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|
// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
/* Copyright 2020 IBM Corp. */
#ifndef pr_fmt
#define pr_fmt(fmt) "SECBOOT_TPM: " fmt
#endif
#include <stdlib.h>
#include <skiboot.h>
#include <opal.h>
#include <mbedtls/sha256.h>
#include "../secvar.h"
#include "../secvar_devtree.h"
#include "secboot_tpm.h"
#include <tssskiboot.h>
#include <ibmtss/TPM_Types.h>
#define CYCLE_BIT(b) (b^0x1)
#define SECBOOT_TPM_MAX_VAR_SIZE 8192
struct secboot *secboot_image = NULL;
struct tpmnv_vars *tpmnv_vars_image = NULL;
struct tpmnv_control *tpmnv_control_image = NULL;
const size_t tpmnv_vars_size = 2048;
/* Expected TPM NV index name field from NV_ReadPublic given our known
* set of attributes (see tss_nv_define_space).
* See Part 1 Section 16, and Part 2 Section 13.5 of the TPM Specification
* for how this is calculated
*
* These hashes are calculated and checked BEFORE TPM2_NV_WriteLock is called,
* which alters the hash slightly as it sets TPMA_NV_WRITELOCKED
*/
const uint8_t tpmnv_vars_name[] = {
0x00, 0x0b, 0x7a, 0xdb, 0x70, 0xdd, 0x27, 0x94, 0x93, 0x26, 0x11, 0xe2, 0x97,
0x00, 0x77, 0x22, 0x4d, 0x5a, 0x74, 0xf8, 0x91, 0x6f, 0xbf, 0xf8, 0x51, 0x4a,
0x67, 0x6f, 0xd9, 0xa8, 0xc3, 0xfc, 0x39, 0xed,
};
const uint8_t tpmnv_control_name[] = {
0x00, 0x0b, 0xad, 0x47, 0x6b, 0xa5, 0xdf, 0xb1, 0xe2, 0x18, 0x50, 0xf6, 0x05,
0x67, 0xe8, 0x8b, 0xa9, 0x0f, 0x86, 0x1f, 0x06, 0xab, 0x43, 0x96, 0x7f, 0x6e,
0x85, 0x33, 0x5b, 0xa6, 0xf0, 0x63, 0x73, 0xd0,
};
const uint8_t tpmnv_vars_prov_name[] = {
0x00, 0x0b, 0x58, 0x36, 0x2c, 0xbf, 0xec, 0x0e, 0xcc, 0xbf, 0xa9, 0x41, 0x94,
0xe9, 0x95, 0xe8, 0x3b, 0xd7, 0x8b, 0x52, 0xac, 0x61, 0x6f, 0xe6, 0x42, 0x93,
0xbb, 0x5a, 0x79, 0x9f, 0xcc, 0x60, 0x5e, 0x8d,
};
const uint8_t tpmnv_control_prov_name[] = {
0x00, 0x0b, 0x7b, 0xd6, 0x02, 0xac, 0xf5, 0x34, 0x54, 0x5c, 0x3e, 0xda, 0xe5,
0xb2, 0xe4, 0x93, 0x4f, 0x36, 0xfb, 0x7f, 0xea, 0xbe, 0xfa, 0x3c, 0xfe, 0xed,
0x6a, 0x12, 0xfb, 0xc8, 0xf7, 0x92, 0x0e, 0xd3,
};
/* Calculate a SHA256 hash over the supplied buffer */
static int calc_bank_hash(char *target_hash, const char *source_buf, uint64_t size)
{
mbedtls_sha256_context ctx;
int rc;
mbedtls_sha256_init(&ctx);
rc = mbedtls_sha256_update_ret(&ctx, source_buf, size);
if (rc)
goto out;
mbedtls_sha256_finish_ret(&ctx, target_hash);
if (rc)
goto out;
out:
mbedtls_sha256_free(&ctx);
return rc;
}
/* Reformat the TPMNV space */
static int tpmnv_format(void)
{
int rc;
memset(tpmnv_vars_image, 0x00, tpmnv_vars_size);
memset(tpmnv_control_image, 0x00, sizeof(struct tpmnv_control));
tpmnv_vars_image->header.magic_number = SECBOOT_MAGIC_NUMBER;
tpmnv_vars_image->header.version = SECBOOT_VERSION;
tpmnv_control_image->header.magic_number = SECBOOT_MAGIC_NUMBER;
tpmnv_control_image->header.version = SECBOOT_VERSION;
/* Counts as first write to the TPM NV, which sets the
* TPMA_NVA_WRITTEN attribute */
rc = tpmnv_ops.write(SECBOOT_TPMNV_VARS_INDEX,
tpmnv_vars_image,
tpmnv_vars_size, 0);
if (rc) {
prlog(PR_ERR, "Could not write new formatted data to VARS index, rc=%d\n", rc);
return rc;
}
rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX,
