[BRIDGE]: prevent bad forwarding table updates
Avoid poisoning of the bridge forwarding table by frames that have been
dropped by filtering. This prevents spoofed source addresses on hostile
side of bridge from causing packet leakage, a small but possible security
risk.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 2b1cce4..2aa5dda 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -54,6 +54,9 @@
struct net_bridge_fdb_entry *dst;
int passedup = 0;
+ /* insert into forwarding database after filtering to avoid spoofing */
+ br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
+
if (br->dev->flags & IFF_PROMISC) {
struct sk_buff *skb2;
@@ -108,8 +111,7 @@
if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
goto err;
- if (p->state == BR_STATE_LEARNING ||
- p->state == BR_STATE_FORWARDING)
+ if (p->state == BR_STATE_LEARNING)
br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
if (p->br->stp_enabled &&