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
8 struct audit_tree;
9 struct audit_chunk;
10
11 struct 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
23 struct 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
38 static LIST_HEAD(tree_list);
39 static LIST_HEAD(prune_list);
40
41 /*
42 * One struct chunk is attached to each inode of interest.
43 * We replace struct chunk on tagging/untagging.
44 * Rules have pointer to struct audit_tree.
45 * Rules have struct list_head rlist forming a list of rules over
46 * the same tree.
47 * References to struct chunk are collected at audit_inode{,_child}()
48 * time and used in AUDIT_TREE rule matching.
49 * These references are dropped at the same time we are calling
50 * audit_free_names(), etc.
51 *
52 * Cyclic lists galore:
53 * tree.chunks anchors chunk.owners[].list hash_lock
54 * tree.rules anchors rule.rlist audit_filter_mutex
55 * chunk.trees anchors tree.same_root hash_lock
56 * chunk.hash is a hash with middle bits of watch.inode as
57 * a hash function. RCU, hash_lock
58 *
59 * tree is refcounted; one reference for "some rules on rules_list refer to
60 * it", one for each chunk with pointer to it.
61 *
62 * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount
63 * of watch contributes 1 to .refs).
64 *
65 * node.index allows to get from node.list to containing chunk.
66 * MSB of that sucker is stolen to mark taggings that we might have to
67 * revert - several operations have very unpleasant cleanup logics and
68 * that makes a difference. Some.
69 */
70
71 static struct fsnotify_group *audit_tree_group;
72
alloc_tree(const char * s)73 static struct audit_tree *alloc_tree(const char *s)
74 {
75 struct audit_tree *tree;
76
77 tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
78 if (tree) {
79 atomic_set(&tree->count, 1);
80 tree->goner = 0;
81 INIT_LIST_HEAD(&tree->chunks);
82 INIT_LIST_HEAD(&tree->rules);
83 INIT_LIST_HEAD(&tree->list);
84 INIT_LIST_HEAD(&tree->same_root);
85 tree->root = NULL;
86 strcpy(tree->pathname, s);
87 }
88 return tree;
89 }
90
get_tree(struct audit_tree * tree)91 static inline void get_tree(struct audit_tree *tree)
92 {
93 atomic_inc(&tree->count);
94 }
95
put_tree(struct audit_tree * tree)96 static inline void put_tree(struct audit_tree *tree)
97 {
98 if (atomic_dec_and_test(&tree->count))
99 kfree_rcu(tree, head);
100 }
101
102 /* to avoid bringing the entire thing in audit.h */
audit_tree_path(struct audit_tree * tree)103 const char *audit_tree_path(struct audit_tree *tree)
104 {
105 return tree->pathname;
106 }
107
free_chunk(struct audit_chunk * chunk)108 static void free_chunk(struct audit_chunk *chunk)
109 {
110 int i;
111
112 for (i = 0; i < chunk->count; i++) {
113 if (chunk->owners[i].owner)
114 put_tree(chunk->owners[i].owner);
115 }
116 kfree(chunk);
117 }
118
audit_put_chunk(struct audit_chunk * chunk)119 void audit_put_chunk(struct audit_chunk *chunk)
120 {
121 if (atomic_long_dec_and_test(&chunk->refs))
122 free_chunk(chunk);
123 }
124
__put_chunk(struct rcu_head * rcu)125 static void __put_chunk(struct rcu_head *rcu)
126 {
127 struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head);
128 audit_put_chunk(chunk);
129 }
