1 /* SPDX-License-Identifier: LGPL-2.1+ */
7 #include <sys/statvfs.h>
10 #include "alloc-util.h"
12 #include "cgroup-util.h"
13 #include "dev-setup.h"
22 #include "mount-setup.h"
23 #include "mountpoint-util.h"
24 #include "path-util.h"
26 #include "smack-util.h"
28 #include "user-util.h"
32 typedef enum MountMode
{
35 MNT_IN_CONTAINER
= 1 << 1,
36 MNT_CHECK_WRITABLE
= 1 << 2,
39 typedef struct MountPoint
{
45 bool (*condition_fn
)(void);
49 /* The first three entries we might need before SELinux is up. The
50 * fourth (securityfs) is needed by IMA to load a custom policy. The
51 * other ones we can delay until SELinux and IMA are loaded. When
52 * SMACK is enabled we need smackfs, too, so it's a fifth one. */
54 #define N_EARLY_MOUNT 5
56 #define N_EARLY_MOUNT 4
59 static const MountPoint mount_table
[] = {
60 { "sysfs", "/sys", "sysfs", NULL
, MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
61 NULL
, MNT_FATAL
|MNT_IN_CONTAINER
},
62 { "proc", "/proc", "proc", NULL
, MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
63 NULL
, MNT_FATAL
|MNT_IN_CONTAINER
},
64 { "devtmpfs", "/dev", "devtmpfs", "mode=755", MS_NOSUID
|MS_STRICTATIME
,
65 NULL
, MNT_FATAL
|MNT_IN_CONTAINER
},
66 { "securityfs", "/sys/kernel/security", "securityfs", NULL
, MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
69 { "smackfs", "/sys/fs/smackfs", "smackfs", "smackfsdef=*", MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
70 mac_smack_use
, MNT_FATAL
},
71 { "tmpfs", "/dev/shm", "tmpfs", "mode=1777,smackfsroot=*", MS_NOSUID
|MS_NODEV
|MS_STRICTATIME
,
72 mac_smack_use
, MNT_FATAL
},
74 { "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID
|MS_NODEV
|MS_STRICTATIME
,
75 NULL
, MNT_FATAL
|MNT_IN_CONTAINER
},
76 { "devpts", "/dev/pts", "devpts", "mode=620,gid=" STRINGIFY(TTY_GID
), MS_NOSUID
|MS_NOEXEC
,
77 NULL
, MNT_IN_CONTAINER
},
79 { "tmpfs", "/run", "tmpfs", "mode=755,smackfsroot=*", MS_NOSUID
|MS_NODEV
|MS_STRICTATIME
,
80 mac_smack_use
, MNT_FATAL
},
82 { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID
|MS_NODEV
|MS_STRICTATIME
,
83 NULL
, MNT_FATAL
|MNT_IN_CONTAINER
},
84 { "cgroup2", "/sys/fs/cgroup", "cgroup2", "nsdelegate", MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
85 cg_is_unified_wanted
, MNT_IN_CONTAINER
|MNT_CHECK_WRITABLE
},
86 { "cgroup2", "/sys/fs/cgroup", "cgroup2", NULL
, MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
87 cg_is_unified_wanted
, MNT_IN_CONTAINER
|MNT_CHECK_WRITABLE
},
88 { "tmpfs", "/sys/fs/cgroup", "tmpfs", "mode=755", MS_NOSUID
|MS_NOEXEC
|MS_NODEV
|MS_STRICTATIME
,
89 cg_is_legacy_wanted
, MNT_FATAL
|MNT_IN_CONTAINER
},
90 { "cgroup2", "/sys/fs/cgroup/unified", "cgroup2", "nsdelegate", MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
91 cg_is_hybrid_wanted
, MNT_IN_CONTAINER
|MNT_CHECK_WRITABLE
},
92 { "cgroup2", "/sys/fs/cgroup/unified", "cgroup2", NULL
, MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
93 cg_is_hybrid_wanted
, MNT_IN_CONTAINER
|MNT_CHECK_WRITABLE
},
94 { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd,xattr", MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
95 cg_is_legacy_wanted
, MNT_IN_CONTAINER
},
96 { "cgroup", "/sys/fs/cgroup/systemd", "cgroup", "none,name=systemd", MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
