projects/linux·blob v7.1-rc2 · refs

1093 lines · 25.7 KiB

1// SPDX-License-Identifier: GPL-2.0
2#include "audit.h"
3#include <linux/fsnotify_backend.h>
4#include <linux/namei.h>
5#include <linux/mount.h>
6#include <linux/kthread.h>
7#include <linux/refcount.h>
8#include <linux/slab.h>
9
10struct audit_tree;
11struct audit_chunk;
12
13struct audit_tree {
14 refcount_t count;
15 int goner;
16 struct audit_chunk *root;
17 struct list_head chunks;
18 struct list_head rules;
19 struct list_head list;
20 struct list_head same_root;
21 struct rcu_head head;
22 char pathname[];
23};
24
25struct audit_chunk {
26 struct list_head hash;
27 unsigned long key;
28 struct fsnotify_mark *mark;
29 struct list_head trees; /* with root here */
30 int count;
31 atomic_long_t refs;
32 struct rcu_head head;
33 struct audit_node {
34 struct list_head list;
35 struct audit_tree *owner;
36 unsigned index; /* index; upper bit indicates 'will prune' */
37 } owners[] __counted_by(count);
38};
39
40struct audit_tree_mark {
41 struct fsnotify_mark mark;
42 struct audit_chunk *chunk;
43};
44
45static LIST_HEAD(tree_list);
46static LIST_HEAD(prune_list);
47static struct task_struct *prune_thread;
48
49/*
50 * One struct chunk is attached to each inode of interest through
51 * audit_tree_mark (fsnotify mark). We replace struct chunk on tagging /
52 * untagging, the mark is stable as long as there is chunk attached. The
53 * association between mark and chunk is protected by hash_lock and
54 * audit_tree_group->mark_mutex. Thus as long as we hold
55 * audit_tree_group->mark_mutex and check that the mark is alive by
56 * FSNOTIFY_MARK_FLAG_ATTACHED flag check, we are sure the mark points to
57 * the current chunk.
58 *
59 * Rules have pointer to struct audit_tree.
60 * Rules have struct list_head rlist forming a list of rules over
61 * the same tree.
62 * References to struct chunk are collected at audit_inode{,_child}()
63 * time and used in AUDIT_TREE rule matching.
64 * These references are dropped at the same time we are calling
65 * audit_free_names(), etc.
66 *
67 * Cyclic lists galore:
68 * tree.chunks anchors chunk.owners[].list hash_lock
69 * tree.rules anchors rule.rlist audit_filter_mutex
70 * chunk.trees anchors tree.same_root hash_lock
71 * chunk.hash is a hash with middle bits of watch.inode as
72 * a hash function. RCU, hash_lock
73 *
74 * tree is refcounted; one reference for "some rules on rules_list refer to
75 * it", one for each chunk with pointer to it.
76 *
77 * chunk is refcounted by embedded .refs. Mark associated with the chunk holds
78 * one chunk reference. This reference is dropped either when a mark is going
79 * to be freed (corresponding inode goes away) or when chunk attached to the
80 * mark gets replaced. This reference must be dropped using
81 * audit_mark_put_chunk() to make sure the reference is dropped only after RCU
82 * grace period as it protects RCU readers of the hash table.
83 *
84 * node.index allows to get from node.list to containing chunk.
85 * MSB of that sucker is stolen to mark taggings that we might have to
86 * revert - several operations have very unpleasant cleanup logics and
87 * that makes a difference. Some.
