Re: Rooting FreeBSD , Privilege Escalation using Jails (P�tur)

[Chris Rees]

On 7 May 2011 23:31, Jamie Landeg Jones <jamie at bishopston.net> wrote:
>> All the same, I've sent a PR [1] with some doc patches to make people
>> more aware of this -- fulfilling my promise of 2+ years ago :S
>>
>> Thanks!
>>
>> Chris
>>
>> [1] http://www.freebsd.org/cgi/query-pr.cgi?pr=156853
>
> Um. Some problems here.
>
> A jail won't work for not-root users if the jail root directory is chmod 700 - although
> there is obviously a 'chroot' running withing the jail, the jailed user still needs
> to have read permission from the hosts / -- chmod 700 therefore locks all non-root
> users out.
>
> I would suggest you add to the docs about the UID clash problem - untrusted users on the host
> shouldn't have the same UID/GID as jailed users, as they will have access to their files.
>
> And of course, the bit mentioned earlier where an untrusted jail user with jail-root access
> should NEVER have access to the host!o
>
> Among other things, my password file in both jails and the host has this line:
>
> # 8000 to 9999  -  Reserved for use within jails - do not use in main host!
>

Thanks!

Updated the patches about chmodding (d'oh), and I'll send another
later about UIDs.

Chris