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",     "/run",      "tmpfs",     "mode=755",  MS_NOSUID|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         char *where;
 129
 130         for (k = 0; k < ELEMENTSOF(mount_table); k++) {
 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         /* Fix the timezone, if possible */
 171         if (asprintf(&where, "%s/%s", dest, "/etc/localtime") >= 0) {
 172                 mount("/etc/localtime", where, "bind", MS_BIND, NULL);
 173                 mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
 174                 free(where);
 175         }
 176
 177         return r;
 178 }
 179
 180 static int copy_devnodes(const char *dest, const char *console) {
 181
 182         static const char devnodes[] =
 183                 "null\0"
 184                 "zero\0"
 185                 "full\0"
 186                 "random\0"
 187                 "urandom\0"
 188                 "tty\0"
 189                 "ptmx\0"
 190                 "kmsg\0"
 191                 "rtc0\0";
 192
 193         const char *d;
 194         int r = 0, k;
 195         mode_t u;
 196         struct stat st;
 197         char *from = NULL, *to = NULL;
 198
 199         assert(dest);
 200         assert(console);
 201
 202         u = umask(0000);
 203
 204         NULSTR_FOREACH(d, devnodes) {
 205                 from = to = NULL;
 206
 207                 asprintf(&from, "/dev/%s", d);
 208                 asprintf(&to, "%s/dev/%s", dest, d);
 209
 210                 if (!from || !to) {
 211                         log_error("Failed to allocate devnode path");
 212
 213                         free(from);
 214                         free(to);
 215
 216                         from = to = NULL;
 217
 218                         if (r == 0)
 219                                 r = -ENOMEM;
 220
 221                         break;
 222                 }
 223
 224                 if (stat(from, &st) < 0) {
 225
 226                         if (errno != ENOENT) {
 227                                 log_error("Failed to stat %s: %m", from);
 228                                 if (r == 0)
 229                                         r = -errno;
 230                         }
 231
 232                 } else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {
 233
 234                         log_error("%s is not a char or block device, cannot copy.", from);
 235                         if (r == 0)
 236                                 r = -EIO;
 237
 238                 } else if (mknod(to, st.st_mode, st.st_rdev) < 0) {
 239
 240                         log_error("mknod(%s) failed: %m", dest);
 241                         if (r == 0)
 242                                 r = -errno;
 243                 }
 244
 245                 free(from);
 246                 free(to);
 247         }
 248
 249         if (stat(console, &st) < 0) {
 250
 251                 log_error("Failed to stat %s: %m", console);
 252                 if (r == 0)
 253                         r = -errno;
 254
 255                 goto finish;
 256
 257         } else if (!S_ISCHR(st.st_mode)) {
 258
 259                 log_error("/dev/console is not a char device.");
 260                 if (r == 0)
 261                         r = -EIO;
 262
 263                 goto finish;
 264         }
 265
 266         if (asprintf(&to, "%s/dev/console", dest) < 0) {
 267
 268                 log_error("Out of memory");
 269                 if (r == 0)
 270                         r = -ENOMEM;
 271
 272                  goto finish;
 273         }
 274
 275         /* We need to bind mount the right tty to /dev/console since
 276          * ptys can only exist on pts file systems. To have something
 277          * to bind mount things on we create a device node first, that
 278          * has the right major/minor (note that the major minor
 279          * doesn't actually matter here, since we mount it over
 280          * anyway). */
 281
 282         if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0)
 283                 log_error("mknod for /dev/console failed: %m");
 284
 285         if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
 286                 log_error("bind mount for /dev/console failed: %m");
 287
 288                 if (r == 0)
 289                         r = -errno;
 290         }
 291
 292         free(to);
 293
 294         if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) {
 295                 log_error("Failed to correct access mode for TTY: %s", strerror(-k));
 296
 297                 if (r == 0)
 298                         r = k;
 299         }
 300
 301 finish:
 302
 303         umask(u);
 304
 305         return r;
 306 }
 307
 308 static int drop_capabilities(void) {
 309         static const unsigned long retain[] = {
 310                 CAP_CHOWN,
 311                 CAP_DAC_OVERRIDE,
