deauthentication and disassociation nl80211 commands

Maxim Levitsky maximlevitsky at gmail.com
Fri Oct 9 23:45:40 EDT 2009


On Mon, 2009-10-05 at 04:11 +0200, Maxim Levitsky wrote: 
> Here I want to ask and summarize problems we found in thread
> 'driver_nl80211 broken again'
> 
> 
> First of all it it known that lifetime of connection to access point is
> typically:
> 
> authentication request/response
> association request/response
> 
> EAPOL 4 way handshake (for WPA)
> 
> <session>
> 
> disassociation
> deauthentication
> 
> Today kernel explicitly requests the driver to perform both
> disassociation and deauthentication in that order.
> It is also possible to do disassociation and then association, skipping
> the authentication step.
> 
> However, currently wpa_supplicant assumes that once it called
> wpa_drv_disassociate it can again start the complete connect sequence
> from the authentication.
> 
> In fact I have carefully studied the code and found that calls to
> wpa_supplicant_deauthenticate (which is the only user of
> wpa_drv_deauthenticate) only happen at deinitialization of wireless
> interface and when wpa_supplicant really has to do it, that is if there
> is a failure (mic failure for example).
> 
> My hacky patch that was rejected on the grounds that it is not right to
> introduce the driver dependent behavior might actually be the correct
> solution. It just makes the wpa_supplicant_disassociate do both
> disassociation and deauthentication, as was always assumed by the
> wpa_supplicant core.
> 
> 
> Or kernel should became smarter and do the work for wpa_supplicant. 
> 
> In this case it should work like that:
> 
> If mac80211 is already authenticated to the AP that was requested, it
> should just return success.
> However currently (and I was told that this is feature, not a bug)
> mac80211 would flatly refuse to do any scanning while it is in
> authenticated but not associated state.
> 
> If it isn't authenticated to new AP then, new authentication should be
> made.
> (and old one can be kept, but removed after a timeout)
> 
> 
> And the last question.
> When do you plan to switch officially the wpa_supplicant to
> driver_nl80211?
> 
> Currently it has this issue, and another issue that it (nl80211) reports
> signal levels in another format that NetworkManager doesn't understand.
> 
> Other that that it is faster, and especially it allows me to bring
> network up, when I press rfkill button within 4 seconds or less.
> 
> 
> Best regards,
> Maxim Levitsky
> 

Nobody uses driver_nl80211 but me?

Best regards,
Maxim Levitsky



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