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1 | /* audit_watch.c -- watching inodes |
2 | * |
3 | * Copyright 2003-2009 Red Hat, Inc. |
4 | * Copyright 2005 Hewlett-Packard Development Company, L.P. |
5 | * Copyright 2005 IBM Corporation |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify |
8 | * it under the terms of the GNU General Public License as published by |
9 | * the Free Software Foundation; either version 2 of the License, or |
10 | * (at your option) any later version. |
11 | * |
12 | * This program is distributed in the hope that it will be useful, |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
15 | * GNU General Public License for more details. |
16 | * |
17 | * You should have received a copy of the GNU General Public License |
18 | * along with this program; if not, write to the Free Software |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
20 | */ |
21 | |
22 | #include <linux/kernel.h> |
23 | #include <linux/audit.h> |
24 | #include <linux/kthread.h> |
25 | #include <linux/mutex.h> |
26 | #include <linux/fs.h> |
27 | #include <linux/fsnotify_backend.h> |
28 | #include <linux/namei.h> |
29 | #include <linux/netlink.h> |
30 | #include <linux/sched.h> |
31 | #include <linux/slab.h> |
32 | #include <linux/security.h> |
33 | #include "audit.h" |
34 | |
35 | /* |
36 | * Reference counting: |
37 | * |
38 | * audit_parent: lifetime is from audit_init_parent() to receipt of an FS_IGNORED |
39 | * event. Each audit_watch holds a reference to its associated parent. |
40 | * |
41 | * audit_watch: if added to lists, lifetime is from audit_init_watch() to |
42 | * audit_remove_watch(). Additionally, an audit_watch may exist |
43 | * temporarily to assist in searching existing filter data. Each |
44 | * audit_krule holds a reference to its associated watch. |
45 | */ |
46 | |
47 | struct audit_watch { |
48 | atomic_t count; /* reference count */ |
49 | dev_t dev; /* associated superblock device */ |
50 | char *path; /* insertion path */ |
51 | unsigned long ino; /* associated inode number */ |
52 | struct audit_parent *parent; /* associated parent */ |
53 | struct list_head wlist; /* entry in parent->watches list */ |
54 | struct list_head rules; /* anchor for krule->rlist */ |
55 | }; |
56 | |
57 | struct audit_parent { |
58 | struct list_head watches; /* anchor for audit_watch->wlist */ |
59 | struct fsnotify_mark mark; /* fsnotify mark on the inode */ |
60 | }; |
61 | |
62 | /* fsnotify handle. */ |
63 | static struct fsnotify_group *audit_watch_group; |
64 | |
65 | /* fsnotify events we care about. */ |
66 | #define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\ |
67 | FS_MOVE_SELF | FS_EVENT_ON_CHILD) |
68 | |
69 | static void audit_free_parent(struct audit_parent *parent) |
70 | { |
71 | WARN_ON(!list_empty(&parent->watches)); |
72 | kfree(parent); |
73 | } |
74 | |
75 | static void audit_watch_free_mark(struct fsnotify_mark *entry) |
76 | { |
77 | struct audit_parent *parent; |
78 | |
79 | parent = container_of(entry, struct audit_parent, mark); |
80 | audit_free_parent(parent); |
81 | } |
82 | |
83 | static void audit_get_parent(struct audit_parent *parent) |
84 | { |
85 | if (likely(parent)) |
86 | fsnotify_get_mark(&parent->mark); |
87 | } |
88 | |
89 | static void audit_put_parent(struct audit_parent *parent) |
90 | { |
91 | if (likely(parent)) |
92 | fsnotify_put_mark(&parent->mark); |
93 | } |
94 | |
95 | /* |
96 | * Find and return the audit_parent on the given inode. If found a reference |
