PLUGINS: Additional plugin check for the ELF loader.

The ELF loader does not have access to the symbols of the main
executable, it just relocates symbols to it via fixed offsets. We need
to make sure that loaded plugins are from the same link process to
prevent crashes. An embedded build date is used for that.

svn-id: r52730

Makefile.common

@@ -54,6 +54,10 @@ DEPFILES =
 # the build date in gScummVMBuildDate is correct.
 base/version.o: $(filter-out base/libbase.a,$(OBJS))
 
+ifdef USE_ELF_LOADER
+backends/plugins/elf/version.o: $(filter-out base/libbase.a,$(filter-out backends/libbackends.a,$(OBJS)))
+endif
+
 # Replace regular output with quiet messages
 ifneq ($(findstring $(MAKEFLAGS),s),s)
 ifneq ($(VERBOSE_BUILD),1)

backends/module.mk

@@ -28,6 +28,7 @@ MODULE_OBJS := \
 	plugins/elf/ppc-loader.o \
 	plugins/elf/arm-loader.o \
 	plugins/elf/elf-provider.o \
+	plugins/elf/version.o \
 	plugins/dc/dc-provider.o \
 	plugins/posix/posix-provider.o \
 	plugins/sdl/sdl-provider.o \

backends/plugins/elf/elf-provider.cpp

@@ -112,6 +112,19 @@ bool ELFPlugin::loadPlugin() {
 		return false;
 	}
 
+	CharFunc buildDateFunc = (CharFunc)findSymbol("PLUGIN_getBuildDate");
+	if (!buildDateFunc) {
+		unloadPlugin();
+		warning("elfloader: plugin '%s' is missing symbols", _filename.c_str());
+		return false;
+	}
+
+	if (strncmp(gScummVMPluginBuildDate, buildDateFunc(), strlen(gScummVMPluginBuildDate))) {
+		unloadPlugin();
+		warning("elfloader: plugin '%s' has a different build date", _filename.c_str());
+		return false;
+	}
+
 	bool ret = DynamicPlugin::loadPlugin();
 
 #ifdef ELF_LOADER_CXA_ATEXIT

backends/plugins/elf/elf-provider.h

@@ -45,6 +45,8 @@
  */
 class ELFPlugin : public DynamicPlugin {
 protected:
+	typedef const char *(*CharFunc)();
+
 	DLObject *_dlHandle;
 	Common::String _filename;
 	void *_dso_handle;

backends/plugins/elf/plugin.syms

@@ -1,3 +1,4 @@
+PLUGIN_getBuildDate
 PLUGIN_getVersion
 PLUGIN_getType
 PLUGIN_getTypeVersion

backends/plugins/elf/version.cpp

@@ -0,0 +1,32 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ *
+ */
+
+#include "backends/plugins/elf/version.h"
+
+#ifdef USE_ELF_LOADER
+const char *gScummVMPluginBuildDate __attribute__((visibility("hidden"))) =
+	__DATE__ " " __TIME__ ;
+#endif
+

backends/plugins/elf/version.h

@@ -0,0 +1,35 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * $URL$
+ * $Id$
+ */
+
+#ifndef BACKENDS_PLUGINS_ELF_VERSION_H
+#define BACKENDS_PLUGINS_ELF_VERSION_H
+
+#include "common/scummsys.h"
+
+#ifdef USE_ELF_LOADER
+extern const char *gScummVMPluginBuildDate;
+#endif
+
+#endif
+

base/plugins.h

@@ -30,6 +30,7 @@
 #include "common/error.h"
 #include "common/singleton.h"
 #include "common/util.h"
+#include "backends/plugins/elf/version.h"
 
 namespace Common {
 	class FSList;
@@ -98,6 +99,13 @@ extern int pluginTypeVersions[PLUGIN_TYPE_MAX];
 #define PLUGIN_DYNAMIC_DSO_HANDLE
 #endif
 
+#ifdef USE_ELF_LOADER
+#define PLUGIN_DYNAMIC_BUILD_DATE \
+	PLUGIN_EXPORT const char *PLUGIN_getBuildDate() { return gScummVMPluginBuildDate; }
+#else
+#define PLUGIN_DYNAMIC_BUILD_DATE
+#endif
+
 /**
  * REGISTER_PLUGIN_STATIC is a convenience macro which is used to declare
  * the plugin interface for static plugins. Code (such as game engines)
@@ -128,6 +136,7 @@ extern int pluginTypeVersions[PLUGIN_TYPE_MAX];
 #define REGISTER_PLUGIN_DYNAMIC(ID,TYPE,PLUGINCLASS) \
 	extern "C" { \
 		PLUGIN_DYNAMIC_DSO_HANDLE \
+		PLUGIN_DYNAMIC_BUILD_DATE \
 		PLUGIN_EXPORT int32 PLUGIN_getVersion() { return PLUGIN_VERSION; } \
 		PLUGIN_EXPORT int32 PLUGIN_getType() { return TYPE; } \
 		PLUGIN_EXPORT int32 PLUGIN_getTypeVersion() { return TYPE##_VERSION; } \

configure

@@ -2112,7 +2112,7 @@ DYNAMIC_MODULES		:= 1
 PLUGIN_PREFIX		:=
 PLUGIN_SUFFIX		:= .plg
 PLUGIN_EXTRA_DEPS	= $(EXECUTABLE)
-PLUGIN_LDFLAGS		= -nostartfiles -Wl,-q,--just-symbols,$(EXECUTABLE),--retain-symbols-file,$(srcdir)/backends/plugins/elf/plugin.syms
+PLUGIN_LDFLAGS		= -nostartfiles backends/plugins/elf/version.o -Wl,-q,--just-symbols,$(EXECUTABLE),--retain-symbols-file,$(srcdir)/backends/plugins/elf/plugin.syms
 PRE_OBJS_FLAGS		:= -Wl,--whole-archive
 POST_OBJS_FLAGS		:= -Wl,--no-whole-archive
 '"$_mak_plugins"