WPA-EAP network stops working after random interval

Jouni Malinen j at w1.fi
Sat Dec 10 06:31:06 EST 2011


On Mon, Dec 05, 2011 at 09:48:25PM +0000, George B. wrote:
> I have only noticed the problem in the last few weeks, which makes
> me suspect that some recent update (kernel, or driver, or something
> else) broke something, but I wanted to run the data past you guys
> first.
> 
> I am able to reproduce the issue - it takes about 5-10 minutes to
> hit. Running "reassoc" from wpa_cli also resolves the issue for me
> until next time (thanks Håvard!)

> ---
> <2>WPA: Group rekeying completed with 00:1e:c1:a2:70:50 [GTK=TKIP]
> <2>WPA: Group rekeying completed with 00:1e:c1:a2:70:50 [GTK=TKIP]
> ---
> 
> After the first time everything works, after the second time
> connectivity is lost (traces will eventually show ARP packets being
> sent out by my laptop into the ether).

Based on just this information, my guess would be that something got
broken in the driver since the second group rekeying would be
configuring the previously used key index again and that could trigger
some bugs.

That said, there is something very strange and quite different in the
debug log below..


> This is the bit from the debug log at the time of the second message above:
> ---
> IEEE 802.1X RX: version=1 type=3 length=95
>    EAPOL-Key type=254
>    key_info 0x89 (ver=1 keyidx=0 rsvd=0 Pairwise Ack)
> State: COMPLETED -> 4WAY_HANDSHAKE
> WPA: RX message 1 of 4-Way Handshake from 00:1e:c1:a2:70:50 (ver=1)

This is not normal group rekeying, but actually full 4-way handshake +
group keying.

> IEEE 802.1X RX: version=1 type=3 length=119
>    EAPOL-Key type=254
>    key_info 0x1c9 (ver=1 keyidx=0 rsvd=0 Pairwise Install Ack MIC)
>    key_length=32 key_data_length=24
> WPA: Invalid EAPOL-Key MIC when using TPTK - ignoring TPTK
> WPA: Invalid EAPOL-Key MIC - dropping packet

And this does not look good.. It looks like the AP would be using
incorrect key here..

> RX EAPOL from 00:1e:c1:a2:70:50
> IEEE 802.1X RX: version=1 type=3 length=127
>    EAPOL-Key type=254
>    key_info 0x3b1 (ver=1 keyidx=3 rsvd=0 Group Ack MIC Secure)

> WPA: Invalid EAPOL-Key MIC when using TPTK - ignoring TPTK
> WPA: RX message 1 of Group Key Handshake from 00:1e:c1:a2:70:50 (ver=1)
> State: 4WAY_HANDSHAKE -> GROUP_HANDSHAKE
> WPA: Group Key - hexdump(len=32): [REMOVED]
> WPA: Installing GTK to the driver (keyidx=3 tx=0 len=32).

But the AP still allows group key handshake to go through with the old
PTK.. This looks quite broken behavior. However, there is not enough
details here to confirm what exactly happened.

Would you be able to send me full debug log with all the key material
included? This can obviously be done with a temporary passphrase so that
your real key does not get exposed. I would need to have full debug log
from wpa_supplicant (-ddKt on command line) and the WPA passphrase
(well, it would show up in that log) for the full sequence (first
association and the two group rekeying steps). Getting a packet capture
trace with all the EAPOL frames would also be helpful. Feel free to send
these directly to me (j at w1.fi) instead of the mailing list.

-- 
Jouni Malinen                                            PGP id EFC895FA


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