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[karo-tx-linux.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/refcount.h>
7 #include <linux/slab.h>
8
9 struct audit_tree;
10 struct audit_chunk;
11
12 struct audit_tree {
13         refcount_t count;
14         int goner;
15         struct audit_chunk *root;
16         struct list_head chunks;
17         struct list_head rules;
18         struct list_head list;
19         struct list_head same_root;
20         struct rcu_head head;
21         char pathname[];
22 };
23
24 struct audit_chunk {
25         struct list_head hash;
26         struct fsnotify_mark mark;
27         struct list_head trees;         /* with root here */
28         int dead;
29         int count;
30         atomic_long_t refs;
31         struct rcu_head head;
32         struct node {
33                 struct list_head list;
34                 struct audit_tree *owner;
35                 unsigned index;         /* index; upper bit indicates 'will prune' */
36         } owners[];
37 };
38
39 static LIST_HEAD(tree_list);
40 static LIST_HEAD(prune_list);
41 static struct task_struct *prune_thread;
42
43 /*
44  * One struct chunk is attached to each inode of interest.
45  * We replace struct chunk on tagging/untagging.
46  * Rules have pointer to struct audit_tree.
47  * Rules have struct list_head rlist forming a list of rules over
48  * the same tree.
49  * References to struct chunk are collected at audit_inode{,_child}()
50  * time and used in AUDIT_TREE rule matching.
51  * These references are dropped at the same time we are calling
52  * audit_free_names(), etc.
53  *
54  * Cyclic lists galore:
55  * tree.chunks anchors chunk.owners[].list                      hash_lock
56  * tree.rules anchors rule.rlist                                audit_filter_mutex
57  * chunk.trees anchors tree.same_root                           hash_lock
58  * chunk.hash is a hash with middle bits of watch.inode as
59  * a hash function.                                             RCU, hash_lock
60  *
61  * tree is refcounted; one reference for "some rules on rules_list refer to
62  * it", one for each chunk with pointer to it.
63  *
64  * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
65  * of watch contributes 1 to .refs).
66  *
67  * node.index allows to get from node.list to containing chunk.
68  * MSB of that sucker is stolen to mark taggings that we might have to
69  * revert - several operations have very unpleasant cleanup logics and
70  * that makes a difference.  Some.
71  */
72
73 static struct fsnotify_group *audit_tree_group;
74
75 static struct audit_tree *alloc_tree(const char *s)
76 {
77         struct audit_tree *tree;
78
79         tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
80         if (tree) {
81                 refcount_set(&tree->count, 1);
82                 tree->goner = 0;
83                 INIT_LIST_HEAD(&tree->chunks);
84                 INIT_LIST_HEAD(&tree->rules);
85                 INIT_LIST_HEAD(&tree->list);
86                 INIT_LIST_HEAD(&tree->same_root);
87                 tree->root = NULL;
88                 strcpy(tree->pathname, s);
89         }
90         return tree;
91 }
92
93 static inline void get_tree(struct audit_tree *tree)
94 {
95         refcount_inc(&tree->count);
96 }
97
98 static inline void put_tree(struct audit_tree *tree)
99 {
100         if (refcount_dec_and_test(&tree->count))
101                 kfree_rcu(tree, head);
102 }
103
104 /* to avoid bringing the entire thing in audit.h */
105 const char *audit_tree_path(struct audit_tree *tree)
106 {
107         return tree->pathname;
108 }
109
110 static void free_chunk(struct audit_chunk *chunk)
111 {
112         int i;
113
114         for (i = 0; i < chunk->count; i++) {
115                 if (chunk->owners[i].owner)
116                         put_tree(chunk->owners[i].owner);
117         }
118         kfree(chunk);
119 }
120
121 void audit_put_chunk(struct audit_chunk *chunk)
122 {
123         if (atomic_long_dec_and_test(&chunk->refs))
124                 free_chunk(chunk);
125 }
126
127 static void __put_chunk(struct rcu_head *rcu)
128 {
129         struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
130         audit_put_chunk(chunk);
131 }
132
133 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
134 {
135         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
136         call_rcu(&chunk->head, __put_chunk);
137 }
138
139 static struct audit_chunk *alloc_chunk(int count)
140 {
141         struct audit_chunk *chunk;
142         size_t size;
143         int i;
144
145         size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
146         chunk = kzalloc(size, GFP_KERNEL);
147         if (!chunk)
148                 return NULL;
149
150         INIT_LIST_HEAD(&chunk->hash);
151         INIT_LIST_HEAD(&chunk->trees);
152         chunk->count = count;
153         atomic_long_set(&chunk->refs, 1);
154         for (i = 0; i < count; i++) {
155                 INIT_LIST_HEAD(&chunk->owners[i].list);
156                 chunk->owners[i].index = i;
157         }
158         fsnotify_init_mark(&chunk->mark, audit_tree_group);
159         chunk->mark.mask = FS_IN_IGNORED;
160         return chunk;
161 }
162
163 enum {HASH_SIZE = 128};
164 static struct list_head chunk_hash_heads[HASH_SIZE];
165 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
166
167 /* Function to return search key in our hash from inode. */
168 static unsigned long inode_to_key(const struct inode *inode)
169 {
170         return (unsigned long)inode;
171 }
172
173 /*
174  * Function to return search key in our hash from chunk. Key 0 is special and
175  * should never be present in the hash.
