src/nspawn/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 Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 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   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser 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 #include <grp.h>
  40 #include <linux/fs.h>
  41 #include <sys/un.h>
  42 #include <sys/socket.h>
  43
  44 #include <systemd/sd-daemon.h>
  45
  46 #include "log.h"
  47 #include "util.h"
  48 #include "mkdir.h"
  49 #include "audit.h"
  50 #include "missing.h"
  51 #include "cgroup-util.h"
  52 #include "strv.h"
  53 #include "path-util.h"
  54 #include "loopback-setup.h"
  55
  56 static char *arg_directory = NULL;
  57 static char *arg_user = NULL;
  58 static char **arg_controllers = NULL;
  59 static char *arg_uuid = NULL;
  60 static bool arg_private_network = false;
  61 static bool arg_read_only = false;
  62 static bool arg_boot = false;
  63
  64 static int help(void) {
  65
  66         printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n"
  67                "Spawn a minimal namespace container for debugging, testing and building.\n\n"
  68                "  -h --help             Show this help\n"
  69                "  -D --directory=NAME   Root directory for the container\n"
  70                "  -b --boot             Boot up full system (i.e. invoke init)\n"
  71                "  -u --user=USER        Run the command under specified user or uid\n"
  72                "  -C --controllers=LIST Put the container in specified comma-separated cgroup hierarchies\n"
  73                "     --uuid=UUID        Set a specific machine UUID for the container\n"
  74                "     --private-network  Disable network in container\n"
  75                "     --read-only        Mount the root directory read-only\n",
  76                program_invocation_short_name);
  77
  78         return 0;
  79 }
  80
  81 static int parse_argv(int argc, char *argv[]) {
  82
  83         enum {
  84                 ARG_PRIVATE_NETWORK = 0x100,
  85                 ARG_UUID,
  86                 ARG_READ_ONLY
  87         };
  88
  89         static const struct option options[] = {
  90                 { "help",            no_argument,       NULL, 'h'                 },
  91                 { "directory",       required_argument, NULL, 'D'                 },
  92                 { "user",            required_argument, NULL, 'u'                 },
  93                 { "controllers",     required_argument, NULL, 'C'                 },
  94                 { "private-network", no_argument,       NULL, ARG_PRIVATE_NETWORK },
  95                 { "boot",            no_argument,       NULL, 'b'                 },
  96                 { "uuid",            required_argument, NULL, ARG_UUID            },
  97                 { "read-only",       no_argument,       NULL, ARG_READ_ONLY       },
  98                 { NULL,              0,                 NULL, 0                   }
  99         };
 100
 101         int c;
 102
 103         assert(argc >= 0);
 104         assert(argv);
 105
 106         while ((c = getopt_long(argc, argv, "+hD:u:C:b", options, NULL)) >= 0) {
 107
 108                 switch (c) {
 109
 110                 case 'h':
 111                         help();
 112                         return 0;
 113
 114                 case 'D':
 115                         free(arg_directory);
 116                         arg_directory = canonicalize_file_name(optarg);
 117                         if (!arg_directory) {
 118                                 log_error("Failed to canonicalize root directory.");
 119                                 return -ENOMEM;
 120                         }
 121
 122                         break;
 123
 124                 case 'u':
 125                         free(arg_user);
 126                         if (!(arg_user = strdup(optarg))) {
 127                                 log_error("Failed to duplicate user name.");
 128                                 return -ENOMEM;
 129                         }
 130
 131                         break;
 132
 133                 case 'C':
 134                         strv_free(arg_controllers);
 135                         arg_controllers = strv_split(optarg, ",");
 136                         if (!arg_controllers) {
 137                                 log_error("Failed to split controllers list.");
 138                                 return -ENOMEM;
 139                         }
 140                         strv_uniq(arg_controllers);
 141
 142                         break;
 143
 144                 case ARG_PRIVATE_NETWORK:
 145                         arg_private_network = true;
 146                         break;
 147
 148                 case 'b':
 149                         arg_boot = true;
 150                         break;
 151
 152                 case ARG_UUID:
 153                         arg_uuid = optarg;
 154                         break;
 155
 156                 case ARG_READ_ONLY:
 157                         arg_read_only = true;
 158                         break;
 159
 160                 case '?':
 161                         return -EINVAL;
 162
 163                 default:
 164                         log_error("Unknown option code %c", c);
 165                         return -EINVAL;
 166                 }
 167         }
 168
 169         return 1;
 170 }
 171
