Stop encrypted disk on instance suspend/power off

Disconnecting dm-crypt device from an encrypted LVM volume while the instance
is suspended or powered off will secure user data from unauthorized access.
This will extend data at-rest protection provided by the LVM ephemeral storage
encryption feature.

Change-Id: I6070754d998abc73c8a2e03025700da71dcdafbe

specs/kilo/approved/stop-dmcrypt-on-suspend.rst

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+..
+ This work is licensed under a Creative Commons Attribution 3.0 Unported
+ License.
+
+ http://creativecommons.org/licenses/by/3.0/legalcode
+
+====================================================================
+Stop dm-crypt device when an encrypted instance is suspended/stopped
+====================================================================
+
+https://blueprints.launchpad.net/nova/+spec/stop-dmcrypt-on-suspend
+
+Disconnect the dm-crypt device from encrypted LVM volume when an
+instance with encrypted LVM ephemeral storage is suspended or powered off.
+
+
+Problem description
+===================
+
+The recently introduced LVM ephemeral storage encryption features secures
+user data at rest.  Current implementation makes user data unreadable after
+the instance has been terminated.  While the instance is active (e.g.,
+running, paused, suspended or powered off), on the compute host the data is
+readable only by the super-user.  This protection against unauthorized
+access can be strengthened further by disconnecting the dm-crypt device when
+an instance is suspended or powered off and flushing the encryption key from
+memory.  The dm-crypt device is what allows the encrypted data to be
+accessed in the clear so disconnecting it will render the data unreadable by
+anyone without the key.
+
+Use Cases
+---------
+
+An encrypted instance operating on sensitive data is stopped but not destroyed
+-- the work to be resumed later.
+
+Project Priority
+----------------
+
+None
+
+
+Proposed change
+===============
+
+The change will add code to stop the dm-crypt device and flush the key in
+libvirt.driver.power_off() and libvirt.driver.suspend() and code to retrieve
+instance ephemeral encryption key and restart the dm-crypt device in
+libvirt.driver.power_on() and libvirt.driver.resume().
+
+Alternatives
+------------
+
+There is no real alternative.
+
+Data model impact
+-----------------
+
+None
+
+REST API impact
+---------------
+
+None
+
+Security impact
+---------------
+
+User data will be inaccessible to anyone while the instance is powered off or
+suspended.
+
+Notifications impact
+--------------------
+
+None
+
+Other end user impact
+---------------------
+
+None
+
+Performance Impact
+------------------
+
+The power on and resume operations will be marginally slower for encrypted
+instances.
+
+Other deployer impact
+---------------------
+
+None
+
+Developer impact
+----------------
+
+None
+
+
+Implementation
+==============
+
+Assignee(s)
+-----------
+
+Primary assignee:
+  dgenin (Dan Genin)
+
+Work Items
+----------
+
+* Add dm-crypt stop/restart functionality to suspend()/resume().
+* Add dm-crypt stop/restart functionality to power_off()/power_on().
+
+
+Dependencies
+============
+
+None
+
+
+Testing
+=======
+
+Unit and Tempest tests will be written to verify correct operation of
+the proposed feature.
+
+
+Documentation Impact
+====================
+
+The extension of data-at-rest security to powered off and suspended instances
+should be mentioned in OpenStack Security Guide.
+
+
+References
+==========
+
+None