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 | unsigned long key; |
28 | struct fsnotify_mark *mark; |
29 | struct list_head trees; /* with root here */ |
30 | int count; |
31 | atomic_long_t refs; |
32 | struct rcu_head head; |
33 | struct audit_node { |
34 | struct list_head list; |
35 | struct audit_tree *owner; |
36 | unsigned index; /* index; upper bit indicates 'will prune' */ |
37 | } owners[] __counted_by(count); |
38 | }; |
39 | |
40 | struct audit_tree_mark { |
41 | struct fsnotify_mark mark; |
42 | struct audit_chunk *chunk; |
43 | }; |
44 | |
45 | static LIST_HEAD(tree_list); |
46 | static LIST_HEAD(prune_list); |
47 | static struct task_struct *prune_thread; |
48 | |
49 | /* |
50 | * One struct chunk is attached to each inode of interest through |
51 | * audit_tree_mark (fsnotify mark). We replace struct chunk on tagging / |
52 | * untagging, the mark is stable as long as there is chunk attached. The |
53 | * association between mark and chunk is protected by hash_lock and |
54 | * audit_tree_group->mark_mutex. Thus as long as we hold |
55 | * audit_tree_group->mark_mutex and check that the mark is alive by |
56 | * FSNOTIFY_MARK_FLAG_ATTACHED flag check, we are sure the mark points to |
57 | * the current chunk. |
58 | * |
59 | * Rules have pointer to struct audit_tree. |
60 | * Rules have struct list_head rlist forming a list of rules over |
61 | * the same tree. |
62 | * References to struct chunk are collected at audit_inode{,_child}() |
63 | * time and used in AUDIT_TREE rule matching. |
64 | * These references are dropped at the same time we are calling |
65 | * audit_free_names(), etc. |
66 | * |
67 | * Cyclic lists galore: |
68 | * tree.chunks anchors chunk.owners[].list hash_lock |
69 | * tree.rules anchors rule.rlist audit_filter_mutex |
70 | * chunk.trees anchors tree.same_root hash_lock |
71 | * chunk.hash is a hash with middle bits of watch.inode as |
72 | * a hash function. RCU, hash_lock |
73 | * |
74 | * tree is refcounted; one reference for "some rules on rules_list refer to |
75 | * it", one for each chunk with pointer to it. |
76 | * |
77 | * chunk is refcounted by embedded .refs. Mark associated with the chunk holds |
78 | * one chunk reference. This reference is dropped either when a mark is going |
79 | * to be freed (corresponding inode goes away) or when chunk attached to the |
80 | * mark gets replaced. This reference must be dropped using |
81 | * audit_mark_put_chunk() to make sure the reference is dropped only after RCU |
82 | * grace period as it protects RCU readers of the hash table. |
83 | * |
84 | * node.index allows to get from node.list to containing chunk. |
85 | * MSB of that sucker is stolen to mark taggings that we might have to |
86 | * revert - several operations have very unpleasant cleanup logics and |
87 | * that makes a difference. Some. |
88 | */ |
89 | |
90 | static struct fsnotify_group *audit_tree_group __ro_after_init; |
91 | static struct kmem_cache *audit_tree_mark_cachep __ro_after_init; |
92 | |
93 | static struct audit_tree *alloc_tree(const char *s) |
94 | { |
95 | struct audit_tree *tree; |
96 | |
97 | tree = kmalloc(struct_size(tree, pathname, strlen(s) + 1), GFP_KERNEL); |
98 | if (tree) { |
99 | refcount_set(r: &tree->count, n: 1); |
100 | tree->goner = 0; |
101 | INIT_LIST_HEAD(list: &tree->chunks); |
102 | INIT_LIST_HEAD(list: &tree->rules); |
103 | INIT_LIST_HEAD(list: &tree->list); |
104 | INIT_LIST_HEAD(list: &tree->same_root); |
105 | tree->root = NULL; |
106 | strcpy(p: tree->pathname, q: s); |
107 | } |
108 | return tree; |
109 | } |
110 | |
111 | static inline void get_tree(struct audit_tree *tree) |
112 | { |
113 | refcount_inc(r: &tree->count); |
114 | } |
115 | |
116 | static inline void put_tree(struct audit_tree *tree) |
117 | { |
118 | if (refcount_dec_and_test(r: &tree->count)) |
119 | kfree_rcu(tree, head); |
120 | } |
121 | |
122 | /* to avoid bringing the entire thing in audit.h */ |
123 | const char *audit_tree_path(struct audit_tree *tree) |
124 | { |
125 | return tree->pathname; |
126 | } |
127 | |
128 | static void free_chunk(struct audit_chunk *chunk) |
129 | { |
130 | int i; |
131 | |
132 | for (i = 0; i < chunk->count; i++) { |
133 | if (chunk->owners[i].owner) |
