nspawn: split out mount related functions into a new nspawn-mount.c file

6 files changed, 951 insertions, 835 deletions

diff --git a/Makefile.am b/Makefile.am
index 1a844acc13..ece3288467 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -2781,6 +2781,8 @@ systemd_nspawn_SOURCES = \
 	src/nspawn/nspawn.h \
 	src/nspawn/nspawn-settings.c \
 	src/nspawn/nspawn-settings.h \
+	src/nspawn/nspawn-mount.c \
+	src/nspawn/nspawn-mount.h \
 	src/core/mount-setup.c \
 	src/core/mount-setup.h \
 	src/core/loopback-setup.c \
diff --git a/src/nspawn/nspawn-mount.c b/src/nspawn/nspawn-mount.c
new file mode 100644
index 0000000000..5521e1bbe0
--- /dev/null
+++ b/src/nspawn/nspawn-mount.c
@@ -0,0 +1,870 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 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 <sys/mount.h>
+
+#include "util.h"
+#include "rm-rf.h"
+#include "strv.h"
+#include "path-util.h"
+#include "mkdir.h"
+#include "label.h"
+#include "set.h"
+#include "cgroup-util.h"
+
+#include "nspawn.h"
+#include "nspawn-mount.h"
+
+CustomMount* custom_mount_add(CustomMount **l, unsigned *n, CustomMountType t) {
+        CustomMount *c, *ret;
+
+        assert(l);
+        assert(n);
+        assert(t >= 0);
+        assert(t < _CUSTOM_MOUNT_TYPE_MAX);
+
+        c = realloc(*l, (*n + 1) * sizeof(CustomMount));
+        if (!c)
+                return NULL;
+
+        *l = c;
+        ret = *l + *n;
+        (*n)++;
+
+        *ret = (CustomMount) { .type = t };
+
+        return ret;
+}
+
+void custom_mount_free_all(CustomMount *l, unsigned n) {
+        unsigned i;
+
+        for (i = 0; i < n; i++) {
+                CustomMount *m = l + i;
+
+                free(m->source);
+                free(m->destination);
+                free(m->options);
+
+                if (m->work_dir) {
+                        (void) rm_rf(m->work_dir, REMOVE_ROOT|REMOVE_PHYSICAL);
+                        free(m->work_dir);
+                }
+
+                strv_free(m->lower);
+        }
+
+        free(l);
+}
+
+int custom_mount_compare(const void *a, const void *b) {
+        const CustomMount *x = a, *y = b;
+        int r;
+
+        r = path_compare(x->destination, y->destination);
+        if (r != 0)
+                return r;
+
+        if (x->type < y->type)
+                return -1;
+        if (x->type > y->type)
+                return 1;
+
+        return 0;
+}
+
+int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only) {
+        _cleanup_free_ char *source = NULL, *destination = NULL, *opts = NULL;
+        const char *p = s;
+        CustomMount *m;
+        int r;
+
+        assert(l);
+        assert(n);
+
+        r = extract_many_words(&p, ":", EXTRACT_DONT_COALESCE_SEPARATORS, &source, &destination, NULL);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EINVAL;
+
+        if (r == 1) {
+                destination = strdup(source);
+                if (!destination)
+                        return -ENOMEM;
+        }
+
+        if (r == 2 && !isempty(p)) {
+                opts = strdup(p);
+                if (!opts)
+                        return -ENOMEM;
+        }
+
+        if (!path_is_absolute(source))
+                return -EINVAL;
+
+        if (!path_is_absolute(destination))
+                return -EINVAL;
+
+        m = custom_mount_add(l, n, CUSTOM_MOUNT_BIND);
+        if (!m)
+                return log_oom();
+
+        m->source = source;
+        m->destination = destination;
+        m->read_only = read_only;
+        m->options = opts;
+
+        source = destination = opts = NULL;
+        return 0;
+}
+
+int tmpfs_mount_parse(CustomMount **l, unsigned *n, const char *s) {
+        _cleanup_free_ char *path = NULL, *opts = NULL;
+        const char *p = s;
+        CustomMount *m;
+        int r;
+
+        assert(l);
+        assert(n);
+        assert(s);
+
+        r = extract_first_word(&p, &path, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return -EINVAL;
+
+        if (isempty(p))
+                opts = strdup("mode=0755");
+        else
+                opts = strdup(p);
+        if (!opts)
+                return -ENOMEM;
+
+        if (!path_is_absolute(path))
+                return -EINVAL;
+
+        m = custom_mount_add(l, n, CUSTOM_MOUNT_TMPFS);
+        if (!m)
+                return -ENOMEM;
+
+        m->destination = path;
+        m->options = opts;
+
+        path = opts = NULL;
+        return 0;
+}
+
+static int tmpfs_patch_options(
+                const char *options,
+                bool userns, uid_t uid_shift, uid_t uid_range,
+                const char *selinux_apifs_context,
+                char **ret) {
+
+        char *buf = NULL;
+
+        if (userns && uid_shift != 0) {
+                assert(uid_shift != UID_INVALID);
+
+                if (options)
+                        (void) asprintf(&buf, "%s,uid=" UID_FMT ",gid=" UID_FMT, options, uid_shift, uid_shift);
+                else
+                        (void) asprintf(&buf, "uid=" UID_FMT ",gid=" UID_FMT, uid_shift, uid_shift);
+                if (!buf)
+                        return -ENOMEM;
+
+                options = buf;
+        }
+
+#ifdef HAVE_SELINUX
+        if (selinux_apifs_context) {
+                char *t;
+
+                if (options)
+                        t = strjoin(options, ",context=\"", selinux_apifs_context, "\"", NULL);
+                else
+                        t = strjoin("context=\"", selinux_apifs_context, "\"", NULL);
+                if (!t) {
+                        free(buf);
+                        return -ENOMEM;
+                }
+
+                free(buf);
+                buf = t;
+        }
+#endif
+
+        *ret = buf;
+        return !!buf;
+}
+
+int mount_all(const char *dest,
+              bool userns, uid_t uid_shift, uid_t uid_range,
+              const char *selinux_apifs_context) {
+
+        typedef struct MountPoint {
+                const char *what;
+                const char *where;
+                const char *type;
+                const char *options;
+                unsigned long flags;
+                bool fatal;
+                bool userns;
+        } MountPoint;
+
+        static const MountPoint mount_table[] = {
+                { "proc",      "/proc",          "proc",   NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV,                              true,  true  },
+                { "/proc/sys", "/proc/sys",      NULL,     NULL,        MS_BIND,                                                   true,  true  },   /* Bind mount first */
+                { NULL,        "/proc/sys",      NULL,     NULL,        MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, true,  true  },   /* Then, make it r/o */
+                { "sysfs",     "/sys",           "sysfs",  NULL,        MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV,                    true,  false },
+                { "tmpfs",     "/dev",           "tmpfs",  "mode=755",  MS_NOSUID|MS_STRICTATIME,                                  true,  false },
+                { "tmpfs",     "/dev/shm",       "tmpfs",  "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         true,  false },
+                { "tmpfs",     "/run",           "tmpfs",  "mode=755",  MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         true,  false },
+                { "tmpfs",     "/tmp",           "tmpfs",  "mode=1777", MS_STRICTATIME,                                            true,  false },
+#ifdef HAVE_SELINUX
+                { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL,     MS_BIND,                                                   false, false },  /* Bind mount first */
+                { NULL,              "/sys/fs/selinux", NULL, NULL,     MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, false, false },  /* Then, make it r/o */
+#endif
+        };
+
+        unsigned k;
+        int r;
+
+        for (k = 0; k < ELEMENTSOF(mount_table); k++) {
