Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[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 void __put_tree(struct rcu_head *rcu)
97 {
98         struct audit_tree *tree = container_of(rcu, struct audit_tree, head);
99         kfree(tree);
100 }
101
102 static inline void put_tree(struct audit_tree *tree)
103 {
104         if (atomic_dec_and_test(&tree->count))
105                 call_rcu(&tree->head, __put_tree);
106 }
107
108 /* to avoid bringing the entire thing in audit.h */
109 const char *audit_tree_path(struct audit_tree *tree)
110 {
111         return tree->pathname;
112 }
113
114 static void free_chunk(struct audit_chunk *chunk)
115 {
116         int i;
117
118         for (i = 0; i < chunk->count; i++) {
119                 if (chunk->owners[i].owner)
120                         put_tree(chunk->owners[i].owner);
121         }
122         kfree(chunk);
123 }
124
125 void audit_put_chunk(struct audit_chunk *chunk)
126 {
127         if (atomic_long_dec_and_test(&chunk->refs))
128                 free_chunk(chunk);
129 }
130
131 static void __put_chunk(struct rcu_head *rcu)
132 {
133         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
134         audit_put_chunk(chunk);
135 }
136
137 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
138 {
139         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
140         call_rcu(&chunk->head, __put_chunk);
141 }
142
143 static struct audit_chunk *alloc_chunk(int count)
144 {
145         struct audit_chunk *chunk;
146         size_t size;
147         int i;
148
149         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
150         chunk = kzalloc(size, GFP_KERNEL);
151         if (!chunk)
152                 return NULL;
153
154         INIT_LIST_HEAD(&chunk->hash);
155         INIT_LIST_HEAD(&chunk->trees);
156         chunk->count = count;
157         atomic_long_set(&chunk->refs, 1);
158         for (i = 0; i < count; i++) {
159                 INIT_LIST_HEAD(&chunk->owners[i].list);
160                 chunk->owners[i].index = i;
161         }
162         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
163         return chunk;
164 }
165
166 enum {HASH_SIZE = 128};
167 static struct list_head chunk_hash_heads[HASH_SIZE];
168 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
169
170 static inline struct list_head *chunk_hash(const struct inode *inode)
171 {
172         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
173         return chunk_hash_heads + n % HASH_SIZE;
174 }
175
176 /* hash_lock & entry->lock is held by caller */
177 static void insert_hash(struct audit_chunk *chunk)
178 {
179         struct fsnotify_mark *entry = &chunk->mark;
180         struct list_head *list;
181
182         if (!entry->i.inode)
183                 return;
184         list = chunk_hash(entry->i.inode);
185         list_add_rcu(&chunk->hash, list);
186 }
187
188 /* called under rcu_read_lock */
189 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
190 {
191         struct list_head *list = chunk_hash(inode);
192         struct audit_chunk *p;
193
194         list_for_each_entry_rcu(p, list, hash) {
195                 /* mark.inode may have gone NULL, but who cares? */
196                 if (p->mark.i.inode == inode) {
197                         atomic_long_inc(&p->refs);
198                         return p;
199                 }
200         }
201         return NULL;
202 }
203
204 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
205 {
206         int n;
207         for (n = 0; n < chunk->count; n++)
208                 if (chunk->owners[n].owner == tree)
209                         return 1;
210         return 0;
211 }
212
213 /* tagging and untagging inodes with trees */
214
215 static struct audit_chunk *find_chunk(struct node *p)
216 {
217         int index = p->index & ~(1U<<31);
218         p -= index;
219         return container_of(p, struct audit_chunk, owners[0]);
220 }
221
222 static void untag_chunk(struct node *p)
223 {
224         struct audit_chunk *chunk = find_chunk(p);
225         struct fsnotify_mark *entry = &chunk->mark;
226         struct audit_chunk *new = NULL;
227         struct audit_tree *owner;
228         int size = chunk->count - 1;
229         int i, j;
230
231         fsnotify_get_mark(entry);
232
233         spin_unlock(&hash_lock);
234
235         if (size)
236                 new = alloc_chunk(size);
237
238         spin_lock(&entry->lock);
239         if (chunk->dead || !entry->i.inode) {
240                 spin_unlock(&entry->lock);
241                 if (new)
242                         free_chunk(new);
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                 spin_unlock(&entry->lock);
258                 fsnotify_destroy_mark(entry);
259                 fsnotify_put_mark(entry);
260                 goto out;
261         }
262
263         if (!new)
