On 5/17/11 1:17 PM, Alexander Leidinger wrote:
On Tue, 17 May 2011 12:56:40 -0700 Sean Bruno<sean...@yahoo-inc.com>
wrote:
Silly thing I ran into today. User wanted to NFS mount a dir inside a
jail. After I groaned about the security implication of this, I noted
that there is a sysctl that looks like it should allow this. Namely,
security.jail.mount_allowed. I noted that setting this follows a path
that *should* have allowed this silly thing to happen, except that the
credentials in the nfsclient were not setup correctly.
As you noticed, this is supposed to allow to mount inside a jail, IF
the FS you want to mount is marked as secure/safe to do so. Nearly no
FS is marked as such, as nobody wants to guarantee that it is safe
(root in a jail should not be able to panic a system by trying to
mount a corrupt/malicious FS-image) and secure (not possible to get
elevated access/privileges).
For NFS there is theoretically the problem that the outgoing address on
requests could be the one of the physical host instead of the IP of the
jail. If this is true in practice, I do not know. This could be
the reason why NFS is not marked with VFCF_JAIL.
a vimage jail would not have that problem if we've done it right.
Bye,
Alexander.
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