Merge pull request #8862 from valeriosetti/issue8825
Improve support of mbedtls_psa_get_random in client-only builds
diff --git a/ChangeLog.d/8825.txt b/ChangeLog.d/8825.txt
new file mode 100644
index 0000000..914bd08
--- /dev/null
+++ b/ChangeLog.d/8825.txt
@@ -0,0 +1,6 @@
+Features
+ * mbedtls_psa_get_random() is always available as soon as
+ MBEDTLS_PSA_CRYPTO_CLIENT is enabled at build time and psa_crypto_init() is
+ called at runtime. This together with MBEDTLS_PSA_RANDOM_STATE can be
+ used as random number generator function (f_rng) and context (p_rng) in
+ legacy functions.
diff --git a/include/mbedtls/psa_util.h b/include/mbedtls/psa_util.h
index 984f031..c78cc23 100644
--- a/include/mbedtls/psa_util.h
+++ b/include/mbedtls/psa_util.h
@@ -21,44 +21,24 @@
* otherwise error codes would be unknown in test_suite_psa_crypto_util.data.*/
#include <mbedtls/asn1write.h>
-#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)
+#if defined(MBEDTLS_PSA_CRYPTO_CLIENT)
/** 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 @@
/** 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
* @{
@@ -180,7 +139,7 @@
{
return (mbedtls_md_type_t) (psa_alg & PSA_ALG_HASH_MASK);
}
-#endif /* MBEDTLS_PSA_CRYPTO_C */
+#endif /* MBEDTLS_PSA_CRYPTO_CLIENT */
#if defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA)
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index d4a8307..31d340d 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -101,11 +101,6 @@
static psa_global_data_t global_data;
-#if !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
-mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state =
- &global_data.rng.drbg;
-#endif
-
#define GUARD_MODULE_INITIALIZED \
if (global_data.initialized == 0) \
return PSA_ERROR_BAD_STATE;
@@ -7103,7 +7098,7 @@
MBEDTLS_ENTROPY_SOURCE_STRONG);
#endif
- mbedtls_psa_drbg_init(MBEDTLS_PSA_RANDOM_STATE);
+ mbedtls_psa_drbg_init(&rng->drbg);
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
@@ -7114,7 +7109,7 @@
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
memset(rng, 0, sizeof(*rng));
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
- mbedtls_psa_drbg_free(MBEDTLS_PSA_RANDOM_STATE);
+ mbedtls_psa_drbg_free(&rng->drbg);
rng->entropy_free(&rng->entropy);
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
@@ -7129,7 +7124,7 @@
return PSA_SUCCESS;
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
const unsigned char drbg_seed[] = "PSA";
- int ret = mbedtls_psa_drbg_seed(&rng->entropy,
+ int ret = mbedtls_psa_drbg_seed(&rng->drbg, &rng->entropy,
drbg_seed, sizeof(drbg_seed) - 1);
return mbedtls_to_psa_error(ret);
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
@@ -7159,12 +7154,16 @@
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
while (output_size > 0) {
+ int ret = MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED;
size_t request_size =
(output_size > MBEDTLS_PSA_RANDOM_MAX_REQUEST ?
MBEDTLS_PSA_RANDOM_MAX_REQUEST :
output_size);
- int ret = mbedtls_psa_get_random(MBEDTLS_PSA_RANDOM_STATE,
- output, request_size);
+#if defined(MBEDTLS_CTR_DRBG_C)
+ ret = mbedtls_ctr_drbg_random(&global_data.rng.drbg, output, request_size);
+#elif defined(MBEDTLS_HMAC_DRBG_C)
+ ret = mbedtls_hmac_drbg_random(&global_data.rng.drbg, output, request_size);
+#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
if (ret != 0) {
return mbedtls_to_psa_error(ret);
}
@@ -7175,39 +7174,6 @@
#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
}
-/* Wrapper function allowing the classic API to use the PSA RNG.
- *
- * `mbedtls_psa_get_random(MBEDTLS_PSA_RANDOM_STATE, ...)` calls
- * `psa_generate_random(...)`. The state parameter is ignored since the
- * PSA API doesn't support passing an explicit state.
