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