1 // SPDX-License-Identifier: GPL-2.0
2 #include "audit.h"
3 #include <linux/fsnotify_backend.h>
4 #include <linux/namei.h>
5 #include <linux/mount.h>
6 #include <linux/kthread.h>
7 #include <linux/refcount.h>
8 #include <linux/slab.h>
9
10 struct audit_tree;
11 struct audit_chunk;
12
13 struct audit_tree {
14 refcount_t count;
15 int goner;
16 struct audit_chunk *root;
17 struct list_head chunks;
18 struct list_head rules;
19 struct list_head list;
20 struct list_head same_root;
21 struct rcu_head head;
22 char pathname[];
23 };
24
25 struct audit_chunk {
26 struct list_head hash;
27 unsigned long key;
28 struct fsnotify_mark *mark;
29 struct list_head trees; /* with root here */
30 int count;
31 atomic_long_t refs;
32 struct rcu_head head;
33 struct audit_node {
34 struct list_head list;
35 struct audit_tree *owner;
36 unsigned index; /* index; upper bit indicates 'will prune' */
37 } owners[] __counted_by(count);
38 };
39
40 struct audit_tree_mark {
41 struct fsnotify_mark mark;
42 struct audit_chunk *chunk;
43 };
44
45 static LIST_HEAD(tree_list);
46 static LIST_HEAD(prune_list);
47 static struct task_struct *prune_thread;
48
49 /*
50 * One struct chunk is attached to each inode of interest through
51 * audit_tree_mark (fsnotify mark). We replace struct chunk on tagging /
52 * untagging, the mark is stable as long as there is chunk attached. The
53 * association between mark and chunk is protected by hash_lock and
54 * audit_tree_group->mark_mutex. Thus as long as we hold
55 * audit_tree_group->mark_mutex and check that the mark is alive by
56 * FSNOTIFY_MARK_FLAG_ATTACHED flag check, we are sure the mark points to
57 * the current chunk.
58 *
59 * Rules have pointer to struct audit_tree.
60 * Rules have struct list_head rlist forming a list of rules over
61 * the same tree.
62 * References to struct chunk are collected at audit_inode{,_child}()
63 * time and used in AUDIT_TREE rule matching.
64 * These references are dropped at the same time we are calling
65 * audit_free_names(), etc.
66 *
67 * Cyclic lists galore:
68 * tree.chunks anchors chunk.owners[].list hash_lock
69 * tree.rules anchors rule.rlist audit_filter_mutex
70 * chunk.trees anchors tree.same_root hash_lock
71 * chunk.hash is a hash with middle bits of watch.inode as
72 * a hash function. RCU, hash_lock
73 *
74 * tree is refcounted; one reference for "some rules on rules_list refer to
75 * it", one for each chunk with pointer to it.
76 *
77 * chunk is refcounted by embedded .refs. Mark associated with the chunk holds
78 * one chunk reference. This reference is dropped either when a mark is going
79 * to be freed (corresponding inode goes away) or when chunk attached to the
80 * mark gets replaced. This reference must be dropped using
81 * audit_mark_put_chunk() to make sure the reference is dropped only after RCU
82 * grace period as it protects RCU readers of the hash table.
83 *
84 * node.index allows to get from node.list to containing chunk.
85 * MSB of that sucker is stolen to mark taggings that we might have to
86 * revert - several operations have very unpleasant cleanup logics and
87 * that makes a difference. Some.
