RESLEVEL and intra-group queuing
By default, when an API-resource security check is made by the intra-group queuing agent, two user IDs are checked to see if access is allowed to the resource. We can change which user IDs are checked by setting up an RESLEVEL profile.
The user IDs checked can be the user ID determined by the IGQUSER attribute of the receiving queue manager, the user ID of the queue manager within the queue sharing group that put the message on to the SYSTEM.QSG.TRANSMIT.QUEUE, or the alternate user ID specified in the UserIdentifier field of the message descriptor of the message. See User IDs used by the intra-group queuing agent for more information.
Because the intra-group queuing agent is an internal queue manager task, it does not issue an explicit connect request and runs under the user ID of the queue manager. The intra-group queuing agent starts at queue manager initialization. During the initialization of the intra-group queuing agent, IBM MQ checks the access that the user ID associated with the queue manager has to a profile in the MQADMIN class called:hlq.RESLEVEL
This check is always performed unless the hlq.NO.SUBSYS.SECURITY switch has been set.
If there is no RESLEVEL profile, IBM MQ enables checking for two user IDs. If there is a RESLEVEL profile, the level of checking depends on the access level granted to the user ID of the queue manager for the profile. Checks made at different RACF®(r) access levels for the intra-group queuing agent shows the checks made for the intra-group queuing agent.| RACF access level | Level of checking |
|---|---|
| NONE | Check two user IDs. |
| READ | Check one user ID. |
| UPDATE | Check one user ID. |
| CONTROL | No check. |
| ALTER | No check. |
| Note: See User IDs used by the intra-group queuing agent for a definition of the user IDs checked | |
If the permissions granted to the RESLEVEL profile for the queue manager's user ID are changed, the intra-group queuing agent must be stopped and restarted to pick up the new permissions. Because there is no way to independently stop and restart the intra-group queuing agent, the queue manager must be stopped and restarted to achieve this.