[PATCH v3 0/3] FT: RSNXE Used without the RSNXE

[Koral Ilgun]

From: Koral Ilgun <koral.ilgun at adtran.com>

The RSNXE Used subfield of the FTE MIC Control field tells the STA that
the AP uses the RSNXE, and a STA on the base RSNE checks it against the
Beacon and Probe Response frames.

Patch 1 stops the AP from setting the bit for a STA on the base RSNE
when it advertises no base RSNXE. That happens with
rsn_override_omit_rsnxe=1, and in WPA3-Personal Compatibility Mode,
where the base RSNE has no SAE AKM. wpa_supplicant then rejected every
FT Reassociation Response of such a STA. A STA that selected RSN
Overriding gets the bit as before.

Patch 2 adds an opt-in interoperability workaround,
ft_rsnxe_used_only_with_rsnxe, default 0, for STAs that check the bit
against the response itself: an iPad that uses SAE without H2E
discards a response with RSNXE Used set and no RSNXE, and FT never
completes.

Patch 3 adds hwsim tests for both.

This complements the series "FT: Support 802.11r with WPA3-Personal
Compatibility Mode" by Gopi Raga
(https://patchwork.ozlabs.org/project/hostap/list/?series=514064),
which handles a STA that uses RSN Overriding. Both series apply
together.

v3:
- v2 patch 1 cleared RSNXE Used for every STA when
  rsn_override_omit_rsnxe=1, which also removed the bit for a STA with
  RSN Overriding. Patch 1 now changes only a STA on the base RSNE, and
  also covers Compatibility Mode without rsn_override_omit_rsnxe.
- Patch 3: two tests with a Compatibility Mode AP and a STA without RSN
  Overriding replace test_ap_ft_sae_omit_rsnxe.
v2: https://patchwork.ozlabs.org/project/hostap/patch/20261029163257.1436843-2-koralilgun@gmail.com/

Testing: hostapd and wpa_supplicant build without warnings. hwsim
under UML: the ap_ft and rsn_override modules pass, 175 tests on main
and 179 with this series; with Gopi Raga's series on top, 181 pass. On
main with only patch 3 applied, both new Compatibility Mode tests fail
with "FTE indicated that AP uses RSNXE, but RSNXE was not included in
Beacon/Probe Response frames".

Koral Ilgun (3):
  FT: Do not set RSNXE Used for a base RSNE STA without the RSNXE
  FT: Add ft_rsnxe_used_only_with_rsnxe interoperability workaround
  tests: FT RSNXE Used without RSNXE in Beacon or request

 hostapd/config_file.c     |  2 +
 hostapd/hostapd.conf      | 11 ++++++
 src/ap/ap_config.h        |  3 ++
 src/ap/wpa_auth.h         |  1 +
 src/ap/wpa_auth_ft.c      | 16 +++++++-
 src/ap/wpa_auth_glue.c    |  2 +
 tests/hwsim/test_ap_ft.py | 80 ++++++++++++++++++++++++++++++++++++++-
 7 files changed, 113 insertions(+), 2 deletions(-)


base-commit: ee5021e41b83060d69115ed91b66485f2fc888e0
-- 
2.43.0