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 | |
10 | struct audit_tree; |
11 | struct audit_chunk; |
12 | |
13 | struct 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 | |
25 | struct 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 | |
40 | static LIST_HEAD(tree_list); |
41 | static LIST_HEAD(prune_list); |
42 | static 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 | |
74 | static struct fsnotify_group *audit_tree_group; |
75 | |
76 | static 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 | |
94 | static inline void get_tree(struct audit_tree *tree) |
95 | { |
96 | refcount_inc(&tree->count); |
97 | } |
98 | |
99 | static 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 */ |
106 | const char *audit_tree_path(struct audit_tree *tree) |
107 | { |
108 | return tree->pathname; |
109 | } |
110 | |
111 | static 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 | |
122 | void audit_put_chunk(struct audit_chunk *chunk) |
123 | { |
124 | if (atomic_long_dec_and_test(&chunk->refs)) |
125 | free_chunk(chunk); |
126 | } |
127 | |
128 | static 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 | |
134 | static 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 | |
140 | static 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 | |
164 | enum {HASH_SIZE = 128}; |
165 | static struct list_head chunk_hash_heads[HASH_SIZE]; |
166 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock); |
167 | |
168 | /* Function to return search key in our hash from inode. */ |
169 | static unsigned long inode_to_key(const struct inode *inode) |
170 | { |
171 | /* Use address pointed to by connector->obj as the key */ |
172 | return (unsigned long)&inode->i_fsnotify_marks; |
173 | } |
174 | |
175 | /* |
176 | * Function to return search key in our hash from chunk. Key 0 is special and |
177 | * should never be present in the hash. |
178 | */ |
179 | static unsigned long chunk_to_key(struct audit_chunk *chunk) |
180 | { |
181 | /* |
182 | * We have a reference to the mark so it should be attached to a |
183 | * connector. |
184 | */ |
185 | if (WARN_ON_ONCE(!chunk->mark.connector)) |
186 | return 0; |
187 | return (unsigned long)chunk->mark.connector->obj; |
188 | } |
189 | |
190 | static inline struct list_head *chunk_hash(unsigned long key) |
191 | { |
192 | unsigned long n = key / L1_CACHE_BYTES; |
193 | return chunk_hash_heads + n % HASH_SIZE; |
194 | } |
195 | |
196 | /* hash_lock & entry->lock is held by caller */ |
197 | static void insert_hash(struct audit_chunk *chunk) |
198 | { |
199 | unsigned long key = chunk_to_key(chunk); |
200 | struct list_head *list; |
201 | |
202 | if (!(chunk->mark.flags & FSNOTIFY_MARK_FLAG_ATTACHED)) |
203 | return; |
204 | list = chunk_hash(key); |
205 | list_add_rcu(&chunk->hash, list); |
206 | } |
207 | |
208 | /* called under rcu_read_lock */ |
209 | struct audit_chunk *audit_tree_lookup(const struct inode *inode) |
210 | { |
211 | unsigned long key = inode_to_key(inode); |
212 | struct list_head *list = chunk_hash(key); |
213 | struct audit_chunk *p; |
214 | |
215 | list_for_each_entry_rcu(p, list, hash) { |
216 | if (chunk_to_key(p) == key) { |
217 | atomic_long_inc(&p->refs); |
218 | return p; |
219 | } |
220 | } |
221 | return NULL; |
222 | } |
223 | |
224 | bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree) |
225 | { |
226 | int n; |
227 | for (n = 0; n < chunk->count; n++) |
