sridhardv/secured-usbip

Purpose and execution model

Secured-USBIP is a GPLv2-derived USB/IP userspace implementation intended as a basis for adding a security protocol. It manages Linux kernel USB/IP drivers: exporting physical USB devices or gadget-backed virtual devices from a server, discovering them remotely, and importing them through a client VHCI controller over TCP (default port 3240).

Primary executables are the usbip management CLI (src/usbip.c) and the server daemon usbipd (src/usbipd.c).

CLI command dispatcher

usbip parses global options and dispatches subcommands to focused command implementations:

• Export lifecycle: src/usbip_bind.c, src/usbip_unbind.c

• Client lifecycle: src/usbip_attach.c, src/usbip_detach.c

• Discovery/status: src/usbip_list.c, src/usbip_port.c

The CLI is the principal control-plane boundary between operators/scripts and kernel-driver sysfs interfaces or the remote USB/IP daemon.

Server daemon and protocol boundary

usbipd accepts TCP USB/IP control connections, enumerates exportable devices, and services attach/import requests. src/usbipd.c owns daemon startup and server behavior; src/usbip_network.c and src/usbip_network.h provide protocol/network operations shared with client-side remote discovery and attachment.

Any security-protocol work is most likely centered at this wire boundary, while preserving compatibility with the kernel USB/IP transport and management flows.

Device export path

For physical USB devices, an operator binds a bus ID to the kernel usbip-host/stub driver. Userspace discovers devices and writes/reads driver state through sysfs-oriented abstractions:

• Generic device and driver operations: libsrc/usbip_device_driver.c, libsrc/usbip_device_driver.h

• Physical host-driver operations: libsrc/usbip_host_driver.c, libsrc/usbip_host_common.c

• Sysfs access: libsrc/sysfs_utils.c

The kernel modules themselves are external prerequisites, not included in this repository: usbip-core, usbip-host, vhci-hcd, and optionally usbip-vudc.

Client import path

usbip attach contacts a remote daemon, requests a bus ID, then attaches the received connection to an available local virtual host-controller port via the VHCI kernel driver. usbip detach removes it; usbip port reports local attachment state.

The VHCI-specific kernel/sysfs boundary is encapsulated by libsrc/vhci_driver.c and consumed by src/usbip_attach.c, src/usbip_detach.c, and src/usbip_port.c. Once attached, ordinary local Linux USB drivers consume the imported device.

Shared models and presentation

Shared USB/IP protocol structures, device metadata, and common operations reside in libsrc/usbip_common.c and libsrc/usbip_common.h. Host enumeration/building of exportable-device information is in libsrc/usbip_host_common.c. USB vendor/product/class naming is resolved through libsrc/names.c, optionally using hwdata USB ID data.

Virtual gadget export

The daemon can also export USB Gadget instances attached to the external usbip-vudc kernel module rather than physical host devices. vudc/vudc_server_example.sh demonstrates the ConfigFS gadget-to-vUDC setup. This path shares daemon/network control flow but relies on gadget ConfigFS and vUDC naming instead of physical bus-ID binding.

Runtime and build dependencies

This is native Linux C software built with Autotools (configure.ac, Makefile.am). Runtime dependencies include libudev for device/sysfs discovery and optional libwrap TCP wrappers for daemon connection policy. The operational environment requires privileged access to sysfs, loaded USB/IP kernel modules, network reachability to TCP/3240, and potentially ConfigFS for gadget export.