[PATCH v2] wpa_supplicant: fix auth failure when the MAC is updated externally
Dan Williams
dcbw at redhat.com
Tue Mar 20 14:31:21 PDT 2018
On Thu, 2018-02-15 at 11:50 +0100, Beniamino Galvani wrote:
> 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):
Patch looks reasonable to me. Jouni, any thoughts on this one?
Thanks!
Dan
> 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 at redhat.com>
> ---
>
> 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_CHA
> NGED,
> + 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) {
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