kit-transue
commented
2 years ago I have not found great sources of documentation for using USB in the post-kext era. I've managed to get a few hack-with-hardware devices working, but I'm definitely not an expert and don't have broad experience in the domain. That said:
I'd look at what device you are trying to get a connection to. Again: my notes are slim, but I recall "can't get exclusive access" happens when the OS thinks it should be providing the driver for the device. I think I get that with the MCP2221 which offers an HID interface: macOS sees that and--quite properly, IMO--binds to it. User mode applications should still be able to communicate with the device; they just have to go through the HID API.
My suggestions:
- be clear about what device you are seeking to attach to, and check your matching dictionary
- use the System Information tool to assess the OS's knowledge of the attached hardware
- watch for extensions being assigned to the hardware
- if you suspect sandboxing, trying building a small application without it
- if you ask for help on this, you probably need to describe the call you're making & its arguments: the failure you're seeing is a bit non-specific
While the documentation can be slim, the fundamental security architecture seems sound and also reasonable. You should not need special DriverKit certification from Apple, nor should you need to be root. My mental model is that the documentation is very old and while much of it describes a kext model that has (thankfully!) disappeared, parts of that technology came over to the usermode side and the documentation is yet to be modernized.
mickeyl
When using inside a sandboxed app I get
I am fairly confident this is more of an Apple usb security level but I thought I'd ask just in case. There isn't much info about this and the only forum question is still unanswered