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1 | #include "audit.h" | |
2 | #include <linux/fsnotify_backend.h> | |
3 | #include <linux/namei.h> | |
4 | #include <linux/mount.h> | |
5 | #include <linux/kthread.h> | |
6 | #include <linux/slab.h> | |
7 | ||
8 | struct audit_tree; | |
9 | struct audit_chunk; | |
10 | ||
11 | struct audit_tree { | |
12 | atomic_t count; | |
13 | int goner; | |
14 | struct audit_chunk *root; | |
15 | struct list_head chunks; | |
16 | struct list_head rules; | |
17 | struct list_head list; | |
18 | struct list_head same_root; | |
19 | struct rcu_head head; | |
20 | char pathname[]; | |
21 | }; | |
22 | ||
23 | struct audit_chunk { | |
24 | struct list_head hash; | |
25 | struct fsnotify_mark mark; | |
26 | struct list_head trees; /* with root here */ | |
27 | int dead; | |
28 | int count; | |
29 | atomic_long_t refs; | |
30 | struct rcu_head head; | |
31 | struct node { | |
32 | struct list_head list; | |
33 | struct audit_tree *owner; | |
34 | unsigned index; /* index; upper bit indicates 'will prune' */ | |
35 | } owners[]; | |
36 | }; | |
37 | ||
38 | static LIST_HEAD(tree_list); | |
39 | static LIST_HEAD(prune_list); | |
40 | ||
41 | /* | |
42 | * One struct chunk is attached to each inode of interest. | |
43 | * We replace struct chunk on tagging/untagging. | |
44 | * Rules have pointer to struct audit_tree. | |
45 | * Rules have struct list_head rlist forming a list of rules over | |
46 | * the same tree. | |
47 | * References to struct chunk are collected at audit_inode{,_child}() | |
48 | * time and used in AUDIT_TREE rule matching. | |
49 | * These references are dropped at the same time we are calling | |
50 | * audit_free_names(), etc. | |
51 | * | |
52 | * Cyclic lists galore: | |
53 | * tree.chunks anchors chunk.owners[].list hash_lock | |
54 | * tree.rules anchors rule.rlist audit_filter_mutex | |
55 | * chunk.trees anchors tree.same_root hash_lock | |
56 | * chunk.hash is a hash with middle bits of watch.inode as | |
57 | * a hash function. RCU, hash_lock | |
58 | * | |
59 | * tree is refcounted; one reference for "some rules on rules_list refer to | |
60 | * it", one for each chunk with pointer to it. | |
61 | * | |
62 | * chunk is refcounted by embedded fsnotify_mark + .refs (non-zero refcount | |
63 | * of watch contributes 1 to .refs). | |
64 | * | |
65 | * node.index allows to get from node.list to containing chunk. | |
66 | * MSB of that sucker is stolen to mark taggings that we might have to | |
67 | * revert - several operations have very unpleasant cleanup logics and | |
68 | * that makes a difference. Some. | |
69 | */ | |
70 | ||
71 | static struct fsnotify_group *audit_tree_group; | |
72 | ||
73 | static struct audit_tree *alloc_tree(const char *s) | |
74 | { | |
75 | struct audit_tree *tree; | |
76 | ||
77 | tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL); | |
78 | if (tree) { | |
79 | atomic_set(&tree->count, 1); | |
80 | tree->goner = 0; | |
81 | INIT_LIST_HEAD(&tree->chunks); | |
82 | INIT_LIST_HEAD(&tree->rules); | |
83 | INIT_LIST_HEAD(&tree->list); | |
84 | INIT_LIST_HEAD(&tree->same_root); | |
85 | tree->root = NULL; | |
86 | strcpy(tree->pathname, s); | |
87 | } | |
88 | return tree; | |
89 | } | |
90 | ||
91 | static inline void get_tree(struct audit_tree *tree) | |
92 | { | |
93 | atomic_inc(&tree->count); | |
94 | } | |
95 | ||
96 | static inline void put_tree(struct audit_tree *tree) | |
97 | { | |
98 | if (atomic_dec_and_test(&tree->count)) | |
99 | kfree_rcu(tree, head); | |
100 | } | |
101 | ||
102 | /* to avoid bringing the entire thing in audit.h */ | |
103 | const char *audit_tree_path(struct audit_tree *tree) | |
104 | { | |
105 | return tree->pathname; | |
106 | } | |
107 | ||
108 | static void free_chunk(struct audit_chunk *chunk) | |
109 | { | |
110 | int i; | |
111 | ||
