Date: Tue, 15 Mar 2016 09:34:46 +0100 From: Miroslav Lachman <000.fbsd@quip.cz> To: Mark Felder <feld@FreeBSD.org>, 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: <56E7C926.3020201@quip.cz> In-Reply-To: <1457989662.568170.549069906.791C2D05@webmail.messagingengine.com> References: <c1e2fc0269e9de3a653d6e47da26b026@whitewinterwolf.com> <0ad738494152d249f3bbe3b722a46bd2@gritton.org> <1457989662.568170.549069906.791C2D05@webmail.messagingengine.com>
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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
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