1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/fanotify.h>
3 #include <linux/fcntl.h>
4 #include <linux/file.h>
5 #include <linux/fs.h>
6 #include <linux/anon_inodes.h>
7 #include <linux/fsnotify_backend.h>
8 #include <linux/init.h>
9 #include <linux/mount.h>
10 #include <linux/namei.h>
11 #include <linux/poll.h>
12 #include <linux/security.h>
13 #include <linux/syscalls.h>
14 #include <linux/slab.h>
15 #include <linux/types.h>
16 #include <linux/uaccess.h>
17 #include <linux/compat.h>
18 #include <linux/sched/signal.h>
19 #include <linux/memcontrol.h>
20 #include <linux/statfs.h>
21 #include <linux/exportfs.h>
22 #include <linux/pidfd.h>
23
24 #include <asm/ioctls.h>
25
26 #include "../fsnotify.h"
27 #include "../fdinfo.h"
28 #include "fanotify.h"
29
30 #define FANOTIFY_DEFAULT_MAX_EVENTS 16384
31 #define FANOTIFY_OLD_DEFAULT_MAX_MARKS 8192
32 #define FANOTIFY_DEFAULT_MAX_GROUPS 128
33 #define FANOTIFY_DEFAULT_FEE_POOL_SIZE 32
34
35 /*
36 * Legacy fanotify marks limits (8192) is per group and we introduced a tunable
37 * limit of marks per user, similar to inotify. Effectively, the legacy limit
38 * of fanotify marks per user is <max marks per group> * <max groups per user>.
39 * This default limit (1M) also happens to match the increased limit of inotify
40 * max_user_watches since v5.10.
41 */
42 #define FANOTIFY_DEFAULT_MAX_USER_MARKS \
43 (FANOTIFY_OLD_DEFAULT_MAX_MARKS * FANOTIFY_DEFAULT_MAX_GROUPS)
44
45 /*
46 * Most of the memory cost of adding an inode mark is pinning the marked inode.
47 * The size of the filesystem inode struct is not uniform across filesystems,
48 * so double the size of a VFS inode is used as a conservative approximation.
49 */
50 #define INODE_MARK_COST (2 * sizeof(struct inode))
51
52 /* configurable via /proc/sys/fs/fanotify/ */
53 static int fanotify_max_queued_events __read_mostly;
54 static int perm_group_timeout __read_mostly;
55
56 #ifdef CONFIG_SYSCTL
57
58 #include <linux/sysctl.h>
59
60 static long ft_zero = 0;
61 static long ft_int_max = INT_MAX;
62
63 static const struct ctl_table fanotify_table[] = {
64 {
65 .procname = "max_user_groups",
66 .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS],
67 .maxlen = sizeof(long),
68 .mode = 0644,
69 .proc_handler = proc_doulongvec_minmax,
70 .extra1 = &ft_zero,
71 .extra2 = &ft_int_max,
72 },
73 {
74 .procname = "max_user_marks",
75 .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS],
76 .maxlen = sizeof(long),
77 .mode = 0644,
78 .proc_handler = proc_doulongvec_minmax,
79 .extra1 = &ft_zero,
80 .extra2 = &ft_int_max,
81 },
82 {
83 .procname = "max_queued_events",
84 .data = &fanotify_max_queued_events,
85 .maxlen = sizeof(int),
86 .mode = 0644,
87 .proc_handler = proc_dointvec_minmax,
88 .extra1 = SYSCTL_ZERO
89 },
90 {
91 .procname = "watchdog_timeout",
92 .data = &perm_group_timeout,
93 .maxlen = sizeof(int),
94 .mode = 0644,
95 .proc_handler = proc_dointvec_minmax,
96 .extra1 = SYSCTL_ZERO,
97 },
98 };
99
fanotify_sysctls_init(void)100 static void __init fanotify_sysctls_init(void)
101 {
102 register_sysctl("fs/fanotify", fanotify_table);
103 }
104 #else
105 #define fanotify_sysctls_init() do { } while (0)
106 #endif /* CONFIG_SYSCTL */
107
108 static LIST_HEAD(perm_group_list);
109 static DEFINE_SPINLOCK(perm_group_lock);
110 static void perm_group_watchdog(struct work_struct *work);
111 static DECLARE_DELAYED_WORK(perm_group_work, perm_group_watchdog);
112
perm_group_watchdog_schedule(void)113 static void perm_group_watchdog_schedule(void)
114 {
115 int timeout = READ_ONCE(perm_group_timeout);
116
117 if (!timeout)
118 return;
119
120 schedule_delayed_work(&perm_group_work, secs_to_jiffies(timeout));
121 }
122
perm_group_watchdog(struct work_struct * work)123 static void perm_group_watchdog(struct work_struct *work)
124 {
125 struct fsnotify_group *group;
126 struct fanotify_perm_event *event;
127 struct task_struct *task;
128 pid_t failed_pid = 0;
129
130 guard(spinlock)(&perm_group_lock);
131 if (list_empty(&perm_group_list))
132 return;
133
134 list_for_each_entry(group, &perm_group_list,
135 fanotify_data.perm_grp_list) {
136 /*
137 * Ok to test without lock, racing with an addition is
138 * fine, will deal with it next round
139 */
140 if (list_empty(&group->fanotify_data.access_list))
141 continue;
142
143 spin_lock(&group->notification_lock);
144 list_for_each_entry(event, &group->fanotify_data.access_list,
145 fae.fse.list) {
146 if (likely(event->watchdog_cnt == 0)) {
147 event->watchdog_cnt = 1;
148 } else if (event->watchdog_cnt == 1) {
149 /* Report on event only once */
150 event->watchdog_cnt = 2;
151
152 /* Do not report same pid repeatedly */
153 if (event->recv_pid == failed_pid)
154 continue;
155
156 failed_pid = event->recv_pid;
157 rcu_read_lock();
158 task = find_task_by_pid_ns(event->recv_pid,
159 &init_pid_ns);
160 pr_warn_ratelimited(
161 "PID %u (%s) failed to respond to fanotify queue for more than %d seconds\n",
162 event->recv_pid,
163 task ? task->comm : NULL,
164 perm_group_timeout);
165 rcu_read_unlock();
166 }
167 }
168 spin_unlock(&group->notification_lock);
169 }
170 perm_group_watchdog_schedule();
171 }
172
fanotify_perm_watchdog_group_remove(struct fsnotify_group * group)173 static void fanotify_perm_watchdog_group_remove(struct fsnotify_group *group)
174 {
175 if (!list_empty(&group->fanotify_data.perm_grp_list)) {
176 /* Perm event watchdog can no longer scan this group. */
177 spin_lock(&perm_group_lock);
178 list_del_init(&group->fanotify_data.perm_grp_list);
179 spin_unlock(&perm_group_lock);
180 }
181 }
182
fanotify_perm_watchdog_group_add(struct fsnotify_group * group)183 static void fanotify_perm_watchdog_group_add(struct fsnotify_group *group)
184 {
185 if (!perm_group_timeout)
186 return;
187
188 spin_lock(&perm_group_lock);
189 if (list_empty(&group->fanotify_data.perm_grp_list)) {
190 /* Add to perm_group_list for monitoring by watchdog. */
191 if (list_empty(&perm_group_list))
192 perm_group_watchdog_schedule();
193 list_add_tail(&group->fanotify_data.perm_grp_list, &perm_group_list);
194 }
195 spin_unlock(&perm_group_lock);
196 }
197
198 /*
199 * All flags that may be specified in parameter event_f_flags of fanotify_init.
200 *
201 * Internal and external open flags are stored together in field f_flags of
202 * struct file. Only external open flags shall be allowed in event_f_flags.
203 * Internal flags like FMODE_EXEC shall be excluded.
204 */
205 #define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \
206 O_ACCMODE | O_APPEND | O_NONBLOCK | \
207 __O_SYNC | O_DSYNC | O_CLOEXEC | \
208 O_LARGEFILE | O_NOATIME )
209
210 extern const struct fsnotify_ops fanotify_fsnotify_ops;
211
212 struct kmem_cache *fanotify_mark_cache __ro_after_init;
213 struct kmem_cache *fanotify_fid_event_cachep __ro_after_init;
214 struct kmem_cache *fanotify_path_event_cachep __ro_after_init;
215 struct kmem_cache *fanotify_perm_event_cachep __ro_after_init;
216 struct kmem_cache *fanotify_mnt_event_cachep __ro_after_init;
217
218 #define FANOTIFY_EVENT_ALIGN 4
219 #define FANOTIFY_FID_INFO_HDR_LEN \
220 (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle))
221 #define FANOTIFY_PIDFD_INFO_LEN \
222 sizeof(struct fanotify_event_info_pidfd)
223 #define FANOTIFY_ERROR_INFO_LEN \
224 (sizeof(struct fanotify_event_info_error))
225 #define FANOTIFY_RANGE_INFO_LEN \
226 (sizeof(struct fanotify_event_info_range))
227 #define FANOTIFY_MNT_INFO_LEN \
228 (sizeof(struct fanotify_event_info_mnt))
229
fanotify_fid_info_len(int fh_len,int name_len)230 static int fanotify_fid_info_len(int fh_len, int name_len)
231 {
232 int info_len = fh_len;
233
234 if (name_len)
235 info_len += name_len + 1;
236
237 return roundup(FANOTIFY_FID_INFO_HDR_LEN + info_len,
238 FANOTIFY_EVENT_ALIGN);
239 }
240
241 /* FAN_RENAME may have one or two dir+name info records */
fanotify_dir_name_info_len(struct fanotify_event * event)242 static int fanotify_dir_name_info_len(struct fanotify_event *event)
243 {
244 struct fanotify_info *info = fanotify_event_info(event);
245 int dir_fh_len = fanotify_event_dir_fh_len(event);
246 int dir2_fh_len = fanotify_event_dir2_fh_len(event);
247 int info_len = 0;
248
249 if (dir_fh_len)
250 info_len += fanotify_fid_info_len(dir_fh_len,
251 info->name_len);
252 if (dir2_fh_len)
253 info_len += fanotify_fid_info_len(dir2_fh_len,
254 info->name2_len);
255
256 return info_len;
257 }
258
fanotify_event_len(unsigned int info_mode,struct fanotify_event * event)259 static size_t fanotify_event_len(unsigned int info_mode,
260 struct fanotify_event *event)
261 {
262 size_t event_len = FAN_EVENT_METADATA_LEN;
263 int fh_len;
264 int dot_len = 0;
265
266 if (fanotify_is_error_event(event->mask))
267 event_len += FANOTIFY_ERROR_INFO_LEN;
268
269 if (fanotify_event_has_any_dir_fh(event)) {
270 event_len += fanotify_dir_name_info_len(event);
271 } else if ((info_mode & FAN_REPORT_NAME) &&
272 (event->mask & FAN_ONDIR)) {
273 /*
274 * With group flag FAN_REPORT_NAME, if name was not recorded in
275 * event on a directory, we will report the name ".".
