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, 1 deletions

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index fcd12333c59b..939a59e15036 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -104,6 +104,7 @@ struct net_bridge_fdb_entry
 	mac_addr			addr;
 	unsigned char			is_local;
 	unsigned char			is_static;
+	unsigned char			added_by_user;
 	__u16				vlan_id;
 };
 
@@ -383,7 +384,7 @@ int br_fdb_fillbuf(struct net_bridge *br, void *buf, unsigned long count,
 int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
 		  const unsigned char *addr, u16 vid);
 void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
-		   const unsigned char *addr, u16 vid);
+		   const unsigned char *addr, u16 vid, bool added_by_user);
 int fdb_delete_by_addr(struct net_bridge *br, const u8 *addr, u16 vid);
 
 int br_fdb_delete(struct ndmsg *ndm, struct nlattr *tb[],