From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752722Ab0KQX6D (ORCPT ); Wed, 17 Nov 2010 18:58:03 -0500 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:46240 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751658Ab0KQX6C (ORCPT ); Wed, 17 Nov 2010 18:58:02 -0500 Date: Wed, 17 Nov 2010 23:56:47 +0000 From: Alan Cox To: Kay Sievers Cc: Valdis.Kletnieks@vt.edu, Lennart Poettering , linux-kernel , Greg KH , Werner Fink , Jiri Slaby Subject: Re: tty: add 'active' sysfs attribute to tty0 and console device Message-ID: <20101117235647.00766e32@lxorguk.ukuu.org.uk> In-Reply-To: References: <1289922400.1253.3.camel@yio.site> <20101116155717.6671e484@lxorguk.ukuu.org.uk> <20101116171447.29336514@lxorguk.ukuu.org.uk> <20101116195538.7fa66b97@lxorguk.ukuu.org.uk> <20101116213622.GA17824@tango.0pointer.de> <20101116225619.5fa7ef8b@lxorguk.ukuu.org.uk> <20101116231023.GB27594@tango.0pointer.de> <25482.1290031268@localhost> X-Mailer: Claws Mail 3.7.6 (GTK+ 2.18.9; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Brilliant conclusion. If you have mounted it, you own it. But you can > not make your inactive session mount another new one. It's like this > since ages. Hint: try stuff before hitting reply too fast. :) Except during the window when screen switching, or of course you could just ssh in remotely and gdb or similar a process with it as controlling tty running on your console and issue a vt switch back, then mount it. Ironically the move from a root owned X server has made that much simpler to automate, although it was always possible. Given you can often guess from the idle data if the victim has gone away from the box it's not ideal. Even better any mess will appear on my display and get hidden when I flip it back. The only way to stop that is to make use of the display locking facility which takes us back where we began in saying that a usable interface is going to need to lock the display. At that point the current console owner has to choose to allow the console to be switched which can be limited effectively to physical console access and done synchronously. In turn that means to abuse it I already have physical access to the other users key so could just as easily steal it and the software security is therefore sufficient. Alan