8b1dde96a0faa1bda645f0e03388f0a47f565bdc
[sfrench/cifs-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 static struct task_struct *prune_thread;
41
42 /*
43  * One struct chunk is attached to each inode of interest.
44  * We replace struct chunk on tagging/untagging.
45  * Rules have pointer to struct audit_tree.
46  * Rules have struct list_head rlist forming a list of rules over
47  * the same tree.
48  * References to struct chunk are collected at audit_inode{,_child}()
49  * time and used in AUDIT_TREE rule matching.
50  * These references are dropped at the same time we are calling
51  * audit_free_names(), etc.
52  *
53  * Cyclic lists galore:
54  * tree.chunks anchors chunk.owners[].list                      hash_lock
55  * tree.rules anchors rule.rlist                                audit_filter_mutex
56  * chunk.trees anchors tree.same_root                           hash_lock
57  * chunk.hash is a hash with middle bits of watch.inode as
58  * a hash function.                                             RCU, hash_lock
59  *
60  * tree is refcounted; one reference for "some rules on rules_list refer to
61  * it", one for each chunk with pointer to it.
62  *
63  * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
64  * of watch contributes 1 to .refs).
65  *
66  * node.index allows to get from node.list to containing chunk.
67  * MSB of that sucker is stolen to mark taggings that we might have to
68  * revert - several operations have very unpleasant cleanup logics and
69  * that makes a difference.  Some.
70  */
71
72 static struct fsnotify_group *audit_tree_group;
73
74 static struct audit_tree *alloc_tree(const char *s)
75 {
76         struct audit_tree *tree;
77
78         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
79         if (tree) {
80                 atomic_set(&tree->count, 1);
81                 tree->goner = 0;
82                 INIT_LIST_HEAD(&tree->chunks);
83                 INIT_LIST_HEAD(&tree->rules);
84                 INIT_LIST_HEAD(&tree->list);
85                 INIT_LIST_HEAD(&tree->same_root);
86                 tree->root = NULL;
87                 strcpy(tree->pathname, s);
88         }
89         return tree;
90 }
91
92 static inline void get_tree(struct audit_tree *tree)
93 {
94         atomic_inc(&tree->count);
95 }
96
97 static inline void put_tree(struct audit_tree *tree)
98 {
99         if (atomic_dec_and_test(&tree->count))
100                 kfree_rcu(tree, head);
101 }
102
103 /* to avoid bringing the entire thing in audit.h */
104 const char *audit_tree_path(struct audit_tree *tree)
105 {
106         return tree->pathname;
107 }
108
109 static void free_chunk(struct audit_chunk *chunk)
110 {
111         int i;
112
113         for (i = 0; i < chunk->count; i++) {
114                 if (chunk->owners[i].owner)
115                         put_tree(chunk->owners[i].owner);
116         }
117         kfree(chunk);
118 }
119
120 void audit_put_chunk(struct audit_chunk *chunk)
121 {
122         if (atomic_long_dec_and_test(&chunk->refs))
123                 free_chunk(chunk);
124 }
125
126 static void __put_chunk(struct rcu_head *rcu)
127 {
128         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
129         audit_put_chunk(chunk);
130 }
131
132 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
133 {
134         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
135         call_rcu(&chunk->head, __put_chunk);
136 }
137
138 static struct audit_chunk *alloc_chunk(int count)
139 {
140         struct audit_chunk *chunk;
141         size_t size;
142         int i;
143
144         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
145         chunk = kzalloc(size, GFP_KERNEL);
146         if (!chunk)
147                 return NULL;
148
149         INIT_LIST_HEAD(&chunk->hash);
150         INIT_LIST_HEAD(&chunk->trees);
151         chunk->count = count;
152         atomic_long_set(&chunk->refs, 1);
153         for (i = 0; i < count; i++) {
154                 INIT_LIST_HEAD(&chunk->owners[i].list);
155                 chunk->owners[i].index = i;
156         }
157         fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
158         chunk->mark.mask = FS_IN_IGNORED;
159         return chunk;
160 }
161
162 enum {HASH_SIZE = 128};
163 static struct list_head chunk_hash_heads[HASH_SIZE];
164 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
165
166 static inline struct list_head *chunk_hash(const struct inode *inode)
167 {
168         unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
169         return chunk_hash_heads + n % HASH_SIZE;
170 }
171
172 /* hash_lock & entry->lock is held by caller */
173 static void insert_hash(struct audit_chunk *chunk)
174 {
175         struct fsnotify_mark *entry = &chunk->mark;
176         struct list_head *list;
177
178         if (!entry->inode)
