Patch "ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ipv4-make-neigh-lookup-keys-for-loopback-point-to-point-devices-be-inaddr_any.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sun Jan 28 17:37:09 CET 2018
From: Jim Westfall <jwestfall@surrealistic.net>
Date: Sun, 14 Jan 2018 04:18:51 -0800
Subject: ipv4: Make neigh lookup keys for loopback/point-to-point devices be INADDR_ANY

From: Jim Westfall <jwestfall@surrealistic.net>


[ 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 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 <jwestfall@surrealistic.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/net/arp.h |    3 +++
 net/ipv4/arp.c    |    7 ++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

--- a/include/net/arp.h
+++ b/include/net/arp.h
@@ -19,6 +19,9 @@ static inline u32 arp_hashfn(const void
 
 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);
 }
 
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -223,11 +223,16 @@ static bool arp_key_eq(const struct neig
 
 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) {


Patches currently in stable-queue which might be from jwestfall@surrealistic.net are

queue-4.9/ipv4-make-neigh-lookup-keys-for-loopback-point-to-point-devices-be-inaddr_any.patch
queue-4.9/net-allow-neigh-contructor-functions-ability-to-modify-the-primary_key.patch