eap_ttls.c

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/*
 * EAP peer method: EAP-TTLS (draft-ietf-pppext-eap-ttls-03.txt)
 * 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 "ms_funcs.h"
#include "sha1.h"
#include "crypto.h"
#include "tls.h"
#include "eap_ttls.h"


/* Maximum supported PEAP version
 * 0 = draft-ietf-pppext-eap-ttls-03.txt / draft-funk-eap-ttls-v0-00.txt
 * 1 = draft-funk-eap-ttls-v1-00.txt
 */
#define EAP_TTLS_VERSION 0 /* TTLSv1 implementation is not yet complete */


#define MSCHAPV2_KEY_LEN 16


static void eap_ttls_deinit(struct eap_sm *sm, void *priv);


struct eap_ttls_data {
	struct eap_ssl_data ssl;
	int ssl_initialized;

	int ttls_version, force_ttls_version;

	const struct eap_method *phase2_method;
	void *phase2_priv;
	int phase2_success;
	int phase2_start;

	enum {
		EAP_TTLS_PHASE2_EAP,
		EAP_TTLS_PHASE2_MSCHAPV2,
		EAP_TTLS_PHASE2_MSCHAP,
		EAP_TTLS_PHASE2_PAP,
		EAP_TTLS_PHASE2_CHAP
	} phase2_type;
	struct eap_method_type phase2_eap_type;
	struct eap_method_type *phase2_eap_types;
	size_t num_phase2_eap_types;

	u8 auth_response[20];
	int auth_response_valid;
	u8 ident;
	int resuming; /* starting a resumed session */
	int reauth; /* reauthentication */
	u8 *key_data;

	u8 *pending_phase2_req;
	size_t pending_phase2_req_len;
};


static void * eap_ttls_init(struct eap_sm *sm)
{
	struct eap_ttls_data *data;
	struct wpa_ssid *config = eap_get_config(sm);
	char *selected;

	data = os_zalloc(sizeof(*data));
	if (data == NULL)
		return NULL;
	data->ttls_version = EAP_TTLS_VERSION;
	data->force_ttls_version = -1;
	selected = "EAP";
	data->phase2_type = EAP_TTLS_PHASE2_EAP;

	if (config && config->phase1) {
		char *pos = os_strstr(config->phase1, "ttlsver=");
		if (pos) {
			data->force_ttls_version = atoi(pos + 8);
			data->ttls_version = data->force_ttls_version;
			wpa_printf(MSG_DEBUG, "EAP-TTLS: Forced TTLS version "
				   "%d", data->force_ttls_version);
		}
	}

	if (config && config->phase2) {
		if (os_strstr(config->phase2, "autheap=")) {
			selected = "EAP";
			data->phase2_type = EAP_TTLS_PHASE2_EAP;
		} else if (os_strstr(config->phase2, "auth=MSCHAPV2")) {
			selected = "MSCHAPV2";
			data->phase2_type = EAP_TTLS_PHASE2_MSCHAPV2;
		} else if (os_strstr(config->phase2, "auth=MSCHAP")) {
			selected = "MSCHAP";
			data->phase2_type = EAP_TTLS_PHASE2_MSCHAP;
		} else if (os_strstr(config->phase2, "auth=PAP")) {
			selected = "PAP";
			data->phase2_type = EAP_TTLS_PHASE2_PAP;
		} else if (os_strstr(config->phase2, "auth=CHAP")) {
			selected = "CHAP";
			data->phase2_type = EAP_TTLS_PHASE2_CHAP;
		}
	}
	wpa_printf(MSG_DEBUG, "EAP-TTLS: Phase2 type: %s", selected);

	if (data->phase2_type == EAP_TTLS_PHASE2_EAP) {
		if (config && config->phase2) {
			char *start, *pos, *buf;
			struct eap_method_type *methods = NULL, *_methods;
			u8 method;
			size_t num_methods = 0;
			start = buf = os_strdup(config->phase2);
			if (buf == NULL) {
				eap_ttls_deinit(sm, data);
				return NULL;
			}
			while (start && *start != '\0') {
				int vendor;
				pos = os_strstr(start, "autheap=");
				if (pos == NULL)
					break;
				if (start != pos && *(pos - 1) != ' ') {
					start = pos + 8;
					continue;
				}

				start = pos + 8;
				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, "EAP-TTLS: "
						   "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);
						eap_ttls_deinit(sm, data);
						return NULL;
					}
					methods = _methods;
					methods[num_methods - 1].vendor =
						vendor;
					methods[num_methods - 1].method =
						method;
				}

