[PATCH 2/5] net: bridge: add flow offload helpers

[Daniel Pawlik]

Add three helpers that expose the bridge state needed by nft_flow_offload
without requiring callers to include net/bridge/br_private.h. Each
performs a single br_port_get_rcu() lookup:

 - br_fdb_has_forwarding_entry_rcu(): resolves the VLAN id for the packet
   (skb tag or PVID when filtering is on, 0 otherwise) then checks whether
   the bridge FDB contains a forwarding entry (dst != NULL, non-local) for
   the resulting MAC/VLAN pair.

 - br_vlan_get_offload_info_rcu(): when VLAN filtering is active, returns
   the VLAN id (skb tag or PVID) and writes the bridge VLAN protocol to
   *proto in a single port lookup. Returns 0 when filtering is off.

 - br_vlan_is_enabled_rcu(): returns true when VLAN filtering is enabled
   on the bridge a port device belongs to.

Based on MediaTek SDK patches by Bo-Cun Chen <bc-bocun.chen at mediatek.com>
and the OpenWrt bridge offload series by Ryan Chen <rchen14b at gmail.com>.
Signed-off-by: Daniel Pawlik <pawlik.dan at gmail.com>
---
 include/linux/if_bridge.h | 23 ++++++++++++++++++++
 net/bridge/br_fdb.c       | 32 ++++++++++++++++++++++++++++
 net/bridge/br_vlan.c      | 45 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 100 insertions(+)

diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
index 75673b8bffcb..c1cae54749c5 100644
--- a/include/linux/if_bridge.h
+++ b/include/linux/if_bridge.h
@@ -148,6 +148,9 @@ int br_vlan_get_info(const struct net_device *dev, u16 vid,
 		     struct bridge_vlan_info *p_vinfo);
 int br_vlan_get_info_rcu(const struct net_device *dev, u16 vid,
 			 struct bridge_vlan_info *p_vinfo);
+u16 br_vlan_get_offload_info_rcu(const struct net_device *dev,
+				 const struct sk_buff *skb, __be16 *proto);
+bool br_vlan_is_enabled_rcu(const struct net_device *dev);
 bool br_mst_enabled(const struct net_device *dev);
 int br_mst_get_info(const struct net_device *dev, u16 msti, unsigned long *vids);
 int br_mst_get_state(const struct net_device *dev, u16 msti, u8 *state);
@@ -184,6 +187,17 @@ static inline int br_vlan_get_info_rcu(const struct net_device *dev, u16 vid,
 	return -EINVAL;
 }
 
+static inline u16 br_vlan_get_offload_info_rcu(const struct net_device *dev,
+						const struct sk_buff *skb,
+						__be16 *proto)
+{
+	return 0;
+}
+
+static inline bool br_vlan_is_enabled_rcu(const struct net_device *dev)
+{
+	return false;
+}
 static inline bool br_mst_enabled(const struct net_device *dev)
 {
 	return false;
@@ -209,6 +223,8 @@ void br_fdb_clear_offload(const struct net_device *dev, u16 vid);
 bool br_port_flag_is_set(const struct net_device *dev, unsigned long flag);
 u8 br_port_get_stp_state(const struct net_device *dev);
 clock_t br_get_ageing_time(const struct net_device *br_dev);
+bool br_fdb_has_forwarding_entry_rcu(const struct net_device *dev,
+				     const struct sk_buff *skb, const u8 *addr);
 #else
 static inline struct net_device *
 br_fdb_find_port(const struct net_device *br_dev,
@@ -237,6 +253,13 @@ static inline clock_t br_get_ageing_time(const struct net_device *br_dev)
 {
 	return 0;
 }
+
+static inline bool br_fdb_has_forwarding_entry_rcu(const struct net_device *dev,
+						   const struct sk_buff *skb,
+						   const u8 *addr)
+{
+	return false;
+}
 #endif
 
 #endif
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index e4570bbed854..3161c2689f6a 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -267,6 +267,38 @@ struct net_bridge_fdb_entry *br_fdb_find_rcu(struct net_bridge *br,
 	return fdb_find_rcu(&br->fdb_hash_tbl, addr, vid);
 }
 
