1f6396d766874b1f28577a44812b0d097106cf88
[linux-2.6.git] / kernel / audit_tree.c
1 #include "audit.h"
2 #include <linux/inotify.h>
3 #include <linux/namei.h>
4 #include <linux/mount.h>
5
6 struct audit_tree;
7 struct audit_chunk;
8
9 struct audit_tree {
10         atomic_t count;
11         int goner;
12         struct audit_chunk *root;
13         struct list_head chunks;
14         struct list_head rules;
15         struct list_head list;
16         struct list_head same_root;
17         struct rcu_head head;
18         char pathname[];
19 };
20
21 struct audit_chunk {
22         struct list_head hash;
23         struct inotify_watch watch;
24         struct list_head trees;         /* with root here */
25         int dead;
26         int count;
27         atomic_long_t refs;
28         struct rcu_head head;
29         struct node {
30                 struct list_head list;
31                 struct audit_tree *owner;
32                 unsigned index;         /* index; upper bit indicates 'will prune' */
33         } owners[];
34 };
35
36 static LIST_HEAD(tree_list);
37 static LIST_HEAD(prune_list);
38
39 /*
40  * One struct chunk is attached to each inode of interest.
41  * We replace struct chunk on tagging/untagging.
42  * Rules have pointer to struct audit_tree.
43  * Rules have struct list_head rlist forming a list of rules over
44  * the same tree.
45  * References to struct chunk are collected at audit_inode{,_child}()
46  * time and used in AUDIT_TREE rule matching.
47  * These references are dropped at the same time we are calling
48  * audit_free_names(), etc.
49  *
50  * Cyclic lists galore:
51  * tree.chunks anchors chunk.owners[].list                      hash_lock
52  * tree.rules anchors rule.rlist                                audit_filter_mutex
53  * chunk.trees anchors tree.same_root                           hash_lock
54  * chunk.hash is a hash with middle bits of watch.inode as
55  * a hash function.                                             RCU, hash_lock
56  *
57  * tree is refcounted; one reference for "some rules on rules_list refer to
58  * it", one for each chunk with pointer to it.
59  *
60  * chunk is refcounted by embedded inotify_watch + .refs (non-zero refcount
61  * of watch contributes 1 to .refs).
62  *
63  * node.index allows to get from node.list to containing chunk.
64  * MSB of that sucker is stolen to mark taggings that we might have to
65  * revert - several operations have very unpleasant cleanup logics and
66  * that makes a difference.  Some.
67  */
68
69 static struct inotify_handle *rtree_ih;
70
71 static struct audit_tree *alloc_tree(const char *s)
72 {
73         struct audit_tree *tree;
74
75         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
76         if (tree) {
77                 atomic_set(&tree->count, 1);
78                 tree->goner = 0;
79                 INIT_LIST_HEAD(&tree->chunks);
80                 INIT_LIST_HEAD(&tree->rules);
81                 INIT_LIST_HEAD(&tree->list);
82                 INIT_LIST_HEAD(&tree->same_root);
83                 tree->root = NULL;
84                 strcpy(tree->pathname, s);
85         }
86         return tree;
87 }
88
89 static inline void get_tree(struct audit_tree *tree)
90 {
91         atomic_inc(&tree->count);
92 }
93
94 static void __put_tree(struct rcu_head *rcu)
95 {
96         struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
97         kfree(tree);
98 }
99
100 static inline void put_tree(struct audit_tree *tree)
101 {
102         if (atomic_dec_and_test(&tree->count))
103                 call_rcu(&tree->head, __put_tree);
104 }
105
106 /* to avoid bringing the entire thing in audit.h */
107 const char *audit_tree_path(struct audit_tree *tree)
108 {
109         return tree->pathname;
110 }
111
112 static struct audit_chunk *alloc_chunk(int count)
113 {
114         struct audit_chunk *chunk;
115         size_t size;
