[PATCH bpf-next v3 0/4] bpf: add BPF_LWT_ENCAP_IP option to bpf_lwt_push_encap

[Peter Oskolkov <posk@google.com>]

This patchset implements BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap
BPF helper. It enables BPF programs (specifically, BPF_PROG_TYPE_LWT_IN
and BPF_PROG_TYPE_LWT_XMIT prog types) to add IP encapsulation headers
to packets (e.g. IP/GRE, GUE, IPIP).

This is useful when thousands of different short-lived flows should be
encapped, each with different and dynamically determined destination.
Although lwtunnels can be used in some of these scenarios, the ability
to dynamically generate encap headers adds more flexibility, e.g.
when routing depends on the state of the host (reflected in global bpf
maps).

V2 changes: Added flowi-based route lookup, IPv6 encapping, and
encapping on ingress.

V3 changes: incorporated David Ahern's suggestions:
  - added l3mdev check/oif (patch 2)
  - sync bpf.h from include/uapi into tools/include/uapi
  - selftest tweaks


Peter Oskolkov (4):
  bpf: add plumbing for BPF_LWT_ENCAP_IP in bpf_lwt_push_encap
  bpf: implement BPF_LWT_ENCAP_IP mode in bpf_lwt_push_encap
  bpf: sync <kdir>/<uapi>/bpf.h with tools/<uapi>/bpf.h
  selftests: bpf: add test_lwt_ip_encap selftest

 include/net/lwtunnel.h                        |   3 +
 include/uapi/linux/bpf.h                      |  23 +-
 net/core/filter.c                             |  47 ++-
 net/core/lwt_bpf.c                            | 147 +++++++++
 tools/include/uapi/linux/bpf.h                |  23 +-
 tools/testing/selftests/bpf/Makefile          |   5 +-
 .../testing/selftests/bpf/test_lwt_ip_encap.c |  84 +++++
 .../selftests/bpf/test_lwt_ip_encap.sh        | 311 ++++++++++++++++++
 8 files changed, 632 insertions(+), 11 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/test_lwt_ip_encap.c
 create mode 100755 tools/testing/selftests/bpf/test_lwt_ip_encap.sh

-- 
2.20.1.495.gaa96b0ce6b-goog