src/nspawn.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   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.
  12
  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.
  17
  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/>.
  20 ***/
  21
  22 #include <signal.h>
  23 #include <sched.h>
  24 #include <unistd.h>
  25 #include <sys/types.h>
  26 #include <sys/syscall.h>
  27 #include <sys/mount.h>
  28 #include <sys/wait.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <stdio.h>
  32 #include <errno.h>
  33 #include <sys/prctl.h>
  34 #include <sys/capability.h>
  35 #include <getopt.h>
  36 #include <sys/epoll.h>
  37 #include <termios.h>
  38 #include <sys/signalfd.h>
  39
  40 #include "log.h"
  41 #include "util.h"
  42 #include "missing.h"
  43 #include "cgroup-util.h"
  44 #include "sd-daemon.h"
  45 #include "strv.h"
  46
  47 static char *arg_directory = NULL;
  48
  49 static int help(void) {
  50
  51         printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n"
  52                "Spawn a minimal namespace container for debugging, testing and building.\n\n"
  53                "  -h --help            Show this help\n"
  54                "  -D --directory=NAME  Root directory for the container\n",
  55                program_invocation_short_name);
  56
  57         return 0;
  58 }
  59
  60 static int parse_argv(int argc, char *argv[]) {
  61
  62         static const struct option options[] = {
  63                 { "help",      no_argument,       NULL, 'h' },
  64                 { "directory", required_argument, NULL, 'D' },
  65                 { NULL,        0,                 NULL, 0   }
  66         };
  67
  68         int c;
  69
  70         assert(argc >= 0);
  71         assert(argv);
  72
  73         while ((c = getopt_long(argc, argv, "+hD:", options, NULL)) >= 0) {
  74
  75                 switch (c) {
  76
  77                 case 'h':
  78                         help();
  79                         return 0;
  80
  81                 case 'D':
  82                         free(arg_directory);
  83                         if (!(arg_directory = strdup(optarg))) {
  84                                 log_error("Failed to duplicate root directory.");
  85                                 return -ENOMEM;
  86                         }
  87
  88                         break;
  89
  90                 case '?':
  91                         return -EINVAL;
  92
  93                 default:
  94                         log_error("Unknown option code %c", c);
  95                         return -EINVAL;
  96                 }
  97         }
  98
  99         return 1;
 100 }
 101
 102 static int mount_all(const char *dest) {
 103
 104         typedef struct MountPoint {
 105                 const char *what;
 106                 const char *where;
 107                 const char *type;
 108                 const char *options;
 109                 unsigned long flags;
 110                 bool fatal;
 111         } MountPoint;
 112
 113         static const MountPoint mount_table[] = {
 114                 { "proc",      "/proc",     "proc",      NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
 115                 { "/proc/sys", "/proc/sys", "bind",      NULL,        MS_BIND, true },                      /* Bind mount first */
 116                 { "/proc/sys", "/proc/sys", "bind",      NULL,        MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */
 117                 { "sysfs",     "/sys",      "sysfs",     NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, true },
 118                 { "tmpfs",     "/dev",      "tmpfs",     "mode=755",  MS_NOSUID, true },
 119                 { "/dev/pts",  "/dev/pts",  "bind",      NULL,        MS_BIND, true },
 120                 { "tmpfs",     "/dev/.run", "tmpfs",     "mode=755",  MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
 121 #ifdef HAVE_SELINUX
 122                 { "selinux",   "/selinux",  "selinuxfs", NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, false },
 123 #endif
 124         };
 125
 126         unsigned k;
 127         int r = 0;
 128
 129         for (k = 0; k < ELEMENTSOF(mount_table); k++) {
 130                 char *where;
 131                 int t;
 132
 133                 if (asprintf(&where, "%s/%s", dest, mount_table[k].where) < 0) {
 134                         log_error("Out of memory");
 135
 136                         if (r == 0)
 137                                 r = -ENOMEM;
 138
 139                         break;
 140                 }
 141
 142                 if ((t = path_is_mount_point(where)) < 0) {
 143                         log_error("Failed to detect whether %s is a mount point: %s", where, strerror(-t));
 144                         free(where);
 145
 146                         if (r == 0)