130
audit_tree_destroy_watch(struct fsnotify_mark * entry)131 static void audit_tree_destroy_watch(struct fsnotify_mark *entry)
132 {
133 struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
134 call_rcu(&chunk->head, __put_chunk);
135 }
136
alloc_chunk(int count)137 static struct audit_chunk *alloc_chunk(int count)
138 {
139 struct audit_chunk *chunk;
140 size_t size;
141 int i;
142
143 size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node);
144 chunk = kzalloc(size, GFP_KERNEL);
145 if (!chunk)
146 return NULL;
147
148 INIT_LIST_HEAD(&chunk->hash);
149 INIT_LIST_HEAD(&chunk->trees);
150 chunk->count = count;
151 atomic_long_set(&chunk->refs, 1);
152 for (i = 0; i < count; i++) {
153 INIT_LIST_HEAD(&chunk->owners[i].list);
154 chunk->owners[i].index = i;
155 }
156 fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch);
157 return chunk;
158 }
159
160 enum {HASH_SIZE = 128};
161 static struct list_head chunk_hash_heads[HASH_SIZE];
162 static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock);
163
chunk_hash(const struct inode * inode)164 static inline struct list_head *chunk_hash(const struct inode *inode)
165 {
166 unsigned long n = (unsigned long)inode / L1_CACHE_BYTES;
167 return chunk_hash_heads + n % HASH_SIZE;
168 }
169
170 /* hash_lock & entry->lock is held by caller */
insert_hash(struct audit_chunk * chunk)171 static void insert_hash(struct audit_chunk *chunk)
172 {
173 struct fsnotify_mark *entry = &chunk->mark;
174 struct list_head *list;
175
176 if (!entry->i.inode)
177 return;
178 list = chunk_hash(entry->i.inode);
179 list_add_rcu(&chunk->hash, list);
180 }
181
182 /* called under rcu_read_lock */
audit_tree_lookup(const struct inode * inode)183 struct audit_chunk *audit_tree_lookup(const struct inode *inode)
184 {
185 struct list_head *list = chunk_hash(inode);
186 struct audit_chunk *p;
187
188 list_for_each_entry_rcu(p, list, hash) {
189 /* mark.inode may have gone NULL, but who cares? */
190 if (p->mark.i.inode == inode) {
191 atomic_long_inc(&p->refs);
192 return p;
193 }
194 }
195 return NULL;
196 }
197
audit_tree_match(struct audit_chunk * chunk,struct audit_tree * tree)198 int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree)
199 {
200 int n;
201 for (n = 0; n < chunk->count; n++)
202 if (chunk->owners[n].owner == tree)
203 return 1;
204 return 0;
205 }
206
207 /* tagging and untagging inodes with trees */
208
find_chunk(struct node * p)209 static struct audit_chunk *find_chunk(struct node *p)
210 {
211 int index = p->index & ~(1U<<31);
212 p -= index;
213 return container_of(p, struct audit_chunk, owners[0]);
214 }
215
untag_chunk(struct node * p)216 static void untag_chunk(struct node *p)
217 {
218 struct audit_chunk *chunk = find_chunk(p);
219 struct fsnotify_mark *entry = &chunk->mark;
220 struct audit_chunk *new = NULL;
221 struct audit_tree *owner;
222 int size = chunk->count - 1;
223 int i, j;
224
225 fsnotify_get_mark(entry);
226
227 spin_unlock(&hash_lock);
228
229 if (size)
230 new = alloc_chunk(size);
231
232 spin_lock(&entry->lock);
233 if (chunk->dead || !entry->i.inode) {
234 spin_unlock(&entry->lock);
235 if (new)
236 free_chunk(new);
237 goto out;
238 }
239
240 owner = p->owner;
