Staging: batman-adv: softif bridge loop avoidance

By connecting multiple batman-adv mesh nodes to the same ethernet
segment a loop can be created when the soft-interface is bridged
into that ethernet segment. A simple visualization of the loop
involving the most common case - a LAN as ethernet segment:

node1  <-- LAN  -->  node2
   |                   |
 wifi  <-- mesh -->  wifi

Packets from the LAN (e.g. ARP broadcasts) will circle forever from
node1 or node2 over the mesh back into the LAN.

This patch adds the functionality to detect other batman-adv nodes
connected to the LAN and select a 'gateway' to talk to the
non-batman-adv devices on this LAN. All traffic from and to the mesh
will be handled by this gateway to avoid the loop. OGMs received via
the soft-interface are interpreted as 'port announcements' to locate
potential batman-adv nodes. The patch can also deal with vlans on
top of batX and offers a list of LAN neighbors via debugfs.

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
[sven.eckelmann@gmx.de: Rework on top of current version]
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 290 insertions, 6 deletions

diff --git a/drivers/staging/batman-adv/soft-interface.c b/drivers/staging/batman-adv/soft-interface.c
index 0e996181daf7..c3313d0616cc 100644
--- a/drivers/staging/batman-adv/soft-interface.c
+++ b/drivers/staging/batman-adv/soft-interface.c
@@ -33,7 +33,9 @@
 #include <linux/slab.h>
 #include <linux/ethtool.h>
 #include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
 #include "unicast.h"
+#include "routing.h"
 
 
 static int bat_get_settings(struct net_device *dev, struct ethtool_cmd *cmd);
@@ -75,6 +77,220 @@ int my_skb_head_push(struct sk_buff *skb, unsigned int len)
 	return 0;
 }
 