 147                                 r = t;
 148
 149                         continue;
 150                 }
 151
 152                 mkdir_p(where, 0755);
 153
 154                 if (mount(mount_table[k].what,
 155                           where,
 156                           mount_table[k].type,
 157                           mount_table[k].flags,
 158                           mount_table[k].options) < 0 &&
 159                     mount_table[k].fatal) {
 160
 161                         log_error("mount(%s) failed: %m", where);
 162
 163                         if (r == 0)
 164                                 r = -errno;
 165                 }
 166
 167                 free(where);
 168         }
 169
 170         return r;
 171 }
 172
 173 static int copy_devnodes(const char *dest, const char *console) {
 174
 175         static const char devnodes[] =
 176                 "null\0"
 177                 "zero\0"
 178                 "full\0"
 179                 "random\0"
 180                 "urandom\0"
 181                 "tty\0"
 182                 "ptmx\0"
 183                 "kmsg\0"
 184                 "rtc0\0";
 185
 186         const char *d;
 187         int r = 0, k;
 188         mode_t u;
 189         struct stat st;
 190         char *from = NULL, *to = NULL;
 191
 192         assert(dest);
 193         assert(console);
 194
 195         u = umask(0000);
 196
 197         NULSTR_FOREACH(d, devnodes) {
 198                 from = to = NULL;
 199
 200                 asprintf(&from, "/dev/%s", d);
 201                 asprintf(&to, "%s/dev/%s", dest, d);
 202
 203                 if (!from || !to) {
 204                         log_error("Failed to allocate devnode path");
 205
 206                         free(from);
 207                         free(to);
 208
 209                         from = to = NULL;
 210
 211                         if (r == 0)
 212                                 r = -ENOMEM;
 213
 214                         break;
 215                 }
 216
 217                 if (stat(from, &st) < 0) {
 218
 219                         if (errno != ENOENT) {
 220                                 log_error("Failed to stat %s: %m", from);
 221                                 if (r == 0)
 222                                         r = -errno;
 223                         }
 224
 225                 } else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {
 226
 227                         log_error("%s is not a char or block device, cannot copy.", from);
 228                         if (r == 0)
 229                                 r = -EIO;
 230
 231                 } else if (mknod(to, st.st_mode, st.st_rdev) < 0) {
 232
 233                         log_error("mknod(%s) failed: %m", dest);
 234                         if (r == 0)
 235                                 r = -errno;
 236                 }
 237
 238                 free(from);
 239                 free(to);
 240         }
 241
 242         if (stat(console, &st) < 0) {
 243
 244                 log_error("Failed to stat %s: %m", console);
 245                 if (r == 0)
 246                         r = -errno;
 247
 248                 goto finish;
 249
 250         } else if (!S_ISCHR(st.st_mode)) {
 251
 252                 log_error("/dev/console is not a char device.");
 253                 if (r == 0)
 254                         r = -EIO;
 255
 256                 goto finish;
 257         }
 258
 259         if (asprintf(&to, "%s/dev/console", dest) < 0) {
 260
 261                 log_error("Out of memory");
 262                 if (r == 0)
 263                         r = -ENOMEM;
 264
 265                  goto finish;
 266         }
 267
 268         /* We need to bind mount the right tty to /dev/console since
 269          * ptys can only exist on pts file systems. To have something
 270          * to bind mount things on we create a device node first, that
 271          * has the right major/minor (note that the major minor
 272          * doesn't actually matter here, since we mount it over
 273          * anyway). */
 274
 275         if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0)
 276                 log_error("mknod for /dev/console failed: %m");
 277
 278         if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
 279                 log_error("bind mount for /dev/console failed: %m");
 280
 281                 if (r == 0)
 282                         r = -errno;
 283         }
 284
 285         free(to);
 286
 287         if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) {
 288                 log_error("Failed to correct access mode for TTY: %s", strerror(-k));
 289
 290                 if (r == 0)
 291                         r = k;
 292         }
 293
 294 finish:
 295
 296         umask(u);
 297
 298         return r;
