PF_KEY
sk = sk_alloc(net, PF_KEY, GFP_KERNEL, &key_proto, kern);
sk->sk_family = PF_KEY;
.family = PF_KEY,
.family = PF_KEY,
sock_unregister(PF_KEY);
MODULE_ALIAS_NETPROTO(PF_KEY);
[PF_KEY] = "PF_KEY",
case PF_KEY: