gbe_fork/mbedtls/psa_crypto_se.c
2023-12-24 14:33:40 +02:00

374 lines
12 KiB
C

/*
* PSA crypto support for secure element drivers
*/
/*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
*/
#include "common.h"
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
#include <stdint.h>
#include <string.h>
#include "psa/crypto_se_driver.h"
#include "psa_crypto_se.h"
#if defined(MBEDTLS_PSA_ITS_FILE_C)
#include "psa_crypto_its.h"
#else /* Native ITS implementation */
#include "psa/error.h"
#include "psa/internal_trusted_storage.h"
#endif
#include "mbedtls/platform.h"
/****************************************************************/
/* Driver lookup */
/****************************************************************/
/* This structure is identical to psa_drv_se_context_t declared in
* `crypto_se_driver.h`, except that some parts are writable here
* (non-const, or pointer to non-const). */
typedef struct {
void *persistent_data;
size_t persistent_data_size;
uintptr_t transient_data;
} psa_drv_se_internal_context_t;
struct psa_se_drv_table_entry_s {
psa_key_location_t location;
const psa_drv_se_t *methods;
union {
psa_drv_se_internal_context_t internal;
psa_drv_se_context_t context;
} u;
};
static psa_se_drv_table_entry_t driver_table[PSA_MAX_SE_DRIVERS];
psa_se_drv_table_entry_t *psa_get_se_driver_entry(
psa_key_lifetime_t lifetime)
{
size_t i;
psa_key_location_t location = PSA_KEY_LIFETIME_GET_LOCATION(lifetime);
/* In the driver table, location=0 means an entry that isn't used.
* No driver has a location of 0 because it's a reserved value
* (which designates transparent keys). Make sure we never return
* a driver entry for location 0. */
if (location == 0) {
return NULL;
}
for (i = 0; i < PSA_MAX_SE_DRIVERS; i++) {
if (driver_table[i].location == location) {
return &driver_table[i];
}
}
return NULL;
}
const psa_drv_se_t *psa_get_se_driver_methods(
const psa_se_drv_table_entry_t *driver)
{
return driver->methods;
}
psa_drv_se_context_t *psa_get_se_driver_context(
psa_se_drv_table_entry_t *driver)
{
return &driver->u.context;
}
int psa_get_se_driver(psa_key_lifetime_t lifetime,
const psa_drv_se_t **p_methods,
psa_drv_se_context_t **p_drv_context)
{
psa_se_drv_table_entry_t *driver = psa_get_se_driver_entry(lifetime);
if (p_methods != NULL) {
*p_methods = (driver ? driver->methods : NULL);
}
if (p_drv_context != NULL) {
*p_drv_context = (driver ? &driver->u.context : NULL);
}
return driver != NULL;
}
/****************************************************************/
/* Persistent data management */
/****************************************************************/
static psa_status_t psa_get_se_driver_its_file_uid(
const psa_se_drv_table_entry_t *driver,
psa_storage_uid_t *uid)
{
if (driver->location > PSA_MAX_SE_LOCATION) {
return PSA_ERROR_NOT_SUPPORTED;
}
/* ITS file sizes are limited to 32 bits. */
if (driver->u.internal.persistent_data_size > UINT32_MAX) {
return PSA_ERROR_NOT_SUPPORTED;
}
/* See the documentation of PSA_CRYPTO_SE_DRIVER_ITS_UID_BASE. */
*uid = PSA_CRYPTO_SE_DRIVER_ITS_UID_BASE + driver->location;
return PSA_SUCCESS;
}
psa_status_t psa_load_se_persistent_data(
const psa_se_drv_table_entry_t *driver)
{
psa_status_t status;
psa_storage_uid_t uid;
size_t length;
status = psa_get_se_driver_its_file_uid(driver, &uid);
if (status != PSA_SUCCESS) {
return status;
}
/* Read the amount of persistent data that the driver requests.
