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Merge pull request #201 from gilles-peskine-arm/psa-se_driver-set_key_slot_number

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Add slot number attribute
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Gilles Peskine 2019-08-08 19:19:29 +02:00 committed by GitHub
commit 311809a49d
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11 changed files with 276 additions and 8 deletions
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73
include/psa/crypto_extra.h
View file

@ -104,6 +104,79 @@ static inline psa_algorithm_t psa_get_key_enrollment_algorithm(
return( attributes->core.policy.alg2 );
}
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
/** Retrieve the slot number where a key is stored.
*
* A slot number is only defined for keys that are stored in a secure
* element.
*
* This information is only useful if the secure element is not entirely
* managed through the PSA Cryptography API. It is up to the secure
* element driver to decide how PSA slot numbers map to any other interface
* that the secure element may have.
*
* \param[in] attributes The key attribute structure to query.
* \param[out] slot_number On success, the slot number containing the key.
*
* \retval #PSA_SUCCESS
* The key is located in a secure element, and \p *slot_number
* indicates the slot number that contains it.
* \retval #PSA_ERROR_NOT_PERMITTED
* The caller is not permitted to query the slot number.
* Mbed Crypto currently does not return this error.
* \retval #PSA_ERROR_INVALID_ARGUMENT
* The key is not located in a secure element.
*/
psa_status_t psa_get_key_slot_number(
const psa_key_attributes_t *attributes,
psa_key_slot_number_t *slot_number );
/** Choose the slot number where a key is stored.
*
* This function declares a slot number in the specified attribute
* structure.
*
* A slot number is only meaningful for keys that are stored in a secure
* element. It is up to the secure element driver to decide how PSA slot
* numbers map to any other interface that the secure element may have.
*
* \note Setting a slot number in key attributes for a key creation can
* cause the following errors when creating the key:
* - #PSA_ERROR_NOT_SUPPORTED if the selected secure element does
* not support choosing a specific slot number.
* - #PSA_ERROR_NOT_PERMITTED if the caller is not permitted to
* choose slot numbers in general or to choose this specific slot.
* - #PSA_ERROR_INVALID_ARGUMENT if the chosen slot number is not
* valid in general or not valid for this specific key.
* - #PSA_ERROR_ALREADY_EXISTS if there is already a key in the
* selected slot.
*
* \param[out] attributes The attribute structure to write to.
* \param slot_number The slot number to set.
*/
static inline void psa_set_key_slot_number(
psa_key_attributes_t *attributes,
psa_key_slot_number_t slot_number )
{
attributes->core.flags |= MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER;
attributes->slot_number = slot_number;
}
/** Remove the slot number attribute from a key attribute structure.
*
* This function undoes the action of psa_set_key_slot_number().
*
* \param[out] attributes The attribute structure to write to.
*/
static inline void psa_clear_key_slot_number(
psa_key_attributes_t *attributes )
{
attributes->core.flags &= ~MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER;
}
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
/**@}*/
/**

7
include/psa/crypto_se_driver.h
View file

@ -134,10 +134,17 @@ typedef psa_status_t (*psa_drv_se_init_t)(psa_drv_se_context_t *drv_context,
void *persistent_data,
psa_key_lifetime_t lifetime);
#if defined(__DOXYGEN_ONLY__) || !defined(MBEDTLS_PSA_CRYPTO_SE_C)
/* Mbed Crypto with secure element support enabled defines this type in
* crypto_types.h because it is also visible to applications through an
* implementation-specific extension.
* For the PSA Cryptography specification, this type is only visible
* via crypto_se_driver.h. */
/** An internal designation of a key slot between the core part of the
* PSA Crypto implementation and the driver. The meaning of this value
* is driver-dependent. */
typedef uint64_t psa_key_slot_number_t;
#endif /* __DOXYGEN_ONLY__ || !MBEDTLS_PSA_CRYPTO_SE_C */
/**@}*/

