fsnotify: provide the data type to should_send_event
[linux-3.10.git] / kernel / audit_tree.c
1 #include "audit.h"
2 #include <linux/fsnotify_backend.h>
3 #include <linux/namei.h>
4 #include <linux/mount.h>
5 #include <linux/kthread.h>
6 #include <linux/slab.h>
7
8 struct audit_tree;
9 struct audit_chunk;
10
11 struct audit_tree {
12         atomic_t count;
13         int goner;
14         struct audit_chunk *root;
15         struct list_head chunks;
16         struct list_head rules;
17         struct list_head list;
18         struct list_head same_root;
19         struct rcu_head head;
20         char pathname[];
21 };
22
23 struct audit_chunk {
24         struct list_head hash;
25         struct fsnotify_mark_entry mark;
26         struct list_head trees;         /* with root here */
27         int dead;
28         int count;
29         atomic_long_t refs;
30         struct rcu_head head;
31         struct node {
32                 struct list_head list;
33                 struct audit_tree *owner;
34                 unsigned index;         /* index; upper bit indicates 'will prune' */
35         } owners[];
36 };
37
38 static LIST_HEAD(tree_list);
39 static LIST_HEAD(prune_list);
40
41 /*
42  * One struct chunk is attached to each inode of interest.
43  * We replace struct chunk on tagging/untagging.
44  * Rules have pointer to struct audit_tree.
45  * Rules have struct list_head rlist forming a list of rules over
46  * the same tree.
47  * References to struct chunk are collected at audit_inode{,_child}()
48  * time and used in AUDIT_TREE rule matching.
49  * These references are dropped at the same time we are calling
50  * audit_free_names(), etc.
51  *
52  * Cyclic lists galore:
53  * tree.chunks anchors chunk.owners[].list                      hash_lock
54  * tree.rules anchors rule.rlist                                audit_filter_mutex
55  * chunk.trees anchors tree.same_root                           hash_lock
56  * chunk.hash is a hash with middle bits of watch.inode as
57  * a hash function.                                             RCU, hash_lock
58  *
59  * tree is refcounted; one reference for "some rules on rules_list refer to
60  * it", one for each chunk with pointer to it.
61  *
62  * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
63  * of watch contributes 1 to .refs).
64  *
65  * node.index allows to get from node.list to containing chunk.
66  * MSB of that sucker is stolen to mark taggings that we might have to
67  * revert - several operations have very unpleasant cleanup logics and
68  * that makes a difference.  Some.
69  */
70
71 static struct fsnotify_group *audit_tree_group;
72
73 static struct audit_tree *alloc_tree(const char *s)
74 {
75         struct audit_tree *tree;
76
77         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
78         if (tree) {
79                 atomic_set(&tree->count, 1);
80                 tree->goner = 0;
81                 INIT_LIST_HEAD(&tree->chunks);
82                 INIT_LIST_HEAD(&tree->rules);
83                 INIT_LIST_HEAD(&tree->list);
84                 INIT_LIST_HEAD(&tree->same_root);
85                 tree->root = NULL;
86                 strcpy(tree->pathname, s);
87         }
88         return tree;
89 }
90
91 static inline void get_tree(struct audit_tree *tree)
92 {
93         atomic_inc(&tree->count);
94 }
95
96 static void __put_tree(struct rcu_head *rcu)
97 {
98         struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
99         kfree(tree);
100 }
101
102 static inline void put_tree(struct audit_tree *tree)
103 {
104         if (atomic_dec_and_test(&tree->count))
105                 call_rcu(&tree->head, __put_tree);
106 }
107
108 /* to avoid bringing the entire thing in audit.h */
109 const char *audit_tree_path(struct audit_tree *tree)
110 {
111         return tree->pathname;
112 }
113
114 static void free_chunk(struct audit_chunk *chunk)
115 {
116         int i;
117
118         for (i = 0; i < chunk->count; i++) {
119                 if (chunk->owners[i].owner)
120                         put_tree(chunk->owners[i].owner);
121         }
122         kfree(chunk);
123 }
124
125 void audit_put_chunk(struct audit_chunk *chunk)
126 {
127         if (atomic_long_dec_and_test(&chunk->refs))
128                 free_chunk(chunk);
129 }
130
131 static void __put_chunk(struct rcu_head *rcu)
132 {
133         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
134         audit_put_chunk(chunk);
135 }
136
137 static void audit_tree_destroy_watch(struct fsnotify_mark_entry *entry)
138 {
139         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
140         call_rcu(&chunk->head, __put_chunk);
141 }
