/*-*- 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 .
***/
#include
#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;
}