116         int i;
117
118         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
119         chunk = kzalloc(size, GFP_KERNEL);
120         if (!chunk)
121                 return NULL;
122
123         INIT_LIST_HEAD(&chunk->hash);
124         INIT_LIST_HEAD(&chunk->trees);
125         chunk->count = count;
126         atomic_long_set(&chunk->refs, 1);
127         for (i = 0; i < count; i++) {
128                 INIT_LIST_HEAD(&chunk->owners[i].list);
129                 chunk->owners[i].index = i;
130         }
131         inotify_init_watch(&chunk->watch);
132         return chunk;
133 }
134
135 static void free_chunk(struct audit_chunk *chunk)
136 {
137         int i;
138
139         for (i = 0; i < chunk->count; i++) {
140                 if (chunk->owners[i].owner)
141                         put_tree(chunk->owners[i].owner);
142         }
143         kfree(chunk);
144 }
145
146 void audit_put_chunk(struct audit_chunk *chunk)
147 {
148         if (atomic_long_dec_and_test(&chunk->refs))
149                 free_chunk(chunk);
150 }
151
152 static void __put_chunk(struct rcu_head *rcu)
153 {
154         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
155         audit_put_chunk(chunk);
156 }
157
158 enum {HASH_SIZE = 128};
159 static struct list_head chunk_hash_heads[HASH_SIZE];
160 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
161
162 static inline struct list_head *chunk_hash(const struct inode *inode)
163 {
164         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
165         return chunk_hash_heads + n % HASH_SIZE;
166 }
167
168 /* hash_lock is held by caller */
169 static void insert_hash(struct audit_chunk *chunk)
170 {
171         struct list_head *list = chunk_hash(chunk->watch.inode);
172         list_add_rcu(&chunk->hash, list);
173 }
174
175 /* called under rcu_read_lock */
176 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
177 {
178         struct list_head *list = chunk_hash(inode);
179         struct audit_chunk *p;
180
181         list_for_each_entry_rcu(p, list, hash) {
182                 if (p->watch.inode == inode) {
183                         atomic_long_inc(&p->refs);
184                         return p;
185                 }
186         }
187         return NULL;
188 }
189
190 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
191 {
192         int n;
193         for (n = 0; n < chunk->count; n++)
194                 if (chunk->owners[n].owner == tree)
195                         return 1;
196         return 0;
197 }
198
199 /* tagging and untagging inodes with trees */
200
201 static struct audit_chunk *find_chunk(struct node *p)
202 {
203         int index = p->index & ~(1U<<31);
204         p -= index;
205         return container_of(p, struct audit_chunk, owners[0]);
206 }
207
208 static void untag_chunk(struct node *p)
209 {
210         struct audit_chunk *chunk = find_chunk(p);
211         struct audit_chunk *new;
212         struct audit_tree *owner;
213         int size = chunk->count - 1;
214         int i, j;
215
216         if (!pin_inotify_watch(&chunk->watch)) {
217                 /*
218                  * Filesystem is shutting down; all watches are getting
219                  * evicted, just take it off the node list for this
220                  * tree and let the eviction logics take care of the
221                  * rest.
222                  */
223                 owner = p->owner;
224                 if (owner->root == chunk) {
225                         list_del_init(&owner->same_root);
226                         owner->root = NULL;
227                 }
228                 list_del_init(&p->list);
229                 p->owner = NULL;
230                 put_tree(owner);
231                 return;
232         }
233
234         spin_unlock(&hash_lock);
235
236         /*
237          * pin_inotify_watch() succeeded, so the watch won't go away
238          * from under us.