112 | for (i = 0; i < chunk->count; i++) { | |
113 | if (chunk->owners[i].owner) | |
114 | put_tree(chunk->owners[i].owner); | |
115 | } | |
116 | kfree(chunk); | |
117 | } | |
118 | ||
119 | void audit_put_chunk(struct audit_chunk *chunk) | |
120 | { | |
121 | if (atomic_long_dec_and_test(&chunk->refs)) | |
122 | free_chunk(chunk); | |
123 | } | |
124 | ||
125 | static void __put_chunk(struct rcu_head *rcu) | |
126 | { | |
127 | struct audit_chunk *chunk = container_of(rcu, struct audit_chunk, head); | |
128 | audit_put_chunk(chunk); | |
129 | } | |
130 | ||
131 | static void audit_tree_destroy_watch(struct fsnotify_mark *entry) | |
132 | { | |
133 | struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark); | |
134 | call_rcu(&chunk->head, __put_chunk); | |
135 | } | |
136 | ||
137 | static struct audit_chunk *alloc_chunk(int count) | |
138 | { | |
139 | struct audit_chunk *chunk; | |
140 | size_t size; | |
141 | int i; | |
142 | ||
143 | size = offsetof(struct audit_chunk, owners) + count * sizeof(struct node); | |
144 | chunk = kzalloc(size, GFP_KERNEL); | |
145 | if (!chunk) | |
146 | return NULL; | |
147 | ||
148 | INIT_LIST_HEAD(&chunk->hash); | |
149 | INIT_LIST_HEAD(&chunk->trees); | |
150 | chunk->count = count; | |
151 | atomic_long_set(&chunk->refs, 1); | |
152 | for (i = 0; i < count; i++) { | |
153 | INIT_LIST_HEAD(&chunk->owners[i].list); | |
154 | chunk->owners[i].index = i; | |
155 | } | |
156 | fsnotify_init_mark(&chunk->mark, audit_tree_destroy_watch); | |
157 | return chunk; | |
158 | } | |
159 | ||
160 | enum {HASH_SIZE = 128}; | |
161 | static struct list_head chunk_hash_heads[HASH_SIZE]; | |
162 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(hash_lock); | |
163 | ||
164 | static inline struct list_head *chunk_hash(const struct inode *inode) | |
165 | { | |
166 | unsigned long n = (unsigned long)inode / L1_CACHE_BYTES; | |
167 | return chunk_hash_heads + n % HASH_SIZE; | |
168 | } | |
169 | ||
170 | /* hash_lock & entry->lock is held by caller */ | |
171 | static void insert_hash(struct audit_chunk *chunk) | |
172 | { | |
173 | struct fsnotify_mark *entry = &chunk->mark; | |
174 | struct list_head *list; | |
175 | ||
176 | if (!entry->i.inode) | |
177 | return; | |
178 | list = chunk_hash(entry->i.inode); | |
179 | list_add_rcu(&chunk->hash, list); | |
180 | } | |
181 | ||
182 | /* called under rcu_read_lock */ | |
183 | struct audit_chunk *audit_tree_lookup(const struct inode *inode) | |
184 | { | |
185 | struct list_head *list = chunk_hash(inode); | |
186 | struct audit_chunk *p; | |
187 | ||
188 | list_for_each_entry_rcu(p, list, hash) { | |
189 | /* mark.inode may have gone NULL, but who cares? */ | |
190 | if (p->mark.i.inode == inode) { | |
191 | atomic_long_inc(&p->refs); | |
192 | return p; | |
193 | } | |
194 | } | |
195 | return NULL; | |
196 | } | |
197 | ||
198 | int audit_tree_match(struct audit_chunk *chunk, struct audit_tree *tree) | |
199 | { | |
200 | int n; | |
201 | for (n = 0; n < chunk->count; n++) | |
202 | if (chunk->owners[n].owner == tree) | |
203 | return 1; | |
204 | return 0; | |
205 | } | |
206 | ||
207 | /* tagging and untagging inodes with trees */ | |
208 | ||
209 | static struct audit_chunk *find_chunk(struct node *p) | |
210 | { | |
211 | int index = p->index & ~(1U<<31); | |
212 | p -= index; | |
213 | return container_of(p, struct audit_chunk, owners[0]); | |
214 | } | |
215 | ||
216 | static void untag_chunk(struct node *p) | |
217 | { | |
218 | struct audit_chunk *chunk = find_chunk(p); | |
219 | struct fsnotify_mark *entry = &chunk->mark; | |
220 | struct audit_chunk *new = NULL; | |
221 | struct audit_tree *owner; | |
222 | int size = chunk->count - 1; | |
223 | int i, j; | |
224 | ||
225 | fsnotify_get_mark(entry); | |
226 | ||
227 | spin_unlock(&hash_lock); | |
228 | ||
229 | if (size) | |
