IPv6 NAT: Do not drop DNATed 6to4/6rd packets

[ Upstream commit 7df37ff33dc122f7bd0614d707939fe84322d264 ]

When a router is doing DNAT for 6to4/6rd packets the latest
anti-spoofing commit 218774dc ("ipv6: add anti-spoofing checks for
6to4 and 6rd") will drop them because the IPv6 address embedded does
not match the IPv4 destination. This patch will allow them to pass by
testing if we have an address that matches on 6to4/6rd interface.  I
have been hit by this problem using Fedora and IPV6TO4_IPV4ADDR.
Also, log the dropped packets (with rate limit).

Signed-off-by: Catalin(ux) M. BOIE <catab@embedromix.ro>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 01b1a1ad77d2..25100687babb 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -73,6 +73,10 @@ extern int			ipv6_chk_home_addr(struct net *net,
                                                    const struct in6_addr *addr);
 #endif
 
+bool ipv6_chk_custom_prefix(const struct in6_addr *addr,
+                                   const unsigned int prefix_len,
+                                   struct net_device *dev);
+
 extern int                      ipv6_chk_prefix(const struct in6_addr *addr,
                                                 struct net_device *dev);