Re: [PATCH bpf-next 4/7] bpf: allow to retrieve cgroup v1 classid from v2 hooks

On Fri, Mar 27, 2020 at 9:00 AM Daniel Borkmann [off-list ref] wrote:

Today, Kubernetes is still operating on cgroups v1, however, it is
possible to retrieve the task's classid based on 'current' out of
connect(), sendmsg(), recvmsg() and bind-related hooks for orchestrators
which attach to the root cgroup v2 hook in a mixed env like in case
of Cilium, for example, in order to then correlate certain pod traffic
and use it as part of the key for BPF map lookups.

Have you tried getting this classid directly from task_struct in your
BPF program with vmlinux.h and CO-RE? Seems like it should be pretty
straightforward and not requiring a special BPF handler just for that?

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 include/net/cls_cgroup.h |  7 ++++++-
 net/core/filter.c        | 21 +++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)

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