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https://issues.apache.org/jira/browse/DERBY-6429?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13855751#comment-13855751
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Rick Hillegas commented on DERBY-6429:
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Thanks for continuing to test-drive this patch, Knut. I am able to reproduce
your results. Looking at the stack traces for both experiments (with and
without rows in the table in the subquery), here is my theory about what is
happening:
1) The subquery result is being materialized as a OnceResultSet which runs
before the UPDATE runs.
2) But all of the permissions attached to the statement are checked just before
the UpdateResultSet executes.
3) If the OnceResultSet contains more than one row, then it raises the "Scalar
subquery is only allowed to return a single row" error before the permissions
associated with the UpdateResultSet are checked.
Fixing this may required some thought. The permissions are attached to the
CompilerContext during the bind() phase. They are not attached to individual
query blocks. I think that the decision to materialize the subquery is made
during the pre-processing phase of optimization. By that time, we have lost all
memory of which query block the permissions came from.
I would tend to regard this as another bug with privilege management, which
deserves its own JIRA. What are your thoughts?
Thanks,
-Rick
> Privilege checks for UPDATE statements are wrong.
> -------------------------------------------------
>
> Key: DERBY-6429
> URL: https://issues.apache.org/jira/browse/DERBY-6429
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.11.0.0
> Reporter: Rick Hillegas
> Assignee: Rick Hillegas
> Attachments: derby-6429-01-ab-privilegeFilters.diff,
> derby-6429-01-ac-privilegeFilters.diff,
> derby-6429-01-ad-privilegeFilters.diff, derby-6429-01-ae-privilegeFilters.diff
>
>
> UPDATE statements confuse SELECT and UPDATE privileges. Consider the
> following SET clause:
> SET updateColumn = selectColumn
> According to part 2 of the 2011 edition of the SQL Standard, that SET clause
> requires the following privileges:
> 1) UPDATE privilege on updateColumn. Privileges for the left side of a SET
> clause are described by section 14.14 (update statement: searched), access
> rule 1b.
> 2) SELECT privilege on selectColumn. Privileges for the right side of a SET
> clause are described by section 14.15 (set clause list) and the various
> productions underneath value expression. In this case, we have a column
> reference, whose privileges are governed by section 6.7 (column reference),
> access rule 2.
> However, Derby requires the following:
> 1') UPDATE privilege on both updateColumn and selectColumn
> When we address this bug, we should make corresponding changes to the MERGE
> statement.
> The following script shows the current behavior:
> connect 'jdbc:derby:memory:db;user=test_dbo;create=true';
> call syscs_util.syscs_create_user( 'TEST_DBO', 'test_dbopassword' );
> call syscs_util.syscs_create_user( 'RUTH', 'ruthpassword' );
> connect 'jdbc:derby:memory:db;shutdown=true';
> connect 'jdbc:derby:memory:db;user=test_dbo;password=test_dbopassword' as dbo;
> create table t1_025
> (
> a int primary key,
> updateColumn int,
> selectColumn int,
> privateColumn int
> );
> grant update ( updateColumn ) on t1_025 to ruth;
> grant select ( selectColumn ) on t1_025 to ruth;
> insert into t1_025 values ( 1, 100, 1000, 10000 );
> connect 'jdbc:derby:memory:db;user=ruth;password=ruthpassword' as ruth;
> -- correctly succeeds because ruth has UPDATE privilege on updateColumn
> update test_dbo.t1_025 set updateColumn = 17;
> -- the error message incorrectly states that the missing privilege
> -- is UPDATE privilege on privateColumn
> update test_dbo.t1_025 set updateColumn = privateColumn;
> -- incorrectly fails.
> -- ruth does have UPDATE privilege on updateColumn
> -- and SELECT privilege on selectColumn, which should be good enough.
> -- however, the error message incorrectly states that the missing privilege
> -- is UPDATE privilege on selectColumn.
> update test_dbo.t1_025 set updateColumn = selectColumn;
> -- incorrectly succeeds even though ruth does not have SELECT privilege on
> updateColumn
> update test_dbo.t1_025 set updateColumn = 2 * updateColumn;
> set connection dbo;
> select * from t1_025 order by a;
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