mac80211: Add support for hardware ARP query filtering

Some hardware allow extended filtering of ARP frames not intended for
the host. To perform such filtering, the hardware needs to know the current
IP address(es) of the host, bound to its interface.

Add support for ARP filtering to mac80211 by adding a new op to the driver
interface, allowing to configure the current IP addresses. This op is called
upon association with the currently configured address(es), and when
associated whenever the IP address(es) change.

This patch adds configuration of IPv4 addresses only, as IPv6 addresses don't
need ARP filtering.

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 62 insertions, 1 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index c8548e61f86..4051b232c6e 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -329,6 +329,58 @@ static void ieee80211_recalc_smps_work(struct work_struct *work)
 	mutex_unlock(&local->iflist_mtx);
 }
 
+int ieee80211_set_arp_filter(struct ieee80211_sub_if_data *sdata)
+{
+	struct in_device *idev;
+	int ret = 0;
+
+	BUG_ON(!sdata);
+	ASSERT_RTNL();
+
+	idev = sdata->dev->ip_ptr;
+	if (!idev)
+		return 0;
+
+	ret = drv_configure_arp_filter(sdata->local, &sdata->vif,
+				       idev->ifa_list);
+	return ret;
+}
+
+static int ieee80211_ifa_changed(struct notifier_block *nb,
+				 unsigned long data, void *arg)
+{
+	struct in_ifaddr *ifa = arg;
+	struct ieee80211_local *local =
+		container_of(nb, struct ieee80211_local,
+			     ifa_notifier);
+	struct net_device *ndev = ifa->ifa_dev->dev;
+	struct wireless_dev *wdev = ndev->ieee80211_ptr;
+	struct ieee80211_sub_if_data *sdata;
+	struct ieee80211_if_managed *ifmgd;
+
+	/* Make sure it's our interface that got changed */
+	if (!wdev)
+		return NOTIFY_DONE;
+
+	if (wdev->wiphy != local->hw.wiphy)
+		return NOTIFY_DONE;
+
+	/* We are concerned about IP addresses only when associated */
+	sdata = IEEE80211_DEV_TO_SUB_IF(ndev);
+
+	/* ARP filtering is only supported in managed mode */
+	if (sdata->vif.type != NL80211_IFTYPE_STATION)
+		return NOTIFY_DONE;
+
+	ifmgd = &sdata->u.mgd;
+	mutex_lock(&ifmgd->mtx);
+	if (ifmgd->associated)
+		ieee80211_set_arp_filter(sdata);
+	mutex_unlock(&ifmgd->mtx);
+
+	return NOTIFY_DONE;
+}
+
 struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
 					const struct ieee80211_ops *ops)
 {
@@ -612,14 +664,22 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 		ieee80211_max_network_latency;
 	result = pm_qos_add_notifier(PM_QOS_NETWORK_LATENCY,
 				     &local->network_latency_notifier);
-
 	if (result) {
 		rtnl_lock();
 		goto fail_pm_qos;
 	}
 
+	local->ifa_notifier.notifier_call = ieee80211_ifa_changed;
+	result = register_inetaddr_notifier(&local->ifa_notifier);
+	if (result)
+		goto fail_ifa;
+
 	return 0;
 
+ fail_ifa:
+	pm_qos_remove_notifier(PM_QOS_NETWORK_LATENCY,
+			       &local->network_latency_notifier);
+	rtnl_lock();
  fail_pm_qos:
 	ieee80211_led_exit(local);
 	ieee80211_remove_interfaces(local);
@@ -647,6 +707,7 @@ void ieee80211_unregister_hw(struct ieee80211_hw *hw)
 
 	pm_qos_remove_notifier(PM_QOS_NETWORK_LATENCY,
 			       &local->network_latency_notifier);
+	unregister_inetaddr_notifier(&local->ifa_notifier);
 
 	rtnl_lock();