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1/*
2 * Implementation of the kernel access vector cache (AVC).
3 *
4 * Authors: Stephen Smalley, <sds@epoch.ncsc.mil>
5 * James Morris <jmorris@redhat.com>
6 *
7 * Update: KaiGai, Kohei <kaigai@ak.jp.nec.com>
8 * Replaced the avc_lock spinlock by RCU.
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,
14 * as published by the Free Software Foundation.
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 <linux/list.h>
26#include <net/sock.h>
27#include <linux/un.h>
28#include <net/af_unix.h>
29#include <linux/ip.h>
30#include <linux/audit.h>
31#include <linux/ipv6.h>
32#include <net/ipv6.h>
33#include "avc.h"
34#include "avc_ss.h"
35#include "classmap.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
47struct 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
55struct 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
61struct avc_xperms_decision_node {
62 struct extended_perms_decision xpd;
63 struct list_head xpd_list; /* list of extended_perms_decision */
64};
65
66struct avc_xperms_node {
67 struct extended_perms xp;
68 struct list_head xpd_head; /* list head of extended_perms_decision */
69};
70
71struct 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
79struct avc_callback_node {
80 int (*callback) (u32 event);
81 u32 events;
82 struct avc_callback_node *next;
83};
84
85/* Exported via selinufs */
86unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
87
88#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
89DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
90#endif
91
92static struct avc_cache avc_cache;
93static struct avc_callback_node *avc_callbacks;
94static struct kmem_cache *avc_node_cachep;
95static struct kmem_cache *avc_xperms_data_cachep;
96static struct kmem_cache *avc_xperms_decision_cachep;
97static struct kmem_cache *avc_xperms_cachep;
98
99static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
100{
101 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
102}
103
104/**
105 * avc_dump_av - Display an access vector in human-readable form.
106 * @tclass: target security class
107 * @av: access vector
108 */
109static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
110{
111 const char **perms;
112 int i, perm;
113
114 if (av == 0) {
115 audit_log_format(ab, " null");
116 return;
117 }
118
119 BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
120 perms = secclass_map[tclass-1].perms;
121
122 audit_log_format(ab, " {");
123 i = 0;
124 perm = 1;
125 while (i < (sizeof(av) * 8)) {
126 if ((perm & av) && perms[i]) {
127 audit_log_format(ab, " %s", perms[i]);
128 av &= ~perm;
129 }
130 i++;
131 perm <<= 1;
132 }
133
134 if (av)
135 audit_log_format(ab, " 0x%x", av);
136
137 audit_log_format(ab, " }");
138}
139
140/**
141 * avc_dump_query - Display a SID pair and a class in human-readable form.
142 * @ssid: source security identifier
143 * @tsid: target security identifier
144 * @tclass: target security class
145 */
146static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
147{
148 int rc;
149 char *scontext;
150 u32 scontext_len;
151
152 rc = security_sid_to_context(ssid, &scontext, &scontext_len);
153 if (rc)
154 audit_log_format(ab, "ssid=%d", ssid);
155 else {
156 audit_log_format(ab, "scontext=%s", scontext);
157 kfree(scontext);
158 }
159
160 rc = security_sid_to_context(tsid, &scontext, &scontext_len);
161 if (rc)
162 audit_log_format(ab, " tsid=%d", tsid);
163 else {
164 audit_log_format(ab, " tcontext=%s", scontext);
165 kfree(scontext);
166 }
167
168 BUG_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map));
169 audit_log_format(ab, " tclass=%s", secclass_map[tclass-1].name);
170}
171
172/**
173 * avc_init - Initialize the AVC.
174 *
175 * Initialize the access vector cache.
176 */
177void __init avc_init(void)
178{
179 int i;
180
181 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
182 INIT_HLIST_HEAD(&avc_cache.slots[i]);
183 spin_lock_init(&avc_cache.slots_lock[i]);
184 }
185 atomic_set(&avc_cache.active_nodes, 0);
186 atomic_set(&avc_cache.lru_hint, 0);
187
188 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
189 0, SLAB_PANIC, NULL);
190 avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
191 sizeof(struct avc_xperms_node),
192 0, SLAB_PANIC, NULL);
193 avc_xperms_decision_cachep = kmem_cache_create(
194 "avc_xperms_decision_node",
195 sizeof(struct avc_xperms_decision_node),
196 0, SLAB_PANIC, NULL);
197 avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
198 sizeof(struct extended_perms_data),
199 0, SLAB_PANIC, NULL);
200
201 audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "AVC INITIALIZED\n");
202}
203
204int avc_get_hash_stats(char *page)
205{
206 int i, chain_len, max_chain_len, slots_used;
207 struct avc_node *node;
208 struct hlist_head *head;
209
210 rcu_read_lock();
211
212 slots_used = 0;
213 max_chain_len = 0;
214 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
215 head = &avc_cache.slots[i];
216 if (!hlist_empty(head)) {
217 slots_used++;
218 chain_len = 0;
219 hlist_for_each_entry_rcu(node, head, list)
220 chain_len++;
221 if (chain_len > max_chain_len)
222 max_chain_len = chain_len;
223 }
224 }
225
226 rcu_read_unlock();
227
228 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
229 "longest chain: %d\n",
230 atomic_read(&avc_cache.active_nodes),
231 slots_used, AVC_CACHE_SLOTS, max_chain_len);
232}
233
234/*
235 * using a linked list for extended_perms_decision lookup because the list is
236 * always small. i.e. less than 5, typically 1
237 */
238static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
239 struct avc_xperms_node *xp_node)
240{
241 struct avc_xperms_decision_node *xpd_node;
242
243 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
244 if (xpd_node->xpd.driver == driver)
245 return &xpd_node->xpd;
246 }
247 return NULL;
248}
249
250static inline unsigned int
251avc_xperms_has_perm(struct extended_perms_decision *xpd,
252 u8 perm, u8 which)
253{
254 unsigned int rc = 0;
255
256 if ((which == XPERMS_ALLOWED) &&
257 (xpd->used & XPERMS_ALLOWED))
258 rc = security_xperm_test(xpd->allowed->p, perm);
259 else if ((which == XPERMS_AUDITALLOW) &&
260 (xpd->used & XPERMS_AUDITALLOW))
261 rc = security_xperm_test(xpd->auditallow->p, perm);
262 else if ((which == XPERMS_DONTAUDIT) &&
263 (xpd->used & XPERMS_DONTAUDIT))
264 rc = security_xperm_test(xpd->dontaudit->p, perm);
265 return rc;
266}
267
268static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
269 u8 driver, u8 perm)
270{
271 struct extended_perms_decision *xpd;
272 security_xperm_set(xp_node->xp.drivers.p, driver);
273 xpd = avc_xperms_decision_lookup(driver, xp_node);
274 if (xpd && xpd->allowed)
275 security_xperm_set(xpd->allowed->p, perm);
276}
277
278static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
279{
280 struct extended_perms_decision *xpd;
281
282 xpd = &xpd_node->xpd;
283 if (xpd->allowed)
284 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
285 if (xpd->auditallow)
286 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
287 if (xpd->dontaudit)
288 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
289 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
290}
291
292static void avc_xperms_free(struct avc_xperms_node *xp_node)
293{
294 struct avc_xperms_decision_node *xpd_node, *tmp;
295
296 if (!xp_node)
297 return;
298
299 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
300 list_del(&xpd_node->xpd_list);
301 avc_xperms_decision_free(xpd_node);
302 }
303 kmem_cache_free(avc_xperms_cachep, xp_node);
304}
305
306static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
307 struct extended_perms_decision *src)
308{
309 dest->driver = src->driver;
310 dest->used = src->used;
311 if (dest->used & XPERMS_ALLOWED)
312 memcpy(dest->allowed->p, src->allowed->p,
313 sizeof(src->allowed->p));
314 if (dest->used & XPERMS_AUDITALLOW)
315 memcpy(dest->auditallow->p, src->auditallow->p,
316 sizeof(src->auditallow->p));
317 if (dest->used & XPERMS_DONTAUDIT)
318 memcpy(dest->dontaudit->p, src->dontaudit->p,
319 sizeof(src->dontaudit->p));
320}
321
322/*
323 * similar to avc_copy_xperms_decision, but only copy decision
324 * information relevant to this perm
325 */
326static inline void avc_quick_copy_xperms_decision(u8 perm,
327 struct extended_perms_decision *dest,
328 struct extended_perms_decision *src)
329{
330 /*
331 * compute index of the u32 of the 256 bits (8 u32s) that contain this
332 * command permission
