[PATCH 1/1] hostapd: Allow roam from OWE transition to OWE only AP

[Jouni Malinen]

On Fri, Dec 13, 2024 at 02:15:27PM +0530, Vinayak Yadawad wrote:
> Currently STA roam works fine in case of OWE only AP to
> OWE-transition mode AP. The roam fails when STA is connected
> in OWE mode with OWE transition AP to an OWE only AP. In the
> OWE transition case, the current_ssid stores only open network
> SSID, specific check is required to compare the OWE BSS ssid
> from the previous target and new target.

The change in owe_trans_ssid() is a clear fix to a recent regression, so
I applied that separately. As far as the changes in
wpa_supplicant_select_config() are concerned, I'm not completely sure I
understood them since the comment about the added OWE transition mode AP
to OWE-only AP comparison of the SSID does not seem to match what I
would have expected from the actual memcmp(). The SSID of the previous
BSS (i.e., the transition mode AP) is a random value that does not match
the network profile whereas the SSID of the selected BSS (i.e., OWE-only
AP) is the SSID of the network profile. Those are different and as such,
the new memcmp() == 0 case would not be met..

Would you be able to share a debug log showing what fails without this
patch?

I did some cleanup while reviewing and trying to understand this and
this is what I came up with while still not fully understanding what
this trying to do:

From: Vinayak Yadawad <vinayak.yadawad at broadcom.com>
Date: Fri, 13 Dec 2024 14:15:27 +0530
Subject: [PATCH] OWE: Allow roam from OWE transition mode AP to OWE-only AP

Currently STA roam works fine in case of OWE only AP to
OWE-transition mode AP. The roam fails when STA is connected
in OWE mode with OWE transition AP to an OWE only AP. In the
OWE transition case, the current_ssid stores only open network
SSID, specific check is required to compare the OWE BSS ssid
from the previous target and new target.

Signed-off-by: Vinayak Yadawad <vinayak.yadawad at broadcom.com>
---
 wpa_supplicant/events.c | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

diff --git a/wpa_supplicant/events.c b/wpa_supplicant/events.c
index 279838afa2bf..e7285fcb5cea 100644
--- a/wpa_supplicant/events.c
+++ b/wpa_supplicant/events.c
@@ -226,6 +226,15 @@ static int wpa_supplicant_select_config(struct wpa_supplicant *wpa_s,
 	int res;
 
 	if (wpa_s->conf->ap_scan == 1 && wpa_s->current_ssid) {
+#ifdef CONFIG_OWE
+		struct wpa_bss *prev_bss;
+
+		/* Remember the current BSS entry before update to a new one to
+		 * allow appropriate comparison in OWE transition mode cases
+		 * below. */
+		prev_bss = wpa_s->current_bss;
+#endif /* CONFIG_OWE */
+
 		wpa_supplicant_update_current_bss(wpa_s, wpa_s->bssid);
 
 		if (wpa_s->current_ssid->ssid_len == 0)
@@ -245,12 +254,29 @@ static int wpa_supplicant_select_config(struct wpa_supplicant *wpa_s,
 
 #ifdef CONFIG_OWE
 		if ((wpa_s->current_ssid->key_mgmt & WPA_KEY_MGMT_OWE) &&
-		    wpa_s->current_bss &&
-		    (wpa_s->current_bss->flags & WPA_BSS_OWE_TRANSITION) &&
-		    drv_ssid_len == wpa_s->current_bss->ssid_len &&
-		    os_memcmp(drv_ssid, wpa_s->current_bss->ssid,
-			      drv_ssid_len) == 0)
-			return 0; /* current profile still in use */
+		    wpa_s->current_bss) {
+			/* Handle the case where the selected BSS uses OWE
+			 * transition mode */
+			if ((wpa_s->current_bss->flags &
+			     WPA_BSS_OWE_TRANSITION) &&
+			    drv_ssid_len == wpa_s->current_bss->ssid_len &&
+			    os_memcmp(drv_ssid, wpa_s->current_bss->ssid,
+				      drv_ssid_len) == 0)
+				return 0; /* current profile still in use */
+
+			/* Handle the case where the selected BSS uses OWE-only
+			 * mode and the previous one uses OWE transition mode.
+			 * The connected SSID would be that of the OWE network
+			 * where as current_ssid stores the open network SSID.
+			 */
+			if (prev_bss &&
+			    (prev_bss->flags & WPA_BSS_OWE_TRANSITION) &&
+			    (prev_bss->ssid_len ==
+			     wpa_s->current_bss->ssid_len) &&
+			    os_memcmp(prev_bss->ssid, wpa_s->current_bss->ssid,
+				      wpa_s->current_bss->ssid_len) == 0)
+				return 0; /* current profile still in use */
+		}
 #endif /* CONFIG_OWE */
 
 		wpa_msg(wpa_s, MSG_DEBUG,
-- 
2.43.0

-- 
Jouni Malinen                                            PGP id EFC895FA