1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
25 #include <sys/types.h>
26 #include <sys/syscall.h>
27 #include <sys/mount.h>
33 #include <sys/prctl.h>
34 #include <sys/capability.h>
36 #include <sys/epoll.h>
38 #include <sys/signalfd.h>
44 #include "cgroup-util.h"
45 #include "sd-daemon.h"
47 #include "loopback-setup.h"
49 static char *arg_directory = NULL;
50 static char *arg_user = NULL;
51 static bool arg_no_net = false;
53 static int help(void) {
55 printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n"
56 "Spawn a minimal namespace container for debugging, testing and building.\n\n"
57 " -h --help Show this help\n"
58 " -D --directory=NAME Root directory for the container\n"
59 " -u --user=USER Run the command under specified user or uid\n"
60 " --no-net Disable network in container\n",
61 program_invocation_short_name);
66 static int parse_argv(int argc, char *argv[]) {
72 static const struct option options[] = {
73 { "help", no_argument, NULL, 'h' },
74 { "directory", required_argument, NULL, 'D' },
75 { "user", required_argument, NULL, 'u' },
76 { "no-net", no_argument, NULL, ARG_NO_NET },
85 while ((c = getopt_long(argc, argv, "+hD:u:", options, NULL)) >= 0) {
95 if (!(arg_directory = strdup(optarg))) {
96 log_error("Failed to duplicate root directory.");
104 if (!(arg_user = strdup(optarg))) {
105 log_error("Failed to duplicate user name.");
119 log_error("Unknown option code %c", c);
127 static int mount_all(const char *dest) {
129 typedef struct MountPoint {
138 static const MountPoint mount_table[] = {
139 { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
140 { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND, true }, /* Bind mount first */
141 { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */
142 { "/sys", "/sys", "bind", NULL, MS_BIND, true }, /* Bind mount first */
143 { "/sys", "/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */
144 { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID, true },
145 { "/dev/pts", "/dev/pts", "bind", NULL, MS_BIND, true },
146 { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV, true },
148 { "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND, false }, /* Bind mount first */
149 { "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false }, /* Then, make it r/o */
157 for (k = 0; k < ELEMENTSOF(mount_table); k++) {
160 if (asprintf(&where, "%s/%s", dest, mount_table[k].where) < 0) {
161 log_error("Out of memory");
169 if ((t = path_is_mount_point(where)) < 0) {
170 log_error("Failed to detect whether %s is a mount point: %s", where, strerror(-t));
179 mkdir_p(where, 0755);
181 if (mount(mount_table[k].what,
184 mount_table[k].flags,
185 mount_table[k].options) < 0 &&
186 mount_table[k].fatal) {
188 log_error("mount(%s) failed: %m", where);
197 /* Fix the timezone, if possible */
198 if (asprintf(&where, "%s/%s", dest, "/etc/localtime") >= 0) {
199 mount("/etc/localtime", where, "bind", MS_BIND, NULL);
200 mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
207 static int copy_devnodes(const char *dest, const char *console) {
209 static const char devnodes[] =
224 char *from = NULL, *to = NULL;
231 NULSTR_FOREACH(d, devnodes) {
234 asprintf(&from, "/dev/%s", d);
235 asprintf(&to, "%s/dev/%s", dest, d);
238 log_error("Failed to allocate devnode path");
251 if (stat(from, &st) < 0) {
253 if (errno != ENOENT) {
254 log_error("Failed to stat %s: %m", from);
259 } else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {
261 log_error("%s is not a char or block device, cannot copy.", from);
265 } else if (mknod(to, st.st_mode, st.st_rdev) < 0) {
267 log_error("mknod(%s) failed: %m", dest);
276 if (stat(console, &st) < 0) {
278 log_error("Failed to stat %s: %m", console);
284 } else if (!S_ISCHR(st.st_mode)) {
286 log_error("/dev/console is not a char device.");
293 if (asprintf(&to, "%s/dev/console", dest) < 0) {
295 log_error("Out of memory");
302 /* We need to bind mount the right tty to /dev/console since
303 * ptys can only exist on pts file systems. To have something
304 * to bind mount things on we create a device node first, that
305 * has the right major/minor (note that the major minor
306 * doesn't actually matter here, since we mount it over
309 if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0)
310 log_error("mknod for /dev/console failed: %m");
312 if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
313 log_error("bind mount for /dev/console failed: %m");
321 if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) {
322 log_error("Failed to correct access mode for TTY: %s", strerror(-k));
334 static int drop_capabilities(void) {
335 static const unsigned long retain[] = {
345 CAP_NET_BIND_SERVICE,
361 for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l++) {
364 for (i = 0; i < ELEMENTSOF(retain); i++)
368 if (i < ELEMENTSOF(retain))