228 | if (chunk->owners[n].owner == tree) |
229 | return true; |
230 | return false; |
231 | } |
232 | |
233 | /* tagging and untagging inodes with trees */ |
234 | |
235 | static struct audit_chunk *find_chunk(struct node *p) |
236 | { |
237 | int index = p->index & ~(1U<<31); |
238 | p -= index; |
239 | return container_of(p, struct audit_chunk, owners[0]); |
240 | } |
241 | |
242 | static void untag_chunk(struct node *p) |
243 | { |
244 | struct audit_chunk *chunk = find_chunk(p); |
245 | struct fsnotify_mark *entry = &chunk->mark; |
246 | struct audit_chunk *new = NULL; |
247 | struct audit_tree *owner; |
248 | int size = chunk->count - 1; |
249 | int i, j; |
250 | |
251 | fsnotify_get_mark(entry); |
252 | |
253 | spin_unlock(&hash_lock); |
254 | |
255 | if (size) |
256 | new = alloc_chunk(size); |
257 | |
258 | mutex_lock(&entry->group->mark_mutex); |
259 | spin_lock(&entry->lock); |
260 | /* |
261 | * mark_mutex protects mark from getting detached and thus also from |
262 | * mark->connector->obj getting NULL. |
263 | */ |
264 | if (chunk->dead || !(entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) { |
265 | spin_unlock(&entry->lock); |
266 | mutex_unlock(&entry->group->mark_mutex); |
267 | if (new) |
268 | fsnotify_put_mark(&new->mark); |
269 | goto out; |
270 | } |
271 | |
272 | owner = p->owner; |
273 | |
274 | if (!size) { |
275 | chunk->dead = 1; |
276 | spin_lock(&hash_lock); |
277 | list_del_init(&chunk->trees); |
278 | if (owner->root == chunk) |
279 | owner->root = NULL; |
280 | list_del_init(&p->list); |
281 | list_del_rcu(&chunk->hash); |
282 | spin_unlock(&hash_lock); |
283 | spin_unlock(&entry->lock); |
284 | mutex_unlock(&entry->group->mark_mutex); |
285 | fsnotify_destroy_mark(entry, audit_tree_group); |
286 | goto out; |
287 | } |
288 | |
289 | if (!new) |
290 | goto Fallback; |
291 | |
292 | if (fsnotify_add_mark_locked(&new->mark, entry->connector->obj, |
293 | FSNOTIFY_OBJ_TYPE_INODE, 1)) { |
294 | fsnotify_put_mark(&new->mark); |
295 | goto Fallback; |
296 | } |
297 | |
298 | chunk->dead = 1; |
299 | spin_lock(&hash_lock); |
300 | list_replace_init(&chunk->trees, &new->trees); |
301 | if (owner->root == chunk) { |
302 | list_del_init(&owner->same_root); |
303 | owner->root = NULL; |
304 | } |
305 | |
306 | for (i = j = 0; j <= size; i++, j++) { |
307 | struct audit_tree *s; |
308 | if (&chunk->owners[j] == p) { |
309 | list_del_init(&p->list); |
310 | i--; |
311 | continue; |
312 | } |
313 | s = chunk->owners[j].owner; |
314 | new->owners[i].owner = s; |
315 | new->owners[i].index = chunk->owners[j].index - j + i; |
316 | if (!s) /* result of earlier fallback */ |
317 | continue; |
318 | get_tree(s); |
319 | list_replace_init(&chunk->owners[j].list, &new->owners[i].list); |
320 | } |
321 | |
322 | list_replace_rcu(&chunk->hash, &new->hash); |
323 | list_for_each_entry(owner, &new->trees, same_root) |
324 | owner->root = new; |
325 | spin_unlock(&hash_lock); |
326 | spin_unlock(&entry->lock); |
327 | mutex_unlock(&entry->group->mark_mutex); |
328 | fsnotify_destroy_mark(entry, audit_tree_group); |
329 | fsnotify_put_mark(&new->mark); /* drop initial reference */ |
330 | goto out; |
331 | |
332 | Fallback: |
333 | // do the best we can |
334 | spin_lock(&hash_lock); |
335 | if (owner->root == chunk) { |
336 | list_del_init(&owner->same_root); |
337 | owner->root = NULL; |
338 | } |
339 | list_del_init(&p->list); |
