3 files changed, 55 insertions, 5 deletions

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index c95cd93acf29..078709233bc4 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -70,6 +70,7 @@
  *                                      bonding can change the skb before
  *                                      sending (e.g. insert 8021q tag).
  *              Harald Welte    :       convert to make use of jenkins hash
+ *              Jesper D. Brouer:       Proxy ARP PVLAN RFC 3069 support.
  */
 
 #include <linux/module.h>
@@ -524,12 +525,15 @@ int arp_bind_neighbour(struct dst_entry *dst)
 /*
  * Check if we can use proxy ARP for this path
  */
-
-static inline int arp_fwd_proxy(struct in_device *in_dev, struct rtable *rt)
+static inline int arp_fwd_proxy(struct in_device *in_dev,
+                                struct net_device *dev, struct rtable *rt)
 {
         struct in_device *out_dev;
         int imi, omi = -1;
 
+        if (rt->u.dst.dev == dev)
+                return 0;
+
         if (!IN_DEV_PROXY_ARP(in_dev))
                 return 0;
 
@@ -548,6 +552,43 @@ static inline int arp_fwd_proxy(struct in_device *in_dev, struct rtable *rt)
 }
 
 /*
+ * Check for RFC3069 proxy arp private VLAN (allow to send back to same dev)
+ *
+ * RFC3069 supports proxy arp replies back to the same interface.  This
+ * is done to support (ethernet) switch features, like RFC 3069, where
+ * the individual ports are not allowed to communicate with each
+ * other, BUT they are allowed to talk to the upstream router.  As
+ * described in RFC 3069, it is possible to allow these hosts to
+ * communicate through the upstream router, by proxy_arp'ing.
+ *
+ * RFC 3069: "VLAN Aggregation for Efficient IP Address Allocation"
+ *
+ *  This technology is known by different names:
+ *    In RFC 3069 it is called VLAN Aggregation.
+ *    Cisco and Allied Telesyn call it Private VLAN.
+ *    Hewlett-Packard call it Source-Port filtering or port-isolation.
+ *    Ericsson call it MAC-Forced Forwarding (RFC Draft).
+ *
+ */
+static inline int arp_fwd_pvlan(struct in_device *in_dev,
+                                struct net_device *dev, struct rtable *rt,
+                                __be32 sip, __be32 tip)
+{
+        /* Private VLAN is only concerned about the same ethernet segment */
+        if (rt->u.dst.dev != dev)
+                return 0;
+
+        /* Don't reply on self probes (often done by windowz boxes)*/
+        if (sip == tip)
+                return 0;
+
+        if (IN_DEV_PROXY_ARP_PVLAN(in_dev))
+                return 1;
+        else
+                return 0;
+}
+
+/*
  *      Interface to link layer: send routine and receive handler.
  */
 
@@ -833,8 +874,11 @@ static int arp_process(struct sk_buff *skb)
                         }
                         goto out;
                 } else if (IN_DEV_FORWARD(in_dev)) {
-                            if (addr_type == RTN_UNICAST  && rt->u.dst.dev != dev &&
-                             (arp_fwd_proxy(in_dev, rt) || pneigh_lookup(&arp_tbl, net, &tip, dev, 0))) {
+                        if (addr_type == RTN_UNICAST  &&
+                            (arp_fwd_proxy(in_dev, dev, rt) ||
+                             arp_fwd_pvlan(in_dev, dev, rt, sip, tip) ||
+                             pneigh_lookup(&arp_tbl, net, &tip, dev, 0)))
+                        {
                                 n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
                                 if (n)
                                         neigh_release(n);
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 5cdbc102a418..0715f4cac391 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -1407,6 +1407,7 @@ static struct devinet_sysctl_table {
                 DEVINET_SYSCTL_RW_ENTRY(ARP_IGNORE, "arp_ignore"),
                 DEVINET_SYSCTL_RW_ENTRY(ARP_ACCEPT, "arp_accept"),
                 DEVINET_SYSCTL_RW_ENTRY(ARP_NOTIFY, "arp_notify"),
+                DEVINET_SYSCTL_RW_ENTRY(PROXY_ARP_PVLAN, "proxy_arp_pvlan"),
 
                 DEVINET_SYSCTL_FLUSHING_ENTRY(NOXFRM, "disable_xfrm"),
                 DEVINET_SYSCTL_FLUSHING_ENTRY(NOPOLICY, "disable_policy"),
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index e446496f564f..1cc339441e7d 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1988,8 +1988,13 @@ static int __mkroute_input(struct sk_buff *skb,
         if (skb->protocol != htons(ETH_P_IP)) {
                 /* Not IP (i.e. ARP). Do not create route, if it is
                  * invalid for proxy arp. DNAT routes are always valid.
+                 *
+                 * Proxy arp feature have been extended to allow, ARP
+                 * replies back to the same interface, to support
+                 * Private VLAN switch technologies. See arp.c.
                  */
-                if (out_dev == in_dev) {
+                if (out_dev == in_dev &&
+                    IN_DEV_PROXY_ARP_PVLAN(in_dev) == 0) {
                         err = -EINVAL;
                         goto cleanup;
                 }