97 cg_is_legacy_wanted
, MNT_FATAL
|MNT_IN_CONTAINER
},
98 { "pstore", "/sys/fs/pstore", "pstore", NULL
, MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
101 { "efivarfs", "/sys/firmware/efi/efivars", "efivarfs", NULL
, MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
102 is_efi_boot
, MNT_NONE
},
104 { "bpf", "/sys/fs/bpf", "bpf", "mode=700", MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
108 /* These are API file systems that might be mounted by other software,
109 * we just list them here so that we know that we should ignore them */
111 static const char ignore_paths
[] =
112 /* SELinux file systems */
114 /* Container bind mounts */
119 bool mount_point_is_api(const char *path
) {
122 /* Checks if this mount point is considered "API", and hence
123 * should be ignored */
125 for (i
= 0; i
< ELEMENTSOF(mount_table
); i
++)
126 if (path_equal(path
, mount_table
[i
].where
))
129 return path_startswith(path
, "/sys/fs/cgroup/");
132 bool mount_point_ignore(const char *path
) {
135 NULSTR_FOREACH(i
, ignore_paths
)
136 if (path_equal(path
, i
))
142 static int mount_one(const MountPoint
*p
, bool relabel
) {
147 priority
= (p
->mode
& MNT_FATAL
) ? LOG_ERR
: LOG_DEBUG
;
149 if (p
->condition_fn
&& !p
->condition_fn())
152 /* Relabel first, just in case */
154 (void) label_fix(p
->where
, LABEL_IGNORE_ENOENT
|LABEL_IGNORE_EROFS
);
156 r
= path_is_mount_point(p
->where
, NULL
, AT_SYMLINK_FOLLOW
);
157 if (r
< 0 && r
!= -ENOENT
) {
158 log_full_errno(priority
, r
, "Failed to determine whether %s is a mount point: %m", p
->where
);
159 return (p
->mode
& MNT_FATAL
) ? r
: 0;
164 /* Skip securityfs in a container */
165 if (!(p
->mode
& MNT_IN_CONTAINER
) && detect_container() > 0)
168 /* The access mode here doesn't really matter too much, since
169 * the mounted file system will take precedence anyway. */
171 (void) mkdir_p_label(p
->where
, 0755);
173 (void) mkdir_p(p
->where
, 0755);
175 log_debug("Mounting %s to %s of type %s with options %s.",
186 log_full_errno(priority
, errno
, "Failed to mount %s at %s: %m", p
->type
, p
->where
);
187 return (p
->mode
& MNT_FATAL
) ? -errno
: 0;
190 /* Relabel again, since we now mounted something fresh here */
192 (void) label_fix(p
->where
, 0);
194 if (p
->mode
& MNT_CHECK_WRITABLE
) {
195 if (access(p
->where
, W_OK
) < 0) {
198 (void) umount(p
->where
);
199 (void) rmdir(p
->where
);
201 log_full_errno(priority
, r
, "Mount point %s not writable after mounting: %m", p
->where
);
202 return (p
->mode
& MNT_FATAL
) ? r
: 0;
209 static int mount_points_setup(unsigned n
, bool loaded_policy
) {
213 for (i
= 0; i
< n
; i
++) {
216 j
= mount_one(mount_table
+ i
, loaded_policy
);
217 if (j
!= 0 && r
>= 0)
224 int mount_setup_early(void) {
225 assert_cc(N_EARLY_MOUNT
<= ELEMENTSOF(mount_table
));
227 /* Do a minimal mount of /proc and friends to enable the most
228 * basic stuff, such as SELinux */
229 return mount_points_setup(N_EARLY_MOUNT
, false);
232 static const char *join_with(const char *controller
) {
234 static const char* const pairs
[] = {
236 "net_cls", "net_prio",
240 const char *const *x
, *const *y
;
244 /* This will lookup which controller to mount another controller with. Input is a controller name, and output
