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Eric Pariscfcad622009-06-11 14:31:36 -04001/* 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/inotify.h>
31#include <linux/security.h>
32#include "audit.h"
33
34/*
35 * Reference counting:
36 *
37 * audit_parent: lifetime is from audit_init_parent() to receipt of an IN_IGNORED
38 * event. Each audit_watch holds a reference to its associated parent.
39 *
40 * audit_watch: if added to lists, lifetime is from audit_init_watch() to
41 * audit_remove_watch(). Additionally, an audit_watch may exist
42 * temporarily to assist in searching existing filter data. Each
43 * audit_krule holds a reference to its associated watch.
44 */
45
46struct audit_watch {
47 atomic_t count; /* reference count */
Eric Pariscfcad622009-06-11 14:31:36 -040048 dev_t dev; /* associated superblock device */
Eric Parise08b0612009-08-07 16:54:23 -040049 char *path; /* insertion path */
Eric Pariscfcad622009-06-11 14:31:36 -040050 unsigned long ino; /* associated inode number */
51 struct audit_parent *parent; /* associated parent */
52 struct list_head wlist; /* entry in parent->watches list */
53 struct list_head rules; /* associated rules */
54};
55
56struct audit_parent {
57 struct list_head ilist; /* entry in inotify registration list */
58 struct list_head watches; /* associated watches */
59 struct inotify_watch wdata; /* inotify watch data */
60 unsigned flags; /* status flags */
61};
62
63/* Inotify handle. */
64struct inotify_handle *audit_ih;
65
66/*
67 * audit_parent status flags:
68 *
69 * AUDIT_PARENT_INVALID - set anytime rules/watches are auto-removed due to
70 * a filesystem event to ensure we're adding audit watches to a valid parent.
71 * Technically not needed for IN_DELETE_SELF or IN_UNMOUNT events, as we cannot
72 * receive them while we have nameidata, but must be used for IN_MOVE_SELF which
73 * we can receive while holding nameidata.
74 */
75#define AUDIT_PARENT_INVALID 0x001
76
77/* Inotify events we care about. */
78#define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF
79
80static void audit_free_parent(struct inotify_watch *i_watch)
81{
82 struct audit_parent *parent;
83
84 parent = container_of(i_watch, struct audit_parent, wdata);
85 WARN_ON(!list_empty(&parent->watches));
86 kfree(parent);
87}
88
89void audit_get_watch(struct audit_watch *watch)
90{
91 atomic_inc(&watch->count);
92}
93
94void audit_put_watch(struct audit_watch *watch)
95{
96 if (atomic_dec_and_test(&watch->count)) {
97 WARN_ON(watch->parent);
98 WARN_ON(!list_empty(&watch->rules));
99 kfree(watch->path);
100 kfree(watch);
101 }
102}
103
104void audit_remove_watch(struct audit_watch *watch)
105{
106 list_del(&watch->wlist);
107 put_inotify_watch(&watch->parent->wdata);
108 watch->parent = NULL;
109 audit_put_watch(watch); /* match initial get */
110}
111
112char *audit_watch_path(struct audit_watch *watch)
113{
114 return watch->path;
115}
116
117struct list_head *audit_watch_rules(struct audit_watch *watch)
118{
119 return &watch->rules;
120}
121
122unsigned long audit_watch_inode(struct audit_watch *watch)
123{
124 return watch->ino;
125}
126
127dev_t audit_watch_dev(struct audit_watch *watch)
128{
129 return watch->dev;
130}
131
132/* Initialize a parent watch entry. */
133static struct audit_parent *audit_init_parent(struct nameidata *ndp)
134{
135 struct audit_parent *parent;
136 s32 wd;
137
138 parent = kzalloc(sizeof(*parent), GFP_KERNEL);
139 if (unlikely(!parent))
140 return ERR_PTR(-ENOMEM);
141
142 INIT_LIST_HEAD(&parent->watches);
143 parent->flags = 0;
144
145 inotify_init_watch(&parent->wdata);
146 /* grab a ref so inotify watch hangs around until we take audit_filter_mutex */
147 get_inotify_watch(&parent->wdata);
148 wd = inotify_add_watch(audit_ih, &parent->wdata,
149 ndp->path.dentry->d_inode, AUDIT_IN_WATCH);
150 if (wd < 0) {
151 audit_free_parent(&parent->wdata);
152 return ERR_PTR(wd);
153 }
154
155 return parent;
156}
157
158/* Initialize a watch entry. */
159static struct audit_watch *audit_init_watch(char *path)
160{
161 struct audit_watch *watch;
162
163 watch = kzalloc(sizeof(*watch), GFP_KERNEL);
164 if (unlikely(!watch))
165 return ERR_PTR(-ENOMEM);
166
167 INIT_LIST_HEAD(&watch->rules);
168 atomic_set(&watch->count, 1);
169 watch->path = path;
170 watch->dev = (dev_t)-1;
171 watch->ino = (unsigned long)-1;
172
173 return watch;
174}
175
176/* Translate a watch string to kernel respresentation. */
177int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