264                 goto Fallback;
265
266         fsnotify_duplicate_mark(&new->mark, entry);
267         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
268                 free_chunk(new);
269                 goto Fallback;
270         }
271
272         chunk->dead = 1;
273         spin_lock(&hash_lock);
274         list_replace_init(&chunk->trees, &new->trees);
275         if (owner->root == chunk) {
276                 list_del_init(&owner->same_root);
277                 owner->root = NULL;
278         }
279
280         for (i = j = 0; j <= size; i++, j++) {
281                 struct audit_tree *s;
282                 if (&chunk->owners[j] == p) {
283                         list_del_init(&p->list);
284                         i--;
285                         continue;
286                 }
287                 s = chunk->owners[j].owner;
288                 new->owners[i].owner = s;
289                 new->owners[i].index = chunk->owners[j].index - j + i;
290                 if (!s) /* result of earlier fallback */
291                         continue;
292                 get_tree(s);
293                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
294         }
295
296         list_replace_rcu(&chunk->hash, &new->hash);
297         list_for_each_entry(owner, &new->trees, same_root)
298                 owner->root = new;
299         spin_unlock(&hash_lock);
300         spin_unlock(&entry->lock);
301         fsnotify_destroy_mark(entry);
302         fsnotify_put_mark(entry);
303         goto out;
304
305 Fallback:
306         // do the best we can
307         spin_lock(&hash_lock);
308         if (owner->root == chunk) {
309                 list_del_init(&owner->same_root);
310                 owner->root = NULL;
311         }
312         list_del_init(&p->list);
313         p->owner = NULL;
314         put_tree(owner);
315         spin_unlock(&hash_lock);
316         spin_unlock(&entry->lock);
317 out:
318         fsnotify_put_mark(entry);
319         spin_lock(&hash_lock);
320 }
321
322 static int create_chunk(struct inode *inode, struct audit_tree *tree)
323 {
324         struct fsnotify_mark *entry;
325         struct audit_chunk *chunk = alloc_chunk(1);
326         if (!chunk)
327                 return -ENOMEM;
328
329         entry = &chunk->mark;
330         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
331                 free_chunk(chunk);
332                 return -ENOSPC;
333         }
334
335         spin_lock(&entry->lock);
336         spin_lock(&hash_lock);
337         if (tree->goner) {
338                 spin_unlock(&hash_lock);
339                 chunk->dead = 1;
340                 spin_unlock(&entry->lock);
341                 fsnotify_destroy_mark(entry);
342                 fsnotify_put_mark(entry);
343                 return 0;
344         }
345         chunk->owners[0].index = (1U << 31);
346         chunk->owners[0].owner = tree;
347         get_tree(tree);
348         list_add(&chunk->owners[0].list, &tree->chunks);
349         if (!tree->root) {
350                 tree->root = chunk;
351                 list_add(&tree->same_root, &chunk->trees);
352         }
353         insert_hash(chunk);
354         spin_unlock(&hash_lock);
355         spin_unlock(&entry->lock);
356         return 0;
357 }
358
359 /* the first tagged inode becomes root of tree */
360 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
361 {
362         struct fsnotify_mark *old_entry, *chunk_entry;
363         struct audit_tree *owner;
364         struct audit_chunk *chunk, *old;
365         struct node *p;
366         int n;
367
368         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
369         if (!old_entry)
370                 return create_chunk(inode, tree);
371
372         old = container_of(old_entry, struct audit_chunk, mark);
373
374         /* are we already there? */
375         spin_lock(&hash_lock);
376         for (n = 0; n < old->count; n++) {
377                 if (old->owners[n].owner == tree) {
378                         spin_unlock(&hash_lock);
379                         fsnotify_put_mark(old_entry);
380                         return 0;
381                 }
382         }
383         spin_unlock(&hash_lock);
384
385         chunk = alloc_chunk(old->count + 1);
386         if (!chunk) {
387                 fsnotify_put_mark(old_entry);
388                 return -ENOMEM;
389         }
390
391         chunk_entry = &chunk->mark;
392
393         spin_lock(&old_entry->lock);
394         if (!old_entry->i.inode) {
395                 /* old_entry is being shot, lets just lie */
396                 spin_unlock(&old_entry->lock);
397                 fsnotify_put_mark(old_entry);
398                 free_chunk(chunk);
399                 return -ENOENT;
400         }
401
402         fsnotify_duplicate_mark(chunk_entry, old_entry);
