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review.trustedfirmware.org / mirror / mbed-tls / 6fb5120fde4ab889bea402f5ab230c720b0a3b9a / . / library / psa_crypto_slot_management.c
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/*
* PSA crypto layer on top of Mbed TLS crypto
*/
/*
* 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_C)
#include "psa/crypto.h"
#include "psa_crypto_core.h"
#include "psa_crypto_driver_wrappers_no_static.h"
#include "psa_crypto_slot_management.h"
#include "psa_crypto_storage.h"
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
#include "psa_crypto_se.h"
#endif
#include <stdlib.h>
#include <string.h>
#include "mbedtls/platform.h"
#if defined(MBEDTLS_THREADING_C)
#include "mbedtls/threading.h"
#endif
/* Make sure we have distinct ranges of key identifiers for distinct
* purposes. */
MBEDTLS_STATIC_ASSERT(PSA_KEY_ID_USER_MIN < PSA_KEY_ID_USER_MAX,
"Empty user key ID range");
MBEDTLS_STATIC_ASSERT(PSA_KEY_ID_VENDOR_MIN < PSA_KEY_ID_VENDOR_MAX,
"Empty vendor key ID range");
MBEDTLS_STATIC_ASSERT(MBEDTLS_PSA_KEY_ID_BUILTIN_MIN <= MBEDTLS_PSA_KEY_ID_BUILTIN_MAX,
"Empty builtin key ID range");
MBEDTLS_STATIC_ASSERT(PSA_KEY_ID_VOLATILE_MIN <= PSA_KEY_ID_VOLATILE_MAX,
"Empty volatile key ID range");
MBEDTLS_STATIC_ASSERT(PSA_KEY_ID_USER_MAX < PSA_KEY_ID_VENDOR_MIN ||
PSA_KEY_ID_VENDOR_MAX < PSA_KEY_ID_USER_MIN,
"Overlap between user key IDs and vendor key IDs");
MBEDTLS_STATIC_ASSERT(PSA_KEY_ID_VENDOR_MIN <= MBEDTLS_PSA_KEY_ID_BUILTIN_MIN &&
MBEDTLS_PSA_KEY_ID_BUILTIN_MAX <= PSA_KEY_ID_VENDOR_MAX,
"Builtin key identifiers are not in the vendor range");
MBEDTLS_STATIC_ASSERT(PSA_KEY_ID_VENDOR_MIN <= PSA_KEY_ID_VOLATILE_MIN &&
PSA_KEY_ID_VOLATILE_MAX <= PSA_KEY_ID_VENDOR_MAX,
"Volatile key identifiers are not in the vendor range");
MBEDTLS_STATIC_ASSERT(PSA_KEY_ID_VOLATILE_MAX < MBEDTLS_PSA_KEY_ID_BUILTIN_MIN ||
MBEDTLS_PSA_KEY_ID_BUILTIN_MAX < PSA_KEY_ID_VOLATILE_MIN,
"Overlap between builtin key IDs and volatile key IDs");
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
/* Dynamic key store.
*
* The key store consists of multiple slices.
*
* The volatile keys are stored in variable-sized tables called slices.
* Slices are allocated on demand and deallocated when possible.
* The size of slices increases exponentially, so the average overhead
* (number of slots that are allocated but not used) is roughly
* proportional to the number of keys (with a factor that grows
* when the key store is fragmented).
*
* One slice is dedicated to the cache of persistent and built-in keys.
* For simplicity, they are separated from volatile keys. This cache
* slice has a fixed size and has the slice index KEY_SLOT_CACHE_SLICE_INDEX,
* located after the slices for volatile keys.
*/
/* Size of the last slice containing the cache of persistent and built-in keys. */
#define PERSISTENT_KEY_CACHE_COUNT MBEDTLS_PSA_KEY_SLOT_COUNT
/* Volatile keys are stored in slices 0 through
* (KEY_SLOT_VOLATILE_SLICE_COUNT - 1) inclusive.
* Each slice is twice the size of the previous slice.
* Volatile key identifiers encode the slice number as follows:
* bits 30..31: 0b10 (mandated by the PSA Crypto specification).
* bits 25..29: slice index (0...KEY_SLOT_VOLATILE_SLICE_COUNT-1)
* bits 0..24: slot index in slice
*/
#define KEY_ID_SLOT_INDEX_WIDTH 25u
#define KEY_ID_SLICE_INDEX_WIDTH 5u
#define KEY_SLOT_VOLATILE_SLICE_BASE_LENGTH 16u
#define KEY_SLOT_VOLATILE_SLICE_COUNT 22u
#define KEY_SLICE_COUNT (KEY_SLOT_VOLATILE_SLICE_COUNT + 1u)
#define KEY_SLOT_CACHE_SLICE_INDEX KEY_SLOT_VOLATILE_SLICE_COUNT
/* Check that the length of the largest slice (calculated as
* KEY_SLICE_LENGTH_MAX below) does not overflow size_t. We use
* an indirect method in case the calculation of KEY_SLICE_LENGTH_MAX
* itself overflows uintmax_t: if (BASE_LENGTH << c)
* overflows size_t then BASE_LENGTH > SIZE_MAX >> c.
