fanotify: create overflow event type
The special overflow event is allocated as struct fanotify_path_event,
but with a null path.
Use a special event type to identify the overflow event, so the helper
fanotify_has_event_path() will always indicate a non null path.
Allocating the overflow event doesn't need any of the fancy stuff in
fanotify_alloc_event(), so create a simplified helper for allocating the
overflow event.
There is also no need to store and report the pid with an overflow event.
Link: https://lore.kernel.org/r/20200708111156.24659-7-amir73il@gmail.com
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index d7f63ae..c9a824e 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -836,13 +836,26 @@ static int fanotify_add_inode_mark(struct fsnotify_group *group,
FSNOTIFY_OBJ_TYPE_INODE, mask, flags, fsid);
}
+static struct fsnotify_event *fanotify_alloc_overflow_event(void)
+{
+ struct fanotify_event *oevent;
+
+ oevent = kmalloc(sizeof(*oevent), GFP_KERNEL_ACCOUNT);
+ if (!oevent)
+ return NULL;
+
+ fanotify_init_event(oevent, 0, FS_Q_OVERFLOW);
+ oevent->type = FANOTIFY_EVENT_TYPE_OVERFLOW;
+
+ return &oevent->fse;
+}
+
/* fanotify syscalls */
SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
{
struct fsnotify_group *group;
int f_flags, fd;
struct user_struct *user;
- struct fanotify_event *oevent;
pr_debug("%s: flags=%x event_f_flags=%x\n",
__func__, flags, event_f_flags);
@@ -897,13 +910,11 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
atomic_inc(&user->fanotify_listeners);
group->memcg = get_mem_cgroup_from_mm(current->mm);
- oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL,
- FSNOTIFY_EVENT_NONE, NULL, NULL);
- if (unlikely(!oevent)) {
+ group->overflow_event = fanotify_alloc_overflow_event();
+ if (unlikely(!group->overflow_event)) {
fd = -ENOMEM;
goto out_destroy_group;
}
- group->overflow_event = &oevent->fse;
if (force_o_largefile())
event_f_flags |= O_LARGEFILE;