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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E7771C433E0 for ; Tue, 16 Feb 2021 16:34:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 6C48F64D79 for ; Tue, 16 Feb 2021 16:34:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6C48F64D79 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id DC6836B0005; Tue, 16 Feb 2021 11:34:39 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D75B66B0006; Tue, 16 Feb 2021 11:34:39 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BEDE36B006C; Tue, 16 Feb 2021 11:34:39 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0154.hostedemail.com [216.40.44.154]) by kanga.kvack.org (Postfix) with ESMTP id A6F9A6B0005 for ; Tue, 16 Feb 2021 11:34:39 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 6BBAF1801ED65 for ; Tue, 16 Feb 2021 16:34:39 +0000 (UTC) X-FDA: 77824679478.28.wine70_530584b27645 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin28.hostedemail.com (Postfix) with ESMTP id 475B26C1D for ; Tue, 16 Feb 2021 16:34:39 +0000 (UTC) X-HE-Tag: wine70_530584b27645 X-Filterd-Recvd-Size: 5804 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf46.hostedemail.com (Postfix) with ESMTP for ; Tue, 16 Feb 2021 16:34:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613493278; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KysYIYMpQ7qMwmL/JUOCOKvLfXo3jE4QCyxH618MYzE=; b=I3w7uM2PpN7v5NwkzNlXeRZkCJtq8yWQ3iH1pmbxSDN+xNBCRYZf0jTbByELZXEKm7HJr/ oBW0N0xcvKUQAsECGJAF6tkNux47g5fQmiwcmcRhGS7rJww7WURkb0QHcoN0w4r40BWEke weSnIyGkhw3WCd3+1vRwTJFcFIVn0iE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-12-p1-EOjkyMC-fthVSXfK3rw-1; Tue, 16 Feb 2021 11:34:33 -0500 X-MC-Unique: p1-EOjkyMC-fthVSXfK3rw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8B1051E561; Tue, 16 Feb 2021 16:34:28 +0000 (UTC) Received: from [10.36.114.70] (ovpn-114-70.ams2.redhat.com [10.36.114.70]) by smtp.corp.redhat.com (Postfix) with ESMTP id BF8E31970A; Tue, 16 Feb 2021 16:34:18 +0000 (UTC) Subject: Re: [PATCH v17 07/10] mm: introduce memfd_secret system call to create "secret" memory areas To: jejb@linux.ibm.com, Michal Hocko Cc: Mike Rapoport , Mike Rapoport , Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , 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, Hagen Paul Pfeifer , Palmer Dabbelt References: <20210214091954.GM242749@kernel.org> <052DACE9-986B-424C-AF8E-D6A4277DE635@redhat.com> <244f86cba227fa49ca30cd595c4e5538fe2f7c2b.camel@linux.ibm.com> <12c3890b233c8ec8e3967352001a7b72a8e0bfd0.camel@linux.ibm.com> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Tue, 16 Feb 2021 17:34:17 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <12c3890b233c8ec8e3967352001a7b72a8e0bfd0.camel@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 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: On 16.02.21 17:25, James Bottomley wrote: > On Mon, 2021-02-15 at 20:20 +0100, Michal Hocko wrote: > [...] >>>> What kind of flags are we talking about and why would that be a >>>> problem with memfd_create interface? Could you be more specific >>>> please? >>> >>> You mean what were the ioctl flags in the patch series linked >>> above? They were SECRETMEM_EXCLUSIVE and SECRETMEM_UNCACHED in >>> patch 3/5. >> >> OK I see. How many potential modes are we talking about? A few or >> potentially many? > > Well I initially thought there were two (uncached or not) until you > came up with the migratable or non-migratable, which affects the > security properties. But now there's also potential for hardware > backing, like mktme, described by flags as well. I suppose you could > also use RDT to restrict which cache the data goes into: say L1 but not > L2 on to lessen the impact of fully uncached (although the big thrust > of uncached was to blunt hyperthread side channels). So there is > potential for quite a large expansion even though I'd be willing to bet > that a lot of the modes people have thought about turn out not to be > very effective in the field. Thanks for the insight. I remember that even the "uncached" parts was effectively nacked by x86 maintainers (I might be wrong). For the other parts, the question is what we actually want to let user space configure. Being able to specify "Very secure" "maximum secure" "average secure" all doesn't really make sense to me. The discussion regarding migratability only really popped up because this is a user-visible thing and not being able to migrate can be a real problem (fragmentation, ZONE_MOVABLE, ...). -- Thanks, David / dhildenb