+                _cleanup_free_ char *where = NULL, *options = NULL;
+                const char *o;
+
+                if (userns != mount_table[k].userns)
+                        continue;
+
+                where = prefix_root(dest, mount_table[k].where);
+                if (!where)
+                        return log_oom();
+
+                r = path_is_mount_point(where, AT_SYMLINK_FOLLOW);
+                if (r < 0 && r != -ENOENT)
+                        return log_error_errno(r, "Failed to detect whether %s is a mount point: %m", where);
+
+                /* Skip this entry if it is not a remount. */
+                if (mount_table[k].what && r > 0)
+                        continue;
+
+                r = mkdir_p(where, 0755);
+                if (r < 0) {
+                        if (mount_table[k].fatal)
+                                return log_error_errno(r, "Failed to create directory %s: %m", where);
+
+                        log_warning_errno(r, "Failed to create directory %s: %m", where);
+                        continue;
+                }
+
+                o = mount_table[k].options;
+                if (streq_ptr(mount_table[k].type, "tmpfs")) {
+                        r = tmpfs_patch_options(o, userns, uid_shift, uid_range, selinux_apifs_context, &options);
+                        if (r < 0)
+                                return log_oom();
+                        if (r > 0)
+                                o = options;
+                }
+
+                if (mount(mount_table[k].what,
+                          where,
+                          mount_table[k].type,
+                          mount_table[k].flags,
+                          o) < 0) {
+
+                        if (mount_table[k].fatal)
+                                return log_error_errno(errno, "mount(%s) failed: %m", where);
+
+                        log_warning_errno(errno, "mount(%s) failed, ignoring: %m", where);
+                }
+        }
+
+        return 0;
+}
+
+static int parse_mount_bind_options(const char *options, unsigned long *mount_flags, char **mount_opts) {
+        const char *p = options;
+        unsigned long flags = *mount_flags;
+        char *opts = NULL;
+
+        assert(options);
+
+        for (;;) {
+                _cleanup_free_ char *word = NULL;
+                int r = extract_first_word(&p, &word, ",", 0);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to extract mount option: %m");
+                if (r == 0)
+                        break;
+
+                if (streq(word, "rbind"))
+                        flags |= MS_REC;
+                else if (streq(word, "norbind"))
+                        flags &= ~MS_REC;
+                else {
+                        log_error("Invalid bind mount option: %s", word);
+                        return -EINVAL;
+                }
+        }
+
+        *mount_flags = flags;
+        /* in the future mount_opts will hold string options for mount(2) */
+        *mount_opts = opts;
+
+        return 0;
+}
+
+static int mount_bind(const char *dest, CustomMount *m) {
+        struct stat source_st, dest_st;
+        const char *where;
+        unsigned long mount_flags = MS_BIND | MS_REC;
+        _cleanup_free_ char *mount_opts = NULL;
+        int r;
+
+        assert(m);
+
+        if (m->options) {
+                r = parse_mount_bind_options(m->options, &mount_flags, &mount_opts);
+                if (r < 0)
+                        return r;
+        }
+
+        if (stat(m->source, &source_st) < 0)
+                return log_error_errno(errno, "Failed to stat %s: %m", m->source);
+
+        where = prefix_roota(dest, m->destination);
+
+        if (stat(where, &dest_st) >= 0) {
+                if (S_ISDIR(source_st.st_mode) && !S_ISDIR(dest_st.st_mode)) {
+                        log_error("Cannot bind mount directory %s on file %s.", m->source, where);
+                        return -EINVAL;
+                }
+
+                if (!S_ISDIR(source_st.st_mode) && S_ISDIR(dest_st.st_mode)) {
+                        log_error("Cannot bind mount file %s on directory %s.", m->source, where);
+                        return -EINVAL;
+                }
+
+        } else if (errno == ENOENT) {
+                r = mkdir_parents_label(where, 0755);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to make parents of %s: %m", where);
+        } else {
+                log_error_errno(errno, "Failed to stat %s: %m", where);
+                return -errno;
+        }
+
+        /* Create the mount point. Any non-directory file can be
+         * mounted on any non-directory file (regular, fifo, socket,
+         * char, block).
+         */
+        if (S_ISDIR(source_st.st_mode))
+                r = mkdir_label(where, 0755);
+        else
+                r = touch(where);
+        if (r < 0 && r != -EEXIST)
+                return log_error_errno(r, "Failed to create mount point %s: %m", where);
+
+        if (mount(m->source, where, NULL, mount_flags, mount_opts) < 0)
+                return log_error_errno(errno, "mount(%s) failed: %m", where);
+
+        if (m->read_only) {
+                r = bind_remount_recursive(where, true);
+                if (r < 0)
+                        return log_error_errno(r, "Read-only bind mount failed: %m");
+        }
+
+        return 0;
+}
+
+static int mount_tmpfs(
+                const char *dest,
+                CustomMount *m,
+                bool userns, uid_t uid_shift, uid_t uid_range,
+                const char *selinux_apifs_context) {
+
+        const char *where, *options;
+        _cleanup_free_ char *buf = NULL;
+        int r;
+
+        assert(dest);
+        assert(m);
+
+        where = prefix_roota(dest, m->destination);
+
+        r = mkdir_p_label(where, 0755);
+        if (r < 0 && r != -EEXIST)
+                return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where);
+
+        r = tmpfs_patch_options(m->options, userns, uid_shift, uid_range, selinux_apifs_context, &buf);
+        if (r < 0)
+                return log_oom();
+        options = r > 0 ? buf : m->options;
+
+        if (mount("tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, options) < 0)
+                return log_error_errno(errno, "tmpfs mount to %s failed: %m", where);
+
+        return 0;
+}
+
+static char *joined_and_escaped_lower_dirs(char * const *lower) {
+        _cleanup_strv_free_ char **sv = NULL;
+
+        sv = strv_copy(lower);
+        if (!sv)
+                return NULL;
+
+        strv_reverse(sv);
+
+        if (!strv_shell_escape(sv, ",:"))
+                return NULL;
+
+        return strv_join(sv, ":");
+}
+
+static int mount_overlay(const char *dest, CustomMount *m) {
+        _cleanup_free_ char *lower = NULL;
+        const char *where, *options;
+        int r;
+
+        assert(dest);
+        assert(m);
+
+        where = prefix_roota(dest, m->destination);
+
+        r = mkdir_label(where, 0755);
+        if (r < 0 && r != -EEXIST)
+                return log_error_errno(r, "Creating mount point for overlay %s failed: %m", where);
+
+        (void) mkdir_p_label(m->source, 0755);
+
+        lower = joined_and_escaped_lower_dirs(m->lower);
+        if (!lower)
+                return log_oom();
+
+        if (m->read_only) {
+                _cleanup_free_ char *escaped_source = NULL;
+
+                escaped_source = shell_escape(m->source, ",:");
+                if (!escaped_source)
+                        return log_oom();
+
+                options = strjoina("lowerdir=", escaped_source, ":", lower);
+        } else {
+                _cleanup_free_ char *escaped_source = NULL, *escaped_work_dir = NULL;
+
+                assert(m->work_dir);
+                (void) mkdir_label(m->work_dir, 0700);
+
+                escaped_source = shell_escape(m->source, ",:");
+                if (!escaped_source)
+                        return log_oom();