230 | new = alloc_chunk(size); | |
231 | ||
232 | spin_lock(&entry->lock); | |
233 | if (chunk->dead || !entry->i.inode) { | |
234 | spin_unlock(&entry->lock); | |
235 | if (new) | |
236 | free_chunk(new); | |
237 | goto out; | |
238 | } | |
239 | ||
240 | owner = p->owner; | |
241 | ||
242 | if (!size) { | |
243 | chunk->dead = 1; | |
244 | spin_lock(&hash_lock); | |
245 | list_del_init(&chunk->trees); | |
246 | if (owner->root == chunk) | |
247 | owner->root = NULL; | |
248 | list_del_init(&p->list); | |
249 | list_del_rcu(&chunk->hash); | |
250 | spin_unlock(&hash_lock); | |
251 | spin_unlock(&entry->lock); | |
252 | fsnotify_destroy_mark(entry, audit_tree_group); | |
253 | goto out; | |
254 | } | |
255 | ||
256 | if (!new) | |
257 | goto Fallback; | |
258 | ||
259 | fsnotify_duplicate_mark(&new->mark, entry); | |
260 | if (fsnotify_add_mark(&new->mark, new->mark.group, new->mark.i.inode, NULL, 1)) { | |
261 | fsnotify_put_mark(&new->mark); | |
262 | goto Fallback; | |
263 | } | |
264 | ||
265 | chunk->dead = 1; | |
266 | spin_lock(&hash_lock); | |
267 | list_replace_init(&chunk->trees, &new->trees); | |
268 | if (owner->root == chunk) { | |
269 | list_del_init(&owner->same_root); | |
270 | owner->root = NULL; | |
271 | } | |
272 | ||
273 | for (i = j = 0; j <= size; i++, j++) { | |
274 | struct audit_tree *s; | |
275 | if (&chunk->owners[j] == p) { | |
276 | list_del_init(&p->list); | |
277 | i--; | |
278 | continue; | |
279 | } | |
280 | s = chunk->owners[j].owner; | |
281 | new->owners[i].owner = s; | |
282 | new->owners[i].index = chunk->owners[j].index - j + i; | |
283 | if (!s) /* result of earlier fallback */ | |
284 | continue; | |
285 | get_tree(s); | |
286 | list_replace_init(&chunk->owners[j].list, &new->owners[i].list); | |
287 | } | |
288 | ||
289 | list_replace_rcu(&chunk->hash, &new->hash); | |
290 | list_for_each_entry(owner, &new->trees, same_root) | |
291 | owner->root = new; | |
292 | spin_unlock(&hash_lock); | |
293 | spin_unlock(&entry->lock); | |
294 | fsnotify_destroy_mark(entry, audit_tree_group); | |
295 | fsnotify_put_mark(&new->mark); /* drop initial reference */ | |
296 | goto out; | |
297 | ||
298 | Fallback: | |
299 | // do the best we can | |
300 | spin_lock(&hash_lock); | |
301 | if (owner->root == chunk) { | |
302 | list_del_init(&owner->same_root); | |
303 | owner->root = NULL; | |
304 | } | |
305 | list_del_init(&p->list); | |
306 | p->owner = NULL; | |
307 | put_tree(owner); | |
308 | spin_unlock(&hash_lock); | |
309 | spin_unlock(&entry->lock); | |
310 | out: | |
311 | fsnotify_put_mark(entry); | |
312 | spin_lock(&hash_lock); | |
313 | } | |
314 | ||
315 | static int create_chunk(struct inode *inode, struct audit_tree *tree) | |
316 | { | |
317 | struct fsnotify_mark *entry; | |
318 | struct audit_chunk *chunk = alloc_chunk(1); | |
319 | if (!chunk) | |
320 | return -ENOMEM; | |
321 | ||
322 | entry = &chunk->mark; | |
323 | if (fsnotify_add_mark(entry, audit_tree_group, inode, NULL, 0)) { | |
324 | fsnotify_put_mark(entry); | |
325 | return -ENOSPC; | |
326 | } | |
327 | ||
328 | spin_lock(&entry->lock); | |
329 | spin_lock(&hash_lock); | |
330 | if (tree->goner) { | |
331 | spin_unlock(&hash_lock); | |
332 | chunk->dead = 1; | |
333 | spin_unlock(&entry->lock); | |
334 | fsnotify_destroy_mark(entry, audit_tree_group); | |
335 | fsnotify_put_mark(entry); | |
336 | return 0; | |
337 | } | |
338 | chunk->owners[0].index = (1U << 31); | |
339 | chunk->owners[0].owner = tree; | |
340 | get_tree(tree); | |
341 | list_add(&chunk->owners[0].list, &tree->chunks); | |
342 | if (!tree->root) { | |
343 | tree->root = chunk; | |
344 | list_add(&tree->same_root, &chunk->trees); | |
345 | } | |
346 | insert_hash(chunk); | |
347 | spin_unlock(&hash_lock); | |
348 | spin_unlock(&entry->lock); | |
349 | fsnotify_put_mark(entry); /* drop initial reference */ | |
