Re: [PATCH v2] wireless: support configuring vdev mac addr on create.

[Arend van Spriel <arend@broadcom.com>]

On 01-10-14 19:57, greearb@candelatech.com wrote:
> From: Ben Greear <greearb@candelatech.com>
> 
> This is useful when creating virtual-stations, and probably
> APs and other devices as well.  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>
> ---
> 
> v2:  Use is_valid_ether_addr
> 
>  include/net/cfg80211.h       | 6 +++---
>  include/uapi/linux/nl80211.h | 3 +++
>  net/mac80211/iface.c         | 5 ++++-
>  net/mac80211/main.c          | 1 +
>  net/wireless/nl80211.c       | 2 +-
>  5 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
> index e1641e6..de9a67f 100644
> --- a/include/net/cfg80211.h
> +++ b/include/net/cfg80211.h
> @@ -319,9 +319,9 @@ 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.
>   */
>  struct vif_params {
>         int use_4addr;
> diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
> index 4b28dc0..fd14703 100644
> --- a/include/uapi/linux/nl80211.h
> +++ b/include/uapi/linux/nl80211.h
> @@ -4042,6 +4042,8 @@ enum nl80211_ap_sme_features {
>   *	multiplexing powersave, ie. can turn off all but one chain
>   *	and then wake the rest up as required after, for example,
>   *	rts/cts handshake.
> + * @NL80211_FEATURE_MAC_ON_CREATE: Device supports configuring
> + *	the vdev's MAC address upon creation.
>   */
>  enum nl80211_feature_flags {
>  	NL80211_FEATURE_SK_TX_STATUS			= 1 << 0,
> @@ -4070,6 +4072,7 @@ enum nl80211_feature_flags {
>  	NL80211_FEATURE_ACKTO_ESTIMATION		= 1 << 23,
>  	NL80211_FEATURE_STATIC_SMPS			= 1 << 24,
>  	NL80211_FEATURE_DYNAMIC_SMPS			= 1 << 25,
> +	NL80211_FEATURE_MAC_ON_CREATE			= 1 << 26,
>  };
>  
>  /**
> diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
> index 878bfca..e92783f 100644
> --- a/net/mac80211/iface.c
> +++ b/net/mac80211/iface.c
> @@ -1715,7 +1715,10 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
>  		}
>  
>  		ieee80211_assign_perm_addr(local, ndev->perm_addr, type);
> -		memcpy(ndev->dev_addr, ndev->perm_addr, ETH_ALEN);
> +		if (params && is_valid_ether_addr(params->macaddr))
> +			memcpy(ndev->dev_addr, params->macaddr, ETH_ALEN);
> +		else
> +			memcpy(ndev->dev_addr, ndev->perm_addr, ETH_ALEN);
>  		SET_NETDEV_DEV(ndev, wiphy_dev(local->hw.wiphy));
>  
>  		/* don't use IEEE80211_DEV_TO_SUB_IF -- it checks too much */
> diff --git a/net/mac80211/main.c b/net/mac80211/main.c
> index 8106770..eb7bdd1 100644
> --- a/net/mac80211/main.c
> +++ b/net/mac80211/main.c
> @@ -550,6 +550,7 @@ struct ieee80211_hw *ieee80211_alloc_hw(size_t priv_data_len,
>  			   NL80211_FEATURE_SAE |
>  			   NL80211_FEATURE_HT_IBSS |
>  			   NL80211_FEATURE_VIF_TXPOWER |
> +			   NL80211_FEATURE_MAC_ON_CREATE |
>  			   NL80211_FEATURE_USERSPACE_MPM;
>  
>  	if (!ops->hw_scan)
> diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
> index 8a010bd..cf79707 100644
> --- a/net/wireless/nl80211.c
> +++ b/net/wireless/nl80211.c
> @@ -2605,7 +2605,7 @@ 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 (info->attrs[NL80211_ATTR_MAC]) {
>  		nla_memcpy(params.macaddr, info->attrs[NL80211_ATTR_MAC],
>  			   ETH_ALEN);
>  		if (!is_valid_ether_addr(params.macaddr))

Hi Ben,

Just noticed this last line and realized that my comment on the previous
patch is invalid. nl80211.c already validates the mac address received
from iw. The zero address check in ieee80211_if_add() is to determine
whether iw provided a mac address or not.

Regards,
Arend