+                escaped_work_dir = shell_escape(m->work_dir, ",:");
+                if (!escaped_work_dir)
+                        return log_oom();
+
+                options = strjoina("lowerdir=", lower, ",upperdir=", escaped_source, ",workdir=", escaped_work_dir);
+        }
+
+        if (mount("overlay", where, "overlay", m->read_only ? MS_RDONLY : 0, options) < 0)
+                return log_error_errno(errno, "overlay mount to %s failed: %m", where);
+
+        return 0;
+}
+
+int mount_custom(
+                const char *dest,
+                CustomMount *mounts, unsigned n,
+                bool userns, uid_t uid_shift, uid_t uid_range,
+                const char *selinux_apifs_context) {
+
+        unsigned i;
+        int r;
+
+        assert(dest);
+
+        for (i = 0; i < n; i++) {
+                CustomMount *m = mounts + i;
+
+                switch (m->type) {
+
+                case CUSTOM_MOUNT_BIND:
+                        r = mount_bind(dest, m);
+                        break;
+
+                case CUSTOM_MOUNT_TMPFS:
+                        r = mount_tmpfs(dest, m, userns, uid_shift, uid_range, selinux_apifs_context);
+                        break;
+
+                case CUSTOM_MOUNT_OVERLAY:
+                        r = mount_overlay(dest, m);
+                        break;
+
+                default:
+                        assert_not_reached("Unknown custom mount type");
+                }
+
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int mount_legacy_cgroup_hierarchy(const char *dest, const char *controller, const char *hierarchy, bool read_only) {
+        char *to;
+        int r;
+
+        to = strjoina(dest, "/sys/fs/cgroup/", hierarchy);
+
+        r = path_is_mount_point(to, 0);
+        if (r < 0 && r != -ENOENT)
+                return log_error_errno(r, "Failed to determine if %s is mounted already: %m", to);
+        if (r > 0)
+                return 0;
+
+        mkdir_p(to, 0755);
+
+        /* The superblock mount options of the mount point need to be
+         * identical to the hosts', and hence writable... */
+        if (mount("cgroup", to, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV, controller) < 0)
+                return log_error_errno(errno, "Failed to mount to %s: %m", to);
+
+        /* ... hence let's only make the bind mount read-only, not the
+         * superblock. */
+        if (read_only) {
+                if (mount(NULL, to, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL) < 0)
+                        return log_error_errno(errno, "Failed to remount %s read-only: %m", to);
+        }
+        return 1;
+}
+
+static int mount_legacy_cgroups(
+                const char *dest,
+                bool userns, uid_t uid_shift, uid_t uid_range,
+                const char *selinux_apifs_context) {
+
+        _cleanup_set_free_free_ Set *controllers = NULL;
+        const char *cgroup_root;
+        int r;
+
+        cgroup_root = prefix_roota(dest, "/sys/fs/cgroup");
+
+        /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */
+        r = path_is_mount_point(cgroup_root, AT_SYMLINK_FOLLOW);
+        if (r < 0)
+                return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m");
+        if (r == 0) {
+                _cleanup_free_ char *options = NULL;
+
+                r = tmpfs_patch_options("mode=755", userns, uid_shift, uid_range, selinux_apifs_context, &options);
+                if (r < 0)
+                        return log_oom();
+
+                if (mount("tmpfs", cgroup_root, "tmpfs", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options) < 0)
+                        return log_error_errno(errno, "Failed to mount /sys/fs/cgroup: %m");
+        }
+
+        if (cg_unified() > 0)
+                goto skip_controllers;
+
+        controllers = set_new(&string_hash_ops);
+        if (!controllers)
+                return log_oom();
+
+        r = cg_kernel_controllers(controllers);
+        if (r < 0)
+                return log_error_errno(r, "Failed to determine cgroup controllers: %m");
+
+        for (;;) {
+                _cleanup_free_ char *controller = NULL, *origin = NULL, *combined = NULL;
+
+                controller = set_steal_first(controllers);
+                if (!controller)
+                        break;
+
+                origin = prefix_root("/sys/fs/cgroup/", controller);
+                if (!origin)
+                        return log_oom();
+
+                r = readlink_malloc(origin, &combined);
+                if (r == -EINVAL) {
+                        /* Not a symbolic link, but directly a single cgroup hierarchy */
+
+                        r = mount_legacy_cgroup_hierarchy(dest, controller, controller, true);
+                        if (r < 0)
+                                return r;
+
+                } else if (r < 0)
+                        return log_error_errno(r, "Failed to read link %s: %m", origin);
+                else {
+                        _cleanup_free_ char *target = NULL;
+
+                        target = prefix_root(dest, origin);
+                        if (!target)
+                                return log_oom();
+
+                        /* A symbolic link, a combination of controllers in one hierarchy */
+
+                        if (!filename_is_valid(combined)) {
+                                log_warning("Ignoring invalid combined hierarchy %s.", combined);
+                                continue;
+                        }
+
+                        r = mount_legacy_cgroup_hierarchy(dest, combined, combined, true);
+                        if (r < 0)
+                                return r;
+
+                        r = symlink_idempotent(combined, target);
+                        if (r == -EINVAL) {
+                                log_error("Invalid existing symlink for combined hierarchy");
+                                return r;
+                        }
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m");
+                }
+        }
+
+skip_controllers:
+        r = mount_legacy_cgroup_hierarchy(dest, "none,name=systemd,xattr", "systemd", false);
+        if (r < 0)
+                return r;
+
+        if (mount(NULL, cgroup_root, NULL, MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755") < 0)
+                return log_error_errno(errno, "Failed to remount %s read-only: %m", cgroup_root);
+
+        return 0;
+}
+
+static int mount_unified_cgroups(const char *dest) {
+        const char *p;
+        int r;
+
+        assert(dest);
+
+        p = strjoina(dest, "/sys/fs/cgroup");
+
+        r = path_is_mount_point(p, AT_SYMLINK_FOLLOW);
+        if (r < 0)
+                return log_error_errno(r, "Failed to determine if %s is mounted already: %m", p);
+        if (r > 0) {
+                p = strjoina(dest, "/sys/fs/cgroup/cgroup.procs");
+                if (access(p, F_OK) >= 0)
+                        return 0;
+                if (errno != ENOENT)
+                        return log_error_errno(errno, "Failed to determine if mount point %s contains the unified cgroup hierarchy: %m", p);
+
+                log_error("%s is already mounted but not a unified cgroup hierarchy. Refusing.", p);
+                return -EINVAL;
+        }
+
+        if (mount("cgroup", p, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV, "__DEVEL__sane_behavior") < 0)
+                return log_error_errno(errno, "Failed to mount unified cgroup hierarchy to %s: %m", p);
+
+        return 0;
+}
+
+int mount_cgroups(
+                const char *dest,
+                bool unified_requested,
+                bool userns, uid_t uid_shift, uid_t uid_range,
+                const char *selinux_apifs_context) {
+
+        if (unified_requested)
+                return mount_unified_cgroups(dest);
+        else
+                return mount_legacy_cgroups(dest, userns, uid_shift, uid_range, selinux_apifs_context);
+}
+