88 */
89
90 static struct fsnotify_group *audit_tree_group __ro_after_init;
91 static struct kmem_cache *audit_tree_mark_cachep __ro_after_init;
92
93 static struct audit_tree *alloc_tree(const char *s)
94 {
95 struct audit_tree *tree;
96
97 tree = kmalloc(struct_size(tree, pathname, strlen(s) + 1), GFP_KERNEL);
98 if (tree) {
99 refcount_set(&tree->count, 1);
100 tree->goner = 0;
101 INIT_LIST_HEAD(&tree->chunks);
102 INIT_LIST_HEAD(&tree->rules);
103 INIT_LIST_HEAD(&tree->list);
104 INIT_LIST_HEAD(&tree->same_root);
105 tree->root = NULL;
106 strcpy(tree->pathname, s);
107 }
108 return tree;
109 }
110
111 static inline void get_tree(struct audit_tree *tree)
112 {
113 refcount_inc(&tree->count);
114 }
115
116 static inline void put_tree(struct audit_tree *tree)
117 {
118 if (refcount_dec_and_test(&tree->count))
119 kfree_rcu(tree, head);
120 }
121
122 /* to avoid bringing the entire thing in audit.h */
123 const char *audit_tree_path(struct audit_tree *tree)
124 {
125 return tree->pathname;
126 }
127
128 static void free_chunk(struct audit_chunk *chunk)
129 {
130 int i;
131
132 for (i = 0; i < chunk->count; i++) {
133 if (chunk->owners[i].owner)
134 put_tree(chunk->owners[i].owner);
135 }
136 kfree(chunk);
137 }
138
139 void audit_put_chunk(struct audit_chunk *chunk)
140 {
141 if (atomic_long_dec_and_test(&chunk->refs))
142 free_chunk(chunk);
143 }
144
145 static void __put_chunk(struct rcu_head *rcu)
146 {
147 struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
148 audit_put_chunk(chunk);
149 }
150
151 /*
152 * Drop reference to the chunk that was held by the mark. This is the reference
153 * that gets dropped after we've removed the chunk from the hash table and we
154 * use it to make sure chunk cannot be freed before RCU grace period expires.
155 */
156 static void audit_mark_put_chunk(struct audit_chunk *chunk)
157 {
158 call_rcu(&chunk->head, __put_chunk);
159 }
160
161 static inline struct audit_tree_mark *audit_mark(struct fsnotify_mark *mark)
162 {
163 return container_of(mark, struct audit_tree_mark, mark);
164 }
165
166 static struct audit_chunk *mark_chunk(struct fsnotify_mark *mark)
167 {
168 return audit_mark(mark)->chunk;
169 }
170
171 static void audit_tree_destroy_watch(struct fsnotify_mark *mark)
172 {
173 kmem_cache_free(audit_tree_mark_cachep, audit_mark(mark));
174 }
175
176 static struct fsnotify_mark *alloc_mark(void)
177 {
178 struct audit_tree_mark *amark;
179
180 amark = kmem_cache_zalloc(audit_tree_mark_cachep, GFP_KERNEL);
181 if (!amark)
182 return NULL;
183 fsnotify_init_mark(&amark->mark, audit_tree_group);
184 amark->mark.mask = FS_IN_IGNORED;
185 return &amark->mark;
186 }
187
188 static struct audit_chunk *alloc_chunk(int count)
189 {
190 struct audit_chunk *chunk;
191 int i;
192
193 chunk = kzalloc(struct_size(chunk, owners, count), GFP_KERNEL);
194 if (!chunk)
195 return NULL;
196
197 INIT_LIST_HEAD(&chunk->hash);
198 INIT_LIST_HEAD(&chunk->trees);
199 chunk->count = count;
200 atomic_long_set(&chunk->refs, 1);
201 for (i = 0; i < count; i++) {
202 INIT_LIST_HEAD(&chunk->owners[i].list);
203 chunk->owners[i].index = i;
204 }
205 return chunk;
206 }
207
208 enum {HASH_SIZE = 128};
209 static struct list_head chunk_hash_heads[HASH_SIZE];
210 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
211
212 /* Function to return search key in our hash from inode. */
213 static unsigned long inode_to_key(const struct inode *inode)
214 {
215 /* Use address pointed to by connector->obj as the key */
216 return (unsigned long)&inode->i_fsnotify_marks;
217 }
218
219 static inline struct list_head *chunk_hash(unsigned long key)
220 {
221 unsigned long n = key / L1_CACHE_BYTES;
222 return chunk_hash_heads + n % HASH_SIZE;
223 }
224
225 /* hash_lock & mark->group->mark_mutex is held by caller */
226 static void insert_hash(struct audit_chunk *chunk)
227 {
228 struct list_head *list;
229
230 /*
231 * Make sure chunk is fully initialized before making it visible in the
232 * hash. Pairs with a data dependency barrier in READ_ONCE() in
233 * audit_tree_lookup().
234 */
235 smp_wmb();
236 WARN_ON_ONCE(!chunk->key);
237 list = chunk_hash(chunk->key);
238 list_add_rcu(&chunk->hash, list);
239 }
240
241 /* called under rcu_read_lock */
242 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
243 {
244 unsigned long key = inode_to_key(inode);
245 struct list_head *list = chunk_hash(key);
246 struct audit_chunk *p;
247
248 list_for_each_entry_rcu(p, list, hash) {
249 /*
250 * We use a data dependency barrier in READ_ONCE() to make sure
251 * the chunk we see is fully initialized.
