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Merge pull request #8764 from Ryan-Everett-arm/threadsafe-key-wiping

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Make key destruction thread safe
This commit is contained in:
Janos Follath
2024-02-12 09:37:59 +00:00
committed by GitHub
parent c3d17cde46 9dc076b4f4
commit f741db3d6e
4 changed files with 67 additions and 13 deletions
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28
library/psa_crypto.c
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@ -1089,6 +1089,14 @@ psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key)
return status;
}
#if defined(MBEDTLS_THREADING_C)
/* We cannot unlock between setting the state to PENDING_DELETION
* and destroying the key in storage, as otherwise another thread
* could load the key into a new slot and the key will not be
* fully destroyed. */
PSA_THREADING_CHK_GOTO_EXIT(mbedtls_mutex_lock(
&mbedtls_threading_key_slot_mutex));
#endif
/* Set the key slot containing the key description's state to
* PENDING_DELETION. This stops new operations from registering
* to read the slot. Current readers can safely continue to access
@ -1097,7 +1105,12 @@ psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key)
* If the key is persistent, we can now delete the copy of the key
* from memory. If the key is opaque, we require the driver to
* deal with the deletion. */
slot->state = PSA_SLOT_PENDING_DELETION;
status = psa_key_slot_state_transition(slot, PSA_SLOT_FULL,
PSA_SLOT_PENDING_DELETION);
if (status != PSA_SUCCESS) {
goto exit;
}
if (PSA_KEY_LIFETIME_IS_READ_ONLY(slot->attr.lifetime)) {
/* Refuse the destruction of a read-only key (which may or may not work
@ -1152,11 +1165,6 @@ psa_status_t psa_destroy_key(mbedtls_svc_key_id_t key)
if (overall_status == PSA_SUCCESS) {
overall_status = status;
}
/* TODO: other slots may have a copy of the same key. We should
* invalidate them.
* https://github.com/ARMmbed/mbed-crypto/issues/214
*/
}
#endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
@ -1182,6 +1190,14 @@ exit:
if (status != PSA_SUCCESS) {
overall_status = status;
}
#if defined(MBEDTLS_THREADING_C)
/* Don't overwrite existing errors if the unlock fails. */
status = overall_status;
PSA_THREADING_CHK_RET(mbedtls_mutex_unlock(
&mbedtls_threading_key_slot_mutex));
#endif
return overall_status;
}