netdev - Re: [PATCH v3 bpf-next 9/9] tcp: bpf: Optionally store mac header in TCP_SAVE

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Message-ID: <CANn89iLA5vongVK=kgS2creh+BiA821YfiiixkC1wa3QGCmvgg@mail.gmail.com>
Date:   Fri, 31 Jul 2020 08:51:36 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Martin KaFai Lau <kafai@...com>
Cc:     bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        kernel-team <kernel-team@...com>,
        Lawrence Brakmo <brakmo@...com>,
        Neal Cardwell <ncardwell@...gle.com>,
        netdev <netdev@...r.kernel.org>,
        Yuchung Cheng <ycheng@...gle.com>
Subject: Re: [PATCH v3 bpf-next 9/9] tcp: bpf: Optionally store mac header in TCP_SAVE_SYN

On Thu, Jul 30, 2020 at 1:58 PM Martin KaFai Lau <kafai@...com> wrote:
>
> This patch is adapted from Eric's patch in an earlier discussion [1].
>
> The TCP_SAVE_SYN currently only stores the network header and
> tcp header.  This patch allows it to optionally store
> the mac header also if the setsockopt's optval is 2.
>
> It requires one more bit for the "save_syn" bit field in tcp_sock.
> This patch achieves this by moving the syn_smc bit next to the is_mptcp.
> The syn_smc is currently used with the TCP experimental option.  Since
> syn_smc is only used when CONFIG_SMC is enabled, this patch also puts
> the "IS_ENABLED(CONFIG_SMC)" around it like the is_mptcp did
> with "IS_ENABLED(CONFIG_MPTCP)".
>
> The mac_hdrlen is also stored in the "struct saved_syn"
> to allow a quick offset from the bpf prog if it chooses to start
> getting from the network header or the tcp header.
>
> [1]: https://lore.kernel.org/netdev/CANn89iLJNWh6bkH7DNhy_kmcAexuUCccqERqe7z2QsvPhGrYPQ@mail.gmail.com/
>
> Suggested-by: Eric Dumazet <edumazet@...gle.com>
> Signed-off-by: Martin KaFai Lau <kafai@...com>
> ---

Reviewed-by: Eric Dumazet <edumazet@...gle.com>