 299 }
 300
 301 static int drop_capabilities(void) {
 302         static const unsigned long retain[] = {
 303                 CAP_CHOWN,
 304                 CAP_DAC_OVERRIDE,
 305                 CAP_DAC_READ_SEARCH,
 306                 CAP_FOWNER,
 307                 CAP_FSETID,
 308                 CAP_IPC_OWNER,
 309                 CAP_KILL,
 310                 CAP_LEASE,
 311                 CAP_LINUX_IMMUTABLE,
 312                 CAP_NET_BIND_SERVICE,
 313                 CAP_NET_BROADCAST,
 314                 CAP_NET_RAW,
 315                 CAP_SETGID,
 316                 CAP_SETFCAP,
 317                 CAP_SETPCAP,
 318                 CAP_SETUID,
 319                 CAP_SYS_ADMIN,
 320                 CAP_SYS_CHROOT,
 321                 CAP_SYS_NICE,
 322                 CAP_SYS_PTRACE,
 323                 CAP_SYS_TTY_CONFIG
 324         };
 325
 326         unsigned long l;
 327
 328         for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l ++) {
 329                 unsigned i;
 330
 331                 for (i = 0; i < ELEMENTSOF(retain); i++)
 332                         if (retain[i] == l)
 333                                 break;
 334
 335                 if (i < ELEMENTSOF(retain))
 336                         continue;
 337
 338                 if (prctl(PR_CAPBSET_DROP, l) < 0) {
 339
 340                         /* If this capability is not known, EINVAL
 341                          * will be returned, let's ignore this. */
 342                         if (errno == EINVAL)
 343                                 continue;
 344
 345                         log_error("PR_CAPBSET_DROP failed: %m");
 346                         return -errno;
 347                 }
 348         }
 349
 350         return 0;
 351 }
 352
 353 static int is_os_tree(const char *path) {
 354         int r;
 355         char *p;
 356         /* We use /bin/sh as flag file if something is an OS */
 357
 358         if (asprintf(&p, "%s/bin/sh", path) < 0)
 359                 return -ENOMEM;
 360
 361         r = access(p, F_OK);
 362         free(p);
 363
 364         return r < 0 ? 0 : 1;
 365 }
 366
 367 #define BUFFER_SIZE 1024
 368
 369 static int process_pty(int master, sigset_t *mask) {
 370         char in_buffer[BUFFER_SIZE], out_buffer[BUFFER_SIZE];
 371         size_t in_buffer_full = 0, out_buffer_full = 0;
 372         struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev;
 373         bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false;
 374         int ep = -1, signal_fd = -1, r;
 375
 376         fd_nonblock(STDIN_FILENO, 1);
 377         fd_nonblock(STDOUT_FILENO, 1);
 378         fd_nonblock(master, 1);
 379
 380         if ((signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 381                 log_error("signalfd(): %m");
 382                 r = -errno;
 383                 goto finish;
 384         }
 385
 386         if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) {
 387                 log_error("Failed to create epoll: %m");
 388                 r = -errno;
 389                 goto finish;
 390         }
 391
 392         zero(stdin_ev);
 393         stdin_ev.events = EPOLLIN|EPOLLET;
 394         stdin_ev.data.fd = STDIN_FILENO;
 395
 396         zero(stdout_ev);
 397         stdout_ev.events = EPOLLOUT|EPOLLET;
 398         stdout_ev.data.fd = STDOUT_FILENO;
 399
 400         zero(master_ev);
 401         master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
 402         master_ev.data.fd = master;
 403
 404         zero(signal_ev);
 405         signal_ev.events = EPOLLIN;
 406         signal_ev.data.fd = signal_fd;
 407
 408         if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 ||
 409             epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 ||
 410             epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 ||
 411             epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) {
 412                 log_error("Failed to regiser fds in epoll: %m");
 413                 r = -errno;
 414                 goto finish;
 415         }
 416
 417         for (;;) {
 418                 struct epoll_event ev[16];
 419                 ssize_t k;
 420                 int i, nfds;
 421
 422                 if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) {
 423
 424                         if (errno == EINTR || errno == EAGAIN)
 425                                 continue;
 426
 427                         log_error("epoll_wait(): %m");
 428                         r = -errno;
 429                         goto finish;
 430                 }
 431
 432                 assert(nfds >= 1);
 433
 434                 for (i = 0; i < nfds; i++) {
 435                         if (ev[i].data.fd == STDIN_FILENO) {
 436
 437                                 if (ev[i].events & (EPOLLIN|EPOLLHUP))
