eap_tls_common.c

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/*
 * EAP peer: EAP-TLS/PEAP/TTLS/FAST common functions
 * Copyright (c) 2004-2006, Jouni Malinen <[e-mail]>
 *
 * 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_i.h"
#include "eap_tls_common.h"
#include "config_ssid.h"
#include "md5.h"
#include "sha1.h"
#include "tls.h"
#include "config.h"


static int eap_tls_check_blob(struct eap_sm *sm, const char **name,
			      const u8 **data, size_t *data_len)
{
	const struct wpa_config_blob *blob;

	if (*name == NULL || os_strncmp(*name, "blob://", 7) != 0)
		return 0;

	blob = eap_get_config_blob(sm, *name + 7);
	if (blob == NULL) {
		wpa_printf(MSG_ERROR, "%s: Named configuration blob '%s' not "
			   "found", __func__, *name + 7);
		return -1;
	}

	*name = NULL;
	*data = blob->data;
	*data_len = blob->len;

	return 0;
}


static void eap_tls_params_from_conf1(struct tls_connection_params *params,
				      struct wpa_ssid *config)
{
	params->ca_cert = (char *) config->ca_cert;
	params->ca_path = (char *) config->ca_path;
	params->client_cert = (char *) config->client_cert;
	params->private_key = (char *) config->private_key;
	params->private_key_passwd = (char *) config->private_key_passwd;
	params->dh_file = (char *) config->dh_file;
	params->subject_match = (char *) config->subject_match;
	params->altsubject_match = (char *) config->altsubject_match;
	params->engine_id = config->engine_id;
	params->pin = config->pin;
	params->key_id = config->key_id;
}


static void eap_tls_params_from_conf2(struct tls_connection_params *params,
				      struct wpa_ssid *config)
{
	params->ca_cert = (char *) config->ca_cert2;
	params->ca_path = (char *) config->ca_path2;
	params->client_cert = (char *) config->client_cert2;
	params->private_key = (char *) config->private_key2;
	params->private_key_passwd = (char *) config->private_key2_passwd;
	params->dh_file = (char *) config->dh_file2;
	params->subject_match = (char *) config->subject_match2;
	params->altsubject_match = (char *) config->altsubject_match2;
}


static int eap_tls_params_from_conf(struct eap_sm *sm,
				    struct eap_ssl_data *data,
				    struct tls_connection_params *params,
				    struct wpa_ssid *config, int phase2)
{
	os_memset(params, 0, sizeof(*params));
	params->engine = config->engine;
	if (phase2)
		eap_tls_params_from_conf2(params, config);
	else
		eap_tls_params_from_conf1(params, config);
	params->tls_ia = data->tls_ia;


	if (eap_tls_check_blob(sm, &params->ca_cert, &params->ca_cert_blob,
			       &params->ca_cert_blob_len) ||
	    eap_tls_check_blob(sm, &params->client_cert,
			       &params->client_cert_blob,
			       &params->client_cert_blob_len) ||
	    eap_tls_check_blob(sm, &params->private_key,
			       &params->private_key_blob,
			       &params->private_key_blob_len) ||
	    eap_tls_check_blob(sm, &params->dh_file, &params->dh_blob,
			       &params->dh_blob_len)) {
		wpa_printf(MSG_INFO, "SSL: Failed to get configuration blobs");
		return -1;
	}

	return 0;
}


static int eap_tls_init_connection(struct eap_sm *sm,
				   struct eap_ssl_data *data,
				   struct wpa_ssid *config,
				   struct tls_connection_params *params)
{
	int res;

	data->conn = tls_connection_init(sm->ssl_ctx);
	if (data->conn == NULL) {
		wpa_printf(MSG_INFO, "SSL: Failed to initialize new TLS "
			   "connection");
		return -1;
	}

	res = tls_connection_set_params(sm->ssl_ctx, data->conn, params);
	if (res == TLS_SET_PARAMS_ENGINE_PRV_INIT_FAILED) {
		/* At this point with the pkcs11 engine the PIN might be wrong.
		 * We reset the PIN in the configuration to be sure to not use
		 * it again and the calling function must request a new one */
		os_free(config->pin);
		config->pin = NULL;
	} else if (res == TLS_SET_PARAMS_ENGINE_PRV_VERIFY_FAILED) {
		wpa_printf(MSG_INFO, "TLS: Failed to load private key");
		/* We don't know exactly but maybe the PIN was wrong,
		 * so ask for a new one. */
		os_free(config->pin);
		config->pin = NULL;
		eap_sm_request_pin(sm);
		sm->ignore = TRUE;
		return -1;
	} else if (res) {
		wpa_printf(MSG_INFO, "TLS: Failed to set TLS connection "
			   "parameters");
		return -1;
	}

	return 0;
}


/**
 * eap_tls_ssl_init - Initialize shared TLS functionality
 * @sm: Pointer to EAP state machine allocated with eap_sm_init()
 * @data: Data for TLS processing
 * @config: Pointer to the network configuration
 * Returns: 0 on success, -1 on failure
 *
 * This function is used to initialize shared TLS functionality for EAP-TLS,
 * EAP-PEAP, EAP-TTLS, and EAP-FAST.
 */
int eap_tls_ssl_init(struct eap_sm *sm, struct eap_ssl_data *data,
		     struct wpa_ssid *config)
{
	int ret = -1;
	struct tls_connection_params params;

	if (config == NULL)
		return -1;

	data->eap = sm;
	data->phase2 = sm->init_phase2;
	if (eap_tls_params_from_conf(sm, data, &params, config, data->phase2) <
	    0)
		goto done;

