[PATCH] wpa_supplicant: update MAC when driver detects a change

[Beniamino Galvani]

wpa_supplicant updates own_addr when the interface becomes enabled, as
the MAC can only change when the interface is down. However, drivers
don't report all interface state changes: for example the nl80211
driver may ignore a down-up cycle if the down message is processed
when the interface is already up.

In such cases, wpa_supplicant (and in particular, the EAP state
machine) would continue to use the old MAC causing authentication
failures due to a mismatch of the computed PMKID.

Add a new driver event that notifies of MAC address changes while the
interface is active.

Signed-off-by: Beniamino Galvani <bgalvani at redhat.com>
---
 src/drivers/driver.h         |  9 +++++++++
 src/drivers/driver_common.c  |  1 +
 src/drivers/driver_nl80211.c | 13 +++++++++----
 wpa_supplicant/events.c      |  3 +++
 4 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/drivers/driver.h b/src/drivers/driver.h
index 6797a5a84..0e04af3f3 100644
--- a/src/drivers/driver.h
+++ b/src/drivers/driver.h
@@ -4220,6 +4220,15 @@ enum wpa_event_type {
 	EVENT_SIGNAL_CHANGE,
 
 	/**
+	 * EVENT_INTERFACE_MAC_CHANGED - Notify that interface MAC changed
+	 *
+	 * This event is emitted when the MAC changes while the interface is
+	 * enabled. When an interface was disabled and becomes enabled, it
+	 * must be always assumed that the MAC possibly changed.
+	 */
+	EVENT_INTERFACE_MAC_CHANGED,
+
+	/**
 	 * EVENT_INTERFACE_ENABLED - Notify that interface was enabled
 	 *
 	 * This event is used to indicate that the interface was enabled after
diff --git a/src/drivers/driver_common.c b/src/drivers/driver_common.c
index 220b7d415..c77cced88 100644
--- a/src/drivers/driver_common.c
+++ b/src/drivers/driver_common.c
@@ -54,6 +54,7 @@ const char * event_to_string(enum wpa_event_type event)
 	E2S(NEW_STA);
 	E2S(EAPOL_RX);
 	E2S(SIGNAL_CHANGE);
+	E2S(INTERFACE_MAC_CHANGED);
 	E2S(INTERFACE_ENABLED);
 	E2S(INTERFACE_DISABLED);
 	E2S(CHANNEL_LIST_CHANGED);
diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index 23bfae1de..9e855e825 100644
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -947,7 +947,7 @@ nl80211_find_drv(struct nl80211_global *global, int idx, u8 *buf, size_t len,
 
 
 static void nl80211_refresh_mac(struct wpa_driver_nl80211_data *drv,
-				int ifindex)
+				int ifindex, Boolean notify)
 {
 	struct i802_bss *bss;
 	u8 addr[ETH_ALEN];
@@ -966,6 +966,11 @@ static void nl80211_refresh_mac(struct wpa_driver_nl80211_data *drv,
 			   ifindex, bss->ifname,
 			   MAC2STR(bss->addr), MAC2STR(addr));
 		os_memcpy(bss->addr, addr, ETH_ALEN);
+		if (notify) {
+			wpa_supplicant_event(drv->ctx,
+					     EVENT_INTERFACE_MAC_CHANGED,
+					     NULL);
+		}
 	}
 }
 
@@ -1037,11 +1042,11 @@ static void wpa_driver_nl80211_event_rtm_newlink(void *ctx,
 		namebuf[0] = '\0';
 		if (if_indextoname(ifi->ifi_index, namebuf) &&
 		    linux_iface_up(drv->global->ioctl_sock, namebuf) > 0) {
-			/* Re-read MAC address as it may have changed */
-			nl80211_refresh_mac(drv, ifi->ifi_index);
 			wpa_printf(MSG_DEBUG, "nl80211: Ignore interface down "
 				   "event since interface %s is up", namebuf);
 			drv->ignore_if_down_event = 0;
+			/* Re-read MAC address as it may have changed */
+			nl80211_refresh_mac(drv, ifi->ifi_index, TRUE);
 			return;
 		}
 		wpa_printf(MSG_DEBUG, "nl80211: Interface down (%s/%s)",
@@ -1087,7 +1092,7 @@ static void wpa_driver_nl80211_event_rtm_newlink(void *ctx,
 				   "removed", drv->first_bss->ifname);
 		} else {
 			/* Re-read MAC address as it may have changed */
-			nl80211_refresh_mac(drv, ifi->ifi_index);
+			nl80211_refresh_mac(drv, ifi->ifi_index, FALSE);
 
 			wpa_printf(MSG_DEBUG, "nl80211: Interface up");
 			drv->if_disabled = 0;
diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c
index db7de89ed..e760febce 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -4236,6 +4236,9 @@ void wpa_supplicant_event(void *ctx, enum wpa_event_type event,
 			data->signal_change.current_noise,
 			data->signal_change.current_txrate);
 		break;
+	case EVENT_INTERFACE_MAC_CHANGED:
+		wpa_supplicant_update_mac_addr(wpa_s);
+		break;
 	case EVENT_INTERFACE_ENABLED:
 		wpa_dbg(wpa_s, MSG_DEBUG, "Interface was enabled");
 		if (wpa_s->wpa_state == WPA_INTERFACE_DISABLED) {
-- 
2.13.5