350 | return 0; | |
351 | } | |
352 | ||
353 | /* the first tagged inode becomes root of tree */ | |
354 | static int tag_chunk(struct inode *inode, struct audit_tree *tree) | |
355 | { | |
356 | struct fsnotify_mark *old_entry, *chunk_entry; | |
357 | struct audit_tree *owner; | |
358 | struct audit_chunk *chunk, *old; | |
359 | struct node *p; | |
360 | int n; | |
361 | ||
362 | old_entry = fsnotify_find_inode_mark(audit_tree_group, inode); | |
363 | if (!old_entry) | |
364 | return create_chunk(inode, tree); | |
365 | ||
366 | old = container_of(old_entry, struct audit_chunk, mark); | |
367 | ||
368 | /* are we already there? */ | |
369 | spin_lock(&hash_lock); | |
370 | for (n = 0; n < old->count; n++) { | |
371 | if (old->owners[n].owner == tree) { | |
372 | spin_unlock(&hash_lock); | |
373 | fsnotify_put_mark(old_entry); | |
374 | return 0; | |
375 | } | |
376 | } | |
377 | spin_unlock(&hash_lock); | |
378 | ||
379 | chunk = alloc_chunk(old->count + 1); | |
380 | if (!chunk) { | |
381 | fsnotify_put_mark(old_entry); | |
382 | return -ENOMEM; | |
383 | } | |
384 | ||
385 | chunk_entry = &chunk->mark; | |
386 | ||
387 | spin_lock(&old_entry->lock); | |
388 | if (!old_entry->i.inode) { | |
389 | /* old_entry is being shot, lets just lie */ | |
390 | spin_unlock(&old_entry->lock); | |
391 | fsnotify_put_mark(old_entry); | |
392 | free_chunk(chunk); | |
393 | return -ENOENT; | |
394 | } | |
395 | ||
396 | fsnotify_duplicate_mark(chunk_entry, old_entry); | |
397 | if (fsnotify_add_mark(chunk_entry, chunk_entry->group, chunk_entry->i.inode, NULL, 1)) { | |
398 | spin_unlock(&old_entry->lock); | |
399 | fsnotify_put_mark(chunk_entry); | |
400 | fsnotify_put_mark(old_entry); | |
401 | return -ENOSPC; | |
402 | } | |
403 | ||
404 | /* even though we hold old_entry->lock, this is safe since chunk_entry->lock could NEVER have been grabbed before */ | |
405 | spin_lock(&chunk_entry->lock); | |
406 | spin_lock(&hash_lock); | |
407 | ||
408 | /* we now hold old_entry->lock, chunk_entry->lock, and hash_lock */ | |
409 | if (tree->goner) { | |
410 | spin_unlock(&hash_lock); | |
411 | chunk->dead = 1; | |
412 | spin_unlock(&chunk_entry->lock); | |
413 | spin_unlock(&old_entry->lock); | |
414 | ||
415 | fsnotify_destroy_mark(chunk_entry, audit_tree_group); | |
416 | ||
417 | fsnotify_put_mark(chunk_entry); | |
418 | fsnotify_put_mark(old_entry); | |
419 | return 0; | |
420 | } | |
421 | list_replace_init(&old->trees, &chunk->trees); | |
422 | for (n = 0, p = chunk->owners; n < old->count; n++, p++) { | |
423 | struct audit_tree *s = old->owners[n].owner; | |
424 | p->owner = s; | |
425 | p->index = old->owners[n].index; | |
426 | if (!s) /* result of fallback in untag */ | |
427 | continue; | |
428 | get_tree(s); | |
429 | list_replace_init(&old->owners[n].list, &p->list); | |
430 | } | |
431 | p->index = (chunk->count - 1) | (1U<<31); | |
432 | p->owner = tree; | |
433 | get_tree(tree); | |
434 | list_add(&p->list, &tree->chunks); | |
435 | list_replace_rcu(&old->hash, &chunk->hash); | |
436 | list_for_each_entry(owner, &chunk->trees, same_root) | |
437 | owner->root = chunk; | |
438 | old->dead = 1; | |
439 | if (!tree->root) { | |
440 | tree->root = chunk; | |
441 | list_add(&tree->same_root, &chunk->trees); | |
442 | } | |
443 | spin_unlock(&hash_lock); | |
444 | spin_unlock(&chunk_entry->lock); | |
445 | spin_unlock(&old_entry->lock); | |
446 | fsnotify_destroy_mark(old_entry, audit_tree_group); | |
447 | fsnotify_put_mark(chunk_entry); /* drop initial reference */ | |
448 | fsnotify_put_mark(old_entry); /* pair to fsnotify_find mark_entry */ | |
449 | return 0; | |
450 | } | |
451 | ||
452 | static void kill_rules(struct audit_tree *tree) | |
453 | { | |
454 | struct audit_krule *rule, *next; | |
455 | struct audit_entry *entry; | |
456 | struct audit_buffer *ab; | |
