On 2016-03-14 15:07, Mark Felder wrote:
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
Yeah, SYSV IPC has been a need for quite a while (a good deal longer
than I've been around). I'm a bit hesitant to put it in right now,
since it's apparently part of upcoming vimage work. But since the Posix
stuff is (virtually) path-based, it would seem a relatively simple thing
to put the jail path to use in keeping those IPC objects separate.
- Jamie
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