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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 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 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);