[IPSEC]: IPv6 over IPv4 IPsec tunnel

This is the patch to support IPv6 over IPv4 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, 77 insertions, 26 deletions

diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index e23c21d31a53..e54c5494c88f 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -23,6 +23,12 @@ static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
                 IP_ECN_set_ce(inner_iph);
 }
 
+static inline void ipip6_ecn_decapsulate(struct iphdr *iph, struct sk_buff *skb)
+{
+        if (INET_ECN_is_ce(iph->tos))
+                IP6_ECN_set_ce(skb->nh.ipv6h);
+}
+
 /* Add encapsulation header.
  *
  * The top IP header will be constructed per RFC 2401.  The following fields
@@ -36,6 +42,7 @@ static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
 static int xfrm4_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 iphdr *iph, *top_iph;
         int flags;
 
@@ -48,15 +55,27 @@ static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
         top_iph->ihl = 5;
         top_iph->version = 4;
 
+        flags = x->props.flags;
+
         /* DS disclosed */
-        top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
+        if (xdst->route->ops->family == AF_INET) {
+                top_iph->protocol = IPPROTO_IPIP;
+                top_iph->tos = INET_ECN_encapsulate(iph->tos, iph->tos);
+                top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
+                        0 : (iph->frag_off & htons(IP_DF));
+        }
+#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
+        else {
+                struct ipv6hdr *ipv6h = (struct ipv6hdr*)iph;
+                top_iph->protocol = IPPROTO_IPV6;
+                top_iph->tos = INET_ECN_encapsulate(iph->tos, ipv6_get_dsfield(ipv6h));
+                top_iph->frag_off = 0;
+        }
+#endif
 
-        flags = x->props.flags;
         if (flags & XFRM_STATE_NOECN)
                 IP_ECN_clear(top_iph);
 
-        top_iph->frag_off = (flags & XFRM_STATE_NOPMTUDISC) ?
-                0 : (iph->frag_off & htons(IP_DF));
         if (!top_iph->frag_off)
                 __ip_select_ident(top_iph, dst->child, 0);
 
@@ -64,7 +83,6 @@ static int xfrm4_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
 
         top_iph->saddr = x->props.saddr.a4;
         top_iph->daddr = x->id.daddr.a4;
-        top_iph->protocol = IPPROTO_IPIP;
 
         memset(&(IPCB(skb)->opt), 0, sizeof(struct ip_options));
         return 0;
@@ -75,8 +93,16 @@ static int xfrm4_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
         struct iphdr *iph = skb->nh.iph;
         int err = -EINVAL;
 
-        if (iph->protocol != IPPROTO_IPIP)
-                goto out;
+        switch(iph->protocol){
+                case IPPROTO_IPIP:
+#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
+                case IPPROTO_IPV6:
+                        break;
+#endif
+                default:
+                        goto out;
+        }
+
         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
                 goto out;
 
@@ -84,10 +110,19 @@ static int xfrm4_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)
-                ipv4_copy_dscp(iph, skb->h.ipiph);
-        if (!(x->props.flags & XFRM_STATE_NOECN))
-                ipip_ecn_decapsulate(skb);
+        if (iph->protocol == IPPROTO_IPIP) {
+                if (x->props.flags & XFRM_STATE_DECAP_DSCP)
+                        ipv4_copy_dscp(iph, skb->h.ipiph);
+                if (!(x->props.flags & XFRM_STATE_NOECN))
+                        ipip_ecn_decapsulate(skb);
+        }
+#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
+        else {
+                if (!(x->props.flags & XFRM_STATE_NOECN))
+                        ipip6_ecn_decapsulate(iph, skb);
+                skb->protocol = htons(ETH_P_IPV6);
+        }
+#endif
         skb->mac.raw = memmove(skb->data - skb->mac_len,
                                skb->mac.raw, skb->mac_len);
         skb->nh.raw = skb->data;
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 8dffd4daae9c..59480e92177d 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -131,13 +131,11 @@ __xfrm6_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
         struct dst_entry *dst, *dst_prev;
         struct rt6_info *rt0 = (struct rt6_info*)(*dst_p);
         struct rt6_info *rt  = rt0;
-        struct in6_addr *remote = &fl->fl6_dst;
-        struct in6_addr *local  = &fl->fl6_src;
         struct flowi fl_tunnel = {
                 .nl_u = {
                         .ip6_u = {
-                                .saddr = *local,
-                                .daddr = *remote
+                                .saddr = fl->fl6_src,
+                                .daddr = fl->fl6_dst,
                         }
                 }
         };
@@ -153,7 +151,6 @@ __xfrm6_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
         for (i = 0; i < nx; i++) {
                 struct dst_entry *dst1 = dst_alloc(&xfrm6_dst_ops);
                 struct xfrm_dst *xdst;
-                int tunnel = 0;
 
                 if (unlikely(dst1 == NULL)) {
                         err = -ENOBUFS;
@@ -177,19 +174,27 @@ __xfrm6_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 = __xfrm6_bundle_addr_remote(xfrm[i], remote);
-                        local  = __xfrm6_bundle_addr_local(xfrm[i], local);
-                        tunnel = 1;
-                }
+
                 __xfrm6_bundle_len_inc(&header_len, &nfheader_len, xfrm[i]);
                 trailer_len += xfrm[i]->props.trailer_len;
 
-                if (tunnel) {
-                        ipv6_addr_copy(&fl_tunnel.fl6_dst, remote);
-                        ipv6_addr_copy(&fl_tunnel.fl6_src, local);
+                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;
+                        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;
+                        default:
+                                BUG_ON(1);
+                        }
+
                         err = xfrm_dst_lookup((struct xfrm_dst **) &rt,
-                                              &fl_tunnel, AF_INET6);
+                                              &fl_tunnel, encap_family);
                         if (err)
                                 goto error;
                 } else
@@ -208,6 +213,7 @@ __xfrm6_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;
 
                 dst_prev->xfrm = xfrm[i++];
                 dst_prev->dev = rt->u.dst.dev;
@@ -224,7 +230,17 @@ __xfrm6_bundle_create(struct xfrm_policy *policy, struct xfrm_state **xfrm, int
                 /* Copy neighbour for reachability confirmation */
                 dst_prev->neighbour     = neigh_clone(rt->u.dst.neighbour);
                 dst_prev->input         = rt->u.dst.input;
-                dst_prev->output        = xfrm6_output;
+                /* XXX: When IPv4 is implemented as module and can be unloaded,
+                 * we should manage reference to xfrm4_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);
                 /* Sheit... I remember I did this right. Apparently,
                  * it was magically lost, so this code needs audit */
                 x->u.rt6.rt6i_flags    = rt0->rt6i_flags&(RTCF_BROADCAST|RTCF_MULTICAST|RTCF_LOCAL);