { |
1da177e4 LT |
305 | if (ssid == node->ae.ssid && |
306 | tclass == node->ae.tclass && | |
307 | tsid == node->ae.tsid) { | |
308 | ret = node; | |
309 | break; | |
310 | } | |
311 | } | |
312 | ||
1da177e4 LT |
313 | return ret; |
314 | } | |
315 | ||
316 | /** | |
317 | * avc_lookup - Look up an AVC entry. | |
318 | * @ssid: source security identifier | |
319 | * @tsid: target security identifier | |
320 | * @tclass: target security class | |
1da177e4 LT |
321 | * |
322 | * Look up an AVC entry that is valid for the | |
1da177e4 LT |
323 | * (@ssid, @tsid), interpreting the permissions |
324 | * based on @tclass. If a valid AVC entry exists, | |
6382dc33 | 325 | * then this function returns the avc_node. |
1da177e4 LT |
326 | * Otherwise, this function returns NULL. |
327 | */ | |
f1c6381a | 328 | static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass) |
1da177e4 LT |
329 | { |
330 | struct avc_node *node; | |
331 | ||
332 | avc_cache_stats_incr(lookups); | |
333 | node = avc_search_node(ssid, tsid, tclass); | |
334 | ||
f1c6381a | 335 | if (node) |
257313b2 | 336 | return node; |
1da177e4 | 337 | |
257313b2 LT |
338 | avc_cache_stats_incr(misses); |
339 | return NULL; | |
1da177e4 LT |
340 | } |
341 | ||
342 | static int avc_latest_notif_update(int seqno, int is_insert) | |
343 | { | |
344 | int ret = 0; | |
345 | static DEFINE_SPINLOCK(notif_lock); | |
346 | unsigned long flag; | |
347 | ||
348 | spin_lock_irqsave(¬if_lock, flag); | |
349 | if (is_insert) { | |
350 | if (seqno < avc_cache.latest_notif) { | |
744ba35e | 351 | printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n", |
1da177e4 LT |
352 | seqno, avc_cache.latest_notif); |
353 | ret = -EAGAIN; | |
354 | } | |
355 | } else { | |
356 | if (seqno > avc_cache.latest_notif) | |
357 | avc_cache.latest_notif = seqno; | |
358 | } | |
359 | spin_unlock_irqrestore(¬if_lock, flag); | |
360 | ||
361 | return ret; | |
362 | } | |
363 | ||
364 | /** | |
365 | * avc_insert - Insert an AVC entry. | |
366 | * @ssid: source security identifier | |
367 | * @tsid: target security identifier | |
368 | * @tclass: target security class | |
21193dcd | 369 | * @avd: resulting av decision |
1da177e4 LT |
370 | * |
371 | * Insert an AVC entry for the SID pair | |
372 | * (@ssid, @tsid) and class @tclass. | |
373 | * The access vectors and the sequence number are | |
374 | * normally provided by the security server in | |
375 | * response to a security_compute_av() call. If the | |
21193dcd | 376 | * sequence number @avd->seqno is not less than the latest |
1da177e4 LT |
377 | * revocation notification, then the function copies |
378 | * the access vectors into a cache entry, returns | |
379 | * avc_node inserted. Otherwise, this function returns NULL. | |
380 | */ | |
21193dcd | 381 | static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd) |
1da177e4 LT |
382 | { |
383 | struct avc_node *pos, *node = NULL; | |
384 | int hvalue; | |
385 | unsigned long flag; | |
386 | ||
21193dcd | 387 | if (avc_latest_notif_update(avd->seqno, 1)) |
1da177e4 LT |
388 | goto out; |
389 | ||
390 | node = avc_alloc_node(); | |
391 | if (node) { | |
26036651 | 392 | struct hlist_head *head; |
edf3d1ae EP |
393 | spinlock_t *lock; |
394 | ||
1da177e4 | 395 | hvalue = avc_hash(ssid, tsid, tclass); |
21193dcd | 396 | avc_node_populate(node, ssid, tsid, tclass, avd); |
1da177e4 | 397 | |
edf3d1ae EP |
398 | head = &avc_cache.slots[hvalue]; |
399 | lock = &avc_cache.slots_lock[hvalue]; | |
400 | ||
401 | spin_lock_irqsave(lock, flag); | |
b67bfe0d | 402 | hlist_for_each_entry(pos, head, list) { |
1da177e4 LT |
403 | if (pos->ae.ssid == ssid && |
