Date: Tue, 22 Mar 2016 17:25:11 -0600 From: James Gritton <jamie@freebsd.org> To: freebsd-jail@freebsd.org Subject: Re: SHM objects cannot be isolated in jails, any evolution in future FreeBSD versions? Message-ID: <972dba829167a5fd824faf61663a3aae@gritton.org> In-Reply-To: <27abd17bc67680df02ef6d06f31d77be@whitewinterwolf.com> References: <c1e2fc0269e9de3a653d6e47da26b026@whitewinterwolf.com> <0ad738494152d249f3bbe3b722a46bd2@gritton.org> <1457989662.568170.549069906.791C2D05@webmail.messagingengine.com> <56E7C926.3020201@quip.cz> <27abd17bc67680df02ef6d06f31d77be@whitewinterwolf.com>
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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). - Jamie
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