333 */
334 u8 i = perm >> 5;
335
336 dest->used = src->used;
337 if (dest->used & XPERMS_ALLOWED)
338 dest->allowed->p[i] = src->allowed->p[i];
339 if (dest->used & XPERMS_AUDITALLOW)
340 dest->auditallow->p[i] = src->auditallow->p[i];
341 if (dest->used & XPERMS_DONTAUDIT)
342 dest->dontaudit->p[i] = src->dontaudit->p[i];
343}
344
345static struct avc_xperms_decision_node
346 *avc_xperms_decision_alloc(u8 which)
347{
348 struct avc_xperms_decision_node *xpd_node;
349 struct extended_perms_decision *xpd;
350
351 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
352 GFP_ATOMIC | __GFP_NOMEMALLOC);
353 if (!xpd_node)
354 return NULL;
355
356 xpd = &xpd_node->xpd;
357 if (which & XPERMS_ALLOWED) {
358 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
359 GFP_ATOMIC | __GFP_NOMEMALLOC);
360 if (!xpd->allowed)
361 goto error;
362 }
363 if (which & XPERMS_AUDITALLOW) {
364 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
365 GFP_ATOMIC | __GFP_NOMEMALLOC);
366 if (!xpd->auditallow)
367 goto error;
368 }
369 if (which & XPERMS_DONTAUDIT) {
370 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
371 GFP_ATOMIC | __GFP_NOMEMALLOC);
372 if (!xpd->dontaudit)
373 goto error;
374 }
375 return xpd_node;
376error:
377 avc_xperms_decision_free(xpd_node);
378 return NULL;
379}
380
381static int avc_add_xperms_decision(struct avc_node *node,
382 struct extended_perms_decision *src)
383{
384 struct avc_xperms_decision_node *dest_xpd;
385
386 node->ae.xp_node->xp.len++;
387 dest_xpd = avc_xperms_decision_alloc(src->used);
388 if (!dest_xpd)
389 return -ENOMEM;
390 avc_copy_xperms_decision(&dest_xpd->xpd, src);
391 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
392 return 0;
393}
394
395static struct avc_xperms_node *avc_xperms_alloc(void)
396{
397 struct avc_xperms_node *xp_node;
398
399 xp_node = kmem_cache_zalloc(avc_xperms_cachep,
400 GFP_ATOMIC|__GFP_NOMEMALLOC);
401 if (!xp_node)
402 return xp_node;
403 INIT_LIST_HEAD(&xp_node->xpd_head);
404 return xp_node;
405}
406
407static int avc_xperms_populate(struct avc_node *node,
408 struct avc_xperms_node *src)
409{
410 struct avc_xperms_node *dest;
411 struct avc_xperms_decision_node *dest_xpd;
412 struct avc_xperms_decision_node *src_xpd;
413
414 if (src->xp.len == 0)
415 return 0;
416 dest = avc_xperms_alloc();
417 if (!dest)
418 return -ENOMEM;
419
420 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
421 dest->xp.len = src->xp.len;
422
423 /* for each source xpd allocate a destination xpd and copy */
424 list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
425 dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
426 if (!dest_xpd)
427 goto error;
428 avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
429 list_add(&dest_xpd->xpd_list, &dest->xpd_head);
430 }
431 node->ae.xp_node = dest;
432 return 0;
433error:
434 avc_xperms_free(dest);
435 return -ENOMEM;
436
437}
438
439static inline u32 avc_xperms_audit_required(u32 requested,
440 struct av_decision *avd,
441 struct extended_perms_decision *xpd,
442 u8 perm,
443 int result,
444 u32 *deniedp)
445{
446 u32 denied, audited;
447
448 denied = requested & ~avd->allowed;
449 if (unlikely(denied)) {
450 audited = denied & avd->auditdeny;
451 if (audited && xpd) {
452 if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
453 audited &= ~requested;
454 }
455 } else if (result) {
456 audited = denied = requested;
457 } else {
458 audited = requested & avd->auditallow;
459 if (audited && xpd) {
460 if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
461 audited &= ~requested;
462 }
463 }
464
465 *deniedp = denied;
466 return audited;
467}
468
469static inline int avc_xperms_audit(u32 ssid, u32 tsid, u16 tclass,
470 u32 requested, struct av_decision *avd,
471 struct extended_perms_decision *xpd,
472 u8 perm, int result,
473 struct common_audit_data *ad)
474{
475 u32 audited, denied;
476
477 audited = avc_xperms_audit_required(
478 requested, avd, xpd, perm, result, &denied);
479 if (likely(!audited))
480 return 0;
481 return slow_avc_audit(ssid, tsid, tclass, requested,
482 audited, denied, result, ad, 0);
483}
484
485static void avc_node_free(struct rcu_head *rhead)
486{
487 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
488 avc_xperms_free(node->ae.xp_node);
489 kmem_cache_free(avc_node_cachep, node);
490 avc_cache_stats_incr(frees);
491}
492
493static void avc_node_delete(struct avc_node *node)
494{
495 hlist_del_rcu(&node->list);
496 call_rcu(&node->rhead, avc_node_free);
497 atomic_dec(&avc_cache.active_nodes);
498}
499
500static void avc_node_kill(struct avc_node *node)
501{
502 avc_xperms_free(node->ae.xp_node);
503 kmem_cache_free(avc_node_cachep, node);
504 avc_cache_stats_incr(frees);
505 atomic_dec(&avc_cache.active_nodes);
506}
507
508static void avc_node_replace(struct avc_node *new, struct avc_node *old)
509{
510 hlist_replace_rcu(&old->list, &new->list);
511 call_rcu(&old->rhead, avc_node_free);
512 atomic_dec(&avc_cache.active_nodes);
513}
514
515static inline int avc_reclaim_node(void)
516{
517 struct avc_node *node;
518 int hvalue, try, ecx;
519 unsigned long flags;
520 struct hlist_head *head;
521 spinlock_t *lock;
522
523 for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
524 hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
525 head = &avc_cache.slots[hvalue];
526 lock = &avc_cache.slots_lock[hvalue];
527
528 if (!spin_trylock_irqsave(lock, flags))
529 continue;
530
531 rcu_read_lock();
532 hlist_for_each_entry(node, head, list) {
533 avc_node_delete(node);
534 avc_cache_stats_incr(reclaims);
535 ecx++;
536 if (ecx >= AVC_CACHE_RECLAIM) {
537 rcu_read_unlock();
538 spin_unlock_irqrestore(lock, flags);
539 goto out;
540 }
541 }
542 rcu_read_unlock();
543 spin_unlock_irqrestore(lock, flags);
544 }
545out:
546 return ecx;
547}
548
549static struct avc_node *avc_alloc_node(void)
550{
551 struct avc_node *node;
552
553 node = kmem_cache_zalloc(avc_node_cachep, GFP_ATOMIC|__GFP_NOMEMALLOC);
554 if (!node)
555 goto out;
556
557 INIT_HLIST_NODE(&node->list);
558 avc_cache_stats_incr(allocations);
559
560 if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
561 avc_reclaim_node();
562
563out:
564 return node;
565}
566
567static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
568{
569 node->ae.ssid = ssid;
570 node->ae.tsid = tsid;
571 node->ae.tclass = tclass;
572 memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
573}
574
575static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
576{
577 struct avc_node *node, *ret = NULL;
578 int hvalue;
579 struct hlist_head *head;
580
581 hvalue = avc_hash(ssid, tsid, tclass);
582 head = &avc_cache.slots[hvalue];
583 hlist_for_each_entry_rcu(node, head, list) {
584 if (ssid == node->ae.ssid &&
585 tclass == node->ae.tclass &&
586 tsid == node->ae.tsid) {
587 ret = node;
588 break;
589 }
590 }
591
592 return ret;
593}
594
595/**
596 * avc_lookup - Look up an AVC entry.
597 * @ssid: source security identifier
598 * @tsid: target security identifier
599 * @tclass: target security class
600 *
601 * Look up an AVC entry that is valid for the
602 * (@ssid, @tsid), interpreting the permissions
603 * based on @tclass. If a valid AVC entry exists,
604 * then this function returns the avc_node.
605 * Otherwise, this function returns NULL.
606 */
607static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass)
608{
609 struct avc_node *node;
610
611 avc_cache_stats_incr(lookups);
612 node = avc_search_node(ssid, tsid, tclass);
613
614 if (node)
615 return node;
616
617 avc_cache_stats_incr(misses);
618 return NULL;
619}
620
621static int avc_latest_notif_update(int seqno, int is_insert)
622{
623 int ret = 0;
624 static DEFINE_SPINLOCK(notif_lock);
625 unsigned long flag;
626
627 spin_lock_irqsave(¬if_lock, flag);
628 if (is_insert) {
629 if (seqno < avc_cache.latest_notif) {
630 printk(KERN_WARNING "SELinux: avc: seqno %d < latest_notif %d\n",
631 seqno, avc_cache.latest_notif);
632 ret = -EAGAIN;
633 }
634 } else {
635 if (seqno > avc_cache.latest_notif)
636 avc_cache.latest_notif = seqno;
637 }
638 spin_unlock_irqrestore(¬if_lock, flag);
639
640 return ret;
641}
642
643/**
644 * avc_insert - Insert an AVC entry.
645 * @ssid: source security identifier
646 * @tsid: target security identifier
647 * @tclass: target security class
648 * @avd: resulting av decision
649 * @xp_node: resulting extended permissions
650 *
651 * Insert an AVC entry for the SID pair
652 * (@ssid, @tsid) and class @tclass.
