Execute dynamic DDL in PL/SQL procedure through definer role permissions - oracle

Question

I want to perform some dynamic DDL in a procedure owned by an admin user. I'd like to execute this procedure with a technical operational user with definer rights (operational user doesn't have the create table role).
The problem is the 'create table' permission is granted to the admin user through use of a role, which doesn't allow me to execute the DDL as it seems that roles don't count in named pl/sql blocks.
create or replace
PROCEDURE test_permissions AUTHID DEFINER AS
v_query_string VARCHAR2(400 CHAR) := 'CREATE TABLE TEST(abcd VARCHAR2(200 CHAR))';
BEGIN
EXECUTE IMMEDIATE v_query_string;
END;
What I tried:
Running the procedure from a function set to AUTHID DEFINER with AUTHID CURRENT_USER on the proc (hoping the function would cascade the definer somehow)
Putting an anonymous block inside the function to execute the DDL (as roles seem to count in anonymous block)
If I set the AUTHID to CURRENT_USER, I can execute the procedure correctly with the admin user.
Is there any way I can work around this without granting CREATE TABLE directly to the admin user?

Answer 1

You can only set a role within a PL/SQL stored procedure/function if it has Invoker's Rights (AUTHID CURRENT_USER)(see doc). Which means that you can't use ops_user to call admin_user's procedure and then access admin_user's roles. If your DBAs insist on using a role to control the CREATE TABLE privilege, here's the approach I've seen before:
create or replace package admin_user.role_test authid current_user is
procedure test_permissions;
end role_test;
/
create or replace package body admin_user.role_test is
procedure test_permissions is
v_query_string VARCHAR2(400 CHAR) := 'begin
dbms_output.put_line(''after'');
for r in (select role from session_roles) loop
dbms_output.put_line(r.role);
end loop;
end;';
begin
dbms_output.put_line('before');
for r in (select role from session_roles) loop
dbms_output.put_line(r.role);
end loop;
DBMS_SESSION.SET_ROLE('CREATE_TABLE_ROLE IDENTIFIED BY "SECRET_PASSWORD"');
execute immediate v_query_string;
DBMS_SESSION.SET_ROLE('ALL EXCEPT CREATE_TABLE_ROLE'); -- restore defaults
end;
end role_test;
/
grant execute on admin_user.role_test to ops_user;
This will temporarily grant the role to ops_user just to execute your code. By default the ops_user should not be able to view the admin_user's package body source. You could probably wrap the package body to further protect the password. But password security aside, my biggest concern with this approach is that Oracle doesn't provide a nice way to disable a single role, so if ops_user has other password-protected roles, this code might raise an ORA-01979 when it tries to restore them.
So, there's an answer, but I'd still recommend doing what the other commenters suggested and granting CREATE TABLE to your admin user.