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mbedtls/library/psa_crypto_slot_management.c
David Horstmann 43124912c5 Tweak macro check to allow 3 extra key slices 
We are technically allowed to use all possible values of key slice index
that will fit into the bit width we have allocated, so allow all values.

Signed-off-by: David Horstmann <david.horstmann@arm.com>
2024-08-21 15:18:28 +01:00

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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
#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 */
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