1/* Return true if the process can perform a chroot operation.
2 Copyright (C) 2017-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <stdio.h>
21#include <support/check.h>
22#include <support/namespace.h>
23#include <support/support.h>
24#include <support/xunistd.h>
25#include <sys/stat.h>
26#include <unistd.h>
27
28static void
29callback (void *closure)
30{
31 int *result = closure;
32 struct stat64 before;
33 xstat ("/dev", &before);
34 if (chroot ("/dev") != 0)
35 {
36 *result = errno;
37 return;
38 }
39 struct stat64 after;
40 xstat ("/", &after);
41 TEST_VERIFY (before.st_dev == after.st_dev);
42 TEST_VERIFY (before.st_ino == after.st_ino);
43 *result = 0;
44}
45
46bool
47support_can_chroot (void)
48{
49 int *result = support_shared_allocate (sizeof (*result));
50 *result = 0;
51 support_isolate_in_subprocess (callback, result);
52 bool ok = *result == 0;
53 if (!ok)
54 {
55 static bool already_warned;
56 if (!already_warned)
57 {
58 already_warned = true;
59 errno = *result;
60 printf ("warning: this process does not support chroot: %m\n");
61 }
62 }
63 support_shared_free (result);
64 return ok;
65}
66