From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 18 Nov 2015 09:05:12 -0600 From: Seth Forshee To: Al Viro Cc: Austin S Hemmelgarn , "Eric W. Biederman" , linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, Serge Hallyn , Andy Lutomirski , linux-kernel@vger.kernel.org, Theodore Ts'o Subject: Re: [PATCH v3 0/7] User namespace mount updates Message-ID: <20151118150512.GE134139@ubuntu-hedt> References: <20151117170556.GV22011@ZenIV.linux.org.uk> <20151117172551.GA108807@ubuntu-hedt> <20151117175506.GW22011@ZenIV.linux.org.uk> <564B79B1.3040207@gmail.com> <20151117191606.GC108807@ubuntu-hedt> <564B941A.2070601@gmail.com> <20151117213255.GE108807@ubuntu-hedt> <564C6DD4.6090308@gmail.com> <20151118142238.GB134139@ubuntu-hedt> <20151118145818.GC22011@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151118145818.GC22011@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: On Wed, Nov 18, 2015 at 02:58:18PM +0000, Al Viro wrote: > On Wed, Nov 18, 2015 at 08:22:38AM -0600, Seth Forshee wrote: > > > But it still requires the admin set it up that way, no? And aren't > > privileges required to set up those devices in the first place? > > > > I'm not saying that it wouldn't be a good idea to lock down the backing > > stores for those types of devices too, just that it isn't something that > > a regular user could exploit without an admin doing something to > > facilitate it. > > Sigh... If it boils down to "all admins within all containers must be > trusted not to try and break out" (along with "roothole in any container > escalates to kernel-mode code execution on host"), then what the fuck > is the *point* of bothering with containers, userns, etc. in the first > place? If your model is basically "you want isolation, just use kvm", > fine, but where's the place for userns in all that? > > And if you are talking about the _host_ admin, then WTF not have him just > mount what's needed as part of setup and to hell with mounting those > inside the container? Yes, the host admin. I'm not talking about trusting the admin inside the container at all. >>From my perspective the idea is essentially to allow mounting with fuse or with ext4 using "mount -o loop ..." within a container.