Linux USB filter kernel module example

README.md

Linux USB filter module

• Build: make -C /lib/modules/$(uname -r)/build M=$(pwd) modules
• Install:sudo insmod usb_filter.ko
• Test: dmesg
• Remove: sudo rmmod usb_filter

usb_filter.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/usb.h>

static struct usb_device_id blacklist[] = {
    { USB_DEVICE(0x1234, 0x5678) },  // Example blacklist entry
    { }  // Terminating entry
};
MODULE_DEVICE_TABLE(usb, blacklist);

static int is_device_blacklisted(struct usb_device *dev) {
    struct usb_device_id *id;

    for (id = blacklist; id->match_flags != 0; id++) {
        if (id->idVendor == le16_to_cpu(dev->descriptor.idVendor) &&
            id->idProduct == le16_to_cpu(dev->descriptor.idProduct)) {
            return 1;  // Device is blacklisted
        }
    }

    return 0;  // Device is not blacklisted
}

static int usb_filter_probe(struct usb_interface *interface, const struct usb_device_id *id) {
    struct usb_device *dev = interface_to_usbdev(interface);

    if (is_device_blacklisted(dev)) {
        printk(KERN_INFO "USB device (%04X:%04X) is blacklisted\n",
            le16_to_cpu(dev->descriptor.idVendor),
            le16_to_cpu(dev->descriptor.idProduct));
        return -ENODEV;  // Reject the device
    }

    // Continue handling the device as needed

    return 0;  // Success
}

static void usb_filter_disconnect(struct usb_interface *interface) {
    // Handle device disconnect event
}

static struct usb_driver usb_filter_driver = {
    .name = "usb_filter",
    .probe = usb_filter_probe,
    .disconnect = usb_filter_disconnect,
    .id_table = blacklist,
};

static int __init usb_filter_init(void) {
    int result = usb_register(&usb_filter_driver);
    if (result < 0) {
        printk(KERN_ERR "Failed to register USB filter driver: %d\n", result);
        return result;
    }

    printk(KERN_INFO "USB filter driver registered\n");
    return 0;  // Success
}

static void __exit usb_filter_exit(void) {
    usb_deregister(&usb_filter_driver);
    printk(KERN_INFO "USB filter driver unregistered\n");
}

module_init(usb_filter_init);
module_exit(usb_filter_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("USB filter kernel module");