 438                                         stdin_readable = true;
 439
 440                         } else if (ev[i].data.fd == STDOUT_FILENO) {
 441
 442                                 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
 443                                         stdout_writable = true;
 444
 445                         } else if (ev[i].data.fd == master) {
 446
 447                                 if (ev[i].events & (EPOLLIN|EPOLLHUP))
 448                                         master_readable = true;
 449
 450                                 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
 451                                         master_writable = true;
 452
 453                         } else if (ev[i].data.fd == signal_fd) {
 454                                 struct signalfd_siginfo sfsi;
 455                                 ssize_t n;
 456
 457                                 if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
 458
 459                                         if (n >= 0) {
 460                                                 r = -EIO;
 461                                                 goto finish;
 462                                         }
 463
 464                                         if (errno != EINTR && errno != EAGAIN) {
 465                                                 r = -errno;
 466                                                 goto finish;
 467                                         }
 468                                 } else {
 469
 470                                         if (sfsi.ssi_signo == SIGWINCH) {
 471                                                 struct winsize ws;
 472
 473                                                 /* The window size changed, let's forward that. */
 474                                                 if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
 475                                                         ioctl(master, TIOCSWINSZ, &ws);
 476                                         } else {
 477                                                 r = -EINTR;
 478                                                 goto finish;
 479                                         }
 480                                 }
 481                         }
 482                 }
 483
 484                 while ((stdin_readable && in_buffer_full <= 0) ||
 485                        (master_writable && in_buffer_full > 0) ||
 486                        (master_readable && out_buffer_full <= 0) ||
 487                        (stdout_writable && out_buffer_full > 0)) {
 488
 489                         if (stdin_readable && in_buffer_full < BUFFER_SIZE) {
 490
 491                                 if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) {
 492
 493                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 494                                                 stdin_readable = false;
 495                                         else {
 496                                                 log_error("read(): %m");
 497                                                 goto finish;
 498                                         }
 499                                 } else
 500                                         in_buffer_full += (size_t) k;
 501                         }
 502
 503                         if (master_writable && in_buffer_full > 0) {
 504
 505                                 if ((k = write(master, in_buffer, in_buffer_full)) < 0) {
 506
 507                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 508                                                 master_writable = false;
 509                                         else {
 510                                                 log_error("write(): %m");
 511                                                 goto finish;
 512                                         }
 513
 514                                 } else {
 515                                         assert(in_buffer_full >= (size_t) k);
 516                                         memmove(in_buffer, in_buffer + k, in_buffer_full - k);
 517                                         in_buffer_full -= k;
 518                                 }
 519                         }
 520
 521                         if (master_readable && out_buffer_full < BUFFER_SIZE) {
 522
 523                                 if ((k = read(master, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) {
 524
 525                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 526                                                 master_readable = false;
 527                                         else {
 528                                                 log_error("read(): %m");
 529                                                 goto finish;