176  */
177 static unsigned long chunk_to_key(struct audit_chunk *chunk)
178 {
179         /*
180          * We have a reference to the mark so it should be attached to a
181          * connector.
182          */
183         if (WARN_ON_ONCE(!chunk->mark.connector))
184                 return 0;
185         return (unsigned long)chunk->mark.connector->inode;
186 }
187
188 static inline struct list_head *chunk_hash(unsigned long key)
189 {
190         unsigned long n = key / L1_CACHE_BYTES;
191         return chunk_hash_heads + n % HASH_SIZE;
192 }
193
194 /* hash_lock & entry->lock is held by caller */
195 static void insert_hash(struct audit_chunk *chunk)
196 {
197         unsigned long key = chunk_to_key(chunk);
198         struct list_head *list;
199
200         if (!(chunk->mark.flags & FSNOTIFY_MARK_FLAG_ATTACHED))
201                 return;
202         list = chunk_hash(key);
203         list_add_rcu(&chunk->hash, list);
204 }
205
206 /* called under rcu_read_lock */
207 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
208 {
209         unsigned long key = inode_to_key(inode);
210         struct list_head *list = chunk_hash(key);
211         struct audit_chunk *p;
212
213         list_for_each_entry_rcu(p, list, hash) {
214                 if (chunk_to_key(p) == key) {
215                         atomic_long_inc(&p->refs);
216                         return p;
217                 }
218         }
219         return NULL;
220 }
221
222 bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
223 {
224         int n;
225         for (n = 0; n < chunk->count; n++)
226                 if (chunk->owners[n].owner == tree)
227                         return true;
228         return false;
229 }
230
231 /* tagging and untagging inodes with trees */
232
233 static struct audit_chunk *find_chunk(struct node *p)
234 {
235         int index = p->index & ~(1U<<31);
236         p -= index;
237         return container_of(p, struct audit_chunk, owners[0]);
238 }
239
240 static void untag_chunk(struct node *p)
241 {
242         struct audit_chunk *chunk = find_chunk(p);
243         struct fsnotify_mark *entry = &chunk->mark;
244         struct audit_chunk *new = NULL;
245         struct audit_tree *owner;
246         int size = chunk->count - 1;
247         int i, j;
248
249         fsnotify_get_mark(entry);
250
251         spin_unlock(&hash_lock);
252
253         if (size)
254                 new = alloc_chunk(size);
255
256         mutex_lock(&entry->group->mark_mutex);
257         spin_lock(&entry->lock);
258         /*
259          * mark_mutex protects mark from getting detached and thus also from
260          * mark->connector->inode getting NULL.