252 */
253 if (READ_ONCE(p->key) == key) {
254 atomic_long_inc(&p->refs);
255 return p;
256 }
257 }
258 return NULL;
259 }
260
261 bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
262 {
263 int n;
264 for (n = 0; n < chunk->count; n++)
265 if (chunk->owners[n].owner == tree)
266 return true;
267 return false;
268 }
269
270 /* tagging and untagging inodes with trees */
271
272 static struct audit_chunk *find_chunk(struct audit_node *p)
273 {
274 int index = p->index & ~(1U<<31);
275 p -= index;
276 return container_of(p, struct audit_chunk, owners[0]);
277 }
278
279 static void replace_mark_chunk(struct fsnotify_mark *mark,
280 struct audit_chunk *chunk)
281 {
282 struct audit_chunk *old;
283
284 assert_spin_locked(&hash_lock);
285 old = mark_chunk(mark);
286 audit_mark(mark)->chunk = chunk;
287 if (chunk)
288 chunk->mark = mark;
289 if (old)
290 old->mark = NULL;
291 }
292
293 static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old)
294 {
295 struct audit_tree *owner;
296 int i, j;
297
298 new->key = old->key;
299 list_splice_init(&old->trees, &new->trees);
300 list_for_each_entry(owner, &new->trees, same_root)
301 owner->root = new;
302 for (i = j = 0; j < old->count; i++, j++) {
303 if (!old->owners[j].owner) {
304 i--;
305 continue;
306 }
307 owner = old->owners[j].owner;
308 new->owners[i].owner = owner;
309 new->owners[i].index = old->owners[j].index - j + i;
310 if (!owner) /* result of earlier fallback */
311 continue;
312 get_tree(owner);
313 list_replace_init(&old->owners[j].list, &new->owners[i].list);
314 }
315 replace_mark_chunk(old->mark, new);
316 /*
317 * Make sure chunk is fully initialized before making it visible in the
318 * hash. Pairs with a data dependency barrier in READ_ONCE() in
319 * audit_tree_lookup().
320 */
321 smp_wmb();
322 list_replace_rcu(&old->hash, &new->hash);
323 }
324
325 static void remove_chunk_node(struct audit_chunk *chunk, struct audit_node *p)
326 {
327 struct audit_tree *owner = p->owner;
328
329 if (owner->root == chunk) {
330 list_del_init(&owner->same_root);
331 owner->root = NULL;
332 }
333 list_del_init(&p->list);
334 p->owner = NULL;
335 put_tree(owner);
336 }
337
338 static int chunk_count_trees(struct audit_chunk *chunk)
339 {
340 int i;
341 int ret = 0;
342
343 for (i = 0; i < chunk->count; i++)
344 if (chunk->owners[i].owner)
345 ret++;
346 return ret;
347 }
348
349 static void untag_chunk(struct audit_chunk *chunk, struct fsnotify_mark *mark)
350 {
351 struct audit_chunk *new;
352 int size;
353
354 fsnotify_group_lock(audit_tree_group);
355 /*
356 * mark_mutex stabilizes chunk attached to the mark so we can check
357 * whether it didn't change while we've dropped hash_lock.
358 */
359 if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) ||
360 mark_chunk(mark) != chunk)
361 goto out_mutex;
362
363 size = chunk_count_trees(chunk);
364 if (!size) {
365 spin_lock(&hash_lock);
366 list_del_init(&chunk->trees);
367 list_del_rcu(&chunk->hash);
368 replace_mark_chunk(mark, NULL);
369 spin_unlock(&hash_lock);
370 fsnotify_detach_mark(mark);
371 fsnotify_group_unlock(audit_tree_group);
372 audit_mark_put_chunk(chunk);
373 fsnotify_free_mark(mark);
374 return;
375 }
376
377 new = alloc_chunk(size);
378 if (!new)
379 goto out_mutex;
380
381 spin_lock(&hash_lock);
382 /*
383 * This has to go last when updating chunk as once replace_chunk() is
384 * called, new RCU readers can see the new chunk.