*/
#if (KEY_SLOT_VOLATILE_SLICE_BASE_LENGTH > \
SIZE_MAX >> (KEY_SLOT_VOLATILE_SLICE_COUNT - 1))
#error "Maximum slice length overflows size_t"
#endif
#if KEY_ID_SLICE_INDEX_WIDTH + KEY_ID_SLOT_INDEX_WIDTH > 30
#error "Not enough room in volatile key IDs for slice index and slot index"
#endif
#if KEY_SLOT_VOLATILE_SLICE_COUNT > (1 << KEY_ID_SLICE_INDEX_WIDTH)
#error "Too many slices to fit the slice index in a volatile key ID"
#endif
#define KEY_SLICE_LENGTH_MAX \
(KEY_SLOT_VOLATILE_SLICE_BASE_LENGTH << (KEY_SLOT_VOLATILE_SLICE_COUNT - 1))
#if KEY_SLICE_LENGTH_MAX > 1 << KEY_ID_SLOT_INDEX_WIDTH
#error "Not enough room in volatile key IDs for a slot index in the largest slice"
#endif
#if KEY_ID_SLICE_INDEX_WIDTH > 8
#error "Slice index does not fit in uint8_t for psa_key_slot_t::slice_index"
#endif
/* Calculate the volatile key id to use for a given slot.
* This function assumes valid parameter values. */
static psa_key_id_t volatile_key_id_of_index(size_t slice_idx,
size_t slot_idx)
{
/* We assert above that the slice and slot indexes fit in separate
* bit-fields inside psa_key_id_t, which is a 32-bit type per the
* PSA Cryptography specification. */
return (psa_key_id_t) (0x40000000u |
(slice_idx << KEY_ID_SLOT_INDEX_WIDTH) |
slot_idx);
}
/* Calculate the slice containing the given volatile key.
* This function assumes valid parameter values. */
static size_t slice_index_of_volatile_key_id(psa_key_id_t key_id)
{
size_t mask = (1LU << KEY_ID_SLICE_INDEX_WIDTH) - 1;
return (key_id >> KEY_ID_SLOT_INDEX_WIDTH) & mask;
}
/* Calculate the index of the slot containing the given volatile key.
* This function assumes valid parameter values. */
static size_t slot_index_of_volatile_key_id(psa_key_id_t key_id)
{
return key_id & ((1LU << KEY_ID_SLOT_INDEX_WIDTH) - 1);
}
/* In global_data.first_free_slot_index, use this special value to
* indicate that the slice is full. */
#define FREE_SLOT_INDEX_NONE ((size_t) -1)
#if defined(MBEDTLS_TEST_HOOKS)
size_t psa_key_slot_volatile_slice_count(void)
{
return KEY_SLOT_VOLATILE_SLICE_COUNT;
}
#endif
#else /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
/* Static key store.
*
* All the keys (volatile or persistent) are in a single slice.
* We only use slices as a concept to allow some differences between
* static and dynamic key store management to be buried in auxiliary
* functions.
*/
#define PERSISTENT_KEY_CACHE_COUNT MBEDTLS_PSA_KEY_SLOT_COUNT
#define KEY_SLICE_COUNT 1u
#define KEY_SLOT_CACHE_SLICE_INDEX 0
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
typedef struct {
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
psa_key_slot_t *key_slices[KEY_SLICE_COUNT];
size_t first_free_slot_index[KEY_SLOT_VOLATILE_SLICE_COUNT];
#else /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
psa_key_slot_t key_slots[MBEDTLS_PSA_KEY_SLOT_COUNT];
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
uint8_t key_slots_initialized;
} psa_global_data_t;
static psa_global_data_t global_data;
static uint8_t psa_get_key_slots_initialized(void)
{
uint8_t initialized;
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_lock(&mbedtls_threading_psa_globaldata_mutex);
#endif /* defined(MBEDTLS_THREADING_C) */
initialized = global_data.key_slots_initialized;
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_unlock(&mbedtls_threading_psa_globaldata_mutex);
#endif /* defined(MBEDTLS_THREADING_C) */
return initialized;
}
/** The length of the given slice in the key slot table.
*
* \param slice_idx The slice number. It must satisfy
* 0 <= slice_idx < KEY_SLICE_COUNT.
*
* \return The number of elements in the given slice.
*/
static inline size_t key_slice_length(size_t slice_idx);
/** Get a pointer to the slot where the given volatile key is located.
*
* \param key_id The key identifier. It must be a valid volatile key
* identifier.
* \return A pointer to the only slot that the given key
* can be in. Note that the slot may be empty or
* contain a different key.