134 | put_tree(tree: chunk->owners[i].owner); |
135 | } |
136 | kfree(objp: chunk); |
137 | } |
138 | |
139 | void audit_put_chunk(struct audit_chunk *chunk) |
140 | { |
141 | if (atomic_long_dec_and_test(v: &chunk->refs)) |
142 | free_chunk(chunk); |
143 | } |
144 | |
145 | static void __put_chunk(struct rcu_head *rcu) |
146 | { |
147 | struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head); |
148 | audit_put_chunk(chunk); |
149 | } |
150 | |
151 | /* |
152 | * Drop reference to the chunk that was held by the mark. This is the reference |
153 | * that gets dropped after we've removed the chunk from the hash table and we |
154 | * use it to make sure chunk cannot be freed before RCU grace period expires. |
155 | */ |
156 | static void audit_mark_put_chunk(struct audit_chunk *chunk) |
157 | { |
158 | call_rcu(head: &chunk->head, func: __put_chunk); |
159 | } |
160 | |
161 | static inline struct audit_tree_mark *audit_mark(struct fsnotify_mark *mark) |
162 | { |
163 | return container_of(mark, struct audit_tree_mark, mark); |
164 | } |
165 | |
166 | static struct audit_chunk *mark_chunk(struct fsnotify_mark *mark) |
167 | { |
168 | return audit_mark(mark)->chunk; |
169 | } |
170 | |
171 | static void audit_tree_destroy_watch(struct fsnotify_mark *mark) |
172 | { |
173 | kmem_cache_free(s: audit_tree_mark_cachep, objp: audit_mark(mark)); |
174 | } |
175 | |
176 | static struct fsnotify_mark *alloc_mark(void) |
177 | { |
178 | struct audit_tree_mark *amark; |
179 | |
180 | amark = kmem_cache_zalloc(k: audit_tree_mark_cachep, GFP_KERNEL); |
181 | if (!amark) |
182 | return NULL; |
183 | fsnotify_init_mark(mark: &amark->mark, group: audit_tree_group); |
184 | amark->mark.mask = FS_IN_IGNORED; |
185 | return &amark->mark; |
186 | } |
187 | |
188 | static struct audit_chunk *alloc_chunk(int count) |
189 | { |
190 | struct audit_chunk *chunk; |
191 | int i; |
192 | |
193 | chunk = kzalloc(struct_size(chunk, owners, count), GFP_KERNEL); |
194 | if (!chunk) |
195 | return NULL; |
196 | |
197 | INIT_LIST_HEAD(list: &chunk->hash); |
198 | INIT_LIST_HEAD(list: &chunk->trees); |
199 | chunk->count = count; |
200 | atomic_long_set(v: &chunk->refs, i: 1); |
201 | for (i = 0; i < count; i++) { |
202 | INIT_LIST_HEAD(list: &chunk->owners[i].list); |
203 | chunk->owners[i].index = i; |
204 | } |
205 | return chunk; |
206 | } |
207 | |
208 | enum {HASH_SIZE = 128}; |
209 | static struct list_head chunk_hash_heads[HASH_SIZE]; |
210 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock); |
211 | |
212 | /* Function to return search key in our hash from inode. */ |
213 | static unsigned long inode_to_key(const struct inode *inode) |
214 | { |
215 | /* Use address pointed to by connector->obj as the key */ |
216 | return (unsigned long)&inode->i_fsnotify_marks; |
217 | } |
218 | |
219 | static inline struct list_head *chunk_hash(unsigned long key) |
220 | { |
221 | unsigned long n = key / L1_CACHE_BYTES; |
222 | return chunk_hash_heads + n % HASH_SIZE; |
223 | } |
224 | |
225 | /* hash_lock & mark->group->mark_mutex is held by caller */ |
226 | static void insert_hash(struct audit_chunk *chunk) |
227 | { |
228 | struct list_head *list; |
229 | |
230 | /* |
231 | * Make sure chunk is fully initialized before making it visible in the |
232 | * hash. Pairs with a data dependency barrier in READ_ONCE() in |
233 | * audit_tree_lookup(). |
234 | */ |
235 | smp_wmb(); |
236 | WARN_ON_ONCE(!chunk->key); |
237 | list = chunk_hash(key: chunk->key); |
238 | list_add_rcu(new: &chunk->hash, head: list); |
239 | } |
240 | |
241 | /* called under rcu_read_lock */ |
242 | struct audit_chunk *audit_tree_lookup(const struct inode *inode) |
243 | { |
244 | unsigned long key = inode_to_key(inode); |
245 | struct list_head *list = chunk_hash(key); |
246 | struct audit_chunk *p; |
247 | |
248 | list_for_each_entry_rcu(p, list, hash) { |
249 | /* |
250 | * We use a data dependency barrier in READ_ONCE() to make sure |
251 | * the chunk we see is fully initialized. |
252 | */ |
253 | if (READ_ONCE(p->key) == key) { |
254 | atomic_long_inc(v: &p->refs); |
255 | return p; |
256 | } |
257 | } |
258 | return NULL; |
259 | } |
260 | |
261 | bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree) |
262 | { |
263 | int n; |
264 | for (n = 0; n < chunk->count; n++) |
