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References: <cover.1660592020.git.dxu@dxuuu.xyz>
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 <871qth87r1.fsf@toke.dk>
Date:   Mon, 15 Aug 2022 16:41:11 -0600
From:   "Daniel Xu" <dxu@dxuuu.xyz>
To:     =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@kernel.org>,
        "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
        "Alexei Starovoitov" <ast@kernel.org>,
        "Daniel Borkmann" <daniel@iogearbox.net>,
        "Andrii Nakryiko" <andrii@kernel.org>,
        "Kumar Kartikeya Dwivedi" <memxor@gmail.com>
Cc:     pablo@netfilter.org, fw@strlen.de, netfilter-devel@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf-next 2/3] bpf: Add support for writing to nf_conn:mark
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Hi Toke,

On Mon, Aug 15, 2022, at 4:25 PM, Toke H=C3=B8iland-J=C3=B8rgensen wrote:
> Daniel Xu <dxu@dxuuu.xyz> writes:
>
>> Support direct writes to nf_conn:mark from TC and XDP prog types. This
>> is useful when applications want to store per-connection metadata. Th=
is
>> is also particularly useful for applications that run both bpf and
>> iptables/nftables because the latter can trivially access this metada=
ta.
>>
>> One example use case would be if a bpf prog is responsible for advanc=
ed
>> packet classification and iptables/nftables is later used for routing
>> due to pre-existing/legacy code.
>>
>> Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
>
> Didn't we agree the last time around that all field access should be
> using helper kfuncs instead of allowing direct writes to struct nf_con=
n?

Sorry, I was not aware of those discussions. Do you have a link handy?

I received the suggestion to enable direct writes here:
https://lore.kernel.org/bpf/CAP01T74aWUW-iyPCV_VfASO6YqfAZmnkYQMN2B4L8ng=
MMgnAcw@mail.gmail.com/ .

Thanks,
Daniel