[dm-devel] encrypted filesystem not encrypted?

[chris]

Thank you both for your replies!

Thank you for the replies! I have learned a lot from this posting... I 
knew to seed a looped file with random data, but had not thought about 
seeding the device itself.

The basic commands that were (should have been) run were:

cryptsetup –-verbose –-verify-passphrase create sda3 /dev/sda3
pvcreate /dev/mapper/sda3
vgcreate loggroup /dev/mapper/sda3
lvcreate -L##G -n logvolume loggroup
mkfs.ext3 -j /dev/loggroup/logvolume
mount /dev/loggroup/logvolume /mount_point

I'm basically the Architect who came up with the process to run for the 
company, the S/A who setup the box actually ran the commands, the ones I 
delivered to him were to build out an encrypted filesystem ontop of an 
existing (loop). He made a change to them to use the actual device and 
they could have easily enough converted the commands to
pvcreate /dev/sda3, vgcreate loggroup /dev/sda3 and the rest doesn't 
matter, nothing would be encrypted.

I think the way I can prove this (please let me know if this has faults) 
is in tearing down (unmounting, and vgchange/lvchange) the filesystem 
and removing the cryptsetup... At that point the LVM should not 
recognize the loggroup as a valid LVM and therefore (vg/pv/lv)display 
wont display anything for the subject groups.... So, I think I am 
comfortable enough proving that we are (or are not) using the encryption 
that way.

What I think has happened was that these devices were in fact used 
previously, and we did not seed the devices with random data... I 
verified that with the S/A who ran the commands to setup the box.

The only reason we were looking at sda3 was to give the testers a way to 
make them feel better that the disk was in fact encrypting the data, are 
there better ways to ensure the data stored on the disk is in fact 
encrypted?

TIA again!

-chris

Ellison, Bob wrote:
> Also, did you initialize the partition with random data before the
> cryptsetup step? If not, you could be looking at stale, unencrypted
> data.
> e.g
>        dd if=/dev/urandom of=/dev/sda3 
>     or
>        /sbin/badblocks -c 10240 -s -w -t random -v /dev/sda3
>
> Either will do; the choice is how secure you want your actual data
> and/or how long you're willing to wait for the seeding to complete.
> --
> bob
>
> -----Original Message-----
> From: dm-devel-bounces at redhat.com [mailto:dm-devel-bounces at redhat.com]
> On Behalf Of Jonathan Brassow
> Sent: Wednesday, August 01, 2007 10:43 AM
> To: device-mapper development
> Subject: Re: [dm-devel] encrypted filesystem not encrypted?
>
> I'm guessing that you are bypassing your crypt device.  Depends on  
> what your arguments are to the LVM commands.
>
> cryptsetup will create a new device that sits on top of sda3 - you  
> should use that one.  Do not use sda3 directly.
>
>   brassow
>
> On Jul 31, 2007, at 8:08 PM, chris wrote:
>
>   
>> Hi all,
>>
>> I was not sure which list to send this to, so I choose a couple  
>> that looked like decent fits, please advise if there is one more  
>> specific to the encryption.
>>
>> I am currently working on a project where we are converting some of  
>> our filesystems to an encrypted fs using LVM2.  We are running  
>> RHEL:  "2.6.9-55.0.2.ELsmp #1 SMP Tue Jun 12 17:59:08 EDT 2007 i686  
>> i686 i386 GNU/Linux"
>>
>> We setup an encrypted filesystem using one of the open partitions  
>> on the physical hard drive using "cryptsetup create /dev/sda3"  We  
>> have verified this using the cryptsetup status, This shows the  
>> filesystem as being encrypted as aes_plain 256 bit key.  We then  
>> created an LVM and mounted the filesystem using the LVM.
>>
>> All seems to be well, except when our testers ran the following  
>> command:
>> head -c 5000 /dev/sda3
>>
>> They got some output that includes clear text and obviously not  
>> encrypted data (along with encrypted data).  Some things are date  
>> formatted strings like 20050912 which appears quite a few times in  
>> the mounted filesystem, and in the raw device (/dev/sda3).
>>
>> I can post the exact commands that were used to create the  
>> filesystem, but they are basically
>> create partition ...sda3
>> cryptsetup create /dev/sda3 (prompts for passphrase)
>> pvcreate
>> vgcreate
>> lvcreate
>> mount
>>
>> (TIA) any help (or light shed on this) is greatly appreciated!
>>
>> -chris
>>
>> --
>> dm-devel mailing list
>> dm-devel at redhat.com
>> https://www.redhat.com/mailman/listinfo/dm-devel
>>     
>
> --
> dm-devel mailing list
> dm-devel at redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>
> --
> dm-devel mailing list
> dm-devel at redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>