403         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
404                 spin_unlock(&old_entry->lock);
405                 free_chunk(chunk);
406                 fsnotify_put_mark(old_entry);
407                 return -ENOSPC;
408         }
409
410         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
411         spin_lock(&chunk_entry->lock);
412         spin_lock(&hash_lock);
413
414         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
415         if (tree->goner) {
416                 spin_unlock(&hash_lock);
417                 chunk->dead = 1;
418                 spin_unlock(&chunk_entry->lock);
419                 spin_unlock(&old_entry->lock);
420
421                 fsnotify_destroy_mark(chunk_entry);
422
423                 fsnotify_put_mark(chunk_entry);
424                 fsnotify_put_mark(old_entry);
425                 return 0;
426         }
427         list_replace_init(&old->trees, &chunk->trees);
428         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
429                 struct audit_tree *s = old->owners[n].owner;
430                 p->owner = s;
431                 p->index = old->owners[n].index;
432                 if (!s) /* result of fallback in untag */
433                         continue;
434                 get_tree(s);
435                 list_replace_init(&old->owners[n].list, &p->list);
436         }
437         p->index = (chunk->count - 1) | (1U<<31);
438         p->owner = tree;
439         get_tree(tree);
440         list_add(&p->list, &tree->chunks);
441         list_replace_rcu(&old->hash, &chunk->hash);
442         list_for_each_entry(owner, &chunk->trees, same_root)
443                 owner->root = chunk;
444         old->dead = 1;
445         if (!tree->root) {
446                 tree->root = chunk;
447                 list_add(&tree->same_root, &chunk->trees);
448         }
449         spin_unlock(&hash_lock);
450         spin_unlock(&chunk_entry->lock);
451         spin_unlock(&old_entry->lock);
452         fsnotify_destroy_mark(old_entry);
453         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
454         fsnotify_put_mark(old_entry); /* and kill it */
455         return 0;
456 }
457
458 static void kill_rules(struct audit_tree *tree)
459 {
460         struct audit_krule *rule, *next;
461         struct audit_entry *entry;
462         struct audit_buffer *ab;
463
464         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
465                 entry = container_of(rule, struct audit_entry, rule);
466
467                 list_del_init(&rule->rlist);
468                 if (rule->tree) {
469                         /* not a half-baked one */
470                         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
471                         audit_log_format(ab, "op=");
472                         audit_log_string(ab, "remove rule");
473                         audit_log_format(ab, " dir=");
474                         audit_log_untrustedstring(ab, rule->tree->pathname);
475                         audit_log_key(ab, rule->filterkey);
476                         audit_log_format(ab, " list=%d res=1", rule->listnr);
477                         audit_log_end(ab);
478                         rule->tree = NULL;
479                         list_del_rcu(&entry->list);
480                         list_del(&entry->rule.list);
481                         call_rcu(&entry->rcu, audit_free_rule_rcu);
482                 }
483         }
484 }
485
486 /*
487  * finish killing struct audit_tree
488  */
489 static void prune_one(struct audit_tree *victim)
490 {
491         spin_lock(&hash_lock);
492         while (!list_empty(&victim->chunks)) {
493                 struct node *p;
494
495                 p = list_entry(victim->chunks.next, struct node, list);
496
497                 untag_chunk(p);
498         }
499         spin_unlock(&hash_lock);
500         put_tree(victim);
501 }
502
503 /* trim the uncommitted chunks from tree */
504
505 static void trim_marked(struct audit_tree *tree)
506 {
507         struct list_head *p, *q;
508         spin_lock(&hash_lock);
509         if (tree->goner) {
510                 spin_unlock(&hash_lock);
511                 return;
512         }
513         /* reorder */
514         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
515                 struct node *node = list_entry(p, struct node, list);
516                 q = p->next;
517                 if (node->index & (1U<<31)) {
518                         list_del_init(p);
519                         list_add(p, &tree->chunks);
520                 }
521         }
522
523         while (!list_empty(&tree->chunks)) {
524                 struct node *node;
525
526                 node = list_entry(tree->chunks.next, struct node, list);
527
528                 /* have we run out of marked? */
