306 lines
7.3 KiB
C
306 lines
7.3 KiB
C
/*
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* Copyright (C) 2007 Martin Willi
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* Hochschule fuer Technik Rapperswil
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* $Id$
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*/
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#include "eap_md5.h"
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#include <daemon.h>
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#include <library.h>
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#include <crypto/hashers/hasher.h>
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typedef struct private_eap_md5_t private_eap_md5_t;
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/**
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* Private data of an eap_md5_t object.
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*/
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struct private_eap_md5_t {
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/**
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* Public authenticator_t interface.
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*/
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eap_md5_t public;
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/**
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* ID of the server
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*/
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identification_t *server;
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/**
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* ID of the peer
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*/
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identification_t *peer;
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/**
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* challenge sent by the server
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*/
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chunk_t challenge;
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/**
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* EAP message identififier
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*/
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u_int8_t identifier;
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};
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typedef struct eap_md5_header_t eap_md5_header_t;
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/**
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* packed eap MD5 header struct
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*/
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struct eap_md5_header_t {
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/** EAP code (REQUEST/RESPONSE) */
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u_int8_t code;
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/** unique message identifier */
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u_int8_t identifier;
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/** length of whole message */
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u_int16_t length;
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/** EAP type */
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u_int8_t type;
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/** length of value (challenge) */
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u_int8_t value_size;
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/** actual value */
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u_int8_t value[];
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} __attribute__((__packed__));
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#define CHALLENGE_LEN 16
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#define PAYLOAD_LEN (CHALLENGE_LEN + sizeof(eap_md5_header_t))
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/**
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* Hash the challenge string, create response
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*/
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static status_t hash_challenge(private_eap_md5_t *this, chunk_t *response)
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{
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shared_key_t *shared;
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chunk_t concat;
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hasher_t *hasher;
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shared = charon->credentials->get_shared(charon->credentials, SHARED_EAP,
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this->server, this->peer);
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if (shared == NULL)
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{
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DBG1(DBG_IKE, "no EAP key found for hosts '%D' - '%D'",
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this->server, this->peer);
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return NOT_FOUND;
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}
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concat = chunk_cata("ccc", chunk_from_thing(this->identifier),
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shared->get_key(shared), this->challenge);
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shared->destroy(shared);
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hasher = lib->crypto->create_hasher(lib->crypto, HASH_MD5);
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if (hasher == NULL)
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{
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DBG1(DBG_IKE, "EAP-MD5 failed, MD5 not supported");
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return FAILED;
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}
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hasher->allocate_hash(hasher, concat, response);
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hasher->destroy(hasher);
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return SUCCESS;
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}
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/**
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* Implementation of eap_method_t.initiate for the peer
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*/
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static status_t initiate_peer(private_eap_md5_t *this, eap_payload_t **out)
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{
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/* peer never initiates */
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return FAILED;
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}
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/**
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* Implementation of eap_method_t.initiate for the server
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*/
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static status_t initiate_server(private_eap_md5_t *this, eap_payload_t **out)
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{
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rng_t *rng;
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eap_md5_header_t *req;
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rng = lib->crypto->create_rng(lib->crypto, RNG_WEAK);
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if (!rng)
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{
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return FAILED;
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}
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rng->allocate_bytes(rng, CHALLENGE_LEN, &this->challenge);
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rng->destroy(rng);
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req = alloca(PAYLOAD_LEN);
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req->length = htons(PAYLOAD_LEN);
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req->code = EAP_REQUEST;
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req->identifier = this->identifier;
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req->type = EAP_MD5;
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req->value_size = this->challenge.len;
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memcpy(req->value, this->challenge.ptr, this->challenge.len);
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*out = eap_payload_create_data(chunk_create((void*)req, PAYLOAD_LEN));
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return NEED_MORE;
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}
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/**
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* Implementation of eap_method_t.process for the peer
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*/
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static status_t process_peer(private_eap_md5_t *this,
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eap_payload_t *in, eap_payload_t **out)
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{
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chunk_t response;
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chunk_t data;
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eap_md5_header_t *req;
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this->identifier = in->get_identifier(in);
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data = in->get_data(in);
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this->challenge = chunk_clone(chunk_skip(data, 6));
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if (data.len < 6 || this->challenge.len < *(data.ptr + 5))
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{
