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>
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index f614ce7..13efab5 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -390,7 +390,8 @@
 	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 @@
 
 	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;