340 | p->owner = NULL; |
341 | put_tree(owner); |
342 | spin_unlock(&hash_lock); |
343 | spin_unlock(&entry->lock); |
344 | mutex_unlock(&entry->group->mark_mutex); |
345 | out: |
346 | fsnotify_put_mark(entry); |
347 | spin_lock(&hash_lock); |
348 | } |
349 | |
350 | static int create_chunk(struct inode *inode, struct audit_tree *tree) |
351 | { |
352 | struct fsnotify_mark *entry; |
353 | struct audit_chunk *chunk = alloc_chunk(1); |
354 | if (!chunk) |
355 | return -ENOMEM; |
356 | |
357 | entry = &chunk->mark; |
358 | if (fsnotify_add_inode_mark(entry, inode, 0)) { |
359 | fsnotify_put_mark(entry); |
360 | return -ENOSPC; |
361 | } |
362 | |
363 | spin_lock(&entry->lock); |
364 | spin_lock(&hash_lock); |
365 | if (tree->goner) { |
366 | spin_unlock(&hash_lock); |
367 | chunk->dead = 1; |
368 | spin_unlock(&entry->lock); |
369 | fsnotify_destroy_mark(entry, audit_tree_group); |
370 | fsnotify_put_mark(entry); |
371 | return 0; |
372 | } |
373 | chunk->owners[0].index = (1U << 31); |
374 | chunk->owners[0].owner = tree; |
375 | get_tree(tree); |
376 | list_add(&chunk->owners[0].list, &tree->chunks); |
377 | if (!tree->root) { |
378 | tree->root = chunk; |
379 | list_add(&tree->same_root, &chunk->trees); |
380 | } |
381 | insert_hash(chunk); |
382 | spin_unlock(&hash_lock); |
383 | spin_unlock(&entry->lock); |
384 | fsnotify_put_mark(entry); /* drop initial reference */ |
385 | return 0; |
386 | } |
387 | |
388 | /* the first tagged inode becomes root of tree */ |
389 | static int tag_chunk(struct inode *inode, struct audit_tree *tree) |
390 | { |
391 | struct fsnotify_mark *old_entry, *chunk_entry; |
392 | struct audit_tree *owner; |
393 | struct audit_chunk *chunk, *old; |
394 | struct node *p; |
395 | int n; |
396 | |
397 | old_entry = fsnotify_find_mark(&inode->i_fsnotify_marks, |
398 | audit_tree_group); |
399 | if (!old_entry) |
400 | return create_chunk(inode, tree); |
401 | |
402 | old = container_of(old_entry, struct audit_chunk, mark); |
403 | |
404 | /* are we already there? */ |
405 | spin_lock(&hash_lock); |
406 | for (n = 0; n < old->count; n++) { |
407 | if (old->owners[n].owner == tree) { |
408 | spin_unlock(&hash_lock); |
409 | fsnotify_put_mark(old_entry); |
410 | return 0; |
411 | } |
412 | } |
413 | spin_unlock(&hash_lock); |
414 | |
415 | chunk = alloc_chunk(old->count + 1); |
416 | if (!chunk) { |
417 | fsnotify_put_mark(old_entry); |
418 | return -ENOMEM; |
419 | } |
420 | |
421 | chunk_entry = &chunk->mark; |
422 | |
423 | mutex_lock(&old_entry->group->mark_mutex); |
424 | spin_lock(&old_entry->lock); |
425 | /* |
426 | * mark_mutex protects mark from getting detached and thus also from |
427 | * mark->connector->obj getting NULL. |
428 | */ |
429 | if (!(old_entry->flags & FSNOTIFY_MARK_FLAG_ATTACHED)) { |
430 | /* old_entry is being shot, lets just lie */ |
431 | spin_unlock(&old_entry->lock); |
432 | mutex_unlock(&old_entry->group->mark_mutex); |
433 | fsnotify_put_mark(old_entry); |
434 | fsnotify_put_mark(&chunk->mark); |
435 | return -ENOENT; |
436 | } |
437 | |
438 | if (fsnotify_add_mark_locked(chunk_entry, old_entry->connector->obj, |
439 | FSNOTIFY_OBJ_TYPE_INODE, 1)) { |
440 | spin_unlock(&old_entry->lock); |
441 | mutex_unlock(&old_entry->group->mark_mutex); |
442 | fsnotify_put_mark(chunk_entry); |
443 | fsnotify_put_mark(old_entry); |
444 | return -ENOSPC; |
445 | } |
446 | |