179                 return;
180         list = chunk_hash(entry->inode);
181         list_add_rcu(&chunk->hash, list);
182 }
183
184 /* called under rcu_read_lock */
185 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
186 {
187         struct list_head *list = chunk_hash(inode);
188         struct audit_chunk *p;
189
190         list_for_each_entry_rcu(p, list, hash) {
191                 /* mark.inode may have gone NULL, but who cares? */
192                 if (p->mark.inode == inode) {
193                         atomic_long_inc(&p->refs);
194                         return p;
195                 }
196         }
197         return NULL;
198 }
199
200 bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
201 {
202         int n;
203         for (n = 0; n < chunk->count; n++)
204                 if (chunk->owners[n].owner == tree)
205                         return true;
206         return false;
207 }
208
209 /* tagging and untagging inodes with trees */
210
211 static struct audit_chunk *find_chunk(struct node *p)
212 {
213         int index = p->index & ~(1U<<31);
214         p -= index;
215         return container_of(p, struct audit_chunk, owners[0]);
216 }
217
218 static void untag_chunk(struct node *p)
219 {
220         struct audit_chunk *chunk = find_chunk(p);
221         struct fsnotify_mark *entry = &chunk->mark;
222         struct audit_chunk *new = NULL;
223         struct audit_tree *owner;
224         int size = chunk->count - 1;
225         int i, j;
226
227         fsnotify_get_mark(entry);
228
229         spin_unlock(&hash_lock);
230
231         if (size)
232                 new = alloc_chunk(size);
233
234         spin_lock(&entry->lock);
235         if (chunk->dead || !entry->inode) {
236                 spin_unlock(&entry->lock);
237                 if (new)
238                         free_chunk(new);
239                 goto out;
240         }
241
242         owner = p->owner;
243
244         if (!size) {
245                 chunk->dead = 1;
246                 spin_lock(&hash_lock);
247                 list_del_init(&chunk->trees);
248                 if (owner->root == chunk)
249                         owner->root = NULL;
250                 list_del_init(&p->list);
251                 list_del_rcu(&chunk->hash);
252                 spin_unlock(&hash_lock);
253                 spin_unlock(&entry->lock);
254                 fsnotify_destroy_mark(entry, audit_tree_group);
255                 goto out;
256         }
257
258         if (!new)
259                 goto Fallback;
260
261         fsnotify_duplicate_mark(&new->mark, entry);
262         if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, NULL, 1)) {
263                 fsnotify_put_mark(&new->mark);
264                 goto Fallback;
265         }
266
267         chunk->dead = 1;
268         spin_lock(&hash_lock);
269         list_replace_init(&chunk->trees, &new->trees);
270         if (owner->root == chunk) {
271                 list_del_init(&owner->same_root);
272                 owner->root = NULL;
273         }
274
275         for (i = j = 0; j <= size; i++, j++) {
276                 struct audit_tree *s;
277                 if (&chunk->owners[j] == p) {
278                         list_del_init(&p->list);
279                         i--;
280                         continue;
281                 }
282                 s = chunk->owners[j].owner;
283                 new->owners[i].owner = s;
284                 new->owners[i].index = chunk->owners[j].index - j + i;
285                 if (!s) /* result of earlier fallback */
286                         continue;
287                 get_tree(s);
288                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
289         }
290
291         list_replace_rcu(&chunk->hash, &new->hash);
292         list_for_each_entry(owner, &new->trees, same_root)
293                 owner->root = new;
294         spin_unlock(&hash_lock);
295         spin_unlock(&entry->lock);
296         fsnotify_destroy_mark(entry, audit_tree_group);
297         fsnotify_put_mark(&new->mark);  /* drop initial reference */
298         goto out;
299
300 Fallback:
301         // do the best we can
302         spin_lock(&hash_lock);
303         if (owner->root == chunk) {
304                 list_del_init(&owner->same_root);
305                 owner->root = NULL;
306         }
307         list_del_init(&p->list);
308         p->owner = NULL;
309         put_tree(owner);
310         spin_unlock(&hash_lock);
311         spin_unlock(&entry->lock);
312 out:
313         fsnotify_put_mark(entry);
314         spin_lock(&hash_lock);
315 }
316
317 static int create_chunk(struct inode *inode, struct audit_tree *tree)
318 {
319         struct fsnotify_mark *entry;
320         struct audit_chunk *chunk = alloc_chunk(1);
321         if (!chunk)
322                 return -ENOMEM;
