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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17AD5C433FE for ; Sat, 15 Jan 2022 01:18:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231912AbiAOBST (ORCPT ); Fri, 14 Jan 2022 20:18:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231905AbiAOBSS (ORCPT ); Fri, 14 Jan 2022 20:18:18 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1A61C06173E; Fri, 14 Jan 2022 17:18:17 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7154E620CD; Sat, 15 Jan 2022 01:18:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5603EC36AE7; Sat, 15 Jan 2022 01:18:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642209496; bh=brmYZ4xsVJ9RXGnMsvg9QqXh7sxIldild9tW5Lgpe0E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DWDCninBjNgm0moqa+yAl6prAEwa+NU8DPl9Eywp98UqLKkfYMkaUMGMJ5fGL47UV zhnU3GceFNsbVnJHyCPAbcR9wwP1KwxovDqog6RsI16fYebjyC828eoM92vR0eNQm2 yMbueFP5OGsUp/rgyZRkmpQ6ZpXrMi1Vt/XlkJ5ww5sJzxNook3/QHlPWeHve87hqg 6Pp/qbzPf06l3j3DYAB8oYOKFxjHIL/6uYEP4Fj/lgc2mddk6dENyCbB4qrZiZH+xT QU7yOsVvXY1UwmX1Sk29amhpbYPKnJcDMoKTStGonwSZh8MAeX+yeRwYlyZhcEcM80 2pSJoDqNXXb9A== Date: Sat, 15 Jan 2022 03:18:04 +0200 From: Jarkko Sakkinen To: Reinette Chatre Cc: Nathaniel McCallum , Haitao Huang , Andy Lutomirski , dave.hansen@linux.intel.com, tglx@linutronix.de, bp@alien8.de, mingo@redhat.com, linux-sgx@vger.kernel.org, x86@kernel.org, seanjc@google.com, kai.huang@intel.com, cathy.zhang@intel.com, cedric.xing@intel.com, haitao.huang@intel.com, mark.shanahan@intel.com, hpa@zytor.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 05/25] x86/sgx: Introduce runtime protection bits Message-ID: References: <168fb2c9-de3f-384a-bb17-ab84db2cf533@intel.com> <6e1cb295-b86e-ae09-2cf0-cfefd1a10e65@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 14, 2022 at 04:41:59PM -0800, Reinette Chatre wrote: > Hi Jarkko, > > On 1/14/2022 4:27 PM, Jarkko Sakkinen wrote: > > On Fri, Jan 14, 2022 at 04:01:33PM -0800, Reinette Chatre wrote: > >> Hi Jarkko, > >> > >> On 1/14/2022 3:15 PM, Jarkko Sakkinen wrote: > >>> On Fri, Jan 14, 2022 at 03:05:21PM -0800, Reinette Chatre wrote: > >>>> Hi Jarkko, > >>> > >>> How enclave can check a page range that EPCM has the expected permissions? > >> > >> Only way to change EPCM permissions from outside enclave is to run ENCLS[EMODPR] > >> that needs to be accepted from within the enclave via ENCLU[EACCEPT]. At that > >> time the enclave provides the expected permissions and that will fail > >> if there is a mismatch with the EPCM permissions (SGX_PAGE_ATTRIBUTES_MISMATCH). > > > > This is a very valid point but that does make the introspection possible > > only at the time of EACCEPT. > > > > It does not give tools for enclave to make sure that EMODPR-ETRACK dance > > was ever exercised. > > Could you please elaborate? EACCEPT is available to the enclave as a tool > and it would fail if ETRACK was not completed (error SGX_NOT_TRACKED). > > Here is the relevant snippet from the SDM from the section where it > describes EACCEPT: > > IF (Tracking not correct) > THEN > RFLAGS.ZF := 1; > RAX := SGX_NOT_TRACKED; > GOTO DONE; > FI; > > Reinette Yes, if enclave calls EACCEPT it does the necessary introspection and makes sure that ETRACK is completed. I have trouble understanding how enclave makes sure that EACCEPT was called. /Jarkko