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