33
include/psa/crypto_struct.h
View file

@ -322,6 +322,29 @@ typedef uint16_t psa_key_bits_t;
* conditionals. */
#define PSA_MAX_KEY_BITS 0xfff8
/** A mask of flags that can be stored in key attributes.
*
* This type is also used internally to store flags in slots. Internal
* flags are defined in library/psa_crypto_core.h. Internal flags may have
* the same value as external flags if they are properly handled during
* key creation and in psa_get_key_attributes.
*/
typedef uint16_t psa_key_attributes_flag_t;
#define MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER \
( (psa_key_attributes_flag_t) 0x0001 )
/* A mask of key attribute flags used externally only.
* Only meant for internal checks inside the library. */
#define MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY ( \
MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER | \
0 )
/* A mask of key attribute flags used both internally and externally.
* Currently there aren't any. */
#define MBEDTLS_PSA_KA_MASK_DUAL_USE ( \
0 )
typedef struct
{
psa_key_type_t type;
@ -329,7 +352,7 @@ typedef struct
psa_key_id_t id;
psa_key_policy_t policy;
psa_key_bits_t bits;
uint16_t flags;
psa_key_attributes_flag_t flags;
} psa_core_key_attributes_t;
#define PSA_CORE_KEY_ATTRIBUTES_INIT {0, 0, 0, {0, 0, 0}, 0, 0}
@ -337,11 +360,19 @@ typedef struct
struct psa_key_attributes_s
{
psa_core_key_attributes_t core;
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
psa_key_slot_number_t slot_number;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
void *domain_parameters;
size_t domain_parameters_size;
};
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
#define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, 0, NULL, 0}
#else
#define PSA_KEY_ATTRIBUTES_INIT {PSA_CORE_KEY_ATTRIBUTES_INIT, NULL, 0}
#endif
static inline struct psa_key_attributes_s psa_key_attributes_init( void )
{
const struct psa_key_attributes_s v = PSA_KEY_ATTRIBUTES_INIT;

11
include/psa/crypto_types.h
View file

@ -244,6 +244,17 @@ typedef uint32_t psa_key_usage_t;
*/
typedef struct psa_key_attributes_s psa_key_attributes_t;
#ifndef __DOXYGEN_ONLY__
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
/* Mbed Crypto defines this type in crypto_types.h because it is also
* visible to applications through an implementation-specific extension.
* For the PSA Cryptography specification, this type is only visible
* via crypto_se_driver.h. */
typedef uint64_t psa_key_slot_number_t;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
#endif /* !__DOXYGEN_ONLY__ */
/**@}*/
/** \defgroup derivation Key derivation

