Merge branch 'net-rmnet-fix-several-bugs'

Taehee Yoo says:

====================
net: rmnet: fix several bugs

This patchset is to fix several bugs in RMNET module.

1. The first patch fixes NULL-ptr-deref in rmnet_newlink().
When rmnet interface is being created, it uses IFLA_LINK
without checking NULL.
So, if userspace doesn't set IFLA_LINK, panic will occur.
In this patch, checking NULL pointer code is added.

2. The second patch fixes NULL-ptr-deref in rmnet_changelink().
To get real device in rmnet_changelink(), it uses IFLA_LINK.
But, IFLA_LINK should not be used in rmnet_changelink().

3. The third patch fixes suspicious RCU usage in rmnet_get_port().
rmnet_get_port() uses rcu_dereference_rtnl().
But, rmnet_get_port() is used by datapath.
So, rcu_dereference_bh() should be used instead of rcu_dereference_rtnl().

4. The fourth patch fixes suspicious RCU usage in
rmnet_force_unassociate_device().
RCU critical section should not be scheduled.
But, unregister_netdevice_queue() in the rmnet_force_unassociate_device()
would be scheduled.
So, the RCU warning occurs.
In this patch, the rcu_read_lock() in the rmnet_force_unassociate_device()
is removed because it's unnecessary.

5. The fifth patch fixes duplicate MUX ID case.
RMNET MUX ID is unique.
So, rmnet interface isn't allowed to be created, which have
a duplicate MUX ID.
But, only rmnet_newlink() checks this condition, rmnet_changelink()
doesn't check this.
So, duplicate MUX ID case would happen.

6. The sixth patch fixes upper/lower interface relationship problems.
When IFLA_LINK is used, the upper/lower infrastructure should be used.
Because it checks the maximum depth of upper/lower interfaces and it also
checks circular interface relationship, etc.
In this patch, netdev_upper_dev_link() is used.

7. The seventh patch fixes bridge related problems.
a) ->ndo_del_slave() doesn't work.
b) It couldn't detect circular upper/lower interface relationship.
c) It couldn't prevent stack overflow because of too deep depth
of upper/lower interface
d) It doesn't check the number of lower interfaces.
e) Panics because of several reasons.
These problems are actually the same problem.
So, this patch fixes these problems.

8. The eighth patch fixes packet forwarding issue in bridge mode
Packet forwarding is not working in rmnet bridge mode.
Because when a packet is forwarded, skb_push() for an ethernet header
is needed. But it doesn't call skb_push().
So, the ethernet header will be lost.

Change log:
 - update commit logs.
 - drop two patches in this patchset because of wrong target branch.
   - ("net: rmnet: add missing module alias")
   - ("net: rmnet: print error message when command fails")
 - remove unneessary rcu_read_lock() in the third patch.
 - use rcu_dereference_bh() instead of rcu_dereference in third patch.
 - do not allow to add a bridge device if rmnet interface is already
   bridge mode in the seventh patch.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qualcomm/rmnet/rmnet_config.h

@@ -28,6 +28,7 @@ struct rmnet_port {
 	u8 rmnet_mode;
 	struct hlist_head muxed_ep[RMNET_MAX_LOGICAL_EP];
 	struct net_device *bridge_ep;
+	struct net_device *rmnet_dev;
 };
 
 extern struct rtnl_link_ops rmnet_link_ops;
@@ -65,7 +66,7 @@ struct rmnet_priv {
 	struct rmnet_priv_stats stats;
 };
 
-struct rmnet_port *rmnet_get_port(struct net_device *real_dev);
+struct rmnet_port *rmnet_get_port_rcu(struct net_device *real_dev);
 struct rmnet_endpoint *rmnet_get_endpoint(struct rmnet_port *port, u8 mux_id);
 int rmnet_add_bridge(struct net_device *rmnet_dev,
 		     struct net_device *slave_dev,

drivers/net/ethernet/qualcomm/rmnet/rmnet_handlers.c

@@ -159,6 +159,9 @@ static int rmnet_map_egress_handler(struct sk_buff *skb,
 static void
 rmnet_bridge_handler(struct sk_buff *skb, struct net_device *bridge_dev)
 {
+	if (skb_mac_header_was_set(skb))
+		skb_push(skb, skb->mac_len);
+
 	if (bridge_dev) {
 		skb->dev = bridge_dev;
 		dev_queue_xmit(skb);
@@ -184,7 +187,7 @@ rx_handler_result_t rmnet_rx_handler(struct sk_buff **pskb)
 		return RX_HANDLER_PASS;
 
 	dev = skb->dev;
-	port = rmnet_get_port(dev);
+	port = rmnet_get_port_rcu(dev);
 
 	switch (port->rmnet_mode) {
 	case RMNET_EPMODE_VND:
@@ -217,7 +220,7 @@ void rmnet_egress_handler(struct sk_buff *skb)
 	skb->dev = priv->real_dev;
 	mux_id = priv->mux_id;
 
-	port = rmnet_get_port(skb->dev);
+	port = rmnet_get_port_rcu(skb->dev);
 	if (!port)
 		goto drop;
 

drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.c

@@ -266,14 +266,6 @@ int rmnet_vnd_dellink(u8 id, struct rmnet_port *port,
 	return 0;
 }
 
-u8 rmnet_vnd_get_mux(struct net_device *rmnet_dev)
-{
-	struct rmnet_priv *priv;
-
-	priv = netdev_priv(rmnet_dev);
-	return priv->mux_id;
-}
-
 int rmnet_vnd_do_flow_control(struct net_device *rmnet_dev, int enable)
 {
 	netdev_dbg(rmnet_dev, "Setting VND TX queue state to %d\n", enable);

drivers/net/ethernet/qualcomm/rmnet/rmnet_vnd.h

@@ -16,6 +16,5 @@ int rmnet_vnd_dellink(u8 id, struct rmnet_port *port,
 		      struct rmnet_endpoint *ep);
 void rmnet_vnd_rx_fixup(struct sk_buff *skb, struct net_device *dev);
 void rmnet_vnd_tx_fixup(struct sk_buff *skb, struct net_device *dev);
-u8 rmnet_vnd_get_mux(struct net_device *rmnet_dev);
 void rmnet_vnd_setup(struct net_device *dev);
 #endif /* _RMNET_VND_H_ */