From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Weinberger Subject: Re: [PATCH] userns/capability: Add user namespace capability Date: Sun, 18 Oct 2015 22:21:10 +0200 Message-ID: <5623FF36.8080800@nod.at> References: <5622700C.9090107@miglix.eu> <5623FD86.2030609@miglix.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5623FD86.2030609-gyUQdkDHmHmHXe+LvDLADg@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Tobias Markus Cc: LKML , "Eric W. Biederman" , Al Viro , Serge Hallyn , Andrew Morton , Andy Lutomirski , Christoph Lameter , "Michael Kerrisk (man-pages)" , LSM , "open list:ABI/API" , linux-man List-Id: linux-man@vger.kernel.org Am 18.10.2015 um 22:13 schrieb Tobias Markus: > On 17.10.2015 22:17, Richard Weinberger wrote: >> On Sat, Oct 17, 2015 at 5:58 PM, Tobias Markus wrote: >>> One question remains though: Does this break userspace executables that >>> expect being able to create user namespaces without priviledge? Since >>> creating user namespaces without CAP_SYS_ADMIN was not possible before >>> Linux 3.8, programs should already expect a potential EPERM upon calling >>> clone. Since creating a user namespace without CAP_SYS_USER_NS would >>> also cause EPERM, we should be on the safe side. >> >> In case of doubt, yes it will break existing software. >> Hiding user namespaces behind CAP_SYS_USER_NS will not magically >> make them secure. >> > The goal is not to make user namespaces secure, but to limit access to > them somewhat in order to reduce the potential attack surface. We have already a framework to reduce the attack surface, seccomp. There is no need to invent new capabilities for every non-trivial kernel feature. I can understand the user namespaces seems scary and had bugs. But which software didn't? Are there any unfixed exploitable bugs in user namespaces in recent kerenls? Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html