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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 | /* Update watch data in audit rules based on fsnotify events. */ | |
469 | static int audit_watch_handle_event(struct fsnotify_group *group, | |
470 | struct inode *to_tell, | |
471 | struct fsnotify_mark *inode_mark, | |
472 | struct fsnotify_mark *vfsmount_mark, | |
473 | u32 mask, void *data, int data_type, | |
474 | const unsigned char *dname, u32 cookie) | |
475 | { | |
476 | struct inode *inode; | |
477 | struct audit_parent *parent; | |
478 | ||
479 | parent = container_of(inode_mark, struct audit_parent, mark); | |
480 | ||
481 | BUG_ON(group != audit_watch_group); | |
482 | ||
483 | switch (data_type) { | |
484 | case (FSNOTIFY_EVENT_PATH): | |
485 | inode = ((struct path *)data)->dentry->d_inode; | |
486 | break; | |
487 | case (FSNOTIFY_EVENT_INODE): | |
488 | inode = (struct inode *)data; | |
489 | break; | |
490 | default: | |
491 | BUG(); | |
492 | inode = NULL; | |
493 | break; | |
494 | }; | |
495 | ||
496 | if (mask & (FS_CREATE|FS_MOVED_TO) && inode) | |
497 | audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0); | |
498 | else if (mask & (FS_DELETE|FS_MOVED_FROM)) | |
499 | audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1); | |
500 | else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF)) | |
501 | audit_remove_parent_watches(parent); | |
502 | ||
503 | return 0; | |
504 | } | |
505 | ||
506 | static const struct fsnotify_ops audit_watch_fsnotify_ops = { | |
507 | .handle_event = audit_watch_handle_event, | |
508 | }; | |
509 | ||
510 | static int __init audit_watch_init(void) | |
511 | { | |
512 | audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops); | |
513 | if (IS_ERR(audit_watch_group)) { | |
514 | audit_watch_group = NULL; | |
515 | audit_panic("cannot create audit fsnotify group"); | |
516 | } | |
517 | return 0; | |
518 | } | |
519 | device_initcall(audit_watch_init); |