265 | if (chunk->owners[n].owner == tree) |
266 | return true; |
267 | return false; |
268 | } |
269 | |
270 | /* tagging and untagging inodes with trees */ |
271 | |
272 | static struct audit_chunk *find_chunk(struct audit_node *p) |
273 | { |
274 | int index = p->index & ~(1U<<31); |
275 | p -= index; |
276 | return container_of(p, struct audit_chunk, owners[0]); |
277 | } |
278 | |
279 | static void replace_mark_chunk(struct fsnotify_mark *mark, |
280 | struct audit_chunk *chunk) |
281 | { |
282 | struct audit_chunk *old; |
283 | |
284 | assert_spin_locked(&hash_lock); |
285 | old = mark_chunk(mark); |
286 | audit_mark(mark)->chunk = chunk; |
287 | if (chunk) |
288 | chunk->mark = mark; |
289 | if (old) |
290 | old->mark = NULL; |
291 | } |
292 | |
293 | static void replace_chunk(struct audit_chunk *new, struct audit_chunk *old) |
294 | { |
295 | struct audit_tree *owner; |
296 | int i, j; |
297 | |
298 | new->key = old->key; |
299 | list_splice_init(list: &old->trees, head: &new->trees); |
300 | list_for_each_entry(owner, &new->trees, same_root) |
301 | owner->root = new; |
302 | for (i = j = 0; j < old->count; i++, j++) { |
303 | if (!old->owners[j].owner) { |
304 | i--; |
305 | continue; |
306 | } |
307 | owner = old->owners[j].owner; |
308 | new->owners[i].owner = owner; |
309 | new->owners[i].index = old->owners[j].index - j + i; |
310 | if (!owner) /* result of earlier fallback */ |
311 | continue; |
312 | get_tree(tree: owner); |
313 | list_replace_init(old: &old->owners[j].list, new: &new->owners[i].list); |
314 | } |
315 | replace_mark_chunk(mark: old->mark, chunk: new); |
316 | /* |
317 | * Make sure chunk is fully initialized before making it visible in the |
318 | * hash. Pairs with a data dependency barrier in READ_ONCE() in |
319 | * audit_tree_lookup(). |
320 | */ |
321 | smp_wmb(); |
322 | list_replace_rcu(old: &old->hash, new: &new->hash); |
323 | } |
324 | |
325 | static void remove_chunk_node(struct audit_chunk *chunk, struct audit_node *p) |
326 | { |
327 | struct audit_tree *owner = p->owner; |
328 | |
329 | if (owner->root == chunk) { |
330 | list_del_init(entry: &owner->same_root); |
331 | owner->root = NULL; |
332 | } |
333 | list_del_init(entry: &p->list); |
334 | p->owner = NULL; |
335 | put_tree(tree: owner); |
336 | } |
337 | |
338 | static int chunk_count_trees(struct audit_chunk *chunk) |
339 | { |
340 | int i; |
341 | int ret = 0; |
342 | |
343 | for (i = 0; i < chunk->count; i++) |
344 | if (chunk->owners[i].owner) |
345 | ret++; |
346 | return ret; |
347 | } |
348 | |
349 | static void untag_chunk(struct audit_chunk *chunk, struct fsnotify_mark *mark) |
350 | { |
351 | struct audit_chunk *new; |
352 | int size; |
353 | |
354 | fsnotify_group_lock(group: audit_tree_group); |
355 | /* |
356 | * mark_mutex stabilizes chunk attached to the mark so we can check |
357 | * whether it didn't change while we've dropped hash_lock. |
358 | */ |
359 | if (!(mark->flags & FSNOTIFY_MARK_FLAG_ATTACHED) || |
360 | mark_chunk(mark) != chunk) |
361 | goto out_mutex; |
362 | |
363 | size = chunk_count_trees(chunk); |
364 | if (!size) { |
365 | spin_lock(lock: &hash_lock); |
366 | list_del_init(entry: &chunk->trees); |
367 | list_del_rcu(entry: &chunk->hash); |
368 | replace_mark_chunk(mark, NULL); |
369 | spin_unlock(lock: &hash_lock); |
370 | fsnotify_detach_mark(mark); |
371 | fsnotify_group_unlock(group: audit_tree_group); |
372 | audit_mark_put_chunk(chunk); |
373 | fsnotify_free_mark(mark); |
374 | return; |
375 | } |
376 | |
377 | new = alloc_chunk(count: size); |
378 | if (!new) |
379 | goto out_mutex; |
380 | |
381 | spin_lock(lock: &hash_lock); |
382 | /* |
383 | * This has to go last when updating chunk as once replace_chunk() is |
384 | * called, new RCU readers can see the new chunk. |
385 | */ |
386 | replace_chunk(new, old: chunk); |
387 | spin_unlock(lock: &hash_lock); |
388 | fsnotify_group_unlock(group: audit_tree_group); |
389 | audit_mark_put_chunk(chunk); |
390 | return; |
391 | |
392 | out_mutex: |
393 | fsnotify_group_unlock(group: audit_tree_group); |
394 | } |
395 | |
396 | /* Call with group->mark_mutex held, releases it */ |
397 | static int create_chunk(struct inode *inode, struct audit_tree *tree) |
398 | { |
