[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>

2 files changed, 65 insertions, 27 deletions

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index fb9f69c616f5..011136a95809 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -72,13 +72,11 @@ __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
         struct dst_entry *dst, *dst_prev;
         struct rtable *rt0 = (struct rtable*)(*dst_p);
         struct rtable *rt = rt0;
-        __be32 remote = fl->fl4_dst;
-        __be32 local  = fl->fl4_src;
         struct flowi fl_tunnel = {
                 .nl_u = {
                         .ip4_u = {
-                                .saddr = local,
-                                .daddr = remote,
+                                .saddr = fl->fl4_src,
+                                .daddr = fl->fl4_dst,
                                 .tos = fl->fl4_tos
                         }
                 }
@@ -94,7 +92,6 @@ __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
         for (i = 0; i < nx; i++) {
                 struct dst_entry *dst1 = dst_alloc(&xfrm4_dst_ops);
                 struct xfrm_dst *xdst;
-                int tunnel = 0;
 
                 if (unlikely(dst1 == NULL)) {
                         err = -ENOBUFS;
@@ -116,19 +113,28 @@ __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
 
                 dst1->next = dst_prev;
                 dst_prev = dst1;
-                if (xfrm[i]->props.mode != XFRM_MODE_TRANSPORT) {
-                        remote = xfrm[i]->id.daddr.a4;
-                        local  = xfrm[i]->props.saddr.a4;
-                        tunnel = 1;
-                }
+
                 header_len += xfrm[i]->props.header_len;
                 trailer_len += xfrm[i]->props.trailer_len;
 
-                if (tunnel) {
-                        fl_tunnel.fl4_src = local;
-                        fl_tunnel.fl4_dst = remote;
+                if (xfrm[i]->props.mode == XFRM_MODE_TUNNEL) {
+                        unsigned short encap_family = xfrm[i]->props.family;
+                        switch(encap_family) {
+                        case AF_INET:
+                                fl_tunnel.fl4_dst = xfrm[i]->id.daddr.a4;
+                                fl_tunnel.fl4_src = xfrm[i]->props.saddr.a4;
+                                break;
+#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
+                        case AF_INET6:
+                                ipv6_addr_copy(&fl_tunnel.fl6_dst, (struct in6_addr*)&xfrm[i]->id.daddr.a6);
+                                ipv6_addr_copy(&fl_tunnel.fl6_src, (struct in6_addr*)&xfrm[i]->props.saddr.a6);
+                                break;
+#endif
+                        default:
+                                BUG_ON(1);
+                        }
                         err = xfrm_dst_lookup((struct xfrm_dst **)&rt,
-                                              &fl_tunnel, AF_INET);
+                                              &fl_tunnel, encap_family);
                         if (err)
                                 goto error;
                 } else
@@ -145,6 +151,7 @@ __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
         i = 0;
         for (; dst_prev != &rt->u.dst; dst_prev = dst_prev->child) {
                 struct xfrm_dst *x = (struct xfrm_dst*)dst_prev;
+                struct xfrm_state_afinfo *afinfo;
                 x->u.rt.fl = *fl;
 
                 dst_prev->xfrm = xfrm[i++];
@@ -162,8 +169,17 @@ __xfrm4_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
                 /* Copy neighbout for reachability confirmation */
                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
                 dst_prev->input         = rt->u.dst.input;
-                dst_prev->output        = xfrm4_output;
-                if (rt->peer)
+                /* XXX: When IPv6 module can be unloaded, we should manage reference
+                 * to xfrm6_output in afinfo->output. Miyazawa
+                 * */
+                afinfo = xfrm_state_get_afinfo(dst_prev->xfrm->props.family);
+                if (!afinfo) {
+                        dst = *dst_p;
+                        goto error;
+                }
+                dst_prev->output = afinfo->output;
+                xfrm_state_put_afinfo(afinfo);
+                if (dst_prev->xfrm->props.family == AF_INET && rt->peer)
                         atomic_inc(&rt->peer->refcnt);
                 x->u.rt.peer = rt->peer;
                 /* Sheit... I remember I did this right. Apparently,
@@ -274,7 +290,7 @@ static void xfrm4_dst_destroy(struct dst_entry *dst)
 
         if (likely(xdst->u.rt.idev))
                 in_dev_put(xdst->u.rt.idev);
-        if (likely(xdst->u.rt.peer))
+        if (dst->xfrm->props.family == AF_INET && likely(xdst->u.rt.peer))
                 inet_putpeer(xdst->u.rt.peer);
         xfrm_dst_destroy(xdst);
 }
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;