Systemd/src/nspawn/nspawn.c

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <signal.h>
#include <sched.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/syscall.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <sys/prctl.h>
#include <sys/capability.h>
#include <getopt.h>
#include <termios.h>
#include <sys/signalfd.h>
#include <grp.h>
#include <linux/fs.h>
#include <sys/un.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <sys/eventfd.h>
#include <net/if.h>
#include <linux/veth.h>
#include <sys/personality.h>

#ifdef HAVE_SELINUX
#include <selinux/selinux.h>
#endif

#ifdef HAVE_SECCOMP
#include <seccomp.h>
#endif

#include "sd-daemon.h"
#include "sd-bus.h"
#include "sd-id128.h"
#include "sd-rtnl.h"
#include "log.h"
#include "util.h"
#include "mkdir.h"
#include "macro.h"
#include "audit.h"
#include "missing.h"
#include "cgroup-util.h"
#include "strv.h"
#include "path-util.h"
#include "loopback-setup.h"
#include "dev-setup.h"
#include "fdset.h"
#include "build.h"
#include "fileio.h"
#include "bus-util.h"
#include "bus-error.h"
#include "ptyfwd.h"
#include "bus-kernel.h"
#include "env-util.h"
#include "def.h"
#include "rtnl-util.h"
#include "udev-util.h"

#ifdef HAVE_SECCOMP
#include "seccomp-util.h"
#endif

typedef enum LinkJournal {
        LINK_NO,
        LINK_AUTO,
        LINK_HOST,
        LINK_GUEST
} LinkJournal;

static char *arg_directory = NULL;
static char *arg_user = NULL;
static sd_id128_t arg_uuid = {};
static char *arg_machine = NULL;
static char *arg_selinux_context = NULL;
static char *arg_selinux_apifs_context = NULL;
static const char *arg_slice = NULL;
static bool arg_private_network = false;
static bool arg_read_only = false;
static bool arg_boot = false;
static LinkJournal arg_link_journal = LINK_AUTO;
static uint64_t arg_retain =
        (1ULL << CAP_CHOWN) |
        (1ULL << CAP_DAC_OVERRIDE) |
        (1ULL << CAP_DAC_READ_SEARCH) |
        (1ULL << CAP_FOWNER) |
        (1ULL << CAP_FSETID) |
        (1ULL << CAP_IPC_OWNER) |
        (1ULL << CAP_KILL) |
        (1ULL << CAP_LEASE) |
        (1ULL << CAP_LINUX_IMMUTABLE) |
        (1ULL << CAP_NET_BIND_SERVICE) |
        (1ULL << CAP_NET_BROADCAST) |
        (1ULL << CAP_NET_RAW) |
        (1ULL << CAP_SETGID) |
        (1ULL << CAP_SETFCAP) |
        (1ULL << CAP_SETPCAP) |
        (1ULL << CAP_SETUID) |
        (1ULL << CAP_SYS_ADMIN) |
        (1ULL << CAP_SYS_CHROOT) |
        (1ULL << CAP_SYS_NICE) |
        (1ULL << CAP_SYS_PTRACE) |
        (1ULL << CAP_SYS_TTY_CONFIG) |
        (1ULL << CAP_SYS_RESOURCE) |
        (1ULL << CAP_SYS_BOOT) |
        (1ULL << CAP_AUDIT_WRITE) |
        (1ULL << CAP_AUDIT_CONTROL) |
        (1ULL << CAP_MKNOD);
static char **arg_bind = NULL;
static char **arg_bind_ro = NULL;
static char **arg_setenv = NULL;
static bool arg_quiet = false;
static bool arg_share_system = false;
static bool arg_register = true;
static bool arg_keep_unit = false;
static char **arg_network_interfaces = NULL;
static bool arg_network_veth = false;
static char *arg_network_bridge = NULL;
static unsigned long arg_personality = 0xffffffffLU;

static int help(void) {

        printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n"
               "Spawn a minimal namespace container for debugging, testing and building.\n\n"
               "  -h --help                 Show this help\n"
               "     --version              Print version string\n"
               "  -q --quiet                Do not show status information\n"
               "  -D --directory=NAME       Root directory for the container\n"
               "  -b --boot                 Boot up full system (i.e. invoke init)\n"
               "  -u --user=USER            Run the command under specified user or uid\n"
               "  -M --machine=NAME         Set the machine name for the container\n"
               "     --uuid=UUID            Set a specific machine UUID for the container\n"
               "  -S --slice=SLICE          Place the container in the specified slice\n"
               "     --private-network      Disable network in container\n"
               "     --network-interface=INTERFACE\n"
               "                            Assign an existing network interface to the\n"
               "                            container\n"
               "     --network-veth         Add a virtual ethernet connection between host\n"
               "                            and container\n"
               "     --network-bridge=INTERFACE\n"
               "                            Add a virtual ethernet connection between host\n"
               "                            and container and add it to an existing bridge on\n"
               "                            the host\n"
               "  -Z --selinux-context=SECLABEL\n"
               "                            Set the SELinux security context to be used by\n"
               "                            processes in the container\n"
               "  -L --selinux-apifs-context=SECLABEL\n"
               "                            Set the SELinux security context to be used by\n"
               "                            API/tmpfs file systems in the container\n"
               "     --capability=CAP       In addition to the default, retain specified\n"
               "                            capability\n"
               "     --drop-capability=CAP  Drop the specified capability from the default set\n"
               "     --link-journal=MODE    Link up guest journal, one of no, auto, guest, host\n"
               "  -j                        Equivalent to --link-journal=host\n"
               "     --read-only            Mount the root directory read-only\n"
               "     --bind=PATH[:PATH]     Bind mount a file or directory from the host into\n"
               "                            the container\n"
               "     --bind-ro=PATH[:PATH]  Similar, but creates a read-only bind mount\n"
               "     --setenv=NAME=VALUE    Pass an environment variable to PID 1\n"
               "     --share-system         Share system namespaces with host\n"
               "     --register=BOOLEAN     Register container as machine\n"
               "     --keep-unit            Do not register a scope for the machine, reuse\n"
               "                            the service unit nspawn is running in\n",
               program_invocation_short_name);

        return 0;
}

static int parse_argv(int argc, char *argv[]) {

        enum {
                ARG_VERSION = 0x100,
                ARG_PRIVATE_NETWORK,
                ARG_UUID,
                ARG_READ_ONLY,
                ARG_CAPABILITY,
                ARG_DROP_CAPABILITY,
                ARG_LINK_JOURNAL,
                ARG_BIND,
                ARG_BIND_RO,
                ARG_SETENV,
                ARG_SHARE_SYSTEM,
                ARG_REGISTER,
                ARG_KEEP_UNIT,
                ARG_NETWORK_INTERFACE,
                ARG_NETWORK_VETH,
                ARG_NETWORK_BRIDGE,
                ARG_PERSONALITY,
        };

        static const struct option options[] = {
                { "help",                  no_argument,       NULL, 'h'                   },
                { "version",               no_argument,       NULL, ARG_VERSION           },
                { "directory",             required_argument, NULL, 'D'                   },
                { "user",                  required_argument, NULL, 'u'                   },
                { "private-network",       no_argument,       NULL, ARG_PRIVATE_NETWORK   },
                { "boot",                  no_argument,       NULL, 'b'                   },
                { "uuid",                  required_argument, NULL, ARG_UUID              },
                { "read-only",             no_argument,       NULL, ARG_READ_ONLY         },
                { "capability",            required_argument, NULL, ARG_CAPABILITY        },
                { "drop-capability",       required_argument, NULL, ARG_DROP_CAPABILITY   },
                { "link-journal",          required_argument, NULL, ARG_LINK_JOURNAL      },
                { "bind",                  required_argument, NULL, ARG_BIND              },
                { "bind-ro",               required_argument, NULL, ARG_BIND_RO           },
                { "machine",               required_argument, NULL, 'M'                   },
                { "slice",                 required_argument, NULL, 'S'                   },
                { "setenv",                required_argument, NULL, ARG_SETENV            },
                { "selinux-context",       required_argument, NULL, 'Z'                   },
                { "selinux-apifs-context", required_argument, NULL, 'L'                   },
                { "quiet",                 no_argument,       NULL, 'q'                   },
                { "share-system",          no_argument,       NULL, ARG_SHARE_SYSTEM      },
                { "register",              required_argument, NULL, ARG_REGISTER          },
                { "keep-unit",             no_argument,       NULL, ARG_KEEP_UNIT         },
                { "network-interface",     required_argument, NULL, ARG_NETWORK_INTERFACE },
                { "network-veth",          no_argument,       NULL, ARG_NETWORK_VETH      },
                { "network-bridge",        required_argument, NULL, ARG_NETWORK_BRIDGE    },
                { "personality",           required_argument, NULL, ARG_PERSONALITY       },
                {}
        };

