From c65c7a306610ee7c13669a8f5601b472c19dc6f1 Mon Sep 17 00:00:00 2001 From: Jon Maxwell Date: Thu, 29 May 2014 17:27:16 +1000 Subject: bridge: notify user space after fdb update There has been a number incidents recently where customers running KVM have reported that VM hosts on different Hypervisors are unreachable. Based on pcap traces we found that the bridge was broadcasting the ARP request out onto the network. However some NICs have an inbuilt switch which on occasions were broadcasting the VMs ARP request back through the physical NIC on the Hypervisor. This resulted in the bridge changing ports and incorrectly learning that the VMs mac address was external. As a result the ARP reply was directed back onto the external network and VM never updated it's ARP cache. This patch will notify the bridge command, after a fdb has been updated to identify such port toggling. Signed-off-by: Jon Maxwell Reviewed-by: Jiri Pirko Acked-by: Toshiaki Makita Acked-by: Stephen Hemminger Signed-off-by: David S. Miller --- net/bridge/br_fdb.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'net/bridge') diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c index 9203d5a1943f..474d36f93342 100644 --- a/net/bridge/br_fdb.c +++ b/net/bridge/br_fdb.c @@ -487,6 +487,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, { struct hlist_head *head = &br->hash[br_mac_hash(addr, vid)]; struct net_bridge_fdb_entry *fdb; + bool fdb_modified = false; /* some users want to always flood. */ if (hold_time(br) == 0) @@ -507,10 +508,15 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, source->dev->name); } else { /* fastpath: update of existing entry */ - fdb->dst = source; + if (unlikely(source != fdb->dst)) { + fdb->dst = source; + fdb_modified = true; + } fdb->updated = jiffies; if (unlikely(added_by_user)) fdb->added_by_user = 1; + if (unlikely(fdb_modified)) + fdb_notify(br, fdb, RTM_NEWNEIGH); } } else { spin_lock(&br->hash_lock); -- cgit v1.2.3 From e0d7968ab6c8bce2437b36fa7f04117e333f196d Mon Sep 17 00:00:00 2001 From: Toshiaki Makita Date: Mon, 26 May 2014 15:15:53 +0900 Subject: 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 Acked-by: Vlad Yasevich Signed-off-by: David S. Miller --- net/bridge/br_input.c | 4 ++-- net/bridge/br_private.h | 7 +++++++ net/bridge/br_vlan.c | 28 ++++++++++++++++++++++++++++ 3 files changed, 37 insertions(+), 2 deletions(-) (limited to 'net/bridge') diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c index 7985deaff52f..04d6348fd530 100644 --- a/net/bridge/br_input.c +++ b/net/bridge/br_input.c @@ -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 */ } diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index 06811d79f89f..59d3a85c5873 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -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) diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c index 4a3716102789..5fee2feaf292 100644 --- a/net/bridge/br_vlan.c +++ b/net/bridge/br_vlan.c @@ -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. */ -- cgit v1.2.3