261          */
262         if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
263                 spin_unlock(&entry->lock);
264                 mutex_unlock(&entry->group->mark_mutex);
265                 if (new)
266                         fsnotify_put_mark(&new->mark);
267                 goto out;
268         }
269
270         owner = p->owner;
271
272         if (!size) {
273                 chunk->dead = 1;
274                 spin_lock(&hash_lock);
275                 list_del_init(&chunk->trees);
276                 if (owner->root == chunk)
277                         owner->root = NULL;
278                 list_del_init(&p->list);
279                 list_del_rcu(&chunk->hash);
280                 spin_unlock(&hash_lock);
281                 spin_unlock(&entry->lock);
282                 mutex_unlock(&entry->group->mark_mutex);
283                 fsnotify_destroy_mark(entry, audit_tree_group);
284                 goto out;
285         }
286
287         if (!new)
288                 goto Fallback;
289
290         if (fsnotify_add_mark_locked(&new->mark, entry->connector->inode,
291                                      NULL, 1)) {
292                 fsnotify_put_mark(&new->mark);
293                 goto Fallback;
294         }
295
296         chunk->dead = 1;
297         spin_lock(&hash_lock);
298         list_replace_init(&chunk->trees, &new->trees);
299         if (owner->root == chunk) {
300                 list_del_init(&owner->same_root);
301                 owner->root = NULL;
302         }
303
304         for (i = j = 0; j <= size; i++, j++) {
305                 struct audit_tree *s;
306                 if (&chunk->owners[j] == p) {
307                         list_del_init(&p->list);
308                         i--;
309                         continue;
310                 }
311                 s = chunk->owners[j].owner;
312                 new->owners[i].owner = s;
313                 new->owners[i].index = chunk->owners[j].index - j + i;
314                 if (!s) /* result of earlier fallback */
315                         continue;
316                 get_tree(s);
317                 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
318         }
319
320         list_replace_rcu(&chunk->hash, &new->hash);
321         list_for_each_entry(owner, &new->trees, same_root)
322                 owner->root = new;
323         spin_unlock(&hash_lock);
324         spin_unlock(&entry->lock);
325         mutex_unlock(&entry->group->mark_mutex);
326         fsnotify_destroy_mark(entry, audit_tree_group);
327         fsnotify_put_mark(&new->mark);  /* drop initial reference */
328         goto out;
329
330 Fallback:
331         // do the best we can
332         spin_lock(&hash_lock);
333         if (owner->root == chunk) {
334                 list_del_init(&owner->same_root);
335                 owner->root = NULL;
336         }
337         list_del_init(&p->list);
338         p->owner = NULL;
339         put_tree(owner);
340         spin_unlock(&hash_lock);
341         spin_unlock(&entry->lock);
342         mutex_unlock(&entry->group->mark_mutex);
343 out:
344         fsnotify_put_mark(entry);
345         spin_lock(&hash_lock);
346 }
347
348 static int create_chunk(struct inode *inode, struct audit_tree *tree)
349 {
350         struct fsnotify_mark *entry;
351         struct audit_chunk *chunk = alloc_chunk(1);
352         if (!chunk)
353                 return -ENOMEM;
354
355         entry = &chunk->mark;
356         if (fsnotify_add_mark(entry, inode, NULL, 0)) {
357                 fsnotify_put_mark(entry);
358                 return -ENOSPC;
359         }
360
361         spin_lock(&entry->lock);
362         spin_lock(&hash_lock);
363         if (tree->goner) {
364                 spin_unlock(&hash_lock);
365                 chunk->dead = 1;
366                 spin_unlock(&entry->lock);
367                 fsnotify_destroy_mark(entry, audit_tree_group);
368                 fsnotify_put_mark(entry);
369                 return 0;
370         }
371         chunk->owners[0].index = (1U << 31);
372         chunk->owners[0].owner = tree;
373         get_tree(tree);
374         list_add(&chunk->owners[0].list, &tree->chunks);
375         if (!tree->root) {
376                 tree->root = chunk;
377                 list_add(&tree->same_root, &chunk->trees);
378         }
379         insert_hash(chunk);
380         spin_unlock(&hash_lock);
381         spin_unlock(&entry->lock);
382         fsnotify_put_mark(entry);       /* drop initial reference */
383         return 0;
384 }
385
386 /* the first tagged inode becomes root of tree */
387 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
388 {
389         struct fsnotify_mark *old_entry, *chunk_entry;
390         struct audit_tree *owner;
391         struct audit_chunk *chunk, *old;
392         struct node *p;
393         int n;
394
395         old_entry = fsnotify_find_mark(&inode->i_fsnotify_marks,
396                                        audit_tree_group);
397         if (!old_entry)
398                 return create_chunk(inode, tree);
399
400         old = container_of(old_entry, struct audit_chunk, mark);
401
402         /* are we already there? */
403         spin_lock(&hash_lock);
404         for (n = 0; n < old->count; n++) {
405                 if (old->owners[n].owner == tree) {
406                         spin_unlock(&hash_lock);
407                         fsnotify_put_mark(old_entry);
408                         return 0;
409                 }
410         }
411         spin_unlock(&hash_lock);
412
413         chunk = alloc_chunk(old->count + 1);
414         if (!chunk) {
415                 fsnotify_put_mark(old_entry);
416                 return -ENOMEM;
417         }
418
419         chunk_entry = &chunk->mark;
420
421         mutex_lock(&old_entry->group->mark_mutex);
422         spin_lock(&old_entry->lock);
423         /*
424          * mark_mutex protects mark from getting detached and thus also from
425          * mark->connector->inode getting NULL.