*/
static inline psa_key_slot_t *get_volatile_key_slot(psa_key_id_t key_id);
/** Get a pointer to an entry in the persistent key cache.
*
* \param slot_idx The index in the table. It must satisfy
* 0 <= slot_idx < PERSISTENT_KEY_CACHE_COUNT.
* \return A pointer to the slot containing the given
* persistent key cache entry.
*/
static inline psa_key_slot_t *get_persistent_key_slot(size_t slot_idx);
/** Get a pointer to a slot given by slice and index.
*
* \param slice_idx The slice number. It must satisfy
* 0 <= slice_idx < KEY_SLICE_COUNT.
* \param slot_idx An index in the given slice. It must satisfy
* 0 <= slot_idx < key_slice_length(slice_idx).
*
* \return A pointer to the given slot.
*/
static inline psa_key_slot_t *get_key_slot(size_t slice_idx, size_t slot_idx);
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
#if defined(MBEDTLS_TEST_HOOKS)
size_t (*mbedtls_test_hook_psa_volatile_key_slice_length)(size_t slice_idx) = NULL;
#endif
static inline size_t key_slice_length(size_t slice_idx)
{
if (slice_idx == KEY_SLOT_CACHE_SLICE_INDEX) {
return PERSISTENT_KEY_CACHE_COUNT;
} else {
#if defined(MBEDTLS_TEST_HOOKS)
if (mbedtls_test_hook_psa_volatile_key_slice_length != NULL) {
return mbedtls_test_hook_psa_volatile_key_slice_length(slice_idx);
}
#endif
return KEY_SLOT_VOLATILE_SLICE_BASE_LENGTH << slice_idx;
}
}
static inline psa_key_slot_t *get_volatile_key_slot(psa_key_id_t key_id)
{
size_t slice_idx = slice_index_of_volatile_key_id(key_id);
if (slice_idx >= KEY_SLOT_VOLATILE_SLICE_COUNT) {
return NULL;
}
size_t slot_idx = slot_index_of_volatile_key_id(key_id);
if (slot_idx >= key_slice_length(slice_idx)) {
return NULL;
}
psa_key_slot_t *slice = global_data.key_slices[slice_idx];
if (slice == NULL) {
return NULL;
}
return &slice[slot_idx];
}
static inline psa_key_slot_t *get_persistent_key_slot(size_t slot_idx)
{
return &global_data.key_slices[KEY_SLOT_CACHE_SLICE_INDEX][slot_idx];
}
static inline psa_key_slot_t *get_key_slot(size_t slice_idx, size_t slot_idx)
{
return &global_data.key_slices[slice_idx][slot_idx];
}
#else /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
static inline size_t key_slice_length(size_t slice_idx)
{
(void) slice_idx;
return ARRAY_LENGTH(global_data.key_slots);
}
static inline psa_key_slot_t *get_volatile_key_slot(psa_key_id_t key_id)
{
MBEDTLS_STATIC_ASSERT(ARRAY_LENGTH(global_data.key_slots) <=
PSA_KEY_ID_VOLATILE_MAX - PSA_KEY_ID_VOLATILE_MIN + 1,
"The key slot array is larger than the volatile key ID range");
return &global_data.key_slots[key_id - PSA_KEY_ID_VOLATILE_MIN];
}
static inline psa_key_slot_t *get_persistent_key_slot(size_t slot_idx)
{
return &global_data.key_slots[slot_idx];
}
static inline psa_key_slot_t *get_key_slot(size_t slice_idx, size_t slot_idx)
{
(void) slice_idx;
return &global_data.key_slots[slot_idx];
}
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
int psa_is_valid_key_id(mbedtls_svc_key_id_t key, int vendor_ok)
{
psa_key_id_t key_id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID(key);
if ((PSA_KEY_ID_USER_MIN <= key_id) &&
(key_id <= PSA_KEY_ID_USER_MAX)) {
return 1;
}
if (vendor_ok &&
(PSA_KEY_ID_VENDOR_MIN <= key_id) &&
(key_id <= PSA_KEY_ID_VENDOR_MAX)) {
return 1;
}
return 0;
}
/** Get the description in memory of a key given its identifier and lock it.
*
* The descriptions of volatile keys and loaded persistent keys are
* stored in key slots. This function returns a pointer to the key slot
* containing the description of a key given its identifier.
*
* The function searches the key slots containing the description of the key
* with \p key identifier. The function does only read accesses to the key
* slots. The function does not load any persistent key thus does not access
* any storage.
*
* For volatile key identifiers, only one key slot is queried as a volatile
* key with identifier key_id can only be stored in slot of index
* ( key_id - #PSA_KEY_ID_VOLATILE_MIN ).
*
* On success, the function locks the key slot. It is the responsibility of
* the caller to unlock the key slot when it does not access it anymore.
*
* If multi-threading is enabled, the caller must hold the
* global key slot mutex.
