Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752828AbdLWM4R (ORCPT ); Sat, 23 Dec 2017 07:56:17 -0500 Received: from mail.sigma-star.at ([95.130.255.111]:45996 "EHLO mail.sigma-star.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750810AbdLWM4P (ORCPT ); Sat, 23 Dec 2017 07:56:15 -0500 From: Richard Weinberger To: Dongsu Park Cc: Richard Weinberger , LKML , Miklos Szeredi , Linux Containers , Seth Forshee , Alban Crequy , "Eric W . Biederman" , Sargun Dhillon , "linux-mtd@lists.infradead.org" Subject: Re: [PATCH 02/11] mtd: Check permissions towards mtd block device inode when mounting Date: Sat, 23 Dec 2017 13:56:51 +0100 Message-ID: <65834980.AClogkzgvk@blindfold> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1316 Lines: 35 Dongsu, Am Samstag, 23. Dezember 2017, 13:18:30 CET schrieb Dongsu Park: > Hi, > > On Fri, Dec 22, 2017 at 10:06 PM, Richard Weinberger > > wrote: > > Dongsu, > > > > On Fri, Dec 22, 2017 at 3:32 PM, Dongsu Park wrote: > >> From: Seth Forshee > >> > >> Unprivileged users should not be able to mount mtd block devices > >> when they lack sufficient privileges towards the block device > >> inode. Update mount_mtd() to validate that the user has the > >> required access to the inode at the specified path. The check > >> will be skipped for CAP_SYS_ADMIN, so privileged mounts will > >> continue working as before. > > > > What is the big picture of this? > > Can in future an unprivileged user just mount UBIFS? > > I'm not sure I'm aware of all use cases w.r.t mtd & ubifs. > To my understanding, in these days many container runtimes allow > unprivileged users to run containers. (docker, lxc, runc, bubblewrap, etc) > That's why the kernel should deal with additional permission checks > that might have not been necessary in the past. > This MTD patch is one of those special cases. My fear is that a corner case is forgotten and all of a sudden someone can do funky things with MTD in a container... Thanks, //richard