vxlan: Flow based tunneling

Allows putting a VXLAN device into a new flow-based mode in which
skbs with a ip_tunnel_info dst metadata attached will be encapsulated
according to the instructions stored in there with the VXLAN device
defaults taken into consideration.

Similar on the receive side, if the VXLAN_F_COLLECT_METADATA flag is
set, the packet processing will populate a ip_tunnel_info struct for
each packet received and attach it to the skb using the new metadata
dst.  The metadata structure will contain the outer header and tunnel
header fields which have been stripped off. Layers further up in the
stack such as routing, tc or netfitler can later match on these fields
and perform forwarding. It is the responsibility of upper layers to
ensure that the flag is set if the metadata is needed. The flag limits
the additional cost of metadata collecting based on demand.

This prepares the VXLAN device to be steered by the routing and other
subsystems which allows to support encapsulation for a large number
of tunnel endpoints and tunnel ids through a single net_device which
improves the scalability.

It also allows for OVS to leverage this mode which in turn allows for
the removal of the OVS specific VXLAN code.

Because the skb is currently scrubed in vxlan_rcv(), the attachment of
the new dst metadata is postponed until after scrubing which requires
the temporary addition of a new member to vxlan_metadata. This member
is removed again in a later commit after the indirect VXLAN receive API
has been removed.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
index 4f7694f3c7d0..e843937fb30a 100644
--- a/include/net/dst_metadata.h
+++ b/include/net/dst_metadata.h
@@ -8,6 +8,9 @@
 struct metadata_dst {
 	struct dst_entry		dst;
 	size_t				opts_len;
+	union {
+		struct ip_tunnel_info	tun_info;
+	} u;
 };
 
 static inline struct metadata_dst *skb_metadata_dst(struct sk_buff *skb)
@@ -20,6 +23,16 @@ static inline struct metadata_dst *skb_metadata_dst(struct sk_buff *skb)
 	return NULL;
 }
 
+static inline struct ip_tunnel_info *skb_tunnel_info(struct sk_buff *skb)
+{
+	struct metadata_dst *md_dst = skb_metadata_dst(skb);
+
+	if (md_dst)
+		return &md_dst->u.tun_info;
+
+	return NULL;
+}
+
 static inline bool skb_valid_dst(const struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);