atheros broadcast/multicast corruption with multiple hostap's

[Russell Yount]

On Sat, Jan 16, 2010 at 3:21 PM, Sam Leffler <sam at errno.com> wrote:

>  Russell Yount wrote:
>
>> It seems AP to client broadcasts/multicasts traffic is
>> broken when using WPA2/802.11i with multiple hostapds in 8.0.
>>
>> Only the SSID associated with the last hostapd to be started has
>> AP to client broadcasts/multicasts being delivered correctly.
>>
>> The AP and client are 8.0 freebsd systems althought I see same
>> problems with windows XP as a client.
>>
>> The AP has 4 hostapds configured to use TLS with client certificates for
>> authentication. (hostapd recompiled with HOSTAPD_CFLAGS=-DEAP_SERVER)
>> The AP and client radio are shown as ath0: AR5212 mac 5.9 RF5112 phy 4.3
>> in dmesg.
>>
>> Client authenticate using client certificates associate correctly
>> to all 4 SSIDs. Unicast traffic flows correctly between clients and AP
>> for all for 4 SSIDs. Client to AP broadcast/multicast traffic works
>> on of 4 SSIDs. AP to client broadcast/multicast traffic only works
>> on 1 of the SSIDs. I have documented this using ARP broadcasts,
>> but normal IP broadcasts also observed to corrupted.
>>
>> When an ARP request is send through the AP to an associated client
>> it seems to be trashed on any of the SSID except the one associated
>> with the last hostapd to be started. Here is the output of client side
>> tcpdump showing the problems.
>>
>> In the first client side tcpdump with the hostapd associated with the SSID
>> being associaed with the last hostapd started and the traffic flowing
>> normally.
>>
>> In the second client side tcpdump with the hostapd associated with the
>> SSID
>> being not the last hostapd started the ARP request is resent multiple
>> times
>> and appears corrupted.
>>
>> I would really like to find a fix for this.
>> Any help would be greatly appreciated.
>>
>
> This sounds like the crypto encap of the frame is clobbering the mbuf
> contents.  You can verify this by setting up multiple vaps w/o WPA.  If this
> is the problem look for the mbuf copy logic for mcast frames and make sure a
> deep copy is done.
>
>        Sam
>



The four VAPs broadcast traffic works find without WPA if I do not start
hostapds on them

I have been trying to discovery why broadcast traffic only works correctly
on the VAP associated with the last hostapd to be started. I have move with
VAP has the working broadcast traffic by restarting the hostapd
associated with it.

 It would seem something in the WPA/802.1x layer initialization remembers
which hostapd was started last and that affected the crypto encap.

I keep looking but do not see any place in the code that could account for
this.

It seems the corrupt crypto encap also happens on broadcast between
stations.
Please correct me if I am wrong:
but when using hostapd normally traffic is bridged withing the card.
So if a station sends to the VAP a broadcast it is actaully sending a non-
broadcast frame to the AP
and the AP sends the frame to all the other stations.

-Russ