eap.c

WPA在Linux下实现的原代码 WPA在Linux下实现的原代码

/*
 * WPA Supplicant / EAP state machines (RFC 4137)
 * 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.
 *
 * This file implements the Peer State Machine as defined in RFC 4137. The used
 * states and state transitions match mostly with the RFC. However, there are
 * couple of additional transitions for working around small issues noticed
 * during testing. These exceptions are explained in comments within the
 * functions in this file. The method functions, m.func(), are similar to the
 * ones used in RFC 4137, but some small changes have used here to optimize
 * operations and to add functionality needed for fast re-authentication
 * (session resumption).
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

#include "common.h"
#include "eap_i.h"
#include "wpa_supplicant.h"
#include "config_ssid.h"
#include "tls.h"
#include "crypto.h"
#include "pcsc_funcs.h"
#include "wpa_ctrl.h"


#define EAP_MAX_AUTH_ROUNDS 50


#ifdef EAP_MD5
extern const struct eap_method eap_method_md5;
#endif
#ifdef EAP_TLS
extern const struct eap_method eap_method_tls;
#endif
#ifdef EAP_MSCHAPv2
extern const struct eap_method eap_method_mschapv2;
#endif
#ifdef EAP_PEAP
extern const struct eap_method eap_method_peap;
#endif
#ifdef EAP_TTLS
extern const struct eap_method eap_method_ttls;
#endif
#ifdef EAP_GTC
extern const struct eap_method eap_method_gtc;
#endif
#ifdef EAP_OTP
extern const struct eap_method eap_method_otp;
#endif
#ifdef EAP_SIM
extern const struct eap_method eap_method_sim;
#endif
#ifdef EAP_LEAP
extern const struct eap_method eap_method_leap;
#endif
#ifdef EAP_PSK
extern const struct eap_method eap_method_psk;
#endif
#ifdef EAP_AKA
extern const struct eap_method eap_method_aka;
#endif
#ifdef EAP_FAST
extern const struct eap_method eap_method_fast;
#endif
#ifdef EAP_PAX
extern const struct eap_method eap_method_pax;
#endif

static const struct eap_method *eap_methods[] =
{
#ifdef EAP_MD5
	&eap_method_md5,
#endif
#ifdef EAP_TLS
	&eap_method_tls,
#endif
#ifdef EAP_MSCHAPv2
	&eap_method_mschapv2,
#endif
#ifdef EAP_PEAP
	&eap_method_peap,
#endif
#ifdef EAP_TTLS
	&eap_method_ttls,
#endif
#ifdef EAP_GTC
	&eap_method_gtc,
#endif
#ifdef EAP_OTP
	&eap_method_otp,
#endif
#ifdef EAP_SIM
	&eap_method_sim,
#endif
#ifdef EAP_LEAP
	&eap_method_leap,
#endif
#ifdef EAP_PSK
	&eap_method_psk,
#endif
#ifdef EAP_AKA
	&eap_method_aka,
#endif
#ifdef EAP_FAST
	&eap_method_fast,
#endif
#ifdef EAP_PAX
	&eap_method_pax,
#endif
};
#define NUM_EAP_METHODS (sizeof(eap_methods) / sizeof(eap_methods[0]))


/**
 * eap_sm_get_eap_methods - Get EAP method based on type number
 * @method: EAP type number
 * Returns: Pointer to EAP method of %NULL if not found
 */
const struct eap_method * eap_sm_get_eap_methods(int method)
{
	int i;
	for (i = 0; i < NUM_EAP_METHODS; i++) {
		if (eap_methods[i]->method == method)
			return eap_methods[i];
	}
	return NULL;
}


static Boolean eap_sm_allowMethod(struct eap_sm *sm, EapType method);
static u8 * eap_sm_buildNak(struct eap_sm *sm, int id, size_t *len);
static void eap_sm_processIdentity(struct eap_sm *sm, const u8 *req,
				   size_t len);
static void eap_sm_processNotify(struct eap_sm *sm, const u8 *req, size_t len);
static u8 * eap_sm_buildNotify(struct eap_sm *sm, int id, size_t *len);
static void eap_sm_parseEapReq(struct eap_sm *sm, const u8 *req, size_t len);
static const char * eap_sm_method_state_txt(EapMethodState state);
static const char * eap_sm_decision_txt(EapDecision decision);


