Re: WPA and WPA2

[Dan Williams <dcbw@redhat.com>]

On Thu, 2017-05-25 at 08:40 +1000, Tobin C. Harding wrote:
> On Wed, May 24, 2017 at 08:06:40PM +0200, Johannes Berg wrote:
> > Just a small correction:
> > 
> > On Wed, 2017-05-24 at 11:44 -0500, Dan Williams wrote:
> > > 
> > > For RSN, they are 1 = PMK, 2 = GMK, 3 = GMK2, 4 seems unused.
> > 
> > PTK and GTK, and in theory you could have more than two GTKs but
> > that's
> > not usually done.
> 
> Excuse my ignorance but why do you say PTK and GTK here? Who
> generates
> the transient keys, hardware, firmware or software? Is this device
> specific or is there a *normal* way?
> 
> From the nomenclature in the WEXT driver I thought the driver
> supplied the
> master keys to the firmware and transient keys were generated at the
> firmware layer or lower.

Usually the supplicant supplies only the PTK/GTK to the driver at the
right times (like during the 4-way handshake).  It looks like the
driver only refers to PMK/GMK when using the rx_seq[] bits, while the
actual WPA keys are probably the PTK/GTK.

While it's not the best example, see
drivers/net/wireless/marvell/libertas/cfg.c and lbs_cfg_connect() and
lbs_cfg_add_key().  That should translate fairly well to the ks7010
driver.  The important parts you'll get from nl80211 are
add_key/del_key and set_default_key.  The connect hook gets called
first to tell the driver to start the auth/assoc process to a given AP,
 and that's where you'd set up the general stuff like whether or not
you'll use WEP or WPA, what the SSID/BSSID are, whether PSK or
EAPOL/802.1x, rates, etc.  Then after that you'll get the add_key hook
that actually sends the real keys to the driver when the supplicant has
calculated them.


Dan