cfg80211: make aware of net namespaces

In order to make cfg80211/nl80211 aware of network namespaces,
we have to do the following things:

 * del_virtual_intf method takes an interface index rather
   than a netdev pointer - simply change this

 * nl80211 uses init_net a lot, it changes to use the sender's
   network namespace

 * scan requests use the interface index, hold a netdev pointer
   and reference instead

 * we want a wiphy and its associated virtual interfaces to be
   in one netns together, so
    - we need to be able to change ns for a given interface, so
      export dev_change_net_namespace()
    - for each virtual interface set the NETIF_F_NETNS_LOCAL
      flag, and clear that flag only when the wiphy changes ns,
      to disallow breaking this invariant

 * when a network namespace goes away, we need to reparent the
   wiphy to init_net

 * cfg80211 users that support creating virtual interfaces must
   create them in the wiphy's namespace, currently this affects
   only mac80211

The end result is that you can now switch an entire wiphy into
a different network namespace with the new command
	iw phy#<idx> set netns <pid>
and all virtual interfaces will follow (or the operation fails).

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 70 insertions, 5 deletions

diff --git a/net/wireless/core.c b/net/wireless/core.c
index 6891cd0e38d..442c9f38979 100644
--- a/net/wireless/core.c
+++ b/net/wireless/core.c
@@ -106,7 +106,7 @@ __cfg80211_rdev_from_info(struct genl_info *info)
 
 	if (info->attrs[NL80211_ATTR_IFINDEX]) {
 		ifindex = nla_get_u32(info->attrs[NL80211_ATTR_IFINDEX]);
-		dev = dev_get_by_index(&init_net, ifindex);
+		dev = dev_get_by_index(genl_info_net(info), ifindex);
 		if (dev) {
 			if (dev->ieee80211_ptr)
 				byifidx =
@@ -151,13 +151,13 @@ cfg80211_get_dev_from_info(struct genl_info *info)
 }
 
 struct cfg80211_registered_device *
-cfg80211_get_dev_from_ifindex(int ifindex)
+cfg80211_get_dev_from_ifindex(struct net *net, int ifindex)
 {
 	struct cfg80211_registered_device *rdev = ERR_PTR(-ENODEV);
 	struct net_device *dev;
 
 	mutex_lock(&cfg80211_mutex);
-	dev = dev_get_by_index(&init_net, ifindex);
+	dev = dev_get_by_index(net, ifindex);
 	if (!dev)
 		goto out;
 	if (dev->ieee80211_ptr) {
@@ -222,6 +222,42 @@ int cfg80211_dev_rename(struct cfg80211_registered_device *rdev,
 	return 0;
 }
 
+int cfg80211_switch_netns(struct cfg80211_registered_device *rdev,
+			  struct net *net)
+{
+	struct wireless_dev *wdev;
+	int err = 0;
+
+	if (!rdev->wiphy.netnsok)
+		return -EOPNOTSUPP;
+
+	list_for_each_entry(wdev, &rdev->netdev_list, list) {
+		wdev->netdev->features &= ~NETIF_F_NETNS_LOCAL;
+		err = dev_change_net_namespace(wdev->netdev, net, "wlan%d");
+		if (err)
+			break;
+		wdev->netdev->features |= NETIF_F_NETNS_LOCAL;
+	}
+
+	if (err) {
+		/* failed -- clean up to old netns */
+		net = wiphy_net(&rdev->wiphy);
+
+		list_for_each_entry_continue_reverse(wdev, &rdev->netdev_list,
+						     list) {
+			wdev->netdev->features &= ~NETIF_F_NETNS_LOCAL;
+			err = dev_change_net_namespace(wdev->netdev, net,
+							"wlan%d");
+			WARN_ON(err);
+			wdev->netdev->features |= NETIF_F_NETNS_LOCAL;
+		}
+	}
+
+	wiphy_net_set(&rdev->wiphy, net);
+
+	return err;
+}
+
 static void cfg80211_rfkill_poll(struct rfkill *rfkill, void *data)
 {
 	struct cfg80211_registered_device *rdev = data;
@@ -375,6 +411,8 @@ struct wiphy *wiphy_new(const struct cfg80211_ops *ops, int sizeof_priv)
 	rdev->wiphy.dev.class = &ieee80211_class;
 	rdev->wiphy.dev.platform_data = rdev;
 
+	wiphy_net_set(&rdev->wiphy, &init_net);
+
 	rdev->rfkill_ops.set_block = cfg80211_rfkill_set_block;
 	rdev->rfkill = rfkill_alloc(dev_name(&rdev->wiphy.dev),
 				   &rdev->wiphy.dev, RFKILL_TYPE_WLAN,
@@ -615,6 +653,9 @@ static int cfg80211_netdev_notifier_call(struct notifier_block * nb,
 		spin_lock_init(&wdev->event_lock);
 		mutex_lock(&rdev->devlist_mtx);
 		list_add(&wdev->list, &rdev->netdev_list);
+		/* can only change netns with wiphy */
+		dev->features |= NETIF_F_NETNS_LOCAL;
+
 		if (sysfs_create_link(&dev->dev.kobj, &rdev->wiphy.dev.kobj,
 				      "phy80211")) {
 			printk(KERN_ERR "wireless: failed to add phy80211 "
@@ -705,10 +746,32 @@ static struct notifier_block cfg80211_netdev_notifier = {
 	.notifier_call = cfg80211_netdev_notifier_call,
 };
 
-static int cfg80211_init(void)
+static void __net_exit cfg80211_pernet_exit(struct net *net)
+{
+	struct cfg80211_registered_device *rdev;
+
+	rtnl_lock();
+	mutex_lock(&cfg80211_mutex);
+	list_for_each_entry(rdev, &cfg80211_rdev_list, list) {
+		if (net_eq(wiphy_net(&rdev->wiphy), net))
+			WARN_ON(cfg80211_switch_netns(rdev, &init_net));
+	}
+	mutex_unlock(&cfg80211_mutex);
+	rtnl_unlock();
+}
+
+static struct pernet_operations cfg80211_pernet_ops = {
+	.exit = cfg80211_pernet_exit,
+};
+
+static int __init cfg80211_init(void)
 {
 	int err;
 
+	err = register_pernet_device(&cfg80211_pernet_ops);
+	if (err)
+		goto out_fail_pernet;
+
 	err = wiphy_sysfs_init();
 	if (err)
 		goto out_fail_sysfs;
@@ -736,9 +799,10 @@ out_fail_nl80211:
 out_fail_notifier:
 	wiphy_sysfs_exit();
 out_fail_sysfs:
+	unregister_pernet_device(&cfg80211_pernet_ops);
+out_fail_pernet:
 	return err;
 }
-
 subsys_initcall(cfg80211_init);
 
 static void cfg80211_exit(void)
@@ -748,5 +812,6 @@ static void cfg80211_exit(void)
 	unregister_netdevice_notifier(&cfg80211_netdev_notifier);
 	wiphy_sysfs_exit();
 	regulatory_exit();
+	unregister_pernet_device(&cfg80211_pernet_ops);
 }
 module_exit(cfg80211_exit);