Implement stricter extension compatibility check

This hardens the dynamic module loading by checking the linker compatibility
between the core and the dynamic module. This likely should be extended
for the CRT as well, as 2015, 2017 and 2019 versions of Visual Studio
all have same DLL name for the CRT.

1 files changed, 37 insertions, 0 deletions

diff --git a/win32/winutil.c b/win32/winutil.c
index 366a48bb11..18f890fb33 100644
--- a/win32/winutil.c
+++ b/win32/winutil.c
@@ -22,6 +22,8 @@
 #include "codepage.h"
 #include <bcrypt.h>
 #include <lmcons.h>
+#include <imagehlp.h>
+
 
 PHP_WINUTIL_API char *php_win32_error_to_msg(HRESULT error)
 {/*{{{*/
@@ -435,3 +437,38 @@ PHP_WINUTIL_API char *php_win32_get_username(void)
 
 	return uname;
 }/*}}}*/
+
+PHP_WINUTIL_API BOOL php_win32_image_compatible(const char *name, const char *path, char **err)
+{/*{{{*/
+	PLOADED_IMAGE img = ImageLoad(name, NULL);
+
+	if (!img) {
+		DWORD _err = GetLastError();
+		char *err_txt = php_win32_error_to_msg(_err);
+		spprintf(err, 0, "Failed to load %s, %s", name, err_txt);
+		free(err_txt);
+		return FALSE;
+	}
+	
+	DWORD major = img->FileHeader->OptionalHeader.MajorLinkerVersion;
+	DWORD minor = img->FileHeader->OptionalHeader.MinorLinkerVersion;
+
+	/* VS 2015, 2017 and 2019 are binary compatible, but only forward compatible.
+		It should be fine, if we load a module linked with an older one into
+		the core linked with the newer one, but not the otherway round.
+		Otherwise, if the linker major version is not same, it is an error, as
+		per the current knowledge.
+		
+		This check is to be extended as new VS versions come out. */
+	if (14 == major && PHP_LINKER_MINOR < minor
+			|| PHP_LINKER_MAJOR != major) {
+		spprintf(err, 0, "Can't load module '%s' as it's linked with %u.%u, but the core is linked with %d.%d", name, major, minor, PHP_LINKER_MAJOR, PHP_LINKER_MINOR);
+		ImageUnload(img);
+		return FALSE;
+	}
+
+	ImageUnload(img);
+
+	return TRUE;
+}/*}}}*/
+