51
library/psa_crypto.c
View file

@ -1187,6 +1187,13 @@ psa_status_t psa_get_key_attributes( psa_key_handle_t handle,
return( status );
attributes->core = slot->attr;
attributes->core.flags &= ( MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY |
MBEDTLS_PSA_KA_MASK_DUAL_USE );
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
if( psa_key_slot_is_external( slot ) )
psa_set_key_slot_number( attributes, slot->data.se.slot_number );
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
switch( slot->attr.type )
{
@ -1196,7 +1203,7 @@ psa_status_t psa_get_key_attributes( psa_key_handle_t handle,
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
/* TOnogrepDO: reporting the public exponent for opaque keys
* is not yet implemented. */
if( psa_get_se_driver( slot->attr.lifetime, NULL, NULL ) )
if( psa_key_slot_is_external( slot ) )
break;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
status = psa_get_rsa_public_exponent( slot->data.rsa, attributes );
@ -1212,6 +1219,21 @@ psa_status_t psa_get_key_attributes( psa_key_handle_t handle,
return( status );
}
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
psa_status_t psa_get_key_slot_number(
const psa_key_attributes_t *attributes,
psa_key_slot_number_t *slot_number )
{
if( attributes->core.flags & MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER )
{
*slot_number = attributes->slot_number;
return( PSA_SUCCESS );
}
else
return( PSA_ERROR_INVALID_ARGUMENT );
}
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
#if defined(MBEDTLS_RSA_C) || defined(MBEDTLS_ECP_C)
static int pk_write_pubkey_simple( mbedtls_pk_context *key,
unsigned char *buf, size_t size )
@ -1408,6 +1430,15 @@ psa_status_t psa_export_public_key( psa_key_handle_t handle,
data_length, 1 ) );
}
#if defined(static_assert)
static_assert( ( MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY & MBEDTLS_PSA_KA_MASK_DUAL_USE ) == 0,
"One or more key attribute flag is listed as both external-only and dual-use" );
static_assert( ( PSA_KA_MASK_INTERNAL_ONLY & MBEDTLS_PSA_KA_MASK_DUAL_USE ) == 0,
"One or more key attribute flag is listed as both internal-only and dual-use" );
static_assert( ( PSA_KA_MASK_INTERNAL_ONLY & MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY ) == 0,
"One or more key attribute flag is listed as both internal-only and external-only" );
#endif
/** Validate that a key policy is internally well-formed.
*
* This function only rejects invalid policies. It does not validate the
@ -1467,6 +1498,11 @@ static psa_status_t psa_validate_key_attributes(
if( psa_get_key_bits( attributes ) > PSA_MAX_KEY_BITS )
return( PSA_ERROR_NOT_SUPPORTED );
/* Reject invalid flags. These should not be reachable through the API. */
if( attributes->core.flags & ~ ( MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY |
MBEDTLS_PSA_KA_MASK_DUAL_USE ) )
return( PSA_ERROR_INVALID_ARGUMENT );
return( PSA_SUCCESS );
}
@ -1510,7 +1546,7 @@ static psa_status_t psa_start_key_creation(
if( status != PSA_SUCCESS )
return( status );
status = psa_internal_allocate_key_slot( handle, p_slot );
status = psa_get_empty_key_slot( handle, p_slot );
if( status != PSA_SUCCESS )
return( status );
slot = *p_slot;
@ -1523,6 +1559,13 @@ static psa_status_t psa_start_key_creation(
slot->attr = attributes->core;
/* Erase external-only flags from the internal copy. To access
* external-only flags, query `attributes`. Thanks to the check
* in psa_validate_key_attributes(), this leaves the dual-use
* flags and any internal flag that psa_get_empty_key_slot()
* may have set. */
slot->attr.flags &= ~MBEDTLS_PSA_KA_MASK_EXTERNAL_ONLY;
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
/* For a key in a secure element, we need to do three things:
* create the key file in internal storage, create the
@ -1539,6 +1582,10 @@ static psa_status_t psa_start_key_creation(
* we can roll back to a state where the key doesn't exist. */
if( *p_drv != NULL )
{
/* Choosing a slot number is not supported yet. */
if( attributes->core.flags & MBEDTLS_PSA_KA_FLAG_HAS_SLOT_NUMBER )
return( PSA_ERROR_NOT_SUPPORTED );
status = psa_find_se_slot_for_key( attributes, *p_drv,
&slot->data.se.slot_number );
if( status != PSA_SUCCESS )

7
library/psa_crypto_core.h
View file

@ -56,14 +56,21 @@ typedef struct
/* EC public key or key pair */
mbedtls_ecp_keypair *ecp;
#endif /* MBEDTLS_ECP_C */
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
/* Any key type in a secure element */
struct se
{
psa_key_slot_number_t slot_number;
} se;
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
} data;
} psa_key_slot_t;
/* A mask of key attribute flags used only internally.
* Currently there aren't any. */
#define PSA_KA_MASK_INTERNAL_ONLY ( \
0 )
/** Test whether a key slot is occupied.
*
* A key slot is occupied iff the key type is nonzero. This works because

4
library/psa_crypto_slot_management.c
View file

@ -102,7 +102,7 @@ void psa_wipe_all_key_slots( void )
global_data.key_slots_initialized = 0;
}
psa_status_t psa_internal_allocate_key_slot( psa_key_handle_t *handle,
psa_status_t psa_get_empty_key_slot( psa_key_handle_t *handle,
psa_key_slot_t **p_slot )
{
if( ! global_data.key_slots_initialized )
@ -228,7 +228,7 @@ psa_status_t psa_open_key( psa_key_file_id_t id, psa_key_handle_t *handle )
if( status != PSA_SUCCESS )
return( status );
status = psa_internal_allocate_key_slot( handle, &slot );
status = psa_get_empty_key_slot( handle, &slot );
if( status != PSA_SUCCESS )
return( status );