385 */
386 replace_chunk(new, chunk);
387 spin_unlock(&hash_lock);
388 fsnotify_group_unlock(audit_tree_group);
389 audit_mark_put_chunk(chunk);
390 return;
391
392 out_mutex:
393 fsnotify_group_unlock(audit_tree_group);
394 }
395
396 /* Call with group->mark_mutex held, releases it */
397 static int create_chunk(struct inode *inode, struct audit_tree *tree)
398 {
399 struct fsnotify_mark *mark;
400 struct audit_chunk *chunk = alloc_chunk(1);
401
402 if (!chunk) {
403 fsnotify_group_unlock(audit_tree_group);
404 return -ENOMEM;
405 }
406
407 mark = alloc_mark();
408 if (!mark) {
409 fsnotify_group_unlock(audit_tree_group);
410 kfree(chunk);
411 return -ENOMEM;
412 }
413
414 if (fsnotify_add_inode_mark_locked(mark, inode, 0)) {
415 fsnotify_group_unlock(audit_tree_group);
416 fsnotify_put_mark(mark);
417 kfree(chunk);
418 return -ENOSPC;
419 }
420
421 spin_lock(&hash_lock);
422 if (tree->goner) {
423 spin_unlock(&hash_lock);
424 fsnotify_detach_mark(mark);
425 fsnotify_group_unlock(audit_tree_group);
426 fsnotify_free_mark(mark);
427 fsnotify_put_mark(mark);
428 kfree(chunk);
429 return 0;
430 }
431 replace_mark_chunk(mark, chunk);
432 chunk->owners[0].index = (1U << 31);
433 chunk->owners[0].owner = tree;
434 get_tree(tree);
435 list_add(&chunk->owners[0].list, &tree->chunks);
436 if (!tree->root) {
437 tree->root = chunk;
438 list_add(&tree->same_root, &chunk->trees);
439 }
440 chunk->key = inode_to_key(inode);
441 /*
442 * Inserting into the hash table has to go last as once we do that RCU
443 * readers can see the chunk.
444 */
445 insert_hash(chunk);
446 spin_unlock(&hash_lock);
447 fsnotify_group_unlock(audit_tree_group);
448 /*
449 * Drop our initial reference. When mark we point to is getting freed,
450 * we get notification through ->freeing_mark callback and cleanup
451 * chunk pointing to this mark.
452 */
453 fsnotify_put_mark(mark);
454 return 0;
455 }
456
457 /* the first tagged inode becomes root of tree */
458 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
459 {
460 struct fsnotify_mark *mark;
461 struct audit_chunk *chunk, *old;
462 struct audit_node *p;
463 int n;
464
465 fsnotify_group_lock(audit_tree_group);
466 mark = fsnotify_find_inode_mark(inode, audit_tree_group);
467 if (!mark)
468 return create_chunk(inode, tree);
469
470 /*
471 * Found mark is guaranteed to be attached and mark_mutex protects mark
472 * from getting detached and thus it makes sure there is chunk attached
473 * to the mark.
474 */
475 /* are we already there? */
476 spin_lock(&hash_lock);
477 old = mark_chunk(mark);
478 for (n = 0; n < old->count; n++) {
479 if (old->owners[n].owner == tree) {
480 spin_unlock(&hash_lock);
481 fsnotify_group_unlock(audit_tree_group);
482 fsnotify_put_mark(mark);
483 return 0;
484 }
485 }
486 spin_unlock(&hash_lock);
487
488 chunk = alloc_chunk(old->count + 1);
489 if (!chunk) {
490 fsnotify_group_unlock(audit_tree_group);
491 fsnotify_put_mark(mark);
492 return -ENOMEM;
493 }
494
495 spin_lock(&hash_lock);
496 if (tree->goner) {
497 spin_unlock(&hash_lock);
498 fsnotify_group_unlock(audit_tree_group);
499 fsnotify_put_mark(mark);
500 kfree(chunk);
501 return 0;
502 }
503 p = &chunk->owners[chunk->count - 1];
504 p->index = (chunk->count - 1) | (1U<<31);
505 p->owner = tree;
506 get_tree(tree);
507 list_add(&p->list, &tree->chunks);
508 if (!tree->root) {
509 tree->root = chunk;
510 list_add(&tree->same_root, &chunk->trees);
511 }
512 /*
513 * This has to go last when updating chunk as once replace_chunk() is
514 * called, new RCU readers can see the new chunk.
