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Subject: Re: [PATCH bpf-next v2 4/4] bpf: more lenient bpf_skb_net_shrink()
 with BPF_F_ADJ_ROOM_FIXED_GSO
To:     =?UTF-8?Q?Maciej_=c5=bbenczykowski?= <zenczykowski@gmail.com>,
        =?UTF-8?Q?Maciej_=c5=bbenczykowski?= <maze@google.com>,
        Alexei Starovoitov <ast@kernel.org>
Cc:     Linux Network Development Mailing List <netdev@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        BPF Mailing List <bpf@vger.kernel.org>,
        "David S . Miller" <davem@davemloft.net>,
        Willem de Bruijn <willemb@google.com>
References: <CANP3RGfjLikQ6dg=YpBU0OeHvyv7JOki7CyOUS9modaXAi-9vQ@mail.gmail.com>
 <20210617000953.2787453-1-zenczykowski@gmail.com>
 <20210617000953.2787453-4-zenczykowski@gmail.com>
From:   Daniel Borkmann <daniel@iogearbox.net>
Message-ID: <919e8f26-4b82-9d4c-8973-b2ab2b4bc5bf@iogearbox.net>
Date:   Thu, 24 Jun 2021 16:05:35 +0200
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On 6/17/21 2:09 AM, Maciej Żenczykowski wrote:
> From: Maciej Żenczykowski <maze@google.com>
> 
> This is to more closely match behaviour of bpf_skb_change_proto()
> which now does not adjust gso_size, and thus thoretically supports
> all gso types, and does not need to set SKB_GSO_DODGY nor reset
> gso_segs to zero.
> 
> Something similar should probably be done with bpf_skb_net_grow(),
> but that code scares me.

Took in all except this one, would be good to have a complete solution for
both bpf_skb_net_{shrink,grow}(). If you don't have the cycles, I'll look
into it.

Thanks,
Daniel