From 2afb5160110f54a5d89e968723b3dbb940de42b7 Mon Sep 17 00:00:00 2001 From: Ryan Everett Date: Fri, 22 Dec 2023 15:59:45 +0000 Subject: [PATCH] Update and rename psa_get_empty_key_slot Rename to psa_reserve_free_key_slot, as this function reserves a slot which is free (not always empty) for filling. Implement necessary state transitions and state checks. Rename unlocked_persistent_key_slot to unused_persistent_key_slot. Signed-off-by: Ryan Everett --- library/psa_crypto_slot_management.c | 39 +++++++++++++++++----------- library/psa_crypto_slot_management.h | 24 ++++++++++------- 2 files changed, 39 insertions(+), 24 deletions(-) diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c index 32881e5e9..0f480fb09 100644 --- a/library/psa_crypto_slot_management.c +++ b/library/psa_crypto_slot_management.c @@ -147,30 +147,31 @@ void psa_wipe_all_key_slots(void) global_data.key_slots_initialized = 0; } -psa_status_t psa_get_empty_key_slot(psa_key_id_t *volatile_key_id, - psa_key_slot_t **p_slot) +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, *unlocked_persistent_key_slot; + psa_key_slot_t *selected_slot, *unused_persistent_key_slot; if (!global_data.key_slots_initialized) { status = PSA_ERROR_BAD_STATE; goto error; } - selected_slot = unlocked_persistent_key_slot = NULL; + selected_slot = unused_persistent_key_slot = NULL; for (slot_idx = 0; slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT; slot_idx++) { psa_key_slot_t *slot = &global_data.key_slots[slot_idx]; - if (!psa_is_key_slot_occupied(slot)) { + if (slot->state == PSA_SLOT_EMPTY) { selected_slot = slot; break; } - if ((unlocked_persistent_key_slot == NULL) && - (!PSA_KEY_LIFETIME_IS_VOLATILE(slot->attr.lifetime)) && - (!psa_is_key_slot_locked(slot))) { - unlocked_persistent_key_slot = slot; + 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; } } @@ -182,16 +183,24 @@ psa_status_t psa_get_empty_key_slot(psa_key_id_t *volatile_key_id, * storage. */ if ((selected_slot == NULL) && - (unlocked_persistent_key_slot != NULL)) { - selected_slot = unlocked_persistent_key_slot; - selected_slot->lock_count = 1; - psa_wipe_key_slot(selected_slot); + (unused_persistent_key_slot != NULL)) { + selected_slot = unused_persistent_key_slot; + psa_register_read(selected_slot); + /* If the state is not changed then psa_wipe_key_slot + * will report an error. */ + psa_key_slot_state_transition(selected_slot, PSA_SLOT_FULL, + PSA_SLOT_PENDING_DELETION); + status = psa_wipe_key_slot(selected_slot); + if (status != PSA_SUCCESS) { + goto error; + } } if (selected_slot != NULL) { - status = psa_lock_key_slot(selected_slot); + status = psa_key_slot_state_transition(selected_slot, PSA_SLOT_EMPTY, + PSA_SLOT_FILLING); if (status != PSA_SUCCESS) { - goto error; + return status; } *volatile_key_id = PSA_KEY_ID_VOLATILE_MIN + diff --git a/library/psa_crypto_slot_management.h b/library/psa_crypto_slot_management.h index f0bbed98f..b2cf57011 100644 --- a/library/psa_crypto_slot_management.h +++ b/library/psa_crypto_slot_management.h @@ -95,23 +95,29 @@ psa_status_t psa_initialize_key_slots(void); * This does not affect persistent storage. */ void psa_wipe_all_key_slots(void); -/** Find a free key slot. +/** Find a free key slot and reserve it to be filled with a key. * - * This function returns a key slot that is available for use and is in its - * ground state (all-bits-zero). On success, the key slot is locked. It is - * the responsibility of the caller to unlock the key slot when it does not - * access it anymore. + * This function finds a key slot that is free, + * sets its state to PSA_SLOT_FILLING and then returns the slot. + * + * On success, the key slot's state is PSA_SLOT_FILLING. + * It is the responsibility of the caller to change the slot's state to + * PSA_SLOT_EMPTY/FULL once key creation has finished. * * \param[out] volatile_key_id On success, volatile key identifier * associated to the returned slot. * \param[out] p_slot On success, a pointer to the slot. * * \retval #PSA_SUCCESS \emptydescription - * \retval #PSA_ERROR_INSUFFICIENT_MEMORY \emptydescription - * \retval #PSA_ERROR_BAD_STATE \emptydescription + * \retval #PSA_ERROR_INSUFFICIENT_MEMORY + * There were no free key slots. + * \retval #PSA_ERROR_BAD_STATE + * This function attempted to operate on a key slot which was in an + * unexpected state. */ -psa_status_t psa_get_empty_key_slot(psa_key_id_t *volatile_key_id, - psa_key_slot_t **p_slot); +psa_status_t psa_reserve_free_key_slot(psa_key_id_t *volatile_key_id, + psa_key_slot_t **p_slot); + /** Change the state of a key slot. * * This function changes the state of the key slot from expected_state to