eap_peap.c

IEEE 802.11a/b/g 服务器端AP

/*
 * hostapd / EAP-PEAP (draft-josefsson-pppext-eap-tls-eap-10.txt)
 * Copyright (c) 2004-2008, 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 "sha1.h"
#include "eap_i.h"
#include "eap_tls_common.h"
#include "eap_common/eap_tlv_common.h"
#include "eap_common/eap_peap_common.h"
#include "tls.h"
#include "tncs.h"


/* Maximum supported PEAP version
 * 0 = Microsoft's PEAP version 0; draft-kamath-pppext-peapv0-00.txt
 * 1 = draft-josefsson-ppext-eap-tls-eap-05.txt
 * 2 = draft-josefsson-ppext-eap-tls-eap-10.txt
 */
#define EAP_PEAP_VERSION 1


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


struct eap_peap_data {
	struct eap_ssl_data ssl;
	enum {
		START, PHASE1, PHASE1_ID2, PHASE2_START, PHASE2_ID,
		PHASE2_METHOD, PHASE2_SOH,
		PHASE2_TLV, SUCCESS_REQ, FAILURE_REQ, SUCCESS, FAILURE
	} state;

	int peap_version;
	int recv_version;
	const struct eap_method *phase2_method;
	void *phase2_priv;
	int force_version;
	struct wpabuf *pending_phase2_resp;
	enum { TLV_REQ_NONE, TLV_REQ_SUCCESS, TLV_REQ_FAILURE } tlv_request;
	int crypto_binding_sent;
	int crypto_binding_used;
	enum { NO_BINDING, OPTIONAL_BINDING, REQUIRE_BINDING } crypto_binding;
	u8 binding_nonce[32];
	u8 ipmk[40];
	u8 cmk[20];
	u8 *phase2_key;
	size_t phase2_key_len;
	struct wpabuf *soh_response;
};


static const char * eap_peap_state_txt(int state)
{
	switch (state) {
	case START:
		return "START";
	case PHASE1:
		return "PHASE1";
	case PHASE1_ID2:
		return "PHASE1_ID2";
	case PHASE2_START:
		return "PHASE2_START";
	case PHASE2_ID:
		return "PHASE2_ID";
	case PHASE2_METHOD:
		return "PHASE2_METHOD";
	case PHASE2_SOH:
		return "PHASE2_SOH";
	case PHASE2_TLV:
		return "PHASE2_TLV";
	case SUCCESS_REQ:
		return "SUCCESS_REQ";
	case FAILURE_REQ:
		return "FAILURE_REQ";
	case SUCCESS:
		return "SUCCESS";
	case FAILURE:
		return "FAILURE";
	default:
		return "Unknown?!";
	}
}


static void eap_peap_state(struct eap_peap_data *data, int state)
{
	wpa_printf(MSG_DEBUG, "EAP-PEAP: %s -> %s",
		   eap_peap_state_txt(data->state),
		   eap_peap_state_txt(state));
	data->state = state;
}


static struct wpabuf * eap_peapv2_tlv_eap_payload(struct wpabuf *buf)
{
	struct wpabuf *e;
	struct eap_tlv_hdr *tlv;

	if (buf == NULL)
		return NULL;

	/* Encapsulate EAP packet in EAP-Payload TLV */
	wpa_printf(MSG_DEBUG, "EAP-PEAPv2: Add EAP-Payload TLV");
	e = wpabuf_alloc(sizeof(*tlv) + wpabuf_len(buf));
	if (e == NULL) {
		wpa_printf(MSG_DEBUG, "EAP-PEAPv2: Failed to allocate memory "
			   "for TLV encapsulation");
		wpabuf_free(buf);
		return NULL;
	}
	tlv = wpabuf_put(e, sizeof(*tlv));
	tlv->tlv_type = host_to_be16(EAP_TLV_TYPE_MANDATORY |
				     EAP_TLV_EAP_PAYLOAD_TLV);
	tlv->length = host_to_be16(wpabuf_len(buf));
	wpabuf_put_buf(e, buf);
	wpabuf_free(buf);
	return e;
}


