netdev - Re: [PATCH bpf-next v3 05/12] bpf, sockmap: Allow inserting listening TCP sockets into sockmap

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Message-ID: <877e1i315r.fsf@cloudflare.com>
Date:   Thu, 23 Jan 2020 11:41:36 +0100
From:   Jakub Sitnicki <jakub@...udflare.com>
To:     Martin Lau <kafai@...com>
Cc:     "bpf\@vger.kernel.org" <bpf@...r.kernel.org>,
        "netdev\@vger.kernel.org" <netdev@...r.kernel.org>,
        "kernel-team\@cloudflare.com" <kernel-team@...udflare.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "John Fastabend" <john.fastabend@...il.com>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: Re: [PATCH bpf-next v3 05/12] bpf, sockmap: Allow inserting listening TCP sockets into sockmap

On Wed, Jan 22, 2020 at 09:52 PM CET, Martin Lau wrote:
> On Wed, Jan 22, 2020 at 02:05:42PM +0100, Jakub Sitnicki wrote:
>> In order for sockmap type to become a generic collection for storing TCP
>> sockets we need to loosen the checks during map update, while tightening
>> the checks in redirect helpers.
>>
>> Currently sockmap requires the TCP socket to be in established state (or
>> transitioning out of SYN_RECV into established state when done from BPF),
> If I read the SYN_RECV changes correctly,
> does it mean BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB currently not work?

It works because before this series we didn't have sk_state checks in
bpf_sock_{hash,map}_update helpers.

It was a surprise to find out that BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB
happens when socket is still in SYN_RECV state, though.

Fortunately selftests/bpf/test_sockmap tests cover it.

-jkbs