        int c, r;
        uint64_t plus = 0, minus = 0;

        assert(argc >= 0);
        assert(argv);

        while ((c = getopt_long(argc, argv, "+hD:u:bL:M:jS:Z:q", options, NULL)) >= 0) {

                switch (c) {

                case 'h':
                        return help();

                case ARG_VERSION:
                        puts(PACKAGE_STRING);
                        puts(SYSTEMD_FEATURES);
                        return 0;

                case 'D':
                        free(arg_directory);
                        arg_directory = canonicalize_file_name(optarg);
                        if (!arg_directory) {
                                log_error("Invalid root directory: %m");
                                return -ENOMEM;
                        }

                        break;

                case 'u':
                        free(arg_user);
                        arg_user = strdup(optarg);
                        if (!arg_user)
                                return log_oom();

                        break;

                case ARG_NETWORK_BRIDGE:
                        arg_network_bridge = strdup(optarg);
                        if (!arg_network_bridge)
                                return log_oom();

                        /* fall through */

                case ARG_NETWORK_VETH:
                        arg_network_veth = true;
                        arg_private_network = true;
                        break;

                case ARG_NETWORK_INTERFACE:
                        if (strv_push(&arg_network_interfaces, optarg) < 0)
                                return log_oom();

                        /* fall through */

                case ARG_PRIVATE_NETWORK:
                        arg_private_network = true;
                        break;

                case 'b':
                        arg_boot = true;
                        break;

                case ARG_UUID:
                        r = sd_id128_from_string(optarg, &arg_uuid);
                        if (r < 0) {
                                log_error("Invalid UUID: %s", optarg);
                                return r;
                        }
                        break;

                case 'S':
                        arg_slice = strdup(optarg);
                        if (!arg_slice)
                                return log_oom();

                        break;

                case 'M':
                        if (isempty(optarg)) {
                                free(arg_machine);
                                arg_machine = NULL;
                        } else {

                                if (!hostname_is_valid(optarg)) {
                                        log_error("Invalid machine name: %s", optarg);
                                        return -EINVAL;
                                }

                                free(arg_machine);
                                arg_machine = strdup(optarg);
                                if (!arg_machine)
                                        return log_oom();

                                break;
                        }

                case 'Z':
                        arg_selinux_context = optarg;
                        break;

                case 'L':
                        arg_selinux_apifs_context = optarg;
                        break;

                case ARG_READ_ONLY:
                        arg_read_only = true;
                        break;

                case ARG_CAPABILITY:
                case ARG_DROP_CAPABILITY: {
                        char *state, *word;
                        size_t length;

                        FOREACH_WORD_SEPARATOR(word, length, optarg, ",", state) {
                                _cleanup_free_ char *t;
                                cap_value_t cap;

                                t = strndup(word, length);
                                if (!t)
                                        return log_oom();

                                if (streq(t, "all")) {
                                        if (c == ARG_CAPABILITY)
                                                plus = (uint64_t) -1;
                                        else
                                                minus = (uint64_t) -1;
                                } else {
                                        if (cap_from_name(t, &cap) < 0) {
                                                log_error("Failed to parse capability %s.", t);
                                                return -EINVAL;
                                        }

                                        if (c == ARG_CAPABILITY)
                                                plus |= 1ULL << (uint64_t) cap;
                                        else
                                                minus |= 1ULL << (uint64_t) cap;
                                }
                        }

                        break;
                }

                case 'j':
                        arg_link_journal = LINK_GUEST;
                        break;

                case ARG_LINK_JOURNAL:
                        if (streq(optarg, "auto"))
                                arg_link_journal = LINK_AUTO;
                        else if (streq(optarg, "no"))
                                arg_link_journal = LINK_NO;
                        else if (streq(optarg, "guest"))
                                arg_link_journal = LINK_GUEST;
                        else if (streq(optarg, "host"))
                                arg_link_journal = LINK_HOST;
                        else {
                                log_error("Failed to parse link journal mode %s", optarg);
                                return -EINVAL;
                        }

                        break;

                case ARG_BIND:
                case ARG_BIND_RO: {
                        _cleanup_free_ char *a = NULL, *b = NULL;
                        char *e;
                        char ***x;

                        x = c == ARG_BIND ? &arg_bind : &arg_bind_ro;

                        e = strchr(optarg, ':');
                        if (e) {
                                a = strndup(optarg, e - optarg);
                                b = strdup(e + 1);
                        } else {
                                a = strdup(optarg);
                                b = strdup(optarg);
                        }

                        if (!a || !b)
                                return log_oom();

                        if (!path_is_absolute(a) || !path_is_absolute(b)) {
                                log_error("Invalid bind mount specification: %s", optarg);
                                return -EINVAL;
                        }

                        r = strv_extend(x, a);
                        if (r < 0)
                                return log_oom();

                        r = strv_extend(x, b);
                        if (r < 0)
                                return log_oom();

                        break;
                }

                case ARG_SETENV: {
                        char **n;

                        if (!env_assignment_is_valid(optarg)) {
                                log_error("Environment variable assignment '%s' is not valid.", optarg);
                                return -EINVAL;
                        }

                        n = strv_env_set(arg_setenv, optarg);
                        if (!n)
                                return log_oom();

                        strv_free(arg_setenv);
                        arg_setenv = n;
                        break;
                }

                case 'q':
                        arg_quiet = true;
                        break;

                case ARG_SHARE_SYSTEM:
                        arg_share_system = true;
                        break;

                case ARG_REGISTER:
                        r = parse_boolean(optarg);
                        if (r < 0) {
                                log_error("Failed to parse --register= argument: %s", optarg);
                                return r;
                        }

                        arg_register = r;
                        break;

                case ARG_KEEP_UNIT:
                        arg_keep_unit = true;
                        break;

                case ARG_PERSONALITY:

                        arg_personality = personality_from_string(optarg);
                        if (arg_personality == 0xffffffffLU) {
                                log_error("Unknown or unsupported personality '%s'.", optarg);
                                return -EINVAL;
                        }

