Linux Kernel to Permanently Remove USB RNDIS Protocol Driver
Linux Kernel to Permanently Remove USB RNDIS Protocol Driver
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Linux Kernel to Permanently Remove USB RNDIS Protocol Driver
January 2 – Greg Kroah-Hartman, a Linux Foundation researcher, has proposed a plan to completely remove the USB Remote Network Driver Interface Specification (RNDIS) protocol driver from the Linux kernel.
USB RNDIS is a network driver protocol that emulates USB devices as network adapters, enabling network connections between computers and devices via USB cables. Essentially, it allows for TCP/IP communication over USB.
Originally introduced during the Microsoft Windows XP era, the protocol is plagued by numerous security vulnerabilities. Kroah-Hartman first suggested removing it in November 2022, citing its risks.
On December 23, 2024, Kroah-Hartman reiterated his proposal, emphasizing that this outdated protocol is no longer necessary and poses significant security risks to systems. He warned that systems using RNDIS to connect to untrusted hosts or devices are highly vulnerable to network threats.
Kroah-Hartman stressed that the safest approach is to remove RNDIS from the Linux kernel as soon as possible to mitigate these risks.
What is USB RNDIS Protocol?
The USB RNDIS (Remote Network Driver Interface Specification) protocol is a Microsoft-developed standard that enables a USB device to emulate a network interface, such as a virtual Ethernet card.
This allows data transfer over USB to mimic standard network operations, enabling communication between a host (like a PC) and a device (like an embedded system or smartphone) using standard networking protocols such as TCP/IP.
Key Features:
- Virtual Network Adapter: RNDIS allows a USB-connected device to appear as a network adapter to the host operating system, facilitating network-like data transfer.
- TCP/IP Communication: Through RNDIS, devices can exchange data using standard internet protocols over a USB connection, without the need for a dedicated network interface (e.g., Ethernet or Wi-Fi).
- Platform Support: It was originally introduced by Microsoft and is mainly supported on Windows platforms, though it has been implemented in other systems like Linux.
Typical Applications:
- Connecting embedded devices (like IoT systems) to computers for configuration or data transfer.
- Allowing smartphones to share their internet connection (tethering) over USB.
- Communicating with USB-enabled industrial equipment or diagnostic tools.
Limitations and Concerns:
- Security Vulnerabilities: Designed during the Windows XP era, RNDIS suffers from outdated security practices, making it susceptible to threats like malicious code injection, spoofing, and unauthorized data access.
- Limited Use Cases: Modern alternatives like USB CDC-ECM (Communications Device Class – Ethernet Control Model) or tethering over dedicated Ethernet ports are more secure and widely adopted.
- Deprecation: Due to its vulnerabilities and the availability of better protocols, many systems are moving away from RNDIS. For example, the Linux kernel is planning its complete removal to improve security and reduce potential attack surfaces.
