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,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 7D5CAC2D0A3 for ; Tue, 3 Nov 2020 13:52:55 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 0EFDC21D91 for ; Tue, 3 Nov 2020 13:52:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="QMRxIyS4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0EFDC21D91 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=jauu.net Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:Subject:References:In-Reply-To: Message-ID:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=GMRnJwwmmfDY6zE+8458lMlQMMQgzqM5IVTPlMBeLRs=; b=QMRxIyS47KW85tROBSw985PrL ws4sbRHR7V5awnwNPRG7BVkROLTvbvgXO21/EgVvP/V3gPL/hEh3uZuK3D4vuJK7NNdQkSZ282KlX tEgKhaczFtB03n5kT/fuVvvS0T/6GEhpzeIyhk+1tAZZ1CVrm7pVQNBKvzjQW8yJch+LJjFF8wDU9 xm+JDbvx4r7RlOBoy5RqA0ntB/qCeRhjlb/KE0Lg3QZOO2/vbOhqPSq1D47zbFonw8w4kJ2jNsQ2U M09b9r0qjq/Mv+ixWVGi8Edl7AYl5jjfGtadLFs41Vgx9C5zvF2+MgkFgLm0R7VquhSWU8h2HgHKq 1gSIZwP+A==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kZwji-0000ES-00; Tue, 03 Nov 2020 13:52:34 +0000 Received: from mout-p-202.mailbox.org ([80.241.56.172]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kZwjb-0000BY-8L; Tue, 03 Nov 2020 13:52:28 +0000 Received: from smtp2.mailbox.org (smtp2.mailbox.org [80.241.60.241]) (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 4CQWS671PfzQkKw; Tue, 3 Nov 2020 14:52:22 +0100 (CET) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter06.heinlein-hosting.de (spamfilter06.heinlein-hosting.de [80.241.56.125]) (amavisd-new, port 10030) with ESMTP id FlqcKCn97r9e; Tue, 3 Nov 2020 14:52:18 +0100 (CET) Date: Tue, 3 Nov 2020 14:52:14 +0100 (CET) From: Hagen Paul Pfeifer To: Mike Rapoport Message-ID: <1547601988.128687.1604411534845@office.mailbox.org> In-Reply-To: <20201102154028.GD4879@kernel.org> References: <20200924132904.1391-1-rppt@kernel.org> <20201101110935.GA4105325@laniakea> <20201102154028.GD4879@kernel.org> Subject: Re: [PATCH v6 0/6] mm: introduce memfd_secret system call to create "secret" memory areas MIME-Version: 1.0 X-Priority: 3 Importance: Normal X-MBO-SPAM-Probability: X-Rspamd-Score: -0.65 / 15.00 / 15.00 X-Rspamd-Queue-Id: D612C1723 X-Rspamd-UID: 9101f0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201103_085227_575421_BB7EBFD3 X-CRM114-Status: GOOD ( 18.78 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , David Hildenbrand , Peter Zijlstra , Catalin Marinas , Dave Hansen , linux-mm@kvack.org, Will Deacon , linux-kselftest@vger.kernel.org, "H. Peter Anvin" , Christopher Lameter , Idan Yaniv , Thomas Gleixner , Elena Reshetova , linux-arch@vger.kernel.org, Tycho Andersen , linux-nvdimm@lists.01.org, Shuah Khan , x86@kernel.org, Matthew Wilcox , Mike Rapoport , Ingo Molnar , Michael Kerrisk , Arnd Bergmann , James Bottomley , Borislav Petkov , Alexander Viro , Andy Lutomirski , Paul Walmsley , "Kirill A. Shutemov" , Dan Williams , linux-arm-kernel@lists.infradead.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Palmer Dabbelt , linux-fsdevel@vger.kernel.org, Andrew Morton Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Archived-At: List-Archive: > 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? > > 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 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv