eap_tls_common.c

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/**
 * eap_peer_tls_process_init - Initial validation/processing of EAP requests
 * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 * @data: Data for TLS processing
 * @eap_type: EAP type (EAP_TYPE_TLS, EAP_TYPE_PEAP, ...)
 * @ret: Return values from EAP request validation and processing
 * @reqData: EAP request to be processed (eapReqData)
 * @len: Buffer for returning length of the remaining payload
 * @flags: Buffer for returning TLS flags
 * Returns: Pointer to payload after TLS flags and length or %NULL on failure
 *
 * This function validates the EAP header and processes the optional TLS
 * Message Length field. If this is the first fragment of a TLS message, the
 * TLS reassembly code is initialized to receive the indicated number of bytes.
 *
 * EAP-TLS, EAP-PEAP, EAP-TTLS, and EAP-FAST methods are expected to use this
 * function as the first step in processing received messages. They will need
 * to process the flags (apart from Message Length Included) that are returned
 * through the flags pointer and the message payload that will be returned (and
 * the length is returned through the len pointer). Return values (ret) are set
 * for continuation of EAP method processing. The caller is responsible for
 * setting these to indicate completion (either success or failure) based on
 * the authentication result.
 */
const u8 * eap_peer_tls_process_init(struct eap_sm *sm,
				     struct eap_ssl_data *data,
				     EapType eap_type,
				     struct eap_method_ret *ret,
				     const struct wpabuf *reqData,
				     size_t *len, u8 *flags)
{
	const u8 *pos;
	size_t left;
	unsigned int tls_msg_len;

	if (tls_get_errors(sm->ssl_ctx)) {
		wpa_printf(MSG_INFO, "SSL: TLS errors detected");
		ret->ignore = TRUE;
		return NULL;
	}

	pos = eap_hdr_validate(EAP_VENDOR_IETF, eap_type, reqData, &left);
	if (pos == NULL) {
		ret->ignore = TRUE;
		return NULL;
	}
	if (left == 0) {
		wpa_printf(MSG_DEBUG, "SSL: Invalid TLS message: no Flags "
			   "octet included");
		if (!sm->workaround) {
			ret->ignore = TRUE;
			return NULL;
		}

		wpa_printf(MSG_DEBUG, "SSL: Workaround - assume no Flags "
			   "indicates ACK frame");
		*flags = 0;
	} else {
		*flags = *pos++;
		left--;
	}
	wpa_printf(MSG_DEBUG, "SSL: Received packet(len=%lu) - "
		   "Flags 0x%02x", (unsigned long) wpabuf_len(reqData),
		   *flags);
	if (*flags & EAP_TLS_FLAGS_LENGTH_INCLUDED) {
		if (left < 4) {
			wpa_printf(MSG_INFO, "SSL: Short frame with TLS "
				   "length");
			ret->ignore = TRUE;
			return NULL;
		}
		tls_msg_len = WPA_GET_BE32(pos);
		wpa_printf(MSG_DEBUG, "SSL: TLS Message Length: %d",
			   tls_msg_len);
		if (data->tls_in_left == 0) {
			data->tls_in_total = tls_msg_len;
			data->tls_in_left = tls_msg_len;
			os_free(data->tls_in);
			data->tls_in = NULL;
			data->tls_in_len = 0;
		}
		pos += 4;
		left -= 4;
	}

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

	*len = left;
	return pos;
}


/**
 * eap_peer_tls_reset_input - Reset input buffers
 * @data: Data for TLS processing
 *
 * This function frees any allocated memory for input buffers and resets input
 * state.
 */
void eap_peer_tls_reset_input(struct eap_ssl_data *data)
{
	data->tls_in_left = data->tls_in_total = data->tls_in_len = 0;
	os_free(data->tls_in);
	data->tls_in = NULL;
}


