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wolfTPM/examples/nvram/read.c

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/* read.c
*
* Copyright (C) 2006-2025 wolfSSL Inc.
*
* This file is part of wolfTPM.
*
* wolfTPM is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* wolfTPM is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
*/
/* Tool and example for extracting a TPM key from the TPM's NVRAM
*
* NB: This example uses Parameter Encryption to protect
* the Password Authorization of the TPM NVRAM Index
*
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <wolftpm/tpm2_wrap.h>
#include <stdio.h>
#ifndef WOLFTPM2_NO_WRAPPER
#include <examples/nvram/nvram.h>
#include <hal/tpm_io.h>
#include <examples/tpm_test.h>
#include <examples/tpm_test_keys.h>
#define PRIVATE_PART_ONLY 0x01
#define PUBLIC_PART_ONLY 0x02
/******************************************************************************/
/* --- BEGIN TPM NVRAM Read Example -- */
/******************************************************************************/
static void usage(void)
{
printf("Expected usage:\n");
printf("./examples/nvram/read [-nvindex] [-priv] [-pub] [-aes/-xor] [-delete]\n");
printf("* -nvindex=[handle] (default 0x%x)\n", TPM2_DEMO_NVRAM_STORE_INDEX);
printf("* -priv: Read ony the private part\n");
printf("* -pub: Read only the public part\n");
printf("* -aes/xor: Use Parameter Encryption\n");
printf("* -endorsement/platform/owner: Auth hierarchy\n");
printf("* -delete: Remove NV\n");
}
int TPM2_NVRAM_Read_Example(void* userCtx, int argc, char *argv[])
{
int rc;
WOLFTPM2_DEV dev;
WOLFTPM2_KEY storage;
WOLFTPM2_KEYBLOB keyBlob;
WOLFTPM2_SESSION tpmSession;
WOLFTPM2_HANDLE parent;
WOLFTPM2_NV nv;
TPM2B_AUTH auth;
word32 readSize;
TPMI_RH_NV_AUTH authHandle = TPM_RH_OWNER;
int paramEncAlg = TPM_ALG_NULL;
int partialRead = 0;
int offset = 0;
/* Needed for TPM2_ParsePublic */
byte pubAreaBuffer[sizeof(TPM2B_PUBLIC)];
int pubAreaSize;
word32 nvIndex = TPM2_DEMO_NVRAM_STORE_INDEX;
int deleteKey = 0;
int nvExtend = 0;
if (argc >= 2) {
if (XSTRCMP(argv[1], "-?") == 0 ||
XSTRCMP(argv[1], "-h") == 0 ||
XSTRCMP(argv[1], "--help") == 0) {
usage();
return 0;
}
}
while (argc > 1) {
if (XSTRNCMP(argv[argc-1], "-nvindex=", XSTRLEN("-nvindex=")) == 0) {
const char* nvIndexStr = argv[argc-1] + XSTRLEN("-nvindex=");
nvIndex = (word32)XSTRTOUL(nvIndexStr, NULL, 0);
if (nvIndex < NV_INDEX_FIRST || nvIndex > NV_INDEX_LAST) {
fprintf(stderr, "Invalid NV Index %s\n", nvIndexStr);
fprintf(stderr, "\tPlatform Range: 0x%x -> 0x%x\n",
TPM_20_PLATFORM_MFG_NV_SPACE, TPM_20_OWNER_NV_SPACE);
fprintf(stderr, "\tOwner Range: 0x%x -> 0x%x\n",
TPM_20_OWNER_NV_SPACE, TPM_20_TCG_NV_SPACE);
usage();
return -1;
}
}
else if (XSTRCMP(argv[argc-1], "-endorsement") == 0) {
authHandle = TPM_RH_ENDORSEMENT;
}
else if (XSTRCMP(argv[argc-1], "-platform") == 0) {
authHandle = TPM_RH_PLATFORM;
