Commit | Line | Data |
---|---|---|
cfcad62c EP |
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/namei.h> | |
28 | #include <linux/netlink.h> | |
29 | #include <linux/sched.h> | |
5a0e3ad6 | 30 | #include <linux/slab.h> |
cfcad62c EP |
31 | #include <linux/inotify.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 IN_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 */ | |
cfcad62c | 49 | dev_t dev; /* associated superblock device */ |
e08b061e | 50 | char *path; /* insertion path */ |
cfcad62c EP |
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; /* associated rules */ | |
55 | }; | |
56 | ||
57 | struct audit_parent { | |
58 | struct list_head ilist; /* entry in inotify registration list */ | |
59 | struct list_head watches; /* associated watches */ | |
60 | struct inotify_watch wdata; /* inotify watch data */ | |
61 | unsigned flags; /* status flags */ | |
62 | }; | |
63 | ||
64 | /* Inotify handle. */ | |
65 | struct inotify_handle *audit_ih; | |
66 | ||
67 | /* | |
68 | * audit_parent status flags: | |
69 | * | |
70 | * AUDIT_PARENT_INVALID - set anytime rules/watches are auto-removed due to | |
71 | * a filesystem event to ensure we're adding audit watches to a valid parent. | |
72 | * Technically not needed for IN_DELETE_SELF or IN_UNMOUNT events, as we cannot | |
73 | * receive them while we have nameidata, but must be used for IN_MOVE_SELF which | |
74 | * we can receive while holding nameidata. | |
75 | */ | |
76 | #define AUDIT_PARENT_INVALID 0x001 | |
77 | ||
78 | /* Inotify events we care about. */ | |
79 | #define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF | |
80 | ||
81 | static void audit_free_parent(struct inotify_watch *i_watch) | |
82 | { | |
83 | struct audit_parent *parent; | |
84 | ||
85 | parent = container_of(i_watch, struct audit_parent, wdata); | |
86 | WARN_ON(!list_empty(&parent->watches)); | |
87 | kfree(parent); | |
88 | } | |
89 | ||
90 | void audit_get_watch(struct audit_watch *watch) | |
91 | { | |
92 | atomic_inc(&watch->count); | |
93 | } | |
94 | ||
95 | void audit_put_watch(struct audit_watch *watch) | |
96 | { | |
97 | if (atomic_dec_and_test(&watch->count)) { | |
98 | WARN_ON(watch->parent); | |
99 | WARN_ON(!list_empty(&watch->rules)); | |
100 | kfree(watch->path); | |
101 | kfree(watch); | |
102 | } | |
103 | } | |
104 | ||
105 | void audit_remove_watch(struct audit_watch *watch) | |
106 | { | |
107 | list_del(&watch->wlist); | |
108 | put_inotify_watch(&watch->parent->wdata); | |
109 | watch->parent = NULL; | |
110 | audit_put_watch(watch); /* match initial get */ | |
111 | } | |
112 | ||
113 | char *audit_watch_path(struct audit_watch *watch) | |
114 | { | |
115 | return watch->path; | |
116 | } | |
117 | ||
118 | struct list_head *audit_watch_rules(struct audit_watch *watch) | |
119 | { | |
120 | return &watch->rules; | |
121 | } | |
122 | ||
123 | unsigned long audit_watch_inode(struct audit_watch *watch) | |
124 | { | |
125 | return watch->ino; | |
126 | } | |
127 | ||
128 | dev_t audit_watch_dev(struct audit_watch *watch) | |
129 | { | |
130 | return watch->dev; | |
131 | } | |
132 | ||
133 | /* Initialize a parent watch entry. */ | |
134 | static struct audit_parent *audit_init_parent(struct nameidata *ndp) | |
135 | { | |
136 | struct audit_parent *parent; | |
137 | s32 wd; | |
138 | ||
139 | parent = kzalloc(sizeof(*parent), GFP_KERNEL); | |
140 | if (unlikely(!parent)) | |
141 | return ERR_PTR(-ENOMEM); | |
142 | ||
143 | INIT_LIST_HEAD(&parent->watches); | |
144 | parent->flags = 0; | |
