Re: NFS4 authentification / fsuid

Satyam Sharma
2007-09-18T23:42:21Z

On Thu, 6 Sep 2007, Kyle Moffett wrote:
>
> On Sep 06, 2007, at 19:35:14, Trond Myklebust wrote:
> >
> > On Thu, 2007-09-06 at 19:30 -0400, Kyle Moffett wrote:
> > >
> > > On Sep 06, 2007, at 11:06:16, J. Bruce Fields wrote:
> > > > The question of how to protect against someone with *physical*
^^^^^^^^^^^^^^^^^^^^^^^
> > > > access certainly is more difficult, but surely that's a separate
^^^^^^

> > > > problem.
> > >
> > > Actually, that's a fairly simple problem (barring disassembling the system
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

> > > and attaching a hardware debugger). You encrypt the root filesystem and
> > > require a password to boot (See: LUKS). Debian has built-in support for
> > > installing onto fs-on-LVM-on-crypt-on-RAID, and it works quite well on all
> > > the laptops I use regularly. It's not even much of a speed penalty; once
> > > you take the overhead of hitting a 5400RPM laptop drive you can chew
> > > thousands of cycles of CPU without anybody noticing (much). Then all you
> > > have to do is burn a copy of your /boot with bootloader onto some
> > > read-only media (like a finalized CDROM/DVDROM) and you're set to go.
> >
> > Disconnect battery, and watch boot password go 'poof!'.
>
> Umm, I did say "encrypt the root filesystem", didn't I? Booting my laptops
^^^^^^^

The whole *point* here is to secure against physical access -- then how
can you assume "barring disassembling the system"? If you're not
considering attacks such as those, then how _are_ you solving the
physical access problem in the first place? :-)

> this way follows this procedure:
> 1) Enter BIOS boot menu
> 2) Insert /boot CDROM
> 3) Select the "CDROM" entry
> 4) Wait for kernel to start and run through initramfs
> 5) Type password into the initramfs prompt so that it can DECRYPT THE ROOT
> FILESYSTEM
> 6) Continue to boot the system.
>
> Under this setup, tinkering with my BIOS does virtually nothing; the only
> avenues of attack are strictly of the "Install a hardware keylogger" variety.

Doesn't flashing/replacing your BIOS firmware/chip count as tinkering?
Then I don't really need a "hardware keylogger", do I ...