241
242 if (!size) {
243 chunk->dead = 1;
244 spin_lock(&hash_lock);
245 list_del_init(&chunk->trees);
246 if (owner->root == chunk)
247 owner->root = NULL;
248 list_del_init(&p->list);
249 list_del_rcu(&chunk->hash);
250 spin_unlock(&hash_lock);
251 spin_unlock(&entry->lock);
252 fsnotify_destroy_mark(entry, audit_tree_group);
253 goto out;
254 }
255
256 if (!new)
257 goto Fallback;
258
259 fsnotify_duplicate_mark(&new->mark, entry);
260 if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) {
261 fsnotify_put_mark(&new->mark);
262 goto Fallback;
263 }
264
265 chunk->dead = 1;
266 spin_lock(&hash_lock);
267 list_replace_init(&chunk->trees, &new->trees);
268 if (owner->root == chunk) {
269 list_del_init(&owner->same_root);
270 owner->root = NULL;
271 }
272
273 for (i = j = 0; j <= size; i++, j++) {
274 struct audit_tree *s;
275 if (&chunk->owners[j] == p) {
276 list_del_init(&p->list);
277 i--;
278 continue;
279 }
280 s = chunk->owners[j].owner;
281 new->owners[i].owner = s;
282 new->owners[i].index = chunk->owners[j].index - j + i;
283 if (!s) /* result of earlier fallback */
284 continue;
285 get_tree(s);
286 list_replace_init(&chunk->owners[j].list, &new->owners[i].list);
287 }
288
289 list_replace_rcu(&chunk->hash, &new->hash);
290 list_for_each_entry(owner, &new->trees, same_root)
291 owner->root = new;
292 spin_unlock(&hash_lock);
293 spin_unlock(&entry->lock);
294 fsnotify_destroy_mark(entry, audit_tree_group);
295 fsnotify_put_mark(&new->mark); /* drop initial reference */
296 goto out;
297
298 Fallback:
299 // do the best we can
300 spin_lock(&hash_lock);
301 if (owner->root == chunk) {
302 list_del_init(&owner->same_root);
303 owner->root = NULL;
304 }
305 list_del_init(&p->list);
306 p->owner = NULL;
307 put_tree(owner);
308 spin_unlock(&hash_lock);
309 spin_unlock(&entry->lock);
310 out:
311 fsnotify_put_mark(entry);
312 spin_lock(&hash_lock);
313 }
314
create_chunk(struct inode * inode,struct audit_tree * tree)315 static int create_chunk(struct inode *inode, struct audit_tree *tree)
316 {
317 struct fsnotify_mark *entry;
318 struct audit_chunk *chunk = alloc_chunk(1);
319 if (!chunk)
320 return -ENOMEM;
321
322 entry = &chunk->mark;
323 if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) {
324 fsnotify_put_mark(entry);
325 return -ENOSPC;
326 }
327
328 spin_lock(&entry->lock);
329 spin_lock(&hash_lock);
330 if (tree->goner) {
331 spin_unlock(&hash_lock);
332 chunk->dead = 1;
333 spin_unlock(&entry->lock);
334 fsnotify_destroy_mark(entry, audit_tree_group);
335 fsnotify_put_mark(entry);
336 return 0;
337 }
338 chunk->owners[0].index = (1U << 31);
339 chunk->owners[0].owner = tree;
340 get_tree(tree);
341 list_add(&chunk->owners[0].list, &tree->chunks);
342 if (!tree->root) {
343 tree->root = chunk;
344 list_add(&tree->same_root, &chunk->trees);
345 }
346 insert_hash(chunk);
347 spin_unlock(&hash_lock);
348 spin_unlock(&entry->lock);
349 fsnotify_put_mark(entry); /* drop initial reference */
350 return 0;
351 }
352
353 /* the first tagged inode becomes root of tree */
tag_chunk(struct inode * inode,struct audit_tree * tree)354 static int tag_chunk(struct inode *inode, struct audit_tree *tree)
355 {