426          */
427         if (!(old_entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) {
428                 /* old_entry is being shot, lets just lie */
429                 spin_unlock(&old_entry->lock);
430                 mutex_unlock(&old_entry->group->mark_mutex);
431                 fsnotify_put_mark(old_entry);
432                 fsnotify_put_mark(&chunk->mark);
433                 return -ENOENT;
434         }
435
436         if (fsnotify_add_mark_locked(chunk_entry,
437                              old_entry->connector->inode, NULL, 1)) {
438                 spin_unlock(&old_entry->lock);
439                 mutex_unlock(&old_entry->group->mark_mutex);
440                 fsnotify_put_mark(chunk_entry);
441                 fsnotify_put_mark(old_entry);
442                 return -ENOSPC;
443         }
444
445         /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
446         spin_lock(&chunk_entry->lock);
447         spin_lock(&hash_lock);
448
449         /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
450         if (tree->goner) {
451                 spin_unlock(&hash_lock);
452                 chunk->dead = 1;
453                 spin_unlock(&chunk_entry->lock);
454                 spin_unlock(&old_entry->lock);
455                 mutex_unlock(&old_entry->group->mark_mutex);
456
457                 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
458
459                 fsnotify_put_mark(chunk_entry);
460                 fsnotify_put_mark(old_entry);
461                 return 0;
462         }
463         list_replace_init(&old->trees, &chunk->trees);
464         for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
465                 struct audit_tree *s = old->owners[n].owner;
466                 p->owner = s;
467                 p->index = old->owners[n].index;
468                 if (!s) /* result of fallback in untag */
469                         continue;
470                 get_tree(s);
471                 list_replace_init(&old->owners[n].list, &p->list);
472         }
473         p->index = (chunk->count - 1) | (1U<<31);
474         p->owner = tree;
475         get_tree(tree);
476         list_add(&p->list, &tree->chunks);
477         list_replace_rcu(&old->hash, &chunk->hash);
478         list_for_each_entry(owner, &chunk->trees, same_root)
479                 owner->root = chunk;
480         old->dead = 1;
481         if (!tree->root) {
482                 tree->root = chunk;
483                 list_add(&tree->same_root, &chunk->trees);
484         }
485         spin_unlock(&hash_lock);
486         spin_unlock(&chunk_entry->lock);
487         spin_unlock(&old_entry->lock);
488         mutex_unlock(&old_entry->group->mark_mutex);
489         fsnotify_destroy_mark(old_entry, audit_tree_group);
490         fsnotify_put_mark(chunk_entry); /* drop initial reference */
491         fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
492         return 0;
493 }
494
495 static void audit_tree_log_remove_rule(struct audit_krule *rule)
496 {
497         struct audit_buffer *ab;
498
499         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
500         if (unlikely(!ab))
501                 return;
502         audit_log_format(ab, "op=remove_rule");
503         audit_log_format(ab, " dir=");
504         audit_log_untrustedstring(ab, rule->tree->pathname);
505         audit_log_key(ab, rule->filterkey);
506         audit_log_format(ab, " list=%d res=1", rule->listnr);
507         audit_log_end(ab);
508 }
509
510 static void kill_rules(struct audit_tree *tree)
511 {
512         struct audit_krule *rule, *next;
513         struct audit_entry *entry;
514
515         list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
516                 entry = container_of(rule, struct audit_entry, rule);
517
518                 list_del_init(&rule->rlist);
519                 if (rule->tree) {
520                         /* not a half-baked one */
521                         audit_tree_log_remove_rule(rule);
522                         if (entry->rule.exe)
523                                 audit_remove_mark(entry->rule.exe);
524                         rule->tree = NULL;
525                         list_del_rcu(&entry->list);
526                         list_del(&entry->rule.list);
527                         call_rcu(&entry->rcu, audit_free_rule_rcu);
528                 }
529         }
530 }
531
