eap_server_gpsk.c

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/*
 * hostapd / EAP-GPSK (RFC 5433) server
 * Copyright (c) 2006-2007, 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 "includes.h"

#include "common.h"
#include "eap_server/eap_i.h"
#include "eap_common/eap_gpsk_common.h"


struct eap_gpsk_data {
        enum { GPSK_1, GPSK_3, SUCCESS, FAILURE } state;
        u8 rand_server[EAP_GPSK_RAND_LEN];
        u8 rand_peer[EAP_GPSK_RAND_LEN];
        u8 msk[EAP_MSK_LEN];
        u8 emsk[EAP_EMSK_LEN];
        u8 sk[EAP_GPSK_MAX_SK_LEN];
        size_t sk_len;
        u8 pk[EAP_GPSK_MAX_PK_LEN];
        size_t pk_len;
        u8 *id_peer;
        size_t id_peer_len;
        u8 *id_server;
        size_t id_server_len;
#define MAX_NUM_CSUITES 2
        struct eap_gpsk_csuite csuite_list[MAX_NUM_CSUITES];
        size_t csuite_count;
        int vendor; /* CSuite/Vendor */
        int specifier; /* CSuite/Specifier */
};


static const char * eap_gpsk_state_txt(int state)
{
        switch (state) {
        case GPSK_1:
                return "GPSK-1";
        case GPSK_3:
                return "GPSK-3";
        case SUCCESS:
                return "SUCCESS";
        case FAILURE:
                return "FAILURE";
        default:
                return "?";
        }
}


static void eap_gpsk_state(struct eap_gpsk_data *data, int state)
{
        wpa_printf(MSG_DEBUG, "EAP-GPSK: %s -> %s",
                   eap_gpsk_state_txt(data->state),
                   eap_gpsk_state_txt(state));
        data->state = state;
}


static void * eap_gpsk_init(struct eap_sm *sm)
{
        struct eap_gpsk_data *data;

        data = os_zalloc(sizeof(*data));
        if (data == NULL)
                return NULL;
        data->state = GPSK_1;

        /* TODO: add support for configuring ID_Server */
        data->id_server = (u8 *) os_strdup("hostapd");
        if (data->id_server)
                data->id_server_len = os_strlen((char *) data->id_server);

        data->csuite_count = 0;
        if (eap_gpsk_supported_ciphersuite(EAP_GPSK_VENDOR_IETF,
                                           EAP_GPSK_CIPHER_AES)) {
                WPA_PUT_BE32(data->csuite_list[data->csuite_count].vendor,
                             EAP_GPSK_VENDOR_IETF);
                WPA_PUT_BE16(data->csuite_list[data->csuite_count].specifier,
                             EAP_GPSK_CIPHER_AES);
                data->csuite_count++;
        }
        if (eap_gpsk_supported_ciphersuite(EAP_GPSK_VENDOR_IETF,
                                           EAP_GPSK_CIPHER_SHA256)) {
                WPA_PUT_BE32(data->csuite_list[data->csuite_count].vendor,
                             EAP_GPSK_VENDOR_IETF);
                WPA_PUT_BE16(data->csuite_list[data->csuite_count].specifier,
                             EAP_GPSK_CIPHER_SHA256);
                data->csuite_count++;
        }

        return data;
}


static void eap_gpsk_reset(struct eap_sm *sm, void *priv)
{
        struct eap_gpsk_data *data = priv;
        os_free(data->id_server);
        os_free(data->id_peer);
        os_free(data);
}


static struct wpabuf * eap_gpsk_build_gpsk_1(struct eap_sm *sm,
                                             struct eap_gpsk_data *data, u8 id)
{
        size_t len;
        struct wpabuf *req;

        wpa_printf(MSG_DEBUG, "EAP-GPSK: Request/GPSK-1");