145 | ||
146 | inotify_init_watch(&parent->wdata); | |
147 | /* grab a ref so inotify watch hangs around until we take audit_filter_mutex */ | |
148 | get_inotify_watch(&parent->wdata); | |
149 | wd = inotify_add_watch(audit_ih, &parent->wdata, | |
150 | ndp->path.dentry->d_inode, AUDIT_IN_WATCH); | |
151 | if (wd < 0) { | |
152 | audit_free_parent(&parent->wdata); | |
153 | return ERR_PTR(wd); | |
154 | } | |
155 | ||
156 | return parent; | |
157 | } | |
158 | ||
159 | /* Initialize a watch entry. */ | |
160 | static struct audit_watch *audit_init_watch(char *path) | |
161 | { | |
162 | struct audit_watch *watch; | |
163 | ||
164 | watch = kzalloc(sizeof(*watch), GFP_KERNEL); | |
165 | if (unlikely(!watch)) | |
166 | return ERR_PTR(-ENOMEM); | |
167 | ||
168 | INIT_LIST_HEAD(&watch->rules); | |
169 | atomic_set(&watch->count, 1); | |
170 | watch->path = path; | |
171 | watch->dev = (dev_t)-1; | |
172 | watch->ino = (unsigned long)-1; | |
173 | ||
174 | return watch; | |
175 | } | |
176 | ||
177 | /* Translate a watch string to kernel respresentation. */ | |
178 | int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op) | |
179 | { | |
180 | struct audit_watch *watch; | |
181 | ||
182 | if (!audit_ih) | |
183 | return -EOPNOTSUPP; | |
184 | ||
185 | if (path[0] != '/' || path[len-1] == '/' || | |
186 | krule->listnr != AUDIT_FILTER_EXIT || | |
187 | op != Audit_equal || | |
188 | krule->inode_f || krule->watch || krule->tree) | |
189 | return -EINVAL; | |
190 | ||
191 | watch = audit_init_watch(path); | |
192 | if (IS_ERR(watch)) | |
193 | return PTR_ERR(watch); | |
194 | ||
195 | audit_get_watch(watch); | |
196 | krule->watch = watch; | |
197 | ||
198 | return 0; | |
199 | } | |
200 | ||
201 | /* Duplicate the given audit watch. The new watch's rules list is initialized | |
202 | * to an empty list and wlist is undefined. */ | |
203 | static struct audit_watch *audit_dupe_watch(struct audit_watch *old) | |
204 | { | |
205 | char *path; | |
206 | struct audit_watch *new; | |
207 | ||
208 | path = kstrdup(old->path, GFP_KERNEL); | |
209 | if (unlikely(!path)) | |
210 | return ERR_PTR(-ENOMEM); | |
211 | ||
212 | new = audit_init_watch(path); | |
213 | if (IS_ERR(new)) { | |
214 | kfree(path); | |
215 | goto out; | |
216 | } | |
217 | ||
218 | new->dev = old->dev; | |
219 | new->ino = old->ino; | |
220 | get_inotify_watch(&old->parent->wdata); | |
221 | new->parent = old->parent; | |
222 | ||
223 | out: | |
224 | return new; | |
225 | } | |
226 | ||
227 | static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op) | |
228 | { | |
229 | if (audit_enabled) { | |
230 | struct audit_buffer *ab; | |
231 | ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE); | |
232 | audit_log_format(ab, "auid=%u ses=%u op=", | |
233 | audit_get_loginuid(current), | |
234 | audit_get_sessionid(current)); | |
235 | audit_log_string(ab, op); | |
236 | audit_log_format(ab, " path="); | |
237 | audit_log_untrustedstring(ab, w->path); | |
9d960985 | 238 | audit_log_key(ab, r->filterkey); |
cfcad62c EP |
239 | audit_log_format(ab, " list=%d res=1", r->listnr); |
240 | audit_log_end(ab); | |
241 | } | |
242 | } | |
243 | ||
244 | /* Update inode info in audit rules based on filesystem event. */ | |
245 | static void audit_update_watch(struct audit_parent *parent, | |
246 | const char *dname, dev_t dev, | |
247 | unsigned long ino, unsigned invalidating) | |
248 | { | |
249 | struct audit_watch *owatch, *nwatch, *nextw; | |
250 | struct audit_krule *r, *nextr; | |