*
* \param key Key identifier to query.
* \param[out] p_slot On success, `*p_slot` contains a pointer to the
* key slot containing the description of the key
* identified by \p key.
*
* \retval #PSA_SUCCESS
* The pointer to the key slot containing the description of the key
* identified by \p key was returned.
* \retval #PSA_ERROR_INVALID_HANDLE
* \p key is not a valid key identifier.
* \retval #PSA_ERROR_DOES_NOT_EXIST
* There is no key with key identifier \p key in the key slots.
*/
static psa_status_t psa_get_and_lock_key_slot_in_memory(
mbedtls_svc_key_id_t key, psa_key_slot_t **p_slot)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
psa_key_id_t key_id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID(key);
size_t slot_idx;
psa_key_slot_t *slot = NULL;
if (psa_key_id_is_volatile(key_id)) {
slot = get_volatile_key_slot(key_id);
/* Check if both the PSA key identifier key_id and the owner
* identifier of key match those of the key slot. */
if (slot != NULL &&
slot->state == PSA_SLOT_FULL &&
mbedtls_svc_key_id_equal(key, slot->attr.id)) {
status = PSA_SUCCESS;
} else {
status = PSA_ERROR_DOES_NOT_EXIST;
}
} else {
if (!psa_is_valid_key_id(key, 1)) {
return PSA_ERROR_INVALID_HANDLE;
}
for (slot_idx = 0; slot_idx < PERSISTENT_KEY_CACHE_COUNT; slot_idx++) {
slot = get_persistent_key_slot(slot_idx);
/* Only consider slots which are in a full state. */
if ((slot->state == PSA_SLOT_FULL) &&
(mbedtls_svc_key_id_equal(key, slot->attr.id))) {
break;
}
}
status = (slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT) ?
PSA_SUCCESS : PSA_ERROR_DOES_NOT_EXIST;
}
if (status == PSA_SUCCESS) {
status = psa_register_read(slot);
if (status == PSA_SUCCESS) {
*p_slot = slot;
}
}
return status;
}
psa_status_t psa_initialize_key_slots(void)
{
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
global_data.key_slices[KEY_SLOT_CACHE_SLICE_INDEX] =
mbedtls_calloc(PERSISTENT_KEY_CACHE_COUNT,
sizeof(*global_data.key_slices[KEY_SLOT_CACHE_SLICE_INDEX]));
if (global_data.key_slices[KEY_SLOT_CACHE_SLICE_INDEX] == NULL) {
return PSA_ERROR_INSUFFICIENT_MEMORY;
}
#else /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
/* Nothing to do: program startup and psa_wipe_all_key_slots() both
* guarantee that the key slots are initialized to all-zero, which
* means that all the key slots are in a valid, empty state. The global
* data mutex is already held when calling this function, so no need to
* lock it here, to set the flag. */
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
global_data.key_slots_initialized = 1;
return PSA_SUCCESS;
}
void psa_wipe_all_key_slots(void)
{
for (size_t slice_idx = 0; slice_idx < KEY_SLICE_COUNT; slice_idx++) {
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
if (global_data.key_slices[slice_idx] == NULL) {
continue;
}
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
for (size_t slot_idx = 0; slot_idx < key_slice_length(slice_idx); slot_idx++) {
psa_key_slot_t *slot = get_key_slot(slice_idx, slot_idx);
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
/* When MBEDTLS_PSA_KEY_STORE_DYNAMIC is disabled, calling
* psa_wipe_key_slot() on an unused slot is useless, but it
* happens to work (because we flip the state to PENDING_DELETION).
*
* When MBEDTLS_PSA_KEY_STORE_DYNAMIC is enabled,
* psa_wipe_key_slot() needs to have a valid slice_index
* field, but that value might not be correct in a
* free slot, so we must not call it.
*
* Bypass the call to psa_wipe_key_slot() if the slot is empty,
* but only if MBEDTLS_PSA_KEY_STORE_DYNAMIC is enabled, to save
* a few bytes of code size otherwise.
