Re: [PATCH iproute2 -next v2 2/2] tc: add eBPF support to f_bpf

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 16 Mar 2015 19:37:41 +0100
Daniel Borkmann <daniel@iogearbox.net> wrote:

> 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>

Applied to net-next of iproute2