                        break;

                case '?':
                        return -EINVAL;

                default:
                        assert_not_reached("Unhandled option");
                }
        }

        if (arg_share_system)
                arg_register = false;

        if (arg_boot && arg_share_system) {
                log_error("--boot and --share-system may not be combined.");
                return -EINVAL;
        }

        if (arg_keep_unit && cg_pid_get_owner_uid(0, NULL) >= 0) {
                log_error("--keep-unit may not be used when invoked from a user session.");
                return -EINVAL;
        }

        arg_retain = (arg_retain | plus | (arg_private_network ? 1ULL << CAP_NET_ADMIN : 0)) & ~minus;

        return 1;
}

static int mount_all(const char *dest) {

        typedef struct MountPoint {
                const char *what;
                const char *where;
                const char *type;
                const char *options;
                unsigned long flags;
                bool fatal;
        } MountPoint;

        static const MountPoint mount_table[] = {
                { "proc",      "/proc",     "proc",  NULL,       MS_NOSUID|MS_NOEXEC|MS_NODEV, true  },
                { "/proc/sys", "/proc/sys", NULL,    NULL,       MS_BIND, true                       },   /* Bind mount first */
                { NULL,        "/proc/sys", NULL,    NULL,       MS_BIND|MS_RDONLY|MS_REMOUNT, true  },   /* Then, make it r/o */
                { "sysfs",     "/sys",      "sysfs", NULL,       MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, true  },
                { "tmpfs",     "/dev",      "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME,     true  },
                { "devpts",    "/dev/pts",  "devpts","newinstance,ptmxmode=0666,mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, true },
                { "tmpfs",     "/dev/shm",  "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true  },
                { "tmpfs",     "/run",      "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true  },
#ifdef HAVE_SELINUX
                { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND,                      false },  /* Bind mount first */
                { NULL,              "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false },  /* Then, make it r/o */
#endif
        };

        unsigned k;
        int r = 0;

        for (k = 0; k < ELEMENTSOF(mount_table); k++) {
                _cleanup_free_ char *where = NULL;
#ifdef HAVE_SELINUX
                _cleanup_free_ char *options = NULL;
#endif
                const char *o;
                int t;

                where = strjoin(dest, "/", mount_table[k].where, NULL);
                if (!where)
                        return log_oom();

                t = path_is_mount_point(where, true);
                if (t < 0) {
                        log_error("Failed to detect whether %s is a mount point: %s", where, strerror(-t));

                        if (r == 0)
                                r = t;

                        continue;
                }

                /* Skip this entry if it is not a remount. */
                if (mount_table[k].what && t > 0)
                        continue;

                mkdir_p(where, 0755);

#ifdef HAVE_SELINUX
                if (arg_selinux_apifs_context &&
                    (streq_ptr(mount_table[k].what, "tmpfs") || streq_ptr(mount_table[k].what, "devpts"))) {
                        options = strjoin(mount_table[k].options, ",context=\"", arg_selinux_apifs_context, "\"", NULL);
                        if (!options)
                                return log_oom();

                        o = options;
                } else
#endif
                        o = mount_table[k].options;


                if (mount(mount_table[k].what,
                          where,
                          mount_table[k].type,
                          mount_table[k].flags,
                          o) < 0 &&
                    mount_table[k].fatal) {

                        log_error("mount(%s) failed: %m", where);

                        if (r == 0)
                                r = -errno;
                }
        }

        return r;
}

static int mount_binds(const char *dest, char **l, unsigned long flags) {
        char **x, **y;

        STRV_FOREACH_PAIR(x, y, l) {
                char *where;
                struct stat source_st, dest_st;
                int r;

                if (stat(*x, &source_st) < 0) {
                        log_error("failed to stat %s: %m", *x);
                        return -errno;
                }

                where = strappenda(dest, *y);
                r = stat(where, &dest_st);
                if (r == 0) {
                        if ((source_st.st_mode & S_IFMT) != (dest_st.st_mode & S_IFMT)) {
                                log_error("The file types of %s and %s do not match. Refusing bind mount",
                                                *x, where);
                                return -EINVAL;
                        }
                } else if (errno == ENOENT) {
                        r = mkdir_parents_label(where, 0755);
                        if (r < 0) {
                                log_error("Failed to bind mount %s: %s", *x, strerror(-r));
                                return r;
                        }
                } else {
                        log_error("Failed to bind mount %s: %s", *x, strerror(errno));
                        return -errno;
                }
                /* Create the mount point, but be conservative -- refuse to create block
                * and char devices. */
                if (S_ISDIR(source_st.st_mode))
                        mkdir_label(where, 0755);
                else if (S_ISFIFO(source_st.st_mode))
                        mkfifo(where, 0644);
                else if (S_ISSOCK(source_st.st_mode))
                        mknod(where, 0644 | S_IFSOCK, 0);
                else if (S_ISREG(source_st.st_mode))
                        touch(where);
                else {
                        log_error("Refusing to create mountpoint for file: %s", *x);
                        return -ENOTSUP;
                }

                if (mount(*x, where, "bind", MS_BIND, NULL) < 0) {
                        log_error("mount(%s) failed: %m", where);
                        return -errno;
                }

                if (flags && mount(NULL, where, NULL, MS_REMOUNT|MS_BIND|flags, NULL) < 0) {
                        log_error("mount(%s) failed: %m", where);
                        return -errno;
                }
        }

        return 0;
}

static int setup_timezone(const char *dest) {
        _cleanup_free_ char *where = NULL, *p = NULL, *q = NULL, *check = NULL, *what = NULL;
        char *z, *y;
        int r;

        assert(dest);

        /* Fix the timezone, if possible */
        r = readlink_malloc("/etc/localtime", &p);
        if (r < 0) {
                log_warning("/etc/localtime is not a symlink, not updating container timezone.");
                return 0;
        }

        z = path_startswith(p, "../usr/share/zoneinfo/");
        if (!z)
                z = path_startswith(p, "/usr/share/zoneinfo/");
        if (!z) {
                log_warning("/etc/localtime does not point into /usr/share/zoneinfo/, not updating container timezone.");
                return 0;
        }

        where = strappend(dest, "/etc/localtime");
        if (!where)
                return log_oom();

        r = readlink_malloc(where, &q);
        if (r >= 0) {
                y = path_startswith(q, "../usr/share/zoneinfo/");
                if (!y)
                        y = path_startswith(q, "/usr/share/zoneinfo/");


                /* Already pointing to the right place? Then do nothing .. */
                if (y && streq(y, z))
                        return 0;
        }

        check = strjoin(dest, "/usr/share/zoneinfo/", z, NULL);
        if (!check)
                return log_oom();

        if (access(check, F_OK) < 0) {
                log_warning("Timezone %s does not exist in container, not updating container timezone.", z);
                return 0;
        }

        what = strappend("../usr/share/zoneinfo/", z);
        if (!what)
                return log_oom();

        unlink(where);
        if (symlink(what, where) < 0) {
                log_error("Failed to correct timezone of container: %m");
                return 0;
        }

        return 0;
}

static int setup_resolv_conf(const char *dest) {
        char _cleanup_free_ *where = NULL;

        assert(dest);

        if (arg_private_network)
                return 0;

        /* Fix resolv.conf, if possible */
        where = strappend(dest, "/etc/resolv.conf");
        if (!where)
                return log_oom();

        /* We don't really care for the results of this really. If it
         * fails, it fails, but meh... */
        copy_file("/etc/resolv.conf", where, O_TRUNC|O_NOFOLLOW);

        return 0;
}

static int setup_boot_id(const char *dest) {
        _cleanup_free_ char *from = NULL, *to = NULL;
        sd_id128_t rnd = {};
        char as_uuid[37];
        int r;

        assert(dest);

        if (arg_share_system)
                return 0;

        /* Generate a new randomized boot ID, so that each boot-up of
         * the container gets a new one */

        from = strappend(dest, "/dev/proc-sys-kernel-random-boot-id");
        to = strappend(dest, "/proc/sys/kernel/random/boot_id");
        if (!from || !to)
                return log_oom();

        r = sd_id128_randomize(&rnd);
        if (r < 0) {
                log_error("Failed to generate random boot id: %s", strerror(-r));
                return r;
        }

        snprintf(as_uuid, sizeof(as_uuid),
                 "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
                 SD_ID128_FORMAT_VAL(rnd));
        char_array_0(as_uuid);

        r = write_string_file(from, as_uuid);
        if (r < 0) {
                log_error("Failed to write boot id: %s", strerror(-r));
                return r;
        }

        if (mount(from, to, "bind", MS_BIND, NULL) < 0) {
                log_error("Failed to bind mount boot id: %m");
                r = -errno;
        } else if (mount(from, to, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL))
                log_warning("Failed to make boot id read-only: %m");

        unlink(from);
        return r;
}

static int copy_devnodes(const char *dest) {

        static const char devnodes[] =
                "null\0"
                "zero\0"
                "full\0"
                "random\0"
                "urandom\0"
                "tty\0";

        const char *d;
        int r = 0;
        _cleanup_umask_ mode_t u;

        assert(dest);

        u = umask(0000);

