bridge: Validate that vlan is permitted on ingress

When a frame arrives on a port or transmitted by the bridge,
if we have VLANs configured, validate that a given VLAN is allowed
to enter the bridge.

Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Vlad Yasevich

net/bridge/br_device.c

@@ -45,6 +45,9 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 	brstats->tx_bytes += skb->len;
 	u64_stats_update_end(&brstats->syncp);
 
+	if (!br_allowed_ingress(br, br_get_vlan_info(br), skb))
+		goto out;
+
 	BR_INPUT_SKB_CB(skb)->brdev = dev;
 
 	skb_reset_mac_header(skb);

net/bridge/br_input.c

@@ -17,6 +17,7 @@
 #include <linux/etherdevice.h>
 #include <linux/netfilter_bridge.h>
 #include <linux/export.h>
+#include <linux/rculist.h>
 #include "br_private.h"
 
 /* Hook for brouter */
@@ -54,6 +55,9 @@ int br_handle_frame_finish(struct sk_buff *skb)
 	if (!p || p->state == BR_STATE_DISABLED)
 		goto drop;
 
+	if (!br_allowed_ingress(p->br, nbp_get_vlan_info(p), skb))
+		goto drop;
+
 	/* insert into forwarding database after filtering to avoid spoofing */
 	br = p->br;
 	br_fdb_update(br, p, eth_hdr(skb)->h_source);

net/bridge/br_private.h

@@ -552,14 +552,52 @@ static inline void br_mdb_uninit(void)
 
 /* br_vlan.c */
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
+extern bool br_allowed_ingress(struct net_bridge *br, struct net_port_vlans *v,
+			       struct sk_buff *skb);
 extern int br_vlan_add(struct net_bridge *br, u16 vid);
 extern int br_vlan_delete(struct net_bridge *br, u16 vid);
 extern void br_vlan_flush(struct net_bridge *br);
 extern int br_vlan_filter_toggle(struct net_bridge *br, unsigned long val);
 extern int nbp_vlan_add(struct net_bridge_port *port, u16 vid);
 extern int nbp_vlan_delete(struct net_bridge_port *port, u16 vid);
 extern void nbp_vlan_flush(struct net_bridge_port *port);
+
+static inline struct net_port_vlans *br_get_vlan_info(
+						const struct net_bridge *br)
+{
+	return rcu_dereference(br->vlan_info);
+}
+
+static inline struct net_port_vlans *nbp_get_vlan_info(
+						const struct net_bridge_port *p)
+{
+	return rcu_dereference(p->vlan_info);
+}
+
+/* Since bridge now depends on 8021Q module, but the time bridge sees the
+ * skb, the vlan tag will always be present if the frame was tagged.
+ */
+static inline int br_vlan_get_tag(const struct sk_buff *skb, u16 *vid)
+{
+	int err = 0;
+
+	if (vlan_tx_tag_present(skb))
+		*vid = vlan_tx_tag_get(skb) & VLAN_VID_MASK;
+	else {
+		*vid = 0;
+		err = -EINVAL;
+	}
+
+	return err;
+}
 #else
+static inline bool br_allowed_ingress(struct net_bridge *br,
+				      struct net_port_vlans *v,
+				      struct sk_buff *skb)
+{
+	return true;
+}
+
 static inline int br_vlan_add(struct net_bridge *br, u16 vid)
 {
 	return -EOPNOTSUPP;
@@ -588,6 +626,21 @@ static inline void nbp_vlan_flush(struct net_bridge_port *port)
 {
 }
 
+static inline struct net_port_vlans *br_get_vlan_info(
+						const struct net_bridge *br)
+{
+	return NULL;
+}
+static inline struct net_port_vlans *nbp_get_vlan_info(
+						const struct net_bridge_port *p)
+{
+	return NULL;
+}
+
+static inline u16 br_vlan_get_tag(const struct sk_buff *skb)
+{
+	return 0;
+}
 #endif
 
 /* br_netfilter.c */

net/bridge/br_vlan.c

@@ -64,6 +64,31 @@ static void __vlan_flush(struct net_port_vlans *v)
 	kfree_rcu(v, rcu);
 }
 
+/* Called under RCU */
+bool br_allowed_ingress(struct net_bridge *br, struct net_port_vlans *v,
+			struct sk_buff *skb)
+{
+	u16 vid;
+
+	/* If VLAN filtering is disabled on the bridge, all packets are
+	 * permitted.
+	 */
+	if (!br->vlan_enabled)
+		return true;
+
+	/* If there are no vlan in the permitted list, all packets are
+	 * rejected.
+	 */
+	if (!v)
+		return false;
+
+	br_vlan_get_tag(skb, &vid);
+	if (test_bit(vid, v->vlan_bitmap))
+		return true;
+
+	return false;
+}
+
 /* Must be protected by RTNL */
 int br_vlan_add(struct net_bridge *br, u16 vid)
 {