static void eap_peap_req_success(struct eap_sm *sm,
				 struct eap_peap_data *data)
{
	if (data->state == FAILURE || data->state == FAILURE_REQ) {
		eap_peap_state(data, FAILURE);
		return;
	}

	if (data->peap_version == 0) {
		data->tlv_request = TLV_REQ_SUCCESS;
		eap_peap_state(data, PHASE2_TLV);
	} else {
		eap_peap_state(data, SUCCESS_REQ);
	}
}


static void eap_peap_req_failure(struct eap_sm *sm,
				 struct eap_peap_data *data)
{
	if (data->state == FAILURE || data->state == FAILURE_REQ ||
	    data->state == SUCCESS_REQ || data->tlv_request != TLV_REQ_NONE) {
		eap_peap_state(data, FAILURE);
		return;
	}

	if (data->peap_version == 0) {
		data->tlv_request = TLV_REQ_FAILURE;
		eap_peap_state(data, PHASE2_TLV);
	} else {
		eap_peap_state(data, FAILURE_REQ);
	}
}


static void * eap_peap_init(struct eap_sm *sm)
{
	struct eap_peap_data *data;

	data = os_zalloc(sizeof(*data));
	if (data == NULL)
		return NULL;
	data->peap_version = EAP_PEAP_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-PEAP: forcing version %d",
			   data->force_version);
		data->peap_version = data->force_version;
	}
	data->state = START;
	data->crypto_binding = OPTIONAL_BINDING;

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

	return data;
}


static void eap_peap_reset(struct eap_sm *sm, void *priv)
{
	struct eap_peap_data *data = priv;
	if (data == NULL)
		return;
	if (data->phase2_priv && data->phase2_method)
		data->phase2_method->reset(sm, data->phase2_priv);
	eap_server_tls_ssl_deinit(sm, &data->ssl);
	wpabuf_free(data->pending_phase2_resp);
	os_free(data->phase2_key);
	wpabuf_free(data->soh_response);
	os_free(data);
}


static struct wpabuf * eap_peap_build_start(struct eap_sm *sm,
					    struct eap_peap_data *data, u8 id)
{
	struct wpabuf *req;

	req = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_PEAP, 1,
			    EAP_CODE_REQUEST, id);
	if (req == NULL) {
		wpa_printf(MSG_ERROR, "EAP-PEAP: Failed to allocate memory for"
			   " request");
		eap_peap_state(data, FAILURE);
		return NULL;
	}

	wpabuf_put_u8(req, EAP_TLS_FLAGS_START | data->peap_version);

	eap_peap_state(data, PHASE1);

	return req;
}


static struct wpabuf * eap_peap_build_phase2_req(struct eap_sm *sm,
						 struct eap_peap_data *data,
						 u8 id)
{
	struct wpabuf *buf, *encr_req;
	const u8 *req;
	size_t req_len;

	if (data->phase2_method == NULL || data->phase2_priv == NULL) {
		wpa_printf(MSG_DEBUG, "EAP-PEAP: Phase 2 method not ready");
		return NULL;
	}
	buf = data->phase2_method->buildReq(sm, data->phase2_priv, id);
	if (data->peap_version >= 2 && buf)
		buf = eap_peapv2_tlv_eap_payload(buf);
	if (buf == NULL)
		return NULL;

	req = wpabuf_head(buf);
	req_len = wpabuf_len(buf);
	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: Encrypting Phase 2 data",
			req, req_len);

	if (data->peap_version == 0 &&
	    data->phase2_method->method != EAP_TYPE_TLV) {
		req += sizeof(struct eap_hdr);
		req_len -= sizeof(struct eap_hdr);
	}

	encr_req = eap_server_tls_encrypt(sm, &data->ssl, req, req_len);
	wpabuf_free(buf);

