[PATCH v3 04/11] wifi: cfg80211: do not use NAN beacons to update the BSS table

[Ilan Peer <ilan.peer@intel.com>]

As NAN beacons have a different structure compared to beacons
defined in the IEEE802.11 specification, e.g., they do not contain
a SSID element etc., they cannot be used to update the BSS table.

Add a utility function to check if a frame is a NAN beacon and
use it do return early in cfg80211_inform_bss_frame_data().

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
---
 include/linux/ieee80211-nan.h | 26 ++++++++++++++++++++++++++
 net/wireless/scan.c           |  4 ++++
 2 files changed, 30 insertions(+)

diff --git a/include/linux/ieee80211-nan.h b/include/linux/ieee80211-nan.h
index 455033955e54..b332a94671ba 100644
--- a/include/linux/ieee80211-nan.h
+++ b/include/linux/ieee80211-nan.h
@@ -74,4 +74,30 @@ struct ieee80211_nan_anchor_master_info {
 	     _attr = (const struct ieee80211_nan_attr *)		\
 		(_attr->data + le16_to_cpu(_attr->length)))
 
+static inline bool ieee80211_is_nan_beacon(const struct ieee80211_mgmt *mgmt,
+					   size_t len)
+{
+	const struct element *elem;
+
+	/* The NAN IE is at least 6 octets */
+	if (len < offsetofend(struct ieee80211_mgmt, u.beacon) + 6)
+		return false;
+
+	if (!ieee80211_is_beacon(mgmt->frame_control))
+		return false;
+
+	/* NAN Cluster IDs range from 50-6F-9A-01-00-00 to 50-6F-9A-01-FF-FF */
+	if (get_unaligned_be32(mgmt->bssid) != ((WLAN_OUI_WFA << 8) | 0x01))
+		return false;
+
+	elem = (const struct element *)mgmt->u.beacon.variable;
+	if (elem->id != WLAN_EID_VENDOR_SPECIFIC ||
+	    elem->datalen < 4 ||
+	    get_unaligned_be32(elem->data) !=
+	    (WLAN_OUI_WFA << 8 | WLAN_OUI_TYPE_WFA_NAN))
+		return false;
+
+	return true;
+}
+
 #endif /* LINUX_IEEE80211_NAN_H */
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index d35c826c4b1a..b7c6c856b3c9 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -3338,6 +3338,10 @@ cfg80211_inform_bss_frame_data(struct wiphy *wiphy,
 	if (WARN_ON(!wiphy))
 		return NULL;
 
+	/* NAN beacons are not a BSS, don't add to the BSS table */
+	if (ieee80211_is_nan_beacon(mgmt, len))
+		return NULL;
+
 	BUILD_BUG_ON(offsetof(struct ieee80211_mgmt, u.probe_resp.variable) !=
 		     offsetof(struct ieee80211_mgmt, u.beacon.variable));
 
-- 
2.55.0