/* Definitions for clarifying state machine implementation */
#define SM_STATE(machine, state) \
static void sm_ ## machine ## _ ## state ## _Enter(struct eap_sm *sm, \
	int global)

#define SM_ENTRY(machine, state) \
if (!global || sm->machine ## _state != machine ## _ ## state) { \
	sm->changed = TRUE; \
	wpa_printf(MSG_DEBUG, "EAP: " #machine " entering state " #state); \
} \
sm->machine ## _state = machine ## _ ## state;

#define SM_ENTER(machine, state) \
sm_ ## machine ## _ ## state ## _Enter(sm, 0)
#define SM_ENTER_GLOBAL(machine, state) \
sm_ ## machine ## _ ## state ## _Enter(sm, 1)

#define SM_STEP(machine) \
static void sm_ ## machine ## _Step(struct eap_sm *sm)

#define SM_STEP_RUN(machine) sm_ ## machine ## _Step(sm)


static Boolean eapol_get_bool(struct eap_sm *sm, enum eapol_bool_var var)
{
	return sm->eapol_cb->get_bool(sm->eapol_ctx, var);
}


static void eapol_set_bool(struct eap_sm *sm, enum eapol_bool_var var,
			   Boolean value)
{
	sm->eapol_cb->set_bool(sm->eapol_ctx, var, value);
}


static unsigned int eapol_get_int(struct eap_sm *sm, enum eapol_int_var var)
{
	return sm->eapol_cb->get_int(sm->eapol_ctx, var);
}


static void eapol_set_int(struct eap_sm *sm, enum eapol_int_var var,
			  unsigned int value)
{
	sm->eapol_cb->set_int(sm->eapol_ctx, var, value);
}


static u8 * eapol_get_eapReqData(struct eap_sm *sm, size_t *len)
{
	return sm->eapol_cb->get_eapReqData(sm->eapol_ctx, len);
}


static void eap_deinit_prev_method(struct eap_sm *sm, const char *txt)
{
	if (sm->m == NULL || sm->eap_method_priv == NULL)
		return;

	wpa_printf(MSG_DEBUG, "EAP: deinitialize previously used EAP method "
		   "(%d, %s) at %s", sm->selectedMethod, sm->m->name, txt);
	sm->m->deinit(sm, sm->eap_method_priv);
	sm->eap_method_priv = NULL;
	sm->m = NULL;
}


/*
 * This state initializes state machine variables when the machine is
 * activated (portEnabled = TRUE). This is also used when re-starting
 * authentication (eapRestart == TRUE).
 */
SM_STATE(EAP, INITIALIZE)
{
	SM_ENTRY(EAP, INITIALIZE);
	if (sm->fast_reauth && sm->m && sm->m->has_reauth_data &&
	    sm->m->has_reauth_data(sm, sm->eap_method_priv)) {
		wpa_printf(MSG_DEBUG, "EAP: maintaining EAP method data for "
			   "fast reauthentication");
		sm->m->deinit_for_reauth(sm, sm->eap_method_priv);
	} else {
		eap_deinit_prev_method(sm, "INITIALIZE");
	}
	sm->selectedMethod = EAP_TYPE_NONE;
	sm->methodState = METHOD_NONE;
	sm->allowNotifications = TRUE;
	sm->decision = DECISION_FAIL;
	eapol_set_int(sm, EAPOL_idleWhile, sm->ClientTimeout);
	eapol_set_bool(sm, EAPOL_eapSuccess, FALSE);
	eapol_set_bool(sm, EAPOL_eapFail, FALSE);
	free(sm->eapKeyData);
	sm->eapKeyData = NULL;
	sm->eapKeyAvailable = FALSE;
	eapol_set_bool(sm, EAPOL_eapRestart, FALSE);
	sm->lastId = -1; /* new session - make sure this does not match with
			  * the first EAP-Packet */
	/*
	 * RFC 4137 does not reset eapResp and eapNoResp here. However, this
	 * seemed to be able to trigger cases where both were set and if EAPOL
	 * state machine uses eapNoResp first, it may end up not sending a real
	 * reply correctly. This occurred when the workaround in FAIL state set
	 * eapNoResp = TRUE.. Maybe that workaround needs to be fixed to do
	 * something else(?)
	 */
	eapol_set_bool(sm, EAPOL_eapResp, FALSE);
	eapol_set_bool(sm, EAPOL_eapNoResp, FALSE);
	sm->num_rounds = 0;
}


