bonding: disallow setting nested bonding + ipsec offload

bonding interface can be nested and it supports ipsec offload.
So, it allows setting the nested bonding + ipsec scenario.
But code does not support this scenario.
So, it should be disallowed.

interface graph:
bond2
   |
bond1
   |
eth0

The nested bonding + ipsec offload may not a real usecase.
So, disallowing this scenario is fine.

Fixes: 18cb261afd ("bonding: support hardware encryption offload to slaves")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -419,8 +419,9 @@ static int bond_ipsec_add_sa(struct xfrm_state *xs)
 	xs->xso.real_dev = slave->dev;
 	bond->xs = xs;
 
-	if (!(slave->dev->xfrmdev_ops
-	      && slave->dev->xfrmdev_ops->xdo_dev_state_add)) {
+	if (!slave->dev->xfrmdev_ops ||
+	    !slave->dev->xfrmdev_ops->xdo_dev_state_add ||
+	    netif_is_bond_master(slave->dev)) {
 		slave_warn(bond_dev, slave->dev, "Slave does not support ipsec offload\n");
 		rcu_read_unlock();
 		return -EINVAL;
@@ -453,8 +454,9 @@ static void bond_ipsec_del_sa(struct xfrm_state *xs)
 
 	xs->xso.real_dev = slave->dev;
 
-	if (!(slave->dev->xfrmdev_ops
-	      && slave->dev->xfrmdev_ops->xdo_dev_state_delete)) {
+	if (!slave->dev->xfrmdev_ops ||
+	    !slave->dev->xfrmdev_ops->xdo_dev_state_delete ||
+	    netif_is_bond_master(slave->dev)) {
 		slave_warn(bond_dev, slave->dev, "%s: no slave xdo_dev_state_delete\n", __func__);
 		goto out;
 	}
@@ -479,8 +481,9 @@ static bool bond_ipsec_offload_ok(struct sk_buff *skb, struct xfrm_state *xs)
 	if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP)
 		return true;
 
-	if (!(slave_dev->xfrmdev_ops
-	      && slave_dev->xfrmdev_ops->xdo_dev_offload_ok)) {
+	if (!slave_dev->xfrmdev_ops ||
+	    !slave_dev->xfrmdev_ops->xdo_dev_offload_ok ||
+	    netif_is_bond_master(slave_dev)) {
 		slave_warn(bond_dev, slave_dev, "%s: no slave xdo_dev_offload_ok\n", __func__);
 		return false;
 	}