[thirdparty/systemd.git] / src / core / machine-id-setup.c

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2010 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 <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <sys/mount.h>

#include "systemd/sd-id128.h"

#include "machine-id-setup.h"
#include "macro.h"
#include "util.h"
#include "mkdir.h"
#include "log.h"
#include "virt.h"
#include "fileio.h"
#include "path-util.h"
#include "process-util.h"

static int shorten_uuid(char destination[34], const char source[36]) {
        unsigned i, j;

        assert(destination);
        assert(source);

        /* Converts a UUID into a machine ID, by lowercasing it and
         * removing dashes. Validates everything. */

        for (i = 0, j = 0; i < 36 && j < 32; i++) {
                int t;

                t = unhexchar(source[i]);
                if (t < 0)
                        continue;

                destination[j++] = hexchar(t);
        }

        if (i != 36 || j != 32)
                return -EINVAL;

        destination[32] = '\n';
        destination[33] = 0;
        return 0;
}

static int read_machine_id(int fd, char id[34]) {
        char id_to_validate[34];
        int r;

        assert(fd >= 0);
        assert(id);

        /* Reads a machine ID from a file, validates it, and returns
         * it. The returned ID ends in a newline. */

        r = loop_read_exact(fd, id_to_validate, 33, false);
        if (r < 0)
                return r;

        if (id_to_validate[32] != '\n')
                return -EINVAL;

        id_to_validate[32] = 0;

        if (!id128_is_valid(id_to_validate))
                return -EINVAL;

        memcpy(id, id_to_validate, 32);
        id[32] = '\n';
        id[33] = 0;
        return 0;
}

static int write_machine_id(int fd, char id[34]) {
        assert(fd >= 0);
        assert(id);

        if (lseek(fd, 0, SEEK_SET) < 0)
                return -errno;

        return loop_write(fd, id, 33, false);
}

static int generate_machine_id(char id[34], const char *root) {
        int fd, r;
        unsigned char *p;
        sd_id128_t buf;
        char  *q;
        const char *dbus_machine_id;

        assert(id);

        if (isempty(root))
                dbus_machine_id = "/var/lib/dbus/machine-id";
        else
                dbus_machine_id = strjoina(root, "/var/lib/dbus/machine-id");

        /* First, try reading the D-Bus machine id, unless it is a symlink */
        fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
        if (fd >= 0) {
                r = read_machine_id(fd, id);
                safe_close(fd);

                if (r >= 0) {
                        log_info("Initializing machine ID from D-Bus machine ID.");
                        return 0;
                }
        }

        if (isempty(root)) {
                /* If that didn't work, see if we are running in a container,
                 * and a machine ID was passed in via $container_uuid the way
                 * libvirt/LXC does it */

                if (detect_container() > 0) {
                        _cleanup_free_ char *e = NULL;

                        r = getenv_for_pid(1, "container_uuid", &e);
                        if (r > 0) {
                                r = shorten_uuid(id, e);
                                if (r >= 0) {
                                        log_info("Initializing machine ID from container UUID.");
                                        return 0;
                                }
                        }

                } else if (detect_vm() == VIRTUALIZATION_KVM) {

                        /* If we are not running in a container, see if we are
                         * running in qemu/kvm and a machine ID was passed in
                         * via -uuid on the qemu/kvm command line */

                        char uuid[36];

                        fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
                        if (fd >= 0) {
                                r = loop_read_exact(fd, uuid, 36, false);
                                safe_close(fd);

                                if (r >= 0) {
                                        r = shorten_uuid(id, uuid);
                                        if (r >= 0) {
                                                log_info("Initializing machine ID from KVM UUID.");
                                                return 0;
                                        }
                                }
                        }
                }
        }

        /* If that didn't work, generate a random machine id */
        r = sd_id128_randomize(&buf);
        if (r < 0)
                return log_error_errno(r, "Failed to open /dev/urandom: %m");

        for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {
                q[0] = hexchar(*p >> 4);
                q[1] = hexchar(*p & 15);
        }

        id[32] = '\n';
        id[33] = 0;

        log_info("Initializing machine ID from random generator.");

        return 0;
}

int machine_id_setup(const char *root) {
        const char *etc_machine_id, *run_machine_id;
        _cleanup_close_ int fd = -1;
        bool writable = true;
        char id[34]; /* 32 + \n + \0 */
        int r;

        if (isempty(root))  {
                etc_machine_id = "/etc/machine-id";
                run_machine_id = "/run/machine-id";
        } else {
                char *x;

                x = strjoina(root, "/etc/machine-id");
                etc_machine_id = path_kill_slashes(x);

                x = strjoina(root, "/run/machine-id");
                run_machine_id = path_kill_slashes(x);
        }

