iwlwifi: mvm: capture the FCS in monitor mode

This can be useful when using the device as a sniffer.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/iwlwifi/mvm/mac-ctxt.c

@@ -719,7 +719,9 @@ static int iwl_mvm_mac_ctxt_cmd_listener(struct iwl_mvm *mvm,
 	cmd.filter_flags = cpu_to_le32(MAC_FILTER_IN_PROMISC |
 				       MAC_FILTER_IN_CONTROL_AND_MGMT |
 				       MAC_FILTER_IN_BEACON |
-				       MAC_FILTER_IN_PROBE_REQUEST);
+				       MAC_FILTER_IN_PROBE_REQUEST |
+				       MAC_FILTER_IN_CRC32);
+	mvm->hw->flags |= IEEE80211_HW_RX_INCLUDES_FCS;
 
 	return iwl_mvm_mac_ctxt_send_cmd(mvm, &cmd);
 }
@@ -1122,6 +1124,10 @@ int iwl_mvm_mac_ctxt_remove(struct iwl_mvm *mvm, struct ieee80211_vif *vif)
 	}
 
 	mvmvif->uploaded = false;
+
+	if (vif->type == NL80211_IFTYPE_MONITOR)
+		mvm->hw->flags &= ~IEEE80211_HW_RX_INCLUDES_FCS;
+
 	return 0;
 }
 

drivers/net/wireless/iwlwifi/mvm/rx.c

@@ -300,10 +300,14 @@ int iwl_mvm_rx_rx_mpdu(struct iwl_mvm *mvm, struct iwl_rx_cmd_buffer *rxb,
 		return 0;
 	}
 
+	/*
+	 * Keep packets with CRC errors (and with overrun) for monitor mode
+	 * (otherwise the firmware discards them) but mark them as bad.
+	 */
 	if (!(rx_pkt_status & RX_MPDU_RES_STATUS_CRC_OK) ||
 	    !(rx_pkt_status & RX_MPDU_RES_STATUS_OVERRUN_OK)) {
 		IWL_DEBUG_RX(mvm, "Bad CRC or FIFO: 0x%08X.\n", rx_pkt_status);
-		return 0;
+		rx_status.flag |= RX_FLAG_FAILED_FCS_CRC;
 	}
 
 	/* This will be used in several places later */