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