mac80211: Get IV len from key conf and not cipher scheme

When a key is installed using a cipher scheme, set a new
internal key flag (KEY_FLAG_CIPHER_SCHEME) on it, to allow
distinguishing such keys more easily.

In particular, use this flag on the TX path instead of
testing the sta->cipher_scheme pointer, as the station is
NULL for broad-/multicast message, and use the key's iv_len
instead of the cipher scheme information.

Signed-off-by: Cedric Izoard <cedric.izoard@ceva-dsp.com>
[add missing documentation, rewrite commit message]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/key.c

@@ -492,6 +492,7 @@ ieee80211_key_alloc(u32 cipher, int idx, size_t key_len,
 				for (j = 0; j < len; j++)
 					key->u.gen.rx_pn[i][j] =
 							seq[len - j - 1];
+			key->flags |= KEY_FLAG_CIPHER_SCHEME;
 		}
 	}
 	memcpy(key->conf.key, key_data, key_len);

net/mac80211/key.h

@@ -30,10 +30,12 @@ struct sta_info;
  * @KEY_FLAG_UPLOADED_TO_HARDWARE: Indicates that this key is present
  *	in the hardware for TX crypto hardware acceleration.
  * @KEY_FLAG_TAINTED: Key is tainted and packets should be dropped.
+ * @KEY_FLAG_CIPHER_SCHEME: This key is for a hardware cipher scheme
  */
 enum ieee80211_internal_key_flags {
 	KEY_FLAG_UPLOADED_TO_HARDWARE	= BIT(0),
 	KEY_FLAG_TAINTED		= BIT(1),
+	KEY_FLAG_CIPHER_SCHEME		= BIT(2),
 };
 
 enum ieee80211_internal_tkip_state {

net/mac80211/wpa.c

@@ -780,9 +780,8 @@ ieee80211_crypto_cs_encrypt(struct ieee80211_tx_data *tx,
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 	struct ieee80211_key *key = tx->key;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
-	const struct ieee80211_cipher_scheme *cs = key->sta->cipher_scheme;
 	int hdrlen;
-	u8 *pos;
+	u8 *pos, iv_len = key->conf.iv_len;
 
 	if (info->control.hw_key &&
 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_PUT_IV_SPACE)) {
@@ -790,14 +789,14 @@ ieee80211_crypto_cs_encrypt(struct ieee80211_tx_data *tx,
 		return TX_CONTINUE;
 	}
 
-	if (unlikely(skb_headroom(skb) < cs->hdr_len &&
-		     pskb_expand_head(skb, cs->hdr_len, 0, GFP_ATOMIC)))
+	if (unlikely(skb_headroom(skb) < iv_len &&
+		     pskb_expand_head(skb, iv_len, 0, GFP_ATOMIC)))
 		return TX_DROP;
 
 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
 
-	pos = skb_push(skb, cs->hdr_len);
-	memmove(pos, pos + cs->hdr_len, hdrlen);
+	pos = skb_push(skb, iv_len);
+	memmove(pos, pos + iv_len, hdrlen);
 
 	return TX_CONTINUE;
 }
@@ -1217,7 +1216,7 @@ ieee80211_crypto_hw_encrypt(struct ieee80211_tx_data *tx)
 		if (!info->control.hw_key)
 			return TX_DROP;
 
-		if (tx->key->sta->cipher_scheme) {
+		if (tx->key->flags & KEY_FLAG_CIPHER_SCHEME) {
 			res = ieee80211_crypto_cs_encrypt(tx, skb);
 			if (res != TX_CONTINUE)
 				return res;