 172 static int mount_all(const char *dest) {
 173
 174         typedef struct MountPoint {
 175                 const char *what;
 176                 const char *where;
 177                 const char *type;
 178                 const char *options;
 179                 unsigned long flags;
 180                 bool fatal;
 181         } MountPoint;
 182
 183         static const MountPoint mount_table[] = {
 184                 { "proc",      "/proc",     "proc",  NULL,       MS_NOSUID|MS_NOEXEC|MS_NODEV, true  },
 185                 { "/proc/sys", "/proc/sys", "bind",  NULL,       MS_BIND, true                       },   /* Bind mount first */
 186                 { "/proc/sys", "/proc/sys", "bind",  NULL,       MS_BIND|MS_RDONLY|MS_REMOUNT, true  },   /* Then, make it r/o */
 187                 { "/sys",      "/sys",      "bind",  NULL,       MS_BIND,                      true  },   /* Bind mount first */
 188                 { "/sys",      "/sys",      "bind",  NULL,       MS_BIND|MS_RDONLY|MS_REMOUNT, true  },   /* Then, make it r/o */
 189                 { "tmpfs",     "/dev",      "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME,     true  },
 190                 { "/dev/pts",  "/dev/pts",  "bind",  NULL,       MS_BIND,                      true  },
 191                 { "tmpfs",     "/run",      "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true  },
 192 #ifdef HAVE_SELINUX
 193                 { "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND,                      false },  /* Bind mount first */
 194                 { "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false },  /* Then, make it r/o */
 195 #endif
 196         };
 197
 198         unsigned k;
 199         int r = 0;
 200         char *where;
 201
 202         for (k = 0; k < ELEMENTSOF(mount_table); k++) {
 203                 int t;
 204
 205                 if (asprintf(&where, "%s/%s", dest, mount_table[k].where) < 0) {
 206                         log_error("Out of memory");
 207
 208                         if (r == 0)
 209                                 r = -ENOMEM;
 210
 211                         break;
 212                 }
 213
 214                 t = path_is_mount_point(where, false);
 215                 if (t < 0) {
 216                         log_error("Failed to detect whether %s is a mount point: %s", where, strerror(-t));
 217                         free(where);
 218
 219                         if (r == 0)
 220                                 r = t;
 221
 222                         continue;
 223                 }
 224
 225                 mkdir_p(where, 0755);
 226
 227                 if (mount(mount_table[k].what,
 228                           where,
 229                           mount_table[k].type,
 230                           mount_table[k].flags,
 231                           mount_table[k].options) < 0 &&
 232                     mount_table[k].fatal) {
 233
 234                         log_error("mount(%s) failed: %m", where);
 235
 236                         if (r == 0)
 237                                 r = -errno;
 238                 }
 239
 240                 free(where);
 241         }
 242
 243         return r;
 244 }
 245
 246 static int setup_timezone(const char *dest) {
 247         char *where;
 248
 249         assert(dest);
 250
 251         /* Fix the timezone, if possible */
 252         if (asprintf(&where, "%s/etc/localtime", dest) < 0) {
 253                 log_error("Out of memory");
 254                 return -ENOMEM;
 255         }
 256
 257         if (mount("/etc/localtime", where, "bind", MS_BIND, NULL) >= 0)
 258                 mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
 259
 260         free(where);
 261
 262         if (asprintf(&where, "%s/etc/timezone", dest) < 0) {
 263                 log_error("Out of memory");
 264                 return -ENOMEM;
 265         }
 266
 267         if (mount("/etc/timezone", where, "bind", MS_BIND, NULL) >= 0)
 268                 mount("/etc/timezone", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
 269
 270         free(where);
 271
 272         return 0;
 273 }
 274
 275 static int setup_resolv_conf(const char *dest) {
 276         char *where;
 277
 278         assert(dest);
 279
 280         if (arg_private_network)
 281                 return 0;
 282
 283         /* Fix resolv.conf, if possible */
 284         if (asprintf(&where, "%s/etc/resolv.conf", dest) < 0) {
 285                 log_error("Out of memory");
 286                 return -ENOMEM;
 287         }
 288
 289         if (mount("/etc/resolv.conf", where, "bind", MS_BIND, NULL) >= 0)
 290                 mount("/etc/resolv.conf", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
 291
 292         free(where);
 293
 294         return 0;
 295 }
 296
 297 static int copy_devnodes(const char *dest) {
 298
 299         static const char devnodes[] =
 300                 "null\0"
 301                 "zero\0"
 302                 "full\0"
 303                 "random\0"
 304                 "urandom\0"
 305                 "tty\0"
 306                 "ptmx\0"
 307                 "rtc0\0";
 308
 309         const char *d;
 310         int r = 0;
 311         mode_t u;
 312
 313         assert(dest);
 314
 315         u = umask(0000);
 316
 317         NULSTR_FOREACH(d, devnodes) {
 318                 struct stat st;
 319                 char *from = NULL, *to = NULL;
