From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Kent Subject: Re: call_usermodehelper in containers Date: Wed, 24 Feb 2016 08:55:16 +0800 Message-ID: <1456275316.2933.14.camel@themaw.net> References: <871u2incyo.fsf@xmission.com> <20131118172844.GA10005@redhat.com> <1455149857.2903.9.camel@themaw.net> <8737sq4teb.fsf@x220.int.ebiederm.org> <56C53DE3.1070108@jp.fujitsu.com> <1455777387.3188.24.camel@themaw.net> <1455781033.2908.5.camel@themaw.net> <87r3g9ychc.fsf@x220.int.ebiederm.org> <1455858850.3356.19.camel@themaw.net> <1456196130.2911.10.camel@themaw.net> <20160223143627.GB31951@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160223143627.GB31951-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "J. Bruce Fields" Cc: linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Stanislav Kinsbursky , Jeff Layton , Greg KH , Linux Containers , Oleg Nesterov , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, "Eric W. Biederman" , bharrosh-C4P08NqkoRlBDgjK7y7TUQ@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: containers.vger.kernel.org On Tue, 2016-02-23 at 09:36 -0500, J. Bruce Fields wrote: > On Tue, Feb 23, 2016 at 10:55:30AM +0800, Ian Kent wrote: > > You know, wrt. the mechanism Oleg suggested, I've been wondering if > > it's > > even necessary to capture process template information for > > execution. > > > > Isn't the main issue the execution of unknown arbitrary objects > > getting > > access to a privileged context? > > > > Then perhaps it is sufficient to require registration of an SHA hash > > (of > > some sort) for these objects by a suitably privileged process and > > only > > allow helper execution of valid objects. > > That executable probably also depends on libraries, services, and tons > of other miscellaneous stuff in its environment. The NFSv4 client > idmapper, for example, may be doing ldap calls. Unless the helper is > created with incredible care, I don't think that it's enough just to > verify that you're executing the correct helper. Yeah, I was thinking the logistics of keeping something like this up to date would be hard but calculating this for every call would be too much overhead I think. > > --b. > > > > > If that is sufficient then helper execution from within a container > > or > > user namespace could just use the callers environment itself. > > > > What else do we need to be wary of, any thoughts Eric? > > > > Ian