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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: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Toshiaki Makita 2014-05-26 15:15:53 +09:00 committed by David S. Miller
parent bfc5184b69
commit e0d7968ab6
3 changed files with 37 additions and 2 deletions
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4
net/bridge/br_input.c
View File

@ -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 */
}

7
net/bridge/br_private.h
View File

@ -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)

28
net/bridge/br_vlan.c
View File

@ -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.
*/