				start = pos;
			}
			os_free(buf);
			data->phase2_eap_types = methods;
			data->num_phase2_eap_types = num_methods;
		}
		if (data->phase2_eap_types == NULL) {
			data->phase2_eap_types = eap_get_phase2_types(
				config, &data->num_phase2_eap_types);
		}
		if (data->phase2_eap_types == NULL) {
			wpa_printf(MSG_ERROR, "EAP-TTLS: No Phase2 EAP method "
				   "available");
			eap_ttls_deinit(sm, data);
			return NULL;
		}
		wpa_hexdump(MSG_DEBUG, "EAP-TTLS: Phase2 EAP types",
			    (u8 *) data->phase2_eap_types,
			    data->num_phase2_eap_types *
			    sizeof(struct eap_method_type));
		data->phase2_eap_type.vendor = EAP_VENDOR_IETF;
		data->phase2_eap_type.method = EAP_TYPE_NONE;
	}

	if (!(tls_capabilities(sm->ssl_ctx) & TLS_CAPABILITY_IA) &&
	    data->ttls_version > 0) {
		if (data->force_ttls_version > 0) {
			wpa_printf(MSG_INFO, "EAP-TTLS: Forced TTLSv%d and "
				   "TLS library does not support TLS/IA.",
				   data->force_ttls_version);
			eap_ttls_deinit(sm, data);
			return NULL;
		}
		data->ttls_version = 0;
	}

	return data;
}


static void eap_ttls_deinit(struct eap_sm *sm, void *priv)
{
	struct eap_ttls_data *data = priv;
	if (data == NULL)
		return;
	if (data->phase2_priv && data->phase2_method)
		data->phase2_method->deinit(sm, data->phase2_priv);
	os_free(data->phase2_eap_types);
	if (data->ssl_initialized)
		eap_tls_ssl_deinit(sm, &data->ssl);
	os_free(data->key_data);
	os_free(data->pending_phase2_req);
	os_free(data);
}


static int eap_ttls_encrypt(struct eap_sm *sm, struct eap_ttls_data *data,
			    int id, const u8 *plain, size_t plain_len,
			    u8 **out_data, size_t *out_len)
{
	int res;
	u8 *pos;
	struct eap_hdr *resp;

	/* TODO: add support for fragmentation, if needed. This will need to
	 * add TLS Message Length field, if the frame is fragmented. */
	resp = os_malloc(sizeof(struct eap_hdr) + 2 + data->ssl.tls_out_limit);
	if (resp == NULL)
		return -1;

	resp->code = EAP_CODE_RESPONSE;
	resp->identifier = id;

	pos = (u8 *) (resp + 1);
	*pos++ = EAP_TYPE_TTLS;
	*pos++ = data->ttls_version;

	res = tls_connection_encrypt(sm->ssl_ctx, data->ssl.conn,
				     plain, plain_len,
				     pos, data->ssl.tls_out_limit);
	if (res < 0) {
		wpa_printf(MSG_INFO, "EAP-TTLS: Failed to encrypt Phase 2 "
			   "data");
		os_free(resp);
		return -1;
	}

	*out_len = sizeof(struct eap_hdr) + 2 + res;
	resp->length = host_to_be16(*out_len);
	*out_data = (u8 *) resp;
	return 0;
}


static u8 * eap_ttls_avp_hdr(u8 *avphdr, u32 avp_code, u32 vendor_id,
			     int mandatory, size_t len)
{
	struct ttls_avp_vendor *avp;
	u8 flags;
	size_t hdrlen;

	avp = (struct ttls_avp_vendor *) avphdr;
	flags = mandatory ? AVP_FLAGS_MANDATORY : 0;
	if (vendor_id) {
		flags |= AVP_FLAGS_VENDOR;
		hdrlen = sizeof(*avp);
		avp->vendor_id = host_to_be32(vendor_id);
	} else {
		hdrlen = sizeof(struct ttls_avp);
	}

	avp->avp_code = host_to_be32(avp_code);
	avp->avp_length = host_to_be32((flags << 24) | (hdrlen + len));

	return avphdr + hdrlen;
}


static u8 * eap_ttls_avp_add(u8 *start, u8 *avphdr, u32 avp_code,
			     u32 vendor_id, int mandatory,
			     u8 *data, size_t len)
{
	u8 *pos;
	pos = eap_ttls_avp_hdr(avphdr, avp_code, vendor_id, mandatory, len);
	os_memcpy(pos, data, len);
	pos += len;
	AVP_PAD(start, pos);
	return pos;
}


