mac80211: allow same PN for AMSDU sub-frames

Some hardware (iwlwifi an example) de-aggregate AMSDUs and copy the IV
as is to the generated MPDUs, so the same PN appears in multiple
packets without being a replay attack.  Allow driver to explicitly
indicate that a frame is allowed to have the same PN as the previous
frame.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 07ef937..ce2f6e3 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1068,6 +1068,9 @@
  * @RX_FLAG_RADIOTAP_VENDOR_DATA: This frame contains vendor-specific
  *	radiotap data in the skb->data (before the frame) as described by
  *	the &struct ieee80211_vendor_radiotap.
+ * @RX_FLAG_ALLOW_SAME_PN: Allow the same PN as same packet before.
+ *	This is used for AMSDU subframes which can have the same PN as
+ *	the first subframe.
  */
 enum mac80211_rx_flags {
 	RX_FLAG_MMIC_ERROR		= BIT(0),
@@ -1101,7 +1104,8 @@
 	RX_FLAG_5MHZ			= BIT(29),
 	RX_FLAG_AMSDU_MORE		= BIT(30),
 	RX_FLAG_RADIOTAP_VENDOR_DATA	= BIT(31),
-	RX_FLAG_MIC_STRIPPED            = BIT_ULL(32),
+	RX_FLAG_MIC_STRIPPED		= BIT_ULL(32),
+	RX_FLAG_ALLOW_SAME_PN		= BIT_ULL(33),
 };
 
 #define RX_FLAG_STBC_SHIFT		26