blob: ee00362b546e1c4abdf0fafce41c2e6109e8040b [file] [log] [blame]
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <sys/mount.h>
#include <linux/magic.h>
#include "alloc-util.h"
#include "chase-symlinks.h"
#include "escape.h"
#include "fd-util.h"
#include "format-util.h"
#include "fs-util.h"
#include "label.h"
#include "mkdir-label.h"
#include "mount-util.h"
#include "mountpoint-util.h"
#include "namespace-util.h"
#include "nspawn-mount.h"
#include "parse-util.h"
#include "path-util.h"
#include "rm-rf.h"
#include "set.h"
#include "sort-util.h"
#include "stat-util.h"
#include "string-util.h"
#include "strv.h"
#include "tmpfile-util.h"
#include "user-util.h"
CustomMount* custom_mount_add(CustomMount **l, size_t *n, CustomMountType t) {
CustomMount *c, *ret;
assert(l);
assert(n);
assert(t >= 0);
assert(t < _CUSTOM_MOUNT_TYPE_MAX);
c = reallocarray(*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, size_t n) {
for (size_t 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);
}
if (m->rm_rf_tmpdir) {
(void) rm_rf(m->rm_rf_tmpdir, REMOVE_ROOT|REMOVE_PHYSICAL);
free(m->rm_rf_tmpdir);
}
strv_free(m->lower);
free(m->type_argument);
}
free(l);
}
static int custom_mount_compare(const CustomMount *a, const CustomMount *b) {
int r;
r = path_compare(a->destination, b->destination);
if (r != 0)
return r;
return CMP(a->type, b->type);
}
static int source_path_parse(const char *p, char **ret) {
assert(p);
assert(ret);
if (isempty(p))
return -EINVAL;
if (*p == '+') {
if (!path_is_absolute(p + 1))
return -EINVAL;
char *s = strdup(p);
if (!s)
return -ENOMEM;
*ret = TAKE_PTR(s);
return 0;
}
return path_make_absolute_cwd(p, ret);
}
static int source_path_parse_nullable(const char *p, char **ret) {
assert(p);
assert(ret);
if (isempty(p)) {
*ret = NULL;
return 0;
}
return source_path_parse(p, ret);
}
static char *resolve_source_path(const char *dest, const char *source) {
if (!source)
return NULL;
if (source[0] == '+')
return path_join(dest, source + 1);
return strdup(source);
}
static int allocate_temporary_source(CustomMount *m) {
assert(m);
assert(!m->source);
assert(!m->rm_rf_tmpdir);
m->rm_rf_tmpdir = strdup("/var/tmp/nspawn-temp-XXXXXX");
if (!m->rm_rf_tmpdir)
return log_oom();
if (!mkdtemp(m->rm_rf_tmpdir)) {
m->rm_rf_tmpdir = mfree(m->rm_rf_tmpdir);
return log_error_errno(errno, "Failed to acquire temporary directory: %m");
}
m->source = path_join(m->rm_rf_tmpdir, "src");
if (!m->source)
return log_oom();
if (mkdir(m->source, 0755) < 0)
return log_error_errno(errno, "Failed to create %s: %m", m->source);
return 0;
}
int custom_mount_prepare_all(const char *dest, CustomMount *l, size_t n) {
int r;
/* Prepare all custom mounts. This will make source we know all temporary directories. This is called in the
* parent process, so that we know the temporary directories to remove on exit before we fork off the
* children. */
assert(l || n == 0);
/* Order the custom mounts, and make sure we have a working directory */
typesafe_qsort(l, n, custom_mount_compare);
for (size_t i = 0; i < n; i++) {
CustomMount *m = l + i;
/* /proc we mount in the inner child, i.e. when we acquired CLONE_NEWPID. All other mounts we mount
* already in the outer child, so that the mounts are already established before CLONE_NEWPID and in
* particular CLONE_NEWUSER. This also means any custom mounts below /proc also need to be mounted in
* the inner child, not the outer one. Determine this here. */
m->in_userns = path_startswith(m->destination, "/proc");
if (m->type == CUSTOM_MOUNT_BIND) {
if (m->source) {
char *s;
s = resolve_source_path(dest, m->source);
if (!s)
return log_oom();
free_and_replace(m->source, s);
} else {
/* No source specified? In that case, use a throw-away temporary directory in /var/tmp */
r = allocate_temporary_source(m);
if (r < 0)
return r;
}
}
if (m->type == CUSTOM_MOUNT_OVERLAY) {
STRV_FOREACH(j, m->lower) {
char *s;
s = resolve_source_path(dest, *j);
if (!s)
return log_oom();
free_and_replace(*j, s);
}
if (m->source) {
char *s;
s = resolve_source_path(dest, m->source);
if (!s)
return log_oom();
free_and_replace(m->source, s);
} else {
r = allocate_temporary_source(m);
if (r < 0)
return r;
}
if (m->work_dir) {
char *s;
s = resolve_source_path(dest, m->work_dir);
if (!s)
return log_oom();
free_and_replace(m->work_dir, s);
} else {
r = tempfn_random(m->source, NULL, &m->work_dir);
if (r < 0)
return log_error_errno(r, "Failed to acquire working directory: %m");