515 */
516 replace_chunk(chunk, old);
517 spin_unlock(&hash_lock);
518 fsnotify_group_unlock(audit_tree_group);
519 fsnotify_put_mark(mark); /* pair to fsnotify_find_mark */
520 audit_mark_put_chunk(old);
521
522 return 0;
523 }
524
525 static void audit_tree_log_remove_rule(struct audit_context *context,
526 struct audit_krule *rule)
527 {
528 struct audit_buffer *ab;
529
530 if (!audit_enabled)
531 return;
532 ab = audit_log_start(context, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
533 if (unlikely(!ab))
534 return;
535 audit_log_format(ab, "op=remove_rule dir=");
536 audit_log_untrustedstring(ab, rule->tree->pathname);
537 audit_log_key(ab, rule->filterkey);
538 audit_log_format(ab, " list=%d res=1", rule->listnr);
539 audit_log_end(ab);
540 }
541
542 static void kill_rules(struct audit_context *context, struct audit_tree *tree)
543 {
544 struct audit_krule *rule, *next;
545 struct audit_entry *entry;
546
547 list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
548 entry = container_of(rule, struct audit_entry, rule);
549
550 list_del_init(&rule->rlist);
551 if (rule->tree) {
552 /* not a half-baked one */
553 audit_tree_log_remove_rule(context, rule);
554 if (entry->rule.exe)
555 audit_remove_mark(entry->rule.exe);
556 rule->tree = NULL;
557 list_del_rcu(&entry->list);
558 list_del(&entry->rule.list);
559 call_rcu(&entry->rcu, audit_free_rule_rcu);
560 }
561 }
562 }
563
564 /*
565 * Remove tree from chunks. If 'tagged' is set, remove tree only from tagged
566 * chunks. The function expects tagged chunks are all at the beginning of the
567 * chunks list.
568 */
569 static void prune_tree_chunks(struct audit_tree *victim, bool tagged)
570 {
571 spin_lock(&hash_lock);
572 while (!list_empty(&victim->chunks)) {
573 struct audit_node *p;
574 struct audit_chunk *chunk;
575 struct fsnotify_mark *mark;
576
577 p = list_first_entry(&victim->chunks, struct audit_node, list);
578 /* have we run out of marked? */
579 if (tagged && !(p->index & (1U<<31)))
580 break;
581 chunk = find_chunk(p);
582 mark = chunk->mark;
583 remove_chunk_node(chunk, p);
584 /* Racing with audit_tree_freeing_mark()? */
585 if (!mark)
586 continue;
587 fsnotify_get_mark(mark);
588 spin_unlock(&hash_lock);
589
590 untag_chunk(chunk, mark);
591 fsnotify_put_mark(mark);
592
593 spin_lock(&hash_lock);
594 }
595 spin_unlock(&hash_lock);
596 }
597
598 /*
599 * finish killing struct audit_tree
600 */
601 static void prune_one(struct audit_tree *victim)
602 {
603 prune_tree_chunks(victim, false);
604 put_tree(victim);
605 }
606
607 /* trim the uncommitted chunks from tree */
608
609 static void trim_marked(struct audit_tree *tree)
610 {
611 struct list_head *p, *q;
612 spin_lock(&hash_lock);
613 if (tree->goner) {
614 spin_unlock(&hash_lock);
615 return;
616 }
617 /* reorder */
618 for (p = tree->chunks.next; p != &tree->chunks; p = q) {
619 struct audit_node *node = list_entry(p, struct audit_node, list);
620 q = p->next;
621 if (node->index & (1U<<31)) {
622 list_del_init(p);
623 list_add(p, &tree->chunks);
624 }
625 }
626 spin_unlock(&hash_lock);
627
628 prune_tree_chunks(tree, true);
629
630 spin_lock(&hash_lock);
631 if (!tree->root && !tree->goner) {
632 tree->goner = 1;
633 spin_unlock(&hash_lock);
634 mutex_lock(&audit_filter_mutex);
635 kill_rules(audit_context(), tree);
636 list_del_init(&tree->list);
637 mutex_unlock(&audit_filter_mutex);
638 prune_one(tree);
639 } else {
640 spin_unlock(&hash_lock);
641 }
642 }
643
644 static void audit_schedule_prune(void);
645
646 /* called with audit_filter_mutex */
647 int audit_remove_tree_rule(struct audit_krule *rule)
648 {
649 struct audit_tree *tree;
650 tree = rule->tree;
651 if (tree) {
652 spin_lock(&hash_lock);
