CSSM_SetPrivilege
» Table of Contents |  | | » Glossary | | | » Index | | |
| | |
| ||
| ||
PARAMETERS
| Privilege (input) | ||
The CSSM_PRIVILEGE value to be applied to subsequent calls to CSSM interfaces. | ||
DESCRIPTION
The CSSM_SetPrivilege() function accepts as input a privilege value and stores it in the CSSM framework. The integrity credentials of the module calling CSSM_SetPrivilege() must be verified by CSSM before the privilege value is updated. Integrity credentials are established using CSSM_Introduce(). CSSM will perform a pointer validation check to ensure the caller has been previously introduced. The CSSM_SetPrivilege() function will fail if no integrity information can be found for the caller.
After pointer validation checks, CSSM verifies the requested privilege is authorized. This is done by comparing Privilege with the set of privileges contained in the caller manifest. If Privilege is not a member, the CSSM_SetPrivilege() call fails.
Subsequent calls to the framework that require privileges inherit the privilege value previously established by CSSM_SetPrivilege(). CSSM will perform pointer validation checks on the API caller before servicing the API call. If OK, then the Privilege value is supplied to the SPI function.
Internally, CSSM builds and maintains privilege information based on the chosen scope of the implementation. The scope may be dictated by the capabilities of the platform hosting the CSSM. If threading is available, the privilege value can be associated with the thread ID of the currently executing thread. In this scenario, CSSM can manage a table of tuples consisting of threadID and privilege value. If threading is not available, the privilege value can be global to the process.
Because the selected privilege value is shared, the application programmer should take precautions to reset the privilege value whenever program flow leaves the caller's module and again when control flow returns. In general, any time there is a possibility for CSSM_SetPrivilege() to be called while within the context of the security critical section, CSSM_SetPrivilege() should be called again. Otherwise, the module receiving execution control could have called CSSM_SetPrivilege(), resulting in the privilege value being reset.
Data structures used to maintain the global privilege value should be initialized in CSSM_Init(). This includes lock initialization and preliminary resource allocation. The CSSM_Init() function is assumed to be idempotent with respect to shared structure initialization. This means CSSM_Init() will ensure a single thread initializes the shared structure and subsequent calls to CSSM_Init() will not reinitialize it. A reference count of calls to CSSM_Init() is needed to ensure matching calls to CSSM_Terminate() are handled.
Resource cleanup is performed at CSSM_Terminate() after the reference count falls to zero. The last call to CSSM_Terminate() results in shared resources being freed and lock structures being released.