cfg80211: support configuring vif mac addr on create

This is useful when creating virtual interfaces.
Keeps udev from mucking with things it shouldn't, since
the default MAC is never seen by udev when specified on
the cmd-line during creation.
Signed-off-by: Ben Greear <greearb@candelatech.com>
[check for feature flag in nl80211 to force drivers to set it]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -319,9 +319,12 @@ struct ieee80211_supported_band {
 /**
  * struct vif_params - describes virtual interface parameters
  * @use_4addr: use 4-address frames
- * @macaddr: address to use for this virtual interface. This will only
- * 	be used for non-netdevice interfaces. If this parameter is set
- * 	to zero address the driver may determine the address as needed.
+ * @macaddr: address to use for this virtual interface.
+ *	If this parameter is set to zero address the driver may
+ *	determine the address as needed.
+ *	This feature is only fully supported by drivers that enable the
+ *	%NL80211_FEATURE_MAC_ON_CREATE flag.  Others may support creating
+ **	only p2p devices with specified MAC.
  */
 struct vif_params {
        int use_4addr;

include/uapi/linux/nl80211.h

@@ -4056,6 +4056,9 @@ enum nl80211_ap_sme_features {
  *	TSPEC sessions (TID aka TSID 0-7) with the %NL80211_CMD_ADD_TX_TS
  *	command. Standard IEEE 802.11 TSPEC setup is not yet supported, it
  *	needs to be able to handle Block-Ack agreements and other things.
+ * @NL80211_FEATURE_MAC_ON_CREATE: Device supports configuring
+ *	the vif's MAC address upon creation.
+ *	See 'macaddr' field in the vif_params (cfg80211.h).
  */
 enum nl80211_feature_flags {
 	NL80211_FEATURE_SK_TX_STATUS			= 1 << 0,
@@ -4085,6 +4088,7 @@ enum nl80211_feature_flags {
 	NL80211_FEATURE_STATIC_SMPS			= 1 << 24,
 	NL80211_FEATURE_DYNAMIC_SMPS			= 1 << 25,
 	NL80211_FEATURE_SUPPORTS_WMM_ADMISSION		= 1 << 26,
+	NL80211_FEATURE_MAC_ON_CREATE			= 1 << 27,
 };
 
 /**

net/wireless/nl80211.c

@@ -2605,7 +2605,9 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 	    !(rdev->wiphy.interface_modes & (1 << type)))
 		return -EOPNOTSUPP;
 
-	if (type == NL80211_IFTYPE_P2P_DEVICE && info->attrs[NL80211_ATTR_MAC]) {
+	if ((type == NL80211_IFTYPE_P2P_DEVICE ||
+	     rdev->wiphy.features & NL80211_FEATURE_MAC_ON_CREATE) &&
+	    info->attrs[NL80211_ATTR_MAC]) {
 		nla_memcpy(params.macaddr, info->attrs[NL80211_ATTR_MAC],
 			   ETH_ALEN);
 		if (!is_valid_ether_addr(params.macaddr))