From: Antoine Tenart atenart@kernel.org
[ Upstream commit 68c1a943ef37bafde5ea2383e8ca224c7169ee31 ]
When the interface is part of a bridge or an Open vSwitch port and a packet exceed a PMTU estimate, an ICMP reply is sent to the sender. When using the external mode (collect metadata) the source and destination addresses are reversed, so that Open vSwitch can match the packet against an existing (reverse) flow.
But inverting the source and destination addresses in the shared ip_tunnel_info will make following packets of the flow to use a wrong destination address (packets will be tunnelled to itself), if the flow isn't updated. Which happens with Open vSwitch, until the flow times out.
Fixes this by uncloning the skb's ip_tunnel_info before inverting its source and destination addresses, so that the modification will only be made for the PTMU packet, not the following ones.
Fixes: c1a800e88dbf ("geneve: Support for PMTU discovery on directly bridged links") Tested-by: Eelco Chaudron echaudro@redhat.com Reviewed-by: Eelco Chaudron echaudro@redhat.com Signed-off-by: Antoine Tenart atenart@kernel.org Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/geneve.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c index 1426bfc009bc..abd37f26af68 100644 --- a/drivers/net/geneve.c +++ b/drivers/net/geneve.c @@ -907,8 +907,16 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
info = skb_tunnel_info(skb); if (info) { - info->key.u.ipv4.dst = fl4.saddr; - info->key.u.ipv4.src = fl4.daddr; + struct ip_tunnel_info *unclone; + + unclone = skb_tunnel_info_unclone(skb); + if (unlikely(!unclone)) { + dst_release(&rt->dst); + return -ENOMEM; + } + + unclone->key.u.ipv4.dst = fl4.saddr; + unclone->key.u.ipv4.src = fl4.daddr; }
if (!pskb_may_pull(skb, ETH_HLEN)) { @@ -992,8 +1000,16 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev, struct ip_tunnel_info *info = skb_tunnel_info(skb);
if (info) { - info->key.u.ipv6.dst = fl6.saddr; - info->key.u.ipv6.src = fl6.daddr; + struct ip_tunnel_info *unclone; + + unclone = skb_tunnel_info_unclone(skb); + if (unlikely(!unclone)) { + dst_release(dst); + return -ENOMEM; + } + + unclone->key.u.ipv6.dst = fl6.saddr; + unclone->key.u.ipv6.src = fl6.daddr; }
if (!pskb_may_pull(skb, ETH_HLEN)) {