projects/linux·blob v4.17 · refs

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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/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_mark(&parent->mark, inode, NULL, 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 if (audit_enabled) {
242 struct audit_buffer *ab;
243 ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
244 if (unlikely(!ab))
245 return;
246 audit_log_format(ab, "auid=%u ses=%u op=%s",
247 from_kuid(&init_user_ns, audit_get_loginuid(current)),
248 audit_get_sessionid(current), 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 mutex_unlock(&audit_filter_mutex);
423
424 /* Avoid calling path_lookup under audit_filter_mutex. */
425 ret = audit_get_nd(watch, &parent_path);
426
427 /* caller expects mutex locked */
428 mutex_lock(&audit_filter_mutex);
429
430 if (ret)
431 return ret;
432
433 /* either find an old parent or attach a new one */
434 parent = audit_find_parent(d_backing_inode(parent_path.dentry));
435 if (!parent) {
436 parent = audit_init_parent(&parent_path);
437 if (IS_ERR(parent)) {
438 ret = PTR_ERR(parent);
439 goto error;
440 }
441 }
442
443 audit_add_to_parent(krule, parent);
444
445 h = audit_hash_ino((u32)watch->ino);
446 *list = &audit_inode_hash[h];
447error:
448 path_put(&parent_path);
449 return ret;
450}
451
452void audit_remove_watch_rule(struct audit_krule *krule)
453{
454 struct audit_watch *watch = krule->watch;
455 struct audit_parent *parent = watch->parent;
456
457 list_del(&krule->rlist);
458
459 if (list_empty(&watch->rules)) {
460 /*
461 * audit_remove_watch() drops our reference to 'parent' which
462 * can get freed. Grab our own reference to be safe.
463 */
464 audit_get_parent(parent);
465 audit_remove_watch(watch);
466 if (list_empty(&parent->watches))
467 fsnotify_destroy_mark(&parent->mark, audit_watch_group);
468 audit_put_parent(parent);
469 }
470}
471
472/* Update watch data in audit rules based on fsnotify events. */
473static int audit_watch_handle_event(struct fsnotify_group *group,
474 struct inode *to_tell,
475 struct fsnotify_mark *inode_mark,
476 struct fsnotify_mark *vfsmount_mark,
477 u32 mask, const void *data, int data_type,
478 const unsigned char *dname, u32 cookie,
479 struct fsnotify_iter_info *iter_info)
480{
481 const struct inode *inode;
482 struct audit_parent *parent;
483
484 parent = container_of(inode_mark, struct audit_parent, mark);
485
486 BUG_ON(group != audit_watch_group);
487
488 switch (data_type) {
489 case (FSNOTIFY_EVENT_PATH):
490 inode = d_backing_inode(((const struct path *)data)->dentry);
491 break;
492 case (FSNOTIFY_EVENT_INODE):
493 inode = (const struct inode *)data;
494 break;
495 default:
496 BUG();
497 inode = NULL;
498 break;
499 }
500
501 if (mask & (FS_CREATE|FS_MOVED_TO) && inode)
502 audit_update_watch(parent, dname, inode->i_sb->s_dev, inode->i_ino, 0);
503 else if (mask & (FS_DELETE|FS_MOVED_FROM))
504 audit_update_watch(parent, dname, AUDIT_DEV_UNSET, AUDIT_INO_UNSET, 1);
505 else if (mask & (FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF))
506 audit_remove_parent_watches(parent);
507
508 return 0;
509}
510
511static const struct fsnotify_ops audit_watch_fsnotify_ops = {
512 .handle_event = audit_watch_handle_event,
513 .free_mark = audit_watch_free_mark,
514};
515
516static int __init audit_watch_init(void)
517{
518 audit_watch_group = fsnotify_alloc_group(&audit_watch_fsnotify_ops);
519 if (IS_ERR(audit_watch_group)) {
520 audit_watch_group = NULL;
521 audit_panic("cannot create audit fsnotify group");
522 }
523 return 0;
524}
525device_initcall(audit_watch_init);
526
527int audit_dupe_exe(struct audit_krule *new, struct audit_krule *old)
528{
529 struct audit_fsnotify_mark *audit_mark;
530 char *pathname;
531
532 pathname = kstrdup(audit_mark_path(old->exe), GFP_KERNEL);
533 if (!pathname)
534 return -ENOMEM;
535
536 audit_mark = audit_alloc_mark(new, pathname, strlen(pathname));
537 if (IS_ERR(audit_mark)) {
538 kfree(pathname);
539 return PTR_ERR(audit_mark);
540 }
541 new->exe = audit_mark;
542
543 return 0;
544}
545
546int audit_exe_compare(struct task_struct *tsk, struct audit_fsnotify_mark *mark)
547{
548 struct file *exe_file;
549 unsigned long ino;
550 dev_t dev;
551
552 exe_file = get_task_exe_file(tsk);
553 if (!exe_file)
554 return 0;
555 ino = file_inode(exe_file)->i_ino;
556 dev = file_inode(exe_file)->i_sb->s_dev;
557 fput(exe_file);
558 return audit_mark_compare(mark, ino, dev);
559}