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/file.h>
23#include <linux/kernel.h>
24#include <linux/audit.h>
25#include <linux/kthread.h>
26#include <linux/mutex.h>
27#include <linux/fs.h>
28#include <linux/fsnotify_backend.h>
29#include <linux/namei.h>
30#include <linux/netlink.h>
31#include <linux/refcount.h>
32#include <linux/sched.h>
33#include <linux/slab.h>
34#include <linux/security.h>
35#include "audit.h"
36
37/*
38 * Reference counting:
39 *
40 * audit_parent: lifetime is from audit_init_parent() to receipt of an FS_IGNORED
41 * event. Each audit_watch holds a reference to its associated parent.
42 *
43 * audit_watch: if added to lists, lifetime is from audit_init_watch() to
44 * audit_remove_watch(). Additionally, an audit_watch may exist
45 * temporarily to assist in searching existing filter data. Each
46 * audit_krule holds a reference to its associated watch.
47 */
48
49struct audit_watch {
50 refcount_t count; /* reference count */
51 dev_t dev; /* associated superblock device */
52 char *path; /* insertion path */
53 unsigned long ino; /* associated inode number */
54 struct audit_parent *parent; /* associated parent */
55 struct list_head wlist; /* entry in parent->watches list */
56 struct list_head rules; /* anchor for krule->rlist */
57};
58
59struct audit_parent {
60 struct list_head watches; /* anchor for audit_watch->wlist */
61 struct fsnotify_mark mark; /* fsnotify mark on the inode */
62};
63
64/* fsnotify handle. */
65static struct fsnotify_group *audit_watch_group;
66
67/* fsnotify events we care about. */
68#define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
69 FS_MOVE_SELF | FS_EVENT_ON_CHILD | FS_UNMOUNT)
70
71static void audit_free_parent(struct audit_parent *parent)
72{
73 WARN_ON(!list_empty(&parent->watches));
74 kfree(parent);
75}
76
77static void audit_watch_free_mark(struct fsnotify_mark *entry)
78{
79 struct audit_parent *parent;
80
81 parent = container_of(entry, struct audit_parent, mark);
82 audit_free_parent(parent);
83}
84
85static void audit_get_parent(struct audit_parent *parent)
86{
87 if (likely(parent))
88 fsnotify_get_mark(&parent->mark);
89}
90
91static void audit_put_parent(struct audit_parent *parent)
92{
93 if (likely(parent))
94 fsnotify_put_mark(&parent->mark);
95}
96
97/*
98 * Find and return the audit_parent on the given inode. If found a reference
99 * is taken on this parent.
100 */
101static inline struct audit_parent *audit_find_parent(struct inode *inode)
102{
103 struct audit_parent *parent = NULL;
104 struct fsnotify_mark *entry;
105
106 entry = fsnotify_find_mark(&inode->i_fsnotify_marks, audit_watch_group);
107 if (entry)
108 parent = container_of(entry, struct audit_parent, mark);
109
110 return parent;
111}
112
113void audit_get_watch(struct audit_watch *watch)
114{
115 refcount_inc(&watch->count);
116}
117
118void audit_put_watch(struct audit_watch *watch)
119{
120 if (refcount_dec_and_test(&watch->count)) {
121 WARN_ON(watch->parent);
122 WARN_ON(!list_empty(&watch->rules));
123 kfree(watch->path);
124 kfree(watch);
125 }
126}
127
128static void audit_remove_watch(struct audit_watch *watch)
129{
130 list_del(&watch->wlist);
131 audit_put_parent(watch->parent);
132 watch->parent = NULL;
133 audit_put_watch(watch); /* match initial get */
134}
135
136char *audit_watch_path(struct audit_watch *watch)
137{
138 return watch->path;
139}
140
141int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev)
142{
143 return (watch->ino != AUDIT_INO_UNSET) &&
144 (watch->ino == ino) &&
145 (watch->dev == dev);
146}
147
148/* Initialize a parent watch entry. */
149static struct audit_parent *audit_init_parent(struct path *path)
150{
151 struct inode *inode = d_backing_inode(path->dentry);
152 struct audit_parent *parent;
153 int ret;
154
155 parent = kzalloc(sizeof(*parent), GFP_KERNEL);
156 if (unlikely(!parent))
157 return ERR_PTR(-ENOMEM);
158
159 INIT_LIST_HEAD(&parent->watches);
160