653 list_del_init(&rule->rlist);
654 if (list_empty(&tree->rules) && !tree->goner) {
655 tree->root = NULL;
656 list_del_init(&tree->same_root);
657 tree->goner = 1;
658 list_move(&tree->list, &prune_list);
659 rule->tree = NULL;
660 spin_unlock(&hash_lock);
661 audit_schedule_prune();
662 return 1;
663 }
664 rule->tree = NULL;
665 spin_unlock(&hash_lock);
666 return 1;
667 }
668 return 0;
669 }
670
671 static int compare_root(struct vfsmount *mnt, void *arg)
672 {
673 return inode_to_key(d_backing_inode(mnt->mnt_root)) ==
674 (unsigned long)arg;
675 }
676
677 void audit_trim_trees(void)
678 {
679 struct list_head cursor;
680
681 mutex_lock(&audit_filter_mutex);
682 list_add(&cursor, &tree_list);
683 while (cursor.next != &tree_list) {
684 struct audit_tree *tree;
685 struct path path;
686 struct vfsmount *root_mnt;
687 struct audit_node *node;
688 int err;
689
690 tree = container_of(cursor.next, struct audit_tree, list);
691 get_tree(tree);
692 list_move(&cursor, &tree->list);
693 mutex_unlock(&audit_filter_mutex);
694
695 err = kern_path(tree->pathname, 0, &path);
696 if (err)
697 goto skip_it;
698
699 root_mnt = collect_mounts(&path);
700 path_put(&path);
701 if (IS_ERR(root_mnt))
702 goto skip_it;
703
704 spin_lock(&hash_lock);
705 list_for_each_entry(node, &tree->chunks, list) {
706 struct audit_chunk *chunk = find_chunk(node);
707 /* this could be NULL if the watch is dying else where... */
708 node->index |= 1U<<31;
709 if (iterate_mounts(compare_root,
710 (void *)(chunk->key),
711 root_mnt))
712 node->index &= ~(1U<<31);
713 }
714 spin_unlock(&hash_lock);
715 trim_marked(tree);
716 drop_collected_mounts(root_mnt);
717 skip_it:
718 put_tree(tree);
719 mutex_lock(&audit_filter_mutex);
720 }
721 list_del(&cursor);
722 mutex_unlock(&audit_filter_mutex);
723 }
724
725 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
726 {
727
728 if (pathname[0] != '/' ||
729 (rule->listnr != AUDIT_FILTER_EXIT &&
730 rule->listnr != AUDIT_FILTER_URING_EXIT) ||
731 op != Audit_equal ||
732 rule->inode_f || rule->watch || rule->tree)
733 return -EINVAL;
734 rule->tree = alloc_tree(pathname);
735 if (!rule->tree)
736 return -ENOMEM;
737 return 0;
738 }
739
740 void audit_put_tree(struct audit_tree *tree)
741 {
742 put_tree(tree);
743 }
744
745 static int tag_mount(struct vfsmount *mnt, void *arg)
746 {
747 return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
748 }
749
750 /*
751 * That gets run when evict_chunk() ends up needing to kill audit_tree.
752 * Runs from a separate thread.
753 */
754 static int prune_tree_thread(void *unused)
755 {
756 for (;;) {
757 if (list_empty(&prune_list)) {
758 set_current_state(TASK_INTERRUPTIBLE);
759 schedule();
760 }
761
762 audit_ctl_lock();
763 mutex_lock(&audit_filter_mutex);
764
765 while (!list_empty(&prune_list)) {
766 struct audit_tree *victim;
767
768 victim = list_entry(prune_list.next,
769 struct audit_tree, list);
770 list_del_init(&victim->list);
771
772 mutex_unlock(&audit_filter_mutex);
773
774 prune_one(victim);
775
776 mutex_lock(&audit_filter_mutex);
777 }
778
779 mutex_unlock(&audit_filter_mutex);
780 audit_ctl_unlock();
781 }
782 return 0;
783 }
784
785 static int audit_launch_prune(void)
786 {
787 if (prune_thread)
788 return 0;
789 prune_thread = kthread_run(prune_tree_thread, NULL,
790 "audit_prune_tree");
791 if (IS_ERR(prune_thread)) {
792 pr_err("cannot start thread audit_prune_tree");
793 prune_thread = NULL;
794 return -ENOMEM;
795 }
796 return 0;
797 }
798
799 /* called with audit_filter_mutex */
800 int audit_add_tree_rule(struct audit_krule *rule)
801 {
802 struct audit_tree *seed = rule->tree, *tree;
803 struct path path;
804 struct vfsmount *mnt;
805 int err;
806
807 rule->tree = NULL;
