cfg80211: don't drop p2p probe responses

Commit 0a35d36d ("cfg80211: Use capability info to detect mesh beacons")
assumed that probe response with both ESS and IBSS bits cleared
means that the frame was sent by a mesh sta.

However, these capabilities are also being used in the p2p_find phase,
and the mesh-validation broke it.

Rename the WLAN_CAPABILITY_IS_MBSS macro, and verify that mesh ies
exist before assuming this frame was sent by a mesh sta.
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

include/linux/ieee80211.h

@@ -1003,8 +1003,12 @@ struct ieee80211_ht_info {
 #define WLAN_CAPABILITY_ESS		(1<<0)
 #define WLAN_CAPABILITY_IBSS		(1<<1)
 
-/* A mesh STA sets the ESS and IBSS capability bits to zero */
-#define WLAN_CAPABILITY_IS_MBSS(cap)	\
+/*
+ * A mesh STA sets the ESS and IBSS capability bits to zero.
+ * however, this holds true for p2p probe responses (in the p2p_find
+ * phase) as well.
+ */
+#define WLAN_CAPABILITY_IS_STA_BSS(cap)	\
 	(!((cap) & (WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS)))
 
 #define WLAN_CAPABILITY_CF_POLLABLE	(1<<2)

net/wireless/scan.c

@@ -267,13 +267,35 @@ static bool is_bss(struct cfg80211_bss *a,
 	return memcmp(ssidie + 2, ssid, ssid_len) == 0;
 }
 
+static bool is_mesh_bss(struct cfg80211_bss *a)
+{
+	const u8 *ie;
+
+	if (!WLAN_CAPABILITY_IS_STA_BSS(a->capability))
+		return false;
+
+	ie = cfg80211_find_ie(WLAN_EID_MESH_ID,
+			      a->information_elements,
+			      a->len_information_elements);
+	if (!ie)
+		return false;
+
+	ie = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
+			      a->information_elements,
+			      a->len_information_elements);
+	if (!ie)
+		return false;
+
+	return true;
+}
+
 static bool is_mesh(struct cfg80211_bss *a,
 		    const u8 *meshid, size_t meshidlen,
 		    const u8 *meshcfg)
 {
 	const u8 *ie;
 
-	if (!WLAN_CAPABILITY_IS_MBSS(a->capability))
+	if (!WLAN_CAPABILITY_IS_STA_BSS(a->capability))
 		return false;
 
 	ie = cfg80211_find_ie(WLAN_EID_MESH_ID,
@@ -311,7 +333,7 @@ static int cmp_bss(struct cfg80211_bss *a,
 	if (a->channel != b->channel)
 		return b->channel->center_freq - a->channel->center_freq;
 
-	if (WLAN_CAPABILITY_IS_MBSS(a->capability | b->capability)) {
+	if (is_mesh_bss(a) && is_mesh_bss(b)) {
 		r = cmp_ies(WLAN_EID_MESH_ID,
 			    a->information_elements,
 			    a->len_information_elements,
@@ -457,7 +479,6 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
 		    struct cfg80211_internal_bss *res)
 {
 	struct cfg80211_internal_bss *found = NULL;
-	const u8 *meshid, *meshcfg;
 
 	/*
 	 * The reference to "res" is donated to this function.
@@ -470,22 +491,6 @@ cfg80211_bss_update(struct cfg80211_registered_device *dev,
 
 	res->ts = jiffies;
 
-	if (WLAN_CAPABILITY_IS_MBSS(res->pub.capability)) {
-		/* must be mesh, verify */
-		meshid = cfg80211_find_ie(WLAN_EID_MESH_ID,
-					  res->pub.information_elements,
-					  res->pub.len_information_elements);
-		meshcfg = cfg80211_find_ie(WLAN_EID_MESH_CONFIG,
-					   res->pub.information_elements,
-					   res->pub.len_information_elements);
-		if (!meshid || !meshcfg ||
-		    meshcfg[1] != sizeof(struct ieee80211_meshconf_ie)) {
-			/* bogus mesh */
-			kref_put(&res->ref, bss_release);
-			return NULL;
-		}
-	}
-
 	spin_lock_bh(&dev->bss_lock);
 
 	found = rb_find_bss(dev, res);