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From:   James Prestwood <prestwoj@gmail.com>
To:     linux-wireless@vger.kernel.org
Cc:     James Prestwood <prestwoj@gmail.com>
Subject: [RFC 0/1] Allow MAC change on up interface
Date:   Thu, 15 Aug 2019 11:57:01 -0700
Message-Id: <20190815185702.30937-1-prestwoj@gmail.com>
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

This is an example of how a devices MAC address could be changed while
the interface is up. Currently RTNL and mac80211 both require the
interface be down before changing the MAC.

After poking around a bit I found that some drivers can actually
change the MAC while the iface is up. Allowing user space to do this
while the iface is up would elminate a few potential race conditions
that arise when changing the MAC from user space.

This commit does a few things:
 - Adds an EXT_FEATURE that user space can check to see if the driver
   allows this MAC changing.
 - Adds a new NL80211_ATTR for including a "random mac" to     
   CMD_CONNECT. This MAC is passed down the stack and gets set to 
   the net_device's address.
 - Set this wiphy extended feature in iwlwifi (just as an example)
 - Relax checks in mac80211 which check if the interface is running
 - Set IFF_LIVE_ADDR_CHANGE on net_device. Note: I know setting this
   where I did is likely not the right way to do it, but for this
   proof-of-concept it works. With guidance I can move this around
   to a proper place.

James Prestwood (1):
  RFC: allow mac address change on up iface

 .../net/wireless/intel/iwlwifi/mvm/mac80211.c |  2 ++
 include/net/cfg80211.h                        |  1 +
 include/uapi/linux/nl80211.h                  |  3 +++
 net/mac80211/iface.c                          |  5 ++---
 net/wireless/nl80211.c                        |  9 +++++++++
 net/wireless/sme.c                            | 20 +++++++++++++++++++
 6 files changed, 37 insertions(+), 3 deletions(-)

-- 
2.17.1