Oracle选择性系统授权

Selective System Grants 

问题：

我只想授予XX用户alter system set user_dump_dest 权限！

I want to give users the ability to execute "alter system set user_dump_dest" only. I want to give them the ability to turn on extended tracing but write out the trace files to a different directory, such as /tmp, rather than to the default directory. Is there a way to do this easily? 

Tom回答：

存储过程是绝佳方案！

Stored procedures are great for this! 

存储过程，默认以定义者权限运行。你需要做的就是：

A stored procedure, by default, runs with the base privileges of the definer of the routine. As a user with the ability to use ALTER SYSTEM , all you need to do is 

create or replace procedure set_udump (p_udump in varchar2)
as
begin
 if ( p_udump NOT LIKE '%=%' )
 then
      execute immediate 'alter system set 
      user_dump_dest = '''||p_udump||''' scope=memory';
 else
    raise_application_error(-20000,'Sorry, but for safety 
    reasons this procedure does not allow "=" in the parameter value');
 end if;
end;
/

防止SQL注入攻击！

Note: Revised content—to prevent SQL injection—for this procedure submitted by Roy Jorgensen.

The owner of the procedure needs to have ALTER SYSTEM granted directly, not via a role. Seeasktom.oracle.com/~tkyte/Misc/RolesAndProcedures.html for details on that nuance. So we run 

SQL> grant alter system to a;
Grant succeeded. 

SQL> grant execute on set_udump to scott;
Grant succeeded.

Now, connected as SCOTT , run 

SQL> exec set_udump( '/tmp' );
PL/SQL procedure successfully 
completed.

这种途径提供优秀的安全机制。

This approach works for any privilege you want to grant selectively like this. Stored procedures—with their ability to run as definer—provide an excellent security mechanism!