netdev - Re: [PATCH bpf-next 1/4] xdp: Support specifying expected existing program when attaching XDP

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Date:   Thu, 26 Mar 2020 10:04:53 +0000
From:   Lorenz Bauer <lmb@...udflare.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Toke Høiland-Jørgensen <toke@...hat.com>,
        John Fastabend <john.fastabend@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        "David S. Miller" <davem@...emloft.net>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Andrey Ignatov <rdna@...com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH bpf-next 1/4] xdp: Support specifying expected existing
 program when attaching XDP

On Thu, 26 Mar 2020 at 00:16, Andrii Nakryiko <andrii.nakryiko@...il.com> wrote:
>
[...]
>
> Those same folks have similar concern with XDP. In the world where
> container management installs "root" XDP program which other user
> applications can plug into (libxdp use case, right?), it's crucial to
> ensure that this root XDP program is not accidentally overwritten by
> some well-meaning, but not overly cautious developer experimenting in
> his own container with XDP programs. This is where bpf_link ownership
> plays a huge role. Tupperware agent (FB's container management agent)
> would install root XDP program and will hold onto this bpf_link
> without sharing it with other applications. That will guarantee that
> the system will be stable and can't be compromised.

Thanks for the extensive explanation Andrii.

This is what I imagine you're referring to: Tupperware creates a new network
namespace ns1 and a veth0<>veth1 pair, moves one of the veth devices
(let's says veth1) into ns1 and runs an application in ns1. On which veth
would the XDP program go?

The way I understand it, veth1 would have XDP, and the application in ns1 would
be prevented from attaching a new program? Maybe you can elaborate on this
a little.

Lorenz

-- 
Lorenz Bauer  |  Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK

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