3 Managing User Privileges

Matthew and Winston both are sample employees in the HR.EMPLOYEES table. This table provides columns for the manager ID and email address of the employees, among other information. You must create user accounts for these two employees so that they can later test the secure application role.

To create the user accounts:

1. In Enterprise Manager, access the Database home page.

   See Oracle Database 2 Day DBA for more information.

2. Access your target database and then log in as user SYSTEM.

3. From the Administration menu, select Security, then Users.

4. In the Users page, click Create.

5. In the Create User page, enter the following information:

   • Name: mweiss (to create the user account for Matthew Weiss)

   • Profile: DEFAULT

   • Authentication: Password

   • Enter Password and Confirm Password: Enter a password that meets the requirements in "Requirements for Creating Passwords".

   • Default Tablespace: EXAMPLE

   • Temporary Tablespace: TEMP

   • Status: Unlocked

6. Click System Privileges.

7. Click Edit List.

8. In the Modify System Privileges, from the Available System Privileges lists, select the CREATE SESSION privilege, and then click Move to move it to the Selected System Privileges list.

9. Click OK.

   The Create User page appears, with CREATE SESSION listed as the system privilege for user mweiss.

10. Ensure that the Admin Option for CREATE SESSION is not selected, and then click OK.

11. In the Users page, select the selection button for user MWEISS from the list of users, and then from the Actions list, select Create Like. Then, click Go.

12. In the Create User page, enter the following information to create the user account for Winston, which will be almost identical to the user account for Matthew:

    • Name: wtaylor

    • Enter Password and Confirm Password: Enter a password that meets the requirements in "Requirements for Creating Passwords".

    You do not need to specify the default and temporary tablespaces, or the CREATE SESSION system privilege, for user wtaylor because they are already specified.

13. Click OK.

Now both Matthew Weiss and Winston Taylor have user accounts that have identical privileges.

To create the sec_admin security administrator account:

1. From the Administration menu, select Security, then Users.

   If the Database Login page appears, then log in as an administrative user, such as SYS. User SYS must log in with the SYSDBA role selected.

2. In the Users page, click Create.

3. In the Create User page, enter the following information:

   • Name: sec_admin

   • Profile: Default

   • Authentication: Password

   • Enter Password and Confirm Password: Enter a password that meets the requirements in "Requirements for Creating Passwords".

   • Default Tablespace: EXAMPLE

   • Temporary Tablespace: TEMP

   • Status: UNLOCKED

4. Click System Privileges.

5. Click Edit List.

   The Modify System Privileges page appears.

6. In the Available System Privileges list, select the following privileges and then click Move to move each one to the Selected System Privileges list. (Hold down the Control key to select multiple privileges.)

   • CREATE PROCEDURE

   • CREATE ROLE

   • CREATE SESSION

   • INHERIT ANY PRIVILEGES

   • SELECT ANY DICTIONARY

7. Click OK.

   The Create User page appears. Under Admin Option, do not select the boxes.

8. Click OK.

   The Users page appears. User sec_admin is listed in the User Name list.

The grant_emp_role procedure, which you will create later in this tutorial, grants the emp_role only to managers who report to Steven King, whose employee ID is 100. This information is located in the HR.EMPLOYEES table. However, you should not use that table in this procedure, because it contains sensitive data such as salary information, and for it to be used, everyone will need access to it. In most real world cases, you create a lookup view that contains only the information that you need. (You could create a lookup table, but a view will reflect the most recent data.) For this tutorial, you create your own lookup view that only contains the employee names, employee IDs, and their manager IDs.

To create the HR.HR_VERIFY lookup view:

1. In SQL*Plus, connect as user HR.

   CONNECT HR
   Enter password: password
   

   If you receive an error message saying that HR is locked, then you can unlock the account and reset its password by entering the following statements. For greater security, do not reuse the same password that was used in previous releases of Oracle Database. Enter any password that is secure, according to the password guidelines described in "Requirements for Creating Passwords".

   CONNECT SYSTEM
   Enter password: password
   
   PASSWORD HR
   Changing password for HR
   New password: password
   Retype new password: password
   Password changed.
   