88 */
89
90static struct fsnotify_group *audit_tree_group __ro_after_init;
91static struct kmem_cache *audit_tree_mark_cachep __ro_after_init;
92
93static struct audit_tree *alloc_tree(const char *s)
94{
95 struct audit_tree *tree;
96 size_t sz;
97
98 sz = strlen(s) + 1;
99 tree = kmalloc_flex(*tree, pathname, sz);
100 if (tree) {
101 refcount_set(&tree->count, 1);
102 tree->goner = 0;
103 INIT_LIST_HEAD(&tree->chunks);
104 INIT_LIST_HEAD(&tree->rules);
105 INIT_LIST_HEAD(&tree->list);
106 INIT_LIST_HEAD(&tree->same_root);
107 tree->root = NULL;
108 strscpy(tree->pathname, s, sz);
109 }
110 return tree;
111}
112
113static inline void get_tree(struct audit_tree *tree)
114{
115 refcount_inc(&tree->count);
116}
117
118static inline void put_tree(struct audit_tree *tree)
119{
120 if (refcount_dec_and_test(&tree->count))
121 kfree_rcu(tree, head);
122}
123
124/* to avoid bringing the entire thing in audit.h */
125const char *audit_tree_path(struct audit_tree *tree)
126{
127 return tree->pathname;
128}
129
130static void free_chunk(struct audit_chunk *chunk)
131{
132 int i;
133
134 for (i = 0; i < chunk->count; i++) {
135 if (chunk->owners[i].owner)
136 put_tree(chunk->owners[i].owner);
137 }
138 kfree(chunk);
139}
140
141void audit_put_chunk(struct audit_chunk *chunk)
142{
143 if (atomic_long_dec_and_test(&chunk->refs))
144 free_chunk(chunk);
145}
146
147static void __put_chunk(struct rcu_head *rcu)
148{
149 struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
150 audit_put_chunk(chunk);
151}
152
153/*
154 * Drop reference to the chunk that was held by the mark. This is the reference
155 * that gets dropped after we've removed the chunk from the hash table and we
156 * use it to make sure chunk cannot be freed before RCU grace period expires.
157 */
158static void audit_mark_put_chunk(struct audit_chunk *chunk)
159{
160 call_rcu(&chunk->head, __put_chunk);
161}
162
163static inline struct audit_tree_mark *audit_mark(struct fsnotify_mark *mark)
164{
165 return container_of(mark, struct audit_tree_mark, mark);
166}
167
168static struct audit_chunk *mark_chunk(struct fsnotify_mark *mark)
169{
170 return audit_mark(mark)->chunk;
171}
172
173static void audit_tree_destroy_watch(struct fsnotify_mark *mark)
174{
175 kmem_cache_free(audit_tree_mark_cachep, audit_mark(mark));
176}
177
178static struct fsnotify_mark *alloc_mark(void)
179{
180 struct audit_tree_mark *amark;
181
182 amark = kmem_cache_zalloc(audit_tree_mark_cachep, GFP_KERNEL);
183 if (!amark)
184 return NULL;
185 fsnotify_init_mark(&amark->mark, audit_tree_group);
186 amark->mark.mask = FS_IN_IGNORED;
187 return &amark->mark;
188}
189
190static struct audit_chunk *alloc_chunk(int count)
191{
192 struct audit_chunk *chunk;
193 int i;
194
195 chunk = kzalloc_flex(*chunk, owners, count);
196 if (!chunk)
197 return NULL;
198
199 INIT_LIST_HEAD(&chunk->hash);
200 INIT_LIST_HEAD(&chunk->trees);
201 chunk->count = count;
202 atomic_long_set(&chunk->refs, 1);
203 for (i = 0; i < count; i++) {
204 INIT_LIST_HEAD(&chunk->owners[i].list);
205 chunk->owners[i].index = i;
206 }
207 return chunk;
208}
209
210enum {HASH_SIZE = 128};
211static struct list_head chunk_hash_heads[HASH_SIZE];
212static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
213
214/* Function to return search key in our hash from inode. */
215static unsigned long inode_to_key(const struct inode *inode)
216{
217 /* Use address pointed to by connector->obj as the key */
218 return (unsigned long)&inode->i_fsnotify_marks;
219}
220
221static inline struct list_head *chunk_hash(unsigned long key)
222{
223 unsigned long n = key / L1_CACHE_BYTES;
224 return chunk_hash_heads + n % HASH_SIZE;
225}
226
227/* hash_lock & mark->group->mark_mutex is held by caller */
228static void insert_hash(struct audit_chunk *chunk)
229{
230 struct list_head *list;
231
232 /*
233 * Make sure chunk is fully initialized before making it visible in the
234 * hash. Pairs with a data dependency barrier in READ_ONCE() in
235 * audit_tree_lookup().
236 */
237 smp_wmb();
238 WARN_ON_ONCE(!chunk->key);
239 list = chunk_hash(chunk->key);
240 list_add_rcu(&chunk->hash, list);
241}
242
243/* called under rcu_read_lock */
244struct audit_chunk *audit_tree_lookup(const struct inode *inode)
245{
246 unsigned long key = inode_to_key(inode);
247 struct list_head *list = chunk_hash(key);
248 struct audit_chunk *p;
249
250 list_for_each_entry_rcu(p, list, hash) {
251 /*
252 * We use a data dependency barrier in READ_ONCE() to make sure
253 * the chunk we see is fully initialized.
