netdev - Re: [RFC PATCH iproute2] Drop capabilities if not running ip exec vrf with libcap

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Date:   Tue, 27 Mar 2018 18:43:42 +0100
From:   Luca Boccassi <bluca@...ian.org>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     netdev@...r.kernel.org, dsahern@...il.com, luto@...capital.net
Subject: Re: [RFC PATCH iproute2] Drop capabilities if not running ip exec
 vrf with libcap

On Tue, 2018-03-27 at 10:15 -0700, Stephen Hemminger wrote:
> On Tue, 27 Mar 2018 17:24:19 +0100
> Luca Boccassi <bluca@...ian.org> wrote:
> 
> > ip vrf exec requires root or CAP_NET_ADMIN, CAP_SYS_ADMIN and
> > CAP_DAC_OVERRIDE. It is not possible to run unprivileged commands
> > like
> > ping as non-root or non-cap-enabled due to this requirement.
> > To allow users and administrators to safely add the required
> > capabilities to the binary, drop all capabilities on start if not
> > invoked with "vrf exec".
> > Update the manpage with the requirements.
> > 
> > Signed-off-by: Luca Boccassi <bluca@...ian.org>
> 
> Gets a little messy, but don't have a better answer.
> When a command like iproute gets involved in security policy things
> I become concerned that it may have unexpected consequences.

Yeah I understand. It requires an explicit action by the sysadmin, to
give you plausible deniability :-)

I've seen changes to let BPF permissions be managed via an LSM (I think
SELinux support is already merged in 4.15), so perhaps one day we'll be
able to do the whole shebang (subdir in /sys + load bpf + manipulate
cgroup) in a more fine-grained way, but for now I think this will do.

I'll send v1 shortly with the change asked by David.

-- 
Kind regards,
Luca Boccassi
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