nl80211: Fix race condition in detecting MAC change

Commit 3e0272ca00ce1df35b45e7d739dd7e935f13fd84 ('nl80211: Re-read MAC
address on RTM_NEWLINK') added the detection of external changes to MAC
address when the interface is brought up.

If the interface state is changed quickly enough, wpa_supplicant may
receive the netlink message for the !IFF_UP event when the interface
has already been brought up and would ignore the next netlink IFF_UP
message, missing the MAC change.

Fix this by also reloading the MAC address when a !IFF_UP event is
received with the interface up, because this implies that the
interface went down and up again, possibly changing the address.

Signed-off-by: Beniamino Galvani <bgalvani@redhat.com>

diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c
index af1cb843d2ab3ad2a287aa63416b747dcbf65163..24fad29d9e434fe1cce22723dfb06d885010b099 100644 (file)
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -933,6 +933,30 @@ 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)
+{
+       struct i802_bss *bss;
+       u8 addr[ETH_ALEN];
+
+       bss = get_bss_ifindex(drv, ifindex);
+       if (bss &&
+           linux_get_ifhwaddr(drv->global->ioctl_sock,
+                              bss->ifname, addr) < 0) {
+               wpa_printf(MSG_DEBUG,
+                          "nl80211: %s: failed to re-read MAC address",
+                          bss->ifname);
+       } else if (bss && os_memcmp(addr, bss->addr, ETH_ALEN) != 0) {
+               wpa_printf(MSG_DEBUG,
+                          "nl80211: Own MAC address on ifindex %d (%s) changed from "
+                          MACSTR " to " MACSTR,
+                          ifindex, bss->ifname,
+                          MAC2STR(bss->addr), MAC2STR(addr));
+               os_memcpy(bss->addr, addr, ETH_ALEN);
+       }
+}
+
+
 static void wpa_driver_nl80211_event_rtm_newlink(void *ctx,
                                                 struct ifinfomsg *ifi,
                                                 u8 *buf, size_t len)
@@ -997,6 +1021,8 @@ 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;
@@ -1044,27 +1070,8 @@ static void wpa_driver_nl80211_event_rtm_newlink(void *ctx,
                                   "event since interface %s is marked "
                                   "removed", drv->first_bss->ifname);
                } else {
-                       struct i802_bss *bss;
-                       u8 addr[ETH_ALEN];
-
                        /* Re-read MAC address as it may have changed */
-                       bss = get_bss_ifindex(drv, ifi->ifi_index);
-                       if (bss &&
-                           linux_get_ifhwaddr(drv->global->ioctl_sock,
-                                              bss->ifname, addr) < 0) {
-                               wpa_printf(MSG_DEBUG,
-                                          "nl80211: %s: failed to re-read MAC address",
-                                          bss->ifname);
-                       } else if (bss &&
-                                  os_memcmp(addr, bss->addr, ETH_ALEN) != 0) {
-                               wpa_printf(MSG_DEBUG,
-                                          "nl80211: Own MAC address on ifindex %d (%s) changed from "
-                                          MACSTR " to " MACSTR,
-                                          ifi->ifi_index, bss->ifname,
-                                          MAC2STR(bss->addr),
-                                          MAC2STR(addr));
-                               os_memcpy(bss->addr, addr, ETH_ALEN);
-                       }
+                       nl80211_refresh_mac(drv, ifi->ifi_index);
 
                        wpa_printf(MSG_DEBUG, "nl80211: Interface up");
                        drv->if_disabled = 0;