97 | * is taken on this parent. |
98 | */ |
99 | static inline struct audit_parent *audit_find_parent(struct inode *inode) |
100 | { |
101 | struct audit_parent *parent = NULL; |
102 | struct fsnotify_mark *entry; |
103 | |
104 | entry = fsnotify_find_inode_mark(audit_watch_group, inode); |
105 | if (entry) |
106 | parent = container_of(entry, struct audit_parent, mark); |
107 | |
108 | return parent; |
109 | } |
110 | |
111 | void audit_get_watch(struct audit_watch *watch) |
112 | { |
113 | atomic_inc(&watch->count); |
114 | } |
115 | |
116 | void audit_put_watch(struct audit_watch *watch) |
117 | { |
118 | if (atomic_dec_and_test(&watch->count)) { |
119 | WARN_ON(watch->parent); |
120 | WARN_ON(!list_empty(&watch->rules)); |
121 | kfree(watch->path); |
122 | kfree(watch); |
123 | } |
124 | } |
125 | |
126 | static void audit_remove_watch(struct audit_watch *watch) |
127 | { |
128 | list_del(&watch->wlist); |
129 | audit_put_parent(watch->parent); |
130 | watch->parent = NULL; |
131 | audit_put_watch(watch); /* match initial get */ |
132 | } |
133 | |
134 | char *audit_watch_path(struct audit_watch *watch) |
135 | { |
136 | return watch->path; |
137 | } |
138 | |
139 | int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev) |
140 | { |
141 | return (watch->ino != (unsigned long)-1) && |
142 | (watch->ino == ino) && |
143 | (watch->dev == dev); |
144 | } |
145 | |
146 | /* Initialize a parent watch entry. */ |
147 | static struct audit_parent *audit_init_parent(struct path *path) |
148 | { |
149 | struct inode *inode = path->dentry->d_inode; |
150 | struct audit_parent *parent; |
151 | int ret; |
152 | |
153 | parent = kzalloc(sizeof(*parent), GFP_KERNEL); |
154 | if (unlikely(!parent)) |
155 | return ERR_PTR(-ENOMEM); |
156 | |
157 | INIT_LIST_HEAD(&parent->watches); |
158 | |
159 | fsnotify_init_mark(&parent->mark, audit_watch_free_mark); |
160 | parent->mark.mask = AUDIT_FS_WATCH; |
161 | ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, NULL, 0); |
162 | if (ret < 0) { |
163 | audit_free_parent(parent); |
164 | return ERR_PTR(ret); |
165 | } |
166 | |
167 | return parent; |
168 | } |
169 | |
170 | /* Initialize a watch entry. */ |
171 | static struct audit_watch *audit_init_watch(char *path) |
172 | { |
173 | struct audit_watch *watch; |
174 | |
175 | watch = kzalloc(sizeof(*watch), GFP_KERNEL); |
176 | if (unlikely(!watch)) |
177 | return ERR_PTR(-ENOMEM); |
178 | |
179 | INIT_LIST_HEAD(&watch->rules); |
180 | atomic_set(&watch->count, 1); |
181 | watch->path = path; |
182 | watch->dev = (dev_t)-1; |
183 | watch->ino = (unsigned long)-1; |
184 | |
185 | return watch; |
186 | } |
187 | |
188 | /* Translate a watch string to kernel respresentation. */ |
189 | int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op) |
190 | { |
191 | struct audit_watch *watch; |
192 | |
193 | if (!audit_watch_group) |
194 | return -EOPNOTSUPP; |
195 | |
196 | if (path[0] != '/' || path[len-1] == '/' || |
197 | krule->listnr != AUDIT_FILTER_EXIT || |
198 | op != Audit_equal || |
199 | krule->inode_f || krule->watch || krule->tree) |
200 | return -EINVAL; |
201 | |
202 | watch = audit_init_watch(path); |
203 | if (IS_ERR(watch)) |
204 | return PTR_ERR(watch); |
205 | |
206 | audit_get_watch(watch); |
207 | krule->watch = watch; |
208 | |
209 | return 0; |
210 | } |
211 | |
212 | /* Duplicate the given audit watch. The new watch's rules list is initialized |
213 | * to an empty list and wlist is undefined. */ |