   ALTER USER HR ACCOUNT UNLOCK;
   
   CONNECT HR
   Enter password: password
   

2. Enter the following CREATE VIEW SQL statement to create the lookup view:

   CREATE VIEW hr_verify AS 
   SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, EMAIL, MANAGER_ID 
   FROM EMPLOYEES;
   

3. Grant the EXECUTE privilege for this view to mweiss, wtaylor, and sec_admin by entering the following SQL statements:

   GRANT SELECT ON hr_verify TO mweiss;
   GRANT SELECT ON hr_verify TO wtaylor;
   GRANT SELECT ON hr_verify TO sec_admin;
   

In most cases, you create a package to hold the procedure, but because this is a simple tutorial that requires only one secure application role test (as defined in the procedure), you will create a procedure by itself. If you want to have a series of procedures to test for the role, then you would create them in a package. At this stage, the role does not exist, but it does not need to. You will create it in the next step.

A PL/SQL package defines a simple, clear interface to a set of related procedures and types that can be accessed by SQL statements. Packages also make code more reusable and easier to maintain. The advantage here for secure application roles is that you can create a group of security policies that used together present a solid security strategy designed to protect your applications. For users (or potential intruders) who fail the security policies, you can add auditing checks to the package to record the failure.

To create the secure application role procedure:

1. In Enterprise Manager, click Log Out to log out of the database.

2. In the Confirmation dialog box, select Logout of (Database Instance) and then select the Display login page after logout check box. Then click Logout.

3. Log in as user sec_admin using the NORMAL role.

4. From the Schema menu, select Programs, then Procedures.

5. In the Procedures page, click Create.

6. In the Create Procedure page, enter the following information:

   • Name: GRANT_EMP_ROLE

   • Schema: SEC_ADMIN

   • Source: Delete the empty procedure code that has been provided and then enter following text to create the secure application role procedure.

     AUTHID CURRENT_USER
      AS
     v_user varchar2(50); 
     v_manager_id number :=1;
      BEGIN    
       v_user := lower((sys_context ('userenv','session_user')));
       SELECT manager_id 
          INTO v_manager_id FROM hr.hr_verify WHERE lower(email)=v_user;
        IF v_manager_id = 100
         THEN 
          EXECUTE IMMEDIATE 'SET ROLE emp_role';  
         ELSE NULL; 
        END IF;        
       EXCEPTION  
        WHEN NO_DATA_FOUND THEN v_manager_id:=0;  
        DBMS_OUTPUT.PUT_LINE(v_manager_id);
     END;
     

     In this specification:

     • AUTHID CURRENT USER: Appends the AUTHID CURRENT_USER clause to the CREATE PROCEDURE statement. The AUTHID CURRENT_USER clause enables the invoking user to run the procedure using his or her privileges.

       You must create the procedure to use invoker's rights for the procedure to work. Invoker's rights allow the user to have EXECUTE privileges on all objects that the procedure accesses.

       Roles that are enabled inside an invoker's right procedure remain in effect even after the procedure exits, but after the user exits the session, he or she no longer has the privileges associated with the secure application role. In this case, you can have a dedicated procedure that enables the role for the rest of the session.

       Because users cannot change the security domain inside definer's rights procedures, secure application roles can only be enabled inside invoker's rights procedures.

       See "About Secure Application Roles" for information about the importance of creating the procedure using invoker's rights.

     • v_user varchar2(50): Declares the v_user variable, which will store the user session information.

     • v_manager_id number :=1: Declares the v_manager_id variable, which will store the manager's ID of the v_user user.

     • v_user := lower...: Retrieves the user session information for the user logging on, in this case, Matthew or Winston. To retrieve user session information, use the SYS_CONTEXT SQL function with the USERENV namespace attributes ('userenv', session_attribute), and writes this information to the v_user variable.

       The information returned by this function indicates the way in which the user was authenticated, the IP address of the client, and whether the user connected through a proxy. See Oracle Database SQL Language Reference for more information about SYS_CONTEXT.

     • SELECT manager_id ... INTO...: Get the manager's ID of the current user. The SELECT statement copies the manager ID into the v_manager_id variable, and then checking the HR.HR_VERIFY view for the manager ID of the current user. This example uses the employees' email addresses because they are the same as their user names.

     • IF ... THEN ... END IF: Use an IF condition to test whether the user should be granted the grant_emp_role role. In this case, the test condition is whether the user reports to Matthew's manager, Steven King, whose employee number is 100. If the user reports to King, as Matthew does, then the secure application role is granted to the user. Otherwise, the role is not granted.

