From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f169.google.com (mail-wi0-f169.google.com [209.85.212.169]) by kanga.kvack.org (Postfix) with ESMTP id BBDCC6B0253 for ; Fri, 25 Sep 2015 02:15:28 -0400 (EDT) Received: by wicgb1 with SMTP id gb1so5951802wic.1 for ; Thu, 24 Sep 2015 23:15:28 -0700 (PDT) Received: from mail-wi0-x231.google.com (mail-wi0-x231.google.com. [2a00:1450:400c:c05::231]) by mx.google.com with ESMTPS id xm4si2549782wib.90.2015.09.24.23.15.27 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 24 Sep 2015 23:15:27 -0700 (PDT) Received: by wiclk2 with SMTP id lk2so7878722wic.0 for ; Thu, 24 Sep 2015 23:15:27 -0700 (PDT) Date: Fri, 25 Sep 2015 08:15:23 +0200 From: Ingo Molnar Subject: Re: [PATCH 26/26] x86, pkeys: Documentation Message-ID: <20150925061523.GA15753@gmail.com> References: <20150916174903.E112E464@viggo.jf.intel.com> <20150916174913.AF5FEA6D@viggo.jf.intel.com> <20150920085554.GA21906@gmail.com> <55FF88BA.6080006@sr71.net> <20150924094956.GA30349@gmail.com> <56044A88.7030203@sr71.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <56044A88.7030203@sr71.net> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andrew Morton , Peter Zijlstra , Andy Lutomirski , Borislav Petkov , Kees Cook * Dave Hansen wrote: > > I.e. AFAICS pkeys could be used to create true '--x' permissions for executable > > (user-space) pages. > > Just remember that all of the protections are dependent on the contents of PKRU. > If an attacker controls the Access-Disable bit in PKRU for the executable-only > region, you're sunk. The same is true if the attacker can execute mprotect() calls. > But, that either requires being able to construct and execute arbitrary code > *or* call existing code that sets PKRU to the desired values. Which, I guess, > gets harder to do if all of the the wrpkru's are *in* the execute-only area. Exactly. True --x executable regions makes it harder to 'upgrade' limited attacks. Thanks, Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org