254 */
255 if (READ_ONCE(p->key) == key) {
256 atomic_long_inc(&p->refs);
257 return p;
258 }
259 }
260 return NULL;
261}
262
263bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
264{
265 int n;
266 for (n = 0; n < chunk->count; n++)
267 if (chunk->owners[n].owner == tree)
268 return true;
269 return false;
270}
271
272/* tagging and untagging inodes with trees */
273
274static struct audit_chunk *find_chunk(struct audit_node *p)
275{
276 int index = p->index & ~(1U<<31);
277 p -= index;
278 return container_of(p, struct audit_chunk, owners[0]);
279}
280
281static void replace_mark_chunk(struct fsnotify_mark *mark,
282 struct audit_chunk *chunk)
283{
284 struct audit_chunk *old;
285
286 assert_spin_locked(&hash_lock);
287 old = mark_chunk(mark);
288 audit_mark(mark)->chunk = chunk;
289 if (chunk)
290 chunk->mark = mark;
291 if (old)
292 old->mark = NULL;
293}
294
295static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old)
296{
297 struct audit_tree *owner;
298 int i, j;
299
300 new->key = old->key;
301 list_splice_init(&old->trees, &new->trees);
302 list_for_each_entry(owner, &new->trees, same_root)
303 owner->root = new;
304 for (i = j = 0; j < old->count; i++, j++) {
305 if (!old->owners[j].owner) {
306 i--;
307 continue;
308 }
309 owner = old->owners[j].owner;
310 new->owners[i].owner = owner;
311 new->owners[i].index = old->owners[j].index - j + i;
312 if (!owner) /* result of earlier fallback */
313 continue;
314 get_tree(owner);
315 list_replace_init(&old->owners[j].list, &new->owners[i].list);
316 }
317 replace_mark_chunk(old->mark, new);
318 /*
319 * Make sure chunk is fully initialized before making it visible in the
320 * hash. Pairs with a data dependency barrier in READ_ONCE() in
321 * audit_tree_lookup().
322 */
323 smp_wmb();
324 list_replace_rcu(&old->hash, &new->hash);
325}
326
327static void remove_chunk_node(struct audit_chunk *chunk, struct audit_node *p)
328{
329 struct audit_tree *owner = p->owner;
330
331 if (owner->root == chunk) {
332 list_del_init(&owner->same_root);
333 owner->root = NULL;
334 }
335 list_del_init(&p->list);
336 p->owner = NULL;
337 put_tree(owner);
338}
339
340static int chunk_count_trees(struct audit_chunk *chunk)
341{
342 int i;
343 int ret = 0;
344
345 for (i = 0; i < chunk->count; i++)
346 if (chunk->owners[i].owner)
347 ret++;
348 return ret;
349}
350
351static void untag_chunk(struct audit_chunk *chunk, struct fsnotify_mark *mark)
352{
353 struct audit_chunk *new;
354 int size;
355
356 fsnotify_group_lock(audit_tree_group);
357 /*
358 * mark_mutex stabilizes chunk attached to the mark so we can check
359 * whether it didn't change while we've dropped hash_lock.
360 */
361 if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) ||
362 mark_chunk(mark) != chunk)
363 goto out_mutex;
364
365 size = chunk_count_trees(chunk);
366 if (!size) {
367 spin_lock(&hash_lock);
368 list_del_init(&chunk->trees);
369 list_del_rcu(&chunk->hash);
370 replace_mark_chunk(mark, NULL);
371 spin_unlock(&hash_lock);
372 fsnotify_detach_mark(mark);
373 fsnotify_group_unlock(audit_tree_group);
374 audit_mark_put_chunk(chunk);
375 fsnotify_free_mark(mark);
376 return;
377 }
378
379 new = alloc_chunk(size);
380 if (!new)
381 goto out_mutex;
382
383 spin_lock(&hash_lock);
384 /*
385 * This has to go last when updating chunk as once replace_chunk() is
386 * called, new RCU readers can see the new chunk.
