blob: 25772476fa4afcfec54210527f548588c402c109
1 | #include "audit.h" |
2 | #include <linux/fsnotify_backend.h> |
3 | #include <linux/namei.h> |
4 | #include <linux/mount.h> |
5 | #include <linux/kthread.h> |
6 | #include <linux/slab.h> |
7 | |
8 | struct audit_tree; |
9 | struct audit_chunk; |
10 | |
11 | struct audit_tree { |
12 | atomic_t count; |
13 | int goner; |
14 | struct audit_chunk *root; |
15 | struct list_head chunks; |
16 | struct list_head rules; |
17 | struct list_head list; |
18 | struct list_head same_root; |
19 | struct rcu_head head; |
20 | char pathname[]; |
21 | }; |
22 | |
23 | struct audit_chunk { |
24 | struct list_head hash; |
25 | struct fsnotify_mark mark; |
26 | struct list_head trees; /* with root here */ |
27 | int dead; |
28 | int count; |
29 | atomic_long_t refs; |
30 | struct rcu_head head; |
31 | struct node { |
32 | struct list_head list; |
33 | struct audit_tree *owner; |
34 | unsigned index; /* index; upper bit indicates 'will prune' */ |
35 | } owners[]; |
36 | }; |
37 | |
38 | static LIST_HEAD(tree_list); |
39 | static LIST_HEAD(prune_list); |
40 | static struct task_struct *prune_thread; |
41 | |
42 | /* |
43 | * One struct chunk is attached to each inode of interest. |
44 | * We replace struct chunk on tagging/untagging. |
45 | * Rules have pointer to struct audit_tree. |
46 | * Rules have struct list_head rlist forming a list of rules over |
47 | * the same tree. |
48 | * References to struct chunk are collected at audit_inode{,_child}() |
49 | * time and used in AUDIT_TREE rule matching. |
50 | * These references are dropped at the same time we are calling |
51 | * audit_free_names(), etc. |
52 | * |
53 | * Cyclic lists galore: |
54 | * tree.chunks anchors chunk.owners[].list hash_lock |
55 | * tree.rules anchors rule.rlist audit_filter_mutex |
56 | * chunk.trees anchors tree.same_root hash_lock |
57 | * chunk.hash is a hash with middle bits of watch.inode as |
58 | * a hash function. RCU, hash_lock |
59 | * |
60 | * tree is refcounted; one reference for "some rules on rules_list refer to |
61 | * it", one for each chunk with pointer to it. |
62 | * |
63 | * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount |
64 | * of watch contributes 1 to .refs). |
65 | * |
66 | * node.index allows to get from node.list to containing chunk. |
67 | * MSB of that sucker is stolen to mark taggings that we might have to |
68 | * revert - several operations have very unpleasant cleanup logics and |
69 | * that makes a difference. Some. |
70 | */ |
71 | |
72 | static struct fsnotify_group *audit_tree_group; |
73 | |
74 | static struct audit_tree *alloc_tree(const char *s) |
75 | { |
76 | struct audit_tree *tree; |
77 | |
78 | tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL); |
79 | if (tree) { |
80 | atomic_set(&tree->count, 1); |
81 | tree->goner = 0; |
82 | INIT_LIST_HEAD(&tree->chunks); |
83 | INIT_LIST_HEAD(&tree->rules); |
84 | INIT_LIST_HEAD(&tree->list); |
85 | INIT_LIST_HEAD(&tree->same_root); |
86 | tree->root = NULL; |
87 | strcpy(tree->pathname, s); |
88 | } |
89 | return tree; |
90 | } |
91 | |
92 | static inline void get_tree(struct audit_tree *tree) |
93 | { |
94 | atomic_inc(&tree->count); |
95 | } |
96 | |
97 | static inline void put_tree(struct audit_tree *tree) |
98 | { |
99 | if (atomic_dec_and_test(&tree->count)) |
100 | kfree_rcu(tree, head); |
101 | } |
102 | |
103 | /* to avoid bringing the entire thing in audit.h */ |
104 | const char *audit_tree_path(struct audit_tree *tree) |
105 | { |
106 | return tree->pathname; |
107 | } |
108 | |
109 | static void free_chunk(struct audit_chunk *chunk) |
110 | { |
111 | int i; |
112 | |
113 | for (i = 0; i < chunk->count; i++) { |