	return encr_req;
}


#ifdef EAP_TNC
static struct wpabuf * eap_peap_build_phase2_soh(struct eap_sm *sm,
						 struct eap_peap_data *data,
						 u8 id)
{
	struct wpabuf *buf1, *buf, *encr_req;
	const u8 *req;
	size_t req_len;

	buf1 = tncs_build_soh_request();
	if (buf1 == NULL)
		return NULL;

	buf = eap_msg_alloc(EAP_VENDOR_MICROSOFT, 0x21, wpabuf_len(buf1),
			    EAP_CODE_REQUEST, id);
	if (buf == NULL) {
		wpabuf_free(buf1);
		return NULL;
	}
	wpabuf_put_buf(buf, buf1);
	wpabuf_free(buf1);

	req = wpabuf_head(buf);
	req_len = wpabuf_len(buf);

	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: Encrypting Phase 2 SOH data",
			req, req_len);

	req += sizeof(struct eap_hdr);
	req_len -= sizeof(struct eap_hdr);

	encr_req = eap_server_tls_encrypt(sm, &data->ssl, req, req_len);
	wpabuf_free(buf);

	return encr_req;
}
#endif /* EAP_TNC */


static void eap_peap_get_isk(struct eap_peap_data *data,
			     u8 *isk, size_t isk_len)
{
	size_t key_len;

	os_memset(isk, 0, isk_len);
	if (data->phase2_key == NULL)
		return;

	key_len = data->phase2_key_len;
	if (key_len > isk_len)
		key_len = isk_len;
	os_memcpy(isk, data->phase2_key, key_len);
}


static int eap_peap_derive_cmk(struct eap_sm *sm, struct eap_peap_data *data)
{
	u8 *tk;
	u8 isk[32], imck[60];

	/*
	 * Tunnel key (TK) is the first 60 octets of the key generated by
	 * phase 1 of PEAP (based on TLS).
	 */
	tk = eap_server_tls_derive_key(sm, &data->ssl, "client EAP encryption",
				       EAP_TLS_KEY_LEN);
	if (tk == NULL)
		return -1;
	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: TK", tk, 60);

	eap_peap_get_isk(data, isk, sizeof(isk));
	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: ISK", isk, sizeof(isk));

	/*
	 * IPMK Seed = "Inner Methods Compound Keys" | ISK
	 * TempKey = First 40 octets of TK
	 * IPMK|CMK = PRF+(TempKey, IPMK Seed, 60)
	 * (note: draft-josefsson-pppext-eap-tls-eap-10.txt includes a space
	 * in the end of the label just before ISK; is that just a typo?)
	 */
	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: TempKey", tk, 40);
	peap_prfplus(data->peap_version, tk, 40, "Inner Methods Compound Keys",
		     isk, sizeof(isk), imck, sizeof(imck));
	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: IMCK (IPMKj)",
			imck, sizeof(imck));

	os_free(tk);

	/* TODO: fast-connect: IPMK|CMK = TK */
	os_memcpy(data->ipmk, imck, 40);
	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: IPMK (S-IPMKj)", data->ipmk, 40);
	os_memcpy(data->cmk, imck + 40, 20);
	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: CMK (CMKj)", data->cmk, 20);

	return 0;
}


static struct wpabuf * eap_peap_build_phase2_tlv(struct eap_sm *sm,
						 struct eap_peap_data *data,
						 u8 id)
{
	struct wpabuf *buf, *encr_req;
	size_t len;

	len = 6; /* Result TLV */
	if (data->crypto_binding != NO_BINDING)
		len += 60; /* Cryptobinding TLV */
#ifdef EAP_TNC
	if (data->soh_response)
		len += wpabuf_len(data->soh_response);
#endif /* EAP_TNC */

	buf = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TLV, len,
			    EAP_CODE_REQUEST, id);
	if (buf == NULL)
		return NULL;

