USB: make usbdevices export their device nodes instead of using a separate class

o The "real" usb-devices export now a device node which can
  populate /dev/bus/usb.

o The usb_device class is optional now and can be disabled in the
  kernel config. Major/minor of the "real" devices and class devices
  are the same.

o The environment of the usb-device event contains DEVNUM and BUSNUM to
  help udev and get rid of the ugly udev rule we need for the class
  devices.

o The usb-devices and usb-interfaces share the same bus, so I used
  the new "struct device_type" to let these devices identify
  themselves. This also removes the current logic of using a magic
  platform-pointer.
  The name of the device_type is also added to the environment
  which makes it easier to distinguish the different kinds of devices
  on the same subsystem.

  It looks like this:
    add@/devices/pci0000:00/0000:00:1d.1/usb2/2-1
    ACTION=add
    DEVPATH=/devices/pci0000:00/0000:00:1d.1/usb2/2-1
    SUBSYSTEM=usb
    SEQNUM=1533
    MAJOR=189
    MINOR=131
    DEVTYPE=usb_device
    PRODUCT=46d/c03e/2000
    TYPE=0/0/0
    BUSNUM=002
    DEVNUM=004

This udev rule works as a replacement for usb_device class devices:
  SUBSYSTEM=="usb", ACTION=="add", ENV{DEVTYPE}=="usb_device", \
    NAME="bus/usb/$env{BUSNUM}/$env{DEVNUM}", MODE="0644"

Updated patch, which needs the device_type patches in Greg's tree.

I also got a bugzilla assigned for this. :)
  https://bugzilla.novell.com/show_bug.cgi?id=250659


Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/Kconfig

@@ -31,7 +31,30 @@ config USB_DEVICEFS
 	  For the format of the various /proc/bus/usb/ files, please read
 	  <file:Documentation/usb/proc_usb_info.txt>.
 
-	  Most users want to say Y here.
+	  Usbfs files can't handle Access Control Lists (ACL), which are the
+	  default way to grant access to USB devices for untrusted users of a
+	  desktop system. The usbfs functionality is replaced by real
+	  device-nodes managed by udev. These nodes live in /dev/bus/usb and
+	  are used by libusb.
+
+config USB_DEVICE_CLASS
+	bool "USB device class-devices (DEPRECATED)"
+	depends on USB
+	default n
+	---help---
+	  Userspace access to USB devices is granted by device-nodes exported
+	  directly from the usbdev in sysfs. Old versions of the driver
+	  core and udev needed additional class devices to export device nodes.
+
+	  These additional devices are difficult to handle in userspace, if
+	  information about USB interfaces must be available. One device contains
+	  the device node, the other device contains the interface data. Both
+	  devices are at the same level in sysfs (siblings) and one can't access
+	  the other. The device node created directly by the usbdev is the parent
+	  device of the interface and therefore easily accessible from the interface
+	  event.
+
+	  This option provides backward compatibility if needed.
 
 config USB_DYNAMIC_MINORS
 	bool "Dynamic USB minor allocation (EXPERIMENTAL)"

drivers/usb/core/devio.c

@@ -57,7 +57,6 @@
 
 #define USB_MAXBUS			64
 #define USB_DEVICE_MAX			USB_MAXBUS * 128
-static struct class *usb_device_class;
 
 /* Mutual exclusion for removal, open, and release */
 DEFINE_MUTEX(usbfs_mutex);
@@ -514,22 +513,25 @@ static int check_ctrlrecip(struct dev_state *ps, unsigned int requesttype, unsig
 	return ret;
 }
 
-static struct usb_device *usbdev_lookup_minor(int minor)
+static int __match_minor(struct device *dev, void *data)
 {
-	struct device *device;
-	struct usb_device *udev = NULL;
+	int minor = *((int *)data);
 
