Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753551Ab0KZHwj (ORCPT ); Fri, 26 Nov 2010 02:52:39 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:53162 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753186Ab0KZHwi (ORCPT ); Fri, 26 Nov 2010 02:52:38 -0500 Date: Fri, 26 Nov 2010 08:51:58 +0100 From: Ingo Molnar To: Kees Cook Cc: Kyle McMartin , Marcus Meissner , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, tj@kernel.org, akpm@osdl.org, hpa@zytor.com, w@1wt.eu, alan@lxorguk.ukuu.org.uk, Andrew Morton Subject: Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking Message-ID: <20101126075158.GE19589@elte.hu> References: <20101116104600.GA24015@suse.de> <20101117050759.GE22651@bombadil.infradead.org> <20101118074804.GC32621@elte.hu> <20101120031820.GC4617@outflux.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101120031820.GC4617@outflux.net> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1611 Lines: 42 * Kees Cook wrote: > On Thu, Nov 18, 2010 at 08:48:04AM +0100, Ingo Molnar wrote: > > Agreed. A few other kernel address things that should be hidden are: > > [snip] > > For reference, here's what GRKERNSEC_HIDESYM looks like in grsecurity. > It's quite a sledgehammer, but it does help to point out at least the > minimum number of things that need fixing. Yeah, it's a somewhat disgusting patch - but it also looks useful. It would be more palatable for upstream if it was: - split up - if all those GRKERNSEC_HIDESYM #ifdefs were removed, either by making the grsecurity defaults the default behavior, or by intelligently hiding it behinds wrappers. I'd suggest a single CONFIG_LEGACY_SYMBOLS=y config option for this, but only used to show those symbols that are absolutely needed for compatibility - like /proc/kallsyms. (Newer distros could disable this option and the kernel could eventually default to it being disabled as well.) Also, while changing hexa output to symbolic output is fine, changing the oops output is borderline - that is an absolutely useful piece of information that helps us in decoding crashes. So i'd suggest to split that into a super-paranoid option or so. Anyway, after a split-up we'll see how good the individual bits are - it's a bit of a mixed bag right now. Thanks, Ingo -- 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/