 320
 321                 asprintf(&from, "/dev/%s", d);
 322                 asprintf(&to, "%s/dev/%s", dest, d);
 323
 324                 if (!from || !to) {
 325                         log_error("Failed to allocate devnode path");
 326
 327                         free(from);
 328                         free(to);
 329
 330                         from = to = NULL;
 331
 332                         if (r == 0)
 333                                 r = -ENOMEM;
 334
 335                         break;
 336                 }
 337
 338                 if (stat(from, &st) < 0) {
 339
 340                         if (errno != ENOENT) {
 341                                 log_error("Failed to stat %s: %m", from);
 342                                 if (r == 0)
 343                                         r = -errno;
 344                         }
 345
 346                 } else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {
 347
 348                         log_error("%s is not a char or block device, cannot copy.", from);
 349                         if (r == 0)
 350                                 r = -EIO;
 351
 352                 } else if (mknod(to, st.st_mode, st.st_rdev) < 0) {
 353
 354                         log_error("mknod(%s) failed: %m", dest);
 355                         if (r == 0)
 356                                 r = -errno;
 357                 }
 358
 359                 free(from);
 360                 free(to);
 361         }
 362
 363         umask(u);
 364
 365         return r;
 366 }
 367
 368 static int setup_dev_console(const char *dest, const char *console) {
 369         struct stat st;
 370         char *to = NULL;
 371         int r;
 372         mode_t u;
 373
 374         assert(dest);
 375         assert(console);
 376
 377         u = umask(0000);
 378
 379         if (stat(console, &st) < 0) {
 380                 log_error("Failed to stat %s: %m", console);
 381                 r = -errno;
 382                 goto finish;
 383
 384         } else if (!S_ISCHR(st.st_mode)) {
 385                 log_error("/dev/console is not a char device.");
 386                 r = -EIO;
 387                 goto finish;
 388         }
 389
 390         r = chmod_and_chown(console, 0600, 0, 0);
 391         if (r < 0) {
 392                 log_error("Failed to correct access mode for TTY: %s", strerror(-r));
 393                 goto finish;
 394         }
 395
 396         if (asprintf(&to, "%s/dev/console", dest) < 0) {
 397                 log_error("Out of memory");
 398                 r = -ENOMEM;
 399                 goto finish;
 400         }
 401
 402         /* We need to bind mount the right tty to /dev/console since
 403          * ptys can only exist on pts file systems. To have something
 404          * to bind mount things on we create a device node first, that
 405          * has the right major/minor (note that the major minor
 406          * doesn't actually matter here, since we mount it over
 407          * anyway). */
 408
 409         if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) {
 410                 log_error("mknod() for /dev/console failed: %m");
 411                 r = -errno;
 412                 goto finish;
 413         }
 414
 415         if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
 416                 log_error("Bind mount for /dev/console failed: %m");
 417                 r = -errno;
 418                 goto finish;
 419         }
 420
 421 finish:
 422         free(to);
 423         umask(u);
 424
 425         return r;
 426 }
 427
 428 static int setup_kmsg(const char *dest, int kmsg_socket) {
 429         char *from = NULL, *to = NULL;
 430         int r, fd, k;
 431         mode_t u;
 432         union {
 433                 struct cmsghdr cmsghdr;
 434                 uint8_t buf[CMSG_SPACE(sizeof(int))];
 435         } control;
 436         struct msghdr mh;
 437         struct cmsghdr *cmsg;
 438
 439         assert(dest);
 440         assert(kmsg_socket >= 0);
 441
 442         u = umask(0000);
 443
 444         /* We create the kmsg FIFO as /dev/kmsg, but immediately
 445          * delete it after bind mounting it to /proc/kmsg. While FIFOs
 446          * on the reading side behave very similar to /proc/kmsg,
 447          * their writing side behaves differently from /dev/kmsg in
 448          * that writing blocks when nothing is reading. In order to
 449          * avoid any problems with containers deadlocking due to this
 450          * we simply make /dev/kmsg unavailable to the container. */
 451         if (asprintf(&from, "%s/dev/kmsg", dest) < 0) {
 452                 log_error("Out of memory");
 453                 r = -ENOMEM;
 454                 goto finish;
 455         }
 456
 457         if (asprintf(&to, "%s/proc/kmsg", dest) < 0) {
 458                 log_error("Out of memory");
 459                 r = -ENOMEM;
 460                 goto finish;
 461         }
 462
 463         if (mkfifo(from, 0600) < 0) {
 464                 log_error("mkfifo() for /dev/kmsg failed: %m");
 465                 r = -errno;
 466                 goto finish;
 467         }
 468
 469         r = chmod_and_chown(from, 0600, 0, 0);
 470         if (r < 0) {
 471                 log_error("Failed to correct access mode for /dev/kmsg: %s", strerror(-r));
 472                 goto finish;
 473         }
 474
