netfilter: nf_tables: flow offload expression

Add new instruction for the nf_tables VM that allows us to specify what
flows are offloaded into a given flow table via name. This new
instruction creates the flow entry and adds it to the flow table.

Only established flows, ie. we have seen traffic in both directions, are
added to the flow table. You can still decide to offload entries at a
later stage via packet counting or checking the ct status in case you
want to offload assured conntracks.

This new extension depends on the conntrack subsystem.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 591b53bce070..53e8dd2a3a03 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -957,6 +957,17 @@ enum nft_ct_attributes {
 };
 #define NFTA_CT_MAX		(__NFTA_CT_MAX - 1)
 
+/**
+ * enum nft_flow_attributes - ct offload expression attributes
+ * @NFTA_FLOW_TABLE_NAME: flow table name (NLA_STRING)
+ */
+enum nft_offload_attributes {
+	NFTA_FLOW_UNSPEC,
+	NFTA_FLOW_TABLE_NAME,
+	__NFTA_FLOW_MAX,
+};
+#define NFTA_FLOW_MAX		(__NFTA_FLOW_MAX - 1)
+
 enum nft_limit_type {
 	NFT_LIMIT_PKTS,
 	NFT_LIMIT_PKT_BYTES