btrfs: don't stop searching after encountering the wrong item
[linux-2.6.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 inline void put_tree(struct audit_tree *tree)
97 {
98         if (atomic_dec_and_test(&tree->count))
99                 kfree_rcu(tree, head);
100 }
101
102 /* to avoid bringing the entire thing in audit.h */
103 const char *audit_tree_path(struct audit_tree *tree)
104 {
105         return tree->pathname;
106 }
107
108 static void free_chunk(struct audit_chunk *chunk)
109 {
110         int i;
111
112         for (i = 0; i < chunk->count; i++) {
113                 if (chunk->owners[i].owner)
114                         put_tree(chunk->owners[i].owner);
115         }
116         kfree(chunk);
117 }
118
119 void audit_put_chunk(struct audit_chunk *chunk)
120 {
121         if (atomic_long_dec_and_test(&chunk->refs))
122                 free_chunk(chunk);
123 }
124
125 static void __put_chunk(struct rcu_head *rcu)
126 {
127         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
128         audit_put_chunk(chunk);
129 }
130
131 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
132 {
133         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
134         call_rcu(&chunk->head, __put_chunk);
135 }
136
137 static struct audit_chunk *alloc_chunk(int count)
138 {
139         struct audit_chunk *chunk;
140         size_t size;
141         int i;
142
143         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
144         chunk = kzalloc(size, GFP_KERNEL);
145         if (!chunk)
146                 return NULL;
147
148         INIT_LIST_HEAD(&chunk->hash);
149         INIT_LIST_HEAD(&chunk->trees);
150         chunk->count = count;
151         atomic_long_set(&chunk->refs, 1);
152         for (i = 0; i < count; i++) {
153                 INIT_LIST_HEAD(&chunk->owners[i].list);
154                 chunk->owners[i].index = i;
155         }
156         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
157         return chunk;
158 }
159
160 enum {HASH_SIZE = 128};
161 static struct list_head chunk_hash_heads[HASH_SIZE];
162 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
163
164 static inline struct list_head *chunk_hash(const struct inode *inode)
165 {
166         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
167         return chunk_hash_heads + n % HASH_SIZE;
168 }
169
170 /* hash_lock & entry->lock is held by caller */
171 static void insert_hash(struct audit_chunk *chunk)
172 {
173         struct fsnotify_mark *entry = &chunk->mark;
174         struct list_head *list;
175
176         if (!entry->i.inode)
177                 return;
178         list = chunk_hash(entry->i.inode);
179         list_add_rcu(&chunk->hash, list);
180 }
181
182 /* called under rcu_read_lock */
183 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
184 {
185         struct list_head *list = chunk_hash(inode);
186         struct audit_chunk *p;
187
188         list_for_each_entry_rcu(p, list, hash) {
189                 /* mark.inode may have gone NULL, but who cares? */
190                 if (p->mark.i.inode == inode) {
191                         atomic_long_inc(&p->refs);
192                         return p;
193                 }
194         }
195         return NULL;
196 }
197
198 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
199 {
200         int n;
201         for (n = 0; n < chunk->count; n++)
202                 if (chunk->owners[n].owner == tree)
203                         return 1;
204         return 0;
205 }
206
207 /* tagging and untagging inodes with trees */
208
209 static struct audit_chunk *find_chunk(struct node *p)
210 {
211         int index = p->index & ~(1U<<31);
212         p -= index;
213         return container_of(p, struct audit_chunk, owners[0]);
214 }
215
216 static void untag_chunk(struct node *p)
217 {
218         struct audit_chunk *chunk = find_chunk(p);
219         struct fsnotify_mark *entry = &chunk->mark;
220         struct audit_chunk *new = NULL;
221         struct audit_tree *owner;
222         int size = chunk->count - 1;
223         int i, j;
224
225         fsnotify_get_mark(entry);
226
227         spin_unlock(&hash_lock);
228
229         if (size)
230                 new = alloc_chunk(size);
231
232         spin_lock(&entry->lock);
233         if (chunk->dead || !entry->i.inode) {
234                 spin_unlock(&entry->lock);
235                 if (new)
236                         free_chunk(new);
237                 goto out;
238         }
239
240         owner = p->owner;
241
242         if (!size) {
243                 chunk->dead = 1;
244                 spin_lock(&hash_lock);
245                 list_del_init(&chunk->trees);
246                 if (owner->root == chunk)
247                         owner->root = NULL;
248                 list_del_init(&p->list);
249                 list_del_rcu(&chunk->hash);
250                 spin_unlock(&hash_lock);
