commit 170a291d4d2ab5e7a223ac3fceb7ee38e76d3ffc
author kar-rahul-aws <118818625+kar-rahul-aws@users.noreply.github.com> Mon Sep 18 15:34:42 2023 +0530
committer GitHub <noreply@github.com> Mon Sep 18 15:34:42 2023 +0530
tree 75e074935bdbf3796f65c18a2aeb8c53607cb541
parent 7db0e87af1a9068056424636b96d520771d3473a

Add Access Control List to MPU ports (#765)

This PR adds Access Control to kernel objects on a per task basis to MPU
ports. The following needs to be defined in the `FreeRTOSConfig.h` to
enable this feature:

```c
#define configUSE_MPU_WRAPPERS_V1 0
#define configENABLE_ACCESS_CONTROL_LIST 1
```

This PR adds the following new APIs:

```c
void vGrantAccessToTask( TaskHandle_t xTask,
                         TaskHandle_t xTaskToGrantAccess );
void vRevokeAccessToTask( TaskHandle_t xTask,
                          TaskHandle_t xTaskToRevokeAccess );

void vGrantAccessToSemaphore( TaskHandle_t xTask,
                              SemaphoreHandle_t xSemaphoreToGrantAccess );
void vRevokeAccessToSemaphore( TaskHandle_t xTask,
                               SemaphoreHandle_t xSemaphoreToRevokeAccess );

void vGrantAccessToQueue( TaskHandle_t xTask,
                          QueueHandle_t xQueueToGrantAccess );
void vRevokeAccessToQueue( TaskHandle_t xTask,
                           QueueHandle_t xQueueToRevokeAccess );

void vGrantAccessToQueueSet( TaskHandle_t xTask,
                             QueueSetHandle_t xQueueSetToGrantAccess );
void vRevokeAccessToQueueSet( TaskHandle_t xTask,
                              QueueSetHandle_t xQueueSetToRevokeAccess );

void vGrantAccessToEventGroup( TaskHandle_t xTask,
                               EventGroupHandle_t xEventGroupToGrantAccess );
void vRevokeAccessToEventGroup( TaskHandle_t xTask,
                                EventGroupHandle_t xEventGroupToRevokeAccess );

void vGrantAccessToStreamBuffer( TaskHandle_t xTask,
                                 StreamBufferHandle_t xStreamBufferToGrantAccess );
void vRevokeAccessToStreamBuffer( TaskHandle_t xTask,
                                  StreamBufferHandle_t xStreamBufferToRevokeAccess );

void vGrantAccessToMessageBuffer( TaskHandle_t xTask,
                                  MessageBufferHandle_t xMessageBufferToGrantAccess );
void vRevokeAccessToMessageBuffer( TaskHandle_t xTask,
                                   MessageBufferHandle_t xMessageBufferToRevokeAccess );

void vGrantAccessToTimer( TaskHandle_t xTask,
                          TimerHandle_t xTimerToGrantAccess );
void vRevokeAccessToTimer( TaskHandle_t xTask,
                           TimerHandle_t xTimerToRevokeAccess );
```

An unprivileged task by default has access to itself only and no other
kernel object. The application writer needs to explicitly grant an
unprivileged task access to all the kernel objects it needs. The best
place to do that is before starting the scheduler when all the kernel
objects are created. 

For example, let's say an unprivileged tasks needs access to a queue and
an event group, the application writer needs to do the following:

```c
vGrantAccessToQueue( xUnprivilegedTaskHandle, xQueue );
vGrantAccessToEventGroup( xUnprivilegedTaskHandle, xEventGroup );
```

The application writer MUST revoke all the accesses before deleting a
task. Failing to do so will result in undefined behavior. In the above
example, the application writer needs to make the following 2 calls
before deleting the task:

```c
vRevokeAccessToQueue( xUnprivilegedTaskHandle, xQueue );
vRevokeAccessToEventGroup( xUnprivilegedTaskHandle, xEventGroup );

```