*/
if (slot->state == PSA_SLOT_EMPTY) {
continue;
}
#endif
slot->var.occupied.registered_readers = 1;
slot->state = PSA_SLOT_PENDING_DELETION;
(void) psa_wipe_key_slot(slot);
}
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
mbedtls_free(global_data.key_slices[slice_idx]);
global_data.key_slices[slice_idx] = NULL;
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
}
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
for (size_t slice_idx = 0; slice_idx < KEY_SLOT_VOLATILE_SLICE_COUNT; slice_idx++) {
global_data.first_free_slot_index[slice_idx] = 0;
}
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
/* The global data mutex is already held when calling this function. */
global_data.key_slots_initialized = 0;
}
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
static psa_status_t psa_allocate_volatile_key_slot(psa_key_id_t *key_id,
psa_key_slot_t **p_slot)
{
size_t slice_idx;
for (slice_idx = 0; slice_idx < KEY_SLOT_VOLATILE_SLICE_COUNT; slice_idx++) {
if (global_data.first_free_slot_index[slice_idx] != FREE_SLOT_INDEX_NONE) {
break;
}
}
if (slice_idx == KEY_SLOT_VOLATILE_SLICE_COUNT) {
return PSA_ERROR_INSUFFICIENT_MEMORY;
}
if (global_data.key_slices[slice_idx] == NULL) {
global_data.key_slices[slice_idx] =
mbedtls_calloc(key_slice_length(slice_idx),
sizeof(psa_key_slot_t));
if (global_data.key_slices[slice_idx] == NULL) {
return PSA_ERROR_INSUFFICIENT_MEMORY;
}
}
psa_key_slot_t *slice = global_data.key_slices[slice_idx];
size_t slot_idx = global_data.first_free_slot_index[slice_idx];
*key_id = volatile_key_id_of_index(slice_idx, slot_idx);
psa_key_slot_t *slot = &slice[slot_idx];
size_t next_free = slot_idx + 1 + slot->var.free.next_free_relative_to_next;
if (next_free >= key_slice_length(slice_idx)) {
next_free = FREE_SLOT_INDEX_NONE;
}
global_data.first_free_slot_index[slice_idx] = next_free;
/* The .next_free field is not meaningful when the slot is not free,
* so give it the same content as freshly initialized memory. */
slot->var.free.next_free_relative_to_next = 0;
psa_status_t status = psa_key_slot_state_transition(slot,
PSA_SLOT_EMPTY,
PSA_SLOT_FILLING);
if (status != PSA_SUCCESS) {
/* The only reason for failure is if the slot state was not empty.
* This indicates that something has gone horribly wrong.
* In this case, we leave the slot out of the free list, and stop
* modifying it. This minimizes any further corruption. The slot
* is a memory leak, but that's a lesser evil. */
return status;
}
*p_slot = slot;
/* We assert at compile time that the slice index fits in uint8_t. */
slot->slice_index = (uint8_t) slice_idx;
return PSA_SUCCESS;
}
psa_status_t psa_free_key_slot(size_t slice_idx,
psa_key_slot_t *slot)
{
if (slice_idx == KEY_SLOT_CACHE_SLICE_INDEX) {
/* This is a cache entry. We don't maintain a free list, so
* there's nothing to do. */
return PSA_SUCCESS;
}
if (slice_idx >= KEY_SLOT_VOLATILE_SLICE_COUNT) {
return PSA_ERROR_CORRUPTION_DETECTED;
}
psa_key_slot_t *slice = global_data.key_slices[slice_idx];
psa_key_slot_t *slice_end = slice + key_slice_length(slice_idx);
if (slot < slice || slot >= slice_end) {
/* The slot isn't actually in the slice! We can't detect that
* condition for sure, because the pointer comparison itself is
* undefined behavior in that case. That same condition makes the
* subtraction to calculate the slot index also UB.
* Give up now to avoid causing further corruption.
*/
return PSA_ERROR_CORRUPTION_DETECTED;
}
size_t slot_idx = slot - slice;
size_t next_free = global_data.first_free_slot_index[slice_idx];
if (next_free >= key_slice_length(slice_idx)) {
/* The slot was full. The newly freed slot thus becomes the
* end of the free list. */
next_free = key_slice_length(slice_idx);
}
global_data.first_free_slot_index[slice_idx] = slot_idx;
slot->var.free.next_free_relative_to_next =
(int32_t) next_free - (int32_t) slot_idx - 1;
return PSA_SUCCESS;
}
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
psa_status_t psa_reserve_free_key_slot(psa_key_id_t *volatile_key_id,
psa_key_slot_t **p_slot)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
size_t slot_idx;
psa_key_slot_t *selected_slot, *unused_persistent_key_slot;
if (!psa_get_key_slots_initialized()) {
status = PSA_ERROR_BAD_STATE;
goto error;
}
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
if (volatile_key_id != NULL) {
return psa_allocate_volatile_key_slot(volatile_key_id, p_slot);
}
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
/* With a dynamic key store, allocate an entry in the cache slice,
* applicable only to non-volatile keys that get cached in RAM.
* With a static key store, allocate an entry in the sole slice,
* applicable to all keys. */
selected_slot = unused_persistent_key_slot = NULL;
for (slot_idx = 0; slot_idx < PERSISTENT_KEY_CACHE_COUNT; slot_idx++) {
psa_key_slot_t *slot = get_key_slot(KEY_SLOT_CACHE_SLICE_INDEX, slot_idx);
if (slot->state == PSA_SLOT_EMPTY) {
selected_slot = slot;
break;
}
if ((unused_persistent_key_slot == NULL) &&
(slot->state == PSA_SLOT_FULL) &&
(!psa_key_slot_has_readers(slot)) &&
(!PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime))) {
unused_persistent_key_slot = slot;
}
}
/*
* If there is no unused key slot and there is at least one unlocked key
* slot containing the description of a persistent key, recycle the first
* such key slot we encountered. If we later need to operate on the
* persistent key we are evicting now, we will reload its description from
* storage.
