[PATCH 4/9] driver core: set up ownership of class devices in sysfs

Tyler Hicks tyhicks at canonical.com
Wed Oct 31 00:55:20 UTC 2018

From: Dmitry Torokhov <dmitry.torokhov at gmail.com>

BugLink: https://launchpad.net/bugs/1784501

Plumb in get_ownership() callback for devices belonging to a class so that
they can be created with uid/gid different from global root. This will
allow network devices in a container to belong to container's root and not
global root.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov at gmail.com>
Reviewed-by: Tyler Hicks <tyhicks at canonical.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(cherry picked from commit 9944e894c1266dc8515c82d1ff752d681215526b)
Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
 drivers/base/core.c    | 9 +++++++++
 include/linux/device.h | 5 +++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 6835736daf2d..3e63e0f443fb 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -833,10 +833,19 @@ static const void *device_namespace(struct kobject *kobj)
 	return ns;
+static void device_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
+	struct device *dev = kobj_to_dev(kobj);
+	if (dev->class && dev->class->get_ownership)
+		dev->class->get_ownership(dev, uid, gid);
 static struct kobj_type device_ktype = {
 	.release	= device_release,
 	.sysfs_ops	= &dev_sysfs_ops,
 	.namespace	= device_namespace,
+	.get_ownership	= device_get_ownership,
diff --git a/include/linux/device.h b/include/linux/device.h
index 7d537ae1fee4..b67683738812 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -377,6 +377,9 @@ int subsys_virtual_register(struct bus_type *subsys,
  * @shutdown_pre: Called at shut-down time before driver shutdown.
  * @ns_type:	Callbacks so sysfs can detemine namespaces.
  * @namespace:	Namespace of the device belongs to this class.
+ * @get_ownership: Allows class to specify uid/gid of the sysfs directories
+ *		for the devices belonging to the class. Usually tied to
+ *		device's namespace.
  * @pm:		The default device power management operations of this class.
  * @p:		The private data of the driver core, no one other than the
  *		driver core can touch this.
@@ -406,6 +409,8 @@ struct class {
 	const struct kobj_ns_type_operations *ns_type;
 	const void *(*namespace)(struct device *dev);
+	void (*get_ownership)(struct device *dev, kuid_t *uid, kgid_t *gid);
 	const struct dev_pm_ops *pm;
 	struct subsys_private *p;

More information about the kernel-team mailing list