Re: [dm-crypt] FYI: how to (really) cleanly shutdown the system when root is on multiple stacked block devices

[Milan Broz <mbroz@redhat.com>]

On 06/27/2010 02:20 AM, markus reichelt wrote:
> * Arno Wagner<arno@wagner.name>  wrote:
>
>> Hmm. You know, encrypted root is a problem and pretty difficult to
>> do in the rfirt place. Why not just encrypt the critical parts,
>> like /var /home /root? The rest only holds binaries and config
>> files anyways, which are not that sensitive...
>
> Are you serious?

Usually encrypting everything is better, otherwise we add many problems here.

Just to randomly pick two of them:

- User must think and know which data are sensitive and avoid to copy them
to unencrypted space. It can happen even without his knowledge
- temporary file somewhere, coredump, whatever.  

- using "social engineering"
how many people will set the same password to disk encryption and
his account? If I have /etc/shadow visible, why I should bother
with attacking disc encryption with all its barriers?
I'll run dictionary search for passwords there, pretty good tools
already here.

...


I think that for laptop, encrypting everything is better. And I expect
that after clean shutdown my machine is safe.
All used tools currently providing methods how to do it properly
(I mean dm-crypt/LUKS, loop-aes or Truecrypt).

It is just about properly written init/shutdown scripts. I do not think it is
so complicated to fix it - just reverse initramfs root-fs mapping.

Several similar parts of problems "cutting own throat" are there
(like pvmove on root-fs in LVM, multipath solving the situation when all paths
to underlying device are temporarily gone).
This is nothing completely new.

(And yes, I a quite intentionally hijacked this thread to focus on this shutdown
& encrypted root-fs problem, sorry:-)

Milan