Subject: [PATCH 05/36] ipv6: Fix PMTU updates for UDP/raw sockets in presence of VRF

From: David Ahern <[email-masked]>
Date: Sun, 18 Nov 2018 10:45:30 -0800

[ Upstream commit 7ddacfa564870cdd97275fd87decb6174abc6380 ]

Preethi reported that PMTU discovery for UDP/raw applications is not
working in the presence of VRF when the socket is not bound to a device.
The problem is that ip6_sk_update_pmtu does not consider the L3 domain
of the skb device if the socket is not bound. Update the function to
set oif to the L3 master device if relevant.

Fixes: ca254490c8df ("net: Add VRF support to IPv6 stack")
Reported-by: Preethi Ramachandra <[email-masked]>
Signed-off-by: David Ahern <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/ipv6/route.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 6045c7af02b6..b2edcf724cb8 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2384,10 +2384,13 @@ EXPORT_SYMBOL_GPL(ip6_update_pmtu);
 
 void ip6_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, __be32 mtu)
 {
+	int oif = sk->sk_bound_dev_if;
 	struct dst_entry *dst;
 
-	ip6_update_pmtu(skb, sock_net(sk), mtu,
-			sk->sk_bound_dev_if, sk->sk_mark, sk->sk_uid);
+	if (!oif && skb->dev)
+		oif = l3mdev_master_ifindex(skb->dev);
+
+	ip6_update_pmtu(skb, sock_net(sk), mtu, oif, sk->sk_mark, sk->sk_uid);
 
 	dst = __sk_dst_get(sk);
 	if (!dst || !dst->obsolete ||
-- 
2.19.1