[B.A.T.M.A.N.] [PATCH maint 1/2] batman-adv: Fix debugfs path for renamed hardif

* [B.A.T.M.A.N.] [PATCH maint 1/2] batman-adv: Fix debugfs path for renamed hardif
@ 2018-06-01 17:24 Sven Eckelmann
  2018-06-01 17:24 ` [B.A.T.M.A.N.] [PATCH maint 2/2] batman-adv: Fix debugfs path for renamed softif Sven Eckelmann
  2018-06-03 13:16 ` [B.A.T.M.A.N.] [PATCH maint 1/2] batman-adv: Fix debugfs path for renamed hardif Sven Eckelmann
  0 siblings, 2 replies; 4+ messages in thread
From: Sven Eckelmann @ 2018-06-01 17:24 UTC (permalink / raw)
  To: b.a.t.m.a.n; +Cc: Sven Eckelmann, John Soros

batman-adv is creating special debugfs directories in the init
net_namespace for each valid hard-interface (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 net_device which gets
the name "wlan0" assigned by default. batman-adv is also adding a new
directory under $debugfs/batman-adv/ with the name "wlan0".

The user then decides to rename this device to "wl_pri" and registers a
different device. The kernel may now decide to use the name "wlan0" again
for this new device. batman-adv will detect it as a valid net_device and
tries to create a directory with the name "wlan0" under
$debugfs/batman-adv/. 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 hard-interfaces whenever it detects such a net_device rename.

Fixes: 3c926a01c8e8 ("batman-adv: add debugfs structure for information per interface")
Reported-by: John Soros <sorosj@gmail.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
Cc: John Soros <sorosj@gmail.com>

You can find a backported version of the patch at 
https://git.open-mesh.org/batman-adv.git/patch/9c24af2f54e7dd138150f2e8c463a15f4fa12b39

 net/batman-adv/debugfs.c        | 20 ++++++++++++++++++++
 net/batman-adv/debugfs.h        |  6 ++++++
 net/batman-adv/hard-interface.c |  3 +++
 3 files changed, 29 insertions(+)

diff --git a/net/batman-adv/debugfs.c b/net/batman-adv/debugfs.c
index 4229b01a..7e5de7b9 100644
--- a/net/batman-adv/debugfs.c
+++ b/net/batman-adv/debugfs.c
@@ -19,6 +19,7 @@
 #include "debugfs.h"
 #include "main.h"
 
+#include <linux/dcache.h>
 #include <linux/debugfs.h>
 #include <linux/err.h>
 #include <linux/errno.h>
@@ -343,6 +344,25 @@ int batadv_debugfs_add_hardif(struct batadv_hard_iface *hard_iface)
 	return -ENOMEM;
 }
 
+/**
+ * batadv_debugfs_rename_hardif() - Fix debugfs path for renamed hardif
+ * @hard_iface: hard interface which was renamed
+ */
+void batadv_debugfs_rename_hardif(struct batadv_hard_iface *hard_iface)
+{
+	const char *name = hard_iface->net_dev->name;
+	struct dentry *dir;
+	struct dentry *d;
+
+	dir = hard_iface->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);
+}
+
 /**
  * batadv_debugfs_del_hardif() - delete the base directory for a hard interface
  *  in debugfs.
diff --git a/net/batman-adv/debugfs.h b/net/batman-adv/debugfs.h
index 37b06969..8538a7a7 100644
--- a/net/batman-adv/debugfs.h
+++ b/net/batman-adv/debugfs.h
@@ -32,6 +32,7 @@ void batadv_debugfs_destroy(void);
 int batadv_debugfs_add_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);
 void batadv_debugfs_del_hardif(struct batadv_hard_iface *hard_iface);
 
 #else
@@ -59,6 +60,11 @@ int batadv_debugfs_add_hardif(struct batadv_hard_iface *hard_iface)
 	return 0;
 }
 
+static inline
+void batadv_debugfs_rename_hardif(struct batadv_hard_iface *hard_iface)
+{
+}
+
 static inline
 void batadv_debugfs_del_hardif(struct batadv_hard_iface *hard_iface)
 {
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index c405d15b..dc2763b1 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -1051,6 +1051,9 @@ static int batadv_hard_if_event(struct notifier_block *this,
 		if (batadv_is_wifi_hardif(hard_iface))
 			hard_iface->num_bcasts = BATADV_NUM_BCASTS_WIRELESS;
 		break;
+	case NETDEV_CHANGENAME:
+		batadv_debugfs_rename_hardif(hard_iface);
+		break;
 	default:
 		break;
 	}
-- 
2.17.0


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