Date: Wed, 23 Mar 2016 10:16:11 +0100 From: Miroslav Lachman <000.fbsd@quip.cz> To: James Gritton <jamie@freebsd.org>, freebsd-jail@freebsd.org Subject: Re: SHM objects cannot be isolated in jails, any evolution in future FreeBSD versions? Message-ID: <56F25EDB.1090408@quip.cz> In-Reply-To: <972dba829167a5fd824faf61663a3aae@gritton.org> References: <c1e2fc0269e9de3a653d6e47da26b026@whitewinterwolf.com> <0ad738494152d249f3bbe3b722a46bd2@gritton.org> <1457989662.568170.549069906.791C2D05@webmail.messagingengine.com> <56E7C926.3020201@quip.cz> <27abd17bc67680df02ef6d06f31d77be@whitewinterwolf.com> <972dba829167a5fd824faf61663a3aae@gritton.org>
next in thread | previous in thread | raw e-mail | index | archive | help
James Gritton wrote on 03/23/2016 00:25: > On 2016-03-17 05:54, Simon wrote: >> Le 2016-03-15 09:34, Miroslav Lachman a écrit : >>> Mark Felder wrote on 03/14/2016 22:07: >>>> >>>> >>>> On Sat, Mar 12, 2016, at 11:42, James Gritton wrote: >>>>> On 2016-03-12 04:05, Simon wrote: >>>>>> The shm_open()(2) function changed since FreeBSD 7.0: the SHM objects >>>>>> path are now uncorrelated from the physical file system to become >>>>>> just >>>>>> abstract objects. Probably due to this, the jail system do not >>>>>> provide >>>>>> any form of filtering regarding shared memory created using this >>>>>> function. Therefore: >>>>>> >>>>>> - Anyone can create unauthorized communication channels between >>>>>> jails, >>>>>> - Users with enough privileges in any jail can access and modify any >>>>>> SHM objects system-wide, ie. shared memory objects created in any >>>>>> other jail and in the host system. >>>>>> >>>>>> I've seen a few claims that SHM objects were being handled >>>>>> differently >>>>>> whether they were created inside or outside a jail. However, I tested >>>>>> on FreeBSD 10.1 and 9.3 but found no evidence of this: both version >>>>>> were affected by the same issue. >>>>>> >>>>>> A reference of such claim: >>>>>> https://lists.freebsd.org/pipermail/freebsd-ports-bugs/2015-July/312665.html >>>>>> >>>>>> >>>>>> My initial post on FreeBSD forum discussing the issue with more >>>>>> details: https://forums.freebsd.org/threads/55468/ >>>>>> >>>>>> Currently, there does not seem to be any way to prevent this. >>>>>> >>>>>> I'm therefore wondering if there are any concrete plans to change >>>>>> this >>>>>> situation in future FreeBSD versions? Be able to block the currently >>>>>> free inter-jail SHM-based communication seems a minimum, however such >>>>>> setting would also most likely prevent SHM-based application to work. >>>>>> >>>>>> Using file based SHM objects in jails seemed a good ideas but it does >>>>>> not seem implemented this way, I don't know why. Is this planned, or >>>>>> are there any greater plans ongoing also involving IPC's similar >>>>>> issue? >>>>> >>>>> There are no concrete plans I'm aware of, but it's definitely a thing >>>>> that should be done. How about filing a bug report for it? You've >>>>> already got a good write-up of the situation. >>>>> >>>> >>>> Both this and SYSV IPC jail support[1] are badly needed. >>>> >>>> [1] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=48471 >>> >>> Yes, it is very sad that original patch was not commited, nor >>> commented or improved by core developers for long 13 years. I am not >>> 100% sure but I thing there was some patch from PJD for SysV IPC too. >>> There were EclipseBSD with resource limits in times of FreeBSD 3.4 and >>> there is FreeVPS for 6.x with virtualized IPC... >>> >>> So I really hope SysV IPC aware jails will become reality soon. >>> >>> Miroslav Lachman >> >> Hi everyone, >> >> Odd thing, I've seen that the very first exchanges which opened this >> mailing list back in 2007 precisely discussed IPC isolation in Jail >> and some work already done in the Jail2 project part of the now >> abandoned FreeVPS project. At that time IPC virtualization was >> qualified as an easy job: >> >>> As say about SYSV IPC stuff you say about only virtualization? or >>> also about limits? "virtualization" is easy, but for limits - need more >>> work >> (https://lists.freebsd.org/pipermail/freebsd-jail/2007-May/000004.html) >> >> We have now come full circle :). >> >> As per the SHM objects issue, I've now filled a new bug #208082: >> https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=208082 >> >> I explain in the bug description why it may be different than the >> already existing bug #48471 covering SysV IPC. >> >> Le 2016-03-17 01:10, Dewayne Geraghty a écrit : >>> PS We don't want/need the complexity (or performance hit) associated >>> with v* additions when a well thought out (simple) jail does the task >>> very nicely :) >> >> I agree, the main advantage of jails and other lightweight containers >> is precisely their lightness. >> >> Regards, >> Simon. > > I've put a diff on the bug report (Bug 208082), for the shm objects, and > also for ksem and mqueue which have the same problems. Any review is > welcome :-). > > SYSV IPC is a separate issue. I'm following up with bz about my memory > of hearing there's something vimage-related there, and if there isn't I > can jump into that one as well (I actually have some work already done > with it, so it just needs a little more). I am more interested in SysV IPC (needed to run PostgreSQL in jails) but working SHM is good starting point. I really appreciate all your work on improving jails! Thank you for this great news :) Miroslav Lachman
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?56F25EDB.1090408>