macvlan: Only deliver one copy of the frame to the macvlan interface

BugLink: http://bugs.launchpad.net/bugs/1745052

[ Upstream commit dd6b9c2c ]

This patch intoduces a slight adjustment for macvlan to address the fact
that in source mode I was seeing two copies of any packet addressed to the
macvlan interface being delivered where there should have been only one.

The issue appears to be that one copy was delivered based on the source MAC
address and then the second copy was being delivered based on the
destination MAC address. To fix it I am just treating a unicast address
match as though it is not a match since source based macvlan isn't supposed
to be matching based on the destination MAC anyway.

Fixes: 79cf79ab ("macvlan: add source mode")
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/net/macvlan.c

@@ -441,7 +441,7 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
 					      struct macvlan_dev, list);
 	else
 		vlan = macvlan_hash_lookup(port, eth->h_dest);
-	if (vlan == NULL)
+	if (!vlan || vlan->mode == MACVLAN_MODE_SOURCE)
 		return RX_HANDLER_PASS;
 
 	dev = vlan->dev;