653 * The access vectors and the sequence number are
654 * normally provided by the security server in
655 * response to a security_compute_av() call. If the
656 * sequence number @avd->seqno is not less than the latest
657 * revocation notification, then the function copies
658 * the access vectors into a cache entry, returns
659 * avc_node inserted. Otherwise, this function returns NULL.
660 */
661static struct avc_node *avc_insert(u32 ssid, u32 tsid, u16 tclass,
662 struct av_decision *avd,
663 struct avc_xperms_node *xp_node)
664{
665 struct avc_node *pos, *node = NULL;
666 int hvalue;
667 unsigned long flag;
668
669 if (avc_latest_notif_update(avd->seqno, 1))
670 goto out;
671
672 node = avc_alloc_node();
673 if (node) {
674 struct hlist_head *head;
675 spinlock_t *lock;
676 int rc = 0;
677
678 hvalue = avc_hash(ssid, tsid, tclass);
679 avc_node_populate(node, ssid, tsid, tclass, avd);
680 rc = avc_xperms_populate(node, xp_node);
681 if (rc) {
682 kmem_cache_free(avc_node_cachep, node);
683 return NULL;
684 }
685 head = &avc_cache.slots[hvalue];
686 lock = &avc_cache.slots_lock[hvalue];
687
688 spin_lock_irqsave(lock, flag);
689 hlist_for_each_entry(pos, head, list) {
690 if (pos->ae.ssid == ssid &&
691 pos->ae.tsid == tsid &&
692 pos->ae.tclass == tclass) {
693 avc_node_replace(node, pos);
694 goto found;
695 }
696 }
697 hlist_add_head_rcu(&node->list, head);
698found:
699 spin_unlock_irqrestore(lock, flag);
700 }
701out:
702 return node;
703}
704
705/**
706 * avc_audit_pre_callback - SELinux specific information
707 * will be called by generic audit code
708 * @ab: the audit buffer
709 * @a: audit_data
710 */
711static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
712{
713 struct common_audit_data *ad = a;
714 audit_log_format(ab, "avc: %s ",
715 ad->selinux_audit_data->denied ? "denied" : "granted");
716 avc_dump_av(ab, ad->selinux_audit_data->tclass,
717 ad->selinux_audit_data->audited);
718 audit_log_format(ab, " for ");
719}
720
721/**
722 * avc_audit_post_callback - SELinux specific information
723 * will be called by generic audit code
724 * @ab: the audit buffer
725 * @a: audit_data
726 */
727static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
728{
729 struct common_audit_data *ad = a;
730 audit_log_format(ab, " ");
731 avc_dump_query(ab, ad->selinux_audit_data->ssid,
732 ad->selinux_audit_data->tsid,
733 ad->selinux_audit_data->tclass);
734 if (ad->selinux_audit_data->denied) {
735 audit_log_format(ab, " permissive=%u",
736 ad->selinux_audit_data->result ? 0 : 1);
737 }
738}
739
740/* This is the slow part of avc audit with big stack footprint */
741noinline int slow_avc_audit(u32 ssid, u32 tsid, u16 tclass,
742 u32 requested, u32 audited, u32 denied, int result,
743 struct common_audit_data *a,
744 unsigned flags)
745{
746 struct common_audit_data stack_data;
747 struct selinux_audit_data sad;
748
749 if (!a) {
750 a = &stack_data;
751 a->type = LSM_AUDIT_DATA_NONE;
752 }
753
754 /*
755 * When in a RCU walk do the audit on the RCU retry. This is because
756 * the collection of the dname in an inode audit message is not RCU
757 * safe. Note this may drop some audits when the situation changes
758 * during retry. However this is logically just as if the operation
759 * happened a little later.
760 */
761 if ((a->type == LSM_AUDIT_DATA_INODE) &&
762 (flags & MAY_NOT_BLOCK))
763 return -ECHILD;
764
765 sad.tclass = tclass;
766 sad.requested = requested;
767 sad.ssid = ssid;
768 sad.tsid = tsid;
769 sad.audited = audited;
770 sad.denied = denied;
771 sad.result = result;
772
773 a->selinux_audit_data = &sad;
774
775 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
776 return 0;
777}
778
779/**
780 * avc_add_callback - Register a callback for security events.
781 * @callback: callback function
782 * @events: security events
783 *
784 * Register a callback function for events in the set @events.
785 * Returns %0 on success or -%ENOMEM if insufficient memory
786 * exists to add the callback.
787 */
788int __init avc_add_callback(int (*callback)(u32 event), u32 events)
789{
790 struct avc_callback_node *c;
791 int rc = 0;
792
793 c = kmalloc(sizeof(*c), GFP_KERNEL);
794 if (!c) {
795 rc = -ENOMEM;
796 goto out;
797 }
798
799 c->callback = callback;
800 c->events = events;
801 c->next = avc_callbacks;
802 avc_callbacks = c;
803out:
804 return rc;
805}
806
807/**
808 * avc_update_node Update an AVC entry
809 * @event : Updating event
810 * @perms : Permission mask bits
811 * @ssid,@tsid,@tclass : identifier of an AVC entry
812 * @seqno : sequence number when decision was made
813 * @xpd: extended_perms_decision to be added to the node
814 *
815 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
816 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
817 * otherwise, this function updates the AVC entry. The original AVC-entry object
818 * will release later by RCU.
819 */
820static int avc_update_node(u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
821 u32 tsid, u16 tclass, u32 seqno,
822 struct extended_perms_decision *xpd,
823 u32 flags)
824{
825 int hvalue, rc = 0;
826 unsigned long flag;
827 struct avc_node *pos, *node, *orig = NULL;
828 struct hlist_head *head;
829 spinlock_t *lock;
830
831 node = avc_alloc_node();
832 if (!node) {
833 rc = -ENOMEM;
834 goto out;
835 }
836
837 /* Lock the target slot */
838 hvalue = avc_hash(ssid, tsid, tclass);
839
840 head = &avc_cache.slots[hvalue];
841 lock = &avc_cache.slots_lock[hvalue];
842
843 spin_lock_irqsave(lock, flag);
844
845 hlist_for_each_entry(pos, head, list) {
846 if (ssid == pos->ae.ssid &&
847 tsid == pos->ae.tsid &&
848 tclass == pos->ae.tclass &&
849 seqno == pos->ae.avd.seqno){
850 orig = pos;
851 break;
852 }
853 }
854
855 if (!orig) {
856 rc = -ENOENT;
857 avc_node_kill(node);
858 goto out_unlock;
859 }
860
861 /*
862 * Copy and replace original node.
863 */
864
865 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
866
867 if (orig->ae.xp_node) {
868 rc = avc_xperms_populate(node, orig->ae.xp_node);
869 if (rc) {
870 kmem_cache_free(avc_node_cachep, node);
871 goto out_unlock;
872 }
873 }
874
875 switch (event) {
876 case AVC_CALLBACK_GRANT:
877 node->ae.avd.allowed |= perms;
878 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
879 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
880 break;
881 case AVC_CALLBACK_TRY_REVOKE:
882 case AVC_CALLBACK_REVOKE:
883 node->ae.avd.allowed &= ~perms;
884 break;
885 case AVC_CALLBACK_AUDITALLOW_ENABLE:
886 node->ae.avd.auditallow |= perms;
887 break;
888 case AVC_CALLBACK_AUDITALLOW_DISABLE:
889 node->ae.avd.auditallow &= ~perms;
890 break;
891 case AVC_CALLBACK_AUDITDENY_ENABLE:
892 node->ae.avd.auditdeny |= perms;
893 break;
894 case AVC_CALLBACK_AUDITDENY_DISABLE:
895 node->ae.avd.auditdeny &= ~perms;
896 break;
897 case AVC_CALLBACK_ADD_XPERMS:
898 avc_add_xperms_decision(node, xpd);
899 break;
900 }
901 avc_node_replace(node, orig);
902out_unlock:
903 spin_unlock_irqrestore(lock, flag);
904out:
905 return rc;
906}
907
908/**
909 * avc_flush - Flush the cache
910 */
911static void avc_flush(void)
912{
913 struct hlist_head *head;
914 struct avc_node *node;
915 spinlock_t *lock;
916 unsigned long flag;
917 int i;
918
919 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
920 head = &avc_cache.slots[i];
921 lock = &avc_cache.slots_lock[i];
922
923 spin_lock_irqsave(lock, flag);
924 /*
925 * With preemptable RCU, the outer spinlock does not
926 * prevent RCU grace periods from ending.
