From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 671A2C31E4A for ; Thu, 13 Jun 2019 23:18:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 456BF21537 for ; Thu, 13 Jun 2019 23:18:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726583AbfFMXR4 (ORCPT ); Thu, 13 Jun 2019 19:17:56 -0400 Received: from mga12.intel.com ([192.55.52.136]:13074 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726519AbfFMXR4 (ORCPT ); Thu, 13 Jun 2019 19:17:56 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 13 Jun 2019 16:17:55 -0700 X-ExtLoop1: 1 Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.36]) by orsmga005.jf.intel.com with ESMTP; 13 Jun 2019 16:17:55 -0700 Date: Thu, 13 Jun 2019 16:17:55 -0700 From: Sean Christopherson To: "Xing, Cedric" Cc: Stephen Smalley , "linux-security-module@vger.kernel.org" , "selinux@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-sgx@vger.kernel.org" , "jarkko.sakkinen@linux.intel.com" , "luto@kernel.org" , "jmorris@namei.org" , "serge@hallyn.com" , "paul@paul-moore.com" , "eparis@parisplace.org" , "jethro@fortanix.com" , "Hansen, Dave" , "tglx@linutronix.de" , "torvalds@linux-foundation.org" , "akpm@linux-foundation.org" , "nhorman@redhat.com" , "pmccallum@redhat.com" , "Ayoun, Serge" , "Katz-zamir, Shay" , "Huang, Haitao" , "andriy.shevchenko@linux.intel.com" , "Svahn, Kai" , "bp@alien8.de" , "josh@joshtriplett.org" , "Huang, Kai" , "rientjes@google.com" , "Roberts, William C" , "Tricca, Philip B" Subject: Re: [RFC PATCH v1 2/3] LSM/x86/sgx: Implement SGX specific hooks in SELinux Message-ID: <20190613231755.GD18385@linux.intel.com> References: <20190611220243.GB3416@linux.intel.com> <8d99d8fb-a921-286a-8cf0-cd522e09b37c@tycho.nsa.gov> <960B34DE67B9E140824F1DCDEC400C0F65503EDD@ORSMSX116.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <960B34DE67B9E140824F1DCDEC400C0F65503EDD@ORSMSX116.amr.corp.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On Thu, Jun 13, 2019 at 04:03:24PM -0700, Xing, Cedric wrote: > > From: Stephen Smalley [mailto:sds@tycho.nsa.gov] > > Sent: Thursday, June 13, 2019 10:02 AM > > > > > My RFC series[1] implements #1. My understanding is that Andy > > > (Lutomirski) prefers #2. Cedric's RFC series implements #3. > > > > > > Perhaps the easiest way to make forward progress is to rule out the > > > options we absolutely *don't* want by focusing on the potentially > > > blocking issue with each option: > > > > > > #1 - SGX UAPI funkiness > > > > > > #2 - Auditing complexity, potential enclave lock contention > > > > > > #3 - Pushing SGX details into LSMs and complexity of kernel > > > implementation > > > > > > > > > [1] > > > https://lkml.kernel.org/r/20190606021145.12604-1-sean.j.christopherson > > > @intel.com > > > > Given the complexity tradeoff, what is the clear motivating example for > > why #1 isn't the obvious choice? That the enclave loader has no way of > > knowing a priori whether the enclave will require W->X or WX? But > > aren't we better off requiring enclaves to be explicitly marked as > > needing such so that we can make a more informed decision about whether > > to load them in the first place? > > Are you asking this question at a) page granularity, b) file granularity or > c) enclave (potentially comprised of multiple executable files) granularity? > > #b is what we have on regular executable files and shared objects (i.e. > FILE__EXECMOD). We all know how to do that. > > #c is kind of new but could be done via some proxy file (e.g. sigstruct file) > hence reduced to #b. > > #a is problematic. It'd require compilers/linkers to generate such > information, and proper executable image file format to carry that > information, to be eventually picked up the loader. SELinux doesn't have > PAGE__EXECMOD I guess is because it is generally considered impractical. > > Option #1 however requires #a because the driver doesn't track which page was > loaded from which file, otherwise it can no longer be qualified "simple". Or > we could just implement #c, which will make all options simpler. But I guess > #b is still preferred, to be aligned with what SELinux is enforcing today on > regular memory pages.o Option #1 doesn't require (a). The checks will happen for every page, but in the RFCs I sent, the policies are still attached to files and processes, i.e. (b).