kx509.c

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/*
 * Copyright (c) 2006 - 2007 Kungliga Tekniska H鰃skolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 *
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 */

#include "kdc_locl.h"
#include <hex.h>
#include <rfc2459_asn1.h>
#include <hx509.h>

RCSID("$Id: kx509.c 21607 2007-07-17 07:04:52Z lha $");

/*
 *
 */

krb5_error_code
_kdc_try_kx509_request(void *ptr, size_t len, Kx509Request *req, size_t *size)
{
    if (len < 4)
	return -1;
    if (memcmp("\x00\x00\x02\x00", ptr, 4) != 0)
	return -1;
    return decode_Kx509Request(((unsigned char *)ptr) + 4, len - 4, req, size);
}

/*
 *
 */

static const unsigned char version_2_0[4] = {0 , 0, 2, 0};

static krb5_error_code
verify_req_hash(krb5_context context, 
		const Kx509Request *req,
		krb5_keyblock *key)
{
    unsigned char digest[SHA_DIGEST_LENGTH];
    HMAC_CTX ctx;
    
    if (req->pk_hash.length != sizeof(digest)) {
	krb5_set_error_string(context, "pk-hash have wrong length: %lu",
			      (unsigned long)req->pk_hash.length);
	return KRB5KDC_ERR_PREAUTH_FAILED;
    }

    HMAC_CTX_init(&ctx);
    HMAC_Init_ex(&ctx, 
		 key->keyvalue.data, key->keyvalue.length, 
		 EVP_sha1(), NULL);
    if (sizeof(digest) != HMAC_size(&ctx))
	krb5_abortx(context, "runtime error, hmac buffer wrong size in kx509");
    HMAC_Update(&ctx, version_2_0, sizeof(version_2_0));
    HMAC_Update(&ctx, req->pk_key.data, req->pk_key.length);
    HMAC_Final(&ctx, digest, 0);
    HMAC_CTX_cleanup(&ctx);

    if (memcmp(req->pk_hash.data, digest, sizeof(digest)) != 0) {
	krb5_set_error_string(context, "pk-hash is not correct");
	return KRB5KDC_ERR_PREAUTH_FAILED;
    }
    return 0;
}

static krb5_error_code
calculate_reply_hash(krb5_context context,
		     krb5_keyblock *key,
		     Kx509Response *rep)
{
    HMAC_CTX ctx;
    
    HMAC_CTX_init(&ctx);

    HMAC_Init_ex(&ctx, 
		 key->keyvalue.data, key->keyvalue.length, 
		 EVP_sha1(), NULL);
    rep->hash->length = HMAC_size(&ctx);
    rep->hash->data = malloc(rep->hash->length);
    if (rep->hash->data == NULL) {
	HMAC_CTX_cleanup(&ctx);
	krb5_set_error_string(context, "out of memory");
	return ENOMEM;
    }

    HMAC_Update(&ctx, version_2_0, sizeof(version_2_0));
    if (rep->error_code) {
	int32_t t = *rep->error_code;
	do {
	    unsigned char p = (t & 0xff);
	    HMAC_Update(&ctx, &p, 1);
	    t >>= 8;
	} while (t);
    }
    if (rep->certificate)
	HMAC_Update(&ctx, rep->certificate->data, rep->certificate->length);
    if (rep->e_text)
	HMAC_Update(&ctx, (unsigned char *)*rep->e_text, strlen(*rep->e_text));

    HMAC_Final(&ctx, rep->hash->data, 0);
    HMAC_CTX_cleanup(&ctx);

    return 0;
}

/*
 * Build a certifate for `principal