}
(void) mkdir_label(m->work_dir, 0700);
}
}
return 0;
}
int bind_mount_parse(CustomMount **l, size_t *n, const char *s, bool read_only) {
_cleanup_free_ char *source = NULL, *destination = NULL, *opts = NULL, *p = NULL;
CustomMount *m;
int r;
assert(l);
assert(n);
r = extract_many_words(&s, ":", EXTRACT_DONT_COALESCE_SEPARATORS, &source, &destination, NULL);
if (r < 0)
return r;
if (r == 0)
return -EINVAL;
if (r == 1) {
destination = strdup(source[0] == '+' ? source+1 : source);
if (!destination)
return -ENOMEM;
}
if (r == 2 && !isempty(s)) {
opts = strdup(s);
if (!opts)
return -ENOMEM;
}
r = source_path_parse_nullable(source, &p);
if (r < 0)
return r;
if (!path_is_absolute(destination))
return -EINVAL;
m = custom_mount_add(l, n, CUSTOM_MOUNT_BIND);
if (!m)
return -ENOMEM;
m->source = TAKE_PTR(p);
m->destination = TAKE_PTR(destination);
m->read_only = read_only;
m->options = TAKE_PTR(opts);
return 0;
}
int tmpfs_mount_parse(CustomMount **l, size_t *n, const char *s) {
_cleanup_free_ char *path = NULL, *opts = NULL;
const char *p = ASSERT_PTR(s);
CustomMount *m;
int r;
assert(l);
assert(n);
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 = TAKE_PTR(path);
m->options = TAKE_PTR(opts);
return 0;
}
int overlay_mount_parse(CustomMount **l, size_t *n, const char *s, bool read_only) {
_cleanup_free_ char *upper = NULL, *destination = NULL;
_cleanup_strv_free_ char **lower = NULL;
CustomMount *m;
int r, k;
k = strv_split_full(&lower, s, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
if (k < 0)
return k;
if (k < 2)
return -EADDRNOTAVAIL;
if (k == 2) {
_cleanup_free_ char *p = NULL;
/* If two parameters are specified, the first one is the lower, the second one the upper directory. And
* we'll also define the destination mount point the same as the upper. */
r = source_path_parse(lower[0], &p);
if (r < 0)
return r;
free_and_replace(lower[0], p);
r = source_path_parse(lower[1], &p);
if (r < 0)
return r;
free_and_replace(lower[1], p);
upper = TAKE_PTR(lower[1]);
destination = strdup(upper[0] == '+' ? upper+1 : upper); /* take the destination without "+" prefix */
if (!destination)
return -ENOMEM;
} else {
_cleanup_free_ char *p = NULL;
/* If more than two parameters are specified, the last one is the destination, the second to last one
* the "upper", and all before that the "lower" directories. */
destination = lower[k - 1];
upper = TAKE_PTR(lower[k - 2]);
STRV_FOREACH(i, lower) {
r = source_path_parse(*i, &p);
if (r < 0)
return r;
free_and_replace(*i, p);
}
/* If the upper directory is unspecified, then let's create it automatically as a throw-away directory
* in /var/tmp */
r = source_path_parse_nullable(upper, &p);
if (r < 0)
return r;
free_and_replace(upper, p);
if (!path_is_absolute(destination))
return -EINVAL;
}
m = custom_mount_add(l, n, CUSTOM_MOUNT_OVERLAY);
if (!m)
return -ENOMEM;
m->destination = TAKE_PTR(destination);
m->source = TAKE_PTR(upper);
m->lower = TAKE_PTR(lower);
m->read_only = read_only;
return 0;
}
int inaccessible_mount_parse(CustomMount **l, size_t *n, const char *s) {
_cleanup_free_ char *path = NULL;
CustomMount *m;
assert(l);
assert(n);
assert(s);
if (!path_is_absolute(s))
return -EINVAL;
path = strdup(s);
if (!path)
return -ENOMEM;
m = custom_mount_add(l, n, CUSTOM_MOUNT_INACCESSIBLE);
if (!m)
return -ENOMEM;
m->destination = TAKE_PTR(path);
return 0;
}
int tmpfs_patch_options(
const char *options,
uid_t uid_shift,
const char *selinux_apifs_context,
char **ret) {
_cleanup_free_ char *buf = NULL;
assert(ret);
if (options) {
buf = strdup(options);
if (!buf)
return -ENOMEM;
}
if (uid_shift != UID_INVALID)
if (strextendf_with_separator(&buf, ",", "uid=" UID_FMT ",gid=" UID_FMT, uid_shift, uid_shift) < 0)
return -ENOMEM;
#if HAVE_SELINUX
if (selinux_apifs_context)
if (strextendf_with_separator(&buf, ",", "context=\"%s\"", selinux_apifs_context) < 0)
return -ENOMEM;
#endif
*ret = TAKE_PTR(buf);
return !!*ret;
}
int mount_sysfs(const char *dest, MountSettingsMask mount_settings) {
const char *full, *top;
int r;
unsigned long extra_flags = 0;
top = prefix_roota(dest, "/sys");
r = path_is_fs_type(top, SYSFS_MAGIC);
if (r < 0)
return log_error_errno(r, "Failed to determine filesystem type of %s: %m", top);
/* /sys might already be mounted as sysfs by the outer child in the
* !netns case. In this case, it's all good. Don't touch it because we
* don't have the right to do so, see https://github.com/systemd/systemd/issues/1555.
