Bug#37428 Potential security issue with UDFs - linux shellcode execution.

plugin_dir option backported from 5.1

per-file messages:
  sql/mysql_priv.h
    Bug#37428 Potential security issue with UDFs - linux shellcode execution.
    
    opt_plugin_dir and opt_plugin_dir_ptr declared.
  sql/mysqld.cc
    Bug#37428 Potential security issue with UDFs - linux shellcode execution.
    
    'plugin_dir' option added
  sql/set_var.cc
    Bug#37428 Potential security issue with UDFs - linux shellcode execution.
    
    'plugin_dir' option added.
  sql/sql_udf.cc
    Bug#37428 Potential security issue with UDFs - linux shellcode execution.
    
    opt_plugin_dir added to the udf->dl path. Warn if it's not specified.
  sql/unireg.h
    Bug#37428 Potential security issue with UDFs - linux shellcode execution.
    
    PLUGINDIR defined.

sql/mysql_priv.h

@@ -1362,6 +1362,9 @@ extern char *default_tz_name;
 extern my_bool opt_large_pages;
 extern uint opt_large_page_size;
 
+extern char *opt_plugin_dir_ptr;
+extern char opt_plugin_dir[FN_REFLEN];
+
 extern MYSQL_LOG mysql_log,mysql_slow_log,mysql_bin_log;
 extern FILE *bootstrap_file;
 extern int bootstrap_error;

sql/mysqld.cc

@@ -324,6 +324,9 @@ arg_cmp_func Arg_comparator::comparator_matrix[5][2] =
 
 /* static variables */
 
+char opt_plugin_dir[FN_REFLEN];
+char *opt_plugin_dir_ptr;
+
 static bool lower_case_table_names_used= 0;
 static bool volatile select_thread_in_use, signal_thread_in_use;
 static bool volatile ready_to_exit;
@@ -4984,6 +4987,7 @@ enum options_mysqld
   OPT_OLD_STYLE_USER_LIMITS,
   OPT_LOG_SLOW_ADMIN_STATEMENTS,
   OPT_TABLE_LOCK_WAIT_TIMEOUT,
+  OPT_PLUGIN_DIR,
   OPT_PORT_OPEN_TIMEOUT,
   OPT_MERGE,
   OPT_PROFILING,
@@ -6223,6 +6227,10 @@ The minimum value for this variable is 4096.",
    (gptr*) &global_system_variables.optimizer_search_depth,
    (gptr*) &max_system_variables.optimizer_search_depth,
    0, GET_ULONG, OPT_ARG, MAX_TABLES+1, 0, MAX_TABLES+2, 0, 1, 0},
+  {"plugin_dir", OPT_PLUGIN_DIR,
+   "Directory for plugins.",
+   (gptr*) &opt_plugin_dir_ptr, (gptr*) &opt_plugin_dir_ptr, 0,
+   GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
    {"preload_buffer_size", OPT_PRELOAD_BUFFER_SIZE,
     "The size of the buffer that is allocated when preloading indexes",
     (gptr*) &global_system_variables.preload_buff_size,
@@ -7761,6 +7769,9 @@ static void fix_paths(void)
   (void) my_load_path(mysql_home,mysql_home,""); // Resolve current dir
   (void) my_load_path(mysql_real_data_home,mysql_real_data_home,mysql_home);
   (void) my_load_path(pidfile_name,pidfile_name,mysql_real_data_home);
+  (void) my_load_path(opt_plugin_dir, opt_plugin_dir_ptr ? opt_plugin_dir_ptr :
+                                      "", "");
+  opt_plugin_dir_ptr= opt_plugin_dir;
 
   char *sharedir=get_relative_path(SHAREDIR);
   if (test_if_hard_path(sharedir))

sql/set_var.cc

@@ -1036,6 +1036,7 @@ struct show_var_st init_vars[]= {
   {sys_optimizer_search_depth.name,(char*) &sys_optimizer_search_depth,
    SHOW_SYS},
   {"pid_file",                (char*) pidfile_name,                 SHOW_CHAR},
+  {"plugin_dir",              (char*) opt_plugin_dir,               SHOW_CHAR},
   {"port",                    (char*) &mysqld_port,                  SHOW_INT},
   {sys_preload_buff_size.name, (char*) &sys_preload_buff_size,      SHOW_SYS},
 #ifdef ENABLED_PROFILING

sql/sql_udf.cc

@@ -214,7 +214,17 @@ void udf_init()
     void *dl = find_udf_dl(tmp->dl);
     if (dl == NULL)
     {
-      if (!(dl = dlopen(tmp->dl, RTLD_NOW)))
+      char dlpath[FN_REFLEN];
+      if (*opt_plugin_dir)
+        strxnmov(dlpath, sizeof(dlpath) - 1, opt_plugin_dir, "/", tmp->dl,
+                 NullS);
+      else
+      {
+        strxnmov(dlpath, sizeof(dlpath)-1, tmp->dl, NullS);
+        push_warning(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN, ER_UNKNOWN_ERROR,
+                     "plugin_dir was not specified");
+      }
+      if (!(dl = dlopen(dlpath, RTLD_NOW)))
       {
 	/* Print warning to log */
 	sql_print_error(ER(ER_CANT_OPEN_LIBRARY), tmp->dl,errno,dlerror());
@@ -443,8 +453,18 @@ int mysql_create_function(THD *thd,udf_func *udf)
   }
   if (!(dl = find_udf_dl(udf->dl)))
   {
-    DBUG_PRINT("info", ("Calling dlopen, udf->dl: %s", udf->dl));
-    if (!(dl = dlopen(udf->dl, RTLD_NOW)))
+    char dlpath[FN_REFLEN];
+    if (*opt_plugin_dir)
+      strxnmov(dlpath, sizeof(dlpath) - 1, opt_plugin_dir, "/", udf->dl,
+               NullS);
+    else
+    {
+      strxnmov(dlpath, sizeof(dlpath)-1, udf->dl, NullS);
+      push_warning(current_thd, MYSQL_ERROR::WARN_LEVEL_WARN, ER_UNKNOWN_ERROR,
+                   "plugin_dir was not specified");
+    }
+    DBUG_PRINT("info", ("Calling dlopen, udf->dl: %s", dlpath));
+    if (!(dl = dlopen(dlpath, RTLD_NOW)))
     {
       DBUG_PRINT("error",("dlopen of %s failed, error: %d (%s)",
 			  udf->dl,errno,dlerror()));

sql/unireg.h

@@ -35,6 +35,9 @@
 #ifndef SHAREDIR
 #define SHAREDIR	"share/"
 #endif
+#ifndef PLUGINDIR
+#define PLUGINDIR	"lib/plugin"
+#endif
 
 #define ER(X) errmesg[(X) - ER_ERROR_FIRST]
 #define ER_SAFE(X) (((X) >= ER_ERROR_FIRST && (X) <= ER_ERROR_LAST) ? ER(X) : "Invalid error code")