DPP2: Reconfig Announcement transmission

Extend DPP chirping mechanism to allow Reconfig Announcement frames to
be transmitted instead of the Presence Announcement frames. Add a new
wpa_supplicant control interface command "DPP_RECONFIG <network id>" to
initiate reconfiguration for a specific network profile.

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

hostapd/Android.mk

@@ -539,6 +539,7 @@ L_CFLAGS += -DCONFIG_DPP
 OBJS += src/common/dpp.c
 OBJS += src/common/dpp_crypto.c
 OBJS += src/common/dpp_pkex.c
+OBJS += src/common/dpp_reconfig.c
 OBJS += src/ap/dpp_hostapd.c
 OBJS += src/ap/gas_query_ap.c
 NEED_AES_SIV=y

hostapd/Makefile

@@ -570,6 +570,7 @@ CFLAGS += -DCONFIG_DPP
 OBJS += ../src/common/dpp.o
 OBJS += ../src/common/dpp_crypto.o
 OBJS += ../src/common/dpp_pkex.o
+OBJS += ../src/common/dpp_reconfig.o
 OBJS += ../src/ap/dpp_hostapd.o
 OBJS += ../src/ap/gas_query_ap.o
 NEED_AES_SIV=y

src/common/dpp.h

@@ -626,5 +626,10 @@ struct dpp_global * dpp_global_init(struct dpp_global_config *config);
 void dpp_global_clear(struct dpp_global *dpp);
 void dpp_global_deinit(struct dpp_global *dpp);
 
+/* dpp_reconfig.c */
+
+struct wpabuf * dpp_build_reconfig_announcement(const u8 *csign_key,
+						size_t csign_key_len);
+
 #endif /* CONFIG_DPP */
 #endif /* DPP_H */

src/common/dpp_reconfig.c

@@ -0,0 +1,76 @@
+/*
+ * DPP reconfiguration
+ * Copyright (c) 2020, The Linux Foundation
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "utils/includes.h"
+
+#include "utils/common.h"
+#include "crypto/crypto.h"
+#include "dpp.h"
+#include "dpp_i.h"
+
+
+#ifdef CONFIG_DPP2
+
+static void dpp_build_attr_csign_key_hash(struct wpabuf *msg, const u8 *hash)
+{
+	if (hash) {
+		wpa_printf(MSG_DEBUG, "DPP: Configurator C-sign key Hash");
+		wpabuf_put_le16(msg, DPP_ATTR_C_SIGN_KEY_HASH);
+		wpabuf_put_le16(msg, SHA256_MAC_LEN);
+		wpabuf_put_data(msg, hash, SHA256_MAC_LEN);
+	}
+}
+
+
+struct wpabuf * dpp_build_reconfig_announcement(const u8 *csign_key,
+						size_t csign_key_len)
+{
+	struct wpabuf *msg;
+	EVP_PKEY *csign = NULL;
+	const unsigned char *p;
+	struct wpabuf *uncomp;
+	u8 hash[SHA256_MAC_LEN];
+	const u8 *addr[1];
+	size_t len[1];
+	int res;
+
+	wpa_printf(MSG_DEBUG, "DPP: Build Reconfig Announcement frame");
+
+	p = csign_key;
+	csign = d2i_PUBKEY(NULL, &p, csign_key_len);
+	if (!csign) {
+		wpa_printf(MSG_ERROR,
+			   "DPP: Failed to parse local C-sign-key information");
+		return NULL;
+	}
+
+	uncomp = dpp_get_pubkey_point(csign, 1);
+	EVP_PKEY_free(csign);
+	if (!uncomp)
+		return NULL;
+	addr[0] = wpabuf_head(uncomp);
+	len[0] = wpabuf_len(uncomp);
+	wpa_hexdump(MSG_DEBUG, "DPP: Uncompressed C-sign key", addr[0], len[0]);
+	res = sha256_vector(1, addr, len, hash);
+	wpabuf_free(uncomp);
+	if (res < 0)
+		return NULL;
+	wpa_hexdump(MSG_DEBUG, "DPP: kid = SHA256(uncompressed C-sign key)",
+		    hash, SHA256_MAC_LEN);
+
+	msg = dpp_alloc_msg(DPP_PA_RECONFIG_ANNOUNCEMENT, 4 + SHA256_MAC_LEN);
+	if (!msg)
+		return NULL;
+
+	/* Configurator C-sign key Hash */
+	dpp_build_attr_csign_key_hash(msg, hash);
+	wpa_hexdump_buf(MSG_DEBUG,
+			"DPP: Reconfig Announcement frame attributes", msg);
+	return msg;
+}
+#endif /* CONFIG_DPP2 */

