1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/fanotify.h>
3 #include <linux/fcntl.h>
4 #include <linux/fdtable.h>
5 #include <linux/file.h>
6 #include <linux/fs.h>
7 #include <linux/anon_inodes.h>
8 #include <linux/fsnotify_backend.h>
9 #include <linux/init.h>
10 #include <linux/mount.h>
11 #include <linux/namei.h>
12 #include <linux/poll.h>
13 #include <linux/security.h>
14 #include <linux/syscalls.h>
15 #include <linux/slab.h>
16 #include <linux/types.h>
17 #include <linux/uaccess.h>
18 #include <linux/compat.h>
19 #include <linux/sched/signal.h>
20 #include <linux/memcontrol.h>
21 #include <linux/statfs.h>
22 #include <linux/exportfs.h>
23
24 #include <asm/ioctls.h>
25
26 #include "../../mount.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
55 #ifdef CONFIG_SYSCTL
56
57 #include <linux/sysctl.h>
58
59 static long ft_zero = 0;
60 static long ft_int_max = INT_MAX;
61
62 static struct ctl_table fanotify_table[] = {
63 {
64 .procname = "max_user_groups",
65 .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS],
66 .maxlen = sizeof(long),
67 .mode = 0644,
68 .proc_handler = proc_doulongvec_minmax,
69 .extra1 = &ft_zero,
70 .extra2 = &ft_int_max,
71 },
72 {
73 .procname = "max_user_marks",
74 .data = &init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS],
75 .maxlen = sizeof(long),
76 .mode = 0644,
77 .proc_handler = proc_doulongvec_minmax,
78 .extra1 = &ft_zero,
79 .extra2 = &ft_int_max,
80 },
81 {
82 .procname = "max_queued_events",
83 .data = &fanotify_max_queued_events,
84 .maxlen = sizeof(int),
85 .mode = 0644,
86 .proc_handler = proc_dointvec_minmax,
87 .extra1 = SYSCTL_ZERO
88 },
89 { }
90 };
91
fanotify_sysctls_init(void)92 static void __init fanotify_sysctls_init(void)
93 {
94 register_sysctl("fs/fanotify", fanotify_table);
95 }
96 #else
97 #define fanotify_sysctls_init() do { } while (0)
98 #endif /* CONFIG_SYSCTL */
99
100 /*
101 * All flags that may be specified in parameter event_f_flags of fanotify_init.
102 *
103 * Internal and external open flags are stored together in field f_flags of
104 * struct file. Only external open flags shall be allowed in event_f_flags.
105 * Internal flags like FMODE_NONOTIFY, FMODE_EXEC, FMODE_NOCMTIME shall be
106 * excluded.
107 */
108 #define FANOTIFY_INIT_ALL_EVENT_F_BITS ( \
109 O_ACCMODE | O_APPEND | O_NONBLOCK | \
110 __O_SYNC | O_DSYNC | O_CLOEXEC | \
111 O_LARGEFILE | O_NOATIME )
112
113 extern const struct fsnotify_ops fanotify_fsnotify_ops;
114
115 struct kmem_cache *fanotify_mark_cache __read_mostly;
116 struct kmem_cache *fanotify_fid_event_cachep __read_mostly;
117 struct kmem_cache *fanotify_path_event_cachep __read_mostly;
118 struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
119
120 #define FANOTIFY_EVENT_ALIGN 4
121 #define FANOTIFY_FID_INFO_HDR_LEN \
122 (sizeof(struct fanotify_event_info_fid) + sizeof(struct file_handle))
123 #define FANOTIFY_PIDFD_INFO_HDR_LEN \
124 sizeof(struct fanotify_event_info_pidfd)
125 #define FANOTIFY_ERROR_INFO_LEN \
126 (sizeof(struct fanotify_event_info_error))
127
fanotify_fid_info_len(int fh_len,int name_len)128 static int fanotify_fid_info_len(int fh_len, int name_len)
129 {
130 int info_len = fh_len;
131
132 if (name_len)
133 info_len += name_len + 1;
134
135 return roundup(FANOTIFY_FID_INFO_HDR_LEN + info_len,
136 FANOTIFY_EVENT_ALIGN);
137 }
138
139 /* FAN_RENAME may have one or two dir+name info records */
fanotify_dir_name_info_len(struct fanotify_event * event)140 static int fanotify_dir_name_info_len(struct fanotify_event *event)
141 {
142 struct fanotify_info *info = fanotify_event_info(event);
143 int dir_fh_len = fanotify_event_dir_fh_len(event);
144 int dir2_fh_len = fanotify_event_dir2_fh_len(event);
145 int info_len = 0;
146
147 if (dir_fh_len)
148 info_len += fanotify_fid_info_len(dir_fh_len,
149 info->name_len);
150 if (dir2_fh_len)
151 info_len += fanotify_fid_info_len(dir2_fh_len,
152 info->name2_len);
153
154 return info_len;
155 }
156
fanotify_event_len(unsigned int info_mode,struct fanotify_event * event)157 static size_t fanotify_event_len(unsigned int info_mode,
158 struct fanotify_event *event)
159 {
160 size_t event_len = FAN_EVENT_METADATA_LEN;
161 int fh_len;
162 int dot_len = 0;
163
164 if (!info_mode)
165 return event_len;
166
167 if (fanotify_is_error_event(event->mask))
168 event_len += FANOTIFY_ERROR_INFO_LEN;
169
170 if (fanotify_event_has_any_dir_fh(event)) {
171 event_len += fanotify_dir_name_info_len(event);
172 } else if ((info_mode & FAN_REPORT_NAME) &&
173 (event->mask & FAN_ONDIR)) {
174 /*
175 * With group flag FAN_REPORT_NAME, if name was not recorded in
176 * event on a directory, we will report the name ".".
177 */
178 dot_len = 1;
179 }
180
181 if (info_mode & FAN_REPORT_PIDFD)
182 event_len += FANOTIFY_PIDFD_INFO_HDR_LEN;
183
184 if (fanotify_event_has_object_fh(event)) {
185 fh_len = fanotify_event_object_fh_len(event);
186 event_len += fanotify_fid_info_len(fh_len, dot_len);
187 }
188
189 return event_len;
190 }
191
192 /*
193 * Remove an hashed event from merge hash table.
194 */
fanotify_unhash_event(struct fsnotify_group * group,struct fanotify_event * event)195 static void fanotify_unhash_event(struct fsnotify_group *group,
196 struct fanotify_event *event)
197 {
198 assert_spin_locked(&group->notification_lock);
199
200 pr_debug("%s: group=%p event=%p bucket=%u\n", __func__,
201 group, event, fanotify_event_hash_bucket(group, event));
202
203 if (WARN_ON_ONCE(hlist_unhashed(&event->merge_list)))
204 return;
205
206 hlist_del_init(&event->merge_list);
207 }
208
209 /*
210 * Get an fanotify notification event if one exists and is small
211 * enough to fit in "count". Return an error pointer if the count
212 * is not large enough. When permission event is dequeued, its state is
213 * updated accordingly.
214 */
get_one_event(struct fsnotify_group * group,size_t count)215 static struct fanotify_event *get_one_event(struct fsnotify_group *group,
216 size_t count)
217 {
218 size_t event_size;
219 struct fanotify_event *event = NULL;
220 struct fsnotify_event *fsn_event;
221 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
222
223 pr_debug("%s: group=%p count=%zd\n", __func__, group, count);
224
225 spin_lock(&group->notification_lock);
226 fsn_event = fsnotify_peek_first_event(group);
227 if (!fsn_event)
228 goto out;
229
230 event = FANOTIFY_E(fsn_event);
231 event_size = fanotify_event_len(info_mode, event);
232
233 if (event_size > count) {
234 event = ERR_PTR(-EINVAL);
235 goto out;
236 }
237
238 /*
239 * Held the notification_lock the whole time, so this is the
240 * same event we peeked above.
241 */
242 fsnotify_remove_first_event(group);
243 if (fanotify_is_perm_event(event->mask))
244 FANOTIFY_PERM(event)->state = FAN_EVENT_REPORTED;
245 if (fanotify_is_hashed_event(event->mask))
246 fanotify_unhash_event(group, event);
247 out:
248 spin_unlock(&group->notification_lock);
249 return event;
250 }
251
create_fd(struct fsnotify_group * group,const struct path * path,struct file ** file)252 static int create_fd(struct fsnotify_group *group, const struct path *path,
253 struct file **file)
254 {
255 int client_fd;
256 struct file *new_file;
257
258 client_fd = get_unused_fd_flags(group->fanotify_data.f_flags);
259 if (client_fd < 0)
260 return client_fd;
261
262 /*
263 * we need a new file handle for the userspace program so it can read even if it was
264 * originally opened O_WRONLY.
265 */
266 new_file = dentry_open(path,
267 group->fanotify_data.f_flags | __FMODE_NONOTIFY,
268 current_cred());
269 if (IS_ERR(new_file)) {
270 put_unused_fd(client_fd);
271 client_fd = PTR_ERR(new_file);
272 } else {
273 *file = new_file;
274 }
275
276 return client_fd;
277 }
278
process_access_response_info(const char __user * info,size_t info_len,struct fanotify_response_info_audit_rule * friar)279 static int process_access_response_info(const char __user *info,
280 size_t info_len,
281 struct fanotify_response_info_audit_rule *friar)
282 {
283 if (info_len != sizeof(*friar))
284 return -EINVAL;
285
286 if (copy_from_user(friar, info, sizeof(*friar)))
287 return -EFAULT;
288
289 if (friar->hdr.type != FAN_RESPONSE_INFO_AUDIT_RULE)
290 return -EINVAL;
291 if (friar->hdr.pad != 0)
292 return -EINVAL;
293 if (friar->hdr.len != sizeof(*friar))
294 return -EINVAL;
295
296 return info_len;
297 }
298
299 /*
300 * Finish processing of permission event by setting it to ANSWERED state and
301 * drop group->notification_lock.
