Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752370AbbKIVYe (ORCPT ); Mon, 9 Nov 2015 16:24:34 -0500 Received: from mail-io0-f173.google.com ([209.85.223.173]:35379 "EHLO mail-io0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751295AbbKIVY2 (ORCPT ); Mon, 9 Nov 2015 16:24:28 -0500 MIME-Version: 1.0 In-Reply-To: References: <1447018493-20631-1-git-send-email-Julia.Lawall@lip6.fr> <20151108221624.GP18797@mwanda> <20151109054253.GQ18797@mwanda> <20151109134942.GB8264@mwanda> <20151109180555.28c45c3ccaf2042dd7fefec4@gmail.com> Date: Mon, 9 Nov 2015 13:24:27 -0800 X-Google-Sender-Auth: 4yhS_UKRKCINltM0-UW6SErLfb4 Message-ID: Subject: Re: [kernel-hardening] Re: [PATCH] video: constify geode ops structures From: Kees Cook To: Julia Lawall Cc: Emese Revfy , "kernel-hardening@lists.openwall.com" , Dan Carpenter , Joe Perches , kernel-janitors@vger.kernel.org, LKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2052 Lines: 57 On Mon, Nov 9, 2015 at 9:48 AM, Julia Lawall wrote: > On Mon, 9 Nov 2015, Emese Revfy wrote: > >> On Mon, 9 Nov 2015 14:50:47 +0000 (GMT) >> Julia Lawall wrote: >> > > Actually, it looks like Emese Revfy is going to merge the GCC plugin >> > > constify stuff sooner rather than later so maybe adding all these consts >> > > isn't going to be needed. >> > >> > Is there any advantage of const over the plugin? The consts are easy to >> > add. >> >> Hi, >> >> I think it's a very good advantage that the plugin constifies automatically >> without regular maintenance (e.g., generate patches with coccinelle, >> send patches to the maintainers every new kernel version). ;) >> But if it doesn't convince you, I did constification by hand (with a coccinelle >> script) some years ago. >> There are too many types that can be const and it took too long to prepare and >> get the maintainers to accept the patches. >> And it never ends as there are always new types that can be const. > > What happens if some structures cannot be made const because there is a > reassignment somewhere? Is there any feedback about the problem? AIUI, for now, we can't make those const (though I would be happy to be corrected). My hope would be to allow reassignment using something like PaX's kernel_open/kernel_close inlines to allow for temporary modification of read-only things (as part of the KERNEXEC feature). -Kees > > julia > >> >> > Does the plugin help for structures that have non-function fields? >> Yes, it does. See __do_const here: >> http://www.openwall.com/lists/kernel-hardening/2015/11/06/11 >> or more about the constify plugin: >> https://pax.grsecurity.net/docs/PaXTeam-H2HC13-PaX-gcc-plugins.pdf >> >> -- >> Emese >> -- 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/