Configure received BIGTK on station/supplicant side

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

src/rsn_supp/wpa.c

@@ -1140,14 +1140,66 @@ static int wpa_supplicant_install_igtk(struct wpa_sm *sm,
 }
 
 
+static int wpa_supplicant_install_bigtk(struct wpa_sm *sm,
+				       const struct wpa_bigtk_kde *bigtk,
+				       int wnm_sleep)
+{
+	size_t len = wpa_cipher_key_len(sm->mgmt_group_cipher);
+	u16 keyidx = WPA_GET_LE16(bigtk->keyid);
+
+	/* Detect possible key reinstallation */
+	if ((sm->bigtk.bigtk_len == len &&
+	     os_memcmp(sm->bigtk.bigtk, bigtk->bigtk,
+		       sm->bigtk.bigtk_len) == 0) ||
+	    (sm->bigtk_wnm_sleep.bigtk_len == len &&
+	     os_memcmp(sm->bigtk_wnm_sleep.bigtk, bigtk->bigtk,
+		       sm->bigtk_wnm_sleep.bigtk_len) == 0)) {
+		wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
+			"WPA: Not reinstalling already in-use BIGTK to the driver (keyidx=%d)",
+			keyidx);
+		return  0;
+	}
+
+	wpa_dbg(sm->ctx->msg_ctx, MSG_DEBUG,
+		"WPA: BIGTK keyid %d pn " COMPACT_MACSTR,
+		keyidx, MAC2STR(bigtk->pn));
+	wpa_hexdump_key(MSG_DEBUG, "WPA: BIGTK", bigtk->bigtk, len);
+	if (keyidx < 6 || keyidx > 7) {
+		wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
+			"WPA: Invalid BIGTK KeyID %d", keyidx);
+		return -1;
+	}
+	if (wpa_sm_set_key(sm, wpa_cipher_to_alg(sm->mgmt_group_cipher),
+			   broadcast_ether_addr,
+			   keyidx, 0, bigtk->pn, sizeof(bigtk->pn),
+			   bigtk->bigtk, len, KEY_FLAG_GROUP_RX) < 0) {
+		wpa_msg(sm->ctx->msg_ctx, MSG_WARNING,
+			"WPA: Failed to configure BIGTK to the driver");
+		return -1;
+	}
+
+	if (wnm_sleep) {
+		sm->bigtk_wnm_sleep.bigtk_len = len;
+		os_memcpy(sm->bigtk_wnm_sleep.bigtk, bigtk->bigtk,
+			  sm->bigtk_wnm_sleep.bigtk_len);
+	} else {
+		sm->bigtk.bigtk_len = len;
+		os_memcpy(sm->bigtk.bigtk, bigtk->bigtk, sm->bigtk.bigtk_len);
+	}
+
+	return 0;
+}
+
+
 static int ieee80211w_set_keys(struct wpa_sm *sm,
 			       struct wpa_eapol_ie_parse *ie)
 {
+	size_t len;
+
 	if (!wpa_cipher_valid_mgmt_group(sm->mgmt_group_cipher))
 		return 0;
 
 	if (ie->igtk) {
-		size_t len;
 		const struct wpa_igtk_kde *igtk;
 
 		len = wpa_cipher_key_len(sm->mgmt_group_cipher);
@@ -1159,6 +1211,18 @@ static int ieee80211w_set_keys(struct wpa_sm *sm,
 			return -1;
 	}
 
+	if (ie->bigtk && sm->beacon_prot) {
+		const struct wpa_bigtk_kde *bigtk;
+
+		len = wpa_cipher_key_len(sm->mgmt_group_cipher);
+		if (ie->bigtk_len != WPA_BIGTK_KDE_PREFIX_LEN + len)
+			return -1;
+
+		bigtk = (const struct wpa_bigtk_kde *) ie->bigtk;
+		if (wpa_supplicant_install_bigtk(sm, bigtk, 0) < 0)
+			return -1;
+	}
+
 	return 0;
 }
 
@@ -3595,6 +3659,13 @@ int wpa_wnmsleep_install_key(struct wpa_sm *sm, u8 subelem_id, u8 *buf)
 		igtk = (const struct wpa_igtk_kde *) (buf + 2);
 		if (wpa_supplicant_install_igtk(sm, igtk, 1) < 0)
 			return -1;
+	} else if (subelem_id == WNM_SLEEP_SUBELEM_BIGTK) {
+		const struct wpa_bigtk_kde *bigtk;
+
+		bigtk = (const struct wpa_bigtk_kde *) (buf + 2);
+		if (sm->beacon_prot &&
+		    wpa_supplicant_install_bigtk(sm, bigtk, 1) < 0)
+			return -1;
 	} else {
 		wpa_printf(MSG_DEBUG, "Unknown element id");
 		return -1;

src/rsn_supp/wpa_ft.c

@@ -855,6 +855,74 @@ static int wpa_ft_process_igtk_subelem(struct wpa_sm *sm, const u8 *igtk_elem,
 }
 
