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 <stdarg.h>
  24 #include <unistd.h>
  25 #include <string.h>
  26 #include <ctype.h>
  27 #include <fcntl.h>
  28 #include <errno.h>
  29 #include <dirent.h>
  30 #include <getopt.h>
  31
  32 #include "systemd/sd-login.h"
  33 #include "logind-acl.h"
  34 #include "udev.h"
  35 #include "util.h"
  36
  37 static int builtin_uaccess(struct udev_device *dev, int argc, char *argv[], bool test) {
  38         int r;
  39         const char *path = NULL, *seat;
  40         bool changed_acl = false;
  41         uid_t uid;
  42
  43         umask(0022);
  44
  45         /* don't muck around with ACLs when the system is not running systemd */
  46         if (!logind_running())
  47                 return 0;
  48
  49         path = udev_device_get_devnode(dev);
  50         seat = udev_device_get_property_value(dev, "ID_SEAT");
  51         if (!seat)
  52                 seat = "seat0";
  53
  54         r = sd_seat_get_active(seat, NULL, &uid);
  55         if (r == -ENOENT) {
  56                 /* No active session on this seat */
  57                 r = 0;
  58                 goto finish;
  59         } else if (r < 0) {
  60                 log_error("Failed to determine active user on seat %s.", seat);
  61                 goto finish;
  62         }
  63
  64         r = devnode_acl(path, true, false, 0, true, uid);
  65         if (r < 0) {
  66                 log_error_errno(r, "Failed to apply ACL on %s: %m", path);
  67                 goto finish;
  68         }
  69
  70         changed_acl = true;
  71         r = 0;
  72
  73 finish:
  74         if (path && !changed_acl) {
  75                 int k;
  76
  77                 /* Better be safe than sorry and reset ACL */
  78                 k = devnode_acl(path, true, false, 0, false, 0);
  79                 if (k < 0) {
  80                         log_error_errno(k, "Failed to apply ACL on %s: %m", path);
  81                         if (r >= 0)
  82                                 r = k;
  83                 }
  84         }
  85
  86         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
  87 }
  88
  89 const struct udev_builtin udev_builtin_uaccess = {
  90         .name = "uaccess",
  91         .cmd = builtin_uaccess,
  92         .help = "manage device node user ACL",
  93 };