brcmfmac: how to setup SAE on RPi // Re: [PATCH] wifi: brcmsmac: advertise MFP_CAPABLE to enable WPA3

[KeithG]

On Wed, Jun 26, 2024 at 7:30 AM Arend Van Spriel
<arend.vanspriel at broadcom.com> wrote:
>
> On June 26, 2024 2:05:07 PM KeithG <ys3al35l at gmail.com> wrote:
>
> > On Wed, Jun 26, 2024 at 2:48 AM Arend Van Spriel
> > <arend.vanspriel at broadcom.com> wrote:
> >>
> >> On June 21, 2024 2:24:19 PM KeithG <ys3al35l at gmail.com> wrote:
> >>
> >>> On Fri, Jun 21, 2024 at 4:09 AM Arend van Spriel
> >>> <arend.vanspriel at broadcom.com> wrote:
> >>>>
> >>>> + Jouni
> >>>>
> >>>> On 6/20/2024 8:25 PM, KeithG wrote:
> >>>>> 1718907734.308740: wlan0: WPA: AP group 0x10 network profile group
> >>>>> 0x18; available group 0x10
> >>>>> 1718907734.308748: wlan0: WPA: using GTK CCMP
> >>>>> 1718907734.308758: wlan0: WPA: AP pairwise 0x10 network profile
> >>>>> pairwise 0x10; available pairwise 0x10
> >>>>> 1718907734.308767: wlan0: WPA: using PTK CCMP
> >>>>> 1718907734.308772: wlan0: WPA: AP key_mgmt 0x400 network profile
> >>>>> key_mgmt 0x400; available key_mgmt 0x0
> >>>>
> >>>>
> >>>> I suspect the message above indicates the problem as there is no
> >>>> available key_mgmt to select so looked it up in the code and here it is:
> >>>>
> >>>> sel = ie.key_mgmt & ssid->key_mgmt;
> >>>> #ifdef CONFIG_SAE
> >>>> if ((!(wpa_s->drv_flags & WPA_DRIVER_FLAGS_SAE) &&
> >>>> !(wpa_s->drv_flags2 & WPA_DRIVER_FLAGS2_SAE_OFFLOAD_STA)) ||
> >>>> wpas_is_sae_avoided(wpa_s, ssid, &ie))
> >>>> sel &= ~(WPA_KEY_MGMT_SAE | WPA_KEY_MGMT_SAE_EXT_KEY |
> >>>>    WPA_KEY_MGMT_FT_SAE |
> >>>> WPA_KEY_MGMT_FT_SAE_EXT_KEY);
> >>>> #endif /* CONFIG_SAE */
> >>>> #ifdef CONFIG_IEEE80211R
> >>>> if (!(wpa_s->drv_flags & (WPA_DRIVER_FLAGS_SME |
> >>>>             WPA_DRIVER_FLAGS_UPDATE_FT_IES)))
> >>>> sel &= ~WPA_KEY_MGMT_FT;
> >>>> #endif /* CONFIG_IEEE80211R */
> >>>> wpa_dbg(wpa_s, MSG_DEBUG,
> >>>> "WPA: AP key_mgmt 0x%x network profile key_mgmt 0x%x;
> >>>> available key_mgmt 0x%x",
> >>>> ie.key_mgmt, ssid->key_mgmt, sel);
> >>>>
> >>>> So 0x400 matches the expectation:
> >>>>
> >>>> #define WPA_KEY_MGMT_SAE BIT(10)
> >>>>
> >>>> You already confirmed that the driver reports SAE and SAE offload
> >>>> support. So it seems wpas_is_sae_avoided() must return true. That will
> >>>> check whether the AP and network profile are setup to MFP. This seems to
> >>>> be the fact as your hostapd.conf and wpa_supplicant.conf both have
> >>>> ieee80211w=2 defined. This function can only return true when
> >>>> is enabled in configuration file:
> >>>>
> >>>> # sae_check_mfp: Require PMF support to select SAE key_mgmt
> >>>> # 0 = Do not check PMF for SAE (default)
> >>>> # 1 = Limit SAE when PMF is not enabled
> >>>> #
> >>>> # When enabled SAE will not be selected if PMF will not be used
> >>>> # for the connection.
> >>>> # Scenarios where this check will limit SAE:
> >>>> #  1) ieee80211w=0 is set for the network
> >>>> #  2) The AP does not have PMF enabled.
> >>>> #  3) ieee80211w is unset, pmf=1 is enabled globally, and
> >>>> #     the device does not support the BIP cipher.
> >>>> # Consider the configuration of global parameterss sae_check_mfp=1,
> >>>> pmf=1 and a
> >>>> # network configured with ieee80211w unset and key_mgmt=SAE WPA-PSK.
> >>>> # In the example WPA-PSK will be used if the device does not support
> >>>> # the BIP cipher or the AP has PMF disabled.
> >>>> # Limiting SAE with this check can avoid failing to associate to an AP
> >>>> # that is configured with sae_requires_mfp=1 if the device does
> >>>> # not support PMF due to lack of the BIP cipher.
> >>>>
> >>>> The default is not to check it and you wpa_supplicant.conf does not
> >>>> specify it.
> >>>>
> >>>> # cat /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
> >>>> ctrl_interface=DIR=/run/wpa_supplicant GROUP=netdev
> >>>> update_config=1
> >>>> network={
> >>>> ssid="deskSAE"
> >>>> sae_password="secret123"
> >>>> proto=RSN
> >>>> key_mgmt=SAE
> >>>> pairwise=CCMP
> >>>> ieee80211w=2
> >>>> }
> >>>>
> >>>> $ cat /etc/hostapd/hostapd.conf
> >>>> # interface and driver
> >>>> interface=ap0
> >>>> driver=nl80211
> >>>>
> >>>> # WIFI-Config
> >>>> ssid=deskSAE
> >>>> channel=1
> >>>> hw_mode=g
> >>>>
> >>>> wpa=2
> >>>> wpa_key_mgmt=SAE
> >>>> wpa_pairwise=CCMP
> >>>> sae_password=secret123
> >>>> sae_groups=19
> >>>> ieee80211w=2
> >>>> sae_pwe=0
> >>>>
> >>>> Regards,
> >>>> Arend
> >>>>
> >>>>
> >>>>> 1718907734.308779: wlan0: WPA: Failed to select authenticated key
> >>>>> management type
> >>>>> 1718907734.308787: wlan0: WPA: Failed to set WPA key management and
> >>>>> encryption suites
> >>>
> >>> Arend,
> >>>
> >>> I find the wpa_supplicant docs really hard to understand. I have read
> >>> through your response a few times and am still a bit confused. Does
> >>> this have to do with a pure wpa3 versus a wpa2/3 AP?
> >>
> >> Correct. If I am not mistaken MFP aka PMF aka 802.11w is mandatory for WPA3.
> >>
> >>> I have tried editing my hostapd.conf and my wpa_supplicant.conf and
> >>> still cannot get a connection, so I must be doing something wrong.
> >>> I commented the ieee80211w line on both and it would not connect.
> >>> I tried changing the wpa_key_mgmt on both ends to be 'SAE WPA_PSK' and
> >>> it still would not connect.
> >>>
> >>> What *should* the configurations be in the hostapd.conf and
> >>> wpa_supplicant.conf to negotiate this as a pure wpa3 setup? What
> >>> should it be to be a wpa2/3 setup? My phone worked fine to connect
> >>> with the original hostapd setup, but I have no idea what it is doing
> >>
> >> As I mentioned in my previous email both config files listed above look
> >> okay to me (might be wrong though). The problem seems to be with
> >> wpas_is_sae_avoided(). For it to return true the config should have:
> >>
> >> sae_check_mfp=1
> >>
> >> But you don't have that and default is 0 so it should check for MFP. This
> >> is where my trail ends. To learn more I would add additional debug prints.
> >> Are you comfortable rebuilding wpa_supplicant from source?
> >>
> >> Regards,
> >> Arend
> >
> > Arend,
> >
> > Thanks for the reply. I could try to rebuild wpa_supplicant from
> > source. This is on RPi, so debian *.debs which are a pain, but I think
> > I can do it.
> >
> > Do I understand correctly that 'sae_check_mfp=1' is supposed to be in
> > the hostapd.conf and wpa_supplicant.conf? I can try that and see if
> > anything changes.
>
> Ok. We can try first to put following in wpa_supplicant.conf:
>
> sae_check_mfp=0
>
> Let me know if that makes any difference.
>
> > Why would I have to re-build wpa_supplicant?
>
> I would provide a patch with additional debug prints so I get better
> understanding what is going wrong. Would be great if you can apply that and
> rebuild.
>
> Regards,
> Arend
>
>
Arend,