245 * is the other controller name. The function works both ways: you can input one and get the other, and input
246 * the other to get the one. */
248 STRV_FOREACH_PAIR(x
, y
, pairs
) {
249 if (streq(controller
, *x
))
251 if (streq(controller
, *y
))
258 static int symlink_controller(const char *target
, const char *alias
) {
265 a
= strjoina("/sys/fs/cgroup/", alias
);
267 r
= symlink_idempotent(target
, a
, false);
269 return log_error_errno(r
, "Failed to create symlink %s: %m", a
);
271 #ifdef SMACK_RUN_LABEL
274 p
= strjoina("/sys/fs/cgroup/", target
);
276 r
= mac_smack_copy(a
, p
);
277 if (r
< 0 && r
!= -EOPNOTSUPP
)
278 return log_error_errno(r
, "Failed to copy smack label from %s to %s: %m", p
, a
);
284 int mount_cgroup_controllers(void) {
285 _cleanup_set_free_free_ Set
*controllers
= NULL
;
288 if (!cg_is_legacy_wanted())
291 /* Mount all available cgroup controllers that are built into the kernel. */
292 r
= cg_kernel_controllers(&controllers
);
294 return log_error_errno(r
, "Failed to enumerate cgroup controllers: %m");
297 _cleanup_free_
char *options
= NULL
, *controller
= NULL
, *where
= NULL
;
298 const char *other_controller
;
302 .flags
= MS_NOSUID
|MS_NOEXEC
|MS_NODEV
,
303 .mode
= MNT_IN_CONTAINER
,
306 controller
= set_steal_first(controllers
);
310 /* Check if we shall mount this together with another controller */
311 other_controller
= join_with(controller
);
312 if (other_controller
) {
313 _cleanup_free_
char *c
= NULL
;
315 /* Check if the other controller is actually available in the kernel too */
316 c
= set_remove(controllers
, other_controller
);
319 /* Join the two controllers into one string, and maintain a stable ordering */
320 if (strcmp(controller
, other_controller
) < 0)
321 options
= strjoin(controller
, ",", other_controller
);
323 options
= strjoin(other_controller
, ",", controller
);
329 /* The simple case, where there's only one controller to mount together */
331 options
= TAKE_PTR(controller
);
333 where
= strappend("/sys/fs/cgroup/", options
);
340 r
= mount_one(&p
, true);
344 /* Create symlinks from the individual controller names, in case we have a joined mount */
346 (void) symlink_controller(options
, controller
);
347 if (other_controller
)
348 (void) symlink_controller(options
, other_controller
);
351 /* Now that we mounted everything, let's make the tmpfs the cgroup file systems are mounted into read-only. */
352 (void) mount("tmpfs", "/sys/fs/cgroup", "tmpfs", MS_REMOUNT
|MS_NOSUID
|MS_NOEXEC
|MS_NODEV
|MS_STRICTATIME
|MS_RDONLY
, "mode=755");
357 #if HAVE_SELINUX || ENABLE_SMACK
360 const struct stat
*sb
,
362 struct FTW
*ftwbuf
) {
364 /* No need to label /dev twice in a row... */
365 if (_unlikely_(ftwbuf
->level
== 0))
368 (void) label_fix(fpath
, 0);
370 /* /run/initramfs is static data and big, no need to
371 * dynamically relabel its contents at boot... */
372 if (_unlikely_(ftwbuf
->level
== 1 &&
374 streq(fpath
, "/run/initramfs")))
375 return FTW_SKIP_SUBTREE
;
380 static int relabel_cgroup_filesystems(void) {
384 r
= cg_all_unified();
386 /* Temporarily remount the root cgroup filesystem to give it a proper label. Do this
387 only when the filesystem has been already populated by a previous instance of systemd