178{
179 struct audit_watch *watch;
180
181 if (!audit_ih)
182 return -EOPNOTSUPP;
183
184 if (path[0] != '/' || path[len-1] == '/' ||
185 krule->listnr != AUDIT_FILTER_EXIT ||
186 op != Audit_equal ||
187 krule->inode_f || krule->watch || krule->tree)
188 return -EINVAL;
189
190 watch = audit_init_watch(path);
191 if (IS_ERR(watch))
192 return PTR_ERR(watch);
193
194 audit_get_watch(watch);
195 krule->watch = watch;
196
197 return 0;
198}
199
200/* Duplicate the given audit watch. The new watch's rules list is initialized
201 * to an empty list and wlist is undefined. */
202static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
203{
204 char *path;
205 struct audit_watch *new;
206
207 path = kstrdup(old->path, GFP_KERNEL);
208 if (unlikely(!path))
209 return ERR_PTR(-ENOMEM);
210
211 new = audit_init_watch(path);
212 if (IS_ERR(new)) {
213 kfree(path);
214 goto out;
215 }
216
217 new->dev = old->dev;
218 new->ino = old->ino;
219 get_inotify_watch(&old->parent->wdata);
220 new->parent = old->parent;
221
222out:
223 return new;
224}
225
226static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
227{
228 if (audit_enabled) {
229 struct audit_buffer *ab;
230 ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
231 audit_log_format(ab, "auid=%u ses=%u op=",
232 audit_get_loginuid(current),
233 audit_get_sessionid(current));
234 audit_log_string(ab, op);
235 audit_log_format(ab, " path=");
236 audit_log_untrustedstring(ab, w->path);
Eric Paris9d960982009-06-11 14:31:37 -0400237 audit_log_key(ab, r->filterkey);
Eric Pariscfcad622009-06-11 14:31:36 -0400238 audit_log_format(ab, " list=%d res=1", r->listnr);
239 audit_log_end(ab);
240 }
241}
242
243/* Update inode info in audit rules based on filesystem event. */
244static void audit_update_watch(struct audit_parent *parent,
245 const char *dname, dev_t dev,
246 unsigned long ino, unsigned invalidating)
247{
248 struct audit_watch *owatch, *nwatch, *nextw;
249 struct audit_krule *r, *nextr;
250 struct audit_entry *oentry, *nentry;
251
252 mutex_lock(&audit_filter_mutex);
253 list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
254 if (audit_compare_dname_path(dname, owatch->path, NULL))
255 continue;
256
257 /* If the update involves invalidating rules, do the inode-based
258 * filtering now, so we don't omit records. */
259 if (invalidating && current->audit_context)
260 audit_filter_inodes(current, current->audit_context);
261
262 nwatch = audit_dupe_watch(owatch);
263 if (IS_ERR(nwatch)) {
264 mutex_unlock(&audit_filter_mutex);
265 audit_panic("error updating watch, skipping");
266 return;
267 }
268 nwatch->dev = dev;
269 nwatch->ino = ino;
270
271 list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
272
273 oentry = container_of(r, struct audit_entry, rule);
274 list_del(&oentry->rule.rlist);
275 list_del_rcu(&oentry->list);
276
277 nentry = audit_dupe_rule(&oentry->rule, nwatch);
278 if (IS_ERR(nentry)) {
279 list_del(&oentry->rule.list);
280 audit_panic("error updating watch, removing");
281 } else {
282 int h = audit_hash_ino((u32)ino);
283 list_add(&nentry->rule.rlist, &nwatch->rules);
284 list_add_rcu(&nentry->list, &audit_inode_hash[h]);
285 list_replace(&oentry->rule.list,
286 &nentry->rule.list);
287 }
288
289 audit_watch_log_rule_change(r, owatch, "updated rules");
290
291 call_rcu(&oentry->rcu, audit_free_rule_rcu);
292 }
293
294 audit_remove_watch(owatch);
295 goto add_watch_to_parent; /* event applies to a single watch */
296 }
297 mutex_unlock(&audit_filter_mutex);
298 return;
299
300add_watch_to_parent:
301 list_add(&nwatch->wlist, &parent->watches);
302 mutex_unlock(&audit_filter_mutex);
303 return;
304}
305
306/* Remove all watches & rules associated with a parent that is going away. */
307static void audit_remove_parent_watches(struct audit_parent *parent)
308{
309 struct audit_watch *w, *nextw;
310 struct audit_krule *r, *nextr;
311 struct audit_entry *e;
312
313 mutex_lock(&audit_filter_mutex);
314 parent->flags |= AUDIT_PARENT_INVALID;
315 list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
316 list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
317 e = container_of(r, struct audit_entry, rule);
318 audit_watch_log_rule_change(r, w, "remove rule");
319 list_del(&r->rlist);
320 list_del(&r->list);
321 list_del_rcu(&e->list);
322 call_rcu(&e->rcu, audit_free_rule_rcu);
323 }
324 audit_remove_watch(w);
325 }
326 mutex_unlock(&audit_filter_mutex);
327}
328
329/* Unregister inotify watches for parents on in_list.