        NULSTR_FOREACH(d, devnodes) {
                _cleanup_free_ char *from = NULL, *to = NULL;
                struct stat st;

                from = strappend("/dev/", d);
                to = strjoin(dest, "/dev/", d, NULL);
                if (!from || !to)
                        return log_oom();

                if (stat(from, &st) < 0) {

                        if (errno != ENOENT) {
                                log_error("Failed to stat %s: %m", from);
                                return -errno;
                        }

                } else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {

                        log_error("%s is not a char or block device, cannot copy", from);
                        return -EIO;

                } else if (mknod(to, st.st_mode, st.st_rdev) < 0) {

                        log_error("mknod(%s) failed: %m", dest);
                        return  -errno;
                }
        }

        return r;
}

static int setup_ptmx(const char *dest) {
        _cleanup_free_ char *p = NULL;

        p = strappend(dest, "/dev/ptmx");
        if (!p)
                return log_oom();

        if (symlink("pts/ptmx", p) < 0) {
                log_error("Failed to create /dev/ptmx symlink: %m");
                return -errno;
        }

        return 0;
}

static int setup_dev_console(const char *dest, const char *console) {
        struct stat st;
        _cleanup_free_ char *to = NULL;
        int r;
        _cleanup_umask_ mode_t u;

        assert(dest);
        assert(console);

        u = umask(0000);

        if (stat(console, &st) < 0) {
                log_error("Failed to stat %s: %m", console);
                return -errno;

        } else if (!S_ISCHR(st.st_mode)) {
                log_error("/dev/console is not a char device");
                return -EIO;
        }

        r = chmod_and_chown(console, 0600, 0, 0);
        if (r < 0) {
                log_error("Failed to correct access mode for TTY: %s", strerror(-r));
                return r;
        }

        if (asprintf(&to, "%s/dev/console", dest) < 0)
                return log_oom();

        /* We need to bind mount the right tty to /dev/console since
         * ptys can only exist on pts file systems. To have something
         * to bind mount things on we create a device node first, that
         * has the right major/minor (note that the major minor
         * doesn't actually matter here, since we mount it over
         * anyway). */

        if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) {
                log_error("mknod() for /dev/console failed: %m");
                return -errno;
        }

        if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
                log_error("Bind mount for /dev/console failed: %m");
                return -errno;
        }

        return 0;
}

static int setup_kmsg(const char *dest, int kmsg_socket) {
        _cleanup_free_ char *from = NULL, *to = NULL;
        int r, fd, k;
        _cleanup_umask_ mode_t u;
        union {
                struct cmsghdr cmsghdr;
                uint8_t buf[CMSG_SPACE(sizeof(int))];
        } control = {};
        struct msghdr mh = {
                .msg_control = &control,
                .msg_controllen = sizeof(control),
        };
        struct cmsghdr *cmsg;

        assert(dest);
        assert(kmsg_socket >= 0);

        u = umask(0000);

        /* We create the kmsg FIFO as /dev/kmsg, but immediately
         * delete it after bind mounting it to /proc/kmsg. While FIFOs
         * on the reading side behave very similar to /proc/kmsg,
         * their writing side behaves differently from /dev/kmsg in
         * that writing blocks when nothing is reading. In order to
         * avoid any problems with containers deadlocking due to this
         * we simply make /dev/kmsg unavailable to the container. */
        if (asprintf(&from, "%s/dev/kmsg", dest) < 0 ||
            asprintf(&to, "%s/proc/kmsg", dest) < 0)
                return log_oom();

        if (mkfifo(from, 0600) < 0) {
                log_error("mkfifo() for /dev/kmsg failed: %m");
                return -errno;
        }

        r = chmod_and_chown(from, 0600, 0, 0);
        if (r < 0) {
                log_error("Failed to correct access mode for /dev/kmsg: %s", strerror(-r));
                return r;
        }

        if (mount(from, to, "bind", MS_BIND, NULL) < 0) {
                log_error("Bind mount for /proc/kmsg failed: %m");
                return -errno;
        }

        fd = open(from, O_RDWR|O_NDELAY|O_CLOEXEC);
        if (fd < 0) {
                log_error("Failed to open fifo: %m");
                return -errno;
        }

        cmsg = CMSG_FIRSTHDR(&mh);
        cmsg->cmsg_level = SOL_SOCKET;
        cmsg->cmsg_type = SCM_RIGHTS;
        cmsg->cmsg_len = CMSG_LEN(sizeof(int));
        memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));

        mh.msg_controllen = cmsg->cmsg_len;

        /* Store away the fd in the socket, so that it stays open as
         * long as we run the child */
        k = sendmsg(kmsg_socket, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
        close_nointr_nofail(fd);

        if (k < 0) {
                log_error("Failed to send FIFO fd: %m");
                return -errno;
        }

        /* And now make the FIFO unavailable as /dev/kmsg... */
        unlink(from);
        return 0;
}

static int setup_hostname(void) {

        if (arg_share_system)
                return 0;

        if (sethostname(arg_machine, strlen(arg_machine)) < 0)
                return -errno;

        return 0;
}

static int setup_journal(const char *directory) {
        sd_id128_t machine_id, this_id;
        _cleanup_free_ char *p = NULL, *b = NULL, *q = NULL, *d = NULL;
        char *id;
        int r;

        p = strappend(directory, "/etc/machine-id");
        if (!p)
                return log_oom();

        r = read_one_line_file(p, &b);
        if (r == -ENOENT && arg_link_journal == LINK_AUTO)
                return 0;
        else if (r < 0) {
                log_error("Failed to read machine ID from %s: %s", p, strerror(-r));
                return r;
        }

        id = strstrip(b);
        if (isempty(id) && arg_link_journal == LINK_AUTO)
                return 0;

        /* Verify validity */
        r = sd_id128_from_string(id, &machine_id);
        if (r < 0) {
                log_error("Failed to parse machine ID from %s: %s", p, strerror(-r));
                return r;
        }

        r = sd_id128_get_machine(&this_id);
        if (r < 0) {
                log_error("Failed to retrieve machine ID: %s", strerror(-r));
                return r;
        }

        if (sd_id128_equal(machine_id, this_id)) {
                log_full(arg_link_journal == LINK_AUTO ? LOG_WARNING : LOG_ERR,
                         "Host and machine ids are equal (%s): refusing to link journals", id);
                if (arg_link_journal == LINK_AUTO)
                        return 0;
                return
                        -EEXIST;
        }

        if (arg_link_journal == LINK_NO)
                return 0;

        free(p);
        p = strappend("/var/log/journal/", id);
        q = strjoin(directory, "/var/log/journal/", id, NULL);
        if (!p || !q)
                return log_oom();

        if (path_is_mount_point(p, false) > 0) {
                if (arg_link_journal != LINK_AUTO) {
                        log_error("%s: already a mount point, refusing to use for journal", p);
                        return -EEXIST;
                }

                return 0;
        }

        if (path_is_mount_point(q, false) > 0) {
                if (arg_link_journal != LINK_AUTO) {
                        log_error("%s: already a mount point, refusing to use for journal", q);
                        return -EEXIST;
                }

                return 0;
        }

        r = readlink_and_make_absolute(p, &d);
        if (r >= 0) {
                if ((arg_link_journal == LINK_GUEST ||
                     arg_link_journal == LINK_AUTO) &&
                    path_equal(d, q)) {

