bridge: prevent bridging wrong device

The bridge code assumes ethernet addressing, so be more strict in
the what is allowed. This showed up when GRE had a bug and was not
using correct address format.

Add some more comments for increased clarity.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index b1b3b0fbf41c1b168c67f7ebdf93e3c8f9e32cf5..4a9f5273265584bc33ae2c54483a71ae00e6d72e 100644 (file)
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -377,12 +377,16 @@ int br_add_if(struct net_bridge *br, struct net_device *dev)
        struct net_bridge_port *p;
        int err = 0;
 
-       if (dev->flags & IFF_LOOPBACK || dev->type != ARPHRD_ETHER)
+       /* Don't allow bridging non-ethernet like devices */
+       if ((dev->flags & IFF_LOOPBACK) ||
+           dev->type != ARPHRD_ETHER || dev->addr_len != ETH_ALEN)
                return -EINVAL;
 
+       /* No bridging of bridges */
        if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit)
                return -ELOOP;
 
+       /* Device is already being bridged */
        if (dev->br_port != NULL)
                return -EBUSY;