323
324         entry = &chunk->mark;
325         if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
326                 fsnotify_put_mark(entry);
327                 return -ENOSPC;
328         }
329
330         spin_lock(&entry->lock);
331         spin_lock(&hash_lock);
332         if (tree->goner) {
333                 spin_unlock(&hash_lock);
334                 chunk->dead = 1;
335                 spin_unlock(&entry->lock);
336                 fsnotify_destroy_mark(entry, audit_tree_group);
337                 fsnotify_put_mark(entry);
338                 return 0;
339         }
340         chunk->owners[0].index = (1U << 31);
341         chunk->owners[0].owner = tree;
342         get_tree(tree);
343         list_add(&chunk->owners[0].list, &tree->chunks);
344         if (!tree->root) {
345                 tree->root = chunk;
346                 list_add(&tree->same_root, &chunk->trees);
347         }
348         insert_hash(chunk);
349         spin_unlock(&hash_lock);
350         spin_unlock(&entry->lock);
351         fsnotify_put_mark(entry);       /* drop initial reference */
352         return 0;
353 }
354
355 /* the first tagged inode becomes root of tree */
356 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
357 {
358         struct fsnotify_mark *old_entry, *chunk_entry;
359         struct audit_tree *owner;
360         struct audit_chunk *chunk, *old;
361         struct node *p;
362         int n;
363
364         old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
365         if (!old_entry)
366                 return create_chunk(inode, tree);
367
368         old = container_of(old_entry, struct audit_chunk, mark);
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                         fsnotify_put_mark(old_entry);
376                         return 0;
377                 }
378         }
379         spin_unlock(&hash_lock);
380
381         chunk = alloc_chunk(old->count + 1);
382         if (!chunk) {
383                 fsnotify_put_mark(old_entry);
384                 return -ENOMEM;
385         }
386
387         chunk_entry = &chunk->mark;
388
389         spin_lock(&old_entry->lock);
390         if (!old_entry->inode) {
391                 /* old_entry is being shot, lets just lie */
392                 spin_unlock(&old_entry->lock);
393                 fsnotify_put_mark(old_entry);
394                 free_chunk(chunk);
395                 return -ENOENT;
396         }
397
398         fsnotify_duplicate_mark(chunk_entry, old_entry);
399         if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, NULL, 1)) {
400                 spin_unlock(&old_entry->lock);
401                 fsnotify_put_mark(chunk_entry);
402                 fsnotify_put_mark(old_entry);
403                 return -ENOSPC;
404         }
405
406         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
407         spin_lock(&chunk_entry->lock);
408         spin_lock(&hash_lock);
409
410         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
411         if (tree->goner) {
412                 spin_unlock(&hash_lock);
413                 chunk->dead = 1;
414                 spin_unlock(&chunk_entry->lock);
415                 spin_unlock(&old_entry->lock);
416
417                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
418
419                 fsnotify_put_mark(chunk_entry);
420                 fsnotify_put_mark(old_entry);
421                 return 0;
422         }
423         list_replace_init(&old->trees, &chunk->trees);
424         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
425                 struct audit_tree *s = old->owners[n].owner;
426                 p->owner = s;
427                 p->index = old->owners[n].index;
428                 if (!s) /* result of fallback in untag */
429                         continue;
430                 get_tree(s);
431                 list_replace_init(&old->owners[n].list, &p->list);
432         }
433         p->index = (chunk->count - 1) | (1U<<31);
434         p->owner = tree;
435         get_tree(tree);
436         list_add(&p->list, &tree->chunks);
437         list_replace_rcu(&old->hash, &chunk->hash);
438         list_for_each_entry(owner, &chunk->trees, same_root)
439                 owner->root = chunk;
440         old->dead = 1;
441         if (!tree->root) {
442                 tree->root = chunk;
443                 list_add(&tree->same_root, &chunk->trees);
444         }
445         spin_unlock(&hash_lock);
446         spin_unlock(&chunk_entry->lock);
447         spin_unlock(&old_entry->lock);
448         fsnotify_destroy_mark(old_entry, audit_tree_group);
449         fsnotify_put_mark(chunk_entry); /* drop initial reference */
450         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
451         return 0;
452 }
453
454 static void audit_tree_log_remove_rule(struct audit_krule *rule)