4
library/psa_crypto_slot_management.h
View file

@ -71,8 +71,8 @@ void psa_wipe_all_key_slots( void );
* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
* \retval #PSA_ERROR_BAD_STATE
*/
psa_status_t psa_internal_allocate_key_slot( psa_key_handle_t *handle,
psa_key_slot_t **p_slot );
psa_status_t psa_get_empty_key_slot( psa_key_handle_t *handle,
psa_key_slot_t **p_slot );
/** Test whether a lifetime designates a key in an external cryptoprocessor.
*

3
tests/suites/test_suite_psa_crypto.data
View file

@ -19,6 +19,9 @@ persistence_attributes:0x1234:3:-1:0x1234:3
PSA key attributes: lifetime then id
persistence_attributes:0x1234:3:0x1235:0x1235:3
PSA key attributes: slot number
slot_number_attribute:
PSA import/export raw: 0 bytes
import_export:"":PSA_KEY_TYPE_RAW_DATA:PSA_KEY_USAGE_EXPORT:0:0:0:PSA_SUCCESS:1

61
tests/suites/test_suite_psa_crypto.function
View file

@ -1113,6 +1113,23 @@ exit:
return( ok );
}
/* Assert that a key isn't reported as having a slot number. */
#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
#define ASSERT_NO_SLOT_NUMBER( attributes ) \
do \
{ \
psa_key_slot_number_t ASSERT_NO_SLOT_NUMBER_slot_number; \
TEST_EQUAL( psa_get_key_slot_number( \
attributes, \
&ASSERT_NO_SLOT_NUMBER_slot_number ), \
PSA_ERROR_INVALID_ARGUMENT ); \
} \
while( 0 )
#else /* MBEDTLS_PSA_CRYPTO_SE_C */
#define ASSERT_NO_SLOT_NUMBER( attributes ) \
( (void) 0 )
#endif /* MBEDTLS_PSA_CRYPTO_SE_C */
/* An overapproximation of the amount of storage needed for a key of the
* given type and with the given content. The API doesn't make it easy
* to find a good value for the size. The current implementation doesn't
@ -1214,6 +1231,46 @@ void persistence_attributes( int id1_arg, int lifetime_arg, int id2_arg,
}
/* END_CASE */
/* BEGIN_CASE depends_on:MBEDTLS_PSA_CRYPTO_SE_C */
void slot_number_attribute( )
{
psa_key_slot_number_t slot_number = 0xdeadbeef;
psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
/* Initially, there is no slot number. */
TEST_EQUAL( psa_get_key_slot_number( &attributes, &slot_number ),
PSA_ERROR_INVALID_ARGUMENT );
/* Test setting a slot number. */
psa_set_key_slot_number( &attributes, 0 );
PSA_ASSERT( psa_get_key_slot_number( &attributes, &slot_number ) );
TEST_EQUAL( slot_number, 0 );
/* Test changing the slot number. */
psa_set_key_slot_number( &attributes, 42 );
PSA_ASSERT( psa_get_key_slot_number( &attributes, &slot_number ) );
TEST_EQUAL( slot_number, 42 );
/* Test clearing the slot number. */
psa_clear_key_slot_number( &attributes );
TEST_EQUAL( psa_get_key_slot_number( &attributes, &slot_number ),
PSA_ERROR_INVALID_ARGUMENT );
/* Clearing again should have no effect. */
psa_clear_key_slot_number( &attributes );
TEST_EQUAL( psa_get_key_slot_number( &attributes, &slot_number ),
PSA_ERROR_INVALID_ARGUMENT );
/* Test that reset clears the slot number. */
psa_set_key_slot_number( &attributes, 42 );
PSA_ASSERT( psa_get_key_slot_number( &attributes, &slot_number ) );
TEST_EQUAL( slot_number, 42 );
psa_reset_key_attributes( &attributes );
TEST_EQUAL( psa_get_key_slot_number( &attributes, &slot_number ),
PSA_ERROR_INVALID_ARGUMENT );
}
/* END_CASE */
/* BEGIN_CASE */
void import_with_policy( int type_arg,
int usage_arg, int alg_arg,
@ -1246,6 +1303,7 @@ void import_with_policy( int type_arg,
TEST_EQUAL( psa_get_key_type( &got_attributes ), type );
TEST_EQUAL( psa_get_key_usage_flags( &got_attributes ), usage );
TEST_EQUAL( psa_get_key_algorithm( &got_attributes ), alg );
ASSERT_NO_SLOT_NUMBER( &got_attributes );
PSA_ASSERT( psa_destroy_key( handle ) );
test_operations_on_invalid_handle( handle );
@ -1284,6 +1342,7 @@ void import_with_data( data_t *data, int type_arg,
TEST_EQUAL( psa_get_key_type( &got_attributes ), type );
if( attr_bits != 0 )
TEST_EQUAL( attr_bits, psa_get_key_bits( &got_attributes ) );
ASSERT_NO_SLOT_NUMBER( &got_attributes );
PSA_ASSERT( psa_destroy_key( handle ) );
test_operations_on_invalid_handle( handle );
@ -1328,6 +1387,7 @@ void import_large_key( int type_arg, int byte_size_arg,
TEST_EQUAL( psa_get_key_type( &attributes ), type );
TEST_EQUAL( psa_get_key_bits( &attributes ),
PSA_BYTES_TO_BITS( byte_size ) );
ASSERT_NO_SLOT_NUMBER( &attributes );
memset( buffer, 0, byte_size + 1 );
PSA_ASSERT( psa_export_key( handle, buffer, byte_size, &n ) );
for( n = 0; n < byte_size; n++ )
@ -1420,6 +1480,7 @@ void import_export( data_t *data,
PSA_ASSERT( psa_get_key_attributes( handle, &got_attributes ) );
TEST_EQUAL( psa_get_key_type( &got_attributes ), type );
TEST_EQUAL( psa_get_key_bits( &got_attributes ), (size_t) expected_bits );
ASSERT_NO_SLOT_NUMBER( &got_attributes );
/* Export the key */
status = psa_export_key( handle,