                        r = mkdir_p(q, 0755);
                        if (r < 0)
                                log_warning("failed to create directory %s: %m", q);
                        return 0;
                }

                if (unlink(p) < 0) {
                        log_error("Failed to remove symlink %s: %m", p);
                        return -errno;
                }
        } else if (r == -EINVAL) {

                if (arg_link_journal == LINK_GUEST &&
                    rmdir(p) < 0) {

                        if (errno == ENOTDIR) {
                                log_error("%s already exists and is neither a symlink nor a directory", p);
                                return r;
                        } else {
                                log_error("Failed to remove %s: %m", p);
                                return -errno;
                        }
                }
        } else if (r != -ENOENT) {
                log_error("readlink(%s) failed: %m", p);
                return r;
        }

        if (arg_link_journal == LINK_GUEST) {

                if (symlink(q, p) < 0) {
                        log_error("Failed to symlink %s to %s: %m", q, p);
                        return -errno;
                }

                r = mkdir_p(q, 0755);
                if (r < 0)
                        log_warning("failed to create directory %s: %m", q);
                return 0;
        }

        if (arg_link_journal == LINK_HOST) {
                r = mkdir_p(p, 0755);
                if (r < 0) {
                        log_error("Failed to create %s: %m", p);
                        return r;
                }

        } else if (access(p, F_OK) < 0)
                return 0;

        if (dir_is_empty(q) == 0) {
                log_error("%s not empty.", q);
                return -ENOTEMPTY;
        }

        r = mkdir_p(q, 0755);
        if (r < 0) {
                log_error("Failed to create %s: %m", q);
                return r;
        }

        if (mount(p, q, "bind", MS_BIND, NULL) < 0) {
                log_error("Failed to bind mount journal from host into guest: %m");
                return -errno;
        }

        return 0;
}

static int setup_kdbus(const char *dest, const char *path) {
        const char *p;

        if (!path)
                return 0;

        p = strappenda(dest, "/dev/kdbus");
        if (mkdir(p, 0755) < 0) {
                log_error("Failed to create kdbus path: %m");
                return  -errno;
        }

        if (mount(path, p, "bind", MS_BIND, NULL) < 0) {
                log_error("Failed to mount kdbus domain path: %m");
                return -errno;
        }

        return 0;
}

static int drop_capabilities(void) {
        return capability_bounding_set_drop(~arg_retain, false);
}

static int register_machine(pid_t pid) {
        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
        _cleanup_bus_unref_ sd_bus *bus = NULL;
        int r;

        if (!arg_register)
                return 0;

        r = sd_bus_default_system(&bus);
        if (r < 0) {
                log_error("Failed to open system bus: %s", strerror(-r));
                return r;
        }

        if (arg_keep_unit) {
                r = sd_bus_call_method(
                                bus,
                                "org.freedesktop.machine1",
                                "/org/freedesktop/machine1",
                                "org.freedesktop.machine1.Manager",
                                "RegisterMachine",
                                &error,
                                NULL,
                                "sayssus",
                                arg_machine,
                                SD_BUS_MESSAGE_APPEND_ID128(arg_uuid),
                                "nspawn",
                                "container",
                                (uint32_t) pid,
                                strempty(arg_directory));
        } else {
                _cleanup_bus_message_unref_ sd_bus_message *m = NULL;

                r = sd_bus_message_new_method_call(
                                bus,
                                &m,
                                "org.freedesktop.machine1",
                                "/org/freedesktop/machine1",
                                "org.freedesktop.machine1.Manager",
                                "CreateMachine");
                if (r < 0) {
                        log_error("Failed to create message: %s", strerror(-r));
                        return r;
                }

                r = sd_bus_message_append(
                                m,
                                "sayssus",
                                arg_machine,
                                SD_BUS_MESSAGE_APPEND_ID128(arg_uuid),
                                "nspawn",
                                "container",
                                (uint32_t) pid,
                                strempty(arg_directory));
                if (r < 0) {
                        log_error("Failed to append message arguments: %s", strerror(-r));
                        return r;
                }

                r = sd_bus_message_open_container(m, 'a', "(sv)");
                if (r < 0) {
                        log_error("Failed to open container: %s", strerror(-r));
                        return r;
                }

                if (!isempty(arg_slice)) {
                        r = sd_bus_message_append(m, "(sv)", "Slice", "s", arg_slice);
                        if (r < 0) {
                                log_error("Failed to append slice: %s", strerror(-r));
                                return r;
                        }
                }

                r = sd_bus_message_append(m, "(sv)", "DevicePolicy", "s", "strict");
                if (r < 0) {
                        log_error("Failed to add device policy: %s", strerror(-r));
                        return r;
                }

                r = sd_bus_message_append(m, "(sv)", "DeviceAllow", "a(ss)", 8,
                                          /* Allow the container to
                                           * access and create the API
                                           * device nodes, so that
                                           * PrivateDevices= in the
                                           * container can work
                                           * fine */
                                          "/dev/null", "rwm",
                                          "/dev/zero", "rwm",
                                          "/dev/full", "rwm",
                                          "/dev/random", "rwm",
                                          "/dev/urandom", "rwm",
                                          "/dev/tty", "rwm",
                                          /* Allow the container
                                           * access to ptys. However,
                                           * do not permit the
                                           * container to ever create
                                           * these device nodes. */
                                          "/dev/pts/ptmx", "rw",
                                          "char-pts", "rw");
                if (r < 0) {
                        log_error("Failed to add device whitelist: %s", strerror(-r));
                        return r;
                }

                r = sd_bus_message_close_container(m);
                if (r < 0) {
                        log_error("Failed to close container: %s", strerror(-r));
                        return r;
                }

                r = sd_bus_call(bus, m, 0, &error, NULL);
        }

        if (r < 0) {
                log_error("Failed to register machine: %s", bus_error_message(&error, r));
                return r;
        }

        return 0;
}

static int terminate_machine(pid_t pid) {
        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
        _cleanup_bus_unref_ sd_bus *bus = NULL;
        const char *path;
        int r;

        if (!arg_register)
                return 0;

        r = sd_bus_default_system(&bus);
        if (r < 0) {
                log_error("Failed to open system bus: %s", strerror(-r));
                return r;
        }

        r = sd_bus_call_method(
                        bus,
                        "org.freedesktop.machine1",
                        "/org/freedesktop/machine1",
                        "org.freedesktop.machine1.Manager",
                        "GetMachineByPID",
                        &error,
                        &reply,
                        "u",
                        (uint32_t) pid);
        if (r < 0) {
                /* Note that the machine might already have been
                 * cleaned up automatically, hence don't consider it a
                 * failure if we cannot get the machine object. */
                log_debug("Failed to get machine: %s", bus_error_message(&error, r));
                return 0;
        }

        r = sd_bus_message_read(reply, "o", &path);
        if (r < 0)
                return bus_log_parse_error(r);

        r = sd_bus_call_method(
                        bus,
                        "org.freedesktop.machine1",
                        path,
                        "org.freedesktop.machine1.Machine",
                        "Terminate",
                        &error,
                        NULL,
                        NULL);
        if (r < 0) {
                log_debug("Failed to terminate machine: %s", bus_error_message(&error, r));
                return 0;
        }

        return 0;
}

static int reset_audit_loginuid(void) {
        _cleanup_free_ char *p = NULL;
        int r;

        if (arg_share_system)
                return 0;

        r = read_one_line_file("/proc/self/loginuid", &p);
        if (r == -EEXIST)
                return 0;
        if (r < 0) {
                log_error("Failed to read /proc/self/loginuid: %s", strerror(-r));
                return r;
        }

        /* Already reset? */
        if (streq(p, "4294967295"))
                return 0;

        r = write_string_file("/proc/self/loginuid", "4294967295");
        if (r < 0) {
                log_error("Failed to reset audit login UID. This probably means that your kernel is too\n"
                          "old and you have audit enabled. Note that the auditing subsystem is known to\n"
                          "be incompatible with containers on old kernels. Please make sure to upgrade\n"
                          "your kernel or to off auditing with 'audit=0' on the kernel command line before\n"
                          "using systemd-nspawn. Sleeping for 5s... (%s)\n", strerror(-r));

                sleep(5);
        }

        return 0;
}

static int setup_veth(pid_t pid, char iface_name[IFNAMSIZ]) {
        _cleanup_rtnl_message_unref_ sd_rtnl_message *m = NULL;
        _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
        int r;

        if (!arg_private_network)
                return 0;

        if (!arg_network_veth)
                return 0;