}
else if (XSTRCMP(argv[argc-1], "-owner") == 0) {
authHandle = TPM_RH_OWNER;
}
else if (XSTRCMP(argv[argc-1], "-aes") == 0) {
paramEncAlg = TPM_ALG_CFB;
}
else if (XSTRCMP(argv[argc-1], "-xor") == 0) {
paramEncAlg = TPM_ALG_XOR;
}
else if (XSTRCMP(argv[argc-1], "-priv") == 0) {
partialRead = PRIVATE_PART_ONLY;
}
else if (XSTRCMP(argv[argc-1], "-pub") == 0) {
partialRead = PUBLIC_PART_ONLY;
}
else if (XSTRCMP(argv[argc-1], "-delete") == 0) {
deleteKey = 1;
}
else {
printf("Warning: Unrecognized option: %s\n", argv[argc-1]);
}
argc--;
}
printf("NV Read\n");
printf("\tNV Index: 0x%08x\n", nvIndex);
printf("\tAuth: %s\n",
(authHandle == TPM_RH_ENDORSEMENT) ? "Endorsement" :
(authHandle == TPM_RH_PLATFORM) ? "Platform" : "Owner");
if (paramEncAlg == TPM_ALG_CFB) {
printf("\tParameter Encryption: Enabled. (AES CFB)\n\n");
}
else if (paramEncAlg == TPM_ALG_XOR) {
printf("\tParameter Encryption: Enabled. (XOR)\n\n");
}
else {
printf("\tParameter Encryption: Not enabled (try -aes or -xor).\n\n");
}
XMEMSET(&keyBlob, 0, sizeof(keyBlob));
XMEMSET(&tpmSession, 0, sizeof(tpmSession));
XMEMSET(&parent, 0, sizeof(parent));
XMEMSET(&auth, 0, sizeof(auth));
XMEMSET(&storage, 0, sizeof(storage));
rc = wolfTPM2_Init(&dev, TPM2_IoCb, userCtx);
if (rc != TPM_RC_SUCCESS) {
printf("\nwolfTPM2_Init failed\n");
goto exit;
}
if (paramEncAlg != TPM_ALG_NULL) {
/* Start TPM session for parameter encryption */
rc = wolfTPM2_StartSession(&dev, &tpmSession, NULL, NULL,
TPM_SE_HMAC, paramEncAlg);
if (rc != 0) goto exit;
printf("TPM2_StartAuthSession: sessionHandle 0x%x\n",
(word32)tpmSession.handle.hndl);
/* Set TPM session attributes for parameter encryption */
rc = wolfTPM2_SetAuthSession(&dev, 1, &tpmSession,
(TPMA_SESSION_decrypt | TPMA_SESSION_encrypt | TPMA_SESSION_continueSession));
if (rc != 0) goto exit;
}
auth.size = sizeof(gNvAuth)-1;
XMEMCPY(auth.buffer, gNvAuth, auth.size);
/* Prepare auth for NV Index */
XMEMSET(&nv, 0, sizeof(nv));
nv.handle.hndl = nvIndex;
nv.handle.auth.size = auth.size;
XMEMCPY(nv.handle.auth.buffer, auth.buffer, auth.size);
rc = wolfTPM2_NVOpen(&dev, &nv, nvIndex, NULL, 0);
if (rc != 0) goto exit;
printf("NV Read: Attributes 0x%08x\n", nv.attributes);
if (((nv.attributes & TPMA_NV_TPM_NT) >> 4) & TPM_NT_EXTEND) {
byte digest[TPM_SHA256_DIGEST_SIZE];
word32 digestLen = (word32)sizeof(digest);
printf("NV Read Extend\n");
nvExtend = 1;
rc = wolfTPM2_NVReadAuth(&dev, &nv, nvIndex, digest, &digestLen, 0);
if (rc == 0) {
printf("\tDigest: %d\n", digestLen);
TPM2_PrintBin(digest, digestLen);
}
}
else {
if (partialRead != PRIVATE_PART_ONLY) {
readSize = sizeof(keyBlob.pub.size);
printf("Trying to read %d bytes of public key size marker\n", readSize);
rc = wolfTPM2_NVReadAuth(&dev, &nv, nvIndex,
(byte*)&keyBlob.pub.size, &readSize, 0);
if (rc != 0) {
printf("Was a public key part written? (see nvram/store)\n");
goto exit;
}