*/
if (r > 0)
return 0;
full = prefix_roota(top, "/full");
(void) mkdir(full, 0755);
if (FLAGS_SET(mount_settings, MOUNT_APPLY_APIVFS_RO))
extra_flags |= MS_RDONLY;
r = mount_nofollow_verbose(LOG_ERR, "sysfs", full, "sysfs",
MS_NOSUID|MS_NOEXEC|MS_NODEV|extra_flags, NULL);
if (r < 0)
return r;
FOREACH_STRING(x, "block", "bus", "class", "dev", "devices", "kernel") {
_cleanup_free_ char *from = NULL, *to = NULL;
from = path_join(full, x);
if (!from)
return log_oom();
to = path_join(top, x);
if (!to)
return log_oom();
(void) mkdir(to, 0755);
r = mount_nofollow_verbose(LOG_ERR, from, to, NULL, MS_BIND, NULL);
if (r < 0)
return r;
r = mount_nofollow_verbose(LOG_ERR, NULL, to, NULL,
MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL);
if (r < 0)
return r;
}
r = umount_verbose(LOG_ERR, full, UMOUNT_NOFOLLOW);
if (r < 0)
return r;
if (rmdir(full) < 0)
return log_error_errno(errno, "Failed to remove %s: %m", full);
/* Create mountpoint for cgroups. Otherwise we are not allowed since we
* remount /sys read-only.
*/
const char *x = prefix_roota(top, "/fs/cgroup");
(void) mkdir_p(x, 0755);
return mount_nofollow_verbose(LOG_ERR, NULL, top, NULL,
MS_BIND|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT|extra_flags, NULL);
}
#define PROC_DEFAULT_MOUNT_FLAGS (MS_NOSUID|MS_NOEXEC|MS_NODEV)
#define SYS_DEFAULT_MOUNT_FLAGS (MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV)
int mount_all(const char *dest,
MountSettingsMask mount_settings,
uid_t uid_shift,
const char *selinux_apifs_context) {
#define PROC_INACCESSIBLE_REG(path) \
{ "/run/systemd/inaccessible/reg", (path), NULL, NULL, MS_BIND, \
MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO }, /* Bind mount first ... */ \
{ NULL, (path), NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, \
MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO } /* Then, make it r/o */
#define PROC_READ_ONLY(path) \
{ (path), (path), NULL, NULL, MS_BIND, \
MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO }, /* Bind mount first ... */ \
{ NULL, (path), NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, \
MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO } /* Then, make it r/o */
typedef struct MountPoint {
const char *what;
const char *where;
const char *type;
const char *options;
unsigned long flags;
MountSettingsMask mount_settings;
} MountPoint;
static const MountPoint mount_table[] = {
/* First we list inner child mounts (i.e. mounts applied *after* entering user namespacing) */
{ "proc", "/proc", "proc", NULL, PROC_DEFAULT_MOUNT_FLAGS,
MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_MKDIR|MOUNT_FOLLOW_SYMLINKS }, /* we follow symlinks here since not following them requires /proc/ already being mounted, which we don't have here. */
{ "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND,
MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO }, /* Bind mount first ... */
{ "/proc/sys/net", "/proc/sys/net", NULL, NULL, MS_BIND,
MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO|MOUNT_APPLY_APIVFS_NETNS }, /* (except for this) */
{ NULL, "/proc/sys", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT,
MOUNT_FATAL|MOUNT_IN_USERNS|MOUNT_APPLY_APIVFS_RO }, /* ... then, make it r/o */
/* Make these files inaccessible to container payloads: they potentially leak information about kernel
* internals or the host's execution environment to the container */
PROC_INACCESSIBLE_REG("/proc/kallsyms"),
PROC_INACCESSIBLE_REG("/proc/kcore"),
PROC_INACCESSIBLE_REG("/proc/keys"),
PROC_INACCESSIBLE_REG("/proc/sysrq-trigger"),
PROC_INACCESSIBLE_REG("/proc/timer_list"),
/* Make these directories read-only to container payloads: they show hardware information, and in some
* cases contain tunables the container really shouldn't have access to. */
PROC_READ_ONLY("/proc/acpi"),
PROC_READ_ONLY("/proc/apm"),
PROC_READ_ONLY("/proc/asound"),
PROC_READ_ONLY("/proc/bus"),
PROC_READ_ONLY("/proc/fs"),
PROC_READ_ONLY("/proc/irq"),
PROC_READ_ONLY("/proc/scsi"),
{ "mqueue", "/dev/mqueue", "mqueue", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
MOUNT_IN_USERNS|MOUNT_MKDIR },
/* Then we list outer child mounts (i.e. mounts applied *before* entering user namespacing) */
{ "tmpfs", "/tmp", "tmpfs", "mode=01777" NESTED_TMPFS_LIMITS, MS_NOSUID|MS_NODEV|MS_STRICTATIME,
MOUNT_FATAL|MOUNT_APPLY_TMPFS_TMP|MOUNT_MKDIR },
{ "tmpfs", "/sys", "tmpfs", "mode=0555" TMPFS_LIMITS_SYS, MS_NOSUID|MS_NOEXEC|MS_NODEV,
MOUNT_FATAL|MOUNT_APPLY_APIVFS_NETNS|MOUNT_MKDIR },
{ "sysfs", "/sys", "sysfs", NULL, SYS_DEFAULT_MOUNT_FLAGS,
MOUNT_FATAL|MOUNT_APPLY_APIVFS_RO|MOUNT_MKDIR }, /* skipped if above was mounted */
{ "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV,