/**
 * eap_peer_tls_reset_output - Reset output buffers
 * @data: Data for TLS processing
 *
 * This function frees any allocated memory for output buffers and resets
 * output state.
 */
void eap_peer_tls_reset_output(struct eap_ssl_data *data)
{
	data->tls_out_len = 0;
	data->tls_out_pos = 0;
	os_free(data->tls_out);
	data->tls_out = NULL;
}


/**
 * eap_peer_tls_decrypt - Decrypt received phase 2 TLS message
 * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 * @data: Data for TLS processing
 * @in_data: Message received from the server
 * @in_decrypted: Buffer for returning a pointer to the decrypted message
 * Returns: 0 on success, 1 if more input data is needed, or -1 on failure
 */
int eap_peer_tls_decrypt(struct eap_sm *sm, struct eap_ssl_data *data,
			 const struct wpabuf *in_data,
			 struct wpabuf **in_decrypted)
{
	int res;
	const u8 *msg;
	size_t msg_len, buf_len;
	int need_more_input;

	msg = eap_peer_tls_data_reassemble(data, wpabuf_head(in_data),
					   wpabuf_len(in_data), &msg_len,
					   &need_more_input);
	if (msg == NULL)
		return need_more_input ? 1 : -1;

	buf_len = wpabuf_len(in_data);
	if (data->tls_in_total > buf_len)
		buf_len = data->tls_in_total;
	/*
	 * Even though we try to disable TLS compression, it is possible that
	 * this cannot be done with all TLS libraries. Add extra buffer space
	 * to handle the possibility of the decrypted data being longer than
	 * input data.
	 */
	buf_len += 500;
	buf_len *= 3;
	*in_decrypted = wpabuf_alloc(buf_len ? buf_len : 1);
	if (*in_decrypted == NULL) {
		eap_peer_tls_reset_input(data);
		wpa_printf(MSG_WARNING, "SSL: Failed to allocate memory for "
			   "decryption");
		return -1;
	}

	res = tls_connection_decrypt(sm->ssl_ctx, data->conn, msg, msg_len,
				     wpabuf_mhead(*in_decrypted), buf_len);
	eap_peer_tls_reset_input(data);
	if (res < 0) {
		wpa_printf(MSG_INFO, "SSL: Failed to decrypt Phase 2 data");
		return -1;
	}
	wpabuf_put(*in_decrypted, res);
	return 0;
}


/**
 * eap_peer_tls_encrypt - Encrypt phase 2 TLS message
 * @sm: Pointer to EAP state machine allocated with eap_peer_sm_init()
 * @data: Data for TLS processing
 * @eap_type: EAP type (EAP_TYPE_TLS, EAP_TYPE_PEAP, ...)
 * @peap_version: Version number for EAP-PEAP/TTLS
 * @id: EAP identifier for the response
 * @in_data: Plaintext phase 2 data to encrypt or %NULL to continue fragments
 * @out_data: Buffer for returning a pointer to the encrypted response message
 * Returns: 0 on success, -1 on failure
 */
int eap_peer_tls_encrypt(struct eap_sm *sm, struct eap_ssl_data *data,
			 EapType eap_type, int peap_version, u8 id,
			 const struct wpabuf *in_data,
			 struct wpabuf **out_data)
{
	int res;
	size_t len;

	if (in_data) {
		eap_peer_tls_reset_output(data);
		len = wpabuf_len(in_data) + 300;
		data->tls_out = os_malloc(len);
		if (data->tls_out == NULL)
			return -1;

		res = tls_connection_encrypt(sm->ssl_ctx, data->conn,
					     wpabuf_head(in_data),
					     wpabuf_len(in_data),
					     data->tls_out, len);
		if (res < 0) {
			wpa_printf(MSG_INFO, "SSL: Failed to encrypt Phase 2 "
				   "data (in_len=%lu)",
				   (unsigned long) wpabuf_len(in_data));
			eap_peer_tls_reset_output(data);
			return -1;
		}

		data->tls_out_len = res;
	}

	return eap_tls_process_output(data, eap_type, peap_version, id, 0,
				      out_data);
}