 475         if (mount(from, to, "bind", MS_BIND, NULL) < 0) {
 476                 log_error("Bind mount for /proc/kmsg failed: %m");
 477                 r = -errno;
 478                 goto finish;
 479         }
 480
 481         fd = open(from, O_RDWR|O_NDELAY|O_CLOEXEC);
 482         if (fd < 0) {
 483                 log_error("Failed to open fifo: %m");
 484                 r = -errno;
 485                 goto finish;
 486         }
 487
 488         zero(mh);
 489         zero(control);
 490
 491         mh.msg_control = &control;
 492         mh.msg_controllen = sizeof(control);
 493
 494         cmsg = CMSG_FIRSTHDR(&mh);
 495         cmsg->cmsg_level = SOL_SOCKET;
 496         cmsg->cmsg_type = SCM_RIGHTS;
 497         cmsg->cmsg_len = CMSG_LEN(sizeof(int));
 498         memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
 499
 500         mh.msg_controllen = cmsg->cmsg_len;
 501
 502         /* Store away the fd in the socket, so that it stays open as
 503          * long as we run the child */
 504         k = sendmsg(kmsg_socket, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
 505         close_nointr_nofail(fd);
 506
 507         if (k < 0) {
 508                 log_error("Failed to send FIFO fd: %m");
 509                 r = -errno;
 510                 goto finish;
 511         }
 512
 513         /* And now make the FIFO unavailable as /dev/kmsg... */
 514         unlink(from);
 515
 516 finish:
 517         free(from);
 518         free(to);
 519         umask(u);
 520
 521         return r;
 522 }
 523
 524 static int setup_hostname(void) {
 525         char *hn;
 526         int r = 0;
 527
 528         hn = path_get_file_name(arg_directory);
 529         if (hn) {
 530                 hn = strdup(hn);
 531                 if (!hn)
 532                         return -ENOMEM;
 533
 534                 hostname_cleanup(hn);
 535
 536                 if (!isempty(hn))
 537                         if (sethostname(hn, strlen(hn)) < 0)
 538                                 r = -errno;
 539
 540                 free(hn);
 541         }
 542
 543         return r;
 544 }
 545
 546 static int drop_capabilities(void) {
 547
 548         static const uint64_t retain =
 549                 (1ULL << CAP_CHOWN) |
 550                 (1ULL << CAP_DAC_OVERRIDE) |
 551                 (1ULL << CAP_DAC_READ_SEARCH) |
 552                 (1ULL << CAP_FOWNER) |
 553                 (1ULL << CAP_FSETID) |
 554                 (1ULL << CAP_IPC_OWNER) |
 555                 (1ULL << CAP_KILL) |
 556                 (1ULL << CAP_LEASE) |
 557                 (1ULL << CAP_LINUX_IMMUTABLE) |
 558                 (1ULL << CAP_NET_BIND_SERVICE) |
 559                 (1ULL << CAP_NET_BROADCAST) |
 560                 (1ULL << CAP_NET_RAW) |
 561                 (1ULL << CAP_SETGID) |
 562                 (1ULL << CAP_SETFCAP) |
 563                 (1ULL << CAP_SETPCAP) |
 564                 (1ULL << CAP_SETUID) |
 565                 (1ULL << CAP_SYS_ADMIN) |
 566                 (1ULL << CAP_SYS_CHROOT) |
 567                 (1ULL << CAP_SYS_NICE) |
 568                 (1ULL << CAP_SYS_PTRACE) |
 569                 (1ULL << CAP_SYS_TTY_CONFIG);
 570
 571         return capability_bounding_set_drop(~retain, false);
 572 }
 573
 574 static int is_os_tree(const char *path) {
 575         int r;
 576         char *p;
 577         /* We use /bin/sh as flag file if something is an OS */
 578
 579         if (asprintf(&p, "%s/bin/sh", path) < 0)
 580                 return -ENOMEM;
 581
 582         r = access(p, F_OK);
 583         free(p);
 584
 585         return r < 0 ? 0 : 1;
 586 }
 587
 588 static int process_pty(int master, sigset_t *mask) {
 589
 590         char in_buffer[LINE_MAX], out_buffer[LINE_MAX];
 591         size_t in_buffer_full = 0, out_buffer_full = 0;
 592         struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev;
 593         bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false;
 594         int ep = -1, signal_fd = -1, r;
 595
 596         fd_nonblock(STDIN_FILENO, 1);
 597         fd_nonblock(STDOUT_FILENO, 1);
 598         fd_nonblock(master, 1);
 599
 600         if ((signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 601                 log_error("signalfd(): %m");
 602                 r = -errno;
 603                 goto finish;
 604         }
 605
 606         if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) {
 607                 log_error("Failed to create epoll: %m");
 608                 r = -errno;
 609                 goto finish;
 610         }
 611
 612         zero(stdin_ev);
 613         stdin_ev.events = EPOLLIN|EPOLLET;
 614         stdin_ev.data.fd = STDIN_FILENO;
 615
 616         zero(stdout_ev);
 617         stdout_ev.events = EPOLLOUT|EPOLLET;
 618         stdout_ev.data.fd = STDOUT_FILENO;
 619
 620         zero(master_ev);
 621         master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
 622         master_ev.data.fd = master;
 623
 624         zero(signal_ev);
 625         signal_ev.events = EPOLLIN;
 626         signal_ev.data.fd = signal_fd;
 627
 628         if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 ||
 629             epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 ||
 630             epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 ||
 631             epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) {
 632                 log_error("Failed to regiser fds in epoll: %m");
