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From: Klavs Klavsen (klavs_at_EnableIT.dk)
Date: Tue 05 Nov 2002 - 08:47:33 GMT

On Mon, 2002-11-04 at 22:47, Lars Braeuer wrote:
> can anyone tell me how it can be possible for a vserver
> admin to break out of the vserver, when the directory
> containing the vserver has any other mode than 000 ?

in short: chroot (which is what vserver is based upon) is only safe,
when the user does not obtain root in the chroot jail.

you can also read some more abstract information of the value of chroot
and other solutions etc.

> or should the permissions be set for the dir of the actual vserver
> (/vserver/x/.) instead of the directory containing the vservers
> (/vserver/x/..) ?
it's /vservers that needs to be chmod 000 /vservers. The reason for that
is that the way the chroot problem has been fixed is that the kernel
checks for the access rights being 000, and if they are - even root are
not allowed to progress beyond them.

I'm not sure, if this means that root in one vserver, can actually enter
another because it's not chmod 000'ed - if he can guess the vserver
name? Anyone can answer that?

Klavs Klavsen

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