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glib/gio/gdbusauthmechanismexternal.c
Simon McVittie cb185c22bc GDBus: Don't log a message for G_DBUS_CONNECTION_FLAGS_CROSS_NAMESPACE 
This was intended to make it feasible to debug connection failures where
a modern GDBus client connects to a GDBusServer that is missing
glib!2826, but those GDBusServers should be increasingly rare: we have
had the fixed version of GDBusServer for 5 GNOME stable releases
(2 years), long enough to get into stable releases of Debian and Ubuntu
and a service-pack release of SUSE.

This debug message can be very noisy, especially when unit-testing
GLib code (which is frequently done with G_MESSAGES_DEBUG=all) or when
a third-party GLogFunc ignores the log_level parameter and logs all
messages as though they indicated a serious problem. I think it has
served its purpose now.

Signed-off-by: Simon McVittie <smcv@collabora.com>
2024-09-18 14:04:09 +01:00

461 lines
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/* GDBus - GLib D-Bus Library
*
* Copyright (C) 2008-2010 Red Hat, Inc.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
* Author: David Zeuthen <davidz@redhat.com>
*/
#include "config.h"
#include <string.h>
#include "gdbusauthmechanismexternal.h"
#include "gcredentials.h"
#include "gdbuserror.h"
#include "gioenumtypes.h"
#include "glibintl.h"
#ifdef G_OS_WIN32
#include "gwin32sid.h"
#endif
struct _GDBusAuthMechanismExternalPrivate
{
gboolean is_client;
gboolean is_server;
GDBusAuthMechanismState state;
gboolean empty_data_sent;
};
static gint mechanism_get_priority (void);
static const gchar *mechanism_get_name (void);
static gboolean mechanism_is_supported (GDBusAuthMechanism *mechanism);
static gchar *mechanism_encode_data (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len,
gsize *out_data_len);
static gchar *mechanism_decode_data (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len,
gsize *out_data_len);
static GDBusAuthMechanismState mechanism_server_get_state (GDBusAuthMechanism *mechanism);
static void mechanism_server_initiate (GDBusAuthMechanism *mechanism,
const gchar *initial_response,
gsize initial_response_len);
static void mechanism_server_data_receive (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len);
static gchar *mechanism_server_data_send (GDBusAuthMechanism *mechanism,
gsize *out_data_len);
static gchar *mechanism_server_get_reject_reason (GDBusAuthMechanism *mechanism);
static void mechanism_server_shutdown (GDBusAuthMechanism *mechanism);
static GDBusAuthMechanismState mechanism_client_get_state (GDBusAuthMechanism *mechanism);
static gchar *mechanism_client_initiate (GDBusAuthMechanism *mechanism,
GDBusConnectionFlags conn_flags,
gsize *out_initial_response_len);
static void mechanism_client_data_receive (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len);
static gchar *mechanism_client_data_send (GDBusAuthMechanism *mechanism,
gsize *out_data_len);
static void mechanism_client_shutdown (GDBusAuthMechanism *mechanism);
/* ---------------------------------------------------------------------------------------------------- */
G_DEFINE_TYPE_WITH_PRIVATE (GDBusAuthMechanismExternal, _g_dbus_auth_mechanism_external, G_TYPE_DBUS_AUTH_MECHANISM)
/* ---------------------------------------------------------------------------------------------------- */
static void
_g_dbus_auth_mechanism_external_finalize (GObject *object)
{
//GDBusAuthMechanismExternal *mechanism = G_DBUS_AUTH_MECHANISM_EXTERNAL (object);
if (G_OBJECT_CLASS (_g_dbus_auth_mechanism_external_parent_class)->finalize != NULL)
G_OBJECT_CLASS (_g_dbus_auth_mechanism_external_parent_class)->finalize (object);
}
static void
_g_dbus_auth_mechanism_external_class_init (GDBusAuthMechanismExternalClass *klass)
{
GObjectClass *gobject_class;
GDBusAuthMechanismClass *mechanism_class;
gobject_class = G_OBJECT_CLASS (klass);
gobject_class->finalize = _g_dbus_auth_mechanism_external_finalize;
mechanism_class = G_DBUS_AUTH_MECHANISM_CLASS (klass);
mechanism_class->get_name = mechanism_get_name;
mechanism_class->get_priority = mechanism_get_priority;
mechanism_class->is_supported = mechanism_is_supported;
mechanism_class->encode_data = mechanism_encode_data;
mechanism_class->decode_data = mechanism_decode_data;
mechanism_class->server_get_state = mechanism_server_get_state;
mechanism_class->server_initiate = mechanism_server_initiate;
mechanism_class->server_data_receive = mechanism_server_data_receive;
mechanism_class->server_data_send = mechanism_server_data_send;
mechanism_class->server_get_reject_reason = mechanism_server_get_reject_reason;
mechanism_class->server_shutdown = mechanism_server_shutdown;