        if (os_get_random(data->rand_server, EAP_GPSK_RAND_LEN)) {
                wpa_printf(MSG_ERROR, "EAP-GPSK: Failed to get random data");
                eap_gpsk_state(data, FAILURE);
                return NULL;
        }
        wpa_hexdump(MSG_MSGDUMP, "EAP-GPSK: RAND_Server",
                    data->rand_server, EAP_GPSK_RAND_LEN);

        len = 1 + 2 + data->id_server_len + EAP_GPSK_RAND_LEN + 2 +
                data->csuite_count * sizeof(struct eap_gpsk_csuite);
        req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_GPSK, len,
                            EAP_CODE_REQUEST, id);
        if (req == NULL) {
                wpa_printf(MSG_ERROR, "EAP-GPSK: Failed to allocate memory "
                           "for request/GPSK-1");
                eap_gpsk_state(data, FAILURE);
                return NULL;
        }

        wpabuf_put_u8(req, EAP_GPSK_OPCODE_GPSK_1);
        wpabuf_put_be16(req, data->id_server_len);
        wpabuf_put_data(req, data->id_server, data->id_server_len);
        wpabuf_put_data(req, data->rand_server, EAP_GPSK_RAND_LEN);
        wpabuf_put_be16(req,
                        data->csuite_count * sizeof(struct eap_gpsk_csuite));
        wpabuf_put_data(req, data->csuite_list,
                        data->csuite_count * sizeof(struct eap_gpsk_csuite));

        return req;
}


static struct wpabuf * eap_gpsk_build_gpsk_3(struct eap_sm *sm,
                                             struct eap_gpsk_data *data, u8 id)
{
        u8 *pos, *start;
        size_t len, miclen;
        struct eap_gpsk_csuite *csuite;
        struct wpabuf *req;

        wpa_printf(MSG_DEBUG, "EAP-GPSK: Request/GPSK-3");

        miclen = eap_gpsk_mic_len(data->vendor, data->specifier);
        len = 1 + 2 * EAP_GPSK_RAND_LEN + 2 + data->id_server_len +
                sizeof(struct eap_gpsk_csuite) + 2 + miclen;
        req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_GPSK, len,
                            EAP_CODE_REQUEST, id);
        if (req == NULL) {
                wpa_printf(MSG_ERROR, "EAP-GPSK: Failed to allocate memory "
                           "for request/GPSK-3");
                eap_gpsk_state(data, FAILURE);
                return NULL;
        }

        wpabuf_put_u8(req, EAP_GPSK_OPCODE_GPSK_3);
        start = wpabuf_put(req, 0);

        wpabuf_put_data(req, data->rand_peer, EAP_GPSK_RAND_LEN);
        wpabuf_put_data(req, data->rand_server, EAP_GPSK_RAND_LEN);
        wpabuf_put_be16(req, data->id_server_len);
        wpabuf_put_data(req, data->id_server, data->id_server_len);
        csuite = wpabuf_put(req, sizeof(*csuite));
        WPA_PUT_BE32(csuite->vendor, data->vendor);
        WPA_PUT_BE16(csuite->specifier, data->specifier);

        /* no PD_Payload_2 */
        wpabuf_put_be16(req, 0);

        pos = wpabuf_put(req, miclen);
        if (eap_gpsk_compute_mic(data->sk, data->sk_len, data->vendor,
                                 data->specifier, start, pos - start, pos) < 0)
        {
                os_free(req);
                eap_gpsk_state(data, FAILURE);
                return NULL;
        }

        return req;
}


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

        switch (data->state) {
        case GPSK_1:
                return eap_gpsk_build_gpsk_1(sm, data, id);
        case GPSK_3:
                return eap_gpsk_build_gpsk_3(sm, data, id);
        default:
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Unknown state %d in buildReq",
                           data->state);
                break;
        }
        return NULL;
}