239          */
240         mutex_lock(&chunk->watch.inode->inotify_mutex);
241         if (chunk->dead) {
242                 mutex_unlock(&chunk->watch.inode->inotify_mutex);
243                 goto out;
244         }
245
246         owner = p->owner;
247
248         if (!size) {
249                 chunk->dead = 1;
250                 spin_lock(&hash_lock);
251                 list_del_init(&chunk->trees);
252                 if (owner->root == chunk)
253                         owner->root = NULL;
254                 list_del_init(&p->list);
255                 list_del_rcu(&chunk->hash);
256                 spin_unlock(&hash_lock);
257                 inotify_evict_watch(&chunk->watch);
258                 mutex_unlock(&chunk->watch.inode->inotify_mutex);
259                 put_inotify_watch(&chunk->watch);
260                 goto out;
261         }
262
263         new = alloc_chunk(size);
264         if (!new)
265                 goto Fallback;
266         if (inotify_clone_watch(&chunk->watch, &new->watch) < 0) {
267                 free_chunk(new);
268                 goto Fallback;
269         }
270
271         chunk->dead = 1;
272         spin_lock(&hash_lock);
273         list_replace_init(&chunk->trees, &new->trees);
274         if (owner->root == chunk) {
275                 list_del_init(&owner->same_root);
276                 owner->root = NULL;
277         }
278
279         for (i = j = 0; i < size; i++, j++) {
280                 struct audit_tree *s;
281                 if (&chunk->owners[j] == p) {
282                         list_del_init(&p->list);
283                         i--;
284                         continue;
285                 }
286                 s = chunk->owners[j].owner;
287                 new->owners[i].owner = s;
288                 new->owners[i].index = chunk->owners[j].index - j + i;
289                 if (!s) /* result of earlier fallback */
290                         continue;
291                 get_tree(s);
292                 list_replace_init(&chunk->owners[i].list, &new->owners[j].list);
293         }
294
295         list_replace_rcu(&chunk->hash, &new->hash);
296         list_for_each_entry(owner, &new->trees, same_root)
297                 owner->root = new;
298         spin_unlock(&hash_lock);
299         inotify_evict_watch(&chunk->watch);
300         mutex_unlock(&chunk->watch.inode->inotify_mutex);
301         put_inotify_watch(&chunk->watch);
302         goto out;
303
304 Fallback:
305         // do the best we can
306         spin_lock(&hash_lock);
307         if (owner->root == chunk) {
308                 list_del_init(&owner->same_root);
309                 owner->root = NULL;
310         }
311         list_del_init(&p->list);
312         p->owner = NULL;
313         put_tree(owner);
314         spin_unlock(&hash_lock);
315         mutex_unlock(&chunk->watch.inode->inotify_mutex);
316 out:
317         unpin_inotify_watch(&chunk->watch);
318         spin_lock(&hash_lock);
319 }
320
321 static int create_chunk(struct inode *inode, struct audit_tree *tree)
322 {
323         struct audit_chunk *chunk = alloc_chunk(1);
324         if (!chunk)
325                 return -ENOMEM;
326
327         if (inotify_add_watch(rtree_ih, &chunk->watch, inode, IN_IGNORED | IN_DELETE_SELF) < 0) {
328                 free_chunk(chunk);
329                 return -ENOSPC;
330         }
331
332         mutex_lock(&inode->inotify_mutex);
333         spin_lock(&hash_lock);
334         if (tree->goner) {
335                 spin_unlock(&hash_lock);
336                 chunk->dead = 1;
337                 inotify_evict_watch(&chunk->watch);
338                 mutex_unlock(&inode->inotify_mutex);
339                 put_inotify_watch(&chunk->watch);
340                 return 0;
341         }
342         chunk->owners[0].index = (1U << 31);
343         chunk->owners[0].owner = tree;
344         get_tree(tree);
345         list_add(&chunk->owners[0].list, &tree->chunks);
346         if (!tree->root) {
347                 tree->root = chunk;
348                 list_add(&tree->same_root, &chunk->trees);
349         }
350         insert_hash(chunk);
351         spin_unlock(&hash_lock);
352         mutex_unlock(&inode->inotify_mutex);
353         return 0;
354 }
355
356 /* the first tagged inode becomes root of tree */
357 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
358 {
359         struct inotify_watch *watch;
360         struct audit_tree *owner;
361         struct audit_chunk *chunk, *old;
362         struct node *p;
363         int n;
364
365         if (inotify_find_watch(rtree_ih, inode, &watch) < 0)
366                 return create_chunk(inode, tree);
367
368         old = container_of(watch, struct audit_chunk, watch);
369
370         /* are we already there? */
371         spin_lock(&hash_lock);
372         for (n = 0; n < old->count; n++) {
