Sharing directories with jails

Ean Kingston ean at
Thu Mar 3 08:03:55 PST 2005

> How dangerous is it to share the ports directory with jails on the
> system?  I am using the jails to give other access to a freebsd system.
>   You can assume they are untrusted (hence the jail ;)).
> Is it enough just to:
> ln -s /usr/ports /usr/jail/ajail/usr/ports

That won't work. The jail does a chroot (along with other things) when it
starts up so the link inside the jail will wind up pointing to itself.

The only way I've been able to figure out how to do something like that is
by running an NFS server outside the jail and then run an NFS client
inside the jail to get access to the disk space outside the jail via NFS.
I actually have a separate jail for the NFS server and export everything

Now, I'm sure you've thought of this but I'm going to say it for anyone
reading the archives. You do know that giving the jailed processes access
to anything outside the jail will reduce the security advantages of having
a jail in the first place?

Besides, why would you provide a jailed process with access to development
tools? You are just making it much easier for anyone with access to the
jail to build/install software to help them break out of the jail.

> Thanks
> Chris

Ean Kingston
    E-Mail: ean_AT_hedron_DOT_org
 PGP KeyID: 1024D/CBC5D6BB

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