blob: 5e4681b195404622c8736cab7ef24fdf5945f80f [file] [log] [blame]
// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "permission_broker/deny_claimed_hidraw_device_rule.h"
#include <libudev.h>
#include <string>
#include "base/logging.h"
#include "permission_broker/udev_scopers.h"
namespace permission_broker {
namespace {
const char kLogitechUnifyingReceiverDriver[] = "logitech-djreceiver";
: HidrawSubsystemUdevRule("DenyClaimedHidrawDeviceRule") {}
Rule::Result DenyClaimedHidrawDeviceRule::ProcessHidrawDevice(
struct udev_device *device) {
// For now, treat non-USB HID devices as claimed.
struct udev_device* usb_interface =
device, "usb", "usb_interface");
if (!usb_interface) {
return DENY;
// Add an exception to the rule for Logitech Unifying receiver.
// This hidraw device is a parent of devices that have input
// subsystem. Yet the traffic to those children is not available on
// the hidraw node of the receiver, so it is safe to white-list it.
struct udev_device* hid_parent =
udev_device_get_parent_with_subsystem_devtype(device, "hid", NULL);
if (hid_parent) {
const char* hid_parent_driver = udev_device_get_driver(hid_parent);
if (strcmp(hid_parent_driver, kLogitechUnifyingReceiverDriver) == 0) {
LOG(INFO) << "Found Logitech Unifying receiver. Skipping rule.";
return IGNORE;
std::string usb_interface_path(udev_device_get_syspath(usb_interface));
// Scan all children of the USB interface for subsystems other than generic
// USB or HID. The presence of such subsystems is an indication that the
// device is in use by another driver.
// Because udev lacks the ability to filter an enumeration by arbitrary
// ancestor properties (e.g. "enumerate all nodes with a usb_interface
// ancestor") we have to scan the entire set of devices to find potential
// matches.
struct udev* udev = udev_device_get_udev(device);
ScopedUdevEnumeratePtr enumerate(udev_enumerate_new(udev));
struct udev_list_entry* entry;
udev_enumerate_get_list_entry(enumerate.get())) {
const char* syspath = udev_list_entry_get_name(entry);
ScopedUdevDevicePtr child(udev_device_new_from_syspath(udev, syspath));
struct udev_device* child_usb_interface =
child.get(), "usb", "usb_interface");
if (!child_usb_interface) {
std::string child_usb_interface_path(
// This device shares a USB interface with the hidraw device in question.
// Check its subsystem to see if it should block hidraw access.
if (child_usb_interface_path == usb_interface_path) {
const char* subsystem = udev_device_get_subsystem(child.get());
if (ShouldSiblingSubsystemExcludeHidAccess(subsystem)) {
return DENY;
return IGNORE;
bool DenyClaimedHidrawDeviceRule::ShouldSiblingSubsystemExcludeHidAccess(
const char *subsystem) {
// Return true iff subsystem something other than NULL or generic USB/HID.
return subsystem &&
strcmp(subsystem, "hid") &&
strcmp(subsystem, "hidraw") &&
strcmp(subsystem, "usb") &&
strcmp(subsystem, "usbmisc");
} // namespace permission_broker