[NET] Move DF check to ip_forward

Do fragmentation check in ip_forward, similar to ipv6 forwarding.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 0 deletions

diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index 467ebedb99ba..61b30d100676 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -85,6 +85,14 @@ 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;