mac80211: add IEEE80211_KEY_FLAG_GENERATE_MMIE to ieee80211_key_flags

Add IEEE80211_KEY_FLAG_GENERATE_MMIE flag to ieee80211_key_flags in order
to allow the driver to notify mac80211 to generate MMIE and that it
requires sequence number generation only.
This is a preliminary patch to add BIP_CMAC_128 hw support to mt7615
driver

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://lore.kernel.org/r/dfe275f9aa0f1cc6b33085f9efd5d8447f68ad13.1563228405.git.lorenzo@kernel.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -1704,6 +1704,9 @@ struct wireless_dev *ieee80211_vif_to_wdev(struct ieee80211_vif *vif);
  *	a TKIP key if it only requires MIC space. Do not set together with
  *	@IEEE80211_KEY_FLAG_GENERATE_MMIC on the same key.
  * @IEEE80211_KEY_FLAG_NO_AUTO_TX: Key needs explicit Tx activation.
+ * @IEEE80211_KEY_FLAG_GENERATE_MMIE: This flag should be set by the driver
+ *	for a AES_CMAC key to indicate that it requires sequence number
+ *	generation only
  */
 enum ieee80211_key_flags {
 	IEEE80211_KEY_FLAG_GENERATE_IV_MGMT	= BIT(0),
@@ -1716,6 +1719,7 @@ enum ieee80211_key_flags {
 	IEEE80211_KEY_FLAG_RESERVE_TAILROOM	= BIT(7),
 	IEEE80211_KEY_FLAG_PUT_MIC_SPACE	= BIT(8),
 	IEEE80211_KEY_FLAG_NO_AUTO_TX		= BIT(9),
+	IEEE80211_KEY_FLAG_GENERATE_MMIE	= BIT(10),
 };
 
 /**

net/mac80211/wpa.c

@@ -946,7 +946,8 @@ ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
 
 	info = IEEE80211_SKB_CB(skb);
 
-	if (info->control.hw_key)
+	if (info->control.hw_key &&
+	    !(key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIE))
 		return TX_CONTINUE;
 
 	if (WARN_ON(skb_tailroom(skb) < sizeof(*mmie)))
@@ -962,6 +963,9 @@ ieee80211_crypto_aes_cmac_encrypt(struct ieee80211_tx_data *tx)
 
 	bip_ipn_set64(mmie->sequence_number, pn64);
 
+	if (info->control.hw_key)
+		return TX_CONTINUE;
+
 	bip_aad(skb, aad);
 
 	/*