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psa: let mbedtls_psa_get_random() always use psa_generate_random()

It means that mbedtls_psa_get_random() goes through the PSA interface
all the times. Fallbacks to CTR_DRBG or HMAC_DRBG are still possible,
but that depends on how the crypto provider is built.

Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
This commit is contained in:
Valerio Setti
2024-02-26 12:03:59 +01:00
parent bb91bcda0e
commit a53e7a5cb5
4 changed files with 37 additions and 116 deletions

View File

@@ -23,42 +23,22 @@
#if defined(MBEDTLS_PSA_CRYPTO_C)
/* Expose whatever RNG the PSA subsystem uses to applications using the
* mbedtls_xxx API. The declarations and definitions here need to be
* consistent with the implementation in library/psa_crypto_random_impl.h.
* See that file for implementation documentation. */
/* The type of a `f_rng` random generator function that many library functions
* take.
*
* This type name is not part of the Mbed TLS stable API. It may be renamed
* or moved without warning.
*/
typedef int mbedtls_f_rng_t(void *p_rng, unsigned char *output, size_t output_size);
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
/** The random generator function for the PSA subsystem.
*
* This function is suitable as the `f_rng` random generator function
* parameter of many `mbedtls_xxx` functions. Use #MBEDTLS_PSA_RANDOM_STATE
* to obtain the \p p_rng parameter.
* parameter of many `mbedtls_xxx` functions.
*
* The implementation of this function depends on the configuration of the
* library.
*
* \note Depending on the configuration, this may be a function or
* a pointer to a function.
*
* \note This function may only be used if the PSA crypto subsystem is active.
* This means that you must call psa_crypto_init() before any call to
* this function, and you must not call this function after calling
* mbedtls_psa_crypto_free().
*
* \param p_rng The random generator context. This must be
* #MBEDTLS_PSA_RANDOM_STATE. No other state is
* supported.
* \param p_rng This parameter is only kept for backward compatibility
* reasons with legacy `f_rng` functions and it's ignored.
* Set to #MBEDTLS_PSA_RANDOM_STATE or NULL.
* \param output The buffer to fill. It must have room for
* \c output_size bytes.
* \param output_size The number of bytes to write to \p output.
@@ -80,32 +60,11 @@ int mbedtls_psa_get_random(void *p_rng,
/** The random generator state for the PSA subsystem.
*
* This macro expands to an expression which is suitable as the `p_rng`
* random generator state parameter of many `mbedtls_xxx` functions.
* It must be used in combination with the random generator function
* mbedtls_psa_get_random().
*
* The implementation of this macro depends on the configuration of the
* library. Do not make any assumption on its nature.
* This macro always expands to NULL because the `p_rng` parameter is unused
* in mbedtls_psa_get_random(), but it's kept for interface's backward
* compatibility.
*/
#define MBEDTLS_PSA_RANDOM_STATE NULL
#else /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */
#if defined(MBEDTLS_CTR_DRBG_C)
#include "mbedtls/ctr_drbg.h"
typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_ctr_drbg_random;
#elif defined(MBEDTLS_HMAC_DRBG_C)
#include "mbedtls/hmac_drbg.h"
typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t;
static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_hmac_drbg_random;
#endif
extern mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state;
#define MBEDTLS_PSA_RANDOM_STATE mbedtls_psa_random_state
#endif /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */
#define MBEDTLS_PSA_RANDOM_STATE NULL
/** \defgroup psa_tls_helpers TLS helper functions
* @{