src/udev/udev-builtin-uaccess.c

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2 /*
   3  * manage device node user ACL
   4  *
   5  * Copyright 2010-2012 Kay Sievers <kay@vrfy.org>
   6  * Copyright 2010 Lennart Poettering
   7  *
   8  * This program is free software: you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation, either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include <errno.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25
  26 #include "sd-login.h"
  27
  28 #include "login-util.h"
  29 #include "logind-acl.h"
  30 #include "udev.h"
  31 #include "util.h"
  32
  33 static int builtin_uaccess(struct udev_device *dev, int argc, char *argv[], bool test) {
  34         int r;
  35         const char *path = NULL, *seat;
  36         bool changed_acl = false;
  37         uid_t uid;
  38
  39         umask(0022);
  40
  41         /* don't muck around with ACLs when the system is not running systemd */
  42         if (!logind_running())
  43                 return 0;
  44
  45         path = udev_device_get_devnode(dev);
  46         seat = udev_device_get_property_value(dev, "ID_SEAT");
  47         if (!seat)
  48                 seat = "seat0";
  49
  50         r = sd_seat_get_active(seat, NULL, &uid);
  51         if (IN_SET(r, -ENXIO, -ENODATA)) {
  52                 /* No active session on this seat */
  53                 r = 0;
  54                 goto finish;
  55         } else if (r < 0) {
  56                 log_error("Failed to determine active user on seat %s.", seat);
  57                 goto finish;
  58         }
  59
  60         r = devnode_acl(path, true, false, 0, true, uid);
  61         if (r < 0) {
  62                 log_full_errno(r == -ENOENT ? LOG_DEBUG : LOG_ERR, r, "Failed to apply ACL on %s: %m", path);
  63                 goto finish;
  64         }
  65
  66         changed_acl = true;
  67         r = 0;
  68
  69 finish:
  70         if (path && !changed_acl) {
  71                 int k;
  72
  73                 /* Better be safe than sorry and reset ACL */
  74                 k = devnode_acl(path, true, false, 0, false, 0);
  75                 if (k < 0) {
  76                         log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, k, "Failed to apply ACL on %s: %m", path);
  77                         if (r >= 0)
  78                                 r = k;
  79                 }
  80         }
  81
  82         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
  83 }
  84
  85 const struct udev_builtin udev_builtin_uaccess = {
  86         .name = "uaccess",
  87         .cmd = builtin_uaccess,
  88         .help = "Manage device node user ACL",
  89 };