P2P: Allow per-device PSK to be assigned

"wpa_cli p2p_set per_sta_psk <0/1>" can now be used to disable/enable
use of per-device PSKs in P2P groups. This is disabled by default.
When enabled, a default passphrase is still generated by the GO for
legacy stations, but all P2P and non-P2P devices using WPS will get
a unique PSK.

This gives more protection for the P2P group by preventing clients from
being able to derive the unicast keys used by other clients. This is
also a step towards allowing specific clients to be removed from a group
reliably without having to tear down the full group to do so.

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

src/ap/ap_config.h

@@ -358,6 +358,7 @@ struct hostapd_bss_config {
 	u8 *extra_cred;
 	size_t extra_cred_len;
 	int wps_cred_processing;
+	int force_per_enrollee_psk;
 	u8 *ap_settings;
 	size_t ap_settings_len;
 	char *upnp_iface;

src/ap/wps_hostapd.c

@@ -1145,6 +1145,7 @@ int hostapd_init_wps(struct hostapd_data *hapd,
 		cfg.dualband = 1;
 	if (cfg.dualband)
 		wpa_printf(MSG_DEBUG, "WPS: Dualband AP");
+	cfg.force_per_enrollee_psk = conf->force_per_enrollee_psk;
 
 	wps->registrar = wps_registrar_init(wps, &cfg);
 	if (wps->registrar == NULL) {

src/wps/wps.h

@@ -382,6 +382,14 @@ struct wps_registrar_config {
 	 * dualband - Whether this is a concurrent dualband AP
 	 */
 	int dualband;
+
+	/**
+	 * force_per_enrollee_psk - Force per-Enrollee random PSK
+	 *
+	 * This forces per-Enrollee random PSK to be generated even if a default
+	 * PSK is set for a network.
+	 */
+	int force_per_enrollee_psk;
 };
 
 

src/wps/wps_registrar.c

@@ -1,6 +1,6 @@
 /*
  * Wi-Fi Protected Setup - Registrar
- * Copyright (c) 2008-2012, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2008-2013, Jouni Malinen <j@w1.fi>
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -171,6 +171,7 @@ struct wps_registrar {
 	int sel_reg_config_methods_override;
 	int static_wep_only;
 	int dualband;
+	int force_per_enrollee_psk;
 
 	struct wps_registrar_device *devices;
 
@@ -667,6 +668,7 @@ wps_registrar_init(struct wps_context *wps,
 	reg->sel_reg_config_methods_override = -1;
 	reg->static_wep_only = cfg->static_wep_only;
 	reg->dualband = cfg->dualband;
+	reg->force_per_enrollee_psk = cfg->force_per_enrollee_psk;
 
 	if (wps_set_ie(reg)) {
 		wps_registrar_deinit(reg);
@@ -1640,13 +1642,15 @@ int wps_build_cred(struct wps_data *wps, struct wpabuf *msg)
 				      wps->new_psk, wps->new_psk_len);
 		os_memcpy(wps->cred.key, wps->new_psk, wps->new_psk_len);
 		wps->cred.key_len = wps->new_psk_len;
-	} else if (wps->use_psk_key && wps->wps->psk_set) {
+	} else if (!wps->wps->registrar->force_per_enrollee_psk &&
+		   wps->use_psk_key && wps->wps->psk_set) {
 		char hex[65];
 		wpa_printf(MSG_DEBUG, "WPS: Use PSK format for Network Key");
 		wpa_snprintf_hex(hex, sizeof(hex), wps->wps->psk, 32);
 		os_memcpy(wps->cred.key, hex, 32 * 2);
 		wps->cred.key_len = 32 * 2;
-	} else if (wps->wps->network_key) {
+	} else if (!wps->wps->registrar->force_per_enrollee_psk &&
+		   wps->wps->network_key) {
 		os_memcpy(wps->cred.key, wps->wps->network_key,
 			  wps->wps->network_key_len);
 		wps->cred.key_len = wps->wps->network_key_len;

wpa_supplicant/ap.c

@@ -148,6 +148,7 @@ static int wpa_supplicant_conf_ap(struct wpa_supplicant *wpa_s,
 	}
 
 	bss->isolate = !wpa_s->conf->p2p_intra_bss;
+	bss->force_per_enrollee_psk = wpa_s->global->p2p_per_sta_psk;
 #endif /* CONFIG_P2P */
 
 	if (ssid->ssid_len == 0) {

wpa_supplicant/ctrl_iface.c

@@ -1,6 +1,6 @@
 /*
  * WPA Supplicant / Control interface (shared code for all backends)
- * Copyright (c) 2004-2012, Jouni Malinen <j@w1.fi>
+ * Copyright (c) 2004-2013, Jouni Malinen <j@w1.fi>
  *
  * This software may be distributed under the terms of the BSD license.
  * See README for more details.
@@ -4559,6 +4559,11 @@ static int p2p_ctrl_set(struct wpa_supplicant *wpa_s, char *cmd)
 					max_disc_int, max_disc_tu);
 	}
 
+	if (os_strcmp(cmd, "per_sta_psk") == 0) {
+		wpa_s->global->p2p_per_sta_psk = !!atoi(param);
+		return 0;
+	}
+
 	wpa_printf(MSG_DEBUG, "CTRL_IFACE: Unknown P2P_SET field value '%s'",
 		   cmd);
 

wpa_supplicant/wpa_cli.c

@@ -2076,6 +2076,7 @@ static char ** wpa_cli_complete_p2p_set(const char *str, int pos)
 		"client_apsd",
 		"disallow_freq",
 		"disc_int",
+		"per_sta_psk",
 	};
 	int i, num_fields = sizeof(fields) / sizeof(fields[0]);
 

wpa_supplicant/wpa_supplicant_i.h

@@ -265,6 +265,7 @@ struct wpa_global {
 		WPA_CONC_PREF_P2P
 	} conc_pref;
 	unsigned int p2p_cb_on_scan_complete:1;
+	unsigned int p2p_per_sta_psk:1;
 
 #ifdef CONFIG_WIFI_DISPLAY
 	int wifi_display;