 312                 CAP_DAC_READ_SEARCH,
 313                 CAP_FOWNER,
 314                 CAP_FSETID,
 315                 CAP_IPC_OWNER,
 316                 CAP_KILL,
 317                 CAP_LEASE,
 318                 CAP_LINUX_IMMUTABLE,
 319                 CAP_NET_BIND_SERVICE,
 320                 CAP_NET_BROADCAST,
 321                 CAP_NET_RAW,
 322                 CAP_SETGID,
 323                 CAP_SETFCAP,
 324                 CAP_SETPCAP,
 325                 CAP_SETUID,
 326                 CAP_SYS_ADMIN,
 327                 CAP_SYS_CHROOT,
 328                 CAP_SYS_NICE,
 329                 CAP_SYS_PTRACE,
 330                 CAP_SYS_TTY_CONFIG
 331         };
 332
 333         unsigned long l;
 334
 335         for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l++) {
 336                 unsigned i;
 337
 338                 for (i = 0; i < ELEMENTSOF(retain); i++)
 339                         if (retain[i] == l)
 340                                 break;
 341
 342                 if (i < ELEMENTSOF(retain))
 343                         continue;
 344
 345                 if (prctl(PR_CAPBSET_DROP, l) < 0) {
 346
 347                         /* If this capability is not known, EINVAL
 348                          * will be returned, let's ignore this. */
 349                         if (errno == EINVAL)
 350                                 break;
 351
 352                         log_error("PR_CAPBSET_DROP failed: %m");
 353                         return -errno;
 354                 }
 355         }
 356
 357         return 0;
 358 }
 359
 360 static int is_os_tree(const char *path) {
 361         int r;
 362         char *p;
 363         /* We use /bin/sh as flag file if something is an OS */
 364
 365         if (asprintf(&p, "%s/bin/sh", path) < 0)
 366                 return -ENOMEM;
 367
 368         r = access(p, F_OK);
 369         free(p);
 370
 371         return r < 0 ? 0 : 1;
 372 }
 373
 374 #define BUFFER_SIZE 1024
 375
 376 static int process_pty(int master, sigset_t *mask) {
 377
 378         char in_buffer[BUFFER_SIZE], out_buffer[BUFFER_SIZE];
 379         size_t in_buffer_full = 0, out_buffer_full = 0;
 380         struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev;
 381         bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false;
 382         int ep = -1, signal_fd = -1, r;
 383
 384         fd_nonblock(STDIN_FILENO, 1);
 385         fd_nonblock(STDOUT_FILENO, 1);
 386         fd_nonblock(master, 1);
 387
 388         if ((signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 389                 log_error("signalfd(): %m");
 390                 r = -errno;
 391                 goto finish;
 392         }
 393
 394         if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) {
 395                 log_error("Failed to create epoll: %m");
 396                 r = -errno;
 397                 goto finish;
 398         }
 399
 400         zero(stdin_ev);
 401         stdin_ev.events = EPOLLIN|EPOLLET;
 402         stdin_ev.data.fd = STDIN_FILENO;
 403
 404         zero(stdout_ev);
 405         stdout_ev.events = EPOLLOUT|EPOLLET;
 406         stdout_ev.data.fd = STDOUT_FILENO;
 407
 408         zero(master_ev);
 409         master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
 410         master_ev.data.fd = master;
 411
 412         zero(signal_ev);
 413         signal_ev.events = EPOLLIN;
 414         signal_ev.data.fd = signal_fd;
 415
 416         if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 ||
 417             epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 ||
 418             epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 ||
 419             epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) {
 420                 log_error("Failed to regiser fds in epoll: %m");
 421                 r = -errno;
 422                 goto finish;
 423         }
 424
 425         for (;;) {
 426                 struct epoll_event ev[16];
 427                 ssize_t k;
 428                 int i, nfds;
 429
 430                 if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) {
 431
 432                         if (errno == EINTR || errno == EAGAIN)
 433                                 continue;
 434
 435                         log_error("epoll_wait(): %m");
 436                         r = -errno;
 437                         goto finish;
 438                 }
 439
 440                 assert(nfds >= 1);
 441
 442                 for (i = 0; i < nfds; i++) {
 443                         if (ev[i].data.fd == STDIN_FILENO) {
 444
 445                                 if (ev[i].events & (EPOLLIN|EPOLLHUP))
 446                                         stdin_readable = true;
 447
 448                         } else if (ev[i].data.fd == STDOUT_FILENO) {
 449
 450                                 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