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

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_GPSK, respData, &len);
        if (pos == NULL || len < 1) {
                wpa_printf(MSG_INFO, "EAP-GPSK: Invalid frame");
                return TRUE;
        }

        wpa_printf(MSG_DEBUG, "EAP-GPSK: Received frame: opcode=%d", *pos);

        if (data->state == GPSK_1 && *pos == EAP_GPSK_OPCODE_GPSK_2)
                return FALSE;

        if (data->state == GPSK_3 && *pos == EAP_GPSK_OPCODE_GPSK_4)
                return FALSE;

        wpa_printf(MSG_INFO, "EAP-GPSK: Unexpected opcode=%d in state=%d",
                   *pos, data->state);

        return TRUE;
}


static void eap_gpsk_process_gpsk_2(struct eap_sm *sm,
                                    struct eap_gpsk_data *data,
                                    const u8 *payload, size_t payloadlen)
{
        const u8 *pos, *end;
        u16 alen;
        const struct eap_gpsk_csuite *csuite;
        size_t i, miclen;
        u8 mic[EAP_GPSK_MAX_MIC_LEN];

        if (data->state != GPSK_1)
                return;

        wpa_printf(MSG_DEBUG, "EAP-GPSK: Received Response/GPSK-2");

        pos = payload;
        end = payload + payloadlen;

        if (end - pos < 2) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "ID_Peer length");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        alen = WPA_GET_BE16(pos);
        pos += 2;
        if (end - pos < alen) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "ID_Peer");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        os_free(data->id_peer);
        data->id_peer = os_malloc(alen);
        if (data->id_peer == NULL) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Not enough memory to store "
                           "%d-octet ID_Peer", alen);
                return;
        }
        os_memcpy(data->id_peer, pos, alen);
        data->id_peer_len = alen;
        wpa_hexdump_ascii(MSG_DEBUG, "EAP-GPSK: ID_Peer",
                          data->id_peer, data->id_peer_len);
        pos += alen;

        if (end - pos < 2) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "ID_Server length");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        alen = WPA_GET_BE16(pos);
        pos += 2;
        if (end - pos < alen) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "ID_Server");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        if (alen != data->id_server_len ||
            os_memcmp(pos, data->id_server, alen) != 0) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: ID_Server in GPSK-1 and "
                           "GPSK-2 did not match");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        pos += alen;

        if (end - pos < EAP_GPSK_RAND_LEN) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "RAND_Peer");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        os_memcpy(data->rand_peer, pos, EAP_GPSK_RAND_LEN);
        wpa_hexdump(MSG_DEBUG, "EAP-GPSK: RAND_Peer",
                    data->rand_peer, EAP_GPSK_RAND_LEN);
        pos += EAP_GPSK_RAND_LEN;

        if (end - pos < EAP_GPSK_RAND_LEN) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "RAND_Server");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        if (os_memcmp(data->rand_server, pos, EAP_GPSK_RAND_LEN) != 0) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: RAND_Server in GPSK-1 and "
                           "GPSK-2 did not match");
                wpa_hexdump(MSG_DEBUG, "EAP-GPSK: RAND_Server in GPSK-1",
                            data->rand_server, EAP_GPSK_RAND_LEN);
                wpa_hexdump(MSG_DEBUG, "EAP-GPSK: RAND_Server in GPSK-2",
                            pos, EAP_GPSK_RAND_LEN);
                eap_gpsk_state(data, FAILURE);
                return;
        }
        pos += EAP_GPSK_RAND_LEN;

        if (end - pos < 2) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "CSuite_List length");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        alen = WPA_GET_BE16(pos);
        pos += 2;
        if (end - pos < alen) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "CSuite_List");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        if (alen != data->csuite_count * sizeof(struct eap_gpsk_csuite) ||
            os_memcmp(pos, data->csuite_list, alen) != 0) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: CSuite_List in GPSK-1 and "
                           "GPSK-2 did not match");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        pos += alen;