+int mount_systemd_cgroup_writable(
+                const char *dest,
+                bool unified_requested) {
+
+        _cleanup_free_ char *own_cgroup_path = NULL;
+        const char *systemd_root, *systemd_own;
+        int r;
+
+        assert(dest);
+
+        r = cg_pid_get_path(NULL, 0, &own_cgroup_path);
+        if (r < 0)
+                return log_error_errno(r, "Failed to determine our own cgroup path: %m");
+
+        /* If we are living in the top-level, then there's nothing to do... */
+        if (path_equal(own_cgroup_path, "/"))
+                return 0;
+
+        if (unified_requested) {
+                systemd_own = strjoina(dest, "/sys/fs/cgroup", own_cgroup_path);
+                systemd_root = prefix_roota(dest, "/sys/fs/cgroup");
+        } else {
+                systemd_own = strjoina(dest, "/sys/fs/cgroup/systemd", own_cgroup_path);
+                systemd_root = prefix_roota(dest, "/sys/fs/cgroup/systemd");
+        }
+
+        /* Make our own cgroup a (writable) bind mount */
+        if (mount(systemd_own, systemd_own,  NULL, MS_BIND, NULL) < 0)
+                return log_error_errno(errno, "Failed to turn %s into a bind mount: %m", own_cgroup_path);
+
+        /* And then remount the systemd cgroup root read-only */
+        if (mount(NULL, systemd_root, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL) < 0)
+                return log_error_errno(errno, "Failed to mount cgroup root read-only: %m");
+
+        return 0;
+}
+
+int setup_volatile_state(
+                const char *directory,
+                VolatileMode mode,
+                bool userns, uid_t uid_shift, uid_t uid_range,
+                const char *selinux_apifs_context) {
+
+        _cleanup_free_ char *buf = NULL;
+        const char *p, *options;
+        int r;
+
+        assert(directory);
+
+        if (mode != VOLATILE_STATE)
+                return 0;
+
+        /* --volatile=state means we simply overmount /var
+           with a tmpfs, and the rest read-only. */
+
+        r = bind_remount_recursive(directory, true);
+        if (r < 0)
+                return log_error_errno(r, "Failed to remount %s read-only: %m", directory);
+
+        p = prefix_roota(directory, "/var");
+        r = mkdir(p, 0755);
+        if (r < 0 && errno != EEXIST)
+                return log_error_errno(errno, "Failed to create %s: %m", directory);
+
+        options = "mode=755";
+        r = tmpfs_patch_options(options, userns, uid_shift, uid_range, selinux_apifs_context, &buf);
+        if (r < 0)
+                return log_oom();
+        if (r > 0)
+                options = buf;
+
+        if (mount("tmpfs", p, "tmpfs", MS_STRICTATIME, options) < 0)
+                return log_error_errno(errno, "Failed to mount tmpfs to /var: %m");
+
+        return 0;
+}
+
+int setup_volatile(
+                const char *directory,
+                VolatileMode mode,
+                bool userns, uid_t uid_shift, uid_t uid_range,
+                const char *selinux_apifs_context) {
+
+        bool tmpfs_mounted = false, bind_mounted = false;
+        char template[] = "/tmp/nspawn-volatile-XXXXXX";
+        _cleanup_free_ char *buf = NULL;
+        const char *f, *t, *options;
+        int r;
+
+        assert(directory);
+
+        if (mode != VOLATILE_YES)
+                return 0;
+
+        /* --volatile=yes means we mount a tmpfs to the root dir, and
+           the original /usr to use inside it, and that read-only. */
+
+        if (!mkdtemp(template))
+                return log_error_errno(errno, "Failed to create temporary directory: %m");
+
+        options = "mode=755";
+        r = tmpfs_patch_options(options, userns, uid_shift, uid_range, selinux_apifs_context, &buf);
+        if (r < 0)
+                return log_oom();
+        if (r > 0)
+                options = buf;
+
+        if (mount("tmpfs", template, "tmpfs", MS_STRICTATIME, options) < 0) {
+                r = log_error_errno(errno, "Failed to mount tmpfs for root directory: %m");
+                goto fail;
+        }
+
+        tmpfs_mounted = true;
+
+        f = prefix_roota(directory, "/usr");
+        t = prefix_roota(template, "/usr");
+
+        r = mkdir(t, 0755);
+        if (r < 0 && errno != EEXIST) {
+                r = log_error_errno(errno, "Failed to create %s: %m", t);
+                goto fail;
+        }
+
+        if (mount(f, t, NULL, MS_BIND|MS_REC, NULL) < 0) {
+                r = log_error_errno(errno, "Failed to create /usr bind mount: %m");
+                goto fail;
+        }
+
+        bind_mounted = true;
+
+        r = bind_remount_recursive(t, true);
+        if (r < 0) {
+                log_error_errno(r, "Failed to remount %s read-only: %m", t);
+                goto fail;
+        }
+
+        if (mount(template, directory, NULL, MS_MOVE, NULL) < 0) {
+                r = log_error_errno(errno, "Failed to move root mount: %m");
+                goto fail;
+        }
+
+        (void) rmdir(template);
+
+        return 0;
+
+fail:
+        if (bind_mounted)
+                (void) umount(t);
+
+        if (tmpfs_mounted)
+                (void) umount(template);
+        (void) rmdir(template);
+        return r;
+}
+
+VolatileMode volatile_mode_from_string(const char *s) {
+        int b;
+
+        if (isempty(s))
+                return _VOLATILE_MODE_INVALID;
+
+        b = parse_boolean(s);
+        if (b > 0)
+                return VOLATILE_YES;
+        if (b == 0)
+                return VOLATILE_NO;
+
+        if (streq(s, "state"))
+                return VOLATILE_STATE;
+
+        return _VOLATILE_MODE_INVALID;
+}
diff --git a/src/nspawn/nspawn-mount.h b/src/nspawn/nspawn-mount.h
new file mode 100644
index 0000000000..5abd44cc4b
--- /dev/null
+++ b/src/nspawn/nspawn-mount.h
@@ -0,0 +1,70 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 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 <stdbool.h>
+
+typedef enum VolatileMode {
+        VOLATILE_NO,
+        VOLATILE_YES,
+        VOLATILE_STATE,
+        _VOLATILE_MODE_MAX,
+        _VOLATILE_MODE_INVALID = -1
+} VolatileMode;
+
+typedef enum CustomMountType {
+        CUSTOM_MOUNT_BIND,
+        CUSTOM_MOUNT_TMPFS,
+        CUSTOM_MOUNT_OVERLAY,
+        _CUSTOM_MOUNT_TYPE_MAX,
+        _CUSTOM_MOUNT_TYPE_INVALID = -1
+} CustomMountType;
+
+typedef struct CustomMount {
+        CustomMountType type;
+        bool read_only;
+        char *source; /* for overlayfs this is the upper directory */
+        char *destination;
+        char *options;
+        char *work_dir;
+        char **lower;
+} CustomMount;
+
+CustomMount* custom_mount_add(CustomMount **l, unsigned *n, CustomMountType t);
+
+void custom_mount_free_all(CustomMount *l, unsigned n);
+int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only);
+int tmpfs_mount_parse(CustomMount **l, unsigned *n, const char *s);
+
+int custom_mount_compare(const void *a, const void *b);
+
+int mount_all(const char *dest, bool userns, uid_t uid_shift, uid_t uid_range, const char *selinux_apifs_context);
+
+int mount_cgroups(const char *dest, bool unified_requested, bool userns, uid_t uid_shift, uid_t uid_range, const char *selinux_apifs_context);
+int mount_systemd_cgroup_writable(const char *dest, bool unified_requested);
+
+int mount_custom(const char *dest, CustomMount *mounts, unsigned n, bool userns, uid_t uid_shift, uid_t uid_range, const char *selinux_apifs_context);
+
+int setup_volatile(const char *directory, VolatileMode mode, bool userns, uid_t uid_shift, uid_t uid_range, const char *selinux_apifs_context);
+int setup_volatile_state(const char *directory, VolatileMode mode, bool userns, uid_t uid_shift, uid_t uid_range, const char *selinux_apifs_context);
+
+VolatileMode volatile_mode_from_string(const char *s);
diff --git a/src/nspawn/nspawn-settings.h b/src/nspawn/nspawn-settings.h
index d9b3b2f7c0..24adbe2d5d 100644
--- a/src/nspawn/nspawn-settings.h
+++ b/src/nspawn/nspawn-settings.h
@@ -25,6 +25,7 @@
 