 530                                         }
 531                                 }  else
 532                                         out_buffer_full += (size_t) k;
 533                         }
 534
 535                         if (stdout_writable && out_buffer_full > 0) {
 536
 537                                 if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) {
 538
 539                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 540                                                 stdout_writable = false;
 541                                         else {
 542                                                 log_error("write(): %m");
 543                                                 goto finish;
 544                                         }
 545
 546                                 } else {
 547                                         assert(out_buffer_full >= (size_t) k);
 548                                         memmove(out_buffer, out_buffer + k, out_buffer_full - k);
 549                                         out_buffer_full -= k;
 550                                 }
 551                         }
 552                 }
 553         }
 554
 555 finish:
 556         if (ep >= 0)
 557                 close_nointr_nofail(ep);
 558
 559         if (signal_fd >= 0)
 560                 close_nointr_nofail(signal_fd);
 561
 562         return r;
 563 }
 564
 565 int main(int argc, char *argv[]) {
 566         pid_t pid = 0;
 567         int r = EXIT_FAILURE, k;
 568         char *oldcg = NULL, *newcg = NULL;
 569         int master = -1;
 570         const char *console = NULL;
 571         struct termios saved_attr, raw_attr;
 572         sigset_t mask;
 573         bool saved_attr_valid = false;
 574         struct winsize ws;
 575
 576         log_parse_environment();
 577         log_open();
 578
 579         if ((r = parse_argv(argc, argv)) <= 0)
 580                 goto finish;
 581
 582         if (arg_directory) {
 583                 char *p;
 584
 585                 p = path_make_absolute_cwd(arg_directory);
 586                 free(arg_directory);
 587                 arg_directory = p;
 588         } else
 589                 arg_directory = get_current_dir_name();
 590
 591         if (!arg_directory) {
 592                 log_error("Failed to determine path");
 593                 goto finish;
 594         }
 595
 596         path_kill_slashes(arg_directory);
 597
 598         if (geteuid() != 0) {
 599                 log_error("Need to be root.");
 600                 goto finish;
 601         }
 602
 603         if (sd_booted() <= 0) {
 604                 log_error("Not running on a systemd system.");
 605                 goto finish;
 606         }
 607
 608         if (path_equal(arg_directory, "/")) {
 609                 log_error("Spawning container on root directory not supported.");
 610                 goto finish;
 611         }
 612
 613         if (is_os_tree(arg_directory) <= 0) {
 614                 log_error("Directory %s doesn't look like an OS root directory. Refusing.", arg_directory);
 615                 goto finish;
 616         }
 617
 618         if ((k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg)) < 0) {
 619                 log_error("Failed to determine current cgroup: %s", strerror(-k));
 620                 goto finish;
 621         }
 622
 623         if (asprintf(&newcg, "%s/nspawn-%lu", oldcg, (unsigned long) getpid()) < 0) {
 624                 log_error("Failed to allocate cgroup path.");
 625                 goto finish;
 626         }
 627
 628         if ((k = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, newcg, 0)) < 0)  {
 629                 log_error("Failed to create cgroup: %s", strerror(-k));
 630                 goto finish;
 631         }
 632
 633         if ((master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY)) < 0) {
 634                 log_error("Failed to acquire pseudo tty: %m");
 635                 goto finish;
 636         }
 637
 638         if (!(console = ptsname(master))) {
 639                 log_error("Failed to determine tty name: %m");
 640                 goto finish;
 641         }
 642
 643         log_info("Spawning namespace container on %s (console is %s).", arg_directory, console);
 644
 645         if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
 646                 ioctl(master, TIOCSWINSZ, &ws);
 647
 648         if (unlockpt(master) < 0) {
 649                 log_error("Failed to unlock tty: %m");
 650                 goto finish;
 651         }
 652
 653         if (tcgetattr(STDIN_FILENO, &saved_attr) < 0) {
 654                 log_error("Failed to get terminal attributes: %m");
 655                 goto finish;
 656         }
 657
 658         saved_attr_valid = true;