-	down(&usb_device_class->sem);
-	list_for_each_entry(device, &usb_device_class->devices, node) {
-		if (device->devt == MKDEV(USB_DEVICE_MAJOR, minor)) {
-			udev = device->platform_data;
-			break;
-		}
-	}
-	up(&usb_device_class->sem);
+	if (dev->devt == MKDEV(USB_DEVICE_MAJOR, minor))
+		return 1;
+	return 0;
+}
 
-	return udev;
-};
+static struct usb_device *usbdev_lookup_by_minor(int minor)
+{
+	struct device *dev;
+
+	dev = bus_find_device(&usb_bus_type, NULL, &minor, __match_minor);
+	if (!dev)
+		return NULL;
+	put_device(dev);
+	return container_of(dev, struct usb_device, dev);
+}
 
 /*
  * file operations
@@ -548,11 +550,14 @@ static int usbdev_open(struct inode *inode, struct file *file)
 		goto out;
 
 	ret = -ENOENT;
-	/* check if we are called from a real node or usbfs */
+	/* usbdev device-node */
 	if (imajor(inode) == USB_DEVICE_MAJOR)
-		dev = usbdev_lookup_minor(iminor(inode));
+		dev = usbdev_lookup_by_minor(iminor(inode));
+#ifdef CONFIG_USB_DEVICEFS
+	/* procfs file */
 	if (!dev)
 		dev = inode->i_private;
+#endif
 	if (!dev)
 		goto out;
 	ret = usb_autoresume_device(dev);
@@ -1570,7 +1575,7 @@ static unsigned int usbdev_poll(struct file *file, struct poll_table_struct *wai
 	return mask;
 }
 
-const struct file_operations usbfs_device_file_operations = {
+const struct file_operations usbdev_file_operations = {
 	.llseek =	usbdev_lseek,
 	.read =		usbdev_read,
 	.poll =		usbdev_poll,
@@ -1579,50 +1584,53 @@ const struct file_operations usbfs_device_file_operations = {
 	.release =	usbdev_release,
 };
 
-static int usbdev_add(struct usb_device *dev)
+#ifdef CONFIG_USB_DEVICE_CLASS
+static struct class *usb_classdev_class;
+
+static int usb_classdev_add(struct usb_device *dev)
 {
 	int minor = ((dev->bus->busnum-1) * 128) + (dev->devnum-1);
 
-	dev->usbfs_dev = device_create(usb_device_class, &dev->dev,
+	dev->usb_classdev = device_create(usb_classdev_class, &dev->dev,
 				MKDEV(USB_DEVICE_MAJOR, minor),
 				"usbdev%d.%d", dev->bus->busnum, dev->devnum);
-	if (IS_ERR(dev->usbfs_dev))
-		return PTR_ERR(dev->usbfs_dev);
+	if (IS_ERR(dev->usb_classdev))
+		return PTR_ERR(dev->usb_classdev);
 
-	dev->usbfs_dev->platform_data = dev;
 	return 0;
 }
 
-static void usbdev_remove(struct usb_device *dev)
+static void usb_classdev_remove(struct usb_device *dev)
 {
-	device_unregister(dev->usbfs_dev);
+	device_unregister(dev->usb_classdev);
 }
 
-static int usbdev_notify(struct notifier_block *self, unsigned long action,
-			 void *dev)
+static int usb_classdev_notify(struct notifier_block *self,
+			       unsigned long action, void *dev)
 {
 	switch (action) {
 	case USB_DEVICE_ADD:
-		if (usbdev_add(dev))
+		if (usb_classdev_add(dev))
 			return NOTIFY_BAD;
 		break;
 	case USB_DEVICE_REMOVE:
-		usbdev_remove(dev);
+		usb_classdev_remove(dev);
 		break;
 	}
 	return NOTIFY_OK;
 }
 
 static struct notifier_block usbdev_nb = {
-	.notifier_call = 	usbdev_notify,
+	.notifier_call = 	usb_classdev_notify,
 };
+#endif
 
 static struct cdev usb_device_cdev = {
 	.kobj   = {.name = "usb_device", },
 	.owner  = THIS_MODULE,
 };
 
-int __init usbdev_init(void)
+int __init usb_devio_init(void)
 {
 	int retval;
 
