Merge branch 'act_ct-UDP-NEW'

Vlad Buslov says:

====================
net: Allow offloading of UDP NEW connections via act_ct

Currently only bidirectional established connections can be offloaded
via act_ct. Such approach allows to hardcode a lot of assumptions into
act_ct, flow_table and flow_offload intermediate layer codes. In order
to enabled offloading of unidirectional UDP NEW connections start with
incrementally changing the following assumptions:

- Drivers assume that only established connections are offloaded and
  don't support updating existing connections. Extract ctinfo from meta
  action cookie and refuse offloading of new connections in the drivers.

- Fix flow_table offload fixup algorithm to calculate flow timeout
  according to current connection state instead of hardcoded
  "established" value.

- Add new flow_table flow flag that designates bidirectional connections
  instead of assuming it and hardcoding hardware offload of every flow
  in both directions.

- Add new flow_table flow flag that designates connections that are
  offloaded to hardware as "established" instead of assuming it. This
  allows some optimizations in act_ct and prevents spamming the
  flow_table workqueue with redundant tasks.

With all the necessary infrastructure in place modify act_ct to offload
UDP NEW as unidirectional connection. Pass reply direction traffic to CT
and promote connection to bidirectional when UDP connection state
changes to "assured". Rely on refresh mechanism to propagate connection
state change to supporting drivers.

Note that early drop algorithm that is designed to free up some space in
connection tracking table when it becomes full (by randomly deleting up
to 5% of non-established connections) currently ignores connections
marked as "offloaded". Now, with UDP NEW connections becoming
"offloaded" it could allow malicious user to perform DoS attack by
filling the table with non-droppable UDP NEW connections by sending just
one packet in single direction. To prevent such scenario change early
drop algorithm to also consider "offloaded" connections for deletion.
====================

Signed-off-by: David S. Miller <[email protected]>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/net/netfilter/nf_flow_table.h b/include/net/netfilter/nf_flow_table.h
index cd982f4a0f50..ebb28ec5b6fa 100644
--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -57,7 +57,7 @@ struct nf_flowtable_type {
 						 struct net_device *dev,
 						 enum flow_block_command cmd);
 	int				(*action)(struct net *net,
-						  const struct flow_offload *flow,
+						  struct flow_offload *flow,
 						  enum flow_offload_tuple_dir dir,
 						  struct nf_flow_rule *flow_rule);
 	void				(*free)(struct nf_flowtable *ft);
@@ -164,6 +164,8 @@ enum nf_flow_flags {
 	NF_FLOW_HW_DYING,
 	NF_FLOW_HW_DEAD,
 	NF_FLOW_HW_PENDING,
+	NF_FLOW_HW_BIDIRECTIONAL,
+	NF_FLOW_HW_ESTABLISHED,
 };
 
 enum flow_offload_type {
@@ -312,10 +314,10 @@ void nf_flow_table_offload_flush_cleanup(struct nf_flowtable *flowtable);
 int nf_flow_table_offload_setup(struct nf_flowtable *flowtable,
 				struct net_device *dev,
 				enum flow_block_command cmd);
-int nf_flow_rule_route_ipv4(struct net *net, const struct flow_offload *flow,
+int nf_flow_rule_route_ipv4(struct net *net, struct flow_offload *flow,
 			    enum flow_offload_tuple_dir dir,
 			    struct nf_flow_rule *flow_rule);
-int nf_flow_rule_route_ipv6(struct net *net, const struct flow_offload *flow,
+int nf_flow_rule_route_ipv6(struct net *net, struct flow_offload *flow,
 			    enum flow_offload_tuple_dir dir,
 			    struct nf_flow_rule *flow_rule);