161 fsnotify_init_mark(&parent->mark, audit_watch_group);
162 parent->mark.mask = AUDIT_FS_WATCH;
163 ret = fsnotify_add_inode_mark(&parent->mark, inode, 0);
164 if (ret < 0) {
165 audit_free_parent(parent);
166 return ERR_PTR(ret);
167 }
168
169 return parent;
170}
171
172/* Initialize a watch entry. */
173static struct audit_watch *audit_init_watch(char *path)
174{
175 struct audit_watch *watch;
176
177 watch = kzalloc(sizeof(*watch), GFP_KERNEL);
178 if (unlikely(!watch))
179 return ERR_PTR(-ENOMEM);
180
181 INIT_LIST_HEAD(&watch->rules);
182 refcount_set(&watch->count, 1);
183 watch->path = path;
184 watch->dev = AUDIT_DEV_UNSET;
185 watch->ino = AUDIT_INO_UNSET;
186
187 return watch;
188}
189
190/* Translate a watch string to kernel representation. */
191int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
192{
193 struct audit_watch *watch;
194
195 if (!audit_watch_group)
196 return -EOPNOTSUPP;
197
198 if (path[0] != '/' || path[len-1] == '/' ||
199 krule->listnr != AUDIT_FILTER_EXIT ||
200 op != Audit_equal ||
201 krule->inode_f || krule->watch || krule->tree)
202 return -EINVAL;
203
204 watch = audit_init_watch(path);
205 if (IS_ERR(watch))
206 return PTR_ERR(watch);
207
208 krule->watch = watch;
209
210 return 0;
211}
212
213/* Duplicate the given audit watch. The new watch's rules list is initialized
214 * to an empty list and wlist is undefined. */
215static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
216{
217 char *path;
218 struct audit_watch *new;
219
220 path = kstrdup(old->path, GFP_KERNEL);
221 if (unlikely(!path))
222 return ERR_PTR(-ENOMEM);
223
224 new = audit_init_watch(path);
225 if (IS_ERR(new)) {
226 kfree(path);
227 goto out;
228 }
229
230 new->dev = old->dev;
231 new->ino = old->ino;
232 audit_get_parent(old->parent);
233 new->parent = old->parent;
234
235out:
236 return new;
237}
238
239static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
240{
241 struct audit_buffer *ab;
242
243 if (!audit_enabled)
244 return;
245 ab = audit_log_start(audit_context(), GFP_NOFS, AUDIT_CONFIG_CHANGE);
246 if (!ab)
247 return;
248 audit_log_session_info(ab);
249 audit_log_format(ab, "op=%s path=", op);
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/* Update inode info in audit rules based on filesystem event. */
257static void audit_update_watch(struct audit_parent *parent,
258 const char *dname, dev_t dev,
259 unsigned long ino, unsigned invalidating)
260{
261 struct audit_watch *owatch, *nwatch, *nextw;
262 struct audit_krule *r, *nextr;
263 struct audit_entry *oentry, *nentry;
264
265 mutex_lock(&audit_filter_mutex);
266 /* Run all of the watches on this parent looking for the one that
267 * matches the given dname */
268 list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
269 if (audit_compare_dname_path(dname, owatch->path,
270 AUDIT_NAME_FULL))
271 continue;
272
273 /* If the update involves invalidating rules, do the inode-based
274 * filtering now, so we don't omit records. */
275 if (invalidating && !audit_dummy_context())
276 audit_filter_inodes(current, audit_context());
277
278 /* updating ino will likely change which audit_hash_list we
279 * are on so we need a new watch for the new list */
280 nwatch = audit_dupe_watch(owatch);
281 if (IS_ERR(nwatch)) {
282 mutex_unlock(&audit_filter_mutex);
283 audit_panic("error updating watch, skipping");
284 return;
285 }
286 nwatch->dev = dev;
287 nwatch->ino = ino;
288
289 list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
290
291 oentry = container_of(r, struct audit_entry, rule);
292 list_del(&oentry->rule.rlist);
293 list_del_rcu(&oentry->list);
294
295 nentry = audit_dupe_rule(&oentry->rule);
296 if (IS_ERR(nentry)) {
297 list_del(&oentry->rule.list);
298 audit_panic("error updating watch, removing");
299 } else {
300 int h = audit_hash_ino((u32)ino);
301
302 /*
303 * nentry->rule.watch == oentry->rule.watch so
304 * we must drop that reference and set it to our
305 * new watch.