455 {
456         struct audit_buffer *ab;
457
458         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
459         if (unlikely(!ab))
460                 return;
461         audit_log_format(ab, "op=remove_rule");
462         audit_log_format(ab, " dir=");
463         audit_log_untrustedstring(ab, rule->tree->pathname);
464         audit_log_key(ab, rule->filterkey);
465         audit_log_format(ab, " list=%d res=1", rule->listnr);
466         audit_log_end(ab);
467 }
468
469 static void kill_rules(struct audit_tree *tree)
470 {
471         struct audit_krule *rule, *next;
472         struct audit_entry *entry;
473
474         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
475                 entry = container_of(rule, struct audit_entry, rule);
476
477                 list_del_init(&rule->rlist);
478                 if (rule->tree) {
479                         /* not a half-baked one */
480                         audit_tree_log_remove_rule(rule);
481                         if (entry->rule.exe)
482                                 audit_remove_mark(entry->rule.exe);
483                         rule->tree = NULL;
484                         list_del_rcu(&entry->list);
485                         list_del(&entry->rule.list);
486                         call_rcu(&entry->rcu, audit_free_rule_rcu);
487                 }
488         }
489 }
490
491 /*
492  * finish killing struct audit_tree
493  */
494 static void prune_one(struct audit_tree *victim)
495 {
496         spin_lock(&hash_lock);
497         while (!list_empty(&victim->chunks)) {
498                 struct node *p;
499
500                 p = list_entry(victim->chunks.next, struct node, list);
501
502                 untag_chunk(p);
503         }
504         spin_unlock(&hash_lock);
505         put_tree(victim);
506 }
507
508 /* trim the uncommitted chunks from tree */
509
510 static void trim_marked(struct audit_tree *tree)
511 {
512         struct list_head *p, *q;
513         spin_lock(&hash_lock);
514         if (tree->goner) {
515                 spin_unlock(&hash_lock);
516                 return;
517         }
518         /* reorder */
519         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
520                 struct node *node = list_entry(p, struct node, list);
521                 q = p->next;
522                 if (node->index & (1U<<31)) {
523                         list_del_init(p);
524                         list_add(p, &tree->chunks);
525                 }
526         }
527
528         while (!list_empty(&tree->chunks)) {
529                 struct node *node;
530
531                 node = list_entry(tree->chunks.next, struct node, list);
532
533                 /* have we run out of marked? */
534                 if (!(node->index & (1U<<31)))
535                         break;
536
537                 untag_chunk(node);
538         }
539         if (!tree->root && !tree->goner) {
540                 tree->goner = 1;
541                 spin_unlock(&hash_lock);
542                 mutex_lock(&audit_filter_mutex);
543                 kill_rules(tree);
544                 list_del_init(&tree->list);
545                 mutex_unlock(&audit_filter_mutex);
546                 prune_one(tree);
547         } else {
548                 spin_unlock(&hash_lock);
549         }
550 }
551
552 static void audit_schedule_prune(void);
553
554 /* called with audit_filter_mutex */
555 int audit_remove_tree_rule(struct audit_krule *rule)
556 {
557         struct audit_tree *tree;
558         tree = rule->tree;
559         if (tree) {
560                 spin_lock(&hash_lock);
561                 list_del_init(&rule->rlist);
562                 if (list_empty(&tree->rules) && !tree->goner) {
563                         tree->root = NULL;
564                         list_del_init(&tree->same_root);
565                         tree->goner = 1;
566                         list_move(&tree->list, &prune_list);
567                         rule->tree = NULL;
568                         spin_unlock(&hash_lock);
569                         audit_schedule_prune();
570                         return 1;
571                 }
572                 rule->tree = NULL;
573                 spin_unlock(&hash_lock);
574                 return 1;
575         }
576         return 0;
577 }
578
579 static int compare_root(struct vfsmount *mnt, void *arg)
580 {
581         return d_backing_inode(mnt->mnt_root) == arg;
582 }
583
584 void audit_trim_trees(void)
585 {
586         struct list_head cursor;
587
588         mutex_lock(&audit_filter_mutex);
589         list_add(&cursor, &tree_list);
590         while (cursor.next != &tree_list) {
591                 struct audit_tree *tree;
592                 struct path path;
593                 struct vfsmount *root_mnt;
594                 struct node *node;
