From: Christian Brauner <christian.brauner-Z7WLFzj8eWMS+FvcfC7Uqw@public•gmane.org>
To: "Serge E. Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public•gmane.org>
Cc: "Daniel Micay"
<danielmicay-Re5JQEeQqe8AvxtiuMwx3w@public•gmane.org>,
"Mahesh Bandewar (महेश बंडेवार)"
<maheshb-hpIqsD4AKlfQT0dZR+AlfA@public•gmane.org>,
"Mahesh Bandewar"
<mahesh-bmGAjcP2qsnk1uMJSBkQmQ@public•gmane.org>,
LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public•gmane.org>,
Netdev <netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org>,
Kernel-hardening
<kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public•gmane.org>,
"Linux API" <linux-api-u79uwXL29TY76Z2rM5mHXA@public•gmane.org>,
"Kees Cook" <keescook-F7+t8E8rja9g9hUCZPvPmw@public•gmane.org>,
"Eric W . Biederman"
<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public•gmane.org>,
"Eric Dumazet" <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public•gmane.org>,
"David Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public•gmane.org>
Subject: Re: [kernel-hardening] Re: [PATCH resend 2/2] userns: control capabilities of some user namespaces
Date: Mon, 6 Nov 2017 23:42:08 +0100 [thread overview]
Message-ID: <20171106224207.pdws44vorkxdf6ur@gmail.com> (raw)
In-Reply-To: <20171106221418.GA32543-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
On Mon, Nov 06, 2017 at 04:14:18PM -0600, Serge Hallyn wrote:
> Quoting Daniel Micay (danielmicay-Re5JQEeQqe8AvxtiuMwx3w@public•gmane.org):
> > Substantial added attack surface will never go away as a problem. There
> > aren't a finite number of vulnerabilities to be found.
>
> There's varying levels of usefulness and quality. There is code which I
> want to be able to use in a container, and code which I can't ever see a
> reason for using there. The latter, especially if it's also in a
> staging driver, would be nice to have a toggle to disable.
>
> You're not advocating dropping the added attack surface, only adding a
> way of dealing with an 0day after the fact. Privilege raising 0days can
> exist anywhere, not just in code which only root in a user namespace can
> exercise. So from that point of view, ksplice seems a more complete
> solution. Why not just actually fix the bad code block when we know
> about it?
>
> Finally, it has been well argued that you can gain many new caps from
> having only a few others. Given that, how could you ever be sure that,
> if an 0day is found which allows root in a user ns to abuse
> CAP_NET_ADMIN against the host, just keeping CAP_NET_ADMIN from them
> would suffice? It seems to me that the existing control in
> /proc/sys/kernel/unprivileged_userns_clone might be the better duct tape
> in that case.
I agree that /proc/sys/kernel/unprivileged_userns_clone is the most reasonable
thing to do. This patch introduces a layer of complexity to fine-tune user
namespace creation that - in the relevant security critical scenario - should
simply be turned of entirely.
Is /proc/sys/kernel/unprivileged_userns_clone upstreamed or is this still only
carried downstream?
next prev parent reply other threads:[~2017-11-06 22:42 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-03 0:44 [PATCH resend 2/2] userns: control capabilities of some user namespaces Mahesh Bandewar
[not found] ` <20171103004436.40026-1-mahesh-bmGAjcP2qsnk1uMJSBkQmQ@public.gmane.org>
2017-11-04 23:53 ` Serge E. Hallyn
[not found] ` <20171104235346.GA17170-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2017-11-06 7:23 ` Mahesh Bandewar (महेश बंडेवार)
2017-11-06 15:03 ` Serge E. Hallyn
[not found] ` <20171106150302.GA26634-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2017-11-06 21:33 ` [kernel-hardening] " Daniel Micay
[not found] ` <1510003994.736.0.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-11-06 22:14 ` Serge E. Hallyn
[not found] ` <20171106221418.GA32543-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2017-11-06 22:42 ` Christian Brauner [this message]
2017-11-07 2:16 ` Daniel Micay
[not found] ` <1510020963.736.42.camel-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-11-07 3:23 ` Serge E. Hallyn
2017-11-09 18:01 ` chris hyser
[not found] ` <da764cbf-7522-06a0-6c21-adfa3eaac9c2-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
2017-11-09 18:05 ` Serge E. Hallyn
2017-11-09 18:27 ` chris hyser
2017-11-06 23:17 ` Boris Lukashev
2017-11-06 23:39 ` Serge E. Hallyn
2017-11-07 0:01 ` Boris Lukashev
[not found] ` <CAFUG7CcW077LHcQEqk7qy7iVvmi-3J8psD1Kwj45XvHThiZC6w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-07 3:28 ` [kernel-hardening] " Serge E. Hallyn
[not found] ` <20171107032802.GA6669-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2017-11-08 11:09 ` Mahesh Bandewar (महेश बंडेवार)
2017-11-08 19:02 ` Christian Brauner
[not found] ` <20171108190223.vdkyepcaegmub6le-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2017-11-09 0:55 ` Mahesh Bandewar (महेश बंडेवार)
[not found] ` <CAF2d9jjed4Q7QvCD9Kpaa7L-Ngg3XFbJvt0jNVUUwt=52wDjjw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-09 3:21 ` Serge E. Hallyn
2017-11-09 7:13 ` Mahesh Bandewar (महेश बंडेवार)
2017-11-09 7:18 ` Mahesh Bandewar (महेश बंडेवार)
2017-11-09 16:14 ` Serge E. Hallyn
[not found] ` <CAF2d9jgs5MYn1dMT2mbhF=6UB2Hoo5kwmJhXuE6memBfWzkWXQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-09 21:58 ` [kernel-hardening] " Eric W. Biederman
[not found] ` <871sl7dsh8.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-11-10 4:30 ` Mahesh Bandewar (महेश बंडेवार)
2017-11-10 4:46 ` Serge E. Hallyn
[not found] ` <20171110044645.GA3694-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2017-11-10 5:28 ` Mahesh Bandewar (महेश बंडेवार)
2017-11-09 17:25 ` Serge E. Hallyn
2017-11-10 1:49 ` Mahesh Bandewar (महेश बंडेवार)
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