[PATCH 20/51] netfilter: nf_flow_table: add a new flow state for tearing down offloading

[Pablo Neira Ayuso]

From: Felix Fietkau <n...@nbd.name>

On cleanup, this will be treated differently from FLOW_OFFLOAD_DYING:

If FLOW_OFFLOAD_DYING is set, the connection is going away, so both the
offload state and the connection tracking entry will be deleted.

If FLOW_OFFLOAD_TEARDOWN is set, the connection remains alive, but
the offload state is torn down. This is useful for cases that require
more complex state tracking / timeout handling on TCP, or if the
connection has been idle for too long.

Support for sending flows back to the slow path will be implemented in
a following patch

Signed-off-by: Felix Fietkau <n...@nbd.name>
Signed-off-by: Pablo Neira Ayuso <pa...@netfilter.org>
---
 include/net/netfilter/nf_flow_table.h |  2 ++
 net/netfilter/nf_flow_table_core.c    | 22 ++++++++++++++--------
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/include/net/netfilter/nf_flow_table.h 
b/include/net/netfilter/nf_flow_table.h
index 5aa49524ebef..ba9fa4592f2b 100644
--- a/include/net/netfilter/nf_flow_table.h
+++ b/include/net/netfilter/nf_flow_table.h
@@ -68,6 +68,7 @@ struct flow_offload_tuple_rhash {
 #define FLOW_OFFLOAD_SNAT      0x1
 #define FLOW_OFFLOAD_DNAT      0x2
 #define FLOW_OFFLOAD_DYING     0x4
+#define FLOW_OFFLOAD_TEARDOWN  0x8
 
 struct flow_offload {
        struct flow_offload_tuple_rhash         tuplehash[FLOW_OFFLOAD_DIR_MAX];
@@ -103,6 +104,7 @@ void nf_flow_table_cleanup(struct net *net, struct 
net_device *dev);
 int nf_flow_table_init(struct nf_flowtable *flow_table);
 void nf_flow_table_free(struct nf_flowtable *flow_table);
 
+void flow_offload_teardown(struct flow_offload *flow);
 static inline void flow_offload_dead(struct flow_offload *flow)
 {
        flow->flags |= FLOW_OFFLOAD_DYING;
diff --git a/net/netfilter/nf_flow_table_core.c 
b/net/netfilter/nf_flow_table_core.c
index 0d38f20fd226..5a81e4f771e9 100644
--- a/net/netfilter/nf_flow_table_core.c
+++ b/net/netfilter/nf_flow_table_core.c
@@ -174,6 +174,12 @@ static void flow_offload_del(struct nf_flowtable 
*flow_table,
        flow_offload_free(flow);
 }
 
+void flow_offload_teardown(struct flow_offload *flow)
+{
+       flow->flags |= FLOW_OFFLOAD_TEARDOWN;
+}
+EXPORT_SYMBOL_GPL(flow_offload_teardown);
+
 struct flow_offload_tuple_rhash *
 flow_offload_lookup(struct nf_flowtable *flow_table,
                    struct flow_offload_tuple *tuple)
@@ -226,11 +232,6 @@ static inline bool nf_flow_has_expired(const struct 
flow_offload *flow)
        return (__s32)(flow->timeout - (u32)jiffies) <= 0;
 }
 
-static inline bool nf_flow_is_dying(const struct flow_offload *flow)
-{
-       return flow->flags & FLOW_OFFLOAD_DYING;
-}
-
 static int nf_flow_offload_gc_step(struct nf_flowtable *flow_table)
 {
        struct flow_offload_tuple_rhash *tuplehash;
@@ -258,7 +259,8 @@ static int nf_flow_offload_gc_step(struct nf_flowtable 
*flow_table)
                flow = container_of(tuplehash, struct flow_offload, 
tuplehash[0]);
 
                if (nf_flow_has_expired(flow) ||
-                   nf_flow_is_dying(flow))
+                   (flow->flags & (FLOW_OFFLOAD_DYING |
+                                   FLOW_OFFLOAD_TEARDOWN)))
                        flow_offload_del(flow_table, flow);
        }
 out:
@@ -419,10 +421,14 @@ static void nf_flow_table_do_cleanup(struct flow_offload 
*flow, void *data)
 {
        struct net_device *dev = data;
 
-       if (dev && flow->tuplehash[0].tuple.iifidx != dev->ifindex)
+       if (!dev) {
+               flow_offload_teardown(flow);
                return;
+       }
 
-       flow_offload_dead(flow);
+       if (flow->tuplehash[0].tuple.iifidx == dev->ifindex ||
+           flow->tuplehash[1].tuple.iifidx == dev->ifindex)
+               flow_offload_dead(flow);
 }
 
 static void nf_flow_table_iterate_cleanup(struct nf_flowtable *flowtable,
-- 
2.11.0