371 if (prctl(PR_CAPBSET_DROP, l) < 0) {
373 /* If this capability is not known, EINVAL
374 * will be returned, let's ignore this. */
378 log_error("PR_CAPBSET_DROP failed: %m");
386 static int is_os_tree(const char *path) {
389 /* We use /bin/sh as flag file if something is an OS */
391 if (asprintf(&p, "%s/bin/sh", path) < 0)
397 return r < 0 ? 0 : 1;
400 #define BUFFER_SIZE 1024
402 static int process_pty(int master, sigset_t *mask) {
404 char in_buffer[BUFFER_SIZE], out_buffer[BUFFER_SIZE];
405 size_t in_buffer_full = 0, out_buffer_full = 0;
406 struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev;
407 bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false;
408 int ep = -1, signal_fd = -1, r;
410 fd_nonblock(STDIN_FILENO, 1);
411 fd_nonblock(STDOUT_FILENO, 1);
412 fd_nonblock(master, 1);
414 if ((signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
415 log_error("signalfd(): %m");
420 if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) {
421 log_error("Failed to create epoll: %m");
427 stdin_ev.events = EPOLLIN|EPOLLET;
428 stdin_ev.data.fd = STDIN_FILENO;
431 stdout_ev.events = EPOLLOUT|EPOLLET;
432 stdout_ev.data.fd = STDOUT_FILENO;
435 master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
436 master_ev.data.fd = master;
439 signal_ev.events = EPOLLIN;
440 signal_ev.data.fd = signal_fd;
442 if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 ||
443 epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 ||
444 epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 ||
445 epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) {
446 log_error("Failed to regiser fds in epoll: %m");
452 struct epoll_event ev[16];
456 if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) {
458 if (errno == EINTR || errno == EAGAIN)
461 log_error("epoll_wait(): %m");
468 for (i = 0; i < nfds; i++) {
469 if (ev[i].data.fd == STDIN_FILENO) {
471 if (ev[i].events & (EPOLLIN|EPOLLHUP))
472 stdin_readable = true;
474 } else if (ev[i].data.fd == STDOUT_FILENO) {
476 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
477 stdout_writable = true;
479 } else if (ev[i].data.fd == master) {
481 if (ev[i].events & (EPOLLIN|EPOLLHUP))
482 master_readable = true;
484 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
485 master_writable = true;
487 } else if (ev[i].data.fd == signal_fd) {
488 struct signalfd_siginfo sfsi;
491 if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
494 log_error("Failed to read from signalfd: invalid block size");
499 if (errno != EINTR && errno != EAGAIN) {
500 log_error("Failed to read from signalfd: %m");
506 if (sfsi.ssi_signo == SIGWINCH) {
509 /* The window size changed, let's forward that. */
510 if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
511 ioctl(master, TIOCSWINSZ, &ws);
520 while ((stdin_readable && in_buffer_full <= 0) ||
521 (master_writable && in_buffer_full > 0) ||
522 (master_readable && out_buffer_full <= 0) ||
523 (stdout_writable && out_buffer_full > 0)) {
525 if (stdin_readable && in_buffer_full < BUFFER_SIZE) {
527 if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) {
529 if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
530 stdin_readable = false;
532 log_error("read(): %m");
537 in_buffer_full += (size_t) k;
540 if (master_writable && in_buffer_full > 0) {
542 if ((k = write(master, in_buffer, in_buffer_full)) < 0) {
544 if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
545 master_writable = false;
547 log_error("write(): %m");
553 assert(in_buffer_full >= (size_t) k);
554 memmove(in_buffer, in_buffer + k, in_buffer_full - k);
559 if (master_readable && out_buffer_full < BUFFER_SIZE) {
561 if ((k = read(master, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) {
563 if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
564 master_readable = false;
566 log_error("read(): %m");
571 out_buffer_full += (size_t) k;
574 if (stdout_writable && out_buffer_full > 0) {
576 if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) {
578 if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
579 stdout_writable = false;
581 log_error("write(): %m");
587 assert(out_buffer_full >= (size_t) k);
588 memmove(out_buffer, out_buffer + k, out_buffer_full - k);
589 out_buffer_full -= k;
597 close_nointr_nofail(ep);
600 close_nointr_nofail(signal_fd);
605 int main(int argc, char *argv[]) {
607 int r = EXIT_FAILURE, k;
608 char *oldcg = NULL, *newcg = NULL;
610 const char *console = NULL;
611 struct termios saved_attr, raw_attr;
613 bool saved_attr_valid = false;
616 log_parse_environment();
619 if ((r = parse_argv(argc, argv)) <= 0)
625 p = path_make_absolute_cwd(arg_directory);
629 arg_directory = get_current_dir_name();
631 if (!arg_directory) {
632 log_error("Failed to determine path");
636 path_kill_slashes(arg_directory);
638 if (geteuid() != 0) {
