net: bridge: add support for port isolation

This patch adds support for a new port flag - BR_ISOLATED. If it is set
then isolated ports cannot communicate between each other, but they can
still communicate with non-isolated ports. The same can be achieved via
ACLs but they can't scale with large number of ports and also the
complexity of the rules grows. This feature can be used to achieve
isolated vlan functionality (similar to pvlan) as well, though currently
it will be port-wide (for all vlans on the port). The new test in
should_deliver uses data that is already cache hot and the new boolean
is used to avoid an additional source port test in should_deliver.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Reviewed-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_forward.c

@@ -30,7 +30,8 @@ static inline int should_deliver(const struct net_bridge_port *p,
 	vg = nbp_vlan_group_rcu(p);
 	return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
 		br_allowed_egress(vg, skb) && p->state == BR_STATE_FORWARDING &&
-		nbp_switchdev_allowed_egress(p, skb);
+		nbp_switchdev_allowed_egress(p, skb) &&
+		!br_skb_isolated(p, skb);
 }
 
 int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)

net/bridge/br_input.c

@@ -114,6 +114,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
 		goto drop;
 
 	BR_INPUT_SKB_CB(skb)->brdev = br->dev;
+	BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
 
 	if (IS_ENABLED(CONFIG_INET) &&
 	    (skb->protocol == htons(ETH_P_ARP) ||

net/bridge/br_netlink.c

@@ -139,6 +139,7 @@ static inline size_t br_port_info_size(void)
 		+ nla_total_size(1)	/* IFLA_BRPORT_PROXYARP_WIFI */
 		+ nla_total_size(1)	/* IFLA_BRPORT_VLAN_TUNNEL */
 		+ nla_total_size(1)	/* IFLA_BRPORT_NEIGH_SUPPRESS */
+		+ nla_total_size(1)	/* IFLA_BRPORT_ISOLATED */
 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_ROOT_ID */
 		+ nla_total_size(sizeof(struct ifla_bridge_id))	/* IFLA_BRPORT_BRIDGE_ID */
 		+ nla_total_size(sizeof(u16))	/* IFLA_BRPORT_DESIGNATED_PORT */
@@ -213,7 +214,8 @@ static int br_port_fill_attrs(struct sk_buff *skb,
 							BR_VLAN_TUNNEL)) ||
 	    nla_put_u16(skb, IFLA_BRPORT_GROUP_FWD_MASK, p->group_fwd_mask) ||
 	    nla_put_u8(skb, IFLA_BRPORT_NEIGH_SUPPRESS,
-		       !!(p->flags & BR_NEIGH_SUPPRESS)))
+		       !!(p->flags & BR_NEIGH_SUPPRESS)) ||
+	    nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)))
 		return -EMSGSIZE;
 
 	timerval = br_timer_value(&p->message_age_timer);
@@ -660,6 +662,7 @@ static const struct nla_policy br_port_policy[IFLA_BRPORT_MAX + 1] = {
 	[IFLA_BRPORT_VLAN_TUNNEL] = { .type = NLA_U8 },
 	[IFLA_BRPORT_GROUP_FWD_MASK] = { .type = NLA_U16 },
 	[IFLA_BRPORT_NEIGH_SUPPRESS] = { .type = NLA_U8 },
+	[IFLA_BRPORT_ISOLATED]	= { .type = NLA_U8 },
 };
 
 /* Change the state of the port and notify spanning tree */
@@ -810,6 +813,10 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[])
 	if (err)
 		return err;
 
+	err = br_set_port_flag(p, tb, IFLA_BRPORT_ISOLATED, BR_ISOLATED);
+	if (err)
+		return err;
+
 	br_port_flags_change(p, old_flags ^ p->flags);
 	return 0;
 }

net/bridge/br_private.h

@@ -423,6 +423,7 @@ struct br_input_skb_cb {
 #endif
 
 	bool proxyarp_replied;
+	bool src_port_isolated;
 
 #ifdef CONFIG_BRIDGE_VLAN_FILTERING
 	bool vlan_filtered;
@@ -574,6 +575,14 @@ int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb);
 void br_flood(struct net_bridge *br, struct sk_buff *skb,
 	      enum br_pkt_type pkt_type, bool local_rcv, bool local_orig);
 
+/* return true if both source port and dest port are isolated */
+static inline bool br_skb_isolated(const struct net_bridge_port *to,
+				   const struct sk_buff *skb)
+{
+	return BR_INPUT_SKB_CB(skb)->src_port_isolated &&
+	       (to->flags & BR_ISOLATED);
+}
+
 /* br_if.c */
 void br_port_carrier_check(struct net_bridge_port *p, bool *notified);
 int br_add_bridge(struct net *net, const char *name);

net/bridge/br_sysfs_if.c

@@ -192,6 +192,7 @@ BRPORT_ATTR_FLAG(proxyarp_wifi, BR_PROXYARP_WIFI);
 BRPORT_ATTR_FLAG(multicast_flood, BR_MCAST_FLOOD);
 BRPORT_ATTR_FLAG(broadcast_flood, BR_BCAST_FLOOD);
 BRPORT_ATTR_FLAG(neigh_suppress, BR_NEIGH_SUPPRESS);
+BRPORT_ATTR_FLAG(isolated, BR_ISOLATED);
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
@@ -243,6 +244,7 @@ static const struct brport_attribute *brport_attrs[] = {
 	&brport_attr_broadcast_flood,
 	&brport_attr_group_fwd_mask,
 	&brport_attr_neigh_suppress,
+	&brport_attr_isolated,
 	NULL
 };