251                 spin_unlock(&entry->lock);
252                 fsnotify_destroy_mark(entry);
253                 goto out;
254         }
255
256         if (!new)
257                 goto Fallback;
258
259         fsnotify_duplicate_mark(&new->mark, entry);
260         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
261                 fsnotify_put_mark(&new->mark);
262                 goto Fallback;
263         }
264
265         chunk->dead = 1;
266         spin_lock(&hash_lock);
267         list_replace_init(&chunk->trees, &new->trees);
268         if (owner->root == chunk) {
269                 list_del_init(&owner->same_root);
270                 owner->root = NULL;
271         }
272
273         for (i = j = 0; j <= size; i++, j++) {
274                 struct audit_tree *s;
275                 if (&chunk->owners[j] == p) {
276                         list_del_init(&p->list);
277                         i--;
278                         continue;
279                 }
280                 s = chunk->owners[j].owner;
281                 new->owners[i].owner = s;
282                 new->owners[i].index = chunk->owners[j].index - j + i;
283                 if (!s) /* result of earlier fallback */
284                         continue;
285                 get_tree(s);
286                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
287         }
288
289         list_replace_rcu(&chunk->hash, &new->hash);
290         list_for_each_entry(owner, &new->trees, same_root)
291                 owner->root = new;
292         spin_unlock(&hash_lock);
293         spin_unlock(&entry->lock);
294         fsnotify_destroy_mark(entry);
295         goto out;
296
297 Fallback:
298         // do the best we can
299         spin_lock(&hash_lock);
300         if (owner->root == chunk) {
301                 list_del_init(&owner->same_root);
302                 owner->root = NULL;
303         }
304         list_del_init(&p->list);
305         p->owner = NULL;
306         put_tree(owner);
307         spin_unlock(&hash_lock);
308         spin_unlock(&entry->lock);
309 out:
310         fsnotify_put_mark(entry);
311         spin_lock(&hash_lock);
312 }
313
314 static int create_chunk(struct inode *inode, struct audit_tree *tree)
315 {
316         struct fsnotify_mark *entry;
317         struct audit_chunk *chunk = alloc_chunk(1);
318         if (!chunk)
319                 return -ENOMEM;
320
321         entry = &chunk->mark;
322         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
323                 fsnotify_put_mark(entry);
324                 return -ENOSPC;
325         }
326
327         spin_lock(&entry->lock);
328         spin_lock(&hash_lock);
329         if (tree->goner) {
330                 spin_unlock(&hash_lock);
331                 chunk->dead = 1;
332                 spin_unlock(&entry->lock);
333                 fsnotify_get_mark(entry);
334                 fsnotify_destroy_mark(entry);
335                 fsnotify_put_mark(entry);
336                 return 0;
337         }
338         chunk->owners[0].index = (1U << 31);
339         chunk->owners[0].owner = tree;
340         get_tree(tree);
341         list_add(&chunk->owners[0].list, &tree->chunks);
342         if (!tree->root) {
343                 tree->root = chunk;
344                 list_add(&tree->same_root, &chunk->trees);
345         }
346         insert_hash(chunk);
347         spin_unlock(&hash_lock);
348         spin_unlock(&entry->lock);
349         return 0;
350 }
351
352 /* the first tagged inode becomes root of tree */
353 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
354 {
355         struct fsnotify_mark *old_entry, *chunk_entry;
356         struct audit_tree *owner;
357         struct audit_chunk *chunk, *old;
358         struct node *p;
359         int n;
360
361         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
362         if (!old_entry)
363                 return create_chunk(inode, tree);
364
365         old = container_of(old_entry, struct audit_chunk, mark);
366
367         /* are we already there? */
368         spin_lock(&hash_lock);
369         for (n = 0; n < old->count; n++) {
370                 if (old->owners[n].owner == tree) {
371                         spin_unlock(&hash_lock);
372                         fsnotify_put_mark(old_entry);
373                         return 0;
374                 }
375         }
376         spin_unlock(&hash_lock);
377
378         chunk = alloc_chunk(old->count + 1);
379         if (!chunk) {
380                 fsnotify_put_mark(old_entry);
381                 return -ENOMEM;
382         }
383
384         chunk_entry = &chunk->mark;
385
386         spin_lock(&old_entry->lock);
387         if (!old_entry->i.inode) {
388                 /* old_entry is being shot, lets just lie */
389                 spin_unlock(&old_entry->lock);
390                 fsnotify_put_mark(old_entry);
