cfg80211: allow registering to beacons

Add the ability to register to received beacon frames
to allow implementing OLBC logic in userspace. The
registration is per wiphy since there's no point in
receiving the same frame multiple times.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a8eda12..68b6708 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -891,6 +891,10 @@
 	if (dev->wiphy.flags & WIPHY_FLAG_SUPPORTS_SCHED_SCAN)
 		CMD(sched_scan_start, START_SCHED_SCAN);
 	CMD(probe_client, PROBE_CLIENT);
+	if (dev->wiphy.flags & WIPHY_FLAG_REPORTS_OBSS) {
+		i++;
+		NLA_PUT_U32(msg, i, NL80211_CMD_REGISTER_BEACONS);
+	}
 
 #undef CMD
 
@@ -5907,6 +5911,21 @@
 	return err;
 }
 
+static int nl80211_register_beacons(struct sk_buff *skb, struct genl_info *info)
+{
+	struct cfg80211_registered_device *rdev = info->user_ptr[0];
+
+	if (!(rdev->wiphy.flags & WIPHY_FLAG_REPORTS_OBSS))
+		return -EOPNOTSUPP;
+
+	if (rdev->ap_beacons_nlpid)
+		return -EBUSY;
+
+	rdev->ap_beacons_nlpid = info->snd_pid;
+
+	return 0;
+}
+
 #define NL80211_FLAG_NEED_WIPHY		0x01
 #define NL80211_FLAG_NEED_NETDEV	0x02
 #define NL80211_FLAG_NEED_RTNL		0x04
@@ -6478,6 +6497,14 @@
 		.internal_flags = NL80211_FLAG_NEED_NETDEV |
 				  NL80211_FLAG_NEED_RTNL,
 	},
+	{
+		.cmd = NL80211_CMD_REGISTER_BEACONS,
+		.doit = nl80211_register_beacons,
+		.policy = nl80211_policy,
+		.flags = GENL_ADMIN_PERM,
+		.internal_flags = NL80211_FLAG_NEED_WIPHY |
+				  NL80211_FLAG_NEED_RTNL,
+	},
 };
 
 static struct genl_multicast_group nl80211_mlme_mcgrp = {
@@ -7582,6 +7609,44 @@
 }
 EXPORT_SYMBOL(cfg80211_probe_status);
 
+void cfg80211_report_obss_beacon(struct wiphy *wiphy,
+				 const u8 *frame, size_t len,
+				 int freq, gfp_t gfp)
+{
+	struct cfg80211_registered_device *rdev = wiphy_to_dev(wiphy);
+	struct sk_buff *msg;
+	void *hdr;
+	u32 nlpid = ACCESS_ONCE(rdev->ap_beacons_nlpid);
+
+	if (!nlpid)
+		return;
+
+	msg = nlmsg_new(len + 100, gfp);
+	if (!msg)
+		return;
+
+	hdr = nl80211hdr_put(msg, 0, 0, 0, NL80211_CMD_FRAME);
+	if (!hdr) {
+		nlmsg_free(msg);
+		return;
+	}
+
+	NLA_PUT_U32(msg, NL80211_ATTR_WIPHY, rdev->wiphy_idx);
+	if (freq)
+		NLA_PUT_U32(msg, NL80211_ATTR_WIPHY_FREQ, freq);
+	NLA_PUT(msg, NL80211_ATTR_FRAME, len, frame);
+
+	genlmsg_end(msg, hdr);
+
+	genlmsg_unicast(wiphy_net(&rdev->wiphy), msg, nlpid);
+	return;
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	nlmsg_free(msg);
+}
+EXPORT_SYMBOL(cfg80211_report_obss_beacon);
+
 static int nl80211_netlink_notify(struct notifier_block * nb,
 				  unsigned long state,
 				  void *_notify)
@@ -7595,9 +7660,12 @@
 
 	rcu_read_lock();
 
-	list_for_each_entry_rcu(rdev, &cfg80211_rdev_list, list)
+	list_for_each_entry_rcu(rdev, &cfg80211_rdev_list, list) {
 		list_for_each_entry_rcu(wdev, &rdev->netdev_list, list)
 			cfg80211_mlme_unregister_socket(wdev, notify->pid);
+		if (rdev->ap_beacons_nlpid == notify->pid)
+			rdev->ap_beacons_nlpid = 0;
+	}
 
 	rcu_read_unlock();