IPv6: add the option to use anycast addresses as source addresses in echo reply
This change allows to follow a recommandation of RFC4942.
- Add "anycast_src_echo_reply" sysctl to control the use of anycast addresses
as source addresses for ICMPv6 echo reply. This sysctl is false by default
to preserve existing behavior.
- Add inline check ipv6_anycast_destination().
- Use them in icmpv6_echo_reply().
Reference:
RFC4942 - IPv6 Transition/Coexistence Security Considerations
(http://tools.ietf.org/html/rfc4942#section-2.1.6)
2.1.6. Anycast Traffic Identification and Security
[...]
To avoid exposing knowledge about the internal structure of the
network, it is recommended that anycast servers now take advantage of
the ability to return responses with the anycast address as the
source address if possible.
Signed-off-by: Francois-Xavier Le Bail <fx.lebail@yahoo.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 1fb6cdd..017badb 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -152,6 +152,13 @@
return rt->rt6i_flags & RTF_LOCAL;
}
+static inline bool ipv6_anycast_destination(const struct sk_buff *skb)
+{
+ struct rt6_info *rt = (struct rt6_info *) skb_dst(skb);
+
+ return rt->rt6i_flags & RTF_ANYCAST;
+}
+
int ip6_fragment(struct sk_buff *skb, int (*output)(struct sk_buff *));
static inline int ip6_skb_dst_mtu(struct sk_buff *skb)
diff --git a/include/net/netns/ipv6.h b/include/net/netns/ipv6.h
index 0fb2401..76fc7d1 100644
--- a/include/net/netns/ipv6.h
+++ b/include/net/netns/ipv6.h
@@ -73,6 +73,7 @@
#endif
atomic_t dev_addr_genid;
atomic_t rt_genid;
+ int anycast_src_echo_reply;
};
#if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)