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AP: Save EAPOL received before Association Response ACK

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There is a race condition in which AP might receive the EAPOL-Start
frame (from the just-associated station) before the TX completion of the
Association Response frame. This in turn will cause the EAPOL-Start
frame to get dropped, and potentially failing the connection.

Solve this by saving EAPOL frames from authenticated-but-not-associated
stations, and handling them during the Association Response frame TX
completion processing.

Signed-off-by: Eliad Peller <eliad@wizery.com>
This commit is contained in:
Eliad Peller 2016-03-06 11:29:16 +02:00 committed by Jouni Malinen
parent c0ca24fc30
commit f2accfe708
3 changed files with 62 additions and 0 deletions
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19
src/ap/ieee802_11.c
View file

@ -2782,6 +2782,25 @@ static void handle_assoc_cb(struct hostapd_data *hapd,
wpa_auth_sm_event(sta->wpa_sm, WPA_ASSOC);
hapd->new_assoc_sta_cb(hapd, sta, !new_assoc);
ieee802_1x_notify_port_enabled(sta->eapol_sm, 1);
if (sta->pending_eapol_rx) {
struct os_reltime now, age;
os_get_reltime(&now);
os_reltime_sub(&now, &sta->pending_eapol_rx->rx_time, &age);
if (age.sec == 0 && age.usec < 200000) {
wpa_printf(MSG_DEBUG,
"Process pending EAPOL frame that was received from " MACSTR " just before association notification",
MAC2STR(sta->addr));
ieee802_1x_receive(
hapd, mgmt->da,
wpabuf_head(sta->pending_eapol_rx->buf),
wpabuf_len(sta->pending_eapol_rx->buf));
}
wpabuf_free(sta->pending_eapol_rx->buf);
os_free(sta->pending_eapol_rx);
sta->pending_eapol_rx = NULL;
}
}

36
src/ap/ieee802_1x.c
View file

@ -861,6 +861,29 @@ ieee802_1x_alloc_eapol_sm(struct hostapd_data *hapd, struct sta_info *sta)
}
static void ieee802_1x_save_eapol(struct sta_info *sta, const u8 *buf,
size_t len)
{
if (sta->pending_eapol_rx) {
wpabuf_free(sta->pending_eapol_rx->buf);
} else {
sta->pending_eapol_rx =
os_malloc(sizeof(*sta->pending_eapol_rx));
if (!sta->pending_eapol_rx)
return;
}
sta->pending_eapol_rx->buf = wpabuf_alloc_copy(buf, len);
if (!sta->pending_eapol_rx->buf) {
os_free(sta->pending_eapol_rx);
sta->pending_eapol_rx = NULL;
return;
}
os_get_reltime(&sta->pending_eapol_rx->rx_time);
}
/**
* ieee802_1x_receive - Process the EAPOL frames from the Supplicant
* @hapd: hostapd BSS data
@ -891,6 +914,13 @@ void ieee802_1x_receive(struct hostapd_data *hapd, const u8 *sa, const u8 *buf,
!(hapd->iface->drv_flags & WPA_DRIVER_FLAGS_WIRED))) {
wpa_printf(MSG_DEBUG, "IEEE 802.1X data frame from not "
"associated/Pre-authenticating STA");
if (sta && (sta->flags & WLAN_STA_AUTH)) {
wpa_printf(MSG_DEBUG, "Saving EAPOL frame from " MACSTR
" for later use", MAC2STR(sta->addr));
ieee802_1x_save_eapol(sta, buf, len);
}
return;
}
@ -1183,6 +1213,12 @@ void ieee802_1x_free_station(struct hostapd_data *hapd, struct sta_info *sta)
eloop_cancel_timeout(ieee802_1x_wnm_notif_send, hapd, sta);
#endif /* CONFIG_HS20 */
if (sta->pending_eapol_rx) {
wpabuf_free(sta->pending_eapol_rx->buf);
os_free(sta->pending_eapol_rx);
sta->pending_eapol_rx = NULL;
}
if (sm == NULL)
return;

7
src/ap/sta_info.h
View file

@ -56,6 +56,11 @@ struct mbo_non_pref_chan_info {
u8 channels[];
};
struct pending_eapol_rx {
struct wpabuf *buf;
struct os_reltime rx_time;
};
struct sta_info {
struct sta_info *next; /* next entry in sta list */
struct sta_info *hnext; /* next entry in hash table list */
@ -113,6 +118,8 @@ struct sta_info {
/* IEEE 802.1X related data */
struct eapol_state_machine *eapol_sm;
struct pending_eapol_rx *pending_eapol_rx;
u64 acct_session_id;
struct os_reltime acct_session_start;
int acct_session_started;