808 list_for_each_entry(tree, &tree_list, list) {
809 if (!strcmp(seed->pathname, tree->pathname)) {
810 put_tree(seed);
811 rule->tree = tree;
812 list_add(&rule->rlist, &tree->rules);
813 return 0;
814 }
815 }
816 tree = seed;
817 list_add(&tree->list, &tree_list);
818 list_add(&rule->rlist, &tree->rules);
819 /* do not set rule->tree yet */
820 mutex_unlock(&audit_filter_mutex);
821
822 if (unlikely(!prune_thread)) {
823 err = audit_launch_prune();
824 if (err)
825 goto Err;
826 }
827
828 err = kern_path(tree->pathname, 0, &path);
829 if (err)
830 goto Err;
831 mnt = collect_mounts(&path);
832 path_put(&path);
833 if (IS_ERR(mnt)) {
834 err = PTR_ERR(mnt);
835 goto Err;
836 }
837
838 get_tree(tree);
839 err = iterate_mounts(tag_mount, tree, mnt);
840 drop_collected_mounts(mnt);
841
842 if (!err) {
843 struct audit_node *node;
844 spin_lock(&hash_lock);
845 list_for_each_entry(node, &tree->chunks, list)
846 node->index &= ~(1U<<31);
847 spin_unlock(&hash_lock);
848 } else {
849 trim_marked(tree);
850 goto Err;
851 }
852
853 mutex_lock(&audit_filter_mutex);
854 if (list_empty(&rule->rlist)) {
855 put_tree(tree);
856 return -ENOENT;
857 }
858 rule->tree = tree;
859 put_tree(tree);
860
861 return 0;
862 Err:
863 mutex_lock(&audit_filter_mutex);
864 list_del_init(&tree->list);
865 list_del_init(&tree->rules);
866 put_tree(tree);
867 return err;
868 }
869
870 int audit_tag_tree(char *old, char *new)
871 {
872 struct list_head cursor, barrier;
873 int failed = 0;
874 struct path path1, path2;
875 struct vfsmount *tagged;
876 int err;
877
878 err = kern_path(new, 0, &path2);
879 if (err)
880 return err;
881 tagged = collect_mounts(&path2);
882 path_put(&path2);
883 if (IS_ERR(tagged))
884 return PTR_ERR(tagged);
885
886 err = kern_path(old, 0, &path1);
887 if (err) {
888 drop_collected_mounts(tagged);
889 return err;
890 }
891
892 mutex_lock(&audit_filter_mutex);
893 list_add(&barrier, &tree_list);
894 list_add(&cursor, &barrier);
895
896 while (cursor.next != &tree_list) {
897 struct audit_tree *tree;
898 int good_one = 0;
899
900 tree = container_of(cursor.next, struct audit_tree, list);
901 get_tree(tree);
902 list_move(&cursor, &tree->list);
903 mutex_unlock(&audit_filter_mutex);
904
905 err = kern_path(tree->pathname, 0, &path2);
906 if (!err) {
907 good_one = path_is_under(&path1, &path2);
908 path_put(&path2);
909 }
910
911 if (!good_one) {
912 put_tree(tree);
913 mutex_lock(&audit_filter_mutex);
914 continue;
915 }
916
917 failed = iterate_mounts(tag_mount, tree, tagged);
918 if (failed) {
919 put_tree(tree);
920 mutex_lock(&audit_filter_mutex);
921 break;
922 }
923
924 mutex_lock(&audit_filter_mutex);
925 spin_lock(&hash_lock);
926 if (!tree->goner) {
927 list_move(&tree->list, &tree_list);
928 }
929 spin_unlock(&hash_lock);
930 put_tree(tree);
931 }
932
933 while (barrier.prev != &tree_list) {
934 struct audit_tree *tree;
935
936 tree = container_of(barrier.prev, struct audit_tree, list);
937 get_tree(tree);
938 list_move(&tree->list, &barrier);
939 mutex_unlock(&audit_filter_mutex);
940
941 if (!failed) {
942 struct audit_node *node;
943 spin_lock(&hash_lock);
944 list_for_each_entry(node, &tree->chunks, list)
945 node->index &= ~(1U<<31);
946 spin_unlock(&hash_lock);
947 } else {
948 trim_marked(tree);
949 }
950
951 put_tree(tree);
952 mutex_lock(&audit_filter_mutex);
953 }
954 list_del(&barrier);
955 list_del(&cursor);
956 mutex_unlock(&audit_filter_mutex);
957 path_put(&path1);
958 drop_collected_mounts(tagged);
959 return failed;
960 }
961
962
963 static void audit_schedule_prune(void)
964 {
965 wake_up_process(prune_thread);
966 }
967
968 /*
969 * ... and that one is done if evict_chunk() decides to delay until the end
970 * of syscall. Runs synchronously.