214 | static struct audit_watch *audit_dupe_watch(struct audit_watch *old) |
215 | { |
216 | char *path; |
217 | struct audit_watch *new; |
218 | |
219 | path = kstrdup(old->path, GFP_KERNEL); |
220 | if (unlikely(!path)) |
221 | return ERR_PTR(-ENOMEM); |
222 | |
223 | new = audit_init_watch(path); |
224 | if (IS_ERR(new)) { |
225 | kfree(path); |
226 | goto out; |
227 | } |
228 | |
229 | new->dev = old->dev; |
230 | new->ino = old->ino; |
231 | audit_get_parent(old->parent); |
232 | new->parent = old->parent; |
233 | |
234 | out: |
235 | return new; |
236 | } |
237 | |
238 | static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op) |
239 | { |
240 | if (audit_enabled) { |
241 | struct audit_buffer *ab; |
242 | ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE); |
243 | if (unlikely(!ab)) |
244 | return; |
245 | audit_log_format(ab, "auid=%u ses=%u op=", |
246 | from_kuid(&init_user_ns, audit_get_loginuid(current)), |
247 | audit_get_sessionid(current)); |
248 | audit_log_string(ab, op); |
249 | audit_log_format(ab, " path="); |
250 | audit_log_untrustedstring(ab, w->path); |
251 | audit_log_key(ab, r->filterkey); |
252 | audit_log_format(ab, " list=%d res=1", r->listnr); |
253 | audit_log_end(ab); |
254 | } |
255 | } |
256 | |
257 | /* Update inode info in audit rules based on filesystem event. */ |
258 | static void audit_update_watch(struct audit_parent *parent, |
259 | const char *dname, dev_t dev, |
260 | unsigned long ino, unsigned invalidating) |
261 | { |
262 | struct audit_watch *owatch, *nwatch, *nextw; |
263 | struct audit_krule *r, *nextr; |
264 | struct audit_entry *oentry, *nentry; |
265 | |
266 | mutex_lock(&audit_filter_mutex); |
267 | /* Run all of the watches on this parent looking for the one that |
268 | * matches the given dname */ |
269 | list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) { |
270 | if (audit_compare_dname_path(dname, owatch->path, |
271 | AUDIT_NAME_FULL)) |
272 | continue; |
273 | |
274 | /* If the update involves invalidating rules, do the inode-based |
275 | * filtering now, so we don't omit records. */ |
276 | if (invalidating && !audit_dummy_context()) |
277 | audit_filter_inodes(current, current->audit_context); |
278 | |
279 | /* updating ino will likely change which audit_hash_list we |
280 | * are on so we need a new watch for the new list */ |
281 | nwatch = audit_dupe_watch(owatch); |
282 | if (IS_ERR(nwatch)) { |
283 | mutex_unlock(&audit_filter_mutex); |
284 | audit_panic("error updating watch, skipping"); |
285 | return; |
286 | } |
287 | nwatch->dev = dev; |
288 | nwatch->ino = ino; |
289 | |
290 | list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) { |
291 | |
292 | oentry = container_of(r, struct audit_entry, rule); |
293 | list_del(&oentry->rule.rlist); |
294 | list_del_rcu(&oentry->list); |
295 | |
296 | nentry = audit_dupe_rule(&oentry->rule); |
297 | if (IS_ERR(nentry)) { |
298 | list_del(&oentry->rule.list); |
299 | audit_panic("error updating watch, removing"); |
300 | } else { |
301 | int h = audit_hash_ino((u32)ino); |
302 | |
303 | /* |
304 | * nentry->rule.watch == oentry->rule.watch so |
305 | * we must drop that reference and set it to our |
306 | * new watch. |
307 | */ |
308 | audit_put_watch(nentry->rule.watch); |
309 | audit_get_watch(nwatch); |
310 | nentry->rule.watch = nwatch; |
311 | list_add(&nentry->rule.rlist, &nwatch->rules); |
312 | list_add_rcu(&nentry->list, &audit_inode_hash[h]); |
313 | list_replace(&oentry->rule.list, |
314 | &nentry->rule.list); |
315 | } |
