[IPSEC]: IPv4 over IPv6 IPsec tunnel

This is the patch to support IPv4 over IPv6 IPsec.

Signed-off-by: Miika Komu <miika@iki.fi>
Signed-off-by: Diego Beltrami <Diego.Beltrami@hiit.fi>
Signed-off-by: Kazunori Miyazawa <miyazawa@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 10 deletions

diff --git a/net/ipv6/xfrm6_mode_tunnel.c b/net/ipv6/xfrm6_mode_tunnel.c
index 5e7d8a7..0bc866c 100644
--- a/net/ipv6/xfrm6_mode_tunnel.c
+++ b/net/ipv6/xfrm6_mode_tunnel.c
@@ -25,6 +25,12 @@ static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
 		IP6_ECN_set_ce(inner_iph);
 }
 
+static inline void ip6ip_ecn_decapsulate(struct sk_buff *skb)
+{
+	if (INET_ECN_is_ce(ipv6_get_dsfield(skb->nh.ipv6h)))
+			IP_ECN_set_ce(skb->h.ipiph);
+}
+
 /* Add encapsulation header.
  *
  * The top IP header will be constructed per RFC 2401.  The following fields
@@ -40,6 +46,7 @@ static inline void ipip6_ecn_decapsulate(struct sk_buff *skb)
 static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb->dst;
+	struct xfrm_dst *xdst = (struct xfrm_dst*)dst;
 	struct ipv6hdr *iph, *top_iph;
 	int dsfield;
 
@@ -52,16 +59,24 @@ static int xfrm6_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 	skb->h.ipv6h = top_iph + 1;
 
 	top_iph->version = 6;
-	top_iph->priority = iph->priority;
-	top_iph->flow_lbl[0] = iph->flow_lbl[0];
-	top_iph->flow_lbl[1] = iph->flow_lbl[1];
-	top_iph->flow_lbl[2] = iph->flow_lbl[2];
+	if (xdst->route->ops->family == AF_INET6) {
+		top_iph->priority = iph->priority;
+		top_iph->flow_lbl[0] = iph->flow_lbl[0];
+		top_iph->flow_lbl[1] = iph->flow_lbl[1];
+		top_iph->flow_lbl[2] = iph->flow_lbl[2];
+		top_iph->nexthdr = IPPROTO_IPV6;
+	} else {
+		top_iph->priority = 0;
+		top_iph->flow_lbl[0] = 0;
+		top_iph->flow_lbl[1] = 0;
+		top_iph->flow_lbl[2] = 0;
+		top_iph->nexthdr = IPPROTO_IPIP;
+	}
 	dsfield = ipv6_get_dsfield(top_iph);
 	dsfield = INET_ECN_encapsulate(dsfield, dsfield);
 	if (x->props.flags & XFRM_STATE_NOECN)
 		dsfield &= ~INET_ECN_MASK;
 	ipv6_change_dsfield(top_iph, 0, dsfield);
-	top_iph->nexthdr = IPPROTO_IPV6; 
 	top_iph->hop_limit = dst_metric(dst->child, RTAX_HOPLIMIT);
 	ipv6_addr_copy(&top_iph->saddr, (struct in6_addr *)&x->props.saddr);
 	ipv6_addr_copy(&top_iph->daddr, (struct in6_addr *)&x->id.daddr);
@@ -72,7 +87,8 @@ static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 	int err = -EINVAL;
 
-	if (skb->nh.raw[IP6CB(skb)->nhoff] != IPPROTO_IPV6)
+	if (skb->nh.raw[IP6CB(skb)->nhoff] != IPPROTO_IPV6
+	    && skb->nh.raw[IP6CB(skb)->nhoff] != IPPROTO_IPIP)
 		goto out;
 	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
 		goto out;
@@ -81,10 +97,16 @@ static int xfrm6_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 	    (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
 		goto out;
 
-	if (x->props.flags & XFRM_STATE_DECAP_DSCP)
-		ipv6_copy_dscp(skb->nh.ipv6h, skb->h.ipv6h);
-	if (!(x->props.flags & XFRM_STATE_NOECN))
-		ipip6_ecn_decapsulate(skb);
+	if (skb->nh.raw[IP6CB(skb)->nhoff] == IPPROTO_IPV6) {
+		if (x->props.flags & XFRM_STATE_DECAP_DSCP)
+			ipv6_copy_dscp(skb->nh.ipv6h, skb->h.ipv6h);
+		if (!(x->props.flags & XFRM_STATE_NOECN))
+			ipip6_ecn_decapsulate(skb);
+	} else {
+		if (!(x->props.flags & XFRM_STATE_NOECN))
+			ip6ip_ecn_decapsulate(skb);
+		skb->protocol = htons(ETH_P_IP);
+	}
 	skb->mac.raw = memmove(skb->data - skb->mac_len,
 			       skb->mac.raw, skb->mac_len);
 	skb->nh.raw = skb->data;