Hi Herbert Xu:

Vlad Yasevich [off-list ref] wrote:
  

quoted

Otherwise, all of my tests have passed.
    

Thanks for testing, here is the corrected patch:

sctp: Drop ipfargok in sctp_xmit function

The ipfragok flag controls whether the packet may be fragmented
either on the local host on beyond.  The latter is only valid on
IPv4.

In fact, we never want to do the latter even on IPv4 when PMTU is
enabled.  This is because even though we can't fragment packets
within SCTP due to the prtocol's inherent faults, we can still
fragment it at IP layer.  By setting the DF bit we will improve
the PMTU process.

RFC 2960 only says that we SHOULD clear the DF bit in this case,
so we're compliant even if we set the DF bit.  In fact RFC 4960
no longer has this statement.

Once we make this change, we only need to control the local
fragmentation.  There is already a bit in the skb which controls
that, local_df.  So this patch sets that instead of using the
ipfragok argument.

The only complication is that there isn't a struct sock object
per transport, so for IPv4 we have to resort to changing the
pmtudisc field for every packet.  This should be safe though
as the protocol is single-threaded.

Note that after this patch we can remove ipfragok from the rest
of the stack too.

  

You need this patch to let sctp under IPv6 do the correct thing.

ipv6: Do not drop packet if skb->local_df is set to true

The old code will drop IPv6 packet if ipfragok is not set, since ipfragok is
obsoleted, will be instead by used skb->local_df, so this check must be 
changed
to skb->local_df.

This patch fix this problem and not drop packet if skb->local_df is set to
true.

Signed-off-by: Wei Yongjun <redacted>
---
 net/ipv6/ip6_output.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 0969f2a..e9f2a35 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c

@@ -269,7 +269,7 @@ int ip6_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl,
 	skb->mark = sk->sk_mark;
 
 	mtu = dst_mtu(dst);
-	if ((skb->len <= mtu) || ipfragok || skb_is_gso(skb)) {
+	if ((skb->len <= mtu) || skb->local_df || skb_is_gso(skb)) {
 		IP6_INC_STATS(ip6_dst_idev(skb->dst),
 			      IPSTATS_MIB_OUTREQUESTS);
 		return NF_HOOK(PF_INET6, NF_INET_LOCAL_OUT, skb, NULL, dst->dev,

-- 
1.5.3.8