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CTR_DRBG: deprecate mbedtls_ctr_drbg_update because it ignores errors

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Deprecate mbedtls_ctr_drbg_update (which returns void) in favor of a
new function mbedtls_ctr_drbg_update_ret which reports error.
This commit is contained in:
Gilles Peskine 2018-09-11 16:41:54 +02:00
parent 1b09f4027e
commit d919993b76
3 changed files with 67 additions and 18 deletions
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36
include/mbedtls/ctr_drbg.h
View file

@ -248,9 +248,12 @@ int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx,
* \param additional The data to update the state with.
* \param add_len Length of \p additional data.
*
* \return \c 0 on success.
* \return An error from the underlying AES cipher on failure.
*/
void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional, size_t add_len );
int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional,
size_t add_len );
/**
* \brief This function updates a CTR_DRBG instance with additional
@ -290,6 +293,35 @@ int mbedtls_ctr_drbg_random_with_add( void *p_rng,
int mbedtls_ctr_drbg_random( void *p_rng,
unsigned char *output, size_t output_len );
#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
#if defined(MBEDTLS_DEPRECATED_WARNING)
#define MBEDTLS_DEPRECATED __attribute__((deprecated))
#else
#define MBEDTLS_DEPRECATED
#endif
/**
* \brief This function updates the state of the CTR_DRBG context.
*
* \deprecated Superseded by mbedtls_ctr_drbg_update_ret()
* in 2.16.0.
*
* \note If \p add_len is greater than
* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT, only the first
* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used.
* The remaining Bytes are silently discarded.
*
* \param ctx The CTR_DRBG context.
* \param additional The data to update the state with.
* \param add_len Length of \p additional data.
*/
MBEDTLS_DEPRECATED void mbedtls_ctr_drbg_update(
mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional,
size_t add_len );
#undef MBEDTLS_DEPRECATED
#endif /* !MBEDTLS_DEPRECATED_REMOVED */
#if defined(MBEDTLS_FS_IO)
/**
* \brief This function writes a seed file.

33
library/ctr_drbg.c
View file

@ -331,23 +331,38 @@ exit:
* and with outputs
* ctx = initial_working_state
*/
void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional, size_t add_len )
int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional,
size_t add_len )
{
unsigned char add_input[MBEDTLS_CTR_DRBG_SEEDLEN];
int ret;
if( add_len > 0 )
if( add_len == 0 )
return( 0 );
if( ( ret = block_cipher_df( add_input, additional, add_len ) ) != 0 )
goto exit;
if( ( ret = ctr_drbg_update_internal( ctx, add_input ) ) != 0 )
goto exit;
exit:
mbedtls_platform_zeroize( add_input, sizeof( add_input ) );
return( ret );
}
#if !defined(MBEDTLS_DEPRECATED_REMOVED)
void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
const unsigned char *additional,
size_t add_len )
{
/* MAX_INPUT would be more logical here, but we have to match
* block_cipher_df()'s limits since we can't propagate errors */
if( add_len > MBEDTLS_CTR_DRBG_MAX_SEED_INPUT )
add_len = MBEDTLS_CTR_DRBG_MAX_SEED_INPUT;
block_cipher_df( add_input, additional, add_len );
ctr_drbg_update_internal( ctx, add_input );
mbedtls_platform_zeroize( add_input, sizeof( add_input ) );
}
(void) mbedtls_ctr_drbg_update_ret( ctx, additional, add_len );
}
#endif /* MBEDTLS_DEPRECATED_REMOVED */
/* CTR_DRBG_Reseed with derivation function (SP 800-90A §10.2.1.4.2)
* mbedtls_ctr_drbg_reseed(ctx, additional, len)
@ -573,7 +588,7 @@ int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx, const char
if( fread( buf, 1, n, f ) != n )
ret = MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR;
else
mbedtls_ctr_drbg_update( ctx, buf, n );
ret = mbedtls_ctr_drbg_update_ret( ctx, buf, n );
fclose( f );

8
tests/suites/test_suite_ctr_drbg.function
View file

@ -244,9 +244,11 @@ void ctr_drbg_entropy_usage( )
}
TEST_ASSERT( last_idx == test_offset_idx );
/* Call update with too much data (sizeof entropy > MAX(_SEED)_INPUT)
* (just make sure it doesn't cause memory corruption) */
mbedtls_ctr_drbg_update( &ctx, entropy, sizeof( entropy ) );
/* Call update with too much data (sizeof entropy > MAX(_SEED)_INPUT).
* Make sure it's detected as an error and doesn't cause memory
* corruption. */
TEST_ASSERT( mbedtls_ctr_drbg_update_ret(
&ctx, entropy, sizeof( entropy ) ) != 0 );
/* Now enable PR, so the next few calls should all reseed */
mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );