Document thread safety for CTR_DRBG

random(), and only this function, is thread-safe.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine 2021-02-09 18:44:18 +01:00
parent 6e2cf25639
commit 275598d3fa

View File

@ -259,6 +259,15 @@ void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx );
* device.
*/
#endif
#if defined(MBEDTLS_THREADING_C)
/**
* \note When Mbed TLS is built with threading support,
* after this function returns successfully,
* it is safe to call mbedtls_ctr_drbg_random()
* from multiple threads. Other operations, including
* reseeding, are not thread-safe.
*/
#endif /* MBEDTLS_THREADING_C */
/**
* \param ctx The CTR_DRBG context to seed.
* It must have been initialized with
@ -268,6 +277,8 @@ void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx );
* the same context unless you call
* mbedtls_ctr_drbg_free() and mbedtls_ctr_drbg_init()
* again first.
* After a failed call to mbedtls_ctr_drbg_seed(),
* you must call mbedtls_ctr_drbg_free().
* \param f_entropy The entropy callback, taking as arguments the
* \p p_entropy context, the buffer to fill, and the
* length of the buffer.
@ -351,6 +362,11 @@ void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx,
* \brief This function reseeds the CTR_DRBG context, that is
* extracts data from the entropy source.
*
* \note This function is not thread-safe. It is not safe
* to call this function if another thread might be
* concurrently obtaining random numbers from the same
* context or updating or reseeding the same context.
*
* \param ctx The CTR_DRBG context.
* \param additional Additional data to add to the state. Can be \c NULL.
* \param len The length of the additional data.
@ -368,6 +384,11 @@ int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx,
/**
* \brief This function updates the state of the CTR_DRBG context.
*
* \note This function is not thread-safe. It is not safe
* to call this function if another thread might be
* concurrently obtaining random numbers from the same
* context or updating or reseeding the same context.
*
* \param ctx The CTR_DRBG context.
* \param additional The data to update the state with. This must not be
* \c NULL unless \p add_len is \c 0.
@ -395,6 +416,11 @@ int mbedtls_ctr_drbg_update_ret( mbedtls_ctr_drbg_context *ctx,
* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used.
* The remaining Bytes are silently discarded.
*
* \note This function is not thread-safe. It is not safe
* to call this function if another thread might be
* concurrently obtaining random numbers from the same
* context or updating or reseeding the same context.
*
* \param ctx The CTR_DRBG context.
* \param additional The data to update the state with. This must not be
* \c NULL unless \p add_len is \c 0.
@ -412,6 +438,11 @@ void mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx,
* This function automatically reseeds if the reseed counter is exceeded
* or prediction resistance is enabled.
*
* \note This function is not thread-safe. It is not safe
* to call this function if another thread might be
* concurrently obtaining random numbers from the same
* context or updating or reseeding the same context.
*
* \param p_rng The CTR_DRBG context. This must be a pointer to a
* #mbedtls_ctr_drbg_context structure.
* \param output The buffer to fill.
@ -440,8 +471,16 @@ int mbedtls_ctr_drbg_random_with_add( void *p_rng,
*
* This function automatically reseeds if the reseed counter is exceeded
* or prediction resistance is enabled.
*
*
*/
#if defined(MBEDTLS_THREADING_C)
/**
* \note When Mbed TLS is built with threading support,
* it is safe to call mbedtls_ctr_drbg_random()
* from multiple threads. Other operations, including
* reseeding, are not thread-safe.
*/
#endif /* MBEDTLS_THREADING_C */
/**
* \param p_rng The CTR_DRBG context. This must be a pointer to a
* #mbedtls_ctr_drbg_context structure.
* \param output The buffer to fill.