@@ -1632,38 +1640,38 @@ int __init usbdev_init(void)
 		err("unable to register minors for usb_device");
 		goto out;
 	}
-	cdev_init(&usb_device_cdev, &usbfs_device_file_operations);
+	cdev_init(&usb_device_cdev, &usbdev_file_operations);
 	retval = cdev_add(&usb_device_cdev, USB_DEVICE_DEV, USB_DEVICE_MAX);
 	if (retval) {
 		err("unable to get usb_device major %d", USB_DEVICE_MAJOR);
 		goto error_cdev;
 	}
-	usb_device_class = class_create(THIS_MODULE, "usb_device");
-	if (IS_ERR(usb_device_class)) {
+#ifdef CONFIG_USB_DEVICE_CLASS
+	usb_classdev_class = class_create(THIS_MODULE, "usb_device");
+	if (IS_ERR(usb_classdev_class)) {
 		err("unable to register usb_device class");
-		retval = PTR_ERR(usb_device_class);
-		goto error_class;
+		retval = PTR_ERR(usb_classdev_class);
+		cdev_del(&usb_device_cdev);
+		usb_classdev_class = NULL;
+		goto out;
 	}
 
 	usb_register_notify(&usbdev_nb);
-
+#endif
 out:
 	return retval;
 
-error_class:
-	usb_device_class = NULL;
-	cdev_del(&usb_device_cdev);
-
 error_cdev:
 	unregister_chrdev_region(USB_DEVICE_DEV, USB_DEVICE_MAX);
 	goto out;
 }
 
-void usbdev_cleanup(void)
+void usb_devio_cleanup(void)
 {
+#ifdef CONFIG_USB_DEVICE_CLASS
 	usb_unregister_notify(&usbdev_nb);
-	class_destroy(usb_device_class);
+	class_destroy(usb_classdev_class);
+#endif
 	cdev_del(&usb_device_cdev);
 	unregister_chrdev_region(USB_DEVICE_DEV, USB_DEVICE_MAX);
 }
-

drivers/usb/core/driver.c

@@ -574,23 +574,10 @@ static int usb_device_match(struct device *dev, struct device_driver *drv)
 }
 
 #ifdef	CONFIG_HOTPLUG
-
-/*
- * This sends an uevent to userspace, typically helping to load driver
- * or other modules, configure the device, and more.  Drivers can provide
- * a MODULE_DEVICE_TABLE to help with module loading subtasks.
- *
- * We're called either from khubd (the typical case) or from root hub
- * (init, kapmd, modprobe, rmmod, etc), but the agents need to handle
- * delays in event delivery.  Use sysfs (and DEVPATH) to make sure the
- * device (and this configuration!) are still present.
- */
 static int usb_uevent(struct device *dev, char **envp, int num_envp,
 		      char *buffer, int buffer_size)
 {
-	struct usb_interface *intf;
 	struct usb_device *usb_dev;
-	struct usb_host_interface *alt;
 	int i = 0;
 	int length = 0;
 
@@ -600,13 +587,11 @@ static int usb_uevent(struct device *dev, char **envp, int num_envp,
 	/* driver is often null here; dev_dbg() would oops */
 	pr_debug ("usb %s: uevent\n", dev->bus_id);
 
-	if (is_usb_device(dev)) {
+	if (is_usb_device(dev))
 		usb_dev = to_usb_device(dev);
-		alt = NULL;
-	} else {
-		intf = to_usb_interface(dev);
+	else {
+		struct usb_interface *intf = to_usb_interface(dev);
 		usb_dev = interface_to_usbdev(intf);
-		alt = intf->cur_altsetting;
 	}
 
 	if (usb_dev->devnum < 0) {
@@ -621,9 +606,7 @@ static int usb_uevent(struct device *dev, char **envp, int num_envp,
 #ifdef	CONFIG_USB_DEVICEFS
 	/* If this is available, userspace programs can directly read
 	 * all the device descriptors we don't tell them about.  Or
-	 * even act as usermode drivers.
-	 *
-	 * FIXME reduce hardwired intelligence here
+	 * act as usermode drivers.
 	 */
 	if (add_uevent_var(envp, num_envp, &i,
 			   buffer, buffer_size, &length,
@@ -650,44 +633,29 @@ static int usb_uevent(struct device *dev, char **envp, int num_envp,
 			   usb_dev->descriptor.bDeviceProtocol))
 		return -ENOMEM;
 
