Avoid unnecessary key clearing operations

Track set_key operations per-key index and clear keys on disconnection
only if the key was set (or may have been set which is the case for the
first operation after wpa_supplicant start).

Signed-hostap: Jouni Malinen <j@w1.fi>

wpa_supplicant/driver_i.h

@@ -117,11 +117,16 @@ static inline int wpa_drv_get_ssid(struct wpa_supplicant *wpa_s, u8 *ssid)
 static inline int wpa_drv_set_key(struct wpa_supplicant *wpa_s,
 				  enum wpa_alg alg, const u8 *addr,
 				  int key_idx, int set_tx,
-				   const u8 *seq, size_t seq_len,
-				   const u8 *key, size_t key_len)
-{
+				  const u8 *seq, size_t seq_len,
+				  const u8 *key, size_t key_len)
+{
+	if (alg != WPA_ALG_NONE) {
+		if (key_idx >= 0 && key_idx <= 6)
+			wpa_s->keys_cleared &= ~BIT(key_idx);
+		else
+			wpa_s->keys_cleared = 0;
+	}
 	if (wpa_s->driver->set_key) {
-		wpa_s->keys_cleared = 0;
 		return wpa_s->driver->set_key(wpa_s->ifname, wpa_s->drv_priv,
 					      alg, addr, key_idx, set_tx,
 					      seq, seq_len, key, key_len);

wpa_supplicant/events.c

@@ -2163,7 +2163,6 @@ static void wpa_supplicant_event_disassoc_finish(struct wpa_supplicant *wpa_s,
 	wpas_notify_disconnect_reason(wpa_s);
 	if (wpa_supplicant_dynamic_keys(wpa_s)) {
 		wpa_dbg(wpa_s, MSG_DEBUG, "Disconnect event - remove keys");
-		wpa_s->keys_cleared = 0;
 		wpa_clear_keys(wpa_s, wpa_s->bssid);
 	}
 	last_ssid = wpa_s->current_ssid;

wpa_supplicant/wpa_supplicant.c

@@ -495,29 +495,23 @@ static void wpa_supplicant_cleanup(struct wpa_supplicant *wpa_s)
  */
 void wpa_clear_keys(struct wpa_supplicant *wpa_s, const u8 *addr)
 {
-	if (wpa_s->keys_cleared) {
-		/* Some drivers (e.g., ndiswrapper & NDIS drivers) seem to have
-		 * timing issues with keys being cleared just before new keys
-		 * are set or just after association or something similar. This
-		 * shows up in group key handshake failing often because of the
-		 * client not receiving the first encrypted packets correctly.
-		 * Skipping some of the extra key clearing steps seems to help
-		 * in completing group key handshake more reliably. */
-		wpa_dbg(wpa_s, MSG_DEBUG, "No keys have been configured - "
-			"skip key clearing");
-		return;
-	}
+	int i, max;
 
-	/* MLME-DELETEKEYS.request */
-	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, NULL, 0, 0, NULL, 0, NULL, 0);
-	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, NULL, 1, 0, NULL, 0, NULL, 0);
-	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, NULL, 2, 0, NULL, 0, NULL, 0);
-	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, NULL, 3, 0, NULL, 0, NULL, 0);
 #ifdef CONFIG_IEEE80211W
-	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, NULL, 4, 0, NULL, 0, NULL, 0);
-	wpa_drv_set_key(wpa_s, WPA_ALG_NONE, NULL, 5, 0, NULL, 0, NULL, 0);
+	max = 6;
+#else /* CONFIG_IEEE80211W */
+	max = 4;
 #endif /* CONFIG_IEEE80211W */
-	if (addr) {
+
+	/* MLME-DELETEKEYS.request */
+	for (i = 0; i < max; i++) {
+		if (wpa_s->keys_cleared & BIT(i))
+			continue;
+		wpa_drv_set_key(wpa_s, WPA_ALG_NONE, NULL, i, 0, NULL, 0,
+				NULL, 0);
+	}
+	if (!(wpa_s->keys_cleared & BIT(0)) && addr &&
+	    !is_zero_ether_addr(addr)) {
 		wpa_drv_set_key(wpa_s, WPA_ALG_NONE, addr, 0, 0, NULL, 0, NULL,
 				0);
 		/* MLME-SETPROTECTION.request(None) */
@@ -526,7 +520,7 @@ void wpa_clear_keys(struct wpa_supplicant *wpa_s, const u8 *addr)
 			MLME_SETPROTECTION_PROTECT_TYPE_NONE,
 			MLME_SETPROTECTION_KEY_TYPE_PAIRWISE);
 	}
-	wpa_s->keys_cleared = 1;
+	wpa_s->keys_cleared = (u32) -1;
 }
 
 

wpa_supplicant/wpa_supplicant_i.h

@@ -432,7 +432,8 @@ struct wpa_supplicant {
 
 	unsigned char last_eapol_src[ETH_ALEN];
 
-	int keys_cleared;
+	unsigned int keys_cleared; /* bitfield of key indexes that the driver is
+				    * known not to be configured with a key */
 
 	struct wpa_blacklist *blacklist;