Commit graph

36 commits

Author SHA1 Message Date
Gilles Peskine 41e50d26ea Remove "allocated" flag from key slots
The flag to mark key slots as allocated was introduced to mark slots
that are claimed and in use, but do not have key material yet, at a
time when creating a key used several API functions: allocate a slot,
then progressively set its metadata, and finally create the key
material. Now that all of these steps are combined into a single
API function call, the notion of allocated-but-not-filled slot is no
longer relevant. So remove the corresponding flag.

A slot is occupied iff there is a key in it. (For a key in a secure
element, the key material is not present, but the slot contains the
key metadata.) This key must have a type which is nonzero, so use this
as an indicator that a slot is in use.
2019-07-31 16:54:38 +02:00
Gilles Peskine b46bef2f76 Store the key size in the slot in memory
There is now a field for the key size in the key slot in memory. Use
it.

This makes psa_get_key_attributes() marginally faster at the expense
of memory that is available anyway in the current memory layout (16
bits for the size, 16 bits for flags). That's not the goal, though:
the goal is to simplify the code, in particular to make it more
uniform between transparent keys (whose size can be recomputed) and
keys in secure elements (whose size cannot be recomputed).

For keys in a secure element, the bit size is now saved by serializing
the type psa_key_bits_t (which is an alias for uint16_t) rather than
size_t.
2019-07-31 14:16:50 +02:00
Gilles Peskine 2431859dc7 Take advantage of psa_core_key_attributes_t internally: key loading 2019-07-31 14:16:19 +02:00
Gilles Peskine 4ed0e6f11a Switch storage functions over to psa_core_key_attributes_t 2019-07-31 14:15:27 +02:00
Gilles Peskine 8e3387029d Use psa_core_key_attributes_t in key slots in memory
Change the type of key slots in memory to use
psa_core_key_attributes_t rather than separate fields. The goal is to
simplify some parts of the code. This commit only does the mechanical
replacement, not the substitution.

The bit-field `allocate` is now a flag `PSA_KEY_SLOT_FLAG_ALLOCATED`
in the `flags` field.

Write accessor functions for flags.

Key slots now contain a bit size field which is currently unused.
Subsequent commits will make use of it.
2019-07-31 14:15:27 +02:00
Gilles Peskine 7e0cff90b9 Move attribute fields to a substructure
Move the "core attributes" to a substructure of psa_key_attribute_t.
The motivation is to be able to use the new structure
psa_core_key_attributes_t internally.
2019-07-30 20:58:27 +02:00
Gilles Peskine e60d1d08a4 SE keys: save the bit size in storage
For a key in a secure element, save the bit size alongside the slot
number.

This is a quick-and-dirty implementation where the storage format
depends on sizeof(size_t), which is fragile. This should be replaced
by a more robust implementation before going into production.
2019-07-29 18:11:09 +02:00
Gilles Peskine 1df83d4f5b SE keys: implement persistent storage
For a key in a secure element, persist the key slot.

This is implemented in the nominal case. Failures may not be handled
properly.
2019-07-23 16:13:14 +02:00
Gilles Peskine bfd322ff34 Use a key attribute structure in the internal storage interface
Pass information via a key attribute structure rather than as separate
parameters to psa_crypto_storage functions. This makes it easier to
maintain the code when the metadata of a key evolves.

This has negligible impact on code size (+4B with "gcc -Os" on x86_64).
2019-07-23 13:31:54 +02:00
Gilles Peskine 8abe6a2d5c Driver table entries are now mutable
Since driver table entries contain the driver context, which is
mutable, they can't be const anymore.
2019-07-12 23:42:20 +02:00
Gilles Peskine 011e4284a1 Look up the SE driver when creating a key
When creating a key with a lifetime that places it in a secure
element, retrieve the appropriate driver table entry.