*/
if ((selected_slot == NULL) &&
(unused_persistent_key_slot != NULL)) {
selected_slot = unused_persistent_key_slot;
psa_register_read(selected_slot);
status = psa_wipe_key_slot(selected_slot);
if (status != PSA_SUCCESS) {
goto error;
}
}
if (selected_slot != NULL) {
status = psa_key_slot_state_transition(selected_slot, PSA_SLOT_EMPTY,
PSA_SLOT_FILLING);
if (status != PSA_SUCCESS) {
goto error;
}
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
selected_slot->slice_index = KEY_SLOT_CACHE_SLICE_INDEX;
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
#if !defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
if (volatile_key_id != NULL) {
/* Refresh slot_idx, for when the slot is not the original
* selected_slot but rather unused_persistent_key_slot. */
slot_idx = selected_slot - global_data.key_slots;
*volatile_key_id = PSA_KEY_ID_VOLATILE_MIN + slot_idx;
}
#endif
*p_slot = selected_slot;
return PSA_SUCCESS;
}
status = PSA_ERROR_INSUFFICIENT_MEMORY;
error:
*p_slot = NULL;
return status;
}
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
static psa_status_t psa_load_persistent_key_into_slot(psa_key_slot_t *slot)
{
psa_status_t status = PSA_SUCCESS;
uint8_t *key_data = NULL;
size_t key_data_length = 0;
status = psa_load_persistent_key(&slot->attr,
&key_data, &key_data_length);
if (status != PSA_SUCCESS) {
goto exit;
}
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
/* Special handling is required for loading keys associated with a
* dynamically registered SE interface. */
const psa_drv_se_t *drv;
psa_drv_se_context_t *drv_context;
if (psa_get_se_driver(slot->attr.lifetime, &drv, &drv_context)) {
psa_se_key_data_storage_t *data;
if (key_data_length != sizeof(*data)) {
status = PSA_ERROR_DATA_INVALID;
goto exit;
}
data = (psa_se_key_data_storage_t *) key_data;
status = psa_copy_key_material_into_slot(
slot, data->slot_number, sizeof(data->slot_number));
goto exit;
}
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
status = psa_copy_key_material_into_slot(slot, key_data, key_data_length);
if (status != PSA_SUCCESS) {
goto exit;
}
exit:
psa_free_persistent_key_data(key_data, key_data_length);
return status;
}
#endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C */
#if defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
static psa_status_t psa_load_builtin_key_into_slot(psa_key_slot_t *slot)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
psa_key_lifetime_t lifetime = PSA_KEY_LIFETIME_VOLATILE;
psa_drv_slot_number_t slot_number = 0;
size_t key_buffer_size = 0;
size_t key_buffer_length = 0;
if (!psa_key_id_is_builtin(
MBEDTLS_SVC_KEY_ID_GET_KEY_ID(slot->attr.id))) {
return PSA_ERROR_DOES_NOT_EXIST;
}
/* Check the platform function to see whether this key actually exists */
status = mbedtls_psa_platform_get_builtin_key(
slot->attr.id, &lifetime, &slot_number);
if (status != PSA_SUCCESS) {
return status;
}
/* Set required key attributes to ensure get_builtin_key can retrieve the
* full attributes. */
psa_set_key_id(&attributes, slot->attr.id);
psa_set_key_lifetime(&attributes, lifetime);
/* Get the full key attributes from the driver in order to be able to
* calculate the required buffer size. */
status = psa_driver_wrapper_get_builtin_key(
slot_number, &attributes,
NULL, 0, NULL);
if (status != PSA_ERROR_BUFFER_TOO_SMALL) {
/* Builtin keys cannot be defined by the attributes alone */
if (status == PSA_SUCCESS) {
status = PSA_ERROR_CORRUPTION_DETECTED;
}
return status;
}
/* If the key should exist according to the platform, then ask the driver
* what its expected size is. */
status = psa_driver_wrapper_get_key_buffer_size(&attributes,
&key_buffer_size);
if (status != PSA_SUCCESS) {
return status;
}
/* Allocate a buffer of the required size and load the builtin key directly
* into the (now properly sized) slot buffer. */
status = psa_allocate_buffer_to_slot(slot, key_buffer_size);
if (status != PSA_SUCCESS) {
return status;
}
status = psa_driver_wrapper_get_builtin_key(
slot_number, &attributes,
slot->key.data, slot->key.bytes, &key_buffer_length);
if (status != PSA_SUCCESS) {
goto exit;
}
/* Copy actual key length and core attributes into the slot on success */
slot->key.bytes = key_buffer_length;
slot->attr = attributes;
exit:
if (status != PSA_SUCCESS) {
psa_remove_key_data_from_memory(slot);
}
return status;
}
#endif /* MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
psa_status_t psa_get_and_lock_key_slot(mbedtls_svc_key_id_t key,
psa_key_slot_t **p_slot)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
*p_slot = NULL;
if (!psa_get_key_slots_initialized()) {
return PSA_ERROR_BAD_STATE;
}
#if defined(MBEDTLS_THREADING_C)
/* We need to set status as success, otherwise CORRUPTION_DETECTED
* would be returned if the lock fails. */
status = PSA_SUCCESS;
/* If the key is persistent and not loaded, we cannot unlock the mutex
* between checking if the key is loaded and setting the slot as FULL,
* as otherwise another thread may load and then destroy the key
* in the meantime. */
PSA_THREADING_CHK_RET(mbedtls_mutex_lock(
&mbedtls_threading_key_slot_mutex));
#endif
/*
* On success, the pointer to the slot is passed directly to the caller
* thus no need to unlock the key slot here.
