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Commit 66760eac authored by Felix Fietkau's avatar Felix Fietkau Committed by John W. Linville
Browse files

ath9k: improve reliability of MIC error detection 



For unicast the hardware sometimes reports MIC errors even though the
frame that it received actually contains a valid MIC - on some chips this
can happen frequently enough to trigger TKIP countermeasures.
Fix this issue by not reporting MIC errors for unicast frames with a
valid key, letting mac80211 validate the MIC instead.

Additionally, strip the MIC for all frames that the hardware considers
valid to avoid wasting CPU cycles re-validating it.

Signed-off-by: default avatarFelix Fietkau <nbd@openwrt.org>
Signed-off-by: default avatarJohn W. Linville <linville@tuxdriver.com>
parent 933d5943

drivers/net/wireless/ath/ath9k/recv.c

+32 −21
Original line number Original line Diff line number Diff line
@@ -814,16 +814,19 @@ static bool ath9k_rx_accept(struct ath_common *common, 
			    struct ath_rx_status *rx_stats,

			    struct ath_rx_status *rx_stats,

			    bool *decrypt_error)

			    bool *decrypt_error)

{

{

#define is_mc_or_valid_tkip_keyix ((is_mc ||			\

	bool is_mc, is_valid_tkip, strip_mic, mic_error;

		(rx_stats->rs_keyix != ATH9K_RXKEYIX_INVALID && \

		test_bit(rx_stats->rs_keyix, common->tkip_keymap))))



	struct ath_hw *ah = common->ah;

	struct ath_hw *ah = common->ah;

	__le16 fc;

	__le16 fc;

	u8 rx_status_len = ah->caps.rx_status_len;

	u8 rx_status_len = ah->caps.rx_status_len;





	fc = hdr->frame_control;

	fc = hdr->frame_control;





	is_mc = !!is_multicast_ether_addr(hdr->addr1);

	is_valid_tkip = rx_stats->rs_keyix != ATH9K_RXKEYIX_INVALID &&

		test_bit(rx_stats->rs_keyix, common->tkip_keymap);

	strip_mic = is_valid_tkip && !(rx_stats->rs_status &

		(ATH9K_RXERR_DECRYPT | ATH9K_RXERR_CRC | ATH9K_RXERR_MIC));



	if (!rx_stats->rs_datalen)

	if (!rx_stats->rs_datalen)

		return false;

		return false;

        /*

        /*
@@ -838,6 +841,11 @@ static bool ath9k_rx_accept(struct ath_common *common, 
	if (rx_stats->rs_more)

	if (rx_stats->rs_more)

		return true;

		return true;





	mic_error = is_valid_tkip && !ieee80211_is_ctl(fc) &&

		!ieee80211_has_morefrags(fc) &&

		!(le16_to_cpu(hdr->seq_ctrl) & IEEE80211_SCTL_FRAG) &&

		(rx_stats->rs_status & ATH9K_RXERR_MIC);



	/*

	/*

	 * The rx_stats->rs_status will not be set until the end of the

	 * The rx_stats->rs_status will not be set until the end of the

	 * chained descriptors so it can be ignored if rs_more is set. The

	 * chained descriptors so it can be ignored if rs_more is set. The
@@ -845,30 +853,18 @@ static bool ath9k_rx_accept(struct ath_common *common, 
	 * descriptors.

	 * descriptors.

	 */

	 */

	if (rx_stats->rs_status != 0) {

	if (rx_stats->rs_status != 0) {

		if (rx_stats->rs_status & ATH9K_RXERR_CRC)

		if (rx_stats->rs_status & ATH9K_RXERR_CRC) {

			rxs->flag |= RX_FLAG_FAILED_FCS_CRC;

			rxs->flag |= RX_FLAG_FAILED_FCS_CRC;

			mic_error = false;

		}

		if (rx_stats->rs_status & ATH9K_RXERR_PHY)

		if (rx_stats->rs_status & ATH9K_RXERR_PHY)

			return false;

			return false;





		if (rx_stats->rs_status & ATH9K_RXERR_DECRYPT) {

		if (rx_stats->rs_status & ATH9K_RXERR_DECRYPT) {

			*decrypt_error = true;

			*decrypt_error = true;

		} else if (rx_stats->rs_status & ATH9K_RXERR_MIC) {

			mic_error = false;

			bool is_mc;

			/*

			 * The MIC error bit is only valid if the frame

			 * is not a control frame or fragment, and it was

			 * decrypted using a valid TKIP key.

			 */

			is_mc = !!is_multicast_ether_addr(hdr->addr1);



			if (!ieee80211_is_ctl(fc) &&

			    !ieee80211_has_morefrags(fc) &&

			    !(le16_to_cpu(hdr->seq_ctrl) & IEEE80211_SCTL_FRAG) &&

			    is_mc_or_valid_tkip_keyix)

				rxs->flag |= RX_FLAG_MMIC_ERROR;

			else

				rx_stats->rs_status &= ~ATH9K_RXERR_MIC;

		}

		}



		/*

		/*

		 * Reject error frames with the exception of

		 * Reject error frames with the exception of

		 * decryption and MIC failures. For monitor mode,

		 * decryption and MIC failures. For monitor mode,
@@ -886,6 +882,18 @@ static bool ath9k_rx_accept(struct ath_common *common, 
			}

			}

		}

		}

	}

	}



	/*

	 * For unicast frames the MIC error bit can have false positives,

	 * so all MIC error reports need to be validated in software.

	 * False negatives are not common, so skip software verification

	 * if the hardware considers the MIC valid.

	 */

	if (strip_mic)

		rxs->flag |= RX_FLAG_MMIC_STRIPPED;

	else if (is_mc && mic_error)

		rxs->flag |= RX_FLAG_MMIC_ERROR;



	return true;

	return true;

}

}
@@ -1938,6 +1946,9 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush, bool hp) 
			sc->rx.rxotherant = 0;

			sc->rx.rxotherant = 0;

		}

		}





		if (rxs->flag & RX_FLAG_MMIC_STRIPPED)

			skb_trim(skb, skb->len - 8);



		spin_lock_irqsave(&sc->sc_pm_lock, flags);

		spin_lock_irqsave(&sc->sc_pm_lock, flags);





		if ((sc->ps_flags & (PS_WAIT_FOR_BEACON |

		if ((sc->ps_flags & (PS_WAIT_FOR_BEACON |