 633                 r = -errno;
 634                 goto finish;
 635         }
 636
 637         for (;;) {
 638                 struct epoll_event ev[16];
 639                 ssize_t k;
 640                 int i, nfds;
 641
 642                 if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) {
 643
 644                         if (errno == EINTR || errno == EAGAIN)
 645                                 continue;
 646
 647                         log_error("epoll_wait(): %m");
 648                         r = -errno;
 649                         goto finish;
 650                 }
 651
 652                 assert(nfds >= 1);
 653
 654                 for (i = 0; i < nfds; i++) {
 655                         if (ev[i].data.fd == STDIN_FILENO) {
 656
 657                                 if (ev[i].events & (EPOLLIN|EPOLLHUP))
 658                                         stdin_readable = true;
 659
 660                         } else if (ev[i].data.fd == STDOUT_FILENO) {
 661
 662                                 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
 663                                         stdout_writable = true;
 664
 665                         } else if (ev[i].data.fd == master) {
 666
 667                                 if (ev[i].events & (EPOLLIN|EPOLLHUP))
 668                                         master_readable = true;
 669
 670                                 if (ev[i].events & (EPOLLOUT|EPOLLHUP))
 671                                         master_writable = true;
 672
 673                         } else if (ev[i].data.fd == signal_fd) {
 674                                 struct signalfd_siginfo sfsi;
 675                                 ssize_t n;
 676
 677                                 if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
 678
 679                                         if (n >= 0) {
 680                                                 log_error("Failed to read from signalfd: invalid block size");
 681                                                 r = -EIO;
 682                                                 goto finish;
 683                                         }
 684
 685                                         if (errno != EINTR && errno != EAGAIN) {
 686                                                 log_error("Failed to read from signalfd: %m");
 687                                                 r = -errno;
 688                                                 goto finish;
 689                                         }
 690                                 } else {
 691
 692                                         if (sfsi.ssi_signo == SIGWINCH) {
 693                                                 struct winsize ws;
 694
 695                                                 /* The window size changed, let's forward that. */
 696                                                 if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
 697                                                         ioctl(master, TIOCSWINSZ, &ws);
 698                                         } else {
 699                                                 r = 0;
 700                                                 goto finish;
 701                                         }
 702                                 }
 703                         }
 704                 }
 705
 706                 while ((stdin_readable && in_buffer_full <= 0) ||
 707                        (master_writable && in_buffer_full > 0) ||
 708                        (master_readable && out_buffer_full <= 0) ||
 709                        (stdout_writable && out_buffer_full > 0)) {
 710
 711                         if (stdin_readable && in_buffer_full < LINE_MAX) {
 712
 713                                 if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, LINE_MAX - in_buffer_full)) < 0) {
 714
 715                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 716                                                 stdin_readable = false;
 717                                         else {
 718                                                 log_error("read(): %m");
 719                                                 r = -errno;
 720                                                 goto finish;
 721                                         }
 722                                 } else
 723                                         in_buffer_full += (size_t) k;
 724                         }
 725
 726                         if (master_writable && in_buffer_full > 0) {
 727
 728                                 if ((k = write(master, in_buffer, in_buffer_full)) < 0) {
 729
 730                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 731                                                 master_writable = false;
 732                                         else {
 733                                                 log_error("write(): %m");
 734                                                 r = -errno;
 735                                                 goto finish;
 736                                         }
 737
 738                                 } else {
 739                                         assert(in_buffer_full >= (size_t) k);
 740                                         memmove(in_buffer, in_buffer + k, in_buffer_full - k);
 741                                         in_buffer_full -= k;