 #include "macro.h"
 #include "nspawn.h"
+#include "nspawn-mount.h"
 
 typedef enum SettingsMask {
         SETTING_BOOT          = 1 << 0,
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index a8afcd1466..c249017c43 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -104,6 +104,7 @@
 
 #include "nspawn.h"
 #include "nspawn-settings.h"
+#include "nspawn-mount.h"
 
 typedef enum ContainerStatus {
         CONTAINER_TERMINATED,
@@ -256,63 +257,6 @@ static void help(void) {
                , program_invocation_short_name);
 }
 
-static CustomMount* custom_mount_add(CustomMount **l, unsigned *n, CustomMountType t) {
-        CustomMount *c, *ret;
-
-        assert(l);
-        assert(n);
-        assert(t >= 0);
-        assert(t < _CUSTOM_MOUNT_TYPE_MAX);
-
-        c = realloc(*l, (*n + 1) * sizeof(CustomMount));
-        if (!c)
-                return NULL;
-
-        *l = c;
-        ret = *l + *n;
-        (*n)++;
-
-        *ret = (CustomMount) { .type = t };
-
-        return ret;
-}
-
-void custom_mount_free_all(CustomMount *l, unsigned n) {
-        unsigned i;
-
-        for (i = 0; i < n; i++) {
-                CustomMount *m = l + i;
-
-                free(m->source);
-                free(m->destination);
-                free(m->options);
-
-                if (m->work_dir) {
-                        (void) rm_rf(m->work_dir, REMOVE_ROOT|REMOVE_PHYSICAL);
-                        free(m->work_dir);
-                }
-
-                strv_free(m->lower);
-        }
-
-        free(l);
-}
-
-static int custom_mount_compare(const void *a, const void *b) {
-        const CustomMount *x = a, *y = b;
-        int r;
-
-        r = path_compare(x->destination, y->destination);
-        if (r != 0)
-                return r;
-
-        if (x->type < y->type)
-                return -1;
-        if (x->type > y->type)
-                return 1;
-
-        return 0;
-}
 
 static int custom_mounts_prepare(void) {
         unsigned i;
@@ -392,24 +336,6 @@ static int detect_unified_cgroup_hierarchy(void) {
         return 0;
 }
 
-VolatileMode volatile_mode_from_string(const char *s) {
-        int b;
-
-        if (isempty(s))
-                return _VOLATILE_MODE_INVALID;
-
-        b = parse_boolean(s);
-        if (b > 0)
-                return VOLATILE_YES;
-        if (b == 0)
-                return VOLATILE_NO;
-
-        if (streq(s, "state"))
-                return VOLATILE_STATE;
-
-        return _VOLATILE_MODE_INVALID;
-}
-
 int expose_port_parse(ExposePort **l, const char *s) {
 
         const char *split, *e;
@@ -464,89 +390,6 @@ int expose_port_parse(ExposePort **l, const char *s) {
         return 0;
 }
 
-int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only) {
-        _cleanup_free_ char *source = NULL, *destination = NULL, *opts = NULL;
-        const char *p = s;
-        CustomMount *m;
-        int r;
-
-        assert(l);
-        assert(n);
-
-        r = extract_many_words(&p, ":", EXTRACT_DONT_COALESCE_SEPARATORS, &source, &destination, NULL);
-        if (r < 0)
-                return r;
-        if (r == 0)
-                return -EINVAL;
-
-        if (r == 1) {
-                destination = strdup(source);
-                if (!destination)
-                        return -ENOMEM;
-        }
-
-        if (r == 2 && !isempty(p)) {
-                opts = strdup(p);
-                if (!opts)
-                        return -ENOMEM;
-        }
-
-        if (!path_is_absolute(source))
-                return -EINVAL;
-
-        if (!path_is_absolute(destination))
-                return -EINVAL;
-
-        m = custom_mount_add(l, n, CUSTOM_MOUNT_BIND);
-        if (!m)
-                return log_oom();
-
-        m->source = source;
-        m->destination = destination;
-        m->read_only = read_only;
-        m->options = opts;
-
-        source = destination = opts = NULL;
-        return 0;
-}
-
-int tmpfs_mount_parse(CustomMount **l, unsigned *n, const char *s) {
-        _cleanup_free_ char *path = NULL, *opts = NULL;
-        const char *p = s;
-        CustomMount *m;
-        int r;
-
-        assert(l);
-        assert(n);
-        assert(s);
-
-        r = extract_first_word(&p, &path, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
-        if (r < 0)
-                return r;
-        if (r == 0)
-                return -EINVAL;
-
-        if (isempty(p))
-                opts = strdup("mode=0755");
-        else
-                opts = strdup(p);
-        if (!opts)
-                return -ENOMEM;
-
-        if (!path_is_absolute(path))
-                return -EINVAL;
-
-        m = custom_mount_add(l, n, CUSTOM_MOUNT_TMPFS);
-        if (!m)
-                return -ENOMEM;
-
-        m->destination = path;
-        m->options = opts;
-
-        path = opts = NULL;
-        return 0;
-}
-
 static int parse_argv(int argc, char *argv[]) {
 
         enum {
@@ -1170,536 +1013,6 @@ static int verify_arguments(void) {
         return 0;
 }
 
