[dm-crypt] verity setup on active device.

Shivaramakrishnan Vaidyanathan shivaramakrishnan740 at gmail.com
Sun Apr 6 00:11:58 CEST 2014


Thanks Milan for your reply.
I have few questions is this regard.I am ready to perform the offline
integrity check.I can have the image files in the nfs-share archived live
to another partition that is not mounted.Will I be able to perform the
integrity check at the block level in this case?Each time virtual machine
boots up,I need to be able to verify if the image was the same as previous
boot.
Is this achievable?

Will these steps work?
1. Image file (VM1 - Virtual hard disk file mounted in nfs share
partition).
2.I rsync the directory of nfs-share to another partition.
3.Then whether I will be able to tell whether the virtual image file has
been altered/changed from the previous boot?

Can you please provide some details in regard to the implementations
required in this case?

If you know any other alternatives,It would be great if you could share
it.Also I dont get the notion "Dm-verity was designed to provide verification
of (read-only) device (to provide verified boot path), all IOs must go
through dm-verity."

So what does this mean?


On Sat, Apr 5, 2014 at 2:39 PM, Milan Broz <gmazyland at gmail.com> wrote:

> On 04/04/2014 11:34 PM, Shiva wrote:
> ...
> > 5.Used the root hash in this command.
> > veritysetup --debug create nfs /dev/sdb /dev/sdc "root hash"
> >
> > Everything works well.
> > My problem is I am not able to perform step5 for a mounted partition.
> >
> > I require a mounted partition since nfs-share will use this partition.
> > (For addition and deletion)
> >
> > Is there a command switch that needs to be performed in order to achieve
> this?
>
> I am afraid this is not possible. Dm-verity was designed to provide
> verification of (read-only) device (to provide verified boot path),
> all IOs must go through dm-verity.
> (So it must be in the stack from the beginning).
>
> You cannot just add it later or run it parallel with mounted partition.
> And how this can work if some data are already in page/fs cache?
>
> Milan
>
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