Getting Started Windows Driver Development Part 1: Introduction and Setting Up the Environment

I’m writing this article on popular demand. This is a quick ramp-up guide for those of you who want to get your hands dirty practically writing Windows driver code. I’ll try to get you up and running in no time (technically less time).

Windows drivers are essential components that allow the operating system to communicate with hardware devices. Whether it’s a mouse, keyboard, or graphics card, each device requires a driver to function properly. Windows driver development can seem daunting at first, but with the right guidance, you can create your first basic driver with ease.

In this series, we’ll walk through the process of getting started with Windows Driver Development. By the end, you’ll have a better understanding of how to write, compile, and install drivers in a Windows environment. Let’s dive into Part 1, where we’ll focus on setting up the development environment and writing a simple driver.

Understanding Windows Drivers

Before jumping into coding, it’s important to understand the different types of drivers in Windows:

• User-mode drivers: These run in user space and are generally less risky, as they don’t have full access to the system’s hardware and memory.
• Kernel-mode drivers: These run in the kernel space and have complete access to the system. These are more powerful but can cause serious issues if not handled correctly.

We will focus on kernel-mode drivers in this series because they offer a deeper interaction with hardware.

Setting Up the Development Environment

To develop Windows drivers, you’ll need a few essential tools:

1. Windows Driver Kit (WDK): This provides the headers, libraries, and tools required to write Windows drivers.
2. Visual Studio: You’ll use this to write and compile your driver code.
3. WinDbg: This is a powerful debugger that can help with troubleshooting drivers.

Steps to Set Up Your Environment:

1. Install Visual Studio Download and install Visual Studio. Ensure you install the following workloads:
2. Install the Windows Driver Kit (WDK) You can download the latest version of WDK from Microsoft’s official site. WDK integrates with Visual Studio and provides the necessary tools to build drivers.
3. Enable Test Mode (Optional but Recommended) When developing and testing drivers, you’ll want to avoid the complexity of signing your driver. To do this, you can enable Windows Test Mode:

Creating a Simple Hello World Driver

Now that your environment is set up, let’s write a simple driver that logs “Hello World” when it loads into the system. This is the kernel-mode equivalent of a “Hello World” program.

Driver Entry Point

In a kernel-mode driver, the starting point is the DriverEntry function. This is where the driver initializes itself. Here’s how a simple driver would look:

#include <ntddk.h>        

NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
    UNREFERENCED_PARAMETER(DriverObject);
    UNREFERENCED_PARAMETER(RegistryPath);    DbgPrint("Hello, World from Kernel Mode Driver!\n");
    
    // Returning STATUS_SUCCESS indicates the driver loaded successfully
    return STATUS_SUCCESS;
}        

Explanation:

• DriverEntry is the entry point of the driver, similar to main() in a regular application.
• PDRIVER_OBJECT and PUNICODE_STRING are structures passed by the system when the driver is loaded.
• DbgPrint() is used to output messages to the debugger, similar to printf in user-mode applications.
• STATUS_SUCCESS is returned to indicate that the driver was loaded successfully.

Compiling the Driver

1. Open your Visual Studio solution.
2. Right-click the project in the Solution Explorer and choose Build.
3. Visual Studio will compile the driver into a .sys file, which is the format for kernel-mode drivers.

Installing and Testing the Driver

Trying the below exercise on a Virtual Machine like Hyper-V is recommended. You can still develop the code on your machine, but the drivers/sys files are better experimented on VMs.

Once the driver is compiled, you can install and load it using a tool called sc.exe (Service Control). This tool is included in Windows and is used to install kernel-mode drivers as services.

sc create HelloWorldDriver binPath= C:\path\to\your\driver.sys type= kernel
sc start HelloWorldDriver        

You can view the output of the DbgPrint call by using the WinDbg tool. Attach WinDbg to your system and use it to catch kernel-mode debug messages.

Conclusion

In this first part, we’ve covered the basics of Windows drivers, set up the development environment, and created a simple “Hello World” kernel-mode driver. In the next part, we’ll dive deeper into driver architecture, explore driver dispatch routines, and understand how drivers communicate with hardware.