fanotify: use both marks when possible
[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 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)
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 = &chunk->mark;
180         struct list_head *list;
181
182         if (!entry->i.inode)
183                 return;
184         list = chunk_hash(entry->i.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.i.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 = &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->i.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(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.i.inode, NULL, 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(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;
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, NULL, 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(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 *old_entry, *chunk_entry;
358         struct audit_tree *owner;
359         struct audit_chunk *chunk, *old;
360         struct node *p;
361         int n;
362
363         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
364         if (!old_entry)
365                 return create_chunk(inode, tree);
366
367         old = container_of(old_entry, struct audit_chunk, mark);
368
369         /* are we already there? */
370         spin_lock(&hash_lock);
371         for (n = 0; n < old->count; n++) {
372                 if (old->owners[n].owner == tree) {
373                         spin_unlock(&hash_lock);
374                         fsnotify_put_mark(old_entry);
375                         return 0;
376                 }
377         }
378         spin_unlock(&hash_lock);
379
380         chunk = alloc_chunk(old->count + 1);
381         if (!chunk) {
382                 fsnotify_put_mark(old_entry);
383                 return -ENOMEM;
384         }
385
386         chunk_entry = &chunk->mark;
387
388         spin_lock(&old_entry->lock);
389         if (!old_entry->i.inode) {
390                 /* old_entry is being shot, lets just lie */
391                 spin_unlock(&old_entry->lock);
392                 fsnotify_put_mark(old_entry);
393                 free_chunk(chunk);
394                 return -ENOENT;
395         }
396
397         fsnotify_duplicate_mark(chunk_entry, old_entry);
398         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
399                 spin_unlock(&old_entry->lock);
400                 free_chunk(chunk);
401                 fsnotify_put_mark(old_entry);
402                 return -ENOSPC;
403         }
404
405         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
406         spin_lock(&chunk_entry->lock);
407         spin_lock(&hash_lock);
408
409         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
410         if (tree->goner) {
411                 spin_unlock(&hash_lock);
412                 chunk->dead = 1;
413                 spin_unlock(&chunk_entry->lock);
414                 spin_unlock(&old_entry->lock);
415
416                 fsnotify_destroy_mark(chunk_entry);
417
418                 fsnotify_put_mark(chunk_entry);
419                 fsnotify_put_mark(old_entry);
420                 return 0;
421         }
422         list_replace_init(&old->trees, &chunk->trees);
423         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
424                 struct audit_tree *s = old->owners[n].owner;
425                 p->owner = s;
426                 p->index = old->owners[n].index;
427                 if (!s) /* result of fallback in untag */
428                         continue;
429                 get_tree(s);
430                 list_replace_init(&old->owners[n].list, &p->list);
431         }
432         p->index = (chunk->count - 1) | (1U<<31);
433         p->owner = tree;
434         get_tree(tree);
435         list_add(&p->list, &tree->chunks);
436         list_replace_rcu(&old->hash, &chunk->hash);
437         list_for_each_entry(owner, &chunk->trees, same_root)
438                 owner->root = chunk;
439         old->dead = 1;
440         if (!tree->root) {
441                 tree->root = chunk;
442                 list_add(&tree->same_root, &chunk->trees);
443         }
444         spin_unlock(&hash_lock);
445         spin_unlock(&chunk_entry->lock);
446         spin_unlock(&old_entry->lock);
447         fsnotify_destroy_mark(old_entry);
448         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
449         fsnotify_put_mark(old_entry); /* and kill it */
450         return 0;
451 }
452
453 static void kill_rules(struct audit_tree *tree)
454 {
455         struct audit_krule *rule, *next;
456         struct audit_entry *entry;
457         struct audit_buffer *ab;
458
459         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
460                 entry = container_of(rule, struct audit_entry, rule);
461
462                 list_del_init(&rule->rlist);
463                 if (rule->tree) {
464                         /* not a half-baked one */
465                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
466                         audit_log_format(ab, "op=");
467                         audit_log_string(ab, "remove rule");
468                         audit_log_format(ab, " dir=");
469                         audit_log_untrustedstring(ab, rule->tree->pathname);
470                         audit_log_key(ab, rule->filterkey);
471                         audit_log_format(ab, " list=%d res=1", rule->listnr);
472                         audit_log_end(ab);
473                         rule->tree = NULL;
474                         list_del_rcu(&entry->list);
