From: Jesse Gross <jesse@nicira.com>
Date: Sat, 4 Dec 2010 03:17:20 +0000 (-0800)
Subject: tunneling: Access correct IP header when processing ECN.
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a2a96c04cb5d7c4df7578aca5ac073d4ef05ca08;p=openvswitch

tunneling: Access correct IP header when processing ECN.

We attempt to copy the ECN bits from the outside of the tunnel to
the inside on receive if we are encapsulating IP traffic.  However,
we were previously looking at the inner IP header as the source of
the ECN bits, when it should have been the outer header.  This
corrects that and cleans up the function a little bit.

Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
---

diff --git a/datapath/tunnel.c b/datapath/tunnel.c
index 542badc4..0faa4ec8 100644
--- a/datapath/tunnel.c
+++ b/datapath/tunnel.c
@@ -365,34 +365,37 @@ found:
 
 static inline void ecn_decapsulate(struct sk_buff *skb)
 {
-	u8 tos = ip_hdr(skb)->tos;
-
-	if (INET_ECN_is_ce(tos)) {
+	/* This is accessing the outer IP header of the tunnel, which we've
+	 * already validated to be OK.  skb->data is currently set to the start
+	 * of the inner Ethernet header, and we've validated ETH_HLEN.
+	 */
+	if (unlikely(INET_ECN_is_ce(ip_hdr(skb)->tos))) {
 		__be16 protocol = skb->protocol;
-		unsigned int nw_header = skb_network_offset(skb);
+
+		skb_set_network_header(skb, ETH_HLEN);
 
 		if (skb->protocol == htons(ETH_P_8021Q)) {
 			if (unlikely(!pskb_may_pull(skb, VLAN_ETH_HLEN)))
 				return;
 
 			protocol = vlan_eth_hdr(skb)->h_vlan_encapsulated_proto;
-			nw_header += VLAN_HLEN;
+			skb_set_network_header(skb, VLAN_ETH_HLEN);
 		}
 
 		if (protocol == htons(ETH_P_IP)) {
-			if (unlikely(!pskb_may_pull(skb, nw_header
+			if (unlikely(!pskb_may_pull(skb, skb_network_offset(skb)
 			    + sizeof(struct iphdr))))
 				return;
 
-			IP_ECN_set_ce((struct iphdr *)(skb->data + nw_header));
+			IP_ECN_set_ce(ip_hdr(skb));
 		}
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 		else if (protocol == htons(ETH_P_IPV6)) {
-			if (unlikely(!pskb_may_pull(skb, nw_header
+			if (unlikely(!pskb_may_pull(skb, skb_network_offset(skb)
 			    + sizeof(struct ipv6hdr))))
 				return;
 
-			IP6_ECN_set_ce((struct ipv6hdr *)(skb->data + nw_header));
+			IP6_ECN_set_ce(ipv6_hdr(skb));
 		}
 #endif
 	}
@@ -418,7 +421,6 @@ void tnl_rcv(struct vport *vport, struct sk_buff *skb)
 	skb_dst_drop(skb);
 	nf_reset(skb);
 	secpath_reset(skb);
-	skb_set_network_header(skb, ETH_HLEN);
 
 	ecn_decapsulate(skb);
 	compute_ip_summed(skb, false);