447 | /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */ |
448 | spin_lock(&chunk_entry->lock); |
449 | spin_lock(&hash_lock); |
450 | |
451 | /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */ |
452 | if (tree->goner) { |
453 | spin_unlock(&hash_lock); |
454 | chunk->dead = 1; |
455 | spin_unlock(&chunk_entry->lock); |
456 | spin_unlock(&old_entry->lock); |
457 | mutex_unlock(&old_entry->group->mark_mutex); |
458 | |
459 | fsnotify_destroy_mark(chunk_entry, audit_tree_group); |
460 | |
461 | fsnotify_put_mark(chunk_entry); |
462 | fsnotify_put_mark(old_entry); |
463 | return 0; |
464 | } |
465 | list_replace_init(&old->trees, &chunk->trees); |
466 | for (n = 0, p = chunk->owners; n < old->count; n++, p++) { |
467 | struct audit_tree *s = old->owners[n].owner; |
468 | p->owner = s; |
469 | p->index = old->owners[n].index; |
470 | if (!s) /* result of fallback in untag */ |
471 | continue; |
472 | get_tree(s); |
473 | list_replace_init(&old->owners[n].list, &p->list); |
474 | } |
475 | p->index = (chunk->count - 1) | (1U<<31); |
476 | p->owner = tree; |
477 | get_tree(tree); |
478 | list_add(&p->list, &tree->chunks); |
479 | list_replace_rcu(&old->hash, &chunk->hash); |
480 | list_for_each_entry(owner, &chunk->trees, same_root) |
481 | owner->root = chunk; |
482 | old->dead = 1; |
483 | if (!tree->root) { |
484 | tree->root = chunk; |
485 | list_add(&tree->same_root, &chunk->trees); |
486 | } |
487 | spin_unlock(&hash_lock); |
488 | spin_unlock(&chunk_entry->lock); |
489 | spin_unlock(&old_entry->lock); |
490 | mutex_unlock(&old_entry->group->mark_mutex); |
491 | fsnotify_destroy_mark(old_entry, audit_tree_group); |
492 | fsnotify_put_mark(chunk_entry); /* drop initial reference */ |
493 | fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */ |
494 | return 0; |
495 | } |
496 | |
497 | static void audit_tree_log_remove_rule(struct audit_krule *rule) |
498 | { |
499 | struct audit_buffer *ab; |
500 | |
501 | if (!audit_enabled) |
502 | return; |
503 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); |
504 | if (unlikely(!ab)) |
505 | return; |
506 | audit_log_format(ab, "op=remove_rule" ); |
507 | audit_log_format(ab, " dir=" ); |
508 | audit_log_untrustedstring(ab, rule->tree->pathname); |
509 | audit_log_key(ab, rule->filterkey); |
510 | audit_log_format(ab, " list=%d res=1" , rule->listnr); |
511 | audit_log_end(ab); |
512 | } |
513 | |
514 | static void kill_rules(struct audit_tree *tree) |
515 | { |
516 | struct audit_krule *rule, *next; |
517 | struct audit_entry *entry; |
518 | |
519 | list_for_each_entry_safe(rule, next, &tree->rules, rlist) { |
520 | entry = container_of(rule, struct audit_entry, rule); |
521 | |
522 | list_del_init(&rule->rlist); |
523 | if (rule->tree) { |
524 | /* not a half-baked one */ |
525 | audit_tree_log_remove_rule(rule); |
526 | if (entry->rule.exe) |
527 | audit_remove_mark(entry->rule.exe); |
528 | rule->tree = NULL; |
529 | list_del_rcu(&entry->list); |
530 | list_del(&entry->rule.list); |
531 | call_rcu(&entry->rcu, audit_free_rule_rcu); |
532 | } |
533 | } |
534 | } |
535 | |
536 | /* |
537 | * finish killing struct audit_tree |
538 | */ |
539 | static void prune_one(struct audit_tree *victim) |
540 | { |
541 | spin_lock(&hash_lock); |
542 | while (!list_empty(&victim->chunks)) { |
543 | struct node *p; |
544 | |
545 | p = list_entry(victim->chunks.next, struct node, list); |
546 | |
547 | untag_chunk(p); |
