netdev - [PATCH bpf-next 0/4] L2 encap support for bpf_skb_adjust

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Date:   Mon,  1 Apr 2019 16:32:07 +0100
From:   Alan Maguire <alan.maguire@...cle.com>
To:     willemb@...gle.com, ast@...nel.org, daniel@...earbox.net,
        davem@...emloft.net, shuah@...nel.org, kafai@...com,
        songliubraving@...com, yhs@...com, quentin.monnet@...ronome.com,
        john.fastabend@...il.com, rdna@...com,
        linux-kselftest@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Alan Maguire <alan.maguire@...cle.com>
Subject: [PATCH bpf-next 0/4] L2 encap support for bpf_skb_adjust_room

Extend bpf_skb_adjust_room growth to mark inner MAC header so that
L2 encapsulation can be used for tc tunnels.

Patch #1 extends the existing test_tc_tunnel to support UDP
encapsulation; later we want to be able to test MPLS over UDP and
MPLS over GRE encapsulation.

Patch #2 adds the BPF_F_ADJ_ROOM_ENCAP_L2(len) macro, which
allows specification of inner mac length.  Other approaches were
explored prior to taking this approach.  Specifically, I tried
automatically computing the inner mac length on the basis of the
specified flags (so inner maclen for GRE/IPv4 encap is the len_diff
specified to bpf_skb_adjust_room minus GRE + IPv4 header length
for example).  Problem with this is that we don't know for sure
what form of GRE/UDP header we have; is it a full GRE header,
or is it a FOU UDP header or generic UDP encap header? My fear
here was we'd end up with an explosion of flags.  The other approach
tried was to support inner L2 header marking as a separate room
adjustment, i.e. adjust for L3/L4 encap, then call
bpf_skb_adjust_room for L2 encap.  This can be made to work but
because it imposed an order on operations, felt a bit clunky.

Patch #3 syncs tools/ bpf.h.

Patch #4 extends the tests again to support MPLSoverGRE and
MPLSoverUDP encap, along with existing test coverage.

Alan Maguire (4):
  selftests_bpf: extend test_tc_tunnel for UDP encap
  bpf: add layer 2 encap support to bpf_skb_adjust_room
  bpf: sync bpf.h to tools/ for BPF_F_ADJ_ROOM_ENCAP_L2
  selftests_bpf: extend test_tc_tunnel.sh test for L2 encap

 include/uapi/linux/bpf.h                           |   5 +
 net/core/filter.c                                  |  19 +-
 tools/include/uapi/linux/bpf.h                     |   5 +
 tools/testing/selftests/bpf/progs/test_tc_tunnel.c | 281 ++++++++++++++++-----
 tools/testing/selftests/bpf/test_tc_tunnel.sh      | 105 +++++---
 5 files changed, 318 insertions(+), 97 deletions(-)

-- 
1.8.3.1