MOUNT_FATAL|MOUNT_MKDIR }, /* skipped if above was mounted */
{ "tmpfs", "/dev", "tmpfs", "mode=0755" TMPFS_LIMITS_PRIVATE_DEV, MS_NOSUID|MS_STRICTATIME,
MOUNT_FATAL|MOUNT_MKDIR },
{ "tmpfs", "/dev/shm", "tmpfs", "mode=01777" NESTED_TMPFS_LIMITS, MS_NOSUID|MS_NODEV|MS_STRICTATIME,
MOUNT_FATAL|MOUNT_MKDIR },
{ "tmpfs", "/run", "tmpfs", "mode=0755" TMPFS_LIMITS_RUN, MS_NOSUID|MS_NODEV|MS_STRICTATIME,
MOUNT_FATAL|MOUNT_MKDIR },
{ "/run/host", "/run/host", NULL, NULL, MS_BIND,
MOUNT_FATAL|MOUNT_MKDIR|MOUNT_PREFIX_ROOT }, /* Prepare this so that we can make it read-only when we are done */
{ "/etc/os-release", "/run/host/os-release", NULL, NULL, MS_BIND,
MOUNT_TOUCH }, /* As per kernel interface requirements, bind mount first (creating mount points) and make read-only later */
{ "/usr/lib/os-release", "/run/host/os-release", NULL, NULL, MS_BIND,
MOUNT_FATAL }, /* If /etc/os-release doesn't exist use the version in /usr/lib as fallback */
{ NULL, "/run/host/os-release", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT,
MOUNT_FATAL },
{ NULL, "/run/host", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT,
MOUNT_FATAL|MOUNT_IN_USERNS },
#if HAVE_SELINUX
{ "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND,
MOUNT_MKDIR }, /* Bind mount first (mkdir/chown the mount point in case /sys/ is mounted as minimal skeleton tmpfs) */
{ NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT,
0 }, /* Then, make it r/o (don't mkdir/chown the mount point here, the previous entry already did that) */
#endif
};
bool use_userns = FLAGS_SET(mount_settings, MOUNT_USE_USERNS);
bool netns = FLAGS_SET(mount_settings, MOUNT_APPLY_APIVFS_NETNS);
bool ro = FLAGS_SET(mount_settings, MOUNT_APPLY_APIVFS_RO);
bool in_userns = FLAGS_SET(mount_settings, MOUNT_IN_USERNS);
bool tmpfs_tmp = FLAGS_SET(mount_settings, MOUNT_APPLY_TMPFS_TMP);
int r;
for (size_t k = 0; k < ELEMENTSOF(mount_table); k++) {
_cleanup_free_ char *where = NULL, *options = NULL, *prefixed = NULL;
bool fatal = FLAGS_SET(mount_table[k].mount_settings, MOUNT_FATAL);
const char *o;
if (in_userns != FLAGS_SET(mount_table[k].mount_settings, MOUNT_IN_USERNS))
continue;
if (!netns && FLAGS_SET(mount_table[k].mount_settings, MOUNT_APPLY_APIVFS_NETNS))
continue;
if (!ro && FLAGS_SET(mount_table[k].mount_settings, MOUNT_APPLY_APIVFS_RO))
continue;
if (!tmpfs_tmp && FLAGS_SET(mount_table[k].mount_settings, MOUNT_APPLY_TMPFS_TMP))
continue;
r = chase_symlinks(mount_table[k].where, dest, CHASE_NONEXISTENT|CHASE_PREFIX_ROOT, &where, NULL);
if (r < 0)
return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, mount_table[k].where);
/* Skip this entry if it is not a remount. */
if (mount_table[k].what) {
r = path_is_mount_point(where, NULL, 0);
if (r < 0 && r != -ENOENT)
return log_error_errno(r, "Failed to detect whether %s is a mount point: %m", where);
if (r > 0)
continue;
}
if ((mount_table[k].mount_settings & (MOUNT_MKDIR|MOUNT_TOUCH)) != 0) {
uid_t u = (use_userns && !in_userns) ? uid_shift : UID_INVALID;
if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_TOUCH))
r = mkdir_parents_safe(dest, where, 0755, u, u, 0);
else
r = mkdir_p_safe(dest, where, 0755, u, u, 0);
if (r < 0 && r != -EEXIST) {
if (fatal && r != -EROFS)
return log_error_errno(r, "Failed to create directory %s: %m", where);
log_debug_errno(r, "Failed to create directory %s: %m", where);
/* If we failed mkdir() or chown() due to the root directory being read only,
* attempt to mount this fs anyway and let mount_verbose log any errors */
if (r != -EROFS)
continue;
}
}
if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_TOUCH)) {
r = touch(where);
if (r < 0 && r != -EEXIST) {
if (fatal && r != -EROFS)
return log_error_errno(r, "Failed to create file %s: %m", where);
log_debug_errno(r, "Failed to create file %s: %m", where);
if (r != -EROFS)
continue;
}
}
o = mount_table[k].options;
if (streq_ptr(mount_table[k].type, "tmpfs")) {
r = tmpfs_patch_options(o, in_userns ? 0 : uid_shift, selinux_apifs_context, &options);
if (r < 0)
return log_oom();
if (r > 0)
o = options;
}
if (FLAGS_SET(mount_table[k].mount_settings, MOUNT_PREFIX_ROOT)) {
/* Optionally prefix the mount source with the root dir. This is useful in bind
* mounts to be created within the container image before we transition into it. Note
* that MOUNT_IN_USERNS is run after we transitioned hence prefixing is not ncessary
* for those. */
r = chase_symlinks(mount_table[k].what, dest, CHASE_PREFIX_ROOT, &prefixed, NULL);
if (r < 0)
return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, mount_table[k].what);
}
r = mount_verbose_full(
fatal ? LOG_ERR : LOG_DEBUG,
prefixed ?: mount_table[k].what,
where,
mount_table[k].type,
mount_table[k].flags,
o,
FLAGS_SET(mount_table[k].mount_settings, MOUNT_FOLLOW_SYMLINKS));
