microblaze: fix clone syscall
[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 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, audit_tree_group);
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, audit_tree_group);
295         fsnotify_put_mark(&new->mark);  /* drop initial reference */
296         goto out;
297
298 Fallback:
299         // do the best we can
300         spin_lock(&hash_lock);
301         if (owner->root == chunk) {
302                 list_del_init(&owner->same_root);
303                 owner->root = NULL;
304         }
305         list_del_init(&p->list);
306         p->owner = NULL;
307         put_tree(owner);
308         spin_unlock(&hash_lock);
309         spin_unlock(&entry->lock);
310 out:
311         fsnotify_put_mark(entry);
312         spin_lock(&hash_lock);
313 }
314
315 static int create_chunk(struct inode *inode, struct audit_tree *tree)
316 {
317         struct fsnotify_mark *entry;
318         struct audit_chunk *chunk = alloc_chunk(1);
319         if (!chunk)
320                 return -ENOMEM;
321
322         entry = &chunk->mark;
323         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
324                 fsnotify_put_mark(entry);
325                 return -ENOSPC;
326         }
327
328         spin_lock(&entry->lock);
329         spin_lock(&hash_lock);
330         if (tree->goner) {
331                 spin_unlock(&hash_lock);
332                 chunk->dead = 1;
333                 spin_unlock(&entry->lock);
334                 fsnotify_destroy_mark(entry, audit_tree_group);
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         fsnotify_put_mark(entry);       /* drop initial reference */
350         return 0;
351 }
352
353 /* the first tagged inode becomes root of tree */
354 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
355 {
356         struct fsnotify_mark *old_entry, *chunk_entry;
357         struct audit_tree *owner;
358         struct audit_chunk *chunk, *old;
359         struct node *p;
360         int n;
361
362         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
363         if (!old_entry)
364                 return create_chunk(inode, tree);
365
366         old = container_of(old_entry, struct audit_chunk, mark);
367
368         /* are we already there? */
369         spin_lock(&hash_lock);
370         for (n = 0; n < old->count; n++) {
371                 if (old->owners[n].owner == tree) {
372                         spin_unlock(&hash_lock);
373                         fsnotify_put_mark(old_entry);
374                         return 0;
375                 }
376         }
377         spin_unlock(&hash_lock);
378
379         chunk = alloc_chunk(old->count + 1);
380         if (!chunk) {
381                 fsnotify_put_mark(old_entry);
382                 return -ENOMEM;
383         }
384
385         chunk_entry = &chunk->mark;
386
387         spin_lock(&old_entry->lock);
388         if (!old_entry->i.inode) {
389                 /* old_entry is being shot, lets just lie */
390                 spin_unlock(&old_entry->lock);
391                 fsnotify_put_mark(old_entry);
392                 free_chunk(chunk);
393                 return -ENOENT;
394         }
395
396         fsnotify_duplicate_mark(chunk_entry, old_entry);
397         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
398                 spin_unlock(&old_entry->lock);
399                 fsnotify_put_mark(chunk_entry);
400                 fsnotify_put_mark(old_entry);
401                 return -ENOSPC;
402         }
403
404         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
405         spin_lock(&chunk_entry->lock);
406         spin_lock(&hash_lock);
407
408         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
409         if (tree->goner) {
410                 spin_unlock(&hash_lock);
411                 chunk->dead = 1;
412                 spin_unlock(&chunk_entry->lock);
413                 spin_unlock(&old_entry->lock);
414
415                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
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, audit_tree_group);
447         fsnotify_put_mark(chunk_entry); /* drop initial reference */
448         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
449         return 0;
450 }
451
452 static void audit_log_remove_rule(struct audit_krule *rule)
453 {
454         struct audit_buffer *ab;
455
456         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