404 | pos->ae.tsid == tsid && | |
405 | pos->ae.tclass == tclass) { | |
95fff33b | 406 | avc_node_replace(node, pos); |
1da177e4 LT |
407 | goto found; |
408 | } | |
409 | } | |
26036651 | 410 | hlist_add_head_rcu(&node->list, head); |
1da177e4 | 411 | found: |
edf3d1ae | 412 | spin_unlock_irqrestore(lock, flag); |
1da177e4 LT |
413 | } |
414 | out: | |
415 | return node; | |
416 | } | |
417 | ||
2bf49690 TL |
418 | /** |
419 | * avc_audit_pre_callback - SELinux specific information | |
420 | * will be called by generic audit code | |
421 | * @ab: the audit buffer | |
422 | * @a: audit_data | |
423 | */ | |
424 | static void avc_audit_pre_callback(struct audit_buffer *ab, void *a) | |
1da177e4 | 425 | { |
2bf49690 TL |
426 | struct common_audit_data *ad = a; |
427 | audit_log_format(ab, "avc: %s ", | |
899838b2 EP |
428 | ad->selinux_audit_data->denied ? "denied" : "granted"); |
429 | avc_dump_av(ab, ad->selinux_audit_data->tclass, | |
430 | ad->selinux_audit_data->audited); | |
2bf49690 | 431 | audit_log_format(ab, " for "); |
1da177e4 LT |
432 | } |
433 | ||
2bf49690 TL |
434 | /** |
435 | * avc_audit_post_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_post_callback(struct audit_buffer *ab, void *a) | |
1da177e4 | 441 | { |
2bf49690 TL |
442 | struct common_audit_data *ad = a; |
443 | audit_log_format(ab, " "); | |
899838b2 EP |
444 | avc_dump_query(ab, ad->selinux_audit_data->ssid, |
445 | ad->selinux_audit_data->tsid, | |
446 | ad->selinux_audit_data->tclass); | |
1da177e4 LT |
447 | } |
448 | ||
48aab2f7 | 449 | /* This is the slow part of avc audit with big stack footprint */ |
2e334057 | 450 | noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass, |
48aab2f7 | 451 | u32 requested, u32 audited, u32 denied, |
f8294f11 | 452 | struct common_audit_data *a, |
48aab2f7 LT |
453 | unsigned flags) |
454 | { | |
455 | struct common_audit_data stack_data; | |
899838b2 | 456 | struct selinux_audit_data sad; |
48aab2f7 LT |
457 | |
458 | if (!a) { | |
459 | a = &stack_data; | |
50c205f5 | 460 | a->type = LSM_AUDIT_DATA_NONE; |
48aab2f7 LT |
461 | } |
462 | ||
463 | /* | |
464 | * When in a RCU walk do the audit on the RCU retry. This is because | |
465 | * the collection of the dname in an inode audit message is not RCU | |
466 | * safe. Note this may drop some audits when the situation changes | |
467 | * during retry. However this is logically just as if the operation | |
468 | * happened a little later. | |
469 | */ | |
470 | if ((a->type == LSM_AUDIT_DATA_INODE) && | |
471 | (flags & MAY_NOT_BLOCK)) | |
472 | return -ECHILD; | |
473 | ||
899838b2 EP |
474 | sad.tclass = tclass; |
475 | sad.requested = requested; | |
476 | sad.ssid = ssid; | |
477 | sad.tsid = tsid; | |
478 | sad.audited = audited; | |
479 | sad.denied = denied; | |
480 | ||
481 | a->selinux_audit_data = &sad; | |
3f0882c4 | 482 | |
b61c37f5 | 483 | common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback); |
48aab2f7 LT |
484 | return 0; |
485 | } | |
486 | ||
1da177e4 LT |
487 | /** |
488 | * avc_add_callback - Register a callback for security events. | |
489 | * @callback: callback function | |
490 | * @events: security events | |
1da177e4 | 491 | * |
562c99f2 WG |
492 | * Register a callback function for events in the set @events. |
493 | * Returns %0 on success or -%ENOMEM if insufficient memory | |
494 | * exists to add the callback. | |
1da177e4 | 495 | */ |
562c99f2 | 496 | int __init avc_add_callback(int (*callback)(u32 event), u32 events) |
1da177e4 LT |
497 | { |
498 | struct avc_callback_node *c; | |
499 | int rc = 0; | |
500 | ||
0b36e44c | 501 | c = kmalloc(sizeof(*c), GFP_KERNEL); |
1da177e4 LT |
502 | if (!c) { |
