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 ilist; /* tmp list used to free parents */
59 struct list_head watches; /* anchor for audit_watch->wlist */
60 struct fsnotify_mark_entry mark; /* fsnotify mark on the inode */
61 unsigned flags; /* status flags */
64 /* fsnotify handle. */
65 struct fsnotify_group *audit_watch_group;
68 * audit_parent status flags:
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 FS_DELETE_SELF or FS_UNMOUNT events, as we cannot
73 * receive them while we have nameidata, but must be used for FS_MOVE_SELF which
74 * we can receive while holding nameidata.
76 #define AUDIT_PARENT_INVALID 0x001
78 /* fsnotify events we care about. */
79 #define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
80 FS_MOVE_SELF | FS_EVENT_ON_CHILD)
82 static void audit_free_parent(struct audit_parent *parent)
84 WARN_ON(!list_empty(&parent->watches));
88 static void audit_watch_free_mark(struct fsnotify_mark_entry *entry)
90 struct audit_parent *parent;
92 parent = container_of(entry, struct audit_parent, mark);
93 audit_free_parent(parent);
96 static void audit_get_parent(struct audit_parent *parent)
99 fsnotify_get_mark(&parent->mark);
102 static void audit_put_parent(struct audit_parent *parent)
105 fsnotify_put_mark(&parent->mark);
109 * Find and return the audit_parent on the given inode. If found a reference
110 * is taken on this parent.
112 static inline struct audit_parent *audit_find_parent(struct inode *inode)
114 struct audit_parent *parent = NULL;
115 struct fsnotify_mark_entry *entry;
117 spin_lock(&inode->i_lock);
118 entry = fsnotify_find_mark_entry(audit_watch_group, inode);
119 spin_unlock(&inode->i_lock);
122 parent = container_of(entry, struct audit_parent, mark);
127 void audit_get_watch(struct audit_watch *watch)
129 atomic_inc(&watch->count);
132 void audit_put_watch(struct audit_watch *watch)
134 if (atomic_dec_and_test(&watch->count)) {
135 WARN_ON(watch->parent);
136 WARN_ON(!list_empty(&watch->rules));
142 void audit_remove_watch(struct audit_watch *watch)
144 list_del(&watch->wlist);
145 audit_put_parent(watch->parent);
146 watch->parent = NULL;
147 audit_put_watch(watch); /* match initial get */
150 char *audit_watch_path(struct audit_watch *watch)
155 int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev)
157 return (watch->ino != (unsigned long)-1) &&
158 (watch->ino == ino) &&
162 /* Initialize a parent watch entry. */
163 static struct audit_parent *audit_init_parent(struct nameidata *ndp)
165 struct inode *inode = ndp->path.dentry->d_inode;
166 struct audit_parent *parent;
169 parent = kzalloc(sizeof(*parent), GFP_KERNEL);
170 if (unlikely(!parent))
171 return ERR_PTR(-ENOMEM);
173 INIT_LIST_HEAD(&parent->watches);
176 fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
177 parent->mark.mask = AUDIT_FS_WATCH;
178 /* grab a ref so fsnotify mark hangs around until we take audit_filter_mutex */
179 audit_get_parent(parent);
180 ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode);
182 audit_free_parent(parent);
189 /* Initialize a watch entry. */
190 static struct audit_watch *audit_init_watch(char *path)
192 struct audit_watch *watch;
194 watch = kzalloc(sizeof(*watch), GFP_KERNEL);
195 if (unlikely(!watch))
196 return ERR_PTR(-ENOMEM);
198 INIT_LIST_HEAD(&watch->rules);
199 atomic_set(&watch->count, 1);
201 watch->dev = (dev_t)-1;
202 watch->ino = (unsigned long)-1;
207 /* Translate a watch string to kernel respresentation. */
208 int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
210 struct audit_watch *watch;
212 if (!audit_watch_group)
215 if (path[0] != '/' || path[len-1] == '/' ||
216 krule->listnr != AUDIT_FILTER_EXIT ||
218 krule->inode_f || krule->watch || krule->tree)
221 watch = audit_init_watch(path);
223 return PTR_ERR(watch);
225 audit_get_watch(watch);
226 krule->watch = watch;
231 /* Duplicate the given audit watch. The new watch's rules list is initialized
232 * to an empty list and wlist is undefined. */
233 static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
236 struct audit_watch *new;
238 path = kstrdup(old->path, GFP_KERNEL);
240 return ERR_PTR(-ENOMEM);
242 new = audit_init_watch(path);
250 audit_get_parent(old->parent);
251 new->parent = old->parent;
257 static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
260 struct audit_buffer *ab;
261 ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
262 audit_log_format(ab, "auid=%u ses=%u op=",
263 audit_get_loginuid(current),
264 audit_get_sessionid(current));
265 audit_log_string(ab, op);
266 audit_log_format(ab, " path=");
267 audit_log_untrustedstring(ab, w->path);
268 audit_log_key(ab, r->filterkey);