This commit doesn't yet achieve behavior: so far the code only
retrieves the driver, it doesn't call the driver.
2019-07-12 11:47:50 +02:00
Gilles Peskine 4bac9a4c4b New function to get key slot statistics
New function mbedtls_psa_get_stats to obtain some data about how many
key slots are in use. This is intended for debugging and testing
purposes.
2019-06-05 16:38:42 +02:00
Gilles Peskine 70e085a7d9 Simplify psa_open_key
Simplify psa_open_key now that the old method for key creation
(returning a handle to a slot with no key material) no longer exists.
2019-06-05 11:34:54 +02:00
Gilles Peskine 267c65666a Simplify key slot allocation
Now that psa_allocate_key() is no longer a public function, expose
psa_internal_allocate_key_slot() instead, which provides a pointer to
the slot to its caller.
2019-06-05 11:34:54 +02:00
Gilles Peskine f46f81ceb5 Remove obsolete key creation functions
Remove the key creation functions from before the attribute-based API,
i.e. the key creation functions that worked by allocating a slot, then
setting metadata through the handle and finally creating key material.
2019-06-05 11:34:54 +02:00
Gilles Peskine 4b3eb69271 Rename PSA_ERROR_TAMPERING_DETECTED to ..._CORRUPTION_DETECTED
“Tampering detected” was misleading because in the real world it can
also arise due to a software bug. “Corruption detected” is neutral and
more precisely reflects what can trigger the error.

perl -i -pe 's/PSA_ERROR_TAMPERING_DETECTED/PSA_ERROR_CORRUPTION_DETECTED/gi' $(git ls-files)
2019-05-16 21:35:18 +02:00
Gilles Peskine e2f62ba9ec Fix unused variable in builds without storage 2019-05-16 00:31:48 +02:00
Gilles Peskine f9fbc38e66 Declare key id 0 as invalid
In keeping with other integral types, declare 0 to be an invalid key
identifier.

Documented, implemented and tested.
2019-05-15 18:42:09 +02:00
Gilles Peskine f9666595e1 Implement and test the new key identifier range
Only allow creating keys in the application (user) range. Allow
opening keys in the implementation (vendor) range as well.

Compared with what the implementation allowed, which was undocumented:
0 is now allowed; values from 0x40000000 to 0xfffeffff are now
forbidden.
2019-05-06 18:56:30 +02:00
Gilles Peskine 225010fdf7 Remove lifetime parameter from psa_open_key
Change the scope of key identifiers to be global, rather than
per lifetime. As a result, you now need to specify the lifetime of a
key only when creating it.
2019-05-06 18:52:22 +02:00
Gilles Peskine 30afafd527 Fix build errors with MBEDTLS_PSA_CRYPTO_STORAGE_C disabled 2019-04-25 17:42:32 +02:00
Gilles Peskine d167b94b87 Reject invalid key ids/lifetimes in attribute-based creation 2019-04-24 15:46:04 +02:00
Jaeden Amero 72f40c6686
Merge pull request #59 from gilles-peskine-arm/psa-its-64_bit_internal_key_id
Support key file IDs encoding the key owner
2019-02-20 13:45:12 +00:00
Gilles Peskine 5b229a06f4 Support encoding an owner in key file IDs
Differentiate between _key identifiers_, which are always `uint32_t`,
and _key file identifiers_, which are platform-dependent. Normally,
the two are the same.

In `psa/crypto_platform.h`, define `psa_app_key_id_t` (which is always
32 bits, the standard key identifier type) and
`psa_key_file_id_t` (which will be different in some service builds).
A subsequent commit will introduce a platform where the two are different.

It would make sense for the function declarations in `psa/crypto.h` to
use `psa_key_file_id_t`. However this file is currently part of the
PSA Crypto API specification, so it must stick to the standard type
`psa_key_id_t`. Hence, as long as the specification and Mbed Crypto
are not separate, use the implementation-specific file
`psa/crypto_platform.h` to define `psa_key_id_t` as `psa_key_file_id_t`.

