From cc9ff19da9bf76a2f70bcb80225a1c587c162e52 Mon Sep 17 00:00:00 2001
From: Timo Teräs
Date: Wed, 3 Nov 2010 04:41:38 +0000
Subject: xfrm: use gre key as flow upper protocol info

The GRE Key field is intended to be used for identifying an individual
traffic flow within a tunnel. It is useful to be able to have XFRM
policy selector matches to have different policies for different
GRE tunnels.

Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/ipv4/xfrm4_policy.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'net/ipv4/xfrm4_policy.c')

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index dd1fd8c473fc..4a8c5335770c 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -11,6 +11,7 @@
 #include <linux/err.h>
 #include <linux/kernel.h>
 #include <linux/inetdevice.h>
+#include <linux/if_tunnel.h>
 #include <net/dst.h>
 #include <net/xfrm.h>
 #include <net/ip.h>
@@ -154,6 +155,20 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 				fl->fl_ipsec_spi = htonl(ntohs(ipcomp_hdr[1]));
 			}
 			break;
+
+		case IPPROTO_GRE:
+			if (pskb_may_pull(skb, xprth + 12 - skb->data)) {
+				__be16 *greflags = (__be16 *)xprth;
+				__be32 *gre_hdr = (__be32 *)xprth;
+
+				if (greflags[0] & GRE_KEY) {
+					if (greflags[0] & GRE_CSUM)
+						gre_hdr++;
+					fl->fl_gre_key = gre_hdr[1];
+				}
+			}
+			break;
+
 		default:
 			fl->fl_ipsec_spi = 0;
 			break;
-- 
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