1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Implementation of the kernel access vector cache (AVC).
4 *
5 * Authors: Stephen Smalley, <stephen.smalley.work@gmail.com>
6 * James Morris <jmorris@redhat.com>
7 *
8 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
9 * Replaced the avc_lock spinlock by RCU.
10 *
11 * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
12 */
13 #include <linux/types.h>
14 #include <linux/stddef.h>
15 #include <linux/kernel.h>
16 #include <linux/slab.h>
17 #include <linux/fs.h>
18 #include <linux/dcache.h>
19 #include <linux/init.h>
20 #include <linux/skbuff.h>
21 #include <linux/percpu.h>
22 #include <linux/list.h>
23 #include <net/sock.h>
24 #include <linux/un.h>
25 #include <net/af_unix.h>
26 #include <linux/ip.h>
27 #include <linux/audit.h>
28 #include <linux/ipv6.h>
29 #include <net/ipv6.h>
30 #include "avc.h"
31 #include "avc_ss.h"
32 #include "classmap.h"
33
34 #define CREATE_TRACE_POINTS
35 #include <trace/events/avc.h>
36
37 #define AVC_CACHE_SLOTS 512
38 #define AVC_DEF_CACHE_THRESHOLD 512
39 #define AVC_CACHE_RECLAIM 16
40
41 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
42 #define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
43 #else
44 #define avc_cache_stats_incr(field) do {} while (0)
45 #endif
46
47 struct avc_entry {
48 u32 ssid;
49 u32 tsid;
50 u16 tclass;
51 struct av_decision avd;
52 struct avc_xperms_node *xp_node;
53 };
54
55 struct avc_node {
56 struct avc_entry ae;
57 struct hlist_node list; /* anchored in avc_cache->slots[i] */
58 struct rcu_head rhead;
59 };
60
61 struct avc_xperms_decision_node {
62 struct extended_perms_decision xpd;
63 struct list_head xpd_list; /* list of extended_perms_decision */
64 };
65
66 struct avc_xperms_node {
67 struct extended_perms xp;
68 struct list_head xpd_head; /* list head of extended_perms_decision */
69 };
70
71 struct avc_cache {
72 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
73 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
74 atomic_t lru_hint; /* LRU hint for reclaim scan */
75 atomic_t active_nodes;
76 u32 latest_notif; /* latest revocation notification */
77 };
78
79 struct avc_callback_node {
80 int (*callback) (u32 event);
81 u32 events;
82 struct avc_callback_node *next;
83 };
84
85 #ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
86 DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
87 #endif
88
89 struct selinux_avc {
90 unsigned int avc_cache_threshold;
91 struct avc_cache avc_cache;
92 };
93
94 static struct selinux_avc selinux_avc;
95
96 void selinux_avc_init(void)
97 {
98 int i;
99
100 selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
101 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
102 INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
103 spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
104 }
105 atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
106 atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
107 }
108
109 unsigned int avc_get_cache_threshold(void)
110 {
111 return selinux_avc.avc_cache_threshold;
112 }
113
114 void avc_set_cache_threshold(unsigned int cache_threshold)
115 {
116 selinux_avc.avc_cache_threshold = cache_threshold;
117 }
118
119 static struct avc_callback_node *avc_callbacks __ro_after_init;
120 static struct kmem_cache *avc_node_cachep __ro_after_init;
121 static struct kmem_cache *avc_xperms_data_cachep __ro_after_init;
122 static struct kmem_cache *avc_xperms_decision_cachep __ro_after_init;
123 static struct kmem_cache *avc_xperms_cachep __ro_after_init;
124
125 static inline u32 avc_hash(u32 ssid, u32 tsid, u16 tclass)
126 {
127 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
128 }
129
130 /**
131 * avc_init - Initialize the AVC.
132 *
133 * Initialize the access vector cache.