356 struct fsnotify_mark *old_entry, *chunk_entry;
357 struct audit_tree *owner;
358 struct audit_chunk *chunk, *old;
359 struct node *p;
360 int n;
361
362 old_entry = fsnotify_find_inode_mark(audit_tree_group, inode);
363 if (!old_entry)
364 return create_chunk(inode, tree);
365
366 old = container_of(old_entry, struct audit_chunk, mark);
367
368 /* are we already there? */
369 spin_lock(&hash_lock);
370 for (n = 0; n < old->count; n++) {
371 if (old->owners[n].owner == tree) {
372 spin_unlock(&hash_lock);
373 fsnotify_put_mark(old_entry);
374 return 0;
375 }
376 }
377 spin_unlock(&hash_lock);
378
379 chunk = alloc_chunk(old->count + 1);
380 if (!chunk) {
381 fsnotify_put_mark(old_entry);
382 return -ENOMEM;
383 }
384
385 chunk_entry = &chunk->mark;
386
387 spin_lock(&old_entry->lock);
388 if (!old_entry->i.inode) {
389 /* old_entry is being shot, lets just lie */
390 spin_unlock(&old_entry->lock);
391 fsnotify_put_mark(old_entry);
392 free_chunk(chunk);
393 return -ENOENT;
394 }
395
396 fsnotify_duplicate_mark(chunk_entry, old_entry);
397 if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) {
398 spin_unlock(&old_entry->lock);
399 fsnotify_put_mark(chunk_entry);
400 fsnotify_put_mark(old_entry);
401 return -ENOSPC;
402 }
403
404 /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */
405 spin_lock(&chunk_entry->lock);
406 spin_lock(&hash_lock);
407
408 /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */
409 if (tree->goner) {
410 spin_unlock(&hash_lock);
411 chunk->dead = 1;
412 spin_unlock(&chunk_entry->lock);
413 spin_unlock(&old_entry->lock);
414
415 fsnotify_destroy_mark(chunk_entry, audit_tree_group);
416
417 fsnotify_put_mark(chunk_entry);
418 fsnotify_put_mark(old_entry);
419 return 0;
420 }
421 list_replace_init(&old->trees, &chunk->trees);
422 for (n = 0, p = chunk->owners; n < old->count; n++, p++) {
423 struct audit_tree *s = old->owners[n].owner;
424 p->owner = s;
425 p->index = old->owners[n].index;
426 if (!s) /* result of fallback in untag */
427 continue;
428 get_tree(s);
429 list_replace_init(&old->owners[n].list, &p->list);
430 }
431 p->index = (chunk->count - 1) | (1U<<31);
432 p->owner = tree;
433 get_tree(tree);
434 list_add(&p->list, &tree->chunks);
435 list_replace_rcu(&old->hash, &chunk->hash);
436 list_for_each_entry(owner, &chunk->trees, same_root)
437 owner->root = chunk;
438 old->dead = 1;
439 if (!tree->root) {
440 tree->root = chunk;
441 list_add(&tree->same_root, &chunk->trees);
442 }
443 spin_unlock(&hash_lock);
444 spin_unlock(&chunk_entry->lock);
445 spin_unlock(&old_entry->lock);
446 fsnotify_destroy_mark(old_entry, audit_tree_group);
447 fsnotify_put_mark(chunk_entry); /* drop initial reference */
448 fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */
449 return 0;
450 }
451
audit_log_remove_rule(struct audit_krule * rule)452 static void audit_log_remove_rule(struct audit_krule *rule)
453 {
454 struct audit_buffer *ab;
455
456 ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
457 if (unlikely(!ab))
458 return;
459 audit_log_format(ab, "op=");
460 audit_log_string(ab, "remove rule");
461 audit_log_format(ab, " dir=");
462 audit_log_untrustedstring(ab, rule->tree->pathname);
463 audit_log_key(ab, rule->filterkey);
