castellan/releasenotes/notes/support-legacy-fixed-key-id-9fa897b547111610.yaml
Alan Bishop fc0fc79eb6 Support handling legacy all-zeros key ID
This patch addresses a specific use case, where a user has encrypted
volumes based on the fixed_key used by Cinder's and Nova's
ConfKeyManager. The user wishes to switch to Barbican, but existing
volumes must continue to function during the migration period.

The code conditionally adds a shim around the backend KeyManager when
both of these conditions are met:

1) The configuration contains a fixed_key value. This essentially
   signals the ConfKeyManager has been in use at one time
2) The current backend is *not* the ConfKeyManager

When the shim is active, a MigrationKeyManager class is dynamically
created that extends the backend's KeyManager class. The
MigrationKeyManager exists solely to override two functions:

o The KeyManager.get() function detects requests for the secret
  associated with the fixed_key, which is identified by an all-zeros
  key ID.

  - Requests for the all-zeros key ID are handled by mimicing the
    ConfKeyManager's response, which is a secret derived from the
    fixed_key.
  - Requests for any other key ID are passed on to the real backend.

o The KeyManager.delete() function is similar:

  - Requests to delete the all-zeros key ID are essentially ignored,
    just as is done by the ConfKeyManager.
  - Requests to delete any other key ID are passed on to the real
    backend.

All other KeyManager functions are not overridden, and will therefore be
handled directly by the real backend.

SecurityImpact
Change-Id: Ia5316490201c33e23a4206838d5a4fb3dd00f527
2017-11-21 09:23:09 -05:00

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YAML

---
features:
- |
Enhance the key manager to handle requests containing the special (all
zeros) managed object ID associated with Cinder's and Nova's legacy
ConfKeyManager. The purpose of this feature is to help users migrate from
the ConfKeyManager to a modern key manager such as Barbican. The feature
works by ensuring the ConfKeyManager's all-zeros key ID continues to
function when Barbican or Vault is the key manager.