Re: [PATCH bpf-next 10/10] bpf: Add sample for raw syncookie helpers

[Maxim Mikityanskiy <maximmi@nvidia.com>]

On 2021-10-20 21:01, Joe Stringer wrote:
> Hi,  just one comment related to the discussion on patch 7.
> 
> On Tue, Oct 19, 2021 at 7:49 AM Maxim Mikityanskiy <maximmi@nvidia.com> wrote:
> 
> <snip>
> 
>> +
>> +       value = 0; // Flags.
>> +       ct = bpf_ct_lookup_tcp(ctx, &tup, tup_size, BPF_F_CURRENT_NETNS, &value);
>> +       if (ct) {
>> +               unsigned long status = ct->status;
>> +
>> +               bpf_ct_release(ct);
>> +               if (status & IPS_CONFIRMED_BIT)
>> +                       return XDP_PASS;
>> +       } else if (value != -ENOENT) {
>> +               return XDP_ABORTED;
>> +       }
> 
> Is this the only reason that you wish to expose conntrack lookup
> functions to the API?
> 
> You should be able to find out whether the TCP session is established
> by doing a TCP socket lookup and checking sk->state.

It's not possible to lookup a socket, because there is no socket. The 
traffic is forwarded through the firewall machine that runs synproxy and 
this XDP program.