Simple Netlink-Based Linux Kernel Module (LKM)

A minimal Linux Loadable Kernel Module (LKM) that communicates with user space via Netlink sockets.

The module receives a message (command + parameters) from a user-space program, performs an action based on the received parameters, and sends a response back to user space.

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Features

• Kernel ↔ User-space communication using Netlink
• Simple command/parameter parsing
• Sends structured responses back to the user-space client
• Minimal and easy-to-read codebase (educational purpose)

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Requirements

• Linux kernel headers for your running kernel
• Build tools: make, gcc
• Root privileges to load/unload kernel modules

On Debian/Ubuntu:

sudo apt update
sudo apt install build-essential linux-headers-$(uname -r)

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Build

make

This should produce a .ko file (e.g., netlink_lkm.ko).

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Load / Unload

Load

sudo insmod netlink_lkm.ko
dmesg | tail -n 50

Unload

sudo rmmod netlink_lkm
dmesg | tail -n 50

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User-space Client

A user-space program sends a Netlink message to the module and prints the received reply. Example (replace with your actual binary name/path):

make user
./user_client "command" "param1=value1" "param2=value2"

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Notes & Safety

Kernel modules run in kernel space. A bug can crash the system. Test in a VM first. Keep code minimal and validate user input. Avoid unsafe memory operations.