mechanism_class->client_get_state = mechanism_client_get_state;
mechanism_class->client_initiate = mechanism_client_initiate;
mechanism_class->client_data_receive = mechanism_client_data_receive;
mechanism_class->client_data_send = mechanism_client_data_send;
mechanism_class->client_shutdown = mechanism_client_shutdown;
}
static void
_g_dbus_auth_mechanism_external_init (GDBusAuthMechanismExternal *mechanism)
{
mechanism->priv = _g_dbus_auth_mechanism_external_get_instance_private (mechanism);
}
/* ---------------------------------------------------------------------------------------------------- */
static gboolean
mechanism_is_supported (GDBusAuthMechanism *mechanism)
{
g_return_val_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism), FALSE);
#if defined(G_OS_WIN32)
/* all that is required is current process SID */
return TRUE;
#else
/* This mechanism is only available if credentials has been exchanged */
if (_g_dbus_auth_mechanism_get_credentials (mechanism) != NULL)
return TRUE;
else
return FALSE;
#endif
}
static gint
mechanism_get_priority (void)
{
/* We prefer EXTERNAL to most other mechanism (DBUS_COOKIE_SHA1 and ANONYMOUS) */
return 100;
}
static const gchar *
mechanism_get_name (void)
{
return "EXTERNAL";
}
static gchar *
mechanism_encode_data (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len,
gsize *out_data_len)
{
return NULL;
}
static gchar *
mechanism_decode_data (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len,
gsize *out_data_len)
{
return NULL;
}
/* ---------------------------------------------------------------------------------------------------- */
static GDBusAuthMechanismState
mechanism_server_get_state (GDBusAuthMechanism *mechanism)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_val_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism), G_DBUS_AUTH_MECHANISM_STATE_INVALID);
g_return_val_if_fail (m->priv->is_server && !m->priv->is_client, G_DBUS_AUTH_MECHANISM_STATE_INVALID);
return m->priv->state;
}
static gboolean
data_matches_credentials (const gchar *data,
gsize data_len,
GCredentials *credentials)
{
gboolean match;
match = FALSE;
if (credentials == NULL)
goto out;
#if defined(G_OS_UNIX)
{
gint64 alleged_uid;
gchar *endp;
/* If we were unable to find out the uid, then nothing
* can possibly match it. */
if (g_credentials_get_unix_user (credentials, NULL) == (uid_t) -1)
goto out;
/* An empty authorization identity means we want to be
* whatever identity the out-of-band credentials say we have
* (RFC 4422 appendix A.1). This effectively matches any uid. */
if (data == NULL || data_len == 0)
{
match = TRUE;
goto out;
}
/* on UNIX, this is the uid as a string in base 10 */
alleged_uid = g_ascii_strtoll (data, &endp, 10);
if (*endp == '\0')
{
if (g_credentials_get_unix_user (credentials, NULL) == alleged_uid)
{
match = TRUE;
}
}
}
#else
/* TODO: Dont know how to compare credentials on this OS. Please implement. */
#endif
out:
return match;
}
static void
mechanism_server_initiate (GDBusAuthMechanism *mechanism,
const gchar *initial_response,
gsize initial_response_len)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism));
g_return_if_fail (!m->priv->is_server && !m->priv->is_client);
m->priv->is_server = TRUE;
if (initial_response != NULL)
{
if (data_matches_credentials (initial_response,
initial_response_len,
_g_dbus_auth_mechanism_get_credentials (mechanism)))
{
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_ACCEPTED;
}
else
{
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_REJECTED;
}
}
else
{
/* The initial-response optimization was not used, so we need to
* send an empty challenge to prompt the client to respond. */
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_HAVE_DATA_TO_SEND;
}
}
static void
mechanism_server_data_receive (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism));
g_return_if_fail (m->priv->is_server && !m->priv->is_client);
g_return_if_fail (m->priv->state == G_DBUS_AUTH_MECHANISM_STATE_WAITING_FOR_DATA);
if (data_matches_credentials (data,
data_len,
_g_dbus_auth_mechanism_get_credentials (mechanism)))
{
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_ACCEPTED;
}
else
{
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_REJECTED;
}
}
static gchar *
mechanism_server_data_send (GDBusAuthMechanism *mechanism,
gsize *out_data_len)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_val_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism), NULL);
g_return_val_if_fail (m->priv->is_server && !m->priv->is_client, NULL);
if (out_data_len)
*out_data_len = 0;
if (m->priv->empty_data_sent)
{
/* We have already sent an empty data response.
