Add server-support for opaque PSKs
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 36ca0d6..54cce0a 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -149,6 +149,48 @@
}
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
+#if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
+static int ssl_conf_has_psk_or_cb( mbedtls_ssl_config const *conf )
+{
+ if( conf->f_psk != NULL )
+ return( 1 );
+
+ if( conf->psk_identity_len == 0 || conf->psk_identity == NULL )
+ return( 0 );
+
+ if( conf->psk != NULL && conf->psk_len != 0 )
+ return( 1 );
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ if( conf->psk_opaque != 0 )
+ return( 1 );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
+ return( 0 );
+}
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+static int ssl_use_opaque_psk( mbedtls_ssl_context const *ssl )
+{
+ if( ssl->conf->f_psk != NULL )
+ {
+ /* If we've used a callback to select the PSK,
+ * the static configuration is irrelevant. */
+
+ if( ssl->handshake->psk_opaque != 0 )
+ return( 1 );
+
+ return( 0 );
+ }
+
+ if( ssl->conf->psk_opaque != 0 )
+ return( 1 );
+
+ return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+#endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
+
static int ssl_parse_renegotiation_info( mbedtls_ssl_context *ssl,
const unsigned char *buf,
size_t len )
@@ -867,9 +909,7 @@
/* If the ciphersuite requires a pre-shared key and we don't
* have one, skip it now rather than failing later */
if( mbedtls_ssl_ciphersuite_uses_psk( suite_info ) &&
- ssl->conf->f_psk == NULL &&
- ( ssl->conf->psk == NULL || ssl->conf->psk_identity == NULL ||
- ssl->conf->psk_identity_len == 0 || ssl->conf->psk_len == 0 ) )
+ ssl_conf_has_psk_or_cb( ssl->conf ) == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ciphersuite mismatch: no pre-shared key" ) );
return( 0 );
@@ -3648,9 +3688,7 @@
int ret = 0;
size_t n;
- if( ssl->conf->f_psk == NULL &&
- ( ssl->conf->psk == NULL || ssl->conf->psk_identity == NULL ||
- ssl->conf->psk_identity_len == 0 || ssl->conf->psk_len == 0 ) )
+ if( ssl_conf_has_psk_or_cb( ssl->conf ) == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no pre-shared key" ) );
return( MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED );
@@ -3828,6 +3866,13 @@
return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE );
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ /* For opaque PSKs, we perform the PSK-to-MS derivation atomatically
+ * and skip the intermediate PMS. */
+ if( ssl_use_opaque_psk( ssl ) )
+ MBEDTLS_SSL_DEBUG_MSG( 1, ( "skip PMS generation for opaque PSK" ) );
+ else
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
if( ( ret = mbedtls_ssl_psk_derive_premaster( ssl,
ciphersuite_info->key_exchange ) ) != 0 )
{
@@ -3859,6 +3904,12 @@
return( ret );
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ /* Opaque PSKs are currently only supported for PSK-only. */
+ if( ssl_use_opaque_psk( ssl ) == 1 )
+ return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif
+
if( ( ret = ssl_parse_encrypted_pms( ssl, p, end, 2 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_parse_encrypted_pms" ), ret );
@@ -3888,6 +3939,12 @@
return( ret );
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ /* Opaque PSKs are currently only supported for PSK-only. */
+ if( ssl_use_opaque_psk( ssl ) == 1 )
+ return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif
+
if( p != end )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad client key exchange" ) );
@@ -3919,6 +3976,12 @@
return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP );
}
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+ /* Opaque PSKs are currently only supported for PSK-only. */
+ if( ssl_use_opaque_psk( ssl ) == 1 )
+ return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif
+
MBEDTLS_SSL_DEBUG_ECP( 3, "ECDH: Qp ", &ssl->handshake->ecdh_ctx.Qp );
if( ( ret = mbedtls_ssl_psk_derive_premaster( ssl,
