Patch "ip_tunnel: fix ipv4 pmtu check to honor inner ip header df" has been added to the 3.14-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ip_tunnel: fix ipv4 pmtu check to honor inner ip header df

to the 3.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ip_tunnel-fix-ipv4-pmtu-check-to-honor-inner-ip-header-df.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sat Sep 26 11:19:08 PDT 2015
From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>
Date: Tue, 7 Jul 2015 08:34:13 +0300
Subject: 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

From: =?UTF-8?q?Timo=20Ter=C3=A4s?= <timo.teras@iki.fi>

[ Upstream commit fc24f2b2094366da8786f59f2606307e934cea17 ]

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 <pshelar@nicira.com>
Signed-off-by: Timo Teräs <timo.teras@iki.fi>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/ipv4/ip_tunnel.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -484,7 +484,8 @@ drop:
 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;
@@ -501,7 +502,8 @@ static int tnl_update_pmtu(struct net_de
 
 	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;
@@ -632,7 +634,7 @@ void ip_tunnel_xmit(struct sk_buff *skb,
 		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;
 	}


Patches currently in stable-queue which might be from timo.teras@iki.fi are

queue-3.14/ip_tunnel-fix-ipv4-pmtu-check-to-honor-inner-ip-header-df.patch