supplicant: set optional PMF using global supplicant property

wpa_supplicant is going to change the global default for PMF from 0
(disabled) to 1 (optional) [1], so NM code needs to be adjusted to
work with all wpa_supplicant versions. Furthermore, it is better to
set optional PMF using the 'Pmf' property instead of the 'ieee80211w'
configuration option because the former better handles missing support
in driver [2].

Note that each interface in wpa_supplicant has its own copy of global
configuration and so 'global' options must still be set on each
interface. So, let's set Pmf=1 when each interface gets created and
override it with ieee80211w={0,2} if needed during association.

[1] http://lists.infradead.org/pipermail/hostap/2018-November/039009.html
[2] http://lists.infradead.org/pipermail/hostap/2019-January/039215.html

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/issues/104

src/supplicant/nm-supplicant-config.c

@@ -869,11 +869,11 @@ nm_supplicant_config_add_setting_wireless_security (NMSupplicantConfig *self,
 
 		if (   !nm_streq (key_mgmt, "wpa-none")
 		    && NM_IN_SET (pmf,
-		                  NM_SETTING_WIRELESS_SECURITY_PMF_OPTIONAL,
+		                  NM_SETTING_WIRELESS_SECURITY_PMF_DISABLE,
 		                  NM_SETTING_WIRELESS_SECURITY_PMF_REQUIRED)) {
 			if (!nm_supplicant_config_add_option (self,
 			                                      "ieee80211w",
-			                                      pmf == NM_SETTING_WIRELESS_SECURITY_PMF_OPTIONAL ? "1" : "2",
+			                                      pmf == NM_SETTING_WIRELESS_SECURITY_PMF_DISABLE ? "0" : "2",
 			                                      -1,
 			                                      NULL,
 			                                      error))

src/supplicant/nm-supplicant-interface.c

@@ -716,6 +716,26 @@ iface_check_netreply_cb (GDBusProxy *proxy, GAsyncResult *result, gpointer user_
 	iface_check_ready (self);
 }
 
+static void
+iface_set_pmf_cb (GDBusProxy *proxy, GAsyncResult *result, gpointer user_data)
+{
+	NMSupplicantInterface *self;
+	gs_unref_variant GVariant *variant = NULL;
+	gs_free_error GError *error = NULL;
+
+	variant = g_dbus_proxy_call_finish (proxy, result, &error);
+	if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+		return;
+
+	self = NM_SUPPLICANT_INTERFACE (user_data);
+
+	/* This can fail if the supplicant doesn't support PMF */
+	if (error)
+		_LOGD ("failed to set Pmf=1: %s", error->message);
+
+	iface_check_ready (self);
+}
+
 gboolean
 nm_supplicant_interface_get_p2p_group_joined (NMSupplicantInterface *self)
 {
@@ -1619,6 +1639,20 @@ on_iface_proxy_acquired (GDBusProxy *proxy, GAsyncResult *result, gpointer user_
 	                   NULL,
 	                   NULL);
 
+	/* Initialize global PMF setting to 'optional' */
+	priv->ready_count++;
+	g_dbus_proxy_call (priv->iface_proxy,
+	                   DBUS_INTERFACE_PROPERTIES ".Set",
+	                   g_variant_new ("(ssv)",
+	                                  WPAS_DBUS_IFACE_INTERFACE,
+	                                  "Pmf",
+	                                  g_variant_new_string ("1")),
+	                   G_DBUS_CALL_FLAGS_NONE,
+	                   -1,
+	                   priv->init_cancellable,
+	                   (GAsyncReadyCallback) iface_set_pmf_cb,
+	                   self);
+
 	/* Check whether NetworkReply and AP mode are supported */
 	g_dbus_proxy_call (priv->iface_proxy,
 	                   "NetworkReply",

src/supplicant/tests/test-supplicant-config.c

@@ -359,8 +359,8 @@ test_wifi_wpa_psk (const char *detail,
 	NMTST_EXPECT_NM_INFO ("Config: added 'pairwise' value 'TKIP CCMP'");
 	NMTST_EXPECT_NM_INFO ("Config: added 'group' value 'TKIP CCMP'");
 	switch (pmf) {
-	case NM_SETTING_WIRELESS_SECURITY_PMF_OPTIONAL:
+	case NM_SETTING_WIRELESS_SECURITY_PMF_DISABLE:
-		NMTST_EXPECT_NM_INFO ("Config: added 'ieee80211w' value '1'");
+		NMTST_EXPECT_NM_INFO ("Config: added 'ieee80211w' value '0'");
 		break;
 	case NM_SETTING_WIRELESS_SECURITY_PMF_REQUIRED:
 		NMTST_EXPECT_NM_INFO ("Config: added 'ieee80211w' value '2'");