399 | struct fsnotify_mark *mark; |
400 | struct audit_chunk *chunk = alloc_chunk(count: 1); |
401 | |
402 | if (!chunk) { |
403 | fsnotify_group_unlock(group: audit_tree_group); |
404 | return -ENOMEM; |
405 | } |
406 | |
407 | mark = alloc_mark(); |
408 | if (!mark) { |
409 | fsnotify_group_unlock(group: audit_tree_group); |
410 | kfree(objp: chunk); |
411 | return -ENOMEM; |
412 | } |
413 | |
414 | if (fsnotify_add_inode_mark_locked(mark, inode, add_flags: 0)) { |
415 | fsnotify_group_unlock(group: audit_tree_group); |
416 | fsnotify_put_mark(mark); |
417 | kfree(objp: chunk); |
418 | return -ENOSPC; |
419 | } |
420 | |
421 | spin_lock(lock: &hash_lock); |
422 | if (tree->goner) { |
423 | spin_unlock(lock: &hash_lock); |
424 | fsnotify_detach_mark(mark); |
425 | fsnotify_group_unlock(group: audit_tree_group); |
426 | fsnotify_free_mark(mark); |
427 | fsnotify_put_mark(mark); |
428 | kfree(objp: chunk); |
429 | return 0; |
430 | } |
431 | replace_mark_chunk(mark, chunk); |
432 | chunk->owners[0].index = (1U << 31); |
433 | chunk->owners[0].owner = tree; |
434 | get_tree(tree); |
435 | list_add(new: &chunk->owners[0].list, head: &tree->chunks); |
436 | if (!tree->root) { |
437 | tree->root = chunk; |
438 | list_add(new: &tree->same_root, head: &chunk->trees); |
439 | } |
440 | chunk->key = inode_to_key(inode); |
441 | /* |
442 | * Inserting into the hash table has to go last as once we do that RCU |
443 | * readers can see the chunk. |
444 | */ |
445 | insert_hash(chunk); |
446 | spin_unlock(lock: &hash_lock); |
447 | fsnotify_group_unlock(group: audit_tree_group); |
448 | /* |
449 | * Drop our initial reference. When mark we point to is getting freed, |
450 | * we get notification through ->freeing_mark callback and cleanup |
451 | * chunk pointing to this mark. |
452 | */ |
453 | fsnotify_put_mark(mark); |
454 | return 0; |
455 | } |
456 | |
457 | /* the first tagged inode becomes root of tree */ |
458 | static int tag_chunk(struct inode *inode, struct audit_tree *tree) |
459 | { |
460 | struct fsnotify_mark *mark; |
461 | struct audit_chunk *chunk, *old; |
462 | struct audit_node *p; |
463 | int n; |
464 | |
465 | fsnotify_group_lock(group: audit_tree_group); |
466 | mark = fsnotify_find_mark(connp: &inode->i_fsnotify_marks, group: audit_tree_group); |
467 | if (!mark) |
468 | return create_chunk(inode, tree); |
469 | |
470 | /* |
471 | * Found mark is guaranteed to be attached and mark_mutex protects mark |
472 | * from getting detached and thus it makes sure there is chunk attached |
473 | * to the mark. |
474 | */ |
475 | /* are we already there? */ |
476 | spin_lock(lock: &hash_lock); |
477 | old = mark_chunk(mark); |
478 | for (n = 0; n < old->count; n++) { |
479 | if (old->owners[n].owner == tree) { |
480 | spin_unlock(lock: &hash_lock); |
481 | fsnotify_group_unlock(group: audit_tree_group); |
482 | fsnotify_put_mark(mark); |
483 | return 0; |
484 | } |
485 | } |
486 | spin_unlock(lock: &hash_lock); |
487 | |
488 | chunk = alloc_chunk(count: old->count + 1); |
489 | if (!chunk) { |
490 | fsnotify_group_unlock(group: audit_tree_group); |
491 | fsnotify_put_mark(mark); |
492 | return -ENOMEM; |
493 | } |
494 | |
495 | spin_lock(lock: &hash_lock); |
496 | if (tree->goner) { |
497 | spin_unlock(lock: &hash_lock); |
498 | fsnotify_group_unlock(group: audit_tree_group); |
499 | fsnotify_put_mark(mark); |
500 | kfree(objp: chunk); |
501 | return 0; |
502 | } |
503 | p = &chunk->owners[chunk->count - 1]; |
504 | p->index = (chunk->count - 1) | (1U<<31); |
505 | p->owner = tree; |
506 | get_tree(tree); |
507 | list_add(new: &p->list, head: &tree->chunks); |
508 | if (!tree->root) { |
509 | tree->root = chunk; |
510 | list_add(new: &tree->same_root, head: &chunk->trees); |
511 | } |
512 | /* |
513 | * This has to go last when updating chunk as once replace_chunk() is |
514 | * called, new RCU readers can see the new chunk. |
515 | */ |
516 | replace_chunk(new: chunk, old); |
517 | spin_unlock(lock: &hash_lock); |
518 | fsnotify_group_unlock(group: audit_tree_group); |
519 | fsnotify_put_mark(mark); /* pair to fsnotify_find_mark */ |
520 | audit_mark_put_chunk(chunk: old); |
521 | |
522 | return 0; |
523 | } |
524 | |
525 | static void audit_tree_log_remove_rule(struct audit_context *context, |