532 /*
533  * finish killing struct audit_tree
534  */
535 static void prune_one(struct audit_tree *victim)
536 {
537         spin_lock(&hash_lock);
538         while (!list_empty(&victim->chunks)) {
539                 struct node *p;
540
541                 p = list_entry(victim->chunks.next, struct node, list);
542
543                 untag_chunk(p);
544         }
545         spin_unlock(&hash_lock);
546         put_tree(victim);
547 }
548
549 /* trim the uncommitted chunks from tree */
550
551 static void trim_marked(struct audit_tree *tree)
552 {
553         struct list_head *p, *q;
554         spin_lock(&hash_lock);
555         if (tree->goner) {
556                 spin_unlock(&hash_lock);
557                 return;
558         }
559         /* reorder */
560         for (p = tree->chunks.next; p != &tree->chunks; p = q) {
561                 struct node *node = list_entry(p, struct node, list);
562                 q = p->next;
563                 if (node->index & (1U<<31)) {
564                         list_del_init(p);
565                         list_add(p, &tree->chunks);
566                 }
567         }
568
569         while (!list_empty(&tree->chunks)) {
570                 struct node *node;
571
572                 node = list_entry(tree->chunks.next, struct node, list);
573
574                 /* have we run out of marked? */
575                 if (!(node->index & (1U<<31)))
576                         break;
577
578                 untag_chunk(node);
579         }
580         if (!tree->root && !tree->goner) {
581                 tree->goner = 1;
582                 spin_unlock(&hash_lock);
583                 mutex_lock(&audit_filter_mutex);
584                 kill_rules(tree);
585                 list_del_init(&tree->list);
586                 mutex_unlock(&audit_filter_mutex);
587                 prune_one(tree);
588         } else {
589                 spin_unlock(&hash_lock);
590         }
591 }
592
593 static void audit_schedule_prune(void);
594
595 /* called with audit_filter_mutex */
596 int audit_remove_tree_rule(struct audit_krule *rule)
597 {
598         struct audit_tree *tree;
599         tree = rule->tree;
600         if (tree) {
601                 spin_lock(&hash_lock);
602                 list_del_init(&rule->rlist);
603                 if (list_empty(&tree->rules) && !tree->goner) {
604                         tree->root = NULL;
605                         list_del_init(&tree->same_root);
606                         tree->goner = 1;
607                         list_move(&tree->list, &prune_list);
608                         rule->tree = NULL;
609                         spin_unlock(&hash_lock);
610                         audit_schedule_prune();
611                         return 1;
612                 }
613                 rule->tree = NULL;
614                 spin_unlock(&hash_lock);
615                 return 1;
616         }
617         return 0;
618 }
619
620 static int compare_root(struct vfsmount *mnt, void *arg)
621 {
622         return inode_to_key(d_backing_inode(mnt->mnt_root)) ==
623                (unsigned long)arg;
624 }
625
626 void audit_trim_trees(void)
627 {
628         struct list_head cursor;
629
630         mutex_lock(&audit_filter_mutex);
631         list_add(&cursor, &tree_list);
632         while (cursor.next != &tree_list) {
633                 struct audit_tree *tree;
634                 struct path path;
635                 struct vfsmount *root_mnt;
636                 struct node *node;
637                 int err;
638
639                 tree = container_of(cursor.next, struct audit_tree, list);
640                 get_tree(tree);
641                 list_del(&cursor);
642                 list_add(&cursor, &tree->list);
643                 mutex_unlock(&audit_filter_mutex);
644
645                 err = kern_path(tree->pathname, 0, &path);
646                 if (err)
647                         goto skip_it;
648
649                 root_mnt = collect_mounts(&path);
650                 path_put(&path);
651                 if (IS_ERR(root_mnt))
652                         goto skip_it;
653
654                 spin_lock(&hash_lock);
655                 list_for_each_entry(node, &tree->chunks, list) {
656                         struct audit_chunk *chunk = find_chunk(node);
657                         /* this could be NULL if the watch is dying else where... */
