nl80211: allow sending CMD_FRAME without specifying any frequency

Users may want to send a frame on the current channel
without specifying it.

This is particularly useful for the correct implementation
of the IBSS/RSN support in wpa_supplicant which requires to
receive and send AUTH frames.

Make mgmt_tx pass a NULL channel to the driver if none has
been specified by the user.
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -7147,6 +7147,9 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
 		return -EOPNOTSUPP;
 
 	switch (wdev->iftype) {
+	case NL80211_IFTYPE_P2P_DEVICE:
+		if (!info->attrs[NL80211_ATTR_WIPHY_FREQ])
+			return -EINVAL;
 	case NL80211_IFTYPE_STATION:
 	case NL80211_IFTYPE_ADHOC:
 	case NL80211_IFTYPE_P2P_CLIENT:
@@ -7154,7 +7157,6 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
 	case NL80211_IFTYPE_AP_VLAN:
 	case NL80211_IFTYPE_MESH_POINT:
 	case NL80211_IFTYPE_P2P_GO:
-	case NL80211_IFTYPE_P2P_DEVICE:
 		break;
 	default:
 		return -EOPNOTSUPP;
@@ -7182,9 +7184,18 @@ static int nl80211_tx_mgmt(struct sk_buff *skb, struct genl_info *info)
 
 	no_cck = nla_get_flag(info->attrs[NL80211_ATTR_TX_NO_CCK_RATE]);
 
-	err = nl80211_parse_chandef(rdev, info, &chandef);
-	if (err)
-		return err;
+	/* get the channel if any has been specified, otherwise pass NULL to
+	 * the driver. The latter will use the current one
+	 */
+	chandef.chan = NULL;
+	if (info->attrs[NL80211_ATTR_WIPHY_FREQ]) {
+		err = nl80211_parse_chandef(rdev, info, &chandef);
+		if (err)
+			return err;
+	}
+
+	if (!chandef.chan && offchan)
+		return -EINVAL;
 
 	if (!dont_wait_for_ack) {
 		msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);