| /*-*- 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 <errno.h> |
| #include <fcntl.h> |
| #include <sched.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <sys/mount.h> |
| #include <unistd.h> |
| |
| #include "sd-id128.h" |
| |
| #include "alloc-util.h" |
| #include "fd-util.h" |
| #include "fileio.h" |
| #include "fs-util.h" |
| #include "hexdecoct.h" |
| #include "io-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 shorten_uuid(char destination[34], const char source[36]) { |
| unsigned i, j; |
| |
| assert(destination); |
| assert(source); |
| |
| /* Converts a UUID into a machine ID, by lowercasing it and |
| * removing dashes. Validates everything. */ |
| |
| 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) |
| return -EINVAL; |
| |
| destination[32] = '\n'; |
| destination[33] = 0; |
| return 0; |
| } |
| |
| static int read_machine_id(int fd, char id[34]) { |
| char id_to_validate[34]; |
| int r; |
| |
| assert(fd >= 0); |
| assert(id); |
| |
| /* Reads a machine ID from a file, validates it, and returns |
| * it. The returned ID ends in a newline. */ |
| |
| r = loop_read_exact(fd, id_to_validate, 33, false); |
| if (r < 0) |
| return r; |
| |
| if (id_to_validate[32] != '\n') |
| return -EINVAL; |
| |
| id_to_validate[32] = 0; |
| |
| if (!id128_is_valid(id_to_validate)) |
| return -EINVAL; |
| |
| memcpy(id, id_to_validate, 32); |
| id[32] = '\n'; |
| id[33] = 0; |
| return 0; |
| } |
| |
| static int write_machine_id(int fd, char id[34]) { |
| assert(fd >= 0); |
| assert(id); |
| |
| if (lseek(fd, 0, SEEK_SET) < 0) |
| return -errno; |
| |
| return loop_write(fd, id, 33, false); |
| } |
| |
| static int generate_machine_id(char id[34], const char *root) { |
| int fd, r; |
| unsigned char *p; |
| sd_id128_t buf; |
| char *q; |
| const char *dbus_machine_id; |
| |
| assert(id); |
| |
| if (isempty(root)) |
| dbus_machine_id = "/var/lib/dbus/machine-id"; |
| else |
| dbus_machine_id = strjoina(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) { |
| r = read_machine_id(fd, id); |
| safe_close(fd); |
| |
| if (r >= 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 */ |
| |
| if (detect_container() > 0) { |
| _cleanup_free_ char *e = NULL; |
| |
| r = getenv_for_pid(1, "container_uuid", &e); |
| if (r > 0) { |
| r = shorten_uuid(id, e); |
| if (r >= 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 */ |
| |
| char uuid[36]; |
| |
| fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); |
| if (fd >= 0) { |
| r = loop_read_exact(fd, uuid, 36, false); |
| safe_close(fd); |
| |
| if (r >= 0) { |
| 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) |
| return log_error_errno(r, "Failed to open /dev/urandom: %m"); |
| |
| 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; |
| char id[34]; /* 32 + \n + \0 */ |
| int r; |
| |
| if (isempty(root)) { |
| etc_machine_id = "/etc/machine-id"; |
| run_machine_id = "/run/machine-id"; |
| } else { |
| char *x; |
| |
| x = strjoina(root, "/etc/machine-id"); |
| etc_machine_id = path_kill_slashes(x); |
| |
| x = strjoina(root, "/run/machine-id"); |
| run_machine_id = path_kill_slashes(x); |
| } |
| |
| 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_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 |
| log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); |
| |
| return -errno; |
| } |
| |
| writable = false; |
| } |
| } |
| |
| if (read_machine_id(fd, id) >= 0) |
| return 0; |
| |
| /* Hmm, so, the id currently stored is not useful, then let's |
| * generate one */ |
| |
| r = generate_machine_id(id, root); |
| if (r < 0) |
| return r; |
| |
| if (writable) |
| if (write_machine_id(fd, id) >= 0) |
| 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, WRITE_STRING_FILE_CREATE); |
| } |
| 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: %m", etc_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; |
| char id[34]; /* 32 + \n + \0 */ |
| int r; |
| |
| if (isempty(root)) |
| etc_machine_id = "/etc/machine-id"; |
| else { |
| char *x; |
| |
| x = strjoina(root, "/etc/machine-id"); |
| etc_machine_id = path_kill_slashes(x); |
| } |
| |
| r = path_is_mount_point(etc_machine_id, 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 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 = read_machine_id(fd, id); |
| if (r < 0) |
| return log_error_errno(r, "We didn't find a valid machine ID in %s.", 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; |
| } |
| |
| 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 */ |
| fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); |
| if (fd < 0) |
| return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id); |
| |
| r = write_machine_id(fd, id); |
| if (r < 0) |
| return log_error_errno(r, "Cannot write %s: %m", etc_machine_id); |
| |
| fd = safe_close(fd); |
| |
| /* 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; |
| } |