* If the data in storage is larger, it is truncated. If the data
* in storage is smaller, silently keep what is already at the end
* of the output buffer. */
/* psa_get_se_driver_its_file_uid ensures that the size_t
* persistent_data_size is in range, but compilers don't know that,
* so cast to reassure them. */
return psa_its_get(uid, 0,
(uint32_t) driver->u.internal.persistent_data_size,
driver->u.internal.persistent_data,
&length);
}
psa_status_t psa_save_se_persistent_data(
const psa_se_drv_table_entry_t *driver)
{
psa_status_t status;
psa_storage_uid_t uid;
status = psa_get_se_driver_its_file_uid(driver, &uid);
if (status != PSA_SUCCESS) {
return status;
}
/* psa_get_se_driver_its_file_uid ensures that the size_t
* persistent_data_size is in range, but compilers don't know that,
* so cast to reassure them. */
return psa_its_set(uid,
(uint32_t) driver->u.internal.persistent_data_size,
driver->u.internal.persistent_data,
0);
}
psa_status_t psa_destroy_se_persistent_data(psa_key_location_t location)
{
psa_storage_uid_t uid;
if (location > PSA_MAX_SE_LOCATION) {
return PSA_ERROR_NOT_SUPPORTED;
}
uid = PSA_CRYPTO_SE_DRIVER_ITS_UID_BASE + location;
return psa_its_remove(uid);
}
psa_status_t psa_find_se_slot_for_key(
const psa_key_attributes_t *attributes,
psa_key_creation_method_t method,
psa_se_drv_table_entry_t *driver,
psa_key_slot_number_t *slot_number)
{
psa_status_t status;
psa_key_location_t key_location =
PSA_KEY_LIFETIME_GET_LOCATION(psa_get_key_lifetime(attributes));
/* If the location is wrong, it's a bug in the library. */
if (driver->location != key_location) {
return PSA_ERROR_CORRUPTION_DETECTED;
}
/* If the driver doesn't support key creation in any way, give up now. */
if (driver->methods->key_management == NULL) {
return PSA_ERROR_NOT_SUPPORTED;
}
if (psa_get_key_slot_number(attributes, slot_number) == PSA_SUCCESS) {
/* The application wants to use a specific slot. Allow it if
* the driver supports it. On a system with isolation,
* the crypto service must check that the application is
* permitted to request this slot. */
psa_drv_se_validate_slot_number_t p_validate_slot_number =
driver->methods->key_management->p_validate_slot_number;
if (p_validate_slot_number == NULL) {
return PSA_ERROR_NOT_SUPPORTED;
}
status = p_validate_slot_number(&driver->u.context,
driver->u.internal.persistent_data,
attributes, method,
*slot_number);
} else if (method == PSA_KEY_CREATION_REGISTER) {
/* The application didn't specify a slot number. This doesn't
* make sense when registering a slot. */
return PSA_ERROR_INVALID_ARGUMENT;
} else {
/* The application didn't tell us which slot to use. Let the driver
* choose. This is the normal case. */
psa_drv_se_allocate_key_t p_allocate =
driver->methods->key_management->p_allocate;
if (p_allocate == NULL) {
return PSA_ERROR_NOT_SUPPORTED;
}
status = p_allocate(&driver->u.context,
driver->u.internal.persistent_data,
attributes, method,
slot_number);
}
return status;
}
psa_status_t psa_destroy_se_key(psa_se_drv_table_entry_t *driver,
psa_key_slot_number_t slot_number)
{
psa_status_t status;
psa_status_t storage_status;
/* Normally a missing method would mean that the action is not
* supported. But psa_destroy_key() is not supposed to return
* PSA_ERROR_NOT_SUPPORTED: if you can create a key, you should
* be able to destroy it. The only use case for a driver that
* does not have a way to destroy keys at all is if the keys are
* locked in a read-only state: we can use the keys but not
* destroy them. Hence, if the driver doesn't support destroying
