OSEN: Do not send the actual BIGTK to OSEN STAs

OSEN STAs are not authenticated, so do not send the actual BIGTK for
them so that they cannot generate forged protected Beacon frames. This
means that OSEN STAs cannot enable beacon protection.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>

src/ap/wpa_auth.c

@@ -3212,6 +3212,14 @@ static u8 * ieee80211w_kde_add(struct wpa_state_machine *sm, u8 *pos)
 	else
 		os_memcpy(bigtk.pn, rsc, sizeof(bigtk.pn));
 	os_memcpy(bigtk.bigtk, gsm->BIGTK[gsm->GN_bigtk - 6], len);
+	if (sm->wpa_key_mgmt == WPA_KEY_MGMT_OSEN) {
+		/*
+		 * Provide unique random BIGTK to each OSEN STA to prevent use
+		 * of BIGTK in the BSS.
+		 */
+		if (random_get_bytes(bigtk.bigtk, len) < 0)
+			return pos;
+	}
 	pos = wpa_add_kde(pos, RSN_KEY_DATA_BIGTK,
 			  (const u8 *) &bigtk, WPA_BIGTK_KDE_PREFIX_LEN + len,
 			  NULL, 0);
@@ -4174,6 +4182,14 @@ int wpa_wnmsleep_bigtk_subelem(struct wpa_state_machine *sm, u8 *pos)
 	pos += 6;
 
 	os_memcpy(pos, gsm->BIGTK[gsm->GN_bigtk - 6], len);
+	if (sm->wpa_key_mgmt == WPA_KEY_MGMT_OSEN) {
+		/*
+		 * Provide unique random BIGTK to each STA to prevent use
+		 * of BIGTK in the BSS.
+		 */
+		if (random_get_bytes(pos, len) < 0)
+			return 0;
+	}
 	pos += len;
 
 	wpa_printf(MSG_DEBUG, "WNM: BIGTK Key ID %u in WNM-Sleep Mode exit",

src/ap/wpa_auth_ft.c

@@ -2315,9 +2315,10 @@ static u8 * wpa_ft_bigtk_subelem(struct wpa_state_machine *sm, size_t *len)
 	u8 *subelem, *pos;
 	struct wpa_group *gsm = sm->group;
 	size_t subelem_len;
-	const u8 *kek;
+	const u8 *kek, *bigtk;
 	size_t kek_len;
 	size_t bigtk_len;
+	u8 dummy_bigtk[WPA_IGTK_MAX_LEN];
 
 	if (wpa_key_mgmt_fils(sm->wpa_key_mgmt)) {
 		kek = sm->PTK.kek2;
@@ -2344,8 +2345,19 @@ static u8 * wpa_ft_bigtk_subelem(struct wpa_state_machine *sm, size_t *len)
 	wpa_auth_get_seqnum(sm->wpa_auth, NULL, gsm->GN_bigtk, pos);
 	pos += 6;
 	*pos++ = bigtk_len;
-	if (aes_wrap(kek, kek_len, bigtk_len / 8,
-		     gsm->IGTK[gsm->GN_bigtk - 6], pos)) {
+	bigtk = gsm->IGTK[gsm->GN_bigtk - 6];
+	if (sm->wpa_key_mgmt == WPA_KEY_MGMT_OSEN) {
+		/*
+		 * Provide unique random BIGTK to each OSEN STA to prevent use
+		 * of BIGTK in the BSS.
+		 */
+		if (random_get_bytes(dummy_bigtk, bigtk_len / 8) < 0) {
+			os_free(subelem);
+			return NULL;
+		}
+		bigtk = dummy_bigtk;
+	}
+	if (aes_wrap(kek, kek_len, bigtk_len / 8, bigtk, pos)) {
 		wpa_printf(MSG_DEBUG,
 			   "FT: BIGTK subelem encryption failed: kek_len=%d",
 			   (int) kek_len);