387 */
388 replace_chunk(new, chunk);
389 spin_unlock(&hash_lock);
390 fsnotify_group_unlock(audit_tree_group);
391 audit_mark_put_chunk(chunk);
392 return;
393
394out_mutex:
395 fsnotify_group_unlock(audit_tree_group);
396}
397
398/* Call with group->mark_mutex held, releases it */
399static int create_chunk(struct inode *inode, struct audit_tree *tree)
400{
401 struct fsnotify_mark *mark;
402 struct audit_chunk *chunk = alloc_chunk(1);
403
404 if (!chunk) {
405 fsnotify_group_unlock(audit_tree_group);
406 return -ENOMEM;
407 }
408
409 mark = alloc_mark();
410 if (!mark) {
411 fsnotify_group_unlock(audit_tree_group);
412 kfree(chunk);
413 return -ENOMEM;
414 }
415
416 if (fsnotify_add_inode_mark_locked(mark, inode, 0)) {
417 fsnotify_group_unlock(audit_tree_group);
418 fsnotify_put_mark(mark);
419 kfree(chunk);
420 return -ENOSPC;
421 }
422
423 spin_lock(&hash_lock);
424 if (tree->goner) {
425 spin_unlock(&hash_lock);
426 fsnotify_detach_mark(mark);
427 fsnotify_group_unlock(audit_tree_group);
428 fsnotify_free_mark(mark);
429 fsnotify_put_mark(mark);
430 kfree(chunk);
431 return 0;
432 }
433 replace_mark_chunk(mark, chunk);
434 chunk->owners[0].index = (1U << 31);
435 chunk->owners[0].owner = tree;
436 get_tree(tree);
437 list_add(&chunk->owners[0].list, &tree->chunks);
438 if (!tree->root) {
439 tree->root = chunk;
440 list_add(&tree->same_root, &chunk->trees);
441 }
442 chunk->key = inode_to_key(inode);
443 /*
444 * Inserting into the hash table has to go last as once we do that RCU
445 * readers can see the chunk.
446 */
447 insert_hash(chunk);
448 spin_unlock(&hash_lock);
449 fsnotify_group_unlock(audit_tree_group);
450 /*
451 * Drop our initial reference. When mark we point to is getting freed,
452 * we get notification through ->freeing_mark callback and cleanup
453 * chunk pointing to this mark.
454 */
455 fsnotify_put_mark(mark);
456 return 0;
457}
458
459/* the first tagged inode becomes root of tree */
460static int tag_chunk(struct inode *inode, struct audit_tree *tree)
461{
462 struct fsnotify_mark *mark;
463 struct audit_chunk *chunk, *old;
464 struct audit_node *p;
465 int n;
466
467 fsnotify_group_lock(audit_tree_group);
468 mark = fsnotify_find_inode_mark(inode, audit_tree_group);
469 if (!mark)
470 return create_chunk(inode, tree);
471
472 /*
473 * Found mark is guaranteed to be attached and mark_mutex protects mark
474 * from getting detached and thus it makes sure there is chunk attached
475 * to the mark.
476 */
477 /* are we already there? */
478 spin_lock(&hash_lock);
479 old = mark_chunk(mark);
480 for (n = 0; n < old->count; n++) {
481 if (old->owners[n].owner == tree) {
482 spin_unlock(&hash_lock);
483 fsnotify_group_unlock(audit_tree_group);
484 fsnotify_put_mark(mark);
485 return 0;
486 }
487 }
488 spin_unlock(&hash_lock);
489
490 chunk = alloc_chunk(old->count + 1);
491 if (!chunk) {
492 fsnotify_group_unlock(audit_tree_group);
493 fsnotify_put_mark(mark);
494 return -ENOMEM;
495 }
496
497 spin_lock(&hash_lock);
498 if (tree->goner) {
499 spin_unlock(&hash_lock);
500 fsnotify_group_unlock(audit_tree_group);
501 fsnotify_put_mark(mark);
502 kfree(chunk);
503 return 0;
504 }
505 p = &chunk->owners[chunk->count - 1];
506 p->index = (chunk->count - 1) | (1U<<31);
507 p->owner = tree;
508 get_tree(tree);
509 list_add(&p->list, &tree->chunks);
510 if (!tree->root) {
511 tree->root = chunk;
512 list_add(&tree->same_root, &chunk->trees);
513 }
514 /*
515 * This has to go last when updating chunk as once replace_chunk() is
516 * called, new RCU readers can see the new chunk.
