Re: setattr for vserver over NFS

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Hi Herbert,

so that is enabled by default on current code? I still mount with attr option just to use the barrier escape prevention
mechanism. I am out-dated with the recent changes...

Thanks,
- -Nik

On 12/14/2011 08:16 PM, Herbert Poetzl wrote:
> On Wed, Dec 14, 2011 at 09:14:24AM -0700, Dan Urist wrote:
>> Can you tell me (or give me a pointer to some docs) what
>> mechanism has replaced the barrier for chroot security?
> 
> mount/filesystem namespaces and pivot basically makes
> the barrier obsolete, as it shouldn't be possible to
> escape from a separate namespace.
> 
> best,
> Herbert
> 
>> On Wed, 14 Dec 2011 02:37:36 +0100
>> Herbert Poetzl <[email protected]> wrote:
> 
>>> On Tue, Dec 13, 2011 at 11:18:38AM -0700, Dan Urist wrote:
>>>> I have a number of vservers running on a Debian lenny host that
>>>> I'm planning to migrate to a squeeze host. The vservers' root
>>>> filesystems are on NFS shares from a netapp.
> 
>>>> I've followed the instructions to set the barrier attribute here:
>>>> http://linux-vserver.org/Secure_chroot_Barrier#Solution:_Secure_Barrier
> 
>>>> The problem I'm having is "setattr --barrier" doesn't appear to
>>>> do anything for the NFS filesystems, as reported by showattr
>>>> (it works for other vservers on ext3 filesystems, though).
>>>> I've tried this on both the lenny and the squeeze hosts, with
>>>> the filesystems mounted as both NFSv3 and NFSv4 (the netapp
>>>> supports both). I've also tried mounting the filesystems with
>>>> the "noac" option, which had no effect. Here are the package
>>>> versions for the squeeze host:
> 
>>>> linux-image-2.6.32-5-vserver-amd64
>>>> 2.6.32-39 util-vserver
>>>> 0.30.216-pre2864-2+b1 
> 
>>> the barrier is not implemented for NFS as NFS doesn't
>>> support xattr (which the barrier is based on) at all
> 
>>> but, with a recent kernel and recent util-vserver,
>>> you won't be needing the barrier anyway ...
> 
>>> note that I do not know if the debian kernel/tools
>>> are recent enough, so I'd suggest to ask the debian
>>> folks about this case.
> 
>>> HTH,
>>> Herbert
> 
>>>> Does anyone have any experience with running vservers over NFS?
> 
> 
>>>> -- 
>>>> Dan Urist
>>>> [email protected]
>>>> 303-497-2459
> 
> 
> 
>> -- 
>> Dan Urist
>> [email protected]
>> 303-497-2459
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