464 audit_log_format(ab, " list=%d res=1", rule->listnr);
465 audit_log_end(ab);
466 }
467
kill_rules(struct audit_tree * tree)468 static void kill_rules(struct audit_tree *tree)
469 {
470 struct audit_krule *rule, *next;
471 struct audit_entry *entry;
472
473 list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
474 entry = container_of(rule, struct audit_entry, rule);
475
476 list_del_init(&rule->rlist);
477 if (rule->tree) {
478 /* not a half-baked one */
479 audit_log_remove_rule(rule);
480 rule->tree = NULL;
481 list_del_rcu(&entry->list);
482 list_del(&entry->rule.list);
483 call_rcu(&entry->rcu, audit_free_rule_rcu);
484 }
485 }
486 }
487
488 /*
489 * finish killing struct audit_tree
490 */
prune_one(struct audit_tree * victim)491 static void prune_one(struct audit_tree *victim)
492 {
493 spin_lock(&hash_lock);
494 while (!list_empty(&victim->chunks)) {
495 struct node *p;
496
497 p = list_entry(victim->chunks.next, struct node, list);
498
499 untag_chunk(p);
500 }
501 spin_unlock(&hash_lock);
502 put_tree(victim);
503 }
504
505 /* trim the uncommitted chunks from tree */
506
trim_marked(struct audit_tree * tree)507 static void trim_marked(struct audit_tree *tree)
508 {
509 struct list_head *p, *q;
510 spin_lock(&hash_lock);
511 if (tree->goner) {
512 spin_unlock(&hash_lock);
513 return;
514 }
515 /* reorder */
516 for (p = tree->chunks.next; p != &tree->chunks; p = q) {
517 struct node *node = list_entry(p, struct node, list);
518 q = p->next;
519 if (node->index & (1U<<31)) {
520 list_del_init(p);
521 list_add(p, &tree->chunks);
522 }
523 }
524
525 while (!list_empty(&tree->chunks)) {
526 struct node *node;
527
528 node = list_entry(tree->chunks.next, struct node, list);
529
530 /* have we run out of marked? */
531 if (!(node->index & (1U<<31)))
532 break;
533
534 untag_chunk(node);
535 }
536 if (!tree->root && !tree->goner) {
537 tree->goner = 1;
538 spin_unlock(&hash_lock);
539 mutex_lock(&audit_filter_mutex);
540 kill_rules(tree);
541 list_del_init(&tree->list);
542 mutex_unlock(&audit_filter_mutex);
543 prune_one(tree);
544 } else {
545 spin_unlock(&hash_lock);
546 }
547 }
548
549 static void audit_schedule_prune(void);
550
551 /* called with audit_filter_mutex */
audit_remove_tree_rule(struct audit_krule * rule)552 int audit_remove_tree_rule(struct audit_krule *rule)
553 {
554 struct audit_tree *tree;
555 tree = rule->tree;
556 if (tree) {
557 spin_lock(&hash_lock);
558 list_del_init(&rule->rlist);
559 if (list_empty(&tree->rules) && !tree->goner) {
560 tree->root = NULL;
561 list_del_init(&tree->same_root);
562 tree->goner = 1;
563 list_move(&tree->list, &prune_list);
564 rule->tree = NULL;
565 spin_unlock(&hash_lock);
566 audit_schedule_prune();
567 return 1;
568 }
569 rule->tree = NULL;
570 spin_unlock(&hash_lock);
571 return 1;
572 }
573 return 0;
574 }
575
compare_root(struct vfsmount * mnt,void * arg)576 static int compare_root(struct vfsmount *mnt, void *arg)
577 {
578 return mnt->mnt_root->d_inode == arg;
579 }
580
audit_trim_trees(void)581 void audit_trim_trees(void)
582 {
583 struct list_head cursor;
584
585 mutex_lock(&audit_filter_mutex);
586 list_add(&cursor, &tree_list);
587 while (cursor.next != &tree_list) {
