From 16abd59a62522852423a35c2b96a087676e6a7ad Mon Sep 17 00:00:00 2001 From: Ryan Everett Date: Wed, 24 Jan 2024 17:37:46 +0000 Subject: [PATCH] Update psa_wipe_all_key_slots and document non-thread safety This function, and mbedtls_psa_crypto_free, are not thread safe as they wipe slots regardless of state. They are not part of the PSA Crypto API, untrusted applications cannot call these functions in a crypto service. In a service intergration, mbedtls_psa_crypto_free on the client cuts the communication with the crypto service. Signed-off-by: Ryan Everett --- include/psa/crypto_extra.h | 2 ++ library/psa_crypto_slot_management.c | 6 ++++++ library/psa_crypto_slot_management.h | 2 ++ 3 files changed, 10 insertions(+) diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h index fc9bf4f0f5..18dccae0a0 100644 --- a/include/psa/crypto_extra.h +++ b/include/psa/crypto_extra.h @@ -198,6 +198,8 @@ psa_status_t mbedtls_psa_register_se_key( * * This function clears all data associated with the PSA layer, * including the whole key store. + * This function is not thread safe, it wipes every key slot regardless of + * state and reader count. It should only be called when no slot is in use. * * This is an Mbed TLS extension. */ diff --git a/library/psa_crypto_slot_management.c b/library/psa_crypto_slot_management.c index e8813b901c..599cc363be 100644 --- a/library/psa_crypto_slot_management.c +++ b/library/psa_crypto_slot_management.c @@ -144,6 +144,9 @@ void psa_wipe_all_key_slots(void) { size_t slot_idx; +#if defined(MBEDTLS_THREADING_C) + mbedtls_mutex_lock(&mbedtls_threading_key_slot_mutex); +#endif for (slot_idx = 0; slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT; slot_idx++) { psa_key_slot_t *slot = &global_data.key_slots[slot_idx]; slot->registered_readers = 1; @@ -151,6 +154,9 @@ void psa_wipe_all_key_slots(void) (void) psa_wipe_key_slot(slot); } global_data.key_slots_initialized = 0; +#if defined(MBEDTLS_THREADING_C) + mbedtls_mutex_unlock(&mbedtls_threading_key_slot_mutex); +#endif } psa_status_t psa_reserve_free_key_slot(psa_key_id_t *volatile_key_id, diff --git a/library/psa_crypto_slot_management.h b/library/psa_crypto_slot_management.h index 002429b933..18a914496d 100644 --- a/library/psa_crypto_slot_management.h +++ b/library/psa_crypto_slot_management.h @@ -92,6 +92,8 @@ psa_status_t psa_get_and_lock_key_slot(mbedtls_svc_key_id_t key, psa_status_t psa_initialize_key_slots(void); /** Delete all data from key slots in memory. + * This function is not thread safe, it wipes every key slot regardless of + * state and reader count. It should only be called when no slot is in use. * * This does not affect persistent storage. */ void psa_wipe_all_key_slots(void);