netdev - Re: [RFC PATCH v4 bpf-next 06/12] bpf: tcp: Add bpf_skops_parse

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Message-ID: <CANn89iLipQWyGB9WVyK1ub48q31oEe9Pn=9RB_D21vTCs6r_vA@mail.gmail.com>
Date:   Mon, 3 Aug 2020 17:50:56 -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: [RFC PATCH v4 bpf-next 06/12] bpf: tcp: Add bpf_skops_parse_hdr()

On Mon, Aug 3, 2020 at 4:10 PM Martin KaFai Lau <kafai@...com> wrote:
>
> The patch adds a function bpf_skops_parse_hdr().
> It will call the bpf prog to parse the TCP header received at
> a tcp_sock that has at least reached the ESTABLISHED state.
>
> For the packets received during the 3WHS (SYN, SYNACK and ACK),
> the received skb will be available to the bpf prog during the callback
> in bpf_skops_established() introduced in the previous patch and
> in the bpf_skops_write_hdr_opt() that will be added in the
> next patch.
>
> Calling bpf prog to parse header is controlled by two new flags in
> tp->bpf_sock_ops_cb_flags:
> BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG and
> BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG.
>
> When BPF_SOCK_OPS_PARSE_UNKNOWN_HDR_OPT_CB_FLAG is set,
> the bpf prog will only be called when there is unknown
> option in the TCP header.
>
> When BPF_SOCK_OPS_PARSE_ALL_HDR_OPT_CB_FLAG is set,
> the bpf prog will be called on all received TCP header.
>
> This function is half implemented to highlight the changes in
> TCP stack.  The actual codes preparing the bpf running context and
> invoking the bpf prog will be added in the later patch with other
> necessary bpf pieces.
>
> Signed-off-by: Martin KaFai Lau <kafai@...com>

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