if (r < 0 && fatal)
return r;
}
return 0;
}
static int parse_mount_bind_options(const char *options, unsigned long *mount_flags, char **mount_opts, RemountIdmapping *idmapping) {
unsigned long flags = *mount_flags;
char *opts = NULL;
RemountIdmapping new_idmapping = *idmapping;
int r;
assert(options);
for (;;) {
_cleanup_free_ char *word = NULL;
r = extract_first_word(&options, &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 if (streq(word, "idmap"))
new_idmapping = REMOUNT_IDMAPPING_HOST_ROOT;
else if (streq(word, "noidmap"))
new_idmapping = REMOUNT_IDMAPPING_NONE;
else if (streq(word, "rootidmap"))
new_idmapping = REMOUNT_IDMAPPING_HOST_OWNER;
else
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Invalid bind mount option: %s", word);
}
*mount_flags = flags;
*idmapping = new_idmapping;
/* 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, uid_t uid_shift, uid_t uid_range) {
_cleanup_free_ char *mount_opts = NULL, *where = NULL;
unsigned long mount_flags = MS_BIND | MS_REC;
struct stat source_st, dest_st;
int r;
RemountIdmapping idmapping = REMOUNT_IDMAPPING_NONE;
assert(dest);
assert(m);
if (m->options) {
r = parse_mount_bind_options(m->options, &mount_flags, &mount_opts, &idmapping);
if (r < 0)
return r;
}
/* If this is a bind mount from a temporary sources change ownership of the source to the container's
* root UID. Otherwise it would always show up as "nobody" if user namespacing is used. */
if (m->rm_rf_tmpdir && chown(m->source, uid_shift, uid_shift) < 0)
return log_error_errno(errno, "Failed to chown %s: %m", m->source);
if (stat(m->source, &source_st) < 0)
return log_error_errno(errno, "Failed to stat %s: %m", m->source);
r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL);
if (r < 0)
return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
if (r > 0) { /* Path exists already? */
if (stat(where, &dest_st) < 0)
return log_error_errno(errno, "Failed to stat %s: %m", where);
if (S_ISDIR(source_st.st_mode) && !S_ISDIR(dest_st.st_mode))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Cannot bind mount directory %s on file %s.",
m->source, where);
if (!S_ISDIR(source_st.st_mode) && S_ISDIR(dest_st.st_mode))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Cannot bind mount file %s on directory %s.",
m->source, where);
} else { /* Path doesn't exist yet? */
r = mkdir_parents_safe_label(dest, where, 0755, uid_shift, uid_shift, MKDIR_IGNORE_EXISTING);
if (r < 0)
return log_error_errno(r, "Failed to make parents of %s: %m", where);
/* 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)
return log_error_errno(r, "Failed to create mount point %s: %m", where);
if (chown(where, uid_shift, uid_shift) < 0)
return log_error_errno(errno, "Failed to chown %s: %m", where);
}
r = mount_nofollow_verbose(LOG_ERR, m->source, where, NULL, mount_flags, mount_opts);
if (r < 0)
return r;
if (m->read_only) {
r = bind_remount_recursive(where, MS_RDONLY, MS_RDONLY, NULL);
if (r < 0)
return log_error_errno(r, "Read-only bind mount failed: %m");
}
if (idmapping != REMOUNT_IDMAPPING_NONE) {
r = remount_idmap(where, uid_shift, uid_range, source_st.st_uid, idmapping);
if (r < 0)
return log_error_errno(r, "Failed to map ids for bind mount %s: %m", where);
}
return 0;
}
static int mount_tmpfs(const char *dest, CustomMount *m, uid_t uid_shift, const char *selinux_apifs_context) {
const char *options;
_cleanup_free_ char *buf = NULL, *where = NULL;
int r;
assert(dest);
assert(m);
r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL);
if (r < 0)
return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
if (r == 0) { /* Doesn't exist yet? */
r = mkdir_p_label(where, 0755);
if (r < 0)
return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where);
}
r = tmpfs_patch_options(m->options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf);
if (r < 0)
return log_oom();
options = r > 0 ? buf : m->options;
return mount_nofollow_verbose(LOG_ERR, "tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, options);
}
static char *joined_and_escaped_lower_dirs(char **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, *where = NULL, *escaped_source = NULL;
const char *options;
int r;
assert(dest);
assert(m);
r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL);
if (r < 0)
return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
if (r == 0) { /* Doesn't exist yet? */
r = mkdir_label(where, 0755);
if (r < 0)
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();
escaped_source = shell_escape(m->source, ",:");
if (!escaped_source)
return log_oom();
if (m->read_only)
options = strjoina("lowerdir=", escaped_source, ":", lower);
else {
_cleanup_free_ char *escaped_work_dir = NULL;
