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

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 23a3647bc4 broke it, and this commit fixes
the ipv4 df check back to the way it was.

Fixes: 23a3647bc4 ("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>
This commit is contained in:
Timo Teräs 2015-07-07 08:34:13 +03:00 committed by David S. Miller
parent 4f7d2cdfdd
commit fc24f2b209
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
net/ipv4/ip_tunnel.c
View File

@ -586,7 +586,8 @@ int ip_tunnel_encap(struct sk_buff *skb, struct ip_tunnel *t,
EXPORT_SYMBOL(ip_tunnel_encap);
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;
@ -603,7 +604,8 @@ 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;
@ -737,7 +739,7 @@ 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;
}