src/shared/polkit.c

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2011 Lennart Poettering

  systemd 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.

  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <sys/types.h>

#include <errno.h>

#include "util.h"
#include "dbus-common.h"
#include "polkit.h"

int verify_polkit(
                DBusConnection *c,
                DBusMessage *request,
                const char *action,
                bool interactive,
                bool *_challenge,
                DBusError *error) {


#ifdef ENABLE_POLKIT
        DBusMessage *m = NULL, *reply = NULL;
        const char *system_bus_name = "system-bus-name", *name = "name", *cancel_id = "";
        uint32_t flags = interactive ? 1 : 0;
        DBusMessageIter iter_msg, iter_struct, iter_array, iter_dict, iter_variant;
        int r;
        dbus_bool_t authorized = FALSE, challenge = FALSE;
#endif
        const char *sender;
        unsigned long ul;

        assert(c);
        assert(request);

        sender = dbus_message_get_sender(request);
        if (!sender)
                return -EINVAL;

        ul = dbus_bus_get_unix_user(c, sender, error);
        if (ul == (unsigned long) -1)
                return -EINVAL;

        /* Shortcut things for root, to avoid the PK roundtrip and dependency */
        if (ul == 0)
                return 1;

#ifdef ENABLE_POLKIT

        m = dbus_message_new_method_call(
                        "org.freedesktop.PolicyKit1",
                        "/org/freedesktop/PolicyKit1/Authority",
                        "org.freedesktop.PolicyKit1.Authority",
                        "CheckAuthorization");
        if (!m)
                return -ENOMEM;

        dbus_message_iter_init_append(m, &iter_msg);

        if (!dbus_message_iter_open_container(&iter_msg, DBUS_TYPE_STRUCT, NULL, &iter_struct) ||
            !dbus_message_iter_append_basic(&iter_struct, DBUS_TYPE_STRING, &system_bus_name) ||
            !dbus_message_iter_open_container(&iter_struct, DBUS_TYPE_ARRAY, "{sv}", &iter_array) ||
            !dbus_message_iter_open_container(&iter_array, DBUS_TYPE_DICT_ENTRY, NULL, &iter_dict) ||
            !dbus_message_iter_append_basic(&iter_dict, DBUS_TYPE_STRING, &name) ||
            !dbus_message_iter_open_container(&iter_dict, DBUS_TYPE_VARIANT, "s", &iter_variant) ||
            !dbus_message_iter_append_basic(&iter_variant, DBUS_TYPE_STRING, &sender) ||
            !dbus_message_iter_close_container(&iter_dict, &iter_variant) ||
            !dbus_message_iter_close_container(&iter_array, &iter_dict) ||
            !dbus_message_iter_close_container(&iter_struct, &iter_array) ||
            !dbus_message_iter_close_container(&iter_msg, &iter_struct) ||
            !dbus_message_iter_append_basic(&iter_msg, DBUS_TYPE_STRING, &action) ||
            !dbus_message_iter_open_container(&iter_msg, DBUS_TYPE_ARRAY, "{ss}", &iter_array) ||
            !dbus_message_iter_close_container(&iter_msg, &iter_array) ||
            !dbus_message_iter_append_basic(&iter_msg, DBUS_TYPE_UINT32, &flags) ||
            !dbus_message_iter_append_basic(&iter_msg, DBUS_TYPE_STRING, &cancel_id)) {
                r = -ENOMEM;
                goto finish;
        }

        reply = dbus_connection_send_with_reply_and_block(c, m, -1, error);
        if (!reply) {

                /* Treat no PK available as access denied */
                if (dbus_error_has_name(error, DBUS_ERROR_SERVICE_UNKNOWN)) {
                        r = -EACCES;
                        dbus_error_free(error);
                        goto finish;
                }

                r = -EIO;
                goto finish;
        }

        if (!dbus_message_iter_init(reply, &iter_msg) ||
            dbus_message_iter_get_arg_type(&iter_msg) != DBUS_TYPE_STRUCT) {
                r = -EIO;
                goto finish;
        }

        dbus_message_iter_recurse(&iter_msg, &iter_struct);

        if (dbus_message_iter_get_arg_type(&iter_struct) != DBUS_TYPE_BOOLEAN) {
                r = -EIO;
                goto finish;
        }

        dbus_message_iter_get_basic(&iter_struct, &authorized);

        if (!dbus_message_iter_next(&iter_struct) ||
            dbus_message_iter_get_arg_type(&iter_struct) != DBUS_TYPE_BOOLEAN) {
                r = -EIO;
                goto finish;
        }

        dbus_message_iter_get_basic(&iter_struct, &challenge);

        if (authorized)
                r = 1;
        else if (_challenge) {
                *_challenge = !!challenge;
                r = 0;
        } else
                r = -EPERM;

finish:
        if (m)
                dbus_message_unref(m);

        if (reply)
                dbus_message_unref(reply);

        return r;
#else
        return -EPERM;
#endif
}