I was able to try it this afternoon.
My hostapd is still:
# interface and driver
interface=ap0
driver=nl80211

# WIFI-Config
ssid=deskSAE
channel=1
hw_mode=g

wpa=2
wpa_key_mgmt=SAE
wpa_pairwise=CCMP
sae_password=secret123
sae_groups=19
ieee80211w=2
sae_pwe=0

and I can still connect from my phone to this AP.

I tried this as my /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
ctrl_interface=DIR=/run/wpa_supplicant GROUP=netdev
update_config=1
 network={
  ssid="deskSAE"
  sae_password="secret123"
  proto=RSN
  key_mgmt=SAE
  pairwise=CCMP
  ieee80211w=2
  sae_check_mfp=1
}

and when I try to connect, I get:
# wpa_supplicant -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant-wlan0.conf
Successfully initialized wpa_supplicant
Line 10: unknown network field 'sae_check_mfp'.
Line 11: failed to parse network block.
Failed to read or parse configuration
'/etc/wpa_supplicant/wpa_supplicant-wlan0.conf'.
: CTRL-EVENT-DSCP-POLICY clear_all

my version of wpa_supplicant is
# wpa_supplicant -v
wpa_supplicant v2.10
Copyright (c) 2003-2022, Jouni Malinen <j at w1.fi> and contributors

I will build the latest from git and await your patch.

Keith