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);
}
return mount_nofollow_verbose(LOG_ERR, "overlay", where, "overlay", m->read_only ? MS_RDONLY : 0, options);
}
static int mount_inaccessible(const char *dest, CustomMount *m) {
_cleanup_free_ char *where = NULL, *source = NULL;
struct stat st;
int r;
assert(dest);
assert(m);
r = chase_symlinks_and_stat(m->destination, dest, CHASE_PREFIX_ROOT, &where, &st, NULL);
if (r < 0) {
log_full_errno(m->graceful ? LOG_DEBUG : LOG_ERR, r, "Failed to resolve %s/%s: %m", dest, m->destination);
return m->graceful ? 0 : r;
}
r = mode_to_inaccessible_node(NULL, st.st_mode, &source);
if (r < 0)
return m->graceful ? 0 : r;
r = mount_nofollow_verbose(m->graceful ? LOG_DEBUG : LOG_ERR, source, where, NULL, MS_BIND, NULL);
if (r < 0)
return m->graceful ? 0 : r;
r = mount_nofollow_verbose(m->graceful ? LOG_DEBUG : LOG_ERR, NULL, where, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL);
if (r < 0) {
(void) umount_verbose(m->graceful ? LOG_DEBUG : LOG_ERR, where, UMOUNT_NOFOLLOW);
return m->graceful ? 0 : r;
}
return 0;
}
static int mount_arbitrary(const char *dest, CustomMount *m) {
_cleanup_free_ char *where = NULL;
int r;
assert(dest);
assert(m);
r = chase_symlinks(m->destination, dest, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &where, NULL);
if (r < 0)
return log_error_errno(r, "Failed to resolve %s/%s: %m", dest, m->destination);
if (r == 0) { /* Doesn't exist yet? */
r = mkdir_p_label(where, 0755);
if (r < 0)
return log_error_errno(r, "Creating mount point for mount %s failed: %m", where);
}
return mount_nofollow_verbose(LOG_ERR, m->source, where, m->type_argument, 0, m->options);
}
int mount_custom(
const char *dest,
CustomMount *mounts, size_t n,
uid_t uid_shift,
uid_t uid_range,
const char *selinux_apifs_context,
MountSettingsMask mount_settings) {
int r;
assert(dest);
for (size_t i = 0; i < n; i++) {
CustomMount *m = mounts + i;
if (FLAGS_SET(mount_settings, MOUNT_IN_USERNS) != m->in_userns)
continue;
if (FLAGS_SET(mount_settings, MOUNT_ROOT_ONLY) && !path_equal(m->destination, "/"))
continue;
if (FLAGS_SET(mount_settings, MOUNT_NON_ROOT_ONLY) && path_equal(m->destination, "/"))
continue;
switch (m->type) {
case CUSTOM_MOUNT_BIND:
r = mount_bind(dest, m, uid_shift, uid_range);
break;
case CUSTOM_MOUNT_TMPFS:
r = mount_tmpfs(dest, m, uid_shift, selinux_apifs_context);
break;
case CUSTOM_MOUNT_OVERLAY:
r = mount_overlay(dest, m);
break;
case CUSTOM_MOUNT_INACCESSIBLE:
r = mount_inaccessible(dest, m);
break;
case CUSTOM_MOUNT_ARBITRARY:
r = mount_arbitrary(dest, m);
break;
default:
assert_not_reached();
}
if (r < 0)
return r;
}
return 0;
}
bool has_custom_root_mount(const CustomMount *mounts, size_t n) {
for (size_t i = 0; i < n; i++)
if (path_equal(mounts[i].destination, "/"))
return true;
return false;
}
static int setup_volatile_state(const char *directory, uid_t uid_shift, const char *selinux_apifs_context) {
_cleanup_free_ char *buf = NULL;
const char *p, *options;
int r;
assert(directory);
/* --volatile=state means we simply overmount /var with a tmpfs, and the rest read-only. */
r = bind_remount_recursive(directory, MS_RDONLY, MS_RDONLY, NULL);
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=0755" TMPFS_LIMITS_VOLATILE_STATE;
r = tmpfs_patch_options(options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf);
if (r < 0)
return log_oom();
if (r > 0)
options = buf;
return mount_nofollow_verbose(LOG_ERR, "tmpfs", p, "tmpfs", MS_STRICTATIME, options);
}
static int setup_volatile_yes(const char *directory, uid_t uid_shift, const char *selinux_apifs_context) {
bool tmpfs_mounted = false, bind_mounted = false;
char template[] = "/tmp/nspawn-volatile-XXXXXX";
_cleanup_free_ char *buf = NULL, *bindir = NULL;
const char *f, *t, *options;
struct stat st;
int r;
assert(directory);
/* --volatile=yes means we mount a tmpfs to the root dir, and the original /usr to use inside it, and
* that read-only. Before we start setting this up let's validate if the image has the /usr merge
* implemented, and let's output a friendly log message if it hasn't. */
bindir = path_join(directory, "/bin");
if (!bindir)
return log_oom();
if (lstat(bindir, &st) < 0) {
if (errno != ENOENT)
return log_error_errno(errno, "Failed to stat /bin directory below image: %m");
/* ENOENT is fine, just means the image is probably just a naked /usr and we can create the
* rest. */
} else if (S_ISDIR(st.st_mode))
return log_error_errno(SYNTHETIC_ERRNO(EISDIR),
"Sorry, --volatile=yes mode is not supported with OS images that have not merged /bin/, /sbin/, /lib/, /lib64/ into /usr/. "
"Please work with your distribution and help them adopt the merged /usr scheme.");