142
143 static struct audit_chunk *alloc_chunk(int count)
144 {
145         struct audit_chunk *chunk;
146         size_t size;
147         int i;
148
149         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
150         chunk = kzalloc(size, GFP_KERNEL);
151         if (!chunk)
152                 return NULL;
153
154         INIT_LIST_HEAD(&chunk->hash);
155         INIT_LIST_HEAD(&chunk->trees);
156         chunk->count = count;
157         atomic_long_set(&chunk->refs, 1);
158         for (i = 0; i < count; i++) {
159                 INIT_LIST_HEAD(&chunk->owners[i].list);
160                 chunk->owners[i].index = i;
161         }
162         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
163         return chunk;
164 }
165
166 enum {HASH_SIZE = 128};
167 static struct list_head chunk_hash_heads[HASH_SIZE];
168 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
169
170 static inline struct list_head *chunk_hash(const struct inode *inode)
171 {
172         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
173         return chunk_hash_heads + n % HASH_SIZE;
174 }
175
176 /* hash_lock & entry->lock is held by caller */
177 static void insert_hash(struct audit_chunk *chunk)
178 {
179         struct fsnotify_mark_entry *entry = &chunk->mark;
180         struct list_head *list;
181
182         if (!entry->inode)
183                 return;
184         list = chunk_hash(entry->inode);
185         list_add_rcu(&chunk->hash, list);
186 }
187
188 /* called under rcu_read_lock */
189 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
190 {
191         struct list_head *list = chunk_hash(inode);
192         struct audit_chunk *p;
193
194         list_for_each_entry_rcu(p, list, hash) {
195                 /* mark.inode may have gone NULL, but who cares? */
196                 if (p->mark.inode == inode) {
197                         atomic_long_inc(&p->refs);
198                         return p;
199                 }
200         }
201         return NULL;
202 }
203
204 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
205 {
206         int n;
207         for (n = 0; n < chunk->count; n++)
208                 if (chunk->owners[n].owner == tree)
209                         return 1;
210         return 0;
211 }
212
213 /* tagging and untagging inodes with trees */
214
215 static struct audit_chunk *find_chunk(struct node *p)
216 {
217         int index = p->index & ~(1U<<31);
218         p -= index;
219         return container_of(p, struct audit_chunk, owners[0]);
220 }
221
222 static void untag_chunk(struct node *p)
223 {
224         struct audit_chunk *chunk = find_chunk(p);
225         struct fsnotify_mark_entry *entry = &chunk->mark;
226         struct audit_chunk *new;
227         struct audit_tree *owner;
228         int size = chunk->count - 1;
229         int i, j;
230
231         fsnotify_get_mark(entry);
232
233         spin_unlock(&hash_lock);
234
235         spin_lock(&entry->lock);
236         if (chunk->dead || !entry->inode) {
237                 spin_unlock(&entry->lock);
238                 goto out;
239         }
240
241         owner = p->owner;
242
243         if (!size) {
244                 chunk->dead = 1;
245                 spin_lock(&hash_lock);
246                 list_del_init(&chunk->trees);
247                 if (owner->root == chunk)
248                         owner->root = NULL;
249                 list_del_init(&p->list);
250                 list_del_rcu(&chunk->hash);
251                 spin_unlock(&hash_lock);
252                 spin_unlock(&entry->lock);
253                 fsnotify_destroy_mark_by_entry(entry);
254                 fsnotify_put_mark(entry);
255                 goto out;
256         }
257
258         new = alloc_chunk(size);
259         if (!new)
260                 goto Fallback;
261         fsnotify_duplicate_mark(&new->mark, entry);
262         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, 1)) {
263                 free_chunk(new);
264                 goto Fallback;
265         }
266
267         chunk->dead = 1;
268         spin_lock(&hash_lock);
269         list_replace_init(&chunk->trees, &new->trees);
270         if (owner->root == chunk) {
271                 list_del_init(&owner->same_root);
272                 owner->root = NULL;
273         }
274
275         for (i = j = 0; j <= size; i++, j++) {
276                 struct audit_tree *s;
277                 if (&chunk->owners[j] == p) {
278                         list_del_init(&p->list);
279                         i--;
280                         continue;
281                 }
282                 s = chunk->owners[j].owner;
283                 new->owners[i].owner = s;
