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

Alexei Starovoitov
2020-03-26T19:45:09Z

On Thu, Mar 26, 2020 at 10:47:55AM -0700, Jakub Kicinski wrote:
> 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.

that's not what is happening.
Jakub, I strongly suggest to avoid talking about things you have no clue.