Add tests for missing CA chains and bad curves.

This commit adds four tests to tests/ssl-opt.sh:
(1) & (2): Check behaviour of optional/required verification when the
trusted CA chain is empty.
(3) & (4): Check behaviour of optional/required verification when the
client receives a server certificate with an unsupported curve.

library/ssl_tls.c

@@ -4569,6 +4569,17 @@ int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
                                             alert );
         }
 
+#if defined(MBEDTLS_DEBUG_C)
+        if( ssl->session_negotiate->verify_result != 0 )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "! Certificate verification flags %x",
+                                        ssl->session_negotiate->verify_result ) );
+        }
+        else
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 3, ( "Certificate verification flags clear" ) );
+        }
+#endif /* MBEDTLS_DEBUG_C */
     }
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate" ) );

programs/ssl/ssl_client2.c

@@ -98,6 +98,7 @@ int main( void )
 #define DFL_RECONNECT_HARD      0
 #define DFL_TICKETS             MBEDTLS_SSL_SESSION_TICKETS_ENABLED
 #define DFL_ALPN_STRING         NULL
+#define DFL_CURVES              NULL
 #define DFL_TRANSPORT           MBEDTLS_SSL_TRANSPORT_STREAM
 #define DFL_HS_TO_MIN           0
 #define DFL_HS_TO_MAX           0
@@ -178,6 +179,17 @@ int main( void )
 #define USAGE_ALPN ""
 #endif /* MBEDTLS_SSL_ALPN */
 
+#if defined(MBEDTLS_ECP_C)
+#define USAGE_CURVES \
+    "    curves=a,b,c,d      default: \"default\" (library default)\n"  \
+    "                        example: \"secp521r1,brainpoolP512r1\"\n"  \
+    "                        - use \"none\" for empty list\n"           \
+    "                        - see mbedtls_ecp_curve_list()\n"          \
+    "                          for acceptable curve names\n"
+#else
+#define USAGE_CURVES ""
+#endif
+
 #if defined(MBEDTLS_SSL_PROTO_DTLS)
 #define USAGE_DTLS \
     "    dtls=%%d             default: 0 (TLS)\n"                           \
@@ -260,6 +272,7 @@ int main( void )
     USAGE_FALLBACK                                          \
     USAGE_EMS                                               \
     USAGE_ETM                                               \
+    USAGE_CURVES                                            \
     USAGE_RECSPLIT                                          \
     USAGE_DHMLEN                                            \
     "\n"                                                    \
@@ -313,6 +326,7 @@ struct options
     int reco_delay;             /* delay in seconds before resuming session */
     int reconnect_hard;         /* unexpectedly reconnect from the same port */
     int tickets;                /* enable / disable session tickets         */
+    const char *curves;         /* list of supported elliptic curves        */
     const char *alpn_string;    /* ALPN supported protocols                 */
     int transport;              /* TLS or DTLS?                             */
     uint32_t hs_to_min;         /* Initial value of DTLS handshake timer    */
@@ -428,6 +442,11 @@ int main( int argc, char *argv[] )
 #if defined(MBEDTLS_SSL_ALPN)
     const char *alpn_list[10];
 #endif
+#if defined(MBEDTLS_ECP_C)
+    mbedtls_ecp_group_id curve_list[20];
+    const mbedtls_ecp_curve_info *curve_cur;
+#endif
+
     const char *pers = "ssl_client2";
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
@@ -524,6 +543,7 @@ int main( int argc, char *argv[] )
     opt.reconnect_hard      = DFL_RECONNECT_HARD;
     opt.tickets             = DFL_TICKETS;
     opt.alpn_string         = DFL_ALPN_STRING;
+    opt.curves              = DFL_CURVES;
     opt.transport           = DFL_TRANSPORT;
     opt.hs_to_min           = DFL_HS_TO_MIN;
     opt.hs_to_max           = DFL_HS_TO_MAX;
@@ -680,6 +700,8 @@ int main( int argc, char *argv[] )
                 default: goto usage;
             }
         }
+        else if( strcmp( p, "curves" ) == 0 )
+            opt.curves = q;
         else if( strcmp( p, "etm" ) == 0 )
         {
             switch( atoi( q ) )
@@ -937,6 +959,64 @@ int main( int argc, char *argv[] )
     }
 #endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
 