	wpabuf_put_u8(buf, 0x80); /* Mandatory */
	wpabuf_put_u8(buf, EAP_TLV_RESULT_TLV);
	/* Length */
	wpabuf_put_be16(buf, 2);
	/* Status */
	wpabuf_put_be16(buf, data->tlv_request == TLV_REQ_SUCCESS ?
			EAP_TLV_RESULT_SUCCESS : EAP_TLV_RESULT_FAILURE);

	if (data->peap_version == 0 && data->tlv_request == TLV_REQ_SUCCESS &&
	    data->crypto_binding != NO_BINDING) {
		u8 *mac;
		u8 eap_type = EAP_TYPE_PEAP;
		const u8 *addr[2];
		size_t len[2];
		u16 tlv_type;

#ifdef EAP_TNC
		if (data->soh_response) {
			wpa_printf(MSG_DEBUG, "EAP-PEAP: Adding MS-SOH "
				   "Response TLV");
			wpabuf_put_buf(buf, data->soh_response);
			wpabuf_free(data->soh_response);
			data->soh_response = NULL;
		}
#endif /* EAP_TNC */

		if (eap_peap_derive_cmk(sm, data) < 0 ||
		    os_get_random(data->binding_nonce, 32)) {
			wpabuf_free(buf);
			return NULL;
		}

		/* Compound_MAC: HMAC-SHA1-160(cryptobinding TLV | EAP type) */
		addr[0] = wpabuf_put(buf, 0);
		len[0] = 60;
		addr[1] = &eap_type;
		len[1] = 1;

		tlv_type = EAP_TLV_CRYPTO_BINDING_TLV;
		if (data->peap_version >= 2)
			tlv_type |= EAP_TLV_TYPE_MANDATORY;
		wpabuf_put_be16(buf, tlv_type);
		wpabuf_put_be16(buf, 56);

		wpabuf_put_u8(buf, 0); /* Reserved */
		wpabuf_put_u8(buf, data->peap_version); /* Version */
		wpabuf_put_u8(buf, data->recv_version); /* RecvVersion */
		wpabuf_put_u8(buf, 0); /* SubType: 0 = Request, 1 = Response */
		wpabuf_put_data(buf, data->binding_nonce, 32); /* Nonce */
		mac = wpabuf_put(buf, 20); /* Compound_MAC */
		wpa_hexdump(MSG_MSGDUMP, "EAP-PEAP: Compound_MAC CMK",
			    data->cmk, 20);
		wpa_hexdump(MSG_MSGDUMP, "EAP-PEAP: Compound_MAC data 1",
			    addr[0], len[0]);
		wpa_hexdump(MSG_MSGDUMP, "EAP-PEAP: Compound_MAC data 2",
			    addr[1], len[1]);
		hmac_sha1_vector(data->cmk, 20, 2, addr, len, mac);
		wpa_hexdump(MSG_MSGDUMP, "EAP-PEAP: Compound_MAC",
			    mac, SHA1_MAC_LEN);
		data->crypto_binding_sent = 1;
	}

	wpa_hexdump_buf_key(MSG_DEBUG, "EAP-PEAP: Encrypting Phase 2 TLV data",
			    buf);

	encr_req = eap_server_tls_encrypt(sm, &data->ssl, wpabuf_head(buf),
					  wpabuf_len(buf));
	wpabuf_free(buf);

	return encr_req;
}


static struct wpabuf * eap_peap_build_phase2_term(struct eap_sm *sm,
						  struct eap_peap_data *data,
						  u8 id, int success)
{
	struct wpabuf *encr_req;
	size_t req_len;
	struct eap_hdr *hdr;

	req_len = sizeof(*hdr);
	hdr = os_zalloc(req_len);
	if (hdr == NULL)
		return NULL;

	hdr->code = success ? EAP_CODE_SUCCESS : EAP_CODE_FAILURE;
	hdr->identifier = id;
	hdr->length = host_to_be16(req_len);

	wpa_hexdump_key(MSG_DEBUG, "EAP-PEAP: Encrypting Phase 2 data",
			(u8 *) hdr, req_len);