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 C433AC4741F for ; Wed, 4 Nov 2020 11:39:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B1FC223BD for ; Wed, 4 Nov 2020 11:39:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729515AbgKDLj1 (ORCPT ); Wed, 4 Nov 2020 06:39:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729263AbgKDLj0 (ORCPT ); Wed, 4 Nov 2020 06:39:26 -0500 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [IPv6:2001:67c:2050::465:202]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52422C0613D3; Wed, 4 Nov 2020 03:39:26 -0800 (PST) Received: from smtp1.mailbox.org (smtp1.mailbox.org [80.241.60.240]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4CR4SB2rQLzQlRc; Wed, 4 Nov 2020 12:39:22 +0100 (CET) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp1.mailbox.org ([80.241.60.240]) by spamfilter04.heinlein-hosting.de (spamfilter04.heinlein-hosting.de [80.241.56.122]) (amavisd-new, port 10030) with ESMTP id F5663DCtL8CE; Wed, 4 Nov 2020 12:39:18 +0100 (CET) Date: Wed, 4 Nov 2020 12:39:13 +0100 (CET) From: Hagen Paul Pfeifer To: Mike Rapoport Cc: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , David Hildenbrand , Elena Reshetova , "H. Peter Anvin" , Idan Yaniv , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Thomas Gleixner , Shuah Khan , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org Message-ID: <1988407921.138656.1604489953944@office.mailbox.org> In-Reply-To: <20201103163002.GK4879@kernel.org> References: <20200924132904.1391-1-rppt@kernel.org> <20201101110935.GA4105325@laniakea> <20201102154028.GD4879@kernel.org> <1547601988.128687.1604411534845@office.mailbox.org> <20201103163002.GK4879@kernel.org> Subject: Re: [PATCH v6 0/6] mm: introduce memfd_secret system call to create "secret" memory areas MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Priority: 3 Importance: Normal X-MBO-SPAM-Probability: ** X-Rspamd-Score: 1.58 / 15.00 / 15.00 X-Rspamd-Queue-Id: B8AE3182D X-Rspamd-UID: 15b699 Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org > On 11/03/2020 5:30 PM Mike Rapoport wrote: > > > > As long as the task share the file descriptor, they can share the > > > secretmem pages, pretty much like normal memfd. > > > > Including process_vm_readv() and process_vm_writev()? Let's take a hypothetical > > "dbus-daemon-secure" service that receives data from process A and wants to > > copy/distribute it to data areas of N other processes. Much like dbus but without > > SOCK_DGRAM rather direct copy into secretmem/mmap pages (ring-buffer). Should be > > possible, right? > > I'm not sure I follow you here. > For process_vm_readv() and process_vm_writev() secremem will be only > accessible on the local part, but not on the remote. > So copying data to secretmem pages using process_vm_writev wouldn't > work. A hypothetical "dbus-daemon-secure" service will not be *process related* with communication peers. E.g. a password-input process (reading a password into secured-memory page) will transfer the password to dbus-daemon-secure and this service will hand-over the password to two additional applications: a IPsec process on CPU0 und CPU1 (which itself use a secured-memory page). So four applications IPC chain: password-input -> dbus-daemon-secure -> {IPsec0, IPsec1} - password-input: uses a secured page to read/save the password locally after reading from TTY - dbus-daemon-secure: uses a secured page for IPC (legitimate user can write and read into the secured page) - IPSecN has secured page to save the password locally (and probably other data as well), IPC memory is memset'ed after copy Goal: the whole password is never saved/touched on non secured pages during IPC transfer. Question: maybe a *file-descriptor passing* mechanism can do the trick? I.e. dbus-daemon-secure allocates via memfd_secret/mmap secure pages and permitted processes will get the descriptor/mmaped-page passed so they can use the pages directly? Hagen