tpmnv_control_image,
sizeof(struct tpmnv_control), 0);
if (rc)
prlog(PR_ERR, "Could not write new formatted data to CONTROL index, rc=%d\n", rc);
return rc;
}
/* Reformat the secboot PNOR space */
static int secboot_format(void)
{
int rc;
memset(secboot_image, 0x00, sizeof(struct secboot));
secboot_image->header.magic_number = SECBOOT_MAGIC_NUMBER;
secboot_image->header.version = SECBOOT_VERSION;
/* Write the hash of the empty bank to the tpm so future loads work */
rc = calc_bank_hash(tpmnv_control_image->bank_hash[0],
secboot_image->bank[0],
SECBOOT_VARIABLE_BANK_SIZE);
if (rc) {
prlog(PR_ERR, "Bank hash failed to calculate somehow\n");
return rc;
}
rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX,
tpmnv_control_image->bank_hash[0],
SHA256_DIGEST_SIZE,
offsetof(struct tpmnv_control,
bank_hash[0]));
if (rc) {
prlog(PR_ERR, "Could not write fresh formatted bank hashes to CONTROL index, rc=%d\n", rc);
return rc;
}
rc = flash_secboot_write(0, secboot_image, sizeof(struct secboot));
if (rc)
prlog(PR_ERR, "Could not write formatted data to PNOR, rc=%d\n", rc);
return rc;
}
/*
* Serialize one variable to a target memory location.
* Returns the advanced target pointer,
* NULL if advanced pointer would exceed the supplied bound
*/
static char *secboot_serialize_secvar(char *target, const struct secvar *var, const char *end)
{
if ((target + sizeof(uint64_t) + sizeof(uint64_t)
+ var->key_len + var->data_size) > end)
return NULL;
*((uint64_t*) target) = cpu_to_be64(var->key_len);
target += sizeof(var->key_len);
*((uint64_t*) target) = cpu_to_be64(var->data_size);
target += sizeof(var->data_size);
memcpy(target, var->key, var->key_len);
target += var->key_len;
memcpy(target, var->data, var->data_size);
target += var->data_size;
return target;
}
/* Flattens a linked-list bank into a contiguous buffer for writing */
static int secboot_serialize_bank(const struct list_head *bank, char *target,
size_t target_size, int flags)
{
struct secvar *var;
char *end = target + target_size;
assert(bank);
assert(target);
memset(target, 0x00, target_size);
list_for_each(bank, var, link) {
if (var->flags != flags)
continue;
target = secboot_serialize_secvar(target, var, end);
if (!target) {
prlog(PR_ERR, "Ran out of %s space, giving up!",
(flags & SECVAR_FLAG_PROTECTED) ? "TPMNV" : "PNOR");
return OPAL_EMPTY;
}
}
return OPAL_SUCCESS;
}
/* Helper for the variable-bank specific writing logic */
static int secboot_tpm_write_variable_bank(const struct list_head *bank)
{
int rc;
uint64_t bit;
bit = CYCLE_BIT(tpmnv_control_image->active_bit);
/* Serialize TPMNV variables */
rc = secboot_serialize_bank(bank, tpmnv_vars_image->vars, tpmnv_vars_size - sizeof(struct tpmnv_vars), SECVAR_FLAG_PROTECTED);
if (rc)
goto out;
/* Write TPMNV variables to actual NV */
rc = tpmnv_ops.write(SECBOOT_TPMNV_VARS_INDEX, tpmnv_vars_image, tpmnv_vars_size, 0);
if (rc)
goto out;
/* Serialize the PNOR variables, but don't write to flash until after the bank hash */
rc = secboot_serialize_bank(bank, secboot_image->bank[bit], SECBOOT_VARIABLE_BANK_SIZE, 0);
if (rc)
goto out;
/* Calculate the bank hash, and write to TPM NV */