302 */
finish_permission_event(struct fsnotify_group * group,struct fanotify_perm_event * event,u32 response,struct fanotify_response_info_audit_rule * friar)303 static void finish_permission_event(struct fsnotify_group *group,
304 struct fanotify_perm_event *event, u32 response,
305 struct fanotify_response_info_audit_rule *friar)
306 __releases(&group->notification_lock)
307 {
308 bool destroy = false;
309
310 assert_spin_locked(&group->notification_lock);
311 event->response = response & ~FAN_INFO;
312 if (response & FAN_INFO)
313 memcpy(&event->audit_rule, friar, sizeof(*friar));
314
315 if (event->state == FAN_EVENT_CANCELED)
316 destroy = true;
317 else
318 event->state = FAN_EVENT_ANSWERED;
319 spin_unlock(&group->notification_lock);
320 if (destroy)
321 fsnotify_destroy_event(group, &event->fae.fse);
322 }
323
process_access_response(struct fsnotify_group * group,struct fanotify_response * response_struct,const char __user * info,size_t info_len)324 static int process_access_response(struct fsnotify_group *group,
325 struct fanotify_response *response_struct,
326 const char __user *info,
327 size_t info_len)
328 {
329 struct fanotify_perm_event *event;
330 int fd = response_struct->fd;
331 u32 response = response_struct->response;
332 int ret = info_len;
333 struct fanotify_response_info_audit_rule friar;
334
335 pr_debug("%s: group=%p fd=%d response=%u buf=%p size=%zu\n", __func__,
336 group, fd, response, info, info_len);
337 /*
338 * make sure the response is valid, if invalid we do nothing and either
339 * userspace can send a valid response or we will clean it up after the
340 * timeout
341 */
342 if (response & ~FANOTIFY_RESPONSE_VALID_MASK)
343 return -EINVAL;
344
345 switch (response & FANOTIFY_RESPONSE_ACCESS) {
346 case FAN_ALLOW:
347 case FAN_DENY:
348 break;
349 default:
350 return -EINVAL;
351 }
352
353 if ((response & FAN_AUDIT) && !FAN_GROUP_FLAG(group, FAN_ENABLE_AUDIT))
354 return -EINVAL;
355
356 if (response & FAN_INFO) {
357 ret = process_access_response_info(info, info_len, &friar);
358 if (ret < 0)
359 return ret;
360 if (fd == FAN_NOFD)
361 return ret;
362 } else {
363 ret = 0;
364 }
365
366 if (fd < 0)
367 return -EINVAL;
368
369 spin_lock(&group->notification_lock);
370 list_for_each_entry(event, &group->fanotify_data.access_list,
371 fae.fse.list) {
372 if (event->fd != fd)
373 continue;
374
375 list_del_init(&event->fae.fse.list);
376 finish_permission_event(group, event, response, &friar);
377 wake_up(&group->fanotify_data.access_waitq);
378 return ret;
379 }
380 spin_unlock(&group->notification_lock);
381
382 return -ENOENT;
383 }
384
copy_error_info_to_user(struct fanotify_event * event,char __user * buf,int count)385 static size_t copy_error_info_to_user(struct fanotify_event *event,
386 char __user *buf, int count)
387 {
388 struct fanotify_event_info_error info = { };
389 struct fanotify_error_event *fee = FANOTIFY_EE(event);
390
391 info.hdr.info_type = FAN_EVENT_INFO_TYPE_ERROR;
392 info.hdr.len = FANOTIFY_ERROR_INFO_LEN;
393
394 if (WARN_ON(count < info.hdr.len))
395 return -EFAULT;
396
397 info.error = fee->error;
398 info.error_count = fee->err_count;
399
400 if (copy_to_user(buf, &info, sizeof(info)))
401 return -EFAULT;
402
403 return info.hdr.len;
404 }
405
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)406 static int copy_fid_info_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
407 int info_type, const char *name,
408 size_t name_len,
409 char __user *buf, size_t count)
410 {
411 struct fanotify_event_info_fid info = { };
412 struct file_handle handle = { };
413 unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf;
414 size_t fh_len = fh ? fh->len : 0;
415 size_t info_len = fanotify_fid_info_len(fh_len, name_len);
416 size_t len = info_len;
417
418 pr_debug("%s: fh_len=%zu name_len=%zu, info_len=%zu, count=%zu\n",
419 __func__, fh_len, name_len, info_len, count);
420
421 if (WARN_ON_ONCE(len < sizeof(info) || len > count))
422 return -EFAULT;
423
424 /*
425 * Copy event info fid header followed by variable sized file handle
426 * and optionally followed by variable sized filename.
427 */
428 switch (info_type) {
429 case FAN_EVENT_INFO_TYPE_FID:
430 case FAN_EVENT_INFO_TYPE_DFID:
431 if (WARN_ON_ONCE(name_len))
432 return -EFAULT;
433 break;
434 case FAN_EVENT_INFO_TYPE_DFID_NAME:
435 case FAN_EVENT_INFO_TYPE_OLD_DFID_NAME:
436 case FAN_EVENT_INFO_TYPE_NEW_DFID_NAME:
437 if (WARN_ON_ONCE(!name || !name_len))
438 return -EFAULT;
439 break;
440 default:
441 return -EFAULT;
442 }
443
444 info.hdr.info_type = info_type;
445 info.hdr.len = len;
446 info.fsid = *fsid;
447 if (copy_to_user(buf, &info, sizeof(info)))
448 return -EFAULT;
449
450 buf += sizeof(info);
451 len -= sizeof(info);
452 if (WARN_ON_ONCE(len < sizeof(handle)))
453 return -EFAULT;
454
455 handle.handle_type = fh->type;
456 handle.handle_bytes = fh_len;
457
458 /* Mangle handle_type for bad file_handle */
459 if (!fh_len)
460 handle.handle_type = FILEID_INVALID;
461
462 if (copy_to_user(buf, &handle, sizeof(handle)))
463 return -EFAULT;
464
465 buf += sizeof(handle);
466 len -= sizeof(handle);
467 if (WARN_ON_ONCE(len < fh_len))
468 return -EFAULT;
469
470 /*
471 * For an inline fh and inline file name, copy through stack to exclude
472 * the copy from usercopy hardening protections.
473 */
474 fh_buf = fanotify_fh_buf(fh);
475 if (fh_len <= FANOTIFY_INLINE_FH_LEN) {
476 memcpy(bounce, fh_buf, fh_len);
477 fh_buf = bounce;
478 }
479 if (copy_to_user(buf, fh_buf, fh_len))
480 return -EFAULT;
481
482 buf += fh_len;
483 len -= fh_len;
484
485 if (name_len) {
486 /* Copy the filename with terminating null */
487 name_len++;
488 if (WARN_ON_ONCE(len < name_len))
489 return -EFAULT;
490
491 if (copy_to_user(buf, name, name_len))
492 return -EFAULT;
493
494 buf += name_len;
495 len -= name_len;
496 }
497
498 /* Pad with 0's */
499 WARN_ON_ONCE(len < 0 || len >= FANOTIFY_EVENT_ALIGN);
500 if (len > 0 && clear_user(buf, len))
501 return -EFAULT;
502
503 return info_len;
504 }
505
copy_pidfd_info_to_user(int pidfd,char __user * buf,size_t count)506 static int copy_pidfd_info_to_user(int pidfd,
507 char __user *buf,
508 size_t count)
509 {
510 struct fanotify_event_info_pidfd info = { };
511 size_t info_len = FANOTIFY_PIDFD_INFO_HDR_LEN;
512
513 if (WARN_ON_ONCE(info_len > count))
514 return -EFAULT;
515
516 info.hdr.info_type = FAN_EVENT_INFO_TYPE_PIDFD;
517 info.hdr.len = info_len;
518 info.pidfd = pidfd;
519
520 if (copy_to_user(buf, &info, info_len))
521 return -EFAULT;
522
523 return info_len;
524 }
525
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)526 static int copy_info_records_to_user(struct fanotify_event *event,
527 struct fanotify_info *info,
528 unsigned int info_mode, int pidfd,
529 char __user *buf, size_t count)
530 {
531 int ret, total_bytes = 0, info_type = 0;
532 unsigned int fid_mode = info_mode & FANOTIFY_FID_BITS;
533 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
534
535 /*
536 * Event info records order is as follows:
537 * 1. dir fid + name
538 * 2. (optional) new dir fid + new name
539 * 3. (optional) child fid
540 */
541 if (fanotify_event_has_dir_fh(event)) {
542 info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
543 FAN_EVENT_INFO_TYPE_DFID;
544
545 /* FAN_RENAME uses special info types */
546 if (event->mask & FAN_RENAME)
547 info_type = FAN_EVENT_INFO_TYPE_OLD_DFID_NAME;
548
549 ret = copy_fid_info_to_user(fanotify_event_fsid(event),
550 fanotify_info_dir_fh(info),
551 info_type,
552 fanotify_info_name(info),
553 info->name_len, buf, count);
554 if (ret < 0)
555 return ret;
556
557 buf += ret;
558 count -= ret;
559 total_bytes += ret;
560 }
561
562 /* New dir fid+name may be reported in addition to old dir fid+name */
563 if (fanotify_event_has_dir2_fh(event)) {
564 info_type = FAN_EVENT_INFO_TYPE_NEW_DFID_NAME;
565 ret = copy_fid_info_to_user(fanotify_event_fsid(event),
566 fanotify_info_dir2_fh(info),
567 info_type,
568 fanotify_info_name2(info),
569 info->name2_len, buf, count);
570 if (ret < 0)
571 return ret;
572
573 buf += ret;
574 count -= ret;
575 total_bytes += ret;
576 }
577
578 if (fanotify_event_has_object_fh(event)) {
579 const char *dot = NULL;
580 int dot_len = 0;
581
582 if (fid_mode == FAN_REPORT_FID || info_type) {
583 /*
584 * With only group flag FAN_REPORT_FID only type FID is
585 * reported. Second info record type is always FID.
