| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #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 "io-util.h" |
| #include "log.h" |
| #include "machine-id-setup.h" |
| #include "macro.h" |
| #include "mkdir.h" |
| #include "mount-util.h" |
| #include "mountpoint-util.h" |
| #include "namespace-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) && running_in_chroot() <= 0) { |
| /* 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 (IN_SET(detect_vm(), VIRTUALIZATION_KVM, VIRTUALIZATION_AMAZON, VIRTUALIZATION_QEMU)) { |
| |
| /* If we are not running in a container, see if we are running in a VM that provides |
| * a system UUID via the SMBIOS/DMI interfaces. Such environments include QEMU/KVM |
| * with the -uuid on the qemu command line or the Amazon EC2 Nitro hypervisor. */ |
| |
| if (id128_get_product(ret) >= 0) { |
| log_info("Initializing machine ID from VM 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 machine ID: %m"); |
| |
| log_info("Initializing machine ID from random generator."); |
| return 0; |
| } |
| |
| int machine_id_setup(const char *root, bool force_transient, 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 the caller requested a transient machine-id, write the string "uninitialized\n" to |
| * disk and overmount it with a transient file. |
| * |
| * Otherwise write the machine-id directly to disk. */ |
| if (force_transient) { |
| r = loop_write(fd, "uninitialized\n", strlen("uninitialized\n"), false); |
| if (r < 0) |
| return log_error_errno(r, "Failed to write uninitialized %s: %m", etc_machine_id); |
| |
| r = fsync_full(fd); |
| if (r < 0) |
| return log_error_errno(r, "Failed to sync %s: %m", etc_machine_id); |
| } else { |
| r = id128_write_fd(fd, ID128_PLAIN, machine_id, true); |
| if (r < 0) |
| return log_error_errno(r, "Failed to write %s: %m", etc_machine_id); |
| else |
| goto finish; |
| } |
| } |
| |
| fd = safe_close(fd); |
| |
| /* Hmm, we couldn't or shouldn't write the machine-id to /etc? |
| * 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 */ |
| r = mount_follow_verbose(LOG_ERR, run_machine_id, etc_machine_id, NULL, MS_BIND, NULL); |
| if (r < 0) { |
| (void) unlink(run_machine_id); |
| return r; |
| } |
| |
| log_full(force_transient ? LOG_DEBUG : LOG_INFO, "Installed transient %s file.", etc_machine_id); |
| |
| /* Mark the mount read-only */ |
| r = mount_follow_verbose(LOG_WARNING, NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL); |
| if (r < 0) |
| return r; |
| |
| 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, *sync_path; |
| sd_id128_t id; |
| int r; |
| |
| /* Before doing anything, sync everything to ensure any changes by first-boot units are persisted. |
| * |
| * First, explicitly sync the file systems we care about and check if it worked. */ |
| FOREACH_STRING(sync_path, "/etc/", "/var/") { |
| r = syncfs_path(AT_FDCWD, sync_path); |
| if (r < 0) |
| return log_error_errno(r, "Cannot sync %s: %m", sync_path); |
| } |
| |
| /* Afterwards, sync() the rest too, but we can't check the return value for these. */ |
| sync(); |
| |
| /* 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) |
| return log_error_errno(SYNTHETIC_ERRNO(EROFS), |
| "%s is not on a temporary file system.", |
| etc_machine_id); |
| |
| 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: %m", 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 */ |
| r = detach_mount_namespace(); |
| if (r < 0) |
| return log_error_errno(r, "Failed to set up new mount namespace: %m"); |
| |
| r = umount_verbose(LOG_ERR, etc_machine_id, 0); |
| if (r < 0) |
| return r; |
| |
| /* 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; |
| } |