927 */
928 rcu_read_lock();
929 hlist_for_each_entry(node, head, list)
930 avc_node_delete(node);
931 rcu_read_unlock();
932 spin_unlock_irqrestore(lock, flag);
933 }
934}
935
936/**
937 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
938 * @seqno: policy sequence number
939 */
940int avc_ss_reset(u32 seqno)
941{
942 struct avc_callback_node *c;
943 int rc = 0, tmprc;
944
945 avc_flush();
946
947 for (c = avc_callbacks; c; c = c->next) {
948 if (c->events & AVC_CALLBACK_RESET) {
949 tmprc = c->callback(AVC_CALLBACK_RESET);
950 /* save the first error encountered for the return
951 value and continue processing the callbacks */
952 if (!rc)
953 rc = tmprc;
954 }
955 }
956
957 avc_latest_notif_update(seqno, 0);
958 return rc;
959}
960
961/*
962 * Slow-path helper function for avc_has_perm_noaudit,
963 * when the avc_node lookup fails. We get called with
964 * the RCU read lock held, and need to return with it
965 * still held, but drop if for the security compute.
966 *
967 * Don't inline this, since it's the slow-path and just
968 * results in a bigger stack frame.
969 */
970static noinline struct avc_node *avc_compute_av(u32 ssid, u32 tsid,
971 u16 tclass, struct av_decision *avd,
972 struct avc_xperms_node *xp_node)
973{
974 rcu_read_unlock();
975 INIT_LIST_HEAD(&xp_node->xpd_head);
976 security_compute_av(ssid, tsid, tclass, avd, &xp_node->xp);
977 rcu_read_lock();
978 return avc_insert(ssid, tsid, tclass, avd, xp_node);
979}
980
981static noinline int avc_denied(u32 ssid, u32 tsid,
982 u16 tclass, u32 requested,
983 u8 driver, u8 xperm, unsigned flags,
984 struct av_decision *avd)
985{
986 if (flags & AVC_STRICT)
987 return -EACCES;
988
989 if (selinux_enforcing && !(avd->flags & AVD_FLAGS_PERMISSIVE))
990 return -EACCES;
991
992 avc_update_node(AVC_CALLBACK_GRANT, requested, driver, xperm, ssid,
993 tsid, tclass, avd->seqno, NULL, flags);
994 return 0;
995}
996
997/*
998 * The avc extended permissions logic adds an additional 256 bits of
999 * permissions to an avc node when extended permissions for that node are
1000 * specified in the avtab. If the additional 256 permissions is not adequate,
1001 * as-is the case with ioctls, then multiple may be chained together and the
1002 * driver field is used to specify which set contains the permission.
1003 */
1004int avc_has_extended_perms(u32 ssid, u32 tsid, u16 tclass, u32 requested,
1005 u8 driver, u8 xperm, struct common_audit_data *ad)
1006{
1007 struct avc_node *node;
1008 struct av_decision avd;
1009 u32 denied;
1010 struct extended_perms_decision local_xpd;
1011 struct extended_perms_decision *xpd = NULL;
1012 struct extended_perms_data allowed;
1013 struct extended_perms_data auditallow;
1014 struct extended_perms_data dontaudit;
1015 struct avc_xperms_node local_xp_node;
1016 struct avc_xperms_node *xp_node;
1017 int rc = 0, rc2;
1018
1019 xp_node = &local_xp_node;
1020 BUG_ON(!requested);
1021
1022 rcu_read_lock();
1023
1024 node = avc_lookup(ssid, tsid, tclass);
1025 if (unlikely(!node)) {
1026 node = avc_compute_av(ssid, tsid, tclass, &avd, xp_node);
1027 } else {
1028 memcpy(&avd, &node->ae.avd, sizeof(avd));
1029 xp_node = node->ae.xp_node;
1030 }
1031 /* if extended permissions are not defined, only consider av_decision */
1032 if (!xp_node || !xp_node->xp.len)
1033 goto decision;
1034
1035 local_xpd.allowed = &allowed;
1036 local_xpd.auditallow = &auditallow;
1037 local_xpd.dontaudit = &dontaudit;
1038
1039 xpd = avc_xperms_decision_lookup(driver, xp_node);
1040 if (unlikely(!xpd)) {
1041 /*
1042 * Compute the extended_perms_decision only if the driver
1043 * is flagged
1044 */
1045 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1046 avd.allowed &= ~requested;
1047 goto decision;
1048 }
1049 rcu_read_unlock();
1050 security_compute_xperms_decision(ssid, tsid, tclass, driver,
1051 &local_xpd);
1052 rcu_read_lock();
1053 avc_update_node(AVC_CALLBACK_ADD_XPERMS, requested, driver, xperm,
1054 ssid, tsid, tclass, avd.seqno, &local_xpd, 0);
1055 } else {
1056 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1057 }
1058 xpd = &local_xpd;
1059
1060 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1061 avd.allowed &= ~requested;
1062
1063decision:
1064 denied = requested & ~(avd.allowed);
1065 if (unlikely(denied))
1066 rc = avc_denied(ssid, tsid, tclass, requested, driver, xperm,
1067 AVC_EXTENDED_PERMS, &avd);
1068
1069 rcu_read_unlock();
1070
1071 rc2 = avc_xperms_audit(ssid, tsid, tclass, requested,
1072 &avd, xpd, xperm, rc, ad);
1073 if (rc2)
1074 return rc2;
1075 return rc;
1076}
1077
1078/**
1079 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1080 * @ssid: source security identifier
1081 * @tsid: target security identifier
1082 * @tclass: target security class
1083 * @requested: requested permissions, interpreted based on @tclass
1084 * @flags: AVC_STRICT or 0
1085 * @avd: access vector decisions
1086 *
1087 * Check the AVC to determine whether the @requested permissions are granted
1088 * for the SID pair (@ssid, @tsid), interpreting the permissions
1089 * based on @tclass, and call the security server on a cache miss to obtain
1090 * a new decision and add it to the cache. Return a copy of the decisions
1091 * in @avd. Return %0 if all @requested permissions are granted,
1092 * -%EACCES if any permissions are denied, or another -errno upon
1093 * other errors. This function is typically called by avc_has_perm(),
1094 * but may also be called directly to separate permission checking from
1095 * auditing, e.g. in cases where a lock must be held for the check but
1096 * should be released for the auditing.
1097 */
1098inline int avc_has_perm_noaudit(u32 ssid, u32 tsid,
1099 u16 tclass, u32 requested,
1100 unsigned flags,
1101 struct av_decision *avd)
1102{
1103 struct avc_node *node;
1104 struct avc_xperms_node xp_node;
1105 int rc = 0;
1106 u32 denied;
1107
1108 BUG_ON(!requested);
1109
1110 rcu_read_lock();
1111
1112 node = avc_lookup(ssid, tsid, tclass);
1113 if (unlikely(!node))
1114 node = avc_compute_av(ssid, tsid, tclass, avd, &xp_node);
1115 else
1116 memcpy(avd, &node->ae.avd, sizeof(*avd));
1117
1118 denied = requested & ~(avd->allowed);
1119 if (unlikely(denied))
1120 rc = avc_denied(ssid, tsid, tclass, requested, 0, 0, flags, avd);
1121
1122 rcu_read_unlock();
1123 return rc;
1124}
1125
1126/**
1127 * avc_has_perm - Check permissions and perform any appropriate 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 * @auditdata: auxiliary audit data
1133 *
1134 * Check the AVC to determine whether the @requested permissions are granted
1135 * for the SID pair (@ssid, @tsid), interpreting the permissions
1136 * based on @tclass, and call the security server on a cache miss to obtain
1137 * a new decision and add it to the cache. Audit the granting or denial of
1138 * permissions in accordance with the policy. Return %0 if all @requested
1139 * permissions are granted, -%EACCES if any permissions are denied, or
1140 * another -errno upon other errors.
1141 */
1142int avc_has_perm(u32 ssid, u32 tsid, u16 tclass,
1143 u32 requested, struct common_audit_data *auditdata)
1144{
1145 struct av_decision avd;
1146 int rc, rc2;
1147
1148 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
1149
1150 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata, 0);
1151 if (rc2)
1152 return rc2;
1153 return rc;
1154}
1155
1156int avc_has_perm_flags(u32 ssid, u32 tsid, u16 tclass,
1157 u32 requested, struct common_audit_data *auditdata,
1158 int flags)
1159{
1160 struct av_decision avd;
1161 int rc, rc2;
1162
1163 rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, 0, &avd);
1164
1165 rc2 = avc_audit(ssid, tsid, tclass, requested, &avd, rc,
1166 auditdata, flags);
1167 if (rc2)
1168 return rc2;
1169 return rc;
1170}
1171
1172u32 avc_policy_seqno(void)
1173{
1174 return avc_cache.latest_notif;
1175}
1176
1177void avc_disable(void)
1178{
1179 /*
1180 * If you are looking at this because you have realized that we are
1181 * not destroying the avc_node_cachep it might be easy to fix, but
1182 * I don't know the memory barrier semantics well enough to know. It's
1183 * possible that some other task dereferenced security_ops when
1184 * it still pointed to selinux operations. If that is the case it's
1185 * possible that it is about to use the avc and is about to need the
1186 * avc_node_cachep. I know I could wrap the security.c security_ops call
1187 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1188 * the cache and get that memory back.
