[PATCH v7 8/9] net-sysfs: add queue_change_owner()

[Christian Brauner <christian.brauner@ubuntu.com>]

Add a function to change the owner of the queue entries for a network device
when it is moved between network namespaces.

Currently, when moving network devices between network namespaces the
ownership of the corresponding queue sysfs entries are not changed. This leads
to problems when tools try to operate on the corresponding sysfs files. Fix
this.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
- kbuild test robot <lkp@intel.com> via sparse:
  - Make net_rx_queue_change_owner() static since it's not exported.

/* v3 */
-  Greg Kroah-Hartman <gregkh@linuxfoundation.org>:
   - Add explicit uid/gid parameters.

/* v4 */
unchanged

/* v5 */
unchanged

/* v6 */
unchanged

/* v7 */
unchanged
---
 net/core/net-sysfs.c | 106 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index e19967665cb0..cf0215734ceb 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -944,6 +944,24 @@ static int rx_queue_add_kobject(struct net_device *dev, int index)
 	kobject_put(kobj);
 	return error;
 }
+
+static int rx_queue_change_owner(struct net_device *dev, int index, kuid_t kuid,
+				 kgid_t kgid)
+{
+	struct netdev_rx_queue *queue = dev->_rx + index;
+	struct kobject *kobj = &queue->kobj;
+	int error;
+
+	error = sysfs_change_owner(kobj, kuid, kgid);
+	if (error)
+		return error;
+
+	if (dev->sysfs_rx_queue_group)
+		error = sysfs_group_change_owner(
+			kobj, dev->sysfs_rx_queue_group, kuid, kgid);
+
+	return error;
+}
 #endif /* CONFIG_SYSFS */
 
 int
@@ -981,6 +999,29 @@ net_rx_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
 #endif
 }
 
+static int net_rx_queue_change_owner(struct net_device *dev, int num,
+				     kuid_t kuid, kgid_t kgid)
+{
+#ifdef CONFIG_SYSFS
+	int error = 0;
+	int i;
+
+#ifndef CONFIG_RPS
+	if (!dev->sysfs_rx_queue_group)
+		return 0;
+#endif
+	for (i = 0; i < num; i++) {
+		error = rx_queue_change_owner(dev, i, kuid, kgid);
+		if (error)
+			break;
+	}
+
+	return error;
+#else
+	return 0;
+#endif
+}
+
 #ifdef CONFIG_SYSFS
 /*
  * netdev_queue sysfs structures and functions.
@@ -1486,6 +1527,23 @@ static int netdev_queue_add_kobject(struct net_device *dev, int index)
 	kobject_put(kobj);
 	return error;
 }
+
+static int tx_queue_change_owner(struct net_device *ndev, int index,
+				 kuid_t kuid, kgid_t kgid)
+{
+	struct netdev_queue *queue = ndev->_tx + index;
+	struct kobject *kobj = &queue->kobj;
+	int error;
+
+	error = sysfs_change_owner(kobj, kuid, kgid);
+	if (error)
+		return error;
+
+#ifdef CONFIG_BQL
+	error = sysfs_group_change_owner(kobj, &dql_group, kuid, kgid);
+#endif
+	return error;
+}
 #endif /* CONFIG_SYSFS */
 
 int
@@ -1520,6 +1578,25 @@ netdev_queue_update_kobjects(struct net_device *dev, int old_num, int new_num)
 #endif /* CONFIG_SYSFS */
 }
 
+static int net_tx_queue_change_owner(struct net_device *dev, int num,
+				     kuid_t kuid, kgid_t kgid)
+{
+#ifdef CONFIG_SYSFS
+	int error = 0;
+	int i;
+
+	for (i = 0; i < num; i++) {
+		error = tx_queue_change_owner(dev, i, kuid, kgid);
+		if (error)
+			break;
+	}
+
+	return error;
+#else
+	return 0;
+#endif /* CONFIG_SYSFS */
+}
+
 static int register_queue_kobjects(struct net_device *dev)
 {
 	int error = 0, txq = 0, rxq = 0, real_rx = 0, real_tx = 0;
@@ -1554,6 +1631,31 @@ static int register_queue_kobjects(struct net_device *dev)
 	return error;
 }
 
+static int queue_change_owner(struct net_device *ndev, kuid_t kuid, kgid_t kgid)
+{
+	int error = 0, real_rx = 0, real_tx = 0;
+
+#ifdef CONFIG_SYSFS
+	if (ndev->queues_kset) {
+		error = sysfs_change_owner(&ndev->queues_kset->kobj, kuid, kgid);
+		if (error)
+			return error;
+	}
+	real_rx = ndev->real_num_rx_queues;
+#endif
+	real_tx = ndev->real_num_tx_queues;
+
+	error = net_rx_queue_change_owner(ndev, real_rx, kuid, kgid);
+	if (error)
+		return error;
+
+	error = net_tx_queue_change_owner(ndev, real_tx, kuid, kgid);
+	if (error)
+		return error;
+
+	return 0;
+}
+
 static void remove_queue_kobjects(struct net_device *dev)
 {
 	int real_rx = 0, real_tx = 0;
@@ -1791,6 +1893,10 @@ int netdev_change_owner(struct net_device *ndev, const struct net *net_old,
 	if (error)
 		return error;
 
+	error = queue_change_owner(ndev, new_uid, new_gid);
+	if (error)
+		return error;
+
 	return 0;
 }
 
-- 
2.25.1