From: Jesper Dangaard Brouer <brouer@redhat.com>
To: David Ahern <dsahern@gmail.com>
Cc: "Daniel Borkmann" <daniel@iogearbox.net>,
ast@kernel.org, john.fastabend@gmail.com, yhs@fb.com,
netdev@vger.kernel.org, bpf@vger.kernel.org,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
brouer@redhat.com,
"Lorenzo Bianconi" <lorenzo.bianconi@redhat.com>
Subject: Re: [PATCH bpf-next v6 2/6] bpf: add redirect_peer helper
Date: Mon, 12 Oct 2020 11:41:30 +0200 [thread overview]
Message-ID: <20201012114130.6f57247f@carbon> (raw)
In-Reply-To: <1992820b-4916-ed42-e1e2-8e37ae67c92f@gmail.com>
On Sun, 11 Oct 2020 20:50:12 -0600
David Ahern <dsahern@gmail.com> wrote:
> On 10/11/20 10:16 AM, Daniel Borkmann wrote:
> >>
> >> This is awesome results and great work Daniel! :-)
>
> +1
>
> >>
> >> I wonder if we can also support this from XDP, which can also native
> >> redirect into veth. Originally I though we could add the peer netdev
> >> in the devmap, but AFAIK Toke showed me that this was not possible.
> >
> > I think it should be possible with similar principle. What was the
> > limitation that you ran into with devmap for XDP?
If you add a device to devmap and afterwards move this device into a
namespace, then the device is removed from the devmap. This is because
devmap detect/react on NETDEV_UNREGISTER and remove the net_device.
> Should just need an API to set the namespace of the redirect device -
> something that devmap can be extended to include now.
Perhaps for other devices being moved into a namespace.
Specifically for veth the XDP redirect (veth_ndo_xdp_xmit) already
pickup the peer net_device, and *queue* the xdp_frame, thus it's not
directly relevant for the XDP redirect (except we also have an
intermediate queue which is likely bad for the TCP_RR test).
I just tried to test native-XDP redirect into a veth with samples/bpf/
xdp_redirect_map, which doesn't work. Packets are actually getting
silently dropped. After digging into the kernel code, I realized this
is because the *peer*-veth device didn't have a XDP-prog loaded. The
xdp_redirect_map loads a dummy-XDP prog on the veth-device (it can
see), as a way to enable the ndo_xdp_xmit (which we have discussed
before it a broken way to do this, but it have become a defacto way).
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2020-10-12 9:41 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-10 23:40 [PATCH bpf-next v6 0/6] Follow-up BPF helper improvements Daniel Borkmann
2020-10-10 23:40 ` [PATCH bpf-next v6 1/6] bpf: improve bpf_redirect_neigh helper description Daniel Borkmann
2020-10-10 23:40 ` [PATCH bpf-next v6 2/6] bpf: add redirect_peer helper Daniel Borkmann
2020-10-11 9:22 ` Jesper Dangaard Brouer
2020-10-11 17:16 ` Daniel Borkmann
2020-10-12 2:50 ` David Ahern
2020-10-12 9:41 ` Jesper Dangaard Brouer [this message]
2020-10-10 23:40 ` [PATCH bpf-next v6 3/6] bpf: allow for map-in-map with dynamic inner array map entries Daniel Borkmann
2020-10-10 23:49 ` Andrii Nakryiko
2020-10-10 23:40 ` [PATCH bpf-next v6 4/6] bpf, selftests: add test for different array inner map size Daniel Borkmann
2020-10-10 23:40 ` [PATCH bpf-next v6 5/6] bpf, selftests: make redirect_neigh test more extensible Daniel Borkmann
2020-10-10 23:40 ` [PATCH bpf-next v6 6/6] bpf, selftests: add redirect_peer selftest Daniel Borkmann
2020-10-11 17:40 ` [PATCH bpf-next v6 0/6] Follow-up BPF helper improvements patchwork-bot+netdevbpf
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