276 */
277 dot_len = 1;
278 }
279
280 if (fanotify_event_has_object_fh(event)) {
281 fh_len = fanotify_event_object_fh_len(event);
282 event_len += fanotify_fid_info_len(fh_len, dot_len);
283 }
284 if (fanotify_is_mnt_event(event->mask))
285 event_len += FANOTIFY_MNT_INFO_LEN;
286
287 if (info_mode & FAN_REPORT_PIDFD)
288 event_len += FANOTIFY_PIDFD_INFO_LEN;
289
290 if (fanotify_event_has_access_range(event))
291 event_len += FANOTIFY_RANGE_INFO_LEN;
292
293 return event_len;
294 }
295
296 /*
297 * Remove an hashed event from merge hash table.
298 */
fanotify_unhash_event(struct fsnotify_group * group,struct fanotify_event * event)299 static void fanotify_unhash_event(struct fsnotify_group *group,
300 struct fanotify_event *event)
301 {
302 assert_spin_locked(&group->notification_lock);
303
304 pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
305 group, event, fanotify_event_hash_bucket(group, event));
306
307 if (WARN_ON_ONCE(hlist_unhashed(&event->merge_list)))
308 return;
309
310 hlist_del_init(&event->merge_list);
311 }
312
313 /*
314 * Get an fanotify notification event if one exists and is small
315 * enough to fit in "count". Return an error pointer if the count
316 * is not large enough. When permission event is dequeued, its state is
317 * updated accordingly.
318 */
get_one_event(struct fsnotify_group * group,size_t count)319 static struct fanotify_event *get_one_event(struct fsnotify_group *group,
320 size_t count)
321 {
322 size_t event_size;
323 struct fanotify_event *event = NULL;
324 struct fsnotify_event *fsn_event;
325 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
326
327 pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
328
329 spin_lock(&group->notification_lock);
330 fsn_event = fsnotify_peek_first_event(group);
331 if (!fsn_event)
332 goto out;
333
334 event = FANOTIFY_E(fsn_event);
335 event_size = fanotify_event_len(info_mode, event);
336
337 if (event_size > count) {
338 event = ERR_PTR(-EINVAL);
339 goto out;
340 }
341
342 /*
343 * Held the notification_lock the whole time, so this is the
344 * same event we peeked above.
345 */
346 fsnotify_remove_first_event(group);
347 if (fanotify_is_perm_event(event->mask))
348 FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED;
349 if (fanotify_is_hashed_event(event->mask))
350 fanotify_unhash_event(group, event);
351 out:
352 spin_unlock(&group->notification_lock);
353 return event;
354 }
355
create_fd(struct fsnotify_group * group,const struct path * path,struct file ** file)356 static int create_fd(struct fsnotify_group *group, const struct path *path,
357 struct file **file)
358 {
359 int client_fd;
360 struct file *new_file;
361
362 client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
363 if (client_fd < 0)
364 return client_fd;
365
366 /*
367 * We provide an fd for the userspace program, so it could access the
368 * file without generating fanotify events itself.
369 */
370 new_file = dentry_open_nonotify(path, group->fanotify_data.f_flags,
371 current_cred());
372 if (IS_ERR(new_file)) {
373 put_unused_fd(client_fd);
374 client_fd = PTR_ERR(new_file);
375 } else {
376 *file = new_file;
377 }
378
379 return client_fd;
380 }
381
process_access_response_info(const char __user * info,size_t info_len,struct fanotify_response_info_audit_rule * friar)382 static int process_access_response_info(const char __user *info,
383 size_t info_len,
384 struct fanotify_response_info_audit_rule *friar)
385 {
386 if (info_len != sizeof(*friar))
387 return -EINVAL;
388
389 if (copy_from_user(friar, info, sizeof(*friar)))
390 return -EFAULT;
391
392 if (friar->hdr.type != FAN_RESPONSE_INFO_AUDIT_RULE)
393 return -EINVAL;
394 if (friar->hdr.pad != 0)
395 return -EINVAL;
396 if (friar->hdr.len != sizeof(*friar))
397 return -EINVAL;
398
399 return info_len;
400 }
401
402 /*
403 * Finish processing of permission event by setting it to ANSWERED state and
404 * drop group->notification_lock.
405 */
finish_permission_event(struct fsnotify_group * group,struct fanotify_perm_event * event,u32 response,struct fanotify_response_info_audit_rule * friar)406 static void finish_permission_event(struct fsnotify_group *group,
407 struct fanotify_perm_event *event, u32 response,
408 struct fanotify_response_info_audit_rule *friar)
409 __releases(&group->notification_lock)
410 {
411 bool destroy = false;
412
413 assert_spin_locked(&group->notification_lock);
414 event->response = response & ~FAN_INFO;
415 if (response & FAN_INFO)
416 memcpy(&event->audit_rule, friar, sizeof(*friar));
417
418 if (event->state == FAN_EVENT_CANCELED)
419 destroy = true;
420 else
421 event->state = FAN_EVENT_ANSWERED;
422 spin_unlock(&group->notification_lock);
423 if (destroy)
424 fsnotify_destroy_event(group, &event->fae.fse);
425 }
426
process_access_response(struct fsnotify_group * group,struct fanotify_response * response_struct,const char __user * info,size_t info_len)427 static int process_access_response(struct fsnotify_group *group,
428 struct fanotify_response *response_struct,
429 const char __user *info,
430 size_t info_len)
431 {
432 struct fanotify_perm_event *event;
433 int fd = response_struct->fd;
434 u32 response = response_struct->response;
435 int errno = fanotify_get_response_errno(response);
436 int ret = info_len;
437 struct fanotify_response_info_audit_rule friar;
438
439 pr_debug("%s: group=%p fd=%d response=%x errno=%d buf=%p size=%zu\n",
440 __func__, group, fd, response, errno, info, info_len);
441 /*
442 * make sure the response is valid, if invalid we do nothing and either
443 * userspace can send a valid response or we will clean it up after the
444 * timeout
445 */
446 if (response & ~FANOTIFY_RESPONSE_VALID_MASK)
447 return -EINVAL;
448
449 switch (response & FANOTIFY_RESPONSE_ACCESS) {
450 case FAN_ALLOW:
451 if (errno)
452 return -EINVAL;
453 break;
454 case FAN_DENY:
455 /* Custom errno is supported only for pre-content groups */
456 if (errno && group->priority != FSNOTIFY_PRIO_PRE_CONTENT)
457 return -EINVAL;
458
459 /*
460 * Limit errno to values expected on open(2)/read(2)/write(2)
461 * of regular files.
462 */
463 switch (errno) {
464 case 0:
465 case EIO:
466 case EPERM:
467 case EBUSY:
468 case ETXTBSY:
469 case EAGAIN:
470 case ENOSPC:
471 case EDQUOT:
472 break;
473 default:
474 return -EINVAL;
475 }
476 break;
477 default:
478 return -EINVAL;
479 }
480
481 if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT))
482 return -EINVAL;
483
484 if (response & FAN_INFO) {
485 ret = process_access_response_info(info, info_len, &friar);
486 if (ret < 0)
487 return ret;
488 if (fd == FAN_NOFD)
489 return ret;
490 } else {
491 ret = 0;
492 }
493
494 if (fd < 0)
495 return -EINVAL;
496
497 spin_lock(&group->notification_lock);
498 list_for_each_entry(event, &group->fanotify_data.access_list,
499 fae.fse.list) {
500 if (event->fd != fd)
501 continue;
502
503 list_del_init(&event->fae.fse.list);
504 finish_permission_event(group, event, response, &friar);
505 wake_up(&group->fanotify_data.access_waitq);
506 return ret;
507 }
508 spin_unlock(&group->notification_lock);
509
510 return -ENOENT;
511 }
512
copy_mnt_info_to_user(struct fanotify_event * event,char __user * buf,int count)513 static size_t copy_mnt_info_to_user(struct fanotify_event *event,
514 char __user *buf, int count)
515 {
516 struct fanotify_event_info_mnt info = { };
517
518 info.hdr.info_type = FAN_EVENT_INFO_TYPE_MNT;
519 info.hdr.len = FANOTIFY_MNT_INFO_LEN;
520
521 if (WARN_ON(count < info.hdr.len))
522 return -EFAULT;
523
524 info.mnt_id = FANOTIFY_ME(event)->mnt_id;
525
526 if (copy_to_user(buf, &info, sizeof(info)))
527 return -EFAULT;
528
529 return info.hdr.len;
530 }
531
copy_error_info_to_user(struct fanotify_event * event,char __user * buf,int count)532 static size_t copy_error_info_to_user(struct fanotify_event *event,
533 char __user *buf, int count)
534 {
535 struct fanotify_event_info_error info = { };
536 struct fanotify_error_event *fee = FANOTIFY_EE(event);
537
538 info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
539 info.hdr.len = FANOTIFY_ERROR_INFO_LEN;
540
541 if (WARN_ON(count < info.hdr.len))
542 return -EFAULT;
543
544 info.error = fee->error;
545 info.error_count = fee->err_count;
546
547 if (copy_to_user(buf, &info, sizeof(info)))
548 return -EFAULT;
549
550 return info.hdr.len;
551 }
552
copy_fid_info_to_user(__kernel_fsid_t * fsid,struct fanotify_fh * fh,int info_type,const char * name,size_t name_len,char __user * buf,size_t count)553 static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
554 int info_type, const char *name,
555 size_t name_len,
556 char __user *buf, size_t count)
557 {
558 struct fanotify_event_info_fid info = { };
559 struct file_handle handle = { };
560 unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf;
561 size_t fh_len = fh ? fh->len : 0;
562 size_t info_len = fanotify_fid_info_len(fh_len, name_len);
563 size_t len = info_len;
564
565 pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",
566 __func__, fh_len, name_len, info_len, count);
567
568 if (WARN_ON_ONCE(len < sizeof(info) || len > count))
569 return -EFAULT;
570
571 /*
572 * Copy event info fid header followed by variable sized file handle
573 * and optionally followed by variable sized filename.
