XenAPI: Cached images are never re-used

[Bob Ball]

_create_cached_image_impl uses _find_cached_image to find the image - which in turn relies on the image name_label to be set. However, the bug is that at the end of _create_cached_image_impl the name_label is cleared - thus meaning the cached image is never re-used and always re-downloaded.

This has the dual effect of slowing down each server start which could have used the cached image and slowing down the "find_cached_image" function as it needs to search an ever larger number of VDIs.

[Bob Ball (bob-ball)]

Upgraded to critical due to the security implications - if two tenants start a server with the same base image, the second tenant will see all writes performed by the first tenant.

This is only in trunk, and not Havana.

[Brian Elliott (belliott)]

Nasty. Nice find!

[Thierry Carrez (ttx)]

Exploring security implications

[Thierry Carrez (ttx)]

https://review.openstack.org/#/c/58281/

[Russell Bryant (russellb)]

https://review.openstack.org/#/c/58281/

[Bob Ball (bob-ball)]

Fixed by https://review.openstack.org/#/c/58281/

Bug introduced in https://review.openstack.org/#/c/46706/ - which landed post-Havana

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/58281
Committed: http://github.com/openstack/nova/commit/a23371787d5cd6347d4afb10bb8abd0bd49dba1d
Submitter: Jenkins
Branch: master

commit a23371787d5cd6347d4afb10bb8abd0bd49dba1d
Author: Bob Ball <email address hidden>
Date: Mon Nov 25 13:06:45 2013 +0000

    XenAPI: Fix caching of images

    Clearing of the cached images' name_label means it can't be found in future.
    Name label of cloned VDI should be cleared so it is not found by the
    caching functions.

    Main impact of this is in test scenarios where the VM is always deleted, but
    a more subtle impact could be data leakage.

    Change-Id: I6bb80443d31128b7d5d47e4b252db5eb8ab86940
    Closes-bug: 1254714

[Thierry Carrez (ttx)]

No OSSA, does not appear in any supported version