284                 new->owners[i].index = chunk->owners[j].index - j + i;
285                 if (!s) /* result of earlier fallback */
286                         continue;
287                 get_tree(s);
288                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
289         }
290
291         list_replace_rcu(&chunk->hash, &new->hash);
292         list_for_each_entry(owner, &new->trees, same_root)
293                 owner->root = new;
294         spin_unlock(&hash_lock);
295         spin_unlock(&entry->lock);
296         fsnotify_destroy_mark_by_entry(entry);
297         fsnotify_put_mark(entry);
298         goto out;
299
300 Fallback:
301         // do the best we can
302         spin_lock(&hash_lock);
303         if (owner->root == chunk) {
304                 list_del_init(&owner->same_root);
305                 owner->root = NULL;
306         }
307         list_del_init(&p->list);
308         p->owner = NULL;
309         put_tree(owner);
310         spin_unlock(&hash_lock);
311         spin_unlock(&entry->lock);
312 out:
313         fsnotify_put_mark(entry);
314         spin_lock(&hash_lock);
315 }
316
317 static int create_chunk(struct inode *inode, struct audit_tree *tree)
318 {
319         struct fsnotify_mark_entry *entry;
320         struct audit_chunk *chunk = alloc_chunk(1);
321         if (!chunk)
322                 return -ENOMEM;
323
324         entry = &chunk->mark;
325         if (fsnotify_add_mark(entry, audit_tree_group, inode, 0)) {
326                 free_chunk(chunk);
327                 return -ENOSPC;
328         }
329
330         spin_lock(&entry->lock);
331         spin_lock(&hash_lock);
332         if (tree->goner) {
333                 spin_unlock(&hash_lock);
334                 chunk->dead = 1;
335                 spin_unlock(&entry->lock);
336                 fsnotify_destroy_mark_by_entry(entry);
337                 fsnotify_put_mark(entry);
338                 return 0;
339         }
340         chunk->owners[0].index = (1U << 31);
341         chunk->owners[0].owner = tree;
342         get_tree(tree);
343         list_add(&chunk->owners[0].list, &tree->chunks);
344         if (!tree->root) {
345                 tree->root = chunk;
346                 list_add(&tree->same_root, &chunk->trees);
347         }
348         insert_hash(chunk);
349         spin_unlock(&hash_lock);
350         spin_unlock(&entry->lock);
351         return 0;
352 }
353
354 /* the first tagged inode becomes root of tree */
355 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
356 {
357         struct fsnotify_mark_entry *old_entry, *chunk_entry;
358         struct audit_tree *owner;
359         struct audit_chunk *chunk, *old;
360         struct node *p;
361         int n;
362
363         spin_lock(&inode->i_lock);
364         old_entry = fsnotify_find_mark_entry(audit_tree_group, inode);
365         spin_unlock(&inode->i_lock);
366         if (!old_entry)
367                 return create_chunk(inode, tree);
368
369         old = container_of(old_entry, struct audit_chunk, mark);
370
371         /* are we already there? */
372         spin_lock(&hash_lock);
373         for (n = 0; n < old->count; n++) {
374                 if (old->owners[n].owner == tree) {
375                         spin_unlock(&hash_lock);
376                         fsnotify_put_mark(old_entry);
377                         return 0;
378                 }
379         }
380         spin_unlock(&hash_lock);
381
382         chunk = alloc_chunk(old->count + 1);
383         if (!chunk) {
384                 fsnotify_put_mark(old_entry);
385                 return -ENOMEM;
386         }
387
388         chunk_entry = &chunk->mark;
389
390         spin_lock(&old_entry->lock);
391         if (!old_entry->inode) {
392                 /* old_entry is being shot, lets just lie */
393                 spin_unlock(&old_entry->lock);
394                 fsnotify_put_mark(old_entry);
395                 free_chunk(chunk);
396                 return -ENOENT;
397         }
398
399         fsnotify_duplicate_mark(chunk_entry, old_entry);
400         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, 1)) {
401                 spin_unlock(&old_entry->lock);
402                 free_chunk(chunk);
403                 fsnotify_put_mark(old_entry);
404                 return -ENOSPC;
405         }
406
407         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
408         spin_lock(&chunk_entry->lock);
409         spin_lock(&hash_lock);
410
411         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
412         if (tree->goner) {
413                 spin_unlock(&hash_lock);
414                 chunk->dead = 1;
