BPF_NETFILTER
if (expected_attach_type == BPF_NETFILTER)
if (attach_type != BPF_NETFILTER)
case BPF_NETFILTER:
[BPF_NETFILTER] = "netfilter",
link_fd = bpf_link_create(prog_fd, 0, BPF_NETFILTER, &lopts);
SEC_DEF("netfilter", NETFILTER, BPF_NETFILTER, SEC_NONE),
opts.expected_attach_type = BPF_NETFILTER;