/*
 * This state is reached whenever service from the lower layer is interrupted
 * or unavailable (portEnabled == FALSE). Immediate transition to INITIALIZE
 * occurs when the port becomes enabled.
 */
SM_STATE(EAP, DISABLED)
{
	SM_ENTRY(EAP, DISABLED);
	sm->num_rounds = 0;
}


/*
 * The state machine spends most of its time here, waiting for something to
 * happen. This state is entered unconditionally from INITIALIZE, DISCARD, and
 * SEND_RESPONSE states.
 */
SM_STATE(EAP, IDLE)
{
	SM_ENTRY(EAP, IDLE);
}


/*
 * This state is entered when an EAP packet is received (eapReq == TRUE) to
 * parse the packet header.
 */
SM_STATE(EAP, RECEIVED)
{
	const u8 *eapReqData;
	size_t eapReqDataLen;

	SM_ENTRY(EAP, RECEIVED);
	eapReqData = eapol_get_eapReqData(sm, &eapReqDataLen);
	/* parse rxReq, rxSuccess, rxFailure, reqId, reqMethod */
	eap_sm_parseEapReq(sm, eapReqData, eapReqDataLen);
	sm->num_rounds++;
}


/*
 * This state is entered when a request for a new type comes in. Either the
 * correct method is started, or a Nak response is built.
 */
SM_STATE(EAP, GET_METHOD)
{
	SM_ENTRY(EAP, GET_METHOD);
	if (eap_sm_allowMethod(sm, sm->reqMethod)) {
		int reinit = 0;
		/*
		 * RFC 4137 does not define specific operation for fast
		 * re-authentication (session resumption). The design here is
		 * to allow the previously used method data to be maintained
		 * for re-authentication if the method support session
		 * resumption. Otherwise, the previously used method data is
		 * freed and a new method is allocated here.
		 */
		if (sm->fast_reauth &&
		    sm->m && sm->m->method == sm->reqMethod &&
		    sm->m->has_reauth_data &&
		    sm->m->has_reauth_data(sm, sm->eap_method_priv)) {
			wpa_printf(MSG_DEBUG, "EAP: Using previous method data"
				   " for fast re-authentication");
			reinit = 1;
		} else
			eap_deinit_prev_method(sm, "GET_METHOD");
		sm->selectedMethod = sm->reqMethod;
		if (sm->m == NULL)
			sm->m = eap_sm_get_eap_methods(sm->selectedMethod);
		if (sm->m) {
			wpa_printf(MSG_DEBUG, "EAP: Initialize selected EAP "
				   "method (%d, %s)",
				   sm->selectedMethod, sm->m->name);
			if (reinit)
				sm->eap_method_priv = sm->m->init_for_reauth(
					sm, sm->eap_method_priv);
			else
				sm->eap_method_priv = sm->m->init(sm);
			if (sm->eap_method_priv == NULL) {
				struct wpa_ssid *config = eap_get_config(sm);
				wpa_msg(sm->msg_ctx, MSG_INFO,
					"EAP: Failed to initialize EAP method "
					"%d (%s)",
					sm->selectedMethod, sm->m->name);
				sm->m = NULL;
				sm->methodState = METHOD_NONE;
				sm->selectedMethod = EAP_TYPE_NONE;
				if (sm->reqMethod == EAP_TYPE_TLS &&
				    config &&
				    (config->pending_req_pin ||
				     config->pending_req_passphrase)) {
					/*
					 * Return without generating Nak in
					 * order to allow entering of PIN code
					 * or passphrase to retry the current
					 * EAP packet.
					 */
					wpa_printf(MSG_DEBUG, "EAP: Pending "
						   "PIN/passphrase request - "
						   "skip Nak");
					return;
				}
			} else {
				sm->methodState = METHOD_INIT;
				wpa_msg(sm->msg_ctx, MSG_INFO,
					WPA_EVENT_EAP_METHOD
					"EAP method %d (%s) selected",
					sm->selectedMethod, sm->m->name);
				return;
			}
		}
	}

	free(sm->eapRespData);
	sm->eapRespData = NULL;
	sm->eapRespData = eap_sm_buildNak(sm, sm->reqId, &sm->eapRespDataLen);
}