269 audit_log_format(ab, " list=%d res=1", r->listnr);
274 /* Update inode info in audit rules based on filesystem event. */
275 static void audit_update_watch(struct audit_parent *parent,
276 const char *dname, dev_t dev,
277 unsigned long ino, unsigned invalidating)
279 struct audit_watch *owatch, *nwatch, *nextw;
280 struct audit_krule *r, *nextr;
281 struct audit_entry *oentry, *nentry;
283 mutex_lock(&audit_filter_mutex);
284 /* Run all of the watches on this parent looking for the one that
285 * matches the given dname */
286 list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
287 if (audit_compare_dname_path(dname, owatch->path, NULL))
290 /* If the update involves invalidating rules, do the inode-based
291 * filtering now, so we don't omit records. */
292 if (invalidating && !audit_dummy_context())
293 audit_filter_inodes(current, current->audit_context);
295 /* updating ino will likely change which audit_hash_list we
296 * are on so we need a new watch for the new list */
297 nwatch = audit_dupe_watch(owatch);
298 if (IS_ERR(nwatch)) {
299 mutex_unlock(&audit_filter_mutex);
300 audit_panic("error updating watch, skipping");
306 list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
308 oentry = container_of(r, struct audit_entry, rule);
309 list_del(&oentry->rule.rlist);
310 list_del_rcu(&oentry->list);
312 nentry = audit_dupe_rule(&oentry->rule);
313 if (IS_ERR(nentry)) {
314 list_del(&oentry->rule.list);
315 audit_panic("error updating watch, removing");
317 int h = audit_hash_ino((u32)ino);
320 * nentry->rule.watch == oentry->rule.watch so
321 * we must drop that reference and set it to our
324 audit_put_watch(nentry->rule.watch);
325 audit_get_watch(nwatch);
326 nentry->rule.watch = nwatch;
327 list_add(&nentry->rule.rlist, &nwatch->rules);
328 list_add_rcu(&nentry->list, &audit_inode_hash[h]);
329 list_replace(&oentry->rule.list,
333 audit_watch_log_rule_change(r, owatch, "updated rules");
335 call_rcu(&oentry->rcu, audit_free_rule_rcu);
338 audit_remove_watch(owatch);
339 goto add_watch_to_parent; /* event applies to a single watch */
341 mutex_unlock(&audit_filter_mutex);
345 list_add(&nwatch->wlist, &parent->watches);
346 mutex_unlock(&audit_filter_mutex);
350 /* Remove all watches & rules associated with a parent that is going away. */
351 static void audit_remove_parent_watches(struct audit_parent *parent)
353 struct audit_watch *w, *nextw;
354 struct audit_krule *r, *nextr;
355 struct audit_entry *e;
357 mutex_lock(&audit_filter_mutex);
358 parent->flags |= AUDIT_PARENT_INVALID;
359 list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
360 list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
361 e = container_of(r, struct audit_entry, rule);
362 audit_watch_log_rule_change(r, w, "remove rule");
365 list_del_rcu(&e->list);
366 call_rcu(&e->rcu, audit_free_rule_rcu);
368 audit_remove_watch(w);
370 mutex_unlock(&audit_filter_mutex);
372 fsnotify_destroy_mark_by_entry(&parent->mark);
375 /* Unregister inotify watches for parents on in_list.
376 * Generates an FS_IGNORED event. */
377 void audit_watch_inotify_unregister(struct list_head *in_list)
379 struct audit_parent *p, *n;
381 list_for_each_entry_safe(p, n, in_list, ilist) {
383 fsnotify_destroy_mark_by_entry(&p->mark);
384 /* matches the get in audit_remove_watch_rule() */
389 /* Get path information necessary for adding watches. */
390 static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw)
392 struct nameidata *ndparent, *ndwatch;
395 ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL);
396 if (unlikely(!ndparent))
399 ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL);
400 if (unlikely(!ndwatch)) {
405 err = path_lookup(path, LOOKUP_PARENT, ndparent);
412 err = path_lookup(path, 0, ndwatch);
424 /* Release resources used for watch path information. */
425 static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw)
428 path_put(&ndp->path);
432 path_put(&ndw->path);
437 /* Associate the given rule with an existing parent.
438 * Caller must hold audit_filter_mutex. */
439 static void audit_add_to_parent(struct audit_krule *krule,
440 struct audit_parent *parent)
442 struct audit_watch *w, *watch = krule->watch;
445 BUG_ON(!mutex_is_locked(&audit_filter_mutex));
447 list_for_each_entry(w, &parent->watches, wlist) {
448 if (strcmp(watch->path, w->path))
453 /* put krule's and initial refs to temporary watch */
454 audit_put_watch(watch);
455 audit_put_watch(watch);
458 krule->watch = watch = w;
463 audit_get_parent(parent);
464 watch->parent = parent;
466 list_add(&watch->wlist, &parent->watches);
468 list_add(&krule->rlist, &watch->rules);
471 /* Find a matching watch entry, or add this one.
