commit dfab8e221aac1c9f736f29e2c3072307ec4a29d9
author Hanno Becker <hanno.becker@arm.com> Tue Oct 23 11:59:34 2018 +0100
committer Hanno Becker <hanno.becker@arm.com> Wed Nov 21 21:12:58 2018 +0000
tree 90912f72a22298dc0a990e43dd0b24502c49d845
parent 2e4f616708747eccb6ab87a706a8ac9520ac5aa9

Allow opaque PSKs in pure-PSK ciphersuites only

In contrast, RSA-PSK, ECDHE-PSK and DHE-PSK are explicitly excluded
for the moment.

library/ssl_cli.c

diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 70ce90f..90cafeb 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -70,6 +70,23 @@
 
     return( 0 );
 }
+
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+static int ssl_conf_has_raw_psk( mbedtls_ssl_config const *conf )
+{
+    if( conf->psk_identity     == NULL ||
+        conf->psk_identity_len == 0     )
+    {
+        return( 0 );
+    }
+
+    if( conf->psk != NULL && conf->psk_len != 0 )
+        return( 1 );
+
+    return( 0 );
+}
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
 #endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
 
 #if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
@@ -778,7 +795,7 @@
     /* Don't suggest PSK-based ciphersuite if no PSK is available. */
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
     if( mbedtls_ssl_ciphersuite_uses_psk( suite_info ) &&
-        ssl_conf_has_psk( ssl ) == 0 )
+        ssl_conf_has_psk( ssl->conf ) == 0 )
     {
         return( 1 );
     }
@@ -3037,7 +3054,7 @@
         /*
          * opaque psk_identity<0..2^16-1>;
          */
-        if( ssl_conf_has_psk( ssl ) == 0 )
+        if( ssl_conf_has_psk( ssl->conf ) == 0 )
         {
             /* We don't offer PSK suites if we don't have a PSK,
              * and we check that the server's choice is among the
@@ -3071,6 +3088,12 @@
 #if defined(MBEDTLS_KEY_EXCHANGE_RSA_PSK_ENABLED)
         if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_RSA_PSK )
         {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+            /* Opaque PSKs are currently only supported for PSK-only suites. */
+            if( ssl_conf_has_raw_psk( ssl->conf ) == 0 )
+                return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
             if( ( ret = ssl_write_encrypted_pms( ssl, i, &n, 2 ) ) != 0 )
                 return( ret );
         }
@@ -3079,6 +3102,12 @@
 #if defined(MBEDTLS_KEY_EXCHANGE_DHE_PSK_ENABLED)
         if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_DHE_PSK )
         {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+            /* Opaque PSKs are currently only supported for PSK-only suites. */
+            if( ssl_conf_has_raw_psk( ssl->conf ) == 0 )
+                return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
             /*
              * ClientDiffieHellmanPublic public (DHM send G^X mod P)
              */
@@ -3109,6 +3138,12 @@
 #if defined(MBEDTLS_KEY_EXCHANGE_ECDHE_PSK_ENABLED)
         if( ciphersuite_info->key_exchange == MBEDTLS_KEY_EXCHANGE_ECDHE_PSK )
         {
+#if defined(MBEDTLS_USE_PSA_CRYPTO)
+            /* Opaque PSKs are currently only supported for PSK-only suites. */
+            if( ssl_conf_has_raw_psk( ssl->conf ) == 0 )
+                return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+#endif /* MBEDTLS_USE_PSA_CRYPTO */
+
             /*
              * ClientECDiffieHellmanPublic public;
              */