From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933450AbcLNV2Z (ORCPT ); Wed, 14 Dec 2016 16:28:25 -0500 Received: from frisell.zx2c4.com ([192.95.5.64]:39683 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933112AbcLNV2X (ORCPT ); Wed, 14 Dec 2016 16:28:23 -0500 MIME-Version: 1.0 In-Reply-To: <20161214185000.GA3930@kroah.com> References: <20161214185000.GA3930@kroah.com> From: "Jason A. Donenfeld" Date: Wed, 14 Dec 2016 22:28:18 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [kernel-hardening] [RFC 0/4] make call_usermodehelper a bit more "safe" To: Greg Kroah-Hartman Cc: LKML , kernel-hardening@lists.openwall.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Greg, On Wed, Dec 14, 2016 at 7:50 PM, Greg KH wrote: > So, anyone have any better ideas? Is this approach worth it? Or should > we just go down the "whitelist" path? I think your approach is generally better than the whitelist path. But maybe there's yet a third approach that involves futzing with page permissions at runtime. I think grsec does something similar with read_mostly function pointer structs. Namely, they make them read-only const, and then temporarily twiddle the page permissions if it needs to be changed while disabling preemption. There could be a particular class of data that needs to be "opened" and "closed" in order to modify. Seems like these strings would be a good use of that. Jason