Load plugins with RTLD_NODELETE if possible

On platforms which support RTLD_NODELETE, use it to load plugin
modules.  While using this flag makes plugins stay in the process map
after libkrb5/libgssapi_krb5 are unloaded, it solves several problems:

1. It prevents plugin modules which link against OpenSSL (PKINIT and
k5tls) from repeatedly initializing instances of libssl or libcrypto,
leaking heap memory each time.  This is only an issue because we
cannot safely uninitialize OpenSSL.

2. It prevents finalization ordering issues from causing a process
crash when unloading libgssapi_krb5 (issue #7135).

3. It makes memory leak tracing with valgrind easier.

ticket: 7947 (new)

diff --git a/src/util/support/plugins.c b/src/util/support/plugins.c
index a04dfc38e9e53bab47430fc1a859f548e6038608..ca4b1285821414aaa4a8c688eae52a10bcaab447 100644 (file)
--- a/src/util/support/plugins.c
+++ b/src/util/support/plugins.c
@@ -45,6 +45,20 @@
 
 #include "k5-platform.h"
 
+#if USE_DLOPEN
+#ifdef RTLD_GROUP
+#define GROUP RTLD_GROUP
+#else
+#define GROUP 0
+#endif
+#ifdef RTLD_NODELETE
+#define NODELETE RTLD_NODELETE
+#else
+#define NODELETE 0
+#endif
+#define PLUGIN_DLOPEN_FLAGS (RTLD_NOW | RTLD_LOCAL | GROUP | NODELETE)
+#endif
+
 #if USE_DLOPEN && USE_CFBUNDLE
 #include <CoreFoundation/CoreFoundation.h>
 
@@ -257,11 +271,6 @@ krb5int_open_plugin (const char *filepath, struct plugin_file_handle **h, struct
         }
 #endif /* USE_CFBUNDLE */
 
-#ifdef RTLD_GROUP
-#define PLUGIN_DLOPEN_FLAGS (RTLD_NOW | RTLD_LOCAL | RTLD_GROUP)
-#else
-#define PLUGIN_DLOPEN_FLAGS (RTLD_NOW | RTLD_LOCAL)
-#endif
         if (!err) {
             handle = dlopen(filepath, PLUGIN_DLOPEN_FLAGS);
             if (handle == NULL) {