457         if (unlikely(!ab))
458                 return;
459         audit_log_format(ab, "op=");
460         audit_log_string(ab, "remove rule");
461         audit_log_format(ab, " dir=");
462         audit_log_untrustedstring(ab, rule->tree->pathname);
463         audit_log_key(ab, rule->filterkey);
464         audit_log_format(ab, " list=%d res=1", rule->listnr);
465         audit_log_end(ab);
466 }
467
468 static void kill_rules(struct audit_tree *tree)
469 {
470         struct audit_krule *rule, *next;
471         struct audit_entry *entry;
472
473         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
474                 entry = container_of(rule, struct audit_entry, rule);
475
476                 list_del_init(&rule->rlist);
477                 if (rule->tree) {
478                         /* not a half-baked one */
479                         audit_log_remove_rule(rule);
480                         rule->tree = NULL;
481                         list_del_rcu(&entry->list);
482                         list_del(&entry->rule.list);
483                         call_rcu(&entry->rcu, audit_free_rule_rcu);
484                 }
485         }
486 }
487
488 /*
489  * finish killing struct audit_tree
490  */
491 static void prune_one(struct audit_tree *victim)
492 {
493         spin_lock(&hash_lock);
494         while (!list_empty(&victim->chunks)) {
495                 struct node *p;
496
497                 p = list_entry(victim->chunks.next, struct node, list);
498
499                 untag_chunk(p);
500         }
501         spin_unlock(&hash_lock);
502         put_tree(victim);
503 }
504
505 /* trim the uncommitted chunks from tree */
506
507 static void trim_marked(struct audit_tree *tree)
508 {
509         struct list_head *p, *q;
510         spin_lock(&hash_lock);
511         if (tree->goner) {
512                 spin_unlock(&hash_lock);
513                 return;
514         }
515         /* reorder */
516         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
517                 struct node *node = list_entry(p, struct node, list);
518                 q = p->next;
519                 if (node->index & (1U<<31)) {
520                         list_del_init(p);
521                         list_add(p, &tree->chunks);
522                 }
523         }
524
525         while (!list_empty(&tree->chunks)) {
526                 struct node *node;
527
528                 node = list_entry(tree->chunks.next, struct node, list);
529
530                 /* have we run out of marked? */
531                 if (!(node->index & (1U<<31)))
532                         break;
533
534                 untag_chunk(node);
535         }
536         if (!tree->root && !tree->goner) {
537                 tree->goner = 1;
538                 spin_unlock(&hash_lock);
539                 mutex_lock(&audit_filter_mutex);
540                 kill_rules(tree);
541                 list_del_init(&tree->list);
542                 mutex_unlock(&audit_filter_mutex);
543                 prune_one(tree);
544         } else {
545                 spin_unlock(&hash_lock);
546         }
547 }
548
549 static void audit_schedule_prune(void);
550
551 /* called with audit_filter_mutex */
552 int audit_remove_tree_rule(struct audit_krule *rule)
553 {
554         struct audit_tree *tree;
555         tree = rule->tree;
556         if (tree) {
557                 spin_lock(&hash_lock);
558                 list_del_init(&rule->rlist);
559                 if (list_empty(&tree->rules) && !tree->goner) {
560                         tree->root = NULL;
561                         list_del_init(&tree->same_root);
562                         tree->goner = 1;
563                         list_move(&tree->list, &prune_list);
564                         rule->tree = NULL;
565                         spin_unlock(&hash_lock);
566                         audit_schedule_prune();
567                         return 1;
568                 }
569                 rule->tree = NULL;
570                 spin_unlock(&hash_lock);
571                 return 1;
572         }
573         return 0;
574 }
575
576 static int compare_root(struct vfsmount *mnt, void *arg)
577 {
578         return mnt->mnt_root->d_inode == arg;
579 }
580
581 void audit_trim_trees(void)
582 {
583         struct list_head cursor;
584
585         mutex_lock(&audit_filter_mutex);
586         list_add(&cursor, &tree_list);