251 | struct audit_entry *oentry, *nentry; | |
252 | ||
253 | mutex_lock(&audit_filter_mutex); | |
254 | list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) { | |
255 | if (audit_compare_dname_path(dname, owatch->path, NULL)) | |
256 | continue; | |
257 | ||
258 | /* If the update involves invalidating rules, do the inode-based | |
259 | * filtering now, so we don't omit records. */ | |
260 | if (invalidating && current->audit_context) | |
261 | audit_filter_inodes(current, current->audit_context); | |
262 | ||
263 | nwatch = audit_dupe_watch(owatch); | |
264 | if (IS_ERR(nwatch)) { | |
265 | mutex_unlock(&audit_filter_mutex); | |
266 | audit_panic("error updating watch, skipping"); | |
267 | return; | |
268 | } | |
269 | nwatch->dev = dev; | |
270 | nwatch->ino = ino; | |
271 | ||
272 | list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) { | |
273 | ||
274 | oentry = container_of(r, struct audit_entry, rule); | |
275 | list_del(&oentry->rule.rlist); | |
276 | list_del_rcu(&oentry->list); | |
277 | ||
278 | nentry = audit_dupe_rule(&oentry->rule, nwatch); | |
279 | if (IS_ERR(nentry)) { | |
280 | list_del(&oentry->rule.list); | |
281 | audit_panic("error updating watch, removing"); | |
282 | } else { | |
283 | int h = audit_hash_ino((u32)ino); | |
284 | list_add(&nentry->rule.rlist, &nwatch->rules); | |
285 | list_add_rcu(&nentry->list, &audit_inode_hash[h]); | |
286 | list_replace(&oentry->rule.list, | |
287 | &nentry->rule.list); | |
288 | } | |
289 | ||
290 | audit_watch_log_rule_change(r, owatch, "updated rules"); | |
291 | ||
292 | call_rcu(&oentry->rcu, audit_free_rule_rcu); | |
293 | } | |
294 | ||
295 | audit_remove_watch(owatch); | |
296 | goto add_watch_to_parent; /* event applies to a single watch */ | |
297 | } | |
298 | mutex_unlock(&audit_filter_mutex); | |
299 | return; | |
300 | ||
301 | add_watch_to_parent: | |
302 | list_add(&nwatch->wlist, &parent->watches); | |
303 | mutex_unlock(&audit_filter_mutex); | |
304 | return; | |
305 | } | |
306 | ||
307 | /* Remove all watches & rules associated with a parent that is going away. */ | |
308 | static void audit_remove_parent_watches(struct audit_parent *parent) | |
309 | { | |
310 | struct audit_watch *w, *nextw; | |
311 | struct audit_krule *r, *nextr; | |
312 | struct audit_entry *e; | |
313 | ||
314 | mutex_lock(&audit_filter_mutex); | |
315 | parent->flags |= AUDIT_PARENT_INVALID; | |
316 | list_for_each_entry_safe(w, nextw, &parent->watches, wlist) { | |
317 | list_for_each_entry_safe(r, nextr, &w->rules, rlist) { | |
318 | e = container_of(r, struct audit_entry, rule); | |
319 | audit_watch_log_rule_change(r, w, "remove rule"); | |
320 | list_del(&r->rlist); | |
321 | list_del(&r->list); | |
322 | list_del_rcu(&e->list); | |
323 | call_rcu(&e->rcu, audit_free_rule_rcu); | |
324 | } | |
325 | audit_remove_watch(w); | |
326 | } | |
327 | mutex_unlock(&audit_filter_mutex); | |
328 | } | |
329 | ||
330 | /* Unregister inotify watches for parents on in_list. | |
331 | * Generates an IN_IGNORED event. */ | |
332 | void audit_inotify_unregister(struct list_head *in_list) | |
333 | { | |
334 | struct audit_parent *p, *n; | |
335 | ||
336 | list_for_each_entry_safe(p, n, in_list, ilist) { | |
337 | list_del(&p->ilist); | |
338 | inotify_rm_watch(audit_ih, &p->wdata); | |
339 | /* the unpin matching the pin in audit_do_del_rule() */ | |
340 | unpin_inotify_watch(&p->wdata); | |
341 | } | |
342 | } | |
343 | ||
344 | /* Get path information necessary for adding watches. */ | |
