Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751747AbaFECxC (ORCPT ); Wed, 4 Jun 2014 22:53:02 -0400 Received: from mail-we0-f181.google.com ([74.125.82.181]:59657 "EHLO mail-we0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750944AbaFECw6 (ORCPT ); Wed, 4 Jun 2014 22:52:58 -0400 MIME-Version: 1.0 In-Reply-To: <20140605003103.GB22052@wotan.suse.de> References: <1400589095-3872-1-git-send-email-mcgrof@do-not-panic.com> <1400589095-3872-13-git-send-email-mcgrof@do-not-panic.com> <1400687040.7272.28.camel@kazak.uk.xensource.com> <20140521230233.GA13289@wotan.suse.de> <1400753147.14637.10.camel@kazak.uk.xensource.com> <20140523232031.GA26450@wotan.suse.de> <1401269449.24800.7.camel@kazak.uk.xensource.com> <20140529232918.GG26450@wotan.suse.de> <20140601061547.GC16257@tango.0pointer.de> <20140605003103.GB22052@wotan.suse.de> Date: Wed, 4 Jun 2014 19:52:56 -0700 Message-ID: Subject: Re: [systemd-devel] [PATCH v5 12/14] autoconf: xen: enable explicit preference option for xenstored preference From: Cameron Norman To: "Luis R. Rodriguez" Cc: Lennart Poettering , luto@mit.edu, Keir Fraser , Ian Campbell , Tim Deegan , Ian Jackson , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, ebiederm@xmission.com, Jan Beulich , xen-devel@lists.xenproject.org, systemd-devel@lists.freedesktop.org, morgan@kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 4, 2014 at 5:31 PM, Luis R. Rodriguez wrote: > On Sun, Jun 01, 2014 at 08:15:47AM +0200, Lennart Poettering wrote: >> On Fri, 30.05.14 01:29, Luis R. Rodriguez (mcgrof@suse.com) wrote: >> >> > I'm cc'ing a few security folks as I'd appreciate review on the ideas here, >> > in particular that of a launcher idea on system to replace alternatives on the >> > ExecStart= line of a systemd service unit file, alternative ideas are of >> > course welcomed. I'm also Cc'ing systemd-devel as this subject was reviewed >> > a little while ago with nothing concrete being recommended but instead a few >> > options being now archived as possibilities. I'm looking for a bit wider >> > review of the approaches and recomendations. >> > >> > Some general background for non xen folks: old xen requires the launch of >> > a daemon which implements supports of the xenstore, which is the database >> > that xen uses for information about guests / dom0. There are two supported >> > daemons, xenstored (C version) and oxenstored (Ocaml version) but they do the >> > same thing. Right now old init lets you override which one you pick through >> > an environment variable on /etc/{sysconfig,default}/xencommons, the script >> > will use the appropriate on there. Systemd doesn't let you use variables on >> > the ExecStart line of a service unit file so alternatives are required. >> > >> > The reason I'm being very careful here this could set a precedent and at >> > least for the launcher idea it'd require the usage of getenv() and execve(), >> > and secure alternatives for these (secure_getenv(), execve_nosecurity()) >> > have either been merged or suggested before for Linux. The systemd discussion >> > is only specific to Linux but if we have a launcher we could consider it for >> > other supported OSes. All that said I'd like proper review of the security >> > implications of *all* strategies but obviously in particular the launcher >> > idea. I want to tread carefuly before setting precedents. >> >> You can also just invoke a shell script from ExecStart=. I mean, we try >> to deemphesize them in the boot process, but there's nothing wrong with >> using shell, if you need to parse shell configuraiton fragments and just >> want to execute on ot another program... > > I tried this and it didn't work given that systemd expects sd_notify() > to be called from the parent process, in this case the shell script. Just use exec before the daemon command. I am pretty certain it can be just like this: ExecStart=/bin/sh -c "exec $XENSTORED" xenstored then has the same PID as the sh process, and $NOTIFY_SOCKET works just fine. Best, -- Cameron -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/