587         while (cursor.next != &tree_list) {
588                 struct audit_tree *tree;
589                 struct path path;
590                 struct vfsmount *root_mnt;
591                 struct node *node;
592                 int err;
593
594                 tree = container_of(cursor.next, struct audit_tree, list);
595                 get_tree(tree);
596                 list_del(&cursor);
597                 list_add(&cursor, &tree->list);
598                 mutex_unlock(&audit_filter_mutex);
599
600                 err = kern_path(tree->pathname, 0, &path);
601                 if (err)
602                         goto skip_it;
603
604                 root_mnt = collect_mounts(&path);
605                 path_put(&path);
606                 if (IS_ERR(root_mnt))
607                         goto skip_it;
608
609                 spin_lock(&hash_lock);
610                 list_for_each_entry(node, &tree->chunks, list) {
611                         struct audit_chunk *chunk = find_chunk(node);
612                         /* this could be NULL if the watch is dying else where... */
613                         struct inode *inode = chunk->mark.i.inode;
614                         node->index |= 1U<<31;
615                         if (iterate_mounts(compare_root, inode, root_mnt))
616                                 node->index &= ~(1U<<31);
617                 }
618                 spin_unlock(&hash_lock);
619                 trim_marked(tree);
620                 drop_collected_mounts(root_mnt);
621 skip_it:
622                 put_tree(tree);
623                 mutex_lock(&audit_filter_mutex);
624         }
625         list_del(&cursor);
626         mutex_unlock(&audit_filter_mutex);
627 }
628
629 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
630 {
631
632         if (pathname[0] != '/' ||
633             rule->listnr != AUDIT_FILTER_EXIT ||
634             op != Audit_equal ||
635             rule->inode_f || rule->watch || rule->tree)
636                 return -EINVAL;
637         rule->tree = alloc_tree(pathname);
638         if (!rule->tree)
639                 return -ENOMEM;
640         return 0;
641 }
642
643 void audit_put_tree(struct audit_tree *tree)
644 {
645         put_tree(tree);
646 }
647
648 static int tag_mount(struct vfsmount *mnt, void *arg)
649 {
650         return tag_chunk(mnt->mnt_root->d_inode, arg);
651 }
652
653 /* called with audit_filter_mutex */
654 int audit_add_tree_rule(struct audit_krule *rule)
655 {
656         struct audit_tree *seed = rule->tree, *tree;
657         struct path path;
658         struct vfsmount *mnt;
659         int err;
660
661         rule->tree = NULL;
662         list_for_each_entry(tree, &tree_list, list) {
663                 if (!strcmp(seed->pathname, tree->pathname)) {
664                         put_tree(seed);
665                         rule->tree = tree;
666                         list_add(&rule->rlist, &tree->rules);
667                         return 0;
668                 }
669         }
670         tree = seed;
671         list_add(&tree->list, &tree_list);
672         list_add(&rule->rlist, &tree->rules);
673         /* do not set rule->tree yet */
674         mutex_unlock(&audit_filter_mutex);
675
676         err = kern_path(tree->pathname, 0, &path);
677         if (err)
678                 goto Err;
679         mnt = collect_mounts(&path);
680         path_put(&path);
681         if (IS_ERR(mnt)) {
682                 err = PTR_ERR(mnt);
683                 goto Err;
684         }
685
686         get_tree(tree);
687         err = iterate_mounts(tag_mount, tree, mnt);
688         drop_collected_mounts(mnt);
689
690         if (!err) {
691                 struct node *node;
692                 spin_lock(&hash_lock);
693                 list_for_each_entry(node, &tree->chunks, list)
694                         node->index &= ~(1U<<31);
695                 spin_unlock(&hash_lock);
696         } else {
697                 trim_marked(tree);
698                 goto Err;
699         }
700
701         mutex_lock(&audit_filter_mutex);
702         if (list_empty(&rule->rlist)) {
703                 put_tree(tree);
704                 return -ENOENT;
705         }
706         rule->tree = tree;
707         put_tree(tree);
708
709         return 0;
710 Err:
711         mutex_lock(&audit_filter_mutex);
712         list_del_init(&tree->list);
713         list_del_init(&tree->rules);
714         put_tree(tree);