114 | if (chunk->owners[i].owner) |
115 | put_tree(chunk->owners[i].owner); |
116 | } |
117 | kfree(chunk); |
118 | } |
119 | |
120 | void audit_put_chunk(struct audit_chunk *chunk) |
121 | { |
122 | if (atomic_long_dec_and_test(&chunk->refs)) |
123 | free_chunk(chunk); |
124 | } |
125 | |
126 | static void __put_chunk(struct rcu_head *rcu) |
127 | { |
128 | struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head); |
129 | audit_put_chunk(chunk); |
130 | } |
131 | |
132 | static void audit_tree_destroy_watch(struct fsnotify_mark *entry) |
133 | { |
134 | struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark); |
135 | call_rcu(&chunk->head, __put_chunk); |
136 | } |
137 | |
138 | static struct audit_chunk *alloc_chunk(int count) |
139 | { |
140 | struct audit_chunk *chunk; |
141 | size_t size; |
142 | int i; |
143 | |
144 | size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node); |
145 | chunk = kzalloc(size, GFP_KERNEL); |
146 | if (!chunk) |
147 | return NULL; |
148 | |
149 | INIT_LIST_HEAD(&chunk->hash); |
150 | INIT_LIST_HEAD(&chunk->trees); |
151 | chunk->count = count; |
152 | atomic_long_set(&chunk->refs, 1); |
153 | for (i = 0; i < count; i++) { |
154 | INIT_LIST_HEAD(&chunk->owners[i].list); |
155 | chunk->owners[i].index = i; |
156 | } |
157 | fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch); |
158 | chunk->mark.mask = FS_IN_IGNORED; |
159 | return chunk; |
160 | } |
161 | |
162 | enum {HASH_SIZE = 128}; |
163 | static struct list_head chunk_hash_heads[HASH_SIZE]; |
164 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock); |
165 | |
166 | static inline struct list_head *chunk_hash(const struct inode *inode) |
167 | { |
168 | unsigned long n = (unsigned long)inode / L1_CACHE_BYTES; |
169 | return chunk_hash_heads + n % HASH_SIZE; |
170 | } |
171 | |
172 | /* hash_lock & entry->lock is held by caller */ |
173 | static void insert_hash(struct audit_chunk *chunk) |
174 | { |
175 | struct fsnotify_mark *entry = &chunk->mark; |
176 | struct list_head *list; |
177 | |
178 | if (!entry->inode) |
179 | return; |
180 | list = chunk_hash(entry->inode); |
181 | list_add_rcu(&chunk->hash, list); |
182 | } |
183 | |
184 | /* called under rcu_read_lock */ |
185 | struct audit_chunk *audit_tree_lookup(const struct inode *inode) |
186 | { |
187 | struct list_head *list = chunk_hash(inode); |
188 | struct audit_chunk *p; |
189 | |
190 | list_for_each_entry_rcu(p, list, hash) { |
191 | /* mark.inode may have gone NULL, but who cares? */ |
192 | if (p->mark.inode == inode) { |
193 | atomic_long_inc(&p->refs); |
194 | return p; |
195 | } |
196 | } |
197 | return NULL; |
198 | } |
199 | |
200 | bool audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree) |
201 | { |
202 | int n; |
203 | for (n = 0; n < chunk->count; n++) |
204 | if (chunk->owners[n].owner == tree) |
205 | return true; |
206 | return false; |
207 | } |
208 | |
209 | /* tagging and untagging inodes with trees */ |
210 | |
211 | static struct audit_chunk *find_chunk(struct node *p) |
212 | { |
213 | int index = p->index & ~(1U<<31); |
214 | p -= index; |
215 | return container_of(p, struct audit_chunk, owners[0]); |
216 | } |
217 | |
218 | static void untag_chunk(struct node *p) |
219 | { |
220 | struct audit_chunk *chunk = find_chunk(p); |
221 | struct fsnotify_mark *entry = &chunk->mark; |
222 | struct audit_chunk *new = NULL; |
223 | struct audit_tree *owner; |
224 | int size = chunk->count - 1; |
225 | int i, j; |
226 | |
227 | fsnotify_get_mark(entry); |
228 | |
229 | spin_unlock(&hash_lock); |
230 | |
231 | if (size) |
232 | new = alloc_chunk(size); |
233 | |
234 | spin_lock(&entry->lock); |
