[PATCH 2/2] SAE: implement retransmission timer
Bob Copeland
me at bobcopeland.com
Wed Jan 7 01:10:57 EST 2015
Add the t0 retransmission timer as specified by 802.11-2012 11.3.8.4.
This makes SAE much more likely to succeed in the case of lost frames.
Signed-off-by: Bob Copeland <me at bobcopeland.com>
---
src/ap/ieee802_11.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
src/common/sae.h | 1 +
2 files changed, 83 insertions(+), 1 deletion(-)
diff --git a/src/ap/ieee802_11.c b/src/ap/ieee802_11.c
index 015cfe0..f896bdc 100644
--- a/src/ap/ieee802_11.c
+++ b/src/ap/ieee802_11.c
@@ -328,6 +328,10 @@ static void handle_auth_ft_finish(void *ctx, const u8 *dst, const u8 *bssid,
#ifdef CONFIG_SAE
+#define dot11RSNASAERetransPeriod 40 /* msec */
+#define dot11RSNASAESync 5 /* attempts */
+
+
static struct wpabuf * auth_build_sae_commit(struct hostapd_data *hapd,
struct sta_info *sta, int update)
{
@@ -483,6 +487,43 @@ static struct wpabuf * auth_build_token_req(struct hostapd_data *hapd,
}
+static int sae_check_big_sync(struct sta_info *sta)
+{
+ if (sta->sae->sync > dot11RSNASAESync) {
+ sta->sae->state = SAE_NOTHING;
+ sta->sae->sync = 0;
+ return -1;
+ }
+ return 0;
+}
+
+
+static void auth_sae_retransmit_timer(void *eloop_ctx, void *eloop_data)
+{
+ struct hostapd_data *hapd = eloop_ctx;
+ struct sta_info *sta = eloop_data;
+
+ if (sae_check_big_sync(sta))
+ return;
+ sta->sae->sync++;
+
+ switch (sta->sae->state) {
+ case SAE_COMMITTED:
+ auth_sae_send_commit(hapd, sta, hapd->own_addr, 0);
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer, hapd, sta);
+ break;
+ case SAE_CONFIRMED:
+ auth_sae_send_confirm(hapd, sta, hapd->own_addr);
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer, hapd, sta);
+ break;
+ default:
+ break;
+ }
+}
+
+
static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
const u8 *bssid, u8 auth_transaction)
{
@@ -530,6 +571,10 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
* when receiving Confirm from STA.
*/
}
+ sta->sae->sync = 0;
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer,
+ hapd, sta);
} else {
hostapd_logger(hapd, sta->addr,
HOSTAPD_MODULE_IEEE80211,
@@ -538,6 +583,7 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
}
break;
case SAE_COMMITTED:
+ eloop_cancel_timeout(auth_sae_retransmit_timer, hapd, sta);
if (auth_transaction == 1) {
if (sae_process_commit(sta->sae) < 0)
return WLAN_STATUS_UNSPECIFIED_FAILURE;
@@ -546,14 +592,26 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
if (ret)
return ret;
sta->sae->state = SAE_CONFIRMED;
+ sta->sae->sync = 0;
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer,
+ hapd, sta);
} else if (hapd->conf->mesh & MESH_ENABLED) {
/*
* In mesh case, follow SAE finite state machine and
- * send Commit now.
+ * send Commit now, if sync count allows.
*/
+ if (sae_check_big_sync(sta))
+ return WLAN_STATUS_SUCCESS;
+ sta->sae->sync++;
+
ret = auth_sae_send_commit(hapd, sta, bssid, 1);
if (ret)
return ret;
+
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer,
+ hapd, sta);
} else {
/*
* For instructure BSS, send the postponed Confirm from
@@ -575,7 +633,12 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
}
break;
case SAE_CONFIRMED:
+ eloop_cancel_timeout(auth_sae_retransmit_timer, hapd, sta);
if (auth_transaction == 1) {
+ if (sae_check_big_sync(sta))
+ return WLAN_STATUS_SUCCESS;
+ sta->sae->sync++;
+
ret = auth_sae_send_commit(hapd, sta, bssid, 1);
if (ret)
return ret;
@@ -586,6 +649,10 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
ret = auth_sae_send_confirm(hapd, sta, bssid);
if (ret)
return ret;
+
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer,
+ hapd, sta);
} else {
sta->flags |= WLAN_STA_AUTH;
sta->auth_alg = WLAN_AUTH_SAE;
@@ -603,6 +670,10 @@ static int sae_sm_step(struct hostapd_data *hapd, struct sta_info *sta,
MAC2STR(sta->addr));
ap_free_sta(hapd, sta);
} else {
+ if (sae_check_big_sync(sta))
+ return WLAN_STATUS_SUCCESS;
+ sta->sae->sync++;
+
ret = auth_sae_send_confirm(hapd, sta, bssid);
sae_clear_temp_data(sta->sae);
if (ret)
@@ -632,6 +703,7 @@ static void handle_auth_sae(struct hostapd_data *hapd, struct sta_info *sta,
if (sta->sae == NULL)
return;
sta->sae->state = SAE_NOTHING;
+ sta->sae->sync = 0;
}
if (auth_transaction == 1) {
@@ -685,6 +757,12 @@ static void handle_auth_sae(struct hostapd_data *hapd, struct sta_info *sta,
return;
}
sta->sae->state = SAE_COMMITTED;
+ eloop_cancel_timeout(auth_sae_retransmit_timer,
+ hapd, sta);
+ sta->sae->sync = 0;
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer,
+ hapd, sta);
return;
}
@@ -782,6 +860,9 @@ int auth_sae_init_committed(struct hostapd_data *hapd, struct sta_info *sta)
return -1;
sta->sae->state = SAE_COMMITTED;
+ sta->sae->sync = 0;
+ eloop_register_timeout(0, dot11RSNASAERetransPeriod * 1000,
+ auth_sae_retransmit_timer, hapd, sta);
return 0;
}
diff --git a/src/common/sae.h b/src/common/sae.h
index 89d74ab..3ebf40c 100644
--- a/src/common/sae.h
+++ b/src/common/sae.h
@@ -44,6 +44,7 @@ struct sae_data {
u8 pmk[SAE_PMK_LEN];
struct crypto_bignum *peer_commit_scalar;
int group;
+ int sync;
struct sae_temporary_data *tmp;
};
--
2.1.4
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