Alexei Starovoitov [off-list ref] wrote:

quoted

1 and 2 have the upside that its easy to handle a 'file not found'
error.

I'm strongly against calling into bpf from the inner guts of nft.
Nack to all options discussed in this thread.
None of them make any sense.

-v please.  I can just rework userspace to allow going via xt_bpf
but its brain damaged.

This helps gradually moving towards move epbf for those that
still heavily rely on the classic forwarding path.

If you are open to BPF_PROG_TYPE_NETFILTER I can go that route
as well, raw bpf program attachment via NF_HOOK and the bpf dispatcher,
but it will take significantly longer to get there.

It involves reviving
https://lore.kernel.org/netfilter-devel/20211014121046.29329-1-fw@strlen.de/ (local)

as a first stage/merge goal.