658                         node->index |= 1U<<31;
659                         if (iterate_mounts(compare_root,
660                                            (void *)chunk_to_key(chunk),
661                                            root_mnt))
662                                 node->index &= ~(1U<<31);
663                 }
664                 spin_unlock(&hash_lock);
665                 trim_marked(tree);
666                 drop_collected_mounts(root_mnt);
667 skip_it:
668                 put_tree(tree);
669                 mutex_lock(&audit_filter_mutex);
670         }
671         list_del(&cursor);
672         mutex_unlock(&audit_filter_mutex);
673 }
674
675 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
676 {
677
678         if (pathname[0] != '/' ||
679             rule->listnr != AUDIT_FILTER_EXIT ||
680             op != Audit_equal ||
681             rule->inode_f || rule->watch || rule->tree)
682                 return -EINVAL;
683         rule->tree = alloc_tree(pathname);
684         if (!rule->tree)
685                 return -ENOMEM;
686         return 0;
687 }
688
689 void audit_put_tree(struct audit_tree *tree)
690 {
691         put_tree(tree);
692 }
693
694 static int tag_mount(struct vfsmount *mnt, void *arg)
695 {
696         return tag_chunk(d_backing_inode(mnt->mnt_root), arg);
697 }
698
699 /*
700  * That gets run when evict_chunk() ends up needing to kill audit_tree.
701  * Runs from a separate thread.
702  */
703 static int prune_tree_thread(void *unused)
704 {
705         for (;;) {
706                 if (list_empty(&prune_list)) {
707                         set_current_state(TASK_INTERRUPTIBLE);
708                         schedule();
709                 }
710
711                 mutex_lock(&audit_cmd_mutex);
712                 mutex_lock(&audit_filter_mutex);
713
714                 while (!list_empty(&prune_list)) {
715                         struct audit_tree *victim;
716
717                         victim = list_entry(prune_list.next,
718                                         struct audit_tree, list);
719                         list_del_init(&victim->list);
720
721                         mutex_unlock(&audit_filter_mutex);
722
723                         prune_one(victim);
724
725                         mutex_lock(&audit_filter_mutex);
726                 }
727
728                 mutex_unlock(&audit_filter_mutex);
729                 mutex_unlock(&audit_cmd_mutex);
730         }
731         return 0;
732 }
733
734 static int audit_launch_prune(void)
735 {
736         if (prune_thread)
737                 return 0;
738         prune_thread = kthread_run(prune_tree_thread, NULL,
739                                 "audit_prune_tree");
740         if (IS_ERR(prune_thread)) {
741                 pr_err("cannot start thread audit_prune_tree");
742                 prune_thread = NULL;
743                 return -ENOMEM;
744         }
745         return 0;
746 }
747
748 /* called with audit_filter_mutex */
749 int audit_add_tree_rule(struct audit_krule *rule)
750 {
751         struct audit_tree *seed = rule->tree, *tree;
752         struct path path;
753         struct vfsmount *mnt;
754         int err;
755
756         rule->tree = NULL;
757         list_for_each_entry(tree, &tree_list, list) {
758                 if (!strcmp(seed->pathname, tree->pathname)) {
759                         put_tree(seed);
760                         rule->tree = tree;
761                         list_add(&rule->rlist, &tree->rules);
762                         return 0;
763                 }
764         }
765         tree = seed;
766         list_add(&tree->list, &tree_list);
767         list_add(&rule->rlist, &tree->rules);
768         /* do not set rule->tree yet */
769         mutex_unlock(&audit_filter_mutex);
770
771         if (unlikely(!prune_thread)) {
772                 err = audit_launch_prune();
773                 if (err)
774                         goto Err;
775         }
776
777         err = kern_path(tree->pathname, 0, &path);
778         if (err)
779                 goto Err;
780         mnt = collect_mounts(&path);
781         path_put(&path);
782         if (IS_ERR(mnt)) {
783                 err = PTR_ERR(mnt);
784                 goto Err;
785         }
786
787         get_tree(tree);
788         err = iterate_mounts(tag_mount, tree, mnt);
789         drop_collected_mounts(mnt);
790
791         if (!err) {
