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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 7FE09C072B5 for ; Fri, 24 May 2019 17:56:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5637D2133D for ; Fri, 24 May 2019 17:56:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728594AbfEXR4s (ORCPT ); Fri, 24 May 2019 13:56:48 -0400 Received: from mga14.intel.com ([192.55.52.115]:33046 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728222AbfEXR4s (ORCPT ); Fri, 24 May 2019 13:56:48 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 24 May 2019 10:56:48 -0700 X-ExtLoop1: 1 Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.36]) by orsmga001.jf.intel.com with ESMTP; 24 May 2019 10:56:45 -0700 Date: Fri, 24 May 2019 10:56:47 -0700 From: Sean Christopherson To: Andy Lutomirski Cc: Stephen Smalley , "Xing, Cedric" , Andy Lutomirski , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , LSM List , Paul Moore , Eric Paris , "selinux@vger.kernel.org" , Jethro Beekman , "Hansen, Dave" , Thomas Gleixner , "Dr. Greg" , Linus Torvalds , LKML , X86 ML , "linux-sgx@vger.kernel.org" , Andrew Morton , "nhorman@redhat.com" , "npmccallum@redhat.com" , "Ayoun, Serge" , "Katz-zamir, Shay" , "Huang, Haitao" , Andy Shevchenko , "Svahn, Kai" , Borislav Petkov , Josh Triplett , "Huang, Kai" , David Rientjes Subject: Re: SGX vs LSM (Re: [PATCH v20 00/28] Intel SGX1 support) Message-ID: <20190524175647.GC365@linux.intel.com> References: <20190523023517.GA31950@linux.intel.com> <20190523102628.GC10955@linux.intel.com> <20190523141752.GA12078@linux.intel.com> <20190523234044.GC12078@linux.intel.com> <960B34DE67B9E140824F1DCDEC400C0F654E8956@ORSMSX116.amr.corp.intel.com> <20190524174243.GA365@linux.intel.com> <56EA6C7C-F69E-42EB-9CFB-CD0300549298@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <56EA6C7C-F69E-42EB-9CFB-CD0300549298@amacapital.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On Fri, May 24, 2019 at 10:54:34AM -0700, Andy Lutomirski wrote: > > > On May 24, 2019, at 10:42 AM, Sean Christopherson wrote: > > > > Hmm, I've been thinking more about pulling permissions from the source > > page. Conceptually I'm not sure we need to meet the same requirements as > > non-enclave DSOs while the enclave is being built, i.e. do we really need > > to force userspace to fully map the enclave in normal memory? > > > > Consider the Graphene scenario where it's building an enclave on the fly. > > Pulling permissions from the source VMAs means Graphene has to map the > > code pages of the enclave with X. This means Graphene will need EXEDMOD > > (or EXECMEM if Graphene isn't careful). In a non-SGX scenario this makes > > perfect sense since there is no way to verify the end result of RW->RX. > > > > But for SGX, assuming enclaves are whitelisted by their sigstruct (checked > > at EINIT) and because page permissions affect sigstruct.MRENCLAVE, it *is* > > possible to verify the resulting RX contents. E.g. for the purposes of > > LSMs, can't we use the .sigstruct file as a proxy for the enclave and > > require FILE__EXECUTE on the .sigstruct inode to map/run the enclave? > > I think it’s sound for some but not all use cases. I would imagine that a lot > of users won’t restrict sigstruct at all — the “use this as a sigstruct” > permission will be granted to everything and maybe even to memfd. But even > users like that might want to force their enclaves to be hardened such that > writable pages are never executable, in which case Graphene may need an > exception to run. Heh, I belatedly had the same thought. See my follow-up about EXECMEM. > But maybe I’m nuts.