From fedbb6b4ff341c1e2120f4ffbf367fd78ac3e8f3 Mon Sep 17 00:00:00 2001 From: Shmulik Ladkani Date: Wed, 29 Jun 2016 21:47:03 +0300 Subject: ipv4: Fix ip_skb_dst_mtu to use the sk passed by ip_finish_output ip_skb_dst_mtu uses skb->sk, assuming it is an AF_INET socket (e.g. it calls ip_sk_use_pmtu which casts sk as an inet_sk). However, in the case of UDP tunneling, the skb->sk is not necessarily an inet socket (could be AF_PACKET socket, or AF_UNSPEC if arriving from tun/tap). OTOH, the sk passed as an argument throughout IP stack's output path is the one which is of PMTU interest: - In case of local sockets, sk is same as skb->sk; - In case of a udp tunnel, sk is the tunneling socket. Fix, by passing ip_finish_output's sk to ip_skb_dst_mtu. This augments 7026b1ddb6 'netfilter: Pass socket pointer down through okfn().' Signed-off-by: Shmulik Ladkani Reviewed-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv4/ip_output.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/ipv4') diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 124bf0a66328..4bd4921639c3 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -271,7 +271,7 @@ static int ip_finish_output(struct net *net, struct sock *sk, struct sk_buff *sk return dst_output(net, sk, skb); } #endif - mtu = ip_skb_dst_mtu(skb); + mtu = ip_skb_dst_mtu(sk, skb); if (skb_is_gso(skb)) return ip_finish_output_gso(net, sk, skb, mtu); @@ -541,7 +541,7 @@ int ip_do_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, iph = ip_hdr(skb); - mtu = ip_skb_dst_mtu(skb); + mtu = ip_skb_dst_mtu(sk, skb); if (IPCB(skb)->frag_max_size && IPCB(skb)->frag_max_size < mtu) mtu = IPCB(skb)->frag_max_size; -- cgit v1.2.3