eap_mschapv2.c

IEEE 802.11a/b/g 服务器端AP

			wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: invalid failure "
				   "challenge len %d", hex_len);
		}
		pos = os_strchr(pos, ' ');
		if (pos)
			pos++;
	} else {
		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: required challenge field "
			   "was not present in failure message");
	}

	if (pos && os_strncmp(pos, "V=", 2) == 0) {
		pos += 2;
		data->passwd_change_version = atoi(pos);
		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: password changing "
			   "protocol version %d", data->passwd_change_version);
		pos = os_strchr(pos, ' ');
		if (pos)
			pos++;
	}

	if (pos && os_strncmp(pos, "M=", 2) == 0) {
		pos += 2;
		msg = pos;
	}
	wpa_msg(sm->msg_ctx, MSG_WARNING,
		"EAP-MSCHAPV2: failure message: '%s' (retry %sallowed, error "
		"%d)",
		msg, retry == 1 ? "" : "not ", data->prev_error);
	if (data->prev_error == ERROR_PASSWD_EXPIRED &&
	    data->passwd_change_version == 3 && config) {
		if (config->new_password == NULL) {
			wpa_msg(sm->msg_ctx, MSG_INFO,
				"EAP-MSCHAPV2: Password expired - password "
				"change required");
			eap_sm_request_new_password(sm);
		}
	} else if (retry == 1 && config) {
		/* TODO: could prevent the current password from being used
		 * again at least for some period of time */
		if (!config->mschapv2_retry)
			eap_sm_request_identity(sm);
		eap_sm_request_password(sm);
		config->mschapv2_retry = 1;
	} else if (config) {
		/* TODO: prevent retries using same username/password */
		config->mschapv2_retry = 0;
	}

	return retry == 1;
}


static struct wpabuf * eap_mschapv2_change_password(
	struct eap_sm *sm, struct eap_mschapv2_data *data,
	struct eap_method_ret *ret, const struct eap_mschapv2_hdr *req, u8 id)
{
	struct wpabuf *resp;
	int ms_len;
	const u8 *username, *password, *new_password;
	size_t username_len, password_len, new_password_len;
	struct eap_mschapv2_hdr *ms;
	struct ms_change_password *cp;
	u8 password_hash[16], password_hash_hash[16];
	int pwhash;

	username = eap_get_config_identity(sm, &username_len);
	password = eap_get_config_password2(sm, &password_len, &pwhash);
	new_password = eap_get_config_new_password(sm, &new_password_len);
	if (username == NULL || password == NULL || new_password == NULL)
		return NULL;

	username = mschapv2_remove_domain(username, &username_len);

	ret->ignore = FALSE;
	ret->methodState = METHOD_MAY_CONT;
	ret->decision = DECISION_COND_SUCC;
	ret->allowNotifications = TRUE;

	ms_len = sizeof(*ms) + sizeof(*cp);
	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, ms_len,
			     EAP_CODE_RESPONSE, id);
	if (resp == NULL)
		return NULL;

	ms = wpabuf_put(resp, sizeof(*ms));
	ms->op_code = MSCHAPV2_OP_CHANGE_PASSWORD;
	ms->mschapv2_id = req->mschapv2_id + 1;
	WPA_PUT_BE16(ms->ms_length, ms_len);
	cp = wpabuf_put(resp, sizeof(*cp));

	/* Encrypted-Password */
	if (pwhash) {
		if (encrypt_pw_block_with_password_hash(
			    new_password, new_password_len,
			    password, cp->encr_password))
			goto fail;
	} else {
		if (new_password_encrypted_with_old_nt_password_hash(
			    new_password, new_password_len,
			    password, password_len, cp->encr_password))
			goto fail;
	}

	/* Encrypted-Hash */
	if (pwhash) {
		u8 new_password_hash[16];
		nt_password_hash(new_password, new_password_len,
				 new_password_hash);
		nt_password_hash_encrypted_with_block(password,
						      new_password_hash,
						      cp->encr_hash);
	} else {
		old_nt_password_hash_encrypted_with_new_nt_password_hash(
			new_password, new_password_len,
			password, password_len, cp->encr_hash);
	}

	/* Peer-Challenge */
	if (os_get_random(cp->peer_challenge, MSCHAPV2_CHAL_LEN))
		goto fail;

	/* Reserved, must be zero */
	os_memset(cp->reserved, 0, 8);

	/* NT-Response */
	wpa_hexdump(MSG_DEBUG, "EAP-MSCHAPV2: auth_challenge",
		    data->passwd_change_challenge, PASSWD_CHANGE_CHAL_LEN);
	wpa_hexdump(MSG_DEBUG, "EAP-MSCHAPV2: peer_challenge",
		    cp->peer_challenge, MSCHAPV2_CHAL_LEN);
	wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: username",
			  username, username_len);
	wpa_hexdump_ascii_key(MSG_DEBUG, "EAP-MSCHAPV2: new password",
			      new_password, new_password_len);
	generate_nt_response(data->passwd_change_challenge, cp->peer_challenge,
			     username, username_len,
			     new_password, new_password_len,
			     cp->nt_response);
	wpa_hexdump(MSG_DEBUG, "EAP-MSCHAPV2: NT-Response",
		    cp->nt_response, MSCHAPV2_NT_RESPONSE_LEN);

