Bug #12998841: libmysql divulges plaintext password upon request in 5.5

1. Clear text password client plugin disabled by default.
2. Added an environment variable LIBMYSQL_ENABLE_CLEARTEXT_PLUGIN, that
when set to something starting with '1', 'Y' or 'y' will enable the clear
text
plugin for all connections.
3. Added a new mysql_options() option : MYSQL_ENABLE_CLEARTEXT_PLUGIN
that takes an my_bool argument. When the value of the argument is non-zero
the clear text plugin is enabled for this connection only.
4. Added an enable-cleartext-plugin config file option that takes a numeric

argument. If the numeric value of the numeric argument is non-zero the
clear
text plugin is enabled for the connection
5. Added a boolean command line option "--enable_cleartext_plugin" to
mysql, mysqlslap and mysqladmin. When specified it will call mysql_options
with the effect of #3
6. Added a new CLEARTEXT option to the connect command in mysqltest.
When specified it will enable the cleartext plugin for usage.
7. Added test cases and updated existing ones that need the clear text
plugin.

2 files changed, 65 insertions, 9 deletions

diff --git a/sql-common/client.c b/sql-common/client.c
index 08f4bfb1151..381768834cd 100644
--- a/sql-common/client.c
+++ b/sql-common/client.c
@@ -1136,7 +1136,8 @@ static const char *default_options[]=
   "connect-timeout", "local-infile", "disable-local-infile",
   "ssl-cipher", "max-allowed-packet", "protocol", "shared-memory-base-name",
   "multi-results", "multi-statements", "multi-queries", "secure-auth",
-  "report-data-truncation", "plugin-dir", "default-auth",
+  "report-data-truncation", "plugin-dir", "default-auth", 
+  "enable-cleartext-plugin",
   NullS
 };
 enum option_id {
@@ -1148,6 +1149,7 @@ enum option_id {
   OPT_ssl_cipher, OPT_max_allowed_packet, OPT_protocol, OPT_shared_memory_base_name, 
   OPT_multi_results, OPT_multi_statements, OPT_multi_queries, OPT_secure_auth, 
   OPT_report_data_truncation, OPT_plugin_dir, OPT_default_auth, 
+  OPT_enable_cleartext_plugin,
   OPT_keep_this_one_last
 };
 
@@ -1180,14 +1182,27 @@ static int add_init_command(struct st_mysql_options *options, const char *cmd)
   return 0;
 }
 
-#define EXTENSION_SET_STRING(OPTS, X, STR)                       \
-    if ((OPTS)->extension)                                       \
-      my_free((OPTS)->extension->X);     \
-    else                                                         \
+#define ALLOCATE_EXTENSIONS(OPTS)                                \
       (OPTS)->extension= (struct st_mysql_options_extention *)   \
         my_malloc(sizeof(struct st_mysql_options_extention),     \
-                  MYF(MY_WME | MY_ZEROFILL));                    \
-    (OPTS)->extension->X= my_strdup((STR), MYF(MY_WME));
+                  MYF(MY_WME | MY_ZEROFILL))                     \
+
+#define ENSURE_EXTENSIONS_PRESENT(OPTS)                          \
+    do {                                                         \
+      if (!(OPTS)->extension)                                    \
+        ALLOCATE_EXTENSIONS(OPTS);                               \
+    } while (0)
+
+
+#define EXTENSION_SET_STRING(OPTS, X, STR)                       \
+    do {                                                         \
+      if ((OPTS)->extension)                                     \
+        my_free((OPTS)->extension->X);                           \
+      else                                                       \
+        ALLOCATE_EXTENSIONS(OPTS);                               \
+      (OPTS)->extension->X= ((STR) != NULL) ?                    \
+        my_strdup((STR), MYF(MY_WME)) : NULL;                    \
+    } while (0)
 
 void mysql_read_default_options(struct st_mysql_options *options,
 				const char *filename,const char *group)
@@ -1386,6 +1401,12 @@ void mysql_read_default_options(struct st_mysql_options *options,
         case OPT_default_auth:
           EXTENSION_SET_STRING(options, default_auth, opt_arg);
           break;
+
+        case OPT_enable_cleartext_plugin:
+          ENSURE_EXTENSIONS_PRESENT(options);
+          options->extension->enable_cleartext_plugin= 
+            (!opt_arg || atoi(opt_arg) != 0) ? TRUE : FALSE;
+
 	default:
 	  DBUG_PRINT("warning",("unknown option: %s",option[0]));
 	}
@@ -2782,6 +2803,27 @@ static void client_mpvio_info(MYSQL_PLUGIN_VIO *vio,
   mpvio_info(mpvio->mysql->net.vio, info);
 }
 
