ipv4: use ip_skb_dst_mtu to determine mtu in ip_fragment
ip_skb_dst_mtu mostly falls back to ip_dst_mtu_maybe_forward if no socket
is attached to the skb (in case of forwarding) or determines the mtu like
we do in ip_finish_output, which actually checks if we should branch to
ip_fragment. Thus use the same function to determine the mtu here, too.
This is important for the introduction of IP_PMTUDISC_OMIT, where we
want the packets getting cut in pieces of the size of the outgoing
interface mtu. IPv6 already does this correctly.
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 8971780..22aa119 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -449,7 +449,6 @@
__be16 not_last_frag;
struct rtable *rt = skb_rtable(skb);
int err = 0;
- bool forwarding = IPCB(skb)->flags & IPSKB_FORWARDED;
dev = rt->dst.dev;
@@ -459,7 +458,7 @@
iph = ip_hdr(skb);
- mtu = ip_dst_mtu_maybe_forward(&rt->dst, forwarding);
+ mtu = ip_skb_dst_mtu(skb);
if (unlikely(((iph->frag_off & htons(IP_DF)) && !skb->local_df) ||
(IPCB(skb)->frag_max_size &&
IPCB(skb)->frag_max_size > mtu))) {