* keys, it's really a lack of permission. */
if (driver->methods->key_management == NULL ||
driver->methods->key_management->p_destroy == NULL) {
return PSA_ERROR_NOT_PERMITTED;
}
status = driver->methods->key_management->p_destroy(
&driver->u.context,
driver->u.internal.persistent_data,
slot_number);
storage_status = psa_save_se_persistent_data(driver);
return status == PSA_SUCCESS ? storage_status : status;
}
psa_status_t psa_init_all_se_drivers(void)
{
size_t i;
for (i = 0; i < PSA_MAX_SE_DRIVERS; i++) {
psa_se_drv_table_entry_t *driver = &driver_table[i];
if (driver->location == 0) {
continue; /* skipping unused entry */
}
const psa_drv_se_t *methods = psa_get_se_driver_methods(driver);
if (methods->p_init != NULL) {
psa_status_t status = methods->p_init(
&driver->u.context,
driver->u.internal.persistent_data,
driver->location);
if (status != PSA_SUCCESS) {
return status;
}
status = psa_save_se_persistent_data(driver);
if (status != PSA_SUCCESS) {
return status;
}
}
}
return PSA_SUCCESS;
}
/****************************************************************/
/* Driver registration */
/****************************************************************/
psa_status_t psa_register_se_driver(
psa_key_location_t location,
const psa_drv_se_t *methods)
{
size_t i;
psa_status_t status;
if (methods->hal_version != PSA_DRV_SE_HAL_VERSION) {
return PSA_ERROR_NOT_SUPPORTED;
}
/* Driver table entries are 0-initialized. 0 is not a valid driver
* location because it means a transparent key. */
MBEDTLS_STATIC_ASSERT(PSA_KEY_LOCATION_LOCAL_STORAGE == 0,
"Secure element support requires 0 to mean a local key");
if (location == PSA_KEY_LOCATION_LOCAL_STORAGE) {
return PSA_ERROR_INVALID_ARGUMENT;
}
if (location > PSA_MAX_SE_LOCATION) {
return PSA_ERROR_NOT_SUPPORTED;
}
for (i = 0; i < PSA_MAX_SE_DRIVERS; i++) {
if (driver_table[i].location == 0) {
break;
}
/* Check that location isn't already in use up to the first free
* entry. Since entries are created in order and never deleted,
* there can't be a used entry after the first free entry. */
if (driver_table[i].location == location) {
return PSA_ERROR_ALREADY_EXISTS;
}
}
if (i == PSA_MAX_SE_DRIVERS) {
return PSA_ERROR_INSUFFICIENT_MEMORY;
}
driver_table[i].location = location;
driver_table[i].methods = methods;
driver_table[i].u.internal.persistent_data_size =
methods->persistent_data_size;
if (methods->persistent_data_size != 0) {
driver_table[i].u.internal.persistent_data =
mbedtls_calloc(1, methods->persistent_data_size);
if (driver_table[i].u.internal.persistent_data == NULL) {
status = PSA_ERROR_INSUFFICIENT_MEMORY;
goto error;
}
/* Load the driver's persistent data. On first use, the persistent
* data does not exist in storage, and is initialized to
* all-bits-zero by the calloc call just above. */
status = psa_load_se_persistent_data(&driver_table[i]);
if (status != PSA_SUCCESS && status != PSA_ERROR_DOES_NOT_EXIST) {
goto error;
}
}
return PSA_SUCCESS;
error:
memset(&driver_table[i], 0, sizeof(driver_table[i]));
return status;
}
void psa_unregister_all_se_drivers(void)
{
size_t i;
for (i = 0; i < PSA_MAX_SE_DRIVERS; i++) {
if (driver_table[i].u.internal.persistent_data != NULL) {
mbedtls_free(driver_table[i].u.internal.persistent_data);
}
}
memset(driver_table, 0, sizeof(driver_table));
}
/****************************************************************/
/* The end */
/****************************************************************/
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */