bizarre mount_nullfs issue with jails / ezjail

[Mars G Miro]

On Wed, Apr 7, 2010 at 5:43 AM, Dan Naumov <dan.naumov at gmail.com> wrote:
> On Wed, Apr 7, 2010 at 12:37 AM, Glen Barber <glen.j.barber at gmail.com> wrote:
>> Hi Dan,
>>
>> Dan Naumov wrote:
>>> So, I want the basejail to only contain the world and link the ports
>>> tree from the host into each individual jail when it's time to update
>>> the ports inside them, but I am running into a bit of a bizarre issue:
>>> I can mount_nullfs /usr/ports elsewhere on the host just fine, but it
>>> doesn't work if I try to mount_nullfs it to /usr/ports inside the
>>> jail:
>>>
>>> mount_nullfs /usr/ports/ /usr/ports2
>>>
>>> df -H | grep ports
>>> cerberus/usr-ports                34G    241M     34G     1%    /usr/ports
>>> cerberus/usr-ports-distfiles      34G      0B     34G     0%
>>> /usr/ports/distfiles
>>> cerberus/usr-ports-packages       34G      0B     34G     0%
>>> /usr/ports/packages
>>> /usr/ports                        34G    241M     34G     1%    /usr/ports2
>>>
>>> mount | grep ports
>>> cerberus/usr-ports on /usr/ports (zfs, local)
>>> cerberus/usr-ports-distfiles on /usr/ports/distfiles (zfs, local)
>>> cerberus/usr-ports-packages on /usr/ports/packages (zfs, local)
>>> /usr/ports on /usr/ports2 (nullfs, local)
>>>
>>> mount_nullfs /usr/ports/ /usr/jails/semipublic/usr/ports
>>> mount_nullfs: /basejail: No such file or directory
>>>
>>> What is going on here? I also note that the error actually wants a
>>> /basejail on the host, which is even more bizarre:
>>>
>>> mount_nullfs /usr/ports/ /usr/jails/semipublic/usr/ports
>>> mount_nullfs: /basejail: No such file or directory
>>>
>>> mkdir /basejail
>>>
>>> mount_nullfs /usr/ports/ /usr/jails/semipublic/usr/ports
>>> mount_nullfs: /basejail/usr: No such file or directory
>>>
>>> Yet, this works:
>>>
>>> mkdir /usr/jails/semipublic/test
>>> mount_nullfs /usr/ports/ /usr/jails/semipublic/test
>>> umount /usr/jails/semipublic/test
>>>
>>> Any ideas?
>>>
>>>
>>
>> The ports directory in an ezjail is a link to /basejail/usr/ports (in the
>> jail).
>>
>> Breaking the link (from the host) allows the mount to work successfully.
>>
>> orion# ll usr/ports
>> lrwxr-xr-x  1 root  wheel  19 Mar  8 18:06 usr/ports -> /basejail/usr/ports
>> orion# unlink usr/ports
>> orion# mkdir usr/ports
>> orion# mount_nullfs /usr/ports usr/ports
>> orion#
>>
>> Regards,
>>
>> --
>> Glen Barber
>
> Thanks for the tip.
>
> An additional question: how come "sade" and "sysinstall" which are run
> inside the jail can see (and I can only assume they can also operate
> on and damage) the real underlying disks of the host?
>

Disks (as well as others you have in your host's /dev) aren't visible
inside jails.

> - Sincerely
> Dan Naumov
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-- 
cheers
mars
-----