517 */
518 replace_chunk(chunk, old);
519 spin_unlock(&hash_lock);
520 fsnotify_group_unlock(audit_tree_group);
521 fsnotify_put_mark(mark); /* pair to fsnotify_find_mark */
522 audit_mark_put_chunk(old);
523
524 return 0;
525}
526
527static void audit_tree_log_remove_rule(struct audit_context *context,
528 struct audit_krule *rule)
529{
530 struct audit_buffer *ab;
531
532 if (!audit_enabled)
533 return;
534 ab = audit_log_start(context, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
535 if (unlikely(!ab))
536 return;
537 audit_log_format(ab, "op=remove_rule dir=");
538 audit_log_untrustedstring(ab, rule->tree->pathname);
539 audit_log_key(ab, rule->filterkey);
540 audit_log_format(ab, " list=%d res=1", rule->listnr);
541 audit_log_end(ab);
542}
543
544static void kill_rules(struct audit_context *context, struct audit_tree *tree)
545{
546 struct audit_krule *rule, *next;
547 struct audit_entry *entry;
548
549 list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
550 entry = container_of(rule, struct audit_entry, rule);
551
552 list_del_init(&rule->rlist);
553 if (rule->tree) {
554 /* not a half-baked one */
555 audit_tree_log_remove_rule(context, rule);
556 if (entry->rule.exe)
557 audit_remove_mark(entry->rule.exe);
558 rule->tree = NULL;
559 list_del_rcu(&entry->list);
560 list_del(&entry->rule.list);
561 call_rcu(&entry->rcu, audit_free_rule_rcu);
562 }
563 }
564}
565
566/*
567 * Remove tree from chunks. If 'tagged' is set, remove tree only from tagged
568 * chunks. The function expects tagged chunks are all at the beginning of the
569 * chunks list.
570 */
571static void prune_tree_chunks(struct audit_tree *victim, bool tagged)
572{
573 spin_lock(&hash_lock);
574 while (!list_empty(&victim->chunks)) {
575 struct audit_node *p;
576 struct audit_chunk *chunk;
577 struct fsnotify_mark *mark;
578
579 p = list_first_entry(&victim->chunks, struct audit_node, list);
580 /* have we run out of marked? */
581 if (tagged && !(p->index & (1U<<31)))
582 break;
583 chunk = find_chunk(p);
584 mark = chunk->mark;
585 remove_chunk_node(chunk, p);
586 /* Racing with audit_tree_freeing_mark()? */
587 if (!mark)
588 continue;
589 fsnotify_get_mark(mark);
590 spin_unlock(&hash_lock);
591
592 untag_chunk(chunk, mark);
593 fsnotify_put_mark(mark);
594
595 spin_lock(&hash_lock);
596 }
597 spin_unlock(&hash_lock);
598}
599
600/*
601 * finish killing struct audit_tree
602 */
603static void prune_one(struct audit_tree *victim)
604{
605 prune_tree_chunks(victim, false);
606 put_tree(victim);
607}
608
609/* trim the uncommitted chunks from tree */
610
611static void trim_marked(struct audit_tree *tree)
612{
613 struct list_head *p, *q;
614 spin_lock(&hash_lock);
615 if (tree->goner) {
616 spin_unlock(&hash_lock);
617 return;
618 }
619 /* reorder */
620 for (p = tree->chunks.next; p != &tree->chunks; p = q) {
621 struct audit_node *node = list_entry(p, struct audit_node, list);
622 q = p->next;
623 if (node->index & (1U<<31)) {
624 list_del_init(p);
625 list_add(p, &tree->chunks);
626 }
627 }
628 spin_unlock(&hash_lock);
629
630 prune_tree_chunks(tree, true);
631
632 spin_lock(&hash_lock);
633 if (!tree->root && !tree->goner) {
634 tree->goner = 1;
635 spin_unlock(&hash_lock);
636 mutex_lock(&audit_filter_mutex);
637 kill_rules(audit_context(), tree);
638 list_del_init(&tree->list);
639 mutex_unlock(&audit_filter_mutex);
640 prune_one(tree);
641 } else {
642 spin_unlock(&hash_lock);
643 }
644}
645
646static void audit_schedule_prune(void);
647
648/* called with audit_filter_mutex */
649int audit_remove_tree_rule(struct audit_krule *rule)
650{
651 struct audit_tree *tree;
652 tree = rule->tree;
653 if (tree) {
654 spin_lock(&hash_lock);
655 list_del_init(&rule->rlist);
656 if (list_empty(&tree->rules) && !tree->goner) {
