mac80211: support adding IV-room in the skb for CCMP keys

Some cards can generate CCMP IVs in HW, but require the space for the IV
to be pre-allocated in the frame at the correct offset. Add a key flag
that allows us to achieve this.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

3 files changed, 19 insertions, 3 deletions

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index dc1123aa8181..f4e0ab49db20 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -901,6 +901,10 @@ static inline bool ieee80211_vif_is_mesh(struct ieee80211_vif *vif)
  * @IEEE80211_KEY_FLAG_SW_MGMT: This flag should be set by the driver for a
  *      CCMP key if it requires CCMP encryption of management frames (MFP) to
  *      be done in software.
+ * @IEEE80211_KEY_FLAG_PUT_IV_SPACE: This flag should be set by the driver
+ *      for a CCMP key if space should be prepared for the IV, but the IV
+ *      itself should not be generated. Do not set together with
+ *      @IEEE80211_KEY_FLAG_GENERATE_IV on the same key.
  */
 enum ieee80211_key_flags {
         IEEE80211_KEY_FLAG_WMM_STA      = 1<<0,
@@ -908,6 +912,7 @@ enum ieee80211_key_flags {
         IEEE80211_KEY_FLAG_GENERATE_MMIC= 1<<2,
         IEEE80211_KEY_FLAG_PAIRWISE     = 1<<3,
         IEEE80211_KEY_FLAG_SW_MGMT      = 1<<4,
+        IEEE80211_KEY_FLAG_PUT_IV_SPACE = 1<<5,
 };
 
 /**
diff --git a/net/mac80211/key.c b/net/mac80211/key.c
index 756b157c2edd..17a5220ed450 100644
--- a/net/mac80211/key.c
+++ b/net/mac80211/key.c
@@ -133,9 +133,13 @@ static int ieee80211_key_enable_hw_accel(struct ieee80211_key *key)
                 key->flags |= KEY_FLAG_UPLOADED_TO_HARDWARE;
 
                 if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
-                      (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
+                      (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
+                      (key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)))
                         sdata->crypto_tx_tailroom_needed_cnt--;
 
+                WARN_ON((key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE) &&
+                        (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV));
+
                 return 0;
         }
 
@@ -178,7 +182,8 @@ static void ieee80211_key_disable_hw_accel(struct ieee80211_key *key)
         sdata = key->sdata;
 
         if (!((key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_MMIC) ||
-              (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV)))
+              (key->conf.flags & IEEE80211_KEY_FLAG_GENERATE_IV) ||
+              (key->conf.flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)))
                 increment_tailroom_need_count(sdata);
 
         if (sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index f614ce7bb6e3..13efab5bf12a 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -390,7 +390,8 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
         u8 scratch[6 * AES_BLOCK_SIZE];
 
         if (info->control.hw_key &&
-            !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV)) {
+            !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
+            !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
                 /*
                  * hwaccel has no need for preallocated room for CCMP
                  * header or MIC fields
@@ -412,6 +413,11 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 
         pos = skb_push(skb, CCMP_HDR_LEN);
         memmove(pos, pos + CCMP_HDR_LEN, hdrlen);
+
+        /* the HW only needs room for the IV, but not the actual IV */
+        if (info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)
+                return 0;
+
         hdr = (struct ieee80211_hdr *) pos;
         pos += hdrlen;