/*
 * Copyright (c) 2011 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Portions Copyright (c) 2011 Apple Inc. 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 "kcm_locl.h"

#include <Kernel/IOKit/crypto/AppleKeyStoreDefs.h>
#include <IOKit/IOBSD.h>
#include <IOKit/IOKitLib.h>

#include <uuid/uuid.h>
#include <stdio.h>
#include <stdarg.h>

static io_connect_t
openiodev(void)
{
    io_registry_entry_t service;
    io_connect_t conn;
    kern_return_t kr;
    
    service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching(kAppleKeyStoreServiceName));
    if (service == IO_OBJECT_NULL)
	return IO_OBJECT_NULL;
    
    kr = IOServiceOpen(service, mach_task_self(), 0, &conn);
    if (kr != KERN_SUCCESS)
	return IO_OBJECT_NULL;
    
    kr = IOConnectCallMethod(conn, kAppleKeyStoreUserClientOpen, NULL, 0, NULL, 0, NULL, NULL, NULL, NULL);
    if (kr != KERN_SUCCESS) {
	IOServiceClose(conn);
	return IO_OBJECT_NULL;
    }
    
    return conn;
}

static void
closeiodev(io_connect_t conn)
{
    kern_return_t kr;

    kr = IOConnectCallMethod(conn, kAppleKeyStoreUserClientClose, NULL, 0, NULL, 0, NULL, NULL, NULL, NULL);
    if (kr != KERN_SUCCESS)
	return;

    IOServiceClose(conn);
}

krb5_error_code
kcm_create_key(krb5_uuid uuid)
{
    io_connect_t conn;
    createKeyGetUUID_InStruct_t createKey;
    kern_return_t kr;
    uuid_OutStruct_t key;
    size_t outputStructSize = sizeof(key);

    conn = openiodev();
    if (conn == IO_OBJECT_NULL)
	return EINVAL;
    
    createKey.keySizeInBytes = V1_KEYSIZE;
    createKey.algorithm = fDE_ALG_AESXTS;
    
    memset(&key, 0, sizeof(key));
    
    kr = IOConnectCallMethod(conn, kAppleKeyStore_createKeyGetUUID,
			     NULL, 0,
			     &createKey, sizeof(createKey),
			     NULL, 0,
			     &key, &outputStructSize);
    closeiodev(conn);
    if (kr != KERN_SUCCESS)
	return EINVAL;
    
    memcpy(uuid, key.uuid, sizeof(key.uuid));
    
    return 0;
}

krb5_error_code
kcm_store_io(krb5_context context,
	     krb5_uuid uuid,
	     void *ptr,
	     size_t length,
	     krb5_data *data,
	     bool encrypt)
{
    xtsEncrypt_InStruct_t xtsEncrypt_InStruct;
    size_t inseed_size = 64;
    io_connect_t conn;
    kern_return_t kr;
    uint8_t *inseed;
    krb5_crypto crypto = NULL;
    krb5_error_code ret;
    
    krb5_data_zero(data);

    inseed = malloc(inseed_size);
    if (inseed == NULL)
	err(1, "malloc");

    memset(inseed, 0, inseed_size);
    
    conn = openiodev();
    if (conn == IO_OBJECT_NULL) {
	free(inseed);
	return EINVAL;
    }

    uuid_copy(xtsEncrypt_InStruct.key_uuid, uuid);
    xtsEncrypt_InStruct.bufferAddress = (uint64_t) (intptr_t) inseed;
    xtsEncrypt_InStruct.bufferLength = (uint64_t) inseed_size;
    memset(xtsEncrypt_InStruct.tweak, 0, XTS_TWEAK_BYTES);
    
    kr = IOConnectCallMethod(conn, kAppleKeyStore_xtsEncrypt, 
			     NULL, 0, 
			     & xtsEncrypt_InStruct, sizeof(xtsEncrypt_InStruct), 
			     NULL, 0,
			     NULL, 0);
    closeiodev(conn);
    if (kr != KERN_SUCCESS) {
	free(inseed);
	return EINVAL;
    }
    
    CC_SHA256(inseed, inseed_size, inseed);    

    krb5_keyblock keyblock;
    keyblock.keytype = ETYPE_AES128_CTS_HMAC_SHA1_96;
    keyblock.keyvalue.data = inseed;
    keyblock.keyvalue.length = 16;
    
    ret = krb5_crypto_init(context, &keyblock, 0, &crypto);
    free(inseed);
    if (ret)
	return ret;

    if (encrypt)
	ret = krb5_encrypt(context, crypto, 1, ptr, length, data);
    else
	ret = krb5_decrypt(context, crypto, 1, ptr, length, data);

    krb5_crypto_destroy(context, crypto);
    
    return ret;
}