639 log_error("Need to be root.");
643 if (sd_booted() <= 0) {
644 log_error("Not running on a systemd system.");
648 if (path_equal(arg_directory, "/")) {
649 log_error("Spawning container on root directory not supported.");
653 if (is_os_tree(arg_directory) <= 0) {
654 log_error("Directory %s doesn't look like an OS root directory. Refusing.", arg_directory);
658 if ((k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg)) < 0) {
659 log_error("Failed to determine current cgroup: %s", strerror(-k));
663 if (asprintf(&newcg, "%s/nspawn-%lu", oldcg, (unsigned long) getpid()) < 0) {
664 log_error("Failed to allocate cgroup path.");
668 if ((k = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, newcg, 0)) < 0) {
669 log_error("Failed to create cgroup: %s", strerror(-k));
673 if ((master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY)) < 0) {
674 log_error("Failed to acquire pseudo tty: %m");
678 if (!(console = ptsname(master))) {
679 log_error("Failed to determine tty name: %m");
683 log_info("Spawning namespace container on %s (console is %s).", arg_directory, console);
685 if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
686 ioctl(master, TIOCSWINSZ, &ws);
688 if (unlockpt(master) < 0) {
689 log_error("Failed to unlock tty: %m");
693 if (tcgetattr(STDIN_FILENO, &saved_attr) < 0) {
694 log_error("Failed to get terminal attributes: %m");
698 saved_attr_valid = true;
700 raw_attr = saved_attr;
701 cfmakeraw(&raw_attr);
702 raw_attr.c_lflag &= ~ECHO;
704 if (tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr) < 0) {
705 log_error("Failed to set terminal attributes: %m");
709 assert_se(sigemptyset(&mask) == 0);
710 sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
711 assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
713 if ((pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS|(arg_no_net ? CLONE_NEWNET : 0), NULL)) < 0) {
714 log_error("clone() failed: %m");
722 const char *home = NULL;
723 uid_t uid = (uid_t) -1;
724 gid_t gid = (gid_t) -1;
725 const char *envp[] = {
726 "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
734 envp[1] = strv_find_prefix(environ, "TERM=");
736 close_nointr_nofail(master);
738 close_nointr(STDIN_FILENO);
739 close_nointr(STDOUT_FILENO);
740 close_nointr(STDERR_FILENO);
742 close_all_fds(NULL, 0);
744 reset_all_signal_handlers();
746 assert_se(sigemptyset(&mask) == 0);
747 assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
752 if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
755 /* Mark / as private, in case somebody marked it shared */
756 if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0)
759 if (mount_all(arg_directory) < 0)
762 if (copy_devnodes(arg_directory, console) < 0)
765 if (chdir(arg_directory) < 0) {
766 log_error("chdir(%s) failed: %m", arg_directory);
770 if (open_terminal("dev/console", O_RDWR) != STDIN_FILENO ||
771 dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO ||
772 dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO)
775 if (mount(arg_directory, "/", "bind", MS_BIND|MS_MOVE, NULL) < 0) {
776 log_error("mount(MS_MOVE) failed: %m");
780 if (chroot(".") < 0) {
781 log_error("chroot() failed: %m");
785 if (chdir("/") < 0) {
786 log_error("chdir() failed: %m");
794 if (drop_capabilities() < 0)
799 if (get_user_creds((const char**)&arg_user, &uid, &gid, &home) < 0) {
800 log_error("get_user_creds() failed: %m");
804 if (mkdir_parents(home, 0775) < 0) {
805 log_error("mkdir_parents() failed: %m");
809 if (safe_mkdir(home, 0775, uid, gid) < 0) {
810 log_error("safe_mkdir() failed: %m");
814 if (initgroups((const char*)arg_user, gid) < 0) {
815 log_error("initgroups() failed: %m");
819 if (setresgid(gid, gid, gid) < 0) {
820 log_error("setregid() failed: %m");
824 if (setresuid(uid, uid, uid) < 0) {
825 log_error("setreuid() failed: %m");
830 if ((asprintf((char**)(envp + 2), "HOME=%s", home? home: "/root") < 0) ||
831 (asprintf((char**)(envp + 3), "USER=%s", arg_user? arg_user : "root") < 0) ||
832 (asprintf((char**)(envp + 4), "LOGNAME=%s", arg_user? arg_user : "root") < 0)) {
833 log_error("Out of memory");
837 if ((hn = file_name_from_path(arg_directory)))
838 sethostname(hn, strlen(hn));
841 execvpe(argv[optind], argv + optind, (char**) envp);
843 chdir(home ? home : "/root");
844 execle("/bin/bash", "-bash", NULL, (char**) envp);
847 log_error("execv() failed: %m");
853 if (process_pty(master, &mask) < 0)
856 if (saved_attr_valid) {
857 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
858 saved_attr_valid = false;
861 r = wait_for_terminate_and_warn(argc > optind ? argv[optind] : "bash", pid);
867 if (saved_attr_valid)
868 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
871 close_nointr_nofail(master);
874 cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);
877 cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, newcg, true);