rc = calc_bank_hash(tpmnv_control_image->bank_hash[bit], secboot_image->bank[bit], SECBOOT_VARIABLE_BANK_SIZE);
if (rc)
goto out;
rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX, tpmnv_control_image->bank_hash[bit],
SHA256_DIGEST_LENGTH, offsetof(struct tpmnv_control, bank_hash[bit]));
if (rc)
goto out;
/* Write new variable bank to pnor */
rc = flash_secboot_write(0, secboot_image, sizeof(struct secboot));
if (rc)
goto out;
/* Flip the bit, and write to TPM NV */
tpmnv_control_image->active_bit = bit;
rc = tpmnv_ops.write(SECBOOT_TPMNV_CONTROL_INDEX,
&tpmnv_control_image->active_bit,
sizeof(tpmnv_control_image->active_bit),
offsetof(struct tpmnv_control, active_bit));
out:
return rc;
}
static int secboot_tpm_write_bank(struct list_head *bank, int section)
{
int rc;
switch (section) {
case SECVAR_VARIABLE_BANK:
rc = secboot_tpm_write_variable_bank(bank);
break;
case SECVAR_UPDATE_BANK:
memset(secboot_image->update, 0, SECBOOT_UPDATE_BANK_SIZE);
rc = secboot_serialize_bank(bank, secboot_image->update,
SECBOOT_UPDATE_BANK_SIZE, 0);
if (rc)
break;
rc = flash_secboot_write(0, secboot_image,
sizeof(struct secboot));
break;
default:
rc = OPAL_HARDWARE;
}
return rc;
}
/*
* Deserialize a single secvar from a buffer.
* Returns an advanced pointer, and an allocated secvar in *var.
* Returns NULL if out of bounds reached, or out of memory.
*/
static int secboot_deserialize_secvar(struct secvar **var, char **src, const char *end)
{
uint64_t key_len;
uint64_t data_size;
struct secvar *ret;
assert(var);
/* Load in the two header values */
key_len = be64_to_cpu(*((uint64_t *) *src));
*src += sizeof(uint64_t);
data_size = be64_to_cpu(*((uint64_t *) *src));
*src += sizeof(uint64_t);
/* Check if we've reached the last var to deserialize */
if ((key_len == 0) && (data_size == 0)) {
return OPAL_EMPTY;
}
if (key_len > SECVAR_MAX_KEY_LEN) {
prlog(PR_ERR, "Deserialization failed: key length exceeded maximum value"
"%llu > %u", key_len, SECVAR_MAX_KEY_LEN);
return OPAL_RESOURCE;
}
if (data_size > SECBOOT_TPM_MAX_VAR_SIZE) {
prlog(PR_ERR, "Deserialization failed: data size exceeded maximum value"
"%llu > %u", key_len, SECBOOT_TPM_MAX_VAR_SIZE);
return OPAL_RESOURCE;
}
/* Make sure these fields aren't oversized... */
if ((*src + key_len + data_size) > end) {
*var = NULL;
prlog(PR_ERR, "key_len or data_size exceeded the expected bounds");
return OPAL_RESOURCE;
}
ret = alloc_secvar(key_len, data_size);
if (!ret) {
*var = NULL;
prlog(PR_ERR, "Out of memory, could not allocate new secvar");
return OPAL_NO_MEM;
}
/* Load in variable-sized data */
memcpy(ret->key, *src, ret->key_len);
*src += ret->key_len;
memcpy(ret->data, *src, ret->data_size);
*src += ret->data_size;
*var = ret;
return OPAL_SUCCESS;
}
/* Load variables from a flattened buffer into a bank list */
static int secboot_tpm_deserialize_from_buffer(struct list_head *bank, char *src,
uint64_t size, uint64_t flags)
{
struct secvar *var;
char *cur;
char *end;
int rc = 0;
cur = src;
end = src + size;
while (cur < end) {
/* Ensure there is enough space to even check for another var header */
if ((end - cur) < (sizeof(uint64_t) * 2))
break;