-	if (!is_usb_device(dev)) {
-
-		if (add_uevent_var(envp, num_envp, &i,
+	if (add_uevent_var(envp, num_envp, &i,
 			   buffer, buffer_size, &length,
-			   "INTERFACE=%d/%d/%d",
-			   alt->desc.bInterfaceClass,
-			   alt->desc.bInterfaceSubClass,
-			   alt->desc.bInterfaceProtocol))
-			return -ENOMEM;
+			   "BUSNUM=%03d",
+			   usb_dev->bus->busnum))
+		return -ENOMEM;
 
-		if (add_uevent_var(envp, num_envp, &i,
+	if (add_uevent_var(envp, num_envp, &i,
 			   buffer, buffer_size, &length,
-			   "MODALIAS=usb:v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02Xic%02Xisc%02Xip%02X",
-			   le16_to_cpu(usb_dev->descriptor.idVendor),
-			   le16_to_cpu(usb_dev->descriptor.idProduct),
-			   le16_to_cpu(usb_dev->descriptor.bcdDevice),
-			   usb_dev->descriptor.bDeviceClass,
-			   usb_dev->descriptor.bDeviceSubClass,
-			   usb_dev->descriptor.bDeviceProtocol,
-			   alt->desc.bInterfaceClass,
-			   alt->desc.bInterfaceSubClass,
-			   alt->desc.bInterfaceProtocol))
-			return -ENOMEM;
-	}
+			   "DEVNUM=%03d",
+			   usb_dev->devnum))
+		return -ENOMEM;
 
 	envp[i] = NULL;
-
 	return 0;
 }
 
 #else
 
 static int usb_uevent(struct device *dev, char **envp,
-			int num_envp, char *buffer, int buffer_size)
+		      int num_envp, char *buffer, int buffer_size)
 {
 	return -ENODEV;
 }
-
 #endif	/* CONFIG_HOTPLUG */
 
 /**

drivers/usb/core/hub.c

@@ -1367,11 +1367,15 @@ int usb_new_device(struct usb_device *udev)
 	}
 #endif
 
+	/* export the usbdev device-node for libusb */
+	udev->dev.devt = MKDEV(USB_DEVICE_MAJOR,
+			(((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
+
 	/* Register the device.  The device driver is responsible
-	 * for adding the device files to usbfs and sysfs and for
-	 * configuring the device.
+	 * for adding the device files to sysfs and for configuring
+	 * the device.
 	 */
-	err = device_add (&udev->dev);
+	err = device_add(&udev->dev);
 	if (err) {
 		dev_err(&udev->dev, "can't device_add, error %d\n", err);
 		goto fail;

drivers/usb/core/inode.c

@@ -662,7 +662,7 @@ static void usbfs_add_device(struct usb_device *dev)
 	sprintf (name, "%03d", dev->devnum);
 	dev->usbfs_dentry = fs_create_file (name, devmode | S_IFREG,
 					    dev->bus->usbfs_dentry, dev,
-					    &usbfs_device_file_operations,
+					    &usbdev_file_operations,
 					    devuid, devgid);
 	if (dev->usbfs_dentry == NULL) {
 		err ("error creating usbfs device entry");

drivers/usb/core/message.c

@@ -1305,7 +1305,7 @@ int usb_reset_configuration(struct usb_device *dev)
 	return 0;
 }
 
-static void release_interface(struct device *dev)
+void usb_release_interface(struct device *dev)
 {
 	struct usb_interface *intf = to_usb_interface(dev);
 	struct usb_interface_cache *intfc =
@@ -1315,6 +1315,67 @@ static void release_interface(struct device *dev)
 	kfree(intf);
 }
 
