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/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Functions for querying, manipulating and locking secure data spaces
* stored in the TPM NVRAM.
*/
#include "2api.h"
#include "2common.h"
#include "secdata_tpm.h"
#include "tlcl.h"
#include "tss_constants.h"
#include "vboot_test.h"
#define RETURN_ON_FAILURE(tpm_command) do { \
uint32_t result_; \
if ((result_ = (tpm_command)) != TPM_SUCCESS) { \
VB2_DEBUG("TPM: %#x returned by " #tpm_command \
"\n", (int)result_); \
return result_; \
} \
} while (0)
#define PRINT_BYTES(title, value) do { \
int i; \
VB2_DEBUG(title); \
VB2_DEBUG_RAW(":"); \
for (i = 0; i < sizeof(*(value)); i++) \
VB2_DEBUG_RAW(" %02x", *((uint8_t *)(value) + i)); \
VB2_DEBUG_RAW("\n"); \
} while (0)
/* Keeps track of whether the kernel space has already been locked or not. */
int secdata_kernel_locked = 0;
/**
* Issue a TPM_Clear and reenable/reactivate the TPM.
*/
uint32_t tlcl_clear_and_reenable(void)
{
VB2_DEBUG("TPM: clear_and_reenable\n");
RETURN_ON_FAILURE(TlclForceClear());
RETURN_ON_FAILURE(TlclSetEnable());
RETURN_ON_FAILURE(TlclSetDeactivated(0));
return TPM_SUCCESS;
}
/**
* Like TlclWrite(), but checks for write errors due to hitting the 64-write
* limit and clears the TPM when that happens. This can only happen when the
* TPM is unowned, so it is OK to clear it (and we really have no choice).
* This is not expected to happen frequently, but it could happen.
*/
uint32_t tlcl_safe_write(uint32_t index, const void *data, uint32_t length)
{
uint32_t result = TlclWrite(index, data, length);
if (result == TPM_E_MAXNVWRITES) {
RETURN_ON_FAILURE(tlcl_clear_and_reenable());
return TlclWrite(index, data, length);
} else {
return result;
}
}
/* Functions to read and write firmware and kernel spaces. */
uint32_t secdata_firmware_write(struct vb2_context *ctx)
{
if (!(ctx->flags & VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED)) {
VB2_DEBUG("TPM: secdata_firmware unchanged\n");
return TPM_SUCCESS;
}
if (!(ctx->flags & VB2_CONTEXT_RECOVERY_MODE)) {
VB2_DEBUG("Error: secdata_firmware modified "
"in non-recovery mode?\n");
return TPM_E_AREA_LOCKED;
}
PRINT_BYTES("TPM: write secdata_firmware", &ctx->secdata_firmware);
RETURN_ON_FAILURE(tlcl_safe_write(FIRMWARE_NV_INDEX,
ctx->secdata_firmware,
VB2_SECDATA_FIRMWARE_SIZE));
ctx->flags &= ~VB2_CONTEXT_SECDATA_FIRMWARE_CHANGED;
return TPM_SUCCESS;
}
uint32_t secdata_kernel_read(struct vb2_context *ctx)
{
#ifndef TPM2_MODE
/*
* Before reading the kernel space, verify its permissions. If the
* kernel space has the wrong permission, we give up. This will need
* to be fixed by the recovery kernel. We will have to worry about
* this because at any time (even with PP turned off) the TPM owner can
* remove and redefine a PP-protected space (but not write to it).
*/
uint32_t perms;
RETURN_ON_FAILURE(TlclGetPermissions(KERNEL_NV_INDEX, &perms));
if (perms != TPM_NV_PER_PPWRITE) {
VB2_DEBUG("TPM: invalid secdata_kernel permissions: %#x\n",
perms);
return TPM_E_CORRUPTED_STATE;
}
#endif
RETURN_ON_FAILURE(TlclRead(KERNEL_NV_INDEX, ctx->secdata_kernel,
VB2_SECDATA_KERNEL_SIZE));
PRINT_BYTES("TPM: read secdata_kernel", &ctx->secdata_kernel);
if (vb2api_secdata_kernel_check(ctx)) {
VB2_DEBUG("TPM: secdata_kernel invalid (corrupted?)\n");
return TPM_E_CORRUPTED_STATE;
}
return TPM_SUCCESS;
}
uint32_t secdata_kernel_write(struct vb2_context *ctx)
{
if (!(ctx->flags & VB2_CONTEXT_SECDATA_KERNEL_CHANGED)) {
VB2_DEBUG("TPM: secdata_kernel unchanged\n");
return TPM_SUCCESS;
}
PRINT_BYTES("TPM: write secdata_kernel", &ctx->secdata_kernel);
RETURN_ON_FAILURE(tlcl_safe_write(KERNEL_NV_INDEX, ctx->secdata_kernel,
VB2_SECDATA_KERNEL_SIZE));
ctx->flags &= ~VB2_CONTEXT_SECDATA_KERNEL_CHANGED;
return TPM_SUCCESS;
}
uint32_t secdata_kernel_lock(struct vb2_context *ctx)
{
/* Skip if already locked */
if (secdata_kernel_locked) {
VB2_DEBUG("TPM: secdata_kernel already locked; skipping\n");
return TPM_SUCCESS;
}
RETURN_ON_FAILURE(TlclLockPhysicalPresence());
VB2_DEBUG("TPM: secdata_kernel locked\n");
secdata_kernel_locked = 1;
return TPM_SUCCESS;
}
uint32_t secdata_fwmp_read(struct vb2_context *ctx)
{
vb2_error_t rv;
uint8_t size = VB2_SECDATA_FWMP_MIN_SIZE;
uint32_t r;
/* Try to read entire 1.0 struct */
r = TlclRead(FWMP_NV_INDEX, ctx->secdata_fwmp, size);
if (TPM_E_BADINDEX == r) {
/* Missing space is not an error; tell vboot */
VB2_DEBUG("TPM: no secdata_fwmp space\n");
ctx->flags |= VB2_CONTEXT_NO_SECDATA_FWMP;
return TPM_SUCCESS;
} else if (TPM_SUCCESS != r) {
VB2_DEBUG("TPM: read secdata_fwmp returned %#x\n", r);
return r;
}
/* Re-read more data if necessary */
rv = vb2api_secdata_fwmp_check(ctx, &size);
if (rv == VB2_SUCCESS)
return VB2_SUCCESS;
if (rv == VB2_ERROR_SECDATA_FWMP_INCOMPLETE) {
RETURN_ON_FAILURE(TlclRead(FWMP_NV_INDEX, ctx->secdata_fwmp,
size));
/* Check one more time */
if (vb2api_secdata_fwmp_check(ctx, &size) == VB2_SUCCESS)
return VB2_SUCCESS;
}
VB2_DEBUG("TPM: secdata_fwmp invalid (corrupted?)\n");
return TPM_E_CORRUPTED_STATE;
}
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