[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 <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <stdio.h>
#include <string.h>
#include <sys/mount.h>
#include <unistd.h>

#include "sd-id128.h"

#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "hexdecoct.h"
#include "io-util.h"
#include "log.h"
#include "machine-id-setup.h"
#include "macro.h"
#include "mkdir.h"
#include "mount-util.h"
#include "path-util.h"
#include "process-util.h"
#include "string-util.h"
#include "util.h"
#include "virt.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
d7ccca2e	22	#include <errno.h>
d7ccca2e	23	#include <fcntl.h>
618234a5 LP	24	#include <sched.h>
	25	#include <stdio.h>
	26	#include <string.h>
d7ccca2e	27	#include <sys/mount.h>
618234a5	28	#include <unistd.h>
d7ccca2e	29
618234a5	30	#include "sd-id128.h"
81527be1	31
3ffd4af2	32	#include "fd-util.h"
618234a5	33	#include "fileio.h"
f4f15635	34	#include "fs-util.h"
4349cd7c	35	#include "hexdecoct.h"
c004493c	36	#include "io-util.h"
618234a5	37	#include "log.h"
3ffd4af2	38	#include "machine-id-setup.h"
d7ccca2e	39	#include "macro.h"
49e942b2	40	#include "mkdir.h"
4349cd7c	41	#include "mount-util.h"
fe970a8a	42	#include "path-util.h"
0b452006	43	#include "process-util.h"
07630cea	44	#include "string-util.h"
618234a5 LP	45	#include "util.h"
618234a5 LP	46	#include "virt.h"
8d41a963	47
34f750b7	48	static int shorten_uuid(char destination[34], const char source[36]) {
09b967ea LP	49	unsigned i, j;
09b967ea LP	50
c6ac7e4b LP	51	assert(destination);
	52	assert(source);
	53
	54	/* Converts a UUID into a machine ID, by lowercasing it and
	55	* removing dashes. Validates everything. */
	56
09b967ea LP	57	for (i = 0, j = 0; i < 36 && j < 32; i++) {
	58	int t;
	59
	60	t = unhexchar(source[i]);
	61	if (t < 0)
	62	continue;
	63
	64	destination[j++] = hexchar(t);
	65	}
	66
c6ac7e4b LP	67	if (i != 36 \|\| j != 32)
	68	return -EINVAL;
	69
	70	destination[32] = '\n';
	71	destination[33] = 0;
	72	return 0;
	73	}
	74
	75	static int read_machine_id(int fd, char id[34]) {
	76	char id_to_validate[34];
	77	int r;
	78
	79	assert(fd >= 0);
	80	assert(id);
	81
	82	/* Reads a machine ID from a file, validates it, and returns
	83	* it. The returned ID ends in a newline. */
	84
	85	r = loop_read_exact(fd, id_to_validate, 33, false);
	86	if (r < 0)
	87	return r;
	88
	89	if (id_to_validate[32] != '\n')
	90	return -EINVAL;
	91
	92	id_to_validate[32] = 0;
	93
	94	if (!id128_is_valid(id_to_validate))
	95	return -EINVAL;
	96
	97	memcpy(id, id_to_validate, 32);
	98	id[32] = '\n';
	99	id[33] = 0;
	100	return 0;
	101	}
09b967ea	102
c6ac7e4b LP	103	static int write_machine_id(int fd, char id[34]) {
	104	assert(fd >= 0);
	105	assert(id);
	106
	107	if (lseek(fd, 0, SEEK_SET) < 0)
	108	return -errno;
	109
	110	return loop_write(fd, id, 33, false);
09b967ea LP	111	}
09b967ea LP	112
c6ac7e4b	113	static int generate_machine_id(char id[34], const char *root) {
87d2c1ff LP	114	int fd, r;
	115	unsigned char *p;
	116	sd_id128_t buf;
5dd6d0f8	117	char *q;
75f86906	118	const char *dbus_machine_id;
d7ccca2e LP	119
	120	assert(id);
	121
5dd6d0f8 LP	122	if (isempty(root))
	123	dbus_machine_id = "/var/lib/dbus/machine-id";
	124	else
63c372cb	125	dbus_machine_id = strjoina(root, "/var/lib/dbus/machine-id");
92f2f92e	126
d7ccca2e	127	/* First, try reading the D-Bus machine id, unless it is a symlink */
92f2f92e	128	fd = open(dbus_machine_id, O_RDONLY\|O_CLOEXEC\|O_NOCTTY\|O_NOFOLLOW);
8d41a963	129	if (fd >= 0) {
c6ac7e4b	130	r = read_machine_id(fd, id);
03e334a1	131	safe_close(fd);
d7ccca2e	132
c6ac7e4b LP	133	if (r >= 0) {
	134	log_info("Initializing machine ID from D-Bus machine ID.");
	135	return 0;
d7ccca2e LP	136	}
	137	}
	138
5dd6d0f8 LP	139	if (isempty(root)) {
	140	/* If that didn't work, see if we are running in a container,