rc = secboot_deserialize_secvar(&var, &cur, end);
switch (rc) {
case OPAL_RESOURCE:
case OPAL_NO_MEM:
goto fail;
case OPAL_EMPTY:
goto done;
default: assert(1);
}
var->flags |= flags;
list_add_tail(bank, &var->link);
}
done:
return OPAL_SUCCESS;
fail:
clear_bank_list(bank);
return rc;
}
static int secboot_tpm_load_variable_bank(struct list_head *bank)
{
char bank_hash[SHA256_DIGEST_LENGTH];
uint64_t bit = tpmnv_control_image->active_bit;
int rc;
/* Check the hash of the bank we loaded from PNOR
* versus the expected hash in TPM NV */
rc = calc_bank_hash(bank_hash,
secboot_image->bank[bit],
SECBOOT_VARIABLE_BANK_SIZE);
if (rc)
return rc;
if (memcmp(bank_hash,
tpmnv_control_image->bank_hash[bit],
SHA256_DIGEST_LENGTH))
/* Tampered pnor space detected, abandon ship */
return OPAL_PERMISSION;
rc = secboot_tpm_deserialize_from_buffer(bank, tpmnv_vars_image->vars, tpmnv_vars_size, SECVAR_FLAG_PROTECTED);
if (rc)
return rc;
return secboot_tpm_deserialize_from_buffer(bank, secboot_image->bank[bit], SECBOOT_VARIABLE_BANK_SIZE, 0);
}
static int secboot_tpm_load_bank(struct list_head *bank, int section)
{
switch (section) {
case SECVAR_VARIABLE_BANK:
return secboot_tpm_load_variable_bank(bank);
case SECVAR_UPDATE_BANK:
return secboot_tpm_deserialize_from_buffer(bank, secboot_image->update, SECBOOT_UPDATE_BANK_SIZE, 0);
}
return OPAL_HARDWARE;
}
static int secboot_tpm_get_tpmnv_names(char *nv_vars_name, char *nv_control_name)
{
TPMS_NV_PUBLIC nv_public; /* Throwaway, we only want the name field */
TPM2B_NAME vars_tmp;
TPM2B_NAME control_tmp;
int rc;
rc = tpmnv_ops.readpublic(SECBOOT_TPMNV_VARS_INDEX,
&nv_public,
&vars_tmp);
if (rc) {
prlog(PR_ERR, "Failed to readpublic from the VARS index, rc=%d\n", rc);
return rc;
}
rc = tpmnv_ops.readpublic(SECBOOT_TPMNV_CONTROL_INDEX,
&nv_public,
&control_tmp);
if (rc) {
prlog(PR_ERR, "Failed to readpublic from the CONTROL index, rc=%d\n", rc);
return rc;
}
memcpy(nv_vars_name, vars_tmp.t.name, MIN(sizeof(tpmnv_vars_name), vars_tmp.t.size));
memcpy(nv_control_name, control_tmp.t.name, MIN(sizeof(tpmnv_control_name), control_tmp.t.size));
return OPAL_SUCCESS;
}
/* Ensure the NV indices were defined with the correct set of attributes */
static int secboot_tpm_check_tpmnv_attrs(char *nv_vars_name, char *nv_control_name)
{
if (memcmp(tpmnv_vars_name,
nv_vars_name,
sizeof(tpmnv_vars_name))) {
prlog(PR_ERR, "VARS index not defined with the correct attributes\n");
return OPAL_RESOURCE;
}
if (memcmp(tpmnv_control_name,
nv_control_name,
sizeof(tpmnv_control_name))) {
prlog(PR_ERR, "CONTROL index not defined with the correct attributes\n");
return OPAL_RESOURCE;
}
return OPAL_SUCCESS;
}
static bool secboot_tpm_check_provisioned_indices(char *nv_vars_name, char *nv_control_name)
{
/* Check for provisioned NV indices, redefine them if detected. */
if (!memcmp(tpmnv_vars_prov_name,
nv_vars_name,
sizeof(tpmnv_vars_prov_name)) &&
!memcmp(tpmnv_control_prov_name,
nv_control_name,
sizeof(tpmnv_control_prov_name))) {
return true;
}
/*
* If one matches but the other doesn't, do NOT redefine.
* The next step should detect they don't match the expected values
* and fail the boot.
