When connecting to a WPA-EAP network and the MAC address is changed
just before the association (for example by NetworkManager, which sets
a random MAC during scans), the authentication sometimes fails in the
following way ('####' logs added by me):
wpa_supplicant logs:
wlan0: WPA: RX message 1 of 4-Way Handshake from 02:00:00:00:01:00 (ver=1)
RSN: msg 1/4 key data - hexdump(len=22): dd 14 00 0f ac 04 d8 21 9d a5 73 98 88 26 ef 03 d2 ce f7 04 7d 23
WPA: PMKID in EAPOL-Key - hexdump(len=22): dd 14 00 0f ac 04 d8 21 9d a5 73 98 88 26 ef 03 d2 ce f7 04 7d 23
RSN: PMKID from Authenticator - hexdump(len=16): d8 21 9d a5 73 98 88 26 ef 03 d2 ce f7 04 7d 23
wlan0: RSN: no matching PMKID found
EAPOL: Successfully fetched key (len=32)
WPA: PMK from EAPOL state machines - hexdump(len=32): [REMOVED]
#### WPA: rsn_pmkid():
#### WPA: aa - hexdump(len=6): 02 00 00 00 01 00
#### WPA: spa - hexdump(len=6): 66 20 cf ab 8c dc
#### WPA: PMK - hexdump(len=32): b5 24 76 4f 6f 50 8c f6 a1 2e 24 b8 07 4e 9a 13 1b 94 c4 a8 1f 7e 22 d6 ed fc 7d 43 c7 77 b6 f7
#### WPA: computed PMKID - hexdump(len=16): ea 73 67 b1 8e 5f 18 43 58 24 e8 1c 47 23 87 71
RSN: Replace PMKSA entry for the current AP and any PMKSA cache entry that was based on the old PMK
nl80211: Delete PMKID for 02:00:00:00:01:00
wlan0: RSN: PMKSA cache entry free_cb: 02:00:00:00:01:00 reason=1
RSN: Added PMKSA cache entry for 02:00:00:00:01:00 network_ctx=0x5630bf85a270
nl80211: Add PMKID for 02:00:00:00:01:00
wlan0: RSN: PMKID mismatch - authentication server may have derived different MSK?!
hostapd logs:
WPA: PMK from EAPOL state machine (MSK len=64 PMK len=32)
WPA: 02:00:00:00:00:00 WPA_PTK entering state PTKSTART
wlan1: STA 02:00:00:00:00:00 WPA: sending 1/4 msg of 4-Way Handshake
#### WPA: rsn_pmkid():
#### WPA: aa - hexdump(len=6): 02 00 00 00 01 00
#### WPA: spa - hexdump(len=6): 02 00 00 00 00 00
#### WPA: PMK - hexdump(len=32): b5 24 76 4f 6f 50 8c f6 a1 2e 24 b8 07 4e 9a 13 1b 94 c4 a8 1f 7e 22 d6 ed fc 7d 43 c7 77 b6 f7
#### WPA: computed PMKID - hexdump(len=16): d8 21 9d a5 73 98 88 26 ef 03 d2 ce f7 04 7d 23
WPA: Send EAPOL(version=1 secure=0 mic=0 ack=1 install=0 pairwise=1 kde_len=22 keyidx=0 encr=0)
That's because wpa_supplicant computed the PMKID using the wrong (old)
MAC address used during the scan. wpa_supplicant updates own_addr when
the interface goes up, as the MAC can only change while 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 later, 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.
Add a new driver event that notifies of MAC address changes while the
interface is active.
Signed-off-by: Beniamino Galvani <bgalvani@xxxxxxxxxx>
---
Changes since v1 at http://lists.infradead.org/pipermail/hostap/2017-September/037936.html
- reworded commit message
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 d9c6fd9f5..c250c11f6 100644
--- a/src/drivers/driver.h
+++ b/src/drivers/driver.h
@@ -4307,6 +4307,15 @@ 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
*
diff --git a/src/drivers/driver_common.c b/src/drivers/driver_common.c
index 33a6db346..c91d66ab5 100644
--- a/src/drivers/driver_common.c
+++ b/src/drivers/driver_common.c
@@ -53,6 +53,7 @@ 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 dfa11834c..13f5959b6 100644
--- a/src/drivers/driver_nl80211.c
+++ b/src/drivers/driver_nl80211.c
@@ -951,7 +951,7 @@ 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];
@@ -970,6 +970,11 @@ 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);
+ }
}
}
@@ -1041,11 +1046,11 @@ 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)",
@@ -1091,7 +1096,7 @@ 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 4f3604358..e8cbac548 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -4366,6 +4366,9 @@ 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) {
--
2.14.3
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