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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 E7815C48BE3 for ; Thu, 20 Jun 2019 21:09:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C03532084A for ; Thu, 20 Jun 2019 21:09:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726145AbfFTVJS (ORCPT ); Thu, 20 Jun 2019 17:09:18 -0400 Received: from mga04.intel.com ([192.55.52.120]:29919 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726098AbfFTVJS (ORCPT ); Thu, 20 Jun 2019 17:09:18 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Jun 2019 14:09:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,398,1557212400"; d="scan'208";a="311795343" Received: from mudigirx-mobl1.gar.corp.intel.com (HELO localhost) ([10.252.61.12]) by orsmga004.jf.intel.com with ESMTP; 20 Jun 2019 14:09:10 -0700 Date: Fri, 21 Jun 2019 00:09:08 +0300 From: Jarkko Sakkinen To: Sean Christopherson Cc: linux-sgx@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, Bill Roberts , Casey Schaufler , James Morris , Dave Hansen , Cedric Xing , Andy Lutomirski , Jethro Beekman , "Dr . Greg Wettstein" , Stephen Smalley Subject: Re: [RFC PATCH v4 02/12] x86/sgx: Do not naturally align MAP_FIXED address Message-ID: <20190620210851.GG15383@linux.intel.com> References: <20190619222401.14942-1-sean.j.christopherson@intel.com> <20190619222401.14942-3-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190619222401.14942-3-sean.j.christopherson@intel.com> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.10.1 (2018-07-13) Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On Wed, Jun 19, 2019 at 03:23:51PM -0700, Sean Christopherson wrote: > SGX enclaves have an associated Enclave Linear Range (ELRANGE) that is > tracked and enforced by the CPU using a base+mask approach, similar to > how hardware range registers such as the variable MTRRs. As a result, > the ELRANGE must be naturally sized and aligned. > > To reduce boilerplate code that would be needed in every userspace > enclave loader, the SGX driver naturally aligns the mmap() address and > also requires the range to be naturally sized. Unfortunately, SGX fails > to grant a waiver to the MAP_FIXED case, e.g. incorrectly rejects mmap() > if userspace is attempting to map a small slice of an existing enclave. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kernel/cpu/sgx/driver/main.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/sgx/driver/main.c b/arch/x86/kernel/cpu/sgx/driver/main.c > index 07aa5f91b2dd..29384cdd0842 100644 > --- a/arch/x86/kernel/cpu/sgx/driver/main.c > +++ b/arch/x86/kernel/cpu/sgx/driver/main.c > @@ -115,7 +115,13 @@ static unsigned long sgx_get_unmapped_area(struct file *file, > unsigned long pgoff, > unsigned long flags) > { > - if (len < 2 * PAGE_SIZE || len & (len - 1) || flags & MAP_PRIVATE) > + if (flags & MAP_PRIVATE) > + return -EINVAL; > + > + if (flags & MAP_FIXED) > + return addr; > + > + if (len < 2 * PAGE_SIZE || len & (len - 1)) > return -EINVAL; Why the last check is needed given that mmap() no longer does not associate with the layout of the enclave? I'd just wipe it away. /Jarkko