529                 if (!(node->index & (1U<<31)))
530                         break;
531
532                 untag_chunk(node);
533         }
534         if (!tree->root && !tree->goner) {
535                 tree->goner = 1;
536                 spin_unlock(&hash_lock);
537                 mutex_lock(&audit_filter_mutex);
538                 kill_rules(tree);
539                 list_del_init(&tree->list);
540                 mutex_unlock(&audit_filter_mutex);
541                 prune_one(tree);
542         } else {
543                 spin_unlock(&hash_lock);
544         }
545 }
546
547 static void audit_schedule_prune(void);
548
549 /* called with audit_filter_mutex */
550 int audit_remove_tree_rule(struct audit_krule *rule)
551 {
552         struct audit_tree *tree;
553         tree = rule->tree;
554         if (tree) {
555                 spin_lock(&hash_lock);
556                 list_del_init(&rule->rlist);
557                 if (list_empty(&tree->rules) && !tree->goner) {
558                         tree->root = NULL;
559                         list_del_init(&tree->same_root);
560                         tree->goner = 1;
561                         list_move(&tree->list, &prune_list);
562                         rule->tree = NULL;
563                         spin_unlock(&hash_lock);
564                         audit_schedule_prune();
565                         return 1;
566                 }
567                 rule->tree = NULL;
568                 spin_unlock(&hash_lock);
569                 return 1;
570         }
571         return 0;
572 }
573
574 static int compare_root(struct vfsmount *mnt, void *arg)
575 {
576         return mnt->mnt_root->d_inode == arg;
577 }
578
579 void audit_trim_trees(void)
580 {
581         struct list_head cursor;
582
583         mutex_lock(&audit_filter_mutex);
584         list_add(&cursor, &tree_list);
585         while (cursor.next != &tree_list) {
586                 struct audit_tree *tree;
587                 struct path path;
588                 struct vfsmount *root_mnt;
589                 struct node *node;
590                 int err;
591
592                 tree = container_of(cursor.next, struct audit_tree, list);
593                 get_tree(tree);
594                 list_del(&cursor);
595                 list_add(&cursor, &tree->list);
596                 mutex_unlock(&audit_filter_mutex);
597
598                 err = kern_path(tree->pathname, 0, &path);
599                 if (err)
600                         goto skip_it;
601
602                 root_mnt = collect_mounts(&path);
603                 path_put(&path);
604                 if (!root_mnt)
605                         goto skip_it;
606
607                 spin_lock(&hash_lock);
608                 list_for_each_entry(node, &tree->chunks, list) {
609                         struct audit_chunk *chunk = find_chunk(node);
610                         /* this could be NULL if the watch is dieing else where... */
611                         struct inode *inode = chunk->mark.i.inode;
612                         node->index |= 1U<<31;
613                         if (iterate_mounts(compare_root, inode, root_mnt))
614                                 node->index &= ~(1U<<31);
615                 }
616                 spin_unlock(&hash_lock);
617                 trim_marked(tree);
618                 put_tree(tree);
619                 drop_collected_mounts(root_mnt);
620 skip_it:
621                 mutex_lock(&audit_filter_mutex);
622         }
623         list_del(&cursor);
624         mutex_unlock(&audit_filter_mutex);
625 }
626
627 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
628 {
629
630         if (pathname[0] != '/' ||
631             rule->listnr != AUDIT_FILTER_EXIT ||
632             op != Audit_equal ||
633             rule->inode_f || rule->watch || rule->tree)
634                 return -EINVAL;
635         rule->tree = alloc_tree(pathname);
636         if (!rule->tree)
637                 return -ENOMEM;
638         return 0;
639 }
640
641 void audit_put_tree(struct audit_tree *tree)
642 {
643         put_tree(tree);
644 }
645
646 static int tag_mount(struct vfsmount *mnt, void *arg)
647 {
648         return tag_chunk(mnt->mnt_root->d_inode, arg);
649 }
650
651 /* called with audit_filter_mutex */
652 int audit_add_tree_rule(struct audit_krule *rule)
653 {
654         struct audit_tree *seed = rule->tree, *tree;
655         struct path path;
656         struct vfsmount *mnt;
657         int err;
658
659         list_for_each_entry(tree, &tree_list, list) {
660                 if (!strcmp(seed->pathname, tree->pathname)) {
661                         put_tree(seed);
662                         rule->tree = tree;
663                         list_add(&rule->rlist, &tree->rules);
664                         return 0;
665                 }
666         }
667         tree = seed;
