180 lines
6.5 KiB
Diff
180 lines
6.5 KiB
Diff
From 3d442dbf936d197aa11ca0a71663c2bc61696151 Mon Sep 17 00:00:00 2001
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From: fujiwarat <takao.fujiwara1@gmail.com>
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Date: Fri, 13 Sep 2019 15:59:03 +0900
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Subject: [PATCH] bus: Implement GDBusAuthObserver callback
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ibus uses a GDBusServer with G_DBUS_SERVER_FLAGS_AUTHENTICATION_ALLOW_ANONYMOUS,
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and doesn't set a GDBusAuthObserver, which allows anyone who can connect
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to its AF_UNIX socket to authenticate and be authorized to send method calls.
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It also seems to use an abstract AF_UNIX socket, which does not have
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filesystem permissions, so the practical effect might be that a local
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attacker can connect to another user's ibus service and make arbitrary
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method calls.
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BUGS=rhbz#1717958
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---
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bus/server.c | 89 ++++++++++++++++++++++++++++++++++++++++++----------
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1 file changed, 73 insertions(+), 16 deletions(-)
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diff --git a/bus/server.c b/bus/server.c
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index 3a626230..2439de14 100644
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--- a/bus/server.c
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+++ b/bus/server.c
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@@ -2,7 +2,8 @@
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/* vim:set et sts=4: */
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/* bus - The Input Bus
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* Copyright (C) 2008-2010 Peng Huang <shawn.p.huang@gmail.com>
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- * Copyright (C) 2008-2010 Red Hat, Inc.
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+ * Copyright (C) 2011-2019 Takao Fujiwara <takao.fujiwara1@gmail.com>
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+ * Copyright (C) 2008-2019 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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@@ -70,16 +71,63 @@ _restart_server (void)
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}
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/**
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+ * bus_allow_mechanism_cb:
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+ * @observer: A #GDBusAuthObserver.
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+ * @mechanism: The name of the mechanism.
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+ * @user_data: always %NULL.
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+ *
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+ * Check if @mechanism can be used to authenticate the other peer.
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+ * Returns: %TRUE if the peer's mechanism is allowed.
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+ */
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+static gboolean
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+bus_allow_mechanism_cb (GDBusAuthObserver *observer,
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+ const gchar *mechanism,
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+ G_GNUC_UNUSED gpointer user_data)
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+{
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+ if (g_strcmp0 (mechanism, "EXTERNAL") == 0)
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+ return TRUE;
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+ return FALSE;
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+}
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+
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+/**
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+ * bus_authorize_authenticated_peer_cb:
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+ * @observer: A #GDBusAuthObserver.
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+ * @stream: A #GIOStream.
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+ * @credentials: A #GCredentials.
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+ * @user_data: always %NULL.
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+ *
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+ * Check if a peer who has already authenticated should be authorized.
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+ * Returns: %TRUE if the peer's credential is authorized.
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+ */
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+static gboolean
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+bus_authorize_authenticated_peer_cb (GDBusAuthObserver *observer,
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+ GIOStream *stream,
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+ GCredentials *credentials,
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+ G_GNUC_UNUSED gpointer user_data)
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+{
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+ gboolean authorized = FALSE;
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+ if (credentials) {
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+ GCredentials *own_credentials = g_credentials_new ();
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+ if (g_credentials_is_same_user (credentials, own_credentials, NULL))
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+ authorized = TRUE;
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+ g_object_unref (own_credentials);
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+ }
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+ return authorized;
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+}
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+
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+/**
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* bus_new_connection_cb:
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- * @user_data: always NULL.
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- * @returns: TRUE when the function can handle the connection.
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+ * @observer: A #GDBusAuthObserver.
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+ * @dbus_connection: A #GDBusconnection.
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+ * @user_data: always %NULL.
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*
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* Handle incoming connections.
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+ * Returns: %TRUE when the function can handle the connection.
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*/
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static gboolean
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-bus_new_connection_cb (GDBusServer *server,
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- GDBusConnection *dbus_connection,
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- gpointer user_data)
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+bus_new_connection_cb (GDBusServer *server,
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+ GDBusConnection *dbus_connection,
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+ G_GNUC_UNUSED gpointer user_data)
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{
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BusConnection *connection = bus_connection_new (dbus_connection);
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bus_dbus_impl_new_connection (dbus, connection);
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@@ -94,9 +142,9 @@ bus_new_connection_cb (GDBusServer *
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}
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static void
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-_server_connect_start_portal_cb (GObject *source_object,
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- GAsyncResult *res,
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- gpointer user_data)
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+_server_connect_start_portal_cb (GObject *source_object,
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+ GAsyncResult *res,
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+ G_GNUC_UNUSED gpointer user_data)
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{
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GVariant *result;
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GError *error = NULL;
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@@ -113,9 +161,9 @@ _server_connect_start_portal_cb (GObject
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}
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static void
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-bus_acquired_handler (GDBusConnection *connection,
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- const gchar *name,
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- gpointer user_data)
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+bus_acquired_handler (GDBusConnection *connection,
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+ const gchar *name,
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+ G_GNUC_UNUSED gpointer user_data)
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{
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g_dbus_connection_call (connection,
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IBUS_SERVICE_PORTAL,
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@@ -136,22 +184,27 @@ void
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bus_server_init (void)
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{
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GError *error = NULL;
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+ GDBusServerFlags flags = G_DBUS_SERVER_FLAGS_NONE;
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+ gchar *guid;
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+ GDBusAuthObserver *observer;
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dbus = bus_dbus_impl_get_default ();
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ibus = bus_ibus_impl_get_default ();
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bus_dbus_impl_register_object (dbus, (IBusService *)ibus);
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/* init server */
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- GDBusServerFlags flags = G_DBUS_SERVER_FLAGS_AUTHENTICATION_ALLOW_ANONYMOUS;
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- gchar *guid = g_dbus_generate_guid ();
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- if (!g_str_has_prefix (g_address, "unix:tmpdir=")) {
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- g_error ("Your socket address does not have the format unix:tmpdir=$DIR; %s",
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- g_address);
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+ guid = g_dbus_generate_guid ();
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+ observer = g_dbus_auth_observer_new ();
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+ if (!g_str_has_prefix (g_address, "unix:tmpdir=") &&
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+ !g_str_has_prefix (g_address, "unix:path=")) {
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+ g_error ("Your socket address does not have the format unix:tmpdir=$DIR "
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+ "or unix:path=$FILE; %s", g_address);
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+
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}
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server = g_dbus_server_new_sync (
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g_address, /* the place where the socket file lives, e.g. /tmp, abstract namespace, etc. */
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flags, guid,
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- NULL /* observer */,
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+ observer,
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NULL /* cancellable */,
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&error);
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if (server == NULL) {
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@@ -161,7 +214,13 @@ bus_server_init (void)
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}
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g_free (guid);
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- g_signal_connect (server, "new-connection", G_CALLBACK (bus_new_connection_cb), NULL);
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+ g_signal_connect (observer, "allow-mechanism",
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+ G_CALLBACK (bus_allow_mechanism_cb), NULL);
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+ g_signal_connect (observer, "authorize-authenticated-peer",
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+ G_CALLBACK (bus_authorize_authenticated_peer_cb), NULL);
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+ g_object_unref (observer);
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+ g_signal_connect (server, "new-connection",
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+ G_CALLBACK (bus_new_connection_cb), NULL);
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g_dbus_server_start (server);
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--
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2.21.0
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