net: ieee802154: forbid monitor for add llsec dev

This patch forbids to add llsec dev for monitor interfaces which we
don't support yet. Otherwise we will access llsec mib which isn't
initialized for monitors.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20210405003054.256017-8-aahringo@redhat.comSigned-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

net/ieee802154/nl802154.c

@@ -1763,6 +1763,9 @@ static int nl802154_add_llsec_dev(struct sk_buff *skb, struct genl_info *info)
 	struct wpan_dev *wpan_dev = dev->ieee802154_ptr;
 	struct ieee802154_llsec_device dev_desc;
 
+	if (wpan_dev->iftype == NL802154_IFTYPE_MONITOR)
+		return -EOPNOTSUPP;
+
 	if (ieee802154_llsec_parse_device(info->attrs[NL802154_ATTR_SEC_DEVICE],
 					  &dev_desc) < 0)
 		return -EINVAL;