134 */
135 void __init avc_init(void)
136 {
137 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
138 0, SLAB_PANIC, NULL);
139 avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
140 sizeof(struct avc_xperms_node),
141 0, SLAB_PANIC, NULL);
142 avc_xperms_decision_cachep = kmem_cache_create(
143 "avc_xperms_decision_node",
144 sizeof(struct avc_xperms_decision_node),
145 0, SLAB_PANIC, NULL);
146 avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
147 sizeof(struct extended_perms_data),
148 0, SLAB_PANIC, NULL);
149 }
150
151 int avc_get_hash_stats(char *page)
152 {
153 int i, chain_len, max_chain_len, slots_used;
154 struct avc_node *node;
155 struct hlist_head *head;
156
157 rcu_read_lock();
158
159 slots_used = 0;
160 max_chain_len = 0;
161 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
162 head = &selinux_avc.avc_cache.slots[i];
163 if (!hlist_empty(head)) {
164 slots_used++;
165 chain_len = 0;
166 hlist_for_each_entry_rcu(node, head, list)
167 chain_len++;
168 if (chain_len > max_chain_len)
169 max_chain_len = chain_len;
170 }
171 }
172
173 rcu_read_unlock();
174
175 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
176 "longest chain: %d\n",
177 atomic_read(&selinux_avc.avc_cache.active_nodes),
178 slots_used, AVC_CACHE_SLOTS, max_chain_len);
179 }
180
181 /*
182 * using a linked list for extended_perms_decision lookup because the list is
183 * always small. i.e. less than 5, typically 1
184 */
185 static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
186 struct avc_xperms_node *xp_node)
187 {
188 struct avc_xperms_decision_node *xpd_node;
189
190 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
191 if (xpd_node->xpd.driver == driver)
192 return &xpd_node->xpd;
193 }
194 return NULL;
195 }
196
197 static inline unsigned int
198 avc_xperms_has_perm(struct extended_perms_decision *xpd,
199 u8 perm, u8 which)
200 {
201 unsigned int rc = 0;
202
203 if ((which == XPERMS_ALLOWED) &&
204 (xpd->used & XPERMS_ALLOWED))
205 rc = security_xperm_test(xpd->allowed->p, perm);
206 else if ((which == XPERMS_AUDITALLOW) &&
207 (xpd->used & XPERMS_AUDITALLOW))
208 rc = security_xperm_test(xpd->auditallow->p, perm);
209 else if ((which == XPERMS_DONTAUDIT) &&
210 (xpd->used & XPERMS_DONTAUDIT))
211 rc = security_xperm_test(xpd->dontaudit->p, perm);
212 return rc;
213 }
214
215 static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
216 u8 driver, u8 perm)
217 {
218 struct extended_perms_decision *xpd;
219 security_xperm_set(xp_node->xp.drivers.p, driver);
220 xpd = avc_xperms_decision_lookup(driver, xp_node);
221 if (xpd && xpd->allowed)
222 security_xperm_set(xpd->allowed->p, perm);
223 }
224
225 static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
226 {
227 struct extended_perms_decision *xpd;
228
229 xpd = &xpd_node->xpd;
230 if (xpd->allowed)
231 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
232 if (xpd->auditallow)
233 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
234 if (xpd->dontaudit)
235 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
236 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
237 }
238
239 static void avc_xperms_free(struct avc_xperms_node *xp_node)
240 {
241 struct avc_xperms_decision_node *xpd_node, *tmp;
242
243 if (!xp_node)
244 return;
245
246 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
247 list_del(&xpd_node->xpd_list);
248 avc_xperms_decision_free(xpd_node);
249 }
250 kmem_cache_free(avc_xperms_cachep, xp_node);
251 }
252
253 static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
254 struct extended_perms_decision *src)
255 {
256 dest->driver = src->driver;
257 dest->used = src->used;
258 if (dest->used & XPERMS_ALLOWED)
259 memcpy(dest->allowed->p, src->allowed->p,
260 sizeof(src->allowed->p));
261 if (dest->used & XPERMS_AUDITALLOW)
262 memcpy(dest->auditallow->p, src->auditallow->p,
263 sizeof(src->auditallow->p));
264 if (dest->used & XPERMS_DONTAUDIT)
265 memcpy(dest->dontaudit->p, src->dontaudit->p,
266 sizeof(src->dontaudit->p));
267 }
268
269 /*
270 * similar to avc_copy_xperms_decision, but only copy decision
271 * information relevant to this perm
272 */
273 static inline void avc_quick_copy_xperms_decision(u8 perm,
274 struct extended_perms_decision *dest,
275 struct extended_perms_decision *src)
276 {
277 /*
278 * compute index of the u32 of the 256 bits (8 u32s) that contain this
279 * command permission
280 */
281 u8 i = perm >> 5;
282
283 dest->used = src->used;
