mirror of
https://github.com/systemd/systemd.git
synced 2024-11-07 09:56:51 +03:00
63c372cb9d
After all it is now much more like strjoin() than strappend(). At the same time, add support for NULL sentinels, even if they are normally not necessary.
366 lines
13 KiB
C
366 lines
13 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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#include "fileio.h"
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#include "path-util.h"
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static int shorten_uuid(char destination[34], const char source[36]) {
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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], const char *root) {
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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, *dbus_machine_id;
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assert(id);
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if (isempty(root))
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dbus_machine_id = "/var/lib/dbus/machine-id";
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else
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dbus_machine_id = strjoina(root, "/var/lib/dbus/machine-id");
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/* First, try reading the D-Bus machine id, unless it is a symlink */
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fd = open(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, 33, false);
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safe_close(fd);
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if (k == 33 && id[32] == '\n') {
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id[32] = 0;
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if (id128_is_valid(id)) {
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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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}
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if (isempty(root)) {
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/* If that didn't work, see if we are running in a container,
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* and a machine ID was passed in via $container_uuid the way
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* libvirt/LXC does it */
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r = detect_container(NULL);
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if (r > 0) {
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_cleanup_free_ char *e = NULL;
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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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return 0;
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}
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}
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}
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} else {
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/* If we are not running in a container, see if we are
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* running in qemu/kvm and a machine ID was passed in
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* via -uuid on the qemu/kvm command 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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safe_close(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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}
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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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return log_error_errno(r, "Failed to open /dev/urandom: %m");
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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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static int get_valid_machine_id(int fd, char id[34]) {
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char id_to_validate[34];
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assert(fd >= 0);
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assert(id);
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if (loop_read(fd, id_to_validate, 33, false) == 33 && id_to_validate[32] == '\n') {
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id_to_validate[32] = 0;
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if (id128_is_valid(id_to_validate)) {
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memcpy(id, id_to_validate, 32);
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id[32] = '\n';
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id[33] = 0;
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return 0;
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}
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}
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return -EINVAL;
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}
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static int write_machine_id(int fd, char id[34]) {
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assert(fd >= 0);
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assert(id);
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lseek(fd, 0, SEEK_SET);
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if (loop_write(fd, id, 33, false) == 0)
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return 0;
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return -errno;
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}
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int machine_id_commit(const char *root) {
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_cleanup_close_ int fd = -1, initial_mntns_fd = -1;
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const char *etc_machine_id;
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char id[34]; /* 32 + \n + \0 */
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int r;
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if (isempty(root))
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etc_machine_id = "/etc/machine-id";
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else {
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char *x;
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x = strjoina(root, "/etc/machine-id");
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etc_machine_id = path_kill_slashes(x);
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}
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r = path_is_mount_point(etc_machine_id, false);
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if (r < 0)
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return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id);
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if (r == 0) {
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log_debug("%s is is not a mount point. Nothing to do.", etc_machine_id);
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return 0;
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}
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/* Read existing machine-id */
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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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return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
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r = get_valid_machine_id(fd, id);
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if (r < 0)
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return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id);
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r = is_fd_on_temporary_fs(fd);
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if (r < 0)
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return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id);
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if (r == 0) {
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log_error("%s is not on a temporary file system.", etc_machine_id);
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return -EROFS;
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}
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fd = safe_close(fd);
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/* Store current mount namespace */
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r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL);
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if (r < 0)
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return log_error_errno(r, "Can't fetch current mount namespace: %m");
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/* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */
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if (unshare(CLONE_NEWNS) < 0)
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return log_error_errno(errno, "Failed to enter new namespace: %m");
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if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0)
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return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m");
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if (umount(etc_machine_id) < 0)
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return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id);
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/* Update a persistent version of etc_machine_id */
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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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return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id);
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r = write_machine_id(fd, id);
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if (r < 0)
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return log_error_errno(r, "Cannot write %s: %m", etc_machine_id);
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fd = safe_close(fd);
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/* Return to initial namespace and proceed a lazy tmpfs unmount */
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r = namespace_enter(-1, initial_mntns_fd, -1, -1);
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if (r < 0)
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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);
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if (umount2(etc_machine_id, MNT_DETACH) < 0)
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return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id);
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return 0;
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}
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int machine_id_setup(const char *root) {
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const char *etc_machine_id, *run_machine_id;
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_cleanup_close_ int fd = -1;
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bool writable = true;
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struct stat st;
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char id[34]; /* 32 + \n + \0 */
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int r;
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if (isempty(root)) {
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etc_machine_id = "/etc/machine-id";
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run_machine_id = "/run/machine-id";
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} else {
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char *x;
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x = strjoina(root, "/etc/machine-id");
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etc_machine_id = path_kill_slashes(x);
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x = strjoina(root, "/run/machine-id");
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run_machine_id = path_kill_slashes(x);
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}
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RUN_WITH_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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mkdir_parents(etc_machine_id, 0755);
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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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int old_errno = errno;
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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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if (old_errno == EROFS && errno == ENOENT)
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log_error("System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n"
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"Booting up is supported only when:\n"
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"1) /etc/machine-id exists and is populated.\n"
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"2) /etc/machine-id exists and is empty.\n"
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"3) /etc/machine-id is missing and /etc is writable.\n");
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else
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log_error_errno(errno, "Cannot open %s: %m", etc_machine_id);
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return -errno;
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}
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writable = false;
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}
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}
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if (fstat(fd, &st) < 0)
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return log_error_errno(errno, "fstat() failed: %m");
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if (S_ISREG(st.st_mode) && get_valid_machine_id(fd, id) == 0)
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return 0;
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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, root);
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if (r < 0)
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return r;
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if (S_ISREG(st.st_mode) && writable)
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if (write_machine_id(fd, id) == 0)
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return 0;
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fd = safe_close(fd);
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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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RUN_WITH_UMASK(0022) {
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r = write_string_file(run_machine_id, id);
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}
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if (r < 0) {
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log_error_errno(r, "Cannot write %s: %m", run_machine_id);
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unlink(run_machine_id);
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return r;
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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);
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if (r < 0) {
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log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id);
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unlink_noerrno(run_machine_id);
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return -errno;
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}
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log_info("Installed transient %s file.", etc_machine_id);
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/* Mark the mount read-only */
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if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0)
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log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id);
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return 0;
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}
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