eap_server_wsc.c

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/*
 * EAP-WSC server for Wi-Fi Protected Setup
 * Copyright (c) 2007-2008, 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 "includes.h"

#include "common.h"
#include "eloop.h"
#include "eap_i.h"
#include "eap_common/eap_wsc_common.h"
#include "wps/wps.h"


struct eap_wsc_data {
        enum { START, MESG, FRAG_ACK, WAIT_FRAG_ACK, DONE, FAIL } state;
        int registrar;
        struct wpabuf *in_buf;
        struct wpabuf *out_buf;
        enum wsc_op_code in_op_code, out_op_code;
        size_t out_used;
        size_t fragment_size;
        struct wps_data *wps;
        int ext_reg_timeout;
};


#ifndef CONFIG_NO_STDOUT_DEBUG
static const char * eap_wsc_state_txt(int state)
{
        switch (state) {
        case START:
                return "START";
        case MESG:
                return "MESG";
        case FRAG_ACK:
                return "FRAG_ACK";
        case WAIT_FRAG_ACK:
                return "WAIT_FRAG_ACK";
        case DONE:
                return "DONE";
        case FAIL:
                return "FAIL";
        default:
                return "?";
        }
}
#endif /* CONFIG_NO_STDOUT_DEBUG */


static void eap_wsc_state(struct eap_wsc_data *data, int state)
{
        wpa_printf(MSG_DEBUG, "EAP-WSC: %s -> %s",
                   eap_wsc_state_txt(data->state),
                   eap_wsc_state_txt(state));
        data->state = state;
}


static void eap_wsc_ext_reg_timeout(void *eloop_ctx, void *timeout_ctx)
{
        struct eap_sm *sm = eloop_ctx;
        struct eap_wsc_data *data = timeout_ctx;

        if (sm->method_pending != METHOD_PENDING_WAIT)
                return;

        wpa_printf(MSG_DEBUG, "EAP-WSC: Timeout while waiting for an External "
                   "Registrar");
        data->ext_reg_timeout = 1;
        eap_sm_pending_cb(sm);
}


static void * eap_wsc_init(struct eap_sm *sm)
{
        struct eap_wsc_data *data;
        int registrar;
        struct wps_config cfg;

        if (sm->identity && sm->identity_len == WSC_ID_REGISTRAR_LEN &&
            os_memcmp(sm->identity, WSC_ID_REGISTRAR, WSC_ID_REGISTRAR_LEN) ==
            0)
                registrar = 0; /* Supplicant is Registrar */
        else if (sm->identity && sm->identity_len == WSC_ID_ENROLLEE_LEN &&
                 os_memcmp(sm->identity, WSC_ID_ENROLLEE, WSC_ID_ENROLLEE_LEN)
                 == 0)
                registrar = 1; /* Supplicant is Enrollee */
        else {
                wpa_hexdump_ascii(MSG_INFO, "EAP-WSC: Unexpected identity",
                                  sm->identity, sm->identity_len);
                return NULL;
        }

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;
        data->state = registrar ? START : MESG;
        data->registrar = registrar;

        os_memset(&cfg, 0, sizeof(cfg));
        cfg.wps = sm->wps;
        cfg.registrar = registrar;
        if (registrar) {
                if (sm->wps == NULL || sm->wps->registrar == NULL) {
                        wpa_printf(MSG_INFO, "EAP-WSC: WPS Registrar not "
                                   "initialized");
                        os_free(data);
                        return NULL;
                }
        } else {
                if (sm->user == NULL || sm->user->password == NULL) {
                        wpa_printf(MSG_INFO, "EAP-WSC: No AP PIN (password) "
                                   "configured for Enrollee functionality");
                        os_free(data);
                        return NULL;
                }
                cfg.pin = sm->user->password;
                cfg.pin_len = sm->user->password_len;
        }
        cfg.assoc_wps_ie = sm->assoc_wps_ie;
        cfg.peer_addr = sm->peer_addr;
        if (0 /* TODO: could provide option for forcing PSK format */)
                 cfg.use_psk_key = 1;
        data->wps = wps_init(&cfg);
        if (data->wps == NULL) {
                os_free(data);
                return NULL;
        }
        data->fragment_size = WSC_FRAGMENT_SIZE;