668         list_add(&tree->list, &tree_list);
669         list_add(&rule->rlist, &tree->rules);
670         /* do not set rule->tree yet */
671         mutex_unlock(&audit_filter_mutex);
672
673         err = kern_path(tree->pathname, 0, &path);
674         if (err)
675                 goto Err;
676         mnt = collect_mounts(&path);
677         path_put(&path);
678         if (!mnt) {
679                 err = -ENOMEM;
680                 goto Err;
681         }
682
683         get_tree(tree);
684         err = iterate_mounts(tag_mount, tree, mnt);
685         drop_collected_mounts(mnt);
686
687         if (!err) {
688                 struct node *node;
689                 spin_lock(&hash_lock);
690                 list_for_each_entry(node, &tree->chunks, list)
691                         node->index &= ~(1U<<31);
692                 spin_unlock(&hash_lock);
693         } else {
694                 trim_marked(tree);
695                 goto Err;
696         }
697
698         mutex_lock(&audit_filter_mutex);
699         if (list_empty(&rule->rlist)) {
700                 put_tree(tree);
701                 return -ENOENT;
702         }
703         rule->tree = tree;
704         put_tree(tree);
705
706         return 0;
707 Err:
708         mutex_lock(&audit_filter_mutex);
709         list_del_init(&tree->list);
710         list_del_init(&tree->rules);
711         put_tree(tree);
712         return err;
713 }
714
715 int audit_tag_tree(char *old, char *new)
716 {
717         struct list_head cursor, barrier;
718         int failed = 0;
719         struct path path1, path2;
720         struct vfsmount *tagged;
721         int err;
722
723         err = kern_path(new, 0, &path2);
724         if (err)
725                 return err;
726         tagged = collect_mounts(&path2);
727         path_put(&path2);
728         if (!tagged)
729                 return -ENOMEM;
730
731         err = kern_path(old, 0, &path1);
732         if (err) {
733                 drop_collected_mounts(tagged);
734                 return err;
735         }
736
737         mutex_lock(&audit_filter_mutex);
738         list_add(&barrier, &tree_list);
739         list_add(&cursor, &barrier);
740
741         while (cursor.next != &tree_list) {
742                 struct audit_tree *tree;
743                 int good_one = 0;
744
745                 tree = container_of(cursor.next, struct audit_tree, list);
746                 get_tree(tree);
747                 list_del(&cursor);
748                 list_add(&cursor, &tree->list);
749                 mutex_unlock(&audit_filter_mutex);
750
751                 err = kern_path(tree->pathname, 0, &path2);
752                 if (!err) {
753                         good_one = path_is_under(&path1, &path2);
754                         path_put(&path2);
755                 }
756
757                 if (!good_one) {
758                         put_tree(tree);
759                         mutex_lock(&audit_filter_mutex);
760                         continue;
761                 }
762
763                 failed = iterate_mounts(tag_mount, tree, tagged);
764                 if (failed) {
765                         put_tree(tree);
766                         mutex_lock(&audit_filter_mutex);
767                         break;
768                 }
769
770                 mutex_lock(&audit_filter_mutex);
771                 spin_lock(&hash_lock);
772                 if (!tree->goner) {
773                         list_del(&tree->list);
774                         list_add(&tree->list, &tree_list);
775                 }
776                 spin_unlock(&hash_lock);
777                 put_tree(tree);
778         }
779
780         while (barrier.prev != &tree_list) {
781                 struct audit_tree *tree;
782
783                 tree = container_of(barrier.prev, struct audit_tree, list);
784                 get_tree(tree);
785                 list_del(&tree->list);
786                 list_add(&tree->list, &barrier);
787                 mutex_unlock(&audit_filter_mutex);
788
789                 if (!failed) {
790                         struct node *node;
791                         spin_lock(&hash_lock);
792                         list_for_each_entry(node, &tree->chunks, list)
793                                 node->index &= ~(1U<<31);
794                         spin_unlock(&hash_lock);
795                 } else {
796                         trim_marked(tree);
797                 }
798
799                 put_tree(tree);
800                 mutex_lock(&audit_filter_mutex);
801         }
802         list_del(&barrier);
803         list_del(&cursor);
804         mutex_unlock(&audit_filter_mutex);
805         path_put(&path1);
806         drop_collected_mounts(tagged);
807         return failed;
808 }
809
810 /*
811  * That gets run when evict_chunk() ends up needing to kill audit_tree.
