1 /* audit_watch.c -- watching inodes
3 * Copyright 2003-2009 Red Hat, Inc.
4 * Copyright 2005 Hewlett-Packard Development Company, L.P.
5 * Copyright 2005 IBM Corporation
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.
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.
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
22 #include <linux/kernel.h>
23 #include <linux/audit.h>
24 #include <linux/kthread.h>
25 #include <linux/mutex.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>
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.
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.
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 */
58 struct list_head watches; /* anchor for audit_watch->wlist */
59 struct fsnotify_mark mark; /* fsnotify mark on the inode */
62 /* fsnotify handle. */
63 struct fsnotify_group *audit_watch_group;
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)
69 static void audit_free_parent(struct audit_parent *parent)
71 WARN_ON(!list_empty(&parent->watches));
75 static void audit_watch_free_mark(struct fsnotify_mark *entry)
77 struct audit_parent *parent;
79 parent = container_of(entry, struct audit_parent, mark);
80 audit_free_parent(parent);
83 static void audit_get_parent(struct audit_parent *parent)
86 fsnotify_get_mark(&parent->mark);
89 static void audit_put_parent(struct audit_parent *parent)
92 fsnotify_put_mark(&parent->mark);
96 * Find and return the audit_parent on the given inode. If found a reference
97 * is taken on this parent.
99 static inline struct audit_parent *audit_find_parent(struct inode *inode)
101 struct audit_parent *parent = NULL;
102 struct fsnotify_mark *entry;
104 spin_lock(&inode->i_lock);
105 entry = fsnotify_find_mark(audit_watch_group, inode);
106 spin_unlock(&inode->i_lock);
109 parent = container_of(entry, struct audit_parent, mark);
114 void audit_get_watch(struct audit_watch *watch)
116 atomic_inc(&watch->count);
119 void audit_put_watch(struct audit_watch *watch)
121 if (atomic_dec_and_test(&watch->count)) {
122 WARN_ON(watch->parent);
123 WARN_ON(!list_empty(&watch->rules));
129 void audit_remove_watch(struct audit_watch *watch)
131 list_del(&watch->wlist);
132 audit_put_parent(watch->parent);
133 watch->parent = NULL;
134 audit_put_watch(watch); /* match initial get */
137 char *audit_watch_path(struct audit_watch *watch)
142 int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev)
144 return (watch->ino != (unsigned long)-1) &&
145 (watch->ino == ino) &&
149 /* Initialize a parent watch entry. */
150 static struct audit_parent *audit_init_parent(struct nameidata *ndp)
152 struct inode *inode = ndp->path.dentry->d_inode;
153 struct audit_parent *parent;
156 parent = kzalloc(sizeof(*parent), GFP_KERNEL);
157 if (unlikely(!parent))
158 return ERR_PTR(-ENOMEM);
160 INIT_LIST_HEAD(&parent->watches);
162 fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
163 parent->mark.mask = AUDIT_FS_WATCH;
164 ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, 0);
166 audit_free_parent(parent);
170 fsnotify_recalc_group_mask(audit_watch_group);
175 /* Initialize a watch entry. */
176 static struct audit_watch *audit_init_watch(char *path)
178 struct audit_watch *watch;
180 watch = kzalloc(sizeof(*watch), GFP_KERNEL);
181 if (unlikely(!watch))
182 return ERR_PTR(-ENOMEM);
184 INIT_LIST_HEAD(&watch->rules);
185 atomic_set(&watch->count, 1);
187 watch->dev = (dev_t)-1;
188 watch->ino = (unsigned long)-1;
193 /* Translate a watch string to kernel respresentation. */
194 int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
196 struct audit_watch *watch;
198 if (!audit_watch_group)
201 if (path[0] != '/' || path[len-1] == '/' ||
202 krule->listnr != AUDIT_FILTER_EXIT ||
204 krule->inode_f || krule->watch || krule->tree)
207 watch = audit_init_watch(path);
209 return PTR_ERR(watch);
211 audit_get_watch(watch);
212 krule->watch = watch;
217 /* Duplicate the given audit watch. The new watch's rules list is initialized
218 * to an empty list and wlist is undefined. */
219 static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
222 struct audit_watch *new;
224 path = kstrdup(old->path, GFP_KERNEL);
226 return ERR_PTR(-ENOMEM);