*/
status = psa_get_and_lock_key_slot_in_memory(key, p_slot);
if (status != PSA_ERROR_DOES_NOT_EXIST) {
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
/* Loading keys from storage requires support for such a mechanism */
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) || \
defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
status = psa_reserve_free_key_slot(NULL, p_slot);
if (status != PSA_SUCCESS) {
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
(*p_slot)->attr.id = key;
(*p_slot)->attr.lifetime = PSA_KEY_LIFETIME_PERSISTENT;
status = PSA_ERROR_DOES_NOT_EXIST;
#if defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
/* Load keys in the 'builtin' range through their own interface */
status = psa_load_builtin_key_into_slot(*p_slot);
#endif /* MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
if (status == PSA_ERROR_DOES_NOT_EXIST) {
status = psa_load_persistent_key_into_slot(*p_slot);
}
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
if (status != PSA_SUCCESS) {
psa_wipe_key_slot(*p_slot);
/* If the key does not exist, we need to return
* PSA_ERROR_INVALID_HANDLE. */
if (status == PSA_ERROR_DOES_NOT_EXIST) {
status = PSA_ERROR_INVALID_HANDLE;
}
} else {
/* Add implicit usage flags. */
psa_extend_key_usage_flags(&(*p_slot)->attr.policy.usage);
psa_key_slot_state_transition((*p_slot), PSA_SLOT_FILLING,
PSA_SLOT_FULL);
status = psa_register_read(*p_slot);
}
#else /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
status = PSA_ERROR_INVALID_HANDLE;
#endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
if (status != PSA_SUCCESS) {
*p_slot = NULL;
}
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
psa_status_t psa_unregister_read(psa_key_slot_t *slot)
{
if (slot == NULL) {
return PSA_SUCCESS;
}
if ((slot->state != PSA_SLOT_FULL) &&
(slot->state != PSA_SLOT_PENDING_DELETION)) {
return PSA_ERROR_CORRUPTION_DETECTED;
}
/* If we are the last reader and the slot is marked for deletion,
* we must wipe the slot here. */
if ((slot->state == PSA_SLOT_PENDING_DELETION) &&
(slot->var.occupied.registered_readers == 1)) {
return psa_wipe_key_slot(slot);
}
if (psa_key_slot_has_readers(slot)) {
slot->var.occupied.registered_readers--;
return PSA_SUCCESS;
}
/*
* As the return error code may not be handled in case of multiple errors,
* do our best to report if there are no registered readers. Assert with
* MBEDTLS_TEST_HOOK_TEST_ASSERT that there are registered readers:
* if the MBEDTLS_TEST_HOOKS configuration option is enabled and
* the function is called as part of the execution of a test suite, the
* execution of the test suite is stopped in error if the assertion fails.