284 if (dest->used & XPERMS_ALLOWED)
285 dest->allowed->p[i] = src->allowed->p[i];
286 if (dest->used & XPERMS_AUDITALLOW)
287 dest->auditallow->p[i] = src->auditallow->p[i];
288 if (dest->used & XPERMS_DONTAUDIT)
289 dest->dontaudit->p[i] = src->dontaudit->p[i];
290 }
291
292 static struct avc_xperms_decision_node
293 *avc_xperms_decision_alloc(u8 which)
294 {
295 struct avc_xperms_decision_node *xpd_node;
296 struct extended_perms_decision *xpd;
297
298 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
299 GFP_NOWAIT | __GFP_NOWARN);
300 if (!xpd_node)
301 return NULL;
302
303 xpd = &xpd_node->xpd;
304 if (which & XPERMS_ALLOWED) {
305 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
306 GFP_NOWAIT | __GFP_NOWARN);
307 if (!xpd->allowed)
308 goto error;
309 }
310 if (which & XPERMS_AUDITALLOW) {
311 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
312 GFP_NOWAIT | __GFP_NOWARN);
313 if (!xpd->auditallow)
314 goto error;
315 }
316 if (which & XPERMS_DONTAUDIT) {
317 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
318 GFP_NOWAIT | __GFP_NOWARN);
319 if (!xpd->dontaudit)
320 goto error;
321 }
322 return xpd_node;
323 error:
324 avc_xperms_decision_free(xpd_node);
325 return NULL;
326 }
327
328 static int avc_add_xperms_decision(struct avc_node *node,
329 struct extended_perms_decision *src)
330 {
331 struct avc_xperms_decision_node *dest_xpd;
332
333 dest_xpd = avc_xperms_decision_alloc(src->used);
334 if (!dest_xpd)
335 return -ENOMEM;
336 avc_copy_xperms_decision(&dest_xpd->xpd, src);
337 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
338 node->ae.xp_node->xp.len++;
339 return 0;
340 }
341
342 static struct avc_xperms_node *avc_xperms_alloc(void)
343 {
344 struct avc_xperms_node *xp_node;
345
346 xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT | __GFP_NOWARN);
347 if (!xp_node)
348 return xp_node;
349 INIT_LIST_HEAD(&xp_node->xpd_head);
350 return xp_node;
351 }
352
353 static int avc_xperms_populate(struct avc_node *node,
354 struct avc_xperms_node *src)
355 {
356 struct avc_xperms_node *dest;
357 struct avc_xperms_decision_node *dest_xpd;
358 struct avc_xperms_decision_node *src_xpd;
359
360 if (src->xp.len == 0)
361 return 0;
362 dest = avc_xperms_alloc();
363 if (!dest)
364 return -ENOMEM;
365
366 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
367 dest->xp.len = src->xp.len;
368
369 /* for each source xpd allocate a destination xpd and copy */
370 list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
371 dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
372 if (!dest_xpd)
373 goto error;
374 avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
375 list_add(&dest_xpd->xpd_list, &dest->xpd_head);
376 }
377 node->ae.xp_node = dest;
378 return 0;
379 error:
380 avc_xperms_free(dest);
381 return -ENOMEM;
382
383 }
384
385 static inline u32 avc_xperms_audit_required(u32 requested,
386 struct av_decision *avd,
387 struct extended_perms_decision *xpd,
388 u8 perm,
389 int result,
390 u32 *deniedp)
391 {
392 u32 denied, audited;
393
394 denied = requested & ~avd->allowed;
395 if (unlikely(denied)) {
396 audited = denied & avd->auditdeny;
397 if (audited && xpd) {
398 if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
399 audited &= ~requested;
400 }
401 } else if (result) {
402 audited = denied = requested;
403 } else {
404 audited = requested & avd->auditallow;
405 if (audited && xpd) {
406 if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
407 audited &= ~requested;
408 }
409 }
410
411 *deniedp = denied;
412 return audited;
413 }
414
415 static inline int avc_xperms_audit(u32 ssid, u32 tsid, u16 tclass,
416 u32 requested, struct av_decision *avd,
417 struct extended_perms_decision *xpd,
418 u8 perm, int result,
419 struct common_audit_data *ad)
420 {
421 u32 audited, denied;
422
423 audited = avc_xperms_audit_required(
424 requested, avd, xpd, perm, result, &denied);
425 if (likely(!audited))
426 return 0;
427 return slow_avc_audit(ssid, tsid, tclass, requested,
428 audited, denied, result, ad);
429 }
430
431 static void avc_node_free(struct rcu_head *rhead)
432 {
433 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
434 avc_xperms_free(node->ae.xp_node);
435 kmem_cache_free(avc_node_cachep, node);
436 avc_cache_stats_incr(frees);
437 }
438
439 static void avc_node_delete(struct avc_node *node)
440 {
441 hlist_del_rcu(&node->list);
442 call_rcu(&node->rhead, avc_node_free);