	/* Authenticator response is not really needed yet, but calculate it
	 * here so that challenges need not be saved. */
	generate_authenticator_response(new_password, new_password_len,
					cp->peer_challenge,
					data->passwd_change_challenge,
					username, username_len,
					cp->nt_response, data->auth_response);
	data->auth_response_valid = 1;

	/* Likewise, generate master_key here since we have the needed data
	 * available. */
	nt_password_hash(new_password, new_password_len, password_hash);
	hash_nt_password_hash(password_hash, password_hash_hash);
	get_master_key(password_hash_hash, cp->nt_response, data->master_key);
	data->master_key_valid = 1;

	/* Flags */
	os_memset(cp->flags, 0, 2);

	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: TX identifier %d mschapv2_id %d "
		   "(change pw)", id, ms->mschapv2_id);

	return resp;

fail:
	wpabuf_free(resp);
	return NULL;
}


/**
 * eap_mschapv2_process - Process an EAP-MSCHAPv2 failure message
 * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 * @data: Pointer to private EAP method data from eap_mschapv2_init()
 * @ret: Return values from EAP request validation and processing
 * @req: Pointer to EAP-MSCHAPv2 header from the request
 * @req_len: Length of the EAP-MSCHAPv2 data
 * @id: EAP identifier used in th erequest
 * Returns: Pointer to allocated EAP response packet (eapRespData) or %NULL if
 * no reply available
 */
static struct wpabuf * eap_mschapv2_failure(struct eap_sm *sm,
					    struct eap_mschapv2_data *data,
					    struct eap_method_ret *ret,
					    const struct eap_mschapv2_hdr *req,
					    size_t req_len, u8 id)
{
	struct wpabuf *resp;
	const u8 *msdata = (const u8 *) (req + 1);
	char *buf;
	size_t len = req_len - sizeof(*req);
	int retry = 0;

	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Received failure");
	wpa_hexdump_ascii(MSG_DEBUG, "EAP-MSCHAPV2: Failure data",
			  msdata, len);
	/*
	 * eap_mschapv2_failure_txt() expects a nul terminated string, so we
	 * must allocate a large enough temporary buffer to create that since
	 * the received message does not include nul termination.
	 */
	buf = os_malloc(len + 1);
	if (buf) {
		os_memcpy(buf, msdata, len);
		buf[len] = '\0';
		retry = eap_mschapv2_failure_txt(sm, data, buf);
		os_free(buf);
	}

	ret->ignore = FALSE;
	ret->methodState = METHOD_DONE;
	ret->decision = DECISION_FAIL;
	ret->allowNotifications = FALSE;

	if (data->prev_error == ERROR_PASSWD_EXPIRED &&
	    data->passwd_change_version == 3) {
		struct eap_peer_config *config = eap_get_config(sm);
		if (config && config->new_password)
			return eap_mschapv2_change_password(sm, data, ret, req,
							    id);
		if (config && config->pending_req_new_password)
			return NULL;
	} else if (retry && data->prev_error == ERROR_AUTHENTICATION_FAILURE) {
		/* TODO: could try to retry authentication, e.g, after having
		 * changed the username/password. In this case, EAP MS-CHAP-v2
		 * Failure Response would not be sent here. */
		return NULL;
	}

	/* Note: Only op_code of the EAP-MSCHAPV2 header is included in failure
	 * message. */
	resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, 1,
			     EAP_CODE_RESPONSE, id);
	if (resp == NULL)
		return NULL;

	wpabuf_put_u8(resp, MSCHAPV2_OP_FAILURE); /* op_code */

	return resp;
}


static int eap_mschapv2_check_config(struct eap_sm *sm)
{
	size_t len;

	if (eap_get_config_identity(sm, &len) == NULL) {
		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Identity not configured");
		eap_sm_request_identity(sm);
		return -1;
	}

	if (eap_get_config_password(sm, &len) == NULL) {
		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Password not configured");
		eap_sm_request_password(sm);
		return -1;
	}

	return 0;
}


static int eap_mschapv2_check_mslen(struct eap_sm *sm, size_t len,
				    const struct eap_mschapv2_hdr *ms)
{
	size_t ms_len = WPA_GET_BE16(ms->ms_length);

	if (ms_len == len)
		return 0;

	wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Invalid header: len=%lu "
		   "ms_len=%lu", (unsigned long) len, (unsigned long) ms_len);
	if (sm->workaround) {
		/* Some authentication servers use invalid ms_len,
		 * ignore it for interoperability. */
		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: workaround, ignore"
			   " invalid ms_len %lu (len %lu)",
			   (unsigned long) ms_len,
			   (unsigned long) len);
		return 0;
	}

	return -1;
}


static void eap_mschapv2_copy_challenge(struct eap_mschapv2_data *data,
					const struct wpabuf *reqData)
{
	/*
	 * Store a copy of the challenge message, so that it can be processed
	 * again in case retry is allowed after a possible failure.
	 */
	wpabuf_free(data->prev_challenge);
	data->prev_challenge = wpabuf_dup(reqData);
}


