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[209.132.183.28]) by mx.google.com with ESMTPS id z11si3391433qkz.141.2019.03.12.05.26.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 12 Mar 2019 05:26:48 -0700 (PDT) Received-SPF: pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of peterx@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=peterx@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6628759445; Tue, 12 Mar 2019 12:26:46 +0000 (UTC) Received: from xz-x1 (dhcp-14-116.nay.redhat.com [10.66.14.116]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 10A3A6684E; Tue, 12 Mar 2019 12:26:35 +0000 (UTC) Date: Tue, 12 Mar 2019 20:26:33 +0800 From: Peter Xu To: Mike Rapoport Cc: linux-kernel@vger.kernel.org, Paolo Bonzini , Hugh Dickins , Luis Chamberlain , Maxime Coquelin , kvm@vger.kernel.org, Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Denis Plotnikov , linux-mm@kvack.org, Marty McFadden , Maya Gokhale , Mike Kravetz , Andrea Arcangeli , Mike Rapoport , Kees Cook , Mel Gorman , "Kirill A . Shutemov" , linux-fsdevel@vger.kernel.org, "Dr . David Alan Gilbert" , Andrew Morton Subject: Re: [PATCH 1/3] userfaultfd/sysctl: introduce unprivileged_userfaultfd Message-ID: <20190312122633.GE14108@xz-x1> References: <20190311093701.15734-1-peterx@redhat.com> <20190311093701.15734-2-peterx@redhat.com> <20190312065830.GB9497@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190312065830.GB9497@rapoport-lnx> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 12 Mar 2019 12:26:47 +0000 (UTC) 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 Tue, Mar 12, 2019 at 08:58:30AM +0200, Mike Rapoport wrote: [...] > > +config USERFAULTFD_UNPRIVILEGED_DEFAULT > > + string "Default behavior for unprivileged userfault syscalls" > > + depends on USERFAULTFD > > + default "disabled" > > + help > > + Set this to "enabled" to allow userfaultfd syscalls from > > + unprivileged users. Set this to "disabled" to forbid > > + userfaultfd syscalls from unprivileged users. Set this to > > + "kvm" to forbid unpriviledged users but still allow users > > + who had enough permission to open /dev/kvm. > > I'd phrase it a bit differently: > > This option controls privilege level required to execute userfaultfd ^ +---- add " the default"? > system call. > > Set this to "enabled" to allow userfaultfd system call from unprivileged > users. > Set this to "disabled" to allow userfaultfd system call only for users who > have ptrace capability. > Set this to "kvm" to restrict userfaultfd system call usage to users with ^ add " who have ptrace capability, or" -------+ > permissions to open "/dev/kvm". I think your version is better than mine, but I'd like to confirm about above two extra changes before I squash them into the patch. :) Thanks! -- Peter Xu