548 | } |
549 | spin_unlock(&hash_lock); |
550 | put_tree(victim); |
551 | } |
552 | |
553 | /* trim the uncommitted chunks from tree */ |
554 | |
555 | static void trim_marked(struct audit_tree *tree) |
556 | { |
557 | struct list_head *p, *q; |
558 | spin_lock(&hash_lock); |
559 | if (tree->goner) { |
560 | spin_unlock(&hash_lock); |
561 | return; |
562 | } |
563 | /* reorder */ |
564 | for (p = tree->chunks.next; p != &tree->chunks; p = q) { |
565 | struct node *node = list_entry(p, struct node, list); |
566 | q = p->next; |
567 | if (node->index & (1U<<31)) { |
568 | list_del_init(p); |
569 | list_add(p, &tree->chunks); |
570 | } |
571 | } |
572 | |
573 | while (!list_empty(&tree->chunks)) { |
574 | struct node *node; |
575 | |
576 | node = list_entry(tree->chunks.next, struct node, list); |
577 | |
578 | /* have we run out of marked? */ |
579 | if (!(node->index & (1U<<31))) |
580 | break; |
581 | |
582 | untag_chunk(node); |
583 | } |
584 | if (!tree->root && !tree->goner) { |
585 | tree->goner = 1; |
586 | spin_unlock(&hash_lock); |
587 | mutex_lock(&audit_filter_mutex); |
588 | kill_rules(tree); |
589 | list_del_init(&tree->list); |
590 | mutex_unlock(&audit_filter_mutex); |
591 | prune_one(tree); |
592 | } else { |
593 | spin_unlock(&hash_lock); |
594 | } |
595 | } |
596 | |
597 | static void audit_schedule_prune(void); |
598 | |
599 | /* called with audit_filter_mutex */ |
600 | int audit_remove_tree_rule(struct audit_krule *rule) |
601 | { |
602 | struct audit_tree *tree; |
603 | tree = rule->tree; |
604 | if (tree) { |
605 | spin_lock(&hash_lock); |
606 | list_del_init(&rule->rlist); |
607 | if (list_empty(&tree->rules) && !tree->goner) { |
608 | tree->root = NULL; |
609 | list_del_init(&tree->same_root); |
610 | tree->goner = 1; |
611 | list_move(&tree->list, &prune_list); |
612 | rule->tree = NULL; |
613 | spin_unlock(&hash_lock); |
614 | audit_schedule_prune(); |
615 | return 1; |
616 | } |
617 | rule->tree = NULL; |
618 | spin_unlock(&hash_lock); |
619 | return 1; |
620 | } |
621 | return 0; |
622 | } |
623 | |
624 | static int compare_root(struct vfsmount *mnt, void *arg) |
625 | { |
626 | return inode_to_key(d_backing_inode(mnt->mnt_root)) == |
627 | (unsigned long)arg; |
628 | } |
629 | |
630 | void audit_trim_trees(void) |
631 | { |
632 | struct list_head cursor; |
633 | |
634 | mutex_lock(&audit_filter_mutex); |
635 | list_add(&cursor, &tree_list); |
636 | while (cursor.next != &tree_list) { |
637 | struct audit_tree *tree; |
638 | struct path path; |
639 | struct vfsmount *root_mnt; |
640 | struct node *node; |
641 | int err; |
642 | |
643 | tree = container_of(cursor.next, struct audit_tree, list); |
644 | get_tree(tree); |
645 | list_del(&cursor); |
646 | list_add(&cursor, &tree->list); |
647 | mutex_unlock(&audit_filter_mutex); |
648 | |
649 | err = kern_path(tree->pathname, 0, &path); |
650 | if (err) |
651 | goto skip_it; |
652 | |
653 | root_mnt = collect_mounts(&path); |
654 | path_put(&path); |
655 | if (IS_ERR(root_mnt)) |
656 | goto skip_it; |
657 | |
658 | spin_lock(&hash_lock); |
659 | list_for_each_entry(node, &tree->chunks, list) { |
660 | struct audit_chunk *chunk = find_chunk(node); |
661 | /* this could be NULL if the watch is dying else where... */ |
662 | node->index |= 1U<<31; |
663 | if (iterate_mounts(compare_root, |
664 | (void *)chunk_to_key(chunk), |
665 | root_mnt)) |
666 | node->index &= ~(1U<<31); |