tests/fuzzing/dpp-uri/Makefile

@@ -23,6 +23,7 @@ OBJS += $(SRC)/tls/asn1.o
 OBJS += $(SRC)/common/dpp.o
 OBJS += $(SRC)/common/dpp_crypto.o
 OBJS += $(SRC)/common/dpp_pkex.o
+OBJS += $(SRC)/common/dpp_reconfig.o
 
 dpp-uri: dpp-uri.o $(OBJS) $(LIBS)
 	$(LDO) $(LDFLAGS) -o $@ $^ -lcrypto

wpa_supplicant/Android.mk

@@ -249,6 +249,7 @@ L_CFLAGS += -DCONFIG_DPP
 OBJS += src/common/dpp.c
 OBJS += src/common/dpp_crypto.c
 OBJS += src/common/dpp_pkex.c
+OBJS += src/common/dpp_reconfig.c
 OBJS += dpp_supplicant.c
 NEED_AES_SIV=y
 NEED_HMAC_SHA256_KDF=y

wpa_supplicant/Makefile

@@ -281,6 +281,7 @@ CFLAGS += -DCONFIG_DPP
 OBJS += ../src/common/dpp.o
 OBJS += ../src/common/dpp_crypto.o
 OBJS += ../src/common/dpp_pkex.o
+OBJS += ../src/common/dpp_reconfig.o
 OBJS += dpp_supplicant.o
 NEED_AES_SIV=y
 NEED_HMAC_SHA256_KDF=y

wpa_supplicant/ctrl_iface.c

@@ -11013,6 +11013,12 @@ char * wpa_supplicant_ctrl_iface_process(struct wpa_supplicant *wpa_s,
 			reply_len = -1;
 	} else if (os_strcmp(buf, "DPP_STOP_CHIRP") == 0) {
 		wpas_dpp_chirp_stop(wpa_s);
+	} else if (os_strncmp(buf, "DPP_RECONFIG ", 13) == 0) {
+		struct wpa_ssid *ssid;
+
+		ssid = wpa_config_get_network(wpa_s->conf, atoi(buf + 13));
+		if (!ssid || wpas_dpp_reconfig(wpa_s, ssid) < 0)
+			reply_len = -1;
 #endif /* CONFIG_DPP2 */
 #endif /* CONFIG_DPP */
 	} else {

wpa_supplicant/dpp_supplicant.c

@@ -2878,15 +2878,24 @@ static void wpas_dpp_chirp_tx_status(struct wpa_supplicant *wpa_s,
 
 static void wpas_dpp_chirp_start(struct wpa_supplicant *wpa_s)
 {
+	struct wpabuf *msg;
+	int type;
+
+	msg = wpa_s->dpp_presence_announcement;
+	type = DPP_PA_PRESENCE_ANNOUNCEMENT;
+	if (!msg) {
+		msg = wpa_s->dpp_reconfig_announcement;
+		if (!msg)
+			return;
+		type = DPP_PA_RECONFIG_ANNOUNCEMENT;
+	}
 	wpa_printf(MSG_DEBUG, "DPP: Chirp on %d MHz", wpa_s->dpp_chirp_freq);
 	wpa_msg(wpa_s, MSG_INFO, DPP_EVENT_TX "dst=" MACSTR " freq=%u type=%d",
-		MAC2STR(broadcast), wpa_s->dpp_chirp_freq,
+		MAC2STR(broadcast), wpa_s->dpp_chirp_freq, type);
-		DPP_PA_PRESENCE_ANNOUNCEMENT);
 	if (offchannel_send_action(
 		    wpa_s, wpa_s->dpp_chirp_freq, broadcast,
 		    wpa_s->own_addr, broadcast,
-		    wpabuf_head(wpa_s->dpp_presence_announcement),
+		    wpabuf_head(msg), wpabuf_len(msg),
-		    wpabuf_len(wpa_s->dpp_presence_announcement),
 		    2000, wpas_dpp_chirp_tx_status, 0) < 0)
 		wpas_dpp_chirp_stop(wpa_s);
 }
@@ -2901,7 +2910,7 @@ static void wpas_dpp_chirp_scan_res_handler(struct wpa_supplicant *wpa_s,
 	int c;
 	struct wpa_bss *bss;
 
-	if (!bi)
+	if (!bi && !wpa_s->dpp_reconfig_announcement)
 		return;
 
 	wpa_s->dpp_chirp_scan_done = 1;
@@ -2910,8 +2919,11 @@ static void wpas_dpp_chirp_scan_res_handler(struct wpa_supplicant *wpa_s,
 	wpa_s->dpp_chirp_freqs = NULL;
 