391                 free_chunk(chunk);
392                 return -ENOENT;
393         }
394
395         fsnotify_duplicate_mark(chunk_entry, old_entry);
396         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
397                 spin_unlock(&old_entry->lock);
398                 fsnotify_put_mark(chunk_entry);
399                 fsnotify_put_mark(old_entry);
400                 return -ENOSPC;
401         }
402
403         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
404         spin_lock(&chunk_entry->lock);
405         spin_lock(&hash_lock);
406
407         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
408         if (tree->goner) {
409                 spin_unlock(&hash_lock);
410                 chunk->dead = 1;
411                 spin_unlock(&chunk_entry->lock);
412                 spin_unlock(&old_entry->lock);
413
414                 fsnotify_get_mark(chunk_entry);
415                 fsnotify_destroy_mark(chunk_entry);
416
417                 fsnotify_put_mark(chunk_entry);
418                 fsnotify_put_mark(old_entry);
419                 return 0;
420         }
421         list_replace_init(&old->trees, &chunk->trees);
422         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
423                 struct audit_tree *s = old->owners[n].owner;
424                 p->owner = s;
425                 p->index = old->owners[n].index;
426                 if (!s) /* result of fallback in untag */
427                         continue;
428                 get_tree(s);
429                 list_replace_init(&old->owners[n].list, &p->list);
430         }
431         p->index = (chunk->count - 1) | (1U<<31);
432         p->owner = tree;
433         get_tree(tree);
434         list_add(&p->list, &tree->chunks);
435         list_replace_rcu(&old->hash, &chunk->hash);
436         list_for_each_entry(owner, &chunk->trees, same_root)
437                 owner->root = chunk;
438         old->dead = 1;
439         if (!tree->root) {
440                 tree->root = chunk;
441                 list_add(&tree->same_root, &chunk->trees);
442         }
443         spin_unlock(&hash_lock);
444         spin_unlock(&chunk_entry->lock);
445         spin_unlock(&old_entry->lock);
446         fsnotify_destroy_mark(old_entry);
447         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
448         return 0;
449 }
450
451 static void kill_rules(struct audit_tree *tree)
452 {
453         struct audit_krule *rule, *next;
454         struct audit_entry *entry;
455         struct audit_buffer *ab;
456
457         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
458                 entry = container_of(rule, struct audit_entry, rule);
459
460                 list_del_init(&rule->rlist);
461                 if (rule->tree) {
462                         /* not a half-baked one */
463                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
464                         audit_log_format(ab, "op=");
465                         audit_log_string(ab, "remove rule");
466                         audit_log_format(ab, " dir=");
467                         audit_log_untrustedstring(ab, rule->tree->pathname);
468                         audit_log_key(ab, rule->filterkey);
469                         audit_log_format(ab, " list=%d res=1", rule->listnr);
470                         audit_log_end(ab);
471                         rule->tree = NULL;
472                         list_del_rcu(&entry->list);
473                         list_del(&entry->rule.list);
474                         call_rcu(&entry->rcu, audit_free_rule_rcu);
475                 }
476         }
477 }
478
479 /*
480  * finish killing struct audit_tree
481  */
482 static void prune_one(struct audit_tree *victim)
483 {
484         spin_lock(&hash_lock);
485         while (!list_empty(&victim->chunks)) {
486                 struct node *p;
487
488                 p = list_entry(victim->chunks.next, struct node, list);
489
490                 untag_chunk(p);
491         }
492         spin_unlock(&hash_lock);
493         put_tree(victim);
494 }
495
496 /* trim the uncommitted chunks from tree */
497
498 static void trim_marked(struct audit_tree *tree)
499 {
500         struct list_head *p, *q;
501         spin_lock(&hash_lock);
502         if (tree->goner) {
503                 spin_unlock(&hash_lock);
504                 return;
505         }
506         /* reorder */
507         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
508                 struct node *node = list_entry(p, struct node, list);
509                 q = p->next;
510                 if (node->index & (1U<<31)) {
511                         list_del_init(p);
512                         list_add(p, &tree->chunks);
513                 }
514         }
515
516         while (!list_empty(&tree->chunks)) {
517                 struct node *node;
518
519                 node = list_entry(tree->chunks.next, struct node, list);