715         return err;
716 }
717
718 int audit_tag_tree(char *old, char *new)
719 {
720         struct list_head cursor, barrier;
721         int failed = 0;
722         struct path path1, path2;
723         struct vfsmount *tagged;
724         int err;
725
726         err = kern_path(new, 0, &path2);
727         if (err)
728                 return err;
729         tagged = collect_mounts(&path2);
730         path_put(&path2);
731         if (IS_ERR(tagged))
732                 return PTR_ERR(tagged);
733
734         err = kern_path(old, 0, &path1);
735         if (err) {
736                 drop_collected_mounts(tagged);
737                 return err;
738         }
739
740         mutex_lock(&audit_filter_mutex);
741         list_add(&barrier, &tree_list);
742         list_add(&cursor, &barrier);
743
744         while (cursor.next != &tree_list) {
745                 struct audit_tree *tree;
746                 int good_one = 0;
747
748                 tree = container_of(cursor.next, struct audit_tree, list);
749                 get_tree(tree);
750                 list_del(&cursor);
751                 list_add(&cursor, &tree->list);
752                 mutex_unlock(&audit_filter_mutex);
753
754                 err = kern_path(tree->pathname, 0, &path2);
755                 if (!err) {
756                         good_one = path_is_under(&path1, &path2);
757                         path_put(&path2);
758                 }
759
760                 if (!good_one) {
761                         put_tree(tree);
762                         mutex_lock(&audit_filter_mutex);
763                         continue;
764                 }
765
766                 failed = iterate_mounts(tag_mount, tree, tagged);
767                 if (failed) {
768                         put_tree(tree);
769                         mutex_lock(&audit_filter_mutex);
770                         break;
771                 }
772
773                 mutex_lock(&audit_filter_mutex);
774                 spin_lock(&hash_lock);
775                 if (!tree->goner) {
776                         list_del(&tree->list);
777                         list_add(&tree->list, &tree_list);
778                 }
779                 spin_unlock(&hash_lock);
780                 put_tree(tree);
781         }
782
783         while (barrier.prev != &tree_list) {
784                 struct audit_tree *tree;
785
786                 tree = container_of(barrier.prev, struct audit_tree, list);
787                 get_tree(tree);
788                 list_del(&tree->list);
789                 list_add(&tree->list, &barrier);
790                 mutex_unlock(&audit_filter_mutex);
791
792                 if (!failed) {
793                         struct node *node;
794                         spin_lock(&hash_lock);
795                         list_for_each_entry(node, &tree->chunks, list)
796                                 node->index &= ~(1U<<31);
797                         spin_unlock(&hash_lock);
798                 } else {
799                         trim_marked(tree);
800                 }
801
802                 put_tree(tree);
803                 mutex_lock(&audit_filter_mutex);
804         }
805         list_del(&barrier);
806         list_del(&cursor);
807         mutex_unlock(&audit_filter_mutex);
808         path_put(&path1);
809         drop_collected_mounts(tagged);
810         return failed;
811 }
812
813 /*
814  * That gets run when evict_chunk() ends up needing to kill audit_tree.
815  * Runs from a separate thread.
816  */
817 static int prune_tree_thread(void *unused)
818 {
819         mutex_lock(&audit_cmd_mutex);
820         mutex_lock(&audit_filter_mutex);
821
822         while (!list_empty(&prune_list)) {
823                 struct audit_tree *victim;
824
825                 victim = list_entry(prune_list.next, struct audit_tree, list);
826                 list_del_init(&victim->list);
827
828                 mutex_unlock(&audit_filter_mutex);
829
830                 prune_one(victim);
831
832                 mutex_lock(&audit_filter_mutex);
833         }
834
835         mutex_unlock(&audit_filter_mutex);
836         mutex_unlock(&audit_cmd_mutex);
837         return 0;
838 }
839
840 static void audit_schedule_prune(void)
841 {
842         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
843 }
844
845 /*
846  * ... and that one is done if evict_chunk() decides to delay until the end
847  * of syscall.  Runs synchronously.
