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Commit 72abd81b authored by Johannes Berg's avatar Johannes Berg Committed by David S. Miller
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[MAC80211]: allow drivers to indicate failed FCS/PLCP checksum 



This patch allows drivers to indicate bad FCS/PLCP CRC to the stack and
have the stack drop packets like that except for monitor interfaces.

Signed-off-by: default avatarJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: default avatarMichael Wu <flamingice@sourmilk.net>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ac630c2b

include/net/mac80211.h

+6 −0
Original line number Diff line number Diff line
@@ -235,6 +235,10 @@ struct ieee80211_tx_control { 
 * @RX_FLAG_IV_STRIPPED: The IV/ICV are stripped from this frame.

 *	If this flag is set, the stack cannot do any replay detection

 *	hence the driver or hardware will have to do that.

 * @RX_FLAG_FAILED_FCS_CRC: Set this flag if the FCS check failed on

 *	the frame.

 * @RX_FLAG_FAILED_PLCP_CRC: Set this flag if the PCLP check failed on

 *	the frame.

 */

enum mac80211_rx_flags {

	RX_FLAG_MMIC_ERROR	= 1<<0,
@@ -242,6 +246,8 @@ enum mac80211_rx_flags { 
	RX_FLAG_RADIOTAP	= 1<<2,

	RX_FLAG_MMIC_STRIPPED	= 1<<3,

	RX_FLAG_IV_STRIPPED	= 1<<4,

	RX_FLAG_FAILED_FCS_CRC	= 1<<5,

	RX_FLAG_FAILED_PLCP_CRC = 1<<6,

};



/**

net/mac80211/rx.c

+29 −3
Original line number Diff line number Diff line
@@ -145,6 +145,8 @@ ieee80211_rx_monitor(struct net_device *dev, struct sk_buff *skb, 
		__le16 chan_freq;

		__le16 chan_flags;

		u8 antsignal;

		u8 padding_for_rxflags;

		__le16 rx_flags;

	} __attribute__ ((packed)) *rthdr;



	skb->dev = dev;
@@ -167,12 +169,21 @@ ieee80211_rx_monitor(struct net_device *dev, struct sk_buff *skb, 
		cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |

			    (1 << IEEE80211_RADIOTAP_RATE) |

			    (1 << IEEE80211_RADIOTAP_CHANNEL) |

			    (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL));

			    (1 << IEEE80211_RADIOTAP_DB_ANTSIGNAL) |

			    (1 << IEEE80211_RADIOTAP_RX_FLAGS));

	rthdr->flags = local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS ?

		       IEEE80211_RADIOTAP_F_FCS : 0;



	/* FIXME: when radiotap gets a 'bad PLCP' flag use it here */

	rthdr->rx_flags = 0;

	if (status->flag &

	    (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))

		rthdr->rx_flags |= cpu_to_le16(IEEE80211_RADIOTAP_F_RX_BADFCS);



	rate = ieee80211_get_rate(local, status->phymode, status->rate);

	if (rate)

		rthdr->rate = rate->rate / 5;



	rthdr->chan_freq = cpu_to_le16(status->freq);

	rthdr->chan_flags =

		status->phymode == MODE_IEEE80211A ?
@@ -200,6 +211,15 @@ ieee80211_rx_h_monitor(struct ieee80211_txrx_data *rx) 
		return TXRX_QUEUED;

	}



	/*

	 * Drop frames with failed FCS/PLCP checksums here, they are only

	 * relevant for monitor mode, the rest of the stack should never

	 * see them.

	 */

	if (rx->u.rx.status->flag &

	    (RX_FLAG_FAILED_FCS_CRC | RX_FLAG_FAILED_PLCP_CRC))

		return TXRX_DROP;



	if (rx->u.rx.status->flag & RX_FLAG_RADIOTAP)

		skb_pull(rx->skb, ieee80211_get_radiotap_len(rx->skb->data));
@@ -1360,6 +1380,7 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb, 
	struct ieee80211_sub_if_data *prev = NULL;

	struct sk_buff *skb_new;

	u8 *bssid;

	int bogon;



	if (status->flag & RX_FLAG_RADIOTAP) {

		radiotap_len = ieee80211_get_radiotap_len(skb->data);
@@ -1380,10 +1401,15 @@ void __ieee80211_rx(struct ieee80211_hw *hw, struct sk_buff *skb, 
	rx.u.rx.status = status;

	rx.fc = skb->len >= 2 ? le16_to_cpu(hdr->frame_control) : 0;

	type = rx.fc & IEEE80211_FCTL_FTYPE;

	if (type == IEEE80211_FTYPE_DATA || type == IEEE80211_FTYPE_MGMT)



	bogon = status->flag & (RX_FLAG_FAILED_FCS_CRC |

				RX_FLAG_FAILED_PLCP_CRC);



	if (!bogon && (type == IEEE80211_FTYPE_DATA ||

		       type == IEEE80211_FTYPE_MGMT))

		local->dot11ReceivedFragmentCount++;



	if (skb->len >= 16) {

	if (!bogon && skb->len >= 16) {

		sta = rx.sta = sta_info_get(local, hdr->addr2);

		if (sta) {

			rx.dev = rx.sta->dev;