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

Jakub Kicinski
2020-03-26T17:47:59Z

On Thu, 26 Mar 2020 10:04:53 +0000 Lorenz Bauer wrote:
> On Thu, 26 Mar 2020 at 00:16, Andrii Nakryiko <andrii.nakryiko@gmail.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.

Nope, there is no veths involved. Tupperware mediates the requests
from containers to install programs on the physical interface for
heavy-duty network processing like DDoS protection for the entire
machine.