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=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 7FBDDC388F7 for ; Fri, 13 Nov 2020 10:33:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 205312224C for ; Fri, 13 Nov 2020 10:33:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726184AbgKMKd2 (ORCPT ); Fri, 13 Nov 2020 05:33:28 -0500 Received: from outbound-smtp50.blacknight.com ([46.22.136.234]:39267 "EHLO outbound-smtp50.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726176AbgKMKd2 (ORCPT ); Fri, 13 Nov 2020 05:33:28 -0500 X-Greylist: delayed 458 seconds by postgrey-1.27 at vger.kernel.org; Fri, 13 Nov 2020 05:33:27 EST Received: from mail.blacknight.com (pemlinmail05.blacknight.ie [81.17.254.26]) by outbound-smtp50.blacknight.com (Postfix) with ESMTPS id 173F0FB190 for ; Fri, 13 Nov 2020 10:25:49 +0000 (GMT) Received: (qmail 5515 invoked from network); 13 Nov 2020 10:25:48 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.22.4]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 13 Nov 2020 10:25:48 -0000 Date: Fri, 13 Nov 2020 10:25:43 +0000 From: Mel Gorman To: Jarkko Sakkinen Cc: x86@kernel.org, linux-sgx@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Christopherson , linux-mm@kvack.org, Andrew Morton , Matthew Wilcox , Jethro Beekman , Dave Hansen , andriy.shevchenko@linux.intel.com, asapek@google.com, bp@alien8.de, cedric.xing@intel.com, chenalexchen@google.com, conradparker@google.com, cyhanish@google.com, haitao.huang@intel.com, kai.huang@intel.com, kai.svahn@intel.com, kmoy@google.com, ludloff@google.com, luto@kernel.org, nhorman@redhat.com, npmccallum@redhat.com, puiterwijk@redhat.com, rientjes@google.com, tglx@linutronix.de, yaozhangx@google.com, mikko.ylinen@intel.com Subject: Re: [PATCH v41 10/24] mm: Add 'mprotect' hook to struct vm_operations_struct Message-ID: <20201113102543.GK3371@techsingularity.net> References: <20201112220135.165028-1-jarkko@kernel.org> <20201112220135.165028-11-jarkko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20201112220135.165028-11-jarkko@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Fri, Nov 13, 2020 at 12:01:21AM +0200, Jarkko Sakkinen wrote: > From: Sean Christopherson > > Background > ========== > > 1. SGX enclave pages are populated with data by copying from normal memory > via ioctl() (SGX_IOC_ENCLAVE_ADD_PAGES), which will be added later in > this series. > 2. It is desirable to be able to restrict those normal memory data sources. > For instance, to ensure that the source data is executable before > copying data to an executable enclave page. > 3. Enclave page permissions are dynamic (just like normal permissions) and > can be adjusted at runtime with mprotect(). > > This creates a problem because the original data source may have long since > vanished at the time when enclave page permissions are established (mmap() > or mprotect()). > > The solution (elsewhere in this series) is to force enclaves creators to > declare their paging permission *intent* up front to the ioctl(). This > intent can be immediately compared to the source data???s mapping and > rejected if necessary. > > The ???intent??? is also stashed off for later comparison with enclave > PTEs. This ensures that any future mmap()/mprotect() operations > performed by the enclave creator or done on behalf of the enclave > can be compared with the earlier declared permissions. > > Problem > ======= > > There is an existing mmap() hook which allows SGX to perform this > permission comparison at mmap() time. However, there is no corresponding > ->mprotect() hook. > > Solution > ======== > > Add a vm_ops->mprotect() hook so that mprotect() operations which are > inconsistent with any page's stashed intent can be rejected by the driver. > > Cc: linux-mm@kvack.org > Cc: Andrew Morton > Cc: Matthew Wilcox > Cc: Mel Gorman > Acked-by: Jethro Beekman # v40 > Acked-by: Dave Hansen # v40 > # Signed-off-by: Sean Christopherson > Co-developed-by: Jarkko Sakkinen > Signed-off-by: Jarkko Sakkinen Acked-by: Mel Gorman -- Mel Gorman SUSE Labs