1189 */
1190 if (avc_node_cachep) {
1191 avc_flush();
1192 /* kmem_cache_destroy(avc_node_cachep); */
1193 }
1194}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Implementation of the kernel access vector cache (AVC).
4 *
5 * Authors: Stephen Smalley, <sds@tycho.nsa.gov>
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 AVC_CACHE_SLOTS 512
35#define AVC_DEF_CACHE_THRESHOLD 512
36#define AVC_CACHE_RECLAIM 16
37
38#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
39#define avc_cache_stats_incr(field) this_cpu_inc(avc_cache_stats.field)
40#else
41#define avc_cache_stats_incr(field) do {} while (0)
42#endif
43
44struct avc_entry {
45 u32 ssid;
46 u32 tsid;
47 u16 tclass;
48 struct av_decision avd;
49 struct avc_xperms_node *xp_node;
50};
51
52struct avc_node {
53 struct avc_entry ae;
54 struct hlist_node list; /* anchored in avc_cache->slots[i] */
55 struct rcu_head rhead;
56};
57
58struct avc_xperms_decision_node {
59 struct extended_perms_decision xpd;
60 struct list_head xpd_list; /* list of extended_perms_decision */
61};
62
63struct avc_xperms_node {
64 struct extended_perms xp;
65 struct list_head xpd_head; /* list head of extended_perms_decision */
66};
67
68struct avc_cache {
69 struct hlist_head slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
70 spinlock_t slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
71 atomic_t lru_hint; /* LRU hint for reclaim scan */
72 atomic_t active_nodes;
73 u32 latest_notif; /* latest revocation notification */
74};
75
76struct avc_callback_node {
77 int (*callback) (u32 event);
78 u32 events;
79 struct avc_callback_node *next;
80};
81
82#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
83DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
84#endif
85
86struct selinux_avc {
87 unsigned int avc_cache_threshold;
88 struct avc_cache avc_cache;
89};
90
91static struct selinux_avc selinux_avc;
92
93void selinux_avc_init(struct selinux_avc **avc)
94{
95 int i;
96
97 selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
98 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
99 INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
100 spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
101 }
102 atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
103 atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
104 *avc = &selinux_avc;
105}
106
107unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
108{
109 return avc->avc_cache_threshold;
110}
111
112void avc_set_cache_threshold(struct selinux_avc *avc,
113 unsigned int cache_threshold)
114{
115 avc->avc_cache_threshold = cache_threshold;
116}
117
118static struct avc_callback_node *avc_callbacks;
119static struct kmem_cache *avc_node_cachep;
120static struct kmem_cache *avc_xperms_data_cachep;
121static struct kmem_cache *avc_xperms_decision_cachep;
122static struct kmem_cache *avc_xperms_cachep;
123
124static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
125{
126 return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
127}
128
129/**
130 * avc_init - Initialize the AVC.
131 *
132 * Initialize the access vector cache.
133 */
134void __init avc_init(void)
135{
136 avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
137 0, SLAB_PANIC, NULL);
138 avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
139 sizeof(struct avc_xperms_node),
140 0, SLAB_PANIC, NULL);
141 avc_xperms_decision_cachep = kmem_cache_create(
142 "avc_xperms_decision_node",
143 sizeof(struct avc_xperms_decision_node),
144 0, SLAB_PANIC, NULL);
145 avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
146 sizeof(struct extended_perms_data),
147 0, SLAB_PANIC, NULL);
148}
149
150int avc_get_hash_stats(struct selinux_avc *avc, char *page)
151{
152 int i, chain_len, max_chain_len, slots_used;
153 struct avc_node *node;
154 struct hlist_head *head;
155
156 rcu_read_lock();
157
158 slots_used = 0;
159 max_chain_len = 0;
160 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
161 head = &avc->avc_cache.slots[i];
162 if (!hlist_empty(head)) {
163 slots_used++;
164 chain_len = 0;
165 hlist_for_each_entry_rcu(node, head, list)
166 chain_len++;
167 if (chain_len > max_chain_len)
168 max_chain_len = chain_len;
169 }
170 }
171
172 rcu_read_unlock();
173
174 return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
175 "longest chain: %d\n",
176 atomic_read(&avc->avc_cache.active_nodes),
177 slots_used, AVC_CACHE_SLOTS, max_chain_len);
178}
179
180/*
181 * using a linked list for extended_perms_decision lookup because the list is
182 * always small. i.e. less than 5, typically 1
183 */
184static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
185 struct avc_xperms_node *xp_node)
186{
187 struct avc_xperms_decision_node *xpd_node;
188
189 list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
190 if (xpd_node->xpd.driver == driver)
191 return &xpd_node->xpd;
192 }
193 return NULL;
194}
195
196static inline unsigned int
197avc_xperms_has_perm(struct extended_perms_decision *xpd,
198 u8 perm, u8 which)
199{
200 unsigned int rc = 0;
201
202 if ((which == XPERMS_ALLOWED) &&
203 (xpd->used & XPERMS_ALLOWED))
204 rc = security_xperm_test(xpd->allowed->p, perm);
205 else if ((which == XPERMS_AUDITALLOW) &&
206 (xpd->used & XPERMS_AUDITALLOW))
207 rc = security_xperm_test(xpd->auditallow->p, perm);
208 else if ((which == XPERMS_DONTAUDIT) &&
209 (xpd->used & XPERMS_DONTAUDIT))
210 rc = security_xperm_test(xpd->dontaudit->p, perm);
211 return rc;
212}
213
214static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
215 u8 driver, u8 perm)
216{
217 struct extended_perms_decision *xpd;
218 security_xperm_set(xp_node->xp.drivers.p, driver);
219 xpd = avc_xperms_decision_lookup(driver, xp_node);
220 if (xpd && xpd->allowed)
221 security_xperm_set(xpd->allowed->p, perm);
222}
223
224static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
225{
226 struct extended_perms_decision *xpd;
227
228 xpd = &xpd_node->xpd;
229 if (xpd->allowed)
230 kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
231 if (xpd->auditallow)
232 kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
233 if (xpd->dontaudit)
234 kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
235 kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
236}
237
238static void avc_xperms_free(struct avc_xperms_node *xp_node)
239{
240 struct avc_xperms_decision_node *xpd_node, *tmp;
241
242 if (!xp_node)
243 return;
244
245 list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
246 list_del(&xpd_node->xpd_list);
247 avc_xperms_decision_free(xpd_node);
248 }
249 kmem_cache_free(avc_xperms_cachep, xp_node);
250}
251
252static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
253 struct extended_perms_decision *src)
254{
255 dest->driver = src->driver;
256 dest->used = src->used;
257 if (dest->used & XPERMS_ALLOWED)
258 memcpy(dest->allowed->p, src->allowed->p,
259 sizeof(src->allowed->p));
260 if (dest->used & XPERMS_AUDITALLOW)
261 memcpy(dest->auditallow->p, src->auditallow->p,
262 sizeof(src->auditallow->p));
263 if (dest->used & XPERMS_DONTAUDIT)
264 memcpy(dest->dontaudit->p, src->dontaudit->p,
265 sizeof(src->dontaudit->p));
266}
267
268/*
269 * similar to avc_copy_xperms_decision, but only copy decision
270 * information relevant to this perm
271 */
272static inline void avc_quick_copy_xperms_decision(u8 perm,
273 struct extended_perms_decision *dest,
274 struct extended_perms_decision *src)
275{
276 /*
277 * compute index of the u32 of the 256 bits (8 u32s) that contain this
278 * command permission
279 */
280 u8 i = perm >> 5;
281
282 dest->used = src->used;
283 if (dest->used & XPERMS_ALLOWED)
284 dest->allowed->p[i] = src->allowed->p[i];
285 if (dest->used & XPERMS_AUDITALLOW)
286 dest->auditallow->p[i] = src->auditallow->p[i];
287 if (dest->used & XPERMS_DONTAUDIT)
288 dest->dontaudit->p[i] = src->dontaudit->p[i];
289}
290
291static struct avc_xperms_decision_node
