1 files changed, 11 insertions, 3 deletions

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 369e721c4bab..9cb04df0054b 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -67,14 +67,14 @@ int ip_forward(struct sk_buff *skb)
         if (skb->pkt_type != PACKET_HOST)
                 goto drop;
 
-        skb->ip_summed = CHECKSUM_NONE;
+        skb_forward_csum(skb);
 
         /*
          *      According to the RFC, we must first decrease the TTL field. If
          *      that reaches zero, we must reply an ICMP control message telling
          *      that the packet's lifetime expired.
          */
-        if (skb->nh.iph->ttl <= 1)
+        if (ip_hdr(skb)->ttl <= 1)
                 goto too_many_hops;
 
         if (!xfrm4_route_forward(skb))
@@ -85,10 +85,18 @@ int ip_forward(struct sk_buff *skb)
         if (opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
                 goto sr_failed;
 
+        if (unlikely(skb->len > dst_mtu(&rt->u.dst) &&
+                     (ip_hdr(skb)->frag_off & htons(IP_DF))) && !skb->local_df) {
+                IP_INC_STATS(IPSTATS_MIB_FRAGFAILS);
+                icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+                          htonl(dst_mtu(&rt->u.dst)));
+                goto drop;
+        }
+
         /* We are about to mangle packet. Copy it! */
         if (skb_cow(skb, LL_RESERVED_SPACE(rt->u.dst.dev)+rt->u.dst.header_len))
                 goto drop;
-        iph = skb->nh.iph;
+        iph = ip_hdr(skb);
 
         /* Decrease ttl after skb cow done */
         ip_decrease_ttl(iph);