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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 7A6AAC10F03 for ; Tue, 23 Apr 2019 22:26:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F4A5206BA for ; Tue, 23 Apr 2019 22:26:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="JHvP3Qc4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726599AbfDWW0s (ORCPT ); Tue, 23 Apr 2019 18:26:48 -0400 Received: from mail-ua1-f65.google.com ([209.85.222.65]:34178 "EHLO mail-ua1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726075AbfDWW0s (ORCPT ); Tue, 23 Apr 2019 18:26:48 -0400 Received: by mail-ua1-f65.google.com with SMTP id c6so5377486uan.1 for ; Tue, 23 Apr 2019 15:26:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5wd3juuCyGv6I7aWGEczXK2I2MkaE+Yk5Y+BNpedQc0=; b=JHvP3Qc4kkkwAoF/0QYHWGplc3qsgSmh5NdB5v8VmADIDIKfxm29Zl03JyD4XVG9cK yzYYTUn+efgCCTi0FS+KzNAIgDktxEMhu5YO/Tot5RTlhcmQOOsrOxBqmB7so3nbTEBw AtVJmduRKOPMSxBxaCpYNVHVhvuORHcV1NhOQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5wd3juuCyGv6I7aWGEczXK2I2MkaE+Yk5Y+BNpedQc0=; b=fGMmj2z5a8rBpeBaD/2rvQeBSlHJWf7VgnmlvvXNQzOq0LjyX3LeRSgTlrBNRzVz3D giZuuHN7KW1oy/DM10OCVcXwh96ed0MEpqu3mLRaSBquLuiTy2OCnjNGR/OGvpb2rOGp iQDSNBgq1TSHtkd1Bq5ERB+O74xuepFSl2CEkHLHd9YhyP4Fkj/GzPWzpbSoqKjuREFh W7+mMVA73lEeW2Q78xrIKw+Ia85iwXoRFBgKXHyj4hJ8GRoEYYht5DfGskxr06K26kGZ f6EbaKj1x0Vg5R5jsNF12881H/Z81togHNCekosVfG2UcoKyjdkLPfatXUoYBhpWzrWV njgw== X-Gm-Message-State: APjAAAUhWoWsy9kjkrRbYM4Y5rMCjFWReIAakrkIIyh5ApMQ555PLiov NhG/F1C3VaKtdzOL1ezPdQVj9GIEAMs= X-Google-Smtp-Source: APXvYqx6gVldm0PI7D4fY51x4OxiEfSa9xbkyJkbVXciIkuDf+KVNYS0UXNel9WNbjpLclDgdlGICg== X-Received: by 2002:ab0:70d4:: with SMTP id r20mr3392117ual.67.1556058407039; Tue, 23 Apr 2019 15:26:47 -0700 (PDT) Received: from mail-vs1-f42.google.com (mail-vs1-f42.google.com. [209.85.217.42]) by smtp.gmail.com with ESMTPSA id m23sm25950191vsl.24.2019.04.23.15.26.46 for (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Tue, 23 Apr 2019 15:26:46 -0700 (PDT) Received: by mail-vs1-f42.google.com with SMTP id g127so9260176vsd.6 for ; Tue, 23 Apr 2019 15:26:46 -0700 (PDT) X-Received: by 2002:a67:f849:: with SMTP id b9mr14894109vsp.188.1556057966875; Tue, 23 Apr 2019 15:19:26 -0700 (PDT) MIME-Version: 1.0 References: <20190319030722.12441-1-peterx@redhat.com> <20190319030722.12441-2-peterx@redhat.com> <20190319110236.b6169d6b469a587a852c7e09@linux-foundation.org> In-Reply-To: <20190319110236.b6169d6b469a587a852c7e09@linux-foundation.org> From: Kees Cook Date: Tue, 23 Apr 2019 15:19:15 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 1/1] userfaultfd/sysctl: add vm.unprivileged_userfaultfd To: Andrew Morton Cc: Peter Xu , LKML , Paolo Bonzini , Hugh Dickins , Luis Chamberlain , Maxime Coquelin , Maya Gokhale , Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Denis Plotnikov , Linux-MM , Marty McFadden , Mike Kravetz , Andrea Arcangeli , Mike Rapoport , Kees Cook , Mel Gorman , "Kirill A . Shutemov" , Linux API , "linux-fsdevel@vger.kernel.org" , "Dr . David Alan Gilbert" Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Mar 19, 2019 at 11:02 AM Andrew Morton wrote: > > On Tue, 19 Mar 2019 11:07:22 +0800 Peter Xu wrote: > > > Add a global sysctl knob "vm.unprivileged_userfaultfd" to control > > whether userfaultfd is allowed by unprivileged users. When this is > > set to zero, only privileged users (root user, or users with the > > CAP_SYS_PTRACE capability) will be able to use the userfaultfd > > syscalls. > > Please send along a full description of why you believe Linux needs > this feature, for me to add to the changelog. What is the benefit to > our users? How will it be used? > > etcetera. As it was presented I'm seeing no justification for adding > the patch! Was there a v3 of this patch? I'd still really like to have this knob added. :) Thanks! -- Kees Cook