wifi: rtl8xxxu: enable MFP support

In order to connect to networks which require 802.11w, add the
MFP_CAPABLE flag and let mac80211 do the actual crypto in software.

When a robust management frames is received, rx_dec->swdec is not set,
even though the HW did not decrypt it. Extend the check and don't set
RX_FLAG_DECRYPTED for these frames in order to use SW decryption.
Signed-off-by: Martin Kaistra <martin.kaistra@linutronix.de>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://msgid.link/20240314164850.86432-1-martin.kaistra@linutronix.de

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c

@@ -6473,7 +6473,9 @@ int rtl8xxxu_parse_rxdesc16(struct rtl8xxxu_priv *priv, struct sk_buff *skb)
 			rx_status->mactime = rx_desc->tsfl;
 			rx_status->flag |= RX_FLAG_MACTIME_START;
 
-			if (!rx_desc->swdec)
+			if (!rx_desc->swdec &&
+			    !(_ieee80211_is_robust_mgmt_frame(hdr) &&
+			      ieee80211_has_protected(hdr->frame_control)))
 				rx_status->flag |= RX_FLAG_DECRYPTED;
 			if (rx_desc->crc32)
 				rx_status->flag |= RX_FLAG_FAILED_FCS_CRC;
@@ -6578,7 +6580,9 @@ int rtl8xxxu_parse_rxdesc24(struct rtl8xxxu_priv *priv, struct sk_buff *skb)
 			rx_status->mactime = rx_desc->tsfl;
 			rx_status->flag |= RX_FLAG_MACTIME_START;
 
-			if (!rx_desc->swdec)
+			if (!rx_desc->swdec &&
+			    !(_ieee80211_is_robust_mgmt_frame(hdr) &&
+			      ieee80211_has_protected(hdr->frame_control)))
 				rx_status->flag |= RX_FLAG_DECRYPTED;
 			if (rx_desc->crc32)
 				rx_status->flag |= RX_FLAG_FAILED_FCS_CRC;
@@ -7998,6 +8002,7 @@ static int rtl8xxxu_probe(struct usb_interface *interface,
 	ieee80211_hw_set(hw, HAS_RATE_CONTROL);
 	ieee80211_hw_set(hw, SUPPORT_FAST_XMIT);
 	ieee80211_hw_set(hw, AMPDU_AGGREGATION);
+	ieee80211_hw_set(hw, MFP_CAPABLE);
 
 	wiphy_ext_feature_set(hw->wiphy, NL80211_EXT_FEATURE_CQM_RSSI_LIST);