linux-kernel - Re: [PATCH 5.10 030/252] mac80211: prevent attacks on TKIP/WEP as well

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Message-ID: <20210601093125.GA30646@amd>
Date:   Tue, 1 Jun 2021 11:31:25 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Johannes Berg <johannes.berg@...el.com>
Subject: Re: [PATCH 5.10 030/252] mac80211: prevent attacks on TKIP/WEP as
 well

Hi!

So this changes bool variables to u8:1, but still assigns true/false
there, which looks like "interesting" style. Should we switch to 0/1?

Best regards,
								Pavel

> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -2284,6 +2284,7 @@ ieee80211_rx_h_defragment(struct ieee802
>  			 * next fragment has a sequential PN value.
>  			 */
>  			entry->check_sequential_pn = true;
> +			entry->is_protected = true;
>  			entry->key_color = rx->key->color;
>  			memcpy(entry->last_pn,
>  			       rx->key->u.ccmp.rx_pn[queue],
> @@ -2296,6 +2297,9 @@ ieee80211_rx_h_defragment(struct ieee802
>  				     sizeof(rx->key->u.gcmp.rx_pn[queue]));
>  			BUILD_BUG_ON(IEEE80211_CCMP_PN_LEN !=
>  				     IEEE80211_GCMP_PN_LEN);
> +		} else if (rx->key && ieee80211_has_protected(fc)) {
> +			entry->is_protected = true;
> +			entry->key_color = rx->key->color;
>  		}
>  		return RX_QUEUED;
>  	}
> @@ -2337,6 +2341,14 @@ ieee80211_rx_h_defragment(struct ieee802
>  		if (memcmp(pn, rpn, IEEE80211_CCMP_PN_LEN))
>  			return RX_DROP_UNUSABLE;
>  		memcpy(entry->last_pn, pn, IEEE80211_CCMP_PN_LEN);
> +	} else if (entry->is_protected &&
> +		   (!rx->key || !ieee80211_has_protected(fc) ||
> +		    rx->key->color != entry->key_color)) {
> +		/* Drop this as a mixed key or fragment cache attack, even
> +		 * if for TKIP Michael MIC should protect us, and WEP is a
> +		 * lost cause anyway.
> +		 */
> +		return RX_DROP_UNUSABLE;
>  	}
>  
>  	skb_pull(rx->skb, ieee80211_hdrlen(fc));
> --- a/net/mac80211/sta_info.h
> +++ b/net/mac80211/sta_info.h
> @@ -453,7 +453,8 @@ struct ieee80211_fragment_entry {
>  	u16 extra_len;
>  	u16 last_frag;
>  	u8 rx_queue;
> -	bool check_sequential_pn; /* needed for CCMP/GCMP */
> +	u8 check_sequential_pn:1, /* needed for CCMP/GCMP */
> +	   is_protected:1;
>  	u8 last_pn[6]; /* PN of the last fragment if CCMP was used */
>  	unsigned int key_color;
>  };
> 

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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