 
+static int wpa_ft_process_bigtk_subelem(struct wpa_sm *sm, const u8 *bigtk_elem,
+				       size_t bigtk_elem_len)
+{
+	u8 bigtk[WPA_BIGTK_MAX_LEN];
+	size_t bigtk_len;
+	u16 keyidx;
+	const u8 *kek;
+	size_t kek_len;
+
+	if (!sm->beacon_prot || !bigtk_elem ||
+	    (sm->mgmt_group_cipher != WPA_CIPHER_AES_128_CMAC &&
+	     sm->mgmt_group_cipher != WPA_CIPHER_BIP_GMAC_128 &&
+	     sm->mgmt_group_cipher != WPA_CIPHER_BIP_GMAC_256 &&
+	     sm->mgmt_group_cipher != WPA_CIPHER_BIP_CMAC_256))
+		return 0;
+
+	if (wpa_key_mgmt_fils(sm->key_mgmt)) {
+		kek = sm->ptk.kek2;
+		kek_len = sm->ptk.kek2_len;
+	} else {
+		kek = sm->ptk.kek;
+		kek_len = sm->ptk.kek_len;
+	}
+
+	wpa_hexdump_key(MSG_DEBUG, "FT: Received BIGTK in Reassoc Resp",
+			bigtk_elem, bigtk_elem_len);
+
+	bigtk_len = wpa_cipher_key_len(sm->mgmt_group_cipher);
+	if (bigtk_elem_len != 2 + 6 + 1 + bigtk_len + 8) {
+		wpa_printf(MSG_DEBUG,
+			   "FT: Invalid BIGTK sub-elem length %lu",
+			   (unsigned long) bigtk_elem_len);
+		return -1;
+	}
+	if (bigtk_elem[8] != bigtk_len) {
+		wpa_printf(MSG_DEBUG,
+			   "FT: Invalid BIGTK sub-elem Key Length %d",
+			   bigtk_elem[8]);
+		return -1;
+	}
+
+	if (aes_unwrap(kek, kek_len, bigtk_len / 8, bigtk_elem + 9, bigtk)) {
+		wpa_printf(MSG_WARNING,
+			   "FT: AES unwrap failed - could not decrypt BIGTK");
+		return -1;
+	}
+
+	/* KeyID[2] | IPN[6] | Key Length[1] | Key[16+8] */
+
+	keyidx = WPA_GET_LE16(bigtk_elem);
+
+	wpa_hexdump_key(MSG_DEBUG, "FT: BIGTK from Reassoc Resp", bigtk,
+			bigtk_len);
+	if (wpa_sm_set_key(sm, wpa_cipher_to_alg(sm->mgmt_group_cipher),
+			   broadcast_ether_addr, keyidx, 0,
+			   bigtk_elem + 2, 6, bigtk, bigtk_len,
+			   KEY_FLAG_GROUP_RX) < 0) {
+		wpa_printf(MSG_WARNING,
+			   "WPA: Failed to set BIGTK to the driver");
+		forced_memzero(bigtk, sizeof(bigtk));
+		return -1;
+	}
+	forced_memzero(bigtk, sizeof(bigtk));
+
+	return 0;
+}
+
+
 int wpa_ft_validate_reassoc_resp(struct wpa_sm *sm, const u8 *ies,
 				 size_t ies_len, const u8 *src_addr)
 {
@@ -1036,10 +1104,9 @@ int wpa_ft_validate_reassoc_resp(struct wpa_sm *sm, const u8 *ies,
 
 	sm->ft_reassoc_completed = 1;
 
-	if (wpa_ft_process_gtk_subelem(sm, parse.gtk, parse.gtk_len) < 0)
-		return -1;
-
-	if (wpa_ft_process_igtk_subelem(sm, parse.igtk, parse.igtk_len) < 0)
+	if (wpa_ft_process_gtk_subelem(sm, parse.gtk, parse.gtk_len) < 0 ||
+	    wpa_ft_process_igtk_subelem(sm, parse.igtk, parse.igtk_len) < 0 ||
+	    wpa_ft_process_bigtk_subelem(sm, parse.bigtk, parse.bigtk_len) < 0)
 		return -1;
 
 	if (sm->set_ptk_after_assoc) {

src/rsn_supp/wpa_i.h

@@ -33,6 +33,8 @@ struct wpa_sm {
 	struct wpa_gtk gtk_wnm_sleep;
 	struct wpa_igtk igtk;
 	struct wpa_igtk igtk_wnm_sleep;
+	struct wpa_bigtk bigtk;
+	struct wpa_bigtk bigtk_wnm_sleep;
 
 	struct eapol_sm *eapol; /* EAPOL state machine from upper level code */
 

wpa_supplicant/wnm_sta.c

@@ -280,6 +280,15 @@ static void wnm_sleep_mode_exit_success(struct wpa_supplicant *wpa_s,
 			wpa_wnmsleep_install_key(wpa_s->wpa,
 						 WNM_SLEEP_SUBELEM_IGTK, ptr);
 			ptr += 10 + WPA_IGTK_LEN;
+		} else if (*ptr == WNM_SLEEP_SUBELEM_BIGTK) {
+			if (ptr[1] < 2 + 6 + WPA_BIGTK_LEN) {
+				wpa_printf(MSG_DEBUG,
+					   "WNM: Too short BIGTK subelem");
+				break;
+			}
+			wpa_wnmsleep_install_key(wpa_s->wpa,
+						 WNM_SLEEP_SUBELEM_BIGTK, ptr);
+			ptr += 10 + WPA_BIGTK_LEN;
 		} else
 			break; /* skip the loop */
 	}