vti4: eliminated some duplicate code.

The ipip tunnel introduced in commit dd9ee344 ("vti4: Fix a ipip
packet processing bug in 'IPCOMP' virtual tunnel") largely duplicated
the existing vti_input and vti_recv functions.  Refactored to
deduplicate the common code.
Signed-off-by: Jeremy Sowden <jeremy@azazel.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv4/ip_vti.c

@@ -50,7 +50,7 @@ static unsigned int vti_net_id __read_mostly;
 static int vti_tunnel_init(struct net_device *dev);
 
 static int vti_input(struct sk_buff *skb, int nexthdr, __be32 spi,
-		     int encap_type)
+		     int encap_type, bool update_skb_dev)
 {
 	struct ip_tunnel *tunnel;
 	const struct iphdr *iph = ip_hdr(skb);
@@ -65,6 +65,9 @@ static int vti_input(struct sk_buff *skb, int nexthdr, __be32 spi,
 
 		XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = tunnel;
 
+		if (update_skb_dev)
+			skb->dev = tunnel->dev;
+
 		return xfrm_input(skb, nexthdr, spi, encap_type);
 	}
 
@@ -74,47 +77,28 @@ static int vti_input(struct sk_buff *skb, int nexthdr, __be32 spi,
 	return 0;
 }
 
-static int vti_input_ipip(struct sk_buff *skb, int nexthdr, __be32 spi,
-		     int encap_type)
+static int vti_input_proto(struct sk_buff *skb, int nexthdr, __be32 spi,
+			   int encap_type)
 {
-	struct ip_tunnel *tunnel;
-	const struct iphdr *iph = ip_hdr(skb);
-	struct net *net = dev_net(skb->dev);
-	struct ip_tunnel_net *itn = net_generic(net, vti_net_id);
-
-	tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
-				  iph->saddr, iph->daddr, 0);
-	if (tunnel) {
-		if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
-			goto drop;
-
-		XFRM_TUNNEL_SKB_CB(skb)->tunnel.ip4 = tunnel;
-
-		skb->dev = tunnel->dev;
-
-		return xfrm_input(skb, nexthdr, spi, encap_type);
-	}
-
-	return -EINVAL;
-drop:
-	kfree_skb(skb);
-	return 0;
+	return vti_input(skb, nexthdr, spi, encap_type, false);
 }
 
-static int vti_rcv(struct sk_buff *skb)
+static int vti_rcv(struct sk_buff *skb, __be32 spi, bool update_skb_dev)
 {
 	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
 	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
 
-	return vti_input(skb, ip_hdr(skb)->protocol, 0, 0);
+	return vti_input(skb, ip_hdr(skb)->protocol, spi, 0, update_skb_dev);
 }
 
-static int vti_rcv_ipip(struct sk_buff *skb)
+static int vti_rcv_proto(struct sk_buff *skb)
 {
-	XFRM_SPI_SKB_CB(skb)->family = AF_INET;
-	XFRM_SPI_SKB_CB(skb)->daddroff = offsetof(struct iphdr, daddr);
+	return vti_rcv(skb, 0, false);
+}
 
-	return vti_input_ipip(skb, ip_hdr(skb)->protocol, ip_hdr(skb)->saddr, 0);
+static int vti_rcv_tunnel(struct sk_buff *skb)
+{
+	return vti_rcv(skb, ip_hdr(skb)->saddr, true);
 }
 
 static int vti_rcv_cb(struct sk_buff *skb, int err)
@@ -447,31 +431,31 @@ static void __net_init vti_fb_tunnel_init(struct net_device *dev)
 }
 
 static struct xfrm4_protocol vti_esp4_protocol __read_mostly = {
-	.handler	=	vti_rcv,
-	.input_handler	=	vti_input,
+	.handler	=	vti_rcv_proto,
+	.input_handler	=	vti_input_proto,
 	.cb_handler	=	vti_rcv_cb,
 	.err_handler	=	vti4_err,
 	.priority	=	100,
 };
 
 static struct xfrm4_protocol vti_ah4_protocol __read_mostly = {
-	.handler	=	vti_rcv,
-	.input_handler	=	vti_input,
+	.handler	=	vti_rcv_proto,
+	.input_handler	=	vti_input_proto,
 	.cb_handler	=	vti_rcv_cb,
 	.err_handler	=	vti4_err,
 	.priority	=	100,
 };
 
 static struct xfrm4_protocol vti_ipcomp4_protocol __read_mostly = {
-	.handler	=	vti_rcv,
-	.input_handler	=	vti_input,
+	.handler	=	vti_rcv_proto,
+	.input_handler	=	vti_input_proto,
 	.cb_handler	=	vti_rcv_cb,
 	.err_handler	=	vti4_err,
 	.priority	=	100,
 };
 
 static struct xfrm_tunnel ipip_handler __read_mostly = {
-	.handler	=	vti_rcv_ipip,
+	.handler	=	vti_rcv_tunnel,
 	.err_handler	=	vti4_err,
 	.priority	=	0,
 };