Re: [BUG] ath9k truncated management packets from TKIP connected stations

[Felix Fietkau <nbd@openwrt.org>]

On 2011-08-16 2:31 PM, Bill Jordan wrote:
> I'm not quite sure what the correct fix is for this.
>
> Ath9k in AP mode with a TKIP security: If a connected station sends a
> management packet, the packet is truncated by 8 bytes before being
> delivered to hostapd. This prevents the station from reauthenticating
> or connecting to a different SSID on the same radio.
>
> In ath9k_rx_accept, for management packets, strip_mic will be true,
> and RX_FLAG_MMIC_STRIPPED will be set in rxs->flag. In
> ath9k_rx_skb_postprocess, if ah->sw_mgmt_crypto is set,
> RX_FLAG_DECRYPTED will be cleared. However, RX_FLAG_MMIC_STRIPPED will
> still be set, so, in ath_rx_tasklet, 8 bytes will be trimmed off the
> end of the skb.
>
> I'm thinking that in ath9k_rx_accept, is_valid_tkip  should also
> consider ieee80211_is_mgmt(fc). But this wouldn't take into
> consideration ah->sw_mgmt_crypto.
>
> Alternatively, RX_FLAG_MMIC_STRIPPED could be cleared in
> ath9k_rx_skb_postprocess when RX_FLAG_DECRYPTED is cleared.
>
> I'm looking for input from someone who understands this code better.
We should probably just keep strip_mic set to false for mgmt frames.

- Felix