-static int tmpfs_patch_options(const char *options, char **ret) {
-        char *buf = NULL;
-
-        if (arg_userns && arg_uid_shift != 0) {
-                assert(arg_uid_shift != UID_INVALID);
-
-                if (options)
-                        (void) asprintf(&buf, "%s,uid=" UID_FMT ",gid=" UID_FMT, options, arg_uid_shift, arg_uid_shift);
-                else
-                        (void) asprintf(&buf, "uid=" UID_FMT ",gid=" UID_FMT, arg_uid_shift, arg_uid_shift);
-                if (!buf)
-                        return -ENOMEM;
-
-                options = buf;
-        }
-
-#ifdef HAVE_SELINUX
-        if (arg_selinux_apifs_context) {
-                char *t;
-
-                if (options)
-                        t = strjoin(options, ",context=\"", arg_selinux_apifs_context, "\"", NULL);
-                else
-                        t = strjoin("context=\"", arg_selinux_apifs_context, "\"", NULL);
-                if (!t) {
-                        free(buf);
-                        return -ENOMEM;
-                }
-
-                free(buf);
-                buf = t;
-        }
-#endif
-
-        *ret = buf;
-        return !!buf;
-}
-
-static int mount_all(const char *dest, bool userns) {
-
-        typedef struct MountPoint {
-                const char *what;
-                const char *where;
-                const char *type;
-                const char *options;
-                unsigned long flags;
-                bool fatal;
-                bool userns;
-        } MountPoint;
-
-        static const MountPoint mount_table[] = {
-                { "proc",      "/proc",          "proc",   NULL,        MS_NOSUID|MS_NOEXEC|MS_NODEV,                              true,  true  },
-                { "/proc/sys", "/proc/sys",      NULL,     NULL,        MS_BIND,                                                   true,  true  },   /* Bind mount first */
-                { NULL,        "/proc/sys",      NULL,     NULL,        MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, true,  true  },   /* Then, make it r/o */
-                { "sysfs",     "/sys",           "sysfs",  NULL,        MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV,                    true,  false },
-                { "tmpfs",     "/dev",           "tmpfs",  "mode=755",  MS_NOSUID|MS_STRICTATIME,                                  true,  false },
-                { "tmpfs",     "/dev/shm",       "tmpfs",  "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         true,  false },
-                { "tmpfs",     "/run",           "tmpfs",  "mode=755",  MS_NOSUID|MS_NODEV|MS_STRICTATIME,                         true,  false },
-                { "tmpfs",     "/tmp",           "tmpfs",  "mode=1777", MS_STRICTATIME,                                            true,  false },
-#ifdef HAVE_SELINUX
-                { "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL,     MS_BIND,                                                   false, false },  /* Bind mount first */
-                { NULL,              "/sys/fs/selinux", NULL, NULL,     MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, false, false },  /* Then, make it r/o */
-#endif
-        };
-
-        unsigned k;
-        int r;
-
-        for (k = 0; k < ELEMENTSOF(mount_table); k++) {
-                _cleanup_free_ char *where = NULL, *options = NULL;
-                const char *o;
-
-                if (userns != mount_table[k].userns)
-                        continue;
-
-                where = prefix_root(dest, mount_table[k].where);
-                if (!where)
-                        return log_oom();
-
-                r = path_is_mount_point(where, AT_SYMLINK_FOLLOW);
-                if (r < 0 && r != -ENOENT)
-                        return log_error_errno(r, "Failed to detect whether %s is a mount point: %m", where);
-
-                /* Skip this entry if it is not a remount. */
-                if (mount_table[k].what && r > 0)
-                        continue;
-
-                r = mkdir_p(where, 0755);
-                if (r < 0) {
-                        if (mount_table[k].fatal)
-                                return log_error_errno(r, "Failed to create directory %s: %m", where);
-
-                        log_warning_errno(r, "Failed to create directory %s: %m", where);
-                        continue;
-                }
-
-                o = mount_table[k].options;
-                if (streq_ptr(mount_table[k].type, "tmpfs")) {
-                        r = tmpfs_patch_options(o, &options);
-                        if (r < 0)
-                                return log_oom();
-                        if (r > 0)
-                                o = options;
-                }
-
-                if (mount(mount_table[k].what,
-                          where,
-                          mount_table[k].type,
-                          mount_table[k].flags,
-                          o) < 0) {
-
-                        if (mount_table[k].fatal)
-                                return log_error_errno(errno, "mount(%s) failed: %m", where);
-
-                        log_warning_errno(errno, "mount(%s) failed, ignoring: %m", where);
-                }
-        }
-
-        return 0;
-}
-
-static int parse_mount_bind_options(const char *options, unsigned long *mount_flags, char **mount_opts) {
-        const char *p = options;
-        unsigned long flags = *mount_flags;
-        char *opts = NULL;
-
-        assert(options);
-
-        for (;;) {
-                _cleanup_free_ char *word = NULL;
-                int r = extract_first_word(&p, &word, ",", 0);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to extract mount option: %m");
-                if (r == 0)
-                        break;
-
-                if (streq(word, "rbind"))
-                        flags |= MS_REC;
-                else if (streq(word, "norbind"))
-                        flags &= ~MS_REC;
-                else {
-                        log_error("Invalid bind mount option: %s", word);
-                        return -EINVAL;
-                }
-        }
-
-        *mount_flags = flags;
-        /* in the future mount_opts will hold string options for mount(2) */
-        *mount_opts = opts;
-
-        return 0;
-}
-
-static int mount_bind(const char *dest, CustomMount *m) {
-        struct stat source_st, dest_st;
-        const char *where;
-        unsigned long mount_flags = MS_BIND | MS_REC;
-        _cleanup_free_ char *mount_opts = NULL;
-        int r;
-
-        assert(m);
-
-        if (m->options) {
-                r = parse_mount_bind_options(m->options, &mount_flags, &mount_opts);
-                if (r < 0)
-                        return r;
-        }
-
-        if (stat(m->source, &source_st) < 0)
-                return log_error_errno(errno, "Failed to stat %s: %m", m->source);
-
-        where = prefix_roota(dest, m->destination);
-
-        if (stat(where, &dest_st) >= 0) {
-                if (S_ISDIR(source_st.st_mode) && !S_ISDIR(dest_st.st_mode)) {
-                        log_error("Cannot bind mount directory %s on file %s.", m->source, where);
-                        return -EINVAL;
-                }
-
-                if (!S_ISDIR(source_st.st_mode) && S_ISDIR(dest_st.st_mode)) {
-                        log_error("Cannot bind mount file %s on directory %s.", m->source, where);
-                        return -EINVAL;
-                }
-
-        } else if (errno == ENOENT) {
-                r = mkdir_parents_label(where, 0755);
-                if (r < 0)
-                        return log_error_errno(r, "Failed to make parents of %s: %m", where);
-        } else {
-                log_error_errno(errno, "Failed to stat %s: %m", where);
-                return -errno;
-        }
-
-        /* Create the mount point. Any non-directory file can be
-         * mounted on any non-directory file (regular, fifo, socket,
-         * char, block).
-         */
-        if (S_ISDIR(source_st.st_mode))
-                r = mkdir_label(where, 0755);
-        else
-                r = touch(where);
-        if (r < 0 && r != -EEXIST)
-                return log_error_errno(r, "Failed to create mount point %s: %m", where);
-
-        if (mount(m->source, where, NULL, mount_flags, mount_opts) < 0)
-                return log_error_errno(errno, "mount(%s) failed: %m", where);
-
-        if (m->read_only) {
-                r = bind_remount_recursive(where, true);
-                if (r < 0)
-                        return log_error_errno(r, "Read-only bind mount failed: %m");
-        }
-
-        return 0;
-}
-
-static int mount_tmpfs(const char *dest, CustomMount *m) {
-        const char *where, *options;
-        _cleanup_free_ char *buf = NULL;
-        int r;
-
-        assert(dest);
-        assert(m);
-
-        where = prefix_roota(dest, m->destination);
-
-        r = mkdir_p_label(where, 0755);
-        if (r < 0 && r != -EEXIST)
-                return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where);
-
-        r = tmpfs_patch_options(m->options, &buf);
-        if (r < 0)
-                return log_oom();
-        options = r > 0 ? buf : m->options;
-
-        if (mount("tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, options) < 0)
-                return log_error_errno(errno, "tmpfs mount to %s failed: %m", where);
-
-        return 0;
-}
-
-static char *joined_and_escaped_lower_dirs(char * const *lower) {
-        _cleanup_strv_free_ char **sv = NULL;
-
-        sv = strv_copy(lower);
-        if (!sv)
-                return NULL;
-
-        strv_reverse(sv);
-
-        if (!strv_shell_escape(sv, ",:"))
-                return NULL;
-
-        return strv_join(sv, ":");
-}
-
-static int mount_overlay(const char *dest, CustomMount *m) {
-        _cleanup_free_ char *lower = NULL;
-        const char *where, *options;
-        int r;
-
-        assert(dest);
-        assert(m);
-
-        where = prefix_roota(dest, m->destination);
-
