IP_GRE: Fix IP-Identification.

GRE-GSO generates ip fragments with id 0,2,3,4... for every
GSO packet, which is not correct. Following patch fixes it
by setting ip-header id unique id of fragments are allowed.
As Eric Dumazet suggested it is optimized by using inner ip-header
whenever inner packet is ipv4.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 3 deletions

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 15847e19b7dd..68f6a94f7661 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1332,8 +1332,10 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
                         if (skb->next != NULL)
                                 iph->frag_off |= htons(IP_MF);
                         offset += (skb->len - skb->mac_len - iph->ihl * 4);
-                } else
-                        iph->id = htons(id++);
+                } else  {
+                        if (!(iph->frag_off & htons(IP_DF)))
+                                iph->id = htons(id++);
+                }
                 iph->tot_len = htons(skb->len - skb->mac_len);
                 iph->check = 0;
                 iph->check = ip_fast_csum(skb_network_header(skb), iph->ihl);
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 5ef4da780ac1..b8bada00d516 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -970,7 +970,8 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
         iph->daddr              =       fl4.daddr;
         iph->saddr              =       fl4.saddr;
         iph->ttl                =       ttl;
-        iph->id                 =       0;
+
+        tunnel_ip_select_ident(skb, old_iph, &rt->dst);
 
         if (ttl == 0) {
                 if (skb->protocol == htons(ETH_P_IP))