Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

With MBEDTLS_USE_PSA_CRYPTO, some of the randomness for the TLS
connection is generated inside the PSA crypto subsystem, which has no
reproducible mode. Whether there is a nonzero amount of randomness
coming from inside the PSA subsystem rather than from the random
generator set by mbedtls_ssl_conf_rng() depends on the choice of
cipher suite and other connection parameters as well as the level of
support for MBEDTLS_USE_PSA_CRYPTO. Rather than give unreliable
results, conservatively abort with a clear error message.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Whether MBEDTLS_USE_PSA_CRYPTO is enabled makes a significant
difference with respect to how random generators are used (and, for
no-HMAC_DRBG, how ECDSA signature is dispatched), so test both with
and without it.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Test random generation as a whole. This is different from
test_suite_*_drbg and test_suite_entropy, which respectively test PRNG
modules and entropy collection.

Start with basic tests: good-case tests, and do it twice and compare
the results to validate that entropy collection doesn't repeat itself.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Expose whatever RNG the PSA subsystem uses to applications using the
mbedtls_xxx API.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

The SSL test programs can now use mbedtls_psa_get_random() rather than
entropy+DRBG as a random generator. This happens if
the configuration option MBEDTLS_USE_PSA_CRYPTO is enabled, or if
MBEDTLS_TEST_USE_PSA_CRYPTO_RNG is set at build time.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Move the call to destroy the PSK to before freeing the SSL session
data and calling rng_free(), which deinitializes the PSA subsystem.
This particular ordering was chosen to make the ssl_client2 more
similar to ssl_server2. This fixes the client failing on the
psa_destroy_key() call in `ssl-opt.sh -f 'opaque psk on client'`.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

The dependency is on MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG plus
MBEDTLS_PSA_CRYPTO_C. MBEDTLS_USE_PSA_CRYPTO is irrelevant.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

The point of having an external RNG is that you can disable all
built-in RNG functionality: both the entropy part and the DRBG part.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

The SSL test programs can now use the PSA RNG, and the PSA RNG can use
an external RNG. The build conditions hadn't been updated and didn't
cover the case when MBEDTLS_TEST_USE_PSA_CRYPTO_RNG is enabled but
MBEDTLS_USE_PSA_CRYPTO is disabled. Fix this.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

It's no longer restricted to MBEDTLS_USE_PSA_CRYPTO.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Also fix some typos.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

There was some intentional duplication between
library/psa_crypto_random_impl.h and include/mbedtls/psa_util.h, with
the intent that the compiler would complain if one file was edited in
a way that's incompatible with the other file. However, the two files
were never included together, and in fact could not be included
together because some definitions can't be duplicated (type, static
variable).

Now library/psa_crypto_random_impl.h includes
include/mbedtls/psa_util.h, so the compiler will check what it can.
There is less redundancy since it isn't always possible to declare
something twice (specifically, types can't be declared).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>