443 atomic_dec(&selinux_avc.avc_cache.active_nodes);
444 }
445
446 static void avc_node_kill(struct avc_node *node)
447 {
448 avc_xperms_free(node->ae.xp_node);
449 kmem_cache_free(avc_node_cachep, node);
450 avc_cache_stats_incr(frees);
451 atomic_dec(&selinux_avc.avc_cache.active_nodes);
452 }
453
454 static void avc_node_replace(struct avc_node *new, struct avc_node *old)
455 {
456 hlist_replace_rcu(&old->list, &new->list);
457 call_rcu(&old->rhead, avc_node_free);
458 atomic_dec(&selinux_avc.avc_cache.active_nodes);
459 }
460
461 static inline int avc_reclaim_node(void)
462 {
463 struct avc_node *node;
464 int hvalue, try, ecx;
465 unsigned long flags;
466 struct hlist_head *head;
467 spinlock_t *lock;
468
469 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
470 hvalue = atomic_inc_return(&selinux_avc.avc_cache.lru_hint) &
471 (AVC_CACHE_SLOTS - 1);
472 head = &selinux_avc.avc_cache.slots[hvalue];
473 lock = &selinux_avc.avc_cache.slots_lock[hvalue];
474
475 if (!spin_trylock_irqsave(lock, flags))
476 continue;
477
478 rcu_read_lock();
479 hlist_for_each_entry(node, head, list) {
480 avc_node_delete(node);
481 avc_cache_stats_incr(reclaims);
482 ecx++;
483 if (ecx >= AVC_CACHE_RECLAIM) {
484 rcu_read_unlock();
485 spin_unlock_irqrestore(lock, flags);
486 goto out;
487 }
488 }
489 rcu_read_unlock();
490 spin_unlock_irqrestore(lock, flags);
491 }
492 out:
493 return ecx;
494 }
495
496 static struct avc_node *avc_alloc_node(void)
497 {
498 struct avc_node *node;
499
500 node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN);
501 if (!node)
502 goto out;
503
504 INIT_HLIST_NODE(&node->list);
505 avc_cache_stats_incr(allocations);
506
507 if (atomic_inc_return(&selinux_avc.avc_cache.active_nodes) >
508 selinux_avc.avc_cache_threshold)
509 avc_reclaim_node();
510
511 out:
512 return node;
513 }
514
515 static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
516 {
517 node->ae.ssid = ssid;
518 node->ae.tsid = tsid;
519 node->ae.tclass = tclass;
520 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
521 }
522
523 static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
524 {
525 struct avc_node *node, *ret = NULL;
526 u32 hvalue;
527 struct hlist_head *head;
528
529 hvalue = avc_hash(ssid, tsid, tclass);
530 head = &selinux_avc.avc_cache.slots[hvalue];
531 hlist_for_each_entry_rcu(node, head, list) {
532 if (ssid == node->ae.ssid &&
533 tclass == node->ae.tclass &&
534 tsid == node->ae.tsid) {
535 ret = node;
536 break;
537 }
538 }
539
540 return ret;
541 }
542
543 /**
544 * avc_lookup - Look up an AVC entry.
545 * @ssid: source security identifier
546 * @tsid: target security identifier
547 * @tclass: target security class
548 *
549 * Look up an AVC entry that is valid for the
550 * (@ssid, @tsid), interpreting the permissions
551 * based on @tclass. If a valid AVC entry exists,
552 * then this function returns the avc_node.
553 * Otherwise, this function returns NULL.
554 */
555 static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
556 {
557 struct avc_node *node;
558
559 avc_cache_stats_incr(lookups);
560 node = avc_search_node(ssid, tsid, tclass);
561
562 if (node)
563 return node;
564
565 avc_cache_stats_incr(misses);
566 return NULL;
567 }
568
569 static int avc_latest_notif_update(u32 seqno, int is_insert)
570 {
571 int ret = 0;
572 static DEFINE_SPINLOCK(notif_lock);
573 unsigned long flag;
574
575 spin_lock_irqsave(¬if_lock, flag);
576 if (is_insert) {
577 if (seqno < selinux_avc.avc_cache.latest_notif) {
578 pr_warn("SELinux: avc: seqno %d < latest_notif %d\n",
579 seqno, selinux_avc.avc_cache.latest_notif);
580 ret = -EAGAIN;
581 }
582 } else {
583 if (seqno > selinux_avc.avc_cache.latest_notif)
584 selinux_avc.avc_cache.latest_notif = seqno;
585 }
586 spin_unlock_irqrestore(¬if_lock, flag);
587
588 return ret;
589 }
590
591 /**
592 * avc_insert - Insert an AVC entry.
593 * @ssid: source security identifier
594 * @tsid: target security identifier
595 * @tclass: target security class
596 * @avd: resulting av decision
597 * @xp_node: resulting extended permissions
598 *
599 * Insert an AVC entry for the SID pair
600 * (@ssid, @tsid) and class @tclass.
601 * The access vectors and the sequence number are
602 * normally provided by the security server in
603 * response to a security_compute_av() call. If the
604 * sequence number @avd->seqno is not less than the latest
605 * revocation notification, then the function copies
606 * the access vectors into a cache entry.