457 | ||
458 | list_for_each_entry_safe(rule, next, &tree->rules, rlist) { | |
459 | entry = container_of(rule, struct audit_entry, rule); | |
460 | ||
461 | list_del_init(&rule->rlist); | |
462 | if (rule->tree) { | |
463 | /* not a half-baked one */ | |
464 | ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE); | |
465 | audit_log_format(ab, "op="); | |
466 | audit_log_string(ab, "remove rule"); | |
467 | audit_log_format(ab, " dir="); | |
468 | audit_log_untrustedstring(ab, rule->tree->pathname); | |
469 | audit_log_key(ab, rule->filterkey); | |
470 | audit_log_format(ab, " list=%d res=1", rule->listnr); | |
471 | audit_log_end(ab); | |
472 | rule->tree = NULL; | |
473 | list_del_rcu(&entry->list); | |
474 | list_del(&entry->rule.list); | |
475 | call_rcu(&entry->rcu, audit_free_rule_rcu); | |
476 | } | |
477 | } | |
478 | } | |
479 | ||
480 | /* | |
481 | * finish killing struct audit_tree | |
482 | */ | |
483 | static void prune_one(struct audit_tree *victim) | |
484 | { | |
485 | spin_lock(&hash_lock); | |
486 | while (!list_empty(&victim->chunks)) { | |
487 | struct node *p; | |
488 | ||
489 | p = list_entry(victim->chunks.next, struct node, list); | |
490 | ||
491 | untag_chunk(p); | |
492 | } | |
493 | spin_unlock(&hash_lock); | |
494 | put_tree(victim); | |
495 | } | |
496 | ||
497 | /* trim the uncommitted chunks from tree */ | |
498 | ||
499 | static void trim_marked(struct audit_tree *tree) | |
500 | { | |
501 | struct list_head *p, *q; | |
502 | spin_lock(&hash_lock); | |
503 | if (tree->goner) { | |
504 | spin_unlock(&hash_lock); | |
505 | return; | |
506 | } | |
507 | /* reorder */ | |
508 | for (p = tree->chunks.next; p != &tree->chunks; p = q) { | |
509 | struct node *node = list_entry(p, struct node, list); | |
510 | q = p->next; | |
511 | if (node->index & (1U<<31)) { | |
512 | list_del_init(p); | |
513 | list_add(p, &tree->chunks); | |
514 | } | |
515 | } | |
516 | ||
517 | while (!list_empty(&tree->chunks)) { | |
518 | struct node *node; | |
519 | ||
520 | node = list_entry(tree->chunks.next, struct node, list); | |
521 | ||
522 | /* have we run out of marked? */ | |
523 | if (!(node->index & (1U<<31))) | |
524 | break; | |
525 | ||
526 | untag_chunk(node); | |
527 | } | |
528 | if (!tree->root && !tree->goner) { | |
529 | tree->goner = 1; | |
530 | spin_unlock(&hash_lock); | |
531 | mutex_lock(&audit_filter_mutex); | |
532 | kill_rules(tree); | |
533 | list_del_init(&tree->list); | |
534 | mutex_unlock(&audit_filter_mutex); | |
535 | prune_one(tree); | |
536 | } else { | |
537 | spin_unlock(&hash_lock); | |
538 | } | |
539 | } | |
540 | ||
541 | static void audit_schedule_prune(void); | |
542 | ||
543 | /* called with audit_filter_mutex */ | |
544 | int audit_remove_tree_rule(struct audit_krule *rule) | |
545 | { | |
546 | struct audit_tree *tree; | |
547 | tree = rule->tree; | |
548 | if (tree) { | |
549 | spin_lock(&hash_lock); | |
550 | list_del_init(&rule->rlist); | |
551 | if (list_empty(&tree->rules) && !tree->goner) { | |
552 | tree->root = NULL; | |
553 | list_del_init(&tree->same_root); | |
554 | tree->goner = 1; | |
555 | list_move(&tree->list, &prune_list); | |
556 | rule->tree = NULL; | |
557 | spin_unlock(&hash_lock); | |
558 | audit_schedule_prune(); | |
559 | return 1; | |
560 | } | |
561 | rule->tree = NULL; | |
562 | spin_unlock(&hash_lock); | |
563 | return 1; | |
564 | } | |
565 | return 0; | |
566 | } | |
567 | ||
568 | static int compare_root(struct vfsmount *mnt, void *arg) | |
569 | { | |
570 | return mnt->mnt_root->d_inode == arg; | |
571 | } | |
572 | ||
573 | void audit_trim_trees(void) | |
574 | { | |
575 | struct list_head cursor; | |
576 | ||
577 | mutex_lock(&audit_filter_mutex); | |
578 | list_add(&cursor, &tree_list); | |
579 | while (cursor.next != &tree_list) { | |
580 | struct audit_tree *tree; | |
