netdev - [net PATCH] macvlan: Only deliver one copy of the frame to the macvlan interface

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Message-ID: <20171008225403.15848.77823.stgit@localhost.localdomain>
Date:   Sun, 08 Oct 2017 15:54:26 -0700
From:   Alexander Duyck <alexander.duyck@...il.com>
To:     netdev@...r.kernel.org, davem@...emloft.net
Subject: [net PATCH] macvlan: Only deliver one copy of the frame to the
 macvlan interface

From: Alexander Duyck <alexander.h.duyck@...el.com>

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 freeing the second copy
instead of delivering it up the stack using the same netdev as was already
delivered to.

Fixes: 79cf79abce71 ("macvlan: add source mode")
Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
---
 drivers/net/macvlan.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index d2aea961e0f4..744b0fe6dc78 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -484,7 +484,8 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
 		return RX_HANDLER_PASS;

 	dev = vlan->dev;
-	if (unlikely(!(dev->flags & IFF_UP))) {
+	if ((vlan->mode == MACVLAN_MODE_SOURCE) ||
+	    unlikely(!(dev->flags & IFF_UP))) {
 		kfree_skb(skb);
 		return RX_HANDLER_CONSUMED;
 	}