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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B10AC77B60 for ; Fri, 28 Apr 2023 15:34:46 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B05D96B0080; Fri, 28 Apr 2023 11:34:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id AB5C06B0081; Fri, 28 Apr 2023 11:34:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 97DA56B0082; Fri, 28 Apr 2023 11:34:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 8839B6B0080 for ; Fri, 28 Apr 2023 11:34:45 -0400 (EDT) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 372711A028F for ; Fri, 28 Apr 2023 15:34:45 +0000 (UTC) X-FDA: 80731197330.06.9A4BC1B Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf14.hostedemail.com (Postfix) with ESMTP id 94C9D10002C for ; Fri, 28 Apr 2023 15:34:42 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=TQN0QZcY; spf=pass (imf14.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1682696082; h=from:from:sender: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:dkim-signature; bh=i1I3bxKpOJ94ZKtbze6sl4BqpXL9nzWwU/RAx5bKUL4=; b=n+EKQBh0Y0T9tHeIrFTgp9NjHQR6tSWfXL9AE5V6Mg41Os2nzd4dUDmty0nPVUF5gNLI3+ tbYbyDFMGz+cu/9y5Zyx9bVRxbJwb3h8W287NyOG0McQKzcf2UhUCZYNvhWS6IA9flzhIB mdKIXDGZ2H0ot5Efjf7F/ANtYCGDL0w= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=TQN0QZcY; spf=pass (imf14.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1682696082; a=rsa-sha256; cv=none; b=YAet6JVu9QF87grRxpaeEW947oD5PvbBDbnkFMiTmPC0L9SIPAj8MktyZV8qNCRNJMyUB4 xTMDr7vZI8/jglFdK1kiob73RYD6niOM2uPC4Fo0iJ7LwQ/744QYvVj/Ts45x2kTF0YXyz AOB+J4SyWeqPytnhYQNlG0K0PLm5E2A= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682696081; 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=i1I3bxKpOJ94ZKtbze6sl4BqpXL9nzWwU/RAx5bKUL4=; b=TQN0QZcYyJMDEh33ESJbF+b3tlF1o5gTCZZDLKkjQx+mnxIRS47oX650LWB7KFTGGNUVT0 09FRjfSX+x6RuR2vaWFdeibtwBELvmplAX+iWsPtz9Qu73omzkpSe/vDpJ2BiJXcnSVB0e pnoEidHowuzsWHr2M1aojGXXwbUtHsY= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-336-M6OVE26OOhubOyzfwUXemw-1; Fri, 28 Apr 2023 11:34:40 -0400 X-MC-Unique: M6OVE26OOhubOyzfwUXemw-1 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-3f250e9e090so23293225e9.0 for ; Fri, 28 Apr 2023 08:34:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1682696079; x=1685288079; h=content-transfer-encoding:in-reply-to:organization:from:references :cc:to:content-language:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=i1I3bxKpOJ94ZKtbze6sl4BqpXL9nzWwU/RAx5bKUL4=; b=Dc1hOjJSA4V1yDpNTUM2188F09e41w1HoJnxhP5jTSKuGphry3oV4LN8px3x3oZsUf c5+NBG0vy8dvwVwLay5yUeSVuczujzyD73eVPtVyS09I2jEGZXuGmzBYoZDrhKW6J/UC QUCDbu9mh0LFSrwfBYMJ3D8Biy/pwaZy2+j8zkThREuOLaIBGhqbC5Mf9Z9UYF5aeK7L KFeReU9EG35xBgr2YHkrGSbsx/b5e1psuGwM69IpDDw+HXiWZrnezqBSbpmX6yOBZkFt 8MWvJLQN5CaURS7PKzIjGeLCKIazkIn93EiVqOYfXMNYbs9mIXc2LeIiYlNsuTICifdx hV6w== X-Gm-Message-State: AC+VfDzWWxKeoiiWKhneiMQNoZUBGNIqaI2yxGfUjDPJ+mYHHlcLXQaP tb/XSIzi+aOKXeh8KfXxFkjm6xLNUpzMnggbiuO8liv5yEz/VBaPEk78f2qBBL0OrmzbO9Go3q0 xdzmPSkkGkvU= X-Received: by 2002:a7b:c408:0:b0:3f1:643e:3872 with SMTP id k8-20020a7bc408000000b003f1643e3872mr4562558wmi.2.1682696079112; Fri, 28 Apr 2023 08:34:39 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ6Z+53Bygi3DB3brEFB63AzkuIarkk5LoZoC423ssWGGEMwrQKBO68KVGzpDBEWIV0h6613fA== X-Received: by 2002:a7b:c408:0:b0:3f1:643e:3872 with SMTP id k8-20020a7bc408000000b003f1643e3872mr4562508wmi.2.1682696078744; Fri, 28 Apr 2023 08:34:38 -0700 (PDT) Received: from ?IPV6:2003:cb:c726:9300:1711:356:6550:7502? (p200300cbc72693001711035665507502.dip0.t-ipconnect.de. [2003:cb:c726:9300:1711:356:6550:7502]) by smtp.gmail.com with ESMTPSA id g9-20020a05600c000900b003f0aa490336sm27987597wmc.26.2023.04.28.08.34.