@@ -646,3 +646,63 @@ int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid,
return error;
}
EXPORT_SYMBOL_GPL(sysfs_file_change_owner);
+
+/**
+ * sysfs_change_owner - change owner of the given object.
+ * @kobj: object.
+ * @kuid: new owner's kuid
+ * @kgid: new owner's kgid
+ *
+ * Change the owner of the default directory, files, groups, and attributes of
+ * @kobj to @kuid/@kgid. Note that sysfs_change_owner mirrors how the sysfs
+ * entries for a kobject are added by driver core. In summary,
+ * sysfs_change_owner() takes care of the default directory entry for @kobj,
+ * the default attributes associated with the ktype of @kobj and the default
+ * attributes associated with the ktype of @kobj.
+ * Additional properties not added by driver core have to be changed by the
+ * driver or subsystem which created them. This is similar to how
+ * driver/subsystem specific entries are removed.
+ *
+ * Returns 0 on success or error code on failure.
+ */
+int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid)
+{
+ int error;
+ const struct kobj_type *ktype;
+
+ if (!kobj->state_in_sysfs)
+ return -EINVAL;
+
+ /* Change the owner of the kobject itself. */
+ error = internal_change_owner(kobj->sd, kuid, kgid);
+ if (error)
+ return error;
+
+ ktype = get_ktype(kobj);
+ if (ktype) {
+ struct attribute **kattr;
+
+ /*
+ * Change owner of the default attributes associated with the
+ * ktype of @kobj.
+ */
+ for (kattr = ktype->default_attrs; kattr && *kattr; kattr++) {
+ error = sysfs_file_change_owner(kobj, (*kattr)->name,
+ kuid, kgid);
+ if (error)
+ return error;
+ }
+
+ /*
+ * Change owner of the default groups associated with the
+ * ktype of @kobj.
+ */
+ error = sysfs_groups_change_owner(kobj, ktype->default_groups,
+ kuid, kgid);
+ if (error)
+ return error;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(sysfs_change_owner);
@@ -312,6 +312,7 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn)
int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid,
kgid_t kgid);
+int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid);
int sysfs_link_change_owner(struct kobject *kobj, struct kobject *targ,
const char *name, kuid_t kuid, kgid_t kgid);
int sysfs_groups_change_owner(struct kobject *kobj,
@@ -548,6 +549,11 @@ static inline int sysfs_link_change_owner(struct kobject *kobj,
return 0;
}
+static inline int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid)
+{
+ return 0;
+}
+
static inline int sysfs_groups_change_owner(struct kobject *kobj,
const struct attribute_group **groups,
kuid_t kuid, kgid_t kgid)
Add a helper to change the owner of sysfs objects. This function will be used to correctly account for kobject ownership changes, e.g. when moving network devices between network namespaces. This mirrors how a kobject is added through driver core which in its guts is done via kobject_add_internal() which in summary creates the main directory via create_dir(), populates that directory with the groups associated with the ktype of the kobject (if any) and populates the directory with the basic attributes associated with the ktype of the kobject (if any). These are the basic steps that are associated with adding a kobject in sysfs. Any additional properties are added by the specific subsystem itself (not by driver core) after it has registered the device. So for the example of network devices, a network device will e.g. register a queue subdirectory under the basic sysfs directory for the network device and than further subdirectories within that queues subdirectory. But that is all specific to network devices and they call the corresponding sysfs functions to do that directly when they create those queue objects. So anything that a subsystem adds outside of what driver core does must also be changed by it (That's already true for removal of files it created outside of driver core.) and it's the same for ownership changes. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- /* v2 */ - Greg Kroah-Hartman <gregkh@linuxfoundation.org>: - Add comment how ownership of sysfs object is changed. /* v3 */ - Greg Kroah-Hartman <gregkh@linuxfoundation.org>: - Add explicit uid/gid parameters. /* v4 */ - Greg Kroah-Hartman <gregkh@linuxfoundation.org>: - Change the ownership of the kobject itself directly in sysfs_change_owner() and do not rely on separate function to do that. - Add more documentation. --- fs/sysfs/file.c | 60 +++++++++++++++++++++++++++++++++++++++++++ include/linux/sysfs.h | 6 +++++ 2 files changed, 66 insertions(+)