*/
return false;
}
static int secboot_tpm_define_indices(void)
{
int rc = OPAL_SUCCESS;
rc = tpmnv_ops.definespace(SECBOOT_TPMNV_VARS_INDEX, tpmnv_vars_size);
if (rc) {
prlog(PR_ERR, "Failed to define the VARS index, rc=%d\n", rc);
return rc;
}
rc = tpmnv_ops.definespace(SECBOOT_TPMNV_CONTROL_INDEX, sizeof(struct tpmnv_control));
if (rc) {
prlog(PR_ERR, "Failed to define the CONTROL index, rc=%d\n", rc);
return rc;
}
rc = tpmnv_format();
if (rc)
return rc;
/* TPM NV just got redefined, so unconditionally format the SECBOOT partition */
return secboot_format();
}
static int secboot_tpm_undefine_indices(bool *vars_defined, bool *control_defined)
{
int rc;
if (vars_defined) {
rc = tpmnv_ops.undefinespace(SECBOOT_TPMNV_VARS_INDEX);
if (rc) {
prlog(PR_ERR, "Failed to undefine VARS, something is seriously wrong\n");
return rc;
}
}
if (control_defined) {
rc = tpmnv_ops.undefinespace(SECBOOT_TPMNV_CONTROL_INDEX);
if (rc) {
prlog(PR_ERR, "Failed to undefine CONTROL, something is seriously wrong\n");
return rc;
}
}
*vars_defined = *control_defined = false;
return OPAL_SUCCESS;
}
static int secboot_tpm_store_init(void)
{
int rc;
unsigned int secboot_size;
TPMI_RH_NV_INDEX *indices = NULL;
char nv_vars_name[sizeof(tpmnv_vars_name)];
char nv_control_name[sizeof(tpmnv_control_name)];
size_t count = 0;
bool control_defined = false;
bool vars_defined = false;
int i;
if (secboot_image)
return OPAL_SUCCESS;
prlog(PR_DEBUG, "Initializing for pnor+tpm based platform\n");
/* Initialize SECBOOT first, we may need to format this later */
rc = flash_secboot_info(&secboot_size);
if (rc) {
prlog(PR_ERR, "error %d retrieving keystore info\n", rc);
goto error;
}
if (sizeof(struct secboot) > secboot_size) {
prlog(PR_ERR, "secboot partition %d KB too small. min=%ld\n",
secboot_size >> 10, sizeof(struct secboot));
rc = OPAL_RESOURCE;
goto error;
}
secboot_image = memalign(0x1000, sizeof(struct secboot));
if (!secboot_image) {
prlog(PR_ERR, "Failed to allocate space for the secboot image\n");
rc = OPAL_NO_MEM;
goto error;
}
/* Read in the PNOR data, bank hash is checked on call to .load_bank() */
rc = flash_secboot_read(secboot_image, 0, sizeof(struct secboot));
if (rc) {
prlog(PR_ERR, "failed to read the secboot partition, rc=%d\n", rc);
goto error;
}
/* Allocate the tpmnv data buffers */
tpmnv_vars_image = zalloc(tpmnv_vars_size);
if (!tpmnv_vars_image)
return OPAL_NO_MEM;
tpmnv_control_image = zalloc(sizeof(struct tpmnv_control));
if (!tpmnv_control_image)
return OPAL_NO_MEM;
/* Check if the NV indices have been defined already */
rc = tpmnv_ops.getindices(&indices, &count);
if (rc) {
prlog(PR_ERR, "Could not load defined indicies from TPM, rc=%d\n", rc);
goto error;
}
for (i = 0; i < count; i++) {
if (indices[i] == SECBOOT_TPMNV_VARS_INDEX)
vars_defined = true;
else if (indices[i] == SECBOOT_TPMNV_CONTROL_INDEX)
control_defined = true;
}
free(indices);
/* Undefine the NV indices if physical presence has been asserted */
if (secvar_check_physical_presence()) {
prlog(PR_INFO, "Physical presence asserted, redefining NV indices, and resetting keystore\n");
rc = secboot_tpm_undefine_indices(&vars_defined, &control_defined);
if (rc)
goto error;
rc = secboot_tpm_define_indices();
if (rc)
goto error;
/* Indices got defined and formatted, we're done here */
goto done;
}
/* Determine if we need to define the indices. These should BOTH be false or true */
if (!vars_defined && !control_defined) {