228 new = audit_init_watch(path);
236 audit_get_parent(old->parent);
237 new->parent = old->parent;
243 static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
246 struct audit_buffer *ab;
247 ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
248 audit_log_format(ab, "auid=%u ses=%u op=",
249 audit_get_loginuid(current),
250 audit_get_sessionid(current));
251 audit_log_string(ab, op);
252 audit_log_format(ab, " path=");
253 audit_log_untrustedstring(ab, w->path);
254 audit_log_key(ab, r->filterkey);
255 audit_log_format(ab, " list=%d res=1", r->listnr);
260 /* Update inode info in audit rules based on filesystem event. */
261 static void audit_update_watch(struct audit_parent *parent,
262 const char *dname, dev_t dev,
263 unsigned long ino, unsigned invalidating)
265 struct audit_watch *owatch, *nwatch, *nextw;
266 struct audit_krule *r, *nextr;
267 struct audit_entry *oentry, *nentry;
269 mutex_lock(&audit_filter_mutex);
270 /* Run all of the watches on this parent looking for the one that
271 * matches the given dname */
272 list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
273 if (audit_compare_dname_path(dname, owatch->path, NULL))
276 /* If the update involves invalidating rules, do the inode-based
277 * filtering now, so we don't omit records. */
278 if (invalidating && !audit_dummy_context())
279 audit_filter_inodes(current, current->audit_context);
281 /* updating ino will likely change which audit_hash_list we
282 * are on so we need a new watch for the new list */
283 nwatch = audit_dupe_watch(owatch);
284 if (IS_ERR(nwatch)) {
285 mutex_unlock(&audit_filter_mutex);
286 audit_panic("error updating watch, skipping");
292 list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
294 oentry = container_of(r, struct audit_entry, rule);
295 list_del(&oentry->rule.rlist);
296 list_del_rcu(&oentry->list);
298 nentry = audit_dupe_rule(&oentry->rule);
299 if (IS_ERR(nentry)) {
300 list_del(&oentry->rule.list);
301 audit_panic("error updating watch, removing");
303 int h = audit_hash_ino((u32)ino);
306 * nentry->rule.watch == oentry->rule.watch so
307 * we must drop that reference and set it to our
310 audit_put_watch(nentry->rule.watch);
311 audit_get_watch(nwatch);
312 nentry->rule.watch = nwatch;
313 list_add(&nentry->rule.rlist, &nwatch->rules);
314 list_add_rcu(&nentry->list, &audit_inode_hash[h]);
315 list_replace(&oentry->rule.list,
319 audit_watch_log_rule_change(r, owatch, "updated rules");
321 call_rcu(&oentry->rcu, audit_free_rule_rcu);
324 audit_remove_watch(owatch);
325 goto add_watch_to_parent; /* event applies to a single watch */
327 mutex_unlock(&audit_filter_mutex);
331 list_add(&nwatch->wlist, &parent->watches);
332 mutex_unlock(&audit_filter_mutex);
336 /* Remove all watches & rules associated with a parent that is going away. */
337 static void audit_remove_parent_watches(struct audit_parent *parent)
339 struct audit_watch *w, *nextw;
340 struct audit_krule *r, *nextr;
341 struct audit_entry *e;
343 mutex_lock(&audit_filter_mutex);
344 list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
345 list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
346 e = container_of(r, struct audit_entry, rule);
347 audit_watch_log_rule_change(r, w, "remove rule");
350 list_del_rcu(&e->list);
351 call_rcu(&e->rcu, audit_free_rule_rcu);
353 audit_remove_watch(w);
355 mutex_unlock(&audit_filter_mutex);
357 fsnotify_destroy_mark(&parent->mark);
359 fsnotify_recalc_group_mask(audit_watch_group);
363 /* Get path information necessary for adding watches. */
364 static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw)
366 struct nameidata *ndparent, *ndwatch;
369 ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL);
370 if (unlikely(!ndparent))
373 ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL);
374 if (unlikely(!ndwatch)) {
379 err = path_lookup(path, LOOKUP_PARENT, ndparent);
386 err = path_lookup(path, 0, ndwatch);
398 /* Release resources used for watch path information. */
399 static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw)
402 path_put(&ndp->path);
406 path_put(&ndw->path);
411 /* Associate the given rule with an existing parent.
