mt7601u: let mac80211 validate rx CCMP PN

Apparently the hardware does not perform CCMP PN validation so
let mac80211 take care of possible replay attacks in sw.
Moreover indicate ICV and MIC had been stripped setting corresponding
bits in ieee80211_rx_status.
The fix has been validated using 4.2.1 and 4.1.3 tests from the WiFi
Alliance vulnerability detection tool.

Fixes: c869f77d ("add mt7601u driver")
Acked-by: Jakub Kicinski <kubakici@wp.pl>
Tested-by: David Park <david.park@hitemengineering.com>
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/mediatek/mt7601u/initvals.h

@@ -139,6 +139,7 @@ static const struct mt76_reg_pair mac_common_vals[] = {
 	{ MT_TXOP_HLDR_ET,		0x00000002 },
 	{ MT_XIFS_TIME_CFG,		0x33a41010 },
 	{ MT_PWR_PIN_CFG,		0x00000000 },
+	{ MT_PN_PAD_MODE,		0x00000001 },
 };
 
 static const struct mt76_reg_pair mac_chip_vals[] = {

drivers/net/wireless/mediatek/mt7601u/mac.c

@@ -480,8 +480,16 @@ u32 mt76_mac_process_rx(struct mt7601u_dev *dev, struct sk_buff *skb,
 
 	if (rxwi->rxinfo & cpu_to_le32(MT_RXINFO_DECRYPT)) {
 		status->flag |= RX_FLAG_DECRYPTED;
-		status->flag |= RX_FLAG_IV_STRIPPED | RX_FLAG_MMIC_STRIPPED;
+		status->flag |= RX_FLAG_MMIC_STRIPPED;
+		status->flag |= RX_FLAG_MIC_STRIPPED;
+		status->flag |= RX_FLAG_ICV_STRIPPED;
+		status->flag |= RX_FLAG_IV_STRIPPED;
 	}
+	/* let mac80211 take care of PN validation since apparently
+	 * the hardware does not support it
+	 */
+	if (rxwi->rxinfo & cpu_to_le32(MT_RXINFO_PN_LEN))
+		status->flag &= ~RX_FLAG_IV_STRIPPED;
 
 	status->chains = BIT(0);
 	rssi = mt7601u_phy_get_rssi(dev, rxwi, rate);