 451                                         stdout_writable = true;
 452
 453                         } else if (ev[i].data.fd == master) {
 454
 455                                 if (ev[i].events & (EPOLLIN|EPOLLHUP))
 456                                         master_readable = true;
 457
 458                                 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
 459                                         master_writable = true;
 460
 461                         } else if (ev[i].data.fd == signal_fd) {
 462                                 struct signalfd_siginfo sfsi;
 463                                 ssize_t n;
 464
 465                                 if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
 466
 467                                         if (n >= 0) {
 468                                                 log_error("Failed to read from signalfd: invalid block size");
 469                                                 r = -EIO;
 470                                                 goto finish;
 471                                         }
 472
 473                                         if (errno != EINTR && errno != EAGAIN) {
 474                                                 log_error("Failed to read from signalfd: %m");
 475                                                 r = -errno;
 476                                                 goto finish;
 477                                         }
 478                                 } else {
 479
 480                                         if (sfsi.ssi_signo == SIGWINCH) {
 481                                                 struct winsize ws;
 482
 483                                                 /* The window size changed, let's forward that. */
 484                                                 if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
 485                                                         ioctl(master, TIOCSWINSZ, &ws);
 486                                         } else {
 487                                                 r = 0;
 488                                                 goto finish;
 489                                         }
 490                                 }
 491                         }
 492                 }
 493
 494                 while ((stdin_readable && in_buffer_full <= 0) ||
 495                        (master_writable && in_buffer_full > 0) ||
 496                        (master_readable && out_buffer_full <= 0) ||
 497                        (stdout_writable && out_buffer_full > 0)) {
 498
 499                         if (stdin_readable && in_buffer_full < BUFFER_SIZE) {
 500
 501                                 if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) {
 502
 503                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 504                                                 stdin_readable = false;
 505                                         else {
 506                                                 log_error("read(): %m");
 507                                                 r = -errno;
 508                                                 goto finish;
 509                                         }
 510                                 } else
 511                                         in_buffer_full += (size_t) k;
 512                         }
 513
 514                         if (master_writable && in_buffer_full > 0) {
 515
 516                                 if ((k = write(master, in_buffer, in_buffer_full)) < 0) {
 517
 518                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 519                                                 master_writable = false;
 520                                         else {
 521                                                 log_error("write(): %m");
 522                                                 r = -errno;
 523                                                 goto finish;
 524                                         }
 525
 526                                 } else {
 527                                         assert(in_buffer_full >= (size_t) k);
 528                                         memmove(in_buffer, in_buffer + k, in_buffer_full - k);
 529                                         in_buffer_full -= k;
 530                                 }
 531                         }
 532
 533                         if (master_readable && out_buffer_full < BUFFER_SIZE) {
 534
 535                                 if ((k = read(master, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) {
 536
 537                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 538                                                 master_readable = false;
 539                                         else {
 540                                                 log_error("read(): %m");