373                 if (old->owners[n].owner == tree) {
374                         spin_unlock(&hash_lock);
375                         put_inotify_watch(watch);
376                         return 0;
377                 }
378         }
379         spin_unlock(&hash_lock);
380
381         chunk = alloc_chunk(old->count + 1);
382         if (!chunk)
383                 return -ENOMEM;
384
385         mutex_lock(&inode->inotify_mutex);
386         if (inotify_clone_watch(&old->watch, &chunk->watch) < 0) {
387                 mutex_unlock(&inode->inotify_mutex);
388                 put_inotify_watch(&old->watch);
389                 free_chunk(chunk);
390                 return -ENOSPC;
391         }
392         spin_lock(&hash_lock);
393         if (tree->goner) {
394                 spin_unlock(&hash_lock);
395                 chunk->dead = 1;
396                 inotify_evict_watch(&chunk->watch);
397                 mutex_unlock(&inode->inotify_mutex);
398                 put_inotify_watch(&old->watch);
399                 put_inotify_watch(&chunk->watch);
400                 return 0;
401         }
402         list_replace_init(&old->trees, &chunk->trees);
403         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
404                 struct audit_tree *s = old->owners[n].owner;
405                 p->owner = s;
406                 p->index = old->owners[n].index;
407                 if (!s) /* result of fallback in untag */
408                         continue;
409                 get_tree(s);
410                 list_replace_init(&old->owners[n].list, &p->list);
411         }
412         p->index = (chunk->count - 1) | (1U<<31);
413         p->owner = tree;
414         get_tree(tree);
415         list_add(&p->list, &tree->chunks);
416         list_replace_rcu(&old->hash, &chunk->hash);
417         list_for_each_entry(owner, &chunk->trees, same_root)
418                 owner->root = chunk;
419         old->dead = 1;
420         if (!tree->root) {
421                 tree->root = chunk;
422                 list_add(&tree->same_root, &chunk->trees);
423         }
424         spin_unlock(&hash_lock);
425         inotify_evict_watch(&old->watch);
426         mutex_unlock(&inode->inotify_mutex);
427         put_inotify_watch(&old->watch);
428         return 0;
429 }
430
431 static void kill_rules(struct audit_tree *tree)
432 {
433         struct audit_krule *rule, *next;
434         struct audit_entry *entry;
435         struct audit_buffer *ab;
436
437         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
438                 entry = container_of(rule, struct audit_entry, rule);
439
440                 list_del_init(&rule->rlist);
441                 if (rule->tree) {
442                         /* not a half-baked one */
443                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
444                         audit_log_format(ab, "op=remove rule dir=");
445                         audit_log_untrustedstring(ab, rule->tree->pathname);
446                         if (rule->filterkey) {
447                                 audit_log_format(ab, " key=");
448                                 audit_log_untrustedstring(ab, rule->filterkey);
449                         } else
450                                 audit_log_format(ab, " key=(null)");
451                         audit_log_format(ab, " list=%d res=1", rule->listnr);
452                         audit_log_end(ab);
453                         rule->tree = NULL;
454                         list_del_rcu(&entry->list);
455                         list_del(&entry->rule.list);
456                         call_rcu(&entry->rcu, audit_free_rule_rcu);
457                 }
458         }
459 }
460
461 /*
462  * finish killing struct audit_tree
463  */
464 static void prune_one(struct audit_tree *victim)
465 {
466         spin_lock(&hash_lock);
467         while (!list_empty(&victim->chunks)) {
468                 struct node *p;
469
470                 p = list_entry(victim->chunks.next, struct node, list);
471
472                 untag_chunk(p);
473         }
474         spin_unlock(&hash_lock);
475         put_tree(victim);
476 }
477
478 /* trim the uncommitted chunks from tree */
479
480 static void trim_marked(struct audit_tree *tree)
481 {
482         struct list_head *p, *q;
483         spin_lock(&hash_lock);
484         if (tree->goner) {
485                 spin_unlock(&hash_lock);
486                 return;
487         }
488         /* reorder */
489         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
490                 struct node *node = list_entry(p, struct node, list);
491                 q = p->next;
492                 if (node->index & (1U<<31)) {
493                         list_del_init(p);
494                         list_add(p, &tree->chunks);
495                 }
496         }
497
