linux-kernel - Re: RFC(v2): Audit Kernel Container IDs

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Message-ID: <1513009857.6310.337.camel@redhat.com>
Date:   Mon, 11 Dec 2017 11:30:57 -0500
From:   Eric Paris <eparis@...hat.com>
To:     Casey Schaufler <casey@...aufler-ca.com>,
        Mickaël Salaün <mic@...ikod.net>,
        Richard Guy Briggs <rgb@...hat.com>, cgroups@...r.kernel.org,
        Linux Containers <containers@...ts.linux-foundation.org>,
        Linux API <linux-api@...r.kernel.org>,
        Linux Audit <linux-audit@...hat.com>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        Linux Network Development <netdev@...r.kernel.org>
Cc:     mszeredi@...hat.com, "Eric W. Biederman" <ebiederm@...ssion.com>,
        Simo Sorce <simo@...hat.com>, jlayton@...hat.com,
        Carlos O'Donell <carlos@...hat.com>,
        David Howells <dhowells@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Andy Lutomirski <luto@...nel.org>,
        Eric Paris <eparis@...isplace.org>, trondmy@...marydata.com,
        Michael Kerrisk <mtk.manpages@...il.com>
Subject: Re: RFC(v2): Audit Kernel Container IDs

On Sat, 2017-12-09 at 10:28 -0800, Casey Schaufler wrote:
> On 12/9/2017 2:20 AM, Mickaï¿½l Salaï¿½n wrote:

> >  What about automatically create
> > and assign an ID to a process when it enters a namespace different
> > than
> > one of its parent process? This delegates the (permission)
> > responsibility to the use of namespaces (e.g. /proc/sys/user/max_*
> > limit).
> 
> That gets ugly when you have a container that uses user, filesystem,
> network and whatever else namespaces. If all containers used the same
> set of namespaces I think this would be a fine idea, but they don't.
> 
> > One interesting side effect of this approach would be to be able to
> > identify which processes are in the same set of namespaces, even if
> > not
> > spawn from the container but entered after its creation (i.e. using
> > setns), by creating container IDs as a (deterministic) checksum
> > from the
> > /proc/self/ns/* IDs.
> > 
> > Since the concern is to identify a container, I think the ability
> > to
> > audit the switch from one container ID to another is enough. I
> > don't
> > think we need nested IDs.
> 
> Because a container doesn't have to use namespaces to be a container
> you still need a mechanism for a process to declare that it is in
> fact
> in a container, and to identify the container.

I like the idea but I'm still tossing it around in my head (and
thinking about Casey's statement too). Lets say we have a 'docker-like' 
container with pid=100  netns=X,userns=Y,mountns=Z. If I'm on the host
in all init namespaces and I run
  nsenter -t 100 -n ip link set eth0 promisc on
How should this be logged? Did this command run in it's own 'container'
unrelated to the 'docker-like' container?

-Eric