We are technically allowed to use all possible values of key slice index
that will fit into the bit width we have allocated, so allow all values.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
The persistent key cache slice is the last slice (not the first as
previously stated). Update the numbering-related comments accordingly.
Signed-off-by: David Horstmann <david.horstmann@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>
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>
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>
Ensure that a key ID can't be in range for more than one of volatile keys,
persistent (i.e. user-chosen) keys or built-in keys.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
If psa_get_and_lock_key_slot fails, the slot must be wiped.
This fixes a bug where a pointer to some valid key slot can
be incorrectly returned
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
Use the global data mutex, as the key slot mutex has to be held in some
of the functions where we are testing the flag, and we already hold the
global data mutex when calling the functions where the flag is set.
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
Switch `psa_key_slot_t` to the full `psa_key_attributes_t`, now that this
structure only has psa_core_key_attributes_t`.
To minimize the diff without breaking the build much, temporarily make
`psa_key_attributes_t` contain either the `core` field or all the fields.
This allows both things like `slot->attr.core.type` and `slot->attr.type`
to exist. The build breaks with compilers that don't support anonymous
unions and structs, which are only standard C since C11.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
There are at least 20 occurences in the current code where
we will need this pattern of code, so I thought it best to
put this in a function
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
Document that callers must hold the key slot mutex.
Change the volatile key checking behaviour so that it
doesn't read the contents of non-FULL slots.
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
These calls otherwise don't abide by our assertions about changing the slot.
psa_get_and_lock_key_slot, the only caller to these, handles the state
transitions already. It also changes the contents of the slot after these calls.
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
It is useful to do this for the call in get_and_lock_key_slot.
Documenting that get_and_lock_key_slot_in_memory requires the mutex
is not part of this PR
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
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 <ryan.everett@arm.com>
Relies on get_and_lock_X being thread safe.
There are two mutex locks here, one in psa_get_and_lock...
Linearization point is the final unlock (or first lock on failure).
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
There are two mutex locks here, the one performed in get_and_lock.. and the one performed outside.
Linearizes at the final unlock.
(This function is deprecated)
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
Make this a global mutex so that we don't have to init and free it.
Also rename the mutex to follow the convention
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
These error codes are only returned if the program has been tampered with,
so they should be CORRUPTION_DETECTED.
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
psa_wipe_key_slot can now be called on a slot in any state, if the slot's state
is PSA_SLOT_FULL or PSA_SLOT_PENDING_DELETION then there must be exactly 1 registered
reader.
Remove the state changing calls that are no longer necessary.
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
Replaces calls to psa_unlock_key_slot with calls to psa_unregister_read.
All instances follow a pattern of a call to psa_get_and_lock_key_slot_X,
followed by some code which reads from a slot, followed by a call to psa_unregister_read.
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
This does not yet implement destruction while a key is in use for psa_destroy_key;
that will be implemented in a separate pr.
(I am not sure if I am allowed to change the documentation in the include files.)
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
Rename to psa_reserve_free_key_slot, as this function reserves a slot which is
free (not always empty) for filling.
Implement necessary state transitions and state checks.
Rename unlocked_persistent_key_slot to unused_persistent_key_slot.
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
Replaces psa_lock_key_slot and psa_unlock_key_slot.
Future commits will remove the calls to locking/unlocking functions,
and add calls to registering/unregistering functions.
Signed-off-by: Ryan Everett <ryan.everett@arm.com>