520
521                 /* have we run out of marked? */
522                 if (!(node->index & (1U<<31)))
523                         break;
524
525                 untag_chunk(node);
526         }
527         if (!tree->root && !tree->goner) {
528                 tree->goner = 1;
529                 spin_unlock(&hash_lock);
530                 mutex_lock(&audit_filter_mutex);
531                 kill_rules(tree);
532                 list_del_init(&tree->list);
533                 mutex_unlock(&audit_filter_mutex);
534                 prune_one(tree);
535         } else {
536                 spin_unlock(&hash_lock);
537         }
538 }
539
540 static void audit_schedule_prune(void);
541
542 /* called with audit_filter_mutex */
543 int audit_remove_tree_rule(struct audit_krule *rule)
544 {
545         struct audit_tree *tree;
546         tree = rule->tree;
547         if (tree) {
548                 spin_lock(&hash_lock);
549                 list_del_init(&rule->rlist);
550                 if (list_empty(&tree->rules) && !tree->goner) {
551                         tree->root = NULL;
552                         list_del_init(&tree->same_root);
553                         tree->goner = 1;
554                         list_move(&tree->list, &prune_list);
555                         rule->tree = NULL;
556                         spin_unlock(&hash_lock);
557                         audit_schedule_prune();
558                         return 1;
559                 }
560                 rule->tree = NULL;
561                 spin_unlock(&hash_lock);
562                 return 1;
563         }
564         return 0;
565 }
566
567 static int compare_root(struct vfsmount *mnt, void *arg)
568 {
569         return mnt->mnt_root->d_inode == arg;
570 }
571
572 void audit_trim_trees(void)
573 {
574         struct list_head cursor;
575
576         mutex_lock(&audit_filter_mutex);
577         list_add(&cursor, &tree_list);
578         while (cursor.next != &tree_list) {
579                 struct audit_tree *tree;
580                 struct path path;
581                 struct vfsmount *root_mnt;
582                 struct node *node;
583                 int err;
584
585                 tree = container_of(cursor.next, struct audit_tree, list);
586                 get_tree(tree);
587                 list_del(&cursor);
588                 list_add(&cursor, &tree->list);
589                 mutex_unlock(&audit_filter_mutex);
590
591                 err = kern_path(tree->pathname, 0, &path);
592                 if (err)
593                         goto skip_it;
594
595                 root_mnt = collect_mounts(&path);
596                 path_put(&path);
597                 if (!root_mnt)
598                         goto skip_it;
599
600                 spin_lock(&hash_lock);
601                 list_for_each_entry(node, &tree->chunks, list) {
602                         struct audit_chunk *chunk = find_chunk(node);
603                         /* this could be NULL if the watch is dying else where... */
604                         struct inode *inode = chunk->mark.i.inode;
605                         node->index |= 1U<<31;
606                         if (iterate_mounts(compare_root, inode, root_mnt))
607                                 node->index &= ~(1U<<31);
608                 }
609                 spin_unlock(&hash_lock);
610                 trim_marked(tree);
611                 drop_collected_mounts(root_mnt);
612 skip_it:
613                 put_tree(tree);
614                 mutex_lock(&audit_filter_mutex);
615         }
616         list_del(&cursor);
617         mutex_unlock(&audit_filter_mutex);
618 }
619
620 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
621 {
622
623         if (pathname[0] != '/' ||
624             rule->listnr != AUDIT_FILTER_EXIT ||
625             op != Audit_equal ||
626             rule->inode_f || rule->watch || rule->tree)
627                 return -EINVAL;
628         rule->tree = alloc_tree(pathname);
629         if (!rule->tree)
630                 return -ENOMEM;
631         return 0;
632 }
633
634 void audit_put_tree(struct audit_tree *tree)
635 {
636         put_tree(tree);
637 }
638
639 static int tag_mount(struct vfsmount *mnt, void *arg)
640 {
641         return tag_chunk(mnt->mnt_root->d_inode, arg);
642 }
643
644 /* called with audit_filter_mutex */
645 int audit_add_tree_rule(struct audit_krule *rule)
646 {
647         struct audit_tree *seed = rule->tree, *tree;
648         struct path path;
649         struct vfsmount *mnt;
650         int err;
651
652         list_for_each_entry(tree, &tree_list, list) {
653                 if (!strcmp(seed->pathname, tree->pathname)) {
654                         put_tree(seed);
655                         rule->tree = tree;
656                         list_add(&rule->rlist, &tree->rules);
657                         return 0;
658                 }