	if (eap_tls_init_connection(sm, data, config, &params) < 0)
		goto done;

	data->tls_out_limit = config->fragment_size;
	if (data->phase2) {
		/* Limit the fragment size in the inner TLS authentication
		 * since the outer authentication with EAP-PEAP does not yet
		 * support fragmentation */
		if (data->tls_out_limit > 100)
			data->tls_out_limit -= 100;
	}

	if (config->phase1 &&
	    os_strstr(config->phase1, "include_tls_length=1")) {
		wpa_printf(MSG_DEBUG, "TLS: Include TLS Message Length in "
			   "unfragmented packets");
		data->include_tls_length = 1;
	}

	ret = 0;

done:
	return ret;
}


/**
 * eap_tls_ssl_deinit - Deinitialize shared TLS functionality
 * @sm: Pointer to EAP state machine allocated with eap_sm_init()
 * @data: Data for TLS processing
 *
 * This function deinitializes shared TLS functionality that was initialized
 * with eap_tls_ssl_init().
 */
void eap_tls_ssl_deinit(struct eap_sm *sm, struct eap_ssl_data *data)
{
	tls_connection_deinit(sm->ssl_ctx, data->conn);
	os_free(data->tls_in);
	os_free(data->tls_out);
}


/**
 * eap_tls_derive_key - Derive a key based on TLS session data
 * @sm: Pointer to EAP state machine allocated with eap_sm_init()
 * @data: Data for TLS processing
 * @label: Label string for deriving the keys, e.g., "client EAP encryption"
 * @len: Length of the key material to generate (usually 64 for MSK)
 * Returns: Pointer to allocated key on success or %NULL on failure
 *
 * This function uses TLS-PRF to generate pseudo-random data based on the TLS
 * session data (client/server random and master key). Each key type may use a
 * different label to bind the key usage into the generated material.
 *
 * The caller is responsible for freeing the returned buffer.
 */
u8 * eap_tls_derive_key(struct eap_sm *sm, struct eap_ssl_data *data,
			const char *label, size_t len)
{
	struct tls_keys keys;
	u8 *rnd = NULL, *out;

	out = os_malloc(len);
	if (out == NULL)
		return NULL;

	/* First, try to use TLS library function for PRF, if available. */
	if (tls_connection_prf(sm->ssl_ctx, data->conn, label, 0, out, len) ==
	    0)
		return out;

	/*
	 * TLS library did not support key generation, so get the needed TLS
	 * session parameters and use an internal implementation of TLS PRF to
	 * derive the key.
	 */
	if (tls_connection_get_keys(sm->ssl_ctx, data->conn, &keys))
		goto fail;

	if (keys.client_random == NULL || keys.server_random == NULL ||
	    keys.master_key == NULL)
		goto fail;

	rnd = os_malloc(keys.client_random_len + keys.server_random_len);
	if (rnd == NULL)
		goto fail;
	os_memcpy(rnd, keys.client_random, keys.client_random_len);
	os_memcpy(rnd + keys.client_random_len, keys.server_random,
		  keys.server_random_len);

	if (tls_prf(keys.master_key, keys.master_key_len,
		    label, rnd, keys.client_random_len +
		    keys.server_random_len, out, len))
		goto fail;

	os_free(rnd);
	return out;

fail:
	os_free(out);
	os_free(rnd);
	return NULL;
}


/**
 * eap_tls_data_reassemble - Reassemble TLS data
 * @sm: Pointer to EAP state machine allocated with eap_sm_init()
 * @data: Data for TLS processing
 * @in_data: Next incoming TLS segment
 * @in_len: Length of in_data
 * @out_len: Variable for returning output data length
 * @need_more_input: Variable for returning whether more input data is needed
 * to reassemble this TLS packet
 * Returns: Pointer to output data, %NULL on error or when more data is needed
 * for the full message (in which case, *need_more_input is also set to 1).
 *
 * This function reassembles TLS fragments. Caller must not free the returned
 * data buffer since an internal pointer to it is maintained.
 */
const u8 * eap_tls_data_reassemble(
	struct eap_sm *sm, struct eap_ssl_data *data, const u8 *in_data,
	size_t in_len, size_t *out_len, int *need_more_input)
{
	u8 *buf;

	*need_more_input = 0;

	if (data->tls_in_left > in_len || data->tls_in) {
		if (data->tls_in_len + in_len == 0) {
			os_free(data->tls_in);
			data->tls_in = NULL;
			data->tls_in_len = 0;
			wpa_printf(MSG_WARNING, "SSL: Invalid reassembly "
				   "state: tls_in_left=%lu tls_in_len=%lu "
				   "in_len=%lu",
				   (unsigned long) data->tls_in_left,
				   (unsigned long) data->tls_in_len,
				   (unsigned long) in_len);
			return NULL;
		}
		if (data->tls_in_len + in_len > 65536) {
			/* Limit length to avoid rogue servers from causing
			 * large memory allocations. */
			os_free(data->tls_in);
			data->tls_in = NULL;
			data->tls_in_len = 0;
			wpa_printf(MSG_INFO, "SSL: Too long TLS fragment (size"
				   " over 64 kB)");
			return NULL;
		}
		buf = os_realloc(data->tls_in, data->tls_in_len + in_len);
		if (buf == NULL) {
			os_free(data->tls_in);
			data->tls_in = NULL;
			data->tls_in_len = 0;
			wpa_printf(MSG_INFO, "SSL: Could not allocate memory "
				   "for TLS data");
			return NULL;
		}
		os_memcpy(buf + data->tls_in_len, in_data, in_len);
		data->tls_in = buf;
		data->tls_in_len += in_len;
		if (in_len > data->tls_in_left) {