574 */
575 switch (info_type) {
576 case FAN_EVENT_INFO_TYPE_FID:
577 case FAN_EVENT_INFO_TYPE_DFID:
578 if (WARN_ON_ONCE(name_len))
579 return -EFAULT;
580 break;
581 case FAN_EVENT_INFO_TYPE_DFID_NAME:
582 case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME:
583 case FAN_EVENT_INFO_TYPE_NEW_DFID_NAME:
584 if (WARN_ON_ONCE(!name || !name_len))
585 return -EFAULT;
586 break;
587 default:
588 return -EFAULT;
589 }
590
591 info.hdr.info_type = info_type;
592 info.hdr.len = len;
593 info.fsid = *fsid;
594 if (copy_to_user(buf, &info, sizeof(info)))
595 return -EFAULT;
596
597 buf += sizeof(info);
598 len -= sizeof(info);
599 if (WARN_ON_ONCE(len < sizeof(handle)))
600 return -EFAULT;
601
602 handle.handle_type = fh->type;
603 handle.handle_bytes = fh_len;
604
605 /* Mangle handle_type for bad file_handle */
606 if (!fh_len)
607 handle.handle_type = FILEID_INVALID;
608
609 if (copy_to_user(buf, &handle, sizeof(handle)))
610 return -EFAULT;
611
612 buf += sizeof(handle);
613 len -= sizeof(handle);
614 if (WARN_ON_ONCE(len < fh_len))
615 return -EFAULT;
616
617 /*
618 * For an inline fh and inline file name, copy through stack to exclude
619 * the copy from usercopy hardening protections.
620 */
621 fh_buf = fanotify_fh_buf(fh);
622 if (fh_len <= FANOTIFY_INLINE_FH_LEN) {
623 memcpy(bounce, fh_buf, fh_len);
624 fh_buf = bounce;
625 }
626 if (copy_to_user(buf, fh_buf, fh_len))
627 return -EFAULT;
628
629 buf += fh_len;
630 len -= fh_len;
631
632 if (name_len) {
633 /* Copy the filename with terminating null */
634 name_len++;
635 if (WARN_ON_ONCE(len < name_len))
636 return -EFAULT;
637
638 if (copy_to_user(buf, name, name_len))
639 return -EFAULT;
640
641 buf += name_len;
642 len -= name_len;
643 }
644
645 /* Pad with 0's */
646 WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN);
647 if (len > 0 && clear_user(buf, len))
648 return -EFAULT;
649
650 return info_len;
651 }
652
copy_pidfd_info_to_user(int pidfd,char __user * buf,size_t count)653 static int copy_pidfd_info_to_user(int pidfd,
654 char __user *buf,
655 size_t count)
656 {
657 struct fanotify_event_info_pidfd info = { };
658 size_t info_len = FANOTIFY_PIDFD_INFO_LEN;
659
660 if (WARN_ON_ONCE(info_len > count))
661 return -EFAULT;
662
663 info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD;
664 info.hdr.len = info_len;
665 info.pidfd = pidfd;
666
667 if (copy_to_user(buf, &info, info_len))
668 return -EFAULT;
669
670 return info_len;
671 }
672
copy_range_info_to_user(struct fanotify_event * event,char __user * buf,int count)673 static size_t copy_range_info_to_user(struct fanotify_event *event,
674 char __user *buf, int count)
675 {
676 struct fanotify_perm_event *pevent = FANOTIFY_PERM(event);
677 struct fanotify_event_info_range info = { };
678 size_t info_len = FANOTIFY_RANGE_INFO_LEN;
679
680 if (WARN_ON_ONCE(info_len > count))
681 return -EFAULT;
682
683 info.hdr.info_type = FAN_EVENT_INFO_TYPE_RANGE;
684 info.hdr.len = info_len;
685 info.offset = pevent->pos;
686 info.count = pevent->count;
687
688 if (copy_to_user(buf, &info, info_len))
689 return -EFAULT;
690
691 return info_len;
692 }
693
copy_info_records_to_user(struct fanotify_event * event,struct fanotify_info * info,unsigned int info_mode,int pidfd,char __user * buf,size_t count)694 static int copy_info_records_to_user(struct fanotify_event *event,
695 struct fanotify_info *info,
696 unsigned int info_mode, int pidfd,
697 char __user *buf, size_t count)
698 {
699 int ret, total_bytes = 0, info_type = 0;
700 unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS;
701 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
702
703 /*
704 * Event info records order is as follows:
705 * 1. dir fid + name
706 * 2. (optional) new dir fid + new name
707 * 3. (optional) child fid
708 */
709 if (fanotify_event_has_dir_fh(event)) {
710 info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
711 FAN_EVENT_INFO_TYPE_DFID;
712
713 /* FAN_RENAME uses special info types */
714 if (event->mask & FAN_RENAME)
715 info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME;
716
717 ret = copy_fid_info_to_user(fanotify_event_fsid(event),
718 fanotify_info_dir_fh(info),
719 info_type,
720 fanotify_info_name(info),
721 info->name_len, buf, count);
722 if (ret < 0)
723 return ret;
724
725 buf += ret;
726 count -= ret;
727 total_bytes += ret;
728 }
729
730 /* New dir fid+name may be reported in addition to old dir fid+name */
731 if (fanotify_event_has_dir2_fh(event)) {
732 info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME;
733 ret = copy_fid_info_to_user(fanotify_event_fsid(event),
734 fanotify_info_dir2_fh(info),
735 info_type,
736 fanotify_info_name2(info),
737 info->name2_len, buf, count);
738 if (ret < 0)
739 return ret;
740
741 buf += ret;
742 count -= ret;
743 total_bytes += ret;
744 }
745
746 if (fanotify_event_has_object_fh(event)) {
747 const char *dot = NULL;
748 int dot_len = 0;
749
750 if (fid_mode == FAN_REPORT_FID || info_type) {
751 /*
752 * With only group flag FAN_REPORT_FID only type FID is
753 * reported. Second info record type is always FID.
754 */
755 info_type = FAN_EVENT_INFO_TYPE_FID;
756 } else if ((fid_mode & FAN_REPORT_NAME) &&
757 (event->mask & FAN_ONDIR)) {
758 /*
759 * With group flag FAN_REPORT_NAME, if name was not
760 * recorded in an event on a directory, report the name
761 * "." with info type DFID_NAME.
762 */
763 info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
764 dot = ".";
765 dot_len = 1;
766 } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
767 (event->mask & FAN_ONDIR)) {
768 /*
769 * With group flag FAN_REPORT_DIR_FID, a single info
770 * record has type DFID for directory entry modification
771 * event and for event on a directory.
772 */
773 info_type = FAN_EVENT_INFO_TYPE_DFID;
774 } else {
775 /*
776 * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
777 * a single info record has type FID for event on a
778 * non-directory, when there is no directory to report.
779 * For example, on FAN_DELETE_SELF event.
780 */
781 info_type = FAN_EVENT_INFO_TYPE_FID;
782 }
783
784 ret = copy_fid_info_to_user(fanotify_event_fsid(event),
785 fanotify_event_object_fh(event),
786 info_type, dot, dot_len,
787 buf, count);
788 if (ret < 0)
789 return ret;
790
791 buf += ret;
792 count -= ret;
793 total_bytes += ret;
794 }
795
796 if (pidfd_mode) {
797 ret = copy_pidfd_info_to_user(pidfd, buf, count);
798 if (ret < 0)
799 return ret;
800
801 buf += ret;
802 count -= ret;
803 total_bytes += ret;
804 }
805
806 if (fanotify_is_error_event(event->mask)) {
807 ret = copy_error_info_to_user(event, buf, count);
808 if (ret < 0)
809 return ret;
810 buf += ret;
811 count -= ret;
812 total_bytes += ret;
813 }
814
815 if (fanotify_event_has_access_range(event)) {
816 ret = copy_range_info_to_user(event, buf, count);
817 if (ret < 0)
818 return ret;
819 buf += ret;
820 count -= ret;
821 total_bytes += ret;
822 }
823
824 if (fanotify_is_mnt_event(event->mask)) {
825 ret = copy_mnt_info_to_user(event, buf, count);
826 if (ret < 0)
827 return ret;
828 buf += ret;
829 count -= ret;
830 total_bytes += ret;
831 }
832
833 return total_bytes;
834 }
835
copy_event_to_user(struct fsnotify_group * group,struct fanotify_event * event,char __user * buf,size_t count)836 static ssize_t copy_event_to_user(struct fsnotify_group *group,
837 struct fanotify_event *event,
838 char __user *buf, size_t count)
839 {
840 struct fanotify_event_metadata metadata;
841 const struct path *path = fanotify_event_path(event);
842 struct fanotify_info *info = fanotify_event_info(event);
843 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
844 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
845 struct file *f = NULL, *pidfd_file = NULL;
846 int ret, pidfd = -ESRCH, fd = -EBADF;
847
848 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
849
850 metadata.event_len = fanotify_event_len(info_mode, event);
851 metadata.metadata_len = FAN_EVENT_METADATA_LEN;
852 metadata.vers = FANOTIFY_METADATA_VERSION;
853 metadata.reserved = 0;
854 metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS;
855 metadata.pid = pid_vnr(event->pid);
856 /*
857 * For an unprivileged listener, event->pid can be used to identify the
858 * events generated by the listener process itself, without disclosing
859 * the pids of other processes.
