picnoir/Systemd
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity
Systemd/src/core/machine-id-setup.c
Lennart Poettering 0c69794138 tree-wide: remove Lennart's copyright lines 
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
2018-06-14 10:20:20 +02:00

245 lines
9.7 KiB
C
Raw Blame History

/* SPDX-License-Identifier: LGPL-2.1+ */
#include <fcntl.h>
#include <sched.h>
#include <sys/mount.h>
#include <unistd.h>
#include "sd-id128.h"
#include "alloc-util.h"
#include "fd-util.h"
#include "fs-util.h"
#include "id128-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 "stat-util.h"
#include "string-util.h"
#include "umask-util.h"
#include "util.h"
#include "virt.h"
static int generate_machine_id(const char *root, sd_id128_t *ret) {
const char *dbus_machine_id;
_cleanup_close_ int fd = -1;
int r;
assert(ret);
/* First, try reading the D-Bus machine id, unless it is a symlink */
dbus_machine_id = prefix_roota(root, "/var/lib/dbus/machine-id");
fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd >= 0) {
if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0) {
log_info("Initializing machine ID from D-Bus machine ID.");
return 0;
}
fd = safe_close(fd);
}
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;
if (getenv_for_pid(1, "container_uuid", &e) > 0 &&
sd_id128_from_string(e, ret) >= 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 */
if (id128_read("/sys/class/dmi/id/product_uuid", ID128_UUID, ret) >= 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(ret);
if (r < 0)
return log_error_errno(r, "Failed to generate randomized : %m");
log_info("Initializing machine ID from random generator.");
return 0;
}
int machine_id_setup(const char *root, sd_id128_t machine_id, sd_id128_t *ret) {
const char *etc_machine_id, *run_machine_id;
_cleanup_close_ int fd = -1;
bool writable;
int r;
etc_machine_id = prefix_roota(root, "/etc/machine-id");
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. */
(void) 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)
return 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
return log_error_errno(errno,
"Cannot open %s: %m", etc_machine_id);
}
writable = false;
} else
writable = true;
}
/* A we got a valid machine ID argument, that's what counts */
if (sd_id128_is_null(machine_id)) {
/* Try to read any existing machine ID */
if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0)
return 0;
/* Hmm, so, the id currently stored is not useful, then let's generate one */
r = generate_machine_id(root, &machine_id);
if (r < 0)
return r;
}
if (writable) {
if (lseek(fd, 0, SEEK_SET) == (off_t) -1)
return log_error_errno(errno, "Failed to seek %s: %m", etc_machine_id);
if (ftruncate(fd, 0) < 0)
return log_error_errno(errno, "Failed to truncate %s: %m", etc_machine_id);
if (id128_write_fd(fd, ID128_PLAIN, machine_id, true) >= 0)
goto finish;
}
fd = safe_close(fd);
/* Hmm, we couldn't write it? So let's write it to /run/machine-id as a replacement */
run_machine_id = prefix_roota(root, "/run/machine-id");
RUN_WITH_UMASK(0022)
r = id128_write(run_machine_id, ID128_PLAIN, machine_id, false);
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, ignoring: %m", etc_machine_id);
finish:
if (ret)
*ret = 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;
sd_id128_t id;
int r;
/* Replaces a tmpfs bind mount of /etc/machine-id by a proper file, atomically. For this, the umount is removed
* in a mount namespace, a new file is created at the right place. Afterwards the mount is also removed in the
* original mount namespace, thus revealing the file that was just created. */
etc_machine_id = prefix_roota(root, "/etc/machine-id");
r = path_is_mount_point(etc_machine_id, NULL, 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 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 = 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;
}
r = id128_read_fd(fd, ID128_PLAIN, &id);
if (r < 0)
return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id);
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 */
r = id128_write(etc_machine_id, ID128_PLAIN, id, true);
if (r < 0)
return log_error_errno(r, "Cannot write %s. This is mandatory to get a persistent machine ID: %m", etc_machine_id);
/* 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;
}
Reference in a new issue View git blame Copy permalink