ipv4: Add helpers for neigh lookup for nexthop
A common theme in the output path is looking up a neigh entry for a
nexthop, either the gateway in an rtable or a fallback to the daddr
in the skb:
nexthop = (__force u32)rt_nexthop(rt, ip_hdr(skb)->daddr);
neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
if (unlikely(!neigh))
neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
To allow the nexthop to be an IPv6 address we need to consider the
family of the nexthop and then call __ipv{4,6}_neigh_lookup_noref based
on it.
To make this simpler, add a ip_neigh_gw4 helper similar to ip_neigh_gw6
added in an earlier patch which handles:
neigh = __ipv4_neigh_lookup_noref(dev, nexthop);
if (unlikely(!neigh))
neigh = __neigh_create(&arp_tbl, &nexthop, dev, false);
And then add a second one, ip_neigh_for_gw, that calls either
ip_neigh_gw4 or ip_neigh_gw6 based on the address family of the gateway.
Update the output paths in the VRF driver and core v4 code to use
ip_neigh_for_gw simplifying the family based lookup and making both
ready for a v6 nexthop.
ipv4_neigh_lookup has a different need - the potential to resolve a
passed in address in addition to any gateway in the rtable or skb. Since
this is a one-off, add ip_neigh_gw4 and ip_neigh_gw6 diectly. The
difference between __neigh_create used by the helpers and neigh_create
called by ipv4_neigh_lookup is taking a refcount, so add rcu_read_lock_bh
and bump the refcnt on the neigh entry.
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/route.h b/include/net/route.h
index 5d28a25..96f6c9a 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -29,6 +29,8 @@
#include <net/flow.h>
#include <net/inet_sock.h>
#include <net/ip_fib.h>
+#include <net/arp.h>
+#include <net/ndisc.h>
#include <linux/in_route.h>
#include <linux/rtnetlink.h>
#include <linux/rcupdate.h>
@@ -350,4 +352,34 @@ static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
return hoplimit;
}
+static inline struct neighbour *ip_neigh_gw4(struct net_device *dev,
+ __be32 daddr)
+{
+ struct neighbour *neigh;
+
+ neigh = __ipv4_neigh_lookup_noref(dev, daddr);
+ if (unlikely(!neigh))
+ neigh = __neigh_create(&arp_tbl, &daddr, dev, false);
+
+ return neigh;
+}
+
+static inline struct neighbour *ip_neigh_for_gw(struct rtable *rt,
+ struct sk_buff *skb,
+ bool *is_v6gw)
+{
+ struct net_device *dev = rt->dst.dev;
+ struct neighbour *neigh;
+
+ if (likely(rt->rt_gw_family == AF_INET)) {
+ neigh = ip_neigh_gw4(dev, rt->rt_gw4);
+ } else if (rt->rt_gw_family == AF_INET6) {
+ neigh = ip_neigh_gw6(dev, &rt->rt_gw6);
+ *is_v6gw = true;
+ } else {
+ neigh = ip_neigh_gw4(dev, ip_hdr(skb)->daddr);
+ }
+ return neigh;
+}
+
#endif /* _ROUTE_H */