+static void softif_neigh_free_ref(struct kref *refcount)
+{
+	struct softif_neigh *softif_neigh;
+
+	softif_neigh = container_of(refcount, struct softif_neigh, refcount);
+	kfree(softif_neigh);
+}
+
+static void softif_neigh_free_rcu(struct rcu_head *rcu)
+{
+	struct softif_neigh *softif_neigh;
+
+	softif_neigh = container_of(rcu, struct softif_neigh, rcu);
+	kref_put(&softif_neigh->refcount, softif_neigh_free_ref);
+}
+
+void softif_neigh_purge(struct bat_priv *bat_priv)
+{
+	struct softif_neigh *softif_neigh, *softif_neigh_tmp;
+	struct hlist_node *node, *node_tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bat_priv->softif_neigh_lock, flags);
+
+	hlist_for_each_entry_safe(softif_neigh, node, node_tmp,
+				  &bat_priv->softif_neigh_list, list) {
+
+		if ((!time_after(jiffies, softif_neigh->last_seen +
+				msecs_to_jiffies(SOFTIF_NEIGH_TIMEOUT))) &&
+		    (atomic_read(&bat_priv->mesh_state) == MESH_ACTIVE))
+			continue;
+
+		hlist_del_rcu(&softif_neigh->list);
+
+		if (bat_priv->softif_neigh == softif_neigh) {
+			bat_dbg(DBG_ROUTES, bat_priv,
+				 "Current mesh exit point '%pM' vanished "
+				 "(vid: %d).\n",
+				 softif_neigh->addr, softif_neigh->vid);
+			softif_neigh_tmp = bat_priv->softif_neigh;
+			bat_priv->softif_neigh = NULL;
+			kref_put(&softif_neigh_tmp->refcount,
+				 softif_neigh_free_ref);
+		}
+
+		call_rcu(&softif_neigh->rcu, softif_neigh_free_rcu);
+	}
+
+	spin_unlock_irqrestore(&bat_priv->softif_neigh_lock, flags);
+}
+
+static struct softif_neigh *softif_neigh_get(struct bat_priv *bat_priv,
+					     uint8_t *addr, short vid)
+{
+	struct softif_neigh *softif_neigh;
+	struct hlist_node *node;
+	unsigned long flags;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(softif_neigh, node,
+				 &bat_priv->softif_neigh_list, list) {
+		if (memcmp(softif_neigh->addr, addr, ETH_ALEN) != 0)
+			continue;
+
+		if (softif_neigh->vid != vid)
+			continue;
+
+		softif_neigh->last_seen = jiffies;
+		goto found;
+	}
+
+	softif_neigh = kzalloc(sizeof(struct softif_neigh), GFP_ATOMIC);
+	if (!softif_neigh)
+		goto out;
+
+	memcpy(softif_neigh->addr, addr, ETH_ALEN);
+	softif_neigh->vid = vid;
+	softif_neigh->last_seen = jiffies;
+	kref_init(&softif_neigh->refcount);
+
+	INIT_HLIST_NODE(&softif_neigh->list);
+	spin_lock_irqsave(&bat_priv->softif_neigh_lock, flags);
+	hlist_add_head_rcu(&softif_neigh->list, &bat_priv->softif_neigh_list);
+	spin_unlock_irqrestore(&bat_priv->softif_neigh_lock, flags);
+
+found:
+	kref_get(&softif_neigh->refcount);
+out:
+	rcu_read_unlock();
+	return softif_neigh;
+}
+
+int softif_neigh_seq_print_text(struct seq_file *seq, void *offset)
+{
+	struct net_device *net_dev = (struct net_device *)seq->private;
+	struct bat_priv *bat_priv = netdev_priv(net_dev);
+	struct softif_neigh *softif_neigh;
+	struct hlist_node *node;
+	size_t buf_size, pos;
+	char *buff;
+
+	if (!bat_priv->primary_if) {
+		return seq_printf(seq, "BATMAN mesh %s disabled - "
+			       "please specify interfaces to enable it\n",
+			       net_dev->name);
+	}
+
+	seq_printf(seq, "Softif neighbor list (%s)\n", net_dev->name);
+
+	buf_size = 1;
+	/* Estimate length for: "   xx:xx:xx:xx:xx:xx\n" */
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(softif_neigh, node,
+				 &bat_priv->softif_neigh_list, list)
+		buf_size += 30;
+	rcu_read_unlock();
+
+	buff = kmalloc(buf_size, GFP_ATOMIC);
+	if (!buff)
+		return -ENOMEM;
+
+	buff[0] = '\0';
+	pos = 0;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(softif_neigh, node,
+				 &bat_priv->softif_neigh_list, list) {
+		pos += snprintf(buff + pos, 31, "%s %pM (vid: %d)\n",
+				bat_priv->softif_neigh == softif_neigh
+				? "=>" : "  ", softif_neigh->addr,
+				softif_neigh->vid);
+	}
+	rcu_read_unlock();
+
+	seq_printf(seq, "%s", buff);
+	kfree(buff);
+	return 0;
+}
+
+static void softif_batman_recv(struct sk_buff *skb, struct net_device *dev,
+			       short vid)
+{
+	struct bat_priv *bat_priv = netdev_priv(dev);
+	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
+	struct batman_packet *batman_packet;
+	struct softif_neigh *softif_neigh, *softif_neigh_tmp;
+
+	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q)
+		batman_packet = (struct batman_packet *)
+					(skb->data + ETH_HLEN + VLAN_HLEN);
+	else
+		batman_packet = (struct batman_packet *)(skb->data + ETH_HLEN);
+
+	if (batman_packet->version != COMPAT_VERSION)
+		goto err;
+
+	if (batman_packet->packet_type != BAT_PACKET)
+		goto err;
+
+	if (!(batman_packet->flags & PRIMARIES_FIRST_HOP))
+		goto err;
+
+	if (is_my_mac(batman_packet->orig))
+		goto err;
+
+	softif_neigh = softif_neigh_get(bat_priv, batman_packet->orig, vid);
+
+	if (!softif_neigh)
+		goto err;
+
+	if (bat_priv->softif_neigh == softif_neigh)
+		goto out;
+
+	/* we got a neighbor but its mac is 'bigger' than ours  */
+	if (memcmp(bat_priv->primary_if->net_dev->dev_addr,
+		   softif_neigh->addr, ETH_ALEN) < 0)
+		goto out;
+
+	/* switch to new 'smallest neighbor' */
+	if ((bat_priv->softif_neigh) &&
+	    (memcmp(softif_neigh->addr, bat_priv->softif_neigh->addr,
+							ETH_ALEN) < 0)) {
+		bat_dbg(DBG_ROUTES, bat_priv,
+			"Changing mesh exit point from %pM (vid: %d) "
+			"to %pM (vid: %d).\n",
+			 bat_priv->softif_neigh->addr,
+			 bat_priv->softif_neigh->vid,
+			 softif_neigh->addr, softif_neigh->vid);
+		softif_neigh_tmp = bat_priv->softif_neigh;
+		bat_priv->softif_neigh = softif_neigh;
+		kref_put(&softif_neigh_tmp->refcount, softif_neigh_free_ref);
+		/* we need to hold the additional reference */
+		goto err;
+	}
+
+	/* close own batX device and use softif_neigh as exit node */
+	if ((!bat_priv->softif_neigh) &&
+	    (memcmp(softif_neigh->addr,
+		    bat_priv->primary_if->net_dev->dev_addr, ETH_ALEN) < 0)) {
+		bat_dbg(DBG_ROUTES, bat_priv,
+			"Setting mesh exit point to %pM (vid: %d).\n",
+			softif_neigh->addr, softif_neigh->vid);
+		bat_priv->softif_neigh = softif_neigh;
+		/* we need to hold the additional reference */
+		goto err;
+	}
+
+out:
+	kref_put(&softif_neigh->refcount, softif_neigh_free_ref);
+err:
+	kfree_skb(skb);
+	return;
+}
+
 static int interface_open(struct net_device *dev)
 {
 	netif_start_queue(dev);
@@ -109,7 +325,6 @@ static int interface_set_mac_addr(struct net_device *dev, void *p)
 	}
 
