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psa: Check generator validity before read

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Check generator validity (i.e. that alg has been initialized) before
allowing reads from the generator or allowing reads of the generator's
capacity.

This aligns our implementation with the documented error code behavior
in our crypto.h and the PSA Crypto API.
This commit is contained in:
Jaeden Amero
2019-02-15 13:05:49 +00:00
parent 9654e11b1d
commit cf2010cf58
2 changed files with 32 additions and 15 deletions
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25
library/psa_crypto.c
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@ -3621,6 +3621,12 @@ psa_status_t psa_generator_abort( psa_crypto_generator_t *generator )
psa_status_t psa_get_generator_capacity(const psa_crypto_generator_t *generator,
size_t *capacity)
{
if( generator->alg == 0 )
{
/* This is a blank generator. */
return PSA_ERROR_BAD_STATE;
}
*capacity = generator->capacity;
return( PSA_SUCCESS );
}
@ -3850,6 +3856,12 @@ psa_status_t psa_generator_read( psa_crypto_generator_t *generator,
{
psa_status_t status;
if( generator->alg == 0 )
{
/* This is a blank generator. */
return PSA_ERROR_BAD_STATE;
}
if( output_length > generator->capacity )
{
generator->capacity = 0;
@ -3858,11 +3870,10 @@ psa_status_t psa_generator_read( psa_crypto_generator_t *generator,
status = PSA_ERROR_INSUFFICIENT_DATA;
goto exit;
}
if( output_length == 0 &&
generator->capacity == 0 && generator->alg == 0 )
if( output_length == 0 && generator->capacity == 0 )
{
/* Edge case: this is a blank or finished generator, and 0
* bytes were requested. The right error in this case could
/* Edge case: this is a finished generator, and 0 bytes
* were requested. The right error in this case could
* be either INSUFFICIENT_CAPACITY or BAD_STATE. Return
* INSUFFICIENT_CAPACITY, which is right for a finished
* generator, for consistency with the case when
@ -3911,7 +3922,13 @@ psa_status_t psa_generator_read( psa_crypto_generator_t *generator,
exit:
if( status != PSA_SUCCESS )
{
/* Preserve the algorithm upon errors, but clear all sensitive state.
* This allows us to differentiate between exhausted generators and
* blank generators, so we can return PSA_ERROR_BAD_STATE on blank
* generators. */
psa_algorithm_t alg = generator->alg;
psa_generator_abort( generator );
generator->alg = alg;
memset( output, '!', output_length );
}
return( status );