306 */
307 audit_put_watch(nentry->rule.watch);
308 audit_get_watch(nwatch);
309 nentry->rule.watch = nwatch;
310 list_add(&nentry->rule.rlist, &nwatch->rules);
311 list_add_rcu(&nentry->list, &audit_inode_hash[h]);
312 list_replace(&oentry->rule.list,
313 &nentry->rule.list);
314 }
315 if (oentry->rule.exe)
316 audit_remove_mark(oentry->rule.exe);
317
318 audit_watch_log_rule_change(r, owatch, "updated_rules");
319
320 call_rcu(&oentry->rcu, audit_free_rule_rcu);
321 }
322
323 audit_remove_watch(owatch);
324 goto add_watch_to_parent; /* event applies to a single watch */
325 }
326 mutex_unlock(&audit_filter_mutex);
327 return;
328
329add_watch_to_parent:
330 list_add(&nwatch->wlist, &parent->watches);
331 mutex_unlock(&audit_filter_mutex);
332 return;
333}
334
335/* Remove all watches & rules associated with a parent that is going away. */
336static void audit_remove_parent_watches(struct audit_parent *parent)
337{
338 struct audit_watch *w, *nextw;
339 struct audit_krule *r, *nextr;
340 struct audit_entry *e;
341
342 mutex_lock(&audit_filter_mutex);
343 list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
344 list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
345 e = container_of(r, struct audit_entry, rule);
346 audit_watch_log_rule_change(r, w, "remove_rule");
347 if (e->rule.exe)
348 audit_remove_mark(e->rule.exe);
349 list_del(&r->rlist);
350 list_del(&r->list);
351 list_del_rcu(&e->list);
352 call_rcu(&e->rcu, audit_free_rule_rcu);
353 }
354 audit_remove_watch(w);
355 }
356 mutex_unlock(&audit_filter_mutex);
357
358 fsnotify_destroy_mark(&parent->mark, audit_watch_group);
359}
360
361/* Get path information necessary for adding watches. */
362static int audit_get_nd(struct audit_watch *watch, struct path *parent)
363{
364 struct dentry *d = kern_path_locked(watch->path, parent);
365 if (IS_ERR(d))
366 return PTR_ERR(d);
367 inode_unlock(d_backing_inode(parent->dentry));
368 if (d_is_positive(d)) {
369 /* update watch filter fields */
370 watch->dev = d->d_sb->s_dev;
371 watch->ino = d_backing_inode(d)->i_ino;
372 }
373 dput(d);
374 return 0;
375}
376
377/* Associate the given rule with an existing parent.
378 * Caller must hold audit_filter_mutex. */
379static void audit_add_to_parent(struct audit_krule *krule,
380 struct audit_parent *parent)
381{
382 struct audit_watch *w, *watch = krule->watch;
383 int watch_found = 0;
384
385 BUG_ON(!mutex_is_locked(&audit_filter_mutex));
386
387 list_for_each_entry(w, &parent->watches, wlist) {
388 if (strcmp(watch->path, w->path))
389 continue;
390
391 watch_found = 1;
392
393 /* put krule's ref to temporary watch */
394 audit_put_watch(watch);
395
396 audit_get_watch(w);
397 krule->watch = watch = w;
398
399 audit_put_parent(parent);
400 break;
401 }
402
403 if (!watch_found) {
404 watch->parent = parent;
405
406 audit_get_watch(watch);
407 list_add(&watch->wlist, &parent->watches);
408 }
409 list_add(&krule->rlist, &watch->rules);
410}
411
412/* Find a matching watch entry, or add this one.
413 * Caller must hold audit_filter_mutex. */
414int audit_add_watch(struct audit_krule *krule, struct list_head **list)
415{
416 struct audit_watch *watch = krule->watch;
417 struct audit_parent *parent;
418 struct path parent_path;
419 int h, ret = 0;
420
421 /*
422 * When we will be calling audit_add_to_parent, krule->watch might have
423 * been updated and watch might have been freed.
424 * So we need to keep a reference of watch.
