[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 5e7d8a7d6414..0bc866c0d83c 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;