595                 int err;
596
597                 tree = container_of(cursor.next, struct audit_tree, list);
598                 get_tree(tree);
599                 list_del(&cursor);
600                 list_add(&cursor, &tree->list);
601                 mutex_unlock(&audit_filter_mutex);
602
603                 err = kern_path(tree->pathname, 0, &path);
604                 if (err)
605                         goto skip_it;
606
607                 root_mnt = collect_mounts(&path);
608                 path_put(&path);
609                 if (IS_ERR(root_mnt))
610                         goto skip_it;
611
612                 spin_lock(&hash_lock);
613                 list_for_each_entry(node, &tree->chunks, list) {
614                         struct audit_chunk *chunk = find_chunk(node);
615                         /* this could be NULL if the watch is dying else where... */
616                         struct inode *inode = chunk->mark.inode;
617                         node->index |= 1U<<31;
618                         if (iterate_mounts(compare_root, inode, root_mnt))
619                                 node->index &= ~(1U<<31);
620                 }
621                 spin_unlock(&hash_lock);
622                 trim_marked(tree);
623                 drop_collected_mounts(root_mnt);
624 skip_it:
625                 put_tree(tree);
626                 mutex_lock(&audit_filter_mutex);
627         }
628         list_del(&cursor);
629         mutex_unlock(&audit_filter_mutex);
630 }
631
632 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
633 {
634
635         if (pathname[0] != '/' ||
636             rule->listnr != AUDIT_FILTER_EXIT ||
637             op != Audit_equal ||
638             rule->inode_f || rule->watch || rule->tree)
639                 return -EINVAL;
640         rule->tree = alloc_tree(pathname);
641         if (!rule->tree)
642                 return -ENOMEM;
643         return 0;
644 }
645
646 void audit_put_tree(struct audit_tree *tree)
647 {
648         put_tree(tree);
649 }
650
651 static int tag_mount(struct vfsmount *mnt, void *arg)
652 {
653         return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
654 }
655
656 /*
657  * That gets run when evict_chunk() ends up needing to kill audit_tree.
658  * Runs from a separate thread.
659  */
660 static int prune_tree_thread(void *unused)
661 {
662         for (;;) {
663                 if (list_empty(&prune_list)) {
664                         set_current_state(TASK_INTERRUPTIBLE);
665                         schedule();
666                 }
667
668                 mutex_lock(&audit_cmd_mutex);
669                 mutex_lock(&audit_filter_mutex);
670
671                 while (!list_empty(&prune_list)) {
672                         struct audit_tree *victim;
673
674                         victim = list_entry(prune_list.next,
675                                         struct audit_tree, list);
676                         list_del_init(&victim->list);
677
678                         mutex_unlock(&audit_filter_mutex);
679
680                         prune_one(victim);
681
682                         mutex_lock(&audit_filter_mutex);
683                 }
684
685                 mutex_unlock(&audit_filter_mutex);
686                 mutex_unlock(&audit_cmd_mutex);
687         }
688         return 0;
689 }
690
691 static int audit_launch_prune(void)
692 {
693         if (prune_thread)
694                 return 0;
695         prune_thread = kthread_run(prune_tree_thread, NULL,
696                                 "audit_prune_tree");
697         if (IS_ERR(prune_thread)) {
698                 pr_err("cannot start thread audit_prune_tree");
699                 prune_thread = NULL;
700                 return -ENOMEM;
701         }
702         return 0;
703 }
704
705 /* called with audit_filter_mutex */
706 int audit_add_tree_rule(struct audit_krule *rule)
707 {
708         struct audit_tree *seed = rule->tree, *tree;
709         struct path path;
710         struct vfsmount *mnt;
711         int err;
712
713         rule->tree = NULL;
714         list_for_each_entry(tree, &tree_list, list) {
715                 if (!strcmp(seed->pathname, tree->pathname)) {
716                         put_tree(seed);
717                         rule->tree = tree;
718                         list_add(&rule->rlist, &tree->rules);
719                         return 0;
720                 }
721         }
722         tree = seed;
723         list_add(&tree->list, &tree_list);
724         list_add(&rule->rlist, &tree->rules);
725         /* do not set rule->tree yet */
726         mutex_unlock(&audit_filter_mutex);
727
728         if (unlikely(!prune_thread)) {
729                 err = audit_launch_prune();
730                 if (err)
731                         goto Err;
732         }
733