316 | |
317 | audit_watch_log_rule_change(r, owatch, "updated rules"); |
318 | |
319 | call_rcu(&oentry->rcu, audit_free_rule_rcu); |
320 | } |
321 | |
322 | audit_remove_watch(owatch); |
323 | goto add_watch_to_parent; /* event applies to a single watch */ |
324 | } |
325 | mutex_unlock(&audit_filter_mutex); |
326 | return; |
327 | |
328 | add_watch_to_parent: |
329 | list_add(&nwatch->wlist, &parent->watches); |
330 | mutex_unlock(&audit_filter_mutex); |
331 | return; |
332 | } |
333 | |
334 | /* Remove all watches & rules associated with a parent that is going away. */ |
335 | static void audit_remove_parent_watches(struct audit_parent *parent) |
336 | { |
337 | struct audit_watch *w, *nextw; |
338 | struct audit_krule *r, *nextr; |
339 | struct audit_entry *e; |
340 | |
341 | mutex_lock(&audit_filter_mutex); |
342 | list_for_each_entry_safe(w, nextw, &parent->watches, wlist) { |
343 | list_for_each_entry_safe(r, nextr, &w->rules, rlist) { |
344 | e = container_of(r, struct audit_entry, rule); |
345 | audit_watch_log_rule_change(r, w, "remove rule"); |
346 | list_del(&r->rlist); |
347 | list_del(&r->list); |
348 | list_del_rcu(&e->list); |
349 | call_rcu(&e->rcu, audit_free_rule_rcu); |
350 | } |
351 | audit_remove_watch(w); |
352 | } |
353 | mutex_unlock(&audit_filter_mutex); |
354 | |
355 | fsnotify_destroy_mark(&parent->mark, audit_watch_group); |
356 | } |
357 | |
358 | /* Get path information necessary for adding watches. */ |
359 | static int audit_get_nd(struct audit_watch *watch, struct path *parent) |
360 | { |
361 | struct dentry *d = kern_path_locked(watch->path, parent); |
362 | if (IS_ERR(d)) |
363 | return PTR_ERR(d); |
364 | mutex_unlock(&parent->dentry->d_inode->i_mutex); |
365 | if (d->d_inode) { |
366 | /* update watch filter fields */ |
367 | watch->dev = d->d_inode->i_sb->s_dev; |
368 | watch->ino = d->d_inode->i_ino; |
369 | } |
370 | dput(d); |
371 | return 0; |
372 | } |
373 | |
374 | /* Associate the given rule with an existing parent. |
375 | * Caller must hold audit_filter_mutex. */ |
376 | static void audit_add_to_parent(struct audit_krule *krule, |
377 | struct audit_parent *parent) |
378 | { |
379 | struct audit_watch *w, *watch = krule->watch; |
380 | int watch_found = 0; |
381 | |
382 | BUG_ON(!mutex_is_locked(&audit_filter_mutex)); |
383 | |
384 | list_for_each_entry(w, &parent->watches, wlist) { |
385 | if (strcmp(watch->path, w->path)) |
386 | continue; |
387 | |
388 | watch_found = 1; |
389 | |
390 | /* put krule's and initial refs to temporary watch */ |
391 | audit_put_watch(watch); |
392 | audit_put_watch(watch); |
393 | |
394 | audit_get_watch(w); |
395 | krule->watch = watch = w; |
396 | break; |
397 | } |
398 | |
399 | if (!watch_found) { |
400 | audit_get_parent(parent); |
401 | watch->parent = parent; |
402 | |
403 | list_add(&watch->wlist, &parent->watches); |
404 | } |
405 | list_add(&krule->rlist, &watch->rules); |
406 | } |
407 | |
408 | /* Find a matching watch entry, or add this one. |
409 | * Caller must hold audit_filter_mutex. */ |
410 | int audit_add_watch(struct audit_krule *krule, struct list_head **list) |
411 | { |
412 | struct audit_watch *watch = krule->watch; |
413 | struct audit_parent *parent; |
414 | struct path parent_path; |
415 | int h, ret = 0; |
416 | |
417 | mutex_unlock(&audit_filter_mutex); |
418 | |
419 | /* Avoid calling path_lookup under audit_filter_mutex. */ |
420 | ret = audit_get_nd(watch, &parent_path); |
421 | |
422 | /* caller expects mutex locked */ |
