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Commit 6c16fa95 authored Jan 14, 2018 by Jim Westfall Committed by Greg Kroah-Hartman Jan 31, 2018

ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY




[ Upstream commit cd9ff4de0107c65d69d02253bb25d6db93c3dbc1 ]

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 a263b309
(ipv4: Make neigh lookups directly in output packet path) and later removed
in 0bb4087c (ipv4: Fix neigh lookup keying over loopback/point-to-point
devices) because it was broken.

Signed-off-by: Jim Westfall <jwestfall@surrealistic.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent fd303009

include/net/arp.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -37,6 +37,9 @@ static inline struct neighbour __ipv4_neigh_lookup(struct net_device dev, u32
		{
		struct neighbour *n;

		if (dev->flags & (IFF_LOOPBACK \| IFF_POINTOPOINT))
		key = INADDR_ANY;

		rcu_read_lock_bh();
		n = __ipv4_neigh_lookup_noref(dev, key);
		if (n && !atomic_inc_not_zero(&n->refcnt))

net/ipv4/arp.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -221,11 +221,16 @@ static u32 arp_hash(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 == NULL) {