bridge: Fix the way to find old local fdb entries in br_fdb_changeaddr

br_fdb_changeaddr() assumes that there is at most one local entry per port
per vlan. It used to be true, but since commit 36fd2b63e3b4 ("bridge: allow
creating/deleting fdb entries via netlink"), it has not been so.
Therefore, the function might fail to search a correct previous address
to be deleted and delete an arbitrary local entry if user has added local
entries manually.

Example of problematic case:
  ip link set eth0 address ee:ff:12:34:56:78
  brctl addif br0 eth0
  bridge fdb add 12:34:56:78:90:ab dev eth0 master
  ip link set eth0 address aa:bb:cc:dd:ee:ff
Then, the address 12:34:56:78:90:ab might be deleted instead of
ee:ff:12:34:56:78, the original mac address of eth0.

Address this issue by introducing a new flag, added_by_user, to struct
net_bridge_fdb_entry.

Note that br_fdb_delete_by_port() has to set added_by_user to 0 in cases
like:
  ip link set eth0 address 12:34:56:78:90:ab
  ip link set eth1 address aa:bb:cc:dd:ee:ff
  brctl addif br0 eth0
  bridge fdb add aa:bb:cc:dd:ee:ff dev eth0 master
  brctl addif br0 eth1
  brctl delif br0 eth0
In this case, kernel should delete the user-added entry aa:bb:cc:dd:ee:ff,
but it also should have been added by "brctl addif br0 eth1" originally,
so we don't delete it and treat it a new kernel-created entry.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index bf8dc7d308d..28d54462742 100644
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -77,7 +77,7 @@ int br_handle_frame_finish(struct sk_buff *skb)
 	/* insert into forwarding database after filtering to avoid spoofing */
 	br = p->br;
 	if (p->flags & BR_LEARNING)
-		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid);
+		br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false);
 
 	if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&
 	    br_multicast_rcv(br, p, skb, vid))
@@ -148,7 +148,7 @@ static int br_handle_local_finish(struct sk_buff *skb)
 
 	br_vlan_get_tag(skb, &vid);
 	if (p->flags & BR_LEARNING)
-		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid);
+		br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false);
 	return 0;	 /* process further */
 }