- *
- * In the non-external case, psa_generate_random() calls an
- * `mbedtls_xxx_drbg_random` function which has exactly the same signature
- * and semantics as mbedtls_psa_get_random(). As an optimization,
- * instead of doing this back-and-forth between the PSA API and the
- * classic API, psa_crypto_random_impl.h defines `mbedtls_psa_get_random`
- * as a constant function pointer to `mbedtls_xxx_drbg_random`.
- */
-#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
-int mbedtls_psa_get_random(void *p_rng,
- unsigned char *output,
- size_t output_size)
-{
- /* This function takes a pointer to the RNG state because that's what
- * classic mbedtls functions using an RNG expect. The PSA RNG manages
- * its own state internally and doesn't let the caller access that state.
- * So we just ignore the state parameter, and in practice we'll pass
- * NULL. */
- (void) p_rng;
- psa_status_t status = psa_generate_random(output, output_size);
- if (status == PSA_SUCCESS) {
- return 0;
- } else {
- return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
- }
-}
-#endif /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
-
#if defined(MBEDTLS_PSA_INJECT_ENTROPY)
psa_status_t mbedtls_psa_inject_entropy(const uint8_t *seed,
size_t seed_size)
diff --git a/library/psa_crypto_random_impl.h b/library/psa_crypto_random_impl.h
index 64b8949..533fb2e 100644
--- a/library/psa_crypto_random_impl.h
+++ b/library/psa_crypto_random_impl.h
@@ -1,14 +1,6 @@
/** \file psa_crypto_random_impl.h
*
* \brief PSA crypto random generator implementation abstraction.
- *
- * The definitions here need to be consistent with the declarations
- * in include/psa_util_internal.h. This file contains some redundant
- * declarations to increase the chance that a compiler will detect
- * inconsistencies if one file is changed without updating the other,
- * but not all potential inconsistencies can be enforced, so make sure
- * to check the public declarations and contracts in
- * include/psa_util_internal.h if you modify this file.
*/
/*
* Copyright The Mbed TLS Contributors
@@ -22,22 +14,12 @@
#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
-#include <string.h>
-#include <mbedtls/entropy.h> // only for error codes
-#include <psa/crypto.h>
-
typedef mbedtls_psa_external_random_context_t mbedtls_psa_random_context_t;
-/* Trivial wrapper around psa_generate_random(). */
-int mbedtls_psa_get_random(void *p_rng,
- unsigned char *output,
- size_t output_size);
-
-/* The PSA RNG API doesn't need any externally maintained state. */
-#define MBEDTLS_PSA_RANDOM_STATE NULL
-
#else /* MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG */
+#include "mbedtls/entropy.h"
+
/* Choose a DRBG based on configuration and availability */
#if defined(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE)
@@ -67,11 +49,37 @@
#error "No hash algorithm available for HMAC_DBRG."
#endif
-#else
+#else /* !MBEDTLS_PSA_HMAC_DRBG_MD_TYPE && !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
+
#error "No DRBG module available for the psa_crypto module."
+
+#endif /* !MBEDTLS_PSA_HMAC_DRBG_MD_TYPE && !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C*/
+
+#if defined(MBEDTLS_CTR_DRBG_C)
+#include "mbedtls/ctr_drbg.h"
+#elif defined(MBEDTLS_HMAC_DRBG_C)
+#include "mbedtls/hmac_drbg.h"
+#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
+
+/* The maximum number of bytes that mbedtls_psa_get_random() is expected to return. */
+#if defined(MBEDTLS_CTR_DRBG_C)
+#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST
+#elif defined(MBEDTLS_HMAC_DRBG_C)
+#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
#endif
-#include "mbedtls/entropy.h"
+#if defined(MBEDTLS_CTR_DRBG_C)
+typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
+#elif defined(MBEDTLS_HMAC_DRBG_C)
+typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t;
+#endif /* !MBEDTLS_CTR_DRBG_C && !MBEDTLS_HMAC_DRBG_C */
+
+typedef struct {
+ void (* entropy_init)(mbedtls_entropy_context *ctx);
+ void (* entropy_free)(mbedtls_entropy_context *ctx);
+ mbedtls_entropy_context entropy;
+ mbedtls_psa_drbg_context_t drbg;
+} mbedtls_psa_random_context_t;
/** Initialize the PSA DRBG.