+
+my_bool libmysql_cleartext_plugin_enabled= 0;
+
+static my_bool check_plugin_enabled(MYSQL *mysql, auth_plugin_t *plugin)
+{
+  if (plugin == &clear_password_client_plugin &&
+      (!libmysql_cleartext_plugin_enabled &&
+       (!mysql->options.extension ||
+       !mysql->options.extension->enable_cleartext_plugin)))
+  {
+    set_mysql_extended_error(mysql, CR_AUTH_PLUGIN_CANNOT_LOAD,
+                             unknown_sqlstate,
+                             ER(CR_AUTH_PLUGIN_CANNOT_LOAD),
+                             clear_password_client_plugin.name,
+                             "plugin not enabled");
+    return TRUE;
+  }
+  return FALSE;
+}
+
+
 /**
   Client side of the plugin driver authentication.
 
@@ -2824,6 +2866,9 @@ int run_plugin_auth(MYSQL *mysql, char *data, uint data_len,
     auth_plugin_name= auth_plugin->name;
   }
 
+  if (check_plugin_enabled(mysql, auth_plugin))
+    DBUG_RETURN(1);
+
   DBUG_PRINT ("info", ("using plugin %s", auth_plugin_name));
 
   mysql->net.last_errno= 0; /* just in case */
@@ -2915,6 +2960,9 @@ int run_plugin_auth(MYSQL *mysql, char *data, uint data_len,
                          auth_plugin_name, MYSQL_CLIENT_AUTHENTICATION_PLUGIN)))
       DBUG_RETURN (1);
 
+    if (check_plugin_enabled(mysql, auth_plugin))
+      DBUG_RETURN(1);
+
     mpvio.plugin= auth_plugin;
     res= auth_plugin->authenticate_user((struct st_plugin_vio *)&mpvio, mysql);
 
@@ -4117,6 +4165,11 @@ mysql_options(MYSQL *mysql,enum mysql_option option, const void *arg)
   case MYSQL_DEFAULT_AUTH:
     EXTENSION_SET_STRING(&mysql->options, default_auth, arg);
     break;
+  case MYSQL_ENABLE_CLEARTEXT_PLUGIN:
+    ENSURE_EXTENSIONS_PRESENT(&mysql->options);
+    mysql->options.extension->enable_cleartext_plugin= 
+      (*(my_bool*) arg) ? TRUE : FALSE;
+    break;
   default:
     DBUG_RETURN(1);
   }
@@ -4336,5 +4389,3 @@ static int clear_password_auth_client(MYSQL_PLUGIN_VIO *vio, MYSQL *mysql)
 
   return res ? CR_ERROR : CR_OK;
 }
-
-
diff --git a/sql-common/client_plugin.c b/sql-common/client_plugin.c
index 4016f0744be..75faeb7ee97 100644
--- a/sql-common/client_plugin.c
+++ b/sql-common/client_plugin.c
@@ -197,6 +197,10 @@ err1:
 static void load_env_plugins(MYSQL *mysql)
 {
   char *plugs, *free_env, *s= getenv("LIBMYSQL_PLUGINS");
+  char *enable_cleartext_plugin= getenv("LIBMYSQL_ENABLE_CLEARTEXT_PLUGIN");
+
+  if (enable_cleartext_plugin && strchr("1Yy", enable_cleartext_plugin[0]))
+    libmysql_cleartext_plugin_enabled= 1;
 
   /* no plugins to load */
   if(!s)
@@ -212,6 +216,7 @@ static void load_env_plugins(MYSQL *mysql)
   } while (s);
 
   my_free(free_env);
+
 }
 
 /********** extern functions to be used by libmysql *********************/