586 */
587 info_type = FAN_EVENT_INFO_TYPE_FID;
588 } else if ((fid_mode & FAN_REPORT_NAME) &&
589 (event->mask & FAN_ONDIR)) {
590 /*
591 * With group flag FAN_REPORT_NAME, if name was not
592 * recorded in an event on a directory, report the name
593 * "." with info type DFID_NAME.
594 */
595 info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
596 dot = ".";
597 dot_len = 1;
598 } else if ((event->mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
599 (event->mask & FAN_ONDIR)) {
600 /*
601 * With group flag FAN_REPORT_DIR_FID, a single info
602 * record has type DFID for directory entry modification
603 * event and for event on a directory.
604 */
605 info_type = FAN_EVENT_INFO_TYPE_DFID;
606 } else {
607 /*
608 * With group flags FAN_REPORT_DIR_FID|FAN_REPORT_FID,
609 * a single info record has type FID for event on a
610 * non-directory, when there is no directory to report.
611 * For example, on FAN_DELETE_SELF event.
612 */
613 info_type = FAN_EVENT_INFO_TYPE_FID;
614 }
615
616 ret = copy_fid_info_to_user(fanotify_event_fsid(event),
617 fanotify_event_object_fh(event),
618 info_type, dot, dot_len,
619 buf, count);
620 if (ret < 0)
621 return ret;
622
623 buf += ret;
624 count -= ret;
625 total_bytes += ret;
626 }
627
628 if (pidfd_mode) {
629 ret = copy_pidfd_info_to_user(pidfd, buf, count);
630 if (ret < 0)
631 return ret;
632
633 buf += ret;
634 count -= ret;
635 total_bytes += ret;
636 }
637
638 if (fanotify_is_error_event(event->mask)) {
639 ret = copy_error_info_to_user(event, buf, count);
640 if (ret < 0)
641 return ret;
642 buf += ret;
643 count -= ret;
644 total_bytes += ret;
645 }
646
647 return total_bytes;
648 }
649
copy_event_to_user(struct fsnotify_group * group,struct fanotify_event * event,char __user * buf,size_t count)650 static ssize_t copy_event_to_user(struct fsnotify_group *group,
651 struct fanotify_event *event,
652 char __user *buf, size_t count)
653 {
654 struct fanotify_event_metadata metadata;
655 const struct path *path = fanotify_event_path(event);
656 struct fanotify_info *info = fanotify_event_info(event);
657 unsigned int info_mode = FAN_GROUP_FLAG(group, FANOTIFY_INFO_MODES);
658 unsigned int pidfd_mode = info_mode & FAN_REPORT_PIDFD;
659 struct file *f = NULL, *pidfd_file = NULL;
660 int ret, pidfd = -ESRCH, fd = -EBADF;
661
662 pr_debug("%s: group=%p event=%p\n", __func__, group, event);
663
664 metadata.event_len = fanotify_event_len(info_mode, event);
665 metadata.metadata_len = FAN_EVENT_METADATA_LEN;
666 metadata.vers = FANOTIFY_METADATA_VERSION;
667 metadata.reserved = 0;
668 metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS;
669 metadata.pid = pid_vnr(event->pid);
670 /*
671 * For an unprivileged listener, event->pid can be used to identify the
672 * events generated by the listener process itself, without disclosing
673 * the pids of other processes.
674 */
675 if (FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
676 task_tgid(current) != event->pid)
677 metadata.pid = 0;
678
679 /*
680 * For now, fid mode is required for an unprivileged listener and
681 * fid mode does not report fd in events. Keep this check anyway
682 * for safety in case fid mode requirement is relaxed in the future
683 * to allow unprivileged listener to get events with no fd and no fid.
684 */
685 if (!FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV) &&
686 path && path->mnt && path->dentry) {
687 fd = create_fd(group, path, &f);
688 /*
689 * Opening an fd from dentry can fail for several reasons.
690 * For example, when tasks are gone and we try to open their
691 * /proc files or we try to open a WRONLY file like in sysfs
692 * or when trying to open a file that was deleted on the
693 * remote network server.
694 *
695 * For a group with FAN_REPORT_FD_ERROR, we will send the
696 * event with the error instead of the open fd, otherwise
697 * Userspace may not get the error at all.
698 * In any case, userspace will not know which file failed to
699 * open, so add a debug print for further investigation.
700 */
701 if (fd < 0) {
702 pr_debug("fanotify: create_fd(%pd2) failed err=%d\n",
703 path->dentry, fd);
704 if (!FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR)) {
705 /*
706 * Historically, we've handled EOPENSTALE in a
707 * special way and silently dropped such
708 * events. Now we have to keep it to maintain
709 * backward compatibility...
710 */
711 if (fd == -EOPENSTALE)
712 fd = 0;
713 return fd;
714 }
715 }
716 }
717 if (FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR))
718 metadata.fd = fd;
719 else
720 metadata.fd = fd >= 0 ? fd : FAN_NOFD;
721
722 if (pidfd_mode) {
723 /*
724 * Complain if the FAN_REPORT_PIDFD and FAN_REPORT_TID mutual
725 * exclusion is ever lifted. At the time of incoporating pidfd
726 * support within fanotify, the pidfd API only supported the
727 * creation of pidfds for thread-group leaders.
728 */
729 WARN_ON_ONCE(FAN_GROUP_FLAG(group, FAN_REPORT_TID));
730
731 /*
732 * The PIDTYPE_TGID check for an event->pid is performed
733 * preemptively in an attempt to catch out cases where the event
734 * listener reads events after the event generating process has
735 * already terminated. Depending on flag FAN_REPORT_FD_ERROR,
736 * report either -ESRCH or FAN_NOPIDFD to the event listener in
737 * those cases with all other pidfd creation errors reported as
738 * the error code itself or as FAN_EPIDFD.
739 */
740 if (metadata.pid && pid_has_task(event->pid, PIDTYPE_TGID))
741 pidfd = pidfd_prepare(event->pid, 0, &pidfd_file);
742
743 if (!FAN_GROUP_FLAG(group, FAN_REPORT_FD_ERROR) && pidfd < 0)
744 pidfd = pidfd == -ESRCH ? FAN_NOPIDFD : FAN_EPIDFD;
745 }
746
747 ret = -EFAULT;
748 /*
749 * Sanity check copy size in case get_one_event() and
750 * event_len sizes ever get out of sync.
751 */
752 if (WARN_ON_ONCE(metadata.event_len > count))
753 goto out_close_fd;
754
755 if (copy_to_user(buf, &metadata, FAN_EVENT_METADATA_LEN))
756 goto out_close_fd;
757
758 buf += FAN_EVENT_METADATA_LEN;
759 count -= FAN_EVENT_METADATA_LEN;
760
761 if (info_mode) {
762 ret = copy_info_records_to_user(event, info, info_mode, pidfd,
763 buf, count);
764 if (ret < 0)
765 goto out_close_fd;
766 }
767
768 if (f)
769 fd_install(fd, f);
770
771 if (pidfd_file)
772 fd_install(pidfd, pidfd_file);
773
774 if (fanotify_is_perm_event(event->mask))
775 FANOTIFY_PERM(event)->fd = fd;
776
777 return metadata.event_len;
778
779 out_close_fd:
780 if (f) {
781 put_unused_fd(fd);
782 fput(f);
783 }
784
785 if (pidfd_file) {
786 put_unused_fd(pidfd);
787 fput(pidfd_file);
788 }
789
790 return ret;
791 }
792
793 /* intofiy userspace file descriptor functions */
fanotify_poll(struct file * file,poll_table * wait)794 static __poll_t fanotify_poll(struct file *file, poll_table *wait)
795 {
796 struct fsnotify_group *group = file->private_data;
797 __poll_t ret = 0;
798
799 poll_wait(file, &group->notification_waitq, wait);
800 spin_lock(&group->notification_lock);
801 if (!fsnotify_notify_queue_is_empty(group))
802 ret = EPOLLIN | EPOLLRDNORM;
803 spin_unlock(&group->notification_lock);
804
805 return ret;
806 }
807
fanotify_read(struct file * file,char __user * buf,size_t count,loff_t * pos)808 static ssize_t fanotify_read(struct file *file, char __user *buf,
809 size_t count, loff_t *pos)
810 {
811 struct fsnotify_group *group;
812 struct fanotify_event *event;
813 char __user *start;
814 int ret;
815 DEFINE_WAIT_FUNC(wait, woken_wake_function);
816
817 start = buf;
818 group = file->private_data;
819
820 pr_debug("%s: group=%p\n", __func__, group);
821
822 add_wait_queue(&group->notification_waitq, &wait);
823 while (1) {
824 /*
825 * User can supply arbitrarily large buffer. Avoid softlockups
826 * in case there are lots of available events.
