[Intel-wired-lan] [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set
Jesper Dangaard Brouer
brouer at redhat.com
Tue Dec 8 09:00:40 UTC 2020
On Mon, 07 Dec 2020 12:52:22 -0800
John Fastabend <john.fastabend at gmail.com> wrote:
> > Use-case(1): Cloud-provider want to give customers (running VMs) ability
> > to load XDP program for DDoS protection (only), but don't want to allow
> > customer to use XDP_TX (that can implement LB or cheat their VM
> > isolation policy).
>
> Not following. What interface do they want to allow loading on? If its
> the VM interface then I don't see how it matters. From outside the
> VM there should be no way to discover if its done in VM or in tc or
> some other stack.
>
> If its doing some onloading/offloading I would assume they need to
> ensure the isolation, etc. is still maintained because you can't
> let one VMs program work on other VMs packets safely.
>
> So what did I miss, above doesn't make sense to me.
The Cloud-provider want to load customer provided BPF-code on the
physical Host-OS NIC (that support XDP). The customer can get access
to a web-interface where they can write or upload their BPF-prog.
As multiple customers can upload BPF-progs, the Cloud-provider have to
write a BPF-prog dispatcher that runs these multiple program. This
could be done via BPF tail-calls, or via Toke's libxdp[1], or via
devmap XDP-progs per egress port.
The Cloud-provider don't fully trust customers BPF-prog. They already
pre-filtered traffic to the given VM, so they can allow customers
freedom to see traffic and do XDP_PASS and XDP_DROP. They
administratively (via ethtool) want to disable the XDP_REDIRECT and
XDP_TX driver feature, as it can be used for violation their VM
isolation policy between customers.
Is the use-case more clear now?
[1] https://github.com/xdp-project/xdp-tools/tree/master/lib/libxdp
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
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