src/udev/udev-builtin-uaccess.c

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