607 */
608 static void avc_insert(u32 ssid, u32 tsid, u16 tclass,
609 struct av_decision *avd, struct avc_xperms_node *xp_node)
610 {
611 struct avc_node *pos, *node = NULL;
612 u32 hvalue;
613 unsigned long flag;
614 spinlock_t *lock;
615 struct hlist_head *head;
616
617 if (avc_latest_notif_update(avd->seqno, 1))
618 return;
619
620 node = avc_alloc_node();
621 if (!node)
622 return;
623
624 avc_node_populate(node, ssid, tsid, tclass, avd);
625 if (avc_xperms_populate(node, xp_node)) {
626 avc_node_kill(node);
627 return;
628 }
629
630 hvalue = avc_hash(ssid, tsid, tclass);
631 head = &selinux_avc.avc_cache.slots[hvalue];
632 lock = &selinux_avc.avc_cache.slots_lock[hvalue];
633 spin_lock_irqsave(lock, flag);
634 hlist_for_each_entry(pos, head, list) {
635 if (pos->ae.ssid == ssid &&
636 pos->ae.tsid == tsid &&
637 pos->ae.tclass == tclass) {
638 avc_node_replace(node, pos);
639 goto found;
640 }
641 }
642 hlist_add_head_rcu(&node->list, head);
643 found:
644 spin_unlock_irqrestore(lock, flag);
645 }
646
647 /**
648 * avc_audit_pre_callback - SELinux specific information
649 * will be called by generic audit code
650 * @ab: the audit buffer
651 * @a: audit_data
652 */
653 static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
654 {
655 struct common_audit_data *ad = a;
656 struct selinux_audit_data *sad = ad->selinux_audit_data;
657 u32 av = sad->audited, perm;
658 const char *const *perms;
659 u32 i;
660
661 audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
662
663 if (av == 0) {
664 audit_log_format(ab, " null");
665 return;
666 }
667
668 perms = secclass_map[sad->tclass-1].perms;
669
670 audit_log_format(ab, " {");
671 i = 0;
672 perm = 1;
673 while (i < (sizeof(av) * 8)) {
674 if ((perm & av) && perms[i]) {
675 audit_log_format(ab, " %s", perms[i]);
676 av &= ~perm;
677 }
678 i++;
679 perm <<= 1;
680 }
681
682 if (av)
683 audit_log_format(ab, " 0x%x", av);
684
685 audit_log_format(ab, " } for ");
686 }
687
688 /**
689 * avc_audit_post_callback - SELinux specific information
690 * will be called by generic audit code
691 * @ab: the audit buffer
692 * @a: audit_data
693 */
694 static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
695 {
696 struct common_audit_data *ad = a;
697 struct selinux_audit_data *sad = ad->selinux_audit_data;
698 char *scontext = NULL;
699 char *tcontext = NULL;
700 const char *tclass = NULL;
701 u32 scontext_len;
702 u32 tcontext_len;
703 int rc;
704
705 rc = security_sid_to_context(sad->ssid, &scontext,
706 &scontext_len);
707 if (rc)
708 audit_log_format(ab, " ssid=%d", sad->ssid);
709 else
710 audit_log_format(ab, " scontext=%s", scontext);
711
712 rc = security_sid_to_context(sad->tsid, &tcontext,
713 &tcontext_len);
714 if (rc)
715 audit_log_format(ab, " tsid=%d", sad->tsid);
716 else
717 audit_log_format(ab, " tcontext=%s", tcontext);
718
719 tclass = secclass_map[sad->tclass-1].name;
720 audit_log_format(ab, " tclass=%s", tclass);
721
722 if (sad->denied)
723 audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
724
725 trace_selinux_audited(sad, scontext, tcontext, tclass);
726 kfree(tcontext);
727 kfree(scontext);
728
729 /* in case of invalid context report also the actual context string */
730 rc = security_sid_to_context_inval(sad->ssid, &scontext,
731 &scontext_len);
732 if (!rc && scontext) {
733 if (scontext_len && scontext[scontext_len - 1] == '\0')
734 scontext_len--;
735 audit_log_format(ab, " srawcon=");
736 audit_log_n_untrustedstring(ab, scontext, scontext_len);
737 kfree(scontext);
738 }
739
740 rc = security_sid_to_context_inval(sad->tsid, &scontext,
741 &scontext_len);
742 if (!rc && scontext) {
743 if (scontext_len && scontext[scontext_len - 1] == '\0')
744 scontext_len--;
745 audit_log_format(ab, " trawcon=");
746 audit_log_n_untrustedstring(ab, scontext, scontext_len);
747 kfree(scontext);
748 }
749 }
750
751 /*
752 * This is the slow part of avc audit with big stack footprint.
753 * Note that it is non-blocking and can be called from under
754 * rcu_read_lock().
755 */
756 noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
757 u32 requested, u32 audited, u32 denied, int result,
758 struct common_audit_data *a)
759 {
760 struct common_audit_data stack_data;
761 struct selinux_audit_data sad;
762
763 if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
764 return -EINVAL;
765
766 if (!a) {
767 a = &stack_data;
768 a->type = LSM_AUDIT_DATA_NONE;
769 }
770
771 sad.tclass = tclass;
772 sad.requested = requested;
773 sad.ssid = ssid;
774 sad.tsid = tsid;
775 sad.audited = audited;
776 sad.denied = denied;
777 sad.result = result;
778
779 a->selinux_audit_data = &sad;
780
781 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
782 return 0;
783 }
784
785 /**
786 * avc_add_callback - Register a callback for security events.
