eap_ttls.c

hostapd源代码

/*
 * hostapd / EAP-TTLS (draft-ietf-pppext-eap-ttls-05.txt)
 * Copyright (c) 2004-2005, 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 "hostapd.h"
#include "common.h"
#include "eap_i.h"
#include "eap_tls_common.h"
#include "ms_funcs.h"
#include "md5.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_reset(struct eap_sm *sm, void *priv);


struct eap_ttls_data {
	struct eap_ssl_data ssl;
	enum {
		START, PHASE1, PHASE2_START, PHASE2_METHOD,
		PHASE2_MSCHAPV2_RESP, PHASE_FINISHED, SUCCESS, FAILURE
	} state;

	int ttls_version;
	int force_version;
	const struct eap_method *phase2_method;
	void *phase2_priv;
	int mschapv2_resp_ok;
	u8 mschapv2_auth_response[20];
	u8 mschapv2_ident;
	int tls_ia_configured;
};


static const char * eap_ttls_state_txt(int state)
{
	switch (state) {
	case START:
		return "START";
	case PHASE1:
		return "PHASE1";
	case PHASE2_START:
		return "PHASE2_START";
	case PHASE2_METHOD:
		return "PHASE2_METHOD";
	case PHASE2_MSCHAPV2_RESP:
		return "PHASE2_MSCHAPV2_RESP";
	case PHASE_FINISHED:
		return "PHASE_FINISHED";
	case SUCCESS:
		return "SUCCESS";
	case FAILURE:
		return "FAILURE";
	default:
		return "Unknown?!";
	}
}


static void eap_ttls_state(struct eap_ttls_data *data, int state)
{
	wpa_printf(MSG_DEBUG, "EAP-TTLS: %s -> %s",
		   eap_ttls_state_txt(data->state),
		   eap_ttls_state_txt(state));
	data->state = state;
}


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

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

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


struct eap_ttls_avp {
	 /* Note: eap is allocated memory; caller is responsible for freeing
	  * it. All the other pointers are pointing to the packet data, i.e.,
	  * they must not be freed separately. */
	u8 *eap;
	size_t eap_len;
	u8 *user_name;
	size_t user_name_len;
	u8 *user_password;
	size_t user_password_len;
	u8 *chap_challenge;
	size_t chap_challenge_len;
	u8 *chap_password;
	size_t chap_password_len;
	u8 *mschap_challenge;
	size_t mschap_challenge_len;
	u8 *mschap_response;
	size_t mschap_response_len;
	u8 *mschap2_response;
	size_t mschap2_response_len;
};


static int eap_ttls_avp_parse(u8 *buf, size_t len, struct eap_ttls_avp *parse)
{
	struct ttls_avp *avp;
	u8 *pos;
	int left;

	pos = buf;
	left = len;
	memset(parse, 0, sizeof(*parse));

	while (left > 0) {
		u32 avp_code, avp_length, vendor_id = 0;
		u8 avp_flags, *dpos;
		size_t pad, dlen;
		avp = (struct ttls_avp *) pos;
		avp_code = be_to_host32(avp->avp_code);
		avp_length = be_to_host32(avp->avp_length);
		avp_flags = (avp_length >> 24) & 0xff;
		avp_length &= 0xffffff;
		wpa_printf(MSG_DEBUG, "EAP-TTLS: AVP: code=%d flags=0x%02x "
			   "length=%d", (int) avp_code, avp_flags,
			   (int) avp_length);
		if (avp_length > left) {
			wpa_printf(MSG_WARNING, "EAP-TTLS: AVP overflow "
				   "(len=%d, left=%d) - dropped",
				   (int) avp_length, left);
			return -1;
		}
		dpos = (u8 *) (avp + 1);
		dlen = avp_length - sizeof(*avp);
		if (avp_flags & AVP_FLAGS_VENDOR) {
			if (dlen < 4) {
				wpa_printf(MSG_WARNING, "EAP-TTLS: vendor AVP "
					   "underflow");
				return -1;
			}
			vendor_id = be_to_host32(* (u32 *) dpos);
			wpa_printf(MSG_DEBUG, "EAP-TTLS: AVP vendor_id %d",
				   (int) vendor_id);
			dpos += 4;
			dlen -= 4;
		}