 541                                                 r = -errno;
 542                                                 goto finish;
 543                                         }
 544                                 }  else
 545                                         out_buffer_full += (size_t) k;
 546                         }
 547
 548                         if (stdout_writable && out_buffer_full > 0) {
 549
 550                                 if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) {
 551
 552                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 553                                                 stdout_writable = false;
 554                                         else {
 555                                                 log_error("write(): %m");
 556                                                 r = -errno;
 557                                                 goto finish;
 558                                         }
 559
 560                                 } else {
 561                                         assert(out_buffer_full >= (size_t) k);
 562                                         memmove(out_buffer, out_buffer + k, out_buffer_full - k);
 563                                         out_buffer_full -= k;
 564                                 }
 565                         }
 566                 }
 567         }
 568
 569 finish:
 570         if (ep >= 0)
 571                 close_nointr_nofail(ep);
 572
 573         if (signal_fd >= 0)
 574                 close_nointr_nofail(signal_fd);
 575
 576         return r;
 577 }
 578
 579 int main(int argc, char *argv[]) {
 580         pid_t pid = 0;
 581         int r = EXIT_FAILURE, k;
 582         char *oldcg = NULL, *newcg = NULL;
 583         int master = -1;
 584         const char *console = NULL;
 585         struct termios saved_attr, raw_attr;
 586         sigset_t mask;
 587         bool saved_attr_valid = false;
 588         struct winsize ws;
 589
 590         log_parse_environment();
 591         log_open();
 592
 593         if ((r = parse_argv(argc, argv)) <= 0)
 594                 goto finish;
 595
 596         if (arg_directory) {
 597                 char *p;
 598
 599                 p = path_make_absolute_cwd(arg_directory);
 600                 free(arg_directory);
 601                 arg_directory = p;
 602         } else
 603                 arg_directory = get_current_dir_name();
 604
 605         if (!arg_directory) {
 606                 log_error("Failed to determine path");
 607                 goto finish;
 608         }
 609
 610         path_kill_slashes(arg_directory);
 611
 612         if (geteuid() != 0) {
 613                 log_error("Need to be root.");
 614                 goto finish;
 615         }
 616
 617         if (sd_booted() <= 0) {
 618                 log_error("Not running on a systemd system.");
 619                 goto finish;
 620         }
 621
 622         if (path_equal(arg_directory, "/")) {
 623                 log_error("Spawning container on root directory not supported.");
 624                 goto finish;
 625         }
 626
 627         if (is_os_tree(arg_directory) <= 0) {
 628                 log_error("Directory %s doesn't look like an OS root directory. Refusing.", arg_directory);
 629                 goto finish;
 630         }
 631
 632         if ((k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg)) < 0) {
 633                 log_error("Failed to determine current cgroup: %s", strerror(-k));
 634                 goto finish;
 635         }
 636
 637         if (asprintf(&newcg, "%s/nspawn-%lu", oldcg, (unsigned long) getpid()) < 0) {
 638                 log_error("Failed to allocate cgroup path.");
 639                 goto finish;
 640         }
 641
 642         if ((k = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, newcg, 0)) < 0)  {
 643                 log_error("Failed to create cgroup: %s", strerror(-k));
 644                 goto finish;
 645         }
 646
 647         if ((master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY)) < 0) {
 648                 log_error("Failed to acquire pseudo tty: %m");
 649                 goto finish;
 650         }
 651
 652         if (!(console = ptsname(master))) {
 653                 log_error("Failed to determine tty name: %m");
 654                 goto finish;
 655         }
 656
 657         log_info("Spawning namespace container on %s (console is %s).", arg_directory, console);
 658
 659         if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
 660                 ioctl(master, TIOCSWINSZ, &ws);
 661
 662         if (unlockpt(master) < 0) {
 663                 log_error("Failed to unlock tty: %m");
 664                 goto finish;
 665         }
 666
 667         if (tcgetattr(STDIN_FILENO, &saved_attr) < 0) {
 668                 log_error("Failed to get terminal attributes: %m");
 669                 goto finish;