526 | struct audit_krule *rule) |
527 | { |
528 | struct audit_buffer *ab; |
529 | |
530 | if (!audit_enabled) |
531 | return; |
532 | ab = audit_log_start(ctx: context, GFP_KERNEL, AUDIT_CONFIG_CHANGE); |
533 | if (unlikely(!ab)) |
534 | return; |
535 | audit_log_format(ab, fmt: "op=remove_rule dir=" ); |
536 | audit_log_untrustedstring(ab, string: rule->tree->pathname); |
537 | audit_log_key(ab, key: rule->filterkey); |
538 | audit_log_format(ab, fmt: " list=%d res=1" , rule->listnr); |
539 | audit_log_end(ab); |
540 | } |
541 | |
542 | static void kill_rules(struct audit_context *context, struct audit_tree *tree) |
543 | { |
544 | struct audit_krule *rule, *next; |
545 | struct audit_entry *entry; |
546 | |
547 | list_for_each_entry_safe(rule, next, &tree->rules, rlist) { |
548 | entry = container_of(rule, struct audit_entry, rule); |
549 | |
550 | list_del_init(entry: &rule->rlist); |
551 | if (rule->tree) { |
552 | /* not a half-baked one */ |
553 | audit_tree_log_remove_rule(context, rule); |
554 | if (entry->rule.exe) |
555 | audit_remove_mark(audit_mark: entry->rule.exe); |
556 | rule->tree = NULL; |
557 | list_del_rcu(entry: &entry->list); |
558 | list_del(entry: &entry->rule.list); |
559 | call_rcu(head: &entry->rcu, func: audit_free_rule_rcu); |
560 | } |
561 | } |
562 | } |
563 | |
564 | /* |
565 | * Remove tree from chunks. If 'tagged' is set, remove tree only from tagged |
566 | * chunks. The function expects tagged chunks are all at the beginning of the |
567 | * chunks list. |
568 | */ |
569 | static void prune_tree_chunks(struct audit_tree *victim, bool tagged) |
570 | { |
571 | spin_lock(lock: &hash_lock); |
572 | while (!list_empty(head: &victim->chunks)) { |
573 | struct audit_node *p; |
574 | struct audit_chunk *chunk; |
575 | struct fsnotify_mark *mark; |
576 | |
577 | p = list_first_entry(&victim->chunks, struct audit_node, list); |
578 | /* have we run out of marked? */ |
579 | if (tagged && !(p->index & (1U<<31))) |
580 | break; |
581 | chunk = find_chunk(p); |
582 | mark = chunk->mark; |
583 | remove_chunk_node(chunk, p); |
584 | /* Racing with audit_tree_freeing_mark()? */ |
585 | if (!mark) |
586 | continue; |
587 | fsnotify_get_mark(mark); |
588 | spin_unlock(lock: &hash_lock); |
589 | |
590 | untag_chunk(chunk, mark); |
591 | fsnotify_put_mark(mark); |
592 | |
593 | spin_lock(lock: &hash_lock); |
594 | } |
595 | spin_unlock(lock: &hash_lock); |
596 | } |
597 | |
598 | /* |
599 | * finish killing struct audit_tree |
600 | */ |
601 | static void prune_one(struct audit_tree *victim) |
602 | { |
603 | prune_tree_chunks(victim, tagged: false); |
604 | put_tree(tree: victim); |
605 | } |
606 | |
607 | /* trim the uncommitted chunks from tree */ |
608 | |
609 | static void trim_marked(struct audit_tree *tree) |
610 | { |
611 | struct list_head *p, *q; |
612 | spin_lock(lock: &hash_lock); |
613 | if (tree->goner) { |
614 | spin_unlock(lock: &hash_lock); |
615 | return; |
616 | } |
617 | /* reorder */ |
618 | for (p = tree->chunks.next; p != &tree->chunks; p = q) { |
619 | struct audit_node *node = list_entry(p, struct audit_node, list); |
620 | q = p->next; |
621 | if (node->index & (1U<<31)) { |
622 | list_del_init(entry: p); |
623 | list_add(new: p, head: &tree->chunks); |
624 | } |
625 | } |
626 | spin_unlock(lock: &hash_lock); |
627 | |
628 | prune_tree_chunks(victim: tree, tagged: true); |
629 | |
630 | spin_lock(lock: &hash_lock); |
631 | if (!tree->root && !tree->goner) { |
632 | tree->goner = 1; |
633 | spin_unlock(lock: &hash_lock); |
634 | mutex_lock(&audit_filter_mutex); |
635 | kill_rules(context: audit_context(), tree); |
636 | list_del_init(entry: &tree->list); |
637 | mutex_unlock(lock: &audit_filter_mutex); |
638 | prune_one(victim: tree); |
639 | } else { |
640 | spin_unlock(lock: &hash_lock); |
641 | } |
642 | } |
643 | |
644 | static void audit_schedule_prune(void); |
645 | |
646 | /* called with audit_filter_mutex */ |
647 | int audit_remove_tree_rule(struct audit_krule *rule) |
648 | { |
649 | struct audit_tree *tree; |
650 | tree = rule->tree; |
651 | if (tree) { |
652 | spin_lock(lock: &hash_lock); |
653 | list_del_init(entry: &rule->rlist); |
654 | if (list_empty(head: &tree->rules) && !tree->goner) { |
655 | tree->root = NULL; |
