tree a32c779f93181a077fd74083f400b4cf6be17924
parent cbdc3ed88a955e22d3a4fe0a6ed03ac17e339042
author Daniel Borkmann <daniel@iogearbox.net> 1426531061 +0100
committer Stephen Hemminger <shemming@brocade.com> 1427237123 -0700

tc: add eBPF support to f_bpf

This work adds the tc frontend for kernel commit e2e9b6541dd4 ("cls_bpf:
add initial eBPF support for programmable classifiers").

A C-like classifier program (f.e. see e2e9b6541dd4) is being compiled via
LLVM's eBPF backend into an ELF file, that is then being passed to tc. tc
then loads, if any, eBPF maps and eBPF opcodes (with fixed-up eBPF map file
descriptors) out of its dedicated sections, and via bpf(2) into the kernel
and then the resulting fd via netlink down to cls_bpf. cls_bpf allows for
annotations, currently, I've used the file name for that, so that the user
can easily identify his filter when dumping configurations back.

Example usage:

  clang -O2 -emit-llvm -c cls.c -o - | llc -march=bpf -filetype=obj -o cls.o
  tc filter add dev em1 parent 1: bpf run object-file cls.o classid x:y

  tc filter show dev em1 [...]
  filter parent 1: protocol all pref 49152 bpf handle 0x1 flowid x:y cls.o

I placed the parser bits derived from Alexei's kernel sample, into tc_bpf.c
as my next step is to also add the same support for BPF action, so we can
have a fully fledged eBPF classifier and action in tc.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>