/**
 * eap_mschapv2_process - Process an EAP-MSCHAPv2 request
 * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 * @priv: Pointer to private EAP method data from eap_mschapv2_init()
 * @ret: Return values from EAP request validation and processing
 * @reqData: EAP request to be processed (eapReqData)
 * Returns: Pointer to allocated EAP response packet (eapRespData) or %NULL if
 * no reply available
 */
static struct wpabuf * eap_mschapv2_process(struct eap_sm *sm, void *priv,
					    struct eap_method_ret *ret,
					    const struct wpabuf *reqData)
{
	struct eap_mschapv2_data *data = priv;
	struct eap_peer_config *config = eap_get_config(sm);
	const struct eap_mschapv2_hdr *ms;
	int using_prev_challenge = 0;
	const u8 *pos;
	size_t len;
	u8 id;

	if (eap_mschapv2_check_config(sm)) {
		ret->ignore = TRUE;
		return NULL;
	}

	if (config->mschapv2_retry && data->prev_challenge &&
	    data->prev_error == ERROR_AUTHENTICATION_FAILURE) {
		wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: Replacing pending packet "
			   "with the previous challenge");

		reqData = data->prev_challenge;
		using_prev_challenge = 1;
		config->mschapv2_retry = 0;
	}

	pos = eap_hdr_validate(EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2, reqData,
			       &len);
	if (pos == NULL || len < sizeof(*ms) + 1) {
		ret->ignore = TRUE;
		return NULL;
	}

	ms = (const struct eap_mschapv2_hdr *) pos;
	if (eap_mschapv2_check_mslen(sm, len, ms)) {
		ret->ignore = TRUE;
		return NULL;
	}

	id = eap_get_id(reqData);
	wpa_printf(MSG_DEBUG, "EAP-MSCHAPV2: RX identifier %d mschapv2_id %d",
		   id, ms->mschapv2_id);

	switch (ms->op_code) {
	case MSCHAPV2_OP_CHALLENGE:
		if (!using_prev_challenge)
			eap_mschapv2_copy_challenge(data, reqData);
		return eap_mschapv2_challenge(sm, data, ret, ms, len, id);
	case MSCHAPV2_OP_SUCCESS:
		return eap_mschapv2_success(sm, data, ret, ms, len, id);
	case MSCHAPV2_OP_FAILURE:
		return eap_mschapv2_failure(sm, data, ret, ms, len, id);
	default:
		wpa_printf(MSG_INFO, "EAP-MSCHAPV2: Unknown op %d - ignored",
			   ms->op_code);
		ret->ignore = TRUE;
		return NULL;
	}
}


static Boolean eap_mschapv2_isKeyAvailable(struct eap_sm *sm, void *priv)
{
	struct eap_mschapv2_data *data = priv;
	return data->success && data->master_key_valid;
}


static u8 * eap_mschapv2_getKey(struct eap_sm *sm, void *priv, size_t *len)
{
	struct eap_mschapv2_data *data = priv;
	u8 *key;
	int key_len;

	if (!data->master_key_valid || !data->success)
		return NULL;

	if (data->full_key) {
		/* EAP-FAST needs both send and receive keys */
		key_len = 2 * MSCHAPV2_KEY_LEN;
	} else {
		key_len = MSCHAPV2_KEY_LEN;
	}

	key = os_malloc(key_len);
	if (key == NULL)
		return NULL;

	if (data->full_key) {
		get_asymetric_start_key(data->master_key, key,
					MSCHAPV2_KEY_LEN, 0, 0);
		get_asymetric_start_key(data->master_key,
					key + MSCHAPV2_KEY_LEN,
					MSCHAPV2_KEY_LEN, 1, 0);
	} else {
		get_asymetric_start_key(data->master_key, key,
					MSCHAPV2_KEY_LEN, 1, 0);
	}

	wpa_hexdump_key(MSG_DEBUG, "EAP-MSCHAPV2: Derived key",
			key, key_len);

	*len = key_len;
	return key;
}


/**
 * eap_peer_mschapv2_register - Register EAP-MSCHAPv2 peer method
 * Returns: 0 on success, -1 on failure
 *
 * This function is used to register EAP-MSCHAPv2 peer method into the EAP
 * method list.
 */
int eap_peer_mschapv2_register(void)
{
	struct eap_method *eap;
	int ret;

	eap = eap_peer_method_alloc(EAP_PEER_METHOD_INTERFACE_VERSION,
				    EAP_VENDOR_IETF, EAP_TYPE_MSCHAPV2,
				    "MSCHAPV2");
	if (eap == NULL)
		return -1;

	eap->init = eap_mschapv2_init;
	eap->deinit = eap_mschapv2_deinit;
	eap->process = eap_mschapv2_process;
	eap->isKeyAvailable = eap_mschapv2_isKeyAvailable;
	eap->getKey = eap_mschapv2_getKey;

	ret = eap_peer_method_register(eap);
	if (ret)
		eap_peer_method_free(eap);
	return ret;
}