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https://issues.apache.org/jira/browse/CASSANDRA-12859?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15728783#comment-15728783
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Boris Melamed commented on CASSANDRA-12859:
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Arguably, this is the ultimate goal.
Yet actually, the REVOKE direction is as user-unfriendly as initially planned,
after the above discussions, for both GRANT and REVOKE. But at least GRANT is
now more user-friendly than that.
In therms of coding, it's not a big effort to make REVOKE subtractive.
For now, would you agree to add the current functionality (pending review) to
the trunk, or do you consider this an 'all or nothing' situation?
Moreover, making REVOKE subtractive opens a can of worms.
As background, please see section "Some details on permission lifecycle and
precedence" in the attached 'v2' document.
Consider these potentially confusing cases, especially #2:
1. Last column gets subtracted
** GRANT SELECT(c1, c2) ON ks.t1 TO Joe; -- Joe can select c1 and c2 from t1
** REVOKE SELECT(c2) ON ks.t1 FROM Joe; -- Joe can select only c1 from t1
** REVOKE SELECT(c1) ON ks.t1 FROM Joe; -- What now?
After the last command, should Joe have access to all of t1, or should his
access to t1 get revoked altogether? I'm guessing the latter, but would like
this confirmed.
2. Subtracting a column that had not been added
** GRANT SELECT ON ks.t1 TO Joe; -- Joe can select all of t1
** REVOKE SELECT(c2) ON ks.t1 FROM Joe; -- What now?
After the REVOKE, should Joe have access to all of t1's columns except for c2?
This might be a natural expectation. However, we're not planning on introducing
black lists. We could 'fake it' by restricting the permission to all columns
except for c2, equivalent to (informally):
** GRANT SELECT(c1,c3,c4,...) ON ks.t1 TO Joe; -- Joe can select all of t1
except for c2
But then, Joe would not be able to access columns that got added afterwards.
So I would suggest that revoking columns that are not in the current permission
constraint should have no effect on permissions. But this may not follow a
user's intuition, and needs to be clearly documented.
In any case, I'm guessing that these other tasks should be the next in line,
before this feature can get into the product:
* LIST PERMISSIONS
* Purging of column constraints after dropping columns
> Column-level permissions
> ------------------------
>
> Key: CASSANDRA-12859
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12859
> Project: Cassandra
> Issue Type: New Feature
> Components: Core, CQL
> Reporter: Boris Melamed
> Labels: doc-impacting
> Attachments: Cassandra Proposal - Column-level permissions v2.docx,
> Cassandra Proposal - Column-level permissions.docx
>
> Original Estimate: 504h
> Remaining Estimate: 504h
>
> h4. Here is a draft of:
> Cassandra Proposal - Column-level permissions.docx (attached)
> h4. Quoting the 'Overview' section:
> The purpose of this proposal is to add column-level (field-level) permissions
> to Cassandra. It is my intent to soon start implementing this feature in a
> fork, and to submit a pull request once it’s ready.
> h4. Motivation
> Cassandra already supports permissions on keyspace and table (column family)
> level. Sources:
> * http://www.datastax.com/dev/blog/role-based-access-control-in-cassandra
> * https://cassandra.apache.org/doc/latest/cql/security.html#data-control
> At IBM, we have use cases in the area of big data analytics where
> column-level access permissions are also a requirement. All industry RDBMS
> products are supporting this level of permission control, and regulators are
> expecting it from all data-based systems.
> h4. Main day-one requirements
> # Extend CQL (Cassandra Query Language) to be able to optionally specify a
> list of individual columns, in the {{GRANT}} statement. The relevant
> permission types are: {{MODIFY}} (for {{UPDATE}} and {{INSERT}}) and
> {{SELECT}}.
> # Persist the optional information in the appropriate system table
> ‘system_auth.role_permissions’.
> # Enforce the column access restrictions during execution. Details:
> #* Should fit with the existing permission propagation down a role chain.
> #* Proposed message format when a user’s roles give access to the queried
> table but not to all of the selected, inserted, or updated columns:
> "User %s has no %s permission on column %s of table %s"
> #* Error will report only the first checked column.
> Nice to have: list all inaccessible columns.
> #* Error code is the same as for table access denial: 2100.
> h4. Additional day-one requirements
> # Reflect the column-level permissions in statements of type
> {{LIST ALL PERMISSIONS OF someuser;}}
> # When columns are dropped or renamed, trigger purging or adapting of their
> permissions
> # Performance should not degrade in any significant way.
> # Backwards compatibility
> #* Permission enforcement for DBs created before the upgrade should continue
> to work with the same behavior after upgrading to a version that allows
> column-level permissions.
> #* Previous CQL syntax will remain valid, and have the same effect as before.
> h4. Documentation
> *
> https://cassandra.apache.org/doc/latest/cql/security.html#grammar-token-permission
> * Feedback request: any others?
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