503 | rc = -ENOMEM; | |
504 | goto out; | |
505 | } | |
506 | ||
507 | c->callback = callback; | |
508 | c->events = events; | |
1da177e4 LT |
509 | c->next = avc_callbacks; |
510 | avc_callbacks = c; | |
511 | out: | |
512 | return rc; | |
513 | } | |
514 | ||
515 | static inline int avc_sidcmp(u32 x, u32 y) | |
516 | { | |
517 | return (x == y || x == SECSID_WILD || y == SECSID_WILD); | |
518 | } | |
519 | ||
520 | /** | |
521 | * avc_update_node Update an AVC entry | |
522 | * @event : Updating event | |
523 | * @perms : Permission mask bits | |
524 | * @ssid,@tsid,@tclass : identifier of an AVC entry | |
a5dda683 | 525 | * @seqno : sequence number when decision was made |
1da177e4 LT |
526 | * |
527 | * if a valid AVC entry doesn't exist,this function returns -ENOENT. | |
528 | * if kmalloc() called internal returns NULL, this function returns -ENOMEM. | |
6382dc33 | 529 | * otherwise, this function updates the AVC entry. The original AVC-entry object |
1da177e4 LT |
530 | * will release later by RCU. |
531 | */ | |
a5dda683 EP |
532 | static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass, |
533 | u32 seqno) | |
1da177e4 LT |
534 | { |
535 | int hvalue, rc = 0; | |
536 | unsigned long flag; | |
537 | struct avc_node *pos, *node, *orig = NULL; | |
26036651 | 538 | struct hlist_head *head; |
edf3d1ae | 539 | spinlock_t *lock; |
1da177e4 LT |
540 | |
541 | node = avc_alloc_node(); | |
542 | if (!node) { | |
543 | rc = -ENOMEM; | |
544 | goto out; | |
545 | } | |
546 | ||
547 | /* Lock the target slot */ | |
548 | hvalue = avc_hash(ssid, tsid, tclass); | |
1da177e4 | 549 | |
edf3d1ae EP |
550 | head = &avc_cache.slots[hvalue]; |
551 | lock = &avc_cache.slots_lock[hvalue]; | |
552 | ||
553 | spin_lock_irqsave(lock, flag); | |
554 | ||
b67bfe0d | 555 | hlist_for_each_entry(pos, head, list) { |
95fff33b EP |
556 | if (ssid == pos->ae.ssid && |
557 | tsid == pos->ae.tsid && | |
a5dda683 EP |
558 | tclass == pos->ae.tclass && |
559 | seqno == pos->ae.avd.seqno){ | |
1da177e4 LT |
560 | orig = pos; |
561 | break; | |
562 | } | |
563 | } | |
564 | ||
565 | if (!orig) { | |
566 | rc = -ENOENT; | |
567 | avc_node_kill(node); | |
568 | goto out_unlock; | |
569 | } | |
570 | ||
571 | /* | |
572 | * Copy and replace original node. | |
573 | */ | |
574 | ||
21193dcd | 575 | avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd); |
1da177e4 LT |
576 | |
577 | switch (event) { | |
578 | case AVC_CALLBACK_GRANT: | |
579 | node->ae.avd.allowed |= perms; | |
580 | break; | |
581 | case AVC_CALLBACK_TRY_REVOKE: | |
582 | case AVC_CALLBACK_REVOKE: | |
583 | node->ae.avd.allowed &= ~perms; | |
584 | break; | |
585 | case AVC_CALLBACK_AUDITALLOW_ENABLE: | |
586 | node->ae.avd.auditallow |= perms; | |
587 | break; | |
588 | case AVC_CALLBACK_AUDITALLOW_DISABLE: | |
589 | node->ae.avd.auditallow &= ~perms; | |
590 | break; | |
591 | case AVC_CALLBACK_AUDITDENY_ENABLE: | |
592 | node->ae.avd.auditdeny |= perms; | |
593 | break; | |
594 | case AVC_CALLBACK_AUDITDENY_DISABLE: | |
595 | node->ae.avd.auditdeny &= ~perms; | |
596 | break; | |
597 | } | |
598 | avc_node_replace(node, orig); | |
599 | out_unlock: | |
edf3d1ae | 600 | spin_unlock_irqrestore(lock, flag); |
1da177e4 LT |
601 | out: |
602 | return rc; | |
603 | } | |
604 | ||
605 | /** | |
008574b1 | 606 | * avc_flush - Flush the cache |
1da177e4 | 607 | */ |
008574b1 | 608 | static void avc_flush(void) |
1da177e4 | 609 | { |
26036651 | 610 | struct hlist_head *head; |
008574b1 | 611 | struct avc_node *node; |
edf3d1ae | 612 | spinlock_t *lock; |
008574b1 EP |
613 | unsigned long flag; |
614 | int i; | |
1da177e4 LT |
615 | |