rc = secboot_tpm_define_indices();
if (rc)
goto error;
/* Indices got defined and formatted, we're done here */
goto done;
}
if (vars_defined ^ control_defined) {
/* This should never happen. Both indices should be defined at the same
* time. Otherwise something seriously went wrong. */
prlog(PR_ERR, "NV indices defined with unexpected attributes. Assert physical presence to clear\n");
goto error;
}
/* Both indices are defined, now need to validate their contents */
rc = secboot_tpm_get_tpmnv_names(nv_vars_name, nv_control_name);
if (rc)
goto error;
/* Check for provisioned TPMNV indices, redefine them if detected */
if (secboot_tpm_check_provisioned_indices(nv_vars_name, nv_control_name)) {
prlog(PR_INFO, "Provisioned TPM NV indices detected, redefining NV indices, and resetting keystore\n");
rc = secboot_tpm_undefine_indices(&vars_defined, &control_defined);
if (rc)
goto error;
rc = secboot_tpm_define_indices();
if (rc)
goto error;
/* Indices got defined and formatted, we're done here */
goto done;
}
/* Otherwise, ensure the NV indices were defined with the correct set of attributes */
rc = secboot_tpm_check_tpmnv_attrs(nv_vars_name, nv_control_name);
if (rc)
goto error;
/* TPMNV indices exist, are correct, and weren't just formatted, so read them in */
rc = tpmnv_ops.read(SECBOOT_TPMNV_VARS_INDEX,
tpmnv_vars_image,
tpmnv_vars_size, 0);
if (rc) {
prlog(PR_ERR, "Failed to read from the VARS index\n");
goto error;
}
rc = tpmnv_ops.read(SECBOOT_TPMNV_CONTROL_INDEX,
tpmnv_control_image,
sizeof(struct tpmnv_control), 0);
if (rc) {
prlog(PR_ERR, "Failed to read from the CONTROL index\n");
goto error;
}
/* Verify the header information is correct */
if (tpmnv_vars_image->header.magic_number != SECBOOT_MAGIC_NUMBER ||
tpmnv_control_image->header.magic_number != SECBOOT_MAGIC_NUMBER ||
tpmnv_vars_image->header.version != SECBOOT_VERSION ||
tpmnv_control_image->header.version != SECBOOT_VERSION) {
prlog(PR_ERR, "TPMNV indices defined, but contain bad data. Assert physical presence to clear\n");
goto error;
}
/* Verify the secboot partition header information,
* reformat if incorrect
* Note: Future variants should attempt to handle older versions safely
*/
if (secboot_image->header.magic_number != SECBOOT_MAGIC_NUMBER ||
secboot_image->header.version != SECBOOT_VERSION) {
rc = secboot_format();
if (rc)
goto error;
}
done:
return OPAL_SUCCESS;
error:
free(secboot_image);
secboot_image = NULL;
free(tpmnv_vars_image);
tpmnv_vars_image = NULL;
free(tpmnv_control_image);
tpmnv_control_image = NULL;
return rc;
}
static void secboot_tpm_lockdown(void)
{
/* Note: While write lock is called here on the two NV indices,
* both indices are also defined on the platform hierarchy.
* The platform hierarchy auth is set later in the skiboot
* initialization process, and not by any secvar-related code.
*/
int rc;
rc = tpmnv_ops.writelock(SECBOOT_TPMNV_VARS_INDEX);
if (rc) {
prlog(PR_EMERG, "TSS Write Lock failed on VARS index, halting.\n");
abort();
}
rc = tpmnv_ops.writelock(SECBOOT_TPMNV_CONTROL_INDEX);
if (rc) {
prlog(PR_EMERG, "TSS Write Lock failed on CONTROL index, halting.\n");
abort();
}
}
struct secvar_storage_driver secboot_tpm_driver = {
.load_bank = secboot_tpm_load_bank,
.write_bank = secboot_tpm_write_bank,
.store_init = secboot_tpm_store_init,
.lockdown = secboot_tpm_lockdown,
.max_var_size = SECBOOT_TPM_MAX_VAR_SIZE,
};
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