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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 5A4F9C433DF for ; Wed, 26 Aug 2020 19:01:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1A6B82078A for ; Wed, 26 Aug 2020 19:01:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1A6B82078A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=deneb.enyo.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9E5336B0003; Wed, 26 Aug 2020 15:01:58 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 96F656B0005; Wed, 26 Aug 2020 15:01:58 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 85DD56B000C; Wed, 26 Aug 2020 15:01:58 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0054.hostedemail.com [216.40.44.54]) by kanga.kvack.org (Postfix) with ESMTP id 6C3B36B0003 for ; Wed, 26 Aug 2020 15:01:58 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 2B71245B4 for ; Wed, 26 Aug 2020 19:01:58 +0000 (UTC) X-FDA: 77193639516.14.voice84_2e029cd27066 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id 37513182299BB for ; Wed, 26 Aug 2020 19:01:51 +0000 (UTC) X-HE-Tag: voice84_2e029cd27066 X-Filterd-Recvd-Size: 2580 Received: from albireo.enyo.de (albireo.enyo.de [37.24.231.21]) by imf29.hostedemail.com (Postfix) with ESMTP for ; Wed, 26 Aug 2020 19:01:50 +0000 (UTC) Received: from [172.17.203.2] (helo=deneb.enyo.de) by albireo.enyo.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) id 1kB0fd-00039M-Py; Wed, 26 Aug 2020 19:01:17 +0000 Received: from fw by deneb.enyo.de with local (Exim 4.92) (envelope-from ) id 1kB0fd-0004bF-Mv; Wed, 26 Aug 2020 21:01:17 +0200 From: Florian Weimer To: Andy Lutomirski Cc: Dave Hansen , Mike Rapoport , LKML , Alan Cox , Andrew Morton , Christopher Lameter , Dave Hansen , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Peter Zijlstra , "Reshetova\, Elena" , Thomas Gleixner , Tycho Andersen , Linux API , Linux-MM Subject: Re: [RFC PATCH] mm: extend memfd with ability to create "secret" memory areas References: <20200130162340.GA14232@rapoport-lnx> <6e020a65-b516-9407-228f-2a3a32947ab9@intel.com> Date: Wed, 26 Aug 2020 21:01:17 +0200 In-Reply-To: (Andy Lutomirski's message of "Wed, 26 Aug 2020 09:54:57 -0700") Message-ID: <87y2m1qlj6.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 37513182299BB X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: * Andy Lutomirski: >> I _believe_ there are also things like AES-NI that can get strong >> protection from stuff like this. They load encryption keys into (AVX) >> registers and then can do encrypt/decrypt operations without the keys >> leaving the registers. If the key was loaded from a secret memory area >> right into the registers, I think the protection from cache attacks >> would be pretty strong. > > Except for context switches :) An rseq sequence could request that the AVX registers should be cleared on context switch. (I'm mostly kidding.) I think the main issue is that we do not have a good established programming model to actually use such features and completely avoid making copies of secret data.