412 * Caller must hold audit_filter_mutex. */
413 static void audit_add_to_parent(struct audit_krule *krule,
414 struct audit_parent *parent)
416 struct audit_watch *w, *watch = krule->watch;
419 BUG_ON(!mutex_is_locked(&audit_filter_mutex));
421 list_for_each_entry(w, &parent->watches, wlist) {
422 if (strcmp(watch->path, w->path))
427 /* put krule's and initial refs to temporary watch */
428 audit_put_watch(watch);
429 audit_put_watch(watch);
432 krule->watch = watch = w;
437 audit_get_parent(parent);
438 watch->parent = parent;
440 list_add(&watch->wlist, &parent->watches);
442 list_add(&krule->rlist, &watch->rules);
445 /* Find a matching watch entry, or add this one.
446 * Caller must hold audit_filter_mutex. */
447 int audit_add_watch(struct audit_krule *krule, struct list_head **list)
449 struct audit_watch *watch = krule->watch;
450 struct audit_parent *parent;
451 struct nameidata *ndp = NULL, *ndw = NULL;
454 mutex_unlock(&audit_filter_mutex);
456 /* Avoid calling path_lookup under audit_filter_mutex. */
457 ret = audit_get_nd(watch->path, &ndp, &ndw);
459 /* caller expects mutex locked */
460 mutex_lock(&audit_filter_mutex);
464 mutex_lock(&audit_filter_mutex);
466 /* update watch filter fields */
468 watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev;
469 watch->ino = ndw->path.dentry->d_inode->i_ino;
472 /* either find an old parent or attach a new one */
473 parent = audit_find_parent(ndp->path.dentry->d_inode);
475 parent = audit_init_parent(ndp);
476 if (IS_ERR(parent)) {
477 ret = PTR_ERR(parent);
482 audit_add_to_parent(krule, parent);
484 /* match get in audit_find_parent or audit_init_parent */
485 audit_put_parent(parent);
487 h = audit_hash_ino((u32)watch->ino);
488 *list = &audit_inode_hash[h];
490 audit_put_nd(ndp, ndw); /* NULL args OK */
495 void audit_remove_watch_rule(struct audit_krule *krule)
497 struct audit_watch *watch = krule->watch;
498 struct audit_parent *parent = watch->parent;
500 list_del(&krule->rlist);
502 if (list_empty(&watch->rules)) {
503 audit_remove_watch(watch);
505 if (list_empty(&parent->watches)) {
506 audit_get_parent(parent);
507 fsnotify_destroy_mark(&parent->mark);
508 audit_put_parent(parent);
512 fsnotify_recalc_group_mask(audit_watch_group);
516 static bool audit_watch_should_send_event(struct fsnotify_group *group, struct inode *inode,
517 struct vfsmount *mnt, __u32 mask, void *data,
520 struct fsnotify_mark *entry;
523 spin_lock(&inode->i_lock);
524 entry = fsnotify_find_mark(group, inode);
525 spin_unlock(&inode->i_lock);
529 mask = (mask & ~FS_EVENT_ON_CHILD);
530 send = (entry->mask & mask);
532 /* find took a reference */
533 fsnotify_put_mark(entry);
538 /* Update watch data in audit rules based on fsnotify events. */
539 static int audit_watch_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
542 __u32 mask = event->mask;
543 const char *dname = event->file_name;
544 struct audit_parent *parent;
546 BUG_ON(group != audit_watch_group);
548 parent = audit_find_parent(event->to_tell);
549 if (unlikely(!parent))
552 switch (event->data_type) {
553 case (FSNOTIFY_EVENT_PATH):
554 inode = event->path.dentry->d_inode;
556 case (FSNOTIFY_EVENT_INODE):
557 inode = event->inode;
565 if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
566 audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
567 else if (mask & (FS_DELETE|FS_MOVED_FROM))
568 audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1);
569 else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
570 audit_remove_parent_watches(parent);
571 /* moved put_inotify_watch to freeing mark */
573 /* matched the ref taken by audit_find_parent */
574 audit_put_parent(parent);
579 static const struct fsnotify_ops audit_watch_fsnotify_ops = {
580 .should_send_event = audit_watch_should_send_event,
581 .handle_event = audit_watch_handle_event,
582 .free_group_priv = NULL,
583 .freeing_mark = NULL,
584 .free_event_priv = NULL,
587 static int __init audit_watch_init(void)
589 audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops);
590 if (IS_ERR(audit_watch_group)) {
591 audit_watch_group = NULL;
592 audit_panic("cannot create audit fsnotify group");
596 device_initcall(audit_watch_init);