657 tree->root = NULL;
658 list_del_init(&tree->same_root);
659 tree->goner = 1;
660 list_move(&tree->list, &prune_list);
661 rule->tree = NULL;
662 spin_unlock(&hash_lock);
663 audit_schedule_prune();
664 return 1;
665 }
666 rule->tree = NULL;
667 spin_unlock(&hash_lock);
668 return 1;
669 }
670 return 0;
671}
672
673void audit_trim_trees(void)
674{
675 struct list_head cursor;
676
677 mutex_lock(&audit_filter_mutex);
678 list_add(&cursor, &tree_list);
679 while (cursor.next != &tree_list) {
680 struct audit_tree *tree;
681 struct path path;
682 struct audit_node *node;
683 const struct path *paths;
684 struct path array[16];
685 int err;
686
687 tree = container_of(cursor.next, struct audit_tree, list);
688 get_tree(tree);
689 list_move(&cursor, &tree->list);
690 mutex_unlock(&audit_filter_mutex);
691
692 err = kern_path(tree->pathname, 0, &path);
693 if (err)
694 goto skip_it;
695
696 paths = collect_paths(&path, array, 16);
697 path_put(&path);
698 if (IS_ERR(paths))
699 goto skip_it;
700
701 spin_lock(&hash_lock);
702 list_for_each_entry(node, &tree->chunks, list) {
703 struct audit_chunk *chunk = find_chunk(node);
704 /* this could be NULL if the watch is dying else where... */
705 node->index |= 1U<<31;
706 for (const struct path *p = paths; p->dentry; p++) {
707 struct inode *inode = p->dentry->d_inode;
708 if (inode_to_key(inode) == chunk->key) {
709 node->index &= ~(1U<<31);
710 break;
711 }
712 }
713 }
714 spin_unlock(&hash_lock);
715 trim_marked(tree);
716 drop_collected_paths(paths, array);
717skip_it:
718 put_tree(tree);
719 mutex_lock(&audit_filter_mutex);
720 }
721 list_del(&cursor);
722 mutex_unlock(&audit_filter_mutex);
723}
724
725int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
726{
727
728 if (pathname[0] != '/' ||
729 (rule->listnr != AUDIT_FILTER_EXIT &&
730 rule->listnr != AUDIT_FILTER_URING_EXIT) ||
731 op != Audit_equal ||
732 rule->inode_f || rule->watch || rule->tree)
733 return -EINVAL;
734 rule->tree = alloc_tree(pathname);
735 if (!rule->tree)
736 return -ENOMEM;
737 return 0;
738}
739
740void audit_put_tree(struct audit_tree *tree)
741{
742 put_tree(tree);
743}
744
745static int tag_mounts(const struct path *paths, struct audit_tree *tree)
746{
747 for (const struct path *p = paths; p->dentry; p++) {
748 int err = tag_chunk(p->dentry->d_inode, tree);
749 if (err)
750 return err;
751 }
752 return 0;
753}
754
755/*
756 * That gets run when evict_chunk() ends up needing to kill audit_tree.
757 * Runs from a separate thread.
758 */
759static int prune_tree_thread(void *unused)
760{
761 for (;;) {
762 if (list_empty(&prune_list)) {
763 set_current_state(TASK_INTERRUPTIBLE);
764 schedule();
765 }
766
767 audit_ctl_lock();
768 mutex_lock(&audit_filter_mutex);
769
770 while (!list_empty(&prune_list)) {
771 struct audit_tree *victim;
772
773 victim = list_entry(prune_list.next,
774 struct audit_tree, list);
775 list_del_init(&victim->list);
776
777 mutex_unlock(&audit_filter_mutex);
778
779 prune_one(victim);
780
781 mutex_lock(&audit_filter_mutex);
782 }
783
784 mutex_unlock(&audit_filter_mutex);
785 audit_ctl_unlock();
786 }
787 return 0;
788}
789
790static int audit_launch_prune(void)
791{
792 if (prune_thread)
793 return 0;
794 prune_thread = kthread_run(prune_tree_thread, NULL,
795 "audit_prune_tree");
796 if (IS_ERR(prune_thread)) {
797 pr_err("cannot start thread audit_prune_tree");
798 prune_thread = NULL;
799 return -ENOMEM;
800 }
801 return 0;
802}
803
804/* called with audit_filter_mutex */
805int audit_add_tree_rule(struct audit_krule *rule)
806{
807 struct audit_tree *seed = rule->tree, *tree;
808 struct path path;
809 struct path array[16];
810 const struct path *paths;
811 int err;
812
813 rule->tree = NULL;