656 | list_del_init(entry: &tree->same_root); |
657 | tree->goner = 1; |
658 | list_move(list: &tree->list, head: &prune_list); |
659 | rule->tree = NULL; |
660 | spin_unlock(lock: &hash_lock); |
661 | audit_schedule_prune(); |
662 | return 1; |
663 | } |
664 | rule->tree = NULL; |
665 | spin_unlock(lock: &hash_lock); |
666 | return 1; |
667 | } |
668 | return 0; |
669 | } |
670 | |
671 | static int compare_root(struct vfsmount *mnt, void *arg) |
672 | { |
673 | return inode_to_key(inode: d_backing_inode(upper: mnt->mnt_root)) == |
674 | (unsigned long)arg; |
675 | } |
676 | |
677 | void audit_trim_trees(void) |
678 | { |
679 | struct list_head cursor; |
680 | |
681 | mutex_lock(&audit_filter_mutex); |
682 | list_add(new: &cursor, head: &tree_list); |
683 | while (cursor.next != &tree_list) { |
684 | struct audit_tree *tree; |
685 | struct path path; |
686 | struct vfsmount *root_mnt; |
687 | struct audit_node *node; |
688 | int err; |
689 | |
690 | tree = container_of(cursor.next, struct audit_tree, list); |
691 | get_tree(tree); |
692 | list_move(list: &cursor, head: &tree->list); |
693 | mutex_unlock(lock: &audit_filter_mutex); |
694 | |
695 | err = kern_path(tree->pathname, 0, &path); |
696 | if (err) |
697 | goto skip_it; |
698 | |
699 | root_mnt = collect_mounts(&path); |
700 | path_put(&path); |
701 | if (IS_ERR(ptr: root_mnt)) |
702 | goto skip_it; |
703 | |
704 | spin_lock(lock: &hash_lock); |
705 | list_for_each_entry(node, &tree->chunks, list) { |
706 | struct audit_chunk *chunk = find_chunk(p: node); |
707 | /* this could be NULL if the watch is dying else where... */ |
708 | node->index |= 1U<<31; |
709 | if (iterate_mounts(compare_root, |
710 | (void *)(chunk->key), |
711 | root_mnt)) |
712 | node->index &= ~(1U<<31); |
713 | } |
714 | spin_unlock(lock: &hash_lock); |
715 | trim_marked(tree); |
716 | drop_collected_mounts(root_mnt); |
717 | skip_it: |
718 | put_tree(tree); |
719 | mutex_lock(&audit_filter_mutex); |
720 | } |
721 | list_del(entry: &cursor); |
722 | mutex_unlock(lock: &audit_filter_mutex); |
723 | } |
724 | |
725 | int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op) |
726 | { |
727 | |
728 | if (pathname[0] != '/' || |
729 | (rule->listnr != AUDIT_FILTER_EXIT && |
730 | rule->listnr != AUDIT_FILTER_URING_EXIT) || |
731 | op != Audit_equal || |
732 | rule->inode_f || rule->watch || rule->tree) |
733 | return -EINVAL; |
734 | rule->tree = alloc_tree(s: pathname); |
735 | if (!rule->tree) |
736 | return -ENOMEM; |
737 | return 0; |
738 | } |
739 | |
740 | void audit_put_tree(struct audit_tree *tree) |
741 | { |
742 | put_tree(tree); |
743 | } |
744 | |
745 | static int tag_mount(struct vfsmount *mnt, void *arg) |
746 | { |
747 | return tag_chunk(inode: d_backing_inode(upper: mnt->mnt_root), tree: arg); |
748 | } |
749 | |
750 | /* |
751 | * That gets run when evict_chunk() ends up needing to kill audit_tree. |
752 | * Runs from a separate thread. |
753 | */ |
754 | static int prune_tree_thread(void *unused) |
755 | { |
756 | for (;;) { |
757 | if (list_empty(head: &prune_list)) { |
758 | set_current_state(TASK_INTERRUPTIBLE); |
759 | schedule(); |
760 | } |
761 | |
762 | audit_ctl_lock(); |
763 | mutex_lock(&audit_filter_mutex); |
764 | |
765 | while (!list_empty(head: &prune_list)) { |
766 | struct audit_tree *victim; |
767 | |
768 | victim = list_entry(prune_list.next, |
769 | struct audit_tree, list); |
770 | list_del_init(entry: &victim->list); |
771 | |
772 | mutex_unlock(lock: &audit_filter_mutex); |
773 | |
774 | prune_one(victim); |
775 | |
776 | mutex_lock(&audit_filter_mutex); |
777 | } |
778 | |
779 | mutex_unlock(lock: &audit_filter_mutex); |
780 | audit_ctl_unlock(); |
781 | } |
782 | return 0; |
783 | } |
784 | |
785 | static int audit_launch_prune(void) |
786 | { |
787 | if (prune_thread) |
788 | return 0; |
789 | prune_thread = kthread_run(prune_tree_thread, NULL, |
790 | "audit_prune_tree" ); |
791 | if (IS_ERR(ptr: prune_thread)) { |
792 | pr_err("cannot start thread audit_prune_tree" ); |
793 | prune_thread = NULL; |
794 | return -ENOMEM; |
795 | } |
796 | return 0; |
797 | } |
798 | |
799 | /* called with audit_filter_mutex */ |
800 | int audit_add_tree_rule(struct audit_krule *rule) |
801 | { |
802 | struct audit_tree *seed = rule->tree, *tree; |
