Add HID-BPF tutorial and implementation for virtual mouse input modification

- Introduced a comprehensive tutorial in README.md explaining how to fix broken HID devices using eBPF without kernel patches.
- Implemented a userspace program (hid-input-modifier.c) that creates a virtual HID mouse using the uhid interface and sends synthetic mouse events.
- Developed a BPF program (hid-input-modifier.bpf.c) that intercepts HID events and modifies mouse movement data, effectively doubling the X and Y movement.
- Created necessary header files (hid_bpf.h, hid_bpf_defs.h, hid_bpf_helpers.h) to define structures and helper functions for the BPF program.
- Added functionality to find and manage the virtual HID device, ensuring seamless integration with the BPF program.

src/41-xdp-tcpdump/README.md

@@ -2,6 +2,8 @@
 
 Extended Berkeley Packet Filter (eBPF) is a revolutionary technology in the Linux kernel that allows developers to run sandboxed programs within the kernel space. It enables powerful networking, security, and tracing capabilities without the need to modify the kernel source code or load kernel modules. This tutorial focuses on using eBPF with the Express Data Path (XDP) to capture TCP header information directly from network packets at the earliest point of ingress.
 
+> The complete source code: <https://github.com/eunomia-bpf/bpf-developer-tutorial/tree/main/src/41-xdp-tcpdump>
+
 ## Capturing TCP Headers with XDP
 
 Capturing network packets is essential for monitoring, debugging, and securing network communications. Traditional tools like `tcpdump` operate in user space and can incur significant overhead. By leveraging eBPF and XDP, we can capture TCP header information directly within the kernel, minimizing overhead and improving performance.