787 * @callback: callback function
788 * @events: security events
789 *
790 * Register a callback function for events in the set @events.
791 * Returns %0 on success or -%ENOMEM if insufficient memory
792 * exists to add the callback.
793 */
794 int __init avc_add_callback(int (*callback)(u32 event), u32 events)
795 {
796 struct avc_callback_node *c;
797 int rc = 0;
798
799 c = kmalloc(sizeof(*c), GFP_KERNEL);
800 if (!c) {
801 rc = -ENOMEM;
802 goto out;
803 }
804
805 c->callback = callback;
806 c->events = events;
807 c->next = avc_callbacks;
808 avc_callbacks = c;
809 out:
810 return rc;
811 }
812
813 /**
814 * avc_update_node - Update an AVC entry
815 * @event : Updating event
816 * @perms : Permission mask bits
817 * @driver: xperm driver information
818 * @xperm: xperm permissions
819 * @ssid: AVC entry source sid
820 * @tsid: AVC entry target sid
821 * @tclass : AVC entry target object class
822 * @seqno : sequence number when decision was made
823 * @xpd: extended_perms_decision to be added to the node
824 * @flags: the AVC_* flags, e.g. AVC_EXTENDED_PERMS, or 0.
825 *
826 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
827 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
828 * otherwise, this function updates the AVC entry. The original AVC-entry object
829 * will release later by RCU.
830 */
831 static int avc_update_node(u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
832 u32 tsid, u16 tclass, u32 seqno,
833 struct extended_perms_decision *xpd,
834 u32 flags)
835 {
836 u32 hvalue;
837 int rc = 0;
838 unsigned long flag;
839 struct avc_node *pos, *node, *orig = NULL;
840 struct hlist_head *head;
841 spinlock_t *lock;
842
843 node = avc_alloc_node();
844 if (!node) {
845 rc = -ENOMEM;
846 goto out;
847 }
848
849 /* Lock the target slot */
850 hvalue = avc_hash(ssid, tsid, tclass);
851
852 head = &selinux_avc.avc_cache.slots[hvalue];
853 lock = &selinux_avc.avc_cache.slots_lock[hvalue];
854
855 spin_lock_irqsave(lock, flag);
856
857 hlist_for_each_entry(pos, head, list) {
858 if (ssid == pos->ae.ssid &&
859 tsid == pos->ae.tsid &&
860 tclass == pos->ae.tclass &&
861 seqno == pos->ae.avd.seqno){
862 orig = pos;
863 break;
864 }
865 }
866
867 if (!orig) {
868 rc = -ENOENT;
869 avc_node_kill(node);
870 goto out_unlock;
871 }
872
873 /*
874 * Copy and replace original node.
875 */
876
877 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
878
879 if (orig->ae.xp_node) {
880 rc = avc_xperms_populate(node, orig->ae.xp_node);
881 if (rc) {
882 avc_node_kill(node);
883 goto out_unlock;
884 }
885 }
886
887 switch (event) {
888 case AVC_CALLBACK_GRANT:
889 node->ae.avd.allowed |= perms;
890 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
891 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
892 break;
893 case AVC_CALLBACK_TRY_REVOKE:
894 case AVC_CALLBACK_REVOKE:
895 node->ae.avd.allowed &= ~perms;
896 break;
897 case AVC_CALLBACK_AUDITALLOW_ENABLE:
898 node->ae.avd.auditallow |= perms;
899 break;
900 case AVC_CALLBACK_AUDITALLOW_DISABLE:
901 node->ae.avd.auditallow &= ~perms;
902 break;
903 case AVC_CALLBACK_AUDITDENY_ENABLE:
904 node->ae.avd.auditdeny |= perms;
905 break;
906 case AVC_CALLBACK_AUDITDENY_DISABLE:
907 node->ae.avd.auditdeny &= ~perms;
908 break;
909 case AVC_CALLBACK_ADD_XPERMS:
910 rc = avc_add_xperms_decision(node, xpd);
911 if (rc) {
912 avc_node_kill(node);
913 goto out_unlock;
914 }
915 break;
916 }
917 avc_node_replace(node, orig);
918 out_unlock:
919 spin_unlock_irqrestore(lock, flag);
920 out:
921 return rc;
922 }
923
924 /**
925 * avc_flush - Flush the cache
926 */
927 static void avc_flush(void)
928 {
929 struct hlist_head *head;
930 struct avc_node *node;
931 spinlock_t *lock;
932 unsigned long flag;
933 int i;
934
935 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
936 head = &selinux_avc.avc_cache.slots[i];
937 lock = &selinux_avc.avc_cache.slots_lock[i];
938
939 spin_lock_irqsave(lock, flag);
940 /*
941 * With preemptable RCU, the outer spinlock does not
942 * prevent RCU grace periods from ending.