	141	* and a machine ID was passed in via $container_uuid the way
	142	* libvirt/LXC does it */
75f86906 LP	143
75f86906 LP	144	if (detect_container() > 0) {
5dd6d0f8	145	_cleanup_free_ char *e = NULL;
0b36bbc4	146
5dd6d0f8 LP	147	r = getenv_for_pid(1, "container_uuid", &e);
5dd6d0f8 LP	148	if (r > 0) {
c6ac7e4b LP	149	r = shorten_uuid(id, e);
	150	if (r >= 0) {
	151	log_info("Initializing machine ID from container UUID.");
	152	return 0;
0b36bbc4 LP	153	}
0b36bbc4 LP	154	}
5dd6d0f8	155
75f86906 LP	156	} else if (detect_vm() == VIRTUALIZATION_KVM) {
75f86906 LP	157
5dd6d0f8 LP	158	/* If we are not running in a container, see if we are
	159	* running in qemu/kvm and a machine ID was passed in
	160	* via -uuid on the qemu/kvm command line */
	161
75f86906	162	char uuid[36];
5dd6d0f8	163
75f86906 LP	164	fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY\|O_CLOEXEC\|O_NOCTTY\|O_NOFOLLOW);
	165	if (fd >= 0) {
	166	r = loop_read_exact(fd, uuid, 36, false);
	167	safe_close(fd);
5dd6d0f8	168
75f86906 LP	169	if (r >= 0) {
75f86906 LP	170	r = shorten_uuid(id, uuid);
a6dcc7e5	171	if (r >= 0) {
75f86906 LP	172	log_info("Initializing machine ID from KVM UUID.");
75f86906 LP	173	return 0;
5dd6d0f8 LP	174	}
	175	}
	176	}
0b36bbc4	177	}
d4eb120a LP	178	}
d4eb120a LP	179
d7ccca2e	180	/* If that didn't work, generate a random machine id */
87d2c1ff	181	r = sd_id128_randomize(&buf);
23bbb0de MS	182	if (r < 0)
23bbb0de MS	183	return log_error_errno(r, "Failed to open /dev/urandom: %m");
d7ccca2e	184
87d2c1ff	185	for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {
d7ccca2e LP	186	q[0] = hexchar(*p >> 4);
	187	q[1] = hexchar(*p & 15);
	188	}
	189
	190	id[32] = '\n';
	191	id[33] = 0;
	192
	193	log_info("Initializing machine ID from random generator.");
	194
	195	return 0;
	196	}
	197
c6ac7e4b LP	198	int machine_id_setup(const char *root) {
	199	const char etc_machine_id, run_machine_id;
	200	_cleanup_close_ int fd = -1;
	201	bool writable = true;
	202	char id[34]; /* 32 + \n + \0 */
	203	int r;
9496e375	204
c6ac7e4b LP	205	if (isempty(root)) {
	206	etc_machine_id = "/etc/machine-id";
	207	run_machine_id = "/run/machine-id";
	208	} else {
	209	char *x;
9496e375	210
c6ac7e4b LP	211	x = strjoina(root, "/etc/machine-id");
c6ac7e4b LP	212	etc_machine_id = path_kill_slashes(x);
9496e375	213
c6ac7e4b LP	214	x = strjoina(root, "/run/machine-id");
c6ac7e4b LP	215	run_machine_id = path_kill_slashes(x);
9496e375 DR	216	}
9496e375 DR	217
c6ac7e4b LP	218	RUN_WITH_UMASK(0000) {
	219	/* We create this 0444, to indicate that this isn't really
	220	* something you should ever modify. Of course, since the file
	221	* will be owned by root it doesn't matter much, but maybe
	222	* people look. */
9496e375	223
c6ac7e4b LP	224	mkdir_parents(etc_machine_id, 0755);
	225	fd = open(etc_machine_id, O_RDWR\|O_CREAT\|O_CLOEXEC\|O_NOCTTY, 0444);
	226	if (fd < 0) {
	227	int old_errno = errno;
	228
	229	fd = open(etc_machine_id, O_RDONLY\|O_CLOEXEC\|O_NOCTTY);
	230	if (fd < 0) {
	231	if (old_errno == EROFS && errno == ENOENT)
	232	log_error_errno(errno,
	233	"System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
	234	"Booting up is supported only when:\n"
	235	"1) /etc/machine-id exists and is populated.\n"
	236	"2) /etc/machine-id exists and is empty.\n"
	237	"3) /etc/machine-id is missing and /etc is writable.\n");
	238	else
	239	log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
	240
	241	return -errno;
	242	}
9496e375	243
c6ac7e4b LP	244	writable = false;
	245	}
	246	}
	247
	248	if (read_machine_id(fd, id) >= 0)
9496e375 DR	249	return 0;
9496e375 DR	250
c6ac7e4b LP	251	/* Hmm, so, the id currently stored is not useful, then let's
	252	* generate one */
	253
	254	r = generate_machine_id(id, root);
	255	if (r < 0)
