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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/namei.h> |
28 | #include <linux/netlink.h> |
29 | #include <linux/sched.h> |
30 | #include <linux/slab.h> |
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 */ |
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; /* 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); |
238 | audit_log_key(ab, r->filterkey); |
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. */ |
345 | static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw) |
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. */ |
380 | static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw) |
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. */ |
426 | int audit_add_watch(struct audit_krule *krule) |
427 | { |
428 | struct audit_watch *watch = krule->watch; |
429 | struct inotify_watch *i_watch; |
430 | struct audit_parent *parent; |
431 | struct nameidata *ndp = NULL, *ndw = NULL; |
432 | int ret = 0; |
433 | |
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 | |
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 | */ |
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); |
461 | ret = PTR_ERR(parent); |
462 | goto error; |
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); |
477 | |
478 | error: |
479 | audit_put_nd(ndp, ndw); /* NULL args OK */ |
480 | return ret; |
481 | |
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); |
545 |
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