827 */
828 cond_resched();
829 event = get_one_event(group, count);
830 if (IS_ERR(event)) {
831 ret = PTR_ERR(event);
832 break;
833 }
834
835 if (!event) {
836 ret = -EAGAIN;
837 if (file->f_flags & O_NONBLOCK)
838 break;
839
840 ret = -ERESTARTSYS;
841 if (signal_pending(current))
842 break;
843
844 if (start != buf)
845 break;
846
847 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
848 continue;
849 }
850
851 ret = copy_event_to_user(group, event, buf, count);
852
853 /*
854 * Permission events get queued to wait for response. Other
855 * events can be destroyed now.
856 */
857 if (!fanotify_is_perm_event(event->mask)) {
858 fsnotify_destroy_event(group, &event->fse);
859 } else {
860 if (ret <= 0 || FANOTIFY_PERM(event)->fd < 0) {
861 spin_lock(&group->notification_lock);
862 finish_permission_event(group,
863 FANOTIFY_PERM(event), FAN_DENY, NULL);
864 wake_up(&group->fanotify_data.access_waitq);
865 } else {
866 spin_lock(&group->notification_lock);
867 list_add_tail(&event->fse.list,
868 &group->fanotify_data.access_list);
869 spin_unlock(&group->notification_lock);
870 }
871 }
872 if (ret < 0)
873 break;
874 buf += ret;
875 count -= ret;
876 }
877 remove_wait_queue(&group->notification_waitq, &wait);
878
879 if (start != buf && ret != -EFAULT)
880 ret = buf - start;
881 return ret;
882 }
883
fanotify_write(struct file * file,const char __user * buf,size_t count,loff_t * pos)884 static ssize_t fanotify_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
885 {
886 struct fanotify_response response;
887 struct fsnotify_group *group;
888 int ret;
889 const char __user *info_buf = buf + sizeof(struct fanotify_response);
890 size_t info_len;
891
892 if (!IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
893 return -EINVAL;
894
895 group = file->private_data;
896
897 pr_debug("%s: group=%p count=%zu\n", __func__, group, count);
898
899 if (count < sizeof(response))
900 return -EINVAL;
901
902 if (copy_from_user(&response, buf, sizeof(response)))
903 return -EFAULT;
904
905 info_len = count - sizeof(response);
906
907 ret = process_access_response(group, &response, info_buf, info_len);
908 if (ret < 0)
909 count = ret;
910 else
911 count = sizeof(response) + ret;
912
913 return count;
914 }
915
fanotify_release(struct inode * ignored,struct file * file)916 static int fanotify_release(struct inode *ignored, struct file *file)
917 {
918 struct fsnotify_group *group = file->private_data;
919 struct fsnotify_event *fsn_event;
920
921 /*
922 * Stop new events from arriving in the notification queue. since
923 * userspace cannot use fanotify fd anymore, no event can enter or
924 * leave access_list by now either.
925 */
926 fsnotify_group_stop_queueing(group);
927
928 /*
929 * Process all permission events on access_list and notification queue
930 * and simulate reply from userspace.
931 */
932 spin_lock(&group->notification_lock);
933 while (!list_empty(&group->fanotify_data.access_list)) {
934 struct fanotify_perm_event *event;
935
936 event = list_first_entry(&group->fanotify_data.access_list,
937 struct fanotify_perm_event, fae.fse.list);
938 list_del_init(&event->fae.fse.list);
939 finish_permission_event(group, event, FAN_ALLOW, NULL);
940 spin_lock(&group->notification_lock);
941 }
942
943 /*
944 * Destroy all non-permission events. For permission events just
945 * dequeue them and set the response. They will be freed once the
946 * response is consumed and fanotify_get_response() returns.
947 */
948 while ((fsn_event = fsnotify_remove_first_event(group))) {
949 struct fanotify_event *event = FANOTIFY_E(fsn_event);
950
951 if (!(event->mask & FANOTIFY_PERM_EVENTS)) {
952 spin_unlock(&group->notification_lock);
953 fsnotify_destroy_event(group, fsn_event);
954 } else {
955 finish_permission_event(group, FANOTIFY_PERM(event),
956 FAN_ALLOW, NULL);
957 }
958 spin_lock(&group->notification_lock);
959 }
960 spin_unlock(&group->notification_lock);
961
962 /* Response for all permission events it set, wakeup waiters */
963 wake_up(&group->fanotify_data.access_waitq);
964
965 /* matches the fanotify_init->fsnotify_alloc_group */
966 fsnotify_destroy_group(group);
967
968 return 0;
969 }
970
fanotify_ioctl(struct file * file,unsigned int cmd,unsigned long arg)971 static long fanotify_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
972 {
973 struct fsnotify_group *group;
974 struct fsnotify_event *fsn_event;
975 void __user *p;
976 int ret = -ENOTTY;
977 size_t send_len = 0;
978
979 group = file->private_data;
980
981 p = (void __user *) arg;
982
983 switch (cmd) {
984 case FIONREAD:
985 spin_lock(&group->notification_lock);
986 list_for_each_entry(fsn_event, &group->notification_list, list)
987 send_len += FAN_EVENT_METADATA_LEN;
988 spin_unlock(&group->notification_lock);
989 ret = put_user(send_len, (int __user *) p);
990 break;
991 }
992
993 return ret;
994 }
995
996 static const struct file_operations fanotify_fops = {
997 .show_fdinfo = fanotify_show_fdinfo,
998 .poll = fanotify_poll,
999 .read = fanotify_read,
1000 .write = fanotify_write,
1001 .fasync = NULL,
1002 .release = fanotify_release,
1003 .unlocked_ioctl = fanotify_ioctl,
1004 .compat_ioctl = compat_ptr_ioctl,
1005 .llseek = noop_llseek,
1006 };
1007
fanotify_find_path(int dfd,const char __user * filename,struct path * path,unsigned int flags,__u64 mask,unsigned int obj_type)1008 static int fanotify_find_path(int dfd, const char __user *filename,
1009 struct path *path, unsigned int flags, __u64 mask,
1010 unsigned int obj_type)
1011 {
1012 int ret;
1013
1014 pr_debug("%s: dfd=%d filename=%p flags=%x\n", __func__,
1015 dfd, filename, flags);
1016
1017 if (filename == NULL) {
1018 struct fd f = fdget(dfd);
1019
1020 ret = -EBADF;
1021 if (!f.file)
1022 goto out;
1023
1024 ret = -ENOTDIR;
1025 if ((flags & FAN_MARK_ONLYDIR) &&
1026 !(S_ISDIR(file_inode(f.file)->i_mode))) {
1027 fdput(f);
1028 goto out;
1029 }
1030
1031 *path = f.file->f_path;
1032 path_get(path);
1033 fdput(f);
1034 } else {
1035 unsigned int lookup_flags = 0;
1036
1037 if (!(flags & FAN_MARK_DONT_FOLLOW))
1038 lookup_flags |= LOOKUP_FOLLOW;
1039 if (flags & FAN_MARK_ONLYDIR)
1040 lookup_flags |= LOOKUP_DIRECTORY;
1041
1042 ret = user_path_at(dfd, filename, lookup_flags, path);
1043 if (ret)
1044 goto out;
1045 }
1046
1047 /* you can only watch an inode if you have read permissions on it */
1048 ret = path_permission(path, MAY_READ);
1049 if (ret) {
1050 path_put(path);
1051 goto out;
1052 }
1053
1054 ret = security_path_notify(path, mask, obj_type);
1055 if (ret)
1056 path_put(path);
1057
1058 out:
1059 return ret;
1060 }
1061
fanotify_mark_remove_from_mask(struct fsnotify_mark * fsn_mark,__u32 mask,unsigned int flags,__u32 umask,int * destroy)1062 static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
1063 __u32 mask, unsigned int flags,
1064 __u32 umask, int *destroy)
1065 {
1066 __u32 oldmask, newmask;
1067
1068 /* umask bits cannot be removed by user */
1069 mask &= ~umask;
1070 spin_lock(&fsn_mark->lock);
1071 oldmask = fsnotify_calc_mask(fsn_mark);
1072 if (!(flags & FANOTIFY_MARK_IGNORE_BITS)) {
1073 fsn_mark->mask &= ~mask;
1074 } else {
1075 fsn_mark->ignore_mask &= ~mask;
1076 }
1077 newmask = fsnotify_calc_mask(fsn_mark);
1078 /*
1079 * We need to keep the mark around even if remaining mask cannot
1080 * result in any events (e.g. mask == FAN_ONDIR) to support incremenal
1081 * changes to the mask.
1082 * Destroy mark when only umask bits remain.