        RUN_WITH_UMASK(0000) {
                /* We create this 0444, to indicate that this isn't really
                 * something you should ever modify. Of course, since the file
                 * will be owned by root it doesn't matter much, but maybe
                 * people look. */

                mkdir_parents(etc_machine_id, 0755);
                fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
                if (fd < 0) {
                        int old_errno = errno;

                        fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
                        if (fd < 0) {
                                if (old_errno == EROFS && errno == ENOENT)
                                        log_error_errno(errno,
                                                  "System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
                                                  "Booting up is supported only when:\n"
                                                  "1) /etc/machine-id exists and is populated.\n"
                                                  "2) /etc/machine-id exists and is empty.\n"
                                                  "3) /etc/machine-id is missing and /etc is writable.\n");
                                else
                                        log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);

                                return -errno;
                        }

                        writable = false;
                }
        }

        if (read_machine_id(fd, id) >= 0)
                return 0;

        /* Hmm, so, the id currently stored is not useful, then let's
         * generate one */

        r = generate_machine_id(id, root);
        if (r < 0)
                return r;

        if (writable)
                if (write_machine_id(fd, id) >= 0)
                        return 0;

        fd = safe_close(fd);

        /* Hmm, we couldn't write it? So let's write it to
         * /run/machine-id as a replacement */

        RUN_WITH_UMASK(0022) {
                r = write_string_file(run_machine_id, id, WRITE_STRING_FILE_CREATE);
        }
        if (r < 0) {
                (void) unlink(run_machine_id);
                return log_error_errno(r, "Cannot write %s: %m", run_machine_id);
        }

        /* And now, let's mount it over */
        if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) {
                (void) unlink_noerrno(run_machine_id);
                return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
        }

        log_info("Installed transient %s file.", etc_machine_id);

        /* Mark the mount read-only */
        if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
                log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);

        return 0;
}

int machine_id_commit(const char *root) {
        _cleanup_close_ int fd = -1, initial_mntns_fd = -1;
        const char *etc_machine_id;
        char id[34]; /* 32 + \n + \0 */
        int r;

        if (isempty(root))
                etc_machine_id = "/etc/machine-id";
        else {
                char *x;

                x = strjoina(root, "/etc/machine-id");
                etc_machine_id = path_kill_slashes(x);
        }

        r = path_is_mount_point(etc_machine_id, 0);
        if (r < 0)
                return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id);
        if (r == 0) {
                log_debug("%s is is not a mount point. Nothing to do.", etc_machine_id);
                return 0;
        }

        /* Read existing machine-id */
        fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY);
        if (fd < 0)
                return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);

        r = read_machine_id(fd, id);
        if (r < 0)
                return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id);

        r = fd_is_temporary_fs(fd);
        if (r < 0)
                return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id);
        if (r == 0) {
                log_error("%s is not on a temporary file system.", etc_machine_id);
                return -EROFS;
        }

        fd = safe_close(fd);

        /* Store current mount namespace */
        r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL, NULL);
        if (r < 0)
                return log_error_errno(r, "Can't fetch current mount namespace: %m");

        /* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */
        if (unshare(CLONE_NEWNS) < 0)
                return log_error_errno(errno, "Failed to enter new namespace: %m");

        if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0)
                return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m");

        if (umount(etc_machine_id) < 0)
                return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id);

        /* Update a persistent version of etc_machine_id */
        fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
        if (fd < 0)
                return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id);

        r = write_machine_id(fd, id);
        if (r < 0)
                return log_error_errno(r, "Cannot write %s: %m", etc_machine_id);

        fd = safe_close(fd);

        /* Return to initial namespace and proceed a lazy tmpfs unmount */
        r = namespace_enter(-1, initial_mntns_fd, -1, -1, -1);
        if (r < 0)
                return log_warning_errno(r, "Failed to switch back to initial mount namespace: %m.\nWe'll keep transient %s file until next reboot.", etc_machine_id);

        if (umount2(etc_machine_id, MNT_DETACH) < 0)
                return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id);