330 * Generates an IN_IGNORED event. */
331void audit_inotify_unregister(struct list_head *in_list)
332{
333 struct audit_parent *p, *n;
334
335 list_for_each_entry_safe(p, n, in_list, ilist) {
336 list_del(&p->ilist);
337 inotify_rm_watch(audit_ih, &p->wdata);
338 /* the unpin matching the pin in audit_do_del_rule() */
339 unpin_inotify_watch(&p->wdata);
340 }
341}
342
343/* Get path information necessary for adding watches. */
Eric Paris35fe4d02009-06-11 14:31:36 -0400344static int audit_get_nd(char *path, struct nameidata **ndp, struct nameidata **ndw)
Eric Pariscfcad622009-06-11 14:31:36 -0400345{
346 struct nameidata *ndparent, *ndwatch;
347 int err;
348
349 ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL);
350 if (unlikely(!ndparent))
351 return -ENOMEM;
352
353 ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL);
354 if (unlikely(!ndwatch)) {
355 kfree(ndparent);
356 return -ENOMEM;
357 }
358
359 err = path_lookup(path, LOOKUP_PARENT, ndparent);
360 if (err) {
361 kfree(ndparent);
362 kfree(ndwatch);
363 return err;
364 }
365
366 err = path_lookup(path, 0, ndwatch);
367 if (err) {
368 kfree(ndwatch);
369 ndwatch = NULL;
370 }
371
372 *ndp = ndparent;
373 *ndw = ndwatch;
374
375 return 0;
376}
377
378/* Release resources used for watch path information. */
Eric Paris35fe4d02009-06-11 14:31:36 -0400379static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw)
Eric Pariscfcad622009-06-11 14:31:36 -0400380{
381 if (ndp) {
382 path_put(&ndp->path);
383 kfree(ndp);
384 }
385 if (ndw) {
386 path_put(&ndw->path);
387 kfree(ndw);
388 }
389}
390
391/* Associate the given rule with an existing parent inotify_watch.
392 * Caller must hold audit_filter_mutex. */
393static void audit_add_to_parent(struct audit_krule *krule,
394 struct audit_parent *parent)
395{
396 struct audit_watch *w, *watch = krule->watch;
397 int watch_found = 0;
398
399 list_for_each_entry(w, &parent->watches, wlist) {
400 if (strcmp(watch->path, w->path))
401 continue;
402
403 watch_found = 1;
404
405 /* put krule's and initial refs to temporary watch */
406 audit_put_watch(watch);
407 audit_put_watch(watch);
408
409 audit_get_watch(w);
410 krule->watch = watch = w;
411 break;
412 }
413
414 if (!watch_found) {
415 get_inotify_watch(&parent->wdata);
416 watch->parent = parent;
417
418 list_add(&watch->wlist, &parent->watches);
419 }
420 list_add(&krule->rlist, &watch->rules);
421}
422
423/* Find a matching watch entry, or add this one.