814 list_for_each_entry(tree, &tree_list, list) {
815 if (!strcmp(seed->pathname, tree->pathname)) {
816 put_tree(seed);
817 rule->tree = tree;
818 list_add(&rule->rlist, &tree->rules);
819 return 0;
820 }
821 }
822 tree = seed;
823 list_add(&tree->list, &tree_list);
824 list_add(&rule->rlist, &tree->rules);
825 /* do not set rule->tree yet */
826 mutex_unlock(&audit_filter_mutex);
827
828 if (unlikely(!prune_thread)) {
829 err = audit_launch_prune();
830 if (err)
831 goto Err;
832 }
833
834 err = kern_path(tree->pathname, 0, &path);
835 if (err)
836 goto Err;
837 paths = collect_paths(&path, array, 16);
838 path_put(&path);
839 if (IS_ERR(paths)) {
840 err = PTR_ERR(paths);
841 goto Err;
842 }
843
844 get_tree(tree);
845 err = tag_mounts(paths, tree);
846 drop_collected_paths(paths, array);
847
848 if (!err) {
849 struct audit_node *node;
850 spin_lock(&hash_lock);
851 list_for_each_entry(node, &tree->chunks, list)
852 node->index &= ~(1U<<31);
853 spin_unlock(&hash_lock);
854 } else {
855 trim_marked(tree);
856 goto Err;
857 }
858
859 mutex_lock(&audit_filter_mutex);
860 if (list_empty(&rule->rlist)) {
861 put_tree(tree);
862 return -ENOENT;
863 }
864 rule->tree = tree;
865 put_tree(tree);
866
867 return 0;
868Err:
869 mutex_lock(&audit_filter_mutex);
870 list_del_init(&tree->list);
871 list_del_init(&tree->rules);
872 put_tree(tree);
873 return err;
874}
875
876int audit_tag_tree(char *old, char *new)
877{
878 struct list_head cursor, barrier;
879 int failed = 0;
880 struct path path1, path2;
881 struct path array[16];
882 const struct path *paths;
883 int err;
884
885 err = kern_path(new, 0, &path2);
886 if (err)
887 return err;
888 paths = collect_paths(&path2, array, 16);
889 path_put(&path2);
890 if (IS_ERR(paths))
891 return PTR_ERR(paths);
892
893 err = kern_path(old, 0, &path1);
894 if (err) {
895 drop_collected_paths(paths, array);
896 return err;
897 }
898
899 mutex_lock(&audit_filter_mutex);
900 list_add(&barrier, &tree_list);
901 list_add(&cursor, &barrier);
902
903 while (cursor.next != &tree_list) {
904 struct audit_tree *tree;
905 int good_one = 0;
906
907 tree = container_of(cursor.next, struct audit_tree, list);
908 get_tree(tree);
909 list_move(&cursor, &tree->list);
910 mutex_unlock(&audit_filter_mutex);
911
912 err = kern_path(tree->pathname, 0, &path2);
913 if (!err) {
914 good_one = path_is_under(&path1, &path2);
915 path_put(&path2);
916 }
917
918 if (!good_one) {
919 put_tree(tree);
920 mutex_lock(&audit_filter_mutex);
921 continue;
922 }
923
924 failed = tag_mounts(paths, tree);
925 if (failed) {
926 put_tree(tree);
927 mutex_lock(&audit_filter_mutex);
928 break;
929 }
930
931 mutex_lock(&audit_filter_mutex);
932 spin_lock(&hash_lock);
933 if (!tree->goner) {
934 list_move(&tree->list, &tree_list);
935 }
936 spin_unlock(&hash_lock);
937 put_tree(tree);
938 }
939
940 while (barrier.prev != &tree_list) {
941 struct audit_tree *tree;
942
943 tree = container_of(barrier.prev, struct audit_tree, list);
944 get_tree(tree);
945 list_move(&tree->list, &barrier);
946 mutex_unlock(&audit_filter_mutex);
947
948 if (!failed) {
949 struct audit_node *node;
950 spin_lock(&hash_lock);
951 list_for_each_entry(node, &tree->chunks, list)
952 node->index &= ~(1U<<31);
953 spin_unlock(&hash_lock);
954 } else {
955 trim_marked(tree);
956 }
957
958 put_tree(tree);
959 mutex_lock(&audit_filter_mutex);
960 }
961 list_del(&barrier);
962 list_del(&cursor);
963 mutex_unlock(&audit_filter_mutex);
964 path_put(&path1);
965 drop_collected_paths(paths, array);
966 return failed;
967}
968
969
970static void audit_schedule_prune(void)
971{
972 wake_up_process(prune_thread);
973}
974
975/*
976 * ... and that one is done if evict_chunk() decides to delay until the end
977 * of syscall. Runs synchronously.