860 */
861 if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
862 task_tgid(current) != event->pid)
863 metadata.pid = 0;
864
865 /*
866 * For now, fid mode is required for an unprivileged listener and
867 * fid mode does not report fd in events. Keep this check anyway
868 * for safety in case fid mode requirement is relaxed in the future
869 * to allow unprivileged listener to get events with no fd and no fid.
870 */
871 if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
872 path && path->mnt && path->dentry) {
873 fd = create_fd(group, path, &f);
874 /*
875 * Opening an fd from dentry can fail for several reasons.
876 * For example, when tasks are gone and we try to open their
877 * /proc files or we try to open a WRONLY file like in sysfs
878 * or when trying to open a file that was deleted on the
879 * remote network server.
880 *
881 * For a group with FAN_REPORT_FD_ERROR, we will send the
882 * event with the error instead of the open fd, otherwise
883 * Userspace may not get the error at all.
884 * In any case, userspace will not know which file failed to
885 * open, so add a debug print for further investigation.
886 */
887 if (fd < 0) {
888 pr_debug("fanotify: create_fd(%pd2) failed err=%d\n",
889 path->dentry, fd);
890 if (!FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR)) {
891 /*
892 * Historically, we've handled EOPENSTALE in a
893 * special way and silently dropped such
894 * events. Now we have to keep it to maintain
895 * backward compatibility...
896 */
897 if (fd == -EOPENSTALE)
898 fd = 0;
899 return fd;
900 }
901 }
902 }
903 if (FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR))
904 metadata.fd = fd;
905 else
906 metadata.fd = fd >= 0 ? fd : FAN_NOFD;
907
908 if (pidfd_mode) {
909 unsigned int pidfd_flags = PIDFD_STALE;
910
911 if (FAN_GROUP_FLAG(group, FAN_REPORT_TID))
912 pidfd_flags |= PIDFD_THREAD;
913
914 if (metadata.pid)
915 pidfd = pidfd_prepare(event->pid, pidfd_flags, &pidfd_file);
916
917 if (!FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR) && pidfd < 0)
918 pidfd = pidfd == -ESRCH ? FAN_NOPIDFD : FAN_EPIDFD;
919 }
920
921 ret = -EFAULT;
922 /*
923 * Sanity check copy size in case get_one_event() and
924 * event_len sizes ever get out of sync.
925 */
926 if (WARN_ON_ONCE(metadata.event_len > count))
927 goto out_close_fd;
928
929 if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN))
930 goto out_close_fd;
931
932 buf += FAN_EVENT_METADATA_LEN;
933 count -= FAN_EVENT_METADATA_LEN;
934
935 ret = copy_info_records_to_user(event, info, info_mode, pidfd,
936 buf, count);
937 if (ret < 0)
938 goto out_close_fd;
939
940 if (f)
941 fd_install(fd, f);
942
943 if (pidfd_file)
944 fd_install(pidfd, pidfd_file);
945
946 if (fanotify_is_perm_event(event->mask))
947 FANOTIFY_PERM(event)->fd = fd;
948
949 return metadata.event_len;
950
951 out_close_fd:
952 if (f) {
953 put_unused_fd(fd);
954 fput(f);
955 }
956
957 if (pidfd_file) {
958 put_unused_fd(pidfd);
959 fput(pidfd_file);
960 }
961
962 return ret;
963 }
964
965 /* intofiy userspace file descriptor functions */
fanotify_poll(struct file * file,poll_table * wait)966 static __poll_t fanotify_poll(struct file *file, poll_table *wait)
967 {
968 struct fsnotify_group *group = file->private_data;
969 __poll_t ret = 0;
970
971 poll_wait(file, &group->notification_waitq, wait);
972 spin_lock(&group->notification_lock);
973 if (!fsnotify_notify_queue_is_empty(group))
974 ret = EPOLLIN | EPOLLRDNORM;
975 spin_unlock(&group->notification_lock);
976
977 return ret;
978 }
979
fanotify_read(struct file * file,char __user * buf,size_t count,loff_t * pos)980 static ssize_t fanotify_read(struct file *file, char __user *buf,
981 size_t count, loff_t *pos)
982 {
983 struct fsnotify_group *group;
984 struct fanotify_event *event;
985 char __user *start;
986 int ret;
987 DEFINE_WAIT_FUNC(wait, woken_wake_function);
988
989 start = buf;
990 group = file->private_data;
991
992 pr_debug("%s: group=%p\n", __func__, group);
993
994 add_wait_queue(&group->notification_waitq, &wait);
995 while (1) {
996 /*
997 * User can supply arbitrarily large buffer. Avoid softlockups
998 * in case there are lots of available events.
999 */
1000 cond_resched();
1001 event = get_one_event(group, count);
1002 if (IS_ERR(event)) {
1003 ret = PTR_ERR(event);
1004 break;
1005 }
1006
1007 if (!event) {
1008 ret = -EAGAIN;
1009 if (file->f_flags & O_NONBLOCK)
1010 break;
1011
1012 ret = -ERESTARTSYS;
1013 if (signal_pending(current))
1014 break;
1015
1016 if (start != buf)
1017 break;
1018
1019 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
1020 continue;
1021 }
1022
1023 ret = copy_event_to_user(group, event, buf, count);
1024
1025 /*
1026 * Permission events get queued to wait for response. Other
1027 * events can be destroyed now.
1028 */
1029 if (!fanotify_is_perm_event(event->mask)) {
1030 fsnotify_destroy_event(group, &event->fse);
1031 } else {
1032 if (ret <= 0 || FANOTIFY_PERM(event)->fd < 0) {
1033 spin_lock(&group->notification_lock);
1034 finish_permission_event(group,
1035 FANOTIFY_PERM(event), FAN_DENY, NULL);
1036 wake_up(&group->fanotify_data.access_waitq);
1037 } else {
1038 spin_lock(&group->notification_lock);
1039 list_add_tail(&event->fse.list,
1040 &group->fanotify_data.access_list);
1041 FANOTIFY_PERM(event)->recv_pid = current->pid;
1042 spin_unlock(&group->notification_lock);
1043 }
1044 }
1045 if (ret < 0)
1046 break;
1047 buf += ret;
1048 count -= ret;
1049 }
1050 remove_wait_queue(&group->notification_waitq, &wait);
1051
1052 if (start != buf && ret != -EFAULT)
1053 ret = buf - start;
1054 return ret;
1055 }
1056
fanotify_write(struct file * file,const char __user * buf,size_t count,loff_t * pos)1057 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
1058 {
1059 struct fanotify_response response;
1060 struct fsnotify_group *group;
1061 int ret;
1062 const char __user *info_buf = buf + sizeof(struct fanotify_response);
1063 size_t info_len;
1064
1065 if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
1066 return -EINVAL;
1067
1068 group = file->private_data;
1069
1070 pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
1071
1072 if (count < sizeof(response))
1073 return -EINVAL;
1074
1075 if (copy_from_user(&response, buf, sizeof(response)))
1076 return -EFAULT;
1077
1078 info_len = count - sizeof(response);
1079
1080 ret = process_access_response(group, &response, info_buf, info_len);
1081 if (ret < 0)
1082 count = ret;
1083 else
1084 count = sizeof(response) + ret;
1085
1086 return count;
1087 }
1088
fanotify_release(struct inode * ignored,struct file * file)1089 static int fanotify_release(struct inode *ignored, struct file *file)
1090 {
1091 struct fsnotify_group *group = file->private_data;
1092 struct fsnotify_event *fsn_event;
1093
1094 /*
1095 * Stop new events from arriving in the notification queue. since
1096 * userspace cannot use fanotify fd anymore, no event can enter or
1097 * leave access_list by now either.
1098 */
1099 fsnotify_group_stop_queueing(group);
1100
1101 fanotify_perm_watchdog_group_remove(group);
1102
1103 /*
1104 * Process all permission events on access_list and notification queue
1105 * and simulate reply from userspace.
1106 */
1107 spin_lock(&group->notification_lock);
1108 while (!list_empty(&group->fanotify_data.access_list)) {
1109 struct fanotify_perm_event *event;
1110
1111 event = list_first_entry(&group->fanotify_data.access_list,
1112 struct fanotify_perm_event, fae.fse.list);
1113 list_del_init(&event->fae.fse.list);
1114 finish_permission_event(group, event, FAN_ALLOW, NULL);
1115 spin_lock(&group->notification_lock);
1116 }
1117
1118 /*
1119 * Destroy all non-permission events. For permission events just
1120 * dequeue them and set the response. They will be freed once the
1121 * response is consumed and fanotify_get_response() returns.