235 | if (chunk->dead || !entry->inode) { |
236 | spin_unlock(&entry->lock); |
237 | if (new) |
238 | free_chunk(new); |
239 | goto out; |
240 | } |
241 | |
242 | owner = p->owner; |
243 | |
244 | if (!size) { |
245 | chunk->dead = 1; |
246 | spin_lock(&hash_lock); |
247 | list_del_init(&chunk->trees); |
248 | if (owner->root == chunk) |
249 | owner->root = NULL; |
250 | list_del_init(&p->list); |
251 | list_del_rcu(&chunk->hash); |
252 | spin_unlock(&hash_lock); |
253 | spin_unlock(&entry->lock); |
254 | fsnotify_destroy_mark(entry, audit_tree_group); |
255 | goto out; |
256 | } |
257 | |
258 | if (!new) |
259 | goto Fallback; |
260 | |
261 | fsnotify_duplicate_mark(&new->mark, entry); |
262 | if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.inode, NULL, 1)) { |
263 | fsnotify_put_mark(&new->mark); |
264 | goto Fallback; |
265 | } |
266 | |
267 | chunk->dead = 1; |
268 | spin_lock(&hash_lock); |
269 | list_replace_init(&chunk->trees, &new->trees); |
270 | if (owner->root == chunk) { |
271 | list_del_init(&owner->same_root); |
272 | owner->root = NULL; |
273 | } |
274 | |
275 | for (i = j = 0; j <= size; i++, j++) { |
276 | struct audit_tree *s; |
277 | if (&chunk->owners[j] == p) { |
278 | list_del_init(&p->list); |
279 | i--; |
280 | continue; |
281 | } |
282 | s = chunk->owners[j].owner; |
283 | new->owners[i].owner = s; |
284 | new->owners[i].index = chunk->owners[j].index - j + i; |
285 | if (!s) /* result of earlier fallback */ |
286 | continue; |
287 | get_tree(s); |
288 | list_replace_init(&chunk->owners[j].list, &new->owners[i].list); |
289 | } |
290 | |
291 | list_replace_rcu(&chunk->hash, &new->hash); |
292 | list_for_each_entry(owner, &new->trees, same_root) |
293 | owner->root = new; |
294 | spin_unlock(&hash_lock); |
295 | spin_unlock(&entry->lock); |
296 | fsnotify_destroy_mark(entry, audit_tree_group); |
297 | fsnotify_put_mark(&new->mark); /* drop initial reference */ |
298 | goto out; |
299 | |
300 | Fallback: |
301 | // do the best we can |
302 | spin_lock(&hash_lock); |
303 | if (owner->root == chunk) { |
304 | list_del_init(&owner->same_root); |
305 | owner->root = NULL; |
306 | } |
307 | list_del_init(&p->list); |
308 | p->owner = NULL; |
309 | put_tree(owner); |
310 | spin_unlock(&hash_lock); |
311 | spin_unlock(&entry->lock); |
312 | out: |
313 | fsnotify_put_mark(entry); |
314 | spin_lock(&hash_lock); |
315 | } |
316 | |
317 | static int create_chunk(struct inode *inode, struct audit_tree *tree) |
318 | { |
319 | struct fsnotify_mark *entry; |
320 | struct audit_chunk *chunk = alloc_chunk(1); |
321 | if (!chunk) |
322 | return -ENOMEM; |
323 | |
324 | entry = &chunk->mark; |
325 | if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) { |
326 | fsnotify_put_mark(entry); |
327 | return -ENOSPC; |
328 | } |
329 | |
330 | spin_lock(&entry->lock); |
331 | spin_lock(&hash_lock); |
332 | if (tree->goner) { |
333 | spin_unlock(&hash_lock); |
334 | chunk->dead = 1; |
335 | spin_unlock(&entry->lock); |
336 | fsnotify_destroy_mark(entry, audit_tree_group); |
337 | fsnotify_put_mark(entry); |
338 | return 0; |
339 | } |
340 | chunk->owners[0].index = (1U << 31); |
341 | chunk->owners[0].owner = tree; |
342 | get_tree(tree); |
343 | list_add(&chunk->owners[0].list, &tree->chunks); |
344 | if (!tree->root) { |
345 | tree->root = chunk; |
346 | list_add(&tree->same_root, &chunk->trees); |
347 | } |
348 | insert_hash(chunk); |
349 | spin_unlock(&hash_lock); |
350 | spin_unlock(&entry->lock); |
351 | fsnotify_put_mark(entry); /* drop initial reference */ |
352 | return 0; |
353 | } |
354 | |
355 | /* the first tagged inode becomes root of tree */ |
356 | static int tag_chunk(struct inode *inode, struct audit_tree *tree) |
