src/tss2-sys/api/Tss2_Sys_GetEncryptParam.c

//**********************************************************************;
// Copyright (c) 2015, Intel Corporation
// 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.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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
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#include "tss2_tpm2_types.h"
#include "tss2_mu.h"
#include "sysapi_util.h"
#include "util/tss2_endian.h"

TSS2_RC Tss2_Sys_GetEncryptParam(
    TSS2_SYS_CONTEXT *sysContext,
    size_t *encryptParamSize,
    const uint8_t **encryptParamBuffer)
{
    _TSS2_SYS_CONTEXT_BLOB *ctx = syscontext_cast(sysContext);
    uint8_t *offset;

    if (!encryptParamSize || !encryptParamBuffer || !ctx)
        return TSS2_SYS_RC_BAD_REFERENCE;

    if (ctx->previousStage != CMD_STAGE_RECEIVE_RESPONSE)
        return TSS2_SYS_RC_BAD_SEQUENCE;

    if (ctx->encryptAllowed == 0 ||
        BE_TO_HOST_16(resp_header_from_cxt(ctx)->tag) == TPM2_ST_NO_SESSIONS)
        return TSS2_SYS_RC_NO_ENCRYPT_PARAM;

    /* Get first parameter, interpret it as a TPM2B and return its size field
     * and a pointer to its buffer area. */
    offset = ctx->cmdBuffer
            + sizeof(TPM20_Header_Out)
            + ctx->numResponseHandles * sizeof(TPM2_HANDLE)
            + sizeof(TPM2_PARAMETER_SIZE);

    *encryptParamSize = BE_TO_HOST_16(*((UINT16 *)offset));
    *encryptParamBuffer = offset + sizeof(UINT16);

    return TSS2_RC_SUCCESS;
}