812  * Runs from a separate thread.
813  */
814 static int prune_tree_thread(void *unused)
815 {
816         mutex_lock(&audit_cmd_mutex);
817         mutex_lock(&audit_filter_mutex);
818
819         while (!list_empty(&prune_list)) {
820                 struct audit_tree *victim;
821
822                 victim = list_entry(prune_list.next, struct audit_tree, list);
823                 list_del_init(&victim->list);
824
825                 mutex_unlock(&audit_filter_mutex);
826
827                 prune_one(victim);
828
829                 mutex_lock(&audit_filter_mutex);
830         }
831
832         mutex_unlock(&audit_filter_mutex);
833         mutex_unlock(&audit_cmd_mutex);
834         return 0;
835 }
836
837 static void audit_schedule_prune(void)
838 {
839         kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
840 }
841
842 /*
843  * ... and that one is done if evict_chunk() decides to delay until the end
844  * of syscall.  Runs synchronously.
845  */
846 void audit_kill_trees(struct list_head *list)
847 {
848         mutex_lock(&audit_cmd_mutex);
849         mutex_lock(&audit_filter_mutex);
850
851         while (!list_empty(list)) {
852                 struct audit_tree *victim;
853
854                 victim = list_entry(list->next, struct audit_tree, list);
855                 kill_rules(victim);
856                 list_del_init(&victim->list);
857
858                 mutex_unlock(&audit_filter_mutex);
859
860                 prune_one(victim);
861
862                 mutex_lock(&audit_filter_mutex);
863         }
864
865         mutex_unlock(&audit_filter_mutex);
866         mutex_unlock(&audit_cmd_mutex);
867 }
868
869 /*
870  *  Here comes the stuff asynchronous to auditctl operations
871  */
872
873 static void evict_chunk(struct audit_chunk *chunk)
874 {
875         struct audit_tree *owner;
876         struct list_head *postponed = audit_killed_trees();
877         int need_prune = 0;
878         int n;
879
880         if (chunk->dead)
881                 return;
882
883         chunk->dead = 1;
884         mutex_lock(&audit_filter_mutex);
885         spin_lock(&hash_lock);
886         while (!list_empty(&chunk->trees)) {
887                 owner = list_entry(chunk->trees.next,
888                                    struct audit_tree, same_root);
889                 owner->goner = 1;
890                 owner->root = NULL;
891                 list_del_init(&owner->same_root);
892                 spin_unlock(&hash_lock);
893                 if (!postponed) {
894                         kill_rules(owner);
895                         list_move(&owner->list, &prune_list);
896                         need_prune = 1;
897                 } else {
898                         list_move(&owner->list, postponed);
899                 }
900                 spin_lock(&hash_lock);
901         }
902         list_del_rcu(&chunk->hash);
903         for (n = 0; n < chunk->count; n++)
904                 list_del_init(&chunk->owners[n].list);
905         spin_unlock(&hash_lock);
906         if (need_prune)
907                 audit_schedule_prune();
908         mutex_unlock(&audit_filter_mutex);
909 }
910
911 static int audit_tree_handle_event(struct fsnotify_group *group,
912                                    struct fsnotify_mark *inode_mark,
913                                    struct fsnotify_mark *vfsmonut_mark,
914                                    struct fsnotify_event *event)
915 {
916         BUG();
917         return -EOPNOTSUPP;
918 }
919
920 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
921 {
922         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
923
924         evict_chunk(chunk);
925         fsnotify_put_mark(entry);
926 }
927
928 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
929                                   struct fsnotify_mark *inode_mark,
930                                   struct fsnotify_mark *vfsmount_mark,
931                                   __u32 mask, void *data, int data_type)
932 {
933         return false;
934 }
935
936 static const struct fsnotify_ops audit_tree_ops = {
937         .handle_event = audit_tree_handle_event,
938         .should_send_event = audit_tree_send_event,
939         .free_group_priv = NULL,
940         .free_event_priv = NULL,
941         .freeing_mark = audit_tree_freeing_mark,
942 };
943
944 static int __init audit_tree_init(void)
945 {
946         int i;
947
948         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
949         if (IS_ERR(audit_tree_group))
950                 audit_panic("cannot initialize fsnotify group for rectree watches");
951
952         for (i = 0; i < HASH_SIZE; i++)
953                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
954
955         return 0;
956 }
957 __initcall(audit_tree_init);