bridge: Add vlan filtering infrastructure

Adds an optional infrustructure component to bridge that would allow
native vlan filtering in the bridge. Each bridge port (as well
as the bridge device) now get a VLAN bitmap. Each bit in the bitmap
is associated with a vlan id. This way if the bit corresponding to
the vid is set in the bitmap that the packet with vid is allowed to
enter and exit the port.

Write access the bitmap is protected by RTNL and read access
protected by RCU.

Vlan functionality is disabled by default.

Signed-off-by: Vlad Yasevich <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/bridge/Kconfig

···
 	  Say N to exclude this support and reduce the binary size.
 
 	  If unsure, say Y.
+
+config BRIDGE_VLAN_FILTERING
+	bool "VLAN filtering"
+	depends on BRIDGE
+	depends on VLAN_8021Q
+	default n
+	---help---
+	  If you say Y here, then the Ethernet bridge will be able selectively
+	  receive and forward traffic based on VLAN information in the packet
+	  any VLAN information configured on the bridge port or bridge device.
+
+	  Say N to exclude this support and reduce the binary size.
+
+	  If unsure, say Y.

net/bridge/Makefile

···
 
 bridge-$(CONFIG_BRIDGE_IGMP_SNOOPING) += br_multicast.o br_mdb.o
 
+bridge-$(CONFIG_BRIDGE_VLAN_FILTERING) += br_vlan.o
+
 obj-$(CONFIG_BRIDGE_NF_EBTABLES) += netfilter/

net/bridge/br_if.c

···
 
 	br_ifinfo_notify(RTM_DELLINK, p);
 
+	nbp_vlan_flush(p);
 	br_fdb_delete_by_port(br, p, 1);
 
 	list_del_rcu(&p->list);

net/bridge/br_private.h

···
 #include <linux/netpoll.h>
 #include <linux/u64_stats_sync.h>
 #include <net/route.h>
+#include <linux/if_vlan.h>
 
 #define BR_HASH_BITS 8
 #define BR_HASH_SIZE (1 << BR_HASH_BITS)
···
 
 #define BR_PORT_BITS	10
 #define BR_MAX_PORTS	(1<<BR_PORT_BITS)
+#define BR_VLAN_BITMAP_LEN	BITS_TO_LONGS(VLAN_N_VID)
 
 #define BR_VERSION	"2.3"
 
···
 #endif
 	} u;
 	__be16		proto;
+};
+
+struct net_port_vlans {
+	u16				port_idx;
+	union {
+		struct net_bridge_port		*port;
+		struct net_bridge		*br;
+	}				parent;
+	struct rcu_head			rcu;
+	unsigned long			vlan_bitmap[BR_VLAN_BITMAP_LEN];
 };
 
 struct net_bridge_fdb_entry
···
 
 #ifdef CONFIG_NET_POLL_CONTROLLER
 	struct netpoll			*np;
+#endif
+#ifdef CONFIG_BRIDGE_VLAN_FILTERING
+	struct net_port_vlans __rcu	*vlan_info;
 #endif
 };
 
···
 	struct timer_list		topology_change_timer;
 	struct timer_list		gc_timer;
 	struct kobject			*ifobj;
+#ifdef CONFIG_BRIDGE_VLAN_FILTERING
+	u8				vlan_enabled;
+	struct net_port_vlans __rcu	*vlan_info;
+#endif
 };
 
 struct br_input_skb_cb {
···
 static inline void br_mdb_uninit(void)
 {
 }
+#endif
+
+/* br_vlan.c */
+#ifdef CONFIG_BRIDGE_VLAN_FILTERING
+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);
+#else
+static inline int br_vlan_add(struct net_bridge *br, u16 vid)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int br_vlan_delete(struct net_bridge *br, u16 vid)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void br_vlan_flush(struct net_bridge *br)
+{
+}
+
+static inline int nbp_vlan_add(struct net_bridge_port *port, u16 vid)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int nbp_vlan_delete(struct net_bridge_port *port, u16 vid)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void nbp_vlan_flush(struct net_bridge_port *port)
+{
+}
+
 #endif
 
 /* br_netfilter.c */

net/bridge/br_sysfs_br.c

···
 static DEVICE_ATTR(nf_call_arptables, S_IRUGO | S_IWUSR,
 		   show_nf_call_arptables, store_nf_call_arptables);
 #endif
+#ifdef CONFIG_BRIDGE_VLAN_FILTERING
+static ssize_t show_vlan_filtering(struct device *d,
+				   struct device_attribute *attr,
+				   char *buf)
+{
+	struct net_bridge *br = to_bridge(d);
+	return sprintf(buf, "%d\n", br->vlan_enabled);
+}
+
+static ssize_t store_vlan_filtering(struct device *d,
+				    struct device_attribute *attr,
+				    const char *buf, size_t len)
+{
+	return store_bridge_parm(d, buf, len, br_vlan_filter_toggle);
+}
+static DEVICE_ATTR(vlan_filtering, S_IRUGO | S_IWUSR,
+		   show_vlan_filtering, store_vlan_filtering);
+#endif
 
 static struct attribute *bridge_attrs[] = {
 	&dev_attr_forward_delay.attr,
···
 	&dev_attr_nf_call_iptables.attr,
 	&dev_attr_nf_call_ip6tables.attr,
 	&dev_attr_nf_call_arptables.attr,
+#endif
+#ifdef CONFIG_BRIDGE_VLAN_FILTERING
+	&dev_attr_vlan_filtering.attr,
 #endif
 	NULL
 };