        return 0;
}
Commit	Line	Data
d7ccca2e LP	1	/-- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil --/
	2
	3	/***
	4	This file is part of systemd.
	5
	6	Copyright 2010 Lennart Poettering
	7
	8	systemd is free software; you can redistribute it and/or modify it
5430f7f2 LP	9	under the terms of the GNU Lesser General Public License as published by
5430f7f2 LP	10	the Free Software Foundation; either version 2.1 of the License, or
d7ccca2e LP	11	(at your option) any later version.
	12
	13	systemd is distributed in the hope that it will be useful, but
	14	WITHOUT ANY WARRANTY; without even the implied warranty of
	15	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
5430f7f2	16	Lesser General Public License for more details.
d7ccca2e	17
5430f7f2	18	You should have received a copy of the GNU Lesser General Public License
d7ccca2e LP	19	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	20	***/
	21
	22	#include <unistd.h>
	23	#include <stdio.h>
	24	#include <errno.h>
	25	#include <string.h>
d7ccca2e LP	26	#include <fcntl.h>
	27	#include <sys/mount.h>
	28
73f860db	29	#include "systemd/sd-id128.h"
81527be1	30
b6e66135	31	#include "machine-id-setup.h"
d7ccca2e LP	32	#include "macro.h"
d7ccca2e LP	33	#include "util.h"
49e942b2	34	#include "mkdir.h"
d7ccca2e	35	#include "log.h"
d4eb120a	36	#include "virt.h"
a5c32cff	37	#include "fileio.h"
fe970a8a	38	#include "path-util.h"
0b452006	39	#include "process-util.h"
8d41a963	40
34f750b7	41	static int shorten_uuid(char destination[34], const char source[36]) {
09b967ea LP	42	unsigned i, j;
09b967ea LP	43
c6ac7e4b LP	44	assert(destination);
	45	assert(source);
	46
	47	/* Converts a UUID into a machine ID, by lowercasing it and
	48	* removing dashes. Validates everything. */
	49
09b967ea LP	50	for (i = 0, j = 0; i < 36 && j < 32; i++) {
	51	int t;
	52
	53	t = unhexchar(source[i]);
	54	if (t < 0)
	55	continue;
	56
	57	destination[j++] = hexchar(t);
	58	}
	59
c6ac7e4b LP	60	if (i != 36 \|\| j != 32)
	61	return -EINVAL;
	62
	63	destination[32] = '\n';
	64	destination[33] = 0;
	65	return 0;
	66	}
	67
	68	static int read_machine_id(int fd, char id[34]) {
	69	char id_to_validate[34];
	70	int r;
	71
	72	assert(fd >= 0);
	73	assert(id);
	74
	75	/* Reads a machine ID from a file, validates it, and returns
	76	* it. The returned ID ends in a newline. */
	77
	78	r = loop_read_exact(fd, id_to_validate, 33, false);
	79	if (r < 0)
	80	return r;
	81
	82	if (id_to_validate[32] != '\n')
	83	return -EINVAL;
	84
	85	id_to_validate[32] = 0;
	86
	87	if (!id128_is_valid(id_to_validate))
	88	return -EINVAL;
	89
	90	memcpy(id, id_to_validate, 32);
	91	id[32] = '\n';
	92	id[33] = 0;
	93	return 0;
	94	}
09b967ea	95
c6ac7e4b LP	96	static int write_machine_id(int fd, char id[34]) {
	97	assert(fd >= 0);
	98	assert(id);
	99
	100	if (lseek(fd, 0, SEEK_SET) < 0)
	101	return -errno;
	102
	103	return loop_write(fd, id, 33, false);
09b967ea LP	104	}
09b967ea LP	105
c6ac7e4b	106	static int generate_machine_id(char id[34], const char *root) {
87d2c1ff LP	107	int fd, r;
	108	unsigned char *p;
	109	sd_id128_t buf;
5dd6d0f8	110	char *q;
75f86906	111	const char *dbus_machine_id;
d7ccca2e LP	112
	113	assert(id);
	114
5dd6d0f8 LP	115	if (isempty(root))
	116	dbus_machine_id = "/var/lib/dbus/machine-id";
	117	else
63c372cb	118	dbus_machine_id = strjoina(root, "/var/lib/dbus/machine-id");
92f2f92e	119
d7ccca2e	120	/* First, try reading the D-Bus machine id, unless it is a symlink */
92f2f92e	121	fd = open(dbus_machine_id, O_RDONLY\|O_CLOEXEC\|O_NOCTTY\|O_NOFOLLOW);
8d41a963	122	if (fd >= 0) {
c6ac7e4b	123	r = read_machine_id(fd, id);
03e334a1	124	safe_close(fd);
d7ccca2e	125
c6ac7e4b LP	126	if (r >= 0) {
	127	log_info("Initializing machine ID from D-Bus machine ID.");
	128	return 0;
d7ccca2e LP	129	}
	130	}
	131
5dd6d0f8 LP	132	if (isempty(root)) {
