Re: [PATCH] udp: avoid ufo handling on IP payload compression packets

On Mon, Mar 06, 2017 at 07:16:57AM +0100, Steffen Klassert wrote:

quoted

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index b67719f..18383ef 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c

@@ -960,7 +960,10 @@ static int __ip_append_data(struct sock *sk,
 	cork->length += length;
 	if ((((length + fragheaderlen) > mtu) || (skb && skb_is_gso(skb))) &&
 	    (sk->sk_protocol == IPPROTO_UDP) &&
-	    (rt->dst.dev->features & NETIF_F_UFO) && !rt->dst.header_len &&
+	    (rt->dst.dev->features & NETIF_F_UFO) &&
+#ifdef CONFIG_XFRM
+	    !rt->dst.xfrm &&
+#endif

Please fix IPcomp to use rt->dst.header_len instead off adding
this ifdef to the generic networking code.

It's not that simple though.  IPComp's header_len is set to zero
because we opportunistically drop the IPComp header when the total
compressed length exceeds the original packet length.  That is,
we only ever do IPComp when it does not cause the packet to expand.

So it seems that we need another way of indicating the presence of
XFRM.

Cheers,
-- 
Email: Herbert Xu [off-list ref]
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