659         }
660         tree = seed;
661         list_add(&tree->list, &tree_list);
662         list_add(&rule->rlist, &tree->rules);
663         /* do not set rule->tree yet */
664         mutex_unlock(&audit_filter_mutex);
665
666         err = kern_path(tree->pathname, 0, &path);
667         if (err)
668                 goto Err;
669         mnt = collect_mounts(&path);
670         path_put(&path);
671         if (!mnt) {
672                 err = -ENOMEM;
673                 goto Err;
674         }
675
676         get_tree(tree);
677         err = iterate_mounts(tag_mount, tree, mnt);
678         drop_collected_mounts(mnt);
679
680         if (!err) {
681                 struct node *node;
682                 spin_lock(&hash_lock);
683                 list_for_each_entry(node, &tree->chunks, list)
684                         node->index &= ~(1U<<31);
685                 spin_unlock(&hash_lock);
686         } else {
687                 trim_marked(tree);
688                 goto Err;
689         }
690
691         mutex_lock(&audit_filter_mutex);
692         if (list_empty(&rule->rlist)) {
693                 put_tree(tree);
694                 return -ENOENT;
695         }
696         rule->tree = tree;
697         put_tree(tree);
698
699         return 0;
700 Err:
701         mutex_lock(&audit_filter_mutex);
702         list_del_init(&tree->list);
703         list_del_init(&tree->rules);
704         put_tree(tree);
705         return err;
706 }
707
708 int audit_tag_tree(char *old, char *new)
709 {
710         struct list_head cursor, barrier;
711         int failed = 0;
712         struct path path1, path2;
713         struct vfsmount *tagged;
714         int err;
715
716         err = kern_path(new, 0, &path2);
717         if (err)
718                 return err;
719         tagged = collect_mounts(&path2);
720         path_put(&path2);
721         if (!tagged)
722                 return -ENOMEM;
723
724         err = kern_path(old, 0, &path1);
725         if (err) {
726                 drop_collected_mounts(tagged);
727                 return err;
728         }
729
730         mutex_lock(&audit_filter_mutex);
731         list_add(&barrier, &tree_list);
732         list_add(&cursor, &barrier);
733
734         while (cursor.next != &tree_list) {
735                 struct audit_tree *tree;
736                 int good_one = 0;
737
738                 tree = container_of(cursor.next, struct audit_tree, list);
739                 get_tree(tree);
740                 list_del(&cursor);
741                 list_add(&cursor, &tree->list);
742                 mutex_unlock(&audit_filter_mutex);
743
744                 err = kern_path(tree->pathname, 0, &path2);
745                 if (!err) {
746                         good_one = path_is_under(&path1, &path2);
747                         path_put(&path2);
748                 }
749
750                 if (!good_one) {
751                         put_tree(tree);
752                         mutex_lock(&audit_filter_mutex);
753                         continue;
754                 }
755
756                 failed = iterate_mounts(tag_mount, tree, tagged);
757                 if (failed) {
758                         put_tree(tree);
759                         mutex_lock(&audit_filter_mutex);
760                         break;
761                 }
762
763                 mutex_lock(&audit_filter_mutex);
764                 spin_lock(&hash_lock);
765                 if (!tree->goner) {
766                         list_del(&tree->list);
767                         list_add(&tree->list, &tree_list);
768                 }
769                 spin_unlock(&hash_lock);
770                 put_tree(tree);
771         }
772
773         while (barrier.prev != &tree_list) {
774                 struct audit_tree *tree;
775
776                 tree = container_of(barrier.prev, struct audit_tree, list);
777                 get_tree(tree);
778                 list_del(&tree->list);
779                 list_add(&tree->list, &barrier);
780                 mutex_unlock(&audit_filter_mutex);
781
782                 if (!failed) {
783                         struct node *node;
784                         spin_lock(&hash_lock);
785                         list_for_each_entry(node, &tree->chunks, list)
786                                 node->index &= ~(1U<<31);
787                         spin_unlock(&hash_lock);
788                 } else {
789                         trim_marked(tree);
790                 }
791
792                 put_tree(tree);
793                 mutex_lock(&audit_filter_mutex);
794         }
795         list_del(&barrier);
796         list_del(&cursor);
797         mutex_unlock(&audit_filter_mutex);
798         path_put(&path1);
799         drop_collected_mounts(tagged);
800         return failed;
801 }
802
803 /*
804  * That gets run when evict_chunk() ends up needing to kill audit_tree.
