Add apparmor element support to bus config parsing

The <apparmor> element can contain a single mode attribute that has one
of three values:

 "enabled"
 "disabled"
 "required"

"enabled" means that kernel support is autodetected and, if available,
AppArmor mediation occurs in dbus-daemon. If kernel support is not
detected, mediation is disabled. "disabled" means that mediation does
not occur. "required" means that kernel support must be detected for
dbus-daemon to start.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=75113
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Reviewed-by: Simon McVittie <simon.mcvittie@collabora.co.uk>

1 files changed, 79 insertions, 0 deletions

diff --git a/bus/apparmor.c b/bus/apparmor.c
new file mode 100644
index 00000000..b53d051d
--- /dev/null
+++ b/bus/apparmor.c
@@ -0,0 +1,79 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
+ * apparmor.c  AppArmor security checks for D-Bus
+ *
+ * Based on selinux.c
+ *
+ * Copyright © 2014-2015 Canonical, Ltd.
+ *
+ * Licensed under the Academic Free License version 2.1
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ */
+
+#include <config.h>
+#include "apparmor.h"
+
+#ifdef HAVE_APPARMOR
+
+#include <dbus/dbus-internals.h>
+#include <string.h>
+
+typedef enum {
+  APPARMOR_DISABLED,
+  APPARMOR_ENABLED,
+  APPARMOR_REQUIRED
+} AppArmorConfigMode;
+
+/* Store the value of the AppArmor mediation mode in the bus configuration */
+static AppArmorConfigMode apparmor_config_mode = APPARMOR_ENABLED;
+
+#endif /* HAVE_APPARMOR */
+
+dbus_bool_t
+bus_apparmor_set_mode_from_config (const char *mode, DBusError *error)
+{
+#ifdef HAVE_APPARMOR
+  if (mode != NULL)
+  {
+    if (strcmp (mode, "disabled") == 0)
+      apparmor_config_mode = APPARMOR_DISABLED;
+    else if (strcmp (mode, "enabled") == 0)
+      apparmor_config_mode = APPARMOR_ENABLED;
+    else if (strcmp (mode, "required") == 0)
+      apparmor_config_mode = APPARMOR_REQUIRED;
+    else
+      {
+        dbus_set_error (error, DBUS_ERROR_FAILED,
+                        "Mode attribute on <apparmor> must have value "
+                        "\"required\", \"enabled\" or \"disabled\", "
+                        "not \"%s\"", mode);
+        return FALSE;
+      }
+  }
+
+  return TRUE;
+#else
+  if (mode == NULL || strcmp (mode, "disabled") == 0 ||
+                      strcmp (mode, "enabled") == 0)
+    return TRUE;
+
+  dbus_set_error (error, DBUS_ERROR_FAILED,
+                  "Mode attribute on <apparmor> must have value \"enabled\" or "
+                  "\"disabled\" but cannot be \"%s\" when D-Bus is built "
+                  "without AppArmor support", mode);
+  return FALSE;
+#endif
+}