       The result is that the secure application role will grant Matthew Weiss the role because he is a direct report of Steven King, but will deny the role to Winston, because he is not a direct report of Steven King.

     • THEN ... ELSE NULL: Within the IF condition, the THEN condition grants the role by executing immediately the SET ROLE statement. Otherwise, the ELSE condition denies the grant.

     • EXCEPTION: Use an EXCEPTION statement to set v_manager_id to 0 if no data is found.

     • DBMS_OUTPUT.PUT_LINE: Copies the manager's ID, which is now 0, into a buffer so that it is readily available.

7. Click OK.

   Tip:

   If you have problems creating or running PL/SQL code, check the Oracle Database trace files. The USER_DUMP_DEST initialization parameter specifies the current location of the trace files. You can find the value of this parameter by issuing SHOW PARAMETER USER_DUMP_DEST in SQL*Plus. See Oracle Database Administrator's Guide for more information about trace files.

To create the secure application role:

1. Ensure that you are still logged in as user sec_admin.

2. From the Administration menu, select Security, then Roles.

3. In the Roles page, click Create.

4. In the Create Role page, enter the following information:

   • Name: emp_role

   • Authentication: Select Application.

     The page expands to show the additional prompts necessary to create the secure application role.

     
     Description of the illustration sec_app_role.gif

5. Select the Procedure option.

6. In the Procedure Name field, enter SEC_ADMIN.GRANT_EMP_ROLE.

7. Click OK.

This gives anyone who has been authorized to use the emp_role role the ability to select from the OE.ORDERS table.

To grant the SELECT privilege for the EMP_ROLE role to the OE.ORDERS table:

1. Connect as user OE.

   CONNECT OE
   Enter password: password
   

   If you receive an error message saying that OE is locked, then you can unlock the OE account and reset its password by entering the following statements. For greater security, do not reuse the same password that was used in previous releases of Oracle Database. Enter any password that is secure, according to the password guidelines described in "Requirements for Creating Passwords".

   CONNECT SYSTEM
   Enter password: sys_password
   
   PASSWORD OE  -- First, change the OE account password.
   Changing password for OE
   New password: password
   Retype new password: password
   Password changed.
   
   ALTER USER OE ACCOUNT UNLOCK; -- Next, unlock the OE account.
   

   Another way to unlock a user account and create a new password is to use the following syntax:

   ALTER USER account_name ACCOUNT UNLOCK IDENTIFIED BY new_password:
   

   Now you can connect as user OE.

   CONNECT OE 
   Enter password: password
   

2. Enter the following statement to grant the emp_role role SELECT privileges on the OE.ORDERS table.

   GRANT SELECT ON ORDERS TO emp_role;
   

   Do not grant the role directly to the users. The PL/SQL package will do that for you, assuming the users pass its security policies.

The next step is to grant them the EXECUTE privilege on the grant_emp_role procedure, so that the grant_emp_role procedure can execute, and then grant or deny access, when they try to select from the OE.ORDERS table.

To grant EXECUTE privileges for the grant_emp_role procedure:

1. In SQL*Plus, log in as user sec_admin.

   connect sec_admin
   Enter password: password
   

2. Run the following GRANT SQL statements for users mweiss and wtaylor:

   GRANT EXECUTE ON grant_emp_role TO mweiss;
   GRANT EXECUTE ON grant_emp_role TO wtaylor;
   

To remove the components:

1. In SQL*Plus, connect as user SYSTEM.

   CONNECT SYSTEM
   Enter password: password
   

2. Enter the following DROP statements:

   DROP USER mweiss;
   DROP USER wtaylor;
   

   Do not drop user sec_admin. You will need this user account for other tutorials in this guide.

3. In SQL*Plus, connect as user sec_admin.

   CONNECT sec_admin
   Enter password: password
   

4. Enter the following DROP SQL statements:

   DROP ROLE emp_role;
   DROP PROCEDURE grant_emp_role;
   

5. Connect as user HR, and then drop the HR_VERIFY view.

   CONNECT HR
   Enter password: password
   DROP VIEW hr_verify;
   

6. Exit SQL*Plus.

   EXIT