preauth_auth.c

Go to the documentation of this file.

/*
 * hostapd - Authenticator for IEEE 802.11i RSN pre-authentication
 * Copyright (c) 2004-2007, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "utils/includes.h"

#ifdef CONFIG_RSN_PREAUTH

#include "utils/common.h"
#include "utils/eloop.h"
#include "l2_packet/l2_packet.h"
#include "common/wpa_common.h"
#include "eapol_auth/eapol_auth_sm.h"
#include "eapol_auth/eapol_auth_sm_i.h"
#include "hostapd.h"
#include "ap_config.h"
#include "ieee802_1x.h"
#include "sta_info.h"
#include "wpa_auth.h"
#include "preauth_auth.h"

#ifndef ETH_P_PREAUTH
#define ETH_P_PREAUTH 0x88C7 /* IEEE 802.11i pre-authentication */
#endif /* ETH_P_PREAUTH */

static const int dot11RSNAConfigPMKLifetime = 43200;

struct rsn_preauth_interface {
        struct rsn_preauth_interface *next;
        struct hostapd_data *hapd;
        struct l2_packet_data *l2;
        char *ifname;
        int ifindex;
};


static void rsn_preauth_receive(void *ctx, const u8 *src_addr,
                                const u8 *buf, size_t len)
{
        struct rsn_preauth_interface *piface = ctx;
        struct hostapd_data *hapd = piface->hapd;
        struct ieee802_1x_hdr *hdr;
        struct sta_info *sta;
        struct l2_ethhdr *ethhdr;

        wpa_printf(MSG_DEBUG, "RSN: receive pre-auth packet "
                   "from interface '%s'", piface->ifname);
        if (len < sizeof(*ethhdr) + sizeof(*hdr)) {
                wpa_printf(MSG_DEBUG, "RSN: too short pre-auth packet "
                           "(len=%lu)", (unsigned long) len);
                return;
        }

        ethhdr = (struct l2_ethhdr *) buf;
        hdr = (struct ieee802_1x_hdr *) (ethhdr + 1);

        if (os_memcmp(ethhdr->h_dest, hapd->own_addr, ETH_ALEN) != 0) {
                wpa_printf(MSG_DEBUG, "RSN: pre-auth for foreign address "
                           MACSTR, MAC2STR(ethhdr->h_dest));
                return;
        }

        sta = ap_get_sta(hapd, ethhdr->h_source);
        if (sta && (sta->flags & WLAN_STA_ASSOC)) {
                wpa_printf(MSG_DEBUG, "RSN: pre-auth for already association "
                           "STA " MACSTR, MAC2STR(sta->addr));
                return;
        }
        if (!sta && hdr->type == IEEE802_1X_TYPE_EAPOL_START) {
                sta = ap_sta_add(hapd, ethhdr->h_source);
                if (sta == NULL)
                        return;
                sta->flags = WLAN_STA_PREAUTH;

                ieee802_1x_new_station(hapd, sta);
                if (sta->eapol_sm == NULL) {
                        ap_free_sta(hapd, sta);
                        sta = NULL;
                } else {
                        sta->eapol_sm->radius_identifier = -1;
                        sta->eapol_sm->portValid = TRUE;
                        sta->eapol_sm->flags |= EAPOL_SM_PREAUTH;
                }
        }
        if (sta == NULL)
                return;
        sta->preauth_iface = piface;
        ieee802_1x_receive(hapd, ethhdr->h_source, (u8 *) (ethhdr + 1),
                           len - sizeof(*ethhdr));
}


static int rsn_preauth_iface_add(struct hostapd_data *hapd, const char *ifname)
{
        struct rsn_preauth_interface *piface;

        wpa_printf(MSG_DEBUG, "RSN pre-auth interface '%s'", ifname);

        piface = os_zalloc(sizeof(*piface));
        if (piface == NULL)
                return -1;
        piface->hapd = hapd;

        piface->ifname = os_strdup(ifname);
        if (piface->ifname == NULL) {
                goto fail1;
        }

        piface->l2 = l2_packet_init(piface->ifname, NULL, ETH_P_PREAUTH,
                                    rsn_preauth_receive, piface, 1);
        if (piface->l2 == NULL) {
                wpa_printf(MSG_ERROR, "Failed to open register layer 2 access "
                           "to ETH_P_PREAUTH");
                goto fail2;
        }

        piface->next = hapd->preauth_iface;
        hapd->preauth_iface = piface;
        return 0;

fail2:
        os_free(piface->ifname);
fail1:
        os_free(piface);
        return -1;
}


