Re: [PATCH -next 4/4] cgroup: bpf: Add an example to do cgroup checking in BPF

On Tue, Jun 21, 2016 at 05:23:22PM -0700, Martin KaFai Lau wrote:

test_cgrp2_array_pin.c:
A userland program that creates a bpf_map (BPF_MAP_TYPE_GROUP_ARRAY),
pouplates/updates it with a cgroup2's backed fd and pins it to a
bpf-fs's file.  The pinned file can be loaded by tc and then used
by the bpf prog later.  This program can also update an existing pinned
array and it could be useful for debugging/testing purpose.

test_cgrp2_tc_kern.c:
A bpf prog which should be loaded by tc.  It is to demonstrate
the usage of bpf_skb_in_cgroup.

test_cgrp2_tc.sh:
A script that glues the test_cgrp2_array_pin.c and
test_cgrp2_tc_kern.c together.  The idea is like:
1. Use test_cgrp2_array_pin.c to populate a BPF_MAP_TYPE_CGROUP_ARRAY
   with a cgroup fd
2. Load the test_cgrp2_tc_kern.o by tc
3. Do a 'ping -6 ff02::1%ve' to ensure the packet has been
   dropped because of a match on the cgroup

Most of the lines in test_cgrp2_tc.sh is the boilerplate
to setup the cgroup/bpf-fs/net-devices/netns...etc.  It is
not bulletproof on errors but should work well enough and
give enough debug info if things did not go well.

Signed-off-by: Martin KaFai Lau <redacted>
Cc: Alexei Starovoitov <redacted>
Cc: Daniel Borkmann <redacted>
Cc: Tejun Heo <redacted>
---
 samples/bpf/Makefile               |   3 +
 samples/bpf/bpf_helpers.h          |   2 +
 samples/bpf/test_cgrp2_array_pin.c | 109 +++++++++++++++++++++
 samples/bpf/test_cgrp2_tc.sh       | 189 +++++++++++++++++++++++++++++++++++++
 samples/bpf/test_cgrp2_tc_kern.c   |  71 ++++++++++++++
 5 files changed, 374 insertions(+)

...

love the test case.
It's using tc + clsact + cls_bpf in da mode + bpffs + direct packet access
and new cgroup helper.
All the most recent features I can think of :)

Acked-by: Alexei Starovoitov <redacted>