hostapd/src/eap_common/eap_fast_common.c

/*
 * EAP-FAST common helper functions (RFC 4851)
 * Copyright (c) 2008, Jouni Malinen <j@w1.fi>
 *
 * 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 "tls.h"
#include "eap_defs.h"
#include "eap_tlv_common.h"
#include "eap_fast_common.h"


void eap_fast_put_tlv_hdr(struct wpabuf *buf, u16 type, u16 len)
{
	struct pac_tlv_hdr hdr;
	hdr.type = host_to_be16(type);
	hdr.len = host_to_be16(len);
	wpabuf_put_data(buf, &hdr, sizeof(hdr));
}


void eap_fast_put_tlv(struct wpabuf *buf, u16 type, const void *data,
			     u16 len)
{
	eap_fast_put_tlv_hdr(buf, type, len);
	wpabuf_put_data(buf, data, len);
}


void eap_fast_put_tlv_buf(struct wpabuf *buf, u16 type,
				 const struct wpabuf *data)
{
	eap_fast_put_tlv_hdr(buf, type, wpabuf_len(data));
	wpabuf_put_buf(buf, data);
}


struct wpabuf * eap_fast_tlv_eap_payload(struct wpabuf *buf)
{
	struct wpabuf *e;

	if (buf == NULL)
		return NULL;

	/* Encapsulate EAP packet in EAP-Payload TLV */
	wpa_printf(MSG_DEBUG, "EAP-FAST: Add EAP-Payload TLV");
	e = wpabuf_alloc(sizeof(struct pac_tlv_hdr) + wpabuf_len(buf));
	if (e == NULL) {
		wpa_printf(MSG_DEBUG, "EAP-FAST: Failed to allocate memory "
			   "for TLV encapsulation");
		wpabuf_free(buf);
		return NULL;
	}
	eap_fast_put_tlv_buf(e,
			     EAP_TLV_TYPE_MANDATORY | EAP_TLV_EAP_PAYLOAD_TLV,
			     buf);
	wpabuf_free(buf);
	return e;
}


void eap_fast_derive_master_secret(const u8 *pac_key, const u8 *server_random,
				   const u8 *client_random, u8 *master_secret)
{
#define TLS_RANDOM_LEN 32
#define TLS_MASTER_SECRET_LEN 48
	u8 seed[2 * TLS_RANDOM_LEN];

	wpa_hexdump(MSG_DEBUG, "EAP-FAST: client_random",
		    client_random, TLS_RANDOM_LEN);
	wpa_hexdump(MSG_DEBUG, "EAP-FAST: server_random",
		    server_random, TLS_RANDOM_LEN);

	/*
	 * RFC 4851, Section 5.1:
	 * master_secret = T-PRF(PAC-Key, "PAC to master secret label hash", 
	 *                       server_random + client_random, 48)
	 */
	os_memcpy(seed, server_random, TLS_RANDOM_LEN);
	os_memcpy(seed + TLS_RANDOM_LEN, client_random, TLS_RANDOM_LEN);
	sha1_t_prf(pac_key, EAP_FAST_PAC_KEY_LEN,
		   "PAC to master secret label hash",
		   seed, sizeof(seed), master_secret, TLS_MASTER_SECRET_LEN);

	wpa_hexdump_key(MSG_DEBUG, "EAP-FAST: master_secret",
			master_secret, TLS_MASTER_SECRET_LEN);
}


u8 * eap_fast_derive_key(void *ssl_ctx, struct tls_connection *conn,
			 const char *label, size_t len)
{
	struct tls_keys keys;
	u8 *rnd = NULL, *out;
	int block_size;

	block_size = tls_connection_get_keyblock_size(ssl_ctx, conn);
	if (block_size < 0)
		return NULL;

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

	if (tls_connection_prf(ssl_ctx, conn, label, 1, out, block_size + len)
	    == 0) {
		os_memmove(out, out + block_size, len);
		return out;
	}

	if (tls_connection_get_keys(ssl_ctx, conn, &keys))
		goto fail;

	rnd = os_malloc(keys.client_random_len + keys.server_random_len);
	if (rnd == NULL)
		goto fail;

	os_memcpy(rnd, keys.server_random, keys.server_random_len);
	os_memcpy(rnd + keys.server_random_len, keys.client_random,
		  keys.client_random_len);

	wpa_hexdump_key(MSG_MSGDUMP, "EAP-FAST: master_secret for key "
			"expansion", keys.master_key, keys.master_key_len);
	if (tls_prf(keys.master_key, keys.master_key_len,
		    label, rnd, keys.client_random_len +
		    keys.server_random_len, out, block_size + len))
		goto fail;
	os_free(rnd);
	os_memmove(out, out + block_size, len);
	return out;