        /* Use two different interface name prefixes depending whether
         * we are in bridge mode or not. */
        if (arg_network_bridge)
                memcpy(iface_name, "vb-", 3);
        else
                memcpy(iface_name, "ve-", 3);

        strncpy(iface_name+3, arg_machine, IFNAMSIZ - 3);

        r = sd_rtnl_open(&rtnl, 0);
        if (r < 0) {
                log_error("Failed to connect to netlink: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_new_link(rtnl, &m, RTM_NEWLINK, 0);
        if (r < 0) {
                log_error("Failed to allocate netlink message: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_append_string(m, IFLA_IFNAME, iface_name);
        if (r < 0) {
                log_error("Failed to add netlink interface name: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_open_container(m, IFLA_LINKINFO);
        if (r < 0) {
                log_error("Failed to open netlink container: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_append_string(m, IFLA_INFO_KIND, "veth");
        if (r < 0) {
                log_error("Failed to append netlink kind: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_open_container(m, IFLA_INFO_DATA);
        if (r < 0) {
                log_error("Failed to open netlink container: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_open_container(m, VETH_INFO_PEER);
        if (r < 0) {
                log_error("Failed to open netlink container: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_append_string(m, IFLA_IFNAME, "host0");
        if (r < 0) {
                log_error("Failed to add netlink interface name: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_append_u32(m, IFLA_NET_NS_PID, pid);
        if (r < 0) {
                log_error("Failed to add netlink namespace field: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_close_container(m);
        if (r < 0) {
                log_error("Failed to close netlink container: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_close_container(m);
        if (r < 0) {
                log_error("Failed to close netlink container: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_close_container(m);
        if (r < 0) {
                log_error("Failed to close netlink container: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_call(rtnl, m, 0, NULL);
        if (r < 0) {
                log_error("Failed to add new veth interfaces: %s", strerror(-r));
                return r;
        }

        return 0;
}

static int setup_bridge(const char veth_name[]) {
        _cleanup_rtnl_message_unref_ sd_rtnl_message *m = NULL;
        _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
        int r, bridge;

        if (!arg_private_network)
                return 0;

        if (!arg_network_veth)
                return 0;

        if (!arg_network_bridge)
                return 0;

        bridge = (int) if_nametoindex(arg_network_bridge);
        if (bridge <= 0) {
                log_error("Failed to resolve interface %s: %m", arg_network_bridge);
                return -errno;
        }

        r = sd_rtnl_open(&rtnl, 0);
        if (r < 0) {
                log_error("Failed to connect to netlink: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_new_link(rtnl, &m, RTM_SETLINK, 0);
        if (r < 0) {
                log_error("Failed to allocate netlink message: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_append_string(m, IFLA_IFNAME, veth_name);
        if (r < 0) {
                log_error("Failed to add netlink interface name field: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_message_append_u32(m, IFLA_MASTER, bridge);
        if (r < 0) {
                log_error("Failed to add netlink master field: %s", strerror(-r));
                return r;
        }

        r = sd_rtnl_call(rtnl, m, 0, NULL);
        if (r < 0) {
                log_error("Failed to add veth interface to bridge: %s", strerror(-r));
                return r;
        }

        return 0;
}

static int move_network_interfaces(pid_t pid) {
        _cleanup_udev_unref_ struct udev *udev = NULL;
        _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
        char **i;
        int r;

        if (!arg_private_network)
                return 0;

        if (strv_isempty(arg_network_interfaces))
                return 0;

        r = sd_rtnl_open(&rtnl, 0);
        if (r < 0) {
                log_error("Failed to connect to netlink: %s", strerror(-r));
                return r;
        }

        udev = udev_new();
        if (!udev) {
                log_error("Failed to connect to udev.");
                return -ENOMEM;
        }

        STRV_FOREACH(i, arg_network_interfaces) {
                _cleanup_rtnl_message_unref_ sd_rtnl_message *m = NULL;
                _cleanup_udev_device_unref_ struct udev_device *d = NULL;
                char ifi_str[2 + DECIMAL_STR_MAX(int)];
                int ifi;

                ifi = (int) if_nametoindex(*i);
                if (ifi <= 0) {
                        log_error("Failed to resolve interface %s: %m", *i);
                        return -errno;
                }

                sprintf(ifi_str, "n%i", ifi);
                d = udev_device_new_from_device_id(udev, ifi_str);
                if (!d) {
                        log_error("Failed to get udev device for interface %s: %m", *i);
                        return -errno;
                }

                if (udev_device_get_is_initialized(d) <= 0) {
                        log_error("Network interface %s is not initialized yet.", *i);
                        return -EBUSY;
                }

                r = sd_rtnl_message_new_link(rtnl, &m, RTM_NEWLINK, ifi);
                if (r < 0) {
                        log_error("Failed to allocate netlink message: %s", strerror(-r));
                        return r;
                }

                r = sd_rtnl_message_append_u32(m, IFLA_NET_NS_PID, pid);
                if (r < 0) {
                        log_error("Failed to append namespace PID to netlink message: %s", strerror(-r));
                        return r;
                }

                r = sd_rtnl_call(rtnl, m, 0, NULL);
                if (r < 0) {
                        log_error("Failed to move interface %s to namespace: %s", *i, strerror(-r));
                        return r;
                }
        }

        return 0;
}

static int audit_still_doesnt_work_in_containers(void) {

#ifdef HAVE_SECCOMP
        scmp_filter_ctx seccomp;
        int r;

        /*
           Audit is broken in containers, much of the userspace audit
           hookup will fail if running inside a container. We don't
           care and just turn off creation of audit sockets.

           This will make socket(AF_NETLINK, *, NETLINK_AUDIT) fail
           with EAFNOSUPPORT which audit userspace uses as indication
           that audit is disabled in the kernel.
         */

        seccomp = seccomp_init(SCMP_ACT_ALLOW);
        if (!seccomp)
                return log_oom();

        r = seccomp_add_secondary_archs(seccomp);
        if (r < 0 && r != -EEXIST) {
                log_error("Failed to add secondary archs to seccomp filter: %s", strerror(-r));
                goto finish;
        }

        r = seccomp_rule_add(
                        seccomp,
                        SCMP_ACT_ERRNO(EAFNOSUPPORT),
                        SCMP_SYS(socket),
                        2,
                        SCMP_A0(SCMP_CMP_EQ, AF_NETLINK),
                        SCMP_A2(SCMP_CMP_EQ, NETLINK_AUDIT));
        if (r < 0) {
                log_error("Failed to add audit seccomp rule: %s", strerror(-r));
                goto finish;
        }

        r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0);
        if (r < 0) {
                log_error("Failed to unset NO_NEW_PRIVS: %s", strerror(-r));
                goto finish;
        }

        r = seccomp_load(seccomp);
        if (r < 0)
                log_error("Failed to install seccomp audit filter: %s", strerror(-r));

finish:
        seccomp_release(seccomp);
        return r;
#else
        return 0;
#endif

