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

David Ahern
2020-03-27T16:12:10Z

On 3/27/20 5:06 AM, Lorenz Bauer wrote:
> However, this behaviour concerns me. It's like Windows not
> letting you delete a file while an application has it opened, which just leads
> to randomly killing programs until you find the right one. It's frustrating
> and counter productive.
>
> You're taking power away from the operator. In your deployment scenario
> this might make sense, but I think it's a really bad model in general. If I am
> privileged I need to be able to exercise that privilege. This means that if
> there is a netdevice in my network namespace, and I have CAP_NET_ADMIN
> or whatever, I can break the association.
>
> So, to be constructive: I'd prefer bpf_link to replace a netlink attachment and
> vice versa. If you need to restrict control, use network namespaces
> to hide the devices, instead of hiding the bpffs.

I had a thought yesterday along similar lines: bpf_link is about
ownership and preventing "accidental" deletes. What's the observability
wrt to learning who owns a program at a specific attach point and can
that ever be hidden.