[TRAFODION-2599] Restrict who can do EXPLAIN

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: any
• Component/s: sql-cmp, sql-security
• Assignee: Unassigned
• Reporter: Dave Birdsall
• Created: 26/Apr/17 22:26
• Updated: 27/Apr/17 23:17

Description

JIRA TRAFODION-2294 will fix a security hole in EXPLAIN: One can do an EXPLAIN of a query, then execute the query because EXPLAIN places the compiled plan in the query cache. Executing the query finds the cached plan which bypasses the query cache.

With the fix to that JIRA, anyone will still be able to do an EXPLAIN, but privileges will always be checked before actually executing the query.

But it is fair to ask: Should anyone be able to do EXPLAIN? An advantage of the current situation is that a performance analyst can look at query plans without having access to the data. But query plans do contain some statistical data which may make a determined hacker able to deduce things about the underlying data which they cannot directly see.

So, perhaps the ability to do EXPLAIN should itself be a privileged operation. Perhaps there should be a separate EXPLAIN privilege, either a global privilege or perhaps on individual tables. A person would be able to do EXPLAIN if they hold that privilege or if they hold SELECT privilege on the underlying tables.