	133	/* If that didn't work, see if we are running in a container,
	134	* and a machine ID was passed in via $container_uuid the way
	135	* libvirt/LXC does it */
75f86906 LP	136
75f86906 LP	137	if (detect_container() > 0) {
5dd6d0f8	138	_cleanup_free_ char *e = NULL;
0b36bbc4	139
5dd6d0f8 LP	140	r = getenv_for_pid(1, "container_uuid", &e);
5dd6d0f8 LP	141	if (r > 0) {
c6ac7e4b LP	142	r = shorten_uuid(id, e);
	143	if (r >= 0) {
	144	log_info("Initializing machine ID from container UUID.");
	145	return 0;
0b36bbc4 LP	146	}
0b36bbc4 LP	147	}
5dd6d0f8	148
75f86906 LP	149	} else if (detect_vm() == VIRTUALIZATION_KVM) {
75f86906 LP	150
5dd6d0f8 LP	151	/* If we are not running in a container, see if we are
	152	* running in qemu/kvm and a machine ID was passed in
	153	* via -uuid on the qemu/kvm command line */
	154
75f86906	155	char uuid[36];
5dd6d0f8	156
75f86906 LP	157	fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY\|O_CLOEXEC\|O_NOCTTY\|O_NOFOLLOW);
	158	if (fd >= 0) {
	159	r = loop_read_exact(fd, uuid, 36, false);
	160	safe_close(fd);
5dd6d0f8	161
75f86906 LP	162	if (r >= 0) {
75f86906 LP	163	r = shorten_uuid(id, uuid);
a6dcc7e5	164	if (r >= 0) {
75f86906 LP	165	log_info("Initializing machine ID from KVM UUID.");
75f86906 LP	166	return 0;
5dd6d0f8 LP	167	}
	168	}
	169	}
0b36bbc4	170	}
d4eb120a LP	171	}
d4eb120a LP	172
d7ccca2e	173	/* If that didn't work, generate a random machine id */
87d2c1ff	174	r = sd_id128_randomize(&buf);
23bbb0de MS	175	if (r < 0)
23bbb0de MS	176	return log_error_errno(r, "Failed to open /dev/urandom: %m");
d7ccca2e	177
87d2c1ff	178	for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {
d7ccca2e LP	179	q[0] = hexchar(*p >> 4);
	180	q[1] = hexchar(*p & 15);
	181	}
	182
	183	id[32] = '\n';
	184	id[33] = 0;
	185
	186	log_info("Initializing machine ID from random generator.");
	187
	188	return 0;
	189	}
	190
c6ac7e4b LP	191	int machine_id_setup(const char *root) {
	192	const char etc_machine_id, run_machine_id;
	193	_cleanup_close_ int fd = -1;
	194	bool writable = true;
	195	char id[34]; /* 32 + \n + \0 */
	196	int r;
9496e375	197
c6ac7e4b LP	198	if (isempty(root)) {
	199	etc_machine_id = "/etc/machine-id";
	200	run_machine_id = "/run/machine-id";
	201	} else {
	202	char *x;
9496e375	203
c6ac7e4b LP	204	x = strjoina(root, "/etc/machine-id");
c6ac7e4b LP	205	etc_machine_id = path_kill_slashes(x);
9496e375	206
c6ac7e4b LP	207	x = strjoina(root, "/run/machine-id");
c6ac7e4b LP	208	run_machine_id = path_kill_slashes(x);
9496e375 DR	209	}
9496e375 DR	210
c6ac7e4b LP	211	RUN_WITH_UMASK(0000) {
	212	/* We create this 0444, to indicate that this isn't really
	213	* something you should ever modify. Of course, since the file
	214	* will be owned by root it doesn't matter much, but maybe
	215	* people look. */
9496e375	216
c6ac7e4b LP	217	mkdir_parents(etc_machine_id, 0755);
	218	fd = open(etc_machine_id, O_RDWR\|O_CREAT\|O_CLOEXEC\|O_NOCTTY, 0444);
	219	if (fd < 0) {
	220	int old_errno = errno;
	221
	222	fd = open(etc_machine_id, O_RDONLY\|O_CLOEXEC\|O_NOCTTY);
	223	if (fd < 0) {
	224	if (old_errno == EROFS && errno == ENOENT)
	225	log_error_errno(errno,
	226	"System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
	227	"Booting up is supported only when:\n"
	228	"1) /etc/machine-id exists and is populated.\n"
	229	"2) /etc/machine-id exists and is empty.\n"
	230	"3) /etc/machine-id is missing and /etc is writable.\n");
	231	else
	232	log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
	233
	234	return -errno;
	235	}
9496e375	236
c6ac7e4b LP	237	writable = false;
	238	}
	239	}
	240
	241	if (read_machine_id(fd, id) >= 0)
9496e375 DR	242	return 0;
9496e375 DR	243
c6ac7e4b LP	244	/* Hmm, so, the id currently stored is not useful, then let's
	245	* generate one */
	246
	247	r = generate_machine_id(id, root);
	248	if (r < 0)
	249	return r;
	250
	251	if (writable)
