mesh: Add support for PMKSA caching

This patch add functionality of mesh SAE PMKSA caching. If the local STA
already has peer's PMKSA entry in the cache, skip SAE authentication and
start AMPE with the cached value.

If the peer does not support PMKSA caching or does not have the local
STA's PMKSA entry in the cache, AMPE will fail and the PMKSA cache entry
of the peer will be removed. Then STA retries with ordinary SAE
authentication.

If the peer does not support PMKSA caching and the local STA uses
no_auto_peer=1, the local STA can not retry SAE authentication because
NEW_PEER_CANDIDATE event cannot start SAE authentication when
no_auto_peer=1. So this patch extends MESH_PEER_ADD command to use
duration(sec). Throughout the duration, the local STA can start SAE
authentication triggered by NEW_PEER_CANDIDATE even though
no_auto_peer=1.

This commit requires commit 70c93963edefa37ef84b73efb9d04ea10268341c
('SAE: Fix PMKID calculation for PMKSA cache'). Without that commit,
chosen PMK comparison will fail.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>

src/ap/hostapd.h

@@ -262,6 +262,7 @@ struct hostapd_data {
 				 struct sta_info *sta);
 	struct wpabuf *mesh_pending_auth;
 	struct os_reltime mesh_pending_auth_time;
+	u8 mesh_required_peer[ETH_ALEN];
 #endif /* CONFIG_MESH */
 
 #ifdef CONFIG_SQLITE

src/ap/ieee802_11.c

@@ -554,6 +554,18 @@ static void sae_set_retransmit_timer(struct hostapd_data *hapd,
 }
 
 
+void sae_accept_sta(struct hostapd_data *hapd, struct sta_info *sta)
+{
+	sta->flags |= WLAN_STA_AUTH;
+	sta->auth_alg = WLAN_AUTH_SAE;
+	mlme_authenticate_indication(hapd, sta);
+	wpa_auth_sm_event(sta->wpa_sm, WPA_AUTH);
+	sta->sae->state = SAE_ACCEPTED;
+	wpa_auth_pmksa_add_sae(hapd->wpa_auth, sta->addr,
+			       sta->sae->pmk, sta->sae->pmkid);
+}
+
+
 static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
 		       const u8 *bssid, u8 auth_transaction)
 {
@@ -676,13 +688,7 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
 
 			sae_set_retransmit_timer(hapd, sta);
 		} else {
-			sta->flags |= WLAN_STA_AUTH;
-			sta->auth_alg = WLAN_AUTH_SAE;
-			mlme_authenticate_indication(hapd, sta);
-			wpa_auth_sm_event(sta->wpa_sm, WPA_AUTH);
-			sta->sae->state = SAE_ACCEPTED;
-			wpa_auth_pmksa_add_sae(hapd->wpa_auth, sta->addr,
-					       sta->sae->pmk, sta->sae->pmkid);
+			sae_accept_sta(hapd, sta);
 		}
 		break;
 	case SAE_ACCEPTED:
@@ -691,6 +697,7 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
 				   ") doing reauthentication",
 				   MAC2STR(sta->addr));
 			ap_free_sta(hapd, sta);
+			wpa_auth_pmksa_remove(hapd->wpa_auth, sta->addr);
 		} else {
 			if (sae_check_big_sync(sta))
 				return WLAN_STATUS_SUCCESS;
@@ -733,6 +740,13 @@ static void handle_auth_sae(struct hostapd_data *hapd, struct sta_info *sta,
 		sta->sae->sync = 0;
 	}
 
+	if (sta->mesh_sae_pmksa_caching) {
+		wpa_printf(MSG_DEBUG,
+			   "SAE: Cancel use of mesh PMKSA caching because peer starts SAE authentication");
+		wpa_auth_pmksa_remove(hapd->wpa_auth, sta->addr);
+		sta->mesh_sae_pmksa_caching = 0;
+	}
+
 	if (auth_transaction == 1) {
 		const u8 *token = NULL, *pos, *end;
 		size_t token_len = 0;

src/ap/ieee802_11.h

@@ -102,6 +102,7 @@ int auth_sae_init_committed(struct hostapd_data *hapd, struct sta_info *sta);
 #ifdef CONFIG_SAE
 void sae_clear_retransmit_timer(struct hostapd_data *hapd,
 				struct sta_info *sta);
+void sae_accept_sta(struct hostapd_data *hapd, struct sta_info *sta);
 #else /* CONFIG_SAE */
 static inline void sae_clear_retransmit_timer(struct hostapd_data *hapd,
 					      struct sta_info *sta)

src/ap/sta_info.h

@@ -183,6 +183,7 @@ struct sta_info {
 
 #ifdef CONFIG_SAE
 	struct sae_data *sae;
+	unsigned int mesh_sae_pmksa_caching:1;
 #endif /* CONFIG_SAE */
 
 	u32 session_timeout; /* valid only if session_timeout_set == 1 */

src/ap/wpa_auth.c

@@ -3375,6 +3375,34 @@ void wpa_auth_pmksa_flush(struct wpa_authenticator *wpa_auth)
 }
 
