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6475a51664
Inside the OS, some utilities and functions are going to need to "break out" and be run from the real root. This is a convenience utility to do so.
118 lines
2.4 KiB
C
118 lines
2.4 KiB
C
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
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*
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* chroot_break: Exit out of active chroot(2) if any. Requires root privileges.
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*
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* Copyright (C) 2011 Colin Walters <walters@verbum.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#define _GNU_SOURCE
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <fcntl.h>
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#include <dirent.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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int
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usage (const char *self,
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int ecode)
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{
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fprintf (stderr, "usage: %s PROGRAM [ARGS...]\n", self);
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return ecode;
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}
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int
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main (int argc,
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char **argv)
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{
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const char *template = "/tmp/chroot.XXXXXX";
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char *tmpdir;
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DIR *tmp;
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struct stat current;
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struct stat up;
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if (argc < 2)
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return usage (argv[0], 1);
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tmpdir = strdup (template);
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if (!mkdtemp (tmpdir))
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{
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perror ("mkdtemp");
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return 1;
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}
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tmp = opendir ("/tmp");
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if (!tmp)
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{
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perror ("opening /tmp");
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return 1;
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}
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if (chroot (tmpdir) < 0)
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{
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perror ("chroot into tempdir");
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return 1;
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}
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do
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{
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if (stat (".", ¤t) < 0)
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{
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perror ("stat");
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return 1;
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}
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if (stat ("..", &up) < 0)
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{
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perror ("stat");
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return 1;
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}
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if (current.st_dev == up.st_dev
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&& current.st_ino == up.st_ino)
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break;
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if (chdir ("..") < 0)
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{
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perror ("chdir");
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return 1;
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}
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} while (1);
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if (chroot (".") < 0)
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{
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perror ("chroot into real root");
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return 1;
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}
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if (unlinkat (dirfd (tmp), strrchr (tmpdir, '/') + 1, AT_REMOVEDIR) < 0)
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{
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perror ("cleaning up tmpdir");
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return 1;
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}
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closedir (tmp);
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if (execv (argv[1], &argv[1]) < 0)
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{
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perror ("Running child process");
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return 1;
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}
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/* Should not be reached */
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return 1;
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}
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