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Commit e0d7968a authored by Toshiaki Makita's avatar Toshiaki Makita Committed by David S. Miller
Browse files

bridge: Prevent insertion of FDB entry with disallowed vlan 



br_handle_local_finish() is allowing us to insert an FDB entry with
disallowed vlan. For example, when port 1 and 2 are communicating in
vlan 10, and even if vlan 10 is disallowed on port 3, port 3 can
interfere with their communication by spoofed src mac address with
vlan id 10.

Note: Even if it is judged that a frame should not be learned, it should
not be dropped because it is destined for not forwarding layer but higher
layer. See IEEE 802.1Q-2011 8.13.10.

Signed-off-by: default avatarToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: default avatarVlad Yasevich <vyasevic@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bfc5184b

net/bridge/br_input.c

+2 −2
Original line number Diff line number Diff line
@@ -147,8 +147,8 @@ static int br_handle_local_finish(struct sk_buff *skb) 
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);

	u16 vid = 0;



	br_vlan_get_tag(skb, &vid);

	if (p->flags & BR_LEARNING)

	/* check if vlan is allowed, to avoid spoofing */

	if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid))

		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);

	return 0;	 /* process further */

}

net/bridge/br_private.h

+7 −0
Original line number Diff line number Diff line
@@ -581,6 +581,7 @@ bool br_allowed_ingress(struct net_bridge *br, struct net_port_vlans *v, 
			struct sk_buff *skb, u16 *vid);

bool br_allowed_egress(struct net_bridge *br, const struct net_port_vlans *v,

		       const struct sk_buff *skb);

bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid);

struct sk_buff *br_handle_vlan(struct net_bridge *br,

			       const struct net_port_vlans *v,

			       struct sk_buff *skb);
@@ -648,6 +649,12 @@ static inline bool br_allowed_egress(struct net_bridge *br, 
	return true;

}



static inline bool br_should_learn(struct net_bridge_port *p,

				   struct sk_buff *skb, u16 *vid)

{

	return true;

}



static inline struct sk_buff *br_handle_vlan(struct net_bridge *br,

					     const struct net_port_vlans *v,

					     struct sk_buff *skb)

net/bridge/br_vlan.c

+28 −0
Original line number Diff line number Diff line
@@ -241,6 +241,34 @@ bool br_allowed_egress(struct net_bridge *br, 
	return false;

}



/* Called under RCU */

bool br_should_learn(struct net_bridge_port *p, struct sk_buff *skb, u16 *vid)

{

	struct net_bridge *br = p->br;

	struct net_port_vlans *v;



	if (!br->vlan_enabled)

		return true;



	v = rcu_dereference(p->vlan_info);

	if (!v)

		return false;



	br_vlan_get_tag(skb, vid);

	if (!*vid) {

		*vid = br_get_pvid(v);

		if (*vid == VLAN_N_VID)

			return false;



		return true;

	}



	if (test_bit(*vid, v->vlan_bitmap))

		return true;



	return false;

}



/* Must be protected by RTNL.

 * Must be called with vid in range from 1 to 4094 inclusive.

 */