[dm-crypt] security concerns with RAID on top of dmcrpyt and with mulitple devices with the same key slot key?

David Christensen dpchrist at holgerdanske.com
Fri Jun 3 06:36:47 CEST 2016

On 06/02/2016 08:14 PM, Christoph Anton Mitterer wrote:
> On Thu, 2016-06-02 at 19:41 -0700, David Christensen wrote:
>> If you put encryption on top of a RAID of N devices, your CPU will
>> have
>> to process one layer of encryption.  If you put a RAID on top of N
>> encrypted devices, your CPU will have to process N layers of
>> encryption.
> Well that's of course clear (I should have mentioned this),... but I
> cannot do the former with btrfs RAID, which in turn has the nice
> feature of being able to (try to) recover from silent block corruption
> (via the checksums), which MD RAID cannot.

Similarly, OpenZFS on encrypted volumes.

>> For stability, the kernel, device drivers, dm-crypt, LVM, btrfs,
>> etc.,
>> need to function correctly under concurrent workloads.  Choose your
>> software accordingly.
> Well...are there any current known issues in here? I used to remember
> that btrfs once had problems on top of dm-crypt, but that's long ago.

My laptop has Debian 7 (Wheezy) with btrfs root on LUKS on one SSD 
partition.  Both my kernel and btrfs versions are fairly old.  So, my 
btrfs is lacking features.  When I install btrfs-tools, it issues 
warnings about btrfs being under heavy development.  But, the laptop 
seems to work reliably.

You might want to dig through the bug reports for the various pieces on 
whatever Linux distribution and release you are considering.


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