else if (!S_ISLNK(st.st_mode))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Error starting image: if --volatile=yes is used /bin must be a symlink (for merged /usr support) or non-existent (in which case a symlink is created automatically).");
if (!mkdtemp(template))
return log_error_errno(errno, "Failed to create temporary directory: %m");
options = "mode=0755" TMPFS_LIMITS_ROOTFS;
r = tmpfs_patch_options(options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf);
if (r < 0)
goto fail;
if (r > 0)
options = buf;
r = mount_nofollow_verbose(LOG_ERR, "tmpfs", template, "tmpfs", MS_STRICTATIME, options);
if (r < 0)
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;
}
r = mount_nofollow_verbose(LOG_ERR, f, t, NULL, MS_BIND|MS_REC, NULL);
if (r < 0)
goto fail;
bind_mounted = true;
r = bind_remount_recursive(t, MS_RDONLY, MS_RDONLY, NULL);
if (r < 0) {
log_error_errno(r, "Failed to remount %s read-only: %m", t);
goto fail;
}
r = mount_nofollow_verbose(LOG_ERR, template, directory, NULL, MS_MOVE, NULL);
if (r < 0)
goto fail;
(void) rmdir(template);
return 0;
fail:
if (bind_mounted)
(void) umount_verbose(LOG_ERR, t, UMOUNT_NOFOLLOW);
if (tmpfs_mounted)
(void) umount_verbose(LOG_ERR, template, UMOUNT_NOFOLLOW);
(void) rmdir(template);
return r;
}
static int setup_volatile_overlay(const char *directory, uid_t uid_shift, const char *selinux_apifs_context) {
_cleanup_free_ char *buf = NULL, *escaped_directory = NULL, *escaped_upper = NULL, *escaped_work = NULL;
char template[] = "/tmp/nspawn-volatile-XXXXXX";
const char *upper, *work, *options;
bool tmpfs_mounted = false;
int r;
assert(directory);
/* --volatile=overlay means we mount an overlayfs to the root dir. */
if (!mkdtemp(template))
return log_error_errno(errno, "Failed to create temporary directory: %m");
options = "mode=0755" TMPFS_LIMITS_ROOTFS;
r = tmpfs_patch_options(options, uid_shift == 0 ? UID_INVALID : uid_shift, selinux_apifs_context, &buf);
if (r < 0)
goto finish;
if (r > 0)
options = buf;
r = mount_nofollow_verbose(LOG_ERR, "tmpfs", template, "tmpfs", MS_STRICTATIME, options);
if (r < 0)
goto finish;
tmpfs_mounted = true;
upper = strjoina(template, "/upper");
work = strjoina(template, "/work");
if (mkdir(upper, 0755) < 0) {
r = log_error_errno(errno, "Failed to create %s: %m", upper);
goto finish;
}
if (mkdir(work, 0755) < 0) {
r = log_error_errno(errno, "Failed to create %s: %m", work);
goto finish;
}
/* And now, let's overmount the root dir with an overlayfs that uses the root dir as lower dir. It's kinda nice
* that the kernel allows us to do that without going through some mount point rearrangements. */
escaped_directory = shell_escape(directory, ",:");
escaped_upper = shell_escape(upper, ",:");
escaped_work = shell_escape(work, ",:");
if (!escaped_directory || !escaped_upper || !escaped_work) {
r = -ENOMEM;
goto finish;
}
options = strjoina("lowerdir=", escaped_directory, ",upperdir=", escaped_upper, ",workdir=", escaped_work);
r = mount_nofollow_verbose(LOG_ERR, "overlay", directory, "overlay", 0, options);
finish:
if (tmpfs_mounted)
(void) umount_verbose(LOG_ERR, template, UMOUNT_NOFOLLOW);
(void) rmdir(template);
return r;
}
int setup_volatile_mode(
const char *directory,
VolatileMode mode,
uid_t uid_shift,
const char *selinux_apifs_context) {
switch (mode) {
case VOLATILE_YES:
return setup_volatile_yes(directory, uid_shift, selinux_apifs_context);
case VOLATILE_STATE:
return setup_volatile_state(directory, uid_shift, selinux_apifs_context);
case VOLATILE_OVERLAY:
return setup_volatile_overlay(directory, uid_shift, selinux_apifs_context);
default:
return 0;
}
}
/* Expects *pivot_root_new and *pivot_root_old to be initialised to allocated memory or NULL. */
int pivot_root_parse(char **pivot_root_new, char **pivot_root_old, const char *s) {
_cleanup_free_ char *root_new = NULL, *root_old = NULL;
const char *p = s;
int r;
assert(pivot_root_new);
assert(pivot_root_old);
r = extract_first_word(&p, &root_new, ":", EXTRACT_DONT_COALESCE_SEPARATORS);
if (r < 0)
return r;
if (r == 0)
return -EINVAL;
if (isempty(p))
root_old = NULL;
else {
root_old = strdup(p);
if (!root_old)
return -ENOMEM;
}
if (!path_is_absolute(root_new))
return -EINVAL;
if (root_old && !path_is_absolute(root_old))
return -EINVAL;
free_and_replace(*pivot_root_new, root_new);
free_and_replace(*pivot_root_old, root_old);
return 0;
}
int setup_pivot_root(const char *directory, const char *pivot_root_new, const char *pivot_root_old) {
_cleanup_free_ char *directory_pivot_root_new = NULL;
_cleanup_free_ char *pivot_tmp_pivot_root_old = NULL;
char pivot_tmp[] = "/tmp/nspawn-pivot-XXXXXX";
bool remove_pivot_tmp = false;
int r;
assert(directory);
if (!pivot_root_new)
return 0;
/* Pivot pivot_root_new to / and the existing / to pivot_root_old.