 	memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
-
 	return 0;
 }
 
@@ -129,13 +344,36 @@ int interface_tx(struct sk_buff *skb, struct net_device *soft_iface)
 	struct ethhdr *ethhdr = (struct ethhdr *)skb->data;
 	struct bat_priv *bat_priv = netdev_priv(soft_iface);
 	struct bcast_packet *bcast_packet;
+	struct vlan_ethhdr *vhdr;
 	int data_len = skb->len, ret;
+	short vid = -1;
 
 	if (atomic_read(&bat_priv->mesh_state) != MESH_ACTIVE)
 		goto dropped;
 
 	soft_iface->trans_start = jiffies;
 
+	switch (ntohs(ethhdr->h_proto)) {
+	case ETH_P_8021Q:
+		vhdr = (struct vlan_ethhdr *)skb->data;
+		vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK;
+
+		if (ntohs(vhdr->h_vlan_encapsulated_proto) != ETH_P_BATMAN)
+			break;
+
+		/* fall through */
+	case ETH_P_BATMAN:
+		softif_batman_recv(skb, soft_iface, vid);
+		goto end;
+	}
+
+	/**
+	 * if we have a another chosen mesh exit node in range
+	 * it will transport the packets to the mesh
+	 */
+	if ((bat_priv->softif_neigh) && (bat_priv->softif_neigh->vid == vid))
+		goto dropped;
+
 	/* TODO: check this for locks */
 	hna_local_add(soft_iface, ethhdr->h_source);
 
@@ -189,16 +427,60 @@ end:
 }
 
 void interface_rx(struct net_device *soft_iface,
-		  struct sk_buff *skb, int hdr_size)
+		  struct sk_buff *skb, struct batman_if *recv_if,
+		  int hdr_size)
 {
-	struct bat_priv *priv = netdev_priv(soft_iface);
+	struct bat_priv *bat_priv = netdev_priv(soft_iface);
+	struct unicast_packet *unicast_packet;
+	struct ethhdr *ethhdr;
+	struct vlan_ethhdr *vhdr;
+	short vid = -1;
+	int ret;
 
 	/* check if enough space is available for pulling, and pull */
 	if (!pskb_may_pull(skb, hdr_size))
 		goto dropped;
 
 	skb_pull_rcsum(skb, hdr_size);
-/*	skb_set_mac_header(skb, -sizeof(struct ethhdr));*/
+	skb_reset_mac_header(skb);
+
+	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+
+	switch (ntohs(ethhdr->h_proto)) {
+	case ETH_P_8021Q:
+		vhdr = (struct vlan_ethhdr *)skb->data;
+		vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK;
+
+		if (ntohs(vhdr->h_vlan_encapsulated_proto) != ETH_P_BATMAN)
+			break;
+
+		/* fall through */
+	case ETH_P_BATMAN:
+		goto dropped;
+	}
+
+	/**
+	 * if we have a another chosen mesh exit node in range
+	 * it will transport the packets to the non-mesh network
+	 */
+	if ((bat_priv->softif_neigh) && (bat_priv->softif_neigh->vid == vid)) {
+		skb_push(skb, hdr_size);
+		unicast_packet = (struct unicast_packet *)skb->data;
+
+		if ((unicast_packet->packet_type != BAT_UNICAST) &&
+		    (unicast_packet->packet_type != BAT_UNICAST_FRAG))
+			goto dropped;
+
+		skb_reset_mac_header(skb);
+
+		memcpy(unicast_packet->dest,
+		       bat_priv->softif_neigh->addr, ETH_ALEN);
+		ret = route_unicast_packet(skb, recv_if, hdr_size);
+		if (ret == NET_RX_DROP)
+			goto dropped;
+
+		goto out;
+	}
 
 	/* skb->dev & skb->pkt_type are set here */
 	if (unlikely(!pskb_may_pull(skb, ETH_HLEN)))
@@ -211,8 +493,8 @@ void interface_rx(struct net_device *soft_iface,
 
 /*	skb->ip_summed = CHECKSUM_UNNECESSARY;*/
 
-	priv->stats.rx_packets++;
-	priv->stats.rx_bytes += skb->len + sizeof(struct ethhdr);
+	bat_priv->stats.rx_packets++;
+	bat_priv->stats.rx_bytes += skb->len + sizeof(struct ethhdr);
 
 	soft_iface->last_rx = jiffies;
 
@@ -221,6 +503,7 @@ void interface_rx(struct net_device *soft_iface,
 
 dropped:
 	kfree_skb(skb);
+out:
 	return;
 }
 
@@ -310,6 +593,7 @@ struct net_device *softif_create(char *name)
 
 	bat_priv->primary_if = NULL;
 	bat_priv->num_ifaces = 0;
+	bat_priv->softif_neigh = NULL;
 
 	ret = sysfs_add_meshif(soft_iface);
 	if (ret < 0)