Merge branch 'bpf-sockmap'

John Fastabend says:

====================
BPF: sockmap and sk redirect support

This series implements a sockmap and socket redirect helper for BPF
using a model similar to XDP netdev redirect. A sockmap is a BPF map
type that holds references to sock structs. Then with a new sk
redirect bpf helper BPF programs can use the map to redirect skbs
between sockets,

      bpf_sk_redirect_map(map, key, flags)

Finally, we need a call site to attach our BPF logic to do socket
redirects. We added hooks to recv_sock using the existing strparser
infrastructure to do this. The call site is added via the BPF attach
map call. To enable users to use this infrastructure a new BPF program
BPF_PROG_TYPE_SK_SKB is created that allows users to reference sock
details, such as port and ip address fields, to build useful socket
layer program. The sockmap datapath is as follows,

     recv -> strparser -> verdict/action

where this series implements the drop and redirect actions.
Additional, actions can be added as needed.

A sample program is provided to illustrate how a sockmap can
be integrated with cgroups and used to add/delete sockets in
a sockmap. The program is simple but should show many of the
key ideas.

To test this work test_maps in selftests/bpf was leveraged.
We added a set of tests to add sockets and do send/recv ops
on the sockets to ensure correct behavior. Additionally, the
selftests tests a series of negative test cases. We can expand
on this in the future.

I also have a basic test program I use with iperf/netperf
clients that could be sent as an additional sample if folks
want this. It needs a bit of cleanup to send to the list and
wasn't included in this series.

For people who prefer git over pulling patches out of their mail
editor I've posted the code here,

https://github.com/jrfastab/linux-kernel-xdp/tree/sockmap

For some background information on the genesis of this work
it might be helpful to review these slides from netconf 2017
by Thomas Graf,

http://vger.kernel.org/netconf2017.html
https://docs.google.com/a/covalent.io/presentation/d/1dwSKSBGpUHD3WO5xxzZWj8awV_-xL-oYhvqQMOBhhtk/edit?usp=sharing

Thanks to Daniel Borkmann for reviewing and providing initial
feedback.
====================

Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>