+#ifdef	CONFIG_HOTPLUG
+static int usb_if_uevent(struct device *dev, char **envp, int num_envp,
+		 char *buffer, int buffer_size)
+{
+	struct usb_device *usb_dev;
+	struct usb_interface *intf;
+	struct usb_host_interface *alt;
+	int i = 0;
+	int length = 0;
+
+	if (!dev)
+		return -ENODEV;
+
+	/* driver is often null here; dev_dbg() would oops */
+	pr_debug ("usb %s: uevent\n", dev->bus_id);
+
+	intf = to_usb_interface(dev);
+	usb_dev = interface_to_usbdev(intf);
+	alt = intf->cur_altsetting;
+
+	if (add_uevent_var(envp, num_envp, &i,
+		   buffer, buffer_size, &length,
+		   "INTERFACE=%d/%d/%d",
+		   alt->desc.bInterfaceClass,
+		   alt->desc.bInterfaceSubClass,
+		   alt->desc.bInterfaceProtocol))
+		return -ENOMEM;
+
+	if (add_uevent_var(envp, num_envp, &i,
+		   buffer, buffer_size, &length,
+		   "MODALIAS=usb:v%04Xp%04Xd%04Xdc%02Xdsc%02Xdp%02Xic%02Xisc%02Xip%02X",
+		   le16_to_cpu(usb_dev->descriptor.idVendor),
+		   le16_to_cpu(usb_dev->descriptor.idProduct),
+		   le16_to_cpu(usb_dev->descriptor.bcdDevice),
+		   usb_dev->descriptor.bDeviceClass,
+		   usb_dev->descriptor.bDeviceSubClass,
+		   usb_dev->descriptor.bDeviceProtocol,
+		   alt->desc.bInterfaceClass,
+		   alt->desc.bInterfaceSubClass,
+		   alt->desc.bInterfaceProtocol))
+		return -ENOMEM;
+
+	envp[i] = NULL;
+	return 0;
+}
+
+#else
+
+static int usb_if_uevent(struct device *dev, char **envp,
+			 int num_envp, char *buffer, int buffer_size)
+{
+	return -ENODEV;
+}
+#endif	/* CONFIG_HOTPLUG */
+
+struct device_type usb_if_device_type = {
+	.name =		"usb_interface",
+	.release =	usb_release_interface,
+	.uevent =	usb_if_uevent,
+};
+
 /*
  * usb_set_configuration - Makes a particular device setting be current
  * @dev: the device whose configuration is being updated
@@ -1478,8 +1539,8 @@ free_interfaces:
 		intf->dev.parent = &dev->dev;
 		intf->dev.driver = NULL;
 		intf->dev.bus = &usb_bus_type;
+		intf->dev.type = &usb_if_device_type;
 		intf->dev.dma_mask = dev->dev.dma_mask;
-		intf->dev.release = release_interface;
 		device_initialize (&intf->dev);
 		mark_quiesced(intf);
 		sprintf (&intf->dev.bus_id[0], "%d-%s:%d.%d",

drivers/usb/core/usb.c

@@ -197,6 +197,11 @@ static void usb_release_dev(struct device *dev)
 	kfree(udev);
 }
 
+struct device_type usb_device_type = {
+	.name =		"usb_device",
+	.release =	usb_release_dev,
+};
+
 #ifdef	CONFIG_PM
 
 static int ksuspend_usb_init(void)
@@ -247,13 +252,10 @@ usb_alloc_dev(struct usb_device *parent, struct usb_bus *bus, unsigned port1)
 
 	device_initialize(&dev->dev);
 	dev->dev.bus = &usb_bus_type;
+	dev->dev.type = &usb_device_type;
 	dev->dev.dma_mask = bus->controller->dma_mask;
-	dev->dev.release = usb_release_dev;
 	dev->state = USB_STATE_ATTACHED;
 
