From 85967bb46dd1f8f2c49b85a313866c00ac0c9b59 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Sun, 29 May 2005 14:15:55 -0700 Subject: [PATCH] [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 Signed-off-by: David S. Miller --- net/bridge/br_input.c | 6 ++++-- net/bridge/br_stp_bpdu.c | 3 +++ 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c index 2b1cce46cab4..2aa5dda24a08 100644 --- a/net/bridge/br_input.c +++ b/net/bridge/br_input.c @@ -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 && diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c index b91a875aca01..d071f1c9ad0b 100644 --- a/net/bridge/br_stp_bpdu.c +++ b/net/bridge/br_stp_bpdu.c @@ -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))) -- 2.20.1