 670         }
 671
 672         saved_attr_valid = true;
 673
 674         raw_attr = saved_attr;
 675         cfmakeraw(&raw_attr);
 676         raw_attr.c_lflag &= ~ECHO;
 677
 678         if (tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr) < 0) {
 679                 log_error("Failed to set terminal attributes: %m");
 680                 goto finish;
 681         }
 682
 683         assert_se(sigemptyset(&mask) == 0);
 684         sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
 685         assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
 686
 687         if ((pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS, NULL)) < 0) {
 688                 log_error("clone() failed: %m");
 689                 goto finish;
 690         }
 691
 692         if (pid == 0) {
 693                 /* child */
 694
 695                 const char *hn;
 696                 const char *envp[] = {
 697                         "HOME=/root",
 698                         "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
 699                         NULL,
 700                         NULL
 701                 };
 702
 703                 envp[2] = strv_find_prefix(environ, "TERM=");
 704
 705                 close_nointr_nofail(master);
 706
 707                 close_nointr(STDIN_FILENO);
 708                 close_nointr(STDOUT_FILENO);
 709                 close_nointr(STDERR_FILENO);
 710
 711                 close_all_fds(NULL, 0);
 712
 713                 reset_all_signal_handlers();
 714
 715                 assert_se(sigemptyset(&mask) == 0);
 716                 assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 717
 718                 if (setsid() < 0)
 719                         goto child_fail;
 720
 721                 if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
 722                         goto child_fail;
 723
 724                 if (mount_all(arg_directory) < 0)
 725                         goto child_fail;
 726
 727                 if (copy_devnodes(arg_directory, console) < 0)
 728                         goto child_fail;
 729
 730                 if (chdir(arg_directory) < 0) {
 731                         log_error("chdir(%s) failed: %m", arg_directory);
 732                         goto child_fail;
 733                 }
 734
 735                 if (open_terminal("dev/console", O_RDWR) != STDIN_FILENO ||
 736                     dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO ||
 737                     dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO)
 738                         goto child_fail;
 739
 740                 if (mount(arg_directory, "/", "bind", MS_BIND|MS_MOVE, NULL) < 0) {
 741                         log_error("mount(MS_MOVE) failed: %m");
 742                         goto child_fail;
 743                 }
 744
 745                 if (chroot(".") < 0) {
 746                         log_error("chroot() failed: %m");
 747                         goto child_fail;
 748                 }
 749
 750                 if (chdir("/") < 0) {
 751                         log_error("chdir() failed: %m");
 752                         goto child_fail;
 753                 }
 754
 755                 umask(0002);
 756
 757                 if (drop_capabilities() < 0)
 758                         goto child_fail;
 759
 760                 if ((hn = file_name_from_path(arg_directory)))
 761                         sethostname(hn, strlen(hn));
 762
 763                 if (argc > optind)
 764                         execvpe(argv[optind], argv + optind, (char**) envp);
 765                 else {
 766                         chdir("/root");
 767                         execle("/bin/bash", "-bash", NULL, (char**) envp);
 768                 }
 769
 770                 log_error("execv() failed: %m");
 771
 772         child_fail:
 773                 _exit(EXIT_FAILURE);
 774         }
 775
 776         if (process_pty(master, &mask) < 0)
 777                 goto finish;
 778
 779         if (saved_attr_valid) {
 780                 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
 781                 saved_attr_valid = false;
 782         }
 783
 784         r = wait_for_terminate_and_warn(argc > optind ? argv[optind] : "bash", pid);
 785
 786         if (r < 0)
 787                 r = EXIT_FAILURE;
 788
 789 finish:
 790         if (saved_attr_valid)
 791                 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
 792
 793         if (master >= 0)
 794                 close_nointr_nofail(master);
 795
 796         if (oldcg)
 797                 cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);
 798
 799         if (newcg)
 800                 cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, newcg, true);
 801
 802         free(arg_directory);
 803         free(oldcg);
 804         free(newcg);
 805
 806         return r;
 807 }