netdev - Re: [PATCH v16 0/5] BPF: New helper to obtain namespace data from current task

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Date:   Thu, 9 Jan 2020 17:46:29 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Carlos Neira <cneirabustos@...il.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        Yonghong Song <yhs@...com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        bpf <bpf@...r.kernel.org>, Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH v16 0/5] BPF: New helper to obtain namespace data from
 current task

On Wed, Dec 18, 2019 at 9:38 AM Carlos Neira <cneirabustos@...il.com> wrote:
>
> Currently bpf_get_current_pid_tgid(), is used to do pid filtering in bcc's
> scripts but this helper returns the pid as seen by the root namespace which is
> fine when a bcc script is not executed inside a container.
> When the process of interest is inside a container, pid filtering will not work
> if bpf_get_current_pid_tgid() is used.
> This helper addresses this limitation returning the pid as it's seen by the current
> namespace where the script is executing.
>
> In the future different pid_ns files may belong to different devices, according to the
> discussion between Eric Biederman and Yonghong in 2017 Linux plumbers conference.
> To address that situation the helper requires inum and dev_t from /proc/self/ns/pid.
> This helper has the same use cases as bpf_get_current_pid_tgid() as it can be
> used to do pid filtering even inside a container.

I think the set looks like fine. Please respin against bpf-next
carrying over Yonghong's ack and I'll apply it.
Please squash patch 2 and 3 together.
Updates to tools/uapi/bpf.h don't need to be separated anymore.
Patch 5 can be squashed into them as well.
Could you also improve selftest from patch 4 to test new helper
both inside and outside of some container?
With unshare(CLONE_NEWPID) or something.
Do you have corresponding bcc change to show how it's going to be used?