datapath: tunnel: Do not use inner ip-header-id for tunnel ip-header-id.

Using inner-id for tunnel id is not safe in some rare cases.
E.g. packets coming from multiple sources entering same tunnel
can have same id. Therefore on tunnel packet receive we
could have packets from two different stream but with same
source and dst IP with same ip-id which could confuse ip packet
reassembly.

CC: Jarno Rajahalme <jrajahalme@nicira.com>
CC: Ansis Atteka <aatteka@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>

diff --git a/datapath/linux/compat/include/net/ip_tunnels.h b/datapath/linux/compat/include/net/ip_tunnels.h
index ad17c9d..14f55d0 100644 (file)
--- a/datapath/linux/compat/include/net/ip_tunnels.h
+++ b/datapath/linux/compat/include/net/ip_tunnels.h
@@ -31,20 +31,6 @@ struct tnl_ptk_info {
 #define PACKET_RCVD    0
 #define PACKET_REJECT  1
 
-static inline void tunnel_ip_select_ident(struct sk_buff *skb,
-                                         const struct iphdr  *old_iph,
-                                         struct dst_entry *dst)
-{
-       struct iphdr *iph = ip_hdr(skb);
-
-       /* Use inner packet iph-id if possible. */
-       if (skb->protocol == htons(ETH_P_IP) && old_iph->id)
-               iph->id = old_iph->id;
-       else
-               __ip_select_ident(iph, dst,
-                               (skb_shinfo(skb)->gso_segs ?: 1) - 1);
-}
-
 int iptunnel_xmit(struct net *net, struct rtable *rt,
                  struct sk_buff *skb,
                  __be32 src, __be32 dst, __u8 proto,

diff --git a/datapath/linux/compat/ip_tunnels_core.c b/datapath/linux/compat/ip_tunnels_core.c
index 03c47a2..01cc2fb 100644 (file)
--- a/datapath/linux/compat/ip_tunnels_core.c
+++ b/datapath/linux/compat/ip_tunnels_core.c
@@ -68,9 +68,7 @@ int iptunnel_xmit(struct net *net, struct rtable *rt,
        iph->daddr      =       dst;
        iph->saddr      =       src;
        iph->ttl        =       ttl;
-       tunnel_ip_select_ident(skb,
-                              (const struct iphdr *)skb_inner_network_header(skb),
-                              &rt_dst(rt));
+       __ip_select_ident(iph, &rt_dst(rt), (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 
        err = ip_local_out(skb);
        if (unlikely(net_xmit_eval(err)))