Merge tag 'batman-adv-fix-for-davem' of git://git.open-mesh.org/linux-merge

Antonio Quartulli says:

====================
pull request [net]: batman-adv 20140721

here you have two fixes that we have been testing for quite some time
(this is why they arrived a bit late in the rc cycle).

Patch 1) ensures that BLA packets get dropped and not forwarded to the
mesh even if they reach batman-adv within QinQ frames. Forwarding them
into the mesh means messing up with the TT database of other nodes which
can generate all kind of unexpected behaviours during route computation.

Patch 2) avoids a couple of race conditions triggered upon fast VLAN
deletion-addition. Such race conditions are pretty dangerous because
they not only create inconsistencies in the TT database of the nodes
in the network, but such scenario is also unrecoverable (unless
nodes are rebooted).
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 46 insertions, 14 deletions

diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index e7ee65dc20bf..cbd677f48c00 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -448,10 +448,15 @@ out:
  *  possibly free it
  * @softif_vlan: the vlan object to release
  */
-void batadv_softif_vlan_free_ref(struct batadv_softif_vlan *softif_vlan)
+void batadv_softif_vlan_free_ref(struct batadv_softif_vlan *vlan)
 {
-	if (atomic_dec_and_test(&softif_vlan->refcount))
-		kfree_rcu(softif_vlan, rcu);
+	if (atomic_dec_and_test(&vlan->refcount)) {
+		spin_lock_bh(&vlan->bat_priv->softif_vlan_list_lock);
+		hlist_del_rcu(&vlan->list);
+		spin_unlock_bh(&vlan->bat_priv->softif_vlan_list_lock);
+
+		kfree_rcu(vlan, rcu);
+	}
 }
 
 /**
@@ -505,6 +510,7 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
 	if (!vlan)
 		return -ENOMEM;
 
+	vlan->bat_priv = bat_priv;
 	vlan->vid = vid;
 	atomic_set(&vlan->refcount, 1);
 
@@ -516,6 +522,10 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
 		return err;
 	}
 
+	spin_lock_bh(&bat_priv->softif_vlan_list_lock);
+	hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list);
+	spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
+
 	/* add a new TT local entry. This one will be marked with the NOPURGE
 	 * flag
 	 */
@@ -523,10 +533,6 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
 			    bat_priv->soft_iface->dev_addr, vid,
 			    BATADV_NULL_IFINDEX, BATADV_NO_MARK);
 
-	spin_lock_bh(&bat_priv->softif_vlan_list_lock);
-	hlist_add_head_rcu(&vlan->list, &bat_priv->softif_vlan_list);
-	spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
-
 	return 0;
 }
 
@@ -538,18 +544,13 @@ int batadv_softif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid)
 static void batadv_softif_destroy_vlan(struct batadv_priv *bat_priv,
 				       struct batadv_softif_vlan *vlan)
 {
-	spin_lock_bh(&bat_priv->softif_vlan_list_lock);
-	hlist_del_rcu(&vlan->list);
-	spin_unlock_bh(&bat_priv->softif_vlan_list_lock);
-
-	batadv_sysfs_del_vlan(bat_priv, vlan);
-
 	/* explicitly remove the associated TT local entry because it is marked
 	 * with the NOPURGE flag
 	 */
 	batadv_tt_local_remove(bat_priv, bat_priv->soft_iface->dev_addr,
 			       vlan->vid, "vlan interface destroyed", false);
 
+	batadv_sysfs_del_vlan(bat_priv, vlan);
 	batadv_softif_vlan_free_ref(vlan);
 }
 
@@ -567,6 +568,8 @@ static int batadv_interface_add_vid(struct net_device *dev, __be16 proto,
 				    unsigned short vid)
 {
 	struct batadv_priv *bat_priv = netdev_priv(dev);
+	struct batadv_softif_vlan *vlan;
+	int ret;
 
 	/* only 802.1Q vlans are supported.
 	 * batman-adv does not know how to handle other types
@@ -576,7 +579,36 @@ static int batadv_interface_add_vid(struct net_device *dev, __be16 proto,
 
 	vid |= BATADV_VLAN_HAS_TAG;
 
-	return batadv_softif_create_vlan(bat_priv, vid);
+	/* if a new vlan is getting created and it already exists, it means that
+	 * it was not deleted yet. batadv_softif_vlan_get() increases the
+	 * refcount in order to revive the object.
+	 *
+	 * if it does not exist then create it.
+	 */
+	vlan = batadv_softif_vlan_get(bat_priv, vid);
+	if (!vlan)
+		return batadv_softif_create_vlan(bat_priv, vid);
+
+	/* recreate the sysfs object if it was already destroyed (and it should
+	 * be since we received a kill_vid() for this vlan
+	 */
+	if (!vlan->kobj) {
+		ret = batadv_sysfs_add_vlan(bat_priv->soft_iface, vlan);
+		if (ret) {
+			batadv_softif_vlan_free_ref(vlan);
+			return ret;
+		}
+	}
+
+	/* add a new TT local entry. This one will be marked with the NOPURGE
+	 * flag. This must be added again, even if the vlan object already
+	 * exists, because the entry was deleted by kill_vid()
+	 */
+	batadv_tt_local_add(bat_priv->soft_iface,
+			    bat_priv->soft_iface->dev_addr, vid,
+			    BATADV_NULL_IFINDEX, BATADV_NO_MARK);
+
+	return 0;
 }
 
 /**