recipes-kernel/linux/linux-mediatek-5.4/mediatek/patches-5.4/999-2726-mtkhnat-tnl-interface-offload-check.patch

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index c30952f..6c0860b 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -851,6 +851,7 @@ enum net_device_path_type {
 	DEV_PATH_DSA,
 	DEV_PATH_DSLITE,
 	DEV_PATH_6RD,
+	DEV_PATH_TNL,
 };
 
 struct net_device_path {
diff --git a/net/l2tp/l2tp_ppp.c b/net/l2tp/l2tp_ppp.c
index 7d3c782..d7a5a9a 100644
--- a/net/l2tp/l2tp_ppp.c
+++ b/net/l2tp/l2tp_ppp.c
@@ -89,6 +89,7 @@
 #include <linux/nsproxy.h>
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
+#include <net/netfilter/nf_flow_table.h>
 #include <net/ip.h>
 #include <net/udp.h>
 #include <net/inet_common.h>
@@ -124,9 +125,14 @@ struct pppol2tp_session {
 };
 
 static int pppol2tp_xmit(struct ppp_channel *chan, struct sk_buff *skb);
+static int l2tp_ppp_flow_offload_check(struct ppp_channel *chan,
+				       struct flow_offload_hw_path *path);
 
 static const struct ppp_channel_ops pppol2tp_chan_ops = {
 	.start_xmit =  pppol2tp_xmit,
+#if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
+	.flow_offload_check = l2tp_ppp_flow_offload_check,
+#endif /* IS_ENABLED(CONFIG_NF_FLOW_TABLE) */
 };
 
 static const struct proto_ops pppol2tp_ops;
@@ -335,6 +341,26 @@ static int pppol2tp_sendmsg(struct socket *sock, struct msghdr *m,
 	return error;
 }
 
+#if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
+static int l2tp_ppp_flow_offload_check(struct ppp_channel *chan,
+				       struct flow_offload_hw_path *path)
+{
+	struct sock *sk = (struct sock *)chan->private;
+	struct l2tp_session *session;
+
+	if (path->flags & BIT(DEV_PATH_TNL))
+		return -EEXIST;
+
+	session = pppol2tp_sock_to_session(sk);
+	if (!session)
+		return -EINVAL;
+
+	path->flags |= BIT(DEV_PATH_TNL);
+
+	return 0;
+}
+#endif /* IS_ENABLED(CONFIG_NF_FLOW_TABLE) */
+
 /* Transmit function called by generic PPP driver.  Sends PPP frame
  * over PPPoL2TP socket.
  *