581 | struct path path; | |
582 | struct vfsmount *root_mnt; | |
583 | struct node *node; | |
584 | int err; | |
585 | ||
586 | tree = container_of(cursor.next, struct audit_tree, list); | |
587 | get_tree(tree); | |
588 | list_del(&cursor); | |
589 | list_add(&cursor, &tree->list); | |
590 | mutex_unlock(&audit_filter_mutex); | |
591 | ||
592 | err = kern_path(tree->pathname, 0, &path); | |
593 | if (err) | |
594 | goto skip_it; | |
595 | ||
596 | root_mnt = collect_mounts(&path); | |
597 | path_put(&path); | |
598 | if (IS_ERR(root_mnt)) | |
599 | goto skip_it; | |
600 | ||
601 | spin_lock(&hash_lock); | |
602 | list_for_each_entry(node, &tree->chunks, list) { | |
603 | struct audit_chunk *chunk = find_chunk(node); | |
604 | /* this could be NULL if the watch is dying else where... */ | |
605 | struct inode *inode = chunk->mark.i.inode; | |
606 | node->index |= 1U<<31; | |
607 | if (iterate_mounts(compare_root, inode, root_mnt)) | |
608 | node->index &= ~(1U<<31); | |
609 | } | |
610 | spin_unlock(&hash_lock); | |
611 | trim_marked(tree); | |
612 | put_tree(tree); | |
613 | drop_collected_mounts(root_mnt); | |
614 | skip_it: | |
615 | mutex_lock(&audit_filter_mutex); | |
616 | } | |
617 | list_del(&cursor); | |
618 | mutex_unlock(&audit_filter_mutex); | |
619 | } | |
620 | ||
621 | int audit_make_tree(struct audit_krule *rule, char *pathname, u32 op) | |
622 | { | |
623 | ||
624 | if (pathname[0] != '/' || | |
625 | rule->listnr != AUDIT_FILTER_EXIT || | |
626 | op != Audit_equal || | |
627 | rule->inode_f || rule->watch || rule->tree) | |
628 | return -EINVAL; | |
629 | rule->tree = alloc_tree(pathname); | |
630 | if (!rule->tree) | |
631 | return -ENOMEM; | |
632 | return 0; | |
633 | } | |
634 | ||
635 | void audit_put_tree(struct audit_tree *tree) | |
636 | { | |
637 | put_tree(tree); | |
638 | } | |
639 | ||
640 | static int tag_mount(struct vfsmount *mnt, void *arg) | |
641 | { | |
642 | return tag_chunk(mnt->mnt_root->d_inode, arg); | |
643 | } | |
644 | ||
645 | /* called with audit_filter_mutex */ | |
646 | int audit_add_tree_rule(struct audit_krule *rule) | |
647 | { | |
648 | struct audit_tree *seed = rule->tree, *tree; | |
649 | struct path path; | |
650 | struct vfsmount *mnt; | |
651 | int err; | |
652 | ||
653 | list_for_each_entry(tree, &tree_list, list) { | |
654 | if (!strcmp(seed->pathname, tree->pathname)) { | |
655 | put_tree(seed); | |
656 | rule->tree = tree; | |
657 | list_add(&rule->rlist, &tree->rules); | |
658 | return 0; | |
659 | } | |
660 | } | |
661 | tree = seed; | |
662 | list_add(&tree->list, &tree_list); | |
663 | list_add(&rule->rlist, &tree->rules); | |
664 | /* do not set rule->tree yet */ | |
665 | mutex_unlock(&audit_filter_mutex); | |
666 | ||
667 | err = kern_path(tree->pathname, 0, &path); | |
668 | if (err) | |
669 | goto Err; | |
670 | mnt = collect_mounts(&path); | |
671 | path_put(&path); | |
672 | if (IS_ERR(mnt)) { | |
673 | err = PTR_ERR(mnt); | |
674 | goto Err; | |
675 | } | |
676 | ||
677 | get_tree(tree); | |
678 | err = iterate_mounts(tag_mount, tree, mnt); | |
679 | drop_collected_mounts(mnt); | |
680 | ||
681 | if (!err) { | |
682 | struct node *node; | |
683 | spin_lock(&hash_lock); | |
684 | list_for_each_entry(node, &tree->chunks, list) | |
685 | node->index &= ~(1U<<31); | |
686 | spin_unlock(&hash_lock); | |
687 | } else { | |
688 | trim_marked(tree); | |
689 | goto Err; | |
690 | } | |
691 | ||
692 | mutex_lock(&audit_filter_mutex); | |
693 | if (list_empty(&rule->rlist)) { | |
694 | put_tree(tree); | |
695 | return -ENOENT; | |
696 | } | |
697 | rule->tree = tree; | |
698 | put_tree(tree); | |
699 | ||
700 | return 0; | |
701 | Err: | |
702 | mutex_lock(&audit_filter_mutex); | |
703 | list_del_init(&tree->list); | |
704 | list_del_init(&tree->rules); | |
705 | put_tree(tree); | |
706 | return err; | |
