3 files changed, 28 insertions, 1 deletions
diff --git a/misc.c b/misc.c
index 901e8cb..744cfc9 100644
--- a/misc.c
+++ b/misc.c
@@ -1159,6 +1159,22 @@ delete_file (const char *filename)
 #endif
 }
 
+bool
+absolute_pathname (const char *pathname)
+{
+  if (pathname)
+    {
+      const int c = pathname[0];
+#ifdef WIN32
+      return c == '\\' || (isalpha(c) && pathname[1] == ':' && pathname[2] == '\\');
+#else
+      return c == '/';
+#endif
+    }
+  else
+    return false;
+}
+
 /*
  * Return the next largest power of 2
  * or u if u is a power of 2.
diff --git a/misc.h b/misc.h
index ffc7e24..5343c02 100644
--- a/misc.h
+++ b/misc.h
@@ -217,6 +217,9 @@ const char *gen_path (const char *directory, const char *filename, struct gc_are
 /* delete a file, return true if succeeded */
 bool delete_file (const char *filename);
 
+/* return true if pathname is absolute */
+bool absolute_pathname (const char *pathname);
+
 /* return the next largest power of 2 */
 unsigned int adjust_power_of_2 (unsigned int u);
 
diff --git a/plugin.c b/plugin.c
index 3b0c435..432ed23 100644
--- a/plugin.c
+++ b/plugin.c
@@ -185,6 +185,8 @@ static void
 plugin_init_item (struct plugin *p, const struct plugin_option *o)
 {
   struct gc_arena gc = gc_new ();
+  bool rel = false;
+
   p->so_pathname = o->so_pathname;
   p->plugin_type_mask = plugin_supported_types ();
 
@@ -192,7 +194,7 @@ plugin_init_item (struct plugin *p, const struct plugin_option *o)
 
   p->handle = NULL;
 #if defined(PLUGIN_LIBDIR)
-  if (!strrchr(p->so_pathname, '/'))
+  if (!absolute_pathname (p->so_pathname))
     {
       char full[PATH_MAX];
 
@@ -201,6 +203,7 @@ plugin_init_item (struct plugin *p, const struct plugin_option *o)
 #if defined(ENABLE_PLUGIN_SEARCH)
       if (!p->handle)
 	{
+	  rel = true;
 	  p->handle = dlopen (p->so_pathname, RTLD_NOW);
 	}
 #endif
@@ -208,6 +211,7 @@ plugin_init_item (struct plugin *p, const struct plugin_option *o)
   else
 #endif
     {
+      rel = !absolute_pathname (p->so_pathname);
       p->handle = dlopen (p->so_pathname, RTLD_NOW);
     }
   if (!p->handle)
@@ -217,6 +221,7 @@ plugin_init_item (struct plugin *p, const struct plugin_option *o)
 
 #elif defined(USE_LOAD_LIBRARY)
 
+  rel = !absolute_pathname (p->so_pathname);
   p->module = LoadLibrary (p->so_pathname);
   if (!p->module)
     msg (M_ERR, "PLUGIN_INIT: could not load plugin DLL: %s", p->so_pathname);
@@ -260,6 +265,9 @@ plugin_init_item (struct plugin *p, const struct plugin_option *o)
   else
     p->requested_initialization_point = OPENVPN_PLUGIN_INIT_PRE_DAEMON;
 
+  if (rel)
+    msg (M_WARN, "WARNING: plugin '%s' specified by a relative pathname -- using an absolute pathname would be more secure", p->so_pathname);
+
   p->initialized = true;
 
   gc_free (&gc);