IPv6: Fix multicast routing bugs.

This patch addresses the IPv6 multicast routing issues described
below.  It was tested with XORP 1.4/1.5 as the IPv6 PIM-SM routing
daemon against FreeBSD peers.

net/ipv6/ip6_input.c:

  - Don't try to forward link-local multicast packets.

  - Don't reset skb2->dev before calling ip6_mr_input() so packets can
    be identified as coming from the PIM register vif properly.

net/ipv6/ip6mr.c:

  - Fix incoming PIM register messages processing:

    * The IPv6 pseudo-header should be included when checksumming PIM
      messages (RFC 4601 section 4.9; RFC 3973 section 4.7.1).

    * Packets decapsulated from PIM register messages should have
      skb->protocol ETH_P_IPV6.

  - Enable/disable IPv6 multicast forwarding on the corresponding
    interface when a routing daemon adds/removes a multicast virtual
    interface.

  - Remove incorrect skb_pull() to fix userspace signaling.

  - Enable/disable global IPv6 multicast forwarding when an IPv6
    multicast routing socket is opened/closed.

net/ipv6/route.c:

  - Don't use strict routing logic for packets decapsulated from PIM
    register messages (similar to disabling rp_filter for the IPv4
    case).

Signed-off-by: Thomas Goff <thomas.goff@boeing.com>
Reviewed-by: Fred Templin <fred.l.templin@boeing.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 20 insertions, 7 deletions

diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 936f48946e20..f171e8dbac91 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -255,6 +255,7 @@ int ip6_mc_input(struct sk_buff *skb)
          *      IPv6 multicast router mode is now supported ;)
          */
         if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
+            !(ipv6_addr_type(&hdr->daddr) & IPV6_ADDR_LINKLOCAL) &&
             likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
                 /*
                  * Okay, we try to forward - split and duplicate
@@ -316,7 +317,6 @@ int ip6_mc_input(struct sk_buff *skb)
                 }
 
                 if (skb2) {
-                        skb2->dev = skb2->dst->dev;
                         ip6_mr_input(skb2);
                 }
         }
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 3c51b2d827f4..d19a84b79503 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -365,7 +365,9 @@ static int pim6_rcv(struct sk_buff *skb)
         pim = (struct pimreghdr *)skb_transport_header(skb);
         if (pim->type != ((PIM_VERSION << 4) | PIM_REGISTER) ||
             (pim->flags & PIM_NULL_REGISTER) ||
-            (ip_compute_csum((void *)pim, sizeof(*pim)) != 0 &&
+            (csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr,
+                             sizeof(*pim), IPPROTO_PIM,
+                             csum_partial((void *)pim, sizeof(*pim), 0)) &&
              csum_fold(skb_checksum(skb, 0, skb->len, 0))))
                 goto drop;
 
@@ -392,7 +394,7 @@ static int pim6_rcv(struct sk_buff *skb)
         skb_pull(skb, (u8 *)encap - skb->data);
         skb_reset_network_header(skb);
         skb->dev = reg_dev;
-        skb->protocol = htons(ETH_P_IP);
+        skb->protocol = htons(ETH_P_IPV6);
         skb->ip_summed = 0;
         skb->pkt_type = PACKET_HOST;
         dst_release(skb->dst);
@@ -481,6 +483,7 @@ static int mif6_delete(struct net *net, int vifi)
 {
         struct mif_device *v;
         struct net_device *dev;
+        struct inet6_dev *in6_dev;
         if (vifi < 0 || vifi >= net->ipv6.maxvif)
                 return -EADDRNOTAVAIL;
 
@@ -513,6 +516,10 @@ static int mif6_delete(struct net *net, int vifi)
 
         dev_set_allmulti(dev, -1);
 
+        in6_dev = __in6_dev_get(dev);
+        if (in6_dev)
+                in6_dev->cnf.mc_forwarding--;
+
         if (v->flags & MIFF_REGISTER)
                 unregister_netdevice(dev);
 
@@ -622,6 +629,7 @@ static int mif6_add(struct net *net, struct mif6ctl *vifc, int mrtsock)
         int vifi = vifc->mif6c_mifi;
         struct mif_device *v = &net->ipv6.vif6_table[vifi];
         struct net_device *dev;
+        struct inet6_dev *in6_dev;
         int err;
 
         /* Is vif busy ? */
@@ -662,6 +670,10 @@ static int mif6_add(struct net *net, struct mif6ctl *vifc, int mrtsock)
                 return -EINVAL;
         }
 
+        in6_dev = __in6_dev_get(dev);
+        if (in6_dev)
+                in6_dev->cnf.mc_forwarding++;
+
         /*
          *      Fill in the VIF structures
          */
@@ -838,8 +850,6 @@ static int ip6mr_cache_report(struct net *net, struct sk_buff *pkt, mifi_t mifi,
 
         skb->dst = dst_clone(pkt->dst);
         skb->ip_summed = CHECKSUM_UNNECESSARY;
-
-        skb_pull(skb, sizeof(struct ipv6hdr));
         }
 
         if (net->ipv6.mroute6_sk == NULL) {
@@ -1222,8 +1232,10 @@ static int ip6mr_sk_init(struct sock *sk)
 
         rtnl_lock();
         write_lock_bh(&mrt_lock);
-        if (likely(net->ipv6.mroute6_sk == NULL))
+        if (likely(net->ipv6.mroute6_sk == NULL)) {
                 net->ipv6.mroute6_sk = sk;
+                net->ipv6.devconf_all->mc_forwarding++;
+        }
         else
                 err = -EADDRINUSE;
         write_unlock_bh(&mrt_lock);
@@ -1242,6 +1254,7 @@ int ip6mr_sk_done(struct sock *sk)
         if (sk == net->ipv6.mroute6_sk) {
                 write_lock_bh(&mrt_lock);
                 net->ipv6.mroute6_sk = NULL;
+                net->ipv6.devconf_all->mc_forwarding--;
                 write_unlock_bh(&mrt_lock);
 
                 mroute_clean_tables(net);
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index c4a59824ac2c..9c574235c905 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -794,7 +794,7 @@ void ip6_route_input(struct sk_buff *skb)
                 .proto = iph->nexthdr,
         };
 
-        if (rt6_need_strict(&iph->daddr))
+        if (rt6_need_strict(&iph->daddr) && skb->dev->type != ARPHRD_PIMREG)
                 flags |= RT6_LOOKUP_F_IFACE;
 
         skb->dst = fib6_rule_lookup(net, &fl, flags, ip6_pol_route_input);