Hi, I'm having problems connecting to wpa_supplicant/hostap running on linux from newer Android devices (Android 6.0 and above). The problem is that the newer Android devices encrypt (with rare exceptions) the message 4 of the WPA 4-way handshake. Such message is likely dropped by the linux kernel as it cannot be decrypted, in consequence the wpa_supplicant does not consider the handshake to be completed successfully and after a couple of re-sends of the message 3 it disassociates the Android device. I've logged a bug report with Fedora [1] where I included a patch providing a best effort solution which I don't consider to be suitable for inclusion in the wpa_supplicant as it is racy and as a consequence can be ineffective on slower hardware. The solution it provides is to install the PTK key as soon as the message 3 is sent by the wpa_supplicant, so that the message 4 can be decrypted if STA encrypts it. Additionally if there is a need to re-send the message 3, the key is uninstalled before the re-send and installed again afterwards (this is totally untested and may likely interfere with frame sequence numbers). Nevertheless in the happy case scenario (no retransmissions) it works. Further in the bug report I envision a better, race-free solution which would install the PTK even before sending the message 3 but despite that it would then send the message 3 (including its possible re-sends) unencrypted. The problem is I don't know how to achieve that: I don't see a way to send an unencrypted frame once the PTK is installed. I tend to think that a recent kernel patch [2] is supposed to address this exact issue. What's your opinion on the best effort solution provided in the patch? Would it make sense to include it the wpa_supplicant? Does the race-free solution make sense? (Is so could it be implemented by other means than those introduced in [2]? I.e. is there some other way to send an unencrypted frame once the PTK is installed?) Cheers, Michal [1] https://bugzilla.redhat.com/show_bug.cgi?id=1571256 [2] https://github.com/torvalds/linux/commit/2576a9ace47eba28a682d249d1d6402f891808c9 _______________________________________________ Hostap mailing list Hostap@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/hostap