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


void eap_fast_derive_eap_msk(const u8 *simck, u8 *msk)
{
	/*
	 * RFC 4851, Section 5.4: EAP Master Session Key Generation
	 * MSK = T-PRF(S-IMCK[j], "Session Key Generating Function", 64)
	 */

	sha1_t_prf(simck, EAP_FAST_SIMCK_LEN,
		   "Session Key Generating Function", (u8 *) "", 0,
		   msk, EAP_FAST_KEY_LEN);
	wpa_hexdump_key(MSG_DEBUG, "EAP-FAST: Derived key (MSK)",
			msk, EAP_FAST_KEY_LEN);
}


void eap_fast_derive_eap_emsk(const u8 *simck, u8 *emsk)
{
	/*
	 * RFC 4851, Section 5.4: EAP Master Session Key Genreration
	 * EMSK = T-PRF(S-IMCK[j],
	 *        "Extended Session Key Generating Function", 64)
	 */

	sha1_t_prf(simck, EAP_FAST_SIMCK_LEN,
		   "Extended Session Key Generating Function", (u8 *) "", 0,
		   emsk, EAP_EMSK_LEN);
	wpa_hexdump_key(MSG_DEBUG, "EAP-FAST: Derived key (EMSK)",
			emsk, EAP_EMSK_LEN);
}


int eap_fast_parse_tlv(struct eap_fast_tlv_parse *tlv,
		       int tlv_type, u8 *pos, int len)
{
	switch (tlv_type) {
	case EAP_TLV_EAP_PAYLOAD_TLV:
		wpa_hexdump(MSG_MSGDUMP, "EAP-FAST: EAP-Payload TLV",
			    pos, len);
		if (tlv->eap_payload_tlv) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: More than one "
				   "EAP-Payload TLV in the message");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			return -2;
		}
		tlv->eap_payload_tlv = pos;
		tlv->eap_payload_tlv_len = len;
		break;
	case EAP_TLV_RESULT_TLV:
		wpa_hexdump(MSG_MSGDUMP, "EAP-FAST: Result TLV", pos, len);
		if (tlv->result) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: More than one "
				   "Result TLV in the message");
			tlv->result = EAP_TLV_RESULT_FAILURE;
			return -2;
		}
		if (len < 2) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: Too short "
				   "Result TLV");
			tlv->result = EAP_TLV_RESULT_FAILURE;
			break;
		}
		tlv->result = WPA_GET_BE16(pos);
		if (tlv->result != EAP_TLV_RESULT_SUCCESS &&
		    tlv->result != EAP_TLV_RESULT_FAILURE) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: Unknown Result %d",
				   tlv->result);
			tlv->result = EAP_TLV_RESULT_FAILURE;
		}
		wpa_printf(MSG_DEBUG, "EAP-FAST: Result: %s",
			   tlv->result == EAP_TLV_RESULT_SUCCESS ?
			   "Success" : "Failure");
		break;
	case EAP_TLV_INTERMEDIATE_RESULT_TLV:
		wpa_hexdump(MSG_MSGDUMP, "EAP-FAST: Intermediate Result TLV",
			    pos, len);
		if (len < 2) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: Too short "
				   "Intermediate-Result TLV");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			break;
		}
		if (tlv->iresult) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: More than one "
				   "Intermediate-Result TLV in the message");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			return -2;
		}
		tlv->iresult = WPA_GET_BE16(pos);
		if (tlv->iresult != EAP_TLV_RESULT_SUCCESS &&
		    tlv->iresult != EAP_TLV_RESULT_FAILURE) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: Unknown Intermediate "
				   "Result %d", tlv->iresult);
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
		}
		wpa_printf(MSG_DEBUG, "EAP-FAST: Intermediate Result: %s",
			   tlv->iresult == EAP_TLV_RESULT_SUCCESS ?
			   "Success" : "Failure");
		break;
	case EAP_TLV_CRYPTO_BINDING_TLV:
		wpa_hexdump(MSG_MSGDUMP, "EAP-FAST: Crypto-Binding TLV",
			    pos, len);
		if (tlv->crypto_binding) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: More than one "
				   "Crypto-Binding TLV in the message");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			return -2;
		}
		tlv->crypto_binding_len = sizeof(struct eap_tlv_hdr) + len;
		if (tlv->crypto_binding_len < sizeof(*tlv->crypto_binding)) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: Too short "
				   "Crypto-Binding TLV");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			return -2;
		}
		tlv->crypto_binding = (struct eap_tlv_crypto_binding_tlv *)
			(pos - sizeof(struct eap_tlv_hdr));
		break;
	case EAP_TLV_REQUEST_ACTION_TLV:
		wpa_hexdump(MSG_MSGDUMP, "EAP-FAST: Request-Action TLV",
			    pos, len);
		if (tlv->request_action) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: More than one "
				   "Request-Action TLV in the message");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			return -2;
		}
		if (len < 2) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: Too short "
				   "Request-Action TLV");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			break;
		}
		tlv->request_action = WPA_GET_BE16(pos);
		wpa_printf(MSG_DEBUG, "EAP-FAST: Request-Action: %d",
			   tlv->request_action);
		break;
	case EAP_TLV_PAC_TLV:
		wpa_hexdump(MSG_MSGDUMP, "EAP-FAST: PAC TLV", pos, len);
		if (tlv->pac) {
			wpa_printf(MSG_DEBUG, "EAP-FAST: More than one "
				   "PAC TLV in the message");
			tlv->iresult = EAP_TLV_RESULT_FAILURE;
			return -2;
		}
		tlv->pac = pos;
		tlv->pac_len = len;
		break;
	default:
		/* Unknown TLV */
		return -1;
	}

	return 0;
}