linux-kernel - Re: [RFC][PATCH 0/9] Make containers kernel objects

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Message-Id: <1495551292.2742620.985957224.3FCF254A@webmail.messagingengine.com>
Date:   Tue, 23 May 2017 10:54:52 -0400
From:   Colin Walters <walters@...bum.org>
To:     Djalal Harouni <tixxdz@...il.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Jeff Layton <jlayton@...hat.com>,
        David Howells <dhowells@...hat.com>, trondmy@...marydata.com,
        Miklos Szeredi <mszeredi@...hat.com>,
        linux-nfs@...r.kernel.org,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        "open list:CONTROL GROUP (CGROUP)" <cgroups@...r.kernel.org>
Subject: Re: [RFC][PATCH 0/9] Make containers kernel objects

On Tue, May 23, 2017, at 10:30 AM, Djalal Harouni wrote:
>
> Maybe it depends on the cases, a general approach can be too difficult
> to handle especially from the security point. Maybe it is better to
> identify what operations need what context, and a userspace
> service/proxy can act using kthreadd with the right context... at
> least the shift to this model has been done for years now in the
> mobile industry.

Why not drop the upcall model in favor of having userspace
monitor events via a (more efficient) protocol and react to them on its own?
It's just generally more flexible and avoids all of those issues like
replicating the seccomp configuration, etc.

Something like inotify/signalfd could be a precedent around having a read()/poll()able
fd.  /proc/keys-requests ?

Then if you create a new user namespace, and open /proc/keys-requests, the
kernel will always write to that instead of calling /sbin/request-key.