In the library, systematically use `psa_key_file_id_t`.

    perl -i -pe 's/psa_key_id_t/psa_key_file_id_t/g' library/*.[hc]
2019-02-20 12:52:07 +01:00
Gilles Peskine e988a66b5b Fix PSA_MAX_PERSISTENT_KEY_IDENTIFIER to mean what it says
PSA_MAX_PERSISTENT_KEY_IDENTIFIER was actually one plus the maximum
key identifier. Change it to be the maximum value, and change the code
that uses it accordingly.

There is no semantic change here (the maximum value hasn't changed).
This commit only makes the implementation clearer.
2019-02-20 12:51:37 +01:00
Gilles Peskine c8569bc5c2 Move key id validity check into its own function 2019-02-20 12:51:34 +01:00
itayzafrir 7723ab1739 Add common header for crypto service integration 2019-02-19 15:09:14 +02:00
David Saada b4ecc27629 Replace PSA error code definitions with the ones defined in PSA spec 2019-02-18 13:53:13 +02:00
Jaeden Amero cfb7ae9318
Merge pull request #16 from itayzafrir/spm-support-crypto-handles-api
Support for slots to handles crypto API changes under SPM
2019-01-23 13:38:50 +00:00
Gilles Peskine d40c1fbd50 Don't require a type and size when creating a key slot
Remove the type and bits arguments to psa_allocate_key() and
psa_create_key(). They can be useful if the implementation wants to
know exactly how much space to allocate for the slot, but many
implementations (including ours) don't care, and it's possible to work
around their lack by deferring size-dependent actions to the time when
the key material is created. They are a burden to applications and
make the API more complex, and the benefits aren't worth it.

Change the API and adapt the implementation, the units test and the
sample code accordingly.
2019-01-19 12:20:52 +01:00
itayzafrir 99974e344a SPM integration update due to crypto API changes
When MBEDTLS_PSA_CRYPTO_SPM is defined, the code is being built for SPM (Secure Partition Manager)
integration which separates the code into two parts: NSPE (Non-Secure Processing Environment) and SPE
(Secure Processing Environment). When building for the SPE, an additional header file should be included.
2019-01-16 11:13:19 +02:00
Gilles Peskine 2e14bd3aaf Add missing static on file-scope variable 2018-12-12 14:05:18 +01:00
Gilles Peskine 23fd2bdb94 Update some documentation related to key slots
Some of the documentation is obsolete in its reference to key slots
when it should discuss key handles. This may require a further pass,
possibly with some reorganization of error codes.

Update the documentation of functions that modify key slots (key
material creation and psa_set_key_policy()) to discuss how they affect
storage.
2018-12-11 16:48:14 +01:00
Gilles Peskine fa4135b135 Move more slot management functions to the proper module
Move psa_load_persistent_key_into_slot,
psa_internal_make_key_persistent and psa_internal_release_key_slot to
the slot management module.

Expose psa_import_key_into_slot from the core.

After this commit, there are no longer any functions declared in
psa_crypto_slot_management.h and defined in psa_crypto.c. There are
still function calls in both directions between psa_crypto.c and
psa_crypto_slot_management.c.
2018-12-11 16:48:14 +01:00
Gilles Peskine 66fb126e87 Move the key slot array to the slot management module
Move the key slot array and its initialization and wiping to the slot
management module.

Also move the lowest-level key slot access function psa_get_key_slot
and the auxiliary function for slot allocation
psa_internal_allocate_key_slot to the slot management module.
2018-12-11 16:48:14 +01:00
Gilles Peskine 961849f6d1 Implement slot allocation
Implement psa_allocate_key, psa_open_key, psa_create_key,
psa_close_key.

Add support for keys designated to handles to psa_get_key_slot, and
thereby to the whole API.

Allocated and non-allocated keys can coexist. This is a temporary
stage in order to transition from the use of direct slot numbers to
allocated handles only. Once all the tests and sample programs have
been migrated to use handles, the implementation will be simplified
and made more robust with support for handles only.
2018-12-11 16:48:13 +01:00