588 struct audit_tree *tree;
589 struct path path;
590 struct vfsmount *root_mnt;
591 struct node *node;
592 int err;
593
594 tree = container_of(cursor.next, struct audit_tree, list);
595 get_tree(tree);
596 list_del(&cursor);
597 list_add(&cursor, &tree->list);
598 mutex_unlock(&audit_filter_mutex);
599
600 err = kern_path(tree->pathname, 0, &path);
601 if (err)
602 goto skip_it;
603
604 root_mnt = collect_mounts(&path);
605 path_put(&path);
606 if (IS_ERR(root_mnt))
607 goto skip_it;
608
609 spin_lock(&hash_lock);
610 list_for_each_entry(node, &tree->chunks, list) {
611 struct audit_chunk *chunk = find_chunk(node);
612 /* this could be NULL if the watch is dying else where... */
613 struct inode *inode = chunk->mark.i.inode;
614 node->index |= 1U<<31;
615 if (iterate_mounts(compare_root, inode, root_mnt))
616 node->index &= ~(1U<<31);
617 }
618 spin_unlock(&hash_lock);
619 trim_marked(tree);
620 drop_collected_mounts(root_mnt);
621 skip_it:
622 put_tree(tree);
623 mutex_lock(&audit_filter_mutex);
624 }
625 list_del(&cursor);
626 mutex_unlock(&audit_filter_mutex);
627 }
628
audit_make_tree(struct audit_krule * rule,char * pathname,u32 op)629 int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op)
630 {
631
632 if (pathname[0] != '/' ||
633 rule->listnr != AUDIT_FILTER_EXIT ||
634 op != Audit_equal ||
635 rule->inode_f || rule->watch || rule->tree)
636 return -EINVAL;
637 rule->tree = alloc_tree(pathname);
638 if (!rule->tree)
639 return -ENOMEM;
640 return 0;
641 }
642
audit_put_tree(struct audit_tree * tree)643 void audit_put_tree(struct audit_tree *tree)
644 {
645 put_tree(tree);
646 }
647
tag_mount(struct vfsmount * mnt,void * arg)648 static int tag_mount(struct vfsmount *mnt, void *arg)
649 {
650 return tag_chunk(mnt->mnt_root->d_inode, arg);
651 }
652
653 /* called with audit_filter_mutex */
audit_add_tree_rule(struct audit_krule * rule)654 int audit_add_tree_rule(struct audit_krule *rule)
655 {
656 struct audit_tree *seed = rule->tree, *tree;
657 struct path path;
658 struct vfsmount *mnt;
659 int err;
660
661 rule->tree = NULL;
662 list_for_each_entry(tree, &tree_list, list) {
663 if (!strcmp(seed->pathname, tree->pathname)) {
664 put_tree(seed);
665 rule->tree = tree;
666 list_add(&rule->rlist, &tree->rules);
667 return 0;
668 }
669 }
670 tree = seed;
671 list_add(&tree->list, &tree_list);
672 list_add(&rule->rlist, &tree->rules);
673 /* do not set rule->tree yet */
674 mutex_unlock(&audit_filter_mutex);
675
676 err = kern_path(tree->pathname, 0, &path);
677 if (err)
678 goto Err;
679 mnt = collect_mounts(&path);
680 path_put(&path);
681 if (IS_ERR(mnt)) {
682 err = PTR_ERR(mnt);
683 goto Err;
684 }
685
686 get_tree(tree);
687 err = iterate_mounts(tag_mount, tree, mnt);
688 drop_collected_mounts(mnt);
689
690 if (!err) {
691 struct node *node;
692 spin_lock(&hash_lock);
693 list_for_each_entry(node, &tree->chunks, list)
694 node->index &= ~(1U<<31);
695 spin_unlock(&hash_lock);
696 } else {
697 trim_marked(tree);
698 goto Err;
699 }
700
701 mutex_lock(&audit_filter_mutex);
702 if (list_empty(&rule->rlist)) {
703 put_tree(tree);
704 return -ENOENT;
705 }
706 rule->tree = tree;
707 put_tree(tree);
708
709 return 0;
710 Err:
