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fanotify: report parent fid + child fid 

Add support for FAN_REPORT_FID | FAN_REPORT_DIR_FID.
Internally, it is implemented as a private case of reporting both
parent and child fids and name, the parent and child fids are recorded
in a variable length fanotify_name_event, but there is no name.

It should be noted that directory modification events are recorded
in fixed size fanotify_fid_event when not reporting name, just like
with group flags FAN_REPORT_FID.

Link: https://lore.kernel.org/r/20200716084230.30611-23-amir73il@gmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Amir Goldstein 2020-07-16 11:42:30 +03:00 committed by Jan Kara
parent 7e8283af6e
commit 691d976352
2 changed files with 15 additions and 16 deletions
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16
fs/notify/fanotify/fanotify.c
View File

@ -535,7 +535,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
/*
* With both flags FAN_REPORT_DIR_FID and FAN_REPORT_FID, we
* report the child fid for events reported on a non-dir child
* in addition to reporting the parent fid and child name.
* in addition to reporting the parent fid and maybe child name.
*/
if ((fid_mode & FAN_REPORT_FID) &&
id != dirid && !(mask & FAN_ONDIR))
@ -552,11 +552,17 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
*
* For event on non-directory that is reported to parent, we
* record the fid of the parent and the name of the child.
*
* Even if not reporting name, we need a variable length
* fanotify_name_event if reporting both parent and child fids.
*/
if ((fid_mode & FAN_REPORT_NAME) &&
((mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
!(mask & FAN_ONDIR)))
if (!(fid_mode & FAN_REPORT_NAME)) {
name_event = !!child;
file_name = NULL;
} else if ((mask & ALL_FSNOTIFY_DIRENT_EVENTS) ||
!(mask & FAN_ONDIR)) {
name_event = true;
}
}
/*
@ -575,7 +581,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
if (fanotify_is_perm_event(mask)) {
event = fanotify_alloc_perm_event(path, gfp);
} else if (name_event && file_name) {
} else if (name_event && (file_name || child)) {
event = fanotify_alloc_name_event(id, fsid, file_name, child,
gfp);
} else if (fid_mode) {

15
fs/notify/fanotify/fanotify_user.c
View File

@ -371,7 +371,8 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
/* Event info records order is: dir fid + name, child fid */
if (fanotify_event_dir_fh_len(event)) {
info_type = FAN_EVENT_INFO_TYPE_DFID_NAME;
info_type = info->name_len ? FAN_EVENT_INFO_TYPE_DFID_NAME :
FAN_EVENT_INFO_TYPE_DFID;
ret = copy_info_to_user(fanotify_event_fsid(event),
fanotify_info_dir_fh(info),
info_type, fanotify_info_name(info),
@ -957,18 +958,10 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
/*
* Child name is reported with parent fid so requires dir fid.
* If reporting child name, we can report both child fid and dir fid.
* We can report both child fid and dir fid with or without name.
*/
switch (fid_mode) {
case 0:
case FAN_REPORT_FID:
case FAN_REPORT_DIR_FID:
case FAN_REPORT_DFID_NAME:
case FAN_REPORT_DFID_NAME | FAN_REPORT_FID:
break;
default:
if ((fid_mode & FAN_REPORT_NAME) && !(fid_mode & FAN_REPORT_DIR_FID))
return -EINVAL;
}
user = get_current_user();
if (atomic_read(&user->fanotify_listeners) > FANOTIFY_DEFAULT_MAX_LISTENERS) {