 742                                 }
 743                         }
 744
 745                         if (master_readable && out_buffer_full < LINE_MAX) {
 746
 747                                 if ((k = read(master, out_buffer + out_buffer_full, LINE_MAX - out_buffer_full)) < 0) {
 748
 749                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 750                                                 master_readable = false;
 751                                         else {
 752                                                 log_error("read(): %m");
 753                                                 r = -errno;
 754                                                 goto finish;
 755                                         }
 756                                 }  else
 757                                         out_buffer_full += (size_t) k;
 758                         }
 759
 760                         if (stdout_writable && out_buffer_full > 0) {
 761
 762                                 if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) {
 763
 764                                         if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
 765                                                 stdout_writable = false;
 766                                         else {
 767                                                 log_error("write(): %m");
 768                                                 r = -errno;
 769                                                 goto finish;
 770                                         }
 771
 772                                 } else {
 773                                         assert(out_buffer_full >= (size_t) k);
 774                                         memmove(out_buffer, out_buffer + k, out_buffer_full - k);
 775                                         out_buffer_full -= k;
 776                                 }
 777                         }
 778                 }
 779         }
 780
 781 finish:
 782         if (ep >= 0)
 783                 close_nointr_nofail(ep);
 784
 785         if (signal_fd >= 0)
 786                 close_nointr_nofail(signal_fd);
 787
 788         return r;
 789 }
 790
 791 int main(int argc, char *argv[]) {
 792         pid_t pid = 0;
 793         int r = EXIT_FAILURE, k;
 794         char *oldcg = NULL, *newcg = NULL;
 795         char **controller = NULL;
 796         int master = -1;
 797         const char *console = NULL;
 798         struct termios saved_attr, raw_attr;
 799         sigset_t mask;
 800         bool saved_attr_valid = false;
 801         struct winsize ws;
 802         int kmsg_socket_pair[2] = { -1, -1 };
 803
 804         log_parse_environment();
 805         log_open();
 806
 807         if ((r = parse_argv(argc, argv)) <= 0)
 808                 goto finish;
 809
 810         if (arg_directory) {
 811                 char *p;
 812
 813                 p = path_make_absolute_cwd(arg_directory);
 814                 free(arg_directory);
 815                 arg_directory = p;
 816         } else
 817                 arg_directory = get_current_dir_name();
 818
 819         if (!arg_directory) {
 820                 log_error("Failed to determine path");
 821                 goto finish;
 822         }
 823
 824         path_kill_slashes(arg_directory);
 825
 826         if (geteuid() != 0) {
 827                 log_error("Need to be root.");
 828                 goto finish;
 829         }
 830
 831         if (sd_booted() <= 0) {
 832                 log_error("Not running on a systemd system.");
 833                 goto finish;
 834         }
 835
 836         if (path_equal(arg_directory, "/")) {
 837                 log_error("Spawning container on root directory not supported.");
 838                 goto finish;
 839         }
 840
 841         if (is_os_tree(arg_directory) <= 0) {
 842                 log_error("Directory %s doesn't look like an OS root directory. Refusing.", arg_directory);
 843                 goto finish;
 844         }
 845
 846         if ((k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg)) < 0) {
 847                 log_error("Failed to determine current cgroup: %s", strerror(-k));
 848                 goto finish;
 849         }
 850
 851         if (asprintf(&newcg, "%s/nspawn-%lu", oldcg, (unsigned long) getpid()) < 0) {
 852                 log_error("Failed to allocate cgroup path.");
 853                 goto finish;
 854         }
 855
 856         k = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, newcg, 0);
 857         if (k < 0)  {
 858                 log_error("Failed to create cgroup: %s", strerror(-k));
 859                 goto finish;
 860         }
 861
 862         STRV_FOREACH(controller,arg_controllers) {
 863                 k = cg_create_and_attach(*controller, newcg, 0);
 864                 if (k < 0)
 865                         log_warning("Failed to create cgroup in controller %s: %s", *controller, strerror(-k));
 866         }
 867
 868         if ((master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY)) < 0) {
 869                 log_error("Failed to acquire pseudo tty: %m");
 870                 goto finish;
 871         }
 872
 873         if (!(console = ptsname(master))) {
 874                 log_error("Failed to determine tty name: %m");
 875                 goto finish;
 876         }
 877