711 mutex_lock(&audit_filter_mutex);
712 list_del_init(&tree->list);
713 list_del_init(&tree->rules);
714 put_tree(tree);
715 return err;
716 }
717
audit_tag_tree(char * old,char * new)718 int audit_tag_tree(char *old, char *new)
719 {
720 struct list_head cursor, barrier;
721 int failed = 0;
722 struct path path1, path2;
723 struct vfsmount *tagged;
724 int err;
725
726 err = kern_path(new, 0, &path2);
727 if (err)
728 return err;
729 tagged = collect_mounts(&path2);
730 path_put(&path2);
731 if (IS_ERR(tagged))
732 return PTR_ERR(tagged);
733
734 err = kern_path(old, 0, &path1);
735 if (err) {
736 drop_collected_mounts(tagged);
737 return err;
738 }
739
740 mutex_lock(&audit_filter_mutex);
741 list_add(&barrier, &tree_list);
742 list_add(&cursor, &barrier);
743
744 while (cursor.next != &tree_list) {
745 struct audit_tree *tree;
746 int good_one = 0;
747
748 tree = container_of(cursor.next, struct audit_tree, list);
749 get_tree(tree);
750 list_del(&cursor);
751 list_add(&cursor, &tree->list);
752 mutex_unlock(&audit_filter_mutex);
753
754 err = kern_path(tree->pathname, 0, &path2);
755 if (!err) {
756 good_one = path_is_under(&path1, &path2);
757 path_put(&path2);
758 }
759
760 if (!good_one) {
761 put_tree(tree);
762 mutex_lock(&audit_filter_mutex);
763 continue;
764 }
765
766 failed = iterate_mounts(tag_mount, tree, tagged);
767 if (failed) {
768 put_tree(tree);
769 mutex_lock(&audit_filter_mutex);
770 break;
771 }
772
773 mutex_lock(&audit_filter_mutex);
774 spin_lock(&hash_lock);
775 if (!tree->goner) {
776 list_del(&tree->list);
777 list_add(&tree->list, &tree_list);
778 }
779 spin_unlock(&hash_lock);
780 put_tree(tree);
781 }
782
783 while (barrier.prev != &tree_list) {
784 struct audit_tree *tree;
785
786 tree = container_of(barrier.prev, struct audit_tree, list);
787 get_tree(tree);
788 list_del(&tree->list);
789 list_add(&tree->list, &barrier);
790 mutex_unlock(&audit_filter_mutex);
791
792 if (!failed) {
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 }
801
802 put_tree(tree);
803 mutex_lock(&audit_filter_mutex);
804 }
805 list_del(&barrier);
806 list_del(&cursor);
807 mutex_unlock(&audit_filter_mutex);
808 path_put(&path1);
809 drop_collected_mounts(tagged);
810 return failed;
811 }
812
813 /*
814 * That gets run when evict_chunk() ends up needing to kill audit_tree.
815 * Runs from a separate thread.
816 */
prune_tree_thread(void * unused)817 static int prune_tree_thread(void *unused)
818 {
819 mutex_lock(&audit_cmd_mutex);
820 mutex_lock(&audit_filter_mutex);
821
822 while (!list_empty(&prune_list)) {
823 struct audit_tree *victim;
824
825 victim = list_entry(prune_list.next, struct audit_tree, list);
826 list_del_init(&victim->list);
827
828 mutex_unlock(&audit_filter_mutex);
829
830 prune_one(victim);
831
832 mutex_lock(&audit_filter_mutex);
833 }
834
835 mutex_unlock(&audit_filter_mutex);
836 mutex_unlock(&audit_cmd_mutex);
837 return 0;
838 }
839
audit_schedule_prune(void)840 static void audit_schedule_prune(void)
841 {
842 kthread_run(prune_tree_thread, NULL, "audit_prune_tree");
843 }
844
845 /*
846 * ... and that one is done if evict_chunk() decides to delay until the end
847 * of syscall. Runs synchronously.