423 | mutex_lock(&audit_filter_mutex); |
424 | |
425 | if (ret) |
426 | return ret; |
427 | |
428 | /* either find an old parent or attach a new one */ |
429 | parent = audit_find_parent(parent_path.dentry->d_inode); |
430 | if (!parent) { |
431 | parent = audit_init_parent(&parent_path); |
432 | if (IS_ERR(parent)) { |
433 | ret = PTR_ERR(parent); |
434 | goto error; |
435 | } |
436 | } |
437 | |
438 | audit_add_to_parent(krule, parent); |
439 | |
440 | /* match get in audit_find_parent or audit_init_parent */ |
441 | audit_put_parent(parent); |
442 | |
443 | h = audit_hash_ino((u32)watch->ino); |
444 | *list = &audit_inode_hash[h]; |
445 | error: |
446 | path_put(&parent_path); |
447 | return ret; |
448 | } |
449 | |
450 | void audit_remove_watch_rule(struct audit_krule *krule) |
451 | { |
452 | struct audit_watch *watch = krule->watch; |
453 | struct audit_parent *parent = watch->parent; |
454 | |
455 | list_del(&krule->rlist); |
456 | |
457 | if (list_empty(&watch->rules)) { |
458 | audit_remove_watch(watch); |
459 | |
460 | if (list_empty(&parent->watches)) { |
461 | audit_get_parent(parent); |
462 | fsnotify_destroy_mark(&parent->mark, audit_watch_group); |
463 | audit_put_parent(parent); |
464 | } |
465 | } |
466 | } |
467 | |
468 | static bool audit_watch_should_send_event(struct fsnotify_group *group, struct inode *inode, |
469 | struct fsnotify_mark *inode_mark, |
470 | struct fsnotify_mark *vfsmount_mark, |
471 | __u32 mask, void *data, int data_type) |
472 | { |
473 | return true; |
474 | } |
475 | |
476 | /* Update watch data in audit rules based on fsnotify events. */ |
477 | static int audit_watch_handle_event(struct fsnotify_group *group, |
478 | struct fsnotify_mark *inode_mark, |
479 | struct fsnotify_mark *vfsmount_mark, |
480 | struct fsnotify_event *event) |
481 | { |
482 | struct inode *inode; |
483 | __u32 mask = event->mask; |
484 | const char *dname = event->file_name; |
485 | struct audit_parent *parent; |
486 | |
487 | parent = container_of(inode_mark, struct audit_parent, mark); |
488 | |
489 | BUG_ON(group != audit_watch_group); |
490 | |
491 | switch (event->data_type) { |
492 | case (FSNOTIFY_EVENT_PATH): |
493 | inode = event->path.dentry->d_inode; |
494 | break; |
495 | case (FSNOTIFY_EVENT_INODE): |
496 | inode = event->inode; |
497 | break; |
498 | default: |
499 | BUG(); |
500 | inode = NULL; |
501 | break; |
502 | }; |
503 | |
504 | if (mask & (FS_CREATE|FS_MOVED_TO) && inode) |
505 | audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0); |
506 | else if (mask & (FS_DELETE|FS_MOVED_FROM)) |
507 | audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1); |
508 | else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) |
509 | audit_remove_parent_watches(parent); |
510 | |
511 | return 0; |
512 | } |
513 | |
514 | static const struct fsnotify_ops audit_watch_fsnotify_ops = { |
515 | .should_send_event = audit_watch_should_send_event, |
516 | .handle_event = audit_watch_handle_event, |
517 | .free_group_priv = NULL, |
518 | .freeing_mark = NULL, |
519 | .free_event_priv = NULL, |
520 | }; |
521 | |
522 | static int __init audit_watch_init(void) |
523 | { |
524 | audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops); |
525 | if (IS_ERR(audit_watch_group)) { |
526 | audit_watch_group = NULL; |
527 | audit_panic("cannot create audit fsnotify group"); |
528 | } |
529 | return 0; |
530 | } |
531 | device_initcall(audit_watch_init); |
532 |
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