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polkit.c

/***
  This file is part of PulseAudio.

  Copyright 2004-2006 Lennart Poettering
  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB

  PulseAudio 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.

  PulseAudio 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 Lesser General Public License
  along with PulseAudio; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  USA.
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <unistd.h>
#include <stdlib.h>
#include <inttypes.h>

#include <dbus/dbus.h>
#include <polkit-dbus/polkit-dbus.h>

#include <pulse/i18n.h>

#include <pulsecore/log.h>
#include <pulsecore/macro.h>

#include "polkit.h"

int pa_polkit_check(const char *action_id) {
    int ret = -1;
    DBusError dbus_error;
    DBusConnection *bus = NULL;
    PolKitCaller *caller = NULL;
    PolKitAction *action = NULL;
    PolKitContext *context = NULL;
    PolKitError *polkit_error = NULL;
    PolKitSession *session = NULL;
    PolKitResult polkit_result;

    dbus_error_init(&dbus_error);

    if (!(bus = dbus_bus_get(DBUS_BUS_SYSTEM, &dbus_error))) {
        pa_log_error(_("Cannot connect to system bus: %s"), dbus_error.message);
        goto finish;
    }

    /* There seems to be a bug in some versions of D-Bus that causes
     * dbus_shutdown() to call exit() when a connection without this
     * flag disabled was created during runtime.*/
    dbus_connection_set_exit_on_disconnect(bus, FALSE);

    if (!(caller = polkit_caller_new_from_pid(bus, getpid(), &dbus_error))) {
        pa_log_error(_("Cannot get caller from PID: %s"), dbus_error.message);
        goto finish;
    }

    /* This function is called when PulseAudio is called SUID root. We
     * want to authenticate the real user that called us and not the
     * effective user we gained through being SUID root. Hence we
     * overwrite the UID caller data here explicitly, just for
     * paranoia. In fact PolicyKit should fill in the UID here anyway
     * -- an not the EUID or any other user id. */

    if (!(polkit_caller_set_uid(caller, getuid()))) {
        pa_log_error(_("Cannot set UID on caller object."));
        goto finish;
    }

    if (!(polkit_caller_get_ck_session(caller, &session))) {
        pa_log_error(_("Failed to get CK session."));
        goto finish;
    }

    /* We need to overwrite the UID in both the caller and the session
     * object */

    if (!(polkit_session_set_uid(session, getuid()))) {
        pa_log_error(_("Cannot set UID on session object."));
        goto finish;
    }

    if (!(action = polkit_action_new())) {
        pa_log_error(_("Cannot allocate PolKitAction."));
        goto finish;
    }

    if (!polkit_action_set_action_id(action, action_id)) {
        pa_log_error(_("Cannot set action_id"));
        goto finish;
    }

    if (!(context = polkit_context_new())) {
        pa_log_error(_("Cannot allocate PolKitContext."));
        goto finish;
    }

    if (!polkit_context_init(context, &polkit_error)) {
        pa_log_error(_("Cannot initialize PolKitContext: %s"), polkit_error_get_error_message(polkit_error));
        goto finish;
    }

    for (;;) {

        polkit_result = polkit_context_is_caller_authorized(context, action, caller, TRUE, &polkit_error);

        if (polkit_error_is_set(polkit_error)) {
            pa_log_error(_("Could not determine whether caller is authorized: %s"), polkit_error_get_error_message(polkit_error));
            goto finish;
        }

        if (polkit_result == POLKIT_RESULT_ONLY_VIA_ADMIN_AUTH ||
            polkit_result == POLKIT_RESULT_ONLY_VIA_ADMIN_AUTH_KEEP_SESSION ||
            polkit_result == POLKIT_RESULT_ONLY_VIA_ADMIN_AUTH_KEEP_ALWAYS ||
            polkit_result == POLKIT_RESULT_ONLY_VIA_ADMIN_AUTH_ONE_SHOT ||
            polkit_result == POLKIT_RESULT_ONLY_VIA_SELF_AUTH ||
            polkit_result == POLKIT_RESULT_ONLY_VIA_SELF_AUTH_KEEP_SESSION ||
            polkit_result == POLKIT_RESULT_ONLY_VIA_SELF_AUTH_KEEP_ALWAYS ||
            polkit_result == POLKIT_RESULT_ONLY_VIA_SELF_AUTH_ONE_SHOT
        ) {

            if (polkit_auth_obtain(action_id, 0, getpid(), &dbus_error)) {
                polkit_result = POLKIT_RESULT_YES;
                break;
            }

            if (dbus_error_is_set(&dbus_error)) {
                pa_log_error(_("Cannot obtain auth: %s"), dbus_error.message);
                goto finish;
            }
        }

        break;
    }

    if (polkit_result != POLKIT_RESULT_YES && polkit_result != POLKIT_RESULT_NO)
        pa_log_warn(_("PolicyKit responded with '%s'"), polkit_result_to_string_representation(polkit_result));

    ret = polkit_result == POLKIT_RESULT_YES;

finish:

    if (caller)
        polkit_caller_unref(caller);

    if (action)
        polkit_action_unref(action);

    if (context)
        polkit_context_unref(context);

    if (bus)
        dbus_connection_unref(bus);

    dbus_error_free(&dbus_error);

    if (polkit_error)
        polkit_error_free(polkit_error);

    return ret;
}

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