net/bridge: Add 'hairpin' port forwarding mode

This patch adds a 'hairpin' (also called 'reflective relay') mode port configuration to the Linux Ethernet bridge kernel module. A bridge supporting hairpin forwarding mode can send frames back out through the port the frame was received on. Hairpin mode is required to support basic VEPA (Virtual Ethernet Port Aggregator) capabilities. You can find additional information on VEPA here: http://tech.groups.yahoo.com/group/evb/ http://www.ieee802.org/1/files/public/docs2009/new-hudson-vepa_seminar-20090514d.pdf http://www.internet2.edu/presentations/jt2009jul/20090719-congdon.pdf An additional patch 'bridge-utils: Add 'hairpin' port forwarding mode' is provided to allow configuring hairpin mode from userspace tools. Signed-off-by: Paul Congdon <[email protected]> Signed-off-by: Anna Fischer <[email protected]> Acked-by: Arnd Bergmann <[email protected]> Signed-off-by: David S. Miller <[email protected]>
chewitt · Aug 13, 2009 · 3982d3d · 3982d3d
1 parent 8dd0708
commit 3982d3d
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Showing 4 changed files with 23 additions and 1 deletion.
diff --git a/net/bridge/br_forward.c b/net/bridge/br_forward.c
@@ -22,7 +22,8 @@
 static inline int should_deliver(const struct net_bridge_port *p,
 				 const struct sk_buff *skb)
 {
-	return (skb->dev != p->dev && p->state == BR_STATE_FORWARDING);
+	return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
+		p->state == BR_STATE_FORWARDING);
 }
 
 static inline unsigned packet_length(const struct sk_buff *skb)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
@@ -256,6 +256,7 @@ static struct net_bridge_port *new_nbp(struct net_bridge *br,
 	p->path_cost = port_cost(dev);
 	p->priority = 0x8000 >> BR_PORT_BITS;
 	p->port_no = index;
+	p->flags = 0;
 	br_init_port(p);
 	p->state = BR_STATE_DISABLED;
 	br_stp_port_timer_init(p);

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
@@ -81,6 +81,9 @@ struct net_bridge_port
 	struct timer_list		message_age_timer;
 	struct kobject			kobj;
 	struct rcu_head			rcu;
+
+	unsigned long 			flags;
+#define BR_HAIRPIN_MODE		0x00000001
 };
 
 struct net_bridge

diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
@@ -143,6 +143,22 @@ static ssize_t store_flush(struct net_bridge_port *p, unsigned long v)
 }
 static BRPORT_ATTR(flush, S_IWUSR, NULL, store_flush);
 
+static ssize_t show_hairpin_mode(struct net_bridge_port *p, char *buf)
+{
+	int hairpin_mode = (p->flags & BR_HAIRPIN_MODE) ? 1 : 0;
+	return sprintf(buf, "%d\n", hairpin_mode);
+}
+static ssize_t store_hairpin_mode(struct net_bridge_port *p, unsigned long v)
+{
+	if (v)
+		p->flags |= BR_HAIRPIN_MODE;
+	else
+		p->flags &= ~BR_HAIRPIN_MODE;
+	return 0;
+}
+static BRPORT_ATTR(hairpin_mode, S_IRUGO | S_IWUSR,
+		   show_hairpin_mode, store_hairpin_mode);
+
 static struct brport_attribute *brport_attrs[] = {
 	&brport_attr_path_cost,
 	&brport_attr_priority,
@@ -159,6 +175,7 @@ static struct brport_attribute *brport_attrs[] = {
 	&brport_attr_forward_delay_timer,
 	&brport_attr_hold_timer,
 	&brport_attr_flush,
+	&brport_attr_hairpin_mode,
 	NULL
 };