[PATCH 3.16 188/366] batman-adv: Fix debugfs path for renamed softif

Ben Hutchings
2018-11-11T19:49:05Z

From: Sven Eckelmann <sven@narfation.org>

commit 6da7be7d24b2921f8215473ba7552796dff05fe1 upstream.

batman-adv is creating special debugfs directories in the init
net_namespace for each created soft-interface (batadv net_device). But it
is possible to rename a net_device to a completely different name then the
original one.

It can therefore happen that a user registers a new batadv net_device with
the name "bat0". batman-adv is then also adding a new directory under
$debugfs/batman-adv/ with the name "wlan0".

The user then decides to rename this device to "bat1" and registers a
different batadv device with the name "bat0". batman-adv will then try to
create a directory with the name "bat0" under $debugfs/batman-adv/ again.
But there already exists one with this name under this path and thus this
fails. batman-adv will detect a problem and rollback the registering of
this device.

batman-adv must therefore take care of renaming the debugfs directories for
soft-interfaces whenever it detects such a net_device rename.

Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/batman-adv/debugfs.c | 20 +++++++++++++++++++
net/batman-adv/debugfs.h | 5 +++++
net/batman-adv/hard-interface.c | 34 +++++++++++++++++++++++++++------
3 files changed, 53 insertions(+), 6 deletions(-)

--- a/net/batman-adv/debugfs.c
+++ b/net/batman-adv/debugfs.c
@@ -560,6 +560,26 @@ out:
return -ENOMEM;
}

+/**
+ * batadv_debugfs_rename_meshif() - Fix debugfs path for renamed softif
+ * @dev: net_device which was renamed
+ */
+void batadv_debugfs_rename_meshif(struct net_device *dev)
+{
+ struct batadv_priv *bat_priv = netdev_priv(dev);
+ const char *name = dev->name;
+ struct dentry *dir;
+ struct dentry *d;
+
+ dir = bat_priv->debug_dir;
+ if (!dir)
+ return;
+
+ d = debugfs_rename(dir->d_parent, dir, dir->d_parent, name);
+ if (!d)
+ pr_err("Can't rename debugfs dir to %s\n", name);
+}
+
void batadv_debugfs_del_meshif(struct net_device *dev)
{
struct batadv_priv *bat_priv = netdev_priv(dev);
--- a/net/batman-adv/debugfs.h
+++ b/net/batman-adv/debugfs.h
@@ -25,6 +25,7 @@
void batadv_debugfs_init(void);
void batadv_debugfs_destroy(void);
int batadv_debugfs_add_meshif(struct net_device *dev);
+void batadv_debugfs_rename_meshif(struct net_device *dev);
void batadv_debugfs_del_meshif(struct net_device *dev);
int batadv_debugfs_add_hardif(struct batadv_hard_iface *hard_iface);
void batadv_debugfs_rename_hardif(struct batadv_hard_iface *hard_iface);
@@ -45,6 +46,10 @@ static inline int batadv_debugfs_add_mes
return 0;
}

+static inline void batadv_debugfs_rename_meshif(struct net_device *dev)
+{
+}
+
static inline void batadv_debugfs_del_meshif(struct net_device *dev)
{
}
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -640,6 +640,32 @@ void batadv_hardif_remove_interfaces(voi
rtnl_unlock();
}

+/**
+ * batadv_hard_if_event_softif() - Handle events for soft interfaces
+ * @event: NETDEV_* event to handle
+ * @net_dev: net_device which generated an event
+ *
+ * Return: NOTIFY_* result
+ */
+static int batadv_hard_if_event_softif(unsigned long event,
+ struct net_device *net_dev)
+{
+ struct batadv_priv *bat_priv;
+
+ switch (event) {
+ case NETDEV_REGISTER:
+ batadv_sysfs_add_meshif(net_dev);
+ bat_priv = netdev_priv(net_dev);
+ batadv_softif_create_vlan(bat_priv, BATADV_NO_FLAGS);
+ break;
+ case NETDEV_CHANGENAME:
+ batadv_debugfs_rename_meshif(net_dev);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
static int batadv_hard_if_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
@@ -648,12 +674,8 @@ static int batadv_hard_if_event(struct n
struct batadv_hard_iface *primary_if = NULL;
struct batadv_priv *bat_priv;

- if (batadv_softif_is_valid(net_dev) && event == NETDEV_REGISTER) {
- batadv_sysfs_add_meshif(net_dev);
- bat_priv = netdev_priv(net_dev);
- batadv_softif_create_vlan(bat_priv, BATADV_NO_FLAGS);
- return NOTIFY_DONE;
- }
+ if (batadv_softif_is_valid(net_dev))
+ return batadv_hard_if_event_softif(event, net_dev);

hard_iface = batadv_hardif_get_by_netdev(net_dev);
if (!hard_iface && event == NETDEV_REGISTER)