1122 */
1123 while ((fsn_event = fsnotify_remove_first_event(group))) {
1124 struct fanotify_event *event = FANOTIFY_E(fsn_event);
1125
1126 if (!(event->mask & FANOTIFY_PERM_EVENTS)) {
1127 spin_unlock(&group->notification_lock);
1128 fsnotify_destroy_event(group, fsn_event);
1129 } else {
1130 finish_permission_event(group, FANOTIFY_PERM(event),
1131 FAN_ALLOW, NULL);
1132 }
1133 spin_lock(&group->notification_lock);
1134 }
1135 spin_unlock(&group->notification_lock);
1136
1137 /* Response for all permission events it set, wakeup waiters */
1138 wake_up(&group->fanotify_data.access_waitq);
1139
1140 /* matches the fanotify_init->fsnotify_alloc_group */
1141 fsnotify_destroy_group(group);
1142
1143 return 0;
1144 }
1145
fanotify_ioctl(struct file * file,unsigned int cmd,unsigned long arg)1146 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1147 {
1148 struct fsnotify_group *group;
1149 struct fsnotify_event *fsn_event;
1150 unsigned int info_mode;
1151 void __user *p;
1152 int ret = -ENOTTY;
1153 size_t send_len = 0;
1154
1155 group = file->private_data;
1156 info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
1157
1158 p = (void __user *) arg;
1159
1160 switch (cmd) {
1161 case FIONREAD:
1162 spin_lock(&group->notification_lock);
1163 list_for_each_entry(fsn_event, &group->notification_list, list)
1164 send_len += fanotify_event_len(info_mode,
1165 FANOTIFY_E(fsn_event));
1166 spin_unlock(&group->notification_lock);
1167 ret = put_user(send_len, (int __user *) p);
1168 break;
1169 }
1170
1171 return ret;
1172 }
1173
1174 static const struct file_operations fanotify_fops = {
1175 .show_fdinfo = fanotify_show_fdinfo,
1176 .poll = fanotify_poll,
1177 .read = fanotify_read,
1178 .write = fanotify_write,
1179 .fasync = NULL,
1180 .release = fanotify_release,
1181 .unlocked_ioctl = fanotify_ioctl,
1182 .compat_ioctl = compat_ptr_ioctl,
1183 .llseek = noop_llseek,
1184 };
1185
fanotify_find_path(int dfd,const char __user * filename,struct path * path,unsigned int flags,__u64 mask,unsigned int obj_type)1186 static int fanotify_find_path(int dfd, const char __user *filename,
1187 struct path *path, unsigned int flags, __u64 mask,
1188 unsigned int obj_type)
1189 {
1190 int ret;
1191
1192 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
1193 dfd, filename, flags);
1194
1195 if (filename == NULL) {
1196 CLASS(fd, f)(dfd);
1197
1198 if (fd_empty(f))
1199 return -EBADF;
1200
1201 if ((flags & FAN_MARK_ONLYDIR) &&
1202 !(S_ISDIR(file_inode(fd_file(f))->i_mode)))
1203 return -ENOTDIR;
1204
1205 *path = fd_file(f)->f_path;
1206 path_get(path);
1207 ret = 0;
1208 } else {
1209 unsigned int lookup_flags = 0;
1210
1211 if (!(flags & FAN_MARK_DONT_FOLLOW))
1212 lookup_flags |= LOOKUP_FOLLOW;
1213 if (flags & FAN_MARK_ONLYDIR)
1214 lookup_flags |= LOOKUP_DIRECTORY;
1215
1216 ret = user_path_at(dfd, filename, lookup_flags, path);
1217 }
1218 return ret;
1219 }
1220
fanotify_mark_remove_from_mask(struct fsnotify_mark * fsn_mark,__u32 mask,unsigned int flags,__u32 umask,int * destroy)1221 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
1222 __u32 mask, unsigned int flags,
1223 __u32 umask, int *destroy)
1224 {
1225 __u32 oldmask, newmask;
1226
1227 /* umask bits cannot be removed by user */
1228 mask &= ~umask;
1229 spin_lock(&fsn_mark->lock);
1230 oldmask = fsnotify_calc_mask(fsn_mark);
1231 if (!(flags & FANOTIFY_MARK_IGNORE_BITS)) {
1232 fsn_mark->mask &= ~mask;
1233 } else {
1234 fsn_mark->ignore_mask &= ~mask;
1235 }
1236 newmask = fsnotify_calc_mask(fsn_mark);
1237 /*
1238 * We need to keep the mark around even if remaining mask cannot
1239 * result in any events (e.g. mask == FAN_ONDIR) to support incremenal
1240 * changes to the mask.
1241 * Destroy mark when only umask bits remain.
1242 */
1243 *destroy = !((fsn_mark->mask | fsn_mark->ignore_mask) & ~umask);
1244 spin_unlock(&fsn_mark->lock);
1245
1246 return oldmask & ~newmask;
1247 }
1248
fanotify_remove_mark(struct fsnotify_group * group,void * obj,unsigned int obj_type,__u32 mask,unsigned int flags,__u32 umask)1249 static int fanotify_remove_mark(struct fsnotify_group *group,
1250 void *obj, unsigned int obj_type, __u32 mask,
1251 unsigned int flags, __u32 umask)
1252 {
1253 struct fsnotify_mark *fsn_mark = NULL;
1254 __u32 removed;
1255 int destroy_mark;
1256
1257 fsnotify_group_lock(group);
1258 fsn_mark = fsnotify_find_mark(obj, obj_type, group);
1259 if (!fsn_mark) {
1260 fsnotify_group_unlock(group);
1261 return -ENOENT;
1262 }
1263
1264 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
1265 umask, &destroy_mark);
1266 if (removed & fsnotify_conn_mask(fsn_mark->connector))
1267 fsnotify_recalc_mask(fsn_mark->connector);
1268 if (destroy_mark)
1269 fsnotify_detach_mark(fsn_mark);
1270 fsnotify_group_unlock(group);
1271 if (destroy_mark)
1272 fsnotify_free_mark(fsn_mark);
1273
1274 /* matches the fsnotify_find_mark() */
1275 fsnotify_put_mark(fsn_mark);
1276 return 0;
1277 }
1278
fanotify_mark_update_flags(struct fsnotify_mark * fsn_mark,unsigned int fan_flags)1279 static bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark,
1280 unsigned int fan_flags)
1281 {
1282 bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE);
1283 unsigned int ignore = fan_flags & FANOTIFY_MARK_IGNORE_BITS;
1284 bool recalc = false;
1285
1286 /*
1287 * When using FAN_MARK_IGNORE for the first time, mark starts using
1288 * independent event flags in ignore mask. After that, trying to
1289 * update the ignore mask with the old FAN_MARK_IGNORED_MASK API
1290 * will result in EEXIST error.
1291 */
1292 if (ignore == FAN_MARK_IGNORE)
1293 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS;
1294
1295 /*
1296 * Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to
1297 * the removal of the FS_MODIFY bit in calculated mask if it was set
1298 * because of an ignore mask that is now going to survive FS_MODIFY.
1299 */
1300 if (ignore && (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
1301 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) {
1302 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
1303 if (!(fsn_mark->mask & FS_MODIFY))
1304 recalc = true;
1305 }
1306
1307 if (fsn_mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE ||
1308 want_iref == !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF))
1309 return recalc;
1310
1311 /*
1312 * NO_IREF may be removed from a mark, but not added.
1313 * When removed, fsnotify_recalc_mask() will take the inode ref.
1314 */
1315 WARN_ON_ONCE(!want_iref);
1316 fsn_mark->flags &= ~FSNOTIFY_MARK_FLAG_NO_IREF;
1317
1318 return true;
1319 }
1320
fanotify_mark_add_to_mask(struct fsnotify_mark * fsn_mark,__u32 mask,unsigned int fan_flags)1321 static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
1322 __u32 mask, unsigned int fan_flags)
1323 {
1324 __u32 old_mask;
1325 bool recalc;
1326
1327 spin_lock(&fsn_mark->lock);
1328 if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS)) {
1329 old_mask = fsn_mark->mask;
1330 fsn_mark->mask |= mask;
1331 recalc = old_mask != fsn_mark->mask;
1332 } else {
1333 fsn_mark->ignore_mask |= mask;
1334 recalc = true;
1335 }
1336
1337 recalc |= fanotify_mark_update_flags(fsn_mark, fan_flags);
1338 spin_unlock(&fsn_mark->lock);
1339
1340 return recalc;
1341 }
1342
1343 struct fan_fsid {
1344 struct super_block *sb;
1345 __kernel_fsid_t id;
1346 bool weak;
1347 };
1348
fanotify_set_mark_fsid(struct fsnotify_group * group,struct fsnotify_mark * mark,struct fan_fsid * fsid)1349 static int fanotify_set_mark_fsid(struct fsnotify_group *group,
1350 struct fsnotify_mark *mark,
1351 struct fan_fsid *fsid)
1352 {
1353 struct fsnotify_mark_connector *conn;
1354 struct fsnotify_mark *old;
1355 struct super_block *old_sb = NULL;
1356
1357 FANOTIFY_MARK(mark)->fsid = fsid->id;
1358 mark->flags |= FSNOTIFY_MARK_FLAG_HAS_FSID;
1359 if (fsid->weak)
1360 mark->flags |= FSNOTIFY_MARK_FLAG_WEAK_FSID;
1361
1362 /* First mark added will determine if group is single or multi fsid */
1363 if (list_empty(&group->marks_list))
1364 return 0;
1365
1366 /* Find sb of an existing mark */
1367 list_for_each_entry(old, &group->marks_list, g_list) {
1368 conn = READ_ONCE(old->connector);
1369 if (!conn)
1370 continue;
1371 old_sb = fsnotify_connector_sb(conn);
1372 if (old_sb)
1373 break;
1374 }
1375
1376 /* Only detached marks left? */
1377 if (!old_sb)
1378 return 0;
1379
1380 /* Do not allow mixing of marks with weak and strong fsid */
1381 if ((mark->flags ^ old->flags) & FSNOTIFY_MARK_FLAG_WEAK_FSID)
1382 return -EXDEV;
1383
1384 /* Allow mixing of marks with strong fsid from different fs */
1385 if (!fsid->weak)
1386 return 0;
1387
1388 /* Do not allow mixing marks with weak fsid from different fs */
1389 if (old_sb != fsid->sb)
1390 return -EXDEV;
1391
1392 /* Do not allow mixing marks from different btrfs sub-volumes */
1393 if (!fanotify_fsid_equal(&FANOTIFY_MARK(old)->fsid,
1394 &FANOTIFY_MARK(mark)->fsid))
1395 return -EXDEV;
1396
1397 return 0;
1398 }
1399
fanotify_add_new_mark(struct fsnotify_group * group,void * obj,unsigned int obj_type,unsigned int fan_flags,struct fan_fsid * fsid)1400 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
1401 void *obj,
1402 unsigned int obj_type,
1403 unsigned int fan_flags,
1404 struct fan_fsid *fsid)
1405 {
1406 struct ucounts *ucounts = group->fanotify_data.ucounts;
1407 struct fanotify_mark *fan_mark;
1408 struct fsnotify_mark *mark;
1409 int ret;
1410
1411 /*
1412 * Enforce per user marks limits per user in all containing user ns.
1413 * A group with FAN_UNLIMITED_MARKS does not contribute to mark count
1414 * in the limited groups account.
