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path: root/kernel/audit_watch.c (plain)
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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/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/sched.h>
32#include <linux/slab.h>
33#include <linux/security.h>
34#include "audit.h"
35
36/*
37 * Reference counting:
38 *
39 * audit_parent: lifetime is from audit_init_parent() to receipt of an FS_IGNORED
40 * event. Each audit_watch holds a reference to its associated parent.
41 *
42 * audit_watch: if added to lists, lifetime is from audit_init_watch() to
43 * audit_remove_watch(). Additionally, an audit_watch may exist
44 * temporarily to assist in searching existing filter data. Each
45 * audit_krule holds a reference to its associated watch.
46 */
47
48struct audit_watch {
49 atomic_t count; /* reference count */
50 dev_t dev; /* associated superblock device */
51 char *path; /* insertion path */
52 unsigned long ino; /* associated inode number */
53 struct audit_parent *parent; /* associated parent */
54 struct list_head wlist; /* entry in parent->watches list */
55 struct list_head rules; /* anchor for krule->rlist */
56};
57
58struct audit_parent {
59 struct list_head watches; /* anchor for audit_watch->wlist */
60 struct fsnotify_mark mark; /* fsnotify mark on the inode */
61};
62
63/* fsnotify handle. */
64static struct fsnotify_group *audit_watch_group;
65
66/* fsnotify events we care about. */
67#define AUDIT_FS_WATCH (FS_MOVE | FS_CREATE | FS_DELETE | FS_DELETE_SELF |\
68 FS_MOVE_SELF | FS_EVENT_ON_CHILD)
69
70static void audit_free_parent(struct audit_parent *parent)
71{
72 WARN_ON(!list_empty(&parent->watches));
73 kfree(parent);
74}
75
76static void audit_watch_free_mark(struct fsnotify_mark *entry)
77{
78 struct audit_parent *parent;
79
80 parent = container_of(entry, struct audit_parent, mark);
81 audit_free_parent(parent);
82}
83
84static void audit_get_parent(struct audit_parent *parent)
85{
86 if (likely(parent))
87 fsnotify_get_mark(&parent->mark);
88}
89
90static void audit_put_parent(struct audit_parent *parent)
91{
92 if (likely(parent))
93 fsnotify_put_mark(&parent->mark);
94}
95
96/*
97 * Find and return the audit_parent on the given inode. If found a reference
98 * is taken on this parent.
99 */
100static inline struct audit_parent *audit_find_parent(struct inode *inode)
101{
102 struct audit_parent *parent = NULL;
103 struct fsnotify_mark *entry;
104
105 entry = fsnotify_find_inode_mark(audit_watch_group, inode);
106 if (entry)
107 parent = container_of(entry, struct audit_parent, mark);
108
109 return parent;
110}
111
112void audit_get_watch(struct audit_watch *watch)
113{
114 atomic_inc(&watch->count);
115}
116
117void audit_put_watch(struct audit_watch *watch)
118{
119 if (atomic_dec_and_test(&watch->count)) {
120 WARN_ON(watch->parent);
121 WARN_ON(!list_empty(&watch->rules));
122 kfree(watch->path);
123 kfree(watch);
124 }
125}
126
127static void audit_remove_watch(struct audit_watch *watch)
128{
129 list_del(&watch->wlist);
130 audit_put_parent(watch->parent);
131 watch->parent = NULL;
132 audit_put_watch(watch); /* match initial get */
133}
134
135char *audit_watch_path(struct audit_watch *watch)
136{
137 return watch->path;
138}
139
140int audit_watch_compare(struct audit_watch *watch, unsigned long ino, dev_t dev)
141{
142 return (watch->ino != AUDIT_INO_UNSET) &&
143 (watch->ino == ino) &&
144 (watch->dev == dev);
145}
146
147/* Initialize a parent watch entry. */
148static struct audit_parent *audit_init_parent(struct path *path)
149{
150 struct inode *inode = d_backing_inode(path->dentry);
151 struct audit_parent *parent;
152 int ret;
153
154 parent = kzalloc(sizeof(*parent), GFP_KERNEL);
155 if (unlikely(!parent))
156 return ERR_PTR(-ENOMEM);
157
158 INIT_LIST_HEAD(&parent->watches);
159
160 fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
161 parent->mark.mask = AUDIT_FS_WATCH;
162 ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, NULL, 0);