-        r = mkdir_label(where, 0755);
-        if (r < 0 && r != -EEXIST)
-                return log_error_errno(r, "Creating mount point for overlay %s failed: %m", where);
-
-        (void) mkdir_p_label(m->source, 0755);
-
-        lower = joined_and_escaped_lower_dirs(m->lower);
-        if (!lower)
-                return log_oom();
-
-        if (m->read_only) {
-                _cleanup_free_ char *escaped_source = NULL;
-
-                escaped_source = shell_escape(m->source, ",:");
-                if (!escaped_source)
-                        return log_oom();
-
-                options = strjoina("lowerdir=", escaped_source, ":", lower);
-        } else {
-                _cleanup_free_ char *escaped_source = NULL, *escaped_work_dir = NULL;
-
-                assert(m->work_dir);
-                (void) mkdir_label(m->work_dir, 0700);
-
-                escaped_source = shell_escape(m->source, ",:");
-                if (!escaped_source)
-                        return log_oom();
-                escaped_work_dir = shell_escape(m->work_dir, ",:");
-                if (!escaped_work_dir)
-                        return log_oom();
-
-                options = strjoina("lowerdir=", lower, ",upperdir=", escaped_source, ",workdir=", escaped_work_dir);
-        }
-
-        if (mount("overlay", where, "overlay", m->read_only ? MS_RDONLY : 0, options) < 0)
-                return log_error_errno(errno, "overlay mount to %s failed: %m", where);
-
-        return 0;
-}
-
-static int mount_custom(const char *dest) {
-        unsigned i;
-        int r;
-
-        assert(dest);
-
-        for (i = 0; i < arg_n_custom_mounts; i++) {
-                CustomMount *m = &arg_custom_mounts[i];
-
-                switch (m->type) {
-
-                case CUSTOM_MOUNT_BIND:
-                        r = mount_bind(dest, m);
-                        break;
-
-                case CUSTOM_MOUNT_TMPFS:
-                        r = mount_tmpfs(dest, m);
-                        break;
-
-                case CUSTOM_MOUNT_OVERLAY:
-                        r = mount_overlay(dest, m);
-                        break;
-
-                default:
-                        assert_not_reached("Unknown custom mount type");
-                }
-
-                if (r < 0)
-                        return r;
-        }
-
-        return 0;
-}
-
-static int mount_legacy_cgroup_hierarchy(const char *dest, const char *controller, const char *hierarchy, bool read_only) {
-        char *to;
-        int r;
-
-        to = strjoina(dest, "/sys/fs/cgroup/", hierarchy);
-
-        r = path_is_mount_point(to, 0);
-        if (r < 0 && r != -ENOENT)
-                return log_error_errno(r, "Failed to determine if %s is mounted already: %m", to);
-        if (r > 0)
-                return 0;
-
-        mkdir_p(to, 0755);
-
-        /* The superblock mount options of the mount point need to be
-         * identical to the hosts', and hence writable... */
-        if (mount("cgroup", to, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV, controller) < 0)
-                return log_error_errno(errno, "Failed to mount to %s: %m", to);
-
-        /* ... hence let's only make the bind mount read-only, not the
-         * superblock. */
-        if (read_only) {
-                if (mount(NULL, to, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL) < 0)
-                        return log_error_errno(errno, "Failed to remount %s read-only: %m", to);
-        }
-        return 1;
-}
-
-static int mount_legacy_cgroups(const char *dest) {
-        _cleanup_set_free_free_ Set *controllers = NULL;
-        const char *cgroup_root;
-        int r;
-
-        cgroup_root = prefix_roota(dest, "/sys/fs/cgroup");
-
-        /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */
-        r = path_is_mount_point(cgroup_root, AT_SYMLINK_FOLLOW);
-        if (r < 0)
-                return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m");
-        if (r == 0) {
-                _cleanup_free_ char *options = NULL;
-
-                r = tmpfs_patch_options("mode=755", &options);
-                if (r < 0)
-                        return log_oom();
-
-                if (mount("tmpfs", cgroup_root, "tmpfs", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options) < 0)
-                        return log_error_errno(errno, "Failed to mount /sys/fs/cgroup: %m");
-        }
-
-        if (cg_unified() > 0)
-                goto skip_controllers;
-
-        controllers = set_new(&string_hash_ops);
-        if (!controllers)
-                return log_oom();
-
-        r = cg_kernel_controllers(controllers);
-        if (r < 0)
-                return log_error_errno(r, "Failed to determine cgroup controllers: %m");
-
-        for (;;) {
-                _cleanup_free_ char *controller = NULL, *origin = NULL, *combined = NULL;
-
-                controller = set_steal_first(controllers);
-                if (!controller)
-                        break;
-
-                origin = prefix_root("/sys/fs/cgroup/", controller);
-                if (!origin)
-                        return log_oom();
-
-                r = readlink_malloc(origin, &combined);
-                if (r == -EINVAL) {
-                        /* Not a symbolic link, but directly a single cgroup hierarchy */
-
-                        r = mount_legacy_cgroup_hierarchy(dest, controller, controller, true);
-                        if (r < 0)
-                                return r;
-
-                } else if (r < 0)
-                        return log_error_errno(r, "Failed to read link %s: %m", origin);
-                else {
-                        _cleanup_free_ char *target = NULL;
-
-                        target = prefix_root(dest, origin);
-                        if (!target)
-                                return log_oom();
-
-                        /* A symbolic link, a combination of controllers in one hierarchy */
-
-                        if (!filename_is_valid(combined)) {
-                                log_warning("Ignoring invalid combined hierarchy %s.", combined);
-                                continue;
-                        }
-
-                        r = mount_legacy_cgroup_hierarchy(dest, combined, combined, true);
-                        if (r < 0)
-                                return r;
-
-                        r = symlink_idempotent(combined, target);
-                        if (r == -EINVAL) {
-                                log_error("Invalid existing symlink for combined hierarchy");
-                                return r;
-                        }
-                        if (r < 0)
-                                return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m");
-                }
-        }
-
-skip_controllers:
-        r = mount_legacy_cgroup_hierarchy(dest, "none,name=systemd,xattr", "systemd", false);
-        if (r < 0)
-                return r;
-
-        if (mount(NULL, cgroup_root, NULL, MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755") < 0)
-                return log_error_errno(errno, "Failed to remount %s read-only: %m", cgroup_root);
-
-        return 0;
-}
-
-static int mount_unified_cgroups(const char *dest) {
-        const char *p;
-        int r;
-
-        assert(dest);
-
-        p = strjoina(dest, "/sys/fs/cgroup");
-
-        r = path_is_mount_point(p, AT_SYMLINK_FOLLOW);
-        if (r < 0)
-                return log_error_errno(r, "Failed to determine if %s is mounted already: %m", p);
-        if (r > 0) {
-                p = strjoina(dest, "/sys/fs/cgroup/cgroup.procs");
-                if (access(p, F_OK) >= 0)
-                        return 0;
-                if (errno != ENOENT)
-                        return log_error_errno(errno, "Failed to determine if mount point %s contains the unified cgroup hierarchy: %m", p);
-
-                log_error("%s is already mounted but not a unified cgroup hierarchy. Refusing.", p);
-                return -EINVAL;
-        }
-
-        if (mount("cgroup", p, "cgroup", MS_NOSUID|MS_NOEXEC|MS_NODEV, "__DEVEL__sane_behavior") < 0)
-                return log_error_errno(errno, "Failed to mount unified cgroup hierarchy to %s: %m", p);
-
-        return 0;
-}
-
-static int mount_cgroups(const char *dest) {
-        if (arg_unified_cgroup_hierarchy)
-                return mount_unified_cgroups(dest);
-        else
-                return mount_legacy_cgroups(dest);
-}
-
-static int mount_systemd_cgroup_writable(const char *dest) {
-        _cleanup_free_ char *own_cgroup_path = NULL;
-        const char *systemd_root, *systemd_own;
-        int r;
-
-        assert(dest);
-
-        r = cg_pid_get_path(NULL, 0, &own_cgroup_path);
-        if (r < 0)
-                return log_error_errno(r, "Failed to determine our own cgroup path: %m");
-
-        /* If we are living in the top-level, then there's nothing to do... */
-        if (path_equal(own_cgroup_path, "/"))
-                return 0;
-
-        if (arg_unified_cgroup_hierarchy) {
-                systemd_own = strjoina(dest, "/sys/fs/cgroup", own_cgroup_path);
-                systemd_root = prefix_roota(dest, "/sys/fs/cgroup");
-        } else {
-                systemd_own = strjoina(dest, "/sys/fs/cgroup/systemd", own_cgroup_path);
-                systemd_root = prefix_roota(dest, "/sys/fs/cgroup/systemd");
-        }
-
-        /* Make our own cgroup a (writable) bind mount */
-        if (mount(systemd_own, systemd_own,  NULL, MS_BIND, NULL) < 0)
-                return log_error_errno(errno, "Failed to turn %s into a bind mount: %m", own_cgroup_path);
-
-        /* And then remount the systemd cgroup root read-only */
-        if (mount(NULL, systemd_root, NULL, MS_BIND|MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, NULL) < 0)
-                return log_error_errno(errno, "Failed to mount cgroup root read-only: %m");
-
-        return 0;
-}
-
 static int userns_lchown(const char *p, uid_t uid, gid_t gid) {
         assert(p);
 