475                         list_del(&entry->rule.list);
476                         call_rcu(&entry->rcu, audit_free_rule_rcu);
477                 }
478         }
479 }
480
481 /*
482  * finish killing struct audit_tree
483  */
484 static void prune_one(struct audit_tree *victim)
485 {
486         spin_lock(&hash_lock);
487         while (!list_empty(&victim->chunks)) {
488                 struct node *p;
489
490                 p = list_entry(victim->chunks.next, struct node, list);
491
492                 untag_chunk(p);
493         }
494         spin_unlock(&hash_lock);
495         put_tree(victim);
496 }
497
498 /* trim the uncommitted chunks from tree */
499
500 static void trim_marked(struct audit_tree *tree)
501 {
502         struct list_head *p, *q;
503         spin_lock(&hash_lock);
504         if (tree->goner) {
505                 spin_unlock(&hash_lock);
506                 return;
507         }
508         /* reorder */
509         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
510                 struct node *node = list_entry(p, struct node, list);
511                 q = p->next;
512                 if (node->index & (1U<<31)) {
513                         list_del_init(p);
514                         list_add(p, &tree->chunks);
515                 }
516         }
517
518         while (!list_empty(&tree->chunks)) {
519                 struct node *node;
520
521                 node = list_entry(tree->chunks.next, struct node, list);
522
523                 /* have we run out of marked? */
524                 if (!(node->index & (1U<<31)))
525                         break;
526
527                 untag_chunk(node);
528         }
529         if (!tree->root && !tree->goner) {
530                 tree->goner = 1;
531                 spin_unlock(&hash_lock);
532                 mutex_lock(&audit_filter_mutex);
533                 kill_rules(tree);
534                 list_del_init(&tree->list);
535                 mutex_unlock(&audit_filter_mutex);
536                 prune_one(tree);
537         } else {
538                 spin_unlock(&hash_lock);
539         }
540 }
541
542 static void audit_schedule_prune(void);
543
544 /* called with audit_filter_mutex */
545 int audit_remove_tree_rule(struct audit_krule *rule)
546 {
547         struct audit_tree *tree;
548         tree = rule->tree;
549         if (tree) {
550                 spin_lock(&hash_lock);
551                 list_del_init(&rule->rlist);
552                 if (list_empty(&tree->rules) && !tree->goner) {
553                         tree->root = NULL;
554                         list_del_init(&tree->same_root);
555                         tree->goner = 1;
556                         list_move(&tree->list, &prune_list);
557                         rule->tree = NULL;
558                         spin_unlock(&hash_lock);
559                         audit_schedule_prune();
560                         return 1;
561                 }
562                 rule->tree = NULL;
563                 spin_unlock(&hash_lock);
564                 return 1;
565         }
566         return 0;
567 }
568
569 static int compare_root(struct vfsmount *mnt, void *arg)
570 {
571         return mnt->mnt_root->d_inode == arg;
572 }
573
574 void audit_trim_trees(void)
575 {
576         struct list_head cursor;
577
578         mutex_lock(&audit_filter_mutex);
579         list_add(&cursor, &tree_list);
580         while (cursor.next != &tree_list) {
581                 struct audit_tree *tree;
582                 struct path path;
583                 struct vfsmount *root_mnt;
584                 struct node *node;
585                 int err;
586
587                 tree = container_of(cursor.next, struct audit_tree, list);
588                 get_tree(tree);
589                 list_del(&cursor);
590                 list_add(&cursor, &tree->list);
591                 mutex_unlock(&audit_filter_mutex);
592
593                 err = kern_path(tree->pathname, 0, &path);
594                 if (err)
595                         goto skip_it;
596
597                 root_mnt = collect_mounts(&path);
598                 path_put(&path);
599                 if (!root_mnt)
600                         goto skip_it;
601
602                 spin_lock(&hash_lock);
603                 list_for_each_entry(node, &tree->chunks, list) {
604                         struct audit_chunk *chunk = find_chunk(node);
605                         /* this could be NULL if the watch is dieing else where... */
606                         struct inode *inode = chunk->mark.i.inode;
607                         node->index |= 1U<<31;
608                         if (iterate_mounts(compare_root, inode, root_mnt))
609                                 node->index &= ~(1U<<31);
610                 }
611                 spin_unlock(&hash_lock);
612                 trim_marked(tree);
613                 put_tree(tree);
614                 drop_collected_mounts(root_mnt);
615 skip_it:
616                 mutex_lock(&audit_filter_mutex);
617         }
618         list_del(&cursor);
619         mutex_unlock(&audit_filter_mutex);
620 }
621
622 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
623 {
624
625         if (pathname[0] != '/' ||
626             rule->listnr != AUDIT_FILTER_EXIT ||
627             op != Audit_equal ||
628             rule->inode_f || rule->watch || rule->tree)
629                 return -EINVAL;
630         rule->tree = alloc_tree(pathname);
631         if (!rule->tree)
632                 return -ENOMEM;
633         return 0;
634 }
635
636 void audit_put_tree(struct audit_tree *tree)
637 {
638         put_tree(tree);