1415 */
1416 BUILD_BUG_ON(!(FANOTIFY_ADMIN_INIT_FLAGS & FAN_UNLIMITED_MARKS));
1417 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) &&
1418 !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS))
1419 return ERR_PTR(-ENOSPC);
1420
1421 fan_mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
1422 if (!fan_mark) {
1423 ret = -ENOMEM;
1424 goto out_dec_ucounts;
1425 }
1426
1427 mark = &fan_mark->fsn_mark;
1428 fsnotify_init_mark(mark, group);
1429 if (fan_flags & FAN_MARK_EVICTABLE)
1430 mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF;
1431
1432 /* Cache fsid of filesystem containing the marked object */
1433 if (fsid) {
1434 ret = fanotify_set_mark_fsid(group, mark, fsid);
1435 if (ret)
1436 goto out_put_mark;
1437 } else {
1438 fan_mark->fsid.val[0] = fan_mark->fsid.val[1] = 0;
1439 }
1440
1441 ret = fsnotify_add_mark_locked(mark, obj, obj_type, 0);
1442 if (ret)
1443 goto out_put_mark;
1444
1445 return mark;
1446
1447 out_put_mark:
1448 fsnotify_put_mark(mark);
1449 out_dec_ucounts:
1450 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS))
1451 dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS);
1452 return ERR_PTR(ret);
1453 }
1454
fanotify_group_init_error_pool(struct fsnotify_group * group)1455 static int fanotify_group_init_error_pool(struct fsnotify_group *group)
1456 {
1457 if (mempool_initialized(&group->fanotify_data.error_events_pool))
1458 return 0;
1459
1460 return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool,
1461 FANOTIFY_DEFAULT_FEE_POOL_SIZE,
1462 sizeof(struct fanotify_error_event));
1463 }
1464
fanotify_may_update_existing_mark(struct fsnotify_mark * fsn_mark,__u32 mask,unsigned int fan_flags)1465 static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark,
1466 __u32 mask, unsigned int fan_flags)
1467 {
1468 /*
1469 * Non evictable mark cannot be downgraded to evictable mark.
1470 */
1471 if (fan_flags & FAN_MARK_EVICTABLE &&
1472 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF))
1473 return -EEXIST;
1474
1475 /*
1476 * New ignore mask semantics cannot be downgraded to old semantics.
1477 */
1478 if (fan_flags & FAN_MARK_IGNORED_MASK &&
1479 fsn_mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
1480 return -EEXIST;
1481
1482 /*
1483 * An ignore mask that survives modify could never be downgraded to not
1484 * survive modify. With new FAN_MARK_IGNORE semantics we make that rule
1485 * explicit and return an error when trying to update the ignore mask
1486 * without the original FAN_MARK_IGNORED_SURV_MODIFY value.
1487 */
1488 if (fan_flags & FAN_MARK_IGNORE &&
1489 !(fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
1490 fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
1491 return -EEXIST;
1492
1493 /* For now pre-content events are not generated for directories */
1494 mask |= fsn_mark->mask;
1495 if (mask & FANOTIFY_PRE_CONTENT_EVENTS && mask & FAN_ONDIR)
1496 return -EEXIST;
1497
1498 return 0;
1499 }
1500
fanotify_add_mark(struct fsnotify_group * group,void * obj,unsigned int obj_type,__u32 mask,unsigned int fan_flags,struct fan_fsid * fsid)1501 static int fanotify_add_mark(struct fsnotify_group *group,
1502 void *obj, unsigned int obj_type,
1503 __u32 mask, unsigned int fan_flags,
1504 struct fan_fsid *fsid)
1505 {
1506 struct fsnotify_mark *fsn_mark;
1507 bool recalc;
1508 int ret = 0;
1509
1510 fsnotify_group_lock(group);
1511 fsn_mark = fsnotify_find_mark(obj, obj_type, group);
1512 if (!fsn_mark) {
1513 fsn_mark = fanotify_add_new_mark(group, obj, obj_type,
1514 fan_flags, fsid);
1515 if (IS_ERR(fsn_mark)) {
1516 fsnotify_group_unlock(group);
1517 return PTR_ERR(fsn_mark);
1518 }
1519 }
1520
1521 /*
1522 * Check if requested mark flags conflict with an existing mark flags.
1523 */
1524 ret = fanotify_may_update_existing_mark(fsn_mark, mask, fan_flags);
1525 if (ret)
1526 goto out;
1527
1528 /*
1529 * Error events are pre-allocated per group, only if strictly
1530 * needed (i.e. FAN_FS_ERROR was requested).
1531 */
1532 if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS) &&
1533 (mask & FAN_FS_ERROR)) {
1534 ret = fanotify_group_init_error_pool(group);
1535 if (ret)
1536 goto out;
1537 }
1538
1539 recalc = fanotify_mark_add_to_mask(fsn_mark, mask, fan_flags);
1540 if (recalc)
1541 fsnotify_recalc_mask(fsn_mark->connector);
1542
1543 out:
1544 fsnotify_group_unlock(group);
1545
1546 fsnotify_put_mark(fsn_mark);
1547
1548 if (!ret && (mask & FANOTIFY_PERM_EVENTS))
1549 fanotify_perm_watchdog_group_add(group);
1550
1551 return ret;
1552 }
1553
fanotify_alloc_overflow_event(void)1554 static struct fsnotify_event *fanotify_alloc_overflow_event(void)
1555 {
1556 struct fanotify_event *oevent;
1557
1558 oevent = kmalloc_obj(*oevent, GFP_KERNEL_ACCOUNT);
1559 if (!oevent)
1560 return NULL;
1561
1562 fanotify_init_event(oevent, 0, FS_Q_OVERFLOW);
1563 oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW;
1564
1565 return &oevent->fse;
1566 }
1567
fanotify_alloc_merge_hash(void)1568 static struct hlist_head *fanotify_alloc_merge_hash(void)
1569 {
1570 struct hlist_head *hash;
1571
1572 hash = kmalloc(sizeof(struct hlist_head) << FANOTIFY_HTABLE_BITS,
1573 GFP_KERNEL_ACCOUNT);
1574 if (!hash)
1575 return NULL;
1576
1577 __hash_init(hash, FANOTIFY_HTABLE_SIZE);
1578
1579 return hash;
1580 }
1581
1582 DEFINE_CLASS(fsnotify_group,
1583 struct fsnotify_group *,
1584 if (!IS_ERR_OR_NULL(_T)) fsnotify_destroy_group(_T),
1585 fsnotify_alloc_group(ops, flags),
1586 const struct fsnotify_ops *ops, int flags)
1587
1588 /* fanotify syscalls */
SYSCALL_DEFINE2(fanotify_init,unsigned int,flags,unsigned int,event_f_flags)1589 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
1590 {
1591 struct user_namespace *user_ns = current_user_ns();
1592 int f_flags, fd;
1593 unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
1594 unsigned int class = flags & FANOTIFY_CLASS_BITS;
1595 unsigned int internal_flags = 0;
1596
1597 pr_debug("%s: flags=%x event_f_flags=%x\n",
1598 __func__, flags, event_f_flags);
1599
1600 /*
1601 * An unprivileged user can setup an fanotify group with limited
1602 * functionality - an unprivileged group is limited to notification
1603 * events with file handles or mount ids and it cannot use unlimited
1604 * queue/marks.
1605 */
1606 if (((flags & FANOTIFY_ADMIN_INIT_FLAGS) ||
1607 !(flags & (FANOTIFY_FID_BITS | FAN_REPORT_MNT))) &&
1608 !capable(CAP_SYS_ADMIN))
1609 return -EPERM;
1610
1611 if (!ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN)) {
1612 /*
1613 * Setting the internal flag FANOTIFY_UNPRIV on the group
1614 * prevents setting mount/filesystem marks on this group and
1615 * prevents reporting pid and open fd in events.
1616 */
1617 internal_flags |= FANOTIFY_UNPRIV;
1618 }
1619
1620 #ifdef CONFIG_AUDITSYSCALL
1621 if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT))
1622 #else
1623 if (flags & ~FANOTIFY_INIT_FLAGS)
1624 #endif
1625 return -EINVAL;
1626
1627 /* Don't allow mixing mnt events with inode events for now */
1628 if (flags & FAN_REPORT_MNT) {
1629 if (class != FAN_CLASS_NOTIF)
1630 return -EINVAL;
1631 if (flags & (FANOTIFY_FID_BITS | FAN_REPORT_FD_ERROR))
1632 return -EINVAL;
1633 }
1634
1635 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
1636 return -EINVAL;
1637
1638 switch (event_f_flags & O_ACCMODE) {
1639 case O_RDONLY:
1640 case O_RDWR:
1641 case O_WRONLY:
1642 break;
1643 default:
1644 return -EINVAL;
1645 }
1646
1647 if (fid_mode && class != FAN_CLASS_NOTIF)
1648 return -EINVAL;
1649
1650 /*
1651 * Child name is reported with parent fid so requires dir fid.
1652 * We can report both child fid and dir fid with or without name.
1653 */
1654 if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID))
1655 return -EINVAL;
1656
1657 /*
1658 * FAN_REPORT_TARGET_FID requires FAN_REPORT_NAME and FAN_REPORT_FID
1659 * and is used as an indication to report both dir and child fid on all
1660 * dirent events.