357 | { |
358 | struct fsnotify_mark *old_entry, *chunk_entry; |
359 | struct audit_tree *owner; |
360 | struct audit_chunk *chunk, *old; |
361 | struct node *p; |
362 | int n; |
363 | |
364 | old_entry = fsnotify_find_inode_mark(audit_tree_group, inode); |
365 | if (!old_entry) |
366 | return create_chunk(inode, tree); |
367 | |
368 | old = container_of(old_entry, struct audit_chunk, mark); |
369 | |
370 | /* are we already there? */ |
371 | spin_lock(&hash_lock); |
372 | for (n = 0; n < old->count; n++) { |
373 | if (old->owners[n].owner == tree) { |
374 | spin_unlock(&hash_lock); |
375 | fsnotify_put_mark(old_entry); |
376 | return 0; |
377 | } |
378 | } |
379 | spin_unlock(&hash_lock); |
380 | |
381 | chunk = alloc_chunk(old->count + 1); |
382 | if (!chunk) { |
383 | fsnotify_put_mark(old_entry); |
384 | return -ENOMEM; |
385 | } |
386 | |
387 | chunk_entry = &chunk->mark; |
388 | |
389 | spin_lock(&old_entry->lock); |
390 | if (!old_entry->inode) { |
391 | /* old_entry is being shot, lets just lie */ |
392 | spin_unlock(&old_entry->lock); |
393 | fsnotify_put_mark(old_entry); |
394 | free_chunk(chunk); |
395 | return -ENOENT; |
396 | } |
397 | |
398 | fsnotify_duplicate_mark(chunk_entry, old_entry); |
399 | if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->inode, NULL, 1)) { |
400 | spin_unlock(&old_entry->lock); |
401 | fsnotify_put_mark(chunk_entry); |
402 | fsnotify_put_mark(old_entry); |
403 | return -ENOSPC; |
404 | } |
405 | |
406 | /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */ |
407 | spin_lock(&chunk_entry->lock); |
408 | spin_lock(&hash_lock); |
409 | |
410 | /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */ |
411 | if (tree->goner) { |
412 | spin_unlock(&hash_lock); |
413 | chunk->dead = 1; |
414 | spin_unlock(&chunk_entry->lock); |
415 | spin_unlock(&old_entry->lock); |
416 | |
417 | fsnotify_destroy_mark(chunk_entry, audit_tree_group); |
418 | |
419 | fsnotify_put_mark(chunk_entry); |
420 | fsnotify_put_mark(old_entry); |
421 | return 0; |
422 | } |
423 | list_replace_init(&old->trees, &chunk->trees); |
424 | for (n = 0, p = chunk->owners; n < old->count; n++, p++) { |
425 | struct audit_tree *s = old->owners[n].owner; |
426 | p->owner = s; |
427 | p->index = old->owners[n].index; |
428 | if (!s) /* result of fallback in untag */ |
429 | continue; |
430 | get_tree(s); |
431 | list_replace_init(&old->owners[n].list, &p->list); |
432 | } |
433 | p->index = (chunk->count - 1) | (1U<<31); |
434 | p->owner = tree; |
435 | get_tree(tree); |
436 | list_add(&p->list, &tree->chunks); |
437 | list_replace_rcu(&old->hash, &chunk->hash); |
438 | list_for_each_entry(owner, &chunk->trees, same_root) |
439 | owner->root = chunk; |
440 | old->dead = 1; |
441 | if (!tree->root) { |
442 | tree->root = chunk; |
443 | list_add(&tree->same_root, &chunk->trees); |
444 | } |
445 | spin_unlock(&hash_lock); |
446 | spin_unlock(&chunk_entry->lock); |
447 | spin_unlock(&old_entry->lock); |
448 | fsnotify_destroy_mark(old_entry, audit_tree_group); |
449 | fsnotify_put_mark(chunk_entry); /* drop initial reference */ |
450 | fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */ |
451 | return 0; |
452 | } |
453 | |
454 | static void audit_tree_log_remove_rule(struct audit_krule *rule) |
455 | { |
456 | struct audit_buffer *ab; |
457 | |
458 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); |
459 | if (unlikely(!ab)) |
460 | return; |
461 | audit_log_format(ab, "op="); |
462 | audit_log_string(ab, "remove_rule"); |
463 | audit_log_format(ab, " dir="); |
464 | audit_log_untrustedstring(ab, rule->tree->pathname); |
465 | audit_log_key(ab, rule->filterkey); |
