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[209.85.220.65]) by mx.google.com with SMTPS id d1sor49487lfk.53.2019.03.14.08.23.25 for (Google Transport Security); Thu, 14 Mar 2019 08:23:26 -0700 (PDT) Received-SPF: pass (google.com: domain of alexei.starovoitov@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=A04py3Qh; spf=pass (google.com: domain of alexei.starovoitov@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=alexei.starovoitov@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5TO12yM7WufkWFhciODab08c+uIiLHgK9xAYUtoPnjg=; b=A04py3QhidUEtRAHxPxTRn/F0L8fiHLfTcI3ptvIahJ4eXSUgKDbbwXsW91oGBQsfF S08CxrQDGCZasd03tij9Z3xNLDPJq3NpBSbEXuXr1bOTloe1Vfr1F/N8GNB1ZztJFcI6 2Jwv7i5eR5SHT7+T2ToYx6LSfA7+20TDZL1usrloJSIhi/tkSKCN4uRmDIN7XWyxwn4F GrKafH9Ov6adDQ5sqRFjDIyx2w4EJ+eRFiSXwoeJi+yy7x0UgHF6UNGuR3Xf4AUNYOed 2e0b982fIq3+EdGb3RynlzXo5hqDeuWVdGBZWVXhdZZsz8Y+Nin+76LA+ON3wpr1kHDi 8D0A== X-Google-Smtp-Source: APXvYqzRC8LBbbd9Z4o3g/WcEnkmCwELLtyDuivnnwdj+alwtyYDSvB1rYiuEwroOTFRphbRB16BnPKtUiqnNqtLyWU= X-Received: by 2002:ac2:4343:: with SMTP id o3mr8059614lfl.129.1552577005440; Thu, 14 Mar 2019 08:23:25 -0700 (PDT) MIME-Version: 1.0 References: <20190311093701.15734-1-peterx@redhat.com> <58e63635-fc1b-cb53-a4d1-237e6b8b7236@oracle.com> <20190313060023.GD2433@xz-x1> <3714d120-64e3-702e-6eef-4ef253bdb66d@redhat.com> <20190313185230.GH25147@redhat.com> <1934896481.7779933.1552504348591.JavaMail.zimbra@redhat.com> <20190313234458.GJ25147@redhat.com> <298b9469-abd2-b02b-5c71-529b8976a46c@redhat.com> In-Reply-To: <298b9469-abd2-b02b-5c71-529b8976a46c@redhat.com> From: Alexei Starovoitov Date: Thu, 14 Mar 2019 08:23:13 -0700 Message-ID: Subject: Re: [PATCH 0/3] userfaultfd: allow to forbid unprivileged users To: Paolo Bonzini Cc: Andrea Arcangeli , Peter Xu , Mike Kravetz , LKML , Hugh Dickins , Luis Chamberlain , Maxime Coquelin , kvm@vger.kernel.org, Jerome Glisse , Pavel Emelyanov , Johannes Weiner , Martin Cracauer , Denis Plotnikov , linux-mm , Marty McFadden , Maya Gokhale , Mike Rapoport , Kees Cook , Mel Gorman , "Kirill A . Shutemov" , Linux-Fsdevel , "Dr . David Alan Gilbert" , Andrew Morton , Daniel Borkmann Content-Type: text/plain; charset="UTF-8" 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 Thu, Mar 14, 2019 at 4:00 AM Paolo Bonzini wrote: > > On 14/03/19 00:44, Andrea Arcangeli wrote: > > Then I thought we can add a tristate so an open of /dev/kvm would also > > allow the syscall to make things more user friendly because > > unprivileged containers ideally should have writable mounts done with > > nodev and no matter the privilege they shouldn't ever get an hold on > > the KVM driver (and those who do, like kubevirt, will then just work). > > I wouldn't even bother with the KVM special case. Containers can use > seccomp if they want a fine-grained policy. > > (Actually I wouldn't bother with the knob at all; the attack surface of > userfaultfd is infinitesimal compared to the BPF JIT...). please name _one_ BPF JIT bug that affected unprivileged user space.