415                 spin_unlock(&chunk_entry->lock);
416                 spin_unlock(&old_entry->lock);
417
418                 fsnotify_destroy_mark_by_entry(chunk_entry);
419
420                 fsnotify_put_mark(chunk_entry);
421                 fsnotify_put_mark(old_entry);
422                 return 0;
423         }
424         list_replace_init(&old->trees, &chunk->trees);
425         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
426                 struct audit_tree *s = old->owners[n].owner;
427                 p->owner = s;
428                 p->index = old->owners[n].index;
429                 if (!s) /* result of fallback in untag */
430                         continue;
431                 get_tree(s);
432                 list_replace_init(&old->owners[n].list, &p->list);
433         }
434         p->index = (chunk->count - 1) | (1U<<31);
435         p->owner = tree;
436         get_tree(tree);
437         list_add(&p->list, &tree->chunks);
438         list_replace_rcu(&old->hash, &chunk->hash);
439         list_for_each_entry(owner, &chunk->trees, same_root)
440                 owner->root = chunk;
441         old->dead = 1;
442         if (!tree->root) {
443                 tree->root = chunk;
444                 list_add(&tree->same_root, &chunk->trees);
445         }
446         spin_unlock(&hash_lock);
447         spin_unlock(&chunk_entry->lock);
448         spin_unlock(&old_entry->lock);
449         fsnotify_destroy_mark_by_entry(old_entry);
450         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
451         fsnotify_put_mark(old_entry); /* and kill it */
452         return 0;
453 }
454
455 static void kill_rules(struct audit_tree *tree)
456 {
457         struct audit_krule *rule, *next;
458         struct audit_entry *entry;
459         struct audit_buffer *ab;
460
461         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
462                 entry = container_of(rule, struct audit_entry, rule);
463
464                 list_del_init(&rule->rlist);
465                 if (rule->tree) {
466                         /* not a half-baked one */
467                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
468                         audit_log_format(ab, "op=");
469                         audit_log_string(ab, "remove rule");
470                         audit_log_format(ab, " dir=");
471                         audit_log_untrustedstring(ab, rule->tree->pathname);
472                         audit_log_key(ab, rule->filterkey);
473                         audit_log_format(ab, " list=%d res=1", rule->listnr);
474                         audit_log_end(ab);
475                         rule->tree = NULL;
476                         list_del_rcu(&entry->list);
477                         list_del(&entry->rule.list);
478                         call_rcu(&entry->rcu, audit_free_rule_rcu);
479                 }
480         }
481 }
482
483 /*
484  * finish killing struct audit_tree
485  */
486 static void prune_one(struct audit_tree *victim)
487 {
488         spin_lock(&hash_lock);
489         while (!list_empty(&victim->chunks)) {
490                 struct node *p;
491
492                 p = list_entry(victim->chunks.next, struct node, list);
493
494                 untag_chunk(p);
495         }
496         spin_unlock(&hash_lock);
497         put_tree(victim);
498 }
499
500 /* trim the uncommitted chunks from tree */
501
502 static void trim_marked(struct audit_tree *tree)
503 {
504         struct list_head *p, *q;
505         spin_lock(&hash_lock);
506         if (tree->goner) {
507                 spin_unlock(&hash_lock);
508                 return;
509         }
510         /* reorder */
511         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
512                 struct node *node = list_entry(p, struct node, list);
513                 q = p->next;
514                 if (node->index & (1U<<31)) {
515                         list_del_init(p);
516                         list_add(p, &tree->chunks);
517                 }
518         }
519
520         while (!list_empty(&tree->chunks)) {
521                 struct node *node;
522
523                 node = list_entry(tree->chunks.next, struct node, list);
524
525                 /* have we run out of marked? */
526                 if (!(node->index & (1U<<31)))
527                         break;
528
529                 untag_chunk(node);
530         }
531         if (!tree->root && !tree->goner) {
532                 tree->goner = 1;
533                 spin_unlock(&hash_lock);
534                 mutex_lock(&audit_filter_mutex);
535                 kill_rules(tree);
536                 list_del_init(&tree->list);