        return data;
}


static void eap_wsc_reset(struct eap_sm *sm, void *priv)
{
        struct eap_wsc_data *data = priv;
        eloop_cancel_timeout(eap_wsc_ext_reg_timeout, sm, data);
        wpabuf_free(data->in_buf);
        wpabuf_free(data->out_buf);
        wps_deinit(data->wps);
        os_free(data);
}


static struct wpabuf * eap_wsc_build_start(struct eap_sm *sm,
                                           struct eap_wsc_data *data, u8 id)
{
        struct wpabuf *req;

        req = eap_msg_alloc(EAP_VENDOR_WFA, EAP_VENDOR_TYPE_WSC, 2,
                            EAP_CODE_REQUEST, id);
        if (req == NULL) {
                wpa_printf(MSG_ERROR, "EAP-WSC: Failed to allocate memory for "
                           "request");
                return NULL;
        }

        wpa_printf(MSG_DEBUG, "EAP-WSC: Send WSC/Start");
        wpabuf_put_u8(req, WSC_Start); /* Op-Code */
        wpabuf_put_u8(req, 0); /* Flags */

        return req;
}


static struct wpabuf * eap_wsc_build_msg(struct eap_wsc_data *data, u8 id)
{
        struct wpabuf *req;
        u8 flags;
        size_t send_len, plen;

        flags = 0;
        send_len = wpabuf_len(data->out_buf) - data->out_used;
        if (2 + send_len > data->fragment_size) {
                send_len = data->fragment_size - 2;
                flags |= WSC_FLAGS_MF;
                if (data->out_used == 0) {
                        flags |= WSC_FLAGS_LF;
                        send_len -= 2;
                }
        }
        plen = 2 + send_len;
        if (flags & WSC_FLAGS_LF)
                plen += 2;
        req = eap_msg_alloc(EAP_VENDOR_WFA, EAP_VENDOR_TYPE_WSC, plen,
                            EAP_CODE_REQUEST, id);
        if (req == NULL) {
                wpa_printf(MSG_ERROR, "EAP-WSC: Failed to allocate memory for "
                           "request");
                return NULL;
        }

        wpabuf_put_u8(req, data->out_op_code); /* Op-Code */
        wpabuf_put_u8(req, flags); /* Flags */
        if (flags & WSC_FLAGS_LF)
                wpabuf_put_be16(req, wpabuf_len(data->out_buf));

        wpabuf_put_data(req, wpabuf_head_u8(data->out_buf) + data->out_used,
                        send_len);
        data->out_used += send_len;

        if (data->out_used == wpabuf_len(data->out_buf)) {
                wpa_printf(MSG_DEBUG, "EAP-WSC: Sending out %lu bytes "
                           "(message sent completely)",
                           (unsigned long) send_len);
                wpabuf_free(data->out_buf);
                data->out_buf = NULL;
                data->out_used = 0;
                eap_wsc_state(data, MESG);
        } else {
                wpa_printf(MSG_DEBUG, "EAP-WSC: Sending out %lu bytes "
                           "(%lu more to send)", (unsigned long) send_len,
                           (unsigned long) wpabuf_len(data->out_buf) -
                           data->out_used);
                eap_wsc_state(data, WAIT_FRAG_ACK);
        }

        return req;
}


static struct wpabuf * eap_wsc_buildReq(struct eap_sm *sm, void *priv, u8 id)
{
        struct eap_wsc_data *data = priv;

        switch (data->state) {
        case START:
                return eap_wsc_build_start(sm, data, id);
        case MESG:
                if (data->out_buf == NULL) {
                        data->out_buf = wps_get_msg(data->wps,
                                                    &data->out_op_code);
                        if (data->out_buf == NULL) {
                                wpa_printf(MSG_DEBUG, "EAP-WSC: Failed to "
                                           "receive message from WPS");
                                return NULL;
                        }
                        data->out_used = 0;
                }
                /* pass through */
        case WAIT_FRAG_ACK:
                return eap_wsc_build_msg(data, id);
        case FRAG_ACK:
                return eap_wsc_build_frag_ack(id, EAP_CODE_REQUEST);
        default:
                wpa_printf(MSG_DEBUG, "EAP-WSC: Unexpected state %d in "
                           "buildReq", data->state);
                return NULL;
        }
}