* If pivot_root_old is NULL, the existing / disappears.
* This requires a temporary directory, pivot_tmp, which is
* not a child of either.
*
* This is typically used for OSTree-style containers, where the root partition contains several
* sysroots which could be run. Normally, one would be chosen by the bootloader and pivoted to / by
* initrd.
*
* For example, for an OSTree deployment, pivot_root_new
* would be: /ostree/deploy/$os/deploy/$checksum. Note that this
* code doesn’t do the /var mount which OSTree expects: use
* --bind +/sysroot/ostree/deploy/$os/var:/var for that.
*
* So in the OSTree case, we’ll end up with something like:
* - directory = /tmp/nspawn-root-123456
* - pivot_root_new = /ostree/deploy/os/deploy/123abc
* - pivot_root_old = /sysroot
* - directory_pivot_root_new =
* /tmp/nspawn-root-123456/ostree/deploy/os/deploy/123abc
* - pivot_tmp = /tmp/nspawn-pivot-123456
* - pivot_tmp_pivot_root_old = /tmp/nspawn-pivot-123456/sysroot
*
* Requires all file systems at directory and below to be mounted
* MS_PRIVATE or MS_SLAVE so they can be moved.
*/
directory_pivot_root_new = path_join(directory, pivot_root_new);
if (!directory_pivot_root_new)
return log_oom();
/* Remount directory_pivot_root_new to make it movable. */
r = mount_nofollow_verbose(LOG_ERR, directory_pivot_root_new, directory_pivot_root_new, NULL, MS_BIND, NULL);
if (r < 0)
goto done;
if (pivot_root_old) {
if (!mkdtemp(pivot_tmp)) {
r = log_error_errno(errno, "Failed to create temporary directory: %m");
goto done;
}
remove_pivot_tmp = true;
pivot_tmp_pivot_root_old = path_join(pivot_tmp, pivot_root_old);
if (!pivot_tmp_pivot_root_old) {
r = log_oom();
goto done;
}
r = mount_nofollow_verbose(LOG_ERR, directory_pivot_root_new, pivot_tmp, NULL, MS_MOVE, NULL);
if (r < 0)
goto done;
r = mount_nofollow_verbose(LOG_ERR, directory, pivot_tmp_pivot_root_old, NULL, MS_MOVE, NULL);
if (r < 0)
goto done;
r = mount_nofollow_verbose(LOG_ERR, pivot_tmp, directory, NULL, MS_MOVE, NULL);
if (r < 0)
goto done;
} else {
r = mount_nofollow_verbose(LOG_ERR, directory_pivot_root_new, directory, NULL, MS_MOVE, NULL);
if (r < 0)
goto done;
}
done:
if (remove_pivot_tmp)
(void) rmdir(pivot_tmp);
return r;
}
#define NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS "/run/host/proc"
#define NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS "/run/host/sys"
int pin_fully_visible_fs(void) {
int r;
(void) mkdir_p(NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS, 0755);
(void) mkdir_p(NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS, 0755);
r = mount_follow_verbose(LOG_ERR, "proc", NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS, "proc", PROC_DEFAULT_MOUNT_FLAGS, NULL);
if (r < 0)
return r;
r = mount_follow_verbose(LOG_ERR, "sysfs", NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS, "sysfs", SYS_DEFAULT_MOUNT_FLAGS, NULL);
if (r < 0)
return r;
return 0;
}
static int do_wipe_fully_visible_fs(void) {
if (umount2(NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS, MNT_DETACH) < 0)
return log_error_errno(errno, "Failed to unmount temporary proc: %m");
if (rmdir(NSPAWN_PRIVATE_FULLY_VISIBLE_PROCFS) < 0)
return log_error_errno(errno, "Failed to remove temporary proc mountpoint: %m");
if (umount2(NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS, MNT_DETACH) < 0)
return log_error_errno(errno, "Failed to unmount temporary sys: %m");
if (rmdir(NSPAWN_PRIVATE_FULLY_VISIBLE_SYSFS) < 0)
return log_error_errno(errno, "Failed to remove temporary sys mountpoint: %m");
return 0;
}
int wipe_fully_visible_fs(int mntns_fd) {
_cleanup_close_ int orig_mntns_fd = -EBADF;
int r, rr;
r = namespace_open(0, NULL, &orig_mntns_fd, NULL, NULL, NULL);
if (r < 0)
return log_error_errno(r, "Failed to pin originating mount namespace: %m");
r = namespace_enter(-EBADF, mntns_fd, -EBADF, -EBADF, -EBADF);
if (r < 0)
return log_error_errno(r, "Failed to enter mount namespace: %m");
rr = do_wipe_fully_visible_fs();
r = namespace_enter(-EBADF, orig_mntns_fd, -EBADF, -EBADF, -EBADF);
if (r < 0)
return log_error_errno(r, "Failed to enter original mount namespace: %m");
return rr;
}