mac80211: allow drivers to report (non-)monitor frames

Some drivers offload some frames internally (e.g.
AddBa). Reporting such frames to mac80211 would
only confuse MLME. However it would be useful to
be able to pass such frames to monitor interfaces
for sniffing purposes, e.g. when running AP +
monitor.

To do that allow drivers to tell mac80211 whether
a given frame should be:
 - processed but not delivered to any monitor vif
 - not processed but delievered to monitor vifs
   only
Signed-off-by: Grzegorz Bajorski <grzegorz.bajorski@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -1031,6 +1031,14 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
  * @RX_FLAG_AMPDU_DELIM_CRC_KNOWN: The delimiter CRC field is known (the CRC
  *	is stored in the @ampdu_delimiter_crc field)
  * @RX_FLAG_LDPC: LDPC was used
+ * @RX_FLAG_ONLY_MONITOR: Report frame only to monitor interfaces without
+ *	processing it in any regular way.
+ *	This is useful if drivers offload some frames but still want to report
+ *	them for sniffing purposes.
+ * @RX_FLAG_SKIP_MONITOR: Process and report frame to all interfaces except
+ *	monitor interfaces.
+ *	This is useful if drivers offload some frames but still want to report
+ *	them for sniffing purposes.
  * @RX_FLAG_STBC_MASK: STBC 2 bit bitmask. 1 - Nss=1, 2 - Nss=2, 3 - Nss=3
  * @RX_FLAG_10MHZ: 10 MHz (half channel) was used
  * @RX_FLAG_5MHZ: 5 MHz (quarter channel) was used
@@ -1071,6 +1079,8 @@ enum mac80211_rx_flags {
 	RX_FLAG_MACTIME_END		= BIT(21),
 	RX_FLAG_VHT			= BIT(22),
 	RX_FLAG_LDPC			= BIT(23),
+	RX_FLAG_ONLY_MONITOR		= BIT(24),
+	RX_FLAG_SKIP_MONITOR		= BIT(25),
 	RX_FLAG_STBC_MASK		= BIT(26) | BIT(27),
 	RX_FLAG_10MHZ			= BIT(28),
 	RX_FLAG_5MHZ			= BIT(29),
@@ -1089,6 +1099,7 @@ enum mac80211_rx_flags {
  * @RX_VHT_FLAG_160MHZ: 160 MHz was used
  * @RX_VHT_FLAG_BF: packet was beamformed
  */
+
 enum mac80211_rx_vht_flags {
 	RX_VHT_FLAG_80MHZ		= BIT(0),
 	RX_VHT_FLAG_160MHZ		= BIT(1),

net/mac80211/rx.c

@@ -122,7 +122,8 @@ static inline bool should_drop_frame(struct sk_buff *skb, int present_fcs_len,
 	hdr = (void *)(skb->data + rtap_vendor_space);
 
 	if (status->flag & (RX_FLAG_FAILED_FCS_CRC |
-			    RX_FLAG_FAILED_PLCP_CRC))
+			    RX_FLAG_FAILED_PLCP_CRC |
+			    RX_FLAG_ONLY_MONITOR))
 		return true;
 
 	if (unlikely(skb->len < 16 + present_fcs_len + rtap_vendor_space))
@@ -507,7 +508,7 @@ ieee80211_rx_monitor(struct ieee80211_local *local, struct sk_buff *origskb,
 		return NULL;
 	}
 
-	if (!local->monitors) {
+	if (!local->monitors || (status->flag & RX_FLAG_SKIP_MONITOR)) {
 		if (should_drop_frame(origskb, present_fcs_len,
 				      rtap_vendor_space)) {
 			dev_kfree_skb(origskb);