163 if (ret < 0) {
164 audit_free_parent(parent);
165 return ERR_PTR(ret);
166 }
167
168 return parent;
169}
170
171/* Initialize a watch entry. */
172static struct audit_watch *audit_init_watch(char *path)
173{
174 struct audit_watch *watch;
175
176 watch = kzalloc(sizeof(*watch), GFP_KERNEL);
177 if (unlikely(!watch))
178 return ERR_PTR(-ENOMEM);
179
180 INIT_LIST_HEAD(&watch->rules);
181 atomic_set(&watch->count, 1);
182 watch->path = path;
183 watch->dev = AUDIT_DEV_UNSET;
184 watch->ino = AUDIT_INO_UNSET;
185
186 return watch;
187}
188
189/* Translate a watch string to kernel representation. */
190int audit_to_watch(struct audit_krule *krule, char *path, int len, u32 op)
191{
192 struct audit_watch *watch;
193
194 if (!audit_watch_group)
195 return -EOPNOTSUPP;
196
197 if (path[0] != '/' || path[len-1] == '/' ||
198 krule->listnr != AUDIT_FILTER_EXIT ||
199 op != Audit_equal ||
200 krule->inode_f || krule->watch || krule->tree)
201 return -EINVAL;
202
203 watch = audit_init_watch(path);
204 if (IS_ERR(watch))
205 return PTR_ERR(watch);
206
207 krule->watch = watch;
208
209 return 0;
210}
211
212/* Duplicate the given audit watch. The new watch's rules list is initialized
213 * to an empty list and wlist is undefined. */
214static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
215{
216 char *path;
217 struct audit_watch *new;
218
219 path = kstrdup(old->path, GFP_KERNEL);
220 if (unlikely(!path))
221 return ERR_PTR(-ENOMEM);
222
223 new = audit_init_watch(path);
224 if (IS_ERR(new)) {
225 kfree(path);
226 goto out;
227 }
228
229 new->dev = old->dev;
230 new->ino = old->ino;
231 audit_get_parent(old->parent);
232 new->parent = old->parent;
233
234out:
235 return new;
236}
237
238static void audit_watch_log_rule_change(struct audit_krule *r, struct audit_watch *w, char *op)
239{
240 if (audit_enabled) {
241 struct audit_buffer *ab;
242 ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
243 if (unlikely(!ab))
244 return;
245 audit_log_format(ab, "auid=%u ses=%u op=",
246 from_kuid(&init_user_ns, audit_get_loginuid(current)),
247 audit_get_sessionid(current));
248 audit_log_string(ab, op);
249 audit_log_format(ab, " path=");
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
257/* Update inode info in audit rules based on filesystem event. */
258static void audit_update_watch(struct audit_parent *parent,
259 const char *dname, dev_t dev,
260 unsigned long ino, unsigned invalidating)
261{
262 struct audit_watch *owatch, *nwatch, *nextw;
263 struct audit_krule *r, *nextr;
264 struct audit_entry *oentry, *nentry;
265
266 mutex_lock(&audit_filter_mutex);
267 /* Run all of the watches on this parent looking for the one that
268 * matches the given dname */
269 list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
270 if (audit_compare_dname_path(dname, owatch->path,
271 AUDIT_NAME_FULL))
272 continue;
273
274 /* If the update involves invalidating rules, do the inode-based
275 * filtering now, so we don't omit records. */
276 if (invalidating && !audit_dummy_context())
277 audit_filter_inodes(current, current->audit_context);
278
279 /* updating ino will likely change which audit_hash_list we
280 * are on so we need a new watch for the new list */
281 nwatch = audit_dupe_watch(owatch);
282 if (IS_ERR(nwatch)) {
283 mutex_unlock(&audit_filter_mutex);
284 audit_panic("error updating watch, skipping");
285 return;
286 }
287 nwatch->dev = dev;
288 nwatch->ino = ino;
289
290 list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {
291
292 oentry = container_of(r, struct audit_entry, rule);
293 list_del(&oentry->rule.rlist);
294 list_del_rcu(&oentry->list);
295
296 nentry = audit_dupe_rule(&oentry->rule);
297 if (IS_ERR(nentry)) {
298 list_del(&oentry->rule.list);
299 audit_panic("error updating watch, removing");
300 } else {
301 int h = audit_hash_ino((u32)ino);
302
303 /*
304 * nentry->rule.watch == oentry->rule.watch so
305 * we must drop that reference and set it to our
306 * new watch.