734         err = kern_path(tree->pathname, 0, &path);
735         if (err)
736                 goto Err;
737         mnt = collect_mounts(&path);
738         path_put(&path);
739         if (IS_ERR(mnt)) {
740                 err = PTR_ERR(mnt);
741                 goto Err;
742         }
743
744         get_tree(tree);
745         err = iterate_mounts(tag_mount, tree, mnt);
746         drop_collected_mounts(mnt);
747
748         if (!err) {
749                 struct node *node;
750                 spin_lock(&hash_lock);
751                 list_for_each_entry(node, &tree->chunks, list)
752                         node->index &= ~(1U<<31);
753                 spin_unlock(&hash_lock);
754         } else {
755                 trim_marked(tree);
756                 goto Err;
757         }
758
759         mutex_lock(&audit_filter_mutex);
760         if (list_empty(&rule->rlist)) {
761                 put_tree(tree);
762                 return -ENOENT;
763         }
764         rule->tree = tree;
765         put_tree(tree);
766
767         return 0;
768 Err:
769         mutex_lock(&audit_filter_mutex);
770         list_del_init(&tree->list);
771         list_del_init(&tree->rules);
772         put_tree(tree);
773         return err;
774 }
775
776 int audit_tag_tree(char *old, char *new)
777 {
778         struct list_head cursor, barrier;
779         int failed = 0;
780         struct path path1, path2;
781         struct vfsmount *tagged;
782         int err;
783
784         err = kern_path(new, 0, &path2);
785         if (err)
786                 return err;
787         tagged = collect_mounts(&path2);
788         path_put(&path2);
789         if (IS_ERR(tagged))
790                 return PTR_ERR(tagged);
791
792         err = kern_path(old, 0, &path1);
793         if (err) {
794                 drop_collected_mounts(tagged);
795                 return err;
796         }
797
798         mutex_lock(&audit_filter_mutex);
799         list_add(&barrier, &tree_list);
800         list_add(&cursor, &barrier);
801
802         while (cursor.next != &tree_list) {
803                 struct audit_tree *tree;
804                 int good_one = 0;
805
806                 tree = container_of(cursor.next, struct audit_tree, list);
807                 get_tree(tree);
808                 list_del(&cursor);
809                 list_add(&cursor, &tree->list);
810                 mutex_unlock(&audit_filter_mutex);
811
812                 err = kern_path(tree->pathname, 0, &path2);
813                 if (!err) {
814                         good_one = path_is_under(&path1, &path2);
815                         path_put(&path2);
816                 }
817
818                 if (!good_one) {
819                         put_tree(tree);
820                         mutex_lock(&audit_filter_mutex);
821                         continue;
822                 }
823
824                 failed = iterate_mounts(tag_mount, tree, tagged);
825                 if (failed) {
826                         put_tree(tree);
827                         mutex_lock(&audit_filter_mutex);
828                         break;
829                 }
830
831                 mutex_lock(&audit_filter_mutex);
832                 spin_lock(&hash_lock);
833                 if (!tree->goner) {
834                         list_del(&tree->list);
835                         list_add(&tree->list, &tree_list);
836                 }
837                 spin_unlock(&hash_lock);
838                 put_tree(tree);
839         }
840
841         while (barrier.prev != &tree_list) {
842                 struct audit_tree *tree;
843
844                 tree = container_of(barrier.prev, struct audit_tree, list);
845                 get_tree(tree);
846                 list_del(&tree->list);
847                 list_add(&tree->list, &barrier);
848                 mutex_unlock(&audit_filter_mutex);
849
850                 if (!failed) {
851                         struct node *node;
852                         spin_lock(&hash_lock);
853                         list_for_each_entry(node, &tree->chunks, list)
854                                 node->index &= ~(1U<<31);
855                         spin_unlock(&hash_lock);
856                 } else {
857                         trim_marked(tree);
858                 }
859
860                 put_tree(tree);
861                 mutex_lock(&audit_filter_mutex);
862         }
863         list_del(&barrier);
864         list_del(&cursor);
865         mutex_unlock(&audit_filter_mutex);
866         path_put(&path1);
867         drop_collected_mounts(tagged);
868         return failed;
869 }
870
871
872 static void audit_schedule_prune(void)
873 {
874         wake_up_process(prune_thread);
875 }
876
877 /*
878  * ... and that one is done if evict_chunk() decides to delay until the end
879  * of syscall.  Runs synchronously.