466 | audit_log_format(ab, " list=%d res=1", rule->listnr); |
467 | audit_log_end(ab); |
468 | } |
469 | |
470 | static void kill_rules(struct audit_tree *tree) |
471 | { |
472 | struct audit_krule *rule, *next; |
473 | struct audit_entry *entry; |
474 | |
475 | list_for_each_entry_safe(rule, next, &tree->rules, rlist) { |
476 | entry = container_of(rule, struct audit_entry, rule); |
477 | |
478 | list_del_init(&rule->rlist); |
479 | if (rule->tree) { |
480 | /* not a half-baked one */ |
481 | audit_tree_log_remove_rule(rule); |
482 | if (entry->rule.exe) |
483 | audit_remove_mark(entry->rule.exe); |
484 | rule->tree = NULL; |
485 | list_del_rcu(&entry->list); |
486 | list_del(&entry->rule.list); |
487 | call_rcu(&entry->rcu, audit_free_rule_rcu); |
488 | } |
489 | } |
490 | } |
491 | |
492 | /* |
493 | * finish killing struct audit_tree |
494 | */ |
495 | static void prune_one(struct audit_tree *victim) |
496 | { |
497 | spin_lock(&hash_lock); |
498 | while (!list_empty(&victim->chunks)) { |
499 | struct node *p; |
500 | |
501 | p = list_entry(victim->chunks.next, struct node, list); |
502 | |
503 | untag_chunk(p); |
504 | } |
505 | spin_unlock(&hash_lock); |
506 | put_tree(victim); |
507 | } |
508 | |
509 | /* trim the uncommitted chunks from tree */ |
510 | |
511 | static void trim_marked(struct audit_tree *tree) |
512 | { |
513 | struct list_head *p, *q; |
514 | spin_lock(&hash_lock); |
515 | if (tree->goner) { |
516 | spin_unlock(&hash_lock); |
517 | return; |
518 | } |
519 | /* reorder */ |
520 | for (p = tree->chunks.next; p != &tree->chunks; p = q) { |
521 | struct node *node = list_entry(p, struct node, list); |
522 | q = p->next; |
523 | if (node->index & (1U<<31)) { |
524 | list_del_init(p); |
525 | list_add(p, &tree->chunks); |
526 | } |
527 | } |
528 | |
529 | while (!list_empty(&tree->chunks)) { |
530 | struct node *node; |
531 | |
532 | node = list_entry(tree->chunks.next, struct node, list); |
533 | |
534 | /* have we run out of marked? */ |
535 | if (!(node->index & (1U<<31))) |
536 | break; |
537 | |
538 | untag_chunk(node); |
539 | } |
540 | if (!tree->root && !tree->goner) { |
541 | tree->goner = 1; |
542 | spin_unlock(&hash_lock); |
543 | mutex_lock(&audit_filter_mutex); |
544 | kill_rules(tree); |
545 | list_del_init(&tree->list); |
546 | mutex_unlock(&audit_filter_mutex); |
547 | prune_one(tree); |
548 | } else { |
549 | spin_unlock(&hash_lock); |
550 | } |
551 | } |
552 | |
553 | static void audit_schedule_prune(void); |
554 | |
555 | /* called with audit_filter_mutex */ |
556 | int audit_remove_tree_rule(struct audit_krule *rule) |
557 | { |
558 | struct audit_tree *tree; |
559 | tree = rule->tree; |
560 | if (tree) { |
561 | spin_lock(&hash_lock); |
562 | list_del_init(&rule->rlist); |
563 | if (list_empty(&tree->rules) && !tree->goner) { |
564 | tree->root = NULL; |
565 | list_del_init(&tree->same_root); |
566 | tree->goner = 1; |
567 | list_move(&tree->list, &prune_list); |
568 | rule->tree = NULL; |
569 | spin_unlock(&hash_lock); |
570 | audit_schedule_prune(); |
571 | return 1; |
572 | } |
573 | rule->tree = NULL; |
574 | spin_unlock(&hash_lock); |
575 | return 1; |
576 | } |
577 | return 0; |
578 | } |
579 | |
580 | static int compare_root(struct vfsmount *mnt, void *arg) |
581 | { |
582 | return d_backing_inode(mnt->mnt_root) == arg; |
583 | } |
584 | |
585 | void audit_trim_trees(void) |
586 | { |
587 | struct list_head cursor; |
588 | |
589 | mutex_lock(&audit_filter_mutex); |
590 | list_add(&cursor, &tree_list); |
591 | while (cursor.next != &tree_list) { |
592 | struct audit_tree *tree; |
593 | struct path path; |
594 | struct vfsmount *root_mnt; |
595 | struct node *node; |
596 | int err; |