307 */
308 audit_put_watch(nentry->rule.watch);
309 audit_get_watch(nwatch);
310 nentry->rule.watch = nwatch;
311 list_add(&nentry->rule.rlist, &nwatch->rules);
312 list_add_rcu(&nentry->list, &audit_inode_hash[h]);
313 list_replace(&oentry->rule.list,
314 &nentry->rule.list);
315 }
316 if (oentry->rule.exe)
317 audit_remove_mark(oentry->rule.exe);
318
319 audit_watch_log_rule_change(r, owatch, "updated_rules");
320
321 call_rcu(&oentry->rcu, audit_free_rule_rcu);
322 }
323
324 audit_remove_watch(owatch);
325 goto add_watch_to_parent; /* event applies to a single watch */
326 }
327 mutex_unlock(&audit_filter_mutex);
328 return;
329
330add_watch_to_parent:
331 list_add(&nwatch->wlist, &parent->watches);
332 mutex_unlock(&audit_filter_mutex);
333 return;
334}
335
336/* Remove all watches & rules associated with a parent that is going away. */
337static void audit_remove_parent_watches(struct audit_parent *parent)
338{
339 struct audit_watch *w, *nextw;
340 struct audit_krule *r, *nextr;
341 struct audit_entry *e;
342
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");
348 if (e->rule.exe)
349 audit_remove_mark(e->rule.exe);
350 list_del(&r->rlist);
351 list_del(&r->list);
352 list_del_rcu(&e->list);
353 call_rcu(&e->rcu, audit_free_rule_rcu);
354 }
355 audit_remove_watch(w);
356 }
357 mutex_unlock(&audit_filter_mutex);
358
359 fsnotify_destroy_mark(&parent->mark, audit_watch_group);
360}
361
362/* Get path information necessary for adding watches. */
363static int audit_get_nd(struct audit_watch *watch, struct path *parent)
364{
365 struct dentry *d = kern_path_locked(watch->path, parent);
366 if (IS_ERR(d))
367 return PTR_ERR(d);
368 inode_unlock(d_backing_inode(parent->dentry));
369 if (d_is_positive(d)) {
370 /* update watch filter fields */
371 watch->dev = d->d_sb->s_dev;
372 watch->ino = d_backing_inode(d)->i_ino;
373 }
374 dput(d);
375 return 0;
376}
377
378/* Associate the given rule with an existing parent.
379 * Caller must hold audit_filter_mutex. */
380static void audit_add_to_parent(struct audit_krule *krule,
381 struct audit_parent *parent)
382{
383 struct audit_watch *w, *watch = krule->watch;
384 int watch_found = 0;
385
386 BUG_ON(!mutex_is_locked(&audit_filter_mutex));
387
388 list_for_each_entry(w, &parent->watches, wlist) {
389 if (strcmp(watch->path, w->path))
390 continue;
391
392 watch_found = 1;
393
394 /* put krule's ref to temporary watch */
395 audit_put_watch(watch);
396
397 audit_get_watch(w);
398 krule->watch = watch = w;
399
400 audit_put_parent(parent);
401 break;
402 }
403
404 if (!watch_found) {
405 watch->parent = parent;
406
407 audit_get_watch(watch);
408 list_add(&watch->wlist, &parent->watches);
409 }
410 list_add(&krule->rlist, &watch->rules);
411}
412
413/* Find a matching watch entry, or add this one.