+#if defined(MBEDTLS_ECP_C)
+    if( opt.curves != NULL )
+    {
+        p = (char *) opt.curves;
+        i = 0;
+
+        if( strcmp( p, "none" ) == 0 )
+        {
+            curve_list[0] = MBEDTLS_ECP_DP_NONE;
+        }
+        else if( strcmp( p, "default" ) != 0 )
+        {
+            /* Leave room for a final NULL in curve list */
+            while( i < (int) ( sizeof( curve_list ) / sizeof( *curve_list ) ) - 1
+                   && *p != '\0' )
+            {
+                q = p;
+
+                /* Terminate the current string */
+                while( *p != ',' && *p != '\0' )
+                    p++;
+                if( *p == ',' )
+                    *p++ = '\0';
+
+                if( ( curve_cur = mbedtls_ecp_curve_info_from_name( q ) ) != NULL )
+                {
+                    curve_list[i++] = curve_cur->grp_id;
+                }
+                else
+                {
+                    mbedtls_printf( "unknown curve %s\n", q );
+                    mbedtls_printf( "supported curves: " );
+                    for( curve_cur = mbedtls_ecp_curve_list();
+                         curve_cur->grp_id != MBEDTLS_ECP_DP_NONE;
+                         curve_cur++ )
+                    {
+                        mbedtls_printf( "%s ", curve_cur->name );
+                    }
+                    mbedtls_printf( "\n" );
+                    goto exit;
+                }
+            }
+
+            mbedtls_printf("Number of curves: %d\n", i );
+
+            if( i == (int) ( sizeof( curve_list ) / sizeof( *curve_list ) ) - 1
+                && *p != '\0' )
+            {
+                mbedtls_printf( "curves list too long, maximum %zu",
+                                (size_t) ( sizeof( curve_list ) / sizeof( *curve_list ) - 1 ) );
+                goto exit;
+            }
+
+            curve_list[i] = MBEDTLS_ECP_DP_NONE;
+        }
+    }
+#endif /* MBEDTLS_ECP_C */
+
 #if defined(MBEDTLS_SSL_ALPN)
     if( opt.alpn_string != NULL )
     {
@@ -1226,6 +1306,14 @@ int main( int argc, char *argv[] )
     }
 #endif
 
+#if defined(MBEDTLS_ECP_C)
+    if( opt.curves != NULL &&
+        strcmp( opt.curves, "default" ) != 0 )
+    {
+        mbedtls_ssl_conf_curves( &conf, curve_list );
+    }
+#endif
+
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
     if( ( ret = mbedtls_ssl_conf_psk( &conf, psk, psk_len,
                              (const unsigned char *) opt.psk_identity,

programs/ssl/ssl_server2.c

@@ -134,6 +134,7 @@ int main( void )
 #define DFL_CACHE_TIMEOUT       -1
 #define DFL_SNI                 NULL
 #define DFL_ALPN_STRING         NULL
+#define DFL_CURVES              NULL
 #define DFL_DHM_FILE            NULL
 #define DFL_TRANSPORT           MBEDTLS_SSL_TRANSPORT_STREAM
 #define DFL_COOKIES             1
@@ -311,6 +312,17 @@ int main( void )
 #define USAGE_ECJPAKE ""
 #endif
 