978 */
979void audit_kill_trees(struct audit_context *context)
980{
981 struct list_head *list = &context->killed_trees;
982
983 audit_ctl_lock();
984 mutex_lock(&audit_filter_mutex);
985
986 while (!list_empty(list)) {
987 struct audit_tree *victim;
988
989 victim = list_entry(list->next, struct audit_tree, list);
990 kill_rules(context, victim);
991 list_del_init(&victim->list);
992
993 mutex_unlock(&audit_filter_mutex);
994
995 prune_one(victim);
996
997 mutex_lock(&audit_filter_mutex);
998 }
999
1000 mutex_unlock(&audit_filter_mutex);
1001 audit_ctl_unlock();
1002}
1003
1004/*
1005 * Here comes the stuff asynchronous to auditctl operations
1006 */
1007
1008static void evict_chunk(struct audit_chunk *chunk)
1009{
1010 struct audit_tree *owner;
1011 struct list_head *postponed = audit_killed_trees();
1012 int need_prune = 0;
1013 int n;
1014
1015 mutex_lock(&audit_filter_mutex);
1016 spin_lock(&hash_lock);
1017 while (!list_empty(&chunk->trees)) {
1018 owner = list_entry(chunk->trees.next,
1019 struct audit_tree, same_root);
1020 owner->goner = 1;
1021 owner->root = NULL;
1022 list_del_init(&owner->same_root);
1023 spin_unlock(&hash_lock);
1024 if (!postponed) {
1025 kill_rules(audit_context(), owner);
1026 list_move(&owner->list, &prune_list);
1027 need_prune = 1;
1028 } else {
1029 list_move(&owner->list, postponed);
1030 }
1031 spin_lock(&hash_lock);
1032 }
1033 list_del_rcu(&chunk->hash);
1034 for (n = 0; n < chunk->count; n++)
1035 list_del_init(&chunk->owners[n].list);
1036 spin_unlock(&hash_lock);
1037 mutex_unlock(&audit_filter_mutex);
1038 if (need_prune)
1039 audit_schedule_prune();
1040}
1041
1042static int audit_tree_handle_event(struct fsnotify_mark *mark, u32 mask,
1043 struct inode *inode, struct inode *dir,
1044 const struct qstr *file_name, u32 cookie)
1045{
1046 return 0;
1047}
1048
1049static void audit_tree_freeing_mark(struct fsnotify_mark *mark,
1050 struct fsnotify_group *group)
1051{
1052 struct audit_chunk *chunk;
1053
1054 fsnotify_group_lock(mark->group);
1055 spin_lock(&hash_lock);
1056 chunk = mark_chunk(mark);
1057 replace_mark_chunk(mark, NULL);
1058 spin_unlock(&hash_lock);
1059 fsnotify_group_unlock(mark->group);
1060 if (chunk) {
1061 evict_chunk(chunk);
1062 audit_mark_put_chunk(chunk);
1063 }
1064
1065 /*
1066 * We are guaranteed to have at least one reference to the mark from
1067 * either the inode or the caller of fsnotify_destroy_mark().
1068 */
1069 BUG_ON(refcount_read(&mark->refcnt) < 1);
1070}
1071
1072static const struct fsnotify_ops audit_tree_ops = {
1073 .handle_inode_event = audit_tree_handle_event,
1074 .freeing_mark = audit_tree_freeing_mark,
1075 .free_mark = audit_tree_destroy_watch,
1076};
1077
1078static int __init audit_tree_init(void)
1079{
1080 int i;
1081
1082 audit_tree_mark_cachep = KMEM_CACHE(audit_tree_mark, SLAB_PANIC);
1083
1084 audit_tree_group = fsnotify_alloc_group(&audit_tree_ops, 0);
1085 if (IS_ERR(audit_tree_group))
1086 audit_panic("cannot initialize fsnotify group for rectree watches");
1087
1088 for (i = 0; i < HASH_SIZE; i++)
1089 INIT_LIST_HEAD(&chunk_hash_heads[i]);
1090
1091 return 0;
1092}
1093__initcall(audit_tree_init);