805  * Runs from a separate thread.
806  */
807 static int prune_tree_thread(void *unused)
808 {
809         mutex_lock(&audit_cmd_mutex);
810         mutex_lock(&audit_filter_mutex);
811
812         while (!list_empty(&prune_list)) {
813                 struct audit_tree *victim;
814
815                 victim = list_entry(prune_list.next, struct audit_tree, list);
816                 list_del_init(&victim->list);
817
818                 mutex_unlock(&audit_filter_mutex);
819
820                 prune_one(victim);
821
822                 mutex_lock(&audit_filter_mutex);
823         }
824
825         mutex_unlock(&audit_filter_mutex);
826         mutex_unlock(&audit_cmd_mutex);
827         return 0;
828 }
829
830 static void audit_schedule_prune(void)
831 {
832         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
833 }
834
835 /*
836  * ... and that one is done if evict_chunk() decides to delay until the end
837  * of syscall.  Runs synchronously.
838  */
839 void audit_kill_trees(struct list_head *list)
840 {
841         mutex_lock(&audit_cmd_mutex);
842         mutex_lock(&audit_filter_mutex);
843
844         while (!list_empty(list)) {
845                 struct audit_tree *victim;
846
847                 victim = list_entry(list->next, struct audit_tree, list);
848                 kill_rules(victim);
849                 list_del_init(&victim->list);
850
851                 mutex_unlock(&audit_filter_mutex);
852
853                 prune_one(victim);
854
855                 mutex_lock(&audit_filter_mutex);
856         }
857
858         mutex_unlock(&audit_filter_mutex);
859         mutex_unlock(&audit_cmd_mutex);
860 }
861
862 /*
863  *  Here comes the stuff asynchronous to auditctl operations
864  */
865
866 static void evict_chunk(struct audit_chunk *chunk)
867 {
868         struct audit_tree *owner;
869         struct list_head *postponed = audit_killed_trees();
870         int need_prune = 0;
871         int n;
872
873         if (chunk->dead)
874                 return;
875
876         chunk->dead = 1;
877         mutex_lock(&audit_filter_mutex);
878         spin_lock(&hash_lock);
879         while (!list_empty(&chunk->trees)) {
880                 owner = list_entry(chunk->trees.next,
881                                    struct audit_tree, same_root);
882                 owner->goner = 1;
883                 owner->root = NULL;
884                 list_del_init(&owner->same_root);
885                 spin_unlock(&hash_lock);
886                 if (!postponed) {
887                         kill_rules(owner);
888                         list_move(&owner->list, &prune_list);
889                         need_prune = 1;
890                 } else {
891                         list_move(&owner->list, postponed);
892                 }
893                 spin_lock(&hash_lock);
894         }
895         list_del_rcu(&chunk->hash);
896         for (n = 0; n < chunk->count; n++)
897                 list_del_init(&chunk->owners[n].list);
898         spin_unlock(&hash_lock);
899         if (need_prune)
900                 audit_schedule_prune();
901         mutex_unlock(&audit_filter_mutex);
902 }
903
904 static int audit_tree_handle_event(struct fsnotify_group *group,
905                                    struct fsnotify_mark *inode_mark,
906                                    struct fsnotify_mark *vfsmonut_mark,
907                                    struct fsnotify_event *event)
908 {
909         BUG();
910         return -EOPNOTSUPP;
911 }
912
913 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
914 {
915         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
916
917         evict_chunk(chunk);
918         fsnotify_put_mark(entry);
919 }
920
921 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
922                                   struct fsnotify_mark *inode_mark,
923                                   struct fsnotify_mark *vfsmount_mark,
924                                   __u32 mask, void *data, int data_type)
925 {
926         return false;
927 }
928
929 static const struct fsnotify_ops audit_tree_ops = {
930         .handle_event = audit_tree_handle_event,
931         .should_send_event = audit_tree_send_event,
932         .free_group_priv = NULL,
933         .free_event_priv = NULL,
934         .freeing_mark = audit_tree_freeing_mark,
935 };
936
937 static int __init audit_tree_init(void)
938 {
939         int i;
940
941         audit_tree_group = fsnotify_alloc_group(&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);