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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 E87F7C43441 for ; Mon, 19 Nov 2018 20:29:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B44FC20851 for ; Mon, 19 Nov 2018 20:29:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B44FC20851 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cyphar.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730762AbeKTGyb (ORCPT ); Tue, 20 Nov 2018 01:54:31 -0500 Received: from mx1.mailbox.org ([80.241.60.212]:42222 "EHLO mx1.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728938AbeKTGyb (ORCPT ); Tue, 20 Nov 2018 01:54:31 -0500 Received: from smtp2.mailbox.org (unknown [IPv6:2001:67c:2050:105:465:1:2:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx1.mailbox.org (Postfix) with ESMTPS id 1EE31497D9; Mon, 19 Nov 2018 21:29:10 +0100 (CET) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter04.heinlein-hosting.de (spamfilter04.heinlein-hosting.de [80.241.56.122]) (amavisd-new, port 10030) with ESMTP id mNbkx0gY0nFg; Mon, 19 Nov 2018 21:29:08 +0100 (CET) Date: Tue, 20 Nov 2018 07:28:57 +1100 From: Aleksa Sarai To: Christian Brauner Cc: ebiederm@xmission.com, linux-kernel@vger.kernel.org, serge@hallyn.com, jannh@google.com, luto@kernel.org, akpm@linux-foundation.org, oleg@redhat.com, viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, dancol@google.com, timmurray@google.com, linux-man@vger.kernel.org, Kees Cook Subject: Re: [PATCH v1 2/2] signal: add procfd_signal() syscall Message-ID: <20181119202857.k5zw742xjfrw677j@yavin> References: <20181119103241.5229-1-christian@brauner.io> <20181119103241.5229-3-christian@brauner.io> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="gtgc45ynebhhjwty" Content-Disposition: inline In-Reply-To: <20181119103241.5229-3-christian@brauner.io> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --gtgc45ynebhhjwty Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2018-11-19, Christian Brauner wrote: > + if (info) { > + ret =3D __copy_siginfo_from_user(sig, &kinfo, info); > + if (unlikely(ret)) > + goto err; > + /* > + * Not even root can pretend to send signals from the kernel. > + * Nor can they impersonate a kill()/tgkill(), which adds > + * source info. > + */ > + ret =3D -EPERM; > + if ((kinfo.si_code >=3D 0 || kinfo.si_code =3D=3D SI_TKILL) && > + (task_pid(current) !=3D pid)) > + goto err; > + } else { > + prepare_kill_siginfo(sig, &kinfo); > + } I wonder whether we should also have a pidns restriction here, since currently it isn't possible for a container process using a pidns to signal processes outside its pidns. AFAICS, this isn't done through an explicit check -- it's a side-effect of processes in a pidns not being able to address non-descendant-pidns processes. But maybe it's reasonable to allow sending a procfd to a different pidns and the same operations working on it? If we extend the procfd API to allow process creation this would allow a container to create a process outside its pidns. --=20 Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH --gtgc45ynebhhjwty Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEb6Gz4/mhjNy+aiz1Snvnv3Dem58FAlvzHQkACgkQSnvnv3De m58IwBAAgHKh2abQgnpam0GUxYiHi88rnCgkNIbQ9UCsmfE565c+gUSS9jmJxDmJ pbd3pdWcS1zZdRWC3mD75W6bYbnu0OEyKcJbjXXwR2+aK4Z98UJNtWtFPtFpny2T U38WVhtyJafQ8GgAQB7WN5SAloUIv8vbMoIlZw5FJzehmks8528fJq4L6zDdc+Cv xaB8Cn6MeWAyry5HM5534QTW4uAEdw0MQ8Q+n8H0tjbXPoJ9kLS7JsIbAm+VFTZJ Lc4jfnm5VUHkHfCnpurJHBYJTtl6EsumWDAeQPG6hcQ3aBDFRGoWQ3GbrmfRwtqi KQgy8SyVZ3RCxK9xJtW2keGMnLPxMaPNL1QWV9rlSPNhSzhbUupyYUKXnnjX9SD8 KG7V1bNv7CScO34o8gTCIv2wX1PVHRczZdbHTmx5aU78EFKFJmml+DdTR7QYUNb/ 4GvnRCMRSrsewabQKfOroLVkg0lmicPh6SMvGujsfd2QDEenzRWHU9QxHzecXfYl qH2Q/+LMa32WRLgG3/sVZLf4Pjy/UHHm/W4I9EkqWLrXjo/87wrMfWjxWCRdLDry ongYz/FLqY56phw1ZkCPICh2UF9sCdQ3fOowyGfTDmOlphSsMIuZWfeITOproXS1 OBL5DWnAtBVP/ZIye1ctHRFF98bak0hIAgvx0YphLHrX9lt5w9g= =Euc9 -----END PGP SIGNATURE----- --gtgc45ynebhhjwty--