From 77a020a118168e05e7cc0d28a7bf661772e531af Mon Sep 17 00:00:00 2001 From: Beniamino Galvani Date: Thu, 15 Feb 2018 11:50:01 +0100 Subject: [PATCH] wpa_supplicant: Fix auth failure when the MAC is updated externally 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 --- src/drivers/driver.h | 9 +++++++++ src/drivers/driver_common.c | 1 + src/drivers/driver_nl80211.c | 11 +++++++---- wpa_supplicant/events.c | 3 +++ 4 files changed, 20 insertions(+), 4 deletions(-) diff --git a/src/drivers/driver.h b/src/drivers/driver.h index 338a56eeb..d7aeef99c 100644 --- a/src/drivers/driver.h +++ b/src/drivers/driver.h @@ -4585,6 +4585,15 @@ enum wpa_event_type { * change event. */ EVENT_STATION_OPMODE_CHANGED, + + /** + * 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, }; diff --git a/src/drivers/driver_common.c b/src/drivers/driver_common.c index 9de9693f5..ca4668aa8 100644 --- a/src/drivers/driver_common.c +++ b/src/drivers/driver_common.c @@ -85,6 +85,7 @@ const char * event_to_string(enum wpa_event_type event) E2S(EXTERNAL_AUTH); E2S(PORT_AUTHORIZED); E2S(STATION_OPMODE_CHANGED); + E2S(INTERFACE_MAC_CHANGED); } return "UNKNOWN"; diff --git a/src/drivers/driver_nl80211.c b/src/drivers/driver_nl80211.c index f7421c4bf..ac06d20fc 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, int notify) { struct i802_bss *bss; u8 addr[ETH_ALEN]; @@ -970,6 +970,9 @@ 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 +1044,11 @@ 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, 1); return; } wpa_printf(MSG_DEBUG, "nl80211: Interface down (%s/%s)", @@ -1091,7 +1094,7 @@ 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, 0); wpa_printf(MSG_DEBUG, "nl80211: Interface up"); drv->if_disabled = 0; diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c index fe64fc285..19c8475b6 100644 --- a/wpa_supplicant/events.c +++ b/wpa_supplicant/events.c @@ -4374,6 +4374,9 @@ 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) {