1083 */
1084 *destroy = !((fsn_mark->mask | fsn_mark->ignore_mask) & ~umask);
1085 spin_unlock(&fsn_mark->lock);
1086
1087 return oldmask & ~newmask;
1088 }
1089
fanotify_remove_mark(struct fsnotify_group * group,fsnotify_connp_t * connp,__u32 mask,unsigned int flags,__u32 umask)1090 static int fanotify_remove_mark(struct fsnotify_group *group,
1091 fsnotify_connp_t *connp, __u32 mask,
1092 unsigned int flags, __u32 umask)
1093 {
1094 struct fsnotify_mark *fsn_mark = NULL;
1095 __u32 removed;
1096 int destroy_mark;
1097
1098 fsnotify_group_lock(group);
1099 fsn_mark = fsnotify_find_mark(connp, group);
1100 if (!fsn_mark) {
1101 fsnotify_group_unlock(group);
1102 return -ENOENT;
1103 }
1104
1105 removed = fanotify_mark_remove_from_mask(fsn_mark, mask, flags,
1106 umask, &destroy_mark);
1107 if (removed & fsnotify_conn_mask(fsn_mark->connector))
1108 fsnotify_recalc_mask(fsn_mark->connector);
1109 if (destroy_mark)
1110 fsnotify_detach_mark(fsn_mark);
1111 fsnotify_group_unlock(group);
1112 if (destroy_mark)
1113 fsnotify_free_mark(fsn_mark);
1114
1115 /* matches the fsnotify_find_mark() */
1116 fsnotify_put_mark(fsn_mark);
1117 return 0;
1118 }
1119
fanotify_remove_vfsmount_mark(struct fsnotify_group * group,struct vfsmount * mnt,__u32 mask,unsigned int flags,__u32 umask)1120 static int fanotify_remove_vfsmount_mark(struct fsnotify_group *group,
1121 struct vfsmount *mnt, __u32 mask,
1122 unsigned int flags, __u32 umask)
1123 {
1124 return fanotify_remove_mark(group, &real_mount(mnt)->mnt_fsnotify_marks,
1125 mask, flags, umask);
1126 }
1127
fanotify_remove_sb_mark(struct fsnotify_group * group,struct super_block * sb,__u32 mask,unsigned int flags,__u32 umask)1128 static int fanotify_remove_sb_mark(struct fsnotify_group *group,
1129 struct super_block *sb, __u32 mask,
1130 unsigned int flags, __u32 umask)
1131 {
1132 return fanotify_remove_mark(group, &sb->s_fsnotify_marks, mask,
1133 flags, umask);
1134 }
1135
fanotify_remove_inode_mark(struct fsnotify_group * group,struct inode * inode,__u32 mask,unsigned int flags,__u32 umask)1136 static int fanotify_remove_inode_mark(struct fsnotify_group *group,
1137 struct inode *inode, __u32 mask,
1138 unsigned int flags, __u32 umask)
1139 {
1140 return fanotify_remove_mark(group, &inode->i_fsnotify_marks, mask,
1141 flags, umask);
1142 }
1143
fanotify_mark_update_flags(struct fsnotify_mark * fsn_mark,unsigned int fan_flags)1144 static bool fanotify_mark_update_flags(struct fsnotify_mark *fsn_mark,
1145 unsigned int fan_flags)
1146 {
1147 bool want_iref = !(fan_flags & FAN_MARK_EVICTABLE);
1148 unsigned int ignore = fan_flags & FANOTIFY_MARK_IGNORE_BITS;
1149 bool recalc = false;
1150
1151 /*
1152 * When using FAN_MARK_IGNORE for the first time, mark starts using
1153 * independent event flags in ignore mask. After that, trying to
1154 * update the ignore mask with the old FAN_MARK_IGNORED_MASK API
1155 * will result in EEXIST error.
1156 */
1157 if (ignore == FAN_MARK_IGNORE)
1158 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS;
1159
1160 /*
1161 * Setting FAN_MARK_IGNORED_SURV_MODIFY for the first time may lead to
1162 * the removal of the FS_MODIFY bit in calculated mask if it was set
1163 * because of an ignore mask that is now going to survive FS_MODIFY.
1164 */
1165 if (ignore && (fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
1166 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) {
1167 fsn_mark->flags |= FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
1168 if (!(fsn_mark->mask & FS_MODIFY))
1169 recalc = true;
1170 }
1171
1172 if (fsn_mark->connector->type != FSNOTIFY_OBJ_TYPE_INODE ||
1173 want_iref == !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF))
1174 return recalc;
1175
1176 /*
1177 * NO_IREF may be removed from a mark, but not added.
1178 * When removed, fsnotify_recalc_mask() will take the inode ref.
1179 */
1180 WARN_ON_ONCE(!want_iref);
1181 fsn_mark->flags &= ~FSNOTIFY_MARK_FLAG_NO_IREF;
1182
1183 return true;
1184 }
1185
fanotify_mark_add_to_mask(struct fsnotify_mark * fsn_mark,__u32 mask,unsigned int fan_flags)1186 static bool fanotify_mark_add_to_mask(struct fsnotify_mark *fsn_mark,
1187 __u32 mask, unsigned int fan_flags)
1188 {
1189 bool recalc;
1190
1191 spin_lock(&fsn_mark->lock);
1192 if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS))
1193 fsn_mark->mask |= mask;
1194 else
1195 fsn_mark->ignore_mask |= mask;
1196
1197 recalc = fsnotify_calc_mask(fsn_mark) &
1198 ~fsnotify_conn_mask(fsn_mark->connector);
1199
1200 recalc |= fanotify_mark_update_flags(fsn_mark, fan_flags);
1201 spin_unlock(&fsn_mark->lock);
1202
1203 return recalc;
1204 }
1205
fanotify_add_new_mark(struct fsnotify_group * group,fsnotify_connp_t * connp,unsigned int obj_type,unsigned int fan_flags,__kernel_fsid_t * fsid)1206 static struct fsnotify_mark *fanotify_add_new_mark(struct fsnotify_group *group,
1207 fsnotify_connp_t *connp,
1208 unsigned int obj_type,
1209 unsigned int fan_flags,
1210 __kernel_fsid_t *fsid)
1211 {
1212 struct ucounts *ucounts = group->fanotify_data.ucounts;
1213 struct fsnotify_mark *mark;
1214 int ret;
1215
1216 /*
1217 * Enforce per user marks limits per user in all containing user ns.
1218 * A group with FAN_UNLIMITED_MARKS does not contribute to mark count
1219 * in the limited groups account.
1220 */
1221 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS) &&
1222 !inc_ucount(ucounts->ns, ucounts->uid, UCOUNT_FANOTIFY_MARKS))
1223 return ERR_PTR(-ENOSPC);
1224
1225 mark = kmem_cache_alloc(fanotify_mark_cache, GFP_KERNEL);
1226 if (!mark) {
1227 ret = -ENOMEM;
1228 goto out_dec_ucounts;
1229 }
1230
1231 fsnotify_init_mark(mark, group);
1232 if (fan_flags & FAN_MARK_EVICTABLE)
1233 mark->flags |= FSNOTIFY_MARK_FLAG_NO_IREF;
1234
1235 ret = fsnotify_add_mark_locked(mark, connp, obj_type, 0, fsid);
1236 if (ret) {
1237 fsnotify_put_mark(mark);
1238 goto out_dec_ucounts;
1239 }
1240
1241 return mark;
1242
1243 out_dec_ucounts:
1244 if (!FAN_GROUP_FLAG(group, FAN_UNLIMITED_MARKS))
1245 dec_ucount(ucounts, UCOUNT_FANOTIFY_MARKS);
1246 return ERR_PTR(ret);
1247 }
1248
fanotify_group_init_error_pool(struct fsnotify_group * group)1249 static int fanotify_group_init_error_pool(struct fsnotify_group *group)
1250 {
1251 if (mempool_initialized(&group->fanotify_data.error_events_pool))
1252 return 0;
1253
1254 return mempool_init_kmalloc_pool(&group->fanotify_data.error_events_pool,
1255 FANOTIFY_DEFAULT_FEE_POOL_SIZE,
1256 sizeof(struct fanotify_error_event));
1257 }
1258
fanotify_may_update_existing_mark(struct fsnotify_mark * fsn_mark,unsigned int fan_flags)1259 static int fanotify_may_update_existing_mark(struct fsnotify_mark *fsn_mark,
1260 unsigned int fan_flags)
1261 {
1262 /*
1263 * Non evictable mark cannot be downgraded to evictable mark.
1264 */
1265 if (fan_flags & FAN_MARK_EVICTABLE &&
1266 !(fsn_mark->flags & FSNOTIFY_MARK_FLAG_NO_IREF))
1267 return -EEXIST;
1268
1269 /*
1270 * New ignore mask semantics cannot be downgraded to old semantics.
1271 */
1272 if (fan_flags & FAN_MARK_IGNORED_MASK &&
1273 fsn_mark->flags & FSNOTIFY_MARK_FLAG_HAS_IGNORE_FLAGS)
1274 return -EEXIST;
1275
1276 /*
1277 * An ignore mask that survives modify could never be downgraded to not
1278 * survive modify. With new FAN_MARK_IGNORE semantics we make that rule
1279 * explicit and return an error when trying to update the ignore mask
1280 * without the original FAN_MARK_IGNORED_SURV_MODIFY value.
1281 */
1282 if (fan_flags & FAN_MARK_IGNORE &&
1283 !(fan_flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
1284 fsn_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
1285 return -EEXIST;
1286
1287 return 0;
1288 }
1289
fanotify_add_mark(struct fsnotify_group * group,fsnotify_connp_t * connp,unsigned int obj_type,__u32 mask,unsigned int fan_flags,__kernel_fsid_t * fsid)1290 static int fanotify_add_mark(struct fsnotify_group *group,
1291 fsnotify_connp_t *connp, unsigned int obj_type,
1292 __u32 mask, unsigned int fan_flags,
1293 __kernel_fsid_t *fsid)
1294 {
1295 struct fsnotify_mark *fsn_mark;
1296 bool recalc;
1297 int ret = 0;
1298
1299 fsnotify_group_lock(group);
1300 fsn_mark = fsnotify_find_mark(connp, group);
1301 if (!fsn_mark) {
1302 fsn_mark = fanotify_add_new_mark(group, connp, obj_type,
1303 fan_flags, fsid);
1304 if (IS_ERR(fsn_mark)) {
1305 fsnotify_group_unlock(group);
1306 return PTR_ERR(fsn_mark);
1307 }
1308 }
1309
1310 /*
1311 * Check if requested mark flags conflict with an existing mark flags.
