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/*
* unshare(1) - command-line interface for unshare(2)
*
* Copyright (C) 2009 Mikhail Gusarov <dottedmag@dottedmag.net>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include <errno.h>
#include <getopt.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/mount.h>
/* we only need some defines missing in sys/mount.h, no libmount linkage */
#include <libmount.h>
#include "nls.h"
#include "c.h"
#include "closestream.h"
#include "namespace.h"
#include "exec_shell.h"
#include "xalloc.h"
#include "pathnames.h"
#include "all-io.h"
static void disable_setgroups(void)
{
const char *file = _PATH_PROC_SETGROUPS;
const char *deny = "deny";
int fd;
fd = open(file, O_WRONLY);
if (fd < 0) {
if (errno == ENOENT)
return;
err(EXIT_FAILURE, _("cannot open %s"), file);
}
if (write_all(fd, deny, strlen(deny)))
err(EXIT_FAILURE, _("write failed %s"), file);
close(fd);
}
static void map_id(const char *file, uint32_t from, uint32_t to)
{
char *buf;
int fd;
fd = open(file, O_WRONLY);
if (fd < 0)
err(EXIT_FAILURE, _("cannot open %s"), file);
xasprintf(&buf, "%u %u 1", from, to);
if (write_all(fd, buf, strlen(buf)))
err(EXIT_FAILURE, _("write failed %s"), file);
free(buf);
close(fd);
}
static void usage(int status)
{
FILE *out = status == EXIT_SUCCESS ? stdout : stderr;
fputs(USAGE_HEADER, out);
fprintf(out,
_(" %s [options] <program> [args...]\n"), program_invocation_short_name);
fputs(USAGE_OPTIONS, out);
fputs(_(" -m, --mount unshare mounts namespace\n"), out);
fputs(_(" -u, --uts unshare UTS namespace (hostname etc)\n"), out);
fputs(_(" -i, --ipc unshare System V IPC namespace\n"), out);
fputs(_(" -n, --net unshare network namespace\n"), out);
fputs(_(" -p, --pid unshare pid namespace\n"), out);
fputs(_(" -U, --user unshare user namespace\n"), out);
fputs(_(" -f, --fork fork before launching <program>\n"), out);
fputs(_(" --mount-proc[=<dir>] mount proc filesystem first (implies --mount)\n"), out);
fputs(_(" -r, --map-root-user map current user to root (implies --user)\n"), out);
fputs(USAGE_SEPARATOR, out);
fputs(USAGE_HELP, out);
fputs(USAGE_VERSION, out);
fprintf(out, USAGE_MAN_TAIL("unshare(1)"));
exit(status);
}
int main(int argc, char *argv[])
{
enum {
OPT_MOUNTPROC = CHAR_MAX + 1
};
static const struct option longopts[] = {
{ "help", no_argument, 0, 'h' },
{ "version", no_argument, 0, 'V'},
{ "mount", no_argument, 0, 'm' },
{ "uts", no_argument, 0, 'u' },
{ "ipc", no_argument, 0, 'i' },
{ "net", no_argument, 0, 'n' },
{ "pid", no_argument, 0, 'p' },
{ "user", no_argument, 0, 'U' },
{ "fork", no_argument, 0, 'f' },
{ "mount-proc", optional_argument, 0, OPT_MOUNTPROC },
{ "map-root-user", no_argument, 0, 'r' },
{ NULL, 0, 0, 0 }
};
int unshare_flags = 0;
int c, forkit = 0, maproot = 0;
const char *procmnt = NULL;
uid_t real_euid = geteuid();
gid_t real_egid = getegid();;
setlocale(LC_ALL, "");
bindtextdomain(PACKAGE, LOCALEDIR);
textdomain(PACKAGE);
atexit(close_stdout);
while ((c = getopt_long(argc, argv, "+fhVmuinpUr", longopts, NULL)) != -1) {
switch (c) {
case 'f':
forkit = 1;
break;
case 'h':
usage(EXIT_SUCCESS);
case 'V':
printf(UTIL_LINUX_VERSION);
return EXIT_SUCCESS;
case 'm':
unshare_flags |= CLONE_NEWNS;
break;
case 'u':
unshare_flags |= CLONE_NEWUTS;
break;
case 'i':
unshare_flags |= CLONE_NEWIPC;
break;
case 'n':
unshare_flags |= CLONE_NEWNET;
break;
case 'p':
unshare_flags |= CLONE_NEWPID;
break;
case 'U':
unshare_flags |= CLONE_NEWUSER;
break;
case OPT_MOUNTPROC:
unshare_flags |= CLONE_NEWNS;
procmnt = optarg ? optarg : "/proc";
break;
case 'r':
unshare_flags |= CLONE_NEWUSER;
maproot = 1;
break;
default:
usage(EXIT_FAILURE);
}
}
if (-1 == unshare(unshare_flags))
err(EXIT_FAILURE, _("unshare failed"));
if (forkit) {
int status;
pid_t pid = fork();
switch(pid) {
case -1:
err(EXIT_FAILURE, _("fork failed"));
case 0: /* child */
break;
default: /* parent */
if (waitpid(pid, &status, 0) == -1)
err(EXIT_FAILURE, _("waitpid failed"));
if (WIFEXITED(status))
return WEXITSTATUS(status);
else if (WIFSIGNALED(status))
kill(getpid(), WTERMSIG(status));
err(EXIT_FAILURE, _("child exit failed"));
}
}
if (maproot) {
disable_setgroups();
map_id(_PATH_PROC_UIDMAP, 0, real_euid);
map_id(_PATH_PROC_GIDMAP, 0, real_egid);
}
if (procmnt &&
(mount("none", procmnt, NULL, MS_PRIVATE|MS_REC, NULL) != 0 ||
mount("proc", procmnt, "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) != 0))
err(EXIT_FAILURE, _("mount %s failed"), procmnt);
if (optind < argc) {
execvp(argv[optind], argv + optind);
err(EXIT_FAILURE, _("failed to execute %s"), argv[optind]);
}
exec_shell();
}
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