 878         log_info("Spawning namespace container on %s (console is %s).", arg_directory, console);
 879
 880         if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
 881                 ioctl(master, TIOCSWINSZ, &ws);
 882
 883         if (unlockpt(master) < 0) {
 884                 log_error("Failed to unlock tty: %m");
 885                 goto finish;
 886         }
 887
 888         if (tcgetattr(STDIN_FILENO, &saved_attr) < 0) {
 889                 log_error("Failed to get terminal attributes: %m");
 890                 goto finish;
 891         }
 892
 893         saved_attr_valid = true;
 894
 895         raw_attr = saved_attr;
 896         cfmakeraw(&raw_attr);
 897         raw_attr.c_lflag &= ~ECHO;
 898
 899         if (tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr) < 0) {
 900                 log_error("Failed to set terminal attributes: %m");
 901                 goto finish;
 902         }
 903
 904         if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, kmsg_socket_pair) < 0) {
 905                 log_error("Failed to create kmsg socket pair");
 906                 goto finish;
 907         }
 908
 909         assert_se(sigemptyset(&mask) == 0);
 910         sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
 911         assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
 912
 913         pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS|(arg_private_network ? CLONE_NEWNET : 0), NULL);
 914         if (pid < 0) {
 915                 if (errno == EINVAL)
 916                         log_error("clone() failed, do you have namespace support enabled in your kernel? (You need UTS, IPC, PID and NET namespacing built in): %m");
 917                 else
 918                         log_error("clone() failed: %m");
 919
 920                 goto finish;
 921         }
 922
 923         if (pid == 0) {
 924                 /* child */
 925
 926                 const char *home = NULL;
 927                 uid_t uid = (uid_t) -1;
 928                 gid_t gid = (gid_t) -1;
 929                 const char *envp[] = {
 930                         "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
 931                         "container=systemd-nspawn", /* LXC sets container=lxc, so follow the scheme here */
 932                         NULL, /* TERM */
 933                         NULL, /* HOME */
 934                         NULL, /* USER */
 935                         NULL, /* LOGNAME */
 936                         NULL, /* container_uuid */
 937                         NULL
 938                 };
 939
 940                 envp[2] = strv_find_prefix(environ, "TERM=");
 941
 942                 close_nointr_nofail(master);
 943
 944                 close_nointr(STDIN_FILENO);
 945                 close_nointr(STDOUT_FILENO);
 946                 close_nointr(STDERR_FILENO);
 947
 948                 close_all_fds(&kmsg_socket_pair[1], 1);
 949
 950                 reset_all_signal_handlers();
 951
 952                 assert_se(sigemptyset(&mask) == 0);
 953                 assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 954
 955                 if (setsid() < 0)
 956                         goto child_fail;
 957
 958                 if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
 959                         goto child_fail;
 960
 961                 /* Mark / as private, in case somebody marked it shared */
 962                 if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0)
 963                         goto child_fail;
 964
 965                 /* Turn directory into bind mount */
 966                 if (mount(arg_directory, arg_directory, "bind", MS_BIND, NULL) < 0) {
 967                         log_error("Failed to make bind mount.");
 968                         goto child_fail;
 969                 }
 970
 971                 if (arg_read_only)
 972                         if (mount(arg_directory, arg_directory, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
 973                                 log_error("Failed to make read-only.");
 974                                 goto child_fail;
 975                         }
 976
 977                 if (mount_all(arg_directory) < 0)
 978                         goto child_fail;
 979
 980                 if (copy_devnodes(arg_directory) < 0)
 981                         goto child_fail;
 982
 983                 if (setup_dev_console(arg_directory, console) < 0)
 984                         goto child_fail;
 985
 986                 if (setup_kmsg(arg_directory, kmsg_socket_pair[1]) < 0)
 987                         goto child_fail;
 988
 989                 close_nointr_nofail(kmsg_socket_pair[1]);
 990
 991                 if (setup_timezone(arg_directory) < 0)
 992                         goto child_fail;
 993
 994                 if (setup_resolv_conf(arg_directory) < 0)
 995                         goto child_fail;
 996
 997                 if (chdir(arg_directory) < 0) {
 998                         log_error("chdir(%s) failed: %m", arg_directory);
 999                         goto child_fail;
1000                 }
1001
1002                 if (open_terminal("dev/console", O_RDWR) != STDIN_FILENO ||
1003                     dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO ||
1004                     dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO)
1005                         goto child_fail;
1006
