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%3Ba=su...

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