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fanotify: Track permission event state

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Track whether permission event got already reported to userspace and
whether userspace already answered to the permission event. Protect
stores to this field together with updates to ->response field by
group->notification_lock. This will allow aborting wait for reply to
permission event from userspace.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara
2019-01-08 14:02:44 +01:00
parent ca6f86998d
commit 40873284d7
3 changed files with 40 additions and 11 deletions
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35
fs/notify/fanotify/fanotify_user.c
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@@ -64,7 +64,8 @@ static int fanotify_event_info_len(struct fanotify_event *event)
/*
* Get an fsnotify notification event if one exists and is small
* enough to fit in "count". Return an error pointer if the count
* is not large enough.
* is not large enough. When permission event is dequeued, its state is
* updated accordingly.
*/
static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
size_t count)
@@ -88,6 +89,8 @@ static struct fsnotify_event *get_one_event(struct fsnotify_group *group,
goto out;
}
fsn_event = fsnotify_remove_first_event(group);
if (fanotify_is_perm_event(FANOTIFY_E(fsn_event)->mask))
FANOTIFY_PE(fsn_event)->state = FAN_EVENT_REPORTED;
out:
spin_unlock(&group->notification_lock);
return fsn_event;
@@ -135,6 +138,21 @@ static int create_fd(struct fsnotify_group *group,
return client_fd;
}
/*
* Finish processing of permission event by setting it to ANSWERED state and
* drop group->notification_lock.
*/
static void finish_permission_event(struct fsnotify_group *group,
struct fanotify_perm_event *event,
unsigned int response)
__releases(&group->notification_lock)
{
assert_spin_locked(&group->notification_lock);
event->response = response;
event->state = FAN_EVENT_ANSWERED;
spin_unlock(&group->notification_lock);
}
static int process_access_response(struct fsnotify_group *group,
struct fanotify_response *response_struct)
{
@@ -170,8 +188,7 @@ static int process_access_response(struct fsnotify_group *group,
continue;
list_del_init(&event->fae.fse.list);
event->response = response;
spin_unlock(&group->notification_lock);
finish_permission_event(group, event, response);
wake_up(&group->fanotify_data.access_waitq);
return 0;
}
@@ -354,7 +371,9 @@ static ssize_t fanotify_read(struct file *file, char __user *buf,
fsnotify_destroy_event(group, kevent);
} else {
if (ret <= 0) {
FANOTIFY_PE(kevent)->response = FAN_DENY;
spin_lock(&group->notification_lock);
finish_permission_event(group,
FANOTIFY_PE(kevent), FAN_DENY);
wake_up(&group->fanotify_data.access_waitq);
} else {
spin_lock(&group->notification_lock);
@@ -423,7 +442,8 @@ static int fanotify_release(struct inode *ignored, struct file *file)
event = list_first_entry(&group->fanotify_data.access_list,
struct fanotify_perm_event, fae.fse.list);
list_del_init(&event->fae.fse.list);
event->response = FAN_ALLOW;
finish_permission_event(group, event, FAN_ALLOW);
spin_lock(&group->notification_lock);
}
/*
@@ -436,10 +456,11 @@ static int fanotify_release(struct inode *ignored, struct file *file)
if (!(FANOTIFY_E(fsn_event)->mask & FANOTIFY_PERM_EVENTS)) {
spin_unlock(&group->notification_lock);
fsnotify_destroy_event(group, fsn_event);
spin_lock(&group->notification_lock);
} else {
FANOTIFY_PE(fsn_event)->response = FAN_ALLOW;
finish_permission_event(group, FANOTIFY_PE(fsn_event),
FAN_ALLOW);
}
spin_lock(&group->notification_lock);
}
spin_unlock(&group->notification_lock);