616 | for (i = 0; i < AVC_CACHE_SLOTS; i++) { | |
edf3d1ae EP |
617 | head = &avc_cache.slots[i]; |
618 | lock = &avc_cache.slots_lock[i]; | |
619 | ||
620 | spin_lock_irqsave(lock, flag); | |
61844250 PM |
621 | /* |
622 | * With preemptable RCU, the outer spinlock does not | |
623 | * prevent RCU grace periods from ending. | |
624 | */ | |
625 | rcu_read_lock(); | |
b67bfe0d | 626 | hlist_for_each_entry(node, head, list) |
1da177e4 | 627 | avc_node_delete(node); |
61844250 | 628 | rcu_read_unlock(); |
edf3d1ae | 629 | spin_unlock_irqrestore(lock, flag); |
1da177e4 | 630 | } |
008574b1 EP |
631 | } |
632 | ||
633 | /** | |
634 | * avc_ss_reset - Flush the cache and revalidate migrated permissions. | |
635 | * @seqno: policy sequence number | |
636 | */ | |
637 | int avc_ss_reset(u32 seqno) | |
638 | { | |
639 | struct avc_callback_node *c; | |
640 | int rc = 0, tmprc; | |
641 | ||
642 | avc_flush(); | |
1da177e4 LT |
643 | |
644 | for (c = avc_callbacks; c; c = c->next) { | |
645 | if (c->events & AVC_CALLBACK_RESET) { | |
562c99f2 | 646 | tmprc = c->callback(AVC_CALLBACK_RESET); |
376bd9cb DG |
647 | /* save the first error encountered for the return |
648 | value and continue processing the callbacks */ | |
649 | if (!rc) | |
650 | rc = tmprc; | |
1da177e4 LT |
651 | } |
652 | } | |
653 | ||
654 | avc_latest_notif_update(seqno, 0); | |
1da177e4 LT |
655 | return rc; |
656 | } | |
657 | ||
a554bea8 LT |
658 | /* |
659 | * Slow-path helper function for avc_has_perm_noaudit, | |
660 | * when the avc_node lookup fails. We get called with | |
661 | * the RCU read lock held, and need to return with it | |
662 | * still held, but drop if for the security compute. | |
663 | * | |
664 | * Don't inline this, since it's the slow-path and just | |
665 | * results in a bigger stack frame. | |
666 | */ | |
667 | static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid, | |
668 | u16 tclass, struct av_decision *avd) | |
669 | { | |
670 | rcu_read_unlock(); | |
671 | security_compute_av(ssid, tsid, tclass, avd); | |
672 | rcu_read_lock(); | |
673 | return avc_insert(ssid, tsid, tclass, avd); | |
674 | } | |
675 | ||
676 | static noinline int avc_denied(u32 ssid, u32 tsid, | |
677 | u16 tclass, u32 requested, | |
678 | unsigned flags, | |
679 | struct av_decision *avd) | |
680 | { | |
681 | if (flags & AVC_STRICT) | |
682 | return -EACCES; | |
683 | ||
684 | if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE)) | |
685 | return -EACCES; | |
686 | ||
687 | avc_update_node(AVC_CALLBACK_GRANT, requested, ssid, | |
688 | tsid, tclass, avd->seqno); | |
689 | return 0; | |
690 | } | |
691 | ||
692 | ||
1da177e4 LT |
693 | /** |
694 | * avc_has_perm_noaudit - Check permissions but perform no auditing. | |
695 | * @ssid: source security identifier | |
696 | * @tsid: target security identifier | |
697 | * @tclass: target security class | |
698 | * @requested: requested permissions, interpreted based on @tclass | |
2c3c05db | 699 | * @flags: AVC_STRICT or 0 |
1da177e4 LT |
700 | * @avd: access vector decisions |
701 | * | |
702 | * Check the AVC to determine whether the @requested permissions are granted | |
703 | * for the SID pair (@ssid, @tsid), interpreting the permissions | |
704 | * based on @tclass, and call the security server on a cache miss to obtain | |
705 | * a new decision and add it to the cache. Return a copy of the decisions | |
706 | * in @avd. Return %0 if all @requested permissions are granted, | |
707 | * -%EACCES if any permissions are denied, or another -errno upon | |
708 | * other errors. This function is typically called by avc_has_perm(), | |
709 | * but may also be called directly to separate permission checking from | |
