From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262392AbUBXSos (ORCPT ); Tue, 24 Feb 2004 13:44:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262390AbUBXSos (ORCPT ); Tue, 24 Feb 2004 13:44:48 -0500 Received: from chaos.analogic.com ([204.178.40.224]:9088 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id S262392AbUBXSn4 (ORCPT ); Tue, 24 Feb 2004 13:43:56 -0500 Date: Tue, 24 Feb 2004 13:44:18 -0500 (EST) From: "Richard B. Johnson" X-X-Sender: root@chaos Reply-To: root@chaos.analogic.com To: Tomas Szepe cc: sandr8@crocetta.org, Gautam Pagedar , linux-kernel@vger.kernel.org Subject: Re: can i modify ls In-Reply-To: <20040224165943.GB24370@louise.pinerecords.com> Message-ID: References: <005601c3fd75$1c681510$8c01080a@crayii> <403B7402.2000008@universitari.crocetta.org> <20040224163530.GA24370@louise.pinerecords.com> <20040224165943.GB24370@louise.pinerecords.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 24 Feb 2004, Tomas Szepe wrote: > On Feb-24 2004, Tue, 11:44 -0500 > Richard B. Johnson wrote: > > > On Tue, 24 Feb 2004, Tomas Szepe wrote: > > > > > On Feb-24 2004, Tue, 15:55 +0000 > > > Alessandro Salvatori wrote: > > > > > > > it's quite interesting... > > > > > > Actually, it's not. > > > > > > 1) The presence/absence of the read permission on a directory determines > > > whether the user will be able to list the directory's contents. > > > > > > 2) The fs permission model is enforced by the kernel. Trying to impose > > > additional restrictions in userspace is fragile, futile and > > > an incredibly stupid idea. > > > > If you don't have any programming tools and no access to any (like > > a banking or restrictive office environment), and there is no > > way to get any external executable files to run, i.e., no floppy > > or no shell that could possibly access one, then writing a minimal > > 'ls' program that allows the clerk to see what's in her directory > > might be useful. > > So what is it exactly that prevents the admin from running /bin/chmod > in the setup you're describing? No such program. FYI, there are lots of systems where the root file-system has a very limited set of tools, sometimes it's on NFS. The machine needs to be booted with a different root for maintenance. This is even commonplace for store cash-register, and resturant menu setups where there is a "server" in the back room that needs to be restarted in a maintenance mode, been that way since DOS 3.0. A system is secure if (1) there are no tools available to harm it, and (2) if the box that contains additional tools is (physically) locked up. Cheers, Dick Johnson Penguin : Linux version 2.4.24 on an i686 machine (797.90 BogoMips). Note 96.31% of all statistics are fiction.