[PATCH net] net: sched: do not offload flows with a helper in act_ct

[Xin Long <lucien.xin@gmail.com>]

There is no hardware supporting ct helper offload. However, prior to this
patch, a flower filter with a helper in the ct action can be successfully
set into the HW, for example (eth1 is a bnxt NIC):

  # tc qdisc add dev eth1 ingress_block 22 ingress
  # tc filter add block 22 proto ip flower skip_sw ip_proto tcp \
    dst_port 21 ct_state -trk action ct helper ipv4-tcp-ftp
  # tc filter show dev eth1 ingress

    filter block 22 protocol ip pref 49152 flower chain 0 handle 0x1
      eth_type ipv4
      ip_proto tcp
      dst_port 21
      ct_state -trk
      skip_sw
      in_hw in_hw_count 1   <----
        action order 1: ct zone 0 helper ipv4-tcp-ftp pipe
         index 2 ref 1 bind 1
        used_hw_stats delayed

This might cause the flower filter not to work as expected in the HW.

This patch avoids this problem by simply returning -EOPNOTSUPP in
tcf_ct_offload_act_setup() to not allow to offload flows with a helper
in act_ct.

Fixes: a21b06e73191 ("net: sched: add helper support in act_ct")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 include/net/tc_act/tc_ct.h | 9 +++++++++
 net/sched/act_ct.c         | 3 +++
 2 files changed, 12 insertions(+)

diff --git a/include/net/tc_act/tc_ct.h b/include/net/tc_act/tc_ct.h
index 8a6dbfb23336..77f87c622a2e 100644
--- a/include/net/tc_act/tc_ct.h
+++ b/include/net/tc_act/tc_ct.h
@@ -58,6 +58,11 @@ static inline struct nf_flowtable *tcf_ct_ft(const struct tc_action *a)
 	return to_ct_params(a)->nf_ft;
 }
 
+static inline struct nf_conntrack_helper *tcf_ct_helper(const struct tc_action *a)
+{
+	return to_ct_params(a)->helper;
+}
+
 #else
 static inline uint16_t tcf_ct_zone(const struct tc_action *a) { return 0; }
 static inline int tcf_ct_action(const struct tc_action *a) { return 0; }
@@ -65,6 +70,10 @@ static inline struct nf_flowtable *tcf_ct_ft(const struct tc_action *a)
 {
 	return NULL;
 }
+static inline struct nf_conntrack_helper *tcf_ct_helper(const struct tc_action *a)
+{
+	return NULL;
+}
 #endif /* CONFIG_NF_CONNTRACK */
 
 #if IS_ENABLED(CONFIG_NET_ACT_CT)
diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 0db0ecf1d110..b3f4a503ee2b 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -1549,6 +1549,9 @@ static int tcf_ct_offload_act_setup(struct tc_action *act, void *entry_data,
 	if (bind) {
 		struct flow_action_entry *entry = entry_data;
 
+		if (tcf_ct_helper(act))
+			return -EOPNOTSUPP;
+
 		entry->id = FLOW_ACTION_CT;
 		entry->ct.action = tcf_ct_action(act);
 		entry->ct.zone = tcf_ct_zone(act);
-- 
2.39.1