597 | |
598 | tree = container_of(cursor.next, struct audit_tree, list); |
599 | get_tree(tree); |
600 | list_del(&cursor); |
601 | list_add(&cursor, &tree->list); |
602 | mutex_unlock(&audit_filter_mutex); |
603 | |
604 | err = kern_path(tree->pathname, 0, &path); |
605 | if (err) |
606 | goto skip_it; |
607 | |
608 | root_mnt = collect_mounts(&path); |
609 | path_put(&path); |
610 | if (IS_ERR(root_mnt)) |
611 | goto skip_it; |
612 | |
613 | spin_lock(&hash_lock); |
614 | list_for_each_entry(node, &tree->chunks, list) { |
615 | struct audit_chunk *chunk = find_chunk(node); |
616 | /* this could be NULL if the watch is dying else where... */ |
617 | struct inode *inode = chunk->mark.inode; |
618 | node->index |= 1U<<31; |
619 | if (iterate_mounts(compare_root, inode, root_mnt)) |
620 | node->index &= ~(1U<<31); |
621 | } |
622 | spin_unlock(&hash_lock); |
623 | trim_marked(tree); |
624 | drop_collected_mounts(root_mnt); |
625 | skip_it: |
626 | put_tree(tree); |
627 | mutex_lock(&audit_filter_mutex); |
628 | } |
629 | list_del(&cursor); |
630 | mutex_unlock(&audit_filter_mutex); |
631 | } |
632 | |
633 | int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op) |
634 | { |
635 | |
636 | if (pathname[0] != '/' || |
637 | rule->listnr != AUDIT_FILTER_EXIT || |
638 | op != Audit_equal || |
639 | rule->inode_f || rule->watch || rule->tree) |
640 | return -EINVAL; |
641 | rule->tree = alloc_tree(pathname); |
642 | if (!rule->tree) |
643 | return -ENOMEM; |
644 | return 0; |
645 | } |
646 | |
647 | void audit_put_tree(struct audit_tree *tree) |
648 | { |
649 | put_tree(tree); |
650 | } |
651 | |
652 | static int tag_mount(struct vfsmount *mnt, void *arg) |
653 | { |
654 | return tag_chunk(d_backing_inode(mnt->mnt_root), arg); |
655 | } |
656 | |
657 | /* |
658 | * That gets run when evict_chunk() ends up needing to kill audit_tree. |
659 | * Runs from a separate thread. |
660 | */ |
661 | static int prune_tree_thread(void *unused) |
662 | { |
663 | for (;;) { |
664 | if (list_empty(&prune_list)) { |
665 | set_current_state(TASK_INTERRUPTIBLE); |
666 | schedule(); |
667 | } |
668 | |
669 | mutex_lock(&audit_cmd_mutex); |
670 | mutex_lock(&audit_filter_mutex); |
671 | |
672 | while (!list_empty(&prune_list)) { |
673 | struct audit_tree *victim; |
674 | |
675 | victim = list_entry(prune_list.next, |
676 | struct audit_tree, list); |
677 | list_del_init(&victim->list); |
678 | |
679 | mutex_unlock(&audit_filter_mutex); |
680 | |
681 | prune_one(victim); |
682 | |
683 | mutex_lock(&audit_filter_mutex); |
684 | } |
685 | |
686 | mutex_unlock(&audit_filter_mutex); |
687 | mutex_unlock(&audit_cmd_mutex); |
688 | } |
689 | return 0; |
690 | } |
691 | |
692 | static int audit_launch_prune(void) |
693 | { |
694 | if (prune_thread) |
695 | return 0; |
696 | prune_thread = kthread_run(prune_tree_thread, NULL, |
697 | "audit_prune_tree"); |
698 | if (IS_ERR(prune_thread)) { |
699 | pr_err("cannot start thread audit_prune_tree"); |
700 | prune_thread = NULL; |
701 | return -ENOMEM; |
702 | } |
703 | return 0; |
704 | } |
705 | |
706 | /* called with audit_filter_mutex */ |
707 | int audit_add_tree_rule(struct audit_krule *rule) |
708 | { |
709 | struct audit_tree *seed = rule->tree, *tree; |
710 | struct path path; |
711 | struct vfsmount *mnt; |
712 | int err; |
713 | |
714 | rule->tree = NULL; |
715 | list_for_each_entry(tree, &tree_list, list) { |
716 | if (!strcmp(seed->pathname, tree->pathname)) { |
717 | put_tree(seed); |
718 | rule->tree = tree; |
719 | list_add(&rule->rlist, &tree->rules); |
720 | return 0; |
721 | } |
722 | } |
723 | tree = seed; |
724 | list_add(&tree->list, &tree_list); |
725 | list_add(&rule->rlist, &tree->rules); |