667 | } |
668 | spin_unlock(&hash_lock); |
669 | trim_marked(tree); |
670 | drop_collected_mounts(root_mnt); |
671 | skip_it: |
672 | put_tree(tree); |
673 | mutex_lock(&audit_filter_mutex); |
674 | } |
675 | list_del(&cursor); |
676 | mutex_unlock(&audit_filter_mutex); |
677 | } |
678 | |
679 | int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op) |
680 | { |
681 | |
682 | if (pathname[0] != '/' || |
683 | rule->listnr != AUDIT_FILTER_EXIT || |
684 | op != Audit_equal || |
685 | rule->inode_f || rule->watch || rule->tree) |
686 | return -EINVAL; |
687 | rule->tree = alloc_tree(pathname); |
688 | if (!rule->tree) |
689 | return -ENOMEM; |
690 | return 0; |
691 | } |
692 | |
693 | void audit_put_tree(struct audit_tree *tree) |
694 | { |
695 | put_tree(tree); |
696 | } |
697 | |
698 | static int tag_mount(struct vfsmount *mnt, void *arg) |
699 | { |
700 | return tag_chunk(d_backing_inode(mnt->mnt_root), arg); |
701 | } |
702 | |
703 | /* |
704 | * That gets run when evict_chunk() ends up needing to kill audit_tree. |
705 | * Runs from a separate thread. |
706 | */ |
707 | static int prune_tree_thread(void *unused) |
708 | { |
709 | for (;;) { |
710 | if (list_empty(&prune_list)) { |
711 | set_current_state(TASK_INTERRUPTIBLE); |
712 | schedule(); |
713 | } |
714 | |
715 | audit_ctl_lock(); |
716 | mutex_lock(&audit_filter_mutex); |
717 | |
718 | while (!list_empty(&prune_list)) { |
719 | struct audit_tree *victim; |
720 | |
721 | victim = list_entry(prune_list.next, |
722 | struct audit_tree, list); |
723 | list_del_init(&victim->list); |
724 | |
725 | mutex_unlock(&audit_filter_mutex); |
726 | |
727 | prune_one(victim); |
728 | |
729 | mutex_lock(&audit_filter_mutex); |
730 | } |
731 | |
732 | mutex_unlock(&audit_filter_mutex); |
733 | audit_ctl_unlock(); |
734 | } |
735 | return 0; |
736 | } |
737 | |
738 | static int audit_launch_prune(void) |
739 | { |
740 | if (prune_thread) |
741 | return 0; |
742 | prune_thread = kthread_run(prune_tree_thread, NULL, |
743 | "audit_prune_tree" ); |
744 | if (IS_ERR(prune_thread)) { |
745 | pr_err("cannot start thread audit_prune_tree" ); |
746 | prune_thread = NULL; |
747 | return -ENOMEM; |
748 | } |
749 | return 0; |
750 | } |
751 | |
752 | /* called with audit_filter_mutex */ |
753 | int audit_add_tree_rule(struct audit_krule *rule) |
754 | { |
755 | struct audit_tree *seed = rule->tree, *tree; |
756 | struct path path; |
757 | struct vfsmount *mnt; |
758 | int err; |
759 | |
760 | rule->tree = NULL; |
761 | list_for_each_entry(tree, &tree_list, list) { |
762 | if (!strcmp(seed->pathname, tree->pathname)) { |
763 | put_tree(seed); |
764 | rule->tree = tree; |
765 | list_add(&rule->rlist, &tree->rules); |
766 | return 0; |
767 | } |
768 | } |
769 | tree = seed; |
770 | list_add(&tree->list, &tree_list); |
771 | list_add(&rule->rlist, &tree->rules); |
772 | /* do not set rule->tree yet */ |
773 | mutex_unlock(&audit_filter_mutex); |
774 | |
775 | if (unlikely(!prune_thread)) { |
776 | err = audit_launch_prune(); |
777 | if (err) |
778 | goto Err; |
779 | } |
780 | |
781 | err = kern_path(tree->pathname, 0, &path); |
782 | if (err) |
783 | goto Err; |
784 | mnt = collect_mounts(&path); |
785 | path_put(&path); |
786 | if (IS_ERR(mnt)) { |
787 | err = PTR_ERR(mnt); |
788 | goto Err; |
789 | } |
790 | |
791 | get_tree(tree); |
792 | err = iterate_mounts(tag_mount, tree, mnt); |
793 | drop_collected_mounts(mnt); |
