247 lines
7.1 KiB
C
247 lines
7.1 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <unistd.h>
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#include <stdio.h>
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#include <errno.h>
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#include <string.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <sys/mount.h>
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#include <systemd/sd-id128.h>
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#include "machine-id-setup.h"
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#include "macro.h"
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#include "util.h"
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#include "mkdir.h"
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#include "log.h"
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#include "virt.h"
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static int shorten_uuid(char destination[36], const char *source) {
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unsigned i, j;
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for (i = 0, j = 0; i < 36 && j < 32; i++) {
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int t;
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t = unhexchar(source[i]);
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if (t < 0)
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continue;
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destination[j++] = hexchar(t);
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}
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if (i == 36 && j == 32) {
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destination[32] = '\n';
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destination[33] = 0;
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return 0;
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}
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return -EINVAL;
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}
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static int generate(char id[34]) {
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int fd, r;
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unsigned char *p;
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sd_id128_t buf;
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char *q;
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ssize_t k;
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const char *vm_id;
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assert(id);
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/* First, try reading the D-Bus machine id, unless it is a symlink */
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fd = open("/var/lib/dbus/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
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if (fd >= 0) {
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k = loop_read(fd, id, 32, false);
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close_nointr_nofail(fd);
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if (k >= 32) {
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id[32] = '\n';
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id[33] = 0;
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log_info("Initializing machine ID from D-Bus machine ID.");
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return 0;
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}
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}
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/* If that didn't work, see if we are running in qemu/kvm and a
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* machine ID was passed in via -uuid on the qemu/kvm command
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* line */
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r = detect_vm(&vm_id);
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if (r > 0 && streq(vm_id, "kvm")) {
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char uuid[37];
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fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
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if (fd >= 0) {
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k = loop_read(fd, uuid, 36, false);
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close_nointr_nofail(fd);
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if (k >= 36) {
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r = shorten_uuid(id, uuid);
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if (r >= 0) {
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log_info("Initializing machine ID from KVM UUID.");
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return 0;
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}
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}
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}
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}
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/* If that didn't work either, see if we are running in a
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* container, and a machine ID was passed in via
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* $container_uuid the way libvirt/LXC does it */
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r = detect_container(NULL);
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if (r > 0) {
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char *e;
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r = getenv_for_pid(1, "container_uuid", &e);
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if (r > 0) {
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if (strlen(e) >= 36) {
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r = shorten_uuid(id, e);
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if (r >= 0) {
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log_info("Initializing machine ID from container UUID.");
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free(e);
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return 0;
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}
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}
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free(e);
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}
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}
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/* If that didn't work, generate a random machine id */
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r = sd_id128_randomize(&buf);
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if (r < 0) {
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log_error("Failed to open /dev/urandom: %s", strerror(-r));
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return r;
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}
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for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) {
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q[0] = hexchar(*p >> 4);
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q[1] = hexchar(*p & 15);
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}
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id[32] = '\n';
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id[33] = 0;
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log_info("Initializing machine ID from random generator.");
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return 0;
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}
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int machine_id_setup(void) {
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int fd, r;
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bool writable;
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struct stat st;
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char id[34]; /* 32 + \n + \0 */
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mode_t m;
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m = umask(0000);
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/* We create this 0444, to indicate that this isn't really
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* something you should ever modify. Of course, since the file
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* will be owned by root it doesn't matter much, but maybe
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* people look. */
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fd = open("/etc/machine-id", O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444);
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if (fd >= 0)
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writable = true;
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else {
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fd = open("/etc/machine-id", O_RDONLY|O_CLOEXEC|O_NOCTTY);
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if (fd < 0) {
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umask(m);
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log_error("Cannot open /etc/machine-id: %m");
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return -errno;
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}
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writable = false;
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}
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umask(m);
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if (fstat(fd, &st) < 0) {
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log_error("fstat() failed: %m");
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r = -errno;
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goto finish;
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}
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if (S_ISREG(st.st_mode)) {
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if (loop_read(fd, id, 32, false) >= 32) {
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r = 0;
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goto finish;
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}
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}
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/* Hmm, so, the id currently stored is not useful, then let's
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* generate one */
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r = generate(id);
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if (r < 0)
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goto finish;
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if (S_ISREG(st.st_mode) && writable) {
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lseek(fd, 0, SEEK_SET);
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if (loop_write(fd, id, 33, false) == 33) {
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r = 0;
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goto finish;
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}
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}
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close_nointr_nofail(fd);
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fd = -1;
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/* Hmm, we couldn't write it? So let's write it to
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* /run/machine-id as a replacement */
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m = umask(0022);
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r = write_one_line_file("/run/machine-id", id);
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umask(m);
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if (r < 0) {
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log_error("Cannot write /run/machine-id: %s", strerror(-r));
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unlink("/run/machine-id");
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goto finish;
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}
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/* And now, let's mount it over */
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r = mount("/run/machine-id", "/etc/machine-id", NULL, MS_BIND, NULL) < 0 ? -errno : 0;
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if (r < 0) {
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unlink("/run/machine-id");
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log_error("Failed to mount /etc/machine-id: %s", strerror(-r));
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} else {
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log_info("Installed transient /etc/machine-id file.");
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/* Mark the mount read-only */
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mount(NULL, "/etc/machine-id", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL);
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}
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finish:
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if (fd >= 0)
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close_nointr_nofail(fd);
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return r;
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}
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