424 * Caller must hold audit_filter_mutex. */
Eric Paris35fe4d02009-06-11 14:31:36 -0400425int audit_add_watch(struct audit_krule *krule)
Eric Pariscfcad622009-06-11 14:31:36 -0400426{
427 struct audit_watch *watch = krule->watch;
428 struct inotify_watch *i_watch;
429 struct audit_parent *parent;
Eric Paris35fe4d02009-06-11 14:31:36 -0400430 struct nameidata *ndp = NULL, *ndw = NULL;
Eric Pariscfcad622009-06-11 14:31:36 -0400431 int ret = 0;
432
Eric Paris35fe4d02009-06-11 14:31:36 -0400433 mutex_unlock(&audit_filter_mutex);
434
435 /* Avoid calling path_lookup under audit_filter_mutex. */
436 ret = audit_get_nd(watch->path, &ndp, &ndw);
437 if (ret) {
438 /* caller expects mutex locked */
439 mutex_lock(&audit_filter_mutex);
440 goto error;
441 }
442
Eric Pariscfcad622009-06-11 14:31:36 -0400443 /* update watch filter fields */
444 if (ndw) {
445 watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev;
446 watch->ino = ndw->path.dentry->d_inode->i_ino;
447 }
448
449 /* The audit_filter_mutex must not be held during inotify calls because
450 * we hold it during inotify event callback processing. If an existing
451 * inotify watch is found, inotify_find_watch() grabs a reference before
452 * returning.
453 */
Eric Pariscfcad622009-06-11 14:31:36 -0400454 if (inotify_find_watch(audit_ih, ndp->path.dentry->d_inode,
455 &i_watch) < 0) {
456 parent = audit_init_parent(ndp);
457 if (IS_ERR(parent)) {
458 /* caller expects mutex locked */
459 mutex_lock(&audit_filter_mutex);
Eric Paris35fe4d02009-06-11 14:31:36 -0400460 ret = PTR_ERR(parent);
461 goto error;
Eric Pariscfcad622009-06-11 14:31:36 -0400462 }
463 } else
464 parent = container_of(i_watch, struct audit_parent, wdata);
465
466 mutex_lock(&audit_filter_mutex);
467
468 /* parent was moved before we took audit_filter_mutex */
469 if (parent->flags & AUDIT_PARENT_INVALID)
470 ret = -ENOENT;
471 else
472 audit_add_to_parent(krule, parent);
473
474 /* match get in audit_init_parent or inotify_find_watch */
475 put_inotify_watch(&parent->wdata);
Eric Paris35fe4d02009-06-11 14:31:36 -0400476
477error:
478 audit_put_nd(ndp, ndw); /* NULL args OK */
Eric Pariscfcad622009-06-11 14:31:36 -0400479 return ret;
Eric Paris35fe4d02009-06-11 14:31:36 -0400480
Eric Pariscfcad622009-06-11 14:31:36 -0400481}
482
483void audit_remove_watch_rule(struct audit_krule *krule, struct list_head *list)
484{
485 struct audit_watch *watch = krule->watch;
486 struct audit_parent *parent = watch->parent;
487
488 list_del(&krule->rlist);
489
490 if (list_empty(&watch->rules)) {
491 audit_remove_watch(watch);
492
493 if (list_empty(&parent->watches)) {
494 /* Put parent on the inotify un-registration
495 * list. Grab a reference before releasing
496 * audit_filter_mutex, to be released in
497 * audit_inotify_unregister().
498 * If filesystem is going away, just leave
499 * the sucker alone, eviction will take
500 * care of it. */
501 if (pin_inotify_watch(&parent->wdata))
502 list_add(&parent->ilist, list);
503 }
504 }
505}
506
507/* Update watch data in audit rules based on inotify events. */
508static void audit_handle_ievent(struct inotify_watch *i_watch, u32 wd, u32 mask,
509 u32 cookie, const char *dname, struct inode *inode)
510{
511 struct audit_parent *parent;
512
513 parent = container_of(i_watch, struct audit_parent, wdata);
514
515 if (mask & (IN_CREATE|IN_MOVED_TO) && inode)
516 audit_update_watch(parent, dname, inode->i_sb->s_dev,
517 inode->i_ino, 0);
518 else if (mask & (IN_DELETE|IN_MOVED_FROM))
519 audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1);
520 /* inotify automatically removes the watch and sends IN_IGNORED */
521 else if (mask & (IN_DELETE_SELF|IN_UNMOUNT))
522 audit_remove_parent_watches(parent);
523 /* inotify does not remove the watch, so remove it manually */
524 else if(mask & IN_MOVE_SELF) {
525 audit_remove_parent_watches(parent);
526 inotify_remove_watch_locked(audit_ih, i_watch);
527 } else if (mask & IN_IGNORED)
528 put_inotify_watch(i_watch);
529}
530
531static const struct inotify_operations audit_inotify_ops = {
532 .handle_event = audit_handle_ievent,
533 .destroy_watch = audit_free_parent,
534};
535
536static int __init audit_watch_init(void)
537{
538 audit_ih = inotify_init(&audit_inotify_ops);
539 if (IS_ERR(audit_ih))
540 audit_panic("cannot initialize inotify handle");
541 return 0;
542}
543subsys_initcall(audit_watch_init);