Re: [BUG] Column-level privileges on inherited tables

KaiGai Kohei wrote:
> I've observed the behavior of column-level privileges and
> required permissions with a few elog()s injected.
>
> I noticed rte->selectedCols is incorrect when we make a query
> on inherited tables.
>
> See below:
> -------------------------------------------------
> postgres=# CREATE TABLE t1 (a int, b int, c int);
> CREATE TABLE
> postgres=# ALTER TABLE t1 DROP COLUMN b;
> ALTER TABLE
> postgres=# CREATE TABLE t2 (d int) inherits (t1);
> CREATE TABLE
> postgres=# SELECT * FROM t1;
> NOTICE: markRTEForSelectPriv: ACL_SELECT on t1.a
> NOTICE: markRTEForSelectPriv: ACL_SELECT on t1.c
> NOTICE: ExecCheckRTEPerms: ACL_SELECT on t1 perms = 0000 inh = 1
> NOTICE: ExecCheckRTEPerms: selectedCols: t1.a
> NOTICE: ExecCheckRTEPerms: selectedCols: t1.c
> NOTICE: ExecCheckRTEPerms: ACL_SELECT on t1 perms = 0002 inh = 0
> NOTICE: ExecCheckRTEPerms: selectedCols: t1.a
> NOTICE: ExecCheckRTEPerms: selectedCols: t1.c
> NOTICE: ExecCheckRTEPerms: ACL_SELECT on t2 perms = 0002 inh = 0
> NOTICE: ExecCheckRTEPerms: selectedCols: t2.a
> NOTICE: ExecCheckRTEPerms: selectedCols: t2.d <--- (*)
> a | c
> ---+---
> (0 rows)
> -------------------------------------------------
>
> I injected elog() at the head of ExecCheckRTEPerms() to print requiredPerms
> and all the columns on selectedCols/modifiedCols.
>
> It seems to me the current implementation assumes the parant table and
> child table have same set of attribute name/number pair, but incorrect.
> It is necessary to lookup attribute names of "t2" when we extract
> inherited tables.

In addition, the whole-row-reference can be problematic.

When we run "SELECT t1 FROM t1", the column level privilege tries to check
all the columns within t1 and t2. But, I think it should not check on "t2.d"
in this case, because the column is not a target of this query.

In the whole-row-reference case, attno==0 on the parent table should be
extracted into correct set of columns on the children.

Thanks,
--
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai(at)ak(dot)jp(dot)nec(dot)com>