From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp1 ([2001:41d0:2:c151::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by ms11 with LMTPS id wNx2D0NxM2D0UgAA0tVLHw (envelope-from ) for ; Mon, 22 Feb 2021 08:54:27 +0000 Received: from aspmx2.migadu.com ([2001:41d0:2:c151::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp1 with LMTPS id UOE2C0NxM2ASDwAAbx9fmQ (envelope-from ) for ; Mon, 22 Feb 2021 08:54:27 +0000 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx2.migadu.com (Postfix) with ESMTPS id E7576279B6 for ; Mon, 22 Feb 2021 09:54:26 +0100 (CET) Received: from localhost ([::1]:57580 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lE6z3-00087v-Rs for larch@yhetil.org; Mon, 22 Feb 2021 03:54:25 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57528) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lE6yw-00087n-5u for guix-devel@gnu.org; Mon, 22 Feb 2021 03:54:18 -0500 Received: from fencepost.gnu.org ([2001:470:142:3::e]:50637) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lE6yu-0002Dq-9m; Mon, 22 Feb 2021 03:54:16 -0500 Received: from [2a01:e0a:1d:7270:af76:b9b:ca24:c465] (port=42000 helo=ribbon) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1lE6yt-0005mC-FC; Mon, 22 Feb 2021 03:54:15 -0500 From: =?utf-8?Q?Ludovic_Court=C3=A8s?= To: Maxime Devos Subject: Re: TOCTTOU race References: <87k0rrls0z.fsf@gnu.org> <08F0CD76-DDCF-4CFA-AE8D-5FB165A62B25@lepiller.eu> <87o8h2ehy7.fsf@gnu.org> <69968b3a01d872cabdf55a94b6c82d5057e010c9.camel@telenet.be> <87v9b66dm1.fsf@gnu.org> <56adb5efa894304c27beba99b07e2f8cfd8ee7cb.camel@telenet.be> <87zh0gzy52.fsf@gnu.org> <53c60ce40d68cfc93a9ea2c4a8f865026e12c889.camel@telenet.be> <87h7m9p8hd.fsf@gnu.org> X-URL: http://www.fdn.fr/~lcourtes/ X-Revolutionary-Date: 4 =?utf-8?Q?Vent=C3=B4se?= an 229 de la =?utf-8?Q?R?= =?utf-8?Q?=C3=A9volution?= X-PGP-Key-ID: 0x090B11993D9AEBB5 X-PGP-Key: http://www.fdn.fr/~lcourtes/ludovic.asc X-PGP-Fingerprint: 3CE4 6455 8A84 FDC6 9DB4 0CFB 090B 1199 3D9A EBB5 X-OS: x86_64-pc-linux-gnu Date: Mon, 22 Feb 2021 09:54:13 +0100 In-Reply-To: (Maxime Devos's message of "Fri, 19 Feb 2021 19:01:11 +0100") Message-ID: <87r1l8eb4a.fsf@gnu.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: guix-devel@gnu.org Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: "Guix-devel" X-Migadu-Flow: FLOW_IN X-Migadu-Spam-Score: -2.87 Authentication-Results: aspmx2.migadu.com; dkim=none; dmarc=pass (policy=none) header.from=gnu.org; spf=pass (aspmx2.migadu.com: domain of guix-devel-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=guix-devel-bounces@gnu.org X-Migadu-Queue-Id: E7576279B6 X-Spam-Score: -2.87 X-Migadu-Scanner: scn1.migadu.com X-TUID: vy2m8LjMEMmp Hi Maxime, Maxime Devos skribis: > On Thu, 2021-02-18 at 18:54 +0100, Ludovic Court=C3=A8s wrote: [...] >> Note that, if that happens at boot time, the system will fail to boot (I >> think you=E2=80=99d get a REPL rather than a kernel panic, but it=E2=80= =99d be good to >> check in a VM.) > > If that happens, that's too bad. Just ignoring the error seems bad from > a security perspective. I verified in a VM you'd get a REPL. > From the REPL, a sysadmin could investigate and choose to delete the offe= nding > symlink & reboot (and presumably fix the security bug and upgrade the ser= vice), > or decide Guix System needs to be reinstalled. OK, sounds reasonable. > Please take note that I didn't correct all potentially insecure activatio= n gexps. > These should ideally be done by someone who knows how to use the particul= ar service > and have a system to test it on. (My changes to nscld-service-type and k= not-activation > are untested.) I agree this is how it should happen ideally=E2=80=A6 let=E2=80=99s see if = things happen =E2=80=9Cideally=E2=80=9D. :-) > From 2c3968f658ada27d2062a960d229f3db9cfe208c Mon Sep 17 00:00:00 2001 > From: Maxime Devos > Date: Sun, 14 Feb 2021 12:57:32 +0100 > Subject: [PATCH] services: prevent following symlinks during activation ^ Nitpick: we usually capitalize here and in the commit log. Perhaps add a couple of lines explaining that this fixes a potential security issue, with a link to this thread. > Currently, there's a TOCTTOU race. This can be addressed > once guile has bindings for fstatat, openat and friends. I=E2=80=99d move that comment next to the =E2=80=98mkdir-p/perms=E2=80=99 d= efinition. > * guix/build/service-utils.scm: new module > with new procedure 'mkdir-p/perms'. I think you can remove these lines. > * Makefile.am (MODULES): compile new module. > * gnu/services/authentication.scm > (%nslcd-activation, nslcd-service-type): use new procedure. > * gnu/services/cups.scm (%cups-activation): likewise. > * gnu/services/dbus.scm (dbus-activation): likewise. > * gnu/services/dns.scm (knot-activation): likewise. LGTM for master, thanks! Ludo=E2=80=99.