880  */
881 void audit_kill_trees(struct list_head *list)
882 {
883         mutex_lock(&audit_cmd_mutex);
884         mutex_lock(&audit_filter_mutex);
885
886         while (!list_empty(list)) {
887                 struct audit_tree *victim;
888
889                 victim = list_entry(list->next, struct audit_tree, list);
890                 kill_rules(victim);
891                 list_del_init(&victim->list);
892
893                 mutex_unlock(&audit_filter_mutex);
894
895                 prune_one(victim);
896
897                 mutex_lock(&audit_filter_mutex);
898         }
899
900         mutex_unlock(&audit_filter_mutex);
901         mutex_unlock(&audit_cmd_mutex);
902 }
903
904 /*
905  *  Here comes the stuff asynchronous to auditctl operations
906  */
907
908 static void evict_chunk(struct audit_chunk *chunk)
909 {
910         struct audit_tree *owner;
911         struct list_head *postponed = audit_killed_trees();
912         int need_prune = 0;
913         int n;
914
915         if (chunk->dead)
916                 return;
917
918         chunk->dead = 1;
919         mutex_lock(&audit_filter_mutex);
920         spin_lock(&hash_lock);
921         while (!list_empty(&chunk->trees)) {
922                 owner = list_entry(chunk->trees.next,
923                                    struct audit_tree, same_root);
924                 owner->goner = 1;
925                 owner->root = NULL;
926                 list_del_init(&owner->same_root);
927                 spin_unlock(&hash_lock);
928                 if (!postponed) {
929                         kill_rules(owner);
930                         list_move(&owner->list, &prune_list);
931                         need_prune = 1;
932                 } else {
933                         list_move(&owner->list, postponed);
934                 }
935                 spin_lock(&hash_lock);
936         }
937         list_del_rcu(&chunk->hash);
938         for (n = 0; n < chunk->count; n++)
939                 list_del_init(&chunk->owners[n].list);
940         spin_unlock(&hash_lock);
941         mutex_unlock(&audit_filter_mutex);
942         if (need_prune)
943                 audit_schedule_prune();
944 }
945
946 static int audit_tree_handle_event(struct fsnotify_group *group,
947                                    struct inode *to_tell,
948                                    struct fsnotify_mark *inode_mark,
949                                    struct fsnotify_mark *vfsmount_mark,
950                                    u32 mask, const void *data, int data_type,
951                                    const unsigned char *file_name, u32 cookie)
952 {
953         return 0;
954 }
955
956 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
957 {
958         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
959
960         evict_chunk(chunk);
961
962         /*
963          * We are guaranteed to have at least one reference to the mark from
964          * either the inode or the caller of fsnotify_destroy_mark().
965          */
966         BUG_ON(atomic_read(&entry->refcnt) < 1);
967 }
968
969 static const struct fsnotify_ops audit_tree_ops = {
970         .handle_event = audit_tree_handle_event,
971         .freeing_mark = audit_tree_freeing_mark,
972 };
973
974 static int __init audit_tree_init(void)
975 {
976         int i;
977
978         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
979         if (IS_ERR(audit_tree_group))
980                 audit_panic("cannot initialize fsnotify group for rectree watches");
981
982         for (i = 0; i < HASH_SIZE; i++)
983                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
984
985         return 0;
986 }
987 __initcall(audit_tree_init);