From: Eric Dumazet <edumazet@google.com>
Date: Fri, 8 Nov 2013 02:32:06 +0000 (-0800)
Subject: inet: fix a UFO regression
X-Git-Tag: firefly_0821_release~176^2~4992^2~24
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=dcd607718385d02ce3741de225927a57f528f93b;p=firefly-linux-kernel-4.4.55.git

inet: fix a UFO regression

While testing virtio_net and skb_segment() changes, Hannes reported
that UFO was sending wrong frames.

It appears this was introduced by a recent commit :
8c3a897bfab1 ("inet: restore gso for vxlan")

The old condition to perform IP frag was :

tunnel = !!skb->encapsulation;
...
        if (!tunnel && proto == IPPROTO_UDP) {

So the new one should be :

udpfrag = !skb->encapsulation && proto == IPPROTO_UDP;
...
        if (udpfrag) {

Initialization of udpfrag must be done before call
to ops->callbacks.gso_segment(skb, features), as
skb_udp_tunnel_segment() clears skb->encapsulation

(We want udpfrag to be true for UFO, false for VXLAN)

With help from Alexei Starovoitov

Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 09d78d4a3cff..68af9aac91d0 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1299,6 +1299,9 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
 
 	segs = ERR_PTR(-EPROTONOSUPPORT);
 
+	/* Note : following gso_segment() might change skb->encapsulation */
+	udpfrag = !skb->encapsulation && proto == IPPROTO_UDP;
+
 	ops = rcu_dereference(inet_offloads[proto]);
 	if (likely(ops && ops->callbacks.gso_segment))
 		segs = ops->callbacks.gso_segment(skb, features);
@@ -1306,7 +1309,6 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
 	if (IS_ERR_OR_NULL(segs))
 		goto out;
 
-	udpfrag = !!skb->encapsulation && proto == IPPROTO_UDP;
 	skb = segs;
 	do {
 		iph = (struct iphdr *)(skb_mac_header(skb) + nhoff);