943 */
944 rcu_read_lock();
945 hlist_for_each_entry(node, head, list)
946 avc_node_delete(node);
947 rcu_read_unlock();
948 spin_unlock_irqrestore(lock, flag);
949 }
950 }
951
952 /**
953 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
954 * @seqno: policy sequence number
955 */
956 int avc_ss_reset(u32 seqno)
957 {
958 struct avc_callback_node *c;
959 int rc = 0, tmprc;
960
961 avc_flush();
962
963 for (c = avc_callbacks; c; c = c->next) {
964 if (c->events & AVC_CALLBACK_RESET) {
965 tmprc = c->callback(AVC_CALLBACK_RESET);
966 /* save the first error encountered for the return
967 value and continue processing the callbacks */
968 if (!rc)
969 rc = tmprc;
970 }
971 }
972
973 avc_latest_notif_update(seqno, 0);
974 return rc;
975 }
976
977 /**
978 * avc_compute_av - Add an entry to the AVC based on the security policy
979 * @ssid: subject
980 * @tsid: object/target
981 * @tclass: object class
982 * @avd: access vector decision
983 * @xp_node: AVC extended permissions node
984 *
985 * Slow-path helper function for avc_has_perm_noaudit, when the avc_node lookup
986 * fails. Don't inline this, since it's the slow-path and just results in a
987 * bigger stack frame.
988 */
989 static noinline void avc_compute_av(u32 ssid, u32 tsid, u16 tclass,
990 struct av_decision *avd,
991 struct avc_xperms_node *xp_node)
992 {
993 INIT_LIST_HEAD(&xp_node->xpd_head);
994 security_compute_av(ssid, tsid, tclass, avd, &xp_node->xp);
995 avc_insert(ssid, tsid, tclass, avd, xp_node);
996 }
997
998 static noinline int avc_denied(u32 ssid, u32 tsid,
999 u16 tclass, u32 requested,
1000 u8 driver, u8 xperm, unsigned int flags,
1001 struct av_decision *avd)
1002 {
1003 if (flags & AVC_STRICT)
1004 return -EACCES;
1005
1006 if (enforcing_enabled() &&
1007 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1008 return -EACCES;
1009
1010 avc_update_node(AVC_CALLBACK_GRANT, requested, driver,
1011 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1012 return 0;
1013 }
1014
1015 /*
1016 * The avc extended permissions logic adds an additional 256 bits of
1017 * permissions to an avc node when extended permissions for that node are
1018 * specified in the avtab. If the additional 256 permissions is not adequate,
1019 * as-is the case with ioctls, then multiple may be chained together and the
1020 * driver field is used to specify which set contains the permission.
1021 */
1022 int avc_has_extended_perms(u32 ssid, u32 tsid, u16 tclass, u32 requested,
1023 u8 driver, u8 xperm, struct common_audit_data *ad)
1024 {
1025 struct avc_node *node;
1026 struct av_decision avd;
1027 u32 denied;
1028 struct extended_perms_decision local_xpd;
1029 struct extended_perms_decision *xpd = NULL;
1030 struct extended_perms_data allowed;
1031 struct extended_perms_data auditallow;
1032 struct extended_perms_data dontaudit;
1033 struct avc_xperms_node local_xp_node;
1034 struct avc_xperms_node *xp_node;
1035 int rc = 0, rc2;
1036
1037 xp_node = &local_xp_node;
1038 if (WARN_ON(!requested))
1039 return -EACCES;
1040
1041 rcu_read_lock();
1042
1043 node = avc_lookup(ssid, tsid, tclass);
1044 if (unlikely(!node)) {
1045 avc_compute_av(ssid, tsid, tclass, &avd, xp_node);
1046 } else {
1047 memcpy(&avd, &node->ae.avd, sizeof(avd));
1048 xp_node = node->ae.xp_node;
1049 }
1050 /* if extended permissions are not defined, only consider av_decision */
1051 if (!xp_node || !xp_node->xp.len)
1052 goto decision;
1053
1054 local_xpd.allowed = &allowed;
1055 local_xpd.auditallow = &auditallow;
1056 local_xpd.dontaudit = &dontaudit;
1057
1058 xpd = avc_xperms_decision_lookup(driver, xp_node);
1059 if (unlikely(!xpd)) {
1060 /*
1061 * Compute the extended_perms_decision only if the driver
1062 * is flagged
1063 */
1064 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1065 avd.allowed &= ~requested;
1066 goto decision;
1067 }
1068 rcu_read_unlock();
1069 security_compute_xperms_decision(ssid, tsid, tclass,
1070 driver, &local_xpd);
1071 rcu_read_lock();
1072 avc_update_node(AVC_CALLBACK_ADD_XPERMS, requested,
1073 driver, xperm, ssid, tsid, tclass, avd.seqno,
1074 &local_xpd, 0);
1075 } else {
1076 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1077 }
1078 xpd = &local_xpd;
1079
1080 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1081 avd.allowed &= ~requested;
1082
1083 decision:
1084 denied = requested & ~(avd.allowed);
1085 if (unlikely(denied))
1086 rc = avc_denied(ssid, tsid, tclass, requested,
1087 driver, xperm, AVC_EXTENDED_PERMS, &avd);
1088
1089 rcu_read_unlock();
1090
1091 rc2 = avc_xperms_audit(ssid, tsid, tclass, requested,
1092 &avd, xpd, xperm, rc, ad);
1093 if (rc2)
1094 return rc2;
1095 return rc;
1096 }
1097
1098 /**
1099 * avc_perm_nonode - Add an entry to the AVC
1100 * @ssid: subject
1101 * @tsid: object/target
1102 * @tclass: object class
1103 * @requested: requested permissions
1104 * @flags: AVC flags
1105 * @avd: access vector decision
1106 *
1107 * This is the "we have no node" part of avc_has_perm_noaudit(), which is
1108 * unlikely and needs extra stack space for the new node that we generate, so
1109 * don't inline it.