		wpa_hexdump(MSG_DEBUG, "EAP-TTLS: AVP data", dpos, dlen);

		if (vendor_id == 0 && avp_code == RADIUS_ATTR_EAP_MESSAGE) {
			wpa_printf(MSG_DEBUG, "EAP-TTLS: AVP - EAP Message");
			if (parse->eap == NULL) {
				parse->eap = malloc(dlen);
				if (parse->eap == NULL) {
					wpa_printf(MSG_WARNING, "EAP-TTLS: "
						   "failed to allocate memory "
						   "for Phase 2 EAP data");
					return -1;
				}
				memcpy(parse->eap, dpos, dlen);
				parse->eap_len = dlen;
			} else {
				u8 *neweap = realloc(parse->eap,
						     parse->eap_len + dlen);
				if (neweap == NULL) {
					wpa_printf(MSG_WARNING, "EAP-TTLS: "
						   "failed to allocate memory "
						   "for Phase 2 EAP data");
					free(parse->eap);
					parse->eap = NULL;
					return -1;
				}
				memcpy(neweap + parse->eap_len, dpos, dlen);
				parse->eap = neweap;
				parse->eap_len += dlen;
			}
		} else if (vendor_id == 0 &&
			   avp_code == RADIUS_ATTR_USER_NAME) {
			wpa_hexdump_ascii(MSG_DEBUG, "EAP-TTLS: User-Name",
					  dpos, dlen);
			parse->user_name = dpos;
			parse->user_name_len = dlen;
		} else if (vendor_id == 0 &&
			   avp_code == RADIUS_ATTR_USER_PASSWORD) {
			u8 *password = dpos;
			size_t password_len = dlen;
			while (password_len > 0 &&
			       password[password_len - 1] == '\0') {
				password_len--;
			}
			wpa_hexdump_ascii_key(MSG_DEBUG, "EAP-TTLS: "
					      "User-Password (PAP)",
					      password, password_len);
			parse->user_password = password;
			parse->user_password_len = password_len;
		} else if (vendor_id == 0 &&
			   avp_code == RADIUS_ATTR_CHAP_CHALLENGE) {
			wpa_hexdump(MSG_DEBUG,
				    "EAP-TTLS: CHAP-Challenge (CHAP)",
				    dpos, dlen);
			parse->chap_challenge = dpos;
			parse->chap_challenge_len = dlen;
		} else if (vendor_id == 0 &&
			   avp_code == RADIUS_ATTR_CHAP_PASSWORD) {
			wpa_hexdump(MSG_DEBUG,
				    "EAP-TTLS: CHAP-Password (CHAP)",
				    dpos, dlen);
			parse->chap_password = dpos;
			parse->chap_password_len = dlen;
		} else if (vendor_id == RADIUS_VENDOR_ID_MICROSOFT &&
			   avp_code == RADIUS_ATTR_MS_CHAP_CHALLENGE) {
			wpa_hexdump(MSG_DEBUG,
				    "EAP-TTLS: MS-CHAP-Challenge",
				    dpos, dlen);
			parse->mschap_challenge = dpos;
			parse->mschap_challenge_len = dlen;
		} else if (vendor_id == RADIUS_VENDOR_ID_MICROSOFT &&
			   avp_code == RADIUS_ATTR_MS_CHAP_RESPONSE) {
			wpa_hexdump(MSG_DEBUG,
				    "EAP-TTLS: MS-CHAP-Response (MSCHAP)",
				    dpos, dlen);
			parse->mschap_response = dpos;
			parse->mschap_response_len = dlen;
		} else if (vendor_id == RADIUS_VENDOR_ID_MICROSOFT &&
			   avp_code == RADIUS_ATTR_MS_CHAP2_RESPONSE) {
			wpa_hexdump(MSG_DEBUG,
				    "EAP-TTLS: MS-CHAP2-Response (MSCHAPV2)",
				    dpos, dlen);
			parse->mschap2_response = dpos;
			parse->mschap2_response_len = dlen;
		} else if (avp_flags & AVP_FLAGS_MANDATORY) {
			wpa_printf(MSG_WARNING, "EAP-TTLS: Unsupported "
				   "mandatory AVP code %d vendor_id %d - "
				   "dropped", (int) avp_code, (int) vendor_id);
			return -1;
		} else {
			wpa_printf(MSG_DEBUG, "EAP-TTLS: Ignoring unsupported "
				   "AVP code %d vendor_id %d",
				   (int) avp_code, (int) vendor_id);
		}

		pad = (4 - (avp_length & 3)) & 3;
		pos += avp_length + pad;
		left -= avp_length + pad;
	}