710 | * auditing, e.g. in cases where a lock must be held for the check but | |
711 | * should be released for the auditing. | |
712 | */ | |
cdb0f9a1 | 713 | inline int avc_has_perm_noaudit(u32 ssid, u32 tsid, |
2c3c05db SS |
714 | u16 tclass, u32 requested, |
715 | unsigned flags, | |
f01e1af4 | 716 | struct av_decision *avd) |
1da177e4 LT |
717 | { |
718 | struct avc_node *node; | |
1da177e4 LT |
719 | int rc = 0; |
720 | u32 denied; | |
721 | ||
eda4f69c EP |
722 | BUG_ON(!requested); |
723 | ||
1da177e4 LT |
724 | rcu_read_lock(); |
725 | ||
f1c6381a | 726 | node = avc_lookup(ssid, tsid, tclass); |
257313b2 | 727 | if (unlikely(!node)) { |
a554bea8 | 728 | node = avc_compute_av(ssid, tsid, tclass, avd); |
21193dcd | 729 | } else { |
f01e1af4 | 730 | memcpy(avd, &node->ae.avd, sizeof(*avd)); |
21193dcd | 731 | avd = &node->ae.avd; |
1da177e4 LT |
732 | } |
733 | ||
21193dcd | 734 | denied = requested & ~(avd->allowed); |
a554bea8 LT |
735 | if (unlikely(denied)) |
736 | rc = avc_denied(ssid, tsid, tclass, requested, flags, avd); | |
1da177e4 LT |
737 | |
738 | rcu_read_unlock(); | |
1da177e4 LT |
739 | return rc; |
740 | } | |
741 | ||
742 | /** | |
743 | * avc_has_perm - Check permissions and perform any appropriate auditing. | |
744 | * @ssid: source security identifier | |
745 | * @tsid: target security identifier | |
746 | * @tclass: target security class | |
747 | * @requested: requested permissions, interpreted based on @tclass | |
748 | * @auditdata: auxiliary audit data | |
749 | * | |
750 | * Check the AVC to determine whether the @requested permissions are granted | |
751 | * for the SID pair (@ssid, @tsid), interpreting the permissions | |
752 | * based on @tclass, and call the security server on a cache miss to obtain | |
753 | * a new decision and add it to the cache. Audit the granting or denial of | |
754 | * permissions in accordance with the policy. Return %0 if all @requested | |
755 | * permissions are granted, -%EACCES if any permissions are denied, or | |
756 | * another -errno upon other errors. | |
757 | */ | |
cb4fbe57 LT |
758 | int avc_has_perm(u32 ssid, u32 tsid, u16 tclass, |
759 | u32 requested, struct common_audit_data *auditdata) | |
1da177e4 LT |
760 | { |
761 | struct av_decision avd; | |
9ade0cf4 | 762 | int rc, rc2; |
1da177e4 | 763 | |
2c3c05db | 764 | rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd); |
9ade0cf4 | 765 | |
ab354062 | 766 | rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata); |
9ade0cf4 EP |
767 | if (rc2) |
768 | return rc2; | |
1da177e4 LT |
769 | return rc; |
770 | } | |
788e7dd4 YN |
771 | |
772 | u32 avc_policy_seqno(void) | |
773 | { | |
774 | return avc_cache.latest_notif; | |
775 | } | |
89c86576 TL |
776 | |
777 | void avc_disable(void) | |
778 | { | |
5224ee08 EP |
779 | /* |
780 | * If you are looking at this because you have realized that we are | |
781 | * not destroying the avc_node_cachep it might be easy to fix, but | |
782 | * I don't know the memory barrier semantics well enough to know. It's | |
783 | * possible that some other task dereferenced security_ops when | |
784 | * it still pointed to selinux operations. If that is the case it's | |
785 | * possible that it is about to use the avc and is about to need the | |
786 | * avc_node_cachep. I know I could wrap the security.c security_ops call | |
787 | * in an rcu_lock, but seriously, it's not worth it. Instead I just flush | |
788 | * the cache and get that memory back. | |
789 | */ | |
790 | if (avc_node_cachep) { | |
791 | avc_flush(); | |
792 | /* kmem_cache_destroy(avc_node_cachep); */ | |
793 | } | |
89c86576 | 794 | } |