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

9 files changed, 98 insertions, 1 deletions

diff --git a/Makefile.common b/Makefile.common
index 14d73405fd..cf8626ce3c 100644
--- a/Makefile.common
+++ b/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)
diff --git a/backends/module.mk b/backends/module.mk
index e0bdd26cf7..b3a23f10e7 100644
--- a/backends/module.mk
+++ b/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 \
diff --git a/backends/plugins/elf/elf-provider.cpp b/backends/plugins/elf/elf-provider.cpp
index 8629de6c45..d1c8f6aa05 100644
--- a/backends/plugins/elf/elf-provider.cpp
+++ b/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
diff --git a/backends/plugins/elf/elf-provider.h b/backends/plugins/elf/elf-provider.h
index 92fe5d63d1..0309ffcece 100644
--- a/backends/plugins/elf/elf-provider.h
+++ b/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;
diff --git a/backends/plugins/elf/plugin.syms b/backends/plugins/elf/plugin.syms
index 24ee1a19dc..70465ae976 100644
--- a/backends/plugins/elf/plugin.syms
+++ b/backends/plugins/elf/plugin.syms
@@ -1,3 +1,4 @@
+PLUGIN_getBuildDate
 PLUGIN_getVersion
 PLUGIN_getType
 PLUGIN_getTypeVersion
diff --git a/backends/plugins/elf/version.cpp b/backends/plugins/elf/version.cpp
new file mode 100644
index 0000000000..0277c6ae1c
--- /dev/null
+++ b/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
+
diff --git a/backends/plugins/elf/version.h b/backends/plugins/elf/version.h
new file mode 100644
index 0000000000..726204aeb7
--- /dev/null
+++ b/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
+
diff --git a/base/plugins.h b/base/plugins.h
index 0893312102..5472ab2fce 100644
--- a/base/plugins.h
+++ b/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; } \
diff --git a/configure b/configure
index a12a37540f..95104491b4 100755
--- a/configure
+++ b/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"