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[BRIDGE]: prevent bad forwarding table updates

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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>
This commit is contained in:
Stephen Hemminger 2005-05-29 14:15:55 -07:00 committed by David S. Miller
parent 81d35307dd
commit 85967bb46d
2 changed files with 7 additions and 2 deletions
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6
net/bridge/br_input.c
View File

@ -54,6 +54,9 @@ int br_handle_frame_finish(struct sk_buff *skb)
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 @@ int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
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 &&

3
net/bridge/br_stp_bpdu.c
View File

@ -140,6 +140,9 @@ int br_stp_handle_bpdu(struct sk_buff *skb)
struct net_bridge *br = p->br;
unsigned char *buf;
/* insert into forwarding database after filtering to avoid spoofing */
br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
/* need at least the 802 and STP headers */
if (!pskb_may_pull(skb, sizeof(header)+1) ||
memcmp(skb->data, header, sizeof(header)))