static Boolean eap_wsc_check(struct eap_sm *sm, void *priv,
                             struct wpabuf *respData)
{
        const u8 *pos;
        size_t len;

        pos = eap_hdr_validate(EAP_VENDOR_WFA, EAP_VENDOR_TYPE_WSC,
                               respData, &len);
        if (pos == NULL || len < 2) {
                wpa_printf(MSG_INFO, "EAP-WSC: Invalid frame");
                return TRUE;
        }

        return FALSE;
}


static int eap_wsc_process_cont(struct eap_wsc_data *data,
                                const u8 *buf, size_t len, u8 op_code)
{
        /* Process continuation of a pending message */
        if (op_code != data->in_op_code) {
                wpa_printf(MSG_DEBUG, "EAP-WSC: Unexpected Op-Code %d in "
                           "fragment (expected %d)",
                           op_code, data->in_op_code);
                eap_wsc_state(data, FAIL);
                return -1;
        }

        if (len > wpabuf_tailroom(data->in_buf)) {
                wpa_printf(MSG_DEBUG, "EAP-WSC: Fragment overflow");
                eap_wsc_state(data, FAIL);
                return -1;
        }

        wpabuf_put_data(data->in_buf, buf, len);
        wpa_printf(MSG_DEBUG, "EAP-WSC: Received %lu bytes, waiting for %lu "
                   "bytes more", (unsigned long) len,
                   (unsigned long) wpabuf_tailroom(data->in_buf));

        return 0;
}


static int eap_wsc_process_fragment(struct eap_wsc_data *data,
                                    u8 flags, u8 op_code, u16 message_length,
                                    const u8 *buf, size_t len)
{
        /* Process a fragment that is not the last one of the message */
        if (data->in_buf == NULL && !(flags & WSC_FLAGS_LF)) {
                wpa_printf(MSG_DEBUG, "EAP-WSC: No Message Length "
                           "field in a fragmented packet");
                return -1;
        }

        if (data->in_buf == NULL) {
                /* First fragment of the message */
                data->in_buf = wpabuf_alloc(message_length);
                if (data->in_buf == NULL) {
                        wpa_printf(MSG_DEBUG, "EAP-WSC: No memory for "
                                   "message");
                        return -1;
                }
                data->in_op_code = op_code;
                wpabuf_put_data(data->in_buf, buf, len);
                wpa_printf(MSG_DEBUG, "EAP-WSC: Received %lu bytes in "
                           "first fragment, waiting for %lu bytes more",
                           (unsigned long) len,
                           (unsigned long) wpabuf_tailroom(data->in_buf));
        }

        return 0;
}


static void eap_wsc_process(struct eap_sm *sm, void *priv,
                            struct wpabuf *respData)
{
        struct eap_wsc_data *data = priv;
        const u8 *start, *pos, *end;
        size_t len;
        u8 op_code, flags;
        u16 message_length = 0;
        enum wps_process_res res;
        struct wpabuf tmpbuf;

        eloop_cancel_timeout(eap_wsc_ext_reg_timeout, sm, data);
        if (data->ext_reg_timeout) {
                eap_wsc_state(data, FAIL);
                return;
        }

        pos = eap_hdr_validate(EAP_VENDOR_WFA, EAP_VENDOR_TYPE_WSC,
                               respData, &len);
        if (pos == NULL || len < 2)
                return; /* Should not happen; message already verified */

        start = pos;
        end = start + len;

        op_code = *pos++;
        flags = *pos++;
        if (flags & WSC_FLAGS_LF) {
                if (end - pos < 2) {
                        wpa_printf(MSG_DEBUG, "EAP-WSC: Message underflow");
                        return;
                }
                message_length = WPA_GET_BE16(pos);
                pos += 2;

                if (message_length < end - pos) {
                        wpa_printf(MSG_DEBUG, "EAP-WSC: Invalid Message "
                                   "Length");
                        return;
                }
        }

