From owner-freebsd-stable@freebsd.org Fri Jul 14 09:43:20 2017 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C79FCD9C893 for ; Fri, 14 Jul 2017 09:43:20 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 70CA3844AA for ; Fri, 14 Jul 2017 09:43:20 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.15.2/8.15.2) with ESMTPS id v6E9hEAJ028209 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 14 Jul 2017 12:43:15 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua v6E9hEAJ028209 Received: (from kostik@localhost) by tom.home (8.15.2/8.15.2/Submit) id v6E9hEkL028208; Fri, 14 Jul 2017 12:43:14 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Fri, 14 Jul 2017 12:43:14 +0300 From: Konstantin Belousov To: Dewayne Geraghty Cc: FreeBSD Stable Mailing List Subject: Re: Extended "system" attributes within jailed environment dont work Message-ID: <20170714094314.GT1935@kib.kiev.ua> References: <20170714075607.GQ1935@kib.kiev.ua> <3c08bee6-3f4e-e176-24b3-4b987188634f@heuristicsystems.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3c08bee6-3f4e-e176-24b3-4b987188634f@heuristicsystems.com.au> User-Agent: Mutt/1.8.3 (2017-05-23) X-Spam-Status: No, score=-2.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FREEMAIL_FROM,NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on tom.home X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 14 Jul 2017 09:43:20 -0000 On Fri, Jul 14, 2017 at 07:28:58PM +1000, Dewayne Geraghty wrote: > On 14/07/2017 5:56 PM, Konstantin Belousov wrote: > > On Fri, Jul 14, 2017 at 01:53:40PM +1000, Dewayne Geraghty wrote: > >> Can someone advise how I can enable extended attributes in a "system" > >> namespace within a jailed (or bhyve) environment? There was no guidance > >> in "man jail" nor "man jail.conf". > > Mentioning jails and bhyve in a single sentence clearly indicates serious > > issues with understanding either feature. > > Hmm. > > > > >> > >> Simple test > >> >From the host or base system: > >> # touch /a ; setextattr user t1 first /a ; getextattr user t1 /a > >> /a first > >> # touch /a ; setextattr system t2 second /a ; getextattr system t2 /a > >> /a second > >> > >> Within a jail: > >> # touch /a ; setextattr user t1 first /a ; getextattr user t1 /a > >> /a first > >> # touch /a ; setextattr system t2 second /a ; getextattr system t2 /a > >> setextattr: /a: failed: Operation not permitted > >> getextattr: /a: failed: Operation not permitted > >> > >> The impact of this is that SAMBA after 4.3 uses "system" namespace > >> extended attributes; hence can not provision an Active Directory within > >> a jailed environment. (For the inclined, this affects sysvol, and > >> interestingly "rsync -x" is unable to copy extended attributes, so > >> having consistent sysvols across a SAMBA domain may be a challenge) > > System namespace access is not allowed for jailed processes by design. > > See sys/kern/vfs_subr.c:extattr_check_cred() and a comment there > > explicitely mentioning the behaviour. The behaviour predates ~ year > > 2002, where extended attributes were introduced, and it makes sense. > > Thank-you for the pointer to the source. With the passage of 15 years > other applications have come to use "system" namespace extended > attributes, as though they were in the host system. Unfortunately if > you have one physical box available to act as both an authentication > server (Quasi Active Directory) and a fileserver, then using a jailed > environment is the only solution. > > By design? I suppose its akin to saying, why would you want to use > sysvipc from within a jail, with its global namespace (since FreeBSD > V5.0) ; or perhaps the use of raw sockets (FreeBSDv6.0); or mount within > a jail (FreeBSD V9.0); or...? > Probably because sophisticated use of jails is one of the many > outstanding features that sets FreeBSD apart from restrictive and > antiquated environments. Not all features of a base system should be > reflected in a jail, that would be silly; but where upstream > applications use features, then the enhancement of a jail's > configuration via way of, at least, an option - makes sense. Doesn't it? > > I suppose that the crux to the question is - why should the "system" > namespace not be available within a jail? Perhaps because system namespace (can) carry attributes which modify the filesystem behaviour in a way which is considered inappropriate to allow for jailed root. This is somewhat similar to jail security.allow_chflags knob, but with more unfortunate consequences. I do not claim that system namespace cannot be opened to the jailed root, but doing so requires a review of all implemented system ext attributes, across all types of filesystems. > > Aside: Someone on the SAMBA mailing list also using FreeBSD has a > similar problem, but he's using bhyve - hence the use within the same > sentence. This cannot be related, obviously. Bhyve is a hypervisor which runs a full instance of the kernel in VM, so again, claiming that the issue is same while mixing jails and bhyve is indicative.