	256	return r;
	257
	258	if (writable)
	259	if (write_machine_id(fd, id) >= 0)
	260	return 0;
	261
	262	fd = safe_close(fd);
	263
	264	/* Hmm, we couldn't write it? So let's write it to
	265	* /run/machine-id as a replacement */
	266
	267	RUN_WITH_UMASK(0022) {
4c1fc3e4	268	r = write_string_file(run_machine_id, id, WRITE_STRING_FILE_CREATE);
c6ac7e4b LP	269	}
	270	if (r < 0) {
	271	(void) unlink(run_machine_id);
	272	return log_error_errno(r, "Cannot write %s: %m", run_machine_id);
	273	}
	274
	275	/* And now, let's mount it over */
	276	if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) {
	277	(void) unlink_noerrno(run_machine_id);
	278	return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
	279	}
	280
	281	log_info("Installed transient %s file.", etc_machine_id);
	282
	283	/* Mark the mount read-only */
	284	if (mount(NULL, etc_machine_id, NULL, MS_BIND\|MS_RDONLY\|MS_REMOUNT, NULL) < 0)
	285	log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);
	286
	287	return 0;
9496e375 DR	288	}
9496e375 DR	289
979ef53a DR	290	int machine_id_commit(const char *root) {
	291	_cleanup_close_ int fd = -1, initial_mntns_fd = -1;
	292	const char *etc_machine_id;
	293	char id[34]; /* 32 + \n + \0 */
	294	int r;
	295
	296	if (isempty(root))
	297	etc_machine_id = "/etc/machine-id";
	298	else {
	299	char *x;
	300
63c372cb	301	x = strjoina(root, "/etc/machine-id");
979ef53a DR	302	etc_machine_id = path_kill_slashes(x);
	303	}
	304
e26d6ce5	305	r = path_is_mount_point(etc_machine_id, 0);
979ef53a	306	if (r < 0)
f131770b	307	return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id);
979ef53a DR	308	if (r == 0) {
	309	log_debug("%s is is not a mount point. Nothing to do.", etc_machine_id);
	310	return 0;
	311	}
	312
	313	/* Read existing machine-id */
	314	fd = open(etc_machine_id, O_RDONLY\|O_CLOEXEC\|O_NOCTTY);
	315	if (fd < 0)
	316	return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
	317
c6ac7e4b	318	r = read_machine_id(fd, id);
979ef53a DR	319	if (r < 0)
	320	return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id);
	321
c6878637	322	r = fd_is_temporary_fs(fd);
979ef53a DR	323	if (r < 0)
	324	return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id);
	325	if (r == 0) {
	326	log_error("%s is not on a temporary file system.", etc_machine_id);
	327	return -EROFS;
	328	}
	329
	330	fd = safe_close(fd);
	331
	332	/* Store current mount namespace */
671c3419	333	r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL, NULL);
979ef53a DR	334	if (r < 0)
	335	return log_error_errno(r, "Can't fetch current mount namespace: %m");
	336
	337	/* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */
	338	if (unshare(CLONE_NEWNS) < 0)
	339	return log_error_errno(errno, "Failed to enter new namespace: %m");
	340
	341	if (mount(NULL, "/", NULL, MS_SLAVE \| MS_REC, NULL) < 0)
	342	return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m");
	343
	344	if (umount(etc_machine_id) < 0)
	345	return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id);
	346
	347	/* Update a persistent version of etc_machine_id */
	348	fd = open(etc_machine_id, O_RDWR\|O_CREAT\|O_CLOEXEC\|O_NOCTTY, 0444);
	349	if (fd < 0)
	350	return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id);
	351
	352	r = write_machine_id(fd, id);
	353	if (r < 0)
	354	return log_error_errno(r, "Cannot write %s: %m", etc_machine_id);
	355
	356	fd = safe_close(fd);
	357
	358	/* Return to initial namespace and proceed a lazy tmpfs unmount */
671c3419	359	r = namespace_enter(-1, initial_mntns_fd, -1, -1, -1);
979ef53a DR	360	if (r < 0)
	361	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);
	362
	363	if (umount2(etc_machine_id, MNT_DETACH) < 0)
	364	return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id);
	365
	366	return 0;
	367	}