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,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 17A7FC55178 for ; Tue, 3 Nov 2020 16:30:20 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9A6D522370 for ; Tue, 3 Nov 2020 16:30:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="aIT9WT+B" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9A6D522370 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 630AC163D0192; Tue, 3 Nov 2020 08:30:19 -0800 (PST) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=rppt@kernel.org; receiver= Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 6F7D8163D018B for ; Tue, 3 Nov 2020 08:30:17 -0800 (PST) Received: from kernel.org (unknown [87.71.17.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8FB1C206DF; Tue, 3 Nov 2020 16:30:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604421016; bh=jYHfX66WW2BdNqS2XWf0ysCG2+5llIa7XFBTFdDX/eI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aIT9WT+BvHALjjzBR+JANCva7x0iax3JsHcWBCEfbBEXiFyByvncM0vQDEjoMsNzh qIUHx4c/P1fmtrQLv9EIQHUB/NNPUa0sJ3XCbfY5Co0b/q6PUKAT7BitPwWCXDu5+c 05kTyD2Qgu6hQisAN/yBj1hMLhxnioRXXIEvqYek= Date: Tue, 3 Nov 2020 18:30:02 +0200 From: Mike Rapoport To: Hagen Paul Pfeifer Subject: Re: [PATCH v6 0/6] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: <20201103163002.GK4879@kernel.org> References: <20200924132904.1391-1-rppt@kernel.org> <20201101110935.GA4105325@laniakea> <20201102154028.GD4879@kernel.org> <1547601988.128687.1604411534845@office.mailbox.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1547601988.128687.1604411534845@office.mailbox.org> Message-ID-Hash: MILWQACYLKTQ6DR2BV67KQX5KG5GTCFE X-Message-ID-Hash: MILWQACYLKTQ6DR2BV67KQX5KG5GTCFE X-MailFrom: rppt@kernel.org X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , 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.kerne l.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 X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Tue, Nov 03, 2020 at 02:52:14PM +0100, Hagen Paul Pfeifer wrote: > > On 11/02/2020 4:40 PM Mike Rapoport wrote: > > > > Isn't memfd_secret currently *unnecessarily* designed to be a "one task > > > feature"? memfd_secret fulfills exactly two (generic) features: > > > > > > - address space isolation from kernel (aka SECRET_EXCLUSIVE, not in kernel's > > > direct map) - hide from kernel, great > > > - disabling processor's memory caches against speculative-execution vulnerabilities > > > (spectre and friends, aka SECRET_UNCACHED), also great > > > > > > But, what about the following use-case: implementing a hardened IPC mechanism > > > where even the kernel is not aware of any data and optionally via SECRET_UNCACHED > > > even the hardware caches are bypassed! With the patches we are so close to > > > achieving this. > > > > > > How? Shared, SECRET_EXCLUSIVE and SECRET_UNCACHED mmaped pages for IPC > > > involved tasks required to know this mapping (and memfd_secret fd). After IPC > > > is done, tasks can copy sensitive data from IPC pages into memfd_secret() > > > pages, un-sensitive data can be used/copied everywhere. > > > > 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. > > > One missing piece is still the secure zeroization of the page(s) if the > > > mapping is closed by last process to guarantee a secure cleanup. This can > > > probably done as an general mmap feature, not coupled to memfd_secret() and > > > can be done independently ("reverse" MAP_UNINITIALIZED feature). > > > > There are "init_on_alloc" and "init_on_free" kernel parameters that > > enable zeroing of the pages on alloc and on free globally. > > Anyway, I'll add zeroing of the freed memory to secretmem. > > Great, this allows page-specific (thus runtime-performance-optimized) zeroing > of secured pages. init_on_free lowers the performance to much and is not precice > enough. > > Hagen -- Sincerely yours, Mike. _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org