static int eap_ttls_avp_encapsulate(u8 **resp, size_t *resp_len, u32 avp_code,
				    int mandatory)
{
	u8 *avp, *pos;

	avp = os_malloc(sizeof(struct ttls_avp) + *resp_len + 4);
	if (avp == NULL) {
		os_free(*resp);
		*resp = NULL;
		*resp_len = 0;
		return -1;
	}

	pos = eap_ttls_avp_hdr(avp, avp_code, 0, mandatory, *resp_len);
	os_memcpy(pos, *resp, *resp_len);
	pos += *resp_len;
	AVP_PAD(avp, pos);
	os_free(*resp);
	*resp = avp;
	*resp_len = pos - avp;
	return 0;
}


static int eap_ttls_ia_permute_inner_secret(struct eap_sm *sm,
					    struct eap_ttls_data *data,
					    const u8 *key, size_t key_len)
{
	u8 *buf;
	size_t buf_len;
	int ret;

	if (key) {
		buf_len = 2 + key_len;
		buf = os_malloc(buf_len);
		if (buf == NULL)
			return -1;
		WPA_PUT_BE16(buf, key_len);
		os_memcpy(buf + 2, key, key_len);
	} else {
		buf = NULL;
		buf_len = 0;
	}

	wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: Session keys for TLS/IA inner "
			"secret permutation", buf, buf_len);
	ret = tls_connection_ia_permute_inner_secret(sm->ssl_ctx,
						     data->ssl.conn,
						     buf, buf_len);
	os_free(buf);

	return ret;
}


static int eap_ttls_v0_derive_key(struct eap_sm *sm,
				  struct eap_ttls_data *data)
{
	os_free(data->key_data);
	data->key_data = eap_tls_derive_key(sm, &data->ssl,
					    "ttls keying material",
					    EAP_TLS_KEY_LEN);
	if (!data->key_data) {
		wpa_printf(MSG_INFO, "EAP-TTLS: Failed to derive key");
		return -1;
	}

	wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: Derived key",
			data->key_data, EAP_TLS_KEY_LEN);

	return 0;
}


static int eap_ttls_v1_derive_key(struct eap_sm *sm,
				  struct eap_ttls_data *data)
{
	struct tls_keys keys;
	u8 *rnd;

	os_free(data->key_data);
	data->key_data = NULL;

	os_memset(&keys, 0, sizeof(keys));
	if (tls_connection_get_keys(sm->ssl_ctx, data->ssl.conn, &keys) ||
	    keys.client_random == NULL || keys.server_random == NULL ||
	    keys.inner_secret == NULL) {
		wpa_printf(MSG_INFO, "EAP-TTLS: Could not get inner secret, "
			   "client random, or server random to derive keying "
			   "material");
		return -1;
	}

	rnd = os_malloc(keys.client_random_len + keys.server_random_len);
	data->key_data = os_malloc(EAP_TLS_KEY_LEN);
	if (rnd == NULL || data->key_data == NULL) {
		wpa_printf(MSG_INFO, "EAP-TTLS: No memory for key derivation");
		os_free(rnd);
		os_free(data->key_data);
		data->key_data = NULL;
		return -1;
	}
	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.inner_secret, keys.inner_secret_len,
		    "ttls v1 keying material", rnd, keys.client_random_len +
		    keys.server_random_len, data->key_data, EAP_TLS_KEY_LEN)) {
		wpa_printf(MSG_DEBUG, "EAP-TTLS: Failed to derive key");
		os_free(rnd);
		os_free(data->key_data);
		data->key_data = NULL;
		return -1;
	}

	wpa_hexdump(MSG_DEBUG, "EAP-TTLS: client/server random",
		    rnd, keys.client_random_len + keys.server_random_len);
	wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: TLS/IA inner secret",
			keys.inner_secret, keys.inner_secret_len);

	os_free(rnd);

	wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: Derived key",
			data->key_data, EAP_TLS_KEY_LEN);

	return 0;
}


static u8 * eap_ttls_implicit_challenge(struct eap_sm *sm,
					struct eap_ttls_data *data, size_t len)
{
	struct tls_keys keys;
	u8 *challenge, *rnd;

	if (data->ttls_version == 0) {
		return eap_tls_derive_key(sm, &data->ssl, "ttls challenge",
					  len);
	}

	os_memset(&keys, 0, sizeof(keys));