Details
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Task
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Status: Closed
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Major
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Resolution: Done
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Description
We want to support two different use cases for cell ACLs:
1. The user can see all cells in a table or CF unless a cell ACL denies access
2. The user cannot see any cells in a table or CF unless a cell ACL grants access
For the sake of flexibility we made it a toggle on an operation by operation basis. However this changed the behavior of the AccessController with respect to how requests for which a user has no grant at the table or CF level are handled. Prior to the cell ACL changes if a user had no grant at the table or CF level, they would see an AccessDeniedException. We can't do that if we want cell ACLs to provide exceptional access. Subsequent to the cell ACL changes if a user has no grant at the table or CF level, there is no exception, they simply won't see any cells except those granting exceptional access at the cell level. This also brings the AccessController semantics in line with those of the new VisibilityController.
Feedback on dev@ is this change is a bridge too far for at least three reasons. First, it is surprising (Enis and Vandana). Second, the audit trail is affected or missing (Enis). Third, it allows any user on the cluster to mount targeted queries against all tables looking for timing differences, that depending on schema design could possibly leak the existence in row keys of sensitive information, or leak the size of the table (Todd). Although we can't prevent timing attacks in general we can limit the scope of what a user can explore by restoring early-out access denial if the user has no access at the table or CF level.
We can make early-out access denial if the user has no access at the table or CF level configurable on a per table basis. Setting the default to "false", with a release note and paragraph in the security guide explaining how to reintroduce the old behavior, would address the above and not introduce another surprising change among 0.98 releases. If the consensus is (presumably a milder) surprise due to this change is fine, then the default could be "true"