848  */
849 void audit_kill_trees(struct list_head *list)
850 {
851         mutex_lock(&audit_cmd_mutex);
852         mutex_lock(&audit_filter_mutex);
853
854         while (!list_empty(list)) {
855                 struct audit_tree *victim;
856
857                 victim = list_entry(list->next, struct audit_tree, list);
858                 kill_rules(victim);
859                 list_del_init(&victim->list);
860
861                 mutex_unlock(&audit_filter_mutex);
862
863                 prune_one(victim);
864
865                 mutex_lock(&audit_filter_mutex);
866         }
867
868         mutex_unlock(&audit_filter_mutex);
869         mutex_unlock(&audit_cmd_mutex);
870 }
871
872 /*
873  *  Here comes the stuff asynchronous to auditctl operations
874  */
875
876 static void evict_chunk(struct audit_chunk *chunk)
877 {
878         struct audit_tree *owner;
879         struct list_head *postponed = audit_killed_trees();
880         int need_prune = 0;
881         int n;
882
883         if (chunk->dead)
884                 return;
885
886         chunk->dead = 1;
887         mutex_lock(&audit_filter_mutex);
888         spin_lock(&hash_lock);
889         while (!list_empty(&chunk->trees)) {
890                 owner = list_entry(chunk->trees.next,
891                                    struct audit_tree, same_root);
892                 owner->goner = 1;
893                 owner->root = NULL;
894                 list_del_init(&owner->same_root);
895                 spin_unlock(&hash_lock);
896                 if (!postponed) {
897                         kill_rules(owner);
898                         list_move(&owner->list, &prune_list);
899                         need_prune = 1;
900                 } else {
901                         list_move(&owner->list, postponed);
902                 }
903                 spin_lock(&hash_lock);
904         }
905         list_del_rcu(&chunk->hash);
906         for (n = 0; n < chunk->count; n++)
907                 list_del_init(&chunk->owners[n].list);
908         spin_unlock(&hash_lock);
909         if (need_prune)
910                 audit_schedule_prune();
911         mutex_unlock(&audit_filter_mutex);
912 }
913
914 static int audit_tree_handle_event(struct fsnotify_group *group,
915                                    struct fsnotify_mark *inode_mark,
916                                    struct fsnotify_mark *vfsmonut_mark,
917                                    struct fsnotify_event *event)
918 {
919         BUG();
920         return -EOPNOTSUPP;
921 }
922
923 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
924 {
925         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
926
927         evict_chunk(chunk);
928
929         /*
930          * We are guaranteed to have at least one reference to the mark from
931          * either the inode or the caller of fsnotify_destroy_mark().
932          */
933         BUG_ON(atomic_read(&entry->refcnt) < 1);
934 }
935
936 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
937                                   struct fsnotify_mark *inode_mark,
938                                   struct fsnotify_mark *vfsmount_mark,
939                                   __u32 mask, void *data, int data_type)
940 {
941         return false;
942 }
943
944 static const struct fsnotify_ops audit_tree_ops = {
945         .handle_event = audit_tree_handle_event,
946         .should_send_event = audit_tree_send_event,
947         .free_group_priv = NULL,
948         .free_event_priv = NULL,
949         .freeing_mark = audit_tree_freeing_mark,
950 };
951
952 static int __init audit_tree_init(void)
953 {
954         int i;
955
956         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
957         if (IS_ERR(audit_tree_group))
958                 audit_panic("cannot initialize fsnotify group for rectree watches");
959
960         for (i = 0; i < HASH_SIZE; i++)
961                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
962
963         return 0;
964 }
965 __initcall(audit_tree_init);