        if (end - pos < (int) sizeof(*csuite)) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "CSuite_Sel");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        csuite = (const struct eap_gpsk_csuite *) pos;
        for (i = 0; i < data->csuite_count; i++) {
                if (os_memcmp(csuite, &data->csuite_list[i], sizeof(*csuite))
                    == 0)
                        break;
        }
        if (i == data->csuite_count) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Peer selected unsupported "
                           "ciphersuite %d:%d",
                           WPA_GET_BE32(csuite->vendor),
                           WPA_GET_BE16(csuite->specifier));
                eap_gpsk_state(data, FAILURE);
                return;
        }
        data->vendor = WPA_GET_BE32(csuite->vendor);
        data->specifier = WPA_GET_BE16(csuite->specifier);
        wpa_printf(MSG_DEBUG, "EAP-GPSK: CSuite_Sel %d:%d",
                   data->vendor, data->specifier);
        pos += sizeof(*csuite); 

        if (end - pos < 2) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "PD_Payload_1 length");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        alen = WPA_GET_BE16(pos);
        pos += 2;
        if (end - pos < alen) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "PD_Payload_1");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        wpa_hexdump(MSG_DEBUG, "EAP-GPSK: PD_Payload_1", pos, alen);
        pos += alen;

        if (sm->user == NULL || sm->user->password == NULL) {
                wpa_printf(MSG_INFO, "EAP-GPSK: No PSK/password configured "
                           "for the user");
                eap_gpsk_state(data, FAILURE);
                return;
        }

        if (eap_gpsk_derive_keys(sm->user->password, sm->user->password_len,
                                 data->vendor, data->specifier,
                                 data->rand_peer, data->rand_server,
                                 data->id_peer, data->id_peer_len,
                                 data->id_server, data->id_server_len,
                                 data->msk, data->emsk,
                                 data->sk, &data->sk_len,
                                 data->pk, &data->pk_len) < 0) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Failed to derive keys");
                eap_gpsk_state(data, FAILURE);
                return;
        }

        miclen = eap_gpsk_mic_len(data->vendor, data->specifier);
        if (end - pos < (int) miclen) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Message too short for MIC "
                           "(left=%lu miclen=%lu)",
                           (unsigned long) (end - pos),
                           (unsigned long) miclen);
                eap_gpsk_state(data, FAILURE);
                return;
        }
        if (eap_gpsk_compute_mic(data->sk, data->sk_len, data->vendor,
                                 data->specifier, payload, pos - payload, mic)
            < 0) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Failed to compute MIC");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        if (os_memcmp(mic, pos, miclen) != 0) {
                wpa_printf(MSG_INFO, "EAP-GPSK: Incorrect MIC in GPSK-2");
                wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Received MIC", pos, miclen);
                wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Computed MIC", mic, miclen);
                eap_gpsk_state(data, FAILURE);
                return;
        }
        pos += miclen;

        if (pos != end) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Ignored %lu bytes of extra "
                           "data in the end of GPSK-2",
                           (unsigned long) (end - pos));
        }

        eap_gpsk_state(data, GPSK_3);
}


static void eap_gpsk_process_gpsk_4(struct eap_sm *sm,
                                    struct eap_gpsk_data *data,
                                    const u8 *payload, size_t payloadlen)
{
        const u8 *pos, *end;
        u16 alen;
        size_t miclen;
        u8 mic[EAP_GPSK_MAX_MIC_LEN];

        if (data->state != GPSK_3)
                return;

        wpa_printf(MSG_DEBUG, "EAP-GPSK: Received Response/GPSK-4");

        pos = payload;
        end = payload + payloadlen;

        if (end - pos < 2) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "PD_Payload_1 length");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        alen = WPA_GET_BE16(pos);
        pos += 2;
        if (end - pos < alen) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Too short message for "
                           "PD_Payload_1");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        wpa_hexdump(MSG_DEBUG, "EAP-GPSK: PD_Payload_1", pos, alen);
        pos += alen;

