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