Re: Non-superuser subscription owners

On 10/20/21 14:40, Mark Dilger wrote:
> These patches have been split off the now deprecated monolithic "Delegating superuser tasks to new security roles"
threadat [1].
 
>
> The purpose of these patches is to allow non-superuser subscription owners without risk of them overwriting tables
theylack privilege to write directly. This both allows subscriptions to be managed by non-superusers, and protects
serverswith subscriptions from malicious activity on the publisher side.
 
>
> [1] https://www.postgresql.org/message-id/flat/F9408A5A-B20B-42D2-9E7F-49CD3D1547BC%40enterprisedb.com


These patches look good on their face. The code changes are very
straightforward.


w.r.t. this:

+   On the subscriber, the subscription owner's privileges are
re-checked for
+   each change record when applied, but beware that a change of
ownership for a
+   subscription may not be noticed immediately by the replication workers.
+   Changes made on the publisher may be applied on the subscriber as
+   the old owner.  In such cases, the old owner's privileges will be
the ones
+   that matter.  Worse still, it may be hard to predict when replication
+   workers will notice the new ownership.  Subscriptions created
disabled and
+   only enabled after ownership has been changed will not be subject to
this
+   race condition.


maybe we should disable the subscription before making such a change and
then re-enable it?


cheers


andrew


--
Andrew Dunstan
EDB: https://www.enterprisedb.com