537                 mutex_unlock(&audit_filter_mutex);
538                 prune_one(tree);
539         } else {
540                 spin_unlock(&hash_lock);
541         }
542 }
543
544 static void audit_schedule_prune(void);
545
546 /* called with audit_filter_mutex */
547 int audit_remove_tree_rule(struct audit_krule *rule)
548 {
549         struct audit_tree *tree;
550         tree = rule->tree;
551         if (tree) {
552                 spin_lock(&hash_lock);
553                 list_del_init(&rule->rlist);
554                 if (list_empty(&tree->rules) && !tree->goner) {
555                         tree->root = NULL;
556                         list_del_init(&tree->same_root);
557                         tree->goner = 1;
558                         list_move(&tree->list, &prune_list);
559                         rule->tree = NULL;
560                         spin_unlock(&hash_lock);
561                         audit_schedule_prune();
562                         return 1;
563                 }
564                 rule->tree = NULL;
565                 spin_unlock(&hash_lock);
566                 return 1;
567         }
568         return 0;
569 }
570
571 static int compare_root(struct vfsmount *mnt, void *arg)
572 {
573         return mnt->mnt_root->d_inode == arg;
574 }
575
576 void audit_trim_trees(void)
577 {
578         struct list_head cursor;
579
580         mutex_lock(&audit_filter_mutex);
581         list_add(&cursor, &tree_list);
582         while (cursor.next != &tree_list) {
583                 struct audit_tree *tree;
584                 struct path path;
585                 struct vfsmount *root_mnt;
586                 struct node *node;
587                 int err;
588
589                 tree = container_of(cursor.next, struct audit_tree, list);
590                 get_tree(tree);
591                 list_del(&cursor);
592                 list_add(&cursor, &tree->list);
593                 mutex_unlock(&audit_filter_mutex);
594
595                 err = kern_path(tree->pathname, 0, &path);
596                 if (err)
597                         goto skip_it;
598
599                 root_mnt = collect_mounts(&path);
600                 path_put(&path);
601                 if (!root_mnt)
602                         goto skip_it;
603
604                 spin_lock(&hash_lock);
605                 list_for_each_entry(node, &tree->chunks, list) {
606                         struct audit_chunk *chunk = find_chunk(node);
607                         /* this could be NULL if the watch is dieing else where... */
608                         struct inode *inode = chunk->mark.inode;
609                         node->index |= 1U<<31;
610                         if (iterate_mounts(compare_root, inode, root_mnt))
611                                 node->index &= ~(1U<<31);
612                 }
613                 spin_unlock(&hash_lock);
614                 trim_marked(tree);
615                 put_tree(tree);
616                 drop_collected_mounts(root_mnt);
617 skip_it:
618                 mutex_lock(&audit_filter_mutex);
619         }
620         list_del(&cursor);
621         mutex_unlock(&audit_filter_mutex);
622 }
623
624 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
625 {
626
627         if (pathname[0] != '/' ||
628             rule->listnr != AUDIT_FILTER_EXIT ||
629             op != Audit_equal ||
630             rule->inode_f || rule->watch || rule->tree)
631                 return -EINVAL;
632         rule->tree = alloc_tree(pathname);
633         if (!rule->tree)
634                 return -ENOMEM;
635         return 0;
636 }
637
638 void audit_put_tree(struct audit_tree *tree)
639 {
640         put_tree(tree);
641 }
642
643 static int tag_mount(struct vfsmount *mnt, void *arg)
644 {
645         return tag_chunk(mnt->mnt_root->d_inode, arg);
646 }
647
648 /* called with audit_filter_mutex */
649 int audit_add_tree_rule(struct audit_krule *rule)
650 {
651         struct audit_tree *seed = rule->tree, *tree;
652         struct path path;
653         struct vfsmount *mnt;
654         int err;
655
656         list_for_each_entry(tree, &tree_list, list) {
657                 if (!strcmp(seed->pathname, tree->pathname)) {
658                         put_tree(seed);
659                         rule->tree = tree;
660                         list_add(&rule->rlist, &tree->rules);
661                         return 0;
662                 }
663         }
664         tree = seed;
665         list_add(&tree->list, &tree_list);
666         list_add(&rule->rlist, &tree->rules);
667         /* do not set rule->tree yet */
668         mutex_unlock(&audit_filter_mutex);
669