	252	if (write_machine_id(fd, id) >= 0)
	253	return 0;
	254
	255	fd = safe_close(fd);
	256
	257	/* Hmm, we couldn't write it? So let's write it to
	258	* /run/machine-id as a replacement */
	259
	260	RUN_WITH_UMASK(0022) {
4c1fc3e4	261	r = write_string_file(run_machine_id, id, WRITE_STRING_FILE_CREATE);
c6ac7e4b LP	262	}
	263	if (r < 0) {
	264	(void) unlink(run_machine_id);
	265	return log_error_errno(r, "Cannot write %s: %m", run_machine_id);
	266	}
	267
	268	/* And now, let's mount it over */
	269	if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) {
	270	(void) unlink_noerrno(run_machine_id);
	271	return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
	272	}
	273
	274	log_info("Installed transient %s file.", etc_machine_id);
	275
	276	/* Mark the mount read-only */
	277	if (mount(NULL, etc_machine_id, NULL, MS_BIND\|MS_RDONLY\|MS_REMOUNT, NULL) < 0)
	278	log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);
	279
	280	return 0;
9496e375 DR	281	}
9496e375 DR	282
979ef53a DR	283	int machine_id_commit(const char *root) {
	284	_cleanup_close_ int fd = -1, initial_mntns_fd = -1;
	285	const char *etc_machine_id;
	286	char id[34]; /* 32 + \n + \0 */
	287	int r;
	288
	289	if (isempty(root))
	290	etc_machine_id = "/etc/machine-id";
	291	else {
	292	char *x;
	293
63c372cb	294	x = strjoina(root, "/etc/machine-id");
979ef53a DR	295	etc_machine_id = path_kill_slashes(x);
	296	}
	297
e26d6ce5	298	r = path_is_mount_point(etc_machine_id, 0);
979ef53a	299	if (r < 0)
f131770b	300	return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id);
979ef53a DR	301	if (r == 0) {
	302	log_debug("%s is is not a mount point. Nothing to do.", etc_machine_id);
	303	return 0;
	304	}
	305
	306	/* Read existing machine-id */
	307	fd = open(etc_machine_id, O_RDONLY\|O_CLOEXEC\|O_NOCTTY);
	308	if (fd < 0)
	309	return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
	310
c6ac7e4b	311	r = read_machine_id(fd, id);
979ef53a DR	312	if (r < 0)
	313	return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id);
	314
c6878637	315	r = fd_is_temporary_fs(fd);
979ef53a DR	316	if (r < 0)
	317	return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id);
	318	if (r == 0) {
	319	log_error("%s is not on a temporary file system.", etc_machine_id);
	320	return -EROFS;
	321	}
	322
	323	fd = safe_close(fd);
	324
	325	/* Store current mount namespace */
671c3419	326	r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL, NULL);
979ef53a DR	327	if (r < 0)
	328	return log_error_errno(r, "Can't fetch current mount namespace: %m");
	329
	330	/* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */
	331	if (unshare(CLONE_NEWNS) < 0)
	332	return log_error_errno(errno, "Failed to enter new namespace: %m");
	333
	334	if (mount(NULL, "/", NULL, MS_SLAVE \| MS_REC, NULL) < 0)
	335	return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m");
	336
	337	if (umount(etc_machine_id) < 0)
	338	return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id);
	339
	340	/* Update a persistent version of etc_machine_id */
	341	fd = open(etc_machine_id, O_RDWR\|O_CREAT\|O_CLOEXEC\|O_NOCTTY, 0444);
	342	if (fd < 0)
	343	return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id);
	344
	345	r = write_machine_id(fd, id);
	346	if (r < 0)
	347	return log_error_errno(r, "Cannot write %s: %m", etc_machine_id);
	348
	349	fd = safe_close(fd);
	350
	351	/* Return to initial namespace and proceed a lazy tmpfs unmount */
671c3419	352	r = namespace_enter(-1, initial_mntns_fd, -1, -1, -1);
979ef53a DR	353	if (r < 0)
	354	return log_warning_errno(r, "Failed to switch back to initial mount namespace: %m.\nWe'll keep transient %s file until next reboot.", etc_machine_id);
	355
	356	if (umount2(etc_machine_id, MNT_DETACH) < 0)
	357	return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id);
	358
	359	return 0;
	360	}