From f0663e5c192810a02570c9764b4bd10547dea9db Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timo=20Ter=C3=A4s?= Date: Tue, 7 Jul 2015 08:34:13 +0300 Subject: [PATCH] ip_tunnel: fix ipv4 pmtu check to honor inner ip header df MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit fc24f2b2094366da8786f59f2606307e934cea17 upstream. Frag needed should be sent only if the inner header asked to not fragment. Currently fragmentation is broken if the tunnel has df set, but df was not asked in the original packet. The tunnel's df needs to be still checked to update internally the pmtu cache. Commit 23a3647bc4f93bac broke it, and this commit fixes the ipv4 df check back to the way it was. Fixes: 23a3647bc4f93bac ("ip_tunnels: Use skb-len to PMTU check.") Cc: Pravin B Shelar Signed-off-by: Timo Teräs Acked-by: Pravin B Shelar Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- net/ipv4/ip_tunnel.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c index 6c2719373bc5..51dd1605f944 100644 --- a/net/ipv4/ip_tunnel.c +++ b/net/ipv4/ip_tunnel.c @@ -488,7 +488,8 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb, EXPORT_SYMBOL_GPL(ip_tunnel_rcv); static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb, - struct rtable *rt, __be16 df) + struct rtable *rt, __be16 df, + const struct iphdr *inner_iph) { struct ip_tunnel *tunnel = netdev_priv(dev); int pkt_size = skb->len - tunnel->hlen - dev->hard_header_len; @@ -505,7 +506,8 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb, if (skb->protocol == htons(ETH_P_IP)) { if (!skb_is_gso(skb) && - (df & htons(IP_DF)) && mtu < pkt_size) { + (inner_iph->frag_off & htons(IP_DF)) && + mtu < pkt_size) { memset(IPCB(skb), 0, sizeof(*IPCB(skb))); icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); return -E2BIG; @@ -636,7 +638,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev, goto tx_error; } - if (tnl_update_pmtu(dev, skb, rt, tnl_params->frag_off)) { + if (tnl_update_pmtu(dev, skb, rt, tnl_params->frag_off, inner_iph)) { ip_rt_put(rt); goto tx_error; }