726 | /* do not set rule->tree yet */ |
727 | mutex_unlock(&audit_filter_mutex); |
728 | |
729 | if (unlikely(!prune_thread)) { |
730 | err = audit_launch_prune(); |
731 | if (err) |
732 | goto Err; |
733 | } |
734 | |
735 | err = kern_path(tree->pathname, 0, &path); |
736 | if (err) |
737 | goto Err; |
738 | mnt = collect_mounts(&path); |
739 | path_put(&path); |
740 | if (IS_ERR(mnt)) { |
741 | err = PTR_ERR(mnt); |
742 | goto Err; |
743 | } |
744 | |
745 | get_tree(tree); |
746 | err = iterate_mounts(tag_mount, tree, mnt); |
747 | drop_collected_mounts(mnt); |
748 | |
749 | if (!err) { |
750 | struct node *node; |
751 | spin_lock(&hash_lock); |
752 | list_for_each_entry(node, &tree->chunks, list) |
753 | node->index &= ~(1U<<31); |
754 | spin_unlock(&hash_lock); |
755 | } else { |
756 | trim_marked(tree); |
757 | goto Err; |
758 | } |
759 | |
760 | mutex_lock(&audit_filter_mutex); |
761 | if (list_empty(&rule->rlist)) { |
762 | put_tree(tree); |
763 | return -ENOENT; |
764 | } |
765 | rule->tree = tree; |
766 | put_tree(tree); |
767 | |
768 | return 0; |
769 | Err: |
770 | mutex_lock(&audit_filter_mutex); |
771 | list_del_init(&tree->list); |
772 | list_del_init(&tree->rules); |
773 | put_tree(tree); |
774 | return err; |
775 | } |
776 | |
777 | int audit_tag_tree(char *old, char *new) |
778 | { |
779 | struct list_head cursor, barrier; |
780 | int failed = 0; |
781 | struct path path1, path2; |
782 | struct vfsmount *tagged; |
783 | int err; |
784 | |
785 | err = kern_path(new, 0, &path2); |
786 | if (err) |
787 | return err; |
788 | tagged = collect_mounts(&path2); |
789 | path_put(&path2); |
790 | if (IS_ERR(tagged)) |
791 | return PTR_ERR(tagged); |
792 | |
793 | err = kern_path(old, 0, &path1); |
794 | if (err) { |
795 | drop_collected_mounts(tagged); |
796 | return err; |
797 | } |
798 | |
799 | mutex_lock(&audit_filter_mutex); |
800 | list_add(&barrier, &tree_list); |
801 | list_add(&cursor, &barrier); |
802 | |
803 | while (cursor.next != &tree_list) { |
804 | struct audit_tree *tree; |
805 | int good_one = 0; |
806 | |
807 | tree = container_of(cursor.next, struct audit_tree, list); |
808 | get_tree(tree); |
809 | list_del(&cursor); |
810 | list_add(&cursor, &tree->list); |
811 | mutex_unlock(&audit_filter_mutex); |
812 | |
813 | err = kern_path(tree->pathname, 0, &path2); |
814 | if (!err) { |
815 | good_one = path_is_under(&path1, &path2); |
816 | path_put(&path2); |
817 | } |
818 | |
819 | if (!good_one) { |
820 | put_tree(tree); |
821 | mutex_lock(&audit_filter_mutex); |
822 | continue; |
823 | } |
824 | |
825 | failed = iterate_mounts(tag_mount, tree, tagged); |
826 | if (failed) { |
827 | put_tree(tree); |
828 | mutex_lock(&audit_filter_mutex); |
829 | break; |
830 | } |
831 | |
832 | mutex_lock(&audit_filter_mutex); |
833 | spin_lock(&hash_lock); |
834 | if (!tree->goner) { |
835 | list_del(&tree->list); |
836 | list_add(&tree->list, &tree_list); |
837 | } |
838 | spin_unlock(&hash_lock); |
839 | put_tree(tree); |
840 | } |
841 | |
842 | while (barrier.prev != &tree_list) { |
843 | struct audit_tree *tree; |
844 | |
845 | tree = container_of(barrier.prev, struct audit_tree, list); |
846 | get_tree(tree); |
847 | list_del(&tree->list); |
848 | list_add(&tree->list, &barrier); |
849 | mutex_unlock(&audit_filter_mutex); |
850 | |
851 | if (!failed) { |
852 | struct node *node; |
853 | spin_lock(&hash_lock); |
854 | list_for_each_entry(node, &tree->chunks, list) |
855 | node->index &= ~(1U<<31); |
856 | spin_unlock(&hash_lock); |
857 | } else { |
858 | trim_marked(tree); |
859 | } |
860 | |
861 | put_tree(tree); |
862 | mutex_lock(&audit_filter_mutex); |
863 | } |
864 | list_del(&barrier); |
