mac80211: Extend SAE authentication in infra BSS STA mode

Previous implementation of SAE authentication in infrastructure BSS was
somewhat restricting and not exactly clean way of handling the two
auth() operations. This ended up removing and re-adding the STA entry
for the AP in the middle of authentication and also messing up
authentication state tracking through the sequence of four
Authentication frames. Furthermore, this did not work if the AP ended up
sending out SAE Confirm (auth trans #2) immediately after SAE Commit
(auth trans #1) before the station had time to transmit its SAE Confirm.

Clean up authentication state handling for the SAE case to allow two
rounds of auth() calls without dropping all state between those
operations. Track peer Confirmed status and mark authentication
completed only once both ends have confirmed.

ieee80211_mgd_auth() check for EBUSY cases is now handling only the
pending association (ifmgd->assoc_data) while all pending authentication
(ifmgd->auth_data) cases are allowed to proceed to allow user space to
start a new connection attempt from scratch even if the previously
requested authentication is still waiting completion. This is needed to
avoid making SAE error cases with retries take excessive amount of time
with no means for the user space to stop that (apart from setting the
netdev down).

As an extra bonus, the end of ieee80211_rx_mgmt_auth() can be cleaned up
to avoid the extra copy of the cfg80211_rx_mlme_mgmt() call for ongoing
SAE authentication since the new ieee80211_mark_sta_auth() helper
function can handle both completion of authentication and updates to the
STA entry under the same condition and there is no need to return from
the function between those operations.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/ieee80211_i.h

@@ -377,6 +377,7 @@ struct ieee80211_mgd_auth_data {
 	u8 key[WLAN_KEY_LEN_WEP104];
 	u8 key_len, key_idx;
 	bool done;
+	bool peer_confirmed;
 	bool timeout_started;
 
 	u16 sae_trans, sae_status;

net/mac80211/mlme.c

@@ -2764,8 +2764,15 @@ static void ieee80211_auth_challenge(struct ieee80211_sub_if_data *sdata,
 static bool ieee80211_mark_sta_auth(struct ieee80211_sub_if_data *sdata,
 				    const u8 *bssid)
 {
+	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
 	struct sta_info *sta;
 
+	sdata_info(sdata, "authenticated\n");
+	ifmgd->auth_data->done = true;
+	ifmgd->auth_data->timeout = jiffies + IEEE80211_AUTH_WAIT_ASSOC;
+	ifmgd->auth_data->timeout_started = true;
+	run_again(sdata, ifmgd->auth_data->timeout);
+
 	/* move station state to auth */
 	mutex_lock(&sdata->local->sta_mtx);
 	sta = sta_info_get(sdata, bssid);
@@ -2811,7 +2818,11 @@ static void ieee80211_rx_mgmt_auth(struct ieee80211_sub_if_data *sdata,
 	status_code = le16_to_cpu(mgmt->u.auth.status_code);
 
 	if (auth_alg != ifmgd->auth_data->algorithm ||
-	    auth_transaction != ifmgd->auth_data->expected_transaction) {
+	    (auth_alg != WLAN_AUTH_SAE &&
+	     auth_transaction != ifmgd->auth_data->expected_transaction) ||
+	    (auth_alg == WLAN_AUTH_SAE &&
+	     (auth_transaction < ifmgd->auth_data->expected_transaction ||
+	      auth_transaction > 2))) {
 		sdata_info(sdata, "%pM unexpected authentication state: alg %d (expected %d) transact %d (expected %d)\n",
 			   mgmt->sa, auth_alg, ifmgd->auth_data->algorithm,
 			   auth_transaction,
@@ -2854,25 +2865,17 @@ static void ieee80211_rx_mgmt_auth(struct ieee80211_sub_if_data *sdata,
 