+/**
+ * br_fdb_has_forwarding_entry_rcu - check if a MAC can be forwarded by the bridge
+ * @dev: bridge port network device
+ * @skb: packet buffer (used to determine VLAN id)
+ * @addr: destination MAC address
+ *
+ * Resolves the VLAN id for @skb on @dev (skb VLAN tag when present, PVID
+ * when VLAN filtering is enabled, 0 otherwise) then checks whether the bridge
+ * FDB contains a forwarding entry (dst != NULL, not a local/self entry) for
+ * @addr and that VLAN id. Single br_port_get_rcu() lookup.
+ * Must be called under RCU read lock.
+ */
+bool br_fdb_has_forwarding_entry_rcu(const struct net_device *dev,
+				     const struct sk_buff *skb, const u8 *addr)
+{
+	struct net_bridge_port *port = br_port_get_rcu(dev);
+	struct net_bridge_fdb_entry *fdb;
+	u16 vid = 0;
+
+	if (!port)
+		return false;
+	if (br_opt_get(port->br, BROPT_VLAN_ENABLED)) {
+		if (skb_vlan_tag_present(skb))
+			vid = skb_vlan_tag_get_id(skb);
+		else
+			br_vlan_get_pvid_rcu(dev, &vid);
+	}
+	fdb = br_fdb_find_rcu(port->br, addr, vid);
+	return fdb && fdb->dst;
+}
+EXPORT_SYMBOL_GPL(br_fdb_has_forwarding_entry_rcu);
+
 /* When a static FDB entry is added, the mac address from the entry is
  * added to the bridge private HW address list and all required ports
  * are then updated with the new information.
diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index 5560afcaaca3..0b296362adf7 100644
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -1559,6 +1559,51 @@ int br_vlan_get_info_rcu(const struct net_device *dev, u16 vid,
 }
 EXPORT_SYMBOL_GPL(br_vlan_get_info_rcu);
 
+/**
+ * br_vlan_get_offload_info_rcu - get VLAN id and protocol for bridge flow offload
+ * @dev: bridge port network device
+ * @skb: packet buffer
+ * @proto: output for the bridge VLAN protocol (set only when return value != 0)
+ *
+ * When VLAN filtering is enabled, resolves the VLAN id for flow offload (skb
+ * VLAN tag id if present, PVID otherwise) and writes the bridge VLAN protocol
+ * to @proto. Returns 0 when filtering is off or @dev is not a bridge port.
+ * Single br_port_get_rcu() lookup. Must be called under RCU read lock.
+ */
+u16 br_vlan_get_offload_info_rcu(const struct net_device *dev,
+				 const struct sk_buff *skb, __be16 *proto)
+{
+	struct net_bridge_port *port = br_port_get_rcu(dev);
+	u16 vid = 0;
+
+	if (!port || !br_opt_get(port->br, BROPT_VLAN_ENABLED))
+		return 0;
+	if (skb_vlan_tag_present(skb))
+		vid = skb_vlan_tag_get_id(skb);
+	else
+		br_vlan_get_pvid_rcu(dev, &vid);
+	if (vid)
+		*proto = port->br->vlan_proto;
+	return vid;
+}
+EXPORT_SYMBOL_GPL(br_vlan_get_offload_info_rcu);
+
+/**
+ * br_vlan_is_enabled_rcu - check if VLAN filtering is active on a port's bridge
+ * @dev: bridge port network device
+ *
+ * Returns true if VLAN filtering is enabled on the bridge @dev belongs to.
+ * Returns false when @dev is not a bridge port or filtering is off.
+ * Must be called under RCU read lock.
+ */
+bool br_vlan_is_enabled_rcu(const struct net_device *dev)
+{
+	struct net_bridge_port *port = br_port_get_rcu(dev);
+
+	return port && br_opt_get(port->br, BROPT_VLAN_ENABLED);
+}
+EXPORT_SYMBOL_GPL(br_vlan_is_enabled_rcu);
+
 static int br_vlan_is_bind_vlan_dev(const struct net_device *dev)
 {
 	return is_vlan_dev(dev) &&
-- 
2.54.0