639 }
640
641 static int tag_mount(struct vfsmount *mnt, void *arg)
642 {
643         return tag_chunk(mnt->mnt_root->d_inode, arg);
644 }
645
646 /* called with audit_filter_mutex */
647 int audit_add_tree_rule(struct audit_krule *rule)
648 {
649         struct audit_tree *seed = rule->tree, *tree;
650         struct path path;
651         struct vfsmount *mnt;
652         int err;
653
654         list_for_each_entry(tree, &tree_list, list) {
655                 if (!strcmp(seed->pathname, tree->pathname)) {
656                         put_tree(seed);
657                         rule->tree = tree;
658                         list_add(&rule->rlist, &tree->rules);
659                         return 0;
660                 }
661         }
662         tree = seed;
663         list_add(&tree->list, &tree_list);
664         list_add(&rule->rlist, &tree->rules);
665         /* do not set rule->tree yet */
666         mutex_unlock(&audit_filter_mutex);
667
668         err = kern_path(tree->pathname, 0, &path);
669         if (err)
670                 goto Err;
671         mnt = collect_mounts(&path);
672         path_put(&path);
673         if (!mnt) {
674                 err = -ENOMEM;
675                 goto Err;
676         }
677
678         get_tree(tree);
679         err = iterate_mounts(tag_mount, tree, mnt);
680         drop_collected_mounts(mnt);
681
682         if (!err) {
683                 struct node *node;
684                 spin_lock(&hash_lock);
685                 list_for_each_entry(node, &tree->chunks, list)
686                         node->index &= ~(1U<<31);
687                 spin_unlock(&hash_lock);
688         } else {
689                 trim_marked(tree);
690                 goto Err;
691         }
692
693         mutex_lock(&audit_filter_mutex);
694         if (list_empty(&rule->rlist)) {
695                 put_tree(tree);
696                 return -ENOENT;
697         }
698         rule->tree = tree;
699         put_tree(tree);
700
701         return 0;
702 Err:
703         mutex_lock(&audit_filter_mutex);
704         list_del_init(&tree->list);
705         list_del_init(&tree->rules);
706         put_tree(tree);
707         return err;
708 }
709
710 int audit_tag_tree(char *old, char *new)
711 {
712         struct list_head cursor, barrier;
713         int failed = 0;
714         struct path path1, path2;
715         struct vfsmount *tagged;
716         int err;
717
718         err = kern_path(new, 0, &path2);
719         if (err)
720                 return err;
721         tagged = collect_mounts(&path2);
722         path_put(&path2);
723         if (!tagged)
724                 return -ENOMEM;
725
726         err = kern_path(old, 0, &path1);
727         if (err) {
728                 drop_collected_mounts(tagged);
729                 return err;
730         }
731
732         mutex_lock(&audit_filter_mutex);
733         list_add(&barrier, &tree_list);
734         list_add(&cursor, &barrier);
735
736         while (cursor.next != &tree_list) {
737                 struct audit_tree *tree;
738                 int good_one = 0;
739
740                 tree = container_of(cursor.next, struct audit_tree, list);
741                 get_tree(tree);
742                 list_del(&cursor);
743                 list_add(&cursor, &tree->list);
744                 mutex_unlock(&audit_filter_mutex);
745
746                 err = kern_path(tree->pathname, 0, &path2);
747                 if (!err) {
748                         good_one = path_is_under(&path1, &path2);
749                         path_put(&path2);
750                 }
751
752                 if (!good_one) {
753                         put_tree(tree);
754                         mutex_lock(&audit_filter_mutex);
755                         continue;
756                 }
757
758                 failed = iterate_mounts(tag_mount, tree, tagged);
759                 if (failed) {
760                         put_tree(tree);
761                         mutex_lock(&audit_filter_mutex);
762                         break;
763                 }
764
765                 mutex_lock(&audit_filter_mutex);
766                 spin_lock(&hash_lock);
767                 if (!tree->goner) {
768                         list_del(&tree->list);
769                         list_add(&tree->list, &tree_list);
770                 }
771                 spin_unlock(&hash_lock);
772                 put_tree(tree);
773         }
774
775         while (barrier.prev != &tree_list) {
776                 struct audit_tree *tree;
777
778                 tree = container_of(barrier.prev, struct audit_tree, list);
779                 get_tree(tree);
780                 list_del(&tree->list);
781                 list_add(&tree->list, &barrier);
782                 mutex_unlock(&audit_filter_mutex);
783
784                 if (!failed) {
785                         struct node *node;
786                         spin_lock(&hash_lock);
787                         list_for_each_entry(node, &tree->chunks, list)
788                                 node->index &= ~(1U<<31);
789                         spin_unlock(&hash_lock);
790                 } else {
791                         trim_marked(tree);
792                 }
793
794                 put_tree(tree);
795                 mutex_lock(&audit_filter_mutex);
796         }
797         list_del(&barrier);
798         list_del(&cursor);
799         mutex_unlock(&audit_filter_mutex);
800         path_put(&path1);
801         drop_collected_mounts(tagged);
802         return failed;
803 }
804
805 /*
806  * That gets run when evict_chunk() ends up needing to kill audit_tree.