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 28 Apr 2023 08:34:38 -0700 (PDT) Message-ID: <62ec50da-5f73-559c-c4b3-bde4eb215e08@redhat.com> Date: Fri, 28 Apr 2023 17:34:35 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v5] mm/gup: disallow GUP writing to file-backed mappings by default To: Lorenzo Stoakes Cc: Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Jens Axboe , Matthew Wilcox , Dennis Dalessandro , Leon Romanovsky , Christian Benvenuti , Nelson Escobar , Bernard Metzler , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Bjorn Topel , Magnus Karlsson , Maciej Fijalkowski , Jonathan Lemon , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Christian Brauner , Richard Cochran , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , linux-fsdevel@vger.kernel.org, linux-perf-users@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Oleg Nesterov , John Hubbard , Jan Kara , "Kirill A . Shutemov" , Pavel Begunkov , Mika Penttila , David Howells , Christoph Hellwig References: <6b73e692c2929dc4613af711bdf92e2ec1956a66.1682638385.git.lstoakes@gmail.com> <094d2074-5b69-5d61-07f7-9f962014fa68@redhat.com> <400da248-a14e-46a4-420a-a3e075291085@redhat.com> <077c4b21-8806-455f-be98-d7052a584259@lucifer.local> From: David Hildenbrand Organization: Red Hat In-Reply-To: <077c4b21-8806-455f-be98-d7052a584259@lucifer.local> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 94C9D10002C X-Stat-Signature: o5tcqijugn7fm93sbsfpx5yt8gujtdch X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1682696082-566040 X-HE-Meta: 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 i3xjL1fx ljMiWADMFjTbBXNU/AbSksS2Nxx1TzoRDPxJv602DhFcHKrmUBSw6oPr12TSOgKBO8B8m55ScsSoDsVilPJupfDeC+uCFf5oBg+TIutcQFpz95a2J3JUFzTIT9FZ81i7mG5PbbsiHKPNgvu9cVceDCfzCAvoeM3mzBPSrTCto2ghQearXGb+ZBD+hwXiRgoLvlaPj9y0fLDtZyboaeZtsbmIDxobng06ySLeCDYFq2yA7XI2NTmDIzPFyNQTeTeTQ+spfYpbSiKY2SAl86fsOJRLCV0zgXaN/AxPd9xQv6E9s4FmZAMAOJbcVsjcGJRdmxqlyCPeHSWbM4/JtfF0u70UrakmdED8RAhEV8rnU6RlLkAEVBK5MBzmeQYJkUleIbWKOPwr1Cs3bYT+QxgS9PTfv0IpK+QJTMIyujWDbSOBRiG937oDXKovXB6TW3lg18k8eiiSZ1oLjcLk= 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 28.04.23 17:33, Lorenzo Stoakes wrote: > On Fri, Apr 28, 2023 at 05:23:29PM +0200, David Hildenbrand wrote: >>>> >>>> Security is the primary case where we have historically closed uAPI >>>> items. >>> >>> As this patch >>> >>> 1) Does not tackle GUP-fast >>> 2) Does not take care of !FOLL_LONGTERM >>> >>> I am not convinced by the security argument in regard to this patch. >>> >>> >>> If we want to sells this as a security thing, we have to block it >>> *completely* and then CC stable. >> >> Regarding GUP-fast, to fix the issue there as well, I guess we could do >> something similar as I did in gup_must_unshare(): >> >> If we're in GUP-fast (no VMA), and want to pin a !anon page writable, >> fallback to ordinary GUP. IOW, if we don't know, better be safe. > > How do we determine it's non-anon in the first place? The check is on the > VMA. We could do it by following page tables down to folio and checking > folio->mapping for PAGE_MAPPING_ANON I suppose? PageAnon(page) can be called from GUP-fast after grabbing a reference. See gup_must_unshare(). > >> >> Of course, this would prevent hugetlb/shmem from getting pinned writable >> during gup-fast. Unless we're able to whitelist them somehow in there. > > We could degrade those to non-fast assuming not FOLL_FAST_ONLY. But it'd be > a pity. -- Thanks, David / dhildenb