35fe4d0b | 345 | static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw) |
cfcad62c EP |
346 | { |
347 | struct nameidata *ndparent, *ndwatch; | |
348 | int err; | |
349 | ||
350 | ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL); | |
351 | if (unlikely(!ndparent)) | |
352 | return -ENOMEM; | |
353 | ||
354 | ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL); | |
355 | if (unlikely(!ndwatch)) { | |
356 | kfree(ndparent); | |
357 | return -ENOMEM; | |
358 | } | |
359 | ||
360 | err = path_lookup(path, LOOKUP_PARENT, ndparent); | |
361 | if (err) { | |
362 | kfree(ndparent); | |
363 | kfree(ndwatch); | |
364 | return err; | |
365 | } | |
366 | ||
367 | err = path_lookup(path, 0, ndwatch); | |
368 | if (err) { | |
369 | kfree(ndwatch); | |
370 | ndwatch = NULL; | |
371 | } | |
372 | ||
373 | *ndp = ndparent; | |
374 | *ndw = ndwatch; | |
375 | ||
376 | return 0; | |
377 | } | |
378 | ||
379 | /* Release resources used for watch path information. */ | |
35fe4d0b | 380 | static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw) |
cfcad62c EP |
381 | { |
382 | if (ndp) { | |
383 | path_put(&ndp->path); | |
384 | kfree(ndp); | |
385 | } | |
386 | if (ndw) { | |
387 | path_put(&ndw->path); | |
388 | kfree(ndw); | |
389 | } | |
390 | } | |
391 | ||
392 | /* Associate the given rule with an existing parent inotify_watch. | |
393 | * Caller must hold audit_filter_mutex. */ | |
394 | static void audit_add_to_parent(struct audit_krule *krule, | |
395 | struct audit_parent *parent) | |
396 | { | |
397 | struct audit_watch *w, *watch = krule->watch; | |
398 | int watch_found = 0; | |
399 | ||
400 | list_for_each_entry(w, &parent->watches, wlist) { | |
401 | if (strcmp(watch->path, w->path)) | |
402 | continue; | |
403 | ||
404 | watch_found = 1; | |
405 | ||
406 | /* put krule's and initial refs to temporary watch */ | |
407 | audit_put_watch(watch); | |
408 | audit_put_watch(watch); | |
409 | ||
410 | audit_get_watch(w); | |
411 | krule->watch = watch = w; | |
412 | break; | |
413 | } | |
414 | ||
415 | if (!watch_found) { | |
416 | get_inotify_watch(&parent->wdata); | |
417 | watch->parent = parent; | |
418 | ||
419 | list_add(&watch->wlist, &parent->watches); | |
420 | } | |
421 | list_add(&krule->rlist, &watch->rules); | |
422 | } | |
423 | ||
424 | /* Find a matching watch entry, or add this one. | |
425 | * Caller must hold audit_filter_mutex. */ | |
35fe4d0b | 426 | int audit_add_watch(struct audit_krule *krule) |
cfcad62c EP |
427 | { |
428 | struct audit_watch *watch = krule->watch; | |
429 | struct inotify_watch *i_watch; | |
430 | struct audit_parent *parent; | |
35fe4d0b | 431 | struct nameidata *ndp = NULL, *ndw = NULL; |
cfcad62c EP |
432 | int ret = 0; |
433 | ||
35fe4d0b EP |
434 | mutex_unlock(&audit_filter_mutex); |
435 | ||
436 | /* Avoid calling path_lookup under audit_filter_mutex. */ | |
437 | ret = audit_get_nd(watch->path, &ndp, &ndw); | |
438 | if (ret) { | |
439 | /* caller expects mutex locked */ | |
440 | mutex_lock(&audit_filter_mutex); | |
441 | goto error; | |
442 | } | |
443 | ||
cfcad62c EP |
444 | /* update watch filter fields */ |
445 | if (ndw) { | |
446 | watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev; | |
447 | watch->ino = ndw->path.dentry->d_inode->i_ino; | |
448 | } | |
449 | ||
450 | /* The audit_filter_mutex must not be held during inotify calls because | |
451 | * we hold it during inotify event callback processing. If an existing | |
452 | * inotify watch is found, inotify_find_watch() grabs a reference before | |
