Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753903AbbEKVJe (ORCPT ); Mon, 11 May 2015 17:09:34 -0400 Received: from 251.110.2.81.in-addr.arpa ([81.2.110.251]:49748 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752129AbbEKVJd (ORCPT ); Mon, 11 May 2015 17:09:33 -0400 Date: Mon, 11 May 2015 22:09:14 +0100 From: One Thousand Gnomes To: Alex Henrie Cc: Kees Cook , "H. Peter Anvin" , Doug Johnson , Thomas Gleixner , Ingo Molnar , Tyler Hicks , Al Viro , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: Preserve iopl on fork and execve Message-ID: <20150511220914.7b841848@lxorguk.ukuu.org.uk> In-Reply-To: <1431377398-12046-1-git-send-email-alexhenrie24@gmail.com> References: <1431377398-12046-1-git-send-email-alexhenrie24@gmail.com> Organization: Intel Corporation X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.27; x86_64-redhat-linux-gnu) 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 Content-Length: 1344 Lines: 35 On Mon, 11 May 2015 14:49:58 -0600 Alex Henrie wrote: > Signed-off-by: Alex Henrie > Suggested-by: Doug Johnson > --- > arch/x86/kernel/process_32.c | 2 +- > arch/x86/kernel/process_64.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) This strikes me as insane. Existing iopl using code does not expect to accidentally pass the keys to the empire to any helper apps it spawns. We wouldn't add a new feature that suddenely gave root to tasks forked from a process that was expecting the rights to be dropped, so we certainly shouldn't add iopl on this way. (I agree the behaviour you suggest was probably preferable, it's just 25 years too late to correct that one) Yes it makes using iopl harder, but if anything that is good. You really really must know what you are doing to use iopl, and its really something only hideous things like legacy PC BIOS flash tools should be touching and even then very very carefully having used mlockall and while making no syscalls or page faults with interrupts off. Alan -- 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/