670         err = kern_path(tree->pathname, 0, &path);
671         if (err)
672                 goto Err;
673         mnt = collect_mounts(&path);
674         path_put(&path);
675         if (!mnt) {
676                 err = -ENOMEM;
677                 goto Err;
678         }
679
680         get_tree(tree);
681         err = iterate_mounts(tag_mount, tree, mnt);
682         drop_collected_mounts(mnt);
683
684         if (!err) {
685                 struct node *node;
686                 spin_lock(&hash_lock);
687                 list_for_each_entry(node, &tree->chunks, list)
688                         node->index &= ~(1U<<31);
689                 spin_unlock(&hash_lock);
690         } else {
691                 trim_marked(tree);
692                 goto Err;
693         }
694
695         mutex_lock(&audit_filter_mutex);
696         if (list_empty(&rule->rlist)) {
697                 put_tree(tree);
698                 return -ENOENT;
699         }
700         rule->tree = tree;
701         put_tree(tree);
702
703         return 0;
704 Err:
705         mutex_lock(&audit_filter_mutex);
706         list_del_init(&tree->list);
707         list_del_init(&tree->rules);
708         put_tree(tree);
709         return err;
710 }
711
712 int audit_tag_tree(char *old, char *new)
713 {
714         struct list_head cursor, barrier;
715         int failed = 0;
716         struct path path1, path2;
717         struct vfsmount *tagged;
718         int err;
719
720         err = kern_path(new, 0, &path2);
721         if (err)
722                 return err;
723         tagged = collect_mounts(&path2);
724         path_put(&path2);
725         if (!tagged)
726                 return -ENOMEM;
727
728         err = kern_path(old, 0, &path1);
729         if (err) {
730                 drop_collected_mounts(tagged);
731                 return err;
732         }
733
734         mutex_lock(&audit_filter_mutex);
735         list_add(&barrier, &tree_list);
736         list_add(&cursor, &barrier);
737
738         while (cursor.next != &tree_list) {
739                 struct audit_tree *tree;
740                 int good_one = 0;
741
742                 tree = container_of(cursor.next, struct audit_tree, list);
743                 get_tree(tree);
744                 list_del(&cursor);
745                 list_add(&cursor, &tree->list);
746                 mutex_unlock(&audit_filter_mutex);
747
748                 err = kern_path(tree->pathname, 0, &path2);
749                 if (!err) {
750                         good_one = path_is_under(&path1, &path2);
751                         path_put(&path2);
752                 }
753
754                 if (!good_one) {
755                         put_tree(tree);
756                         mutex_lock(&audit_filter_mutex);
757                         continue;
758                 }
759
760                 failed = iterate_mounts(tag_mount, tree, tagged);
761                 if (failed) {
762                         put_tree(tree);
763                         mutex_lock(&audit_filter_mutex);
764                         break;
765                 }
766
767                 mutex_lock(&audit_filter_mutex);
768                 spin_lock(&hash_lock);
769                 if (!tree->goner) {
770                         list_del(&tree->list);
771                         list_add(&tree->list, &tree_list);
772                 }
773                 spin_unlock(&hash_lock);
774                 put_tree(tree);
775         }
776
777         while (barrier.prev != &tree_list) {
778                 struct audit_tree *tree;
779
780                 tree = container_of(barrier.prev, struct audit_tree, list);
781                 get_tree(tree);
782                 list_del(&tree->list);
783                 list_add(&tree->list, &barrier);
784                 mutex_unlock(&audit_filter_mutex);
785
786                 if (!failed) {
787                         struct node *node;
788                         spin_lock(&hash_lock);
789                         list_for_each_entry(node, &tree->chunks, list)
790                                 node->index &= ~(1U<<31);
791                         spin_unlock(&hash_lock);
792                 } else {
793                         trim_marked(tree);
794                 }
795
796                 put_tree(tree);
797                 mutex_lock(&audit_filter_mutex);
798         }
799         list_del(&barrier);
800         list_del(&cursor);
801         mutex_unlock(&audit_filter_mutex);
802         path_put(&path1);
803         drop_collected_mounts(tagged);
804         return failed;
805 }
806
807 /*
808  * That gets run when evict_chunk() ends up needing to kill audit_tree.
