[PATCH 2/2] ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY
From: Jim Westfall <hidden>
Date: 2018-01-14 00:01:40
Map all lookup neigh keys to INADDR_ANY for loopback/point-to-point devices to avoid making an entry for every remote ip the device needs to talk to. This used the be the old behavior but became broken in a263b3093641f (ipv4: Make neigh lookups directly in output packet path) and later removed in 0bb4087cbec0 (ipv4: Fix neigh lookup keying over loopback/point-to-point devices) because it was broken. Signed-off-by: Jim Westfall <redacted> --- include/net/arp.h | 3 +++ net/ipv4/arp.c | 7 ++++++- 2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/include/net/arp.h b/include/net/arp.h
index dc8cd47f883b..9bb399597b4b 100644
--- a/include/net/arp.h
+++ b/include/net/arp.h@@ -20,6 +20,9 @@ static inline u32 arp_hashfn(const void *pkey, const struct net_device *dev, u32 static inline struct neighbour *__ipv4_neigh_lookup_noref(struct net_device *dev, u32 key) { + if(dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) + key = INADDR_ANY; + return ___neigh_lookup_noref(&arp_tbl, neigh_key_eq32, arp_hashfn, &key, dev); }
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index a8d7c5a9fb05..77fe6d53ac15 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c@@ -223,11 +223,16 @@ static bool arp_key_eq(const struct neighbour *neigh, const void *pkey) static int arp_constructor(struct neighbour *neigh) { - __be32 addr = *(__be32 *)neigh->primary_key; + __be32 addr; struct net_device *dev = neigh->dev; struct in_device *in_dev; struct neigh_parms *parms; + u32 inaddr_any = INADDR_ANY; + if(dev->flags & (IFF_LOOPBACK | IFF_POINTOPOINT)) + memcpy(neigh->primary_key, &inaddr_any, arp_tbl.key_len); + + addr = *(__be32 *)neigh->primary_key; rcu_read_lock(); in_dev = __in_dev_get_rcu(dev); if (!in_dev) {