425 */
426 audit_get_watch(watch);
427
428 mutex_unlock(&audit_filter_mutex);
429
430 /* Avoid calling path_lookup under audit_filter_mutex. */
431 ret = audit_get_nd(watch, &parent_path);
432
433 /* caller expects mutex locked */
434 mutex_lock(&audit_filter_mutex);
435
436 if (ret) {
437 audit_put_watch(watch);
438 return ret;
439 }
440
441 /* either find an old parent or attach a new one */
442 parent = audit_find_parent(d_backing_inode(parent_path.dentry));
443 if (!parent) {
444 parent = audit_init_parent(&parent_path);
445 if (IS_ERR(parent)) {
446 ret = PTR_ERR(parent);
447 goto error;
448 }
449 }
450
451 audit_add_to_parent(krule, parent);
452
453 h = audit_hash_ino((u32)watch->ino);
454 *list = &audit_inode_hash[h];
455error:
456 path_put(&parent_path);
457 audit_put_watch(watch);
458 return ret;
459}
460
461void audit_remove_watch_rule(struct audit_krule *krule)
462{
463 struct audit_watch *watch = krule->watch;
464 struct audit_parent *parent = watch->parent;
465
466 list_del(&krule->rlist);
467
468 if (list_empty(&watch->rules)) {
469 /*
470 * audit_remove_watch() drops our reference to 'parent' which
471 * can get freed. Grab our own reference to be safe.
472 */
473 audit_get_parent(parent);
474 audit_remove_watch(watch);
475 if (list_empty(&parent->watches))
476 fsnotify_destroy_mark(&parent->mark, audit_watch_group);
477 audit_put_parent(parent);
478 }
479}
480
481/* Update watch data in audit rules based on fsnotify events. */
482static int audit_watch_handle_event(struct fsnotify_group *group,
483 struct inode *to_tell,
484 u32 mask, const void *data, int data_type,
485 const unsigned char *dname, u32 cookie,
486 struct fsnotify_iter_info *iter_info)
487{
488 struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
489 const struct inode *inode;
490 struct audit_parent *parent;
491
492 parent = container_of(inode_mark, struct audit_parent, mark);
493
494 BUG_ON(group != audit_watch_group);
495
496 switch (data_type) {
497 case (FSNOTIFY_EVENT_PATH):
498 inode = d_backing_inode(((const struct path *)data)->dentry);
499 break;
500 case (FSNOTIFY_EVENT_INODE):
501 inode = (const struct inode *)data;
502 break;
503 default:
504 BUG();
505 inode = NULL;
506 break;
507 }
508
509 if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
510 audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
511 else if (mask & (FS_DELETE|FS_MOVED_FROM))
512 audit_update_watch(parent, dname, AUDIT_DEV_UNSET, AUDIT_INO_UNSET, 1);
513 else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
514 audit_remove_parent_watches(parent);
515
516 return 0;
517}
518
519static const struct fsnotify_ops audit_watch_fsnotify_ops = {
520 .handle_event = audit_watch_handle_event,
521 .free_mark = audit_watch_free_mark,
522};
523
524static int __init audit_watch_init(void)
525{
526 audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops);
527 if (IS_ERR(audit_watch_group)) {
528 audit_watch_group = NULL;
529 audit_panic("cannot create audit fsnotify group");
530 }
531 return 0;
532}
533device_initcall(audit_watch_init);
534
535int audit_dupe_exe(struct audit_krule *new, struct audit_krule *old)
536{
537 struct audit_fsnotify_mark *audit_mark;
538 char *pathname;
539
540 pathname = kstrdup(audit_mark_path(old->exe), GFP_KERNEL);
541 if (!pathname)
542 return -ENOMEM;
543
544 audit_mark = audit_alloc_mark(new, pathname, strlen(pathname));
545 if (IS_ERR(audit_mark)) {
546 kfree(pathname);
547 return PTR_ERR(audit_mark);
548 }
549 new->exe = audit_mark;
550
551 return 0;
552}
553
554int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark)
555{
556 struct file *exe_file;
557 unsigned long ino;
558 dev_t dev;
559
560 exe_file = get_task_exe_file(tsk);
561 if (!exe_file)
562 return 0;
563 ino = file_inode(exe_file)->i_ino;
564 dev = file_inode(exe_file)->i_sb->s_dev;
565 fput(exe_file);
566 return audit_mark_compare(mark, ino, dev);
567}
568