809  * Runs from a separate thread.
810  */
811 static int prune_tree_thread(void *unused)
812 {
813         mutex_lock(&audit_cmd_mutex);
814         mutex_lock(&audit_filter_mutex);
815
816         while (!list_empty(&prune_list)) {
817                 struct audit_tree *victim;
818
819                 victim = list_entry(prune_list.next, struct audit_tree, list);
820                 list_del_init(&victim->list);
821
822                 mutex_unlock(&audit_filter_mutex);
823
824                 prune_one(victim);
825
826                 mutex_lock(&audit_filter_mutex);
827         }
828
829         mutex_unlock(&audit_filter_mutex);
830         mutex_unlock(&audit_cmd_mutex);
831         return 0;
832 }
833
834 static void audit_schedule_prune(void)
835 {
836         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
837 }
838
839 /*
840  * ... and that one is done if evict_chunk() decides to delay until the end
841  * of syscall.  Runs synchronously.
842  */
843 void audit_kill_trees(struct list_head *list)
844 {
845         mutex_lock(&audit_cmd_mutex);
846         mutex_lock(&audit_filter_mutex);
847
848         while (!list_empty(list)) {
849                 struct audit_tree *victim;
850
851                 victim = list_entry(list->next, struct audit_tree, list);
852                 kill_rules(victim);
853                 list_del_init(&victim->list);
854
855                 mutex_unlock(&audit_filter_mutex);
856
857                 prune_one(victim);
858
859                 mutex_lock(&audit_filter_mutex);
860         }
861
862         mutex_unlock(&audit_filter_mutex);
863         mutex_unlock(&audit_cmd_mutex);
864 }
865
866 /*
867  *  Here comes the stuff asynchronous to auditctl operations
868  */
869
870 static void evict_chunk(struct audit_chunk *chunk)
871 {
872         struct audit_tree *owner;
873         struct list_head *postponed = audit_killed_trees();
874         int need_prune = 0;
875         int n;
876
877         if (chunk->dead)
878                 return;
879
880         chunk->dead = 1;
881         mutex_lock(&audit_filter_mutex);
882         spin_lock(&hash_lock);
883         while (!list_empty(&chunk->trees)) {
884                 owner = list_entry(chunk->trees.next,
885                                    struct audit_tree, same_root);
886                 owner->goner = 1;
887                 owner->root = NULL;
888                 list_del_init(&owner->same_root);
889                 spin_unlock(&hash_lock);
890                 if (!postponed) {
891                         kill_rules(owner);
892                         list_move(&owner->list, &prune_list);
893                         need_prune = 1;
894                 } else {
895                         list_move(&owner->list, postponed);
896                 }
897                 spin_lock(&hash_lock);
898         }
899         list_del_rcu(&chunk->hash);
900         for (n = 0; n < chunk->count; n++)
901                 list_del_init(&chunk->owners[n].list);
902         spin_unlock(&hash_lock);
903         if (need_prune)
904                 audit_schedule_prune();
905         mutex_unlock(&audit_filter_mutex);
906 }
907
908 static int audit_tree_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
909 {
910         BUG();
911         return -EOPNOTSUPP;
912 }
913
914 static void audit_tree_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
915 {
916         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
917
918         evict_chunk(chunk);
919         fsnotify_put_mark(entry);
920 }
921
922 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
923                                   __u32 mask, int data_type)
924 {
925         return 0;
926 }
927
928 static const struct fsnotify_ops audit_tree_ops = {
929         .handle_event = audit_tree_handle_event,
930         .should_send_event = audit_tree_send_event,
931         .free_group_priv = NULL,
932         .free_event_priv = NULL,
933         .freeing_mark = audit_tree_freeing_mark,
934 };
935
936 static int __init audit_tree_init(void)
937 {
938         int i;
939
940         audit_tree_group = fsnotify_obtain_group(AUDIT_TREE_GROUP_NUM,
941                                                  0, &audit_tree_ops);
942         if (IS_ERR(audit_tree_group))
943                 audit_panic("cannot initialize fsnotify group for rectree watches");
944
945         for (i = 0; i < HASH_SIZE; i++)
946                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
947
948         return 0;
949 }
950 __initcall(audit_tree_init);