792                 struct node *node;
793                 spin_lock(&hash_lock);
794                 list_for_each_entry(node, &tree->chunks, list)
795                         node->index &= ~(1U<<31);
796                 spin_unlock(&hash_lock);
797         } else {
798                 trim_marked(tree);
799                 goto Err;
800         }
801
802         mutex_lock(&audit_filter_mutex);
803         if (list_empty(&rule->rlist)) {
804                 put_tree(tree);
805                 return -ENOENT;
806         }
807         rule->tree = tree;
808         put_tree(tree);
809
810         return 0;
811 Err:
812         mutex_lock(&audit_filter_mutex);
813         list_del_init(&tree->list);
814         list_del_init(&tree->rules);
815         put_tree(tree);
816         return err;
817 }
818
819 int audit_tag_tree(char *old, char *new)
820 {
821         struct list_head cursor, barrier;
822         int failed = 0;
823         struct path path1, path2;
824         struct vfsmount *tagged;
825         int err;
826
827         err = kern_path(new, 0, &path2);
828         if (err)
829                 return err;
830         tagged = collect_mounts(&path2);
831         path_put(&path2);
832         if (IS_ERR(tagged))
833                 return PTR_ERR(tagged);
834
835         err = kern_path(old, 0, &path1);
836         if (err) {
837                 drop_collected_mounts(tagged);
838                 return err;
839         }
840
841         mutex_lock(&audit_filter_mutex);
842         list_add(&barrier, &tree_list);
843         list_add(&cursor, &barrier);
844
845         while (cursor.next != &tree_list) {
846                 struct audit_tree *tree;
847                 int good_one = 0;
848
849                 tree = container_of(cursor.next, struct audit_tree, list);
850                 get_tree(tree);
851                 list_del(&cursor);
852                 list_add(&cursor, &tree->list);
853                 mutex_unlock(&audit_filter_mutex);
854
855                 err = kern_path(tree->pathname, 0, &path2);
856                 if (!err) {
857                         good_one = path_is_under(&path1, &path2);
858                         path_put(&path2);
859                 }
860
861                 if (!good_one) {
862                         put_tree(tree);
863                         mutex_lock(&audit_filter_mutex);
864                         continue;
865                 }
866
867                 failed = iterate_mounts(tag_mount, tree, tagged);
868                 if (failed) {
869                         put_tree(tree);
870                         mutex_lock(&audit_filter_mutex);
871                         break;
872                 }
873
874                 mutex_lock(&audit_filter_mutex);
875                 spin_lock(&hash_lock);
876                 if (!tree->goner) {
877                         list_del(&tree->list);
878                         list_add(&tree->list, &tree_list);
879                 }
880                 spin_unlock(&hash_lock);
881                 put_tree(tree);
882         }
883
884         while (barrier.prev != &tree_list) {
885                 struct audit_tree *tree;
886
887                 tree = container_of(barrier.prev, struct audit_tree, list);
888                 get_tree(tree);
889                 list_del(&tree->list);
890                 list_add(&tree->list, &barrier);
891                 mutex_unlock(&audit_filter_mutex);
892
893                 if (!failed) {
894                         struct node *node;
895                         spin_lock(&hash_lock);
896                         list_for_each_entry(node, &tree->chunks, list)
897                                 node->index &= ~(1U<<31);
898                         spin_unlock(&hash_lock);
899                 } else {
900                         trim_marked(tree);
901                 }
902
903                 put_tree(tree);
904                 mutex_lock(&audit_filter_mutex);
905         }
906         list_del(&barrier);
907         list_del(&cursor);
908         mutex_unlock(&audit_filter_mutex);
909         path_put(&path1);
910         drop_collected_mounts(tagged);
911         return failed;
912 }
913
914
915 static void audit_schedule_prune(void)
916 {
917         wake_up_process(prune_thread);
918 }
919
920 /*
921  * ... and that one is done if evict_chunk() decides to delay until the end
922  * of syscall.  Runs synchronously.
