Overview

This repository organizes a 'test lab' to build and run xdp programs. It creates 3 machines based on alpine:

• a xdp virtual machine (qemu)
• a server (podman)
• a client (podman)

Connected by two bridges:

• br-wan (server, xdp)
• br-lan (xdp, client)

With this we can guarantee that all traffic from client goes through the xdp machine. Tests can be designed from client to server or from client to the internet.

+--------+  br-wan  +-----+  br-lan  +--------+
| server |<----+--->| xdp |<-------->| client |
+--------+     |    +-----+          +--------+
               |
               | iptables (masquerade)
               |
+----------+   |
| internet |<--+
+----------+

eXpress Data Path (XDP)

Express Data Path is a linux infrastructure to execute programs on packets before they are handled by the regular TCP/IP network stack. This allows for earlier drops and redirects of specific packets resulting in a higher network troughput.

Application

A sample application is provided to interact with the eBPF programs. It installs the eBPF programs in XDP, setups:

• loads a eBPF program
• epoll loop with a hook interactive command line
• generic netlink sample to communicate with the included kernel module
• timerfd (for periodic interactions of ebpf maps)
• lua (to trigger dynamic userspace functionality from kernel)

Kernel Module

A sample module is provided to interact with the generic Netlink from the kernel side, setups:

• echo request
• echo reply

eBPF programs

A pair sample programs to pass and to drop packages is also provided.

Build and Run

This step will build a kernel, module, application and an initramfs based on alpine linux. You will have a kernel and an rootfs.img with everything ready to run in qemu.

• details of the kernel can be found in config.mk and script/qemu.config.
• details of the initramfs image can be found in script/cmd, function initrd_init.

make buildr cmd=all
make buildr cmd=buildr-rootfs
sudo sh script/network_init

• Only make qemu is necessary after the first setup, it should rebuild the application, kernel modules and image as necessary.

make qemu

• To only rebuild the application, you can issue the command:

make buildr cmd=all

tmux

A tmux script is provided as an automated way to run the test environment. It creates a pane for each of the qemu, client and server machines in the following layout:

./script/cmd tmux_run

+---------------+
| $    | xdp    |
|      +--------+
|      | server |
|      +--------+
|      | client |
+---------------+