292 *avc_xperms_decision_alloc(u8 which)
293{
294 struct avc_xperms_decision_node *xpd_node;
295 struct extended_perms_decision *xpd;
296
297 xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep, GFP_NOWAIT);
298 if (!xpd_node)
299 return NULL;
300
301 xpd = &xpd_node->xpd;
302 if (which & XPERMS_ALLOWED) {
303 xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
304 GFP_NOWAIT);
305 if (!xpd->allowed)
306 goto error;
307 }
308 if (which & XPERMS_AUDITALLOW) {
309 xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
310 GFP_NOWAIT);
311 if (!xpd->auditallow)
312 goto error;
313 }
314 if (which & XPERMS_DONTAUDIT) {
315 xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
316 GFP_NOWAIT);
317 if (!xpd->dontaudit)
318 goto error;
319 }
320 return xpd_node;
321error:
322 avc_xperms_decision_free(xpd_node);
323 return NULL;
324}
325
326static int avc_add_xperms_decision(struct avc_node *node,
327 struct extended_perms_decision *src)
328{
329 struct avc_xperms_decision_node *dest_xpd;
330
331 node->ae.xp_node->xp.len++;
332 dest_xpd = avc_xperms_decision_alloc(src->used);
333 if (!dest_xpd)
334 return -ENOMEM;
335 avc_copy_xperms_decision(&dest_xpd->xpd, src);
336 list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
337 return 0;
338}
339
340static struct avc_xperms_node *avc_xperms_alloc(void)
341{
342 struct avc_xperms_node *xp_node;
343
344 xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT);
345 if (!xp_node)
346 return xp_node;
347 INIT_LIST_HEAD(&xp_node->xpd_head);
348 return xp_node;
349}
350
351static int avc_xperms_populate(struct avc_node *node,
352 struct avc_xperms_node *src)
353{
354 struct avc_xperms_node *dest;
355 struct avc_xperms_decision_node *dest_xpd;
356 struct avc_xperms_decision_node *src_xpd;
357
358 if (src->xp.len == 0)
359 return 0;
360 dest = avc_xperms_alloc();
361 if (!dest)
362 return -ENOMEM;
363
364 memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
365 dest->xp.len = src->xp.len;
366
367 /* for each source xpd allocate a destination xpd and copy */
368 list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
369 dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
370 if (!dest_xpd)
371 goto error;
372 avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
373 list_add(&dest_xpd->xpd_list, &dest->xpd_head);
374 }
375 node->ae.xp_node = dest;
376 return 0;
377error:
378 avc_xperms_free(dest);
379 return -ENOMEM;
380
381}
382
383static inline u32 avc_xperms_audit_required(u32 requested,
384 struct av_decision *avd,
385 struct extended_perms_decision *xpd,
386 u8 perm,
387 int result,
388 u32 *deniedp)
389{
390 u32 denied, audited;
391
392 denied = requested & ~avd->allowed;
393 if (unlikely(denied)) {
394 audited = denied & avd->auditdeny;
395 if (audited && xpd) {
396 if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
397 audited &= ~requested;
398 }
399 } else if (result) {
400 audited = denied = requested;
401 } else {
402 audited = requested & avd->auditallow;
403 if (audited && xpd) {
404 if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
405 audited &= ~requested;
406 }
407 }
408
409 *deniedp = denied;
410 return audited;
411}
412
413static inline int avc_xperms_audit(struct selinux_state *state,
414 u32 ssid, u32 tsid, u16 tclass,
415 u32 requested, struct av_decision *avd,
416 struct extended_perms_decision *xpd,
417 u8 perm, int result,
418 struct common_audit_data *ad)
419{
420 u32 audited, denied;
421
422 audited = avc_xperms_audit_required(
423 requested, avd, xpd, perm, result, &denied);
424 if (likely(!audited))
425 return 0;
426 return slow_avc_audit(state, ssid, tsid, tclass, requested,
427 audited, denied, result, ad);
428}
429
430static void avc_node_free(struct rcu_head *rhead)
431{
432 struct avc_node *node = container_of(rhead, struct avc_node, rhead);
433 avc_xperms_free(node->ae.xp_node);
434 kmem_cache_free(avc_node_cachep, node);
435 avc_cache_stats_incr(frees);
436}
437
438static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
439{
440 hlist_del_rcu(&node->list);
441 call_rcu(&node->rhead, avc_node_free);
442 atomic_dec(&avc->avc_cache.active_nodes);
443}
444
445static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
446{
447 avc_xperms_free(node->ae.xp_node);
448 kmem_cache_free(avc_node_cachep, node);
449 avc_cache_stats_incr(frees);
450 atomic_dec(&avc->avc_cache.active_nodes);
451}
452
453static void avc_node_replace(struct selinux_avc *avc,
454 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(&avc->avc_cache.active_nodes);
459}
460
461static inline int avc_reclaim_node(struct selinux_avc *avc)
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(&avc->avc_cache.lru_hint) &
471 (AVC_CACHE_SLOTS - 1);
472 head = &avc->avc_cache.slots[hvalue];
473 lock = &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(avc, 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 }
492out:
493 return ecx;
494}
495
496static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
497{
498 struct avc_node *node;
499
500 node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT);
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(&avc->avc_cache.active_nodes) >
508 avc->avc_cache_threshold)
509 avc_reclaim_node(avc);
510
511out:
512 return node;
513}
514
515static 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
523static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
524 u32 ssid, u32 tsid, u16 tclass)
525{
526 struct avc_node *node, *ret = NULL;
527 int hvalue;
528 struct hlist_head *head;
529
530 hvalue = avc_hash(ssid, tsid, tclass);
531 head = &avc->avc_cache.slots[hvalue];
532 hlist_for_each_entry_rcu(node, head, list) {
533 if (ssid == node->ae.ssid &&
534 tclass == node->ae.tclass &&
535 tsid == node->ae.tsid) {
536 ret = node;
537 break;
538 }
539 }
540
541 return ret;
542}
543
544/**
545 * avc_lookup - Look up an AVC entry.
546 * @ssid: source security identifier
547 * @tsid: target security identifier
548 * @tclass: target security class
549 *
550 * Look up an AVC entry that is valid for the
551 * (@ssid, @tsid), interpreting the permissions
552 * based on @tclass. If a valid AVC entry exists,
553 * then this function returns the avc_node.
554 * Otherwise, this function returns NULL.
555 */
556static struct avc_node *avc_lookup(struct selinux_avc *avc,
557 u32 ssid, u32 tsid, u16 tclass)
558{
559 struct avc_node *node;
560
561 avc_cache_stats_incr(lookups);
562 node = avc_search_node(avc, ssid, tsid, tclass);
563
564 if (node)
565 return node;
566
567 avc_cache_stats_incr(misses);
568 return NULL;
569}
570
571static int avc_latest_notif_update(struct selinux_avc *avc,
572 int seqno, int is_insert)
573{
574 int ret = 0;
575 static DEFINE_SPINLOCK(notif_lock);
576 unsigned long flag;
577
578 spin_lock_irqsave(¬if_lock, flag);
579 if (is_insert) {
580 if (seqno < avc->avc_cache.latest_notif) {
581 pr_warn("SELinux: avc: seqno %d < latest_notif %d\n",
582 seqno, avc->avc_cache.latest_notif);
583 ret = -EAGAIN;
584 }
585 } else {
586 if (seqno > avc->avc_cache.latest_notif)
587 avc->avc_cache.latest_notif = seqno;
588 }
589 spin_unlock_irqrestore(¬if_lock, flag);
590
591 return ret;
592}
593
594/**
595 * avc_insert - Insert an AVC entry.
596 * @ssid: source security identifier
597 * @tsid: target security identifier
598 * @tclass: target security class
599 * @avd: resulting av decision
600 * @xp_node: resulting extended permissions
601 *
602 * Insert an AVC entry for the SID pair
603 * (@ssid, @tsid) and class @tclass.
604 * The access vectors and the sequence number are
605 * normally provided by the security server in
606 * response to a security_compute_av() call. If the
607 * sequence number @avd->seqno is not less than the latest
608 * revocation notification, then the function copies
609 * the access vectors into a cache entry, returns
610 * avc_node inserted. Otherwise, this function returns NULL.