 
+struct rsn_pmksa_cache_entry *
+wpa_auth_pmksa_get(struct wpa_authenticator *wpa_auth, const u8 *sta_addr)
+{
+	if (!wpa_auth || !wpa_auth->pmksa)
+		return NULL;
+	return pmksa_cache_auth_get(wpa_auth->pmksa, sta_addr, NULL);
+}
+
+
+void wpa_auth_pmksa_set_to_sm(struct rsn_pmksa_cache_entry *pmksa,
+			      struct wpa_state_machine *sm,
+			      struct wpa_authenticator *wpa_auth,
+			      u8 *pmkid, u8 *pmk)
+{
+	if (!sm)
+		return;
+
+	sm->pmksa = pmksa;
+	if (sm->pmksa->pmk)
+		os_memcpy(pmk, sm->pmksa->pmk, PMK_LEN);
+	if (sm->pmksa->pmkid) {
+		os_memcpy(pmkid, sm->pmksa->pmkid, PMKID_LEN);
+		os_memcpy(wpa_auth->dot11RSNAPMKIDUsed,
+			  sm->pmksa->pmkid, PMKID_LEN);
+	}
+}
+
+
 /*
  * Remove and free the group from wpa_authenticator. This is triggered by a
  * callback to make sure nobody is currently iterating the group list while it

src/ap/wpa_auth.h

@@ -301,6 +301,12 @@ void wpa_auth_pmksa_remove(struct wpa_authenticator *wpa_auth,
 int wpa_auth_pmksa_list(struct wpa_authenticator *wpa_auth, char *buf,
 			size_t len);
 void wpa_auth_pmksa_flush(struct wpa_authenticator *wpa_auth);
+struct rsn_pmksa_cache_entry *
+wpa_auth_pmksa_get(struct wpa_authenticator *wpa_auth, const u8 *sta_addr);
+void wpa_auth_pmksa_set_to_sm(struct rsn_pmksa_cache_entry *pmksa,
+			      struct wpa_state_machine *sm,
+			      struct wpa_authenticator *wpa_auth,
+			      u8 *pmkid, u8 *pmk);
 int wpa_auth_sta_set_vlan(struct wpa_state_machine *sm, int vlan_id);
 void wpa_auth_eapol_key_tx_status(struct wpa_authenticator *wpa_auth,
 				  struct wpa_state_machine *sm, int ack);

wpa_supplicant/ctrl_iface.c

@@ -2744,11 +2744,21 @@ static int wpa_supplicant_ctrl_iface_mesh_peer_add(
 	struct wpa_supplicant *wpa_s, char *cmd)
 {
 	u8 addr[ETH_ALEN];
+	int duration;
+	char *pos;
+
+	pos = os_strstr(cmd, " duration=");
+	if (pos) {
+		*pos = '\0';
+		duration = atoi(pos + 10);
+	} else {
+		duration = -1;
+	}
 
 	if (hwaddr_aton(cmd, addr))
 		return -1;
 
-	return wpas_mesh_peer_add(wpa_s, addr);
+	return wpas_mesh_peer_add(wpa_s, addr, duration);
 }
 
 #endif /* CONFIG_MESH */

wpa_supplicant/mesh.c

@@ -605,7 +605,8 @@ int wpas_mesh_peer_remove(struct wpa_supplicant *wpa_s, const u8 *addr)
 }
 
 
-int wpas_mesh_peer_add(struct wpa_supplicant *wpa_s, const u8 *addr)
+int wpas_mesh_peer_add(struct wpa_supplicant *wpa_s, const u8 *addr,
+		       int duration)
 {
-	return mesh_mpm_connect_peer(wpa_s, addr);
+	return mesh_mpm_connect_peer(wpa_s, addr, duration);
 }

wpa_supplicant/mesh.h

@@ -19,7 +19,8 @@ int wpas_mesh_scan_result_text(const u8 *ies, size_t ies_len, char *buf,
 int wpas_mesh_add_interface(struct wpa_supplicant *wpa_s, char *ifname,
 			    size_t len);
 int wpas_mesh_peer_remove(struct wpa_supplicant *wpa_s, const u8 *addr);
-int wpas_mesh_peer_add(struct wpa_supplicant *wpa_s, const u8 *addr);
+int wpas_mesh_peer_add(struct wpa_supplicant *wpa_s, const u8 *addr,
+		       int duration);
 