printf("Successfully read public key part from NV\n\n");
offset += readSize;
readSize = sizeof(UINT16) + keyBlob.pub.size; /* account for TPM2B size marker */
printf("Trying to read %d bytes of public key part from NV\n", keyBlob.pub.size);
rc = wolfTPM2_NVReadAuth(&dev, &nv, nvIndex,
pubAreaBuffer, &readSize, offset);
if (rc != 0) goto exit;
printf("Successfully read public key part from NV\n\n");
offset += readSize;
/* Necessary for storing the publicArea with the correct encoding */
rc = TPM2_ParsePublic(&keyBlob.pub, pubAreaBuffer,
readSize, &pubAreaSize);
if (rc != TPM_RC_SUCCESS) {
printf("Decoding of PublicArea failed. Unable to extract correctly.\n");
goto exit;
}
#ifdef WOLFTPM_DEBUG_VERBOSE
TPM2_PrintPublicArea(&keyBlob.pub);
#endif
}
if (partialRead != PUBLIC_PART_ONLY) {
printf("Trying to read size marker of the private key part from NV\n");
readSize = sizeof(keyBlob.priv.size);
rc = wolfTPM2_NVReadAuth(&dev, &nv, nvIndex,
(byte*)&keyBlob.priv.size, &readSize, offset);
if (rc != 0) {
printf("Was a private key part written? (see nvram/store)\n");
goto exit;
}
printf("Successfully read size marker from NV\n\n");
offset += readSize;
readSize = keyBlob.priv.size;
printf("Trying to read %d bytes of private key part from NV\n", readSize);
rc = wolfTPM2_NVReadAuth(&dev, &nv, nvIndex,
(byte*)&keyBlob.priv.buffer, &readSize, offset);
if (rc != 0) goto exit;
printf("Successfully read private key part from NV\n\n");
}
}
/* auth 0 is owner, no auth */
wolfTPM2_SetAuthPassword(&dev, 0, NULL);
wolfTPM2_UnsetAuth(&dev, 1);
if (deleteKey) {
parent.hndl = authHandle;
rc = wolfTPM2_NVDeleteAuth(&dev, &parent, nvIndex);
if (rc != 0) goto exit;
}
printf("Extraction of key from NVRAM at index 0x%x succeeded\n",
nvIndex);
if (!nvExtend && !partialRead) {
/* get SRK */
rc = getPrimaryStoragekey(&dev, &storage, TPM_ALG_RSA);
if (rc != 0) goto exit;
printf("Trying to load the key extracted from NVRAM\n");
rc = wolfTPM2_LoadKey(&dev, &keyBlob, &storage.handle);
if (rc != TPM_RC_SUCCESS) {
printf("wolfTPM2_LoadKey failed\n");
goto exit;
}
printf("Loaded key to 0x%x\n",
(word32)keyBlob.handle.hndl);
}
exit:
if (rc != 0) {
printf("\nFailure 0x%x: %s\n\n", rc, wolfTPM2_GetRCString(rc));
}
wolfTPM2_UnloadHandle(&dev, &keyBlob.handle);
wolfTPM2_UnloadHandle(&dev, &tpmSession.handle);
wolfTPM2_Cleanup(&dev);
return rc;
}
/******************************************************************************/
/* --- END TPM NVRAM Read Example -- */
/******************************************************************************/
#endif /* !WOLFTPM2_NO_WRAPPER */
#ifndef NO_MAIN_DRIVER
int main(int argc, char *argv[])
{
int rc = NOT_COMPILED_IN;
#ifndef WOLFTPM2_NO_WRAPPER
rc = TPM2_NVRAM_Read_Example(NULL, argc, argv);
#else
printf("NVRAM code not compiled in\n");
(void)argc;
(void)argv;
#endif
return rc;
}
#endif
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