794 | |
795 | if (!err) { |
796 | struct node *node; |
797 | spin_lock(&hash_lock); |
798 | list_for_each_entry(node, &tree->chunks, list) |
799 | node->index &= ~(1U<<31); |
800 | spin_unlock(&hash_lock); |
801 | } else { |
802 | trim_marked(tree); |
803 | goto Err; |
804 | } |
805 | |
806 | mutex_lock(&audit_filter_mutex); |
807 | if (list_empty(&rule->rlist)) { |
808 | put_tree(tree); |
809 | return -ENOENT; |
810 | } |
811 | rule->tree = tree; |
812 | put_tree(tree); |
813 | |
814 | return 0; |
815 | Err: |
816 | mutex_lock(&audit_filter_mutex); |
817 | list_del_init(&tree->list); |
818 | list_del_init(&tree->rules); |
819 | put_tree(tree); |
820 | return err; |
821 | } |
822 | |
823 | int audit_tag_tree(char *old, char *new) |
824 | { |
825 | struct list_head cursor, barrier; |
826 | int failed = 0; |
827 | struct path path1, path2; |
828 | struct vfsmount *tagged; |
829 | int err; |
830 | |
831 | err = kern_path(new, 0, &path2); |
832 | if (err) |
833 | return err; |
834 | tagged = collect_mounts(&path2); |
835 | path_put(&path2); |
836 | if (IS_ERR(tagged)) |
837 | return PTR_ERR(tagged); |
838 | |
839 | err = kern_path(old, 0, &path1); |
840 | if (err) { |
841 | drop_collected_mounts(tagged); |
842 | return err; |
843 | } |
844 | |
845 | mutex_lock(&audit_filter_mutex); |
846 | list_add(&barrier, &tree_list); |
847 | list_add(&cursor, &barrier); |
848 | |
849 | while (cursor.next != &tree_list) { |
850 | struct audit_tree *tree; |
851 | int good_one = 0; |
852 | |
853 | tree = container_of(cursor.next, struct audit_tree, list); |
854 | get_tree(tree); |
855 | list_del(&cursor); |
856 | list_add(&cursor, &tree->list); |
857 | mutex_unlock(&audit_filter_mutex); |
858 | |
859 | err = kern_path(tree->pathname, 0, &path2); |
860 | if (!err) { |
861 | good_one = path_is_under(&path1, &path2); |
862 | path_put(&path2); |
863 | } |
864 | |
865 | if (!good_one) { |
866 | put_tree(tree); |
867 | mutex_lock(&audit_filter_mutex); |
868 | continue; |
869 | } |
870 | |
871 | failed = iterate_mounts(tag_mount, tree, tagged); |
872 | if (failed) { |
873 | put_tree(tree); |
874 | mutex_lock(&audit_filter_mutex); |
875 | break; |
876 | } |
877 | |
878 | mutex_lock(&audit_filter_mutex); |
879 | spin_lock(&hash_lock); |
880 | if (!tree->goner) { |
881 | list_del(&tree->list); |
882 | list_add(&tree->list, &tree_list); |
883 | } |
884 | spin_unlock(&hash_lock); |
885 | put_tree(tree); |
886 | } |
887 | |
888 | while (barrier.prev != &tree_list) { |
889 | struct audit_tree *tree; |
890 | |
891 | tree = container_of(barrier.prev, struct audit_tree, list); |
892 | get_tree(tree); |
893 | list_del(&tree->list); |
894 | list_add(&tree->list, &barrier); |
895 | mutex_unlock(&audit_filter_mutex); |
896 | |
897 | if (!failed) { |
898 | struct node *node; |
899 | spin_lock(&hash_lock); |
900 | list_for_each_entry(node, &tree->chunks, list) |
901 | node->index &= ~(1U<<31); |
902 | spin_unlock(&hash_lock); |
903 | } else { |
904 | trim_marked(tree); |
905 | } |
906 | |
907 | put_tree(tree); |
908 | mutex_lock(&audit_filter_mutex); |
909 | } |
910 | list_del(&barrier); |
911 | list_del(&cursor); |
912 | mutex_unlock(&audit_filter_mutex); |
913 | path_put(&path1); |
914 | drop_collected_mounts(tagged); |
915 | return failed; |
916 | } |
917 | |
918 | |
919 | static void audit_schedule_prune(void) |
920 | { |
921 | wake_up_process(prune_thread); |
922 | } |