848 */
audit_kill_trees(struct list_head * list)849 void audit_kill_trees(struct list_head *list)
850 {
851 mutex_lock(&audit_cmd_mutex);
852 mutex_lock(&audit_filter_mutex);
853
854 while (!list_empty(list)) {
855 struct audit_tree *victim;
856
857 victim = list_entry(list->next, struct audit_tree, list);
858 kill_rules(victim);
859 list_del_init(&victim->list);
860
861 mutex_unlock(&audit_filter_mutex);
862
863 prune_one(victim);
864
865 mutex_lock(&audit_filter_mutex);
866 }
867
868 mutex_unlock(&audit_filter_mutex);
869 mutex_unlock(&audit_cmd_mutex);
870 }
871
872 /*
873 * Here comes the stuff asynchronous to auditctl operations
874 */
875
evict_chunk(struct audit_chunk * chunk)876 static void evict_chunk(struct audit_chunk *chunk)
877 {
878 struct audit_tree *owner;
879 struct list_head *postponed = audit_killed_trees();
880 int need_prune = 0;
881 int n;
882
883 if (chunk->dead)
884 return;
885
886 chunk->dead = 1;
887 mutex_lock(&audit_filter_mutex);
888 spin_lock(&hash_lock);
889 while (!list_empty(&chunk->trees)) {
890 owner = list_entry(chunk->trees.next,
891 struct audit_tree, same_root);
892 owner->goner = 1;
893 owner->root = NULL;
894 list_del_init(&owner->same_root);
895 spin_unlock(&hash_lock);
896 if (!postponed) {
897 kill_rules(owner);
898 list_move(&owner->list, &prune_list);
899 need_prune = 1;
900 } else {
901 list_move(&owner->list, postponed);
902 }
903 spin_lock(&hash_lock);
904 }
905 list_del_rcu(&chunk->hash);
906 for (n = 0; n < chunk->count; n++)
907 list_del_init(&chunk->owners[n].list);
908 spin_unlock(&hash_lock);
909 if (need_prune)
910 audit_schedule_prune();
911 mutex_unlock(&audit_filter_mutex);
912 }
913
audit_tree_handle_event(struct fsnotify_group * group,struct fsnotify_mark * inode_mark,struct fsnotify_mark * vfsmonut_mark,struct fsnotify_event * event)914 static int audit_tree_handle_event(struct fsnotify_group *group,
915 struct fsnotify_mark *inode_mark,
916 struct fsnotify_mark *vfsmonut_mark,
917 struct fsnotify_event *event)
918 {
919 BUG();
920 return -EOPNOTSUPP;
921 }
922
audit_tree_freeing_mark(struct fsnotify_mark * entry,struct fsnotify_group * group)923 static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group)
924 {
925 struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark);
926
927 evict_chunk(chunk);
928
929 /*
930 * We are guaranteed to have at least one reference to the mark from
931 * either the inode or the caller of fsnotify_destroy_mark().
932 */
933 BUG_ON(atomic_read(&entry->refcnt) < 1);
934 }
935
audit_tree_send_event(struct fsnotify_group * group,struct inode * inode,struct fsnotify_mark * inode_mark,struct fsnotify_mark * vfsmount_mark,__u32 mask,void * data,int data_type)936 static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode,
937 struct fsnotify_mark *inode_mark,
938 struct fsnotify_mark *vfsmount_mark,
939 __u32 mask, void *data, int data_type)
940 {
941 return false;
942 }
943
944 static const struct fsnotify_ops audit_tree_ops = {
945 .handle_event = audit_tree_handle_event,
946 .should_send_event = audit_tree_send_event,
947 .free_group_priv = NULL,
948 .free_event_priv = NULL,
949 .freeing_mark = audit_tree_freeing_mark,
950 };
951
audit_tree_init(void)952 static int __init audit_tree_init(void)
953 {
954 int i;
955
956 audit_tree_group = fsnotify_alloc_group(&audit_tree_ops);
957 if (IS_ERR(audit_tree_group))
958 audit_panic("cannot initialize fsnotify group for rectree watches");
959
960 for (i = 0; i < HASH_SIZE; i++)
961 INIT_LIST_HEAD(&chunk_hash_heads[i]);
962
963 return 0;
964 }
965 __initcall(audit_tree_init);
966