*/
MBEDTLS_TEST_HOOK_TEST_ASSERT(psa_key_slot_has_readers(slot));
return PSA_ERROR_CORRUPTION_DETECTED;
}
psa_status_t psa_unregister_read_under_mutex(psa_key_slot_t *slot)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
#if defined(MBEDTLS_THREADING_C)
/* We need to set status as success, otherwise CORRUPTION_DETECTED
* would be returned if the lock fails. */
status = PSA_SUCCESS;
PSA_THREADING_CHK_RET(mbedtls_mutex_lock(
&mbedtls_threading_key_slot_mutex));
#endif
status = psa_unregister_read(slot);
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
psa_status_t psa_validate_key_location(psa_key_lifetime_t lifetime,
psa_se_drv_table_entry_t **p_drv)
{
if (psa_key_lifetime_is_external(lifetime)) {
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
/* Check whether a driver is registered against this lifetime */
psa_se_drv_table_entry_t *driver = psa_get_se_driver_entry(lifetime);
if (driver != NULL) {
if (p_drv != NULL) {
*p_drv = driver;
}
return PSA_SUCCESS;
}
#else /* MBEDTLS_PSA_CRYPTO_SE_C */
(void) p_drv;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
/* Key location for external keys gets checked by the wrapper */
return PSA_SUCCESS;
} else {
/* Local/internal keys are always valid */
return PSA_SUCCESS;
}
}
psa_status_t psa_validate_key_persistence(psa_key_lifetime_t lifetime)
{
if (PSA_KEY_LIFETIME_IS_VOLATILE(lifetime)) {
/* Volatile keys are always supported */
return PSA_SUCCESS;
} else {
/* Persistent keys require storage support */
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
if (PSA_KEY_LIFETIME_IS_READ_ONLY(lifetime)) {
return PSA_ERROR_INVALID_ARGUMENT;
} else {
return PSA_SUCCESS;
}
#else /* MBEDTLS_PSA_CRYPTO_STORAGE_C */
return PSA_ERROR_NOT_SUPPORTED;
#endif /* !MBEDTLS_PSA_CRYPTO_STORAGE_C */
}
}
psa_status_t psa_open_key(mbedtls_svc_key_id_t key, psa_key_handle_t *handle)
{
#if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) || \
defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
psa_status_t status;
psa_key_slot_t *slot;
status = psa_get_and_lock_key_slot(key, &slot);
if (status != PSA_SUCCESS) {
*handle = PSA_KEY_HANDLE_INIT;
if (status == PSA_ERROR_INVALID_HANDLE) {
status = PSA_ERROR_DOES_NOT_EXIST;
}
return status;
}
*handle = key;
return psa_unregister_read_under_mutex(slot);
#else /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
(void) key;
*handle = PSA_KEY_HANDLE_INIT;
return PSA_ERROR_NOT_SUPPORTED;
#endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
}
psa_status_t psa_close_key(psa_key_handle_t handle)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
psa_key_slot_t *slot;
if (psa_key_handle_is_null(handle)) {
return PSA_SUCCESS;
}
#if defined(MBEDTLS_THREADING_C)
/* We need to set status as success, otherwise CORRUPTION_DETECTED
* would be returned if the lock fails. */
status = PSA_SUCCESS;
PSA_THREADING_CHK_RET(mbedtls_mutex_lock(
&mbedtls_threading_key_slot_mutex));
#endif
status = psa_get_and_lock_key_slot_in_memory(handle, &slot);
if (status != PSA_SUCCESS) {
if (status == PSA_ERROR_DOES_NOT_EXIST) {
status = PSA_ERROR_INVALID_HANDLE;
}
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
if (slot->var.occupied.registered_readers == 1) {
status = psa_wipe_key_slot(slot);
} else {
status = psa_unregister_read(slot);
}
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
psa_status_t psa_purge_key(mbedtls_svc_key_id_t key)
{
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
psa_key_slot_t *slot;
#if defined(MBEDTLS_THREADING_C)
/* We need to set status as success, otherwise CORRUPTION_DETECTED
* would be returned if the lock fails. */
status = PSA_SUCCESS;
PSA_THREADING_CHK_RET(mbedtls_mutex_lock(
&mbedtls_threading_key_slot_mutex));
#endif
status = psa_get_and_lock_key_slot_in_memory(key, &slot);
if (status != PSA_SUCCESS) {
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
if ((!PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) &&
(slot->var.occupied.registered_readers == 1)) {
status = psa_wipe_key_slot(slot);
} else {
status = psa_unregister_read(slot);
}
#if defined(MBEDTLS_THREADING_C)
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return status;
}
void mbedtls_psa_get_stats(mbedtls_psa_stats_t *stats)
{
memset(stats, 0, sizeof(*stats));
for (size_t slice_idx = 0; slice_idx < KEY_SLICE_COUNT; slice_idx++) {
#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
if (global_data.key_slices[slice_idx] == NULL) {
continue;
}
#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
for (size_t slot_idx = 0; slot_idx < key_slice_length(slice_idx); slot_idx++) {
const psa_key_slot_t *slot = get_key_slot(slice_idx, slot_idx);
if (slot->state == PSA_SLOT_EMPTY) {
++stats->empty_slots;
continue;
}
if (psa_key_slot_has_readers(slot)) {
++stats->locked_slots;
}
if (PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) {
++stats->volatile_slots;
} else {
psa_key_id_t id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID(slot->attr.id);
++stats->persistent_slots;
if (id > stats->max_open_internal_key_id) {
stats->max_open_internal_key_id = id;
}
}
if (PSA_KEY_LIFETIME_GET_LOCATION(slot->attr.lifetime) !=
PSA_KEY_LOCATION_LOCAL_STORAGE) {
psa_key_id_t id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID(slot->attr.id);
++stats->external_slots;
if (id > stats->max_open_external_key_id) {
stats->max_open_external_key_id = id;
}
}
}
}
}
#endif /* MBEDTLS_PSA_CRYPTO_C */