	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);
	}

	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 "
			   "implicit challenge");
		return NULL;
	}

	rnd = malloc(keys.client_random_len + keys.server_random_len);
	challenge = malloc(len);
	if (rnd == NULL || challenge == NULL) {
		wpa_printf(MSG_INFO, "EAP-TTLS: No memory for implicit "
			   "challenge derivation");
		free(rnd);
		free(challenge);
		return NULL;
	}
	memcpy(rnd, keys.server_random, keys.server_random_len);
	memcpy(rnd + keys.server_random_len, keys.client_random,
	       keys.client_random_len);

	if (tls_prf(keys.inner_secret, keys.inner_secret_len,
		    "inner application challenge", rnd,
		    keys.client_random_len + keys.server_random_len,
		    challenge, len)) {
		wpa_printf(MSG_DEBUG, "EAP-TTLS: Failed to derive implicit "
			   "challenge");
		free(rnd);
		free(challenge);
		return NULL;
	}

	free(rnd);

	wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: Derived implicit challenge",
			challenge, len);

	return challenge;
}


static void * eap_ttls_init(struct eap_sm *sm)
{
	struct eap_ttls_data *data;

	data = wpa_zalloc(sizeof(*data));
	if (data == NULL)
		return NULL;
	data->ttls_version = EAP_TTLS_VERSION;
	data->force_version = -1;
	if (sm->user && sm->user->force_version >= 0) {
		data->force_version = sm->user->force_version;
		wpa_printf(MSG_DEBUG, "EAP-TTLS: forcing version %d",
			   data->force_version);
		data->ttls_version = data->force_version;
	}
	data->state = START;

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

	if (eap_tls_ssl_init(sm, &data->ssl, 0)) {
		wpa_printf(MSG_INFO, "EAP-TTLS: Failed to initialize SSL.");
		eap_ttls_reset(sm, data);
		return NULL;
	}

	return data;
}


static void eap_ttls_reset(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->reset(sm, data->phase2_priv);
	eap_tls_ssl_deinit(sm, &data->ssl);
	free(data);
}


static u8 * eap_ttls_build_start(struct eap_sm *sm, struct eap_ttls_data *data,
				 int id, size_t *reqDataLen)
{
	struct eap_hdr *req;
	u8 *pos;

	*reqDataLen = sizeof(*req) + 2;
	req = malloc(*reqDataLen);
	if (req == NULL) {
		wpa_printf(MSG_ERROR, "EAP-TTLS: Failed to allocate memory for"
			   " request");
		eap_ttls_state(data, FAILURE);
		return NULL;
	}

	req->code = EAP_CODE_REQUEST;
	req->identifier = id;
	req->length = htons(*reqDataLen);
	pos = (u8 *) (req + 1);
	*pos++ = EAP_TYPE_TTLS;
	*pos = EAP_TLS_FLAGS_START | data->ttls_version;

	eap_ttls_state(data, PHASE1);

	return (u8 *) req;
}


static u8 * eap_ttls_build_req(struct eap_sm *sm, struct eap_ttls_data *data,
			       int id, size_t *reqDataLen)
{
	int res;
	u8 *req;

	res = eap_tls_buildReq_helper(sm, &data->ssl, EAP_TYPE_TTLS,
				      data->ttls_version, id, &req,
				      reqDataLen);

	if (tls_connection_established(sm->ssl_ctx, data->ssl.conn)) {
		wpa_printf(MSG_DEBUG, "EAP-TTLS: Phase1 done, starting "
			   "Phase2");
		eap_ttls_state(data, PHASE2_START);
	}

	if (res == 1)
		return eap_tls_build_ack(reqDataLen, id, EAP_TYPE_TTLS,
					 data->ttls_version);
	return req;
}


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

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

	req->code = EAP_CODE_REQUEST;
	req->identifier = id;

	pos = (u8 *) (req + 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");
		free(req);
		return NULL;
	}

	*out_len = sizeof(struct eap_hdr) + 2 + res;
	req->length = host_to_be16(*out_len);