mac80211_hwsim: Allow managing radios from non-initial namespaces

While wiphys can be moved into network namespaces over nl80211, the
creation and removal of hwsim radios is currently limited to the initial
namespace. This patch allows management of namespaced radios from the
owning namespace by setting genetlink netnsok.

To prevent two arbitrary namespaces to communicate over the simulated
shared medium, radios are separated by netgroups. Each radio created in
the same namespace lives in the same netgroup and hence can communicate
with other radios in that group. When moving radios to other namespaces,
the netgroup is preserved, so two radios having the same netgroup can
communicate even if not in the same namespace; This allows a controlling
namespace to create radios and move them to other namespaces for
communication.

When a net namespace owning a radio exits, the radio is destroyed unless
it was created in the initial network namespace. This keeps the previous
behavior by returning them to the init namespace, but prevents unprivileged
users from creating radios in the initial namespace.

Signed-off-by: Martin Willi <[e-mail]>
Signed-off-by: Johannes Berg <[e-mail]>

drivers/net/wireless/mac80211_hwsim.c

···
 #include <linux/module.h>
 #include <linux/ktime.h>
 #include <net/genetlink.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
 #include "mac80211_hwsim.h"
 
 #define WARN_QUEUE 100
···
 {
 	struct hwsim_chanctx_priv *cp = (void *)c->drv_priv;
 	cp->magic = 0;
+}
+
+static unsigned int hwsim_net_id;
+
+static int hwsim_netgroup;
+
+struct hwsim_net {
+	int netgroup;
+};
+
+static inline int hwsim_net_get_netgroup(struct net *net)
+{
+	struct hwsim_net *hwsim_net = net_generic(net, hwsim_net_id);
+
+	return hwsim_net->netgroup;
+}
+
+static inline void hwsim_net_set_netgroup(struct net *net)
+{
+	struct hwsim_net *hwsim_net = net_generic(net, hwsim_net_id);
+
+	hwsim_net->netgroup = hwsim_netgroup++;
 }
 
 static struct class *hwsim_class;
···
 	 */
 	u64 group;
 
+	/* group shared by radios created in the same netns */
+	int netgroup;
+
 	int power_level;
 
 	/* difference between this hw's clock and the real clock, in usecs */
···
 	.name = "MAC80211_HWSIM",
 	.version = 1,
 	.maxattr = HWSIM_ATTR_MAX,
+	.netnsok = true,
 };
 
 enum hwsim_multicast_groups {
···
 			continue;
 
 		if (!(data->group & data2->group))
+			continue;
+
+		if (data->netgroup != data2->netgroup)
 			continue;
 
 		if (!hwsim_chans_compat(chan, data2->tmp_chan) &&
···
 	struct ieee80211_hw *hw;
 	enum nl80211_band band;
 	const struct ieee80211_ops *ops = &mac80211_hwsim_ops;
+	struct net *net;
 	int idx;
 
 	if (WARN_ON(param->channels > 1 && !param->use_chanctx))
···
 		err = -ENOMEM;
 		goto failed;
 	}
+
+	if (info)
+		net = genl_info_net(info);
+	else
+		net = &init_net;
+	wiphy_net_set(hw->wiphy, net);
+
 	data = hw->priv;
 	data->hw = hw;
 
···
 	/* By default all radios belong to the first group */
 	data->group = 1;
 	mutex_init(&data->mutex);
+
+	data->netgroup = hwsim_net_get_netgroup(net);
 
 	/* Enable frame retransmissions for lossy channels */
 	hw->max_rates = 4;
···
 				continue;
 		}
 
+		if (!net_eq(wiphy_net(data->hw->wiphy), genl_info_net(info)))
+			continue;
+
 		list_del(&data->list);
 		spin_unlock_bh(&hwsim_radio_lock);
 		mac80211_hwsim_del_radio(data, wiphy_name(data->hw->wiphy),
···
 	spin_lock_bh(&hwsim_radio_lock);
 	list_for_each_entry(data, &hwsim_radios, list) {
 		if (data->idx != idx)
+			continue;
+
+		if (!net_eq(wiphy_net(data->hw->wiphy), genl_info_net(info)))
 			continue;
 
 		skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
···
 		if (data->idx < idx)
 			continue;
 
+		if (!net_eq(wiphy_net(data->hw->wiphy), sock_net(skb->sk)))
+			continue;
+
 		res = mac80211_hwsim_get_radio(skb, data,
 					       NETLINK_CB(cb->skb).portid,
 					       cb->nlh->nlmsg_seq, cb,
···
 		.cmd = HWSIM_CMD_NEW_RADIO,
 		.policy = hwsim_genl_policy,
 		.doit = hwsim_new_radio_nl,
-		.flags = GENL_ADMIN_PERM,
+		.flags = GENL_UNS_ADMIN_PERM,
 	},
 	{
 		.cmd = HWSIM_CMD_DEL_RADIO,
 		.policy = hwsim_genl_policy,
 		.doit = hwsim_del_radio_nl,
-		.flags = GENL_ADMIN_PERM,
+		.flags = GENL_UNS_ADMIN_PERM,
 	},
 	{
 		.cmd = HWSIM_CMD_GET_RADIO,
···
 	return -EINVAL;
 }
 
+static __net_init int hwsim_init_net(struct net *net)
+{
+	hwsim_net_set_netgroup(net);
+
+	return 0;
+}
+
+static void __net_exit hwsim_exit_net(struct net *net)
+{
+	struct mac80211_hwsim_data *data, *tmp;
+
+	spin_lock_bh(&hwsim_radio_lock);
+	list_for_each_entry_safe(data, tmp, &hwsim_radios, list) {
+		if (!net_eq(wiphy_net(data->hw->wiphy), net))
+			continue;
+
+		/* Radios created in init_net are returned to init_net. */
+		if (data->netgroup == hwsim_net_get_netgroup(&init_net))
+			continue;
+
+		list_del(&data->list);
+		INIT_WORK(&data->destroy_work, destroy_radio);
+		schedule_work(&data->destroy_work);
+	}
+	spin_unlock_bh(&hwsim_radio_lock);
+}
+
+static struct pernet_operations hwsim_net_ops = {
+	.init = hwsim_init_net,
+	.exit = hwsim_exit_net,
+	.id   = &hwsim_net_id,
+	.size = sizeof(struct hwsim_net),
+};
+
 static void hwsim_exit_netlink(void)
 {
 	/* unregister the notifier */
···
 	spin_lock_init(&hwsim_radio_lock);
 	INIT_LIST_HEAD(&hwsim_radios);
 
-	err = platform_driver_register(&mac80211_hwsim_driver);
+	err = register_pernet_device(&hwsim_net_ops);
 	if (err)
 		return err;
+
+	err = platform_driver_register(&mac80211_hwsim_driver);
+	if (err)
+		goto out_unregister_pernet;
 
 	hwsim_class = class_create(THIS_MODULE, "mac80211_hwsim");
 	if (IS_ERR(hwsim_class)) {
···
 	mac80211_hwsim_free();
 out_unregister_driver:
 	platform_driver_unregister(&mac80211_hwsim_driver);
+out_unregister_pernet:
+	unregister_pernet_device(&hwsim_net_ops);
 	return err;
 }
 module_init(init_mac80211_hwsim);
···
 	mac80211_hwsim_free();
 	unregister_netdev(hwsim_mon);
 	platform_driver_unregister(&mac80211_hwsim_driver);
+	unregister_pernet_device(&hwsim_net_ops);
 }
 module_exit(exit_mac80211_hwsim);