*
@@ -99,63 +107,6 @@
#endif
}
-/** The type of the PSA random generator context.
- *
- * The random generator context is composed of an entropy context and
- * a DRBG context.
- */
-typedef struct {
- void (* entropy_init)(mbedtls_entropy_context *ctx);
- void (* entropy_free)(mbedtls_entropy_context *ctx);
- mbedtls_entropy_context entropy;
- mbedtls_psa_drbg_context_t drbg;
-} mbedtls_psa_random_context_t;
-
-/* Defined in include/psa_util_internal.h so that it's visible to
- * application code. The declaration here is redundant, but included
- * as a safety net to make it more likely that a future change that
- * accidentally causes the implementation to diverge from the interface
- * will be noticed. */
-/* Do not include the declaration under MSVC because it doesn't accept it
- * ("error C2370: 'mbedtls_psa_get_random' : redefinition; different storage class").
- * Observed with Visual Studio 2013. A known bug apparently:
- * https://stackoverflow.com/questions/8146541/duplicate-external-static-declarations-not-allowed-in-visual-studio
- */
-#if !defined(_MSC_VER)
-static mbedtls_f_rng_t *const mbedtls_psa_get_random;
-#endif
-
-/** The maximum number of bytes that mbedtls_psa_get_random() is expected to
- * return.
- */
-#if defined(MBEDTLS_CTR_DRBG_C)
-#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_CTR_DRBG_MAX_REQUEST
-#elif defined(MBEDTLS_HMAC_DRBG_C)
-#define MBEDTLS_PSA_RANDOM_MAX_REQUEST MBEDTLS_HMAC_DRBG_MAX_REQUEST
-#endif
-
-/** A pointer to the PSA DRBG state.
- *
- * This variable is only intended to be used through the macro
- * #MBEDTLS_PSA_RANDOM_STATE.
- */
-/* psa_crypto.c sets this variable to a pointer to the DRBG state in the
- * global PSA crypto state. */
-/* The type `mbedtls_psa_drbg_context_t` is defined in
- * include/psa_util_internal.h so that `mbedtls_psa_random_state` can be
- * declared there and be visible to application code. */
-extern mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state;
-
-/** A pointer to the PSA DRBG state.
- *
- * This macro expands to an expression that is suitable as the \c p_rng
- * parameter to pass to mbedtls_psa_get_random().
- *
- * This macro exists in all configurations where the psa_crypto module is
- * enabled. Its expansion depends on the configuration.
- */
-#define MBEDTLS_PSA_RANDOM_STATE mbedtls_psa_random_state
-
/** Seed the PSA DRBG.
*
* \param entropy An entropy context to read the seed from.
@@ -167,23 +118,15 @@
* \return \c 0 on success.
* \return An Mbed TLS error code (\c MBEDTLS_ERR_xxx) on failure.