-	/* This magic assignment distinguishes devices from interfaces */
-	dev->dev.platform_data = &usb_generic_driver;
-
 	INIT_LIST_HEAD(&dev->ep0.urb_list);
 	dev->ep0.desc.bLength = USB_DT_ENDPOINT_SIZE;
 	dev->ep0.desc.bDescriptorType = USB_DT_ENDPOINT;
@@ -882,9 +884,9 @@ static int __init usb_init(void)
 	retval = usb_register(&usbfs_driver);
 	if (retval)
 		goto driver_register_failed;
-	retval = usbdev_init();
+	retval = usb_devio_init();
 	if (retval)
-		goto usbdevice_init_failed;
+		goto usb_devio_init_failed;
 	retval = usbfs_init();
 	if (retval)
 		goto fs_init_failed;
@@ -899,8 +901,8 @@ static int __init usb_init(void)
 hub_init_failed:
 	usbfs_cleanup();
 fs_init_failed:
-	usbdev_cleanup();
-usbdevice_init_failed:
+	usb_devio_cleanup();
+usb_devio_init_failed:
 	usb_deregister(&usbfs_driver);
 driver_register_failed:
 	usb_major_cleanup();
@@ -927,7 +929,7 @@ static void __exit usb_exit(void)
 	usb_major_cleanup();
 	usbfs_cleanup();
 	usb_deregister(&usbfs_driver);
-	usbdev_cleanup();
+	usb_devio_cleanup();
 	usb_hub_cleanup();
 	usb_host_cleanup();
 	bus_unregister(&usb_bus_type);

drivers/usb/core/usb.h

@@ -78,15 +78,13 @@ static inline int usb_autoresume_device(struct usb_device *udev)
 
 extern struct workqueue_struct *ksuspend_usb_wq;
 extern struct bus_type usb_bus_type;
+extern struct device_type usb_device_type;
+extern struct device_type usb_if_device_type;
 extern struct usb_device_driver usb_generic_driver;
 
-/* Here's how we tell apart devices and interfaces.  Luckily there's
- * no such thing as a platform USB device, so we can steal the use
- * of the platform_data field. */
-
 static inline int is_usb_device(const struct device *dev)
 {
-	return dev->platform_data == &usb_generic_driver;
+	return dev->type == &usb_device_type;
 }
 
 /* Do the same for device drivers and interface drivers. */
@@ -122,11 +120,11 @@ extern const char *usbcore_name;
 extern struct mutex usbfs_mutex;
 extern struct usb_driver usbfs_driver;
 extern const struct file_operations usbfs_devices_fops;
-extern const struct file_operations usbfs_device_file_operations;
+extern const struct file_operations usbdev_file_operations;
 extern void usbfs_conn_disc_event(void);
 
-extern int usbdev_init(void);
-extern void usbdev_cleanup(void);
+extern int usb_devio_init(void);
+extern void usb_devio_cleanup(void);
 
 struct dev_state {
 	struct list_head list;      /* state list */

include/linux/usb.h

@@ -299,8 +299,9 @@ struct usb_bus {
 	int bandwidth_int_reqs;		/* number of Interrupt requests */
 	int bandwidth_isoc_reqs;	/* number of Isoc. requests */
 
+#ifdef CONFIG_USB_DEVICEFS
 	struct dentry *usbfs_dentry;	/* usbfs dentry entry for the bus */
-
+#endif
 	struct class_device *class_dev;	/* class device for this bus */
 
 #if defined(CONFIG_USB_MON)
@@ -373,9 +374,12 @@ struct usb_device {
 	char *serial;			/* iSerialNumber string, if present */
 
 	struct list_head filelist;
-	struct device *usbfs_dev;
+#ifdef CONFIG_USB_DEVICE_CLASS
+	struct device *usb_classdev;
+#endif
+#ifdef CONFIG_USB_DEVICEFS
 	struct dentry *usbfs_dentry;	/* usbfs dentry entry for the device */
-
+#endif
 	/*
 	 * Child devices - these can be either new devices
 	 * (if this is a hub device), or different instances