 #ifdef CONFIG_MESH
 

wpa_supplicant/mesh_mpm.c

@@ -14,6 +14,7 @@
 #include "ap/hostapd.h"
 #include "ap/sta_info.h"
 #include "ap/ieee802_11.h"
+#include "ap/wpa_auth.h"
 #include "wpa_supplicant_i.h"
 #include "driver_i.h"
 #include "mesh_mpm.h"
@@ -419,6 +420,7 @@ static void plink_timer(void *eloop_ctx, void *user_data)
 	struct sta_info *sta = user_data;
 	u16 reason = 0;
 	struct mesh_conf *conf = wpa_s->ifmsh->mconf;
+	struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
 
 	switch (sta->plink_state) {
 	case PLINK_OPEN_RCVD:
@@ -448,6 +450,13 @@ static void plink_timer(void *eloop_ctx, void *user_data)
 		break;
 	case PLINK_HOLDING:
 		/* holding timer */
+
+		if (sta->mesh_sae_pmksa_caching) {
+			wpa_printf(MSG_DEBUG, "MPM: Peer " MACSTR
+				   " looks like it does not support mesh SAE PMKSA caching, so remove the cached entry for it",
+				   MAC2STR(sta->addr));
+			wpa_auth_pmksa_remove(hapd->wpa_auth, sta->addr);
+		}
 		mesh_mpm_fsm_restart(wpa_s, sta);
 		break;
 	default:
@@ -512,7 +521,17 @@ int mesh_mpm_close_peer(struct wpa_supplicant *wpa_s, const u8 *addr)
 }
 
 
-int mesh_mpm_connect_peer(struct wpa_supplicant *wpa_s, const u8 *addr)
+static void peer_add_timer(void *eloop_ctx, void *user_data)
+{
+	struct wpa_supplicant *wpa_s = eloop_ctx;
+	struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
+
+	os_memset(hapd->mesh_required_peer, 0, ETH_ALEN);
+}
+
+
+int mesh_mpm_connect_peer(struct wpa_supplicant *wpa_s, const u8 *addr,
+			  int duration)
 {
 	struct wpa_ssid *ssid = wpa_s->current_ssid;
 	struct hostapd_data *hapd;
@@ -547,10 +566,14 @@ int mesh_mpm_connect_peer(struct wpa_supplicant *wpa_s, const u8 *addr)
 		return -1;
 	}
 
-	if (conf->security == MESH_CONF_SEC_NONE)
+	if (conf->security == MESH_CONF_SEC_NONE) {
 		mesh_mpm_plink_open(wpa_s, sta, PLINK_OPEN_SENT);
-	else
+	} else {
 		mesh_rsn_auth_sae_sta(wpa_s, sta);
+		os_memcpy(hapd->mesh_required_peer, addr, ETH_ALEN);
+		eloop_register_timeout(duration == -1 ? 10 : duration, 0,
+				       peer_add_timer, wpa_s, NULL);
+	}
 
 	return 0;
 }
@@ -565,6 +588,7 @@ void mesh_mpm_deinit(struct wpa_supplicant *wpa_s, struct hostapd_iface *ifmsh)
 
 	hapd->num_plinks = 0;
 	hostapd_free_stas(hapd);
+	eloop_cancel_timeout(peer_add_timer, wpa_s, NULL);
 }
 
 
@@ -705,7 +729,9 @@ void wpa_mesh_new_mesh_peer(struct wpa_supplicant *wpa_s, const u8 *addr,
 	if (!sta)
 		return;
 
-	if (ssid && ssid->no_auto_peer) {
+	if (ssid && ssid->no_auto_peer &&
+	    (is_zero_ether_addr(data->mesh_required_peer) ||
+	     os_memcmp(data->mesh_required_peer, addr, ETH_ALEN) != 0)) {
 		wpa_msg(wpa_s, MSG_INFO, "will not initiate new peer link with "
 			MACSTR " because of no_auto_peer", MAC2STR(addr));
 		if (data->mesh_pending_auth) {
@@ -785,7 +811,10 @@ static void mesh_mpm_plink_estab(struct wpa_supplicant *wpa_s,
 	hapd->num_plinks++;
 
 	sta->flags |= WLAN_STA_ASSOC;
+	sta->mesh_sae_pmksa_caching = 0;
 
+	eloop_cancel_timeout(peer_add_timer, wpa_s, NULL);
+	peer_add_timer(wpa_s, NULL);
 	eloop_cancel_timeout(plink_timer, wpa_s, sta);
 