        wpa_printf(MSG_DEBUG, "EAP-WSC: Received packet: Op-Code %d "
                   "Flags 0x%x Message Length %d",
                   op_code, flags, message_length);

        if (data->state == WAIT_FRAG_ACK) {
                if (op_code != WSC_FRAG_ACK) {
                        wpa_printf(MSG_DEBUG, "EAP-WSC: Unexpected Op-Code %d "
                                   "in WAIT_FRAG_ACK state", op_code);
                        eap_wsc_state(data, FAIL);
                        return;
                }
                wpa_printf(MSG_DEBUG, "EAP-WSC: Fragment acknowledged");
                eap_wsc_state(data, MESG);
                return;
        }

        if (op_code != WSC_ACK && op_code != WSC_NACK && op_code != WSC_MSG &&
            op_code != WSC_Done) {
                wpa_printf(MSG_DEBUG, "EAP-WSC: Unexpected Op-Code %d",
                           op_code);
                eap_wsc_state(data, FAIL);
                return;
        }

        if (data->in_buf &&
            eap_wsc_process_cont(data, pos, end - pos, op_code) < 0) {
                eap_wsc_state(data, FAIL);
                return;
        }

        if (flags & WSC_FLAGS_MF) {
                if (eap_wsc_process_fragment(data, flags, op_code,
                                             message_length, pos, end - pos) <
                    0)
                        eap_wsc_state(data, FAIL);
                else
                        eap_wsc_state(data, FRAG_ACK);
                return;
        }

        if (data->in_buf == NULL) {
                /* Wrap unfragmented messages as wpabuf without extra copy */
                wpabuf_set(&tmpbuf, pos, end - pos);
                data->in_buf = &tmpbuf;
        }

        res = wps_process_msg(data->wps, op_code, data->in_buf);
        switch (res) {
        case WPS_DONE:
                wpa_printf(MSG_DEBUG, "EAP-WSC: WPS processing completed "
                           "successfully - report EAP failure");
                eap_wsc_state(data, FAIL);
                break;
        case WPS_CONTINUE:
                eap_wsc_state(data, MESG);
                break;
        case WPS_FAILURE:
                wpa_printf(MSG_DEBUG, "EAP-WSC: WPS processing failed");
                eap_wsc_state(data, FAIL);
                break;
        case WPS_PENDING:
                eap_wsc_state(data, MESG);
                sm->method_pending = METHOD_PENDING_WAIT;
                eloop_cancel_timeout(eap_wsc_ext_reg_timeout, sm, data);
                eloop_register_timeout(5, 0, eap_wsc_ext_reg_timeout,
                                       sm, data);
                break;
        }

        if (data->in_buf != &tmpbuf)
                wpabuf_free(data->in_buf);
        data->in_buf = NULL;
}


static Boolean eap_wsc_isDone(struct eap_sm *sm, void *priv)
{
        struct eap_wsc_data *data = priv;
        return data->state == FAIL;
}


static Boolean eap_wsc_isSuccess(struct eap_sm *sm, void *priv)
{
        /* EAP-WSC will always result in EAP-Failure */
        return FALSE;
}


static int eap_wsc_getTimeout(struct eap_sm *sm, void *priv)
{
        /* Recommended retransmit times: retransmit timeout 5 seconds,
         * per-message timeout 15 seconds, i.e., 3 tries. */
        sm->MaxRetrans = 2; /* total 3 attempts */
        return 5;
}


int eap_server_wsc_register(void)
{
        struct eap_method *eap;
        int ret;

        eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
                                      EAP_VENDOR_WFA, EAP_VENDOR_TYPE_WSC,
                                      "WSC");
        if (eap == NULL)
                return -1;

        eap->init = eap_wsc_init;
        eap->reset = eap_wsc_reset;
        eap->buildReq = eap_wsc_buildReq;
        eap->check = eap_wsc_check;
        eap->process = eap_wsc_process;
        eap->isDone = eap_wsc_isDone;
        eap->isSuccess = eap_wsc_isSuccess;
        eap->getTimeout = eap_wsc_getTimeout;

        ret = eap_server_method_register(eap);
        if (ret)
                eap_server_method_free(eap);
        return ret;
}