staging: wfx: fix CCMP/TKIP replay protection

To enable the TKIP/CCMP replay protection, the frames has to be
processed in the right order. However, the device is not able to
re-order the frames during BlockAck sessions.

Mac80211 is able to reorder the frames, but it need the information
about the BlockAck sessions start and stop. Unfortunately, since the
BlockAck is fully handled by the hardware, these frames were not
forwarded to the host. So, if the driver ask to mac80211 to apply the
replay protection, it drop all misordered frames.

So, until now, the driver explicitly asked to mac80211 to not apply
the CCMP/TKIP replay protection.

The situation has changed with the API 3.4 of the device firmware. The
firmware forward the BlockAck information. Mac80211 is now able to
correctly reorder the frames. There is no more reasons to drop
cryptographic data.

This patch also impact the older firmwares. There will be a performance
impact on these firmware (since the misordered frames will dropped).
However, we can't keep the replay protection disabled.

Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200701150707.222985-12-Jerome.Pouiller@silabs.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/staging/wfx/data_tx.c b/drivers/staging/wfx/data_tx.c
index 5c744d9c8c11..3acf4eb0214d 100644
--- a/drivers/staging/wfx/data_tx.c
+++ b/drivers/staging/wfx/data_tx.c
@@ -418,7 +418,8 @@ void wfx_tx(struct ieee80211_hw *hw, struct ieee80211_tx_control *control,
 		wvif = wvif_iterate(wdev, NULL);
 	if (WARN_ON(!wvif))
 		goto drop;
-	// FIXME: why?
+	// Because of TX_AMPDU_SETUP_IN_HW, mac80211 does not try to send any
+	// BlockAck session management frame. The check below exist just in case.
 	if (ieee80211_is_action_back(hdr)) {
 		dev_info(wdev->dev, "drop BA action\n");
 		goto drop;