mac80211: Add MIC space only for TX key option

Add a key flag to indicates that the device only needs
MIC space and not a real MIC.
In such cases, keep the MIC zeroed for ease of debug.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

4 files changed, 29 insertions, 9 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 2ee4af25256d..906e90223066 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1552,6 +1552,9 @@ struct wireless_dev *ieee80211_vif_to_wdev(struct ieee80211_vif *vif);
  * @IEEE80211_KEY_FLAG_RESERVE_TAILROOM: This flag should be set by the
  *      driver for a key to indicate that sufficient tailroom must always
  *      be reserved for ICV or MIC, even when HW encryption is enabled.
+ * @IEEE80211_KEY_FLAG_PUT_MIC_SPACE: This flag should be set by the driver for
+ *      a TKIP key if it only requires MIC space. Do not set together with
+ *      @IEEE80211_KEY_FLAG_GENERATE_MMIC on the same key.
  */
 enum ieee80211_key_flags {
         IEEE80211_KEY_FLAG_GENERATE_IV_MGMT     = BIT(0),
@@ -1562,6 +1565,7 @@ enum ieee80211_key_flags {
         IEEE80211_KEY_FLAG_PUT_IV_SPACE         = BIT(5),
         IEEE80211_KEY_FLAG_RX_MGMT              = BIT(6),
         IEEE80211_KEY_FLAG_RESERVE_TAILROOM     = BIT(7),
+        IEEE80211_KEY_FLAG_PUT_MIC_SPACE        = BIT(8),
 };
 
 /**
@@ -1593,8 +1597,8 @@ struct ieee80211_key_conf {
         u8 icv_len;
         u8 iv_len;
         u8 hw_key_idx;
-        u8 flags;
         s8 keyidx;
+        u16 flags;
         u8 keylen;
         u8 key[0];
 };
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 938049395f90..aee05ec3f7ea 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -178,13 +178,17 @@ static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
         if (!ret) {
                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
 
-                if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+                if (!((key->conf.flags & (IEEE80211_KEY_FLAG_GENERATE_MMIC |
+                                           IEEE80211_KEY_FLAG_PUT_MIC_SPACE)) ||
                       (key->conf.flags & IEEE80211_KEY_FLAG_RESERVE_TAILROOM)))
                         decrease_tailroom_need_count(sdata, 1);
 
                 WARN_ON((key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE) &&
                         (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV));
 
+                WARN_ON((key->conf.flags & IEEE80211_KEY_FLAG_PUT_MIC_SPACE) &&
+                        (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC));
+
                 return 0;
         }
 
@@ -237,7 +241,8 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
         sta = key->sta;
         sdata = key->sdata;
 
-        if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+        if (!((key->conf.flags & (IEEE80211_KEY_FLAG_GENERATE_MMIC |
+                                   IEEE80211_KEY_FLAG_PUT_MIC_SPACE)) ||
               (key->conf.flags & IEEE80211_KEY_FLAG_RESERVE_TAILROOM)))
                 increment_tailroom_need_count(sdata);
 
@@ -1104,7 +1109,8 @@ void ieee80211_remove_key(struct ieee80211_key_conf *keyconf)
         if (key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE) {
                 key->flags &= ~KEY_FLAG_UPLOADED_TO_HARDWARE;
 
-                if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
+                if (!((key->conf.flags & (IEEE80211_KEY_FLAG_GENERATE_MMIC |
+                                           IEEE80211_KEY_FLAG_PUT_MIC_SPACE)) ||
                       (key->conf.flags & IEEE80211_KEY_FLAG_RESERVE_TAILROOM)))
                         increment_tailroom_need_count(key->sdata);
         }
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 3160954fc406..25904af38839 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2922,7 +2922,9 @@ void ieee80211_check_fast_xmit(struct sta_info *sta)
 
                 gen_iv = build.key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV;
                 iv_spc = build.key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE;
-                mmic = build.key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC;
+                mmic = build.key->conf.flags &
+                        (IEEE80211_KEY_FLAG_GENERATE_MMIC |
+                         IEEE80211_KEY_FLAG_PUT_MIC_SPACE);
 
                 /* don't handle software crypto */
                 if (!(build.key->flags & KEY_FLAG_UPLOADED_TO_HARDWARE))
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index b58722d9de37..785056cb76f6 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -1,7 +1,7 @@
 /*
  * Copyright 2002-2004, Instant802 Networks, Inc.
  * Copyright 2008, Jouni Malinen <j@w1.fi>
- * Copyright (C) 2016 Intel Deutschland GmbH
+ * Copyright (C) 2016-2017 Intel Deutschland GmbH
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -59,8 +59,9 @@ ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
         if (info->control.hw_key &&
             (info->flags & IEEE80211_TX_CTL_DONTFRAG ||
              ieee80211_hw_check(&tx->local->hw, SUPPORTS_TX_FRAG)) &&
-            !(tx->key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC)) {
-                /* hwaccel - with no need for SW-generated MMIC */
+            !(tx->key->conf.flags & (IEEE80211_KEY_FLAG_GENERATE_MMIC |
+                                     IEEE80211_KEY_FLAG_PUT_MIC_SPACE))) {
+                /* hwaccel - with no need for SW-generated MMIC or MIC space */
                 return TX_CONTINUE;
         }
 
@@ -75,8 +76,15 @@ ieee80211_tx_h_michael_mic_add(struct ieee80211_tx_data *tx)
                  skb_tailroom(skb), tail))
                 return TX_DROP;
 
-        key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY];
         mic = skb_put(skb, MICHAEL_MIC_LEN);
+
+        if (tx->key->conf.flags & IEEE80211_KEY_FLAG_PUT_MIC_SPACE) {
+                /* Zeroed MIC can help with debug */
+                memset(mic, 0, MICHAEL_MIC_LEN);
+                return TX_CONTINUE;
+        }
+
+        key = &tx->key->conf.key[NL80211_TKIP_DATA_OFFSET_TX_MIC_KEY];
         michael_mic(key, hdr, data, data_len, mic);
         if (unlikely(info->flags & IEEE80211_TX_INTFL_TKIP_MIC_FAILURE))
                 mic[0]++;