corda/sdk/selib/sgx_get_key.cpp

/*
 * Copyright (C) 2011-2016 Intel Corporation. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
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 *     notice, this list of conditions and the following disclaimer.
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 *     notice, this list of conditions and the following disclaimer in
 *     the documentation and/or other materials provided with the
 *     distribution.
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 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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/**
 * File: sgx_get_key.cpp
 * Description:
 *     Wrapper for EGETKEY instruction
 */

#include "sgx_utils.h"
#include "util.h"
#include <stdlib.h>
#include <string.h>
#include "se_memcpy.h"
#include "trts_inst.h"
#include "sgx_trts.h"
#include "se_cdefs.h"

// add a version to tservice.
SGX_ACCESS_VERSION(tservice, 2)

sgx_status_t sgx_get_key(const sgx_key_request_t *key_request, sgx_key_128bit_t *key)
{
    sgx_status_t err = SGX_ERROR_UNEXPECTED;
    void *buffer = NULL;
    size_t size = 0, buf_ptr =0;
    sgx_key_request_t *tmp_key_request = NULL;
    sgx_key_128bit_t *tmp_key = NULL;
    egetkey_status_t egetkey_status = EGETKEY_SUCCESS;
    int i = 0;

    // check parameters
    //
    // key_request must be within the enclave
    if(!key_request || !sgx_is_within_enclave(key_request, sizeof(*key_request)))
    {
        err = SGX_ERROR_INVALID_PARAMETER;
        goto CLEANUP;
    }

    if (key_request->reserved1 != 0)
    {
        err = SGX_ERROR_INVALID_PARAMETER;
        goto CLEANUP;
    }

    for (i=0; i<SGX_KEY_REQUEST_RESERVED2_BYTES; ++i)
    {
        if (key_request->reserved2[i] != 0)
        {
            err = SGX_ERROR_INVALID_PARAMETER;
            goto CLEANUP;
        }
    }

    // key must be within the enclave
    if(!key || !sgx_is_within_enclave(key, sizeof(*key)))
    {
        err = SGX_ERROR_INVALID_PARAMETER;
        goto CLEANUP;
    }
    // check key_request->key_policy reserved bits
    if(key_request->key_policy & ~(SGX_KEYPOLICY_MRENCLAVE | SGX_KEYPOLICY_MRSIGNER))
    {
        err = SGX_ERROR_INVALID_PARAMETER;
        goto CLEANUP;
    }

    // allocate memory
    // 
    // To minimize the effort of memory management, the two elements allocation 
    // are combined in a single malloc. The calculation for the required size has
    // an assumption, that
    // the elements should be allocated in descending order of the alignment size. 
    //
    // If the alignment requirements are changed, the allocation order needs to
    // change accordingly.
    //
    // Current allocation order is:
    //     key_request -> key
    //
    // key_request: 512-byte aligned, 512-byte length
    // key:          16-byte aligned,  16-byte length
    size = ROUND_TO(sizeof(*key_request), KEY_REQUEST_ALIGN_SIZE) + ROUND_TO(sizeof(*key), KEY_ALIGN_SIZE);
    size += MAX(KEY_REQUEST_ALIGN_SIZE, KEY_ALIGN_SIZE) - 1;

    buffer = malloc(size);
    if(buffer == NULL)
    {
        err = SGX_ERROR_OUT_OF_MEMORY;
        goto CLEANUP;
    }
    memset(buffer, 0, size);
    buf_ptr = reinterpret_cast<size_t>(buffer);

    buf_ptr = ROUND_TO(buf_ptr, KEY_REQUEST_ALIGN_SIZE);
    tmp_key_request = reinterpret_cast<sgx_key_request_t *>(buf_ptr);
    buf_ptr += sizeof(*tmp_key_request);

    buf_ptr = ROUND_TO(buf_ptr, KEY_ALIGN_SIZE);
    tmp_key = reinterpret_cast<sgx_key_128bit_t *>(buf_ptr);

    // Copy data from user buffer to the aligned memory
    memcpy_s(tmp_key_request, sizeof(*tmp_key_request), key_request, sizeof(*key_request));

    // Do EGETKEY
    egetkey_status = (egetkey_status_t) do_egetkey(tmp_key_request, tmp_key);
    switch(egetkey_status)
    {
    case EGETKEY_SUCCESS:
        err = SGX_SUCCESS;
        break;
    case  EGETKEY_INVALID_ATTRIBUTE:
        err =  SGX_ERROR_INVALID_ATTRIBUTE;
        break;
    case EGETKEY_INVALID_CPUSVN:
        err =  SGX_ERROR_INVALID_CPUSVN;
        break;
    case EGETKEY_INVALID_ISVSVN:
        err = SGX_ERROR_INVALID_ISVSVN;
        break;
    case EGETKEY_INVALID_KEYNAME:
        err = SGX_ERROR_INVALID_KEYNAME;
        break;
    default:
        err = SGX_ERROR_UNEXPECTED;
        break;
    }


CLEANUP:
    if((SGX_SUCCESS != err) && (NULL != key))
    {
        // The key buffer should be filled with random number.
        // If sgx_read_rand returns failure, let the key buffer untouched
        sgx_read_rand(reinterpret_cast<uint8_t *>(key), sizeof(*key));
    }
    else if(NULL != key)
    {
        // Copy data to the user buffer
        memcpy_s(key, sizeof(*key), tmp_key, sizeof(*tmp_key));
    }

    // cleanup
    if(buffer)
    {
        memset_s(buffer, size, 0, size);
        free(buffer);
    }

    return err;
}