When MBEDTLS_PSA_KEY_STORE_DYNAMIC is enabled, key slots are now organized in
multiple slices. The slices are allocated on demand, which allows the key
store to grow. The size of slices grows exponentially, which allows reaching
a large number of slots with a small (static) number of slices without too
much overhead.
Maintain a linked list of free slots in each slice. This way, allocating a
slot takes O(1) time unless a slice needs to be allocated.
In this commit, slices are only ever freed when deinitializing the key
store. This should be improved in the future to free empty slices.
To avoid growing the persistent key cache without control, the persistent
key cache has a fixed size (reusing MBEDTLS_PSA_KEY_SLOT_COUNT to avoid
creating yet another option).
When MBEDTLS_PSA_KEY_STORE_DYNAMIC is disabled. no semantic change and
minimal changes to the code.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Place some fields of psa_key_slot_t in a union, to prepare for a new field
in free slots that should not require extra memory.
For occupied slots, place only the registered_readers field in the union,
not other fields, to minimize textual changes. All fields could move to the
union except state (also needed in free slots) and attr (which must stay
first to reduce the code size, because it is accessed at many call sites).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
It's impractical to fill the key store when it can grow to accommodate
millions of keys.
A later commit will restore those tests in test configurations with the
dynamic key store.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add some abstractions around code that traverses the key store, in
preparation for adding support for MBEDTLS_PSA_KEY_STORE_DYNAMIC.
No intended behavior change. The generated machine code should be
almost the same with an optimizing compiler (in principle, it could be the
same with sufficient constant folding and inlining, but in practice it will
likely be a few byes larger),
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Create a new compilation option for a dynamically resized key store. The
implementation will follow in subsequent commits.
This option is off by default with custom configuration files, which is best
for typical deployments on highly constrained platforms. This option is on
by default with the provided configuration file, which is best for typical
deployments on relatively high-end platforms.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
In public headers, we want to avoid things that are not standard C++,
including features that GCC and Clang support as extensions, such as
flexible array members. So compile with `-pedantic`.
Non-regression for https://github.com/Mbed-TLS/mbedtls/issues/9020.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Document psa_generate_key_ext() and psa_key_derivation_output_key_ext() as
deprecated in favor of psa_generate_key_custom() and
psa_key_derivation_output_key_custom(), and no longer declared in C++ builds.
Resolves#9020.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
We know it's a thin wrapper around psa_generate_key_custom, so we just need
to check that it's passing the information through, we don't need coverage
of the parameter interpretation.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Don't formally deprecate them because we don't do that in a
long-time support branch. But do point readers away from them.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Replace references to the deprecated functions `psa_generate_key_ext()` and
`psa_key_derivation_output_key_ext()` by their replacements
Implement `psa_generate_key_custom()` and
`psa_key_derivation_output_key_custom()`.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Implement `psa_generate_key_custom()` and
`psa_key_derivation_output_key_custom()`. These functions replace
`psa_generate_key_ext()` and `psa_key_derivation_output_key_ext()`.
They have the same functionality, but a slightly different interface:
the `ext` functions use a structure with a flexible array member to pass
variable-length data, while the `custom` functions use a separate parameter.
Keep the `ext` functions for backward compatibility with Mbed TLS 3.6.0.
But make them a thin wrapper around the new `custom` functions.
Duplicate the test code and data. The test cases have to be duplicated
anyway, and the test functions are individually more readable this way.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
