/*-*- 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 <stdlib.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"
static int shorten_uuid(char destination[34], const char source[36]) {
unsigned i, j;
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) {
destination[32] = '\n';
destination[33] = 0;
return 0;
}
return -EINVAL;
}
static int generate(char id[34], const char *root) {
int fd, r;
unsigned char *p;
sd_id128_t buf;
char *q;
ssize_t k;
const char *vm_id, *dbus_machine_id;
assert(id);
if (isempty(root))
dbus_machine_id = "/var/lib/dbus/machine-id";
else
dbus_machine_id = strappenda(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) {
k = loop_read(fd, id, 33, false);
safe_close(fd);
if (k == 33 && id[32] == '\n') {
id[32] = 0;
if (id128_is_valid(id)) {
id[32] = '\n';
id[33] = 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 */
r = detect_container(NULL);
if (r > 0) {
_cleanup_free_ char *e = NULL;
r = getenv_for_pid(1, "container_uuid", &e);
if (r > 0) {
if (strlen(e) >= 36) {
r = shorten_uuid(id, e);
if (r >= 0) {
log_info("Initializing machine ID from container UUID.");
return 0;
}
}
}
} else {
/* 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 */
r = detect_vm(&vm_id);
if (r > 0 && streq(vm_id, "kvm")) {
char uuid[37];
fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
if (fd >= 0) {
k = loop_read(fd, uuid, 36, false);
safe_close(fd);
if (k >= 36) {
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) {
log_error("Failed to open /dev/urandom: %s", strerror(-r));
return r;
}
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;
struct stat st;
char id[34]; /* 32 + \n + \0 */
int r;
if (isempty(root)) {
etc_machine_id = "/etc/machine-id";
run_machine_id = "/run/machine-id";
} else {
etc_machine_id = strappenda(root, "/etc/machine-id");
path_kill_slashes((char*) etc_machine_id);
run_machine_id = strappenda(root, "/run/machine-id");
path_kill_slashes((char*) run_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. */
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("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("Cannot open %s: %m", etc_machine_id);
return -errno;
}
writable = false;
}
}
if (fstat(fd, &st) < 0) {
log_error("fstat() failed: %m");
return -errno;
}
if (S_ISREG(st.st_mode))
if (loop_read(fd, id, 33, false) == 33 && id[32] == '\n') {
id[32] = 0;
if (id128_is_valid(id))
return 0;
}
/* Hmm, so, the id currently stored is not useful, then let's
* generate one */
r = generate(id, root);
if (r < 0)
return r;
if (S_ISREG(st.st_mode) && writable) {
lseek(fd, 0, SEEK_SET);
if (loop_write(fd, id, 33, false) == 33)
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);
}
if (r < 0) {
log_error("Cannot write %s: %s", run_machine_id, strerror(-r));
unlink(run_machine_id);
return r;
}
/* And now, let's mount it over */
r = mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL);
if (r < 0) {
log_error("Failed to mount %s: %m", etc_machine_id);
unlink_noerrno(run_machine_id);
return -errno;
}
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("Failed to make transient %s read-only: %m", etc_machine_id);
return 0;
}