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DBG1(DBG_IKE, "received invalid EAP-MD5 message");
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return FAILED;
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}
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if (hash_challenge(this, &response) != SUCCESS)
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{
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return FAILED;
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}
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req = alloca(PAYLOAD_LEN);
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req->length = htons(PAYLOAD_LEN);
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req->code = EAP_RESPONSE;
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req->identifier = this->identifier;
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req->type = EAP_MD5;
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req->value_size = response.len;
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memcpy(req->value, response.ptr, response.len);
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chunk_free(&response);
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*out = eap_payload_create_data(chunk_create((void*)req, PAYLOAD_LEN));
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return NEED_MORE;
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}
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/**
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* Implementation of eap_method_t.process for the server
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*/
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static status_t process_server(private_eap_md5_t *this,
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eap_payload_t *in, eap_payload_t **out)
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{
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chunk_t response, expected;
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chunk_t data;
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if (this->identifier != in->get_identifier(in))
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{
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DBG1(DBG_IKE, "received invalid EAP-MD5 message");
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return FAILED;
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}
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if (hash_challenge(this, &expected) != SUCCESS)
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{
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return FAILED;
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}
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data = in->get_data(in);
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response = chunk_skip(data, 6);
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if (response.len < expected.len ||
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!memeq(response.ptr, expected.ptr, expected.len))
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{
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chunk_free(&expected);
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DBG1(DBG_IKE, "EAP-MD5 verification failed");
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return FAILED;
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}
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chunk_free(&expected);
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return SUCCESS;
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}
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/**
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* Implementation of eap_method_t.get_type.
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*/
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static eap_type_t get_type(private_eap_md5_t *this, u_int32_t *vendor)
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{
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*vendor = 0;
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return EAP_MD5;
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}
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/**
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* Implementation of eap_method_t.get_msk.
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*/
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static status_t get_msk(private_eap_md5_t *this, chunk_t *msk)
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{
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return FAILED;
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}
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/**
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* Implementation of eap_method_t.is_mutual.
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*/
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static bool is_mutual(private_eap_md5_t *this)
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{
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return FALSE;
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}
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/**
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* Implementation of eap_method_t.destroy.
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*/
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static void destroy(private_eap_md5_t *this)
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{
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this->peer->destroy(this->peer);
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this->server->destroy(this->server);
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chunk_free(&this->challenge);
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free(this);
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}
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/**
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* Generic constructor
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*/
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static private_eap_md5_t *eap_md5_create_generic(identification_t *server,
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identification_t *peer)
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{
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private_eap_md5_t *this = malloc_thing(private_eap_md5_t);
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this->public.eap_method_interface.initiate = NULL;
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this->public.eap_method_interface.process = NULL;
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this->public.eap_method_interface.get_type = (eap_type_t(*)(eap_method_t*,u_int32_t*))get_type;
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this->public.eap_method_interface.is_mutual = (bool(*)(eap_method_t*))is_mutual;
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this->public.eap_method_interface.get_msk = (status_t(*)(eap_method_t*,chunk_t*))get_msk;
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this->public.eap_method_interface.destroy = (void(*)(eap_method_t*))destroy;
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/* private data */
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this->peer = peer->clone(peer);
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this->server = server->clone(server);
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this->challenge = chunk_empty;
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this->identifier = 0;
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return this;
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}
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/*
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* see header
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*/
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eap_md5_t *eap_md5_create_server(identification_t *server, identification_t *peer)
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{
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private_eap_md5_t *this = eap_md5_create_generic(server, peer);
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this->public.eap_method_interface.initiate = (status_t(*)(eap_method_t*,eap_payload_t**))initiate_server;
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this->public.eap_method_interface.process = (status_t(*)(eap_method_t*,eap_payload_t*,eap_payload_t**))process_server;
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/* generate a non-zero identifier */
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do {
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this->identifier = random();
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} while (!this->identifier);
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return &this->public;
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}
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/*
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* see header
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*/
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eap_md5_t *eap_md5_create_peer(identification_t *server, identification_t *peer)
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{
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private_eap_md5_t *this = eap_md5_create_generic(server, peer);
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this->public.eap_method_interface.initiate = (status_t(*)(eap_method_t*,eap_payload_t**))initiate_peer;
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this->public.eap_method_interface.process = (status_t(*)(eap_method_t*,eap_payload_t*,eap_payload_t**))process_peer;
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return &this->public;
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}
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