/**
 * eap_peer_select_phase2_methods - Select phase 2 EAP method
 * @config: Pointer to the network configuration
 * @prefix: 'phase2' configuration prefix, e.g., "auth="
 * @types: Buffer for returning allocated list of allowed EAP methods
 * @num_types: Buffer for returning number of allocated EAP methods
 * Returns: 0 on success, -1 on failure
 *
 * This function is used to parse EAP method list and select allowed methods
 * for Phase2 authentication.
 */
int eap_peer_select_phase2_methods(struct eap_peer_config *config,
				   const char *prefix,
				   struct eap_method_type **types,
				   size_t *num_types)
{
	char *start, *pos, *buf;
	struct eap_method_type *methods = NULL, *_methods;
	u8 method;
	size_t num_methods = 0, prefix_len;

	if (config == NULL || config->phase2 == NULL)
		goto get_defaults;

	start = buf = os_strdup(config->phase2);
	if (buf == NULL)
		return -1;

	prefix_len = os_strlen(prefix);

	while (start && *start != '\0') {
		int vendor;
		pos = os_strstr(start, prefix);
		if (pos == NULL)
			break;
		if (start != pos && *(pos - 1) != ' ') {
			start = pos + prefix_len;
			continue;
		}

		start = pos + prefix_len;
		pos = os_strchr(start, ' ');
		if (pos)
			*pos++ = '\0';
		method = eap_get_phase2_type(start, &vendor);
		if (vendor == EAP_VENDOR_IETF && method == EAP_TYPE_NONE) {
			wpa_printf(MSG_ERROR, "TLS: Unsupported Phase2 EAP "
				   "method '%s'", start);
		} else {
			num_methods++;
			_methods = os_realloc(methods,
					      num_methods * sizeof(*methods));
			if (_methods == NULL) {
				os_free(methods);
				os_free(buf);
				return -1;
			}
			methods = _methods;
			methods[num_methods - 1].vendor = vendor;
			methods[num_methods - 1].method = method;
		}

		start = pos;
	}

	os_free(buf);

get_defaults:
	if (methods == NULL)
		methods = eap_get_phase2_types(config, &num_methods);

	if (methods == NULL) {
		wpa_printf(MSG_ERROR, "TLS: No Phase2 EAP methods available");
		return -1;
	}
	wpa_hexdump(MSG_DEBUG, "TLS: Phase2 EAP types",
		    (u8 *) methods,
		    num_methods * sizeof(struct eap_method_type));

	*types = methods;
	*num_types = num_methods;

	return 0;
}


/**
 * eap_peer_tls_phase2_nak - Generate EAP-Nak for Phase 2
 * @types: Buffer for returning allocated list of allowed EAP methods
 * @num_types: Buffer for returning number of allocated EAP methods
 * @hdr: EAP-Request header (and the following EAP type octet)
 * @resp: Buffer for returning the EAP-Nak message
 * Returns: 0 on success, -1 on failure
 */
int eap_peer_tls_phase2_nak(struct eap_method_type *types, size_t num_types,
			    struct eap_hdr *hdr, struct wpabuf **resp)
{
	u8 *pos = (u8 *) (hdr + 1);
	size_t i;

	/* TODO: add support for expanded Nak */
	wpa_printf(MSG_DEBUG, "TLS: Phase 2 Request: Nak type=%d", *pos);
	wpa_hexdump(MSG_DEBUG, "TLS: Allowed Phase2 EAP types",
		    (u8 *) types, num_types * sizeof(struct eap_method_type));
	*resp = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_NAK, num_types,
			      EAP_CODE_RESPONSE, hdr->identifier);
	if (*resp == NULL)
		return -1;

	for (i = 0; i < num_types; i++) {
		if (types[i].vendor == EAP_VENDOR_IETF &&
		    types[i].method < 256)
			wpabuf_put_u8(*resp, types[i].method);
	}

	eap_update_len(*resp);

	return 0;
}