707 | } | |
708 | ||
709 | int audit_tag_tree(char *old, char *new) | |
710 | { | |
711 | struct list_head cursor, barrier; | |
712 | int failed = 0; | |
713 | struct path path1, path2; | |
714 | struct vfsmount *tagged; | |
715 | int err; | |
716 | ||
717 | err = kern_path(new, 0, &path2); | |
718 | if (err) | |
719 | return err; | |
720 | tagged = collect_mounts(&path2); | |
721 | path_put(&path2); | |
722 | if (IS_ERR(tagged)) | |
723 | return PTR_ERR(tagged); | |
724 | ||
725 | err = kern_path(old, 0, &path1); | |
726 | if (err) { | |
727 | drop_collected_mounts(tagged); | |
728 | return err; | |
729 | } | |
730 | ||
731 | mutex_lock(&audit_filter_mutex); | |
732 | list_add(&barrier, &tree_list); | |
733 | list_add(&cursor, &barrier); | |
734 | ||
735 | while (cursor.next != &tree_list) { | |
736 | struct audit_tree *tree; | |
737 | int good_one = 0; | |
738 | ||
739 | tree = container_of(cursor.next, struct audit_tree, list); | |
740 | get_tree(tree); | |
741 | list_del(&cursor); | |
742 | list_add(&cursor, &tree->list); | |
743 | mutex_unlock(&audit_filter_mutex); | |
744 | ||
745 | err = kern_path(tree->pathname, 0, &path2); | |
746 | if (!err) { | |
747 | good_one = path_is_under(&path1, &path2); | |
748 | path_put(&path2); | |
749 | } | |
750 | ||
751 | if (!good_one) { | |
752 | put_tree(tree); | |
753 | mutex_lock(&audit_filter_mutex); | |
754 | continue; | |
755 | } | |
756 | ||
757 | failed = iterate_mounts(tag_mount, tree, tagged); | |
758 | if (failed) { | |
759 | put_tree(tree); | |
760 | mutex_lock(&audit_filter_mutex); | |
761 | break; | |
762 | } | |
763 | ||
764 | mutex_lock(&audit_filter_mutex); | |
765 | spin_lock(&hash_lock); | |
766 | if (!tree->goner) { | |
767 | list_del(&tree->list); | |
768 | list_add(&tree->list, &tree_list); | |
769 | } | |
770 | spin_unlock(&hash_lock); | |
771 | put_tree(tree); | |
772 | } | |
773 | ||
774 | while (barrier.prev != &tree_list) { | |
775 | struct audit_tree *tree; | |
776 | ||
777 | tree = container_of(barrier.prev, struct audit_tree, list); | |
778 | get_tree(tree); | |
779 | list_del(&tree->list); | |
780 | list_add(&tree->list, &barrier); | |
781 | mutex_unlock(&audit_filter_mutex); | |
782 | ||
783 | if (!failed) { | |
784 | struct node *node; | |
785 | spin_lock(&hash_lock); | |
786 | list_for_each_entry(node, &tree->chunks, list) | |
787 | node->index &= ~(1U<<31); | |
788 | spin_unlock(&hash_lock); | |
789 | } else { | |
790 | trim_marked(tree); | |
791 | } | |
792 | ||
793 | put_tree(tree); | |
794 | mutex_lock(&audit_filter_mutex); | |
795 | } | |
796 | list_del(&barrier); | |
797 | list_del(&cursor); | |
798 | mutex_unlock(&audit_filter_mutex); | |
799 | path_put(&path1); | |
800 | drop_collected_mounts(tagged); | |
801 | return failed; | |
802 | } | |
803 | ||
804 | /* | |
805 | * That gets run when evict_chunk() ends up needing to kill audit_tree. | |
806 | * Runs from a separate thread. | |
807 | */ | |
808 | static int prune_tree_thread(void *unused) | |
809 | { | |
810 | mutex_lock(&audit_cmd_mutex); | |
811 | mutex_lock(&audit_filter_mutex); | |
812 | ||
813 | while (!list_empty(&prune_list)) { | |
814 | struct audit_tree *victim; | |
815 | ||
816 | victim = list_entry(prune_list.next, struct audit_tree, list); | |
817 | list_del_init(&victim->list); | |
818 | ||
819 | mutex_unlock(&audit_filter_mutex); | |
820 | ||
821 | prune_one(victim); | |
822 | ||
823 | mutex_lock(&audit_filter_mutex); | |
824 | } | |
825 | ||
826 | mutex_unlock(&audit_filter_mutex); | |
827 | mutex_unlock(&audit_cmd_mutex); | |
828 | return 0; | |
829 | } | |
830 | ||
831 | static void audit_schedule_prune(void) | |
832 | { | |
833 | kthread_run(prune_tree_thread, NULL, "audit_prune_tree"); | |
834 | } | |
835 | ||
836 | /* | |
837 | * ... and that one is done if evict_chunk() decides to delay until the end | |