1312 */
1313 ret = fanotify_may_update_existing_mark(fsn_mark, fan_flags);
1314 if (ret)
1315 goto out;
1316
1317 /*
1318 * Error events are pre-allocated per group, only if strictly
1319 * needed (i.e. FAN_FS_ERROR was requested).
1320 */
1321 if (!(fan_flags & FANOTIFY_MARK_IGNORE_BITS) &&
1322 (mask & FAN_FS_ERROR)) {
1323 ret = fanotify_group_init_error_pool(group);
1324 if (ret)
1325 goto out;
1326 }
1327
1328 recalc = fanotify_mark_add_to_mask(fsn_mark, mask, fan_flags);
1329 if (recalc)
1330 fsnotify_recalc_mask(fsn_mark->connector);
1331
1332 out:
1333 fsnotify_group_unlock(group);
1334
1335 fsnotify_put_mark(fsn_mark);
1336 return ret;
1337 }
1338
fanotify_add_vfsmount_mark(struct fsnotify_group * group,struct vfsmount * mnt,__u32 mask,unsigned int flags,__kernel_fsid_t * fsid)1339 static int fanotify_add_vfsmount_mark(struct fsnotify_group *group,
1340 struct vfsmount *mnt, __u32 mask,
1341 unsigned int flags, __kernel_fsid_t *fsid)
1342 {
1343 return fanotify_add_mark(group, &real_mount(mnt)->mnt_fsnotify_marks,
1344 FSNOTIFY_OBJ_TYPE_VFSMOUNT, mask, flags, fsid);
1345 }
1346
fanotify_add_sb_mark(struct fsnotify_group * group,struct super_block * sb,__u32 mask,unsigned int flags,__kernel_fsid_t * fsid)1347 static int fanotify_add_sb_mark(struct fsnotify_group *group,
1348 struct super_block *sb, __u32 mask,
1349 unsigned int flags, __kernel_fsid_t *fsid)
1350 {
1351 return fanotify_add_mark(group, &sb->s_fsnotify_marks,
1352 FSNOTIFY_OBJ_TYPE_SB, mask, flags, fsid);
1353 }
1354
fanotify_add_inode_mark(struct fsnotify_group * group,struct inode * inode,__u32 mask,unsigned int flags,__kernel_fsid_t * fsid)1355 static int fanotify_add_inode_mark(struct fsnotify_group *group,
1356 struct inode *inode, __u32 mask,
1357 unsigned int flags, __kernel_fsid_t *fsid)
1358 {
1359 pr_debug("%s: group=%p inode=%p\n", __func__, group, inode);
1360
1361 /*
1362 * If some other task has this inode open for write we should not add
1363 * an ignore mask, unless that ignore mask is supposed to survive
1364 * modification changes anyway.
1365 */
1366 if ((flags & FANOTIFY_MARK_IGNORE_BITS) &&
1367 !(flags & FAN_MARK_IGNORED_SURV_MODIFY) &&
1368 inode_is_open_for_write(inode))
1369 return 0;
1370
1371 return fanotify_add_mark(group, &inode->i_fsnotify_marks,
1372 FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid);
1373 }
1374
fanotify_alloc_overflow_event(void)1375 static struct fsnotify_event *fanotify_alloc_overflow_event(void)
1376 {
1377 struct fanotify_event *oevent;
1378
1379 oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT);
1380 if (!oevent)
1381 return NULL;
1382
1383 fanotify_init_event(oevent, 0, FS_Q_OVERFLOW);
1384 oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW;
1385
1386 return &oevent->fse;
1387 }
1388
fanotify_alloc_merge_hash(void)1389 static struct hlist_head *fanotify_alloc_merge_hash(void)
1390 {
1391 struct hlist_head *hash;
1392
1393 hash = kmalloc(sizeof(struct hlist_head) << FANOTIFY_HTABLE_BITS,
1394 GFP_KERNEL_ACCOUNT);
1395 if (!hash)
1396 return NULL;
1397
1398 __hash_init(hash, FANOTIFY_HTABLE_SIZE);
1399
1400 return hash;
1401 }
1402
1403 /* fanotify syscalls */
SYSCALL_DEFINE2(fanotify_init,unsigned int,flags,unsigned int,event_f_flags)1404 SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
1405 {
1406 struct fsnotify_group *group;
1407 int f_flags, fd;
1408 unsigned int fid_mode = flags & FANOTIFY_FID_BITS;
1409 unsigned int class = flags & FANOTIFY_CLASS_BITS;
1410 unsigned int internal_flags = 0;
1411
1412 pr_debug("%s: flags=%x event_f_flags=%x\n",
1413 __func__, flags, event_f_flags);
1414
1415 if (!capable(CAP_SYS_ADMIN)) {
1416 /*
1417 * An unprivileged user can setup an fanotify group with
1418 * limited functionality - an unprivileged group is limited to
1419 * notification events with file handles and it cannot use
1420 * unlimited queue/marks.
1421 */
1422 if ((flags & FANOTIFY_ADMIN_INIT_FLAGS) || !fid_mode)
1423 return -EPERM;
1424
1425 /*
1426 * Setting the internal flag FANOTIFY_UNPRIV on the group
1427 * prevents setting mount/filesystem marks on this group and
1428 * prevents reporting pid and open fd in events.
1429 */
1430 internal_flags |= FANOTIFY_UNPRIV;
1431 }
1432
1433 #ifdef CONFIG_AUDITSYSCALL
1434 if (flags & ~(FANOTIFY_INIT_FLAGS | FAN_ENABLE_AUDIT))
1435 #else
1436 if (flags & ~FANOTIFY_INIT_FLAGS)
1437 #endif
1438 return -EINVAL;
1439
1440 /*
1441 * A pidfd can only be returned for a thread-group leader; thus
1442 * FAN_REPORT_PIDFD and FAN_REPORT_TID need to remain mutually
1443 * exclusive.
1444 */
1445 if ((flags & FAN_REPORT_PIDFD) && (flags & FAN_REPORT_TID))
1446 return -EINVAL;
1447
1448 if (event_f_flags & ~FANOTIFY_INIT_ALL_EVENT_F_BITS)
1449 return -EINVAL;
1450
1451 switch (event_f_flags & O_ACCMODE) {
1452 case O_RDONLY:
1453 case O_RDWR:
1454 case O_WRONLY:
1455 break;
1456 default:
1457 return -EINVAL;
1458 }
1459
1460 if (fid_mode && class != FAN_CLASS_NOTIF)
1461 return -EINVAL;
1462
1463 /*
1464 * Child name is reported with parent fid so requires dir fid.
1465 * We can report both child fid and dir fid with or without name.
1466 */
1467 if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID))
1468 return -EINVAL;
1469
1470 /*
1471 * FAN_REPORT_TARGET_FID requires FAN_REPORT_NAME and FAN_REPORT_FID
1472 * and is used as an indication to report both dir and child fid on all
1473 * dirent events.
1474 */
1475 if ((fid_mode & FAN_REPORT_TARGET_FID) &&
1476 (!(fid_mode & FAN_REPORT_NAME) || !(fid_mode & FAN_REPORT_FID)))
1477 return -EINVAL;
1478
1479 f_flags = O_RDWR | __FMODE_NONOTIFY;
1480 if (flags & FAN_CLOEXEC)
1481 f_flags |= O_CLOEXEC;
1482 if (flags & FAN_NONBLOCK)
1483 f_flags |= O_NONBLOCK;
1484
1485 /* fsnotify_alloc_group takes a ref. Dropped in fanotify_release */
1486 group = fsnotify_alloc_group(&fanotify_fsnotify_ops,
1487 FSNOTIFY_GROUP_USER | FSNOTIFY_GROUP_NOFS);
1488 if (IS_ERR(group)) {
1489 return PTR_ERR(group);
1490 }
1491
1492 /* Enforce groups limits per user in all containing user ns */
1493 group->fanotify_data.ucounts = inc_ucount(current_user_ns(),
1494 current_euid(),
1495 UCOUNT_FANOTIFY_GROUPS);
1496 if (!group->fanotify_data.ucounts) {
1497 fd = -EMFILE;
1498 goto out_destroy_group;
1499 }
1500
1501 group->fanotify_data.flags = flags | internal_flags;
1502 group->memcg = get_mem_cgroup_from_mm(current->mm);
1503
1504 group->fanotify_data.merge_hash = fanotify_alloc_merge_hash();
1505 if (!group->fanotify_data.merge_hash) {
1506 fd = -ENOMEM;
1507 goto out_destroy_group;
1508 }
1509
1510 group->overflow_event = fanotify_alloc_overflow_event();
1511 if (unlikely(!group->overflow_event)) {
1512 fd = -ENOMEM;
1513 goto out_destroy_group;
1514 }
1515
1516 if (force_o_largefile())
1517 event_f_flags |= O_LARGEFILE;
1518 group->fanotify_data.f_flags = event_f_flags;
1519 init_waitqueue_head(&group->fanotify_data.access_waitq);
1520 INIT_LIST_HEAD(&group->fanotify_data.access_list);
1521 switch (class) {
1522 case FAN_CLASS_NOTIF:
1523 group->priority = FS_PRIO_0;
1524 break;
1525 case FAN_CLASS_CONTENT:
1526 group->priority = FS_PRIO_1;
1527 break;
1528 case FAN_CLASS_PRE_CONTENT:
1529 group->priority = FS_PRIO_2;
1530 break;
1531 default:
1532 fd = -EINVAL;
1533 goto out_destroy_group;
1534 }
1535
1536 if (flags & FAN_UNLIMITED_QUEUE) {
1537 fd = -EPERM;
1538 if (!capable(CAP_SYS_ADMIN))
1539 goto out_destroy_group;
1540 group->max_events = UINT_MAX;
1541 } else {
1542 group->max_events = fanotify_max_queued_events;
1543 }
1544
1545 if (flags & FAN_UNLIMITED_MARKS) {
1546 fd = -EPERM;
1547 if (!capable(CAP_SYS_ADMIN))
1548 goto out_destroy_group;
1549 }
1550
1551 if (flags & FAN_ENABLE_AUDIT) {
1552 fd = -EPERM;
1553 if (!capable(CAP_AUDIT_WRITE))
1554 goto out_destroy_group;
1555 }
1556
1557 fd = anon_inode_getfd("[fanotify]", &fanotify_fops, group, f_flags);
1558 if (fd < 0)
1559 goto out_destroy_group;
1560
1561 return fd;
1562
1563 out_destroy_group:
1564 fsnotify_destroy_group(group);
1565 return fd;
1566 }
1567
fanotify_test_fsid(struct dentry * dentry,__kernel_fsid_t * fsid)1568 static int fanotify_test_fsid(struct dentry *dentry, __kernel_fsid_t *fsid)
1569 {
1570 __kernel_fsid_t root_fsid;
1571 int err;
1572
1573 /*
1574 * Make sure dentry is not of a filesystem with zero fsid (e.g. fuse).
