MidPoint authorizations provide a very powerful mechanism for a fine-grained access control. This mechanism is quite simple in principle. But the configuration can get very complex especially if a sophisticated RBAC structure is in place. Setting the authorization up is not entirely easy task. It is often quite difficult to tell why the user is not authorized for a specific action or why the user can access more than he is supposed to. Therefore this page describes basic mechanisms how to troubleshoot authorizations.
The basic troubleshooting steps are simple in theory:
- Enable logging of authorization processing
- Repeat the operation
- Figure out which authorization is wrong
- Fix it
- Rinse and repeat
Yet, the practice is much more complex. As always.
The authorizations are processed in midPoint security component. The processing of every authorization is logged. Therefore to see the authorization processing trace simply enable the logging of security component:
However, please keep in mind that this is quite intense logging. It can easily impact the system performance and flood the logs on a busy system with a lot of authorization. It is better to troubleshoot the configuration in a development or testing environment.
When the security logging is enabled then you can see following messages in the logs:
There is a set of similar messages for every operation that midPoint attempts. First message describes the operations and its "context": who has executed it (principal), what was the object and target of the operation (if applicable). The last line usually summarizes the decision: allow or deny. The lines between describe the processing of each individual authorization. If you examine that part carefully then you can figure out which authorizations were used. The result of authorization evaluation can be one of these:
- Authorization denies the operation. That's a dead end. If any authorization denies the operation then the operation is denied. No other authorizations need to be evaluated.
- Authorization allows the operation. That's a green light. However, other authorizations are still evaluated to make sure that there is no other authorization that denies the operation.
- Authorization is not applicable. The authorization does not match the constraint for object or target. Or it is not applicable for other reasons. Such authorization is skipped.
If there is a single deny then the evaluation is done. The operation is denied. Deny is also a default decision. I.e. if there is no decision at the end of the evaluation then the operation is denied. At least one explicit allow is needed to allow the operation
All of that is recorded in the log. You will see processing of every operation, every authorization, evaluation of every authorization clause whether the authorization is applicable or not.
Yes, this is no easy task. Troubleshooting is a hard work. And this is the best way that we have figured out to troubleshoot the authorizations. If you have any better idea we are more than open to suggestions.
Authorization of operations such as add or delete is quite easy. The result is simple: the operation is either allowed or denied. But it is a bit different for get operations. The entire get operation can still be denied if the user does not have any access to the object that he is trying to retrieve. But the common case is that the user has some access to the object, but not all the fields (properties). In such a case the operation must be allowed. But the retrieved object needs to be post-processed to remove the fields that are not accessible to the user. This is done in two steps.
Firstly the set of object security constraints is compiled from the authorizations. The object security constraints is a data structure that describes which properties of an object are accessible to the user. There is a map (
itemConstraintMap) with an entry for every item (property) which is explicitly mentioned in the authorizations. This entry contains explicit decisions given by the authorizations for every basic access operation (read, add, modify, delete). And then there are default decisions (
actionDecisionMap). These decisions are applied if there is no explicit entry for the item. This object security constraints data structure is usually logged when it is compiled.
Secondly, the object security constraints are applied to the retrieved object. The constraints are used to remove the properties that are not accessible to the user. This process is not easy to follow in the logs. Therefore it is better to inspect the object security constraints structure. If it is correct then also the resulting object will be most likely correct.
Object security constraints and the user inteface
The object security constraints has much broader application than just authorization of the read operations. This data structure is (indirectly) used by midPoint user interface when displaying edit forms for objects. The data from this structure are used to figure out which fields are displayed as read-write, which fields are read only and which fields are not displayed at all. The object security constraints structure is always produced by the same algorithm in the security component. Therefore the interaction of authorizations and GUI forms can be diagnosed in the same way as the get operations.
Search operations are very different than common operations such as add or delete and they are also different than get operations. Search operations will not result in an access denied error (except for few special cases). If the user that is searching has access only to some objects then only those objects will be returned. There is no error, because this is a perfectly normal situation. The extreme case is that user has access to no object at all. But although this situation is not entirely "normal" it is also not in any way special. The search will simply return empty result and there is also no error. You need to keep this in mind when troubleshooting the read authorizations. Attempt to get unaccessible objects will result in a security violation error. But searching for them will simply return empty result and there is no error.
The search operations are interesting for another reason. Operations such as get, add or delete have precise specification of object: the object that is being retrieved, added or modified. But it is entirely different for search operations. The object is a result of the search operation, not the parameter. We cannot examine the object before the search and decide whether we allow or deny the operation. There is no object before search operation. Also, we cannot simply search all objects and then filter out those that are denied. That would be totally inefficient and it will completely ruin paging mechanisms. A completely different strategy is needed for search operations.
Search authorizations work the other way around: first the authorizations statements are compiled to a search filter. For example if the authorization allows access only to active roles the authorization is compiled to a filter
enabled. Then this filter is appended to the normal search filter and the search operation is performed. This approach ensures that the search returns only the objects that the user is authorized to see. It also makes the search as efficient as possible and maintains page boundaries. But that is not all. Another round of post processing is needed to filter out only the items that are not visible to the user. This is the same filter as is applied to get operations.
Tips and Notes
There is a couple of things to keep in mind:
- The authorizations are designed to be additive. Each role should allow the minimum set of operations needed for the users to complete their job. The midPoint will "merge" all the authorizations from all the roles. Use allow operations, avoid deny operations if possible. It is much better not to allow an operation than to deny it.
- Deny always wins. If there is a single deny in any applicable authorization in any roles then the operation is denied. It does not matter if there are thousands of allow authorizations, deny always wins. What was once denied cannot be allowed again. We need this approach because we do not have any way how to order the authorization in many roles. Do not use deny unless really needed.
- There are two phases: request and execution. The operation needs to be allowed in both phases to proceed. Please keep in mind the that object may be changed between request and execution due to mappings, metadata and properties that are maintained by midPoint. This is also the reason why we have separate authorizations for request and execution.
Name the authorizations. Each authorization statement can have an optional name. Specify a reasonably unique name there. Then use that name as a string to find the appropriate trace in the log files:
The configuration issues listed in this section are commonly seen in midPoint deployments.
Request and Execution
There are two phases: request and execution. The operation needs to be allowed in both phases to proceed. Common issue is that the operation is allowed in the request phase, but it is not allowed in execution phase.
Special note about assign/unassign authorizations: assgin/unassign authorizations make sense only in the request phase. The primary goal of these authorizations is to limit the targets of assignment. And that is processed only in the request phase. All that execution phase can see is just a modification of the
assignment container. Therefore for the assign/unassign authorizations to work correctly, you have to allow assign in the request phase and modification of
assignment container in the execution phase. The default end user role is a good example for this: