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=-9.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL autolearn=no 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 8857DC11D00 for ; Fri, 21 Feb 2020 00:11:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 56A6A208E4 for ; Fri, 21 Feb 2020 00:11:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="Gqbbv60b" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729387AbgBUALG (ORCPT ); Thu, 20 Feb 2020 19:11:06 -0500 Received: from linux.microsoft.com ([13.77.154.182]:43026 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729373AbgBUALF (ORCPT ); Thu, 20 Feb 2020 19:11:05 -0500 Received: from [10.131.86.135] (unknown [131.107.147.135]) by linux.microsoft.com (Postfix) with ESMTPSA id BF7BB2007690; Thu, 20 Feb 2020 16:11:04 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com BF7BB2007690 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1582243864; bh=zorJuQNXMnYkPB8Xz0B94YjuA01qeWQy1dyOh6tP+f8=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=Gqbbv60bmqz+5F6mV/kCW3gQZGu3DycmYrYLu8NMF+ZHg4LfwU14I/TTaZKt2yHJK qvlueHIQyEPAkSW+rKdO9Uxo1MXtzS5rI8gxvOKqp0qt1eantpqZaiLAqKmy20yLRv mHenMROitS8e5qUS0mN4zJi8tgUR3TtD4JvjaDLk= Subject: Re: [PATCH v26 10/22] x86/sgx: Linux Enclave Driver To: Jarkko Sakkinen , Sean Christopherson Cc: linux-kernel@vger.kernel.org, x86@kernel.org, linux-sgx@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, nhorman@redhat.com, npmccallum@redhat.com, haitao.huang@intel.com, andriy.shevchenko@linux.intel.com, tglx@linutronix.de, kai.svahn@intel.com, bp@alien8.de, josh@joshtriplett.org, luto@kernel.org, kai.huang@intel.com, rientjes@google.com, cedric.xing@intel.com, puiterwijk@redhat.com, linux-security-module@vger.kernel.org, Suresh Siddha , Haitao Huang References: <20200209212609.7928-1-jarkko.sakkinen@linux.intel.com> <20200209212609.7928-11-jarkko.sakkinen@linux.intel.com> <15074c16-4832-456d-dd12-af8548e46d6d@linux.microsoft.com> <20200220181345.GD3972@linux.intel.com> <7738b3cf-fb32-5306-5740-59974444e327@linux.microsoft.com> <20200220184842.GE3972@linux.intel.com> <20200220221607.GB26618@linux.intel.com> From: Jordan Hand Message-ID: <2c077197-a8a7-feac-58ea-e901c92fb58b@linux.microsoft.com> Date: Thu, 20 Feb 2020 16:11:04 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200220221607.GB26618@linux.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-sgx-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On 2/20/20 2:16 PM, Jarkko Sakkinen wrote: > On Thu, Feb 20, 2020 at 10:48:42AM -0800, Sean Christopherson wrote: >> My biggest concern for allowing PROT_EXEC if RIE is that it would result >> in #PF(SGX) (#GP on Skylake) due to an EPCM violation if the enclave >> actually tried to execute from such a page. This isn't a problem for the >> kernel as the fault will be reported cleanly through the vDSO (or get >> delivered as a SIGSEGV if the enclave isn't entered through the vDSO), but >> it's a bit weird for userspace as userspace will see the #PF(SGX) and >> likely assume the EPC was lost, e.g. silently restart the enclave instead >> of logging an error that the enclave is broken. > > I think right way to fix the current implementation is to -EACCES mmap() > (and mprotect) when !!(current->personality & READ_IMPLIES_EXEC). > I agree. It still means userspace code with an executable stack can't mmap/mprotect enclave pages and request PROT_READ but the check you've proposed would more consistently enforce this which is easier to understand from userspace perspective. -Jordan