1661 */
1662 if ((fid_mode & FAN_REPORT_TARGET_FID) &&
1663 (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))
1664 return -EINVAL;
1665
1666 f_flags = O_RDWR;
1667 if (flags & FAN_CLOEXEC)
1668 f_flags |= O_CLOEXEC;
1669 if (flags & FAN_NONBLOCK)
1670 f_flags |= O_NONBLOCK;
1671
1672 CLASS(fsnotify_group, group)(&fanotify_fsnotify_ops,
1673 FSNOTIFY_GROUP_USER);
1674 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
1675 if (IS_ERR(group))
1676 return PTR_ERR(group);
1677
1678 /* Enforce groups limits per user in all containing user ns */
1679 group->fanotify_data.ucounts = inc_ucount(user_ns, current_euid(),
1680 UCOUNT_FANOTIFY_GROUPS);
1681 if (!group->fanotify_data.ucounts)
1682 return -EMFILE;
1683
1684 group->fanotify_data.flags = flags | internal_flags;
1685 group->memcg = get_mem_cgroup_from_mm(current->mm);
1686 group->user_ns = get_user_ns(user_ns);
1687
1688 group->fanotify_data.merge_hash = fanotify_alloc_merge_hash();
1689 if (!group->fanotify_data.merge_hash)
1690 return -ENOMEM;
1691
1692 group->overflow_event = fanotify_alloc_overflow_event();
1693 if (unlikely(!group->overflow_event))
1694 return -ENOMEM;
1695
1696 if (force_o_largefile())
1697 event_f_flags |= O_LARGEFILE;
1698 group->fanotify_data.f_flags = event_f_flags;
1699 init_waitqueue_head(&group->fanotify_data.access_waitq);
1700 INIT_LIST_HEAD(&group->fanotify_data.access_list);
1701 INIT_LIST_HEAD(&group->fanotify_data.perm_grp_list);
1702 switch (class) {
1703 case FAN_CLASS_NOTIF:
1704 group->priority = FSNOTIFY_PRIO_NORMAL;
1705 break;
1706 case FAN_CLASS_CONTENT:
1707 group->priority = FSNOTIFY_PRIO_CONTENT;
1708 break;
1709 case FAN_CLASS_PRE_CONTENT:
1710 group->priority = FSNOTIFY_PRIO_PRE_CONTENT;
1711 break;
1712 default:
1713 return -EINVAL;
1714 }
1715
1716 BUILD_BUG_ON(!(FANOTIFY_ADMIN_INIT_FLAGS & FAN_UNLIMITED_QUEUE));
1717 if (flags & FAN_UNLIMITED_QUEUE) {
1718 group->max_events = UINT_MAX;
1719 } else {
1720 group->max_events = fanotify_max_queued_events;
1721 }
1722
1723 if (flags & FAN_ENABLE_AUDIT) {
1724 if (!capable(CAP_AUDIT_WRITE))
1725 return -EPERM;
1726 }
1727
1728 fd = FD_ADD(f_flags,
1729 anon_inode_getfile_fmode("[fanotify]", &fanotify_fops,
1730 group, f_flags, FMODE_NONOTIFY));
1731 if (fd >= 0)
1732 retain_and_null_ptr(group);
1733 return fd;
1734 }
1735
fanotify_test_fsid(struct dentry * dentry,unsigned int flags,struct fan_fsid * fsid)1736 static int fanotify_test_fsid(struct dentry *dentry, unsigned int flags,
1737 struct fan_fsid *fsid)
1738 {
1739 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
1740 __kernel_fsid_t root_fsid;
1741 int err;
1742
1743 /*
1744 * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse).
1745 */
1746 err = vfs_get_fsid(dentry, &fsid->id);
1747 if (err)
1748 return err;
1749
1750 fsid->sb = dentry->d_sb;
1751 if (!fsid->id.val[0] && !fsid->id.val[1]) {
1752 err = -ENODEV;
1753 goto weak;
1754 }
1755
1756 /*
1757 * Make sure dentry is not of a filesystem subvolume (e.g. btrfs)
1758 * which uses a different fsid than sb root.
1759 */
1760 err = vfs_get_fsid(dentry->d_sb->s_root, &root_fsid);
1761 if (err)
1762 return err;
1763
1764 if (!fanotify_fsid_equal(&root_fsid, &fsid->id)) {
1765 err = -EXDEV;
1766 goto weak;
1767 }
1768
1769 fsid->weak = false;
1770 return 0;
1771
1772 weak:
1773 /* Allow weak fsid when marking inodes */
1774 fsid->weak = true;
1775 return (mark_type == FAN_MARK_INODE) ? 0 : err;
1776 }
1777
1778 /* Check if filesystem can encode a unique fid */
fanotify_test_fid(struct dentry * dentry,unsigned int flags)1779 static int fanotify_test_fid(struct dentry *dentry, unsigned int flags)
1780 {
1781 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
1782 const struct export_operations *nop = dentry->d_sb->s_export_op;
1783
1784 /*
1785 * We need to make sure that the filesystem supports encoding of
1786 * file handles so user can use name_to_handle_at() to compare fids
1787 * reported with events to the file handle of watched objects.
1788 */
1789 if (!exportfs_can_encode_fid(nop))
1790 return -EOPNOTSUPP;
1791
1792 /*
1793 * For sb/mount mark, we also need to make sure that the filesystem
1794 * supports decoding file handles, so user has a way to map back the
1795 * reported fids to filesystem objects.
1796 */
1797 if (mark_type != FAN_MARK_INODE && !exportfs_can_decode_fh(nop))
1798 return -EOPNOTSUPP;
1799
1800 return 0;
1801 }
1802
fanotify_events_supported(struct fsnotify_group * group,const struct path * path,__u64 mask,unsigned int flags)1803 static int fanotify_events_supported(struct fsnotify_group *group,
1804 const struct path *path, __u64 mask,
1805 unsigned int flags)
1806 {
1807 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
1808 bool is_dir = d_is_dir(path->dentry);
1809 /* Strict validation of events in non-dir inode mask with v5.17+ APIs */
1810 bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) ||
1811 (mask & FAN_RENAME) ||
1812 (flags & FAN_MARK_IGNORE);
1813
1814 /*
1815 * Filesystems need to opt-into pre-content evnets (a.k.a HSM)
1816 * and they are only supported on regular files and directories.
1817 */
1818 if (mask & FANOTIFY_PRE_CONTENT_EVENTS) {
1819 if (!(path->mnt->mnt_sb->s_iflags & SB_I_ALLOW_HSM))
1820 return -EOPNOTSUPP;
1821 if (!is_dir && !d_is_reg(path->dentry))
1822 return -EINVAL;
1823 }
1824
1825 /*
1826 * Some filesystems such as 'proc' acquire unusual locks when opening
1827 * files. For them fanotify permission events have high chances of
1828 * deadlocking the system - open done when reporting fanotify event
1829 * blocks on this "unusual" lock while another process holding the lock
1830 * waits for fanotify permission event to be answered. Just disallow
1831 * permission events for such filesystems.
1832 */
1833 if (mask & FANOTIFY_PERM_EVENTS &&
1834 path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM)
1835 return -EINVAL;
1836
1837 /*
1838 * mount and sb marks are not allowed on kernel internal pseudo fs,
1839 * like pipe_mnt, because that would subscribe to events on all the
1840 * anonynous pipes in the system.
1841 *
1842 * SB_NOUSER covers all of the internal pseudo fs whose objects are not
1843 * exposed to user's mount namespace, but there are other SB_KERNMOUNT
1844 * fs, like nsfs, debugfs, for which the value of allowing sb and mount
1845 * mark is questionable. For now we leave them alone.
1846 */
1847 if (mark_type != FAN_MARK_INODE &&
1848 path->mnt->mnt_sb->s_flags & SB_NOUSER)
1849 return -EINVAL;
1850
1851 /*
1852 * We shouldn't have allowed setting dirent events and the directory
1853 * flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode,
1854 * but because we always allowed it, error only when using new APIs.
1855 */
1856 if (strict_dir_events && mark_type == FAN_MARK_INODE &&
1857 !is_dir && (mask & FANOTIFY_DIRONLY_EVENT_BITS))
1858 return -ENOTDIR;
1859
1860 return 0;
1861 }
1862
do_fanotify_mark(int fanotify_fd,unsigned int flags,__u64 mask,int dfd,const char __user * pathname)1863 static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
1864 int dfd, const char __user *pathname)
1865 {
1866 struct inode *inode = NULL;
1867 struct fsnotify_group *group;
1868 struct path path;
1869 struct fan_fsid __fsid, *fsid = NULL;
1870 struct user_namespace *user_ns = NULL;
1871 struct mnt_namespace *mntns;
1872 u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;
1873 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
1874 unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS;
1875 unsigned int ignore = flags & FANOTIFY_MARK_IGNORE_BITS;
1876 unsigned int obj_type, fid_mode;
1877 void *obj = NULL;
1878 u32 umask = 0;
1879 int ret;
1880
1881 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
1882 __func__, fanotify_fd, flags, dfd, pathname, mask);
1883
1884 /* we only use the lower 32 bits as of right now. */
1885 if (upper_32_bits(mask))
1886 return -EINVAL;
1887
1888 if (flags & ~FANOTIFY_MARK_FLAGS)
1889 return -EINVAL;
1890
1891 switch (mark_type) {
1892 case FAN_MARK_INODE:
1893 obj_type = FSNOTIFY_OBJ_TYPE_INODE;
1894 break;
1895 case FAN_MARK_MOUNT:
1896 obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT;
1897 break;
1898 case FAN_MARK_FILESYSTEM:
1899 obj_type = FSNOTIFY_OBJ_TYPE_SB;
1900 break;
1901 case FAN_MARK_MNTNS:
1902 obj_type = FSNOTIFY_OBJ_TYPE_MNTNS;
1903 break;
1904 default:
1905 return -EINVAL;
1906 }
1907
1908 switch (mark_cmd) {
1909 case FAN_MARK_ADD:
1910 case FAN_MARK_REMOVE:
1911 if (!mask)
1912 return -EINVAL;
1913 break;
1914 case FAN_MARK_FLUSH:
1915 if (flags & ~(FANOTIFY_MARK_TYPE_BITS | FAN_MARK_FLUSH))
1916 return -EINVAL;
1917 break;
1918 default:
1919 return -EINVAL;
1920 }
1921
1922 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
1923 valid_mask |= FANOTIFY_PERM_EVENTS;
1924
1925 if (mask & ~valid_mask)
1926 return -EINVAL;
1927
1928
1929 /* We don't allow FAN_MARK_IGNORE & FAN_MARK_IGNORED_MASK together */
1930 if (ignore == (FAN_MARK_IGNORE | FAN_MARK_IGNORED_MASK))
1931 return -EINVAL;
1932
1933 /*
1934 * Event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) have no effect with
1935 * FAN_MARK_IGNORED_MASK.
