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. Vlad Buslov (7): net: flow_offload: provision conntrack info in ct_metadata netfilter: flowtable: fixup UDP timeout depending on ct state netfilter: flowtable: allow unidirectional rules netfilter: flowtable: cache info of last offload net/sched: act_ct: set ctinfo in meta action depending on ct state net/sched: act_ct: offload UDP NEW connections netfilter: nf_conntrack: allow early drop of offloaded UDP conns .../ethernet/mellanox/mlx5/core/en/tc_ct.c | 4 ++ .../ethernet/netronome/nfp/flower/conntrack.c | 24 +++++++ include/net/netfilter/nf_flow_table.h | 8 ++- net/netfilter/nf_conntrack_core.c | 11 ++-- net/netfilter/nf_flow_table_core.c | 5 +- net/netfilter/nf_flow_table_inet.c | 2 +- net/netfilter/nf_flow_table_offload.c | 18 +++-- net/sched/act_ct.c | 65 ++++++++++++++----- 8 files changed, 103 insertions(+), 34 deletions(-) -- 2.38.1
