IOKit not permitted in Sandbox?

I'm new to using IOKit and have noticed what I think is the sandbox making it fail.

Here is the test I'm trying (in Pascal) which runs fine outside the sandbox but when I enable it IOServiceOpen returns the error kIOReturnNotPermitted every time.

Is IOKit not safe in the sandbox for certain services? I was trying to get some fan speeds/cpu temperatures and I see there are some apps in the AppStore (sandboxed) doing this so I believe it's possible. The only one I could confirm appears to have an XPC service bundled with the app as a helper so maybe that's a clue to make IOKit work? I tried basically all the entitlements and none of them seemed to help any.

Thanks for any ideas you may have.

procedure TestIOKit;
var
    err: kern_return_t;
    masterPort: mach_port_t;
    iterator: io_iterator_t;
    device: io_object_t;
    matchingDictionary: CFMutableDictionaryRef;
    conn: io_connect_t;
begin
    IOMasterPort(0, masterPort);
    matchingDictionary := IOServiceMatching('AppleSMC');
    err := IOServiceGetMatchingServices(masterPort, matchingDictionary, iterator);
    if err <> kIOReturnSuccess then
        writeln('IOServiceGetMatchingServices: ', err);

    device := IOIteratorNext(iterator);
    IOObjectRelease(iterator);
  if device = 0 then
        writeln('no smc found');

    err := IOServiceOpen(device, mach_task_self_, 0, conn);
  if err <> kIOReturnSuccess then
        writeln('IOServiceOpen: ', err);
end;

Solution

I found the same problem trying to read SMC keys in order get sensor temps and fan speeds from inside an OSX Yosemite 'Today extension'. The extension needs to be sandboxed, and I was also getting the kIOReturnNotPermitted error every time I tried to read the temp and fan sensors.

The only way I got it working was by creating a XPC service that manages all the SMC stuff, configured as a launch agent. This way, the sandboxed app (the 'today' extension) asks the XPC service for all the relevant data, instead of messing with IOKit directly.

So far, it seems to be working properly.