30
tests/suites/test_suite_psa_crypto_se_driver_hal.function
View file

@ -212,6 +212,31 @@ static int check_key_attributes(
psa_get_key_bits( reference_attributes ) );
}
{
psa_key_slot_number_t actual_slot_number = 0xdeadbeef;
psa_key_slot_number_t desired_slot_number = 0xb90cc011;
psa_key_lifetime_t lifetime =
psa_get_key_lifetime( &actual_attributes );
psa_status_t status = psa_get_key_slot_number( &actual_attributes,
&actual_slot_number );
if( lifetime < MIN_DRIVER_LIFETIME )
{
/* The key is not in a secure element. */
TEST_EQUAL( status, PSA_ERROR_INVALID_ARGUMENT );
}
else
{
/* The key is in a secure element. If it had been created
* in a specific slot, check that it is reported there. */
PSA_ASSERT( status );
status = psa_get_key_slot_number( reference_attributes,
&desired_slot_number );
if( status == PSA_SUCCESS )
{
TEST_EQUAL( desired_slot_number, actual_slot_number );
}
}
}
ok = 1;
exit:
@ -485,11 +510,14 @@ void key_creation_import_export( int min_slot, int restart )
/* Test that the key was created in the expected slot. */
TEST_ASSERT( ram_slots[min_slot].type == PSA_KEY_TYPE_RAW_DATA );
/* Test the key attributes and the key data. */
/* Test the key attributes, including the reported slot number. */
psa_set_key_bits( &attributes,
PSA_BYTES_TO_BITS( sizeof( key_material ) ) );
psa_set_key_slot_number( &attributes, min_slot );
if( ! check_key_attributes( handle, &attributes ) )
goto exit;
/* Test the key data. */
PSA_ASSERT( psa_export_key( handle,
exported, sizeof( exported ),
&exported_length ) );