838 | * of syscall. Runs synchronously. | |
839 | */ | |
840 | void audit_kill_trees(struct list_head *list) | |
841 | { | |
842 | mutex_lock(&audit_cmd_mutex); | |
843 | mutex_lock(&audit_filter_mutex); | |
844 | ||
845 | while (!list_empty(list)) { | |
846 | struct audit_tree *victim; | |
847 | ||
848 | victim = list_entry(list->next, struct audit_tree, list); | |
849 | kill_rules(victim); | |
850 | list_del_init(&victim->list); | |
851 | ||
852 | mutex_unlock(&audit_filter_mutex); | |
853 | ||
854 | prune_one(victim); | |
855 | ||
856 | mutex_lock(&audit_filter_mutex); | |
857 | } | |
858 | ||
859 | mutex_unlock(&audit_filter_mutex); | |
860 | mutex_unlock(&audit_cmd_mutex); | |
861 | } | |
862 | ||
863 | /* | |
864 | * Here comes the stuff asynchronous to auditctl operations | |
865 | */ | |
866 | ||
867 | static void evict_chunk(struct audit_chunk *chunk) | |
868 | { | |
869 | struct audit_tree *owner; | |
870 | struct list_head *postponed = audit_killed_trees(); | |
871 | int need_prune = 0; | |
872 | int n; | |
873 | ||
874 | if (chunk->dead) | |
875 | return; | |
876 | ||
877 | chunk->dead = 1; | |
878 | mutex_lock(&audit_filter_mutex); | |
879 | spin_lock(&hash_lock); | |
880 | while (!list_empty(&chunk->trees)) { | |
881 | owner = list_entry(chunk->trees.next, | |
882 | struct audit_tree, same_root); | |
883 | owner->goner = 1; | |
884 | owner->root = NULL; | |
885 | list_del_init(&owner->same_root); | |
886 | spin_unlock(&hash_lock); | |
887 | if (!postponed) { | |
888 | kill_rules(owner); | |
889 | list_move(&owner->list, &prune_list); | |
890 | need_prune = 1; | |
891 | } else { | |
892 | list_move(&owner->list, postponed); | |
893 | } | |
894 | spin_lock(&hash_lock); | |
895 | } | |
896 | list_del_rcu(&chunk->hash); | |
897 | for (n = 0; n < chunk->count; n++) | |
898 | list_del_init(&chunk->owners[n].list); | |
899 | spin_unlock(&hash_lock); | |
900 | if (need_prune) | |
901 | audit_schedule_prune(); | |
902 | mutex_unlock(&audit_filter_mutex); | |
903 | } | |
904 | ||
905 | static int audit_tree_handle_event(struct fsnotify_group *group, | |
906 | struct fsnotify_mark *inode_mark, | |
907 | struct fsnotify_mark *vfsmonut_mark, | |
908 | struct fsnotify_event *event) | |
909 | { | |
910 | BUG(); | |
911 | return -EOPNOTSUPP; | |
912 | } | |
913 | ||
914 | static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify_group *group) | |
915 | { | |
916 | struct audit_chunk *chunk = container_of(entry, struct audit_chunk, mark); | |
917 | ||
918 | evict_chunk(chunk); | |
919 | ||
920 | /* | |
921 | * We are guaranteed to have at least one reference to the mark from | |
922 | * either the inode or the caller of fsnotify_destroy_mark(). | |
923 | */ | |
924 | BUG_ON(atomic_read(&entry->refcnt) < 1); | |
925 | } | |
926 | ||
927 | static bool audit_tree_send_event(struct fsnotify_group *group, struct inode *inode, | |
928 | struct fsnotify_mark *inode_mark, | |
929 | struct fsnotify_mark *vfsmount_mark, | |
930 | __u32 mask, void *data, int data_type) | |
931 | { | |
932 | return false; | |
933 | } | |
934 | ||
935 | static const struct fsnotify_ops audit_tree_ops = { | |
936 | .handle_event = audit_tree_handle_event, | |
937 | .should_send_event = audit_tree_send_event, | |
938 | .free_group_priv = NULL, | |
939 | .free_event_priv = NULL, | |
940 | .freeing_mark = audit_tree_freeing_mark, | |
941 | }; | |
942 | ||
943 | static int __init audit_tree_init(void) | |
944 | { | |
945 | int i; | |
946 | ||
947 | audit_tree_group = fsnotify_alloc_group(&audit_tree_ops); | |
948 | if (IS_ERR(audit_tree_group)) | |
949 | audit_panic("cannot initialize fsnotify group for rectree watches"); | |
950 | ||
951 | for (i = 0; i < HASH_SIZE; i++) | |
952 | INIT_LIST_HEAD(&chunk_hash_heads[i]); | |
953 | ||
954 | return 0; | |
955 | } | |
956 | __initcall(audit_tree_init); |