+#if defined(MBEDTLS_ECP_C)
+#define USAGE_CURVES \
+    "    curves=a,b,c,d      default: \"default\" (library default)\n"  \
+    "                        example: \"secp521r1,brainpoolP512r1\"\n"  \
+    "                        - use \"none\" for empty list\n"           \
+    "                        - see mbedtls_ecp_curve_list()\n"          \
+    "                          for acceptable curve names\n"
+#else
+#define USAGE_CURVES ""
+#endif
+
 #define USAGE \
     "\n usage: ssl_server2 param=<>...\n"                   \
     "\n acceptable parameters:\n"                           \
@@ -347,6 +359,7 @@ int main( void )
     USAGE_ALPN                                              \
     USAGE_EMS                                               \
     USAGE_ETM                                               \
+    USAGE_CURVES                                            \
     "\n"                                                    \
     "    arc4=%%d             default: (library default: 0)\n" \
     "    allow_sha1=%%d       default: 0\n"                             \
@@ -415,6 +428,7 @@ struct options
     int cache_max;              /* max number of session cache entries      */
     int cache_timeout;          /* expiration delay of session cache entries */
     char *sni;                  /* string describing sni information        */
+    const char *curves;         /* list of supported elliptic curves        */
     const char *alpn_string;    /* ALPN supported protocols                 */
     const char *dhm_file;       /* the file with the DH parameters          */
     int extended_ms;            /* allow negotiation of extended MS?        */
@@ -871,6 +885,10 @@ int main( int argc, char *argv[] )
 #if defined(SNI_OPTION)
     sni_entry *sni_info = NULL;
 #endif
+#if defined(MBEDTLS_ECP_C)
+    mbedtls_ecp_group_id     curve_list[20];
+    const mbedtls_ecp_curve_info * curve_cur;
+#endif
 #if defined(MBEDTLS_SSL_ALPN)
     const char *alpn_list[10];
 #endif
@@ -982,6 +1000,7 @@ int main( int argc, char *argv[] )
     opt.cache_timeout       = DFL_CACHE_TIMEOUT;
     opt.sni                 = DFL_SNI;
     opt.alpn_string         = DFL_ALPN_STRING;
+    opt.curves              = DFL_CURVES;
     opt.dhm_file            = DFL_DHM_FILE;
     opt.transport           = DFL_TRANSPORT;
     opt.cookies             = DFL_COOKIES;
@@ -1060,6 +1079,8 @@ int main( int argc, char *argv[] )
             }
             opt.force_ciphersuite[1] = 0;
         }
+        else if( strcmp( p, "curves" ) == 0 )
+            opt.curves = q;
         else if( strcmp( p, "version_suites" ) == 0 )
             opt.version_suites = q;
         else if( strcmp( p, "renegotiation" ) == 0 )
@@ -1419,6 +1440,64 @@ int main( int argc, char *argv[] )
     }
 #endif /* MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED */
 
+#if defined(MBEDTLS_ECP_C)
+    if( opt.curves != NULL )
+    {
+        p = (char *) opt.curves;
+        i = 0;
+
+        if( strcmp( p, "none" ) == 0 )
+        {
+            curve_list[0] = MBEDTLS_ECP_DP_NONE;
+        }
+        else if( strcmp( p, "default" ) != 0 )
+        {
+            /* Leave room for a final NULL in curve list */
+            while( i < (int) ( sizeof( curve_list ) / sizeof( *curve_list ) ) - 1
+                   && *p != '\0' )
+            {
+                q = p;
+
+                /* Terminate the current string */
+                while( *p != ',' && *p != '\0' )
+                    p++;
+                if( *p == ',' )
+                    *p++ = '\0';
+
+                if( ( curve_cur = mbedtls_ecp_curve_info_from_name( q ) ) != NULL )
+                {
+                    curve_list[i++] = curve_cur->grp_id;
+                }
+                else
+                {
+                    mbedtls_printf( "unknown curve %s\n", q );
+                    mbedtls_printf( "supported curves: " );
+                    for( curve_cur = mbedtls_ecp_curve_list();
+                         curve_cur->grp_id != MBEDTLS_ECP_DP_NONE;
+                         curve_cur++ )
+                    {
+                        mbedtls_printf( "%s ", curve_cur->name );
+                    }
+                    mbedtls_printf( "\n" );
+                    goto exit;
+                }
+            }
+
+            mbedtls_printf("Number of curves: %d\n", i );
+
+            if( i == (int) ( sizeof( curve_list ) / sizeof( *curve_list ) ) - 1
+                && *p != '\0' )
+            {
+                mbedtls_printf( "curves list too long, maximum %zu",
+                                (size_t) ( sizeof( curve_list ) / sizeof( *curve_list ) - 1 ) );
+                goto exit;
+            }
+
+            curve_list[i] = MBEDTLS_ECP_DP_NONE;
+        }
+    }
+#endif /* MBEDTLS_ECP_C */
+
 #if defined(MBEDTLS_SSL_ALPN)
     if( opt.alpn_string != NULL )
     {
@@ -1870,6 +1949,14 @@ int main( int argc, char *argv[] )
         mbedtls_ssl_conf_sni( &conf, sni_callback, sni_info );
 #endif
 