1110 */
1111 static noinline int avc_perm_nonode(u32 ssid, u32 tsid, u16 tclass,
1112 u32 requested, unsigned int flags,
1113 struct av_decision *avd)
1114 {
1115 u32 denied;
1116 struct avc_xperms_node xp_node;
1117
1118 avc_compute_av(ssid, tsid, tclass, avd, &xp_node);
1119 denied = requested & ~(avd->allowed);
1120 if (unlikely(denied))
1121 return avc_denied(ssid, tsid, tclass, requested, 0, 0,
1122 flags, avd);
1123 return 0;
1124 }
1125
1126 /**
1127 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1128 * @ssid: source security identifier
1129 * @tsid: target security identifier
1130 * @tclass: target security class
1131 * @requested: requested permissions, interpreted based on @tclass
1132 * @flags: AVC_STRICT or 0
1133 * @avd: access vector decisions
1134 *
1135 * Check the AVC to determine whether the @requested permissions are granted
1136 * for the SID pair (@ssid, @tsid), interpreting the permissions
1137 * based on @tclass, and call the security server on a cache miss to obtain
1138 * a new decision and add it to the cache. Return a copy of the decisions
1139 * in @avd. Return %0 if all @requested permissions are granted,
1140 * -%EACCES if any permissions are denied, or another -errno upon
1141 * other errors. This function is typically called by avc_has_perm(),
1142 * but may also be called directly to separate permission checking from
1143 * auditing, e.g. in cases where a lock must be held for the check but
1144 * should be released for the auditing.
1145 */
1146 inline int avc_has_perm_noaudit(u32 ssid, u32 tsid,
1147 u16 tclass, u32 requested,
1148 unsigned int flags,
1149 struct av_decision *avd)
1150 {
1151 u32 denied;
1152 struct avc_node *node;
1153
1154 if (WARN_ON(!requested))
1155 return -EACCES;
1156
1157 rcu_read_lock();
1158 node = avc_lookup(ssid, tsid, tclass);
1159 if (unlikely(!node)) {
1160 rcu_read_unlock();
1161 return avc_perm_nonode(ssid, tsid, tclass, requested,
1162 flags, avd);
1163 }
1164 denied = requested & ~node->ae.avd.allowed;
1165 memcpy(avd, &node->ae.avd, sizeof(*avd));
1166 rcu_read_unlock();
1167
1168 if (unlikely(denied))
1169 return avc_denied(ssid, tsid, tclass, requested, 0, 0,
1170 flags, avd);
1171 return 0;
1172 }
1173
1174 /**
1175 * avc_has_perm - Check permissions and perform any appropriate auditing.
1176 * @ssid: source security identifier
1177 * @tsid: target security identifier
1178 * @tclass: target security class
1179 * @requested: requested permissions, interpreted based on @tclass
1180 * @auditdata: auxiliary audit data
1181 *
1182 * Check the AVC to determine whether the @requested permissions are granted
1183 * for the SID pair (@ssid, @tsid), interpreting the permissions
1184 * based on @tclass, and call the security server on a cache miss to obtain
1185 * a new decision and add it to the cache. Audit the granting or denial of
1186 * permissions in accordance with the policy. Return %0 if all @requested
1187 * permissions are granted, -%EACCES if any permissions are denied, or
1188 * another -errno upon other errors.
1189 */
1190 int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
1191 u32 requested, struct common_audit_data *auditdata)
1192 {
1193 struct av_decision avd;
1194 int rc, rc2;
1195
1196 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0,
1197 &avd);
1198
1199 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc,
1200 auditdata);
1201 if (rc2)
1202 return rc2;
1203 return rc;
1204 }
1205
1206 u32 avc_policy_seqno(void)
1207 {
1208 return selinux_avc.avc_cache.latest_notif;
1209 }
1210
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