}

int main(int argc, char *argv[]) {

        _cleanup_close_ int master = -1, kdbus_fd = -1, sync_fd = -1;
        _cleanup_close_pipe_ int kmsg_socket_pair[2] = { -1, -1 };
        _cleanup_free_ char *kdbus_domain = NULL;
        _cleanup_fdset_free_ FDSet *fds = NULL;
        const char *console = NULL;
        int r = EXIT_FAILURE, k;
        int n_fd_passed;
        pid_t pid = 0;
        sigset_t mask;
        char veth_name[IFNAMSIZ];

        log_parse_environment();
        log_open();

        k = parse_argv(argc, argv);
        if (k < 0)
                goto finish;
        else if (k == 0) {
                r = EXIT_SUCCESS;
                goto finish;
        }

        if (arg_directory) {
                char *p;

                p = path_make_absolute_cwd(arg_directory);
                free(arg_directory);
                arg_directory = p;
        } else
                arg_directory = get_current_dir_name();

        if (!arg_directory) {
                log_error("Failed to determine path, please use -D.");
                goto finish;
        }

        path_kill_slashes(arg_directory);

        if (!arg_machine) {
                arg_machine = strdup(basename(arg_directory));
                if (!arg_machine) {
                        log_oom();
                        goto finish;
                }

                hostname_cleanup(arg_machine, false);
                if (isempty(arg_machine)) {
                        log_error("Failed to determine machine name automatically, please use -M.");
                        goto finish;
                }
        }

        if (geteuid() != 0) {
                log_error("Need to be root.");
                goto finish;
        }

        if (sd_booted() <= 0) {
                log_error("Not running on a systemd system.");
                goto finish;
        }

        if (path_equal(arg_directory, "/")) {
                log_error("Spawning container on root directory not supported.");
                goto finish;
        }

        if (arg_boot) {
                if (path_is_os_tree(arg_directory) <= 0) {
                        log_error("Directory %s doesn't look like an OS root directory (/etc/os-release is missing). Refusing.", arg_directory);
                        goto finish;
                }
        } else {
                const char *p;

                p = strappenda(arg_directory,
                               argc > optind && path_is_absolute(argv[optind]) ? argv[optind] : "/usr/bin/");
                if (access(p, F_OK) < 0) {
                        log_error("Directory %s lacks the binary to execute or doesn't look like a binary tree. Refusing.", arg_directory);
                        goto finish;

                }
        }

        log_close();
        n_fd_passed = sd_listen_fds(false);
        if (n_fd_passed > 0) {
                k = fdset_new_listen_fds(&fds, false);
                if (k < 0) {
                        log_error("Failed to collect file descriptors: %s", strerror(-k));
                        goto finish;
                }
        }
        fdset_close_others(fds);
        log_open();

        master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY);
        if (master < 0) {
                log_error("Failed to acquire pseudo tty: %m");
                goto finish;
        }

        console = ptsname(master);
        if (!console) {
                log_error("Failed to determine tty name: %m");
                goto finish;
        }

        if (!arg_quiet)
                log_info("Spawning container %s on %s. Press ^] three times within 1s to abort execution.", arg_machine, arg_directory);

        if (unlockpt(master) < 0) {
                log_error("Failed to unlock tty: %m");
                goto finish;
        }

        if (access("/dev/kdbus/control", F_OK) >= 0) {

                if (arg_share_system) {
                        kdbus_domain = strdup("/dev/kdbus");
                        if (!kdbus_domain) {
                                log_oom();
                                goto finish;
                        }
                } else {
                        const char *ns;

                        ns = strappenda("machine-", arg_machine);
                        kdbus_fd = bus_kernel_create_domain(ns, &kdbus_domain);
                        if (r < 0)
                                log_debug("Failed to create kdbus domain: %s", strerror(-r));
                        else
                                log_debug("Successfully created kdbus domain as %s", kdbus_domain);
                }
        }

        if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, kmsg_socket_pair) < 0) {
                log_error("Failed to create kmsg socket pair: %m");
                goto finish;
        }

        sd_notify(0, "READY=1");

        assert_se(sigemptyset(&mask) == 0);
        sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
        assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);

        for (;;) {
                siginfo_t status;

                sync_fd = eventfd(0, EFD_CLOEXEC);
                if (sync_fd < 0) {
                        log_error("Failed to create event fd: %m");
                        goto finish;
                }

                pid = syscall(__NR_clone,
                              SIGCHLD|CLONE_NEWNS|
                              (arg_share_system ? 0 : CLONE_NEWIPC|CLONE_NEWPID|CLONE_NEWUTS)|
                              (arg_private_network ? CLONE_NEWNET : 0), NULL);
                if (pid < 0) {
                        if (errno == EINVAL)
                                log_error("clone() failed, do you have namespace support enabled in your kernel? (You need UTS, IPC, PID and NET namespacing built in): %m");
                        else
                                log_error("clone() failed: %m");

                        goto finish;
                }

                if (pid == 0) {
                        /* child */
                        const char *home = NULL;
                        uid_t uid = (uid_t) -1;
                        gid_t gid = (gid_t) -1;
                        unsigned n_env = 2;
                        const char *envp[] = {
                                "PATH=" DEFAULT_PATH_SPLIT_USR,
                                "container=systemd-nspawn", /* LXC sets container=lxc, so follow the scheme here */
                                NULL, /* TERM */
                                NULL, /* HOME */
                                NULL, /* USER */
                                NULL, /* LOGNAME */
                                NULL, /* container_uuid */
                                NULL, /* LISTEN_FDS */
                                NULL, /* LISTEN_PID */
                                NULL
                        };
                        char **env_use;
                        eventfd_t x;

                        envp[n_env] = strv_find_prefix(environ, "TERM=");
                        if (envp[n_env])
                                n_env ++;

                        close_nointr_nofail(master);
                        master = -1;

                        close_nointr(STDIN_FILENO);
                        close_nointr(STDOUT_FILENO);
                        close_nointr(STDERR_FILENO);

                        close_nointr_nofail(kmsg_socket_pair[0]);
                        kmsg_socket_pair[0] = -1;

                        reset_all_signal_handlers();

                        assert_se(sigemptyset(&mask) == 0);
                        assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);

                        k = open_terminal(console, O_RDWR);
                        if (k != STDIN_FILENO) {
                                if (k >= 0) {
                                        close_nointr_nofail(k);
                                        k = -EINVAL;
                                }

                                log_error("Failed to open console: %s", strerror(-k));
                                goto child_fail;
                        }

                        if (dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO ||
                            dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO) {
                                log_error("Failed to duplicate console: %m");
                                goto child_fail;
                        }

                        if (setsid() < 0) {
                                log_error("setsid() failed: %m");
                                goto child_fail;
                        }

                        if (reset_audit_loginuid() < 0)
                                goto child_fail;

                        if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0) {
                                log_error("PR_SET_PDEATHSIG failed: %m");
                                goto child_fail;
                        }

                        /* Mark everything as slave, so that we still
                         * receive mounts from the real root, but don't
                         * propagate mounts to the real root. */
                        if (mount(NULL, "/", NULL, MS_SLAVE|MS_REC, NULL) < 0) {
                                log_error("MS_SLAVE|MS_REC failed: %m");
                                goto child_fail;
                        }

                        /* Turn directory into bind mount */
                        if (mount(arg_directory, arg_directory, "bind", MS_BIND|MS_REC, NULL) < 0) {
                                log_error("Failed to make bind mount.");
                                goto child_fail;
                        }

                        if (arg_read_only)
                                if (mount(arg_directory, arg_directory, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY|MS_REC, NULL) < 0) {
                                        log_error("Failed to make read-only.");
                                        goto child_fail;
                                }

                        if (mount_all(arg_directory) < 0)
                                goto child_fail;

                        if (copy_devnodes(arg_directory) < 0)
                                goto child_fail;

                        if (setup_ptmx(arg_directory) < 0)
                                goto child_fail;

                        dev_setup(arg_directory);

                        if (audit_still_doesnt_work_in_containers() < 0)
                                goto child_fail;

                        if (setup_dev_console(arg_directory, console) < 0)
                                goto child_fail;

                        if (setup_kmsg(arg_directory, kmsg_socket_pair[1]) < 0)
                                goto child_fail;

                        close_nointr_nofail(kmsg_socket_pair[1]);
                        kmsg_socket_pair[1] = -1;

                        if (setup_boot_id(arg_directory) < 0)
                                goto child_fail;

                        if (setup_timezone(arg_directory) < 0)
                                goto child_fail;

                        if (setup_resolv_conf(arg_directory) < 0)
                                goto child_fail;

                        if (setup_journal(arg_directory) < 0)
                                goto child_fail;

                        if (mount_binds(arg_directory, arg_bind, 0) < 0)
                                goto child_fail;

                        if (mount_binds(arg_directory, arg_bind_ro, MS_RDONLY) < 0)
                                goto child_fail;

                        if (setup_kdbus(arg_directory, kdbus_domain) < 0)
                                goto child_fail;