 	/* Send ctrl event */
@@ -1065,7 +1094,8 @@ void mesh_mpm_action_rx(struct wpa_supplicant *wpa_s,
 	 * open mesh, then go ahead and add the peer before proceeding.
 	 */
 	if (!sta && action_field == PLINK_OPEN &&
-	    !(mconf->security & MESH_CONF_SEC_AMPE))
+	    (!(mconf->security & MESH_CONF_SEC_AMPE) ||
+	     wpa_auth_pmksa_get(hapd->wpa_auth, mgmt->sa)))
 		sta = mesh_mpm_add_peer(wpa_s, mgmt->sa, &elems);
 
 	if (!sta) {

wpa_supplicant/mesh_mpm.h

@@ -19,7 +19,8 @@ void wpa_mesh_set_plink_state(struct wpa_supplicant *wpa_s,
 			      struct sta_info *sta,
 			      enum mesh_plink_state state);
 int mesh_mpm_close_peer(struct wpa_supplicant *wpa_s, const u8 *addr);
-int mesh_mpm_connect_peer(struct wpa_supplicant *wpa_s, const u8 *addr);
+int mesh_mpm_connect_peer(struct wpa_supplicant *wpa_s, const u8 *addr,
+			  int duration);
 
 #ifdef CONFIG_MESH
 

wpa_supplicant/mesh_rsn.c

@@ -291,6 +291,7 @@ int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s,
 {
 	struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
 	struct wpa_ssid *ssid = wpa_s->current_ssid;
+	struct rsn_pmksa_cache_entry *pmksa;
 	unsigned int rnd;
 	int ret;
 
@@ -306,6 +307,29 @@ int mesh_rsn_auth_sae_sta(struct wpa_supplicant *wpa_s,
 			return -1;
 	}
 
+	pmksa = wpa_auth_pmksa_get(hapd->wpa_auth, sta->addr);
+	if (pmksa) {
+		if (!sta->wpa_sm)
+			sta->wpa_sm = wpa_auth_sta_init(hapd->wpa_auth,
+							sta->addr, NULL);
+		if (!sta->wpa_sm) {
+			wpa_printf(MSG_ERROR,
+				   "mesh: Failed to initialize RSN state machine");
+			return -1;
+		}
+
+		wpa_printf(MSG_DEBUG,
+			   "AUTH: Mesh PMKSA cache entry found for " MACSTR
+			   " - try to use PMKSA caching instead of new SAE authentication",
+			   MAC2STR(sta->addr));
+		wpa_auth_pmksa_set_to_sm(pmksa, sta->wpa_sm, hapd->wpa_auth,
+					 sta->sae->pmkid, sta->sae->pmk);
+		sae_accept_sta(hapd, sta);
+		sta->mesh_sae_pmksa_caching = 1;
+		return 0;
+	}
+	sta->mesh_sae_pmksa_caching = 0;
+
 	if (mesh_rsn_build_sae_commit(wpa_s, ssid, sta))
 		return -1;
 
@@ -514,6 +538,17 @@ int mesh_rsn_process_ampe(struct wpa_supplicant *wpa_s, struct sta_info *sta,
 	const size_t aad_len[] = { ETH_ALEN, ETH_ALEN,
 				   (elems->mic - 2) - cat };
 
+	if (!sta->sae) {
+		struct hostapd_data *hapd = wpa_s->ifmsh->bss[0];
+
+		if (!wpa_auth_pmksa_get(hapd->wpa_auth, sta->addr)) {
+			wpa_printf(MSG_INFO,
+				   "Mesh RSN: SAE is not prepared yet");
+			return -1;
+		}
+		mesh_rsn_auth_sae_sta(wpa_s, sta);
+	}
+
 	if (chosen_pmk && os_memcmp(chosen_pmk, sta->sae->pmkid, PMKID_LEN)) {
 		wpa_msg(wpa_s, MSG_DEBUG,
 			"Mesh RSN: Invalid PMKID (Chosen PMK did not match calculated PMKID)");

wpa_supplicant/wpa_cli.c

@@ -3229,7 +3229,7 @@ static const struct wpa_cli_cmd wpa_cli_commands[] = {
 	  "<addr> = Remove a mesh peer" },
 	{ "mesh_peer_add", wpa_cli_cmd_mesh_peer_add, NULL,
 	  cli_cmd_flag_none,
-	  "<addr> = Add a mesh peer" },
+	  "<addr> [duration=<seconds>] = Add a mesh peer" },
 #endif /* CONFIG_MESH */
 #ifdef CONFIG_P2P
 	{ "p2p_find", wpa_cli_cmd_p2p_find, wpa_cli_complete_p2p_find,