lisp: Use IP addresses rather than flow on hash failure.

When calculating the source port for the UDP header, LISP primarily uses skb_get_hash() but needs a backup in case this fails. The current backup is a hash of the entire flow key but this includes many fields that probably would not be considered to be part of a flow in many situations. It assumes that all fields, including those not used, are zeroed out which will soon not be the case. This switches to using a hash of the IP addresses instead, which solves both problems. These should always be present since LISP encapsulates L3 packets. Signed-off-by: Jesse Gross <[email protected]> Acked-by: Thomas Graf <[email protected]>
krjoshi · Jun 13, 2014 · 31125eb · 31125eb
1 parent b96986e
commit 31125eb
Showing 1 changed file with 9 additions and 2 deletions.
diff --git a/datapath/vport-lisp.c b/datapath/vport-lisp.c
@@ -173,8 +173,15 @@ static u16 get_src_port(struct net *net, struct sk_buff *skb)
 	if (!hash) {
 		struct sw_flow_key *pkt_key = OVS_CB(skb)->pkt_key;
 
-		hash = jhash2((const u32 *)pkt_key,
-			    sizeof(*pkt_key) / sizeof(u32), 0);
+		if (skb->protocol == htons(ETH_P_IP))
+			hash = jhash2((const u32 *)&pkt_key->ipv4.addr,
+				   sizeof(pkt_key->ipv4.addr) / sizeof(u32), 0);
+		else if (skb->protocol == htons(ETH_P_IPV6))
+			hash = jhash2((const u32 *)&pkt_key->ipv6.addr,
+				   sizeof(pkt_key->ipv6.addr) / sizeof(u32), 0);
+		else
+			pr_warn_once("LISP inner protocol is not IP when "
+				     "calculating hash.\n");
 	}
 
 	inet_get_local_port_range(net, &low, &high);