[3.16.y-ckt stable] Patch "packet: always probe for transport header" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    packet: always probe for transport header

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt22.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 66a74d9654121cd7c2ea432f19bd682a12d96835 Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <daniel at iogearbox.net>
Date: Wed, 11 Nov 2015 23:25:41 +0100
Subject: packet: always probe for transport header

commit 8fd6c80d9dd938ca338c70698533a7e304752846 upstream.

We concluded that the skb_probe_transport_header() should better be
called unconditionally. Avoiding the call into the flow dissector has
also not really much to do with the direct xmit mode.

While it seems that only virtio_net code makes use of GSO from non
RX/TX ring packet socket paths, we should probe for a transport header
nevertheless before they hit devices.

Reference: http://thread.gmane.org/gmane.linux.network/386173/
Signed-off-by: Daniel Borkmann <daniel at iogearbox.net>
Acked-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/packet/af_packet.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index ede33f60991a..e9ea7ff99bc0 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2216,8 +2216,7 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
 		len = ((to_write > len_max) ? len_max : to_write);
 	}

-	if (!packet_use_direct_xmit(po))
-		skb_probe_transport_header(skb, 0);
+	skb_probe_transport_header(skb, 0);

 	return tp_len;
 }
@@ -2540,8 +2539,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
 		len += vnet_hdr_len;
 	}

-	if (!packet_use_direct_xmit(po))
-		skb_probe_transport_header(skb, reserve);
+	skb_probe_transport_header(skb, reserve);
+
 	if (unlikely(extra_len == 4))
 		skb->no_fcs = 1;