Re: [PATCH 02/11] libnvdimm/security: change clear text nvdimm keys to encrypted keys

[Dave Jiang]

On 11/11/2018 1:09 PM, Mimi Zohar wrote:
> > > Traditionally there is a single master key for the system, which would
> > > be sealed to a set of boot time PCR values.  After decrypting all of
> > > the encrypted keys, the master key would be removed from the keyring
> > > and a PCR extended.  Extending a PCR would prevent the master key from
> > > being unsealed again and used to decrypt encrypted keys, without
> > > rebooting the system.  Normally this would be done before pivoting
> > > root.
> > >
> > > If you're not referring to the system master key and are intentionally
> > > limiting usage to TPM 2.0, more details on the master key security
> > > requirements should be included.
> > Oh, interesting point. I think we had been assuming a local +
> > unsealed-at-runtime nvdimm master key rather than a system-wide master
> > key. Yes, we need to rethink this in terms of supporting a sealed
> > system-key. This would seem to limit security actions, outside of
> > unlock, to always requiring a reboot. I.e. the nominal case is that we
> > boot up and unlock the DIMMs, but any subsequent security operation
> > like erase, or change-passphrase would require rebooting into an
> > environment where the system-master key is unsealed. I do think
> > re-provisioning keys and erasing DIMM contents are sufficiently
> > exceptional events that a reboot requirement is tolerable.
> > Is there already existing tooling around this to be able to schedule
> > master-key related actions to be deferred to an initrd environment?
> There's the original dracut support for loading a masterkey, which is
> used by the EVM and ecryptfs dracut modules. ÂAfter the last usage,
> the masterkey needs to be removed from the keyring.

How does one generate new encrypted keys with the system masterkey 
removed from the keyring?


> Different people over the years have wanted to add support for
> calculating the boot time expected PCRs values in order to reseal keys
> (trusted key update), but I haven't looked to see if there are any
> open source tools available.
>
> Mimi