803 | struct path path; |
804 | struct vfsmount *mnt; |
805 | int err; |
806 | |
807 | rule->tree = NULL; |
808 | list_for_each_entry(tree, &tree_list, list) { |
809 | if (!strcmp(seed->pathname, tree->pathname)) { |
810 | put_tree(tree: seed); |
811 | rule->tree = tree; |
812 | list_add(new: &rule->rlist, head: &tree->rules); |
813 | return 0; |
814 | } |
815 | } |
816 | tree = seed; |
817 | list_add(new: &tree->list, head: &tree_list); |
818 | list_add(new: &rule->rlist, head: &tree->rules); |
819 | /* do not set rule->tree yet */ |
820 | mutex_unlock(lock: &audit_filter_mutex); |
821 | |
822 | if (unlikely(!prune_thread)) { |
823 | err = audit_launch_prune(); |
824 | if (err) |
825 | goto Err; |
826 | } |
827 | |
828 | err = kern_path(tree->pathname, 0, &path); |
829 | if (err) |
830 | goto Err; |
831 | mnt = collect_mounts(&path); |
832 | path_put(&path); |
833 | if (IS_ERR(ptr: mnt)) { |
834 | err = PTR_ERR(ptr: mnt); |
835 | goto Err; |
836 | } |
837 | |
838 | get_tree(tree); |
839 | err = iterate_mounts(tag_mount, tree, mnt); |
840 | drop_collected_mounts(mnt); |
841 | |
842 | if (!err) { |
843 | struct audit_node *node; |
844 | spin_lock(lock: &hash_lock); |
845 | list_for_each_entry(node, &tree->chunks, list) |
846 | node->index &= ~(1U<<31); |
847 | spin_unlock(lock: &hash_lock); |
848 | } else { |
849 | trim_marked(tree); |
850 | goto Err; |
851 | } |
852 | |
853 | mutex_lock(&audit_filter_mutex); |
854 | if (list_empty(head: &rule->rlist)) { |
855 | put_tree(tree); |
856 | return -ENOENT; |
857 | } |
858 | rule->tree = tree; |
859 | put_tree(tree); |
860 | |
861 | return 0; |
862 | Err: |
863 | mutex_lock(&audit_filter_mutex); |
864 | list_del_init(entry: &tree->list); |
865 | list_del_init(entry: &tree->rules); |
866 | put_tree(tree); |
867 | return err; |
868 | } |
869 | |
870 | int audit_tag_tree(char *old, char *new) |
871 | { |
872 | struct list_head cursor, barrier; |
873 | int failed = 0; |
874 | struct path path1, path2; |
875 | struct vfsmount *tagged; |
876 | int err; |
877 | |
878 | err = kern_path(new, 0, &path2); |
879 | if (err) |
880 | return err; |
881 | tagged = collect_mounts(&path2); |
882 | path_put(&path2); |
883 | if (IS_ERR(ptr: tagged)) |
884 | return PTR_ERR(ptr: tagged); |
885 | |
886 | err = kern_path(old, 0, &path1); |
887 | if (err) { |
888 | drop_collected_mounts(tagged); |
889 | return err; |
890 | } |
891 | |
892 | mutex_lock(&audit_filter_mutex); |
893 | list_add(new: &barrier, head: &tree_list); |
894 | list_add(new: &cursor, head: &barrier); |
895 | |
896 | while (cursor.next != &tree_list) { |
897 | struct audit_tree *tree; |
898 | int good_one = 0; |
899 | |
900 | tree = container_of(cursor.next, struct audit_tree, list); |
901 | get_tree(tree); |
902 | list_move(list: &cursor, head: &tree->list); |
903 | mutex_unlock(lock: &audit_filter_mutex); |
904 | |
905 | err = kern_path(tree->pathname, 0, &path2); |
906 | if (!err) { |
907 | good_one = path_is_under(&path1, &path2); |
908 | path_put(&path2); |
909 | } |
910 | |
911 | if (!good_one) { |
912 | put_tree(tree); |
913 | mutex_lock(&audit_filter_mutex); |
914 | continue; |
915 | } |
916 | |
917 | failed = iterate_mounts(tag_mount, tree, tagged); |
918 | if (failed) { |
919 | put_tree(tree); |
920 | mutex_lock(&audit_filter_mutex); |
921 | break; |
922 | } |
923 | |
924 | mutex_lock(&audit_filter_mutex); |
925 | spin_lock(lock: &hash_lock); |
926 | if (!tree->goner) { |
927 | list_move(list: &tree->list, head: &tree_list); |
928 | } |
929 | spin_unlock(lock: &hash_lock); |
930 | put_tree(tree); |
931 | } |
932 | |
933 | while (barrier.prev != &tree_list) { |
934 | struct audit_tree *tree; |
935 | |
936 | tree = container_of(barrier.prev, struct audit_tree, list); |
937 | get_tree(tree); |
938 | list_move(list: &tree->list, head: &barrier); |
939 | mutex_unlock(lock: &audit_filter_mutex); |
940 | |
941 | if (!failed) { |
942 | struct audit_node *node; |
943 | spin_lock(lock: &hash_lock); |
944 | list_for_each_entry(node, &tree->chunks, list) |
945 | node->index &= ~(1U<<31); |
946 | spin_unlock(lock: &hash_lock); |
947 | } else { |
948 | trim_marked(tree); |
949 | } |
950 | |
951 | put_tree(tree); |
952 | mutex_lock(&audit_filter_mutex); |
953 | } |
954 | list_del(entry: &barrier); |
