Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753842Ab2KUASf (ORCPT ); Tue, 20 Nov 2012 19:18:35 -0500 Received: from mail-ob0-f174.google.com ([209.85.214.174]:33828 "EHLO mail-ob0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750818Ab2KUASe (ORCPT ); Tue, 20 Nov 2012 19:18:34 -0500 MIME-Version: 1.0 In-Reply-To: References: <20121120204238.GA19554@www.outflux.net> Date: Tue, 20 Nov 2012 16:18:33 -0800 X-Google-Sender-Auth: g1OMruitIqjSgMCEOFN_QNVnQEI Message-ID: Subject: Re: [PATCH v2] devtmpfs: mount with noexec and nosuid From: Kees Cook To: Kay Sievers Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , ellyjones@chromium.org, Roland Eggner Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1031 Lines: 25 On Tue, Nov 20, 2012 at 4:13 PM, Kay Sievers wrote: > On Tue, Nov 20, 2012 at 9:42 PM, Kees Cook wrote: >> Since devtmpfs is writable, make the default noexec,nosuid as well. This >> protects from the case of a privileged process having an arbitrary file >> write flaw and an argumentless arbitrary execution (i.e. it would lack >> the ability to run "mount -o remount,exec,suid /dev"). > > This only really applies to systems without an initramfs when the > kernel mounts /dev over the rootfs it has mounted; with an initramfs, > /dev is always mounted by user code. > > Just checking, that is the use case you are doing that for? Correct. We're using this in Chrome OS, which does not use an initramfs. -Kees -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/