 659
 660         raw_attr = saved_attr;
 661         cfmakeraw(&raw_attr);
 662         raw_attr.c_lflag &= ~ECHO;
 663
 664         if (tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr) < 0) {
 665                 log_error("Failed to set terminal attributes: %m");
 666                 goto finish;
 667         }
 668
 669         assert_se(sigemptyset(&mask) == 0);
 670         sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
 671         assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
 672
 673         if ((pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS, NULL)) < 0) {
 674                 log_error("clone() failed: %m");
 675                 goto finish;
 676         }
 677
 678         if (pid == 0) {
 679                 /* child */
 680
 681                 const char *hn;
 682                 const char *envp[] = {
 683                         "HOME=/root",
 684                         "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
 685                         NULL,
 686                         NULL
 687                 };
 688
 689                 envp[2] = strv_find_prefix(environ, "TERM=");
 690
 691                 close_nointr_nofail(master);
 692
 693                 close_nointr(STDIN_FILENO);
 694                 close_nointr(STDOUT_FILENO);
 695                 close_nointr(STDERR_FILENO);
 696
 697                 close_all_fds(NULL, 0);
 698
 699                 reset_all_signal_handlers();
 700
 701                 assert_se(sigemptyset(&mask) == 0);
 702                 assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 703
 704                 if (setsid() < 0)
 705                         goto child_fail;
 706
 707                 if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
 708                         goto child_fail;
 709
 710                 if (mount_all(arg_directory) < 0)
 711                         goto child_fail;
 712
 713                 if (copy_devnodes(arg_directory, console) < 0)
 714                         goto child_fail;
 715
 716                 if (chdir(arg_directory) < 0) {
 717                         log_error("chdir(%s) failed: %m", arg_directory);
 718                         goto child_fail;
 719                 }
 720
 721                 if (open_terminal("dev/console", O_RDWR) != STDIN_FILENO ||
 722                     dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO ||
 723                     dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO)
 724                         goto child_fail;
 725
 726                 if (mount(arg_directory, "/", "bind", MS_BIND|MS_MOVE, NULL) < 0) {
 727                         log_error("mount(MS_MOVE) failed: %m");
 728                         goto child_fail;
 729                 }
 730
 731                 if (chroot(".") < 0) {
 732                         log_error("chroot() failed: %m");
 733                         goto child_fail;
 734                 }
 735
 736                 if (chdir("/") < 0) {
 737                         log_error("chdir() failed: %m");
 738                         goto child_fail;
 739                 }
 740
 741                 umask(0002);
 742
 743                 if (drop_capabilities() < 0)
 744                         goto child_fail;
 745
 746                 if ((hn = file_name_from_path(arg_directory)))
 747                         sethostname(hn, strlen(hn));
 748
 749                 if (argc > optind)
 750                         execvpe(argv[optind], argv + optind, (char**) envp);
 751                 else {
 752                         chdir("/root");
 753                         execle("/bin/bash", "-bash", NULL, (char**) envp);
 754                 }
 755
 756                 log_error("execv() failed: %m");
 757
 758         child_fail:
 759                 _exit(EXIT_FAILURE);
 760         }
 761
 762         if (process_pty(master, &mask) < 0)
 763                 goto finish;
 764
 765         if (saved_attr_valid) {
 766                 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
 767                 saved_attr_valid = false;
 768         }
 769
 770         r = wait_for_terminate_and_warn(argc > optind ? argv[optind] : "bash", pid);
 771
 772         if (r < 0)
 773                 r = EXIT_FAILURE;
 774
 775 finish:
 776         if (saved_attr_valid)
 777                 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
 778
 779         if (master >= 0)
 780                 close_nointr_nofail(master);
 781
 782         if (oldcg)
 783                 cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);
 784
 785         if (newcg)
 786                 cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, newcg, true);
 787
 788         free(arg_directory);
 789         free(oldcg);
 790         free(newcg);
 791
 792         return r;
 793 }