mac80211: AMPDU handling for rekeys with Extended Key ID

Extended Key ID allows A-MPDU sessions while rekeying as long as each
A-MPDU aggregates only MPDUs with one keyid together.

Drivers able to segregate MPDUs accordingly can tell mac80211 to not
stop A-MPDU sessions when rekeying by setting the new flag
IEEE80211_HW_AMPDU_KEYBORDER_SUPPORT.

Signed-off-by: Alexander Wetzel <alexander@wetzel-home.de>
Link: https://lore.kernel.org/r/20190629195015.19680-3-alexander@wetzel-home.de
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

3 files changed, 14 insertions, 6 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 58941893a13f..0187d84031fc 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -2268,6 +2268,10 @@ struct ieee80211_txq {
  * @IEEE80211_HW_SUPPORTS_ONLY_HE_MULTI_BSSID: Hardware supports multi BSSID
  *      only for HE APs. Applies if @IEEE80211_HW_SUPPORTS_MULTI_BSSID is set.
  *
+ * @IEEE80211_HW_AMPDU_KEYBORDER_SUPPORT: The card and driver is only
+ *      aggregating MPDUs with the same keyid, allowing mac80211 to keep Tx
+ *      A-MPDU sessions active while rekeying with Extended Key ID.
+ *
  * @NUM_IEEE80211_HW_FLAGS: number of hardware flags, used for sizing arrays
  */
 enum ieee80211_hw_flags {
@@ -2319,6 +2323,7 @@ enum ieee80211_hw_flags {
         IEEE80211_HW_TX_STATUS_NO_AMPDU_LEN,
         IEEE80211_HW_SUPPORTS_MULTI_BSSID,
         IEEE80211_HW_SUPPORTS_ONLY_HE_MULTI_BSSID,
+        IEEE80211_HW_AMPDU_KEYBORDER_SUPPORT,
 
         /* keep last, obviously */
         NUM_IEEE80211_HW_FLAGS
diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c
index 47435f57e086..568b3b276931 100644
--- a/net/mac80211/debugfs.c
+++ b/net/mac80211/debugfs.c
@@ -271,6 +271,7 @@ static const char *hw_flag_names[] = {
         FLAG(TX_STATUS_NO_AMPDU_LEN),
         FLAG(SUPPORTS_MULTI_BSSID),
         FLAG(SUPPORTS_ONLY_HE_MULTI_BSSID),
+        FLAG(AMPDU_KEYBORDER_SUPPORT),
 #undef FLAG
 };
 
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 92c3affb0eb0..7dfee848abac 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -270,7 +270,8 @@ int ieee80211_set_tx_key(struct ieee80211_key *key)
 
         sta->ptk_idx = key->conf.keyidx;
 
-        clear_sta_flag(sta, WLAN_STA_BLOCK_BA);
+        if (!ieee80211_hw_check(&local->hw, AMPDU_KEYBORDER_SUPPORT))
+                clear_sta_flag(sta, WLAN_STA_BLOCK_BA);
         ieee80211_check_fast_xmit(sta);
 
         return 0;
@@ -288,15 +289,16 @@ static void ieee80211_pairwise_rekey(struct ieee80211_key *old,
         if (new->conf.flags & IEEE80211_KEY_FLAG_NO_AUTO_TX) {
                 /* Extended Key ID key install, initial one or rekey */
 
-                if (sta->ptk_idx != INVALID_PTK_KEYIDX) {
+                if (sta->ptk_idx != INVALID_PTK_KEYIDX &&
+                    !ieee80211_hw_check(&local->hw, AMPDU_KEYBORDER_SUPPORT)) {
                         /* Aggregation Sessions with Extended Key ID must not
                          * mix MPDUs with different keyIDs within one A-MPDU.
                          * Tear down running Tx aggregation sessions and block
                          * new Rx/Tx aggregation requests during rekey to
-                         * ensure there are no A-MPDUs for the driver to
-                         * aggregate. (Blocking Tx only would be sufficient but
-                         * WLAN_STA_BLOCK_BA gets the job done for the few ms
-                         * we need it.)
+                         * ensure there are no A-MPDUs when the driver is not
+                         * supporting A-MPDU key borders. (Blocking Tx only
+                         * would be sufficient but WLAN_STA_BLOCK_BA gets the
+                         * job done for the few ms we need it.)
                          */
                         set_sta_flag(sta, WLAN_STA_BLOCK_BA);
                         mutex_lock(&sta->ampdu_mlme.mtx);