LWTUNNEL_IP_OPTS
[LWTUNNEL_IP_UNSPEC] = { .strict_start_type = LWTUNNEL_IP_OPTS },
[LWTUNNEL_IP_OPTS] = { .type = NLA_NESTED },
opt_len = ip_tun_get_optlen(tb[LWTUNNEL_IP_OPTS], extack);
err = ip_tun_set_opts(tb[LWTUNNEL_IP_OPTS], tun_info, extack);
ip_tun_fill_encap_opts(skb, LWTUNNEL_IP_OPTS, tun_info))