414 * Caller must hold audit_filter_mutex. */
415int audit_add_watch(struct audit_krule *krule, struct list_head **list)
416{
417 struct audit_watch *watch = krule->watch;
418 struct audit_parent *parent;
419 struct path parent_path;
420 int h, ret = 0;
421
422 /*
423 * When we will be calling audit_add_to_parent, krule->watch might have
424 * been updated and watch might have been freed.
425 * So we need to keep a reference of watch.
426 */
427 audit_get_watch(watch);
428
429 mutex_unlock(&audit_filter_mutex);
430
431 /* Avoid calling path_lookup under audit_filter_mutex. */
432 ret = audit_get_nd(watch, &parent_path);
433
434 /* caller expects mutex locked */
435 mutex_lock(&audit_filter_mutex);
436
437 if (ret) {
438 audit_put_watch(watch);
439 return ret;
440 }
441
442 /* either find an old parent or attach a new one */
443 parent = audit_find_parent(d_backing_inode(parent_path.dentry));
444 if (!parent) {
445 parent = audit_init_parent(&parent_path);
446 if (IS_ERR(parent)) {
447 ret = PTR_ERR(parent);
448 goto error;
449 }
450 }
451
452 audit_add_to_parent(krule, parent);
453
454 h = audit_hash_ino((u32)watch->ino);
455 *list = &audit_inode_hash[h];
456error:
457 path_put(&parent_path);
458 audit_put_watch(watch);
459 return ret;
460}
461
462void audit_remove_watch_rule(struct audit_krule *krule)
463{
464 struct audit_watch *watch = krule->watch;
465 struct audit_parent *parent = watch->parent;
466
467 list_del(&krule->rlist);
468
469 if (list_empty(&watch->rules)) {
470 /*
471 * audit_remove_watch() drops our reference to 'parent' which
472 * can get freed. Grab our own reference to be safe.
473 */
474 audit_get_parent(parent);
475 audit_remove_watch(watch);
476 if (list_empty(&parent->watches))
477 fsnotify_destroy_mark(&parent->mark, audit_watch_group);
478 audit_put_parent(parent);
479 }
480}
481
482/* Update watch data in audit rules based on fsnotify events. */
483static int audit_watch_handle_event(struct fsnotify_group *group,
484 struct inode *to_tell,
485 struct fsnotify_mark *inode_mark,
486 struct fsnotify_mark *vfsmount_mark,
487 u32 mask, void *data, int data_type,
488 const unsigned char *dname, u32 cookie)
489{
490 struct inode *inode;
491 struct audit_parent *parent;
492
493 parent = container_of(inode_mark, struct audit_parent, mark);
494
495 BUG_ON(group != audit_watch_group);
496
497 switch (data_type) {
498 case (FSNOTIFY_EVENT_PATH):
499 inode = d_backing_inode(((struct path *)data)->dentry);
500 break;
501 case (FSNOTIFY_EVENT_INODE):
502 inode = (struct inode *)data;
503 break;
504 default:
505 BUG();
506 inode = NULL;
507 break;
508 };
509
510 if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
511 audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
512 else if (mask & (FS_DELETE|FS_MOVED_FROM))
513 audit_update_watch(parent, dname, AUDIT_DEV_UNSET, AUDIT_INO_UNSET, 1);
514 else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
515 audit_remove_parent_watches(parent);
516
517 return 0;
518}
519
520static const struct fsnotify_ops audit_watch_fsnotify_ops = {
521 .handle_event = audit_watch_handle_event,
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 = exe_file->f_inode->i_ino;
564 dev = exe_file->f_inode->i_sb->s_dev;
565 fput(exe_file);
566 return audit_mark_compare(mark, ino, dev);
567}
568
generated by cgit at 2024-05-18 16:40:10 (GMT)