1936 */
1937 if (ignore == FAN_MARK_IGNORED_MASK) {
1938 mask &= ~FANOTIFY_EVENT_FLAGS;
1939 umask = FANOTIFY_EVENT_FLAGS;
1940 }
1941
1942 CLASS(fd, f)(fanotify_fd);
1943 if (fd_empty(f))
1944 return -EBADF;
1945
1946 /* verify that this is indeed an fanotify instance */
1947 if (unlikely(fd_file(f)->f_op != &fanotify_fops))
1948 return -EINVAL;
1949 group = fd_file(f)->private_data;
1950
1951 /* Only report mount events on mnt namespace */
1952 if (FAN_GROUP_FLAG(group, FAN_REPORT_MNT)) {
1953 if (mask & ~FANOTIFY_MOUNT_EVENTS)
1954 return -EINVAL;
1955 if (mark_type != FAN_MARK_MNTNS)
1956 return -EINVAL;
1957 } else {
1958 if (mask & FANOTIFY_MOUNT_EVENTS)
1959 return -EINVAL;
1960 if (mark_type == FAN_MARK_MNTNS)
1961 return -EINVAL;
1962 }
1963
1964 /*
1965 * A user is allowed to setup sb/mount/mntns marks only if it is
1966 * capable in the user ns where the group was created.
1967 */
1968 if (mark_type != FAN_MARK_INODE &&
1969 !ns_capable(group->user_ns, CAP_SYS_ADMIN))
1970 return -EPERM;
1971
1972 /*
1973 * Permission events are not allowed for FAN_CLASS_NOTIF.
1974 * Pre-content permission events are not allowed for FAN_CLASS_CONTENT.
1975 */
1976 if (mask & FANOTIFY_PERM_EVENTS &&
1977 group->priority == FSNOTIFY_PRIO_NORMAL)
1978 return -EINVAL;
1979 else if (mask & FANOTIFY_PRE_CONTENT_EVENTS &&
1980 group->priority == FSNOTIFY_PRIO_CONTENT)
1981 return -EINVAL;
1982
1983 if (mask & FAN_FS_ERROR &&
1984 mark_type != FAN_MARK_FILESYSTEM)
1985 return -EINVAL;
1986
1987 /*
1988 * Evictable is only relevant for inode marks, because only inode object
1989 * can be evicted on memory pressure.
1990 */
1991 if (flags & FAN_MARK_EVICTABLE &&
1992 mark_type != FAN_MARK_INODE)
1993 return -EINVAL;
1994
1995 /*
1996 * Events that do not carry enough information to report
1997 * event->fd require a group that supports reporting fid. Those
1998 * events are not supported on a mount mark, because they do not
1999 * carry enough information (i.e. path) to be filtered by mount
2000 * point.
2001 */
2002 fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
2003 if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_MOUNT_EVENTS|FANOTIFY_EVENT_FLAGS) &&
2004 (!fid_mode || mark_type == FAN_MARK_MOUNT))
2005 return -EINVAL;
2006
2007 /*
2008 * FAN_RENAME uses special info type records to report the old and
2009 * new parent+name. Reporting only old and new parent id is less
2010 * useful and was not implemented.
2011 */
2012 if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME))
2013 return -EINVAL;
2014
2015 /* Pre-content events are not currently generated for directories. */
2016 if (mask & FANOTIFY_PRE_CONTENT_EVENTS && mask & FAN_ONDIR)
2017 return -EINVAL;
2018
2019 if (mark_cmd == FAN_MARK_FLUSH) {
2020 fsnotify_clear_marks_by_group(group, obj_type);
2021 return 0;
2022 }
2023
2024 ret = fanotify_find_path(dfd, pathname, &path, flags,
2025 (mask & ALL_FSNOTIFY_EVENTS), obj_type);
2026 if (ret)
2027 return ret;
2028
2029 if (mark_cmd == FAN_MARK_ADD) {
2030 ret = fanotify_events_supported(group, &path, mask, flags);
2031 if (ret)
2032 goto path_put_and_out;
2033 }
2034
2035 /* you can only watch an inode if you have read permissions on it */
2036 ret = path_permission(&path, MAY_READ);
2037 if (ret)
2038 goto path_put_and_out;
2039
2040 ret = security_path_notify(&path, mask, obj_type);
2041 if (ret)
2042 goto path_put_and_out;
2043
2044 if (fid_mode) {
2045 ret = fanotify_test_fsid(path.dentry, flags, &__fsid);
2046 if (ret)
2047 goto path_put_and_out;
2048
2049 ret = fanotify_test_fid(path.dentry, flags);
2050 if (ret)
2051 goto path_put_and_out;
2052
2053 fsid = &__fsid;
2054 }
2055
2056 /*
2057 * In addition to being capable in the user ns where group was created,
2058 * the user also needs to be capable in the user ns associated with
2059 * the filesystem or in the user ns associated with the mntns
2060 * (when marking mntns).
2061 */
2062 if (obj_type == FSNOTIFY_OBJ_TYPE_INODE) {
2063 inode = path.dentry->d_inode;
2064 obj = inode;
2065 } else if (obj_type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
2066 user_ns = path.mnt->mnt_sb->s_user_ns;
2067 obj = path.mnt;
2068 } else if (obj_type == FSNOTIFY_OBJ_TYPE_SB) {
2069 user_ns = path.mnt->mnt_sb->s_user_ns;
2070 obj = path.mnt->mnt_sb;
2071 } else if (obj_type == FSNOTIFY_OBJ_TYPE_MNTNS) {
2072 ret = -EINVAL;
2073 mntns = mnt_ns_from_dentry(path.dentry);
2074 if (!mntns)
2075 goto path_put_and_out;
2076 user_ns = mntns->user_ns;
2077 obj = mntns;
2078 }
2079
2080 ret = -EPERM;
2081 if (user_ns && !ns_capable(user_ns, CAP_SYS_ADMIN))
2082 goto path_put_and_out;
2083
2084 ret = -EINVAL;
2085 if (!obj)
2086 goto path_put_and_out;
2087
2088 /*
2089 * If some other task has this inode open for write we should not add
2090 * an ignore mask, unless that ignore mask is supposed to survive
2091 * modification changes anyway.
2092 */
2093 if (mark_cmd == FAN_MARK_ADD && (flags & FANOTIFY_MARK_IGNORE_BITS) &&
2094 !(flags & FAN_MARK_IGNORED_SURV_MODIFY)) {
2095 ret = !inode ? -EINVAL : -EISDIR;
2096 /* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */
2097 if (ignore == FAN_MARK_IGNORE &&
2098 (!inode || S_ISDIR(inode->i_mode)))
2099 goto path_put_and_out;
2100
2101 ret = 0;
2102 if (inode && inode_is_open_for_write(inode))
2103 goto path_put_and_out;
2104 }
2105
2106 /* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */
2107 if (!inode || !S_ISDIR(inode->i_mode)) {
2108 mask &= ~FAN_EVENT_ON_CHILD;
2109 umask = FAN_EVENT_ON_CHILD;
2110 /*
2111 * If group needs to report parent fid, register for getting
2112 * events with parent/name info for non-directory.
2113 */
2114 if ((fid_mode & FAN_REPORT_DIR_FID) &&
2115 (flags & FAN_MARK_ADD) && !ignore)
2116 mask |= FAN_EVENT_ON_CHILD;
2117 }
2118
2119 /* create/update an inode mark */
2120 switch (mark_cmd) {
2121 case FAN_MARK_ADD:
2122 ret = fanotify_add_mark(group, obj, obj_type, mask, flags,
2123 fsid);
2124 break;
2125 case FAN_MARK_REMOVE:
2126 ret = fanotify_remove_mark(group, obj, obj_type, mask, flags,
2127 umask);
2128 break;
2129 default:
2130 ret = -EINVAL;
2131 }
2132
2133 path_put_and_out:
2134 path_put(&path);
2135 return ret;
2136 }
2137
2138 #ifndef CONFIG_ARCH_SPLIT_ARG64
SYSCALL_DEFINE5(fanotify_mark,int,fanotify_fd,unsigned int,flags,__u64,mask,int,dfd,const char __user *,pathname)2139 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
2140 __u64, mask, int, dfd,
2141 const char __user *, pathname)
2142 {
2143 return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname);
2144 }
2145 #endif
2146
2147 #if defined(CONFIG_ARCH_SPLIT_ARG64) || defined(CONFIG_COMPAT)
SYSCALL32_DEFINE6(fanotify_mark,int,fanotify_fd,unsigned int,flags,SC_ARG64 (mask),int,dfd,const char __user *,pathname)2148 SYSCALL32_DEFINE6(fanotify_mark,
2149 int, fanotify_fd, unsigned int, flags,
2150 SC_ARG64(mask), int, dfd,
2151 const char __user *, pathname)
2152 {
2153 return do_fanotify_mark(fanotify_fd, flags, SC_VAL64(__u64, mask),
2154 dfd, pathname);
2155 }
2156 #endif
2157
2158 /*
2159 * fanotify_user_setup - Our initialization function. Note that we cannot return
2160 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
2161 * must result in panic().
2162 */
fanotify_user_setup(void)2163 static int __init fanotify_user_setup(void)
2164 {
2165 struct sysinfo si;
2166 int max_marks;
2167
2168 si_meminfo(&si);
2169 /*
2170 * Allow up to 1% of addressable memory to be accounted for per user
2171 * marks limited to the range [8192, 1048576]. mount and sb marks are
2172 * a lot cheaper than inode marks, but there is no reason for a user
2173 * to have many of those, so calculate by the cost of inode marks.
2174 */
2175 max_marks = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) /
2176 INODE_MARK_COST;
2177 max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS,
2178 FANOTIFY_DEFAULT_MAX_USER_MARKS);
2179
2180 BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS);
2181 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 14);
2182 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11);
2183
2184 fanotify_mark_cache = KMEM_CACHE(fanotify_mark,
2185 SLAB_PANIC|SLAB_ACCOUNT);
2186 fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event,
2187 SLAB_PANIC);
2188 fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_event,
2189 SLAB_PANIC);
2190 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
2191 fanotify_perm_event_cachep =
2192 KMEM_CACHE(fanotify_perm_event, SLAB_PANIC);
2193 }
2194 fanotify_mnt_event_cachep = KMEM_CACHE(fanotify_mnt_event, SLAB_PANIC);
2195
2196 fanotify_max_queued_events = FANOTIFY_DEFAULT_MAX_EVENTS;
2197 init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] =
2198 FANOTIFY_DEFAULT_MAX_GROUPS;
2199 init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks;
2200 fanotify_sysctls_init();
2201
2202 return 0;
2203 }
2204 device_initcall(fanotify_user_setup);
2205