1007                 if (mount(arg_directory, "/", "bind", MS_MOVE, NULL) < 0) {
1008                         log_error("mount(MS_BIND) failed: %m");
1009                         goto child_fail;
1010                 }
1011
1012                 if (chroot(".") < 0) {
1013                         log_error("chroot() failed: %m");
1014                         goto child_fail;
1015                 }
1016
1017                 if (chdir("/") < 0) {
1018                         log_error("chdir() failed: %m");
1019                         goto child_fail;
1020                 }
1021
1022                 umask(0022);
1023
1024                 loopback_setup();
1025
1026                 if (drop_capabilities() < 0) {
1027                         log_error("drop_capabilities() failed: %m");
1028                         goto child_fail;
1029                 }
1030
1031                 if (arg_user) {
1032
1033                         if (get_user_creds((const char**)&arg_user, &uid, &gid, &home) < 0) {
1034                                 log_error("get_user_creds() failed: %m");
1035                                 goto child_fail;
1036                         }
1037
1038                         if (mkdir_parents(home, 0775) < 0) {
1039                                 log_error("mkdir_parents() failed: %m");
1040                                 goto child_fail;
1041                         }
1042
1043                         if (safe_mkdir(home, 0775, uid, gid) < 0) {
1044                                 log_error("safe_mkdir() failed: %m");
1045                                 goto child_fail;
1046                         }
1047
1048                         if (initgroups((const char*)arg_user, gid) < 0) {
1049                                 log_error("initgroups() failed: %m");
1050                                 goto child_fail;
1051                         }
1052
1053                         if (setresgid(gid, gid, gid) < 0) {
1054                                 log_error("setregid() failed: %m");
1055                                 goto child_fail;
1056                         }
1057
1058                         if (setresuid(uid, uid, uid) < 0) {
1059                                 log_error("setreuid() failed: %m");
1060                                 goto child_fail;
1061                         }
1062                 }
1063
1064                 if ((asprintf((char**)(envp + 3), "HOME=%s", home ? home: "/root") < 0) ||
1065                     (asprintf((char**)(envp + 4), "USER=%s", arg_user ? arg_user : "root") < 0) ||
1066                     (asprintf((char**)(envp + 5), "LOGNAME=%s", arg_user ? arg_user : "root") < 0)) {
1067                     log_error("Out of memory");
1068                     goto child_fail;
1069                 }
1070
1071                 if (arg_uuid) {
1072                         if (asprintf((char**)(envp + 6), "container_uuid=%s", arg_uuid) < 0) {
1073                                 log_error("Out of memory");
1074                                 goto child_fail;
1075                         }
1076                 }
1077
1078                 setup_hostname();
1079
1080                 if (arg_boot) {
1081                         char **a;
1082                         size_t l;
1083
1084                         /* Automatically search for the init system */
1085
1086                         l = 1 + argc - optind;
1087                         a = newa(char*, l + 1);
1088                         memcpy(a + 1, argv + optind, l * sizeof(char*));
1089
1090                         a[0] = (char*) "/usr/lib/systemd/systemd";
1091                         execve(a[0], a, (char**) envp);
1092
1093                         a[0] = (char*) "/lib/systemd/systemd";
1094                         execve(a[0], a, (char**) envp);
1095
1096                         a[0] = (char*) "/sbin/init";
1097                         execve(a[0], a, (char**) envp);
1098                 } else if (argc > optind)
1099                         execvpe(argv[optind], argv + optind, (char**) envp);
1100                 else {
1101                         chdir(home ? home : "/root");
1102                         execle("/bin/bash", "-bash", NULL, (char**) envp);
1103                 }
1104
1105                 log_error("execv() failed: %m");
1106
1107         child_fail:
1108                 _exit(EXIT_FAILURE);
1109         }
1110
1111         if (process_pty(master, &mask) < 0)
1112                 goto finish;
1113
1114         if (saved_attr_valid) {
1115                 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
1116                 saved_attr_valid = false;
1117         }
1118
1119         r = wait_for_terminate_and_warn(argc > optind ? argv[optind] : "bash", pid);
1120
1121         if (r < 0)
1122                 r = EXIT_FAILURE;
1123
1124 finish:
1125         if (saved_attr_valid)
1126                 tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
1127
1128         if (master >= 0)
1129                 close_nointr_nofail(master);
1130
1131         close_pipe(kmsg_socket_pair);
1132
1133         if (oldcg)
1134                 cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);
1135
1136         if (newcg)
1137                 cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, newcg, true);
1138
1139         free(arg_directory);
1140         strv_free(arg_controllers);
1141         free(oldcg);
1142         free(newcg);
1143
1144         return r;
1145 }