611 */
612static struct avc_node *avc_insert(struct selinux_avc *avc,
613 u32 ssid, u32 tsid, u16 tclass,
614 struct av_decision *avd,
615 struct avc_xperms_node *xp_node)
616{
617 struct avc_node *pos, *node = NULL;
618 int hvalue;
619 unsigned long flag;
620 spinlock_t *lock;
621 struct hlist_head *head;
622
623 if (avc_latest_notif_update(avc, avd->seqno, 1))
624 return NULL;
625
626 node = avc_alloc_node(avc);
627 if (!node)
628 return NULL;
629
630 avc_node_populate(node, ssid, tsid, tclass, avd);
631 if (avc_xperms_populate(node, xp_node)) {
632 avc_node_kill(avc, node);
633 return NULL;
634 }
635
636 hvalue = avc_hash(ssid, tsid, tclass);
637 head = &avc->avc_cache.slots[hvalue];
638 lock = &avc->avc_cache.slots_lock[hvalue];
639 spin_lock_irqsave(lock, flag);
640 hlist_for_each_entry(pos, head, list) {
641 if (pos->ae.ssid == ssid &&
642 pos->ae.tsid == tsid &&
643 pos->ae.tclass == tclass) {
644 avc_node_replace(avc, node, pos);
645 goto found;
646 }
647 }
648 hlist_add_head_rcu(&node->list, head);
649found:
650 spin_unlock_irqrestore(lock, flag);
651 return node;
652}
653
654/**
655 * avc_audit_pre_callback - SELinux specific information
656 * will be called by generic audit code
657 * @ab: the audit buffer
658 * @a: audit_data
659 */
660static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
661{
662 struct common_audit_data *ad = a;
663 struct selinux_audit_data *sad = ad->selinux_audit_data;
664 u32 av = sad->audited;
665 const char **perms;
666 int i, perm;
667
668 audit_log_format(ab, "avc: %s ", sad->denied ? "denied" : "granted");
669
670 if (av == 0) {
671 audit_log_format(ab, " null");
672 return;
673 }
674
675 perms = secclass_map[sad->tclass-1].perms;
676
677 audit_log_format(ab, " {");
678 i = 0;
679 perm = 1;
680 while (i < (sizeof(av) * 8)) {
681 if ((perm & av) && perms[i]) {
682 audit_log_format(ab, " %s", perms[i]);
683 av &= ~perm;
684 }
685 i++;
686 perm <<= 1;
687 }
688
689 if (av)
690 audit_log_format(ab, " 0x%x", av);
691
692 audit_log_format(ab, " } for ");
693}
694
695/**
696 * avc_audit_post_callback - SELinux specific information
697 * will be called by generic audit code
698 * @ab: the audit buffer
699 * @a: audit_data
700 */
701static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
702{
703 struct common_audit_data *ad = a;
704 struct selinux_audit_data *sad = ad->selinux_audit_data;
705 char *scontext;
706 u32 scontext_len;
707 int rc;
708
709 rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
710 &scontext_len);
711 if (rc)
712 audit_log_format(ab, " ssid=%d", sad->ssid);
713 else {
714 audit_log_format(ab, " scontext=%s", scontext);
715 kfree(scontext);
716 }
717
718 rc = security_sid_to_context(sad->state, sad->tsid, &scontext,
719 &scontext_len);
720 if (rc)
721 audit_log_format(ab, " tsid=%d", sad->tsid);
722 else {
723 audit_log_format(ab, " tcontext=%s", scontext);
724 kfree(scontext);
725 }
726
727 audit_log_format(ab, " tclass=%s", secclass_map[sad->tclass-1].name);
728
729 if (sad->denied)
730 audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
731
732 /* in case of invalid context report also the actual context string */
733 rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
734 &scontext_len);
735 if (!rc && scontext) {
736 if (scontext_len && scontext[scontext_len - 1] == '\0')
737 scontext_len--;
738 audit_log_format(ab, " srawcon=");
739 audit_log_n_untrustedstring(ab, scontext, scontext_len);
740 kfree(scontext);
741 }
742
743 rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
744 &scontext_len);
745 if (!rc && scontext) {
746 if (scontext_len && scontext[scontext_len - 1] == '\0')
747 scontext_len--;
748 audit_log_format(ab, " trawcon=");
749 audit_log_n_untrustedstring(ab, scontext, scontext_len);
750 kfree(scontext);
751 }
752}
753
754/* This is the slow part of avc audit with big stack footprint */
755noinline int slow_avc_audit(struct selinux_state *state,
756 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 sad.state = state;
779
780 a->selinux_audit_data = &sad;
781
782 common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
783 return 0;
784}
785
786/**
787 * avc_add_callback - Register a callback for security events.
788 * @callback: callback function
789 * @events: security events
790 *
791 * Register a callback function for events in the set @events.
792 * Returns %0 on success or -%ENOMEM if insufficient memory
793 * exists to add the callback.
794 */
795int __init avc_add_callback(int (*callback)(u32 event), u32 events)
796{
797 struct avc_callback_node *c;
798 int rc = 0;
799
800 c = kmalloc(sizeof(*c), GFP_KERNEL);
801 if (!c) {
802 rc = -ENOMEM;
803 goto out;
804 }
805
806 c->callback = callback;
807 c->events = events;
808 c->next = avc_callbacks;
809 avc_callbacks = c;
810out:
811 return rc;
812}
813
814/**
815 * avc_update_node Update an AVC entry
816 * @event : Updating event
817 * @perms : Permission mask bits
818 * @ssid,@tsid,@tclass : identifier of an AVC entry
819 * @seqno : sequence number when decision was made
820 * @xpd: extended_perms_decision to be added to the node
821 * @flags: the AVC_* flags, e.g. AVC_NONBLOCKING, AVC_EXTENDED_PERMS, or 0.
822 *
823 * if a valid AVC entry doesn't exist,this function returns -ENOENT.
824 * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
825 * otherwise, this function updates the AVC entry. The original AVC-entry object
826 * will release later by RCU.
827 */
828static int avc_update_node(struct selinux_avc *avc,
829 u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
830 u32 tsid, u16 tclass, u32 seqno,
831 struct extended_perms_decision *xpd,
832 u32 flags)
833{
834 int hvalue, rc = 0;
835 unsigned long flag;
836 struct avc_node *pos, *node, *orig = NULL;
837 struct hlist_head *head;
838 spinlock_t *lock;
839
840 /*
841 * If we are in a non-blocking code path, e.g. VFS RCU walk,
842 * then we must not add permissions to a cache entry
843 * because we will not audit the denial. Otherwise,
844 * during the subsequent blocking retry (e.g. VFS ref walk), we
845 * will find the permissions already granted in the cache entry
846 * and won't audit anything at all, leading to silent denials in
847 * permissive mode that only appear when in enforcing mode.
848 *
849 * See the corresponding handling of MAY_NOT_BLOCK in avc_audit()
850 * and selinux_inode_permission().
851 */
852 if (flags & AVC_NONBLOCKING)
853 return 0;
854
855 node = avc_alloc_node(avc);
856 if (!node) {
857 rc = -ENOMEM;
858 goto out;
859 }
860
861 /* Lock the target slot */
862 hvalue = avc_hash(ssid, tsid, tclass);
863
864 head = &avc->avc_cache.slots[hvalue];
865 lock = &avc->avc_cache.slots_lock[hvalue];
866
867 spin_lock_irqsave(lock, flag);
868
869 hlist_for_each_entry(pos, head, list) {
870 if (ssid == pos->ae.ssid &&
871 tsid == pos->ae.tsid &&
872 tclass == pos->ae.tclass &&
873 seqno == pos->ae.avd.seqno){
874 orig = pos;
875 break;
876 }
877 }
878
879 if (!orig) {
880 rc = -ENOENT;
881 avc_node_kill(avc, node);
882 goto out_unlock;
883 }
884
885 /*
886 * Copy and replace original node.
887 */
888
889 avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
890
891 if (orig->ae.xp_node) {
892 rc = avc_xperms_populate(node, orig->ae.xp_node);
893 if (rc) {
894 avc_node_kill(avc, node);
895 goto out_unlock;
896 }
897 }
898
899 switch (event) {
900 case AVC_CALLBACK_GRANT:
901 node->ae.avd.allowed |= perms;
902 if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
903 avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
904 break;
905 case AVC_CALLBACK_TRY_REVOKE:
906 case AVC_CALLBACK_REVOKE:
907 node->ae.avd.allowed &= ~perms;
908 break;
909 case AVC_CALLBACK_AUDITALLOW_ENABLE:
910 node->ae.avd.auditallow |= perms;
911 break;
912 case AVC_CALLBACK_AUDITALLOW_DISABLE:
913 node->ae.avd.auditallow &= ~perms;
914 break;
915 case AVC_CALLBACK_AUDITDENY_ENABLE:
916 node->ae.avd.auditdeny |= perms;
917 break;
918 case AVC_CALLBACK_AUDITDENY_DISABLE:
919 node->ae.avd.auditdeny &= ~perms;
920 break;
921 case AVC_CALLBACK_ADD_XPERMS:
922 avc_add_xperms_decision(node, xpd);
923 break;
924 }
925 avc_node_replace(avc, node, orig);
926out_unlock:
927 spin_unlock_irqrestore(lock, flag);
928out:
929 return rc;
930}
931
932/**
933 * avc_flush - Flush the cache
934 */
935static void avc_flush(struct selinux_avc *avc)
936{
937 struct hlist_head *head;
938 struct avc_node *node;
939 spinlock_t *lock;
940 unsigned long flag;
941 int i;
942
943 for (i = 0; i < AVC_CACHE_SLOTS; i++) {
944 head = &avc->avc_cache.slots[i];
945 lock = &avc->avc_cache.slots_lock[i];
946
947 spin_lock_irqsave(lock, flag);
948 /*
949 * With preemptable RCU, the outer spinlock does not
950 * prevent RCU grace periods from ending.
951 */
952 rcu_read_lock();
953 hlist_for_each_entry(node, head, list)
954 avc_node_delete(avc, node);
955 rcu_read_unlock();
956 spin_unlock_irqrestore(lock, flag);
957 }
958}
959
960/**
961 * avc_ss_reset - Flush the cache and revalidate migrated permissions.