955 | list_del(entry: &cursor); |
956 | mutex_unlock(lock: &audit_filter_mutex); |
957 | path_put(&path1); |
958 | drop_collected_mounts(tagged); |
959 | return failed; |
960 | } |
961 | |
962 | |
963 | static void audit_schedule_prune(void) |
964 | { |
965 | wake_up_process(tsk: prune_thread); |
966 | } |
967 | |
968 | /* |
969 | * ... and that one is done if evict_chunk() decides to delay until the end |
970 | * of syscall. Runs synchronously. |
971 | */ |
972 | void audit_kill_trees(struct audit_context *context) |
973 | { |
974 | struct list_head *list = &context->killed_trees; |
975 | |
976 | audit_ctl_lock(); |
977 | mutex_lock(&audit_filter_mutex); |
978 | |
979 | while (!list_empty(head: list)) { |
980 | struct audit_tree *victim; |
981 | |
982 | victim = list_entry(list->next, struct audit_tree, list); |
983 | kill_rules(context, tree: victim); |
984 | list_del_init(entry: &victim->list); |
985 | |
986 | mutex_unlock(lock: &audit_filter_mutex); |
987 | |
988 | prune_one(victim); |
989 | |
990 | mutex_lock(&audit_filter_mutex); |
991 | } |
992 | |
993 | mutex_unlock(lock: &audit_filter_mutex); |
994 | audit_ctl_unlock(); |
995 | } |
996 | |
997 | /* |
998 | * Here comes the stuff asynchronous to auditctl operations |
999 | */ |
1000 | |
1001 | static void evict_chunk(struct audit_chunk *chunk) |
1002 | { |
1003 | struct audit_tree *owner; |
1004 | struct list_head *postponed = audit_killed_trees(); |
1005 | int need_prune = 0; |
1006 | int n; |
1007 | |
1008 | mutex_lock(&audit_filter_mutex); |
1009 | spin_lock(lock: &hash_lock); |
1010 | while (!list_empty(head: &chunk->trees)) { |
1011 | owner = list_entry(chunk->trees.next, |
1012 | struct audit_tree, same_root); |
1013 | owner->goner = 1; |
1014 | owner->root = NULL; |
1015 | list_del_init(entry: &owner->same_root); |
1016 | spin_unlock(lock: &hash_lock); |
1017 | if (!postponed) { |
1018 | kill_rules(context: audit_context(), tree: owner); |
1019 | list_move(list: &owner->list, head: &prune_list); |
1020 | need_prune = 1; |
1021 | } else { |
1022 | list_move(list: &owner->list, head: postponed); |
1023 | } |
1024 | spin_lock(lock: &hash_lock); |
1025 | } |
1026 | list_del_rcu(entry: &chunk->hash); |
1027 | for (n = 0; n < chunk->count; n++) |
1028 | list_del_init(entry: &chunk->owners[n].list); |
1029 | spin_unlock(lock: &hash_lock); |
1030 | mutex_unlock(lock: &audit_filter_mutex); |
1031 | if (need_prune) |
1032 | audit_schedule_prune(); |
1033 | } |
1034 | |
1035 | static int audit_tree_handle_event(struct fsnotify_mark *mark, u32 mask, |
1036 | struct inode *inode, struct inode *dir, |
1037 | const struct qstr *file_name, u32 cookie) |
1038 | { |
1039 | return 0; |
1040 | } |
1041 | |
1042 | static void audit_tree_freeing_mark(struct fsnotify_mark *mark, |
1043 | struct fsnotify_group *group) |
1044 | { |
1045 | struct audit_chunk *chunk; |
1046 | |
1047 | fsnotify_group_lock(group: mark->group); |
1048 | spin_lock(lock: &hash_lock); |
1049 | chunk = mark_chunk(mark); |
1050 | replace_mark_chunk(mark, NULL); |
1051 | spin_unlock(lock: &hash_lock); |
1052 | fsnotify_group_unlock(group: mark->group); |
1053 | if (chunk) { |
1054 | evict_chunk(chunk); |
1055 | audit_mark_put_chunk(chunk); |
1056 | } |
1057 | |
1058 | /* |
1059 | * We are guaranteed to have at least one reference to the mark from |
1060 | * either the inode or the caller of fsnotify_destroy_mark(). |
1061 | */ |
1062 | BUG_ON(refcount_read(&mark->refcnt) < 1); |
1063 | } |
1064 | |
1065 | static const struct fsnotify_ops audit_tree_ops = { |
1066 | .handle_inode_event = audit_tree_handle_event, |
1067 | .freeing_mark = audit_tree_freeing_mark, |
1068 | .free_mark = audit_tree_destroy_watch, |
1069 | }; |
1070 | |
1071 | static int __init audit_tree_init(void) |
1072 | { |
1073 | int i; |
1074 | |
1075 | audit_tree_mark_cachep = KMEM_CACHE(audit_tree_mark, SLAB_PANIC); |
1076 | |
1077 | audit_tree_group = fsnotify_alloc_group(ops: &audit_tree_ops, flags: 0); |
1078 | if (IS_ERR(ptr: audit_tree_group)) |
1079 | audit_panic(message: "cannot initialize fsnotify group for rectree watches" ); |
1080 | |
1081 | for (i = 0; i < HASH_SIZE; i++) |
1082 | INIT_LIST_HEAD(list: &chunk_hash_heads[i]); |
1083 | |
1084 | return 0; |
1085 | } |
1086 | __initcall(audit_tree_init); |
1087 | |