453 | * returning. | |
454 | */ | |
cfcad62c EP |
455 | if (inotify_find_watch(audit_ih, ndp->path.dentry->d_inode, |
456 | &i_watch) < 0) { | |
457 | parent = audit_init_parent(ndp); | |
458 | if (IS_ERR(parent)) { | |
459 | /* caller expects mutex locked */ | |
460 | mutex_lock(&audit_filter_mutex); | |
35fe4d0b EP |
461 | ret = PTR_ERR(parent); |
462 | goto error; | |
cfcad62c EP |
463 | } |
464 | } else | |
465 | parent = container_of(i_watch, struct audit_parent, wdata); | |
466 | ||
467 | mutex_lock(&audit_filter_mutex); | |
468 | ||
469 | /* parent was moved before we took audit_filter_mutex */ | |
470 | if (parent->flags & AUDIT_PARENT_INVALID) | |
471 | ret = -ENOENT; | |
472 | else | |
473 | audit_add_to_parent(krule, parent); | |
474 | ||
475 | /* match get in audit_init_parent or inotify_find_watch */ | |
476 | put_inotify_watch(&parent->wdata); | |
35fe4d0b EP |
477 | |
478 | error: | |
479 | audit_put_nd(ndp, ndw); /* NULL args OK */ | |
cfcad62c | 480 | return ret; |
35fe4d0b | 481 | |
cfcad62c EP |
482 | } |
483 | ||
484 | void audit_remove_watch_rule(struct audit_krule *krule, struct list_head *list) | |
485 | { | |
486 | struct audit_watch *watch = krule->watch; | |
487 | struct audit_parent *parent = watch->parent; | |
488 | ||
489 | list_del(&krule->rlist); | |
490 | ||
491 | if (list_empty(&watch->rules)) { | |
492 | audit_remove_watch(watch); | |
493 | ||
494 | if (list_empty(&parent->watches)) { | |
495 | /* Put parent on the inotify un-registration | |
496 | * list. Grab a reference before releasing | |
497 | * audit_filter_mutex, to be released in | |
498 | * audit_inotify_unregister(). | |
499 | * If filesystem is going away, just leave | |
500 | * the sucker alone, eviction will take | |
501 | * care of it. */ | |
502 | if (pin_inotify_watch(&parent->wdata)) | |
503 | list_add(&parent->ilist, list); | |
504 | } | |
505 | } | |
506 | } | |
507 | ||
508 | /* Update watch data in audit rules based on inotify events. */ | |
509 | static void audit_handle_ievent(struct inotify_watch *i_watch, u32 wd, u32 mask, | |
510 | u32 cookie, const char *dname, struct inode *inode) | |
511 | { | |
512 | struct audit_parent *parent; | |
513 | ||
514 | parent = container_of(i_watch, struct audit_parent, wdata); | |
515 | ||
516 | if (mask & (IN_CREATE|IN_MOVED_TO) && inode) | |
517 | audit_update_watch(parent, dname, inode->i_sb->s_dev, | |
518 | inode->i_ino, 0); | |
519 | else if (mask & (IN_DELETE|IN_MOVED_FROM)) | |
520 | audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1); | |
521 | /* inotify automatically removes the watch and sends IN_IGNORED */ | |
522 | else if (mask & (IN_DELETE_SELF|IN_UNMOUNT)) | |
523 | audit_remove_parent_watches(parent); | |
524 | /* inotify does not remove the watch, so remove it manually */ | |
525 | else if(mask & IN_MOVE_SELF) { | |
526 | audit_remove_parent_watches(parent); | |
527 | inotify_remove_watch_locked(audit_ih, i_watch); | |
528 | } else if (mask & IN_IGNORED) | |
529 | put_inotify_watch(i_watch); | |
530 | } | |
531 | ||
532 | static const struct inotify_operations audit_inotify_ops = { | |
533 | .handle_event = audit_handle_ievent, | |
534 | .destroy_watch = audit_free_parent, | |
535 | }; | |
536 | ||
537 | static int __init audit_watch_init(void) | |
538 | { | |
539 | audit_ih = inotify_init(&audit_inotify_ops); | |
540 | if (IS_ERR(audit_ih)) | |
541 | audit_panic("cannot initialize inotify handle"); | |
542 | return 0; | |
543 | } | |
544 | subsys_initcall(audit_watch_init); |