923  */
924 void audit_kill_trees(struct list_head *list)
925 {
926         mutex_lock(&audit_cmd_mutex);
927         mutex_lock(&audit_filter_mutex);
928
929         while (!list_empty(list)) {
930                 struct audit_tree *victim;
931
932                 victim = list_entry(list->next, struct audit_tree, list);
933                 kill_rules(victim);
934                 list_del_init(&victim->list);
935
936                 mutex_unlock(&audit_filter_mutex);
937
938                 prune_one(victim);
939
940                 mutex_lock(&audit_filter_mutex);
941         }
942
943         mutex_unlock(&audit_filter_mutex);
944         mutex_unlock(&audit_cmd_mutex);
945 }
946
947 /*
948  *  Here comes the stuff asynchronous to auditctl operations
949  */
950
951 static void evict_chunk(struct audit_chunk *chunk)
952 {
953         struct audit_tree *owner;
954         struct list_head *postponed = audit_killed_trees();
955         int need_prune = 0;
956         int n;
957
958         if (chunk->dead)
959                 return;
960
961         chunk->dead = 1;
962         mutex_lock(&audit_filter_mutex);
963         spin_lock(&hash_lock);
964         while (!list_empty(&chunk->trees)) {
965                 owner = list_entry(chunk->trees.next,
966                                    struct audit_tree, same_root);
967                 owner->goner = 1;
968                 owner->root = NULL;
969                 list_del_init(&owner->same_root);
970                 spin_unlock(&hash_lock);
971                 if (!postponed) {
972                         kill_rules(owner);
973                         list_move(&owner->list, &prune_list);
974                         need_prune = 1;
975                 } else {
976                         list_move(&owner->list, postponed);
977                 }
978                 spin_lock(&hash_lock);
979         }
980         list_del_rcu(&chunk->hash);
981         for (n = 0; n < chunk->count; n++)
982                 list_del_init(&chunk->owners[n].list);
983         spin_unlock(&hash_lock);
984         mutex_unlock(&audit_filter_mutex);
985         if (need_prune)
986                 audit_schedule_prune();
987 }
988
989 static int audit_tree_handle_event(struct fsnotify_group *group,
990                                    struct inode *to_tell,
991                                    struct fsnotify_mark *inode_mark,
992                                    struct fsnotify_mark *vfsmount_mark,
993                                    u32 mask, const void *data, int data_type,
994                                    const unsigned char *file_name, u32 cookie,
995                                    struct fsnotify_iter_info *iter_info)
996 {
997         return 0;
998 }
999
1000 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
1001 {
1002         struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
1003
1004         evict_chunk(chunk);
1005
1006         /*
1007          * We are guaranteed to have at least one reference to the mark from
1008          * either the inode or the caller of fsnotify_destroy_mark().
1009          */
1010         BUG_ON(atomic_read(&entry->refcnt) < 1);
1011 }
1012
1013 static const struct fsnotify_ops audit_tree_ops = {
1014         .handle_event = audit_tree_handle_event,
1015         .freeing_mark = audit_tree_freeing_mark,
1016         .free_mark = audit_tree_destroy_watch,
1017 };
1018
1019 static int __init audit_tree_init(void)
1020 {
1021         int i;
1022
1023         audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
1024         if (IS_ERR(audit_tree_group))
1025                 audit_panic("cannot initialize fsnotify group for rectree watches");
1026
1027         for (i = 0; i < HASH_SIZE; i++)
1028                 INIT_LIST_HEAD(&chunk_hash_heads[i]);
1029
1030         return 0;
1031 }
1032 __initcall(audit_tree_init);