865 | list_del(&cursor); |
866 | mutex_unlock(&audit_filter_mutex); |
867 | path_put(&path1); |
868 | drop_collected_mounts(tagged); |
869 | return failed; |
870 | } |
871 | |
872 | |
873 | static void audit_schedule_prune(void) |
874 | { |
875 | wake_up_process(prune_thread); |
876 | } |
877 | |
878 | /* |
879 | * ... and that one is done if evict_chunk() decides to delay until the end |
880 | * of syscall. Runs synchronously. |
881 | */ |
882 | void audit_kill_trees(struct list_head *list) |
883 | { |
884 | mutex_lock(&audit_cmd_mutex); |
885 | mutex_lock(&audit_filter_mutex); |
886 | |
887 | while (!list_empty(list)) { |
888 | struct audit_tree *victim; |
889 | |
890 | victim = list_entry(list->next, struct audit_tree, list); |
891 | kill_rules(victim); |
892 | list_del_init(&victim->list); |
893 | |
894 | mutex_unlock(&audit_filter_mutex); |
895 | |
896 | prune_one(victim); |
897 | |
898 | mutex_lock(&audit_filter_mutex); |
899 | } |
900 | |
901 | mutex_unlock(&audit_filter_mutex); |
902 | mutex_unlock(&audit_cmd_mutex); |
903 | } |
904 | |
905 | /* |
906 | * Here comes the stuff asynchronous to auditctl operations |
907 | */ |
908 | |
909 | static void evict_chunk(struct audit_chunk *chunk) |
910 | { |
911 | struct audit_tree *owner; |
912 | struct list_head *postponed = audit_killed_trees(); |
913 | int need_prune = 0; |
914 | int n; |
915 | |
916 | if (chunk->dead) |
917 | return; |
918 | |
919 | chunk->dead = 1; |
920 | mutex_lock(&audit_filter_mutex); |
921 | spin_lock(&hash_lock); |
922 | while (!list_empty(&chunk->trees)) { |
923 | owner = list_entry(chunk->trees.next, |
924 | struct audit_tree, same_root); |
925 | owner->goner = 1; |
926 | owner->root = NULL; |
927 | list_del_init(&owner->same_root); |
928 | spin_unlock(&hash_lock); |
929 | if (!postponed) { |
930 | kill_rules(owner); |
931 | list_move(&owner->list, &prune_list); |
932 | need_prune = 1; |
933 | } else { |
934 | list_move(&owner->list, postponed); |
935 | } |
936 | spin_lock(&hash_lock); |
937 | } |
938 | list_del_rcu(&chunk->hash); |
939 | for (n = 0; n < chunk->count; n++) |
940 | list_del_init(&chunk->owners[n].list); |
941 | spin_unlock(&hash_lock); |
942 | mutex_unlock(&audit_filter_mutex); |
943 | if (need_prune) |
944 | audit_schedule_prune(); |
945 | } |
946 | |
947 | static int audit_tree_handle_event(struct fsnotify_group *group, |
948 | struct inode *to_tell, |
949 | struct fsnotify_mark *inode_mark, |
950 | struct fsnotify_mark *vfsmount_mark, |
951 | u32 mask, void *data, int data_type, |
952 | const unsigned char *file_name, u32 cookie) |
953 | { |
954 | return 0; |
955 | } |
956 | |
957 | static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group) |
958 | { |
959 | struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark); |
960 | |
961 | evict_chunk(chunk); |
962 | |
963 | /* |
964 | * We are guaranteed to have at least one reference to the mark from |
965 | * either the inode or the caller of fsnotify_destroy_mark(). |
966 | */ |
967 | BUG_ON(atomic_read(&entry->refcnt) < 1); |
968 | } |
969 | |
970 | static const struct fsnotify_ops audit_tree_ops = { |
971 | .handle_event = audit_tree_handle_event, |
972 | .freeing_mark = audit_tree_freeing_mark, |
973 | }; |
974 | |
975 | static int __init audit_tree_init(void) |
976 | { |
977 | int i; |
978 | |
979 | audit_tree_group = fsnotify_alloc_group(&audit_tree_ops); |
980 | if (IS_ERR(audit_tree_group)) |
981 | audit_panic("cannot initialize fsnotify group for rectree watches"); |
982 | |
983 | for (i = 0; i < HASH_SIZE; i++) |
984 | INIT_LIST_HEAD(&chunk_hash_heads[i]); |
985 | |
986 | return 0; |
987 | } |
988 | __initcall(audit_tree_init); |
989 |