net/bridge/br_vlan.c

···
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+
+#include "br_private.h"
+
+static int __vlan_add(struct net_port_vlans *v, u16 vid)
+{
+	int err;
+
+	if (test_bit(vid, v->vlan_bitmap))
+		return -EEXIST;
+
+	if (v->port_idx && vid) {
+		struct net_device *dev = v->parent.port->dev;
+
+		/* Add VLAN to the device filter if it is supported.
+		 * Stricly speaking, this is not necessary now, since devices
+		 * are made promiscuous by the bridge, but if that ever changes
+		 * this code will allow tagged traffic to enter the bridge.
+		 */
+		if (dev->features & NETIF_F_HW_VLAN_FILTER) {
+			err = dev->netdev_ops->ndo_vlan_rx_add_vid(dev, vid);
+			if (err)
+				return err;
+		}
+	}
+
+	set_bit(vid, v->vlan_bitmap);
+	return 0;
+}
+
+static int __vlan_del(struct net_port_vlans *v, u16 vid)
+{
+	if (!test_bit(vid, v->vlan_bitmap))
+		return -EINVAL;
+
+	if (v->port_idx && vid) {
+		struct net_device *dev = v->parent.port->dev;
+
+		if (dev->features & NETIF_F_HW_VLAN_FILTER)
+			dev->netdev_ops->ndo_vlan_rx_kill_vid(dev, vid);
+	}
+
+	clear_bit(vid, v->vlan_bitmap);
+	if (bitmap_empty(v->vlan_bitmap, BR_VLAN_BITMAP_LEN)) {
+		if (v->port_idx)
+			rcu_assign_pointer(v->parent.port->vlan_info, NULL);
+		else
+			rcu_assign_pointer(v->parent.br->vlan_info, NULL);
+		kfree_rcu(v, rcu);
+	}
+	return 0;
+}
+
+static void __vlan_flush(struct net_port_vlans *v)
+{
+	bitmap_zero(v->vlan_bitmap, BR_VLAN_BITMAP_LEN);
+	if (v->port_idx)
+		rcu_assign_pointer(v->parent.port->vlan_info, NULL);
+	else
+		rcu_assign_pointer(v->parent.br->vlan_info, NULL);
+	kfree_rcu(v, rcu);
+}
+
+/* Must be protected by RTNL */
+int br_vlan_add(struct net_bridge *br, u16 vid)
+{
+	struct net_port_vlans *pv = NULL;
+	int err;
+
+	ASSERT_RTNL();
+
+	pv = rtnl_dereference(br->vlan_info);
+	if (pv)
+		return __vlan_add(pv, vid);
+
+	/* Create port vlan infomration
+	 */
+	pv = kzalloc(sizeof(*pv), GFP_KERNEL);
+	if (!pv)
+		return -ENOMEM;
+
+	pv->parent.br = br;
+	err = __vlan_add(pv, vid);
+	if (err)
+		goto out;
+
+	rcu_assign_pointer(br->vlan_info, pv);
+	return 0;
+out:
+	kfree(pv);
+	return err;
+}
+
+/* Must be protected by RTNL */
+int br_vlan_delete(struct net_bridge *br, u16 vid)
+{
+	struct net_port_vlans *pv;
+
+	ASSERT_RTNL();
+
+	pv = rtnl_dereference(br->vlan_info);
+	if (!pv)
+		return -EINVAL;
+
+	__vlan_del(pv, vid);
+	return 0;
+}
+
+void br_vlan_flush(struct net_bridge *br)
+{
+	struct net_port_vlans *pv;
+
+	ASSERT_RTNL();
+
+	pv = rtnl_dereference(br->vlan_info);
+	if (!pv)
+		return;
+
+	__vlan_flush(pv);
+}
+
+int br_vlan_filter_toggle(struct net_bridge *br, unsigned long val)
+{
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	if (br->vlan_enabled == val)
+		goto unlock;
+
+	br->vlan_enabled = val;
+
+unlock:
+	rtnl_unlock();
+	return 0;
+}
+
+/* Must be protected by RTNL */
+int nbp_vlan_add(struct net_bridge_port *port, u16 vid)
+{
+	struct net_port_vlans *pv = NULL;
+	int err;
+
+	ASSERT_RTNL();
+
+	pv = rtnl_dereference(port->vlan_info);
+	if (pv)
+		return __vlan_add(pv, vid);
+
+	/* Create port vlan infomration
+	 */
+	pv = kzalloc(sizeof(*pv), GFP_KERNEL);
+	if (!pv) {
+		err = -ENOMEM;
+		goto clean_up;
+	}
+
+	pv->port_idx = port->port_no;
+	pv->parent.port = port;
+	err = __vlan_add(pv, vid);
+	if (err)
+		goto clean_up;
+
+	rcu_assign_pointer(port->vlan_info, pv);
+	return 0;
+
+clean_up:
+	kfree(pv);
+	return err;
+}
+
+/* Must be protected by RTNL */
+int nbp_vlan_delete(struct net_bridge_port *port, u16 vid)
+{
+	struct net_port_vlans *pv;
+
+	ASSERT_RTNL();
+
+	pv = rtnl_dereference(port->vlan_info);
+	if (!pv)
+		return -EINVAL;
+
+	return __vlan_del(pv, vid);
+}
+
+void nbp_vlan_flush(struct net_bridge_port *port)
+{
+	struct net_port_vlans *pv;
+
+	ASSERT_RTNL();
+
+	pv = rtnl_dereference(port->vlan_info);
+	if (!pv)
+		return;
+
+	__vlan_flush(pv);
+}