rtnetlink: implement setting of master device

This patch allows userspace to enslave/release slave devices via netlink
interface using IFLA_MASTER. This introduces generic way to add/remove
underling devices.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 55 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 5a42b1003767..d08ef6538579 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -783,6 +783,14 @@ struct netdev_tc_txq {
  *      Set hardware filter for RFS.  rxq_index is the target queue index;
  *      flow_id is a flow ID to be passed to rps_may_expire_flow() later.
  *      Return the filter ID on success, or a negative error code.
+ *
+ *      Slave management functions (for bridge, bonding, etc). User should
+ *      call netdev_set_master() to set dev->master properly.
+ * int (*ndo_add_slave)(struct net_device *dev, struct net_device *slave_dev);
+ *      Called to make another netdev an underling.
+ *
+ * int (*ndo_del_slave)(struct net_device *dev, struct net_device *slave_dev);
+ *      Called to release previously enslaved netdev.
  */
 #define HAVE_NET_DEVICE_OPS
 struct net_device_ops {
@@ -862,6 +870,10 @@ struct net_device_ops {
                                                      u16 rxq_index,
                                                      u32 flow_id);
 #endif
+        int                     (*ndo_add_slave)(struct net_device *dev,
+                                                 struct net_device *slave_dev);
+        int                     (*ndo_del_slave)(struct net_device *dev,
+                                                 struct net_device *slave_dev);
 };
 
 /*
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index da0fe457c858..49f7ea5b4c75 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1036,6 +1036,7 @@ const struct nla_policy ifla_policy[IFLA_MAX+1] = {
         [IFLA_MAP]              = { .len = sizeof(struct rtnl_link_ifmap) },
         [IFLA_MTU]              = { .type = NLA_U32 },
         [IFLA_LINK]             = { .type = NLA_U32 },
+        [IFLA_MASTER]           = { .type = NLA_U32 },
         [IFLA_TXQLEN]           = { .type = NLA_U32 },
         [IFLA_WEIGHT]           = { .type = NLA_U32 },
         [IFLA_OPERSTATE]        = { .type = NLA_U8 },
@@ -1178,6 +1179,41 @@ static int do_setvfinfo(struct net_device *dev, struct nlattr *attr)
         return err;
 }
 
+static int do_set_master(struct net_device *dev, int ifindex)
+{
+        struct net_device *master_dev;
+        const struct net_device_ops *ops;
+        int err;
+
+        if (dev->master) {
+                if (dev->master->ifindex == ifindex)
+                        return 0;
+                ops = dev->master->netdev_ops;
+                if (ops->ndo_del_slave) {
+                        err = ops->ndo_del_slave(dev->master, dev);
+                        if (err)
+                                return err;
+                } else {
+                        return -EOPNOTSUPP;
+                }
+        }
+
+        if (ifindex) {
+                master_dev = __dev_get_by_index(dev_net(dev), ifindex);
+                if (!master_dev)
+                        return -EINVAL;
+                ops = master_dev->netdev_ops;
+                if (ops->ndo_add_slave) {
+                        err = ops->ndo_add_slave(master_dev, dev);
+                        if (err)
+                                return err;
+                } else {
+                        return -EOPNOTSUPP;
+                }
+        }
+        return 0;
+}
+
 static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
                       struct nlattr **tb, char *ifname, int modified)
 {
@@ -1301,6 +1337,13 @@ static int do_setlink(struct net_device *dev, struct ifinfomsg *ifm,
                         goto errout;
         }
 
+        if (tb[IFLA_MASTER]) {
+                err = do_set_master(dev, nla_get_u32(tb[IFLA_MASTER]));
+                if (err)
+                        goto errout;
+                modified = 1;
+        }
+
         if (tb[IFLA_TXQLEN])
                 dev->tx_queue_len = nla_get_u32(tb[IFLA_TXQLEN]);