Reject the connection. */
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_REJECTED;
return NULL;
}
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_WAITING_FOR_DATA;
m->priv->empty_data_sent = TRUE;
return g_strdup ("");
}
static gchar *
mechanism_server_get_reject_reason (GDBusAuthMechanism *mechanism)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_val_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism), NULL);
g_return_val_if_fail (m->priv->is_server && !m->priv->is_client, NULL);
g_return_val_if_fail (m->priv->state == G_DBUS_AUTH_MECHANISM_STATE_REJECTED, NULL);
/* can never end up here because we are never in the REJECTED state */
g_assert_not_reached ();
return NULL;
}
static void
mechanism_server_shutdown (GDBusAuthMechanism *mechanism)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism));
g_return_if_fail (m->priv->is_server && !m->priv->is_client);
m->priv->is_server = FALSE;
}
/* ---------------------------------------------------------------------------------------------------- */
static GDBusAuthMechanismState
mechanism_client_get_state (GDBusAuthMechanism *mechanism)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_val_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism), G_DBUS_AUTH_MECHANISM_STATE_INVALID);
g_return_val_if_fail (m->priv->is_client && !m->priv->is_server, G_DBUS_AUTH_MECHANISM_STATE_INVALID);
return m->priv->state;
}
static gchar *
mechanism_client_initiate (GDBusAuthMechanism *mechanism,
GDBusConnectionFlags conn_flags,
gsize *out_initial_response_len)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
gchar *initial_response = NULL;
g_return_val_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism), NULL);
g_return_val_if_fail (!m->priv->is_server && !m->priv->is_client, NULL);
m->priv->is_client = TRUE;
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_WAITING_FOR_DATA;
*out_initial_response_len = 0;
if (conn_flags & G_DBUS_CONNECTION_FLAGS_CROSS_NAMESPACE)
{
/* If backwards-compatibility with GDBus servers < 2.73.3 is not a
* concern, we do not send an initial response, because there is
* no way to express an empty authorization identity this way.
* Instead, we'll reply to the server's first (empty) challenge
* with an empty authorization identity in our first response. */
}
else
{
/* Send the Unix uid or Windows SID as an initial response.
* This is the only thing that is interoperable with GDBus < 2.73.3
* servers (RHEL ≤ 9, Debian ≤ 11, Ubuntu ≤ 22.04, SUSE ≤ 15.5). */
#if defined(G_OS_UNIX)
GCredentials *credentials;
credentials = _g_dbus_auth_mechanism_get_credentials (mechanism);
g_assert (credentials != NULL);
initial_response = g_strdup_printf ("%" G_GINT64_FORMAT, (gint64) g_credentials_get_unix_user (credentials, NULL));
#elif defined(G_OS_WIN32)
initial_response = _g_win32_current_process_sid_string (NULL);
#else
/* GDBus < 2.73.3 servers can't have worked on this platform anyway,
* so it isn't a regression to behave as though
* G_DBUS_CONNECTION_FLAGS_CROSS_NAMESPACE had been set. */
g_debug ("Unknown platform, cannot use initial response in EXTERNAL");
#endif
}
if (initial_response)
{
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_ACCEPTED;
*out_initial_response_len = strlen (initial_response);
}
return initial_response;
}
static void
mechanism_client_data_receive (GDBusAuthMechanism *mechanism,
const gchar *data,
gsize data_len)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism));
g_return_if_fail (m->priv->is_client && !m->priv->is_server);
g_return_if_fail (m->priv->state == G_DBUS_AUTH_MECHANISM_STATE_WAITING_FOR_DATA);
/* The server sent us a challenge, which should normally
* be empty. We respond with our authorization identity. */
m->priv->state = G_DBUS_AUTH_MECHANISM_STATE_HAVE_DATA_TO_SEND;
}
static gchar *
mechanism_client_data_send (GDBusAuthMechanism *mechanism,
gsize *out_data_len)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_val_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism), NULL);
g_return_val_if_fail (m->priv->is_client && !m->priv->is_server, NULL);
g_return_val_if_fail (m->priv->state == G_DBUS_AUTH_MECHANISM_STATE_HAVE_DATA_TO_SEND, NULL);
/* We respond to the server's challenge by sending our
* authorization identity, which is the empty string, meaning
* whoever the out-of-band credentials say we are. */
*out_data_len = 0;
return g_strdup ("");
}
static void
mechanism_client_shutdown (GDBusAuthMechanism *mechanism)
{
GDBusAuthMechanismExternal *m = G_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism);
g_return_if_fail (G_IS_DBUS_AUTH_MECHANISM_EXTERNAL (mechanism));
g_return_if_fail (m->priv->is_client && !m->priv->is_server);
m->priv->is_client = FALSE;
}
/* ---------------------------------------------------------------------------------------------------- */
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