#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

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

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

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

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

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;

}