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
