[BRIDGE]: use llc for receiving STP packets

Use LLC for the receive path of Spanning Tree Protocol packets.
This allows link local multicast packets to be received by
other protocols (if they care), and uses the existing LLC
code to get STP packets back into bridge code.

The bridge multicast address is also checked, so bridges using
other link local multicast addresses are ignored. This allows
for use of different multicast addresses to define separate STP
domains.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 9 deletions

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 6e223723cc8d..dad409489753 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -94,6 +94,25 @@ drop:
         goto out;
 }
 
+/* note: already called with rcu_read_lock (preempt_disabled) */
+static int br_handle_local_finish(struct sk_buff *skb)
+{
+        struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
+
+        if (p && p->state != BR_STATE_DISABLED)
+                br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
+
+        return 0;        /* process further */
+}
+
+/* Does address match the link local multicast address.
+ * 01:80:c2:00:00:0X
+ */
+static inline int is_link_local(const unsigned char *dest)
+{
+        return memcmp(dest, bridge_ula, 5) == 0 && (dest[5] & 0xf0) == 0;
+}
+
 /*
  * Called via br_handle_frame_hook.
  * Return 0 if *pskb should be processed furthur
@@ -111,15 +130,10 @@ int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
         if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
                 goto err;
 
-        if (p->br->stp_enabled &&
-            !memcmp(dest, bridge_ula, 5) &&
-            !(dest[5] & 0xF0)) {
-                if (!dest[5]) {
-                        NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 
-                                NULL, br_stp_handle_bpdu);
-                        return 1;
-                }
-                goto err;
+        if (unlikely(is_link_local(dest))) {
+                skb->pkt_type = PACKET_HOST;
+                return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
+                               NULL, br_handle_local_finish) != 0;
         }
 
         if (p->state == BR_STATE_FORWARDING || p->state == BR_STATE_LEARNING) {