1575 */
1576 err = vfs_get_fsid(dentry, fsid);
1577 if (err)
1578 return err;
1579
1580 if (!fsid->val[0] && !fsid->val[1])
1581 return -ENODEV;
1582
1583 /*
1584 * Make sure dentry is not of a filesystem subvolume (e.g. btrfs)
1585 * which uses a different fsid than sb root.
1586 */
1587 err = vfs_get_fsid(dentry->d_sb->s_root, &root_fsid);
1588 if (err)
1589 return err;
1590
1591 if (root_fsid.val[0] != fsid->val[0] ||
1592 root_fsid.val[1] != fsid->val[1])
1593 return -EXDEV;
1594
1595 return 0;
1596 }
1597
1598 /* Check if filesystem can encode a unique fid */
fanotify_test_fid(struct dentry * dentry,unsigned int flags)1599 static int fanotify_test_fid(struct dentry *dentry, unsigned int flags)
1600 {
1601 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
1602 const struct export_operations *nop = dentry->d_sb->s_export_op;
1603
1604 /*
1605 * We need to make sure that the filesystem supports encoding of
1606 * file handles so user can use name_to_handle_at() to compare fids
1607 * reported with events to the file handle of watched objects.
1608 */
1609 if (!nop)
1610 return -EOPNOTSUPP;
1611
1612 /*
1613 * For sb/mount mark, we also need to make sure that the filesystem
1614 * supports decoding file handles, so user has a way to map back the
1615 * reported fids to filesystem objects.
1616 */
1617 if (mark_type != FAN_MARK_INODE && !nop->fh_to_dentry)
1618 return -EOPNOTSUPP;
1619
1620 return 0;
1621 }
1622
fanotify_events_supported(struct fsnotify_group * group,const struct path * path,__u64 mask,unsigned int flags)1623 static int fanotify_events_supported(struct fsnotify_group *group,
1624 const struct path *path, __u64 mask,
1625 unsigned int flags)
1626 {
1627 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
1628 /* Strict validation of events in non-dir inode mask with v5.17+ APIs */
1629 bool strict_dir_events = FAN_GROUP_FLAG(group, FAN_REPORT_TARGET_FID) ||
1630 (mask & FAN_RENAME) ||
1631 (flags & FAN_MARK_IGNORE);
1632
1633 /*
1634 * Some filesystems such as 'proc' acquire unusual locks when opening
1635 * files. For them fanotify permission events have high chances of
1636 * deadlocking the system - open done when reporting fanotify event
1637 * blocks on this "unusual" lock while another process holding the lock
1638 * waits for fanotify permission event to be answered. Just disallow
1639 * permission events for such filesystems.
1640 */
1641 if (mask & FANOTIFY_PERM_EVENTS &&
1642 path->mnt->mnt_sb->s_type->fs_flags & FS_DISALLOW_NOTIFY_PERM)
1643 return -EINVAL;
1644
1645 /*
1646 * mount and sb marks are not allowed on kernel internal pseudo fs,
1647 * like pipe_mnt, because that would subscribe to events on all the
1648 * anonynous pipes in the system.
1649 *
1650 * SB_NOUSER covers all of the internal pseudo fs whose objects are not
1651 * exposed to user's mount namespace, but there are other SB_KERNMOUNT
1652 * fs, like nsfs, debugfs, for which the value of allowing sb and mount
1653 * mark is questionable. For now we leave them alone.
1654 */
1655 if (mark_type != FAN_MARK_INODE &&
1656 path->mnt->mnt_sb->s_flags & SB_NOUSER)
1657 return -EINVAL;
1658
1659 /*
1660 * We shouldn't have allowed setting dirent events and the directory
1661 * flags FAN_ONDIR and FAN_EVENT_ON_CHILD in mask of non-dir inode,
1662 * but because we always allowed it, error only when using new APIs.
1663 */
1664 if (strict_dir_events && mark_type == FAN_MARK_INODE &&
1665 !d_is_dir(path->dentry) && (mask & FANOTIFY_DIRONLY_EVENT_BITS))
1666 return -ENOTDIR;
1667
1668 return 0;
1669 }
1670
do_fanotify_mark(int fanotify_fd,unsigned int flags,__u64 mask,int dfd,const char __user * pathname)1671 static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
1672 int dfd, const char __user *pathname)
1673 {
1674 struct inode *inode = NULL;
1675 struct vfsmount *mnt = NULL;
1676 struct fsnotify_group *group;
1677 struct fd f;
1678 struct path path;
1679 __kernel_fsid_t __fsid, *fsid = NULL;
1680 u32 valid_mask = FANOTIFY_EVENTS | FANOTIFY_EVENT_FLAGS;
1681 unsigned int mark_type = flags & FANOTIFY_MARK_TYPE_BITS;
1682 unsigned int mark_cmd = flags & FANOTIFY_MARK_CMD_BITS;
1683 unsigned int ignore = flags & FANOTIFY_MARK_IGNORE_BITS;
1684 unsigned int obj_type, fid_mode;
1685 u32 umask = 0;
1686 int ret;
1687
1688 pr_debug("%s: fanotify_fd=%d flags=%x dfd=%d pathname=%p mask=%llx\n",
1689 __func__, fanotify_fd, flags, dfd, pathname, mask);
1690
1691 /* we only use the lower 32 bits as of right now. */
1692 if (upper_32_bits(mask))
1693 return -EINVAL;
1694
1695 if (flags & ~FANOTIFY_MARK_FLAGS)
1696 return -EINVAL;
1697
1698 switch (mark_type) {
1699 case FAN_MARK_INODE:
1700 obj_type = FSNOTIFY_OBJ_TYPE_INODE;
1701 break;
1702 case FAN_MARK_MOUNT:
1703 obj_type = FSNOTIFY_OBJ_TYPE_VFSMOUNT;
1704 break;
1705 case FAN_MARK_FILESYSTEM:
1706 obj_type = FSNOTIFY_OBJ_TYPE_SB;
1707 break;
1708 default:
1709 return -EINVAL;
1710 }
1711
1712 switch (mark_cmd) {
1713 case FAN_MARK_ADD:
1714 case FAN_MARK_REMOVE:
1715 if (!mask)
1716 return -EINVAL;
1717 break;
1718 case FAN_MARK_FLUSH:
1719 if (flags & ~(FANOTIFY_MARK_TYPE_BITS | FAN_MARK_FLUSH))
1720 return -EINVAL;
1721 break;
1722 default:
1723 return -EINVAL;
1724 }
1725
1726 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS))
1727 valid_mask |= FANOTIFY_PERM_EVENTS;
1728
1729 if (mask & ~valid_mask)
1730 return -EINVAL;
1731
1732
1733 /* We don't allow FAN_MARK_IGNORE & FAN_MARK_IGNORED_MASK together */
1734 if (ignore == (FAN_MARK_IGNORE | FAN_MARK_IGNORED_MASK))
1735 return -EINVAL;
1736
1737 /*
1738 * Event flags (FAN_ONDIR, FAN_EVENT_ON_CHILD) have no effect with
1739 * FAN_MARK_IGNORED_MASK.
