FIM-eBPF: File Integrity Monitoring with eBPF

A lightweight eBPF program to monitor file creation and modification events on Linux. This tool leverages eBPF (Extended Berkeley Packet Filter) to trace file operations directly from the kernel, providing high-performance monitoring with minimal overhead.

Features

• Kernel-level Monitoring: Traces file operations (touch, nano, etc.) directly from the kernel.
• CO-RE Support: Designed to work with Compile Once – Run Everywhere (CO-RE) on kernels that support it (Kernel 5.x+).
• Configurable Filtering: Filter events by file path, action, or user via a simple YAML configuration.
• Directory Monitoring: Supports monitoring entire directories recursively. Any file accessed within a monitored directory (e.g., /tmp) will be tracked.
• Low Noise: Filters events in the kernel before they reach userspace, reducing overhead.
• Path Resolution: Handles both absolute and relative paths (e.g., cd /tmp; touch file) correctly by tracking directory inodes in the kernel.

Prerequisites

• Linux Kernel 5.x or higher: Required for CO-RE support (e.g., RHEL 9, Ubuntu 20.04+, etc.).
• Root Privileges: eBPF programs require root access to load into the kernel.

Installation

You can download the latest binaries from the Releases page.

Building from Source

To build the project yourself, you need Go installed.

# Clone the repository
git clone https://github.com/harshavmb/fim-ebpf.git
cd fim-ebpf

# Build the binary
go build -o fim-ebpf .

Usage

1. Create a config.yaml file in the same directory as the binary (or modify the existing one).

   monitored_files:
     - /tmp/testfile
     - /etc/passwd
     - /etc/shadow
     - /tmp ## monitor the entire directory
   ignore_actions:
     - read
     - stat
   ignore_users:
     - root

2. Run the binary with root privileges:

   sudo ./fim-ebpf

Example Output

2025/08/18 07:22:09 Monitoring started. Ctrl+C to exit.
2025/08/18 07:22:37 Event: PID=1745080 UID=6087179 (6087179 (harsha)) CMD=touch FILE=/tmp/testfile FLAGS=00000941 ## actual user
2025/08/18 07:22:54 Event: PID=1745108 UID=0 (0 (root) [Login: 6087179 (harsha)]) CMD=touch FILE=/tmp/testfile FLAGS=00000941 ## even after sudo
2026/01/03 18:55:56 Event: PID=3718310 UID=1002 (1002 (harsha)) CMD=touch FILE=/tmp/testfile ACTION=OPEN FLAGS=00000941 ## monitoring files in a dir

Architecture

The project uses cilium/ebpf for loading and interacting with the eBPF program. The eBPF code runs in the kernel and sends events to the userspace Go program via a ring buffer.