Subject: Re: [RFC bpf-next 2/5] bpf, sockmap: Allow inserting listening TCP sockets into SOCKMAP

From: Jakub Sitnicki <[email-masked]>
Date: Fri, 25 Oct 2019 11:41:36 +0200

On Thu, Oct 24, 2019 at 07:06 PM CEST, John Fastabend wrote:
> Jakub Sitnicki wrote:
>> In order for SOCKMAP type to become a generic collection for storing socket
>> references we need to loosen the checks in update callback.
>>
>> Currently SOCKMAP requires the TCP socket to be in established state, which
>> prevents us from using it to keep references to listening sockets.
>>
>> Change the update pre-checks so that it is sufficient for socket to be in a
>> hash table, i.e. have a local address/port, to be inserted.
>>
>> Return -EINVAL if the condition is not met to be consistent with
>> REUSEPORT_SOCKARRY map type.
>>
>> Signed-off-by: Jakub Sitnicki <[email-masked]>
>> ---
>
> We need to also have some tests then to verify redirecting to this listen socket
> does the correct thing. Once its in the map we can redirect (ingress or egress)
> to it and need to be sure the semantics are sane.

You're right. The redirect BPF helpers that operate on SOCMAP might be
relying on an assumption that sockets are in established state. I need
look into that.

Thanks,
Jakub