962 * @seqno: policy sequence number
963 */
964int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
965{
966 struct avc_callback_node *c;
967 int rc = 0, tmprc;
968
969 avc_flush(avc);
970
971 for (c = avc_callbacks; c; c = c->next) {
972 if (c->events & AVC_CALLBACK_RESET) {
973 tmprc = c->callback(AVC_CALLBACK_RESET);
974 /* save the first error encountered for the return
975 value and continue processing the callbacks */
976 if (!rc)
977 rc = tmprc;
978 }
979 }
980
981 avc_latest_notif_update(avc, seqno, 0);
982 return rc;
983}
984
985/*
986 * Slow-path helper function for avc_has_perm_noaudit,
987 * when the avc_node lookup fails. We get called with
988 * the RCU read lock held, and need to return with it
989 * still held, but drop if for the security compute.
990 *
991 * Don't inline this, since it's the slow-path and just
992 * results in a bigger stack frame.
993 */
994static noinline
995struct avc_node *avc_compute_av(struct selinux_state *state,
996 u32 ssid, u32 tsid,
997 u16 tclass, struct av_decision *avd,
998 struct avc_xperms_node *xp_node)
999{
1000 rcu_read_unlock();
1001 INIT_LIST_HEAD(&xp_node->xpd_head);
1002 security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
1003 rcu_read_lock();
1004 return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
1005}
1006
1007static noinline int avc_denied(struct selinux_state *state,
1008 u32 ssid, u32 tsid,
1009 u16 tclass, u32 requested,
1010 u8 driver, u8 xperm, unsigned int flags,
1011 struct av_decision *avd)
1012{
1013 if (flags & AVC_STRICT)
1014 return -EACCES;
1015
1016 if (enforcing_enabled(state) &&
1017 !(avd->flags & AVD_FLAGS_PERMISSIVE))
1018 return -EACCES;
1019
1020 avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
1021 xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
1022 return 0;
1023}
1024
1025/*
1026 * The avc extended permissions logic adds an additional 256 bits of
1027 * permissions to an avc node when extended permissions for that node are
1028 * specified in the avtab. If the additional 256 permissions is not adequate,
1029 * as-is the case with ioctls, then multiple may be chained together and the
1030 * driver field is used to specify which set contains the permission.
1031 */
1032int avc_has_extended_perms(struct selinux_state *state,
1033 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1034 u8 driver, u8 xperm, struct common_audit_data *ad)
1035{
1036 struct avc_node *node;
1037 struct av_decision avd;
1038 u32 denied;
1039 struct extended_perms_decision local_xpd;
1040 struct extended_perms_decision *xpd = NULL;
1041 struct extended_perms_data allowed;
1042 struct extended_perms_data auditallow;
1043 struct extended_perms_data dontaudit;
1044 struct avc_xperms_node local_xp_node;
1045 struct avc_xperms_node *xp_node;
1046 int rc = 0, rc2;
1047
1048 xp_node = &local_xp_node;
1049 if (WARN_ON(!requested))
1050 return -EACCES;
1051
1052 rcu_read_lock();
1053
1054 node = avc_lookup(state->avc, ssid, tsid, tclass);
1055 if (unlikely(!node)) {
1056 node = avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
1057 } else {
1058 memcpy(&avd, &node->ae.avd, sizeof(avd));
1059 xp_node = node->ae.xp_node;
1060 }
1061 /* if extended permissions are not defined, only consider av_decision */
1062 if (!xp_node || !xp_node->xp.len)
1063 goto decision;
1064
1065 local_xpd.allowed = &allowed;
1066 local_xpd.auditallow = &auditallow;
1067 local_xpd.dontaudit = &dontaudit;
1068
1069 xpd = avc_xperms_decision_lookup(driver, xp_node);
1070 if (unlikely(!xpd)) {
1071 /*
1072 * Compute the extended_perms_decision only if the driver
1073 * is flagged
1074 */
1075 if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
1076 avd.allowed &= ~requested;
1077 goto decision;
1078 }
1079 rcu_read_unlock();
1080 security_compute_xperms_decision(state, ssid, tsid, tclass,
1081 driver, &local_xpd);
1082 rcu_read_lock();
1083 avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
1084 driver, xperm, ssid, tsid, tclass, avd.seqno,
1085 &local_xpd, 0);
1086 } else {
1087 avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
1088 }
1089 xpd = &local_xpd;
1090
1091 if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
1092 avd.allowed &= ~requested;
1093
1094decision:
1095 denied = requested & ~(avd.allowed);
1096 if (unlikely(denied))
1097 rc = avc_denied(state, ssid, tsid, tclass, requested,
1098 driver, xperm, AVC_EXTENDED_PERMS, &avd);
1099
1100 rcu_read_unlock();
1101
1102 rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
1103 &avd, xpd, xperm, rc, ad);
1104 if (rc2)
1105 return rc2;
1106 return rc;
1107}
1108
1109/**
1110 * avc_has_perm_noaudit - Check permissions but perform no auditing.
1111 * @ssid: source security identifier
1112 * @tsid: target security identifier
1113 * @tclass: target security class
1114 * @requested: requested permissions, interpreted based on @tclass
1115 * @flags: AVC_STRICT, AVC_NONBLOCKING, or 0
1116 * @avd: access vector decisions
1117 *
1118 * Check the AVC to determine whether the @requested permissions are granted
1119 * for the SID pair (@ssid, @tsid), interpreting the permissions
1120 * based on @tclass, and call the security server on a cache miss to obtain
1121 * a new decision and add it to the cache. Return a copy of the decisions
1122 * in @avd. Return %0 if all @requested permissions are granted,
1123 * -%EACCES if any permissions are denied, or another -errno upon
1124 * other errors. This function is typically called by avc_has_perm(),
1125 * but may also be called directly to separate permission checking from
1126 * auditing, e.g. in cases where a lock must be held for the check but
1127 * should be released for the auditing.
1128 */
1129inline int avc_has_perm_noaudit(struct selinux_state *state,
1130 u32 ssid, u32 tsid,
1131 u16 tclass, u32 requested,
1132 unsigned int flags,
1133 struct av_decision *avd)
1134{
1135 struct avc_node *node;
1136 struct avc_xperms_node xp_node;
1137 int rc = 0;
1138 u32 denied;
1139
1140 if (WARN_ON(!requested))
1141 return -EACCES;
1142
1143 rcu_read_lock();
1144
1145 node = avc_lookup(state->avc, ssid, tsid, tclass);
1146 if (unlikely(!node))
1147 node = avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
1148 else
1149 memcpy(avd, &node->ae.avd, sizeof(*avd));
1150
1151 denied = requested & ~(avd->allowed);
1152 if (unlikely(denied))
1153 rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
1154 flags, avd);
1155
1156 rcu_read_unlock();
1157 return rc;
1158}
1159
1160/**
1161 * avc_has_perm - Check permissions and perform any appropriate auditing.
1162 * @ssid: source security identifier
1163 * @tsid: target security identifier
1164 * @tclass: target security class
1165 * @requested: requested permissions, interpreted based on @tclass
1166 * @auditdata: auxiliary audit data
1167 *
1168 * Check the AVC to determine whether the @requested permissions are granted
1169 * for the SID pair (@ssid, @tsid), interpreting the permissions
1170 * based on @tclass, and call the security server on a cache miss to obtain
1171 * a new decision and add it to the cache. Audit the granting or denial of
1172 * permissions in accordance with the policy. Return %0 if all @requested
1173 * permissions are granted, -%EACCES if any permissions are denied, or
1174 * another -errno upon other errors.
1175 */
1176int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
1177 u32 requested, struct common_audit_data *auditdata)
1178{
1179 struct av_decision avd;
1180 int rc, rc2;
1181
1182 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
1183 &avd);
1184
1185 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1186 auditdata, 0);
1187 if (rc2)
1188 return rc2;
1189 return rc;
1190}
1191
1192int avc_has_perm_flags(struct selinux_state *state,
1193 u32 ssid, u32 tsid, u16 tclass, u32 requested,
1194 struct common_audit_data *auditdata,
1195 int flags)
1196{
1197 struct av_decision avd;
1198 int rc, rc2;
1199
1200 rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested,
1201 (flags & MAY_NOT_BLOCK) ? AVC_NONBLOCKING : 0,
1202 &avd);
1203
1204 rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
1205 auditdata, flags);
1206 if (rc2)
1207 return rc2;
1208 return rc;
1209}
1210
1211u32 avc_policy_seqno(struct selinux_state *state)
1212{
1213 return state->avc->avc_cache.latest_notif;
1214}
1215
1216void avc_disable(void)
1217{
1218 /*
1219 * If you are looking at this because you have realized that we are
1220 * not destroying the avc_node_cachep it might be easy to fix, but
1221 * I don't know the memory barrier semantics well enough to know. It's
1222 * possible that some other task dereferenced security_ops when
1223 * it still pointed to selinux operations. If that is the case it's
1224 * possible that it is about to use the avc and is about to need the
1225 * avc_node_cachep. I know I could wrap the security.c security_ops call
1226 * in an rcu_lock, but seriously, it's not worth it. Instead I just flush
1227 * the cache and get that memory back.
1228 */
1229 if (avc_node_cachep) {
1230 avc_flush(selinux_state.avc);
1231 /* kmem_cache_destroy(avc_node_cachep); */
1232 }
1233}