New test app for dynamic loading of libmbed* with dlopen

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

programs/.gitignore

@@ -54,6 +54,7 @@ ssl/ssl_server2
 test/benchmark
 test/cpp_dummy_build
 test/cpp_dummy_build.cpp
+test/dlopen
 test/ecp-bench
 test/query_compile_time_config
 test/selftest

programs/Makefile

@@ -114,6 +114,10 @@ ifdef PTHREAD
 APPS +=	ssl/ssl_pthread_server$(EXEXT)
 endif
 
+ifdef SHARED
+APPS +=	test/dlopen
+endif
+
 ifdef TEST_CPP
 APPS += test/cpp_dummy_build$(EXEXT)
 endif
@@ -318,6 +322,15 @@ test/cpp_dummy_build$(EXEXT): test/cpp_dummy_build.cpp $(DEP)
 	echo "  CXX   test/cpp_dummy_build.cpp"
 	$(CXX) $(LOCAL_CXXFLAGS) $(CXXFLAGS) test/cpp_dummy_build.cpp   $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
 
+ifdef SHARED
+test/dlopen$(EXEXT): test/dlopen.c $(DEP)
+	echo "  CC    test/dlopen.c"
+# Do not link any test objects (that would bring in a static dependency on
+# libmbedcrypto at least). Do not link with libmbed* (that would defeat the
+# purpose of testing dynamic loading).
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) test/dlopen.c $(LDFLAGS) -ldl -o $@
+endif
+
 test/query_config.o: test/query_config.c test/query_config.h $(DEP)
 	echo "  CC    test/query_config.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) -c test/query_config.c -o $@
@@ -379,6 +392,7 @@ ifndef WINDOWS
 	rm -f $(APPS)
 	-rm -f ssl/ssl_pthread_server$(EXEXT)
 	-rm -f test/cpp_dummy_build.cpp test/cpp_dummy_build$(EXEXT)
+	-rm -f test/dlopen$(EXEXT)
 else
 	if exist *.o del /Q /F *.o
 	if exist *.exe del /Q /F *.exe

programs/test/CMakeLists.txt

@@ -35,6 +35,12 @@ if(TEST_CPP)
     target_link_libraries(cpp_dummy_build ${mbedcrypto_target})
 endif()
 
+if(USE_SHARED_MBEDTLS_LIBRARY)
+    add_executable(dlopen "dlopen.c")
+    target_include_directories(dlopen PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../../include)
+    target_link_libraries(dlopen "-ldl")
+endif()
+
 foreach(exe IN LISTS executables_libs executables_mbedcrypto)
     set(extra_sources "")
     if(exe STREQUAL "query_compile_time_config")

programs/test/dlopen.c

@@ -0,0 +1,102 @@
+/*
+ *  Test dynamic loading of libmbed*
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+#include "mbedtls/config.h"
+
+#include "mbedtls/platform.h"
+#if !defined(MBEDTLS_PLATFORM_C)
+#include <stdio.h>
+#include <stdlib.h>
+#define mbedtls_fprintf    fprintf
+#define mbedtls_printf     printf
+#define mbedtls_exit       exit
+#define MBEDTLS_EXIT_SUCCESS EXIT_SUCCESS
+#define MBEDTLS_EXIT_FAILURE EXIT_FAILURE
+#endif
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+#include "mbedtls/x509_crt.h"
+#endif
+
+#define CRYPTO_SO_FILENAME "libmbedcrypto.so"
+#define X509_SO_FILENAME "libmbedx509.so"
+#define TLS_SO_FILENAME "libmbedtls.so"
+
+#include <dlfcn.h>
+
+#define CHECK_DLERROR( function, argument )                             \
+    do                                                                  \
+    {                                                                   \
+        char *CHECK_DLERROR_error = dlerror ( );                        \
+        if( CHECK_DLERROR_error != NULL )                               \
+        {                                                               \
+            fprintf( stderr, "Dynamic loading error for %s(%s): %s\n",  \
+                     function, argument, CHECK_DLERROR_error );         \
+            mbedtls_exit( MBEDTLS_EXIT_FAILURE );                       \
+        }                                                               \
+    }                                                                   \
+    while( 0 )
+
+int main( void )
+{
+    unsigned n;
+
+#if defined(MBEDTLS_SSL_TLS_C)
+    void *tls_so = dlopen( TLS_SO_FILENAME, RTLD_NOW );
+    CHECK_DLERROR( "dlopen", TLS_SO_FILENAME );
+    const int *( *ssl_list_ciphersuites )( void ) =
+        dlsym( tls_so, "mbedtls_ssl_list_ciphersuites" );
+    CHECK_DLERROR( "dlsym", "mbedtls_ssl_list_ciphersuites" );
+    const int *ciphersuites = ssl_list_ciphersuites( );
+    for( n = 0; ciphersuites[n] != 0; n++ )
+        /* nothing to do, we're just counting */;
+    mbedtls_printf( "%u ciphersuites\n", n );
+    dlclose( tls_so );
+    CHECK_DLERROR( "dlclose", TLS_SO_FILENAME );
+#endif  /* MBEDTLS_SSL_TLS_C */
+
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+    void *x509_so = dlopen( X509_SO_FILENAME, RTLD_NOW );
+    CHECK_DLERROR( "dlopen", X509_SO_FILENAME );
+    const mbedtls_x509_crt_profile *profile =
+        dlsym( x509_so, "mbedtls_x509_crt_profile_default" );
+    CHECK_DLERROR( "dlsym", "mbedtls_x509_crt_profile_default" );
+    mbedtls_printf( "Allowed md mask: %08x\n",
+                    (unsigned) profile->allowed_mds );
+    dlclose( x509_so );
+    CHECK_DLERROR( "dlclose", X509_SO_FILENAME );
+#endif  /* MBEDTLS_X509_CRT_PARSE_C */
+
+#if defined(MBEDTLS_MD_C)
+    void *crypto_so = dlopen( CRYPTO_SO_FILENAME, RTLD_NOW );
+    CHECK_DLERROR( "dlopen", CRYPTO_SO_FILENAME );
+    const int *( *md_list )( void ) =
+        dlsym( crypto_so, "mbedtls_md_list" );
+    CHECK_DLERROR( "dlsym", "mbedtls_md_list" );
+    const int *mds = md_list( );
+    for( n = 0; mds[n] != 0; n++ )
+        /* nothing to do, we're just counting */;
+    mbedtls_printf( "%u hashes\n", n );
+    dlclose( crypto_so );
+    CHECK_DLERROR( "dlclose", CRYPTO_SO_FILENAME );
+#endif  /* MBEDTLS_MD_C */
+
+    return( 0 );
+}
+