Re: [RFC] mac80211: validate key before MIC verify

[Johannes Berg <johannes@sipsolutions.net>]

On Fri, 2012-09-21 at 14:41 +0200, Stanislaw Gruszka wrote:

> --- a/net/mac80211/wpa.c
> +++ b/net/mac80211/wpa.c
> @@ -97,6 +97,14 @@ ieee80211_rx_h_michael_mic_verify(struct ieee80211_rx_data *rx)
>  		return RX_CONTINUE;
>  
>  	/*
> +	 * Some hardware seems to generate Michael MIC failure reports; even
> +	 * though, the frame was not encrypted with TKIP and therefore has no
> +	 * MIC. Ignore the flag them to avoid triggering countermeasures.
> +	 */
> +	if (!rx->key || rx->key->conf.cipher != WLAN_CIPHER_SUITE_TKIP)
> +		return RX_CONTINUE;
> +
> +	/*
>  	 * No way to verify the MIC if the hardware stripped it or
>  	 * the IV with the key index. In this case we have solely rely
>  	 * on the driver to set RX_FLAG_MMIC_ERROR in the event of a

Hm, this doesn't seem _quite_ right, but I'm not sure: it seems that
previously it was possible that we don't have a key pointer but the
driver set all of RX_FLAG_MMIC_STRIPPED, RX_FLAG_IV_STRIPPED and
RX_FLAG_MMIC_ERROR, in which case after your change the frame will be
accepted rather than rejected.

johannes