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=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 8FFB0C433F8 for ; Thu, 23 Jul 2020 17:30:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6AA6C20792 for ; Thu, 23 Jul 2020 17:30:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="YjrAHQwa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728600AbgGWRas (ORCPT ); Thu, 23 Jul 2020 13:30:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49186 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726666AbgGWRaq (ORCPT ); Thu, 23 Jul 2020 13:30:46 -0400 Received: from mail-io1-xd42.google.com (mail-io1-xd42.google.com [IPv6:2607:f8b0:4864:20::d42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65A17C0619DC for ; Thu, 23 Jul 2020 10:30:46 -0700 (PDT) Received: by mail-io1-xd42.google.com with SMTP id q74so7120929iod.1 for ; Thu, 23 Jul 2020 10:30:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=fBT1YHYehsULa5041VfTOXF4E/wfuVFEWswNl4qqheM=; b=YjrAHQwakysKhK/uMN8tazLEkVJfnT8KlS75mhdIZTrHekThF6A1QoO8LeE4KRYv79 9U1h+f8QxbfVSEa+wo1ooIRq90DsazR/yuqNMOI8KSbxYRocKc3EpZdFtK1mCmoj+SYX qMyenttxkX+IGflwu8drtiTgIVH8TdElCo2WxwbHaGnVHCN0Msrq0FVAYGe4mo0CelAr 7vFgE/ydE9PaZ9Yxfax14ep0ZIwgmfJYwhrtN2+39UjoQ2ssbqrZurbbKm1Hmx0P3/o3 wg7UQ6bicG8OaiG9dE0GW1aBhzJ7or5/NV9gOvfK2HquYLYsil1SutQ1nMBcqlTaNv1f +NpA== 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=fBT1YHYehsULa5041VfTOXF4E/wfuVFEWswNl4qqheM=; b=FHsaFXlRY1Pf7do2LMNTawwibWUMwK5jlY0MNsE0qqfJCV+89RLGIWGFMx7UphCdnq MtCsOO4EpSAIZM+HZPinn0z+7cDj3AI0/ELgxjjFEiDEJzHHudJgZmXQd/d2HyZicGJS EsOp29gZRADBR6PvxWzqV3mUB5/pMbMGB1sY4twPq3fLr4J68gpYPFh3JtxVpbvNja31 zO4hts+5M4lfyyFbCx6aw/40Wvzv61JUSVaJc6ZusW9lJ8H/vDLA0UmiUszPymaY4/Gk 8B4HiphsttZXSOHTW51fEhZgwqILCqKJLLinNF+tNBboNobnYXsRnzge5PhhOiVrw2Dn LW0w== X-Gm-Message-State: AOAM531IQJZGZUVo7usMOCCeJBjszaWJE5Mx8rkCZpYDJMli3gflV8WZ 7NH1JgwL4l7b/6G9yQVp1KI3uZ504IwEWVIoYohqCg== X-Google-Smtp-Source: ABdhPJyIqBAKndpkDTRooZU00sQLj+EJ2gNlhOJAdMucoDkJLrVRnPm5q0vLnqiwg56deW/zDgZDAJR/qbOzd/o3brw= X-Received: by 2002:a6b:bc41:: with SMTP id m62mr5742175iof.95.1595525445467; Thu, 23 Jul 2020 10:30:45 -0700 (PDT) MIME-Version: 1.0 References: <20200423002632.224776-1-dancol@google.com> <20200423002632.224776-3-dancol@google.com> <20200508125054-mutt-send-email-mst@kernel.org> <20200508125314-mutt-send-email-mst@kernel.org> <20200520045938.GC26186@redhat.com> <202005200921.2BD5A0ADD@keescook> <20200520194804.GJ26186@redhat.com> <20200520195134.GK26186@redhat.com> <20200520211634.GL26186@redhat.com> In-Reply-To: From: Lokesh Gidra Date: Thu, 23 Jul 2020 10:30:34 -0700 Message-ID: Subject: Re: [PATCH 2/2] Add a new sysctl knob: unprivileged_userfaultfd_user_mode_only To: Jeffrey Vander Stoep Cc: Andrea Arcangeli , Suren Baghdasaryan , Kees Cook , "Michael S. Tsirkin" , Daniel Colascione , Jonathan Corbet , Alexander Viro , Luis Chamberlain , Iurii Zaikin , Mauro Carvalho Chehab , Andrew Morton , Andy Shevchenko , Vlastimil Babka , Mel Gorman , Sebastian Andrzej Siewior , Peter Xu , Mike Rapoport , Jerome Glisse , Shaohua Li , linux-doc@vger.kernel.org, LKML , Linux FS Devel , Tim Murray , Minchan Kim , Sandeep Patil , kernel@android.com, Daniel Colascione , Kalesh Singh , Nick Kralevich Content-Type: text/plain; charset="UTF-8" Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Daniel, the original contributor of this patchset, has moved to another company. Adding his personal email, in case he still wants to be involved. >From the discussion so far it seems that there is a consensus that patch 1/2 in this series should be upstreamed in any case. Is there anything that is pending on that patch? On Fri, Jul 17, 2020 at 5:57 AM Jeffrey Vander Stoep wrote: > > On Wed, May 20, 2020 at 11:17 PM Andrea Arcangeli wrote: > > > > On Wed, May 20, 2020 at 01:17:20PM -0700, Lokesh Gidra wrote: > > > Adding the Android kernel team in the discussion. > > > > Unless I'm mistaken that you can already enforce bit 1 of the second > > parameter of the userfaultfd syscall to be set with seccomp-bpf, this > > would be more a question to the Android userland team. > > > > The question would be: does it ever happen that a seccomp filter isn't > > already applied to unprivileged software running without > > SYS_CAP_PTRACE capability? > > Yes. > > Android uses selinux as our primary sandboxing mechanism. We do use > seccomp on a few processes, but we have found that it has a > surprisingly high performance cost [1] on arm64 devices so turning it > on system wide is not a good option. > > [1] https://lore.kernel.org/linux-security-module/202006011116.3F7109A@keescook/T/#m82ace19539ac595682affabdf652c0ffa5d27dad > > > > > > If answer is "no" the behavior of the new sysctl in patch 2/2 (in > > subject) should be enforceable with minor changes to the BPF > > assembly. Otherwise it'd require more changes. > > Adding Nick (Jeff is already here) to respond to Andrea's concerns about adding option '2' to sysctl knob. > > Thanks! > > Andrea > >