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

Wed Jun 26 00:47:56 PDT 2024

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

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