1740 */
1741 if (ignore == FAN_MARK_IGNORED_MASK) {
1742 mask &= ~FANOTIFY_EVENT_FLAGS;
1743 umask = FANOTIFY_EVENT_FLAGS;
1744 }
1745
1746 f = fdget(fanotify_fd);
1747 if (unlikely(!f.file))
1748 return -EBADF;
1749
1750 /* verify that this is indeed an fanotify instance */
1751 ret = -EINVAL;
1752 if (unlikely(f.file->f_op != &fanotify_fops))
1753 goto fput_and_out;
1754 group = f.file->private_data;
1755
1756 /*
1757 * An unprivileged user is not allowed to setup mount nor filesystem
1758 * marks. This also includes setting up such marks by a group that
1759 * was initialized by an unprivileged user.
1760 */
1761 ret = -EPERM;
1762 if ((!capable(CAP_SYS_ADMIN) ||
1763 FAN_GROUP_FLAG(group, FANOTIFY_UNPRIV)) &&
1764 mark_type != FAN_MARK_INODE)
1765 goto fput_and_out;
1766
1767 /*
1768 * group->priority == FS_PRIO_0 == FAN_CLASS_NOTIF. These are not
1769 * allowed to set permissions events.
1770 */
1771 ret = -EINVAL;
1772 if (mask & FANOTIFY_PERM_EVENTS &&
1773 group->priority == FS_PRIO_0)
1774 goto fput_and_out;
1775
1776 if (mask & FAN_FS_ERROR &&
1777 mark_type != FAN_MARK_FILESYSTEM)
1778 goto fput_and_out;
1779
1780 /*
1781 * Evictable is only relevant for inode marks, because only inode object
1782 * can be evicted on memory pressure.
1783 */
1784 if (flags & FAN_MARK_EVICTABLE &&
1785 mark_type != FAN_MARK_INODE)
1786 goto fput_and_out;
1787
1788 /*
1789 * Events that do not carry enough information to report
1790 * event->fd require a group that supports reporting fid. Those
1791 * events are not supported on a mount mark, because they do not
1792 * carry enough information (i.e. path) to be filtered by mount
1793 * point.
1794 */
1795 fid_mode = FAN_GROUP_FLAG(group, FANOTIFY_FID_BITS);
1796 if (mask & ~(FANOTIFY_FD_EVENTS|FANOTIFY_EVENT_FLAGS) &&
1797 (!fid_mode || mark_type == FAN_MARK_MOUNT))
1798 goto fput_and_out;
1799
1800 /*
1801 * FAN_RENAME uses special info type records to report the old and
1802 * new parent+name. Reporting only old and new parent id is less
1803 * useful and was not implemented.
1804 */
1805 if (mask & FAN_RENAME && !(fid_mode & FAN_REPORT_NAME))
1806 goto fput_and_out;
1807
1808 if (mark_cmd == FAN_MARK_FLUSH) {
1809 ret = 0;
1810 if (mark_type == FAN_MARK_MOUNT)
1811 fsnotify_clear_vfsmount_marks_by_group(group);
1812 else if (mark_type == FAN_MARK_FILESYSTEM)
1813 fsnotify_clear_sb_marks_by_group(group);
1814 else
1815 fsnotify_clear_inode_marks_by_group(group);
1816 goto fput_and_out;
1817 }
1818
1819 ret = fanotify_find_path(dfd, pathname, &path, flags,
1820 (mask & ALL_FSNOTIFY_EVENTS), obj_type);
1821 if (ret)
1822 goto fput_and_out;
1823
1824 if (mark_cmd == FAN_MARK_ADD) {
1825 ret = fanotify_events_supported(group, &path, mask, flags);
1826 if (ret)
1827 goto path_put_and_out;
1828 }
1829
1830 if (fid_mode) {
1831 ret = fanotify_test_fsid(path.dentry, &__fsid);
1832 if (ret)
1833 goto path_put_and_out;
1834
1835 ret = fanotify_test_fid(path.dentry, flags);
1836 if (ret)
1837 goto path_put_and_out;
1838
1839 fsid = &__fsid;
1840 }
1841
1842 /* inode held in place by reference to path; group by fget on fd */
1843 if (mark_type == FAN_MARK_INODE)
1844 inode = path.dentry->d_inode;
1845 else
1846 mnt = path.mnt;
1847
1848 ret = mnt ? -EINVAL : -EISDIR;
1849 /* FAN_MARK_IGNORE requires SURV_MODIFY for sb/mount/dir marks */
1850 if (mark_cmd == FAN_MARK_ADD && ignore == FAN_MARK_IGNORE &&
1851 (mnt || S_ISDIR(inode->i_mode)) &&
1852 !(flags & FAN_MARK_IGNORED_SURV_MODIFY))
1853 goto path_put_and_out;
1854
1855 /* Mask out FAN_EVENT_ON_CHILD flag for sb/mount/non-dir marks */
1856 if (mnt || !S_ISDIR(inode->i_mode)) {
1857 mask &= ~FAN_EVENT_ON_CHILD;
1858 umask = FAN_EVENT_ON_CHILD;
1859 /*
1860 * If group needs to report parent fid, register for getting
1861 * events with parent/name info for non-directory.
1862 */
1863 if ((fid_mode & FAN_REPORT_DIR_FID) &&
1864 (flags & FAN_MARK_ADD) && !ignore)
1865 mask |= FAN_EVENT_ON_CHILD;
1866 }
1867
1868 /* create/update an inode mark */
1869 switch (mark_cmd) {
1870 case FAN_MARK_ADD:
1871 if (mark_type == FAN_MARK_MOUNT)
1872 ret = fanotify_add_vfsmount_mark(group, mnt, mask,
1873 flags, fsid);
1874 else if (mark_type == FAN_MARK_FILESYSTEM)
1875 ret = fanotify_add_sb_mark(group, mnt->mnt_sb, mask,
1876 flags, fsid);
1877 else
1878 ret = fanotify_add_inode_mark(group, inode, mask,
1879 flags, fsid);
1880 break;
1881 case FAN_MARK_REMOVE:
1882 if (mark_type == FAN_MARK_MOUNT)
1883 ret = fanotify_remove_vfsmount_mark(group, mnt, mask,
1884 flags, umask);
1885 else if (mark_type == FAN_MARK_FILESYSTEM)
1886 ret = fanotify_remove_sb_mark(group, mnt->mnt_sb, mask,
1887 flags, umask);
1888 else
1889 ret = fanotify_remove_inode_mark(group, inode, mask,
1890 flags, umask);
1891 break;
1892 default:
1893 ret = -EINVAL;
1894 }
1895
1896 path_put_and_out:
1897 path_put(&path);
1898 fput_and_out:
1899 fdput(f);
1900 return ret;
1901 }
1902
1903 #ifndef CONFIG_ARCH_SPLIT_ARG64
SYSCALL_DEFINE5(fanotify_mark,int,fanotify_fd,unsigned int,flags,__u64,mask,int,dfd,const char __user *,pathname)1904 SYSCALL_DEFINE5(fanotify_mark, int, fanotify_fd, unsigned int, flags,
1905 __u64, mask, int, dfd,
1906 const char __user *, pathname)
1907 {
1908 return do_fanotify_mark(fanotify_fd, flags, mask, dfd, pathname);
1909 }
1910 #endif
1911
1912 #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)1913 SYSCALL32_DEFINE6(fanotify_mark,
1914 int, fanotify_fd, unsigned int, flags,
1915 SC_ARG64(mask), int, dfd,
1916 const char __user *, pathname)
1917 {
1918 return do_fanotify_mark(fanotify_fd, flags, SC_VAL64(__u64, mask),
1919 dfd, pathname);
1920 }
1921 #endif
1922
1923 /*
1924 * fanotify_user_setup - Our initialization function. Note that we cannot return
1925 * error because we have compiled-in VFS hooks. So an (unlikely) failure here
1926 * must result in panic().
1927 */
fanotify_user_setup(void)1928 static int __init fanotify_user_setup(void)
1929 {
1930 struct sysinfo si;
1931 int max_marks;
1932
1933 si_meminfo(&si);
1934 /*
1935 * Allow up to 1% of addressable memory to be accounted for per user
1936 * marks limited to the range [8192, 1048576]. mount and sb marks are
1937 * a lot cheaper than inode marks, but there is no reason for a user
1938 * to have many of those, so calculate by the cost of inode marks.
1939 */
1940 max_marks = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) /
1941 INODE_MARK_COST;
1942 max_marks = clamp(max_marks, FANOTIFY_OLD_DEFAULT_MAX_MARKS,
1943 FANOTIFY_DEFAULT_MAX_USER_MARKS);
1944
1945 BUILD_BUG_ON(FANOTIFY_INIT_FLAGS & FANOTIFY_INTERNAL_GROUP_FLAGS);
1946 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 13);
1947 BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 11);
1948
1949 fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
1950 SLAB_PANIC|SLAB_ACCOUNT);
1951 fanotify_fid_event_cachep = KMEM_CACHE(fanotify_fid_event,
1952 SLAB_PANIC);
1953 fanotify_path_event_cachep = KMEM_CACHE(fanotify_path_event,
1954 SLAB_PANIC);
1955 if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
1956 fanotify_perm_event_cachep =
1957 KMEM_CACHE(fanotify_perm_event, SLAB_PANIC);
1958 }
1959
1960 fanotify_max_queued_events = FANOTIFY_DEFAULT_MAX_EVENTS;
1961 init_user_ns.ucount_max[UCOUNT_FANOTIFY_GROUPS] =
1962 FANOTIFY_DEFAULT_MAX_GROUPS;
1963 init_user_ns.ucount_max[UCOUNT_FANOTIFY_MARKS] = max_marks;
1964 fanotify_sysctls_init();
1965
1966 return 0;
1967 }
1968 device_initcall(fanotify_user_setup);
1969