498         while (!list_empty(&tree->chunks)) {
499                 struct node *node;
500
501                 node = list_entry(tree->chunks.next, struct node, list);
502
503                 /* have we run out of marked? */
504                 if (!(node->index & (1U<<31)))
505                         break;
506
507                 untag_chunk(node);
508         }
509         if (!tree->root && !tree->goner) {
510                 tree->goner = 1;
511                 spin_unlock(&hash_lock);
512                 mutex_lock(&audit_filter_mutex);
513                 kill_rules(tree);
514                 list_del_init(&tree->list);
515                 mutex_unlock(&audit_filter_mutex);
516                 prune_one(tree);
517         } else {
518                 spin_unlock(&hash_lock);
519         }
520 }
521
522 /* called with audit_filter_mutex */
523 int audit_remove_tree_rule(struct audit_krule *rule)
524 {
525         struct audit_tree *tree;
526         tree = rule->tree;
527         if (tree) {
528                 spin_lock(&hash_lock);
529                 list_del_init(&rule->rlist);
530                 if (list_empty(&tree->rules) && !tree->goner) {
531                         tree->root = NULL;
532                         list_del_init(&tree->same_root);
533                         tree->goner = 1;
534                         list_move(&tree->list, &prune_list);
535                         rule->tree = NULL;
536                         spin_unlock(&hash_lock);
537                         audit_schedule_prune();
538                         return 1;
539                 }
540                 rule->tree = NULL;
541                 spin_unlock(&hash_lock);
542                 return 1;
543         }
544         return 0;
545 }
546
547 void audit_trim_trees(void)
548 {
549         struct list_head cursor;
550
551         mutex_lock(&audit_filter_mutex);
552         list_add(&cursor, &tree_list);
553         while (cursor.next != &tree_list) {
554                 struct audit_tree *tree;
555                 struct path path;
556                 struct vfsmount *root_mnt;
557                 struct node *node;
558                 struct list_head list;
559                 int err;
560
561                 tree = container_of(cursor.next, struct audit_tree, list);
562                 get_tree(tree);
563                 list_del(&cursor);
564                 list_add(&cursor, &tree->list);
565                 mutex_unlock(&audit_filter_mutex);
566
567                 err = kern_path(tree->pathname, 0, &path);
568                 if (err)
569                         goto skip_it;
570
571                 root_mnt = collect_mounts(&path);
572                 path_put(&path);
573                 if (!root_mnt)
574                         goto skip_it;
575
576                 list_add_tail(&list, &root_mnt->mnt_list);
577                 spin_lock(&hash_lock);
578                 list_for_each_entry(node, &tree->chunks, list) {
579                         struct audit_chunk *chunk = find_chunk(node);
580                         struct inode *inode = chunk->watch.inode;
581                         struct vfsmount *mnt;
582                         node->index |= 1U<<31;
583                         list_for_each_entry(mnt, &list, mnt_list) {
584                                 if (mnt->mnt_root->d_inode == inode) {
585                                         node->index &= ~(1U<<31);
586                                         break;
587                                 }
588                         }
589                 }
590                 spin_unlock(&hash_lock);
591                 trim_marked(tree);
592                 put_tree(tree);
593                 list_del_init(&list);
594                 drop_collected_mounts(root_mnt);
595 skip_it:
596                 mutex_lock(&audit_filter_mutex);
597         }
598         list_del(&cursor);
599         mutex_unlock(&audit_filter_mutex);
600 }
601
602 static int is_under(struct vfsmount *mnt, struct dentry *dentry,
603                     struct path *path)
604 {
605         if (mnt != path->mnt) {
606                 for (;;) {
607                         if (mnt->mnt_parent == mnt)
608                                 return 0;
609                         if (mnt->mnt_parent == path->mnt)
610                                         break;
611                         mnt = mnt->mnt_parent;
612                 }
613                 dentry = mnt->mnt_mountpoint;
614         }
615         return is_subdir(dentry, path->dentry);
616 }
617
618 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
619 {
620
621         if (pathname[0] != '/' ||
622             rule->listnr != AUDIT_FILTER_EXIT ||
623             op != Audit_equal ||
624             rule->inode_f || rule->watch || rule->tree)
625                 return -EINVAL;
626         rule->tree = alloc_tree(pathname);