+#if defined(MBEDTLS_ECP_C)
+    if( opt.curves != NULL &&
+        strcmp( opt.curves, "default" ) != 0 )
+    {
+        mbedtls_ssl_conf_curves( &conf, curve_list );
+    }
+#endif
+
 #if defined(MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED)
     if( strlen( opt.psk ) != 0 && strlen( opt.psk_identity ) != 0 )
     {

tests/ssl-opt.sh

@@ -1837,6 +1837,54 @@ run_test    "Authentication: server badcert, client optional" \
             -C "! mbedtls_ssl_handshake returned" \
             -C "X509 - Certificate verification failed"
 
+run_test    "Authentication: server goodcert, client optional, no trusted CA" \
+            "$P_SRV" \
+            "$P_CLI debug_level=3 auth_mode=optional ca_file=none ca_path=none" \
+            0 \
+            -c "x509_verify_cert() returned" \
+            -c "! The certificate is not correctly signed by the trusted CA" \
+            -c "! Certificate verification flags"\
+            -C "! mbedtls_ssl_handshake returned" \
+            -C "X509 - Certificate verification failed" \
+            -C "SSL - No CA Chain is set, but required to operate"
+
+run_test    "Authentication: server goodcert, client required, no trusted CA" \
+            "$P_SRV" \
+            "$P_CLI debug_level=3 auth_mode=required ca_file=none ca_path=none" \
+            1 \
+            -c "x509_verify_cert() returned" \
+            -c "! The certificate is not correctly signed by the trusted CA" \
+            -c "! Certificate verification flags"\
+            -c "! mbedtls_ssl_handshake returned" \
+            -c "SSL - No CA Chain is set, but required to operate"
+
+# The purpose of the next two tests is to test the client's behaviour when receiving a server
+# certificate with an unsupported elliptic curve. This should usually not happen because
+# the client informs the server about the supported curves - it does, though, in the
+# corner case of a static ECDH suite, because the server doesn't check the curve on that
+# occasion (to be fixed). If that bug's fixed, the test needs to be altered to use a
+# different means to have the server ignoring the client's supported curve list.
+
+requires_config_enabled MBEDTLS_ECP_C
+run_test    "Authentication: server ECDH p256v1, client required, p256v1 unsupported" \
+            "$P_SRV debug_level=1 key_file=data_files/server5.key \
+             crt_file=data_files/server5.ku-ka.crt" \
+            "$P_CLI debug_level=3 auth_mode=required curves=secp521r1" \
+            1 \
+            -c "bad certificate (EC key curve)"\
+            -c "! Certificate verification flags"\
+            -C "bad server certificate (ECDH curve)" # Expect failure at earlier verification stage
+
+requires_config_enabled MBEDTLS_ECP_C
+run_test    "Authentication: server ECDH p256v1, client optional, p256v1 unsupported" \
+            "$P_SRV debug_level=1 key_file=data_files/server5.key \
+             crt_file=data_files/server5.ku-ka.crt" \
+            "$P_CLI debug_level=3 auth_mode=optional curves=secp521r1" \
+            1 \
+            -c "bad certificate (EC key curve)"\
+            -c "! Certificate verification flags"\
+            -c "bad server certificate (ECDH curve)" # Expect failure only at ECDH params check
+
 run_test    "Authentication: server badcert, client none" \
             "$P_SRV crt_file=data_files/server5-badsign.crt \
              key_file=data_files/server5.key" \