        miclen = eap_gpsk_mic_len(data->vendor, data->specifier);
        if (end - pos < (int) miclen) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Message too short for MIC "
                           "(left=%lu miclen=%lu)",
                           (unsigned long) (end - pos),
                           (unsigned long) miclen);
                eap_gpsk_state(data, FAILURE);
                return;
        }
        if (eap_gpsk_compute_mic(data->sk, data->sk_len, data->vendor,
                                 data->specifier, payload, pos - payload, mic)
            < 0) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Failed to compute MIC");
                eap_gpsk_state(data, FAILURE);
                return;
        }
        if (os_memcmp(mic, pos, miclen) != 0) {
                wpa_printf(MSG_INFO, "EAP-GPSK: Incorrect MIC in GPSK-4");
                wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Received MIC", pos, miclen);
                wpa_hexdump(MSG_DEBUG, "EAP-GPSK: Computed MIC", mic, miclen);
                eap_gpsk_state(data, FAILURE);
                return;
        }
        pos += miclen;

        if (pos != end) {
                wpa_printf(MSG_DEBUG, "EAP-GPSK: Ignored %lu bytes of extra "
                           "data in the end of GPSK-4",
                           (unsigned long) (end - pos));
        }

        eap_gpsk_state(data, SUCCESS);
}


static void eap_gpsk_process(struct eap_sm *sm, void *priv,
                             struct wpabuf *respData)
{
        struct eap_gpsk_data *data = priv;
        const u8 *pos;
        size_t len;

        pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_GPSK, respData, &len);
        if (pos == NULL || len < 1)
                return;

        switch (*pos) {
        case EAP_GPSK_OPCODE_GPSK_2:
                eap_gpsk_process_gpsk_2(sm, data, pos + 1, len - 1);
                break;
        case EAP_GPSK_OPCODE_GPSK_4:
                eap_gpsk_process_gpsk_4(sm, data, pos + 1, len - 1);
                break;
        }
}


static Boolean eap_gpsk_isDone(struct eap_sm *sm, void *priv)
{
        struct eap_gpsk_data *data = priv;
        return data->state == SUCCESS || data->state == FAILURE;
}


static u8 * eap_gpsk_getKey(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_gpsk_data *data = priv;
        u8 *key;

        if (data->state != SUCCESS)
                return NULL;

        key = os_malloc(EAP_MSK_LEN);
        if (key == NULL)
                return NULL;
        os_memcpy(key, data->msk, EAP_MSK_LEN);
        *len = EAP_MSK_LEN;

        return key;
}


static u8 * eap_gpsk_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
{
        struct eap_gpsk_data *data = priv;
        u8 *key;

        if (data->state != SUCCESS)
                return NULL;

        key = os_malloc(EAP_EMSK_LEN);
        if (key == NULL)
                return NULL;
        os_memcpy(key, data->emsk, EAP_EMSK_LEN);
        *len = EAP_EMSK_LEN;

        return key;
}


static Boolean eap_gpsk_isSuccess(struct eap_sm *sm, void *priv)
{
        struct eap_gpsk_data *data = priv;
        return data->state == SUCCESS;
}


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

        eap = eap_server_method_alloc(EAP_SERVER_METHOD_INTERFACE_VERSION,
                                      EAP_VENDOR_IETF, EAP_TYPE_GPSK, "GPSK");
        if (eap == NULL)
                return -1;

        eap->init = eap_gpsk_init;
        eap->reset = eap_gpsk_reset;
        eap->buildReq = eap_gpsk_buildReq;
        eap->check = eap_gpsk_check;
        eap->process = eap_gpsk_process;
        eap->isDone = eap_gpsk_isDone;
        eap->getKey = eap_gpsk_getKey;
        eap->isSuccess = eap_gpsk_isSuccess;
        eap->get_emsk = eap_gpsk_get_emsk;

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