 	/* Channels from own bootstrapping info */
+	if (bi) {
 		for (i = 0; i < bi->num_freq; i++)
-		int_array_add_unique(&wpa_s->dpp_chirp_freqs, bi->freq[i]);
+			int_array_add_unique(&wpa_s->dpp_chirp_freqs,
+					     bi->freq[i]);
+	}
 
 	/* Preferred chirping channels */
 	int_array_add_unique(&wpa_s->dpp_chirp_freqs, 2437);
@@ -3085,13 +3097,16 @@ int wpas_dpp_chirp(struct wpa_supplicant *wpa_s, const char *cmd)
 
 void wpas_dpp_chirp_stop(struct wpa_supplicant *wpa_s)
 {
-	if (wpa_s->dpp_presence_announcement) {
+	if (wpa_s->dpp_presence_announcement ||
+	    wpa_s->dpp_reconfig_announcement) {
 		offchannel_send_action_done(wpa_s);
 		wpa_msg(wpa_s, MSG_INFO, DPP_EVENT_CHIRP_STOPPED);
 	}
 	wpa_s->dpp_chirp_bi = NULL;
 	wpabuf_free(wpa_s->dpp_presence_announcement);
 	wpa_s->dpp_presence_announcement = NULL;
+	wpabuf_free(wpa_s->dpp_reconfig_announcement);
+	wpa_s->dpp_reconfig_announcement = NULL;
 	if (wpa_s->dpp_chirp_listen)
 		wpas_dpp_listen_stop(wpa_s);
 	wpa_s->dpp_chirp_listen = 0;
@@ -3106,4 +3121,29 @@ void wpas_dpp_chirp_stop(struct wpa_supplicant *wpa_s)
 	}
 }
 
+
+int wpas_dpp_reconfig(struct wpa_supplicant *wpa_s, struct wpa_ssid *ssid)
+{
+	if (!ssid->dpp_connector || !ssid->dpp_netaccesskey ||
+	    !ssid->dpp_csign)
+		return -1;
+
+	wpas_dpp_chirp_stop(wpa_s);
+	wpa_s->dpp_allowed_roles = DPP_CAPAB_ENROLLEE;
+	wpa_s->dpp_qr_mutual = 0;
+	wpa_s->dpp_reconfig_announcement =
+		dpp_build_reconfig_announcement(ssid->dpp_csign,
+						ssid->dpp_csign_len);
+	if (!wpa_s->dpp_reconfig_announcement)
+		return -1;
+	wpa_s->dpp_reconfig_ssid = ssid;
+	wpa_s->dpp_reconfig_ssid_id = ssid->id;
+	wpa_s->dpp_chirp_iter = 1;
+	wpa_s->dpp_chirp_round = 0;
+	wpa_s->dpp_chirp_scan_done = 0;
+	wpa_s->dpp_chirp_listen = 0;
+
+	return eloop_register_timeout(0, 0, wpas_dpp_chirp_next, wpa_s, NULL);
+}
+
 #endif /* CONFIG_DPP2 */

wpa_supplicant/dpp_supplicant.h

@@ -39,5 +39,6 @@ void wpas_dpp_send_conn_status_result(struct wpa_supplicant *wpa_s,
 				      enum dpp_status_error result);
 int wpas_dpp_chirp(struct wpa_supplicant *wpa_s, const char *cmd);
 void wpas_dpp_chirp_stop(struct wpa_supplicant *wpa_s);
+int wpas_dpp_reconfig(struct wpa_supplicant *wpa_s, struct wpa_ssid *ssid);
 
 #endif /* DPP_SUPPLICANT_H */

wpa_supplicant/wpa_supplicant_i.h

@@ -1277,6 +1277,7 @@ struct wpa_supplicant {
 #ifdef CONFIG_DPP2
 	struct dpp_pfs *dpp_pfs;
 	int dpp_pfs_fallback;
+	struct wpabuf *dpp_reconfig_announcement;
 	struct wpabuf *dpp_presence_announcement;
 	struct dpp_bootstrap_info *dpp_chirp_bi;
 	int dpp_chirp_freq;
@@ -1285,6 +1286,8 @@ struct wpa_supplicant {
 	int dpp_chirp_round;
 	int dpp_chirp_scan_done;
 	int dpp_chirp_listen;
+	struct wpa_ssid *dpp_reconfig_ssid;
+	int dpp_reconfig_ssid_id;
 #endif /* CONFIG_DPP2 */
 #ifdef CONFIG_TESTING_OPTIONS
 	char *dpp_config_obj_override;