It is easier to read if the parameter controlling constant timeness with
respect to a parameter is next to that parameter.
Signed-off-by: Janos Follath <janos.follath@arm.com>
In Thumb instructions, constant can be:
- any constant that can be produced by shifting an 8-bit value left by any
number of bits within a 32-bit word
- any constant of the form 0x00XY00XY
- any constant of the form 0xXY00XY00
- any constant of the form 0xXYXYXYXY.
Signed-off-by: Janos Follath <janos.follath@arm.com>
These macros are not part of any public or internal API, ideally they
would be defined in the source files. The reason to put them in
bignum_core.h to avoid duplication as macros for this purpose are
needed in both bignum.c and bignum_core.c.
Signed-off-by: Janos Follath <janos.follath@arm.com>
The complexity of having functions whose security properties depend on a
runtime argument can be dangerous. Limit risk by isolating such code in
small functions with limited scope.
Signed-off-by: Janos Follath <janos.follath@arm.com>
The complexity of having functions whose security properties depend on a
runtime argument can be dangerous. Limit misuse by making any such
functions local.
Signed-off-by: Janos Follath <janos.follath@arm.com>
Reassure both humans and compilers that the places where we assign an
integer to a smaller type are safe.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
We were only testing the static key store (MBEDTLS_PSA_KEY_STORE_DYNAMIC
disabled) with configs/*.h. Add a component with the static key store and
everything else (including built-in keys), and a component with the static
key store and CTR_DBRG using PSA for AES (which means PSA uses a volatile
key internally).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add a practical way to fill the dynamic key store by artificially limiting
the slice length through a test hook.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
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>