                        if (chdir(arg_directory) < 0) {
                                log_error("chdir(%s) failed: %m", arg_directory);
                                goto child_fail;
                        }

                        if (mount(arg_directory, "/", NULL, MS_MOVE, NULL) < 0) {
                                log_error("mount(MS_MOVE) failed: %m");
                                goto child_fail;
                        }

                        if (chroot(".") < 0) {
                                log_error("chroot() failed: %m");
                                goto child_fail;
                        }

                        if (chdir("/") < 0) {
                                log_error("chdir() failed: %m");
                                goto child_fail;
                        }

                        umask(0022);

                        if (arg_private_network)
                                loopback_setup();

                        if (drop_capabilities() < 0) {
                                log_error("drop_capabilities() failed: %m");
                                goto child_fail;
                        }

                        if (arg_user) {

                                /* Note that this resolves user names
                                 * inside the container, and hence
                                 * accesses the NSS modules from the
                                 * container and not the host. This is
                                 * a bit weird... */

                                if (get_user_creds((const char**)&arg_user, &uid, &gid, &home, NULL) < 0) {
                                        log_error("get_user_creds() failed: %m");
                                        goto child_fail;
                                }

                                if (mkdir_parents_label(home, 0775) < 0) {
                                        log_error("mkdir_parents_label() failed: %m");
                                        goto child_fail;
                                }

                                if (mkdir_safe_label(home, 0775, uid, gid) < 0) {
                                        log_error("mkdir_safe_label() failed: %m");
                                        goto child_fail;
                                }

                                if (initgroups((const char*)arg_user, gid) < 0) {
                                        log_error("initgroups() failed: %m");
                                        goto child_fail;
                                }

                                if (setresgid(gid, gid, gid) < 0) {
                                        log_error("setregid() failed: %m");
                                        goto child_fail;
                                }

                                if (setresuid(uid, uid, uid) < 0) {
                                        log_error("setreuid() failed: %m");
                                        goto child_fail;
                                }
                        } else {
                                /* Reset everything fully to 0, just in case */

                                if (setgroups(0, NULL) < 0) {
                                        log_error("setgroups() failed: %m");
                                        goto child_fail;
                                }

                                if (setresgid(0, 0, 0) < 0) {
                                        log_error("setregid() failed: %m");
                                        goto child_fail;
                                }

                                if (setresuid(0, 0, 0) < 0) {
                                        log_error("setreuid() failed: %m");
                                        goto child_fail;
                                }
                        }

                        if ((asprintf((char**)(envp + n_env++), "HOME=%s", home ? home: "/root") < 0) ||
                            (asprintf((char**)(envp + n_env++), "USER=%s", arg_user ? arg_user : "root") < 0) ||
                            (asprintf((char**)(envp + n_env++), "LOGNAME=%s", arg_user ? arg_user : "root") < 0)) {
                                log_oom();
                                goto child_fail;
                        }

                        if (!sd_id128_equal(arg_uuid, SD_ID128_NULL)) {
                                if (asprintf((char**)(envp + n_env++), "container_uuid=" SD_ID128_FORMAT_STR, SD_ID128_FORMAT_VAL(arg_uuid)) < 0) {
                                        log_oom();
                                        goto child_fail;
                                }
                        }

                        if (fdset_size(fds) > 0) {
                                k = fdset_cloexec(fds, false);
                                if (k < 0) {
                                        log_error("Failed to unset O_CLOEXEC for file descriptors.");
                                        goto child_fail;
                                }

                                if ((asprintf((char **)(envp + n_env++), "LISTEN_FDS=%u", n_fd_passed) < 0) ||
                                    (asprintf((char **)(envp + n_env++), "LISTEN_PID=1") < 0)) {
                                        log_oom();
                                        goto child_fail;
                                }
                        }

                        setup_hostname();

                        if (arg_personality != 0xffffffffLU) {
                                if (personality(arg_personality) < 0) {
                                        log_error("personality() failed: %m");
                                        goto child_fail;
                                }
                        }

                        eventfd_read(sync_fd, &x);
                        close_nointr_nofail(sync_fd);
                        sync_fd = -1;

                        if (!strv_isempty(arg_setenv)) {
                                char **n;

                                n = strv_env_merge(2, envp, arg_setenv);
                                if (!n) {
                                        log_oom();
                                        goto child_fail;
                                }

                                env_use = n;
                        } else
                                env_use = (char**) envp;

#ifdef HAVE_SELINUX
                        if (arg_selinux_context)
                                if (setexeccon(arg_selinux_context) < 0)
                                        log_error("setexeccon(\"%s\") failed: %m", arg_selinux_context);
#endif
                        if (arg_boot) {
                                char **a;
                                size_t l;

                                /* Automatically search for the init system */

                                l = 1 + argc - optind;
                                a = newa(char*, l + 1);
                                memcpy(a + 1, argv + optind, l * sizeof(char*));

                                a[0] = (char*) "/usr/lib/systemd/systemd";
                                execve(a[0], a, env_use);

                                a[0] = (char*) "/lib/systemd/systemd";
                                execve(a[0], a, env_use);

                                a[0] = (char*) "/sbin/init";
                                execve(a[0], a, env_use);
                        } else if (argc > optind)
                                execvpe(argv[optind], argv + optind, env_use);
                        else {
                                chdir(home ? home : "/root");
                                execle("/bin/bash", "-bash", NULL, env_use);
                                execle("/bin/sh", "-sh", NULL, env_use);
                        }

                        log_error("execv() failed: %m");

                child_fail:
                        _exit(EXIT_FAILURE);
                }

                fdset_free(fds);
                fds = NULL;

                r = register_machine(pid);
                if (r < 0)
                        goto finish;

                r = move_network_interfaces(pid);
                if (r < 0)
                        goto finish;

                r = setup_veth(pid, veth_name);
                if (r < 0)
                        goto finish;

                r = setup_bridge(veth_name);
                if (r < 0)
                        goto finish;

                eventfd_write(sync_fd, 1);
                close_nointr_nofail(sync_fd);
                sync_fd = -1;

                k = process_pty(master, &mask, arg_boot ? pid : 0, SIGRTMIN+3);
                if (k < 0) {
                        r = EXIT_FAILURE;
                        break;
                }

                if (!arg_quiet)
                        putc('\n', stdout);

                /* Kill if it is not dead yet anyway */
                terminate_machine(pid);

                /* Redundant, but better safe than sorry */
                kill(pid, SIGKILL);

                k = wait_for_terminate(pid, &status);
                pid = 0;

                if (k < 0) {
                        r = EXIT_FAILURE;
                        break;
                }

                if (status.si_code == CLD_EXITED) {
                        r = status.si_status;
                        if (status.si_status != 0) {
                                log_error("Container %s failed with error code %i.", arg_machine, status.si_status);
                                break;
                        }

                        if (!arg_quiet)
                                log_debug("Container %s exited successfully.", arg_machine);
                        break;
                } else if (status.si_code == CLD_KILLED &&
                           status.si_status == SIGINT) {

                        if (!arg_quiet)
                                log_info("Container %s has been shut down.", arg_machine);
                        r = 0;
                        break;
                } else if (status.si_code == CLD_KILLED &&
                           status.si_status == SIGHUP) {

                        if (!arg_quiet)
                                log_info("Container %s is being rebooted.", arg_machine);
                        continue;
                } else if (status.si_code == CLD_KILLED ||
                           status.si_code == CLD_DUMPED) {

                        log_error("Container %s terminated by signal %s.", arg_machine, signal_to_string(status.si_status));
                        r = EXIT_FAILURE;
                        break;
                } else {
                        log_error("Container %s failed due to unknown reason.", arg_machine);
                        r = EXIT_FAILURE;
                        break;
                }
        }

finish:
        if (pid > 0)
                kill(pid, SIGKILL);

        free(arg_directory);
        free(arg_machine);
        free(arg_setenv);
        free(arg_network_interfaces);

        return r;
}