void rsn_preauth_iface_deinit(struct hostapd_data *hapd)
{
        struct rsn_preauth_interface *piface, *prev;

        piface = hapd->preauth_iface;
        hapd->preauth_iface = NULL;
        while (piface) {
                prev = piface;
                piface = piface->next;
                l2_packet_deinit(prev->l2);
                os_free(prev->ifname);
                os_free(prev);
        }
}


int rsn_preauth_iface_init(struct hostapd_data *hapd)
{
        char *tmp, *start, *end;

        if (hapd->conf->rsn_preauth_interfaces == NULL)
                return 0;

        tmp = os_strdup(hapd->conf->rsn_preauth_interfaces);
        if (tmp == NULL)
                return -1;
        start = tmp;
        for (;;) {
                while (*start == ' ')
                        start++;
                if (*start == '\0')
                        break;
                end = os_strchr(start, ' ');
                if (end)
                        *end = '\0';

                if (rsn_preauth_iface_add(hapd, start)) {
                        rsn_preauth_iface_deinit(hapd);
                        os_free(tmp);
                        return -1;
                }

                if (end)
                        start = end + 1;
                else
                        break;
        }
        os_free(tmp);
        return 0;
}


static void rsn_preauth_finished_cb(void *eloop_ctx, void *timeout_ctx)
{
        struct hostapd_data *hapd = eloop_ctx;
        struct sta_info *sta = timeout_ctx;
        wpa_printf(MSG_DEBUG, "RSN: Removing pre-authentication STA entry for "
                   MACSTR, MAC2STR(sta->addr));
        ap_free_sta(hapd, sta);
}


void rsn_preauth_finished(struct hostapd_data *hapd, struct sta_info *sta,
                          int success)
{
        const u8 *key;
        size_t len;
        hostapd_logger(hapd, sta->addr, HOSTAPD_MODULE_WPA,
                       HOSTAPD_LEVEL_INFO, "pre-authentication %s",
                       success ? "succeeded" : "failed");

        key = ieee802_1x_get_key(sta->eapol_sm, &len);
        if (len > PMK_LEN)
                len = PMK_LEN;
        if (success && key) {
                if (wpa_auth_pmksa_add_preauth(hapd->wpa_auth, key, len,
                                               sta->addr,
                                               dot11RSNAConfigPMKLifetime,
                                               sta->eapol_sm) == 0) {
                        hostapd_logger(hapd, sta->addr, HOSTAPD_MODULE_WPA,
                                       HOSTAPD_LEVEL_DEBUG,
                                       "added PMKSA cache entry (pre-auth)");
                } else {
                        hostapd_logger(hapd, sta->addr, HOSTAPD_MODULE_WPA,
                                       HOSTAPD_LEVEL_DEBUG,
                                       "failed to add PMKSA cache entry "
                                       "(pre-auth)");
                }
        }

        /*
         * Finish STA entry removal from timeout in order to avoid freeing
         * STA data before the caller has finished processing.
         */
        eloop_register_timeout(0, 0, rsn_preauth_finished_cb, hapd, sta);
}


void rsn_preauth_send(struct hostapd_data *hapd, struct sta_info *sta,
                      u8 *buf, size_t len)
{
        struct rsn_preauth_interface *piface;
        struct l2_ethhdr *ethhdr;

        piface = hapd->preauth_iface;
        while (piface) {
                if (piface == sta->preauth_iface)
                        break;
                piface = piface->next;
        }

        if (piface == NULL) {
                wpa_printf(MSG_DEBUG, "RSN: Could not find pre-authentication "
                           "interface for " MACSTR, MAC2STR(sta->addr));
                return;
        }

        ethhdr = os_malloc(sizeof(*ethhdr) + len);
        if (ethhdr == NULL)
                return;

        os_memcpy(ethhdr->h_dest, sta->addr, ETH_ALEN);
        os_memcpy(ethhdr->h_source, hapd->own_addr, ETH_ALEN);
        ethhdr->h_proto = host_to_be16(ETH_P_PREAUTH);
        os_memcpy(ethhdr + 1, buf, len);

        if (l2_packet_send(piface->l2, sta->addr, ETH_P_PREAUTH, (u8 *) ethhdr,
                           sizeof(*ethhdr) + len) < 0) {
                wpa_printf(MSG_ERROR, "Failed to send preauth packet using "
                           "l2_packet_send\n");
        }
        os_free(ethhdr);
}


void rsn_preauth_free_station(struct hostapd_data *hapd, struct sta_info *sta)
{
        eloop_cancel_timeout(rsn_preauth_finished_cb, hapd, sta);
}

#endif /* CONFIG_RSN_PREAUTH */