627         if (!rule->tree)
628                 return -ENOMEM;
629         return 0;
630 }
631
632 void audit_put_tree(struct audit_tree *tree)
633 {
634         put_tree(tree);
635 }
636
637 /* called with audit_filter_mutex */
638 int audit_add_tree_rule(struct audit_krule *rule)
639 {
640         struct audit_tree *seed = rule->tree, *tree;
641         struct path path;
642         struct vfsmount *mnt, *p;
643         struct list_head list;
644         int err;
645
646         list_for_each_entry(tree, &tree_list, list) {
647                 if (!strcmp(seed->pathname, tree->pathname)) {
648                         put_tree(seed);
649                         rule->tree = tree;
650                         list_add(&rule->rlist, &tree->rules);
651                         return 0;
652                 }
653         }
654         tree = seed;
655         list_add(&tree->list, &tree_list);
656         list_add(&rule->rlist, &tree->rules);
657         /* do not set rule->tree yet */
658         mutex_unlock(&audit_filter_mutex);
659
660         err = kern_path(tree->pathname, 0, &path);
661         if (err)
662                 goto Err;
663         mnt = collect_mounts(&path);
664         path_put(&path);
665         if (!mnt) {
666                 err = -ENOMEM;
667                 goto Err;
668         }
669         list_add_tail(&list, &mnt->mnt_list);
670
671         get_tree(tree);
672         list_for_each_entry(p, &list, mnt_list) {
673                 err = tag_chunk(p->mnt_root->d_inode, tree);
674                 if (err)
675                         break;
676         }
677
678         list_del(&list);
679         drop_collected_mounts(mnt);
680
681         if (!err) {
682                 struct node *node;
683                 spin_lock(&hash_lock);
684                 list_for_each_entry(node, &tree->chunks, list)
685                         node->index &= ~(1U<<31);
686                 spin_unlock(&hash_lock);
687         } else {
688                 trim_marked(tree);
689                 goto Err;
690         }
691
692         mutex_lock(&audit_filter_mutex);
693         if (list_empty(&rule->rlist)) {
694                 put_tree(tree);
695                 return -ENOENT;
696         }
697         rule->tree = tree;
698         put_tree(tree);
699
700         return 0;
701 Err:
702         mutex_lock(&audit_filter_mutex);
703         list_del_init(&tree->list);
704         list_del_init(&tree->rules);
705         put_tree(tree);
706         return err;
707 }
708
709 int audit_tag_tree(char *old, char *new)
710 {
711         struct list_head cursor, barrier;
712         int failed = 0;
713         struct path path;
714         struct vfsmount *tagged;
715         struct list_head list;
716         struct vfsmount *mnt;
717         struct dentry *dentry;
718         int err;
719
720         err = kern_path(new, 0, &path);
721         if (err)
722                 return err;
723         tagged = collect_mounts(&path);
724         path_put(&path);
725         if (!tagged)
726                 return -ENOMEM;
727
728         err = kern_path(old, 0, &path);
729         if (err) {
730                 drop_collected_mounts(tagged);
731                 return err;
732         }
733         mnt = mntget(path.mnt);
734         dentry = dget(path.dentry);
735         path_put(&path);
736
737         list_add_tail(&list, &tagged->mnt_list);
738
739         mutex_lock(&audit_filter_mutex);
740         list_add(&barrier, &tree_list);
741         list_add(&cursor, &barrier);
742
743         while (cursor.next != &tree_list) {
744                 struct audit_tree *tree;
745                 struct vfsmount *p;
746
747                 tree = container_of(cursor.next, struct audit_tree, list);
748                 get_tree(tree);
749                 list_del(&cursor);
750                 list_add(&cursor, &tree->list);
751                 mutex_unlock(&audit_filter_mutex);
752
753                 err = kern_path(tree->pathname, 0, &path);
754                 if (err) {
755                         put_tree(tree);
756                         mutex_lock(&audit_filter_mutex);
757                         continue;
758                 }
759
760                 spin_lock(&vfsmount_lock);
761                 if (!is_under(mnt, dentry, &path)) {
762                         spin_unlock(&vfsmount_lock);
763                         path_put(&path);
764                         put_tree(tree);
765                         mutex_lock(&audit_filter_mutex);
766                         continue;
767                 }
768                 spin_unlock(&vfsmount_lock);
769                 path_put(&path);
770
771                 list_for_each_entry(p, &list, mnt_list) {
772                         failed = tag_chunk(p->mnt_root->d_inode, tree);
773                         if (failed)
774                                 break;
