Date: Sat, 12 Mar 2016 09:42:33 -0700 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: <0ad738494152d249f3bbe3b722a46bd2@gritton.org> In-Reply-To: <c1e2fc0269e9de3a653d6e47da26b026@whitewinterwolf.com> References: <c1e2fc0269e9de3a653d6e47da26b026@whitewinterwolf.com>
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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. - Jamie
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