/*
 * The method processing happens here. The request from the authenticator is
 * processed, and an appropriate response packet is built.
 */
SM_STATE(EAP, METHOD)
{
	u8 *eapReqData;
	size_t eapReqDataLen;
	struct eap_method_ret ret;

	SM_ENTRY(EAP, METHOD);
	if (sm->m == NULL) {
		wpa_printf(MSG_WARNING, "EAP::METHOD - method not selected");
		return;
	}

	eapReqData = eapol_get_eapReqData(sm, &eapReqDataLen);

	/*
	 * Get ignore, methodState, decision, allowNotifications, and
	 * eapRespData. RFC 4137 uses three separate method procedure (check,
	 * process, and buildResp) in this state. These have been combined into
	 * a single function call to m->process() in order to optimize EAP
	 * method implementation interface a bit. These procedures are only
	 * used from within this METHOD state, so there is no need to keep
	 * these as separate C functions.
	 *
	 * The RFC 4137 procedures return values as follows:
	 * ignore = m.check(eapReqData)
	 * (methodState, decision, allowNotifications) = m.process(eapReqData)
	 * eapRespData = m.buildResp(reqId)
	 */
	memset(&ret, 0, sizeof(ret));
	ret.ignore = sm->ignore;
	ret.methodState = sm->methodState;
	ret.decision = sm->decision;
	ret.allowNotifications = sm->allowNotifications;
	free(sm->eapRespData);
	sm->eapRespData = NULL;
	sm->eapRespData = sm->m->process(sm, sm->eap_method_priv, &ret,
					 eapReqData, eapReqDataLen,
					 &sm->eapRespDataLen);
	wpa_printf(MSG_DEBUG, "EAP: method process -> ignore=%s "
		   "methodState=%s decision=%s",
		   ret.ignore ? "TRUE" : "FALSE",
		   eap_sm_method_state_txt(ret.methodState),
		   eap_sm_decision_txt(ret.decision));

	sm->ignore = ret.ignore;
	if (sm->ignore)
		return;
	sm->methodState = ret.methodState;
	sm->decision = ret.decision;
	sm->allowNotifications = ret.allowNotifications;

	if (sm->m->isKeyAvailable && sm->m->getKey &&
	    sm->m->isKeyAvailable(sm, sm->eap_method_priv)) {
		free(sm->eapKeyData);
		sm->eapKeyData = sm->m->getKey(sm, sm->eap_method_priv,
					       &sm->eapKeyDataLen);
	}
}


/*
 * This state signals the lower layer that a response packet is ready to be
 * sent.
 */
SM_STATE(EAP, SEND_RESPONSE)
{
	SM_ENTRY(EAP, SEND_RESPONSE);
	free(sm->lastRespData);
	if (sm->eapRespData) {
		if (sm->workaround)
			memcpy(sm->last_md5, sm->req_md5, 16);
		sm->lastId = sm->reqId;
		sm->lastRespData = malloc(sm->eapRespDataLen);
		if (sm->lastRespData) {
			memcpy(sm->lastRespData, sm->eapRespData,
			       sm->eapRespDataLen);
			sm->lastRespDataLen = sm->eapRespDataLen;
		}
		eapol_set_bool(sm, EAPOL_eapResp, TRUE);
	} else
		sm->lastRespData = NULL;
	eapol_set_bool(sm, EAPOL_eapReq, FALSE);
	eapol_set_int(sm, EAPOL_idleWhile, sm->ClientTimeout);
}


/*
 * This state signals the lower layer that the request was discarded, and no
 * response packet will be sent at this time.
 */
SM_STATE(EAP, DISCARD)
{
	SM_ENTRY(EAP, DISCARD);
	eapol_set_bool(sm, EAPOL_eapReq, FALSE);
	eapol_set_bool(sm, EAPOL_eapNoResp, TRUE);
}


/*