971 */
972 void audit_kill_trees(struct audit_context *context)
973 {
974 struct list_head *list = &context->killed_trees;
975
976 audit_ctl_lock();
977 mutex_lock(&audit_filter_mutex);
978
979 while (!list_empty(list)) {
980 struct audit_tree *victim;
981
982 victim = list_entry(list->next, struct audit_tree, list);
983 kill_rules(context, victim);
984 list_del_init(&victim->list);
985
986 mutex_unlock(&audit_filter_mutex);
987
988 prune_one(victim);
989
990 mutex_lock(&audit_filter_mutex);
991 }
992
993 mutex_unlock(&audit_filter_mutex);
994 audit_ctl_unlock();
995 }
996
997 /*
998 * Here comes the stuff asynchronous to auditctl operations
999 */
1000
1001 static void evict_chunk(struct audit_chunk *chunk)
1002 {
1003 struct audit_tree *owner;
1004 struct list_head *postponed = audit_killed_trees();
1005 int need_prune = 0;
1006 int n;
1007
1008 mutex_lock(&audit_filter_mutex);
1009 spin_lock(&hash_lock);
1010 while (!list_empty(&chunk->trees)) {
1011 owner = list_entry(chunk->trees.next,
1012 struct audit_tree, same_root);
1013 owner->goner = 1;
1014 owner->root = NULL;
1015 list_del_init(&owner->same_root);
1016 spin_unlock(&hash_lock);
1017 if (!postponed) {
1018 kill_rules(audit_context(), owner);
1019 list_move(&owner->list, &prune_list);
1020 need_prune = 1;
1021 } else {
1022 list_move(&owner->list, postponed);
1023 }
1024 spin_lock(&hash_lock);
1025 }
1026 list_del_rcu(&chunk->hash);
1027 for (n = 0; n < chunk->count; n++)
1028 list_del_init(&chunk->owners[n].list);
1029 spin_unlock(&hash_lock);
1030 mutex_unlock(&audit_filter_mutex);
1031 if (need_prune)
1032 audit_schedule_prune();
1033 }
1034
1035 static int audit_tree_handle_event(struct fsnotify_mark *mark, u32 mask,
1036 struct inode *inode, struct inode *dir,
1037 const struct qstr *file_name, u32 cookie)
1038 {
1039 return 0;
1040 }
1041
1042 static void audit_tree_freeing_mark(struct fsnotify_mark *mark,
1043 struct fsnotify_group *group)
1044 {
1045 struct audit_chunk *chunk;
1046
1047 fsnotify_group_lock(mark->group);
1048 spin_lock(&hash_lock);
1049 chunk = mark_chunk(mark);
1050 replace_mark_chunk(mark, NULL);
1051 spin_unlock(&hash_lock);
1052 fsnotify_group_unlock(mark->group);
1053 if (chunk) {
1054 evict_chunk(chunk);
1055 audit_mark_put_chunk(chunk);
1056 }
1057
1058 /*
1059 * We are guaranteed to have at least one reference to the mark from
1060 * either the inode or the caller of fsnotify_destroy_mark().
1061 */
1062 BUG_ON(refcount_read(&mark->refcnt) < 1);
1063 }
1064
1065 static const struct fsnotify_ops audit_tree_ops = {
1066 .handle_inode_event = audit_tree_handle_event,
1067 .freeing_mark = audit_tree_freeing_mark,
1068 .free_mark = audit_tree_destroy_watch,
1069 };
1070
1071 static int __init audit_tree_init(void)
1072 {
1073 int i;
1074
1075 audit_tree_mark_cachep = KMEM_CACHE(audit_tree_mark, SLAB_PANIC);
1076
1077 audit_tree_group = fsnotify_alloc_group(&audit_tree_ops, 0);
1078 if (IS_ERR(audit_tree_group))
1079 audit_panic("cannot initialize fsnotify group for rectree watches");
1080
1081 for (i = 0; i < HASH_SIZE; i++)
1082 INIT_LIST_HEAD(&chunk_hash_heads[i]);
1083
1084 return 0;
1085 }
1086 __initcall(audit_tree_init);
1087
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