388 running from initrd. Otherwise don't remount anything and leave the filesystem read-write
389 for the cgroup filesystems to be mounted inside. */
390 if (statfs("/sys/fs/cgroup", &st
) < 0)
391 return log_error_errno(errno
, "Failed to determine mount flags for /sys/fs/cgroup: %m");
393 if (st
.f_flags
& ST_RDONLY
)
394 (void) mount(NULL
, "/sys/fs/cgroup", NULL
, MS_REMOUNT
, NULL
);
396 (void) label_fix("/sys/fs/cgroup", 0);
397 (void) nftw("/sys/fs/cgroup", nftw_cb
, 64, FTW_MOUNT
|FTW_PHYS
|FTW_ACTIONRETVAL
);
399 if (st
.f_flags
& ST_RDONLY
)
400 (void) mount(NULL
, "/sys/fs/cgroup", NULL
, MS_REMOUNT
|MS_RDONLY
, NULL
);
403 return log_error_errno(r
, "Failed to determine whether we are in all unified mode: %m");
409 int mount_setup(bool loaded_policy
) {
412 r
= mount_points_setup(ELEMENTSOF(mount_table
), loaded_policy
);
416 #if HAVE_SELINUX || ENABLE_SMACK
417 /* Nodes in devtmpfs and /run need to be manually updated for
418 * the appropriate labels, after mounting. The other virtual
419 * API file systems like /sys and /proc do not need that, they
420 * use the same label for all their files. */
422 usec_t before_relabel
, after_relabel
;
423 char timespan
[FORMAT_TIMESPAN_MAX
];
425 before_relabel
= now(CLOCK_MONOTONIC
);
427 (void) nftw("/dev", nftw_cb
, 64, FTW_MOUNT
|FTW_PHYS
|FTW_ACTIONRETVAL
);
428 (void) nftw("/dev/shm", nftw_cb
, 64, FTW_MOUNT
|FTW_PHYS
|FTW_ACTIONRETVAL
);
429 (void) nftw("/run", nftw_cb
, 64, FTW_MOUNT
|FTW_PHYS
|FTW_ACTIONRETVAL
);
431 r
= relabel_cgroup_filesystems();
435 after_relabel
= now(CLOCK_MONOTONIC
);
437 log_info("Relabelled /dev, /run and /sys/fs/cgroup in %s.",
438 format_timespan(timespan
, sizeof(timespan
), after_relabel
- before_relabel
, 0));
442 /* Create a few default symlinks, which are normally created
443 * by udevd, but some scripts might need them before we start
445 dev_setup(NULL
, UID_INVALID
, GID_INVALID
);
447 /* Mark the root directory as shared in regards to mount propagation. The kernel defaults to "private", but we
448 * think it makes more sense to have a default of "shared" so that nspawn and the container tools work out of
449 * the box. If specific setups need other settings they can reset the propagation mode to private if
450 * needed. Note that we set this only when we are invoked directly by the kernel. If we are invoked by a
451 * container manager we assume the container manager knows what it is doing (for example, because it set up
452 * some directories with different propagation modes). */
453 if (detect_container() <= 0)
454 if (mount(NULL
, "/", NULL
, MS_REC
|MS_SHARED
, NULL
) < 0)
455 log_warning_errno(errno
, "Failed to set up the root directory for shared mount propagation: %m");
457 /* Create a few directories we always want around, Note that sd_booted() checks for /run/systemd/system, so
458 * this mkdir really needs to stay for good, otherwise software that copied sd-daemon.c into their sources will
459 * misdetect systemd. */
460 (void) mkdir_label("/run/systemd", 0755);
461 (void) mkdir_label("/run/systemd/system", 0755);
463 /* Also create /run/systemd/inaccessible nodes, so that we always have something to mount inaccessible nodes
465 (void) make_inaccessible_nodes(NULL
, UID_INVALID
, GID_INVALID
);