[PATCH 4.19 20/49] xfrmi: drop ignore_df check before updating pmtu

[Greg Kroah-Hartman]

From: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>

commit 45a36a18d01907710bad5258d81f76c18882ad88 upstream.

xfrm interfaces currently test for !skb->ignore_df when deciding
whether to update the pmtu on the skb's dst. Because of this, no pmtu
exception is created when we do something like:

    ping -s 1438 <dest>

By dropping this check, the pmtu exception will be created and the
next ping attempt will work.

Fixes: f203b76d7809 ("xfrm: Add virtual xfrm interfaces")
Reported-by: Xiumei Mu <xmu@xxxxxxxxxx>
Signed-off-by: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
Signed-off-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/xfrm/xfrm_interface.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -293,7 +293,7 @@ xfrmi_xmit2(struct sk_buff *skb, struct
 	}
 
 	mtu = dst_mtu(dst);
-	if (!skb->ignore_df && skb->len > mtu) {
+	if (skb->len > mtu) {
 		skb_dst_update_pmtu_no_confirm(skb, mtu);
 
 		if (skb->protocol == htons(ETH_P_IPV6)) {