472 * Caller must hold audit_filter_mutex. */
473 int audit_add_watch(struct audit_krule *krule, struct list_head **list)
475 struct audit_watch *watch = krule->watch;
476 struct audit_parent *parent;
477 struct nameidata *ndp = NULL, *ndw = NULL;
480 mutex_unlock(&audit_filter_mutex);
482 /* Avoid calling path_lookup under audit_filter_mutex. */
483 ret = audit_get_nd(watch->path, &ndp, &ndw);
485 /* caller expects mutex locked */
486 mutex_lock(&audit_filter_mutex);
490 /* update watch filter fields */
492 watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev;
493 watch->ino = ndw->path.dentry->d_inode->i_ino;
496 /* The audit_filter_mutex must not be held during inotify calls because
497 * we hold it during inotify event callback processing. If an existing
498 * inotify watch is found, inotify_find_watch() grabs a reference before
501 parent = audit_find_parent(ndp->path.dentry->d_inode);
503 parent = audit_init_parent(ndp);
504 if (IS_ERR(parent)) {
505 /* caller expects mutex locked */
506 mutex_lock(&audit_filter_mutex);
507 ret = PTR_ERR(parent);
512 mutex_lock(&audit_filter_mutex);
514 /* parent was moved before we took audit_filter_mutex */
515 if (parent->flags & AUDIT_PARENT_INVALID)
518 audit_add_to_parent(krule, parent);
520 /* match get in audit_find_parent or audit_init_parent */
521 audit_put_parent(parent);
523 h = audit_hash_ino((u32)watch->ino);
524 *list = &audit_inode_hash[h];
526 audit_put_nd(ndp, ndw); /* NULL args OK */
531 void audit_remove_watch_rule(struct audit_krule *krule, struct list_head *list)
533 struct audit_watch *watch = krule->watch;
534 struct audit_parent *parent = watch->parent;
536 list_del(&krule->rlist);
538 if (list_empty(&watch->rules)) {
539 audit_remove_watch(watch);
541 if (list_empty(&parent->watches)) {
542 /* Put parent on the un-registration list.
543 * Grab a reference before releasing
544 * audit_filter_mutex, to be released in
545 * audit_watch_inotify_unregister().
546 * If filesystem is going away, just leave
547 * the sucker alone, eviction will take
549 audit_get_parent(parent);
550 list_add(&parent->ilist, list);
555 static bool audit_watch_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)
557 struct fsnotify_mark_entry *entry;
560 spin_lock(&inode->i_lock);
561 entry = fsnotify_find_mark_entry(group, inode);
562 spin_unlock(&inode->i_lock);
566 mask = (mask & ~FS_EVENT_ON_CHILD);
567 send = (entry->mask & mask);
569 /* find took a reference */
570 fsnotify_put_mark(entry);
575 /* Update watch data in audit rules based on fsnotify events. */
576 static int audit_watch_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
579 __u32 mask = event->mask;
580 const char *dname = event->file_name;
581 struct audit_parent *parent;
583 BUG_ON(group != audit_watch_group);
585 parent = audit_find_parent(event->to_tell);
586 if (unlikely(!parent))
589 switch (event->data_type) {
590 case (FSNOTIFY_EVENT_PATH):
591 inode = event->path.dentry->d_inode;
593 case (FSNOTIFY_EVENT_INODE):
594 inode = event->inode;
602 if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
603 audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
604 else if (mask & (FS_DELETE|FS_MOVED_FROM))
605 audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1);
606 else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
607 audit_remove_parent_watches(parent);
608 /* moved put_inotify_watch to freeing mark */
610 /* matched the ref taken by audit_find_parent */
611 audit_put_parent(parent);
616 static void audit_watch_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
618 struct audit_parent *parent;
620 parent = container_of(entry, struct audit_parent, mark);
621 /* taken from audit_handle_ievent & FS_IGNORED please figure out what I match... */
622 audit_put_parent(parent);
625 static const struct fsnotify_ops audit_watch_fsnotify_ops = {
626 .should_send_event = audit_watch_should_send_event,
627 .handle_event = audit_watch_handle_event,
628 .free_group_priv = NULL,
629 .freeing_mark = audit_watch_freeing_mark,
630 .free_event_priv = NULL,
633 static int __init audit_watch_init(void)
635 audit_watch_group = fsnotify_obtain_group(AUDIT_WATCH_GROUP_NUM, AUDIT_FS_WATCH,
636 &audit_watch_fsnotify_ops);
637 if (IS_ERR(audit_watch_group)) {
638 audit_watch_group = NULL;
639 audit_panic("cannot create audit fsnotify group");
643 subsys_initcall(audit_watch_init);