807  * Runs from a separate thread.
808  */
809 static int prune_tree_thread(void *unused)
810 {
811         mutex_lock(&audit_cmd_mutex);
812         mutex_lock(&audit_filter_mutex);
813
814         while (!list_empty(&prune_list)) {
815                 struct audit_tree *victim;
816
817                 victim = list_entry(prune_list.next, struct audit_tree, list);
818                 list_del_init(&victim->list);
819
820                 mutex_unlock(&audit_filter_mutex);
821
822                 prune_one(victim);
823
824                 mutex_lock(&audit_filter_mutex);
825         }
826
827         mutex_unlock(&audit_filter_mutex);
828         mutex_unlock(&audit_cmd_mutex);
829         return 0;
830 }
831
832 static void audit_schedule_prune(void)
833 {
834         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
835 }
836
837 /*
838  * ... and that one is done if evict_chunk() decides to delay until the end
839  * of syscall.  Runs synchronously.
840  */
841 void audit_kill_trees(struct list_head *list)
842 {
843         mutex_lock(&audit_cmd_mutex);
844         mutex_lock(&audit_filter_mutex);
845
846         while (!list_empty(list)) {
847                 struct audit_tree *victim;
848
849                 victim = list_entry(list->next, struct audit_tree, list);
850                 kill_rules(victim);
851                 list_del_init(&victim->list);
852
853                 mutex_unlock(&audit_filter_mutex);
854
855                 prune_one(victim);
856
857                 mutex_lock(&audit_filter_mutex);
858         }
859
860         mutex_unlock(&audit_filter_mutex);
861         mutex_unlock(&audit_cmd_mutex);
862 }
863
864 /*
865  *  Here comes the stuff asynchronous to auditctl operations
866  */
867
868 static void evict_chunk(struct audit_chunk *chunk)
869 {
870         struct audit_tree *owner;
871         struct list_head *postponed = audit_killed_trees();
872         int need_prune = 0;
873         int n;
874
875         if (chunk->dead)
876                 return;
877
878         chunk->dead = 1;
879         mutex_lock(&audit_filter_mutex);
880         spin_lock(&hash_lock);
881         while (!list_empty(&chunk->trees)) {
882                 owner = list_entry(chunk->trees.next,
883                                    struct audit_tree, same_root);
884                 owner->goner = 1;
885                 owner->root = NULL;
886                 list_del_init(&owner->same_root);
887                 spin_unlock(&hash_lock);
888                 if (!postponed) {
889                         kill_rules(owner);
890                         list_move(&owner->list, &prune_list);
891                         need_prune = 1;
892                 } else {
893                         list_move(&owner->list, postponed);
894                 }
895                 spin_lock(&hash_lock);
896         }
897         list_del_rcu(&chunk->hash);
898         for (n = 0; n < chunk->count; n++)
899                 list_del_init(&chunk->owners[n].list);
900         spin_unlock(&hash_lock);
901         if (need_prune)
902                 audit_schedule_prune();
903         mutex_unlock(&audit_filter_mutex);
904 }
905
906 static int audit_tree_handle_event(struct fsnotify_group *group,
907                                    struct fsnotify_mark *inode_mark,
908                                    struct fsnotify_mark *vfsmonut_mark,
909                                    struct fsnotify_event *event)
910 {
911         BUG();
912         return -EOPNOTSUPP;
913 }
914
915 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
916 {
917         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
918
919         evict_chunk(chunk);
920         fsnotify_put_mark(entry);
921 }
922
923 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
924                                   struct fsnotify_mark *inode_mark,
925                                   struct fsnotify_mark *vfsmount_mark,
926                                   __u32 mask, void *data, int data_type)
927 {
928         return false;
929 }
930
931 static const struct fsnotify_ops audit_tree_ops = {
932         .handle_event = audit_tree_handle_event,
933         .should_send_event = audit_tree_send_event,
934         .free_group_priv = NULL,
935         .free_event_priv = NULL,
936         .freeing_mark = audit_tree_freeing_mark,
937 };
938
939 static int __init audit_tree_init(void)
940 {
941         int i;
942
943         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
944         if (IS_ERR(audit_tree_group))
945                 audit_panic("cannot initialize fsnotify group for rectree watches");
946
947         for (i = 0; i < HASH_SIZE; i++)
948                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
949
950         return 0;
951 }
952 __initcall(audit_tree_init);