@@ -1837,114 +1150,6 @@ static int setup_resolv_conf(const char *dest) {
         return 0;
 }
 
-static int setup_volatile_state(const char *directory) {
-        _cleanup_free_ char *buf = NULL;
-        const char *p, *options;
-        int r;
-
-        assert(directory);
-
-        if (arg_volatile_mode != VOLATILE_STATE)
-                return 0;
-
-        /* --volatile=state means we simply overmount /var
-           with a tmpfs, and the rest read-only. */
-
-        r = bind_remount_recursive(directory, true);
-        if (r < 0)
-                return log_error_errno(r, "Failed to remount %s read-only: %m", directory);
-
-        p = prefix_roota(directory, "/var");
-        r = mkdir(p, 0755);
-        if (r < 0 && errno != EEXIST)
-                return log_error_errno(errno, "Failed to create %s: %m", directory);
-
-        options = "mode=755";
-        r = tmpfs_patch_options(options, &buf);
-        if (r < 0)
-                return log_oom();
-        if (r > 0)
-                options = buf;
-
-        if (mount("tmpfs", p, "tmpfs", MS_STRICTATIME, options) < 0)
-                return log_error_errno(errno, "Failed to mount tmpfs to /var: %m");
-
-        return 0;
-}
-
-static int setup_volatile(const char *directory) {
-        bool tmpfs_mounted = false, bind_mounted = false;
-        char template[] = "/tmp/nspawn-volatile-XXXXXX";
-        _cleanup_free_ char *buf = NULL;
-        const char *f, *t, *options;
-        int r;
-
-        assert(directory);
-
-        if (arg_volatile_mode != VOLATILE_YES)
-                return 0;
-
-        /* --volatile=yes means we mount a tmpfs to the root dir, and
-           the original /usr to use inside it, and that read-only. */
-
-        if (!mkdtemp(template))
-                return log_error_errno(errno, "Failed to create temporary directory: %m");
-
-        options = "mode=755";
-        r = tmpfs_patch_options(options, &buf);
-        if (r < 0)
-                return log_oom();
-        if (r > 0)
-                options = buf;
-
-        if (mount("tmpfs", template, "tmpfs", MS_STRICTATIME, options) < 0) {
-                r = log_error_errno(errno, "Failed to mount tmpfs for root directory: %m");
-                goto fail;
-        }
-
-        tmpfs_mounted = true;
-
-        f = prefix_roota(directory, "/usr");
-        t = prefix_roota(template, "/usr");
-
-        r = mkdir(t, 0755);
-        if (r < 0 && errno != EEXIST) {
-                r = log_error_errno(errno, "Failed to create %s: %m", t);
-                goto fail;
-        }
-
-        if (mount(f, t, NULL, MS_BIND|MS_REC, NULL) < 0) {
-                r = log_error_errno(errno, "Failed to create /usr bind mount: %m");
-                goto fail;
-        }
-
-        bind_mounted = true;
-
-        r = bind_remount_recursive(t, true);
-        if (r < 0) {
-                log_error_errno(r, "Failed to remount %s read-only: %m", t);
-                goto fail;
-        }
-
-        if (mount(template, directory, NULL, MS_MOVE, NULL) < 0) {
-                r = log_error_errno(errno, "Failed to move root mount: %m");
-                goto fail;
-        }
-
-        (void) rmdir(template);
-
-        return 0;
-
-fail:
-        if (bind_mounted)
-                (void) umount(t);
-
-        if (tmpfs_mounted)
-                (void) umount(template);
-        (void) rmdir(template);
-        return r;
-}
-
 static char* id128_format_as_uuid(sd_id128_t id, char s[37]) {
         assert(s);
 
@@ -4401,7 +3606,7 @@ static int inner_child(
                 }
         }
 
-        r = mount_all(NULL, true);
+        r = mount_all(NULL, true, arg_uid_shift, arg_uid_range, arg_selinux_apifs_context);
         if (r < 0)
                 return r;
 
@@ -4412,7 +3617,7 @@ static int inner_child(
                 return -ESRCH;
         }
 
-        r = mount_systemd_cgroup_writable("");
+        r = mount_systemd_cgroup_writable("", arg_unified_cgroup_hierarchy);
         if (r < 0)
                 return r;
 
@@ -4632,11 +3837,11 @@ static int outer_child(
         if (mount(directory, directory, NULL, MS_BIND|MS_REC, NULL) < 0)
                 return log_error_errno(errno, "Failed to make bind mount: %m");
 
-        r = setup_volatile(directory);
+        r = setup_volatile(directory, arg_volatile_mode, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_context);
         if (r < 0)
                 return r;
 
-        r = setup_volatile_state(directory);
+        r = setup_volatile_state(directory, arg_volatile_mode, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_context);
         if (r < 0)
                 return r;
 
@@ -4650,7 +3855,7 @@ static int outer_child(
                         return log_error_errno(r, "Failed to make tree read-only: %m");
         }
 
-        r = mount_all(directory, false);
+        r = mount_all(directory, false, arg_uid_shift, arg_uid_range, arg_selinux_apifs_context);
         if (r < 0)
                 return r;
 
@@ -4686,11 +3891,11 @@ static int outer_child(
         if (r < 0)
                 return r;
 
-        r = mount_custom(directory);
+        r = mount_custom(directory, arg_custom_mounts, arg_n_custom_mounts, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_apifs_context);
         if (r < 0)
                 return r;
 
-        r = mount_cgroups(directory);
+        r = mount_cgroups(directory, arg_unified_cgroup_hierarchy, arg_userns, arg_uid_shift, arg_uid_range, arg_selinux_apifs_context);
         if (r < 0)
                 return r;
 
diff --git a/src/nspawn/nspawn.h b/src/nspawn/nspawn.h
index 2124b434fe..1e2c26b65c 100644
--- a/src/nspawn/nspawn.h
+++ b/src/nspawn/nspawn.h
@@ -26,32 +26,6 @@
 
 #include "list.h"
 
-typedef enum VolatileMode {
-        VOLATILE_NO,
-        VOLATILE_YES,
-        VOLATILE_STATE,
-        _VOLATILE_MODE_MAX,
-        _VOLATILE_MODE_INVALID = -1
-} VolatileMode;
-
-typedef enum CustomMountType {
-        CUSTOM_MOUNT_BIND,
-        CUSTOM_MOUNT_TMPFS,
-        CUSTOM_MOUNT_OVERLAY,
-        _CUSTOM_MOUNT_TYPE_MAX,
-        _CUSTOM_MOUNT_TYPE_INVALID = -1
-} CustomMountType;
-
-typedef struct CustomMount {
-        CustomMountType type;
-        bool read_only;
-        char *source; /* for overlayfs this is the upper directory */
-        char *destination;
-        char *options;
-        char *work_dir;
-        char **lower;
-} CustomMount;
-
 typedef struct ExposePort {
         int protocol;
         uint16_t host_port;
@@ -59,11 +33,5 @@ typedef struct ExposePort {
         LIST_FIELDS(struct ExposePort, ports);
 } ExposePort;
 
-void custom_mount_free_all(CustomMount *l, unsigned n);
-int bind_mount_parse(CustomMount **l, unsigned *n, const char *s, bool read_only);
-int tmpfs_mount_parse(CustomMount **l, unsigned *n, const char *s);
-
 void expose_port_free_all(ExposePort *p);
 int expose_port_parse(ExposePort **l, const char *s);
-
-VolatileMode volatile_mode_from_string(const char *s);