 	event.u.mlme.status = MLME_SUCCESS;
 	drv_event_callback(sdata->local, sdata, &event);
-	sdata_info(sdata, "authenticated\n");
-	ifmgd->auth_data->done = true;
-	ifmgd->auth_data->timeout = jiffies + IEEE80211_AUTH_WAIT_ASSOC;
-	ifmgd->auth_data->timeout_started = true;
-	run_again(sdata, ifmgd->auth_data->timeout);
-
-	if (ifmgd->auth_data->algorithm == WLAN_AUTH_SAE &&
-	    ifmgd->auth_data->expected_transaction != 2) {
-		/*
-		 * Report auth frame to user space for processing since another
-		 * round of Authentication frames is still needed.
-		 */
-		cfg80211_rx_mlme_mgmt(sdata->dev, (u8 *)mgmt, len);
-		return;
+	if (ifmgd->auth_data->algorithm != WLAN_AUTH_SAE ||
+	    (auth_transaction == 2 &&
+	     ifmgd->auth_data->expected_transaction == 2)) {
+		if (!ieee80211_mark_sta_auth(sdata, bssid))
+			goto out_err;
+	} else if (ifmgd->auth_data->algorithm == WLAN_AUTH_SAE &&
+		   auth_transaction == 2) {
+		sdata_info(sdata, "SAE peer confirmed\n");
+		ifmgd->auth_data->peer_confirmed = true;
 	}
 
-	if (!ieee80211_mark_sta_auth(sdata, bssid))
-		goto out_err;
-
 	cfg80211_rx_mlme_mgmt(sdata->dev, (u8 *)mgmt, len);
 	return;
  out_err:
@@ -4888,6 +4891,7 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_mgd_auth_data *auth_data;
 	u16 auth_alg;
 	int err;
+	bool cont_auth;
 
 	/* prepare auth data structure */
 
@@ -4922,8 +4926,7 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 		return -EOPNOTSUPP;
 	}
 
-	if ((ifmgd->auth_data && !ifmgd->auth_data->done) ||
-	    ifmgd->assoc_data)
+	if (ifmgd->assoc_data)
 		return -EBUSY;
 
 	auth_data = kzalloc(sizeof(*auth_data) + req->auth_data_len +
@@ -4945,6 +4948,13 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 		auth_data->data_len += req->auth_data_len - 4;
 	}
 
+	/* Check if continuing authentication or trying to authenticate with the
+	 * same BSS that we were in the process of authenticating with and avoid
+	 * removal and re-addition of the STA entry in
+	 * ieee80211_prep_connection().
+	 */
+	cont_auth = ifmgd->auth_data && req->bss == ifmgd->auth_data->bss;
+
 	if (req->ie && req->ie_len) {
 		memcpy(&auth_data->data[auth_data->data_len],
 		       req->ie, req->ie_len);
@@ -4961,12 +4971,26 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 
 	/* try to authenticate/probe */
 
-	if (ifmgd->auth_data)
-		ieee80211_destroy_auth_data(sdata, false);
+	if (ifmgd->auth_data) {
+		if (cont_auth && req->auth_type == NL80211_AUTHTYPE_SAE) {
+			auth_data->peer_confirmed =
+				ifmgd->auth_data->peer_confirmed;
+		}
+		ieee80211_destroy_auth_data(sdata, cont_auth);
+	}
 
 	/* prep auth_data so we don't go into idle on disassoc */
 	ifmgd->auth_data = auth_data;
 
+	/* If this is continuation of an ongoing SAE authentication exchange
+	 * (i.e., request to send SAE Confirm) and the peer has already
+	 * confirmed, mark authentication completed since we are about to send
+	 * out SAE Confirm.
+	 */
+	if (cont_auth && req->auth_type == NL80211_AUTHTYPE_SAE &&
+	    auth_data->peer_confirmed && auth_data->sae_trans == 2)
+		ieee80211_mark_sta_auth(sdata, req->bss->bssid);
+
 	if (ifmgd->associated) {
 		u8 frame_buf[IEEE80211_DEAUTH_FRAME_LEN];
 
@@ -4984,7 +5008,7 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 
 	sdata_info(sdata, "authenticate with %pM\n", req->bss->bssid);
 
-	err = ieee80211_prep_connection(sdata, req->bss, false, false);
+	err = ieee80211_prep_connection(sdata, req->bss, cont_auth, false);
 	if (err)
 		goto err_clear;