Determining the level of Android permission

For Android-Permission..

• To enforce permissions, various parts of the system invoke a permission validation mechanism to check whether a given application has a specied permission. The permission validation mechanism is implemented as part of the trusted system process, and invocations of the permission validation mechanism are spread throughout the API. There is no centralized policy for checking permissions when an API is called. Rather, mediation is contingent on the correct placement of permission validation calls.

  

• Permission checks are placed in the API implementation in the system process. When necessary, the API implementation calls the permission validation mechanism to check that the invoking application has the necessary permissions. In some cases, the API library may also redundantly check these permissions, but such checks cannot be relied upon: applications can circumvent them by directly communicating with the system process via the RPC stubs. Permission checks therefore should not occur in the API library. In- stead, the API implementation in the system process should invoke the permission validation mechanism.

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