Driver context structure.
Driver functions receive a pointer to this structure. Each registered driver has one instance of this structure.
Implementations must include the fields specified here and may include other fields.
Public Functions#
A read-only pointer to the driver's persistent data.
The size of persistent_data
in bytes.
Driver transient data.
Public Function Documentation#
MBEDTLS_PRIVATE#
const void *const psa_drv_se_context_t::MBEDTLS_PRIVATE (persistent_data )
A read-only pointer to the driver's persistent data.
Type | Direction | Argument Name | Description |
---|---|---|---|
persistent_data | N/A |
Drivers typically use this persistent data to keep track of which slot numbers are available. This is only a guideline: drivers may use the persistent data for any purpose, keeping in mind the restrictions on when the persistent data is saved to storage: the persistent data is only saved after calling certain functions that receive a writable pointer to the persistent data.
The core allocates a memory buffer for the persistent data. The pointer is guaranteed to be suitably aligned for any data type, like a pointer returned by malloc
(but the core can use any method to allocate the buffer, not necessarily malloc
).
The size of this buffer is in the persistent_data_size
field of this structure.
Before the driver is initialized for the first time, the content of the persistent data is all-bits-zero. After a driver upgrade, if the size of the persistent data has increased, the original data is padded on the right with zeros; if the size has decreased, the original data is truncated to the new size.
This pointer is to read-only data. Only a few driver functions are allowed to modify the persistent data. These functions receive a writable pointer. These functions are:
psa_drv_se_t::p_init
psa_drv_se_key_management_t::p_allocate
psa_drv_se_key_management_t::p_destroy
The PSA Cryptography core saves the persistent data from one session to the next. It does this before returning from API functions that call a driver method that is allowed to modify the persistent data, specifically:
psa_crypto_init() causes a call to psa_drv_se_t::p_init, and may call psa_drv_se_key_management_t::p_destroy to complete an action that was interrupted by a power failure.
Key creation functions cause a call to psa_drv_se_key_management_t::p_allocate, and may cause a call to psa_drv_se_key_management_t::p_destroy in case an error occurs.
psa_destroy_key() causes a call to psa_drv_se_key_management_t::p_destroy.
MBEDTLS_PRIVATE#
const size_t psa_drv_se_context_t::MBEDTLS_PRIVATE (persistent_data_size )
The size of persistent_data
in bytes.
Type | Direction | Argument Name | Description |
---|---|---|---|
persistent_data_size | N/A |
This is always equal to the value of the persistent_data_size
field of the psa_drv_se_t structure when the driver is registered.
MBEDTLS_PRIVATE#
uintptr_t psa_drv_se_context_t::MBEDTLS_PRIVATE (transient_data )
Driver transient data.
Type | Direction | Argument Name | Description |
---|---|---|---|
transient_data | N/A |
The core initializes this value to 0 and does not read or modify it afterwards. The driver may store whatever it wants in this field.