923 | |
924 | /* |
925 | * ... and that one is done if evict_chunk() decides to delay until the end |
926 | * of syscall. Runs synchronously. |
927 | */ |
928 | void audit_kill_trees(struct list_head *list) |
929 | { |
930 | audit_ctl_lock(); |
931 | mutex_lock(&audit_filter_mutex); |
932 | |
933 | while (!list_empty(list)) { |
934 | struct audit_tree *victim; |
935 | |
936 | victim = list_entry(list->next, struct audit_tree, list); |
937 | kill_rules(victim); |
938 | list_del_init(&victim->list); |
939 | |
940 | mutex_unlock(&audit_filter_mutex); |
941 | |
942 | prune_one(victim); |
943 | |
944 | mutex_lock(&audit_filter_mutex); |
945 | } |
946 | |
947 | mutex_unlock(&audit_filter_mutex); |
948 | audit_ctl_unlock(); |
949 | } |
950 | |
951 | /* |
952 | * Here comes the stuff asynchronous to auditctl operations |
953 | */ |
954 | |
955 | static void evict_chunk(struct audit_chunk *chunk) |
956 | { |
957 | struct audit_tree *owner; |
958 | struct list_head *postponed = audit_killed_trees(); |
959 | int need_prune = 0; |
960 | int n; |
961 | |
962 | if (chunk->dead) |
963 | return; |
964 | |
965 | chunk->dead = 1; |
966 | mutex_lock(&audit_filter_mutex); |
967 | spin_lock(&hash_lock); |
968 | while (!list_empty(&chunk->trees)) { |
969 | owner = list_entry(chunk->trees.next, |
970 | struct audit_tree, same_root); |
971 | owner->goner = 1; |
972 | owner->root = NULL; |
973 | list_del_init(&owner->same_root); |
974 | spin_unlock(&hash_lock); |
975 | if (!postponed) { |
976 | kill_rules(owner); |
977 | list_move(&owner->list, &prune_list); |
978 | need_prune = 1; |
979 | } else { |
980 | list_move(&owner->list, postponed); |
981 | } |
982 | spin_lock(&hash_lock); |
983 | } |
984 | list_del_rcu(&chunk->hash); |
985 | for (n = 0; n < chunk->count; n++) |
986 | list_del_init(&chunk->owners[n].list); |
987 | spin_unlock(&hash_lock); |
988 | mutex_unlock(&audit_filter_mutex); |
989 | if (need_prune) |
990 | audit_schedule_prune(); |
991 | } |
992 | |
993 | static int audit_tree_handle_event(struct fsnotify_group *group, |
994 | struct inode *to_tell, |
995 | u32 mask, const void *data, int data_type, |
996 | const unsigned char *file_name, u32 cookie, |
997 | struct fsnotify_iter_info *iter_info) |
998 | { |
999 | return 0; |
1000 | } |
1001 | |
1002 | static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group) |
1003 | { |
1004 | struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark); |
1005 | |
1006 | evict_chunk(chunk); |
1007 | |
1008 | /* |
1009 | * We are guaranteed to have at least one reference to the mark from |
1010 | * either the inode or the caller of fsnotify_destroy_mark(). |
1011 | */ |
1012 | BUG_ON(refcount_read(&entry->refcnt) < 1); |
1013 | } |
1014 | |
1015 | static const struct fsnotify_ops audit_tree_ops = { |
1016 | .handle_event = audit_tree_handle_event, |
1017 | .freeing_mark = audit_tree_freeing_mark, |
1018 | .free_mark = audit_tree_destroy_watch, |
1019 | }; |
1020 | |
1021 | static int __init audit_tree_init(void) |
1022 | { |
1023 | int i; |
1024 | |
1025 | audit_tree_group = fsnotify_alloc_group(&audit_tree_ops); |
1026 | if (IS_ERR(audit_tree_group)) |
1027 | audit_panic("cannot initialize fsnotify group for rectree watches" ); |
1028 | |
1029 | for (i = 0; i < HASH_SIZE; i++) |
1030 | INIT_LIST_HEAD(&chunk_hash_heads[i]); |
1031 | |
1032 | return 0; |
1033 | } |
1034 | __initcall(audit_tree_init); |
1035 | |