*/
-static inline int mbedtls_psa_drbg_seed(
- mbedtls_entropy_context *entropy,
- const unsigned char *custom, size_t len)
+static inline int mbedtls_psa_drbg_seed(mbedtls_psa_drbg_context_t *drbg_ctx,
+ mbedtls_entropy_context *entropy,
+ const unsigned char *custom, size_t len)
{
#if defined(MBEDTLS_CTR_DRBG_C)
- return mbedtls_ctr_drbg_seed(MBEDTLS_PSA_RANDOM_STATE,
- mbedtls_entropy_func,
- entropy,
- custom, len);
+ return mbedtls_ctr_drbg_seed(drbg_ctx, mbedtls_entropy_func, entropy, custom, len);
#elif defined(MBEDTLS_HMAC_DRBG_C)
- const mbedtls_md_info_t *md_info =
- mbedtls_md_info_from_type(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE);
- return mbedtls_hmac_drbg_seed(MBEDTLS_PSA_RANDOM_STATE,
- md_info,
- mbedtls_entropy_func,
- entropy,
- custom, len);
+ const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type(MBEDTLS_PSA_HMAC_DRBG_MD_TYPE);
+ return mbedtls_hmac_drbg_seed(drbg_ctx, md_info, mbedtls_entropy_func, entropy, custom, len);
#endif
}
diff --git a/library/psa_util.c b/library/psa_util.c
index 125b173..4ccc5b0 100644
--- a/library/psa_util.c
+++ b/library/psa_util.c
@@ -18,7 +18,7 @@
#include "psa_util_internal.h"
-#if defined(MBEDTLS_PSA_CRYPTO_C)
+#if defined(MBEDTLS_PSA_CRYPTO_CLIENT)
#include <psa/crypto.h>
@@ -46,6 +46,7 @@
#if defined(MBEDTLS_BLOCK_CIPHER_SOME_PSA)
#include <mbedtls/cipher.h>
#endif
+#include <mbedtls/entropy.h>
/* PSA_SUCCESS is kept at the top of each error table since
* it's the most common status when everything functions properly. */
@@ -338,7 +339,31 @@
}
#endif /* PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY */
-#endif /* MBEDTLS_PSA_CRYPTO_C */
+/* Wrapper function allowing the classic API to use the PSA RNG.
+ *
+ * `mbedtls_psa_get_random(MBEDTLS_PSA_RANDOM_STATE, ...)` calls
+ * `psa_generate_random(...)`. The state parameter is ignored since the
+ * PSA API doesn't support passing an explicit state.
+ */
+int mbedtls_psa_get_random(void *p_rng,
+ unsigned char *output,
+ size_t output_size)
+{
+ /* This function takes a pointer to the RNG state because that's what
+ * classic mbedtls functions using an RNG expect. The PSA RNG manages
+ * its own state internally and doesn't let the caller access that state.
+ * So we just ignore the state parameter, and in practice we'll pass
+ * NULL. */
+ (void) p_rng;
+ psa_status_t status = psa_generate_random(output, output_size);
+ if (status == PSA_SUCCESS) {
+ return 0;
+ } else {
+ return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
+ }
+}
+
+#endif /* MBEDTLS_PSA_CRYPTO_CLIENT */
#if defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA)
diff --git a/library/psa_util_internal.h b/library/psa_util_internal.h
index 3e62d5f..70a08a0 100644
--- a/library/psa_util_internal.h
+++ b/library/psa_util_internal.h
@@ -16,7 +16,7 @@
#include "psa/crypto.h"
-#if defined(MBEDTLS_PSA_CRYPTO_C)
+#if defined(MBEDTLS_PSA_CRYPTO_CLIENT)
/*************************************************************************
* FFDH
@@ -96,5 +96,5 @@
sizeof(error_list)/sizeof(error_list[0]), \
fallback_f)
-#endif /* MBEDTLS_PSA_CRYPTO_C */
+#endif /* MBEDTLS_PSA_CRYPTO_CLIENT */
#endif /* MBEDTLS_PSA_UTIL_INTERNAL_H */
diff --git a/tests/src/psa_crypto_stubs.c b/tests/src/psa_crypto_stubs.c
new file mode 100644
index 0000000..f3ca850
--- /dev/null
+++ b/tests/src/psa_crypto_stubs.c
@@ -0,0 +1,25 @@
+/** \file psa_crypto_stubs.c
+ *
+ * \brief Stub functions when MBEDTLS_PSA_CRYPTO_CLIENT is enabled but
+ * MBEDTLS_PSA_CRYPTO_C is disabled.
+ */
+
+/*
+ * Copyright The Mbed TLS Contributors
+ * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
+ */
+
+#include <psa/crypto.h>
+
+#if defined(MBEDTLS_PSA_CRYPTO_CLIENT) && !defined(MBEDTLS_PSA_CRYPTO_C)
+
+psa_status_t psa_generate_random(uint8_t *output,
+ size_t output_size)
+{
+ (void) output;
+ (void) output_size;
+
+ return PSA_ERROR_COMMUNICATION_FAILURE;
+}
+
+#endif /* MBEDTLS_PSA_CRYPTO_CLIENT && !MBEDTLS_PSA_CRYPTO_C */