775                 }
776
777                 if (failed) {
778                         put_tree(tree);
779                         mutex_lock(&audit_filter_mutex);
780                         break;
781                 }
782
783                 mutex_lock(&audit_filter_mutex);
784                 spin_lock(&hash_lock);
785                 if (!tree->goner) {
786                         list_del(&tree->list);
787                         list_add(&tree->list, &tree_list);
788                 }
789                 spin_unlock(&hash_lock);
790                 put_tree(tree);
791         }
792
793         while (barrier.prev != &tree_list) {
794                 struct audit_tree *tree;
795
796                 tree = container_of(barrier.prev, struct audit_tree, list);
797                 get_tree(tree);
798                 list_del(&tree->list);
799                 list_add(&tree->list, &barrier);
800                 mutex_unlock(&audit_filter_mutex);
801
802                 if (!failed) {
803                         struct node *node;
804                         spin_lock(&hash_lock);
805                         list_for_each_entry(node, &tree->chunks, list)
806                                 node->index &= ~(1U<<31);
807                         spin_unlock(&hash_lock);
808                 } else {
809                         trim_marked(tree);
810                 }
811
812                 put_tree(tree);
813                 mutex_lock(&audit_filter_mutex);
814         }
815         list_del(&barrier);
816         list_del(&cursor);
817         list_del(&list);
818         mutex_unlock(&audit_filter_mutex);
819         dput(dentry);
820         mntput(mnt);
821         drop_collected_mounts(tagged);
822         return failed;
823 }
824
825 /*
826  * That gets run when evict_chunk() ends up needing to kill audit_tree.
827  * Runs from a separate thread, with audit_cmd_mutex held.
828  */
829 void audit_prune_trees(void)
830 {
831         mutex_lock(&audit_filter_mutex);
832
833         while (!list_empty(&prune_list)) {
834                 struct audit_tree *victim;
835
836                 victim = list_entry(prune_list.next, struct audit_tree, list);
837                 list_del_init(&victim->list);
838
839                 mutex_unlock(&audit_filter_mutex);
840
841                 prune_one(victim);
842
843                 mutex_lock(&audit_filter_mutex);
844         }
845
846         mutex_unlock(&audit_filter_mutex);
847 }
848
849 /*
850  *  Here comes the stuff asynchronous to auditctl operations
851  */
852
853 /* inode->inotify_mutex is locked */
854 static void evict_chunk(struct audit_chunk *chunk)
855 {
856         struct audit_tree *owner;
857         int n;
858
859         if (chunk->dead)
860                 return;
861
862         chunk->dead = 1;
863         mutex_lock(&audit_filter_mutex);
864         spin_lock(&hash_lock);
865         while (!list_empty(&chunk->trees)) {
866                 owner = list_entry(chunk->trees.next,
867                                    struct audit_tree, same_root);
868                 owner->goner = 1;
869                 owner->root = NULL;
870                 list_del_init(&owner->same_root);
871                 spin_unlock(&hash_lock);
872                 kill_rules(owner);
873                 list_move(&owner->list, &prune_list);
874                 audit_schedule_prune();
875                 spin_lock(&hash_lock);
876         }
877         list_del_rcu(&chunk->hash);
878         for (n = 0; n < chunk->count; n++)
879                 list_del_init(&chunk->owners[n].list);
880         spin_unlock(&hash_lock);
881         mutex_unlock(&audit_filter_mutex);
882 }
883
884 static void handle_event(struct inotify_watch *watch, u32 wd, u32 mask,
885                          u32 cookie, const char *dname, struct inode *inode)
886 {
887         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
888
889         if (mask & IN_IGNORED) {
890                 evict_chunk(chunk);
891                 put_inotify_watch(watch);
892         }
893 }
894
895 static void destroy_watch(struct inotify_watch *watch)
896 {
897         struct audit_chunk *chunk = container_of(watch, struct audit_chunk, watch);
898         call_rcu(&chunk->head, __put_chunk);
899 }
900
901 static const struct inotify_operations rtree_inotify_ops = {
902         .handle_event   = handle_event,
903         .destroy_watch  = destroy_watch,
904 };
905
906 static int __init